1 /* 2 * Copyright (c) 1997, 2016, 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 "opto/valuetypenode.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 Node *parent_ctrl; 575 if( cnt == 0 ) { 576 assert( req() == 1, "no inputs expected" ); 577 // During IGVN phase such region will be subsumed by TOP node 578 // so region's phis will have TOP as control node. 579 // Kill phis here to avoid it. PhiNode::is_copy() will be always false. 580 // Also set other user's input to top. 581 parent_ctrl = phase->C->top(); 582 } else { 583 // The fallthrough case since we already checked dead loops above. 584 parent_ctrl = in(1); 585 assert(parent_ctrl != NULL, "Region is a copy of some non-null control"); 586 assert(!igvn->eqv(parent_ctrl, this), "Close dead loop"); 587 } 588 if (!add_to_worklist) 589 igvn->add_users_to_worklist(this); // Check for further allowed opts 590 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) { 591 Node* n = last_out(i); 592 igvn->hash_delete(n); // Remove from worklist before modifying edges 593 if( n->is_Phi() ) { // Collapse all Phis 594 // Eagerly replace phis to avoid copies generation. 595 Node* in; 596 if( cnt == 0 ) { 597 assert( n->req() == 1, "No data inputs expected" ); 598 in = parent_ctrl; // replaced by top 599 } else { 600 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" ); 601 in = n->in(1); // replaced by unique input 602 if( n->as_Phi()->is_unsafe_data_reference(in) ) 603 in = phase->C->top(); // replaced by top 604 } 605 igvn->replace_node(n, in); 606 } 607 else if( n->is_Region() ) { // Update all incoming edges 608 assert( !igvn->eqv(n, this), "Must be removed from DefUse edges"); 609 uint uses_found = 0; 610 for( uint k=1; k < n->req(); k++ ) { 611 if( n->in(k) == this ) { 612 n->set_req(k, parent_ctrl); 613 uses_found++; 614 } 615 } 616 if( uses_found > 1 ) { // (--i) done at the end of the loop. 617 i -= (uses_found - 1); 618 } 619 } 620 else { 621 assert( igvn->eqv(n->in(0), this), "Expect RegionNode to be control parent"); 622 n->set_req(0, parent_ctrl); 623 } 624 #ifdef ASSERT 625 for( uint k=0; k < n->req(); k++ ) { 626 assert( !igvn->eqv(n->in(k), this), "All uses of RegionNode should be gone"); 627 } 628 #endif 629 } 630 // Remove the RegionNode itself from DefUse info 631 igvn->remove_dead_node(this); 632 return NULL; 633 } 634 return this; // Record progress 635 } 636 637 638 // If a Region flows into a Region, merge into one big happy merge. 639 if (can_reshape) { 640 Node *m = merge_region(this, phase); 641 if (m != NULL) return m; 642 } 643 644 // Check if this region is the root of a clipping idiom on floats 645 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) { 646 // Check that only one use is a Phi and that it simplifies to two constants + 647 PhiNode* phi = has_unique_phi(); 648 if (phi != NULL) { // One Phi user 649 // Check inputs to the Phi 650 ConNode *min; 651 ConNode *max; 652 Node *val; 653 uint min_idx; 654 uint max_idx; 655 uint val_idx; 656 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) { 657 IfNode *top_if; 658 IfNode *bot_if; 659 if( check_if_clipping( this, bot_if, top_if ) ) { 660 // Control pattern checks, now verify compares 661 Node *top_in = NULL; // value being compared against 662 Node *bot_in = NULL; 663 if( check_compare_clipping( true, bot_if, min, bot_in ) && 664 check_compare_clipping( false, top_if, max, top_in ) ) { 665 if( bot_in == top_in ) { 666 PhaseIterGVN *gvn = phase->is_IterGVN(); 667 assert( gvn != NULL, "Only had DefUse info in IterGVN"); 668 // Only remaining check is that bot_in == top_in == (Phi's val + mods) 669 670 // Check for the ConvF2INode 671 ConvF2INode *convf2i; 672 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) && 673 convf2i->in(1) == bot_in ) { 674 // Matched pattern, including LShiftI; RShiftI, replace with integer compares 675 // max test 676 Node *cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, min )); 677 Node *boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::lt )); 678 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt )); 679 Node *if_min= gvn->register_new_node_with_optimizer(new IfTrueNode (iff)); 680 Node *ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff)); 681 // min test 682 cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, max )); 683 boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::gt )); 684 iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt )); 685 Node *if_max= gvn->register_new_node_with_optimizer(new IfTrueNode (iff)); 686 ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff)); 687 // update input edges to region node 688 set_req_X( min_idx, if_min, gvn ); 689 set_req_X( max_idx, if_max, gvn ); 690 set_req_X( val_idx, ifF, gvn ); 691 // remove unnecessary 'LShiftI; RShiftI' idiom 692 gvn->hash_delete(phi); 693 phi->set_req_X( val_idx, convf2i, gvn ); 694 gvn->hash_find_insert(phi); 695 // Return transformed region node 696 return this; 697 } 698 } 699 } 700 } 701 } 702 } 703 } 704 705 return modified ? this : NULL; 706 } 707 708 709 710 const RegMask &RegionNode::out_RegMask() const { 711 return RegMask::Empty; 712 } 713 714 // Find the one non-null required input. RegionNode only 715 Node *Node::nonnull_req() const { 716 assert( is_Region(), "" ); 717 for( uint i = 1; i < _cnt; i++ ) 718 if( in(i) ) 719 return in(i); 720 ShouldNotReachHere(); 721 return NULL; 722 } 723 724 725 //============================================================================= 726 // note that these functions assume that the _adr_type field is flattened 727 uint PhiNode::hash() const { 728 const Type* at = _adr_type; 729 return TypeNode::hash() + (at ? at->hash() : 0); 730 } 731 uint PhiNode::cmp( const Node &n ) const { 732 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type; 733 } 734 static inline 735 const TypePtr* flatten_phi_adr_type(const TypePtr* at) { 736 if (at == NULL || at == TypePtr::BOTTOM) return at; 737 return Compile::current()->alias_type(at)->adr_type(); 738 } 739 740 //----------------------------make--------------------------------------------- 741 // create a new phi with edges matching r and set (initially) to x 742 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) { 743 uint preds = r->req(); // Number of predecessor paths 744 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at"); 745 PhiNode* p = new PhiNode(r, t, at); 746 for (uint j = 1; j < preds; j++) { 747 // Fill in all inputs, except those which the region does not yet have 748 if (r->in(j) != NULL) 749 p->init_req(j, x); 750 } 751 return p; 752 } 753 PhiNode* PhiNode::make(Node* r, Node* x) { 754 const Type* t = x->bottom_type(); 755 const TypePtr* at = NULL; 756 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type()); 757 return make(r, x, t, at); 758 } 759 PhiNode* PhiNode::make_blank(Node* r, Node* x) { 760 const Type* t = x->bottom_type(); 761 const TypePtr* at = NULL; 762 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type()); 763 return new PhiNode(r, t, at); 764 } 765 766 767 //------------------------slice_memory----------------------------------------- 768 // create a new phi with narrowed memory type 769 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const { 770 PhiNode* mem = (PhiNode*) clone(); 771 *(const TypePtr**)&mem->_adr_type = adr_type; 772 // convert self-loops, or else we get a bad graph 773 for (uint i = 1; i < req(); i++) { 774 if ((const Node*)in(i) == this) mem->set_req(i, mem); 775 } 776 mem->verify_adr_type(); 777 return mem; 778 } 779 780 //------------------------split_out_instance----------------------------------- 781 // Split out an instance type from a bottom phi. 782 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const { 783 const TypeOopPtr *t_oop = at->isa_oopptr(); 784 assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr"); 785 const TypePtr *t = adr_type(); 786 assert(type() == Type::MEMORY && 787 (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM || 788 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() && 789 t->is_oopptr()->cast_to_exactness(true) 790 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr()) 791 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop), 792 "bottom or raw memory required"); 793 794 // Check if an appropriate node already exists. 