1 /* 2 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "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 #include "utilities/vmError.hpp" 46 47 // Portions of code courtesy of Clifford Click 48 49 // Optimization - Graph Style 50 51 //============================================================================= 52 //------------------------------Value------------------------------------------ 53 // Compute the type of the RegionNode. 54 const Type* RegionNode::Value(PhaseGVN* phase) const { 55 for( uint i=1; i<req(); ++i ) { // For all paths in 56 Node *n = in(i); // Get Control source 57 if( !n ) continue; // Missing inputs are TOP 58 if( phase->type(n) == Type::CONTROL ) 59 return Type::CONTROL; 60 } 61 return Type::TOP; // All paths dead? Then so are we 62 } 63 64 //------------------------------Identity--------------------------------------- 65 // Check for Region being Identity. 66 Node* RegionNode::Identity(PhaseGVN* phase) { 67 // Cannot have Region be an identity, even if it has only 1 input. 68 // Phi users cannot have their Region input folded away for them, 69 // since they need to select the proper data input 70 return this; 71 } 72 73 //------------------------------merge_region----------------------------------- 74 // If a Region flows into a Region, merge into one big happy merge. This is 75 // hard to do if there is stuff that has to happen 76 static Node *merge_region(RegionNode *region, PhaseGVN *phase) { 77 if( region->Opcode() != Op_Region ) // Do not do to LoopNodes 78 return NULL; 79 Node *progress = NULL; // Progress flag 80 PhaseIterGVN *igvn = phase->is_IterGVN(); 81 82 uint rreq = region->req(); 83 for( uint i = 1; i < rreq; i++ ) { 84 Node *r = region->in(i); 85 if( r && r->Opcode() == Op_Region && // Found a region? 86 r->in(0) == r && // Not already collapsed? 87 r != region && // Avoid stupid situations 88 r->outcnt() == 2 ) { // Self user and 'region' user only? 89 assert(!r->as_Region()->has_phi(), "no phi users"); 90 if( !progress ) { // No progress 91 if (region->has_phi()) { 92 return NULL; // Only flatten if no Phi users 93 // igvn->hash_delete( phi ); 94 } 95 igvn->hash_delete( region ); 96 progress = region; // Making progress 97 } 98 igvn->hash_delete( r ); 99 100 // Append inputs to 'r' onto 'region' 101 for( uint j = 1; j < r->req(); j++ ) { 102 // Move an input from 'r' to 'region' 103 region->add_req(r->in(j)); 104 r->set_req(j, phase->C->top()); 105 // Update phis of 'region' 106 //for( uint k = 0; k < max; k++ ) { 107 // Node *phi = region->out(k); 108 // if( phi->is_Phi() ) { 109 // phi->add_req(phi->in(i)); 110 // } 111 //} 112 113 rreq++; // One more input to Region 114 } // Found a region to merge into Region 115 igvn->_worklist.push(r); 116 // Clobber pointer to the now dead 'r' 117 region->set_req(i, phase->C->top()); 118 } 119 } 120 121 return progress; 122 } 123 124 125 126 //--------------------------------has_phi-------------------------------------- 127 // Helper function: Return any PhiNode that uses this region or NULL 128 PhiNode* RegionNode::has_phi() const { 129 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 130 Node* phi = fast_out(i); 131 if (phi->is_Phi()) { // Check for Phi users 132 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)"); 133 return phi->as_Phi(); // this one is good enough 134 } 135 } 136 137 return NULL; 138 } 139 140 141 //-----------------------------has_unique_phi---------------------------------- 142 // Helper function: Return the only PhiNode that uses this region or NULL 143 PhiNode* RegionNode::has_unique_phi() const { 144 // Check that only one use is a Phi 145 PhiNode* only_phi = NULL; 146 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 147 Node* phi = fast_out(i); 148 if (phi->is_Phi()) { // Check for Phi users 149 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)"); 150 if (only_phi == NULL) { 151 only_phi = phi->as_Phi(); 152 } else { 153 return NULL; // multiple phis 154 } 155 } 156 } 157 158 return only_phi; 159 } 160 161 162 //------------------------------check_phi_clipping----------------------------- 163 // Helper function for RegionNode's identification of FP clipping 164 // Check inputs to the Phi 165 static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) { 166 min = NULL; 167 max = NULL; 168 val = NULL; 169 min_idx = 0; 170 max_idx = 0; 171 val_idx = 0; 172 uint phi_max = phi->req(); 173 if( phi_max == 4 ) { 174 for( uint j = 1; j < phi_max; ++j ) { 175 Node *n = phi->in(j); 176 int opcode = n->Opcode(); 177 switch( opcode ) { 178 case Op_ConI: 179 { 180 if( min == NULL ) { 181 min = n->Opcode() == Op_ConI ? (ConNode*)n : NULL; 182 min_idx = j; 183 } else { 184 max = n->Opcode() == Op_ConI ? (ConNode*)n : NULL; 185 max_idx = j; 186 if( min->get_int() > max->get_int() ) { 187 // Swap min and max 188 ConNode *temp; 189 uint temp_idx; 190 temp = min; min = max; max = temp; 191 temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx; 192 } 193 } 194 } 195 break; 196 default: 197 { 198 val = n; 199 val_idx = j; 200 } 201 break; 202 } 203 } 204 } 205 return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) ); 206 } 207 208 209 //------------------------------check_if_clipping------------------------------ 210 // Helper function for RegionNode's identification of FP clipping 211 // Check that inputs to Region come from two IfNodes, 212 // 213 // If 214 // False True 215 // If | 216 // False True | 217 // | | | 218 // RegionNode_inputs 219 // 220 static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) { 221 top_if = NULL; 222 bot_if = NULL; 223 224 // Check control structure above RegionNode for (if ( if ) ) 225 Node *in1 = region->in(1); 226 Node *in2 = region->in(2); 227 Node *in3 = region->in(3); 228 // Check that all inputs are projections 229 if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) { 230 Node *in10 = in1->in(0); 231 Node *in20 = in2->in(0); 232 Node *in30 = in3->in(0); 233 // Check that #1 and #2 are ifTrue and ifFalse from same If 234 if( in10 != NULL && in10->is_If() && 235 in20 != NULL && in20->is_If() && 236 in30 != NULL && in30->is_If() && in10 == in20 && 237 (in1->Opcode() != in2->Opcode()) ) { 238 Node *in100 = in10->in(0); 239 Node *in1000 = (in100 != NULL && in100->is_Proj()) ? in100->in(0) : NULL; 240 // Check that control for in10 comes from other branch of IF from in3 241 if( in1000 != NULL && in1000->is_If() && 242 in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) { 243 // Control pattern checks 244 top_if = (IfNode*)in1000; 245 bot_if = (IfNode*)in10; 246 } 247 } 248 } 249 250 return (top_if != NULL); 251 } 252 253 254 //------------------------------check_convf2i_clipping------------------------- 255 // Helper function for RegionNode's identification of FP clipping 256 // Verify that the value input to the phi comes from "ConvF2I; LShift; RShift" 257 static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) { 258 convf2i = NULL; 259 260 // Check for the RShiftNode 261 Node *rshift = phi->in(idx); 262 assert( rshift, "Previous checks ensure phi input is present"); 263 if( rshift->Opcode() != Op_RShiftI ) { return false; } 264 265 // Check for the LShiftNode 266 Node *lshift = rshift->in(1); 267 assert( lshift, "Previous checks ensure phi input is present"); 268 if( lshift->Opcode() != Op_LShiftI ) { return false; } 269 270 // Check for the ConvF2INode 271 Node *conv = lshift->in(1); 272 if( conv->Opcode() != Op_ConvF2I ) { return false; } 273 274 // Check that shift amounts are only to get sign bits set after F2I 275 jint max_cutoff = max->get_int(); 276 jint min_cutoff = min->get_int(); 277 jint left_shift = lshift->in(2)->get_int(); 278 jint right_shift = rshift->in(2)->get_int(); 279 jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1); 280 if( left_shift != right_shift || 281 0 > left_shift || left_shift >= BitsPerJavaInteger || 282 max_post_shift < max_cutoff || 283 max_post_shift < -min_cutoff ) { 284 // Shifts are necessary but current transformation eliminates them 285 return false; 286 } 287 288 // OK to return the result of ConvF2I without shifting 289 convf2i = (ConvF2INode*)conv; 290 return true; 291 } 292 293 294 //------------------------------check_compare_clipping------------------------- 295 // Helper function for RegionNode's identification of FP clipping 296 static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) { 297 Node *i1 = iff->in(1); 298 if ( !i1->is_Bool() ) { return false; } 299 BoolNode *bool1 = i1->as_Bool(); 300 if( less_than && bool1->_test._test != BoolTest::le ) { return false; } 301 else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; } 302 const Node *cmpF = bool1->in(1); 303 if( cmpF->Opcode() != Op_CmpF ) { return false; } 304 // Test that the float value being compared against 305 // is equivalent to the int value used as a limit 306 Node *nodef = cmpF->in(2); 307 if( nodef->Opcode() != Op_ConF ) { return false; } 308 jfloat conf = nodef->getf(); 309 jint coni = limit->get_int(); 310 if( ((int)conf) != coni ) { return false; } 311 input = cmpF->in(1); 312 return true; 313 } 314 315 //------------------------------is_unreachable_region-------------------------- 316 // Find if the Region node is reachable from the root. 317 bool RegionNode::is_unreachable_region(PhaseGVN *phase) const { 318 assert(req() == 2, ""); 319 320 // First, cut the simple case of fallthrough region when NONE of 321 // region's phis references itself directly or through a data node. 322 uint max = outcnt(); 323 uint i; 324 for (i = 0; i < max; i++) { 325 Node* phi = raw_out(i); 326 if (phi != NULL && phi->is_Phi()) { 327 assert(phase->eqv(phi->in(0), this) && phi->req() == 2, ""); 328 if (phi->outcnt() == 0) 329 continue; // Safe case - no loops 330 if (phi->outcnt() == 1) { 331 Node* u = phi->raw_out(0); 332 // Skip if only one use is an other Phi or Call or Uncommon trap. 333 // It is safe to consider this case as fallthrough. 334 if (u != NULL && (u->is_Phi() || u->is_CFG())) 335 continue; 336 } 337 // Check when phi references itself directly or through an other node. 338 if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe) 339 break; // Found possible unsafe data loop. 340 } 341 } 342 if (i >= max) 343 return false; // An unsafe case was NOT found - don't need graph walk. 344 345 // Unsafe case - check if the Region node is reachable from root. 346 ResourceMark rm; 347 348 Arena *a = Thread::current()->resource_area(); 349 Node_List nstack(a); 350 VectorSet visited(a); 351 352 // Mark all control nodes reachable from root outputs 353 Node *n = (Node*)phase->C->root(); 354 nstack.push(n); 355 visited.set(n->_idx); 356 while (nstack.size() != 0) { 357 n = nstack.pop(); 358 uint max = n->outcnt(); 359 for (uint i = 0; i < max; i++) { 360 Node* m = n->raw_out(i); 361 if (m != NULL && m->is_CFG()) { 362 if (phase->eqv(m, this)) { 363 return false; // We reached the Region node - it is not dead. 364 } 365 if (!visited.test_set(m->_idx)) 366 nstack.push(m); 367 } 368 } 369 } 370 371 return true; // The Region node is unreachable - it is dead. 372 } 373 374 bool RegionNode::try_clean_mem_phi(PhaseGVN *phase) { 375 // Incremental inlining + PhaseStringOpts sometimes produce: 376 // 377 // cmpP with 1 top input 378 // | 379 // If 380 // / \ 381 // IfFalse IfTrue /- Some Node 382 // \ / / / 383 // Region / /-MergeMem 384 // \---Phi 385 // 386 // 387 // It's expected by PhaseStringOpts that the Region goes away and is 388 // replaced by If's control input but because there's still a Phi, 389 // the Region stays in the graph. The top input from the cmpP is 390 // propagated forward and a subgraph that is useful goes away. The 391 // code below replaces the Phi with the MergeMem so that the Region 392 // is simplified. 