1 /* 2 * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/systemDictionary.hpp" 27 #include "memory/allocation.inline.hpp" 28 #include "memory/resourceArea.hpp" 29 #include "oops/objArrayKlass.hpp" 30 #include "opto/addnode.hpp" 31 #include "opto/castnode.hpp" 32 #include "opto/cfgnode.hpp" 33 #include "opto/connode.hpp" 34 #include "opto/convertnode.hpp" 35 #include "opto/loopnode.hpp" 36 #include "opto/machnode.hpp" 37 #include "opto/movenode.hpp" 38 #include "opto/narrowptrnode.hpp" 39 #include "opto/mulnode.hpp" 40 #include "opto/phaseX.hpp" 41 #include "opto/regmask.hpp" 42 #include "opto/runtime.hpp" 43 #include "opto/subnode.hpp" 44 45 // Portions of code courtesy of Clifford Click 46 47 // Optimization - Graph Style 48 49 //============================================================================= 50 //------------------------------Value------------------------------------------ 51 // Compute the type of the RegionNode. 52 const Type* RegionNode::Value(PhaseGVN* phase) const { 53 for( uint i=1; i<req(); ++i ) { // For all paths in 54 Node *n = in(i); // Get Control source 55 if( !n ) continue; // Missing inputs are TOP 56 if( phase->type(n) == Type::CONTROL ) 57 return Type::CONTROL; 58 } 59 return Type::TOP; // All paths dead? Then so are we 60 } 61 62 //------------------------------Identity--------------------------------------- 63 // Check for Region being Identity. 64 Node* RegionNode::Identity(PhaseGVN* phase) { 65 // Cannot have Region be an identity, even if it has only 1 input. 66 // Phi users cannot have their Region input folded away for them, 67 // since they need to select the proper data input 68 return this; 69 } 70 71 //------------------------------merge_region----------------------------------- 72 // If a Region flows into a Region, merge into one big happy merge. This is 73 // hard to do if there is stuff that has to happen 74 static Node *merge_region(RegionNode *region, PhaseGVN *phase) { 75 if( region->Opcode() != Op_Region ) // Do not do to LoopNodes 76 return NULL; 77 Node *progress = NULL; // Progress flag 78 PhaseIterGVN *igvn = phase->is_IterGVN(); 79 80 uint rreq = region->req(); 81 for( uint i = 1; i < rreq; i++ ) { 82 Node *r = region->in(i); 83 if( r && r->Opcode() == Op_Region && // Found a region? 84 r->in(0) == r && // Not already collapsed? 85 r != region && // Avoid stupid situations 86 r->outcnt() == 2 ) { // Self user and 'region' user only? 87 assert(!r->as_Region()->has_phi(), "no phi users"); 88 if( !progress ) { // No progress 89 if (region->has_phi()) { 90 return NULL; // Only flatten if no Phi users 91 // igvn->hash_delete( phi ); 92 } 93 igvn->hash_delete( region ); 94 progress = region; // Making progress 95 } 96 igvn->hash_delete( r ); 97 98 // Append inputs to 'r' onto 'region' 99 for( uint j = 1; j < r->req(); j++ ) { 100 // Move an input from 'r' to 'region' 101 region->add_req(r->in(j)); 102 r->set_req(j, phase->C->top()); 103 // Update phis of 'region' 104 //for( uint k = 0; k < max; k++ ) { 105 // Node *phi = region->out(k); 106 // if( phi->is_Phi() ) { 107 // phi->add_req(phi->in(i)); 108 // } 109 //} 110 111 rreq++; // One more input to Region 112 } // Found a region to merge into Region 113 igvn->_worklist.push(r); 114 // Clobber pointer to the now dead 'r' 115 region->set_req(i, phase->C->top()); 116 } 117 } 118 119 return progress; 120 } 121 122 123 124 //--------------------------------has_phi-------------------------------------- 125 // Helper function: Return any PhiNode that uses this region or NULL 126 PhiNode* RegionNode::has_phi() const { 127 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 128 Node* phi = fast_out(i); 129 if (phi->is_Phi()) { // Check for Phi users 130 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)"); 131 return phi->as_Phi(); // this one is good enough 132 } 133 } 134 135 return NULL; 136 } 137 138 139 //-----------------------------has_unique_phi---------------------------------- 140 // Helper function: Return the only PhiNode that