795 Node *region = in(0); 796 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) { 797 Node* use = region->fast_out(k); 798 if( use->is_Phi()) { 799 PhiNode *phi2 = use->as_Phi(); 800 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) { 801 return phi2; 802 } 803 } 804 } 805 Compile *C = igvn->C; 806 Arena *a = Thread::current()->resource_area(); 807 Node_Array node_map = new Node_Array(a); 808 Node_Stack stack(a, C->live_nodes() >> 4); 809 PhiNode *nphi = slice_memory(at); 810 igvn->register_new_node_with_optimizer( nphi ); 811 node_map.map(_idx, nphi); 812 stack.push((Node *)this, 1); 813 while(!stack.is_empty()) { 814 PhiNode *ophi = stack.node()->as_Phi(); 815 uint i = stack.index(); 816 assert(i >= 1, "not control edge"); 817 stack.pop(); 818 nphi = node_map[ophi->_idx]->as_Phi(); 819 for (; i < ophi->req(); i++) { 820 Node *in = ophi->in(i); 821 if (in == NULL || igvn->type(in) == Type::TOP) 822 continue; 823 Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, NULL, igvn); 824 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL; 825 if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) { 826 opt = node_map[optphi->_idx]; 827 if (opt == NULL) { 828 stack.push(ophi, i); 829 nphi = optphi->slice_memory(at); 830 igvn->register_new_node_with_optimizer( nphi ); 831 node_map.map(optphi->_idx, nphi); 832 ophi = optphi; 833 i = 0; // will get incremented at top of loop 834 continue; 835 } 836 } 837 nphi->set_req(i, opt); 838 } 839 } 840 return nphi; 841 } 842 843 //------------------------verify_adr_type-------------------------------------- 844 #ifdef ASSERT 845 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const { 846 if (visited.test_set(_idx)) return; //already visited 847 848 // recheck constructor invariants: 849 verify_adr_type(false); 850 851 // recheck local phi/phi consistency: 852 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM, 853 "adr_type must be consistent across phi nest"); 854 855 // walk around 856 for (uint i = 1; i < req(); i++) { 857 Node* n = in(i); 858 if (n == NULL) continue; 859 const Node* np = in(i); 860 if (np->is_Phi()) { 861 np->as_Phi()->verify_adr_type(visited, at); 862 } else if (n->bottom_type() == Type::TOP 863 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) { 864 // ignore top inputs 865 } else { 866 const TypePtr* nat = flatten_phi_adr_type(n->adr_type()); 867 // recheck phi/non-phi consistency at leaves: 868 assert((nat != NULL) == (at != NULL), ""); 869 assert(nat == at || nat == TypePtr::BOTTOM, 870 "adr_type must be consistent at leaves of phi nest"); 871 } 872 } 873 } 874 875 // Verify a whole nest of phis rooted at this one. 876 void PhiNode::verify_adr_type(bool recursive) const { 877 if (is_error_reported()) return; // muzzle asserts when debugging an error 878 if (Node::in_dump()) return; // muzzle asserts when printing 879 880 assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only"); 881 882 if (!VerifyAliases) return; // verify thoroughly only if requested 883 884 assert(_adr_type == flatten_phi_adr_type(_adr_type), 885 "Phi::adr_type must be pre-normalized"); 886 887 if (recursive) { 888 VectorSet visited(Thread::current()->resource_area()); 889 verify_adr_type(visited, _adr_type); 890 } 891 } 892 #endif 893 894 895 //------------------------------Value------------------------------------------ 896 // Compute the type of the PhiNode 897 const Type* PhiNode::Value(PhaseGVN* phase) const { 898 Node *r = in(0); // RegionNode 899 if( !r ) // Copy or dead 900 return in(1) ? phase->type(in(1)) : Type::TOP; 901 902 // Note: During parsing, phis are often transformed before their regions. 903 // This means we have to use type_or_null to defend against untyped regions. 904 if( phase->type_or_null(r) == Type::TOP ) // Dead code? 905 return Type::TOP; 906 907 // Check for trip-counted loop. If so, be smarter. 908 CountedLoopNode* l = r->is_CountedLoop() ? r->as_CountedLoop() : NULL; 909 if (l && ((const Node*)l->phi() == this)) { // Trip counted loop! 910 // protect against init_trip() or limit() returning NULL 911 if (l->can_be_counted_loop(phase)) { 912 const Node *init = l->init_trip(); 913 const Node *limit = l->limit(); 914 const Node* stride = l->stride(); 915 if (init != NULL && limit != NULL && stride != NULL) { 916 const TypeInt* lo = phase->type(init)->isa_int(); 917 const TypeInt* hi = phase->type(limit)->isa_int(); 918 const TypeInt* stride_t = phase->type(stride)->isa_int(); 919 if (lo != NULL && hi != NULL && stride_t != NULL) { // Dying loops might have TOP here 920 assert(stride_t->_hi >= stride_t->_lo, "bad stride type"); 921 if (stride_t->_hi < 0) { // Down-counter loop 922 swap(lo, hi); 923 return TypeInt::make(MIN2(lo->_lo, hi->_lo) , hi->_hi, 3); 924 } else if (stride_t->_lo >= 0) { 925 return TypeInt::make(lo->_lo, MAX2(lo->_hi, hi->_hi), 3); 926 } 927 } 928 } 929 } else if (l->in(LoopNode::LoopBackControl) != NULL && 930 in(LoopNode::EntryControl) != NULL && 931 phase->type(l->in(LoopNode::LoopBackControl)) == Type::TOP) { 932 // During CCP, if we saturate the type of a counted loop's Phi 933 // before the special code for counted loop above has a chance 934 // to run (that is as long as the type of the backedge's control 935 // is top), we might end up with non monotonic types 936 return phase->type(in(LoopNode::EntryControl)); 937 } 938 } 939 940 // Until we have harmony between classes and interfaces in the type 941 // lattice, we must tread carefully around phis which implicitly 942 // convert the one to the other. 943 const TypePtr* ttp = _type->make_ptr(); 944 const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL; 945 const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_klassptr() : NULL; 946 bool is_intf = false; 947 if (ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) { 948 is_intf = true; 949 } else if (ttkp != NULL && ttkp->is_loaded() && ttkp->klass()->is_interface()) { 950 is_intf = true; 951 } 952 953 // Default case: merge all inputs 954 const Type *t = Type::TOP; // Merged type starting value 955 for (uint i = 1; i < req(); ++i) {// For all paths in 956 // Reachable control path? 957 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) { 958 const Type* ti = phase->type(in(i)); 959 // We assume that each input of an interface-valued Phi is a true 960 // subtype of that interface. This might not be true of the meet 961 // of all the input types. The lattice is not distributive in 962 // such cases. Ward off asserts in type.cpp by refusing to do 963 // meets between interfaces and proper classes. 964 const TypePtr* tip = ti->make_ptr(); 965 const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL; 966 if (tiip) { 967 bool ti_is_intf = false; 968 ciKlass* k = tiip->klass(); 969 if (k->is_loaded() && k->is_interface()) 970 ti_is_intf = true; 971 if (is_intf != ti_is_intf) 972 { t = _type; break; } 973 } 974 t = t->meet_speculative(ti); 975 } 976 } 977 978 // The worst-case type (from ciTypeFlow) should be consistent with "t". 979 // That is, we expect that "t->higher_equal(_type)" holds true. 980 // There are various exceptions: 981 // - Inputs which are phis might in fact be widened unnecessarily. 982 // For example, an input might be a widened int while the phi is a short. 983 // - Inputs might be BotPtrs but this phi is dependent on a null check, 984 // and postCCP has removed the cast which encodes the result of the check. 985 // - The type of this phi is an interface, and the inputs are classes. 986 // - Value calls on inputs might produce fuzzy results. 987 // (Occurrences of this case suggest improvements to Value methods.) 988 // 989 // It is not possible to see Type::BOTTOM values as phi inputs, 990 // because the ciTypeFlow pre-pass produces verifier-quality types. 991 const Type* ft = t->filter_speculative(_type); // Worst case type 992 993 #ifdef ASSERT 994 // The following logic has been moved into TypeOopPtr::filter. 995 const Type* jt = t->join_speculative(_type); 996 if (jt->empty()) { // Emptied out??? 997 998 // Check for evil case of 't' being a class and '_type' expecting an 999 // interface. This can happen because the bytecodes do not contain 1000 // enough type info to distinguish a Java-level interface variable 1001 // from a Java-level object variable. If we meet 2 classes which 1002 // both implement interface I, but their meet is at 'j/l/O' which 1003 // doesn't implement I, we have no way to tell if the result should 1004 // be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows 1005 // into a Phi which "knows" it's an Interface type we'll have to 1006 // uplift the type. 1007 if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) { 1008 assert(ft == _type, ""); // Uplift to interface 1009 } else if (!t->empty() && ttkp != NULL && ttkp->is_loaded() && ttkp->klass()->is_interface()) { 1010 assert(ft == _type, ""); // Uplift to interface 1011 } else { 1012 // We also have to handle 'evil cases' of interface- vs. class-arrays 1013 Type::get_arrays_base_elements(jt, _type, NULL, &ttip); 1014 if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) { 1015 assert(ft == _type, ""); // Uplift to array of interface 1016 } else { 1017 // Otherwise it's something stupid like non-overlapping int ranges 1018 // found on dying counted loops. 