393 394 PhiNode* phi = has_unique_phi(); 395 if (phi && phi->type() == Type::MEMORY && req() == 3 && phi->is_diamond_phi(true)) { 396 MergeMemNode* m = NULL; 397 assert(phi->req() == 3, "same as region"); 398 for (uint i = 1; i < 3; ++i) { 399 Node *mem = phi->in(i); 400 if (mem && mem->is_MergeMem() && in(i)->outcnt() == 1) { 401 // Nothing is control-dependent on path #i except the region itself. 402 m = mem->as_MergeMem(); 403 uint j = 3 - i; 404 Node* other = phi->in(j); 405 if (other && other == m->base_memory()) { 406 // m is a successor memory to other, and is not pinned inside the diamond, so push it out. 407 // This will allow the diamond to collapse completely. 408 phase->is_IterGVN()->replace_node(phi, m); 409 return true; 410 } 411 } 412 } 413 } 414 return false; 415 } 416 417 //------------------------------Ideal------------------------------------------ 418 // Return a node which is more "ideal" than the current node. Must preserve 419 // the CFG, but we can still strip out dead paths. 420 Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) { 421 if( !can_reshape && !in(0) ) return NULL; // Already degraded to a Copy 422 assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge"); 423 424 // Check for RegionNode with no Phi users and both inputs come from either 425 // arm of the same IF. If found, then the control-flow split is useless. 426 bool has_phis = false; 427 if (can_reshape) { // Need DU info to check for Phi users 428 has_phis = (has_phi() != NULL); // Cache result 429 if (has_phis && try_clean_mem_phi(phase)) { 430 has_phis = false; 431 } 432 433 if (!has_phis) { // No Phi users? Nothing merging? 434 for (uint i = 1; i < req()-1; i++) { 435 Node *if1 = in(i); 436 if( !if1 ) continue; 437 Node *iff = if1->in(0); 438 if( !iff || !iff->is_If() ) continue; 439 for( uint j=i+1; j<req(); j++ ) { 440 if( in(j) && in(j)->in(0) == iff && 441 if1->Opcode() != in(j)->Opcode() ) { 442 // Add the IF Projections to the worklist. They (and the IF itself) 443 // will be eliminated if dead. 444 phase->is_IterGVN()->add_users_to_worklist(iff); 445 set_req(i, iff->in(0));// Skip around the useless IF diamond 446 set_req(j, NULL); 447 return this; // Record progress 448 } 449 } 450 } 451 } 452 } 453 454 // Remove TOP or NULL input paths. If only 1 input path remains, this Region 455 // degrades to a copy. 456 bool add_to_worklist = false; 457 bool modified = false; 458 int cnt = 0; // Count of values merging 459 DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count 460 int del_it = 0; // The last input path we delete 461 // For all inputs... 462 for( uint i=1; i<req(); ++i ){// For all paths in 463 Node *n = in(i); // Get the input 464 if( n != NULL ) { 465 // Remove useless control copy inputs 466 if( n->is_Region() && n->as_Region()->is_copy() ) { 467 set_req(i, n->nonnull_req()); 468 modified = true; 469 i--; 470 continue; 471 } 472 if( n->is_Proj() ) { // Remove useless rethrows 473 Node *call = n->in(0); 474 if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) { 475 set_req(i, call->in(0)); 476 modified = true; 477 i--; 478 continue; 479 } 480 } 481 if( phase->type(n) == Type::TOP ) { 482 set_req(i, NULL); // Ignore TOP inputs 483 modified = true; 484 i--; 485 continue; 486 } 487 cnt++; // One more value merging 488 489 } else if (can_reshape) { // Else found dead path with DU info 490 PhaseIterGVN *igvn = phase->is_IterGVN(); 491 del_req(i); // Yank path from self 492 del_it = i; 493 uint max = outcnt(); 494 DUIterator j; 495 bool progress = true; 496 while(progress) { // Need to establish property over all users 497 progress = false; 498 for (j = outs(); has_out(j); j++) { 499 Node *n = out(j); 500 if( n->req() != req() && n->is_Phi() ) { 501 assert( n->in(0) == this, "" ); 502 igvn->hash_delete(n); // Yank from hash before hacking edges 503 n->set_req_X(i,NULL,igvn);// Correct DU info 504 n->del_req(i); // Yank path from Phis 505 if( max != outcnt() ) { 506 progress = true; 507 j = refresh_out_pos(j); 508 max = outcnt(); 509 } 510 } 511 } 512 } 513 add_to_worklist = true; 514 i--; 515 } 516 } 517 518 if (can_reshape && cnt == 1) { 519 // Is it dead loop? 520 // If it is LoopNopde it had 2 (+1 itself) inputs and 521 // one of them was cut. The loop is dead if it was EntryContol. 522 // Loop node may have only one input because entry path 523 // is removed in PhaseIdealLoop::Dominators(). 524 assert(!this->is_Loop() || cnt_orig <= 3, "Loop node should have 3 or less inputs"); 525 if ((this->is_Loop() && (del_it == LoopNode::EntryControl || 526 (del_it == 0 && is_unreachable_region(phase)))) || 527 (!this->is_Loop() && has_phis && is_unreachable_region(phase))) { 528 // Yes, the region will be removed during the next step below. 529 // Cut the backedge input and remove phis since no data paths left. 530 // We don't cut outputs to other nodes here since we need to put them 531 // on the worklist. 532 PhaseIterGVN *igvn = phase->is_IterGVN(); 533 if (in(1)->outcnt() == 1) { 534 igvn->_worklist.push(in(1)); 535 } 536 del_req(1); 537 cnt = 0; 538 assert( req() == 1, "no more inputs expected" ); 539 uint max = outcnt(); 540 bool progress = true; 541 Node *top = phase->C->top(); 542 DUIterator j; 543 while(progress) { 544 progress = false; 545 for (j = outs(); has_out(j); j++) { 546 Node *n = out(j); 547 if( n->is_Phi() ) { 548 assert( igvn->eqv(n->in(0), this), "" ); 549 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" ); 550 // Break dead loop data path. 551 // Eagerly replace phis with top to avoid phis copies generation. 552 igvn->replace_node(n, top); 553 if( max != outcnt() ) { 554 progress = true; 555 j = refresh_out_pos(j); 556 max = outcnt(); 557 } 558 } 559 } 560 } 561 add_to_worklist = true; 562 } 563 } 564 if (add_to_worklist) { 565 phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis 566 } 567 568 if( cnt <= 1 ) { // Only 1 path in? 569 set_req(0, NULL); // Null control input for region copy 570 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is. 571 // No inputs or all inputs are NULL. 572 return NULL; 573 } else if (can_reshape) { // Optimization phase - remove the node 574 PhaseIterGVN *igvn = phase->is_IterGVN(); 575 // Strip mined (inner) loop is going away, remove outer loop. 576 if (is_CountedLoop() && 577 as_Loop()->is_strip_mined()) { 578 Node* outer_sfpt = as_CountedLoop()->outer_safepoint(); 579 Node* outer_out = as_CountedLoop()->outer_loop_exit(); 580 if (outer_sfpt != NULL && outer_out != NULL) { 581 Node* in = outer_sfpt->in(0); 582 igvn->replace_node(outer_out, in); 583 LoopNode* outer = as_CountedLoop()->outer_loop(); 584 igvn->replace_input_of(outer, LoopNode::LoopBackControl, igvn->C->top()); 585 } 586 } 587 Node *parent_ctrl; 588 if( cnt == 0 ) { 589 assert( req() == 1, "no inputs expected" ); 590 // During IGVN phase such region will be subsumed by TOP node 591 // so region's phis will have TOP as control node. 592 // Kill phis here to avoid it. PhiNode::is_copy() will be always false. 593 // Also set other user's input to top. 594 parent_ctrl = phase->C->top(); 595 } else { 596 // The fallthrough case since we already checked dead loops above. 597 parent_ctrl = in(1); 598 assert(parent_ctrl != NULL, "Region is a copy of some non-null control"); 599 assert(!igvn->eqv(parent_ctrl, this), "Close dead loop"); 600 } 601 if (!add_to_worklist) 602 igvn->add_users_to_worklist(this); // Check for further allowed opts 603 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) { 604 Node* n = last_out(i); 605 igvn->hash_delete(n); // Remove from worklist before modifying edges 606 if( n->is_Phi() ) { // Collapse all Phis 607 // Eagerly replace phis to avoid copies generation. 608 Node* in; 609 if( cnt == 0 ) { 610 assert( n->req() == 1, "No data inputs expected" ); 611 in = parent_ctrl; // replaced by top 612 } else { 613 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" ); 614 in = n->in(1); // replaced by unique input 615 if( n->as_Phi()->is_unsafe_data_reference(in) ) 616 in = phase->C->top(); // replaced by top 617 } 618 igvn->replace_node(n, in); 619 } 620 else if( n->is_Region() ) { // Update all incoming edges 621 assert( !igvn->eqv(n, this), "Must be removed from DefUse edges"); 622 uint uses_found = 0; 623 for( uint k=1; k < n->req(); k++ ) { 624 if( n->in(k) == this ) { 625 n->set_req(k, parent_ctrl); 626 uses_found++; 627 } 628 } 629 if( uses_found > 1 ) { // (--i) done at the end of the loop. 630 i -= (uses_found - 1); 631 } 632 } 633 else { 634 assert( igvn->eqv(n->in(0), this), "Expect RegionNode to be control parent"); 635 n->set_req(0, parent_ctrl); 636 } 637 #ifdef ASSERT 638 for( uint k=0; k < n->req(); k++ ) { 639 assert( !igvn->eqv(n->in(k), this), "All uses of RegionNode should be gone"); 640 } 641 #endif 642 } 643 // Remove the RegionNode itself from DefUse info 644 igvn->remove_dead_node(this); 645 return NULL; 646 } 647 return this; // Record progress 648 } 649 650 651 // If a Region flows into a Region, merge into one big happy merge. 