uses this region or NULL 141 PhiNode* RegionNode::has_unique_phi() const { 142 // Check that only one use is a Phi 143 PhiNode* only_phi = NULL; 144 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 145 Node* phi = fast_out(i); 146 if (phi->is_Phi()) { // Check for Phi users 147 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)"); 148 if (only_phi == NULL) { 149 only_phi = phi->as_Phi(); 150 } else { 151 return NULL; // multiple phis 152 } 153 } 154 } 155 156 return only_phi; 157 } 158 159 160 //------------------------------check_phi_clipping----------------------------- 161 // Helper function for RegionNode's identification of FP clipping 162 // Check inputs to the Phi 163 static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) { 164 min = NULL; 165 max = NULL; 166 val = NULL; 167 min_idx = 0; 168 max_idx = 0; 169 val_idx = 0; 170 uint phi_max = phi->req(); 171 if( phi_max == 4 ) { 172 for( uint j = 1; j < phi_max; ++j ) { 173 Node *n = phi->in(j); 174 int opcode = n->Opcode(); 175 switch( opcode ) { 176 case Op_ConI: 177 { 178 if( min == NULL ) { 179 min = n->Opcode() == Op_ConI ? (ConNode*)n : NULL; 180 min_idx = j; 181 } else { 182 max = n->Opcode() == Op_ConI ? (ConNode*)n : NULL; 183 max_idx = j; 184 if( min->get_int() > max->get_int() ) { 185 // Swap min and max 186 ConNode *temp; 187 uint temp_idx; 188 temp = min; min = max; max = temp; 189 temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx; 190 } 191 } 192 } 193 break; 194 default: 195 { 196 val = n; 197 val_idx = j; 198 } 199 break; 200 } 201 } 202 } 203 return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) ); 204 } 205 206 207 //------------------------------check_if_clipping------------------------------ 208 // Helper function for RegionNode's identification of FP clipping 209 // Check that inputs to Region come from two IfNodes, 210 // 211 // If 212 // False True 213 // If | 214 // False True | 215 // | | | 216 // RegionNode_inputs 217 // 218 static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) { 219 top_if = NULL; 220 bot_if = NULL; 221 222 // Check control structure above RegionNode for (if ( if ) ) 223 Node *in1 = region->in(1); 224 Node *in2 = region->in(2); 225 Node *in3 = region->in(3); 226 // Check that all inputs are projections 227 if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) { 228 Node *in10 = in1->in(0); 229 Node *in20 = in2->in(0); 230 Node *in30 = in3->in(0); 231 // Check that #1 and #2 are ifTrue and ifFalse from same If 232 if( in10 != NULL && in10->is_If() && 233 in20 != NULL && in20->is_If() && 234 in30 != NULL && in30->is_If() && in10 == in20 && 235 (in1->Opcode() != in2->Opcode()) ) { 236 Node *in100 = in10->in(0); 237 Node *in1000 = (in100 != NULL && in100->is_Proj()) ? in100->in(0) : NULL; 238 // Check that control for in10 comes from other branch of IF from in3 239 if( in1000 != NULL && in1000->is_If() && 240 in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) { 241 // Control pattern checks 242 top_if = (IfNode*)in1000; 243 bot_if = (IfNode*)in10; 244 } 245 } 246 } 247 248 return (top_if != NULL); 249 } 250 251 252 //------------------------------check_convf2i_clipping------------------------- 253 // Helper function for RegionNode's identification of FP clipping 254 // Verify that the value input to the phi comes from "ConvF2I; LShift; RShift" 255 static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) { 256 convf2i = NULL; 257 258 // Check for the RShiftNode 259 Node *rshift = phi->in(idx); 260 assert( rshift, "Previous checks ensure phi input is present"); 261 if( rshift->Opcode() != Op_RShiftI ) { return false; } 262 263 // Check for the LShiftNode 264 Node *lshift = rshift->in(1); 265 assert( lshift, "Previous checks ensure phi input is present"); 266 if( lshift->Opcode() != Op_LShiftI ) { return false; } 267 268 // Check for the ConvF2INode 269 Node *conv = lshift->in(1); 270 if( conv->Opcode() != Op_ConvF2I ) { return false; } 271 272 // Check that shift amounts are only to get sign bits set after