1019 assert(ft == Type::TOP, ""); // Canonical empty value 1020 } 1021 } 1022 } 1023 1024 else { 1025 1026 // If we have an interface-typed Phi and we narrow to a class type, the join 1027 // should report back the class. However, if we have a J/L/Object 1028 // class-typed Phi and an interface flows in, it's possible that the meet & 1029 // join report an interface back out. This isn't possible but happens 1030 // because the type system doesn't interact well with interfaces. 1031 const TypePtr *jtp = jt->make_ptr(); 1032 const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL; 1033 const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_klassptr() : NULL; 1034 if( jtip && ttip ) { 1035 if( jtip->is_loaded() && jtip->klass()->is_interface() && 1036 ttip->is_loaded() && !ttip->klass()->is_interface() ) { 1037 assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) || 1038 ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), ""); 1039 jt = ft; 1040 } 1041 } 1042 if( jtkp && ttkp ) { 1043 if( jtkp->is_loaded() && jtkp->klass()->is_interface() && 1044 !jtkp->klass_is_exact() && // Keep exact interface klass (6894807) 1045 ttkp->is_loaded() && !ttkp->klass()->is_interface() ) { 1046 assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) || 1047 ft->isa_narrowklass() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), ""); 1048 jt = ft; 1049 } 1050 } 1051 if (jt != ft && jt->base() == ft->base()) { 1052 if (jt->isa_int() && 1053 jt->is_int()->_lo == ft->is_int()->_lo && 1054 jt->is_int()->_hi == ft->is_int()->_hi) 1055 jt = ft; 1056 if (jt->isa_long() && 1057 jt->is_long()->_lo == ft->is_long()->_lo && 1058 jt->is_long()->_hi == ft->is_long()->_hi) 1059 jt = ft; 1060 } 1061 if (jt != ft) { 1062 tty->print("merge type: "); t->dump(); tty->cr(); 1063 tty->print("kill type: "); _type->dump(); tty->cr(); 1064 tty->print("join type: "); jt->dump(); tty->cr(); 1065 tty->print("filter type: "); ft->dump(); tty->cr(); 1066 } 1067 assert(jt == ft, ""); 1068 } 1069 #endif //ASSERT 1070 1071 // Deal with conversion problems found in data loops. 1072 ft = phase->saturate(ft, phase->type_or_null(this), _type); 1073 1074 return ft; 1075 } 1076 1077 1078 //------------------------------is_diamond_phi--------------------------------- 1079 // Does this Phi represent a simple well-shaped diamond merge? Return the 1080 // index of the true path or 0 otherwise. 1081 // If check_control_only is true, do not inspect the If node at the 1082 // top, and return -1 (not an edge number) on success. 1083 int PhiNode::is_diamond_phi(bool check_control_only) const { 1084 // Check for a 2-path merge 1085 Node *region = in(0); 1086 if( !region ) return 0; 1087 if( region->req() != 3 ) return 0; 1088 if( req() != 3 ) return 0; 1089 // Check that both paths come from the same If 1090 Node *ifp1 = region->in(1); 1091 Node *ifp2 = region->in(2); 1092 if( !ifp1 || !ifp2 ) return 0; 1093 Node *iff = ifp1->in(0); 1094 if( !iff || !iff->is_If() ) return 0; 1095 if( iff != ifp2->in(0) ) return 0; 1096 if (check_control_only) return -1; 1097 // Check for a proper bool/cmp 1098 const Node *b = iff->in(1); 1099 if( !b->is_Bool() ) return 0; 1100 const Node *cmp = b->in(1); 1101 if( !cmp->is_Cmp() ) return 0; 1102 1103 // Check for branching opposite expected 1104 if( ifp2->Opcode() == Op_IfTrue ) { 1105 assert( ifp1->Opcode() == Op_IfFalse, "" ); 1106 return 2; 1107 } else { 1108 assert( ifp1->Opcode() == Op_IfTrue, "" ); 1109 return 1; 1110 } 1111 } 1112 1113 //----------------------------check_cmove_id----------------------------------- 1114 // Check for CMove'ing a constant after comparing against the constant. 1115 // Happens all the time now, since if we compare equality vs a constant in 1116 // the parser, we "know" the variable is constant on one path and we force 1117 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a 1118 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more 1119 // general in that we don't need constants. Since CMove's are only inserted 1120 // in very special circumstances, we do it here on generic Phi's. 1121 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) { 1122 assert(true_path !=0, "only diamond shape graph expected"); 1123 1124 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1125 // phi->region->if_proj->ifnode->bool->cmp 1126 Node* region = in(0); 1127 Node* iff = region->in(1)->in(0); 1128 BoolNode* b = iff->in(1)->as_Bool(); 1129 Node* cmp = b->in(1); 1130 Node* tval = in(true_path); 1131 Node* fval = in(3-true_path); 1132 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b); 1133 if (id == NULL) 1134 return NULL; 1135 1136 // Either value might be a cast that depends on a branch of 'iff'. 1137 // Since the 'id' value will float free of the diamond, either 1138 // decast or return failure. 1139 Node* ctl = id->in(0); 1140 if (ctl != NULL && ctl->in(0) == iff) { 1141 if (id->is_ConstraintCast()) { 1142 return id->in(1); 1143 } else { 1144 // Don't know how to disentangle this value. 1145 return NULL; 1146 } 1147 } 1148 1149 return id; 1150 } 1151 1152 //------------------------------Identity--------------------------------------- 1153 // Check for Region being Identity. 1154 Node* PhiNode::Identity(PhaseGVN* phase) { 1155 // Check for no merging going on 1156 // (There used to be special-case code here when this->region->is_Loop. 1157 // It would check for a tributary phi on the backedge that the main phi 1158 // trivially, perhaps with a single cast. The unique_input method 1159 // does all this and more, by reducing such tributaries to 'this'.) 1160 Node* uin = unique_input(phase, false); 1161 if (uin != NULL) { 1162 return uin; 1163 } 1164 1165 int true_path = is_diamond_phi(); 1166 if (true_path != 0) { 1167 Node* id = is_cmove_id(phase, true_path); 1168 if (id != NULL) return id; 1169 } 1170 1171 return this; // No identity 1172 } 1173 1174 //-----------------------------unique_input------------------------------------ 1175 // Find the unique value, discounting top, self-loops, and casts. 1176 // Return top if there are no inputs, and self if there are multiple. 1177 Node* PhiNode::unique_input(PhaseTransform* phase, bool uncast) { 1178 // 1) One unique direct input, 1179 // or if uncast is true: 1180 // 2) some of the inputs have an intervening ConstraintCast 1181 // 3) an input is a self loop 1182 // 1183 // 1) input or 2) input or 3) input __ 1184 // / \ / \ \ / \ 1185 // \ / | cast phi cast 1186 // phi \ / / \ / 1187 // phi / -- 1188 1189 Node* r = in(0); // RegionNode 1190 if (r == NULL) return in(1); // Already degraded to a Copy 1191 Node* input = NULL; // The unique direct input (maybe uncasted = ConstraintCasts removed) 1192 1193 for (uint i = 1, cnt = req(); i < cnt; ++i) { 1194 Node* rc = r->in(i); 1195 if (rc == NULL || phase->type(rc) == Type::TOP) 1196 continue; // ignore unreachable control path 1197 Node* n = in(i); 1198 if (n == NULL) 1199 continue; 1200 Node* un = n; 1201 if (uncast) { 1202 #ifdef ASSERT 1203 Node* m = un->uncast(); 1204 #endif 1205 while (un != NULL && un->req() == 2 && un->is_ConstraintCast()) { 1206 Node* next = un->in(1); 1207 if (phase->type(next)->isa_rawptr() && phase->type(un)->isa_oopptr()) { 1208 // risk exposing raw ptr at safepoint 1209 break; 1210 } 1211 un = next; 1212 } 1213 assert(m == un || un->in(1) == m, "Only expected at CheckCastPP from allocation"); 1214 } 1215 if (un == NULL || un == this || phase->type(un) == Type::TOP) { 1216 continue; // ignore if top, or in(i) and "this" are in a data cycle 1217 } 1218 // Check for a unique input (maybe uncasted) 1219 if (input == NULL) { 1220 input = un; 1221 } else if (input != un) { 1222 input = NodeSentinel; // no unique input 1223 } 1224 } 1225 if (input == NULL) { 1226 return phase->C->top(); // no inputs 1227 } 1228 1229 if (input != NodeSentinel) { 1230 return input; // one unique direct input 1231 } 1232 1233 // Nothing. 1234 return NULL; 1235 } 1236 1237 //------------------------------is_x2logic------------------------------------- 1238 // Check for simple convert-to-boolean pattern 1239 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1) 1240 // Convert Phi to an ConvIB. 1241 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) { 1242 assert(true_path !=0, "only diamond shape graph expected"); 1243 // Convert the true/false index into an expected 0/1 return. 1244 // Map 2->0 and 1->1. 