652 if (can_reshape) { 653 Node *m = merge_region(this, phase); 654 if (m != NULL) return m; 655 } 656 657 // Check if this region is the root of a clipping idiom on floats 658 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) { 659 // Check that only one use is a Phi and that it simplifies to two constants + 660 PhiNode* phi = has_unique_phi(); 661 if (phi != NULL) { // One Phi user 662 // Check inputs to the Phi 663 ConNode *min; 664 ConNode *max; 665 Node *val; 666 uint min_idx; 667 uint max_idx; 668 uint val_idx; 669 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) { 670 IfNode *top_if; 671 IfNode *bot_if; 672 if( check_if_clipping( this, bot_if, top_if ) ) { 673 // Control pattern checks, now verify compares 674 Node *top_in = NULL; // value being compared against 675 Node *bot_in = NULL; 676 if( check_compare_clipping( true, bot_if, min, bot_in ) && 677 check_compare_clipping( false, top_if, max, top_in ) ) { 678 if( bot_in == top_in ) { 679 PhaseIterGVN *gvn = phase->is_IterGVN(); 680 assert( gvn != NULL, "Only had DefUse info in IterGVN"); 681 // Only remaining check is that bot_in == top_in == (Phi's val + mods) 682 683 // Check for the ConvF2INode 684 ConvF2INode *convf2i; 685 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) && 686 convf2i->in(1) == bot_in ) { 687 // Matched pattern, including LShiftI; RShiftI, replace with integer compares 688 // max test 689 Node *cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, min )); 690 Node *boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::lt )); 691 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt )); 692 Node *if_min= gvn->register_new_node_with_optimizer(new IfTrueNode (iff)); 693 Node *ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff)); 694 // min test 695 cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, max )); 696 boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::gt )); 697 iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt )); 698 Node *if_max= gvn->register_new_node_with_optimizer(new IfTrueNode (iff)); 699 ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff)); 700 // update input edges to region node 701 set_req_X( min_idx, if_min, gvn ); 702 set_req_X( max_idx, if_max, gvn ); 703 set_req_X( val_idx, ifF, gvn ); 704 // remove unnecessary 'LShiftI; RShiftI' idiom 705 gvn->hash_delete(phi); 706 phi->set_req_X( val_idx, convf2i, gvn ); 707 gvn->hash_find_insert(phi); 708 // Return transformed region node 709 return this; 710 } 711 } 712 } 713 } 714 } 715 } 716 } 717 718 return modified ? this : NULL; 719 } 720 721 722 723 const RegMask &RegionNode::out_RegMask() const { 724 return RegMask::Empty; 725 } 726 727 // Find the one non-null required input. RegionNode only 728 Node *Node::nonnull_req() const { 729 assert( is_Region(), "" ); 730 for( uint i = 1; i < _cnt; i++ ) 731 if( in(i) ) 732 return in(i); 733 ShouldNotReachHere(); 734 return NULL; 735 } 736 737 738 //============================================================================= 739 // note that these functions assume that the _adr_type field is flattened 740 uint PhiNode::hash() const { 741 const Type* at = _adr_type; 742 return TypeNode::hash() + (at ? at->hash() : 0); 743 } 744 uint PhiNode::cmp( const Node &n ) const { 745 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type; 746 } 747 static inline 748 const TypePtr* flatten_phi_adr_type(const TypePtr* at) { 749 if (at == NULL || at == TypePtr::BOTTOM) return at; 750 return Compile::current()->alias_type(at)->adr_type(); 751 } 752 753 //----------------------------make--------------------------------------------- 754 // create a new phi with edges matching r and set (initially) to x 755 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) { 756 uint preds = r->req(); // Number of predecessor paths 757 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at"); 758 PhiNode* p = new PhiNode(r, t, at); 759 for (uint j = 1; j < preds; j++) { 760 // Fill in all inputs, except those which the region does not yet have 761 if (r->in(j) != NULL) 762 p->init_req(j, x); 763 } 764 return p; 765 } 766 PhiNode* PhiNode::make(Node* r, Node* x) { 767 const Type* t = x->bottom_type(); 768 const TypePtr* at = NULL; 769 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type()); 770 return make(r, x, t, at); 771 } 772 PhiNode* PhiNode::make_blank(Node* r, Node* x) { 773 const Type* t = x->bottom_type(); 774 const TypePtr* at = NULL; 775 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type()); 776 return new PhiNode(r, t, at); 777 } 778 779 780 //------------------------slice_memory----------------------------------------- 781 // create a new phi with narrowed memory type 782 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const { 783 PhiNode* mem = (PhiNode*) clone(); 784 *(const TypePtr**)&mem->_adr_type = adr_type; 785 // convert self-loops, or else we get a bad graph 786 for (uint i = 1; i < req(); i++) { 787 if ((const Node*)in(i) == this) mem->set_req(i, mem); 788 } 789 mem->verify_adr_type(); 790 return mem; 791 } 792 793 //------------------------split_out_instance----------------------------------- 794 // Split out an instance type from a bottom phi. 795 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const { 796 const TypeOopPtr *t_oop = at->isa_oopptr(); 797 assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr"); 798 const TypePtr *t = adr_type(); 799 assert(type() == Type::MEMORY && 800 (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM || 801 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() && 802 t->is_oopptr()->cast_to_exactness(true) 803 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr()) 804 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop), 805 "bottom or raw memory required"); 806 807 // Check if an appropriate node already exists. 808 Node *region = in(0); 809 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) { 810 Node* use = region->fast_out(k); 811 if( use->is_Phi()) { 812 PhiNode *phi2 = use->as_Phi(); 813 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) { 814 return phi2; 815 } 816 } 817 } 818 Compile *C = igvn->C; 819 Arena *a = Thread::current()->resource_area(); 820 Node_Array node_map = new Node_Array(a); 821 Node_Stack stack(a, C->live_nodes() >> 4); 822 PhiNode *nphi = slice_memory(at); 823 igvn->register_new_node_with_optimizer( nphi ); 824 node_map.map(_idx, nphi); 825 stack.push((Node *)this, 1); 826 while(!stack.is_empty()) { 827 PhiNode *ophi = stack.node()->as_Phi(); 828 uint i = stack.index(); 829 assert(i >= 1, "not control edge"); 830 stack.pop(); 831 nphi = node_map[ophi->_idx]->as_Phi(); 832 for (; i < ophi->req(); i++) { 833 Node *in = ophi->in(i); 834 if (in == NULL || igvn->type(in) == Type::TOP) 835 continue; 836 Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, NULL, igvn); 837 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL; 838 if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) { 839 opt = node_map[optphi->_idx]; 840 if (opt == NULL) { 841 stack.push(ophi, i); 842 nphi = optphi->slice_memory(at); 843 igvn->register_new_node_with_optimizer( nphi ); 844 node_map.map(optphi->_idx, nphi); 845 ophi = optphi; 846 i = 0; // will get incremented at top of loop 847 continue; 848 } 849 } 850 nphi->set_req(i, opt); 851 } 852 } 853 return nphi; 854 } 855 856 //------------------------verify_adr_type-------------------------------------- 857 #ifdef ASSERT 858 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const { 859 if (visited.test_set(_idx)) return; //already visited 860 861 // recheck constructor invariants: 862 verify_adr_type(false); 863 864 // recheck local phi/phi consistency: 865 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM, 866 "adr_type must be consistent across phi nest"); 867 868 // walk around 869 for (uint i = 1; i < req(); i++) { 870 Node* n = in(i); 871 if (n == NULL) continue; 872 const Node* np = in(i); 873 if (np->is_Phi()) { 874 np->as_Phi()->verify_adr_type(visited, at); 875 } else if (n->bottom_type() == Type::TOP 876 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) { 877 // ignore top inputs 878 } else { 879 const TypePtr* nat = flatten_phi_adr_type(n->adr_type()); 880 // recheck phi/non-phi consistency at leaves: 881 assert((nat != NULL) == (at != NULL), ""); 882 assert(nat == at || nat == TypePtr::BOTTOM, 883 "adr_type must be consistent at leaves of phi nest"); 884 } 885 } 886 } 887 888 // Verify a whole nest of phis rooted at this one. 889 void PhiNode::verify_adr_type(bool recursive) const { 890 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error 891 if (Node::in_dump()) return; // muzzle asserts when printing 892 893 assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only"); 894 895 if (!VerifyAliases) return; // verify thoroughly only if requested 896 897 assert(_adr_type == flatten_phi_adr_type(_adr_type), 898 "Phi::adr_type must be pre-normalized"); 899 900 if (recursive) { 901 VectorSet visited(Thread::current()->resource_area()); 902 verify_adr_type(visited, _adr_type); 903 } 904 } 905 #endif 906 907 908 //------------------------------Value------------------------------------------ 909 // Compute the type of the PhiNode 910 const Type* PhiNode::Value(PhaseGVN* phase) const { 911 Node *r = in(0); // RegionNode 912 if( !r ) // Copy or dead 913 return in(1) ? phase->type(in(1)) : Type::TOP; 914 915 // Note: During parsing, phis are often transformed before their regions. 916 // This means we have to use type_or_null to defend against untyped regions. 917 if( phase->type_or_null(r) == Type::TOP ) // Dead code? 918 return Type::TOP; 919 920 // Check for trip-counted loop. If so, be smarter. 921 CountedLoopNode* l = r->is_CountedLoop() ? r->as_CountedLoop() : NULL; 922 if (l && ((const Node*)l->phi() == this)) { // Trip counted loop! 923 // protect against init_trip() or limit() returning NULL 924 if (l->can_be_counted_loop(phase)) { 925 const Node *init = l->init_trip(); 926 const Node *limit = l->limit(); 927 const Node* stride = l->stride(); 928 if (init != NULL && limit != NULL && stride != NULL) { 929 const TypeInt* lo = phase->type(init)->isa_int(); 930 const TypeInt* hi = phase->type(limit)->isa_int(); 931 const TypeInt* stride_t = phase->type(stride)->isa_int(); 932 if (lo != NULL && hi != NULL && stride_t != NULL) { // Dying loops might have TOP here 933 assert(stride_t->_hi >= stride_t->_lo, "bad stride type"); 934 BoolTest::mask bt = l->loopexit()->test_trip(); 935 // If the loop exit condition is "not equal", the condition 936 // would not trigger if init > limit (if stride > 0) or if 937 // init < limit if (stride > 0) so we can't deduce bounds 938 // for the iv from the exit condition. 939 if (bt != BoolTest::ne) { 940 if (stride_t->_hi < 0) { // Down-counter loop 941 swap(lo, hi); 942 return TypeInt::make(MIN2(lo->_lo, hi->_lo) , hi->_hi, 3); 943 } else if (stride_t->_lo >= 0) { 944 return TypeInt::make(lo->_lo, MAX2(lo->_hi, hi->_hi), 3); 945 } 946 } 947 } 948 } 949 } else if (l->in(LoopNode::LoopBackControl) != NULL && 950 in(LoopNode::EntryControl) != NULL && 951 phase->type(l->in(LoopNode::LoopBackControl)) == Type::TOP) { 952 // During CCP, if we saturate the type of a counted loop's Phi 953 // before the special code for counted loop above has a chance 954 // to run (that is as long as the type of the backedge's control 955 // is top), we might end up with non monotonic types 956 return phase->type(in(LoopNode::EntryControl))->filter_speculative(_type); 957 } 958 } 959 960 // Until we have harmony between classes and interfaces in the type 961 // lattice, we must tread carefully around phis which implicitly 962 // convert the one to the other. 963 const TypePtr* ttp = _type->make_ptr(); 964 const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL; 965 const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_klassptr() : NULL; 966 bool is_intf = false; 967 if (ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) { 968 is_intf = true; 969 } else if (ttkp != NULL && ttkp->is_loaded() && ttkp->klass()->is_interface()) { 970 is_intf = true; 971 } 972 973 // Default case: merge all inputs 974 const Type *t = Type::TOP; // Merged type starting value 975 for (uint i = 1; i < req(); ++i) {// For all paths in 976 // Reachable control path? 977 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) { 978 const Type* ti = phase->type(in(i)); 979 // We assume that each input of an interface-valued Phi is a true 980 // subtype of that interface. This might not be true of the meet 981 // of all the input types. The lattice is not distributive in 982 // such cases. Ward off asserts in type.cpp by refusing to do 983 // meets between interfaces and proper classes. 