F2I 273 jint max_cutoff = max->get_int(); 274 jint min_cutoff = min->get_int(); 275 jint left_shift = lshift->in(2)->get_int(); 276 jint right_shift = rshift->in(2)->get_int(); 277 jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1); 278 if( left_shift != right_shift || 279 0 > left_shift || left_shift >= BitsPerJavaInteger || 280 max_post_shift < max_cutoff || 281 max_post_shift < -min_cutoff ) { 282 // Shifts are necessary but current transformation eliminates them 283 return false; 284 } 285 286 // OK to return the result of ConvF2I without shifting 287 convf2i = (ConvF2INode*)conv; 288 return true; 289 } 290 291 292 //------------------------------check_compare_clipping------------------------- 293 // Helper function for RegionNode's identification of FP clipping 294 static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) { 295 Node *i1 = iff->in(1); 296 if ( !i1->is_Bool() ) { return false; } 297 BoolNode *bool1 = i1->as_Bool(); 298 if( less_than && bool1->_test._test != BoolTest::le ) { return false; } 299 else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; } 300 const Node *cmpF = bool1->in(1); 301 if( cmpF->Opcode() != Op_CmpF ) { return false; } 302 // Test that the float value being compared against 303 // is equivalent to the int value used as a limit 304 Node *nodef = cmpF->in(2); 305 if( nodef->Opcode() != Op_ConF ) { return false; } 306 jfloat conf = nodef->getf(); 307 jint coni = limit->get_int(); 308 if( ((int)conf) != coni ) { return false; } 309 input = cmpF->in(1); 310 return true; 311 } 312 313 //------------------------------is_unreachable_region-------------------------- 314 // Find if the Region node is reachable from the root. 315 bool RegionNode::is_unreachable_region(PhaseGVN *phase) const { 316 assert(req() == 2, ""); 317 318 // First, cut the simple case of fallthrough region when NONE of 319 // region's phis references itself directly or through a data node. 320 uint max = outcnt(); 321 uint i; 322 for (i = 0; i < max; i++) { 323 Node* phi = raw_out(i); 324 if (phi != NULL && phi->is_Phi()) { 325 assert(phase->eqv(phi->in(0), this) && phi->req() == 2, ""); 326 if (phi->outcnt() == 0) 327 continue; // Safe case - no loops 328 if (phi->outcnt() == 1) { 329 Node* u = phi->raw_out(0); 330 // Skip if only one use is an other Phi or Call or Uncommon trap. 331 // It is safe to consider this case as fallthrough. 332 if (u != NULL && (u->is_Phi() || u->is_CFG())) 333 continue; 334 } 335 // Check when phi references itself directly or through an other node. 336 if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe) 337 break; // Found possible unsafe data loop. 338 } 339 } 340 if (i >= max) 341 return false; // An unsafe case was NOT found - don't need graph walk. 342 343 // Unsafe case - check if the Region node is reachable from root. 344 ResourceMark rm; 345 346 Arena *a = Thread::current()->resource_area(); 347 Node_List nstack(a); 348 VectorSet visited(a); 349 350 // Mark all control nodes reachable from root outputs 351 Node *n = (Node*)phase->C->root(); 352 nstack.push(n); 353 visited.set(n->_idx); 354 while (nstack.size() != 0) { 355 n = nstack.pop(); 356 uint max = n->outcnt(); 357 for (uint i = 0; i < max; i++) { 358 Node* m = n->raw_out(i); 359 if (m != NULL && m->is_CFG()) { 360 if (phase->eqv(m, this)) { 361 return false; // We reached the Region node - it is not dead. 362 } 363 if (!visited.test_set(m->_idx)) 364 nstack.push(m); 365 } 366 } 367 } 368 369 return true; // The Region node is unreachable - it is dead. 370 } 371 372 bool RegionNode::try_clean_mem_phi(PhaseGVN *phase) { 373 // Incremental inlining + PhaseStringOpts sometimes produce: 374 // 375 // cmpP with 1 top input 376 // | 377 // If 378 // / \ 379 // IfFalse IfTrue /- Some Node 380 // \ / / / 381 // Region / /-MergeMem 382 // \---Phi 383 // 384 // 385 // It's expected by PhaseStringOpts that the Region goes away and is 386 // replaced by If's control input but because there's still a Phi, 387 // the Region stays in the graph. The top input from the cmpP is 388 // propagated forward and a subgraph that is useful goes away. The 389 // code below replaces the Phi with the MergeMem so that the Region 390 // is simplified. 