1245 int flipped = 2-true_path; 1246 1247 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1248 // phi->region->if_proj->ifnode->bool->cmp 1249 Node *region = phi->in(0); 1250 Node *iff = region->in(1)->in(0); 1251 BoolNode *b = (BoolNode*)iff->in(1); 1252 const CmpNode *cmp = (CmpNode*)b->in(1); 1253 1254 Node *zero = phi->in(1); 1255 Node *one = phi->in(2); 1256 const Type *tzero = phase->type( zero ); 1257 const Type *tone = phase->type( one ); 1258 1259 // Check for compare vs 0 1260 const Type *tcmp = phase->type(cmp->in(2)); 1261 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) { 1262 // Allow cmp-vs-1 if the other input is bounded by 0-1 1263 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) ) 1264 return NULL; 1265 flipped = 1-flipped; // Test is vs 1 instead of 0! 1266 } 1267 1268 // Check for setting zero/one opposite expected 1269 if( tzero == TypeInt::ZERO ) { 1270 if( tone == TypeInt::ONE ) { 1271 } else return NULL; 1272 } else if( tzero == TypeInt::ONE ) { 1273 if( tone == TypeInt::ZERO ) { 1274 flipped = 1-flipped; 1275 } else return NULL; 1276 } else return NULL; 1277 1278 // Check for boolean test backwards 1279 if( b->_test._test == BoolTest::ne ) { 1280 } else if( b->_test._test == BoolTest::eq ) { 1281 flipped = 1-flipped; 1282 } else return NULL; 1283 1284 // Build int->bool conversion 1285 Node *n = new Conv2BNode( cmp->in(1) ); 1286 if( flipped ) 1287 n = new XorINode( phase->transform(n), phase->intcon(1) ); 1288 1289 return n; 1290 } 1291 1292 //------------------------------is_cond_add------------------------------------ 1293 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;" 1294 // To be profitable the control flow has to disappear; there can be no other 1295 // values merging here. We replace the test-and-branch with: 1296 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by 1297 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'. 1298 // Then convert Y to 0-or-Y and finally add. 1299 // This is a key transform for SpecJava _201_compress. 1300 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) { 1301 assert(true_path !=0, "only diamond shape graph expected"); 1302 1303 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1304 // phi->region->if_proj->ifnode->bool->cmp 1305 RegionNode *region = (RegionNode*)phi->in(0); 1306 Node *iff = region->in(1)->in(0); 1307 BoolNode* b = iff->in(1)->as_Bool(); 1308 const CmpNode *cmp = (CmpNode*)b->in(1); 1309 1310 // Make sure only merging this one phi here 1311 if (region->has_unique_phi() != phi) return NULL; 1312 1313 // Make sure each arm of the diamond has exactly one output, which we assume 1314 // is the region. Otherwise, the control flow won't disappear. 1315 if (region->in(1)->outcnt() != 1) return NULL; 1316 if (region->in(2)->outcnt() != 1) return NULL; 1317 1318 // Check for "(P < Q)" of type signed int 1319 if (b->_test._test != BoolTest::lt) return NULL; 1320 if (cmp->Opcode() != Op_CmpI) return NULL; 1321 1322 Node *p = cmp->in(1); 1323 Node *q = cmp->in(2); 1324 Node *n1 = phi->in( true_path); 1325 Node *n2 = phi->in(3-true_path); 1326 1327 int op = n1->Opcode(); 1328 if( op != Op_AddI // Need zero as additive identity 1329 /*&&op != Op_SubI && 1330 op != Op_AddP && 1331 op != Op_XorI && 1332 op != Op_OrI*/ ) 1333 return NULL; 1334 1335 Node *x = n2; 1336 Node *y = NULL; 1337 if( x == n1->in(1) ) { 1338 y = n1->in(2); 1339 } else if( x == n1->in(2) ) { 1340 y = n1->in(1); 1341 } else return NULL; 1342 1343 // Not so profitable if compare and add are constants 1344 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() ) 1345 return NULL; 1346 1347 Node *cmplt = phase->transform( new CmpLTMaskNode(p,q) ); 1348 Node *j_and = phase->transform( new AndINode(cmplt,y) ); 1349 return new AddINode(j_and,x); 1350 } 1351 1352 //------------------------------is_absolute------------------------------------ 1353 // Check for absolute value. 1354 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) { 1355 assert(true_path !=0, "only diamond shape graph expected"); 1356 1357 int cmp_zero_idx = 0; // Index of compare input where to look for zero 1358 int phi_x_idx = 0; // Index of phi input where to find naked x 1359 1360 // ABS ends with the merge of 2 control flow paths. 1361 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely. 1362 int false_path = 3 - true_path; 1363 1364 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1365 // phi->region->if_proj->ifnode->bool->cmp 1366 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool(); 1367 1368 // Check bool sense 1369 switch( bol->_test._test ) { 1370 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break; 1371 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break; 1372 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break; 1373 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break; 1374 default: return NULL; break; 1375 } 1376 1377 // Test is next 1378 Node *cmp = bol->in(1); 1379 const Type *tzero = NULL; 1380 switch( cmp->Opcode() ) { 1381 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS 1382 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS 1383 default: return NULL; 1384 } 1385 1386 // Find zero input of compare; the other input is being abs'd 1387 Node *x = NULL; 1388 bool flip = false; 1389 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) { 1390 x = cmp->in(3 - cmp_zero_idx); 1391 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) { 1392 // The test is inverted, we should invert the result... 1393 x = cmp->in(cmp_zero_idx); 1394 flip = true; 1395 } else { 1396 return NULL; 1397 } 1398 1399 // Next get the 2 pieces being selected, one is the original value 1400 // and the other is the negated value. 1401 if( phi_root->in(phi_x_idx) != x ) return NULL; 1402 1403 // Check other phi input for subtract node 1404 Node *sub = phi_root->in(3 - phi_x_idx); 1405 1406 // Allow only Sub(0,X) and fail out for all others; Neg is not OK 1407 if( tzero == TypeF::ZERO ) { 1408 if( sub->Opcode() != Op_SubF || 1409 sub->in(2) != x || 1410 phase->type(sub->in(1)) != tzero ) return NULL; 1411 x = new AbsFNode(x); 1412 if (flip) { 1413 x = new SubFNode(sub->in(1), phase->transform(x)); 1414 } 1415 } else { 1416 if( sub->Opcode() != Op_SubD || 1417 sub->in(2) != x || 1418 phase->type(sub->in(1)) != tzero ) return NULL; 1419 x = new AbsDNode(x); 1420 if (flip) { 1421 x = new SubDNode(sub->in(1), phase->transform(x)); 1422 } 1423 } 1424 1425 return x; 1426 } 1427 1428 //------------------------------split_once------------------------------------- 1429 // Helper for split_flow_path 1430 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) { 1431 igvn->hash_delete(n); // Remove from hash before hacking edges 1432 1433 uint j = 1; 1434 for (uint i = phi->req()-1; i > 0; i--) { 1435 if (phi->in(i) == val) { // Found a path with val? 1436 // Add to NEW Region/Phi, no DU info 1437 newn->set_req( j++, n->in(i) ); 1438 // Remove from OLD Region/Phi 1439 n->del_req(i); 1440 } 1441 } 1442 1443 // Register the new node but do not transform it. Cannot transform until the 1444 // entire Region/Phi conglomerate has been hacked as a single huge transform. 1445 igvn->register_new_node_with_optimizer( newn ); 1446 1447 // Now I can point to the new node. 1448 n->add_req(newn); 1449 igvn->_worklist.push(n); 1450 } 1451 1452 //------------------------------split_flow_path-------------------------------- 1453 // Check for merging identical values and split flow paths 1454 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) { 1455 BasicType bt = phi->type()->basic_type(); 1456 if( bt == T_ILLEGAL || type2size[bt] <= 0 ) 1457 return NULL; // Bail out on funny non-value stuff 1458 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a 1459 return NULL; // third unequal input to be worth doing 1460 1461 // Scan for a constant 1462 uint i; 1463 for( i = 1; i < phi->req()-1; i++ ) { 1464 Node *n = phi->in(i); 1465 if( !n ) return NULL; 1466 if( phase->type(n) == Type::TOP ) return NULL; 1467 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN || n->Opcode() == Op_ConNKlass ) 1468 break; 1469 } 1470 if( i >= phi->req() ) // Only split for constants 1471 return NULL; 1472 1473 Node *val = phi->in(i); // Constant to split for 1474 uint hit = 0; // Number of times it occurs 1475 Node *r = phi->region(); 1476 1477 for( ; i < phi->req(); i++ ){ // Count occurrences of constant 1478 Node *n = phi->in(i); 1479 if( !n ) return NULL; 1480 if( phase->type(n) == Type::TOP ) return NULL; 1481 if( phi->in(i) == val ) { 1482 hit++; 1483 if (PhaseIdealLoop::find_predicate(r->in(i)) != NULL) { 1484 return NULL; // don't split loop entry path 1485 } 1486 } 1487 } 1488 1489 if( hit <= 1 || // Make sure we find 2 or more 1490 hit == phi->req()-1 ) // and not ALL the same value 1491 return NULL; 1492 1493 // Now start splitting out the flow paths that merge the same value. 1494 // Split first the RegionNode. 