984 const TypePtr* tip = ti->make_ptr(); 985 const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL; 986 if (tiip) { 987 bool ti_is_intf = false; 988 ciKlass* k = tiip->klass(); 989 if (k->is_loaded() && k->is_interface()) 990 ti_is_intf = true; 991 if (is_intf != ti_is_intf) 992 { t = _type; break; } 993 } 994 t = t->meet_speculative(ti); 995 } 996 } 997 998 // The worst-case type (from ciTypeFlow) should be consistent with "t". 999 // That is, we expect that "t->higher_equal(_type)" holds true. 1000 // There are various exceptions: 1001 // - Inputs which are phis might in fact be widened unnecessarily. 1002 // For example, an input might be a widened int while the phi is a short. 1003 // - Inputs might be BotPtrs but this phi is dependent on a null check, 1004 // and postCCP has removed the cast which encodes the result of the check. 1005 // - The type of this phi is an interface, and the inputs are classes. 1006 // - Value calls on inputs might produce fuzzy results. 1007 // (Occurrences of this case suggest improvements to Value methods.) 1008 // 1009 // It is not possible to see Type::BOTTOM values as phi inputs, 1010 // because the ciTypeFlow pre-pass produces verifier-quality types. 1011 const Type* ft = t->filter_speculative(_type); // Worst case type 1012 1013 #ifdef ASSERT 1014 // The following logic has been moved into TypeOopPtr::filter. 1015 const Type* jt = t->join_speculative(_type); 1016 if (jt->empty()) { // Emptied out??? 1017 1018 // Check for evil case of 't' being a class and '_type' expecting an 1019 // interface. This can happen because the bytecodes do not contain 1020 // enough type info to distinguish a Java-level interface variable 1021 // from a Java-level object variable. If we meet 2 classes which 1022 // both implement interface I, but their meet is at 'j/l/O' which 1023 // doesn't implement I, we have no way to tell if the result should 1024 // be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows 1025 // into a Phi which "knows" it's an Interface type we'll have to 1026 // uplift the type. 1027 if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) { 1028 assert(ft == _type, ""); // Uplift to interface 1029 } else if (!t->empty() && ttkp != NULL && ttkp->is_loaded() && ttkp->klass()->is_interface()) { 1030 assert(ft == _type, ""); // Uplift to interface 1031 } else { 1032 // We also have to handle 'evil cases' of interface- vs. class-arrays 1033 Type::get_arrays_base_elements(jt, _type, NULL, &ttip); 1034 if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) { 1035 assert(ft == _type, ""); // Uplift to array of interface 1036 } else { 1037 // Otherwise it's something stupid like non-overlapping int ranges 1038 // found on dying counted loops. 1039 assert(ft == Type::TOP, ""); // Canonical empty value 1040 } 1041 } 1042 } 1043 1044 else { 1045 1046 // If we have an interface-typed Phi and we narrow to a class type, the join 1047 // should report back the class. However, if we have a J/L/Object 1048 // class-typed Phi and an interface flows in, it's possible that the meet & 1049 // join report an interface back out. This isn't possible but happens 1050 // because the type system doesn't interact well with interfaces. 1051 const TypePtr *jtp = jt->make_ptr(); 1052 const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL; 1053 const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_klassptr() : NULL; 1054 if( jtip && ttip ) { 1055 if( jtip->is_loaded() && jtip->klass()->is_interface() && 1056 ttip->is_loaded() && !ttip->klass()->is_interface() ) { 1057 assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) || 1058 ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), ""); 1059 jt = ft; 1060 } 1061 } 1062 if( jtkp && ttkp ) { 1063 if( jtkp->is_loaded() && jtkp->klass()->is_interface() && 1064 !jtkp->klass_is_exact() && // Keep exact interface klass (6894807) 1065 ttkp->is_loaded() && !ttkp->klass()->is_interface() ) { 1066 assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) || 1067 ft->isa_narrowklass() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), ""); 1068 jt = ft; 1069 } 1070 } 1071 if (jt != ft && jt->base() == ft->base()) { 1072 if (jt->isa_int() && 1073 jt->is_int()->_lo == ft->is_int()->_lo && 1074 jt->is_int()->_hi == ft->is_int()->_hi) 1075 jt = ft; 1076 if (jt->isa_long() && 1077 jt->is_long()->_lo == ft->is_long()->_lo && 1078 jt->is_long()->_hi == ft->is_long()->_hi) 1079 jt = ft; 1080 } 1081 if (jt != ft) { 1082 tty->print("merge type: "); t->dump(); tty->cr(); 1083 tty->print("kill type: "); _type->dump(); tty->cr(); 1084 tty->print("join type: "); jt->dump(); tty->cr(); 1085 tty->print("filter type: "); ft->dump(); tty->cr(); 1086 } 1087 assert(jt == ft, ""); 1088 } 1089 #endif //ASSERT 1090 1091 // Deal with conversion problems found in data loops. 1092 ft = phase->saturate(ft, phase->type_or_null(this), _type); 1093 1094 return ft; 1095 } 1096 1097 1098 //------------------------------is_diamond_phi--------------------------------- 1099 // Does this Phi represent a simple well-shaped diamond merge? Return the 1100 // index of the true path or 0 otherwise. 1101 // If check_control_only is true, do not inspect the If node at the 1102 // top, and return -1 (not an edge number) on success. 1103 int PhiNode::is_diamond_phi(bool check_control_only) const { 1104 // Check for a 2-path merge 1105 Node *region = in(0); 1106 if( !region ) return 0; 1107 if( region->req() != 3 ) return 0; 1108 if( req() != 3 ) return 0; 1109 // Check that both paths come from the same If 1110 Node *ifp1 = region->in(1); 1111 Node *ifp2 = region->in(2); 1112 if( !ifp1 || !ifp2 ) return 0; 1113 Node *iff = ifp1->in(0); 1114 if( !iff || !iff->is_If() ) return 0; 1115 if( iff != ifp2->in(0) ) return 0; 1116 if (check_control_only) return -1; 1117 // Check for a proper bool/cmp 1118 const Node *b = iff->in(1); 1119 if( !b->is_Bool() ) return 0; 1120 const Node *cmp = b->in(1); 1121 if( !cmp->is_Cmp() ) return 0; 1122 1123 // Check for branching opposite expected 1124 if( ifp2->Opcode() == Op_IfTrue ) { 1125 assert( ifp1->Opcode() == Op_IfFalse, "" ); 1126 return 2; 1127 } else { 1128 assert( ifp1->Opcode() == Op_IfTrue, "" ); 1129 return 1; 1130 } 1131 } 1132 1133 //----------------------------check_cmove_id----------------------------------- 1134 // Check for CMove'ing a constant after comparing against the constant. 1135 // Happens all the time now, since if we compare equality vs a constant in 1136 // the parser, we "know" the variable is constant on one path and we force 1137 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a 1138 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more 1139 // general in that we don't need constants. Since CMove's are only inserted 1140 // in very special circumstances, we do it here on generic Phi's. 1141 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) { 1142 assert(true_path !=0, "only diamond shape graph expected"); 1143 1144 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1145 // phi->region->if_proj->ifnode->bool->cmp 1146 Node* region = in(0); 1147 Node* iff = region->in(1)->in(0); 1148 BoolNode* b = iff->in(1)->as_Bool(); 1149 Node* cmp = b->in(1); 1150 Node* tval = in(true_path); 1151 Node* fval = in(3-true_path); 1152 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b); 1153 if (id == NULL) 1154 return NULL; 1155 1156 // Either value might be a cast that depends on a branch of 'iff'. 1157 // Since the 'id' value will float free of the diamond, either 1158 // decast or return failure. 1159 Node* ctl = id->in(0); 1160 if (ctl != NULL && ctl->in(0) == iff) { 1161 if (id->is_ConstraintCast()) { 1162 return id->in(1); 1163 } else { 1164 // Don't know how to disentangle this value. 1165 return NULL; 1166 } 1167 } 1168 1169 return id; 1170 } 1171 1172 //------------------------------Identity--------------------------------------- 1173 // Check for Region being Identity. 1174 Node* PhiNode::Identity(PhaseGVN* phase) { 1175 // Check for no merging going on 1176 // (There used to be special-case code here when this->region->is_Loop. 1177 // It would check for a tributary phi on the backedge that the main phi 1178 // trivially, perhaps with a single cast. The unique_input method 1179 // does all this and more, by reducing such tributaries to 'this'.) 1180 Node* uin = unique_input(phase, false); 1181 if (uin != NULL) { 1182 return uin; 1183 } 1184 1185 int true_path = is_diamond_phi(); 1186 if (true_path != 0) { 1187 Node* id = is_cmove_id(phase, true_path); 1188 if (id != NULL) return id; 1189 } 1190 1191 return this; // No identity 1192 } 1193 1194 //-----------------------------unique_input------------------------------------ 1195 // Find the unique value, discounting top, self-loops, and casts. 1196 // Return top if there are no inputs, and self if there are multiple. 1197 Node* PhiNode::unique_input(PhaseTransform* phase, bool uncast) { 1198 // 1) One unique direct input, 1199 // or if uncast is true: 1200 // 2) some of the inputs have an intervening ConstraintCast 1201 // 3) an input is a self loop 1202 // 1203 // 1) input or 2) input or 3) input __ 1204 // / \ / \ \ / \ 1205 // \ / | cast phi cast 1206 // phi \ / / \ / 1207 // phi / -- 1208 1209 Node* r = in(0); // RegionNode 1210 if (r == NULL) return in(1); // Already degraded to a Copy 1211 Node* input = NULL; // The unique direct input (maybe uncasted = ConstraintCasts removed) 1212 1213 for (uint i = 1, cnt = req(); i < cnt; ++i) { 1214 Node* rc = r->in(i); 1215 if (rc == NULL || phase->type(rc) == Type::TOP) 1216 continue; // ignore unreachable control path 1217 Node* n = in(i); 1218 if (n == NULL) 1219 continue; 1220 Node* un = n; 1221 if (uncast) { 1222 #ifdef ASSERT 1223 Node* m = un->uncast(); 1224 #endif 1225 while (un != NULL && un->req() == 2 && un->is_ConstraintCast()) { 1226 Node* next = un->in(1); 1227 if (phase->type(next)->isa_rawptr() && phase->type(un)->isa_oopptr()) { 1228 // risk exposing raw ptr at safepoint 1229 break; 1230 } 1231 un = next; 1232 } 1233 assert(m == un || un->in(1) == m, "Only expected at CheckCastPP from allocation"); 1234 } 1235 if (un == NULL || un == this || phase->type(un) == Type::TOP) { 1236 continue; // ignore if top, or in(i) and "this" are in a data cycle 1237 } 1238 // Check for a unique input (maybe uncasted) 1239 if (input == NULL) { 1240 input = un; 1241 } else if (input != un) { 1242 input = NodeSentinel; // no unique input 1243 } 1244 } 1245 if (input == NULL) { 1246 return phase->C->top(); // no inputs 1247 } 1248 1249 if (input != NodeSentinel) { 1250 return input; // one unique direct input 1251 } 1252 1253 // Nothing. 1254 return NULL; 1255 } 1256 1257 //------------------------------is_x2logic------------------------------------- 1258 // Check for simple convert-to-boolean pattern 1259 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1) 1260 // Convert Phi to an ConvIB. 1261 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) { 1262 assert(true_path !=0, "only diamond shape graph expected"); 1263 // Convert the true/false index into an expected 0/1 return. 1264 // Map 2->0 and 1->1. 