391 392 PhiNode* phi = has_unique_phi(); 393 if (phi && phi->type() == Type::MEMORY && req() == 3 && phi->is_diamond_phi(true)) { 394 MergeMemNode* m = NULL; 395 assert(phi->req() == 3, "same as region"); 396 for (uint i = 1; i < 3; ++i) { 397 Node *mem = phi->in(i); 398 if (mem && mem->is_MergeMem() && in(i)->outcnt() == 1) { 399 // Nothing is control-dependent on path #i except the region itself. 400 m = mem->as_MergeMem(); 401 uint j = 3 - i; 402 Node* other = phi->in(j); 403 if (other && other == m->base_memory()) { 404 // m is a successor memory to other, and is not pinned inside the diamond, so push it out. 405 // This will allow the diamond to collapse completely. 406 phase->is_IterGVN()->replace_node(phi, m); 407 return true; 408 } 409 } 410 } 411 } 412 return false; 413 } 414 415 //------------------------------Ideal------------------------------------------ 416 // Return a node which is more "ideal" than the current node. Must preserve 417 // the CFG, but we can still strip out dead paths. 418 Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) { 419 if( !can_reshape && !in(0) ) return NULL; // Already degraded to a Copy 420 assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge"); 421 422 // Check for RegionNode with no Phi users and both inputs come from either 423 // arm of the same IF. If found, then the control-flow split is useless. 424 bool has_phis = false; 425 if (can_reshape) { // Need DU info to check for Phi users 426 has_phis = (has_phi() != NULL); // Cache result 427 if (has_phis && try_clean_mem_phi(phase)) { 428 has_phis = false; 429 } 430 431 if (!has_phis) { // No Phi users? Nothing merging? 432 for (uint i = 1; i < req()-1; i++) { 433 Node *if1 = in(i); 434 if( !if1 ) continue; 435 Node *iff = if1->in(0); 436 if( !iff || !iff->is_If() ) continue; 437 for( uint j=i+1; j<req(); j++ ) { 438 if( in(j) && in(j)->in(0) == iff && 439 if1->Opcode() != in(j)->Opcode() ) { 440 // Add the IF Projections to the worklist. They (and the IF itself) 441 // will be eliminated if dead. 442 phase->is_IterGVN()->add_users_to_worklist(iff); 443 set_req(i, iff->in(0));// Skip around the useless IF diamond 444 set_req(j, NULL); 445 return this; // Record progress 446 } 447 } 448 } 449 } 450 } 451 452 // Remove TOP or NULL input paths. If only 1 input path remains, this Region 453 // degrades to a copy. 454 bool add_to_worklist = false; 455 bool modified = false; 456 int cnt = 0; // Count of values merging 457 DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count 458 int del_it = 0; // The last input path we delete 459 // For all inputs... 460 for( uint i=1; i<req(); ++i ){// For all paths in 461 Node *n = in(i); // Get the input 462 if( n != NULL ) { 463 // Remove useless control copy inputs 464 if( n->is_Region() && n->as_Region()->is_copy() ) { 465 set_req(i, n->nonnull_req()); 466 modified = true; 467 i--; 468 continue; 469 } 470 if( n->is_Proj() ) { // Remove useless rethrows 471 Node *call = n->in(0); 472 if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) { 473 set_req(i, call->in(0)); 474 modified = true; 475 i--; 476 continue; 477 } 478 } 479 if( phase->type(n) == Type::TOP ) { 480 set_req(i, NULL); // Ignore TOP inputs 481 modified = true; 482 i--; 483 continue; 484 } 485 cnt++; // One more value merging 486 487 } else if (can_reshape) { // Else found dead path with DU info 488 PhaseIterGVN *igvn = phase->is_IterGVN(); 489 del_req(i); // Yank path from self 490 del_it = i; 491 uint max = outcnt(); 492 DUIterator j; 493 bool progress = true; 494 while(progress) { // Need to establish property over all users 495 progress = false; 496 for (j = outs(); has_out(j); j++) { 497 Node *n = out(j); 498 if( n->req() != req() && n->is_Phi() ) { 499 assert( n->in(0) == this, "" ); 500 igvn->hash_delete(n); // Yank from hash before hacking edges 501 n->set_req_X(i,NULL,igvn);// Correct DU info 502 n->del_req(i); // Yank path from Phis 503 if( max != outcnt() ) { 504 progress = true; 505 j = refresh_out_pos(j); 506 max = outcnt(); 507 } 508 } 509 } 510 } 511 add_to_worklist = true; 512 i--; 513 } 514 } 515 516 if (can_reshape && cnt == 1) { 517 // Is it dead loop? 518 // If it is LoopNopde it had 2 (+1 itself) inputs and 519 // one of them was cut. The loop is dead if it was EntryContol. 