1495 PhaseIterGVN *igvn = phase->is_IterGVN(); 1496 RegionNode *newr = new RegionNode(hit+1); 1497 split_once(igvn, phi, val, r, newr); 1498 1499 // Now split all other Phis than this one 1500 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) { 1501 Node* phi2 = r->fast_out(k); 1502 if( phi2->is_Phi() && phi2->as_Phi() != phi ) { 1503 PhiNode *newphi = PhiNode::make_blank(newr, phi2); 1504 split_once(igvn, phi, val, phi2, newphi); 1505 } 1506 } 1507 1508 // Clean up this guy 1509 igvn->hash_delete(phi); 1510 for( i = phi->req()-1; i > 0; i-- ) { 1511 if( phi->in(i) == val ) { 1512 phi->del_req(i); 1513 } 1514 } 1515 phi->add_req(val); 1516 1517 return phi; 1518 } 1519 1520 //============================================================================= 1521 //------------------------------simple_data_loop_check------------------------- 1522 // Try to determining if the phi node in a simple safe/unsafe data loop. 1523 // Returns: 1524 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop }; 1525 // Safe - safe case when the phi and it's inputs reference only safe data 1526 // nodes; 1527 // Unsafe - the phi and it's inputs reference unsafe data nodes but there 1528 // is no reference back to the phi - need a graph walk 1529 // to determine if it is in a loop; 1530 // UnsafeLoop - unsafe case when the phi references itself directly or through 1531 // unsafe data node. 1532 // Note: a safe data node is a node which could/never reference itself during 1533 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP. 1534 // I mark Phi nodes as safe node not only because they can reference itself 1535 // but also to prevent mistaking the fallthrough case inside an outer loop 1536 // as dead loop when the phi references itselfs through an other phi. 1537 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const { 1538 // It is unsafe loop if the phi node references itself directly. 1539 if (in == (Node*)this) 1540 return UnsafeLoop; // Unsafe loop 1541 // Unsafe loop if the phi node references itself through an unsafe data node. 1542 // Exclude cases with null inputs or data nodes which could reference 1543 // itself (safe for dead loops). 1544 if (in != NULL && !in->is_dead_loop_safe()) { 1545 // Check inputs of phi's inputs also. 1546 // It is much less expensive then full graph walk. 1547 uint cnt = in->req(); 1548 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1; 1549 for (; i < cnt; ++i) { 1550 Node* m = in->in(i); 1551 if (m == (Node*)this) 1552 return UnsafeLoop; // Unsafe loop 1553 if (m != NULL && !m->is_dead_loop_safe()) { 1554 // Check the most common case (about 30% of all cases): 1555 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con). 1556 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL; 1557 if (m1 == (Node*)this) 1558 return UnsafeLoop; // Unsafe loop 1559 if (m1 != NULL && m1 == m->in(2) && 1560 m1->is_dead_loop_safe() && m->in(3)->is_Con()) { 1561 continue; // Safe case 1562 } 1563 // The phi references an unsafe node - need full analysis. 1564 return Unsafe; 1565 } 1566 } 1567 } 1568 return Safe; // Safe case - we can optimize the phi node. 1569 } 1570 1571 //------------------------------is_unsafe_data_reference----------------------- 1572 // If phi can be reached through the data input - it is data loop. 1573 bool PhiNode::is_unsafe_data_reference(Node *in) const { 1574 assert(req() > 1, ""); 1575 // First, check simple cases when phi references itself directly or 1576 // through an other node. 1577 LoopSafety safety = simple_data_loop_check(in); 1578 if (safety == UnsafeLoop) 1579 return true; // phi references itself - unsafe loop 1580 else if (safety == Safe) 1581 return false; // Safe case - phi could be replaced with the unique input. 1582 1583 // Unsafe case when we should go through data graph to determine 1584 // if the phi references itself. 1585 1586 ResourceMark rm; 1587 1588 Arena *a = Thread::current()->resource_area(); 1589 Node_List nstack(a); 1590 VectorSet visited(a); 1591 1592 nstack.push(in); // Start with unique input. 1593 visited.set(in->_idx); 1594 while (nstack.size() != 0) { 1595 Node* n = nstack.pop(); 1596 uint cnt = n->req(); 1597 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1; 1598 for (; i < cnt; i++) { 1599 Node* m = n->in(i); 1600 if (m == (Node*)this) { 1601 return true; // Data loop 1602 } 1603 if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases. 1604 if (!visited.test_set(m->_idx)) 1605 nstack.push(m); 1606 } 1607 } 1608 } 1609 return false; // The phi is not reachable from its inputs 1610 } 1611 1612 1613 //------------------------------Ideal------------------------------------------ 1614 // Return a node which is more "ideal" than the current node. Must preserve 1615 // the CFG, but we can still strip out dead paths. 1616 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1617 // The next should never happen after 6297035 fix. 1618 if( is_copy() ) // Already degraded to a Copy ? 1619 return NULL; // No change 1620 1621 Node *r = in(0); // RegionNode 1622 assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge"); 1623 1624 // Note: During parsing, phis are often transformed before their regions. 1625 // This means we have to use type_or_null to defend against untyped regions. 1626 if( phase->type_or_null(r) == Type::TOP ) // Dead code? 1627 return NULL; // No change 1628 1629 // If all inputs are value types, push the value type node down through the 1630 // phi because value type nodes should be merged through their input values. 1631 if (req() > 2 && in(1) != NULL && in(1)->is_ValueTypeBase() && (can_reshape || in(1)->is_ValueType())) { 1632 int opcode = in(1)->Opcode(); 1633 uint i = 2; 1634 for (; i < req() && in(i) && in(i)->is_ValueTypeBase(); i++) { 1635 assert(in(i)->Opcode() == opcode, "mixing pointers and values?"); 1636 } 1637 if (i == req()) { 1638 ValueTypeBaseNode* vt = in(1)->as_ValueTypeBase()->clone_with_phis(phase, in(0)); 1639 for (uint i = 2; i < req(); ++i) { 1640 vt->merge_with(phase, in(i)->as_ValueTypeBase(), i, i == (req()-1)); 1641 } 1642 return vt; 1643 } 1644 } 1645 1646 if (type()->isa_valuetypeptr() && can_reshape) { 1647 const TypeValueTypePtr* vtptr = NULL; 1648 for (uint i = 1; i < req(); i++) { 1649 if (in(i) != NULL && in(i)->is_ValueTypePtr()) { 1650 const TypeValueTypePtr* t = phase->type(in(i))->is_valuetypeptr(); 1651 if (vtptr == NULL) { 1652 vtptr = t; 1653 } else { 1654 assert(vtptr == t, "Phi should merge identical value types"); 1655 } 1656 } else { 1657 assert(in(i) == NULL || vtptr == NULL || phase->type(in(i))->higher_equal(vtptr) || phase->type(in(i)) == Type::TOP || 1658 phase->type(in(i))->is_valuetypeptr()->value_type()->value_klass() == phase->C->env()->___Value_klass(), "bad type"); 1659 } 1660 } 1661 if (vtptr != NULL) { 1662 // One input is a value type. All inputs must have the same 1663 // type. 1664 bool progress = false; 1665 PhaseIterGVN* igvn = phase->is_IterGVN(); 1666 for (uint i = 1; i < req(); i++) { 1667 if (in(i) != NULL && !phase->type(in(i))->higher_equal(vtptr)) { 1668 // Can't transform because CheckCastPPNode::Identity can 1669 // push the cast up through another Phi and cause this same 1670 // transformation to run again, indefinitely 1671 Node* cast = igvn->register_new_node_with_optimizer(new CheckCastPPNode(NULL, in(i), vtptr)); 1672 set_req(i, cast); 1673 progress = true; 1674 } 1675 } 1676 if (progress) { 1677 return this; 1678 } 1679 } 1680 } 1681 1682 Node *top = phase->C->top(); 1683 bool new_phi = (outcnt() == 0); // transforming new Phi 1684 // No change for igvn if new phi is not hooked 1685 if (new_phi && can_reshape) 1686 return NULL; 1687 1688 // The are 2 situations when only one valid phi's input is left 1689 // (in addition to Region input). 1690 // One: region is not loop - replace phi with this input. 1691 // Two: region is loop - replace phi with top since this data path is dead 1692 // and we need to break the dead data loop. 1693 Node* progress = NULL; // Record if any progress made 1694 for( uint j = 1; j < req(); ++j ){ // For all paths in 1695 // Check unreachable control paths 1696 Node* rc = r->in(j); 1697 Node* n = in(j); // Get the input 1698 if (rc == NULL || phase->type(rc) == Type::TOP) { 1699 if (n != top) { // Not already top? 1700 PhaseIterGVN *igvn = phase->is_IterGVN(); 1701 if (can_reshape && igvn != NULL) { 1702 igvn->_worklist.push(r); 1703 } 1704 set_req(j, top); // Nuke it down 1705 progress = this; // Record progress 1706 } 1707 } 1708 } 1709 1710 if (can_reshape && outcnt() == 0) { 1711 // set_req() above may kill outputs if Phi is referenced 1712 // only by itself on the dead (top) control path. 1713 return top; 1714 } 1715 1716 bool uncasted = false; 1717 Node* uin = unique_input(phase, false); 1718 if (uin == NULL && can_reshape) { 1719 uncasted = true; 1720 uin = unique_input(phase, true); 1721 } 1722 if (uin == top) { // Simplest case: no alive inputs. 