1265 int flipped = 2-true_path; 1266 1267 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1268 // phi->region->if_proj->ifnode->bool->cmp 1269 Node *region = phi->in(0); 1270 Node *iff = region->in(1)->in(0); 1271 BoolNode *b = (BoolNode*)iff->in(1); 1272 const CmpNode *cmp = (CmpNode*)b->in(1); 1273 1274 Node *zero = phi->in(1); 1275 Node *one = phi->in(2); 1276 const Type *tzero = phase->type( zero ); 1277 const Type *tone = phase->type( one ); 1278 1279 // Check for compare vs 0 1280 const Type *tcmp = phase->type(cmp->in(2)); 1281 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) { 1282 // Allow cmp-vs-1 if the other input is bounded by 0-1 1283 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) ) 1284 return NULL; 1285 flipped = 1-flipped; // Test is vs 1 instead of 0! 1286 } 1287 1288 // Check for setting zero/one opposite expected 1289 if( tzero == TypeInt::ZERO ) { 1290 if( tone == TypeInt::ONE ) { 1291 } else return NULL; 1292 } else if( tzero == TypeInt::ONE ) { 1293 if( tone == TypeInt::ZERO ) { 1294 flipped = 1-flipped; 1295 } else return NULL; 1296 } else return NULL; 1297 1298 // Check for boolean test backwards 1299 if( b->_test._test == BoolTest::ne ) { 1300 } else if( b->_test._test == BoolTest::eq ) { 1301 flipped = 1-flipped; 1302 } else return NULL; 1303 1304 // Build int->bool conversion 1305 Node *n = new Conv2BNode( cmp->in(1) ); 1306 if( flipped ) 1307 n = new XorINode( phase->transform(n), phase->intcon(1) ); 1308 1309 return n; 1310 } 1311 1312 //------------------------------is_cond_add------------------------------------ 1313 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;" 1314 // To be profitable the control flow has to disappear; there can be no other 1315 // values merging here. We replace the test-and-branch with: 1316 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by 1317 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'. 1318 // Then convert Y to 0-or-Y and finally add. 1319 // This is a key transform for SpecJava _201_compress. 1320 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) { 1321 assert(true_path !=0, "only diamond shape graph expected"); 1322 1323 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1324 // phi->region->if_proj->ifnode->bool->cmp 1325 RegionNode *region = (RegionNode*)phi->in(0); 1326 Node *iff = region->in(1)->in(0); 1327 BoolNode* b = iff->in(1)->as_Bool(); 1328 const CmpNode *cmp = (CmpNode*)b->in(1); 1329 1330 // Make sure only merging this one phi here 1331 if (region->has_unique_phi() != phi) return NULL; 1332 1333 // Make sure each arm of the diamond has exactly one output, which we assume 1334 // is the region. Otherwise, the control flow won't disappear. 1335 if (region->in(1)->outcnt() != 1) return NULL; 1336 if (region->in(2)->outcnt() != 1) return NULL; 1337 1338 // Check for "(P < Q)" of type signed int 1339 if (b->_test._test != BoolTest::lt) return NULL; 1340 if (cmp->Opcode() != Op_CmpI) return NULL; 1341 1342 Node *p = cmp->in(1); 1343 Node *q = cmp->in(2); 1344 Node *n1 = phi->in( true_path); 1345 Node *n2 = phi->in(3-true_path); 1346 1347 int op = n1->Opcode(); 1348 if( op != Op_AddI // Need zero as additive identity 1349 /*&&op != Op_SubI && 1350 op != Op_AddP && 1351 op != Op_XorI && 1352 op != Op_OrI*/ ) 1353 return NULL; 1354 1355 Node *x = n2; 1356 Node *y = NULL; 1357 if( x == n1->in(1) ) { 1358 y = n1->in(2); 1359 } else if( x == n1->in(2) ) { 1360 y = n1->in(1); 1361 } else return NULL; 1362 1363 // Not so profitable if compare and add are constants 1364 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() ) 1365 return NULL; 1366 1367 Node *cmplt = phase->transform( new CmpLTMaskNode(p,q) ); 1368 Node *j_and = phase->transform( new AndINode(cmplt,y) ); 1369 return new AddINode(j_and,x); 1370 } 1371 1372 //------------------------------is_absolute------------------------------------ 1373 // Check for absolute value. 1374 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) { 1375 assert(true_path !=0, "only diamond shape graph expected"); 1376 1377 int cmp_zero_idx = 0; // Index of compare input where to look for zero 1378 int phi_x_idx = 0; // Index of phi input where to find naked x 1379 1380 // ABS ends with the merge of 2 control flow paths. 1381 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely. 1382 int false_path = 3 - true_path; 1383 1384 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1385 // phi->region->if_proj->ifnode->bool->cmp 1386 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool(); 1387 1388 // Check bool sense 1389 switch( bol->_test._test ) { 1390 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break; 1391 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break; 1392 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break; 1393 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break; 1394 default: return NULL; break; 1395 } 1396 1397 // Test is next 1398 Node *cmp = bol->in(1); 1399 const Type *tzero = NULL; 1400 switch( cmp->Opcode() ) { 1401 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS 1402 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS 1403 default: return NULL; 1404 } 1405 1406 // Find zero input of compare; the other input is being abs'd 1407 Node *x = NULL; 1408 bool flip = false; 1409 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) { 1410 x = cmp->in(3 - cmp_zero_idx); 1411 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) { 1412 // The test is inverted, we should invert the result... 1413 x = cmp->in(cmp_zero_idx); 1414 flip = true; 1415 } else { 1416 return NULL; 1417 } 1418 1419 // Next get the 2 pieces being selected, one is the original value 1420 // and the other is the negated value. 1421 if( phi_root->in(phi_x_idx) != x ) return NULL; 1422 1423 // Check other phi input for subtract node 1424 Node *sub = phi_root->in(3 - phi_x_idx); 1425 1426 // Allow only Sub(0,X) and fail out for all others; Neg is not OK 1427 if( tzero == TypeF::ZERO ) { 1428 if( sub->Opcode() != Op_SubF || 1429 sub->in(2) != x || 1430 phase->type(sub->in(1)) != tzero ) return NULL; 1431 x = new AbsFNode(x); 1432 if (flip) { 1433 x = new SubFNode(sub->in(1), phase->transform(x)); 1434 } 1435 } else { 1436 if( sub->Opcode() != Op_SubD || 1437 sub->in(2) != x || 1438 phase->type(sub->in(1)) != tzero ) return NULL; 1439 x = new AbsDNode(x); 1440 if (flip) { 1441 x = new SubDNode(sub->in(1), phase->transform(x)); 1442 } 1443 } 1444 1445 return x; 1446 } 1447 1448 //------------------------------split_once------------------------------------- 1449 // Helper for split_flow_path 1450 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) { 1451 igvn->hash_delete(n); // Remove from hash before hacking edges 1452 1453 uint j = 1; 1454 for (uint i = phi->req()-1; i > 0; i--) { 1455 if (phi->in(i) == val) { // Found a path with val? 1456 // Add to NEW Region/Phi, no DU info 1457 newn->set_req( j++, n->in(i) ); 1458 // Remove from OLD Region/Phi 1459 n->del_req(i); 1460 } 1461 } 1462 1463 // Register the new node but do not transform it. Cannot transform until the 1464 // entire Region/Phi conglomerate has been hacked as a single huge transform. 1465 igvn->register_new_node_with_optimizer( newn ); 1466 1467 // Now I can point to the new node. 1468 n->add_req(newn); 1469 igvn->_worklist.push(n); 1470 } 1471 1472 //------------------------------split_flow_path-------------------------------- 1473 // Check for merging identical values and split flow paths 1474 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) { 1475 BasicType bt = phi->type()->basic_type(); 1476 if( bt == T_ILLEGAL || type2size[bt] <= 0 ) 1477 return NULL; // Bail out on funny non-value stuff 1478 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a 1479 return NULL; // third unequal input to be worth doing 1480 1481 // Scan for a constant 1482 uint i; 1483 for( i = 1; i < phi->req()-1; i++ ) { 1484 Node *n = phi->in(i); 1485 if( !n ) return NULL; 1486 if( phase->type(n) == Type::TOP ) return NULL; 1487 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN || n->Opcode() == Op_ConNKlass ) 1488 break; 1489 } 1490 if( i >= phi->req() ) // Only split for constants 1491 return NULL; 1492 1493 Node *val = phi->in(i); // Constant to split for 1494 uint hit = 0; // Number of times it occurs 1495 Node *r = phi->region(); 1496 1497 for( ; i < phi->req(); i++ ){ // Count occurrences of constant 1498 Node *n = phi->in(i); 1499 if( !n ) return NULL; 1500 if( phase->type(n) == Type::TOP ) return NULL; 1501 if( phi->in(i) == val ) { 1502 hit++; 1503 if (PhaseIdealLoop::find_predicate(r->in(i)) != NULL) { 1504 return NULL; // don't split loop entry path 1505 } 1506 } 1507 } 1508 1509 if( hit <= 1 || // Make sure we find 2 or more 1510 hit == phi->req()-1 ) // and not ALL the same value 1511 return NULL; 1512 1513 // Now start splitting out the flow paths that merge the same value. 1514 // Split first the RegionNode. 1515 PhaseIterGVN *igvn = phase->is_IterGVN(); 1516 RegionNode *newr = new RegionNode(hit+1); 1517 split_once(igvn, phi, val, r, newr); 1518 1519 // Now split all other Phis than this one 1520 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) { 1521 Node* phi2 = r->fast_out(k); 1522 if( phi2->is_Phi() && phi2->as_Phi() != phi ) { 1523 PhiNode *newphi = PhiNode::make_blank(newr, phi2); 1524 split_once(igvn, phi, val, phi2, newphi); 1525 } 1526 } 1527 1528 // Clean up this guy 1529 igvn->hash_delete(phi); 1530 for( i = phi->req()-1; i > 0; i-- ) { 1531 if( phi->in(i) == val ) { 1532 phi->del_req(i); 1533 } 1534 } 1535 phi->add_req(val); 1536 1537 return phi; 1538 } 1539 1540 //============================================================================= 1541 //------------------------------simple_data_loop_check------------------------- 1542 // Try to determining if the phi node in a simple safe/unsafe data loop. 1543 // Returns: 1544 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop }; 1545 // Safe - safe case when the phi and it's inputs reference only safe data 1546 // nodes; 1547 // Unsafe - the phi and it's inputs reference unsafe data nodes but there 1548 // is no reference back to the phi - need a graph walk 1549 // to determine if it is in a loop; 1550 // UnsafeLoop - unsafe case when the phi references itself directly or through 1551 // unsafe data node. 1552 // Note: a safe data node is a node which could/never reference itself during 1553 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP. 1554 // I mark Phi nodes as safe node not only because they can reference itself 1555 // but also to prevent mistaking the fallthrough case inside an outer loop 1556 // as dead loop when the phi references itselfs through an other phi. 1557 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const { 1558 // It is unsafe loop if the phi node references itself directly. 1559 if (in == (Node*)this) 1560 return UnsafeLoop; // Unsafe loop 1561 // Unsafe loop if the phi node references itself through an unsafe data node. 1562 // Exclude cases with null inputs or data nodes which could reference 1563 // itself (safe for dead loops). 1564 if (in != NULL && !in->is_dead_loop_safe()) { 1565 // Check inputs of phi's inputs also. 1566 // It is much less expensive then full graph walk. 1567 uint cnt = in->req(); 1568 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1; 1569 for (; i < cnt; ++i) { 1570 Node* m = in->in(i); 1571 if (m == (Node*)this) 1572 return UnsafeLoop; // Unsafe loop 1573 if (m != NULL && !m->is_dead_loop_safe()) { 1574 // Check the most common case (about 30% of all cases): 1575 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con). 1576 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL; 1577 if (m1 == (Node*)this) 1578 return UnsafeLoop; // Unsafe loop 1579 if (m1 != NULL && m1 == m->in(2) && 1580 m1->is_dead_loop_safe() && m->in(3)->is_Con()) { 1581 continue; // Safe case 1582 } 1583 // The phi references an unsafe node - need full analysis. 1584 return Unsafe; 1585 } 1586 } 1587 } 1588 return Safe; // Safe case - we can optimize the phi node. 1589 } 1590 1591 //------------------------------is_unsafe_data_reference----------------------- 1592 // If phi can be reached through the data input - it is data loop. 1593 bool PhiNode::is_unsafe_data_reference(Node *in) const { 1594 assert(req() > 1, ""); 1595 // First, check simple cases when phi references itself directly or 1596 // through an other node. 1597 LoopSafety safety = simple_data_loop_check(in); 1598 if (safety == UnsafeLoop) 1599 return true; // phi references itself - unsafe loop 1600 else if (safety == Safe) 1601 return false; // Safe case - phi could be replaced with the unique input. 1602 1603 // Unsafe case when we should go through data graph to determine 1604 // if the phi references itself. 1605 1606 ResourceMark rm; 1607 1608 Arena *a = Thread::current()->resource_area(); 1609 Node_List nstack(a); 1610 VectorSet visited(a); 1611 1612 nstack.push(in); // Start with unique input. 1613 visited.set(in->_idx); 1614 while (nstack.size() != 0) { 1615 Node* n = nstack.pop(); 1616 uint cnt = n->req(); 1617 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1; 1618 for (; i < cnt; i++) { 1619 Node* m = n->in(i); 1620 if (m == (Node*)this) { 1621 return true; // Data loop 1622 } 1623 if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases. 1624 if (!visited.test_set(m->_idx)) 1625 nstack.push(m); 1626 } 1627 } 1628 } 1629 return false; // The phi is not reachable from its inputs 1630 } 1631 1632 1633 //------------------------------Ideal------------------------------------------ 1634 // Return a node which is more "ideal" than the current node. Must preserve 1635 // the CFG, but we can still strip out dead paths. 1636 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1637 // The next should never happen after 6297035 fix. 1638 if( is_copy() ) // Already degraded to a Copy ? 1639 return NULL; // No change 1640 1641 Node *r = in(0); // RegionNode 1642 assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge"); 1643 1644 // Note: During parsing, phis are often transformed before their regions. 1645 // This means we have to use type_or_null to defend against untyped regions. 1646 if( phase->type_or_null(r) == Type::TOP ) // Dead code? 1647 return NULL; // No change 1648 1649 // If all inputs are value types, push the value type node down through the 1650 // phi because value type nodes should be merged through their input values. 1651 if (req() > 2 && in(1) != NULL && in(1)->is_ValueTypeBase() && (can_reshape || in(1)->is_ValueType())) { 1652 int opcode = in(1)->Opcode(); 1653 uint i = 2; 1654 for (; i < req() && in(i) && in(i)->is_ValueTypeBase(); i++) { 1655 assert(in(i)->Opcode() == opcode, "mixing pointers and values?"); 1656 } 1657 if (i == req()) { 1658 ValueTypeBaseNode* vt = in(1)->as_ValueTypeBase()->clone_with_phis(phase, in(0)); 1659 for (uint i = 2; i < req(); ++i) { 1660 vt->merge_with(phase, in(i)->as_ValueTypeBase(), i, i == (req()-1)); 1661 } 1662 return vt; 1663 } 1664 } 1665 1666 if (type()->isa_valuetypeptr() && can_reshape) { 1667 // If the Phi merges the result from a mix of constant and non 1668 // constant method handles, only some of its inputs are 1669 // ValueTypePtr nodes and we can't push the ValueTypePtr node down 1670 // to remove the need for allocations. This if fixed by transforming: 1671 // 1672 // (Phi ValueTypePtr#1 Node#2) to (Phi ValueTypePtr#1 CheckCastPP#2) 1673 // 1674 // Then pushing the CheckCastPP up through Phis until it reaches 1675 // the non constant method handle call. The type of the return 1676 // value is then known from the type of the CheckCastPP. A 1677 // ValueTypePtr can be created by adding projections to the call 1678 // for all values being returned. See 1679 // CheckCastPPNode::Ideal(). That ValueTypePtr node can then be 1680 // pushed down through Phis. 1681 const TypeValueTypePtr* vtptr = NULL; 1682 for (uint i = 1; i < req(); i++) { 1683 if (in(i) != NULL && in(i)->is_ValueTypePtr()) { 1684 const TypeValueTypePtr* t = phase->type(in(i))->is_valuetypeptr(); 1685 t = t->cast_to_ptr_type(TypePtr::BotPTR)->is_valuetypeptr(); 1686 if (vtptr == NULL) { 1687 vtptr = t; 1688 } else { 1689 assert(vtptr == t, "Phi should merge identical value types"); 1690 } 1691 } else { 1692 assert(in(i) == NULL || vtptr == NULL || phase->type(in(i))->higher_equal(vtptr) || phase->type(in(i)) == Type::TOP || 1693 phase->type(in(i))->is_valuetypeptr()->is__Value(), "bad type"); 1694 } 1695 } 1696 if (vtptr != NULL) { 1697 // One input is a value type. All inputs must have the same type. 1698 bool progress = false; 1699 PhaseIterGVN* igvn = phase->is_IterGVN(); 1700 for (uint i = 1; i < req(); i++) { 1701 if (in(i) != NULL && !in(i)->is_Con() && !phase->type(in(i))->higher_equal(vtptr)) { 1702 // Can't transform because CheckCastPPNode::Identity can 1703 // push the cast up through another Phi and cause this same 1704 // transformation to run again, indefinitely 1705 Node* cast = igvn->register_new_node_with_optimizer(new CheckCastPPNode(NULL, in(i), vtptr)); 1706 set_req(i, cast); 1707 progress = true; 1708 } 1709 } 1710 if (progress) { 1711 return this; 1712 } 1713 } 1714 } 1715 1716 Node *top = phase->C->top(); 1717 bool new_phi = (outcnt() == 0); // transforming new Phi 1718 // No change for igvn if new phi is not hooked 1719 if (new_phi && can_reshape) 1720 return NULL; 1721 1722 // The are 2 situations when only one valid phi's input is left 1723 // (in addition to Region input). 1724 // One: region is not loop - replace phi with this input. 1725 // Two: region is loop - replace phi with top since this data path is dead 1726 // and we need to break the dead data loop. 1727 Node* progress = NULL; // Record if any progress made 1728 for( uint j = 1; j < req(); ++j ){ // For all paths in 1729 // Check unreachable control paths 1730 Node* rc = r->in(j); 1731 Node* n = in(j); // Get the input 1732 if (rc == NULL || phase->type(rc) == Type::TOP) { 1733 if (n != top) { // Not already top? 1734 PhaseIterGVN *igvn = phase->is_IterGVN(); 1735 if (can_reshape && igvn != NULL) { 1736 igvn->_worklist.push(r); 1737 } 1738 set_req(j, top); // Nuke it down 1739 progress = this; // Record progress 1740 } 1741 } 1742 } 1743 1744 if (can_reshape && outcnt() == 0) { 1745 // set_req() above may kill outputs if Phi is referenced 1746 // only by itself on the dead (top) control path. 1747 return top; 1748 } 1749 1750 bool uncasted = false; 1751 Node* uin = unique_input(phase, false); 1752 if (uin == NULL && can_reshape) { 1753 uncasted = true; 1754 uin = unique_input(phase, true); 1755 } 1756 if (uin == top) { // Simplest case: no alive inputs. 1757 if (can_reshape) // IGVN transformation 1758 return top; 1759 else 1760 return NULL; // Identity will return TOP 1761 } else if (uin != NULL) { 1762 // Only one not-NULL unique input path is left. 1763 // Determine if this input is backedge of a loop. 1764 // (Skip new phis which have no uses and dead regions). 1765 if (outcnt() > 0 && r->in(0) != NULL) { 1766 // First, take the short cut when we know it is a loop and 1767 // the EntryControl data path is dead. 1768 // Loop node may have only one input because entry path 1769 // is removed in PhaseIdealLoop::Dominators(). 1770 assert(!r->is_Loop() || r->req() <= 3, "Loop node should have 3 or less inputs"); 1771 bool is_loop = (r->is_Loop() && r->req() == 3); 1772 // Then, check if there is a data loop when phi references itself directly 1773 // or through other data nodes. 1774 if ((is_loop && !uin->eqv_uncast(in(LoopNode::EntryControl))) || 1775 (!is_loop && is_unsafe_data_reference(uin))) { 1776 // Break this data loop to avoid creation of a dead loop. 1777 if (can_reshape) { 1778 return top; 1779 } else { 1780 // We can't return top if we are in Parse phase - cut inputs only 1781 // let Identity to handle the case. 1782 replace_edge(uin, top); 1783 return NULL; 1784 } 1785 } 1786 } 1787 1788 if (uncasted) { 1789 // Add cast nodes between the phi to be removed and its unique input. 1790 // Wait until after parsing for the type information to propagate from the casts. 1791 assert(can_reshape, "Invalid during parsing"); 1792 const Type* phi_type = bottom_type(); 1793 assert(phi_type->isa_int() || phi_type->isa_ptr(), "bad phi type"); 1794 // Add casts to carry the control dependency of the Phi that is 1795 // going away 1796 Node* cast = NULL; 1797 if (phi_type->isa_int()) { 1798 cast = ConstraintCastNode::make_cast(Op_CastII, r, uin, phi_type, true); 1799 } else { 1800 const Type* uin_type = phase->type(uin); 1801 if (!phi_type->isa_oopptr() && !uin_type->isa_oopptr()) { 1802 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true); 1803 } else { 1804 // Use a CastPP for a cast to not null and a CheckCastPP for 1805 // a cast to a new klass (and both if both null-ness and 1806 // klass change). 1807 1808 // If the type of phi is not null but the type of uin may be 1809 // null, uin's type must be casted to not null 1810 if (phi_type->join(TypePtr::NOTNULL) == phi_type->remove_speculative() && 1811 uin_type->join(TypePtr::NOTNULL) != uin_type->remove_speculative()) { 1812 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, TypePtr::NOTNULL, true); 1813 } 1814 1815 // If the type of phi and uin, both casted to not null, 1816 // differ the klass of uin must be (check)cast'ed to match 1817 // that of phi 1818 if (phi_type->join_speculative(TypePtr::NOTNULL) != uin_type->join_speculative(TypePtr::NOTNULL)) { 1819 Node* n = uin; 1820 if (cast != NULL) { 1821 cast = phase->transform(cast); 1822 n = cast; 1823 } 1824 cast = ConstraintCastNode::make_cast(Op_CheckCastPP, r, n, phi_type, true); 1825 } 1826 if (cast == NULL) { 1827 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true); 1828 } 1829 } 1830 } 1831 assert(cast != NULL, "cast should be set"); 1832 cast = phase->transform(cast); 1833 // set all inputs to the new cast(s) so the Phi is removed by Identity 1834 PhaseIterGVN* igvn = phase->is_IterGVN(); 1835 for (uint i = 1; i < req(); i++) { 1836 set_req_X(i, cast, igvn); 1837 } 1838 uin = cast; 1839 } 1840 1841 // One unique input. 