1723 if (can_reshape) // IGVN transformation 1724 return top; 1725 else 1726 return NULL; // Identity will return TOP 1727 } else if (uin != NULL) { 1728 // Only one not-NULL unique input path is left. 1729 // Determine if this input is backedge of a loop. 1730 // (Skip new phis which have no uses and dead regions). 1731 if (outcnt() > 0 && r->in(0) != NULL) { 1732 // First, take the short cut when we know it is a loop and 1733 // the EntryControl data path is dead. 1734 // Loop node may have only one input because entry path 1735 // is removed in PhaseIdealLoop::Dominators(). 1736 assert(!r->is_Loop() || r->req() <= 3, "Loop node should have 3 or less inputs"); 1737 bool is_loop = (r->is_Loop() && r->req() == 3); 1738 // Then, check if there is a data loop when phi references itself directly 1739 // or through other data nodes. 1740 if (is_loop && !uin->eqv_uncast(in(LoopNode::EntryControl)) || 1741 !is_loop && is_unsafe_data_reference(uin)) { 1742 // Break this data loop to avoid creation of a dead loop. 1743 if (can_reshape) { 1744 return top; 1745 } else { 1746 // We can't return top if we are in Parse phase - cut inputs only 1747 // let Identity to handle the case. 1748 replace_edge(uin, top); 1749 return NULL; 1750 } 1751 } 1752 } 1753 1754 if (uncasted) { 1755 // Add cast nodes between the phi to be removed and its unique input. 1756 // Wait until after parsing for the type information to propagate from the casts. 1757 assert(can_reshape, "Invalid during parsing"); 1758 const Type* phi_type = bottom_type(); 1759 assert(phi_type->isa_int() || phi_type->isa_ptr(), "bad phi type"); 1760 // Add casts to carry the control dependency of the Phi that is 1761 // going away 1762 Node* cast = NULL; 1763 if (phi_type->isa_int()) { 1764 cast = ConstraintCastNode::make_cast(Op_CastII, r, uin, phi_type, true); 1765 } else { 1766 const Type* uin_type = phase->type(uin); 1767 if (!phi_type->isa_oopptr() && !uin_type->isa_oopptr()) { 1768 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true); 1769 } else { 1770 // Use a CastPP for a cast to not null and a CheckCastPP for 1771 // a cast to a new klass (and both if both null-ness and 1772 // klass change). 1773 1774 // If the type of phi is not null but the type of uin may be 1775 // null, uin's type must be casted to not null 1776 if (phi_type->join(TypePtr::NOTNULL) == phi_type->remove_speculative() && 1777 uin_type->join(TypePtr::NOTNULL) != uin_type->remove_speculative()) { 1778 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, TypePtr::NOTNULL, true); 1779 } 1780 1781 // If the type of phi and uin, both casted to not null, 1782 // differ the klass of uin must be (check)cast'ed to match 1783 // that of phi 1784 if (phi_type->join_speculative(TypePtr::NOTNULL) != uin_type->join_speculative(TypePtr::NOTNULL)) { 1785 Node* n = uin; 1786 if (cast != NULL) { 1787 cast = phase->transform(cast); 1788 n = cast; 1789 } 1790 cast = ConstraintCastNode::make_cast(Op_CheckCastPP, r, n, phi_type, true); 1791 } 1792 if (cast == NULL) { 1793 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true); 1794 } 1795 } 1796 } 1797 assert(cast != NULL, "cast should be set"); 1798 cast = phase->transform(cast); 1799 // set all inputs to the new cast(s) so the Phi is removed by Identity 1800 PhaseIterGVN* igvn = phase->is_IterGVN(); 1801 for (uint i = 1; i < req(); i++) { 1802 set_req_X(i, cast, igvn); 1803 } 1804 uin = cast; 1805 } 1806 1807 // One unique input. 1808 debug_only(Node* ident = Identity(phase)); 1809 // The unique input must eventually be detected by the Identity call. 1810 #ifdef ASSERT 1811 if (ident != uin && !ident->is_top()) { 1812 // print this output before failing assert 1813 r->dump(3); 1814 this->dump(3); 1815 ident->dump(); 1816 uin->dump(); 1817 } 1818 #endif 1819 assert(ident == uin || ident->is_top(), "Identity must clean this up"); 1820 return NULL; 1821 } 1822 1823 Node* opt = NULL; 1824 int true_path = is_diamond_phi(); 1825 if( true_path != 0 ) { 1826 // Check for CMove'ing identity. If it would be unsafe, 1827 // handle it here. In the safe case, let Identity handle it. 1828 Node* unsafe_id = is_cmove_id(phase, true_path); 1829 if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) ) 1830 opt = unsafe_id; 1831 1832 // Check for simple convert-to-boolean pattern 1833 if( opt == NULL ) 1834 opt = is_x2logic(phase, this, true_path); 1835 1836 // Check for absolute value 1837 if( opt == NULL ) 1838 opt = is_absolute(phase, this, true_path); 1839 1840 // Check for conditional add 1841 if( opt == NULL && can_reshape ) 1842 opt = is_cond_add(phase, this, true_path); 1843 1844 // These 4 optimizations could subsume the phi: 1845 // have to check for a dead data loop creation. 1846 if( opt != NULL ) { 1847 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) { 1848 // Found dead loop. 1849 if( can_reshape ) 1850 return top; 1851 // We can't return top if we are in Parse phase - cut inputs only 1852 // to stop further optimizations for this phi. Identity will return TOP. 1853 assert(req() == 3, "only diamond merge phi here"); 1854 set_req(1, top); 1855 set_req(2, top); 1856 return NULL; 1857 } else { 1858 return opt; 1859 } 1860 } 1861 } 1862 1863 // Check for merging identical values and split flow paths 1864 if (can_reshape) { 1865 opt = split_flow_path(phase, this); 1866 // This optimization only modifies phi - don't need to check for dead loop. 1867 assert(opt == NULL || phase->eqv(opt, this), "do not elide phi"); 1868 if (opt != NULL) return opt; 1869 } 1870 1871 if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) { 1872 // Try to undo Phi of AddP: 1873 // (Phi (AddP base base y) (AddP base2 base2 y)) 1874 // becomes: 1875 // newbase := (Phi base base2) 1876 // (AddP newbase newbase y) 1877 // 1878 // This occurs as a result of unsuccessful split_thru_phi and 1879 // interferes with taking advantage of addressing modes. See the 1880 // clone_shift_expressions code in matcher.cpp 1881 Node* addp = in(1); 1882 const Type* type = addp->in(AddPNode::Base)->bottom_type(); 1883 Node* y = addp->in(AddPNode::Offset); 1884 if (y != NULL && addp->in(AddPNode::Base) == addp->in(AddPNode::Address)) { 1885 // make sure that all the inputs are similar to the first one, 1886 // i.e. AddP with base == address and same offset as first AddP 1887 bool doit = true; 1888 for (uint i = 2; i < req(); i++) { 1889 if (in(i) == NULL || 1890 in(i)->Opcode() != Op_AddP || 1891 in(i)->in(AddPNode::Base) != in(i)->in(AddPNode::Address) || 1892 in(i)->in(AddPNode::Offset) != y) { 1893 doit = false; 1894 break; 1895 } 1896 // Accumulate type for resulting Phi 1897 type = type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type()); 1898 } 1899 Node* base = NULL; 1900 if (doit) { 1901 // Check for neighboring AddP nodes in a tree. 1902 // If they have a base, use that it. 1903 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) { 1904 Node* u = this->fast_out(k); 1905 if (u->is_AddP()) { 1906 Node* base2 = u->in(AddPNode::Base); 1907 if (base2 != NULL && !base2->is_top()) { 1908 if (base == NULL) 1909 base = base2; 1910 else if (base != base2) 1911 { doit = false; break; } 1912 } 1913 } 1914 } 1915 } 1916 if (doit) { 1917 if (base == NULL) { 1918 base = new PhiNode(in(0), type, NULL); 1919 for (uint i = 1; i < req(); i++) { 1920 base->init_req(i, in(i)->in(AddPNode::Base)); 1921 } 1922 phase->is_IterGVN()->register_new_node_with_optimizer(base); 1923 } 1924 return new AddPNode(base, base, y); 1925 } 1926 } 1927 } 1928 1929 // Split phis through memory merges, so that the memory merges will go away. 1930 // Piggy-back this transformation on the search for a unique input.... 1931 // It will be as if the merged memory is the unique value of the phi. 1932 // (Do not attempt this optimization unless parsing is complete. 1933 // It would make the parser's memory-merge logic sick.) 1934 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.) 1935 if (progress == NULL && can_reshape && type() == Type::MEMORY) { 1936 // see if this phi should be sliced 1937 uint merge_width = 0; 1938 bool saw_self = false; 1939 for( uint i=1; i<req(); ++i ) {// For all paths in 1940 Node *ii = in(i); 1941 // TOP inputs should not be counted as safe inputs because if the 1942 // Phi references itself through all other inputs then splitting the 1943 // Phi through memory merges would create dead loop at later stage. 1944 if (ii == top) { 1945 return NULL; // Delay optimization until graph is cleaned. 1946 } 1947 if (ii->is_MergeMem()) { 1948 MergeMemNode* n = ii->as_MergeMem(); 1949 merge_width = MAX2(merge_width, n->req()); 1950 saw_self = saw_self || phase->eqv(n->base_memory(), this); 1951 } 1952 } 1953 1954 // This restriction is temporarily necessary to ensure termination: 1955 if (!saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0; 1956 1957 if (merge_width > Compile::AliasIdxRaw) { 1958 // found at least one non-empty MergeMem 1959 const TypePtr* at = adr_type(); 1960 if (at != TypePtr::BOTTOM) { 1961 // Patch the existing phi to select an input from the merge: 1962 // Phi:AT1(...MergeMem(m0, m1, m2)...) into 1963 // Phi:AT1(...m1...) 1964 int alias_idx = phase->C->get_alias_index(at); 1965 for (uint i=1; i<req(); ++i) { 1966 Node *ii = in(i); 1967 if (ii->is_MergeMem()) { 1968 MergeMemNode* n = ii->as_MergeMem(); 1969 // compress paths and change unreachable cycles to TOP 1970 // If not, we can update the input infinitely along a MergeMem cycle 1971 // Equivalent code is in MemNode::Ideal_common 1972 Node *m = phase->transform(n); 1973 if (outcnt() == 0) { // Above transform() may kill us! 1974 return top; 1975 } 1976 // If transformed to a MergeMem, get the desired slice 1977 // Otherwise the returned node represents memory for every slice 1978 Node *new_mem = (m->is_MergeMem()) ? 1979 m->as_MergeMem()->memory_at(alias_idx) : m; 1980 // Update input if it is progress over what we have now 1981 if (new_mem != ii) { 1982 set_req(i, new_mem); 1983 progress = this; 1984 } 1985 } 1986 } 1987 } else { 1988 // We know that at least one MergeMem->base_memory() == this 1989 // (saw_self == true). If all other inputs also references this phi 1990 // (directly or through data nodes) - it is dead loop. 1991 bool saw_safe_input = false; 1992 for (uint j = 1; j < req(); ++j) { 1993 Node *n = in(j); 1994 if (n->is_MergeMem() && n->as_MergeMem()->base_memory() == this) 1995 continue; // skip known cases 1996 if (!is_unsafe_data_reference(n)) { 1997 saw_safe_input = true; // found safe input 1998 break; 1999 } 2000 } 2001 if (!saw_safe_input) 2002 return top; // all inputs reference back to this phi - dead loop 2003 2004 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into 2005 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...)) 2006 PhaseIterGVN *igvn = phase->is_IterGVN(); 2007 Node* hook = new Node(1); 2008 PhiNode* new_base = (PhiNode*) clone(); 2009 // Must eagerly register phis, since they participate in loops. 2010 if (igvn) { 2011 igvn->register_new_node_with_optimizer(new_base); 2012 hook->add_req(new_base); 2013 } 2014 MergeMemNode* result = MergeMemNode::make(new_base); 2015 for (uint i = 1; i < req(); ++i) { 2016 Node *ii = in(i); 2017 if (ii->is_MergeMem()) { 2018 MergeMemNode* n = ii->as_MergeMem(); 2019 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) { 2020 // If we have not seen this slice yet, make a phi for it. 2021 bool made_new_phi = false; 2022 if (mms.is_empty()) { 2023 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C)); 2024 made_new_phi = true; 2025 if (igvn) { 2026 igvn->register_new_node_with_optimizer(new_phi); 2027 hook->add_req(new_phi); 2028 } 2029 mms.set_memory(new_phi); 2030 } 2031 Node* phi = mms.memory(); 2032 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice"); 2033 phi->set_req(i, mms.memory2()); 2034 } 2035 } 2036 } 2037 // Distribute all self-loops. 2038 { // (Extra braces to hide mms.) 2039 for (MergeMemStream mms(result); mms.next_non_empty(); ) { 2040 Node* phi = mms.memory(); 2041 for (uint i = 1; i < req(); ++i) { 2042 if (phi->in(i) == this) phi->set_req(i, phi); 2043 } 2044 } 2045 } 2046 // now transform the new nodes, and return the mergemem 2047 for (MergeMemStream mms(result); mms.next_non_empty(); ) { 2048 Node* phi = mms.memory(); 2049 mms.set_memory(phase->transform(phi)); 2050 } 2051 if (igvn) { // Unhook. 2052 igvn->hash_delete(hook); 2053 for (uint i = 1; i < hook->req(); i++) { 2054 hook->set_req(i, NULL); 2055 } 2056 } 2057 // Replace self with the result. 2058 return result; 2059 } 2060 } 2061 // 2062 // Other optimizations on the memory chain 2063 // 2064 const TypePtr* at = adr_type(); 2065 for( uint i=1; i<req(); ++i ) {// For all paths in 2066 Node *ii = in(i); 2067 Node *new_in = MemNode::optimize_memory_chain(ii, at, NULL, phase); 2068 if (ii != new_in ) { 2069 set_req(i, new_in); 2070 progress = this; 2071 } 2072 } 2073 } 2074 2075 #ifdef _LP64 2076 // Push DecodeN/DecodeNKlass down through phi. 2077 // The rest of phi graph will transform by split EncodeP node though phis up. 2078 if ((UseCompressedOops || UseCompressedClassPointers) && can_reshape && progress == NULL) { 2079 bool may_push = true; 2080 bool has_decodeN = false; 2081 bool is_decodeN = false; 2082 for (uint i=1; i<req(); ++i) {// For all paths in 2083 Node *ii = in(i); 2084 if (ii->is_DecodeNarrowPtr() && ii->bottom_type() == bottom_type()) { 2085 // Do optimization if a non dead path exist. 2086 if (ii->in(1)->bottom_type() != Type::TOP) { 2087 has_decodeN = true; 2088 is_decodeN = ii->is_DecodeN(); 2089 } 2090 } else if (!ii->is_Phi()) { 2091 may_push = false; 2092 } 2093 } 2094 2095 if (has_decodeN && may_push) { 2096 PhaseIterGVN *igvn = phase->is_IterGVN(); 2097 // Make narrow type for new phi. 2098 const Type* narrow_t; 2099 if (is_decodeN) { 2100 narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr()); 2101 } else { 2102 narrow_t = TypeNarrowKlass::make(this->bottom_type()->is_ptr()); 2103 } 2104 PhiNode* new_phi = new PhiNode(r, narrow_t); 2105 uint orig_cnt = req(); 2106 for (uint i=1; i<req(); ++i) {// For all paths in 2107 Node *ii = in(i); 2108 Node* new_ii = NULL; 2109 if (ii->is_DecodeNarrowPtr()) { 2110 assert(ii->bottom_type() == bottom_type(), "sanity"); 2111 new_ii = ii->in(1); 2112 } else { 2113 assert(ii->is_Phi(), "sanity"); 2114 if (ii->as_Phi() == this) { 2115 new_ii = new_phi; 2116 } else { 2117 if (is_decodeN) { 2118 new_ii = new EncodePNode(ii, narrow_t); 2119 } else { 2120 new_ii = new EncodePKlassNode(ii, narrow_t); 2121 } 2122 igvn->register_new_node_with_optimizer(new_ii); 2123 } 2124 } 2125 new_phi->set_req(i, new_ii); 2126 } 2127 igvn->register_new_node_with_optimizer(new_phi, this); 2128 if (is_decodeN) { 2129 progress = new DecodeNNode(new_phi, bottom_type()); 2130 } else { 2131 progress = new DecodeNKlassNode(new_phi, bottom_type()); 2132 } 2133 } 2134 } 2135 #endif 2136 2137 return progress; // Return any progress 2138 } 2139 2140 //------------------------------is_tripcount----------------------------------- 2141 bool PhiNode::is_tripcount() const { 2142 return (in(0) != NULL && in(0)->is_CountedLoop() && 2143 in(0)->as_CountedLoop()->phi() == this); 2144 } 2145 2146 //------------------------------out_RegMask------------------------------------ 2147 const RegMask &PhiNode::in_RegMask(uint i) const { 2148 return i ? out_RegMask() : RegMask::Empty; 2149 } 2150 2151 const RegMask &PhiNode::out_RegMask() const { 2152 uint ideal_reg = _type->ideal_reg(); 2153 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" ); 2154 if( ideal_reg == 0 ) return RegMask::Empty; 2155 assert(ideal_reg != Op_RegFlags, "flags register is not spillable"); 2156 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]); 2157 } 2158 2159 #ifndef PRODUCT 2160 void PhiNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const { 2161 // For a PhiNode, the set of related nodes includes all inputs till level 2, 2162 // and all outputs till level 1. In compact mode, inputs till level 1 are 2163 // collected. 2164 this->collect_nodes(in_rel, compact ? 1 : 2, false, false); 2165 this->collect_nodes(out_rel, -1, false, false); 2166 } 2167 2168 void PhiNode::dump_spec(outputStream *st) const { 2169 TypeNode::dump_spec(st); 2170 if (is_tripcount()) { 2171 st->print(" #tripcount"); 2172 } 2173 } 2174 #endif 2175 2176 2177 //============================================================================= 2178 const Type* GotoNode::Value(PhaseGVN* phase) const { 2179 // If the input is reachable, then we are executed. 2180 // If the input is not reachable, then we are not executed. 2181 return phase->type(in(0)); 2182 } 2183 2184 Node* GotoNode::Identity(PhaseGVN* phase) { 2185 return in(0); // Simple copy of incoming control 2186 } 2187 2188 const RegMask &GotoNode::out_RegMask() const { 2189 return RegMask::Empty; 2190 } 2191 2192 #ifndef PRODUCT 2193 //-----------------------------related----------------------------------------- 2194 // The related nodes of a GotoNode are all inputs at level 1, as well as the 2195 // outputs at level 1. This is regardless of compact mode. 2196 void GotoNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const { 2197 this->collect_nodes(in_rel, 1, false, false); 2198 this->collect_nodes(out_rel, -1, false, false); 2199 } 2200 #endif 2201 2202 2203 //============================================================================= 2204 const RegMask &JumpNode::out_RegMask() const { 2205 return RegMask::Empty; 2206 } 2207 2208 #ifndef PRODUCT 2209 //-----------------------------related----------------------------------------- 2210 // The related nodes of a JumpNode are all inputs at level 1, as well as the 2211 // outputs at level 2 (to include actual jump targets beyond projection nodes). 