1842 debug_only(Node* ident = Identity(phase)); 1843 // The unique input must eventually be detected by the Identity call. 1844 #ifdef ASSERT 1845 if (ident != uin && !ident->is_top()) { 1846 // print this output before failing assert 1847 r->dump(3); 1848 this->dump(3); 1849 ident->dump(); 1850 uin->dump(); 1851 } 1852 #endif 1853 assert(ident == uin || ident->is_top(), "Identity must clean this up"); 1854 return NULL; 1855 } 1856 1857 Node* opt = NULL; 1858 int true_path = is_diamond_phi(); 1859 if( true_path != 0 ) { 1860 // Check for CMove'ing identity. If it would be unsafe, 1861 // handle it here. In the safe case, let Identity handle it. 1862 Node* unsafe_id = is_cmove_id(phase, true_path); 1863 if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) ) 1864 opt = unsafe_id; 1865 1866 // Check for simple convert-to-boolean pattern 1867 if( opt == NULL ) 1868 opt = is_x2logic(phase, this, true_path); 1869 1870 // Check for absolute value 1871 if( opt == NULL ) 1872 opt = is_absolute(phase, this, true_path); 1873 1874 // Check for conditional add 1875 if( opt == NULL && can_reshape ) 1876 opt = is_cond_add(phase, this, true_path); 1877 1878 // These 4 optimizations could subsume the phi: 1879 // have to check for a dead data loop creation. 1880 if( opt != NULL ) { 1881 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) { 1882 // Found dead loop. 1883 if( can_reshape ) 1884 return top; 1885 // We can't return top if we are in Parse phase - cut inputs only 1886 // to stop further optimizations for this phi. Identity will return TOP. 1887 assert(req() == 3, "only diamond merge phi here"); 1888 set_req(1, top); 1889 set_req(2, top); 1890 return NULL; 1891 } else { 1892 return opt; 1893 } 1894 } 1895 } 1896 1897 // Check for merging identical values and split flow paths 1898 if (can_reshape) { 1899 opt = split_flow_path(phase, this); 1900 // This optimization only modifies phi - don't need to check for dead loop. 1901 assert(opt == NULL || phase->eqv(opt, this), "do not elide phi"); 1902 if (opt != NULL) return opt; 1903 } 1904 1905 if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) { 1906 // Try to undo Phi of AddP: 1907 // (Phi (AddP base base y) (AddP base2 base2 y)) 1908 // becomes: 1909 // newbase := (Phi base base2) 1910 // (AddP newbase newbase y) 1911 // 1912 // This occurs as a result of unsuccessful split_thru_phi and 1913 // interferes with taking advantage of addressing modes. See the 1914 // clone_shift_expressions code in matcher.cpp 1915 Node* addp = in(1); 1916 const Type* type = addp->in(AddPNode::Base)->bottom_type(); 1917 Node* y = addp->in(AddPNode::Offset); 1918 if (y != NULL && addp->in(AddPNode::Base) == addp->in(AddPNode::Address)) { 1919 // make sure that all the inputs are similar to the first one, 1920 // i.e. AddP with base == address and same offset as first AddP 1921 bool doit = true; 1922 for (uint i = 2; i < req(); i++) { 1923 if (in(i) == NULL || 1924 in(i)->Opcode() != Op_AddP || 1925 in(i)->in(AddPNode::Base) != in(i)->in(AddPNode::Address) || 1926 in(i)->in(AddPNode::Offset) != y) { 1927 doit = false; 1928 break; 1929 } 1930 // Accumulate type for resulting Phi 1931 type = type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type()); 1932 } 1933 Node* base = NULL; 1934 if (doit) { 1935 // Check for neighboring AddP nodes in a tree. 1936 // If they have a base, use that it. 1937 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) { 1938 Node* u = this->fast_out(k); 1939 if (u->is_AddP()) { 1940 Node* base2 = u->in(AddPNode::Base); 1941 if (base2 != NULL && !base2->is_top()) { 1942 if (base == NULL) 1943 base = base2; 1944 else if (base != base2) 1945 { doit = false; break; } 1946 } 1947 } 1948 } 1949 } 1950 if (doit) { 1951 if (base == NULL) { 1952 base = new PhiNode(in(0), type, NULL); 1953 for (uint i = 1; i < req(); i++) { 1954 base->init_req(i, in(i)->in(AddPNode::Base)); 1955 } 1956 phase->is_IterGVN()->register_new_node_with_optimizer(base); 1957 } 1958 return new AddPNode(base, base, y); 1959 } 1960 } 1961 } 1962 1963 // Split phis through memory merges, so that the memory merges will go away. 1964 // Piggy-back this transformation on the search for a unique input.... 1965 // It will be as if the merged memory is the unique value of the phi. 1966 // (Do not attempt this optimization unless parsing is complete. 1967 // It would make the parser's memory-merge logic sick.) 1968 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.) 1969 if (progress == NULL && can_reshape && type() == Type::MEMORY) { 1970 // see if this phi should be sliced 1971 uint merge_width = 0; 1972 bool saw_self = false; 1973 for( uint i=1; i<req(); ++i ) {// For all paths in 1974 Node *ii = in(i); 1975 // TOP inputs should not be counted as safe inputs because if the 1976 // Phi references itself through all other inputs then splitting the 1977 // Phi through memory merges would create dead loop at later stage. 1978 if (ii == top) { 1979 return NULL; // Delay optimization until graph is cleaned. 1980 } 1981 if (ii->is_MergeMem()) { 1982 MergeMemNode* n = ii->as_MergeMem(); 1983 merge_width = MAX2(merge_width, n->req()); 1984 saw_self = saw_self || phase->eqv(n->base_memory(), this); 1985 } 1986 } 1987 1988 // This restriction is temporarily necessary to ensure termination: 1989 if (!saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0; 1990 1991 if (merge_width > Compile::AliasIdxRaw) { 1992 // found at least one non-empty MergeMem 1993 const TypePtr* at = adr_type(); 1994 if (at != TypePtr::BOTTOM) { 1995 // Patch the existing phi to select an input from the merge: 1996 // Phi:AT1(...MergeMem(m0, m1, m2)...) into 1997 // Phi:AT1(...m1...) 1998 int alias_idx = phase->C->get_alias_index(at); 1999 for (uint i=1; i<req(); ++i) { 2000 Node *ii = in(i); 2001 if (ii->is_MergeMem()) { 2002 MergeMemNode* n = ii->as_MergeMem(); 2003 // compress paths and change unreachable cycles to TOP 2004 // If not, we can update the input infinitely along a MergeMem cycle 2005 // Equivalent code is in MemNode::Ideal_common 2006 Node *m = phase->transform(n); 2007 if (outcnt() == 0) { // Above transform() may kill us! 2008 return top; 2009 } 2010 // If transformed to a MergeMem, get the desired slice 2011 // Otherwise the returned node represents memory for every slice 2012 Node *new_mem = (m->is_MergeMem()) ? 2013 m->as_MergeMem()->memory_at(alias_idx) : m; 2014 // Update input if it is progress over what we have now 2015 if (new_mem != ii) { 2016 set_req(i, new_mem); 2017 progress = this; 2018 } 2019 } 2020 } 2021 } else { 2022 // We know that at least one MergeMem->base_memory() == this 2023 // (saw_self == true). If all other inputs also references this phi 2024 // (directly or through data nodes) - it is dead loop. 2025 bool saw_safe_input = false; 2026 for (uint j = 1; j < req(); ++j) { 2027 Node *n = in(j); 2028 if (n->is_MergeMem() && n->as_MergeMem()->base_memory() == this) 2029 continue; // skip known cases 2030 if (!is_unsafe_data_reference(n)) { 2031 saw_safe_input = true; // found safe input 2032 break; 2033 } 2034 } 2035 if (!saw_safe_input) 2036 return top; // all inputs reference back to this phi - dead loop 2037 2038 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into 2039 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...)) 2040 PhaseIterGVN *igvn = phase->is_IterGVN(); 2041 Node* hook = new Node(1); 2042 PhiNode* new_base = (PhiNode*) clone(); 2043 // Must eagerly register phis, since they participate in loops. 2044 if (igvn) { 2045 igvn->register_new_node_with_optimizer(new_base); 2046 hook->add_req(new_base); 2047 } 2048 MergeMemNode* result = MergeMemNode::make(new_base); 2049 for (uint i = 1; i < req(); ++i) { 2050 Node *ii = in(i); 2051 if (ii->is_MergeMem()) { 2052 MergeMemNode* n = ii->as_MergeMem(); 2053 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) { 2054 // If we have not seen this slice yet, make a phi for it. 2055 bool made_new_phi = false; 2056 if (mms.is_empty()) { 2057 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C)); 2058 made_new_phi = true; 2059 if (igvn) { 2060 igvn->register_new_node_with_optimizer(new_phi); 2061 hook->add_req(new_phi); 2062 } 2063 mms.set_memory(new_phi); 2064 } 2065 Node* phi = mms.memory(); 2066 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice"); 2067 phi->set_req(i, mms.memory2()); 2068 } 2069 } 2070 } 2071 // Distribute all self-loops. 2072 { // (Extra braces to hide mms.) 2073 for (MergeMemStream mms(result); mms.next_non_empty(); ) { 2074 Node* phi = mms.memory(); 2075 for (uint i = 1; i < req(); ++i) { 2076 if (phi->in(i) == this) phi->set_req(i, phi); 2077 } 2078 } 2079 } 2080 // now transform the new nodes, and return the mergemem 2081 for (MergeMemStream mms(result); mms.next_non_empty(); ) { 2082 Node* phi = mms.memory(); 2083 mms.set_memory(phase->transform(phi)); 2084 } 2085 if (igvn) { // Unhook. 2086 igvn->hash_delete(hook); 2087 for (uint i = 1; i < hook->req(); i++) { 2088 hook->set_req(i, NULL); 2089 } 2090 } 2091 // Replace self with the result. 2092 return result; 2093 } 2094 } 2095 // 2096 // Other optimizations on the memory chain 2097 // 2098 const TypePtr* at = adr_type(); 2099 for( uint i=1; i<req(); ++i ) {// For all paths in 2100 Node *ii = in(i); 2101 Node *new_in = MemNode::optimize_memory_chain(ii, at, NULL, phase); 2102 if (ii != new_in ) { 2103 set_req(i, new_in); 2104 progress = this; 2105 } 2106 } 2107 } 2108 2109 #ifdef _LP64 2110 // Push DecodeN/DecodeNKlass down through phi. 2111 // The rest of phi graph will transform by split EncodeP node though phis up. 2112 if ((UseCompressedOops || UseCompressedClassPointers) && can_reshape && progress == NULL) { 2113 bool may_push = true; 2114 bool has_decodeN = false; 2115 bool is_decodeN = false; 2116 for (uint i=1; i<req(); ++i) {// For all paths in 2117 Node *ii = in(i); 2118 if (ii->is_DecodeNarrowPtr() && ii->bottom_type() == bottom_type()) { 2119 // Do optimization if a non dead path exist. 2120 if (ii->in(1)->bottom_type() != Type::TOP) { 2121 has_decodeN = true; 2122 is_decodeN = ii->is_DecodeN(); 2123 } 2124 } else if (!ii->is_Phi()) { 2125 may_push = false; 2126 } 2127 } 2128 2129 if (has_decodeN && may_push) { 2130 PhaseIterGVN *igvn = phase->is_IterGVN(); 2131 // Make narrow type for new phi. 2132 const Type* narrow_t; 2133 if (is_decodeN) { 2134 narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr()); 2135 } else { 2136 narrow_t = TypeNarrowKlass::make(this->bottom_type()->is_ptr()); 2137 } 2138 PhiNode* new_phi = new PhiNode(r, narrow_t); 2139 uint orig_cnt = req(); 2140 for (uint i=1; i<req(); ++i) {// For all paths in 2141 Node *ii = in(i); 2142 Node* new_ii = NULL; 2143 if (ii->is_DecodeNarrowPtr()) { 2144 assert(ii->bottom_type() == bottom_type(), "sanity"); 2145 new_ii = ii->in(1); 2146 } else { 2147 assert(ii->is_Phi(), "sanity"); 2148 if (ii->as_Phi() == this) { 2149 new_ii = new_phi; 2150 } else { 2151 if (is_decodeN) { 2152 new_ii = new EncodePNode(ii, narrow_t); 2153 } else { 2154 new_ii = new EncodePKlassNode(ii, narrow_t); 2155 } 2156 igvn->register_new_node_with_optimizer(new_ii); 2157 } 2158 } 2159 new_phi->set_req(i, new_ii); 2160 } 2161 igvn->register_new_node_with_optimizer(new_phi, this); 2162 if (is_decodeN) { 2163 progress = new DecodeNNode(new_phi, bottom_type()); 2164 } else { 2165 progress = new DecodeNKlassNode(new_phi, bottom_type()); 2166 } 2167 } 2168 } 2169 #endif 2170 2171 return progress; // Return any progress 2172 } 2173 2174 //------------------------------is_tripcount----------------------------------- 2175 bool PhiNode::is_tripcount() const { 2176 return (in(0) != NULL && in(0)->is_CountedLoop() && 2177 in(0)->as_CountedLoop()->phi() == this); 2178 } 2179 2180 //------------------------------out_RegMask------------------------------------ 2181 const RegMask &PhiNode::in_RegMask(uint i) const { 2182 return i ? out_RegMask() : RegMask::Empty; 2183 } 2184 2185 const RegMask &PhiNode::out_RegMask() const { 2186 uint ideal_reg = _type->ideal_reg(); 2187 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" ); 2188 if( ideal_reg == 0 ) return RegMask::Empty; 2189 assert(ideal_reg != Op_RegFlags, "flags register is not spillable"); 2190 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]); 2191 } 2192 2193 #ifndef PRODUCT 2194 void PhiNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const { 2195 // For a PhiNode, the set of related nodes includes all inputs till level 2, 2196 // and all outputs till level 1. In compact mode, inputs till level 1 are 2197 // collected. 2198 this->collect_nodes(in_rel, compact ? 1 : 2, false, false); 2199 this->collect_nodes(out_rel, -1, false, false); 2200 } 2201 2202 void PhiNode::dump_spec(outputStream *st) const { 2203 TypeNode::dump_spec(st); 2204 if (is_tripcount()) { 2205 st->print(" #tripcount"); 2206 } 2207 } 2208 #endif 2209 2210 2211 //============================================================================= 2212 const Type* GotoNode::Value(PhaseGVN* phase) const { 2213 // If the input is reachable, then we are executed. 2214 // If the input is not reachable, then we are not executed. 2215 return phase->type(in(0)); 2216 } 2217 2218 Node* GotoNode::Identity(PhaseGVN* phase) { 2219 return in(0); // Simple copy of incoming control 2220 } 2221 2222 const RegMask &GotoNode::out_RegMask() const { 2223 return RegMask::Empty; 2224 } 2225 2226 #ifndef PRODUCT 2227 //-----------------------------related----------------------------------------- 2228 // The related nodes of a GotoNode are all inputs at level 1, as well as the 2229 // outputs at level 1. This is regardless of compact mode. 2230 void GotoNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const { 2231 this->collect_nodes(in_rel, 1, false, false); 2232 this->collect_nodes(out_rel, -1, false, false); 2233 } 2234 #endif 2235 2236 2237 //============================================================================= 2238 const RegMask &JumpNode::out_RegMask() const { 2239 return RegMask::Empty; 2240 } 2241 2242 #ifndef PRODUCT 2243 //-----------------------------related----------------------------------------- 2244 // The related nodes of a JumpNode are all inputs at level 1, as well as the 2245 // outputs at level 2 (to include actual jump targets beyond projection nodes). 2246 // This is regardless of compact mode. 2247 void JumpNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const { 2248 this->collect_nodes(in_rel, 1, false, false); 2249 this->collect_nodes(out_rel, -2, false, false); 2250 } 2251 #endif 2252 2253 //============================================================================= 2254 const RegMask &JProjNode::out_RegMask() const { 2255 return RegMask::Empty; 2256 } 2257 2258 //============================================================================= 2259 const RegMask &CProjNode::out_RegMask() const { 2260 return RegMask::Empty; 2261 } 2262 2263 2264 2265 //============================================================================= 2266 2267 uint PCTableNode::hash() const { return Node::hash() + _size; } 2268 uint PCTableNode::cmp( const Node &n ) const 2269 { return _size == ((PCTableNode&)n)._size; } 2270 2271 const Type *PCTableNode::bottom_type() const { 2272 const Type** f = TypeTuple::fields(_size); 2273 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL; 2274 return TypeTuple::make(_size, f); 2275 } 2276 2277 //------------------------------Value------------------------------------------ 2278 // Compute the type of the PCTableNode. If reachable it is a tuple of 2279 // Control, otherwise the table targets are not reachable 2280 const Type* PCTableNode::Value(PhaseGVN* phase) const { 2281 if( phase->type(in(0)) == Type::CONTROL ) 2282 return bottom_type(); 2283 return Type::TOP; // All paths dead? Then so are we 2284 } 2285 2286 //------------------------------Ideal------------------------------------------ 2287 // Return a node which is more "ideal" than the current node. Strip out 2288 // control copies 2289 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2290 return remove_dead_region(phase, can_reshape) ? this : NULL; 2291 } 2292 2293 //============================================================================= 2294 uint JumpProjNode::hash() const { 2295 return Node::hash() + _dest_bci; 2296 } 2297 2298 uint JumpProjNode::cmp( const Node &n ) const { 2299 return ProjNode::cmp(n) && 2300 _dest_bci == ((JumpProjNode&)n)._dest_bci; 2301 } 2302 2303 #ifndef PRODUCT 2304 void JumpProjNode::dump_spec(outputStream *st) const { 2305 ProjNode::dump_spec(st); 2306 st->print("@bci %d ",_dest_bci); 2307 } 2308 2309 void JumpProjNode::dump_compact_spec(outputStream *st) const { 2310 ProjNode::dump_compact_spec(st); 2311 st->print("(%d)%d@%d", _switch_val, _proj_no, _dest_bci); 2312 } 2313 2314 void JumpProjNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const { 2315 // The related nodes of a JumpProjNode are its inputs and outputs at level 1. 2316 this->collect_nodes(in_rel, 1, false, false); 2317 this->collect_nodes(out_rel, -1, false, false); 2318 } 2319 #endif 2320 2321 //============================================================================= 2322 //------------------------------Value------------------------------------------ 2323 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot 2324 // have the default "fall_through_index" path. 2325 const Type* CatchNode::Value(PhaseGVN* phase) const { 2326 // Unreachable? Then so are all paths from here. 2327 if( phase->type(in(0)) == Type::TOP ) return Type::TOP; 2328 // First assume all paths are reachable 2329 const Type** f = TypeTuple::fields(_size); 2330 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL; 2331 // Identify cases that will always throw an exception 2332 // () rethrow call 2333 // () virtual or interface call with NULL receiver 2334 // () call is a check cast with incompatible arguments 2335 if( in(1)->is_Proj() ) { 2336 Node *i10 = in(1)->in(0); 2337 if( i10->is_Call() ) { 2338 CallNode *call = i10->as_Call(); 2339 // Rethrows always throw exceptions, never return 2340 if (call->entry_point() == OptoRuntime::rethrow_stub()) { 2341 f[CatchProjNode::fall_through_index] = Type::TOP; 2342 } else if( call->req() > TypeFunc::Parms ) { 2343 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) ); 2344 // Check for null receiver to virtual or interface calls 2345 if( call->is_CallDynamicJava() && 2346 arg0->higher_equal(TypePtr::NULL_PTR) ) { 2347 f[CatchProjNode::fall_through_index] = Type::TOP; 2348 } 2349 } // End of if not a runtime stub 2350 } // End of if have call above me 2351 } // End of slot 1 is not a projection 2352 return TypeTuple::make(_size, f); 2353 } 2354 2355 //============================================================================= 2356 uint CatchProjNode::hash() const { 2357 return Node::hash() + _handler_bci; 2358 } 2359 2360 2361 uint CatchProjNode::cmp( const Node &n ) const { 2362 return ProjNode::cmp(n) && 2363 _handler_bci == ((CatchProjNode&)n)._handler_bci; 2364 } 2365 2366 2367 //------------------------------Identity--------------------------------------- 2368 // If only 1 target is possible, choose it if it is the main control 2369 Node* CatchProjNode::Identity(PhaseGVN* phase) { 2370 // If my value is control and no other value is, then treat as ID 2371 const TypeTuple *t = phase->type(in(0))->is_tuple(); 2372 if (t->field_at(_con) != Type::CONTROL) return this; 2373 // If we remove the last CatchProj and elide the Catch/CatchProj, then we 2374 // also remove any exception table entry. Thus we must know the call 2375 // feeding the Catch will not really throw an exception. This is ok for 2376 // the main fall-thru control (happens when we know a call can never throw 2377 // an exception) or for "rethrow", because a further optimization will 2378 // yank the rethrow (happens when we inline a function that can throw an 2379 // exception and the caller has no handler). Not legal, e.g., for passing 2380 // a NULL receiver to a v-call, or passing bad types to a slow-check-cast. 2381 // These cases MUST throw an exception via the runtime system, so the VM 2382 // will be looking for a table entry. 2383 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode 2384 CallNode *call; 2385 if (_con != TypeFunc::Control && // Bail out if not the main control. 2386 !(proj->is_Proj() && // AND NOT a rethrow 2387 proj->in(0)->is_Call() && 2388 (call = proj->in(0)->as_Call()) && 2389 call->entry_point() == OptoRuntime::rethrow_stub())) 2390 return this; 2391 2392 // Search for any other path being control 2393 for (uint i = 0; i < t->cnt(); i++) { 2394 if (i != _con && t->field_at(i) == Type::CONTROL) 2395 return this; 2396 } 2397 // Only my path is possible; I am identity on control to the jump 2398 return in(0)->in(0); 2399 } 2400 2401 2402 #ifndef PRODUCT 2403 void CatchProjNode::dump_spec(outputStream *st) const { 2404 ProjNode::dump_spec(st); 2405 st->print("@bci %d ",_handler_bci); 2406 } 2407 #endif 2408 2409 //============================================================================= 2410 //------------------------------Identity--------------------------------------- 2411 // Check for CreateEx being Identity. 2412 Node* CreateExNode::Identity(PhaseGVN* phase) { 2413 if( phase->type(in(1)) == Type::TOP ) return in(1); 2414 if( phase->type(in(0)) == Type::TOP ) return in(0); 2415 // We only come from CatchProj, unless the CatchProj goes away. 2416 // If the CatchProj is optimized away, then we just carry the 2417 // exception oop through. 2418 2419 // CheckCastPPNode::Ideal() for value types reuses the exception 2420 // paths of a call to perform an allocation: we can see a Phi here. 2421 if (in(1)->is_Phi()) { 2422 return this; 2423 } 2424 CallNode *call = in(1)->in(0)->as_Call(); 2425 2426 return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) ) 2427 ? this 2428 : call->in(TypeFunc::Parms); 2429 } 2430 2431 //============================================================================= 2432 //------------------------------Value------------------------------------------ 2433 // Check for being unreachable. 2434 const Type* NeverBranchNode::Value(PhaseGVN* phase) const { 2435 if (!in(0) || in(0)->is_top()) return Type::TOP; 2436 return bottom_type(); 2437 } 2438 2439 //------------------------------Ideal------------------------------------------ 2440 // Check for no longer being part of a loop 2441 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2442 if (can_reshape && !in(0)->is_Loop()) { 2443 // Dead code elimination can sometimes delete this projection so 2444 // if it's not there, there's nothing to do. 2445 Node* fallthru = proj_out_or_null(0); 2446 if (fallthru != NULL) { 2447 phase->is_IterGVN()->replace_node(fallthru, in(0)); 2448 } 2449 return phase->C->top(); 2450 } 2451 return NULL; 2452 } 2453 2454 #ifndef PRODUCT 2455 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const { 2456 st->print("%s", Name()); 2457 } 2458 #endif