2212 // This is regardless of compact mode. 2213 void JumpNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const { 2214 this->collect_nodes(in_rel, 1, false, false); 2215 this->collect_nodes(out_rel, -2, false, false); 2216 } 2217 #endif 2218 2219 //============================================================================= 2220 const RegMask &JProjNode::out_RegMask() const { 2221 return RegMask::Empty; 2222 } 2223 2224 //============================================================================= 2225 const RegMask &CProjNode::out_RegMask() const { 2226 return RegMask::Empty; 2227 } 2228 2229 2230 2231 //============================================================================= 2232 2233 uint PCTableNode::hash() const { return Node::hash() + _size; } 2234 uint PCTableNode::cmp( const Node &n ) const 2235 { return _size == ((PCTableNode&)n)._size; } 2236 2237 const Type *PCTableNode::bottom_type() const { 2238 const Type** f = TypeTuple::fields(_size); 2239 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL; 2240 return TypeTuple::make(_size, f); 2241 } 2242 2243 //------------------------------Value------------------------------------------ 2244 // Compute the type of the PCTableNode. If reachable it is a tuple of 2245 // Control, otherwise the table targets are not reachable 2246 const Type* PCTableNode::Value(PhaseGVN* phase) const { 2247 if( phase->type(in(0)) == Type::CONTROL ) 2248 return bottom_type(); 2249 return Type::TOP; // All paths dead? Then so are we 2250 } 2251 2252 //------------------------------Ideal------------------------------------------ 2253 // Return a node which is more "ideal" than the current node. Strip out 2254 // control copies 2255 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2256 return remove_dead_region(phase, can_reshape) ? this : NULL; 2257 } 2258 2259 //============================================================================= 2260 uint JumpProjNode::hash() const { 2261 return Node::hash() + _dest_bci; 2262 } 2263 2264 uint JumpProjNode::cmp( const Node &n ) const { 2265 return ProjNode::cmp(n) && 2266 _dest_bci == ((JumpProjNode&)n)._dest_bci; 2267 } 2268 2269 #ifndef PRODUCT 2270 void JumpProjNode::dump_spec(outputStream *st) const { 2271 ProjNode::dump_spec(st); 2272 st->print("@bci %d ",_dest_bci); 2273 } 2274 2275 void JumpProjNode::dump_compact_spec(outputStream *st) const { 2276 ProjNode::dump_compact_spec(st); 2277 st->print("(%d)%d@%d", _switch_val, _proj_no, _dest_bci); 2278 } 2279 2280 void JumpProjNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const { 2281 // The related nodes of a JumpProjNode are its inputs and outputs at level 1. 2282 this->collect_nodes(in_rel, 1, false, false); 2283 this->collect_nodes(out_rel, -1, false, false); 2284 } 2285 #endif 2286 2287 //============================================================================= 2288 //------------------------------Value------------------------------------------ 2289 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot 2290 // have the default "fall_through_index" path. 2291 const Type* CatchNode::Value(PhaseGVN* phase) const { 2292 // Unreachable? Then so are all paths from here. 2293 if( phase->type(in(0)) == Type::TOP ) return Type::TOP; 2294 // First assume all paths are reachable 2295 const Type** f = TypeTuple::fields(_size); 2296 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL; 2297 // Identify cases that will always throw an exception 2298 // () rethrow call 2299 // () virtual or interface call with NULL receiver 2300 // () call is a check cast with incompatible arguments 2301 if( in(1)->is_Proj() ) { 2302 Node *i10 = in(1)->in(0); 2303 if( i10->is_Call() ) { 2304 CallNode *call = i10->as_Call(); 2305 // Rethrows always throw exceptions, never return 2306 if (call->entry_point() == OptoRuntime::rethrow_stub()) { 2307 f[CatchProjNode::fall_through_index] = Type::TOP; 2308 } else if( call->req() > TypeFunc::Parms ) { 2309 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) ); 2310 // Check for null receiver to virtual or interface calls 2311 if( call->is_CallDynamicJava() && 2312 arg0->higher_equal(TypePtr::NULL_PTR) ) { 2313 f[CatchProjNode::fall_through_index] = Type::TOP; 2314 } 2315 } // End of if not a runtime stub 2316 } // End of if have call above me 2317 } // End of slot 1 is not a projection 2318 return TypeTuple::make(_size, f); 2319 } 2320 2321 //============================================================================= 2322 uint CatchProjNode::hash() const { 2323 return Node::hash() + _handler_bci; 2324 } 2325 2326 2327 uint CatchProjNode::cmp( const Node &n ) const { 2328 return ProjNode::cmp(n) && 2329 _handler_bci == ((CatchProjNode&)n)._handler_bci; 2330 } 2331 2332 2333 //------------------------------Identity--------------------------------------- 2334 // If only 1 target is possible, choose it if it is the main control 2335 Node* CatchProjNode::Identity(PhaseGVN* phase) { 2336 // If my value is control and no other value is, then treat as ID 2337 const TypeTuple *t = phase->type(in(0))->is_tuple(); 2338 if (t->field_at(_con) != Type::CONTROL) return this; 2339 // If we remove the last CatchProj and elide the Catch/CatchProj, then we 2340 // also remove any exception table entry. Thus we must know the call 2341 // feeding the Catch will not really throw an exception. This is ok for 2342 // the main fall-thru control (happens when we know a call can never throw 2343 // an exception) or for "rethrow", because a further optimization will 2344 // yank the rethrow (happens when we inline a function that can throw an 2345 // exception and the caller has no handler). Not legal, e.g., for passing 2346 // a NULL receiver to a v-call, or passing bad types to a slow-check-cast. 2347 // These cases MUST throw an exception via the runtime system, so the VM 2348 // will be looking for a table entry. 2349 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode 2350 CallNode *call; 2351 if (_con != TypeFunc::Control && // Bail out if not the main control. 2352 !(proj->is_Proj() && // AND NOT a rethrow 2353 proj->in(0)->is_Call() && 2354 (call = proj->in(0)->as_Call()) && 2355 call->entry_point() == OptoRuntime::rethrow_stub())) 2356 return this; 2357 2358 // Search for any other path being control 2359 for (uint i = 0; i < t->cnt(); i++) { 2360 if (i != _con && t->field_at(i) == Type::CONTROL) 2361 return this; 2362 } 2363 // Only my path is possible; I am identity on control to the jump 2364 return in(0)->in(0); 2365 } 2366 2367 2368 #ifndef PRODUCT 2369 void CatchProjNode::dump_spec(outputStream *st) const { 2370 ProjNode::dump_spec(st); 2371 st->print("@bci %d ",_handler_bci); 2372 } 2373 #endif 2374 2375 //============================================================================= 2376 //------------------------------Identity--------------------------------------- 2377 // Check for CreateEx being Identity. 2378 Node* CreateExNode::Identity(PhaseGVN* phase) { 2379 if( phase->type(in(1)) == Type::TOP ) return in(1); 2380 if( phase->type(in(0)) == Type::TOP ) return in(0); 2381 // We only come from CatchProj, unless the CatchProj goes away. 2382 // If the CatchProj is optimized away, then we just carry the 2383 // exception oop through. 2384 if (in(1)->is_Phi()) return this; 2385 CallNode *call = in(1)->in(0)->as_Call(); 2386 2387 return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) ) 2388 ? this 2389 : call->in(TypeFunc::Parms); 2390 } 2391 2392 //============================================================================= 2393 //------------------------------Value------------------------------------------ 2394 // Check for being unreachable. 2395 const Type* NeverBranchNode::Value(PhaseGVN* phase) const { 2396 if (!in(0) || in(0)->is_top()) return Type::TOP; 2397 return bottom_type(); 2398 } 2399 2400 //------------------------------Ideal------------------------------------------ 2401 // Check for no longer being part of a loop 2402 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2403 if (can_reshape && !in(0)->is_Loop()) { 2404 // Dead code elimination can sometimes delete this projection so 2405 // if it's not there, there's nothing to do. 2406 Node* fallthru = proj_out(0); 2407 if (fallthru != NULL) { 2408 phase->is_IterGVN()->replace_node(fallthru, in(0)); 2409 } 2410 return phase->C->top(); 2411 } 2412 return NULL; 2413 } 2414 2415 #ifndef PRODUCT 2416 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const { 2417 st->print("%s", Name()); 2418 } 2419 #endif