520 // Loop node may have only one input because entry path 521 // is removed in PhaseIdealLoop::Dominators(). 522 assert(!this->is_Loop() || cnt_orig <= 3, "Loop node should have 3 or less inputs"); 523 if (this->is_Loop() && (del_it == LoopNode::EntryControl || 524 del_it == 0 && is_unreachable_region(phase)) || 525 !this->is_Loop() && has_phis && is_unreachable_region(phase)) { 526 // Yes, the region will be removed during the next step below. 527 // Cut the backedge input and remove phis since no data paths left. 528 // We don't cut outputs to other nodes here since we need to put them 529 // on the worklist. 530 PhaseIterGVN *igvn = phase->is_IterGVN(); 531 if (in(1)->outcnt() == 1) { 532 igvn->_worklist.push(in(1)); 533 } 534 del_req(1); 535 cnt = 0; 536 assert( req() == 1, "no more inputs expected" ); 537 uint max = outcnt(); 538 bool progress = true; 539 Node *top = phase->C->top(); 540 DUIterator j; 541 while(progress) { 542 progress = false; 543 for (j = outs(); has_out(j); j++) { 544 Node *n = out(j); 545 if( n->is_Phi() ) { 546 assert( igvn->eqv(n->in(0), this), "" ); 547 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" ); 548 // Break dead loop data path. 549 // Eagerly replace phis with top to avoid phis copies generation. 550 igvn->replace_node(n, top); 551 if( max != outcnt() ) { 552 progress = true; 553 j = refresh_out_pos(j); 554 max = outcnt(); 555 } 556 } 557 } 558 } 559 add_to_worklist = true; 560 } 561 } 562 if (add_to_worklist) { 563 phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis 564 } 565 566 if( cnt <= 1 ) { // Only 1 path in? 567 set_req(0, NULL); // Null control input for region copy 568 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is. 569 // No inputs or all inputs are NULL. 570 return NULL; 571 } else if (can_reshape) { // Optimization phase - remove the node 572 PhaseIterGVN *igvn = phase->is_IterGVN(); 573 Node *parent_ctrl; 574 if( cnt == 0 ) { 575 assert( req() == 1, "no inputs expected" ); 576 // During IGVN phase such region will be subsumed by TOP node 577 // so region's phis will have TOP as control node. 578 // Kill phis here to avoid it. PhiNode::is_copy() will be always false. 579 // Also set other user's input to top. 580 parent_ctrl = phase->C->top(); 581 } else { 582 // The fallthrough case since we already checked dead loops above. 583 parent_ctrl = in(1); 584 assert(parent_ctrl != NULL, "Region is a copy of some non-null control"); 585 assert(!igvn->eqv(parent_ctrl, this), "Close dead loop"); 586 } 587 if (!add_to_worklist) 588 igvn->add_users_to_worklist(this); // Check for further allowed opts 589 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) { 590 Node* n = last_out(i); 591 igvn->hash_delete(n); // Remove from worklist before modifying edges 592 if( n->is_Phi() ) { // Collapse all Phis 593 // Eagerly replace phis to avoid copies generation. 594 Node* in; 595 if( cnt == 0 ) { 596 assert( n->req() == 1, "No data inputs expected" ); 597 in = parent_ctrl; // replaced by top 598 } else { 599 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" ); 600 in = n->in(1); // replaced by unique input 601 if( n->as_Phi()->is_unsafe_data_reference(in) ) 602 in = phase->C->top(); // replaced by top 603 } 604 igvn->replace_node(n, in); 605 } 606 else if( n->is_Region() ) { // Update all incoming edges 607 assert( !igvn->eqv(n, this), "Must be removed from DefUse edges"); 608 uint uses_found = 0; 609 for( uint k=1; k < n->req(); k++ ) { 610 if( n->in(k) == this ) { 611 n->set_req(k, parent_ctrl); 612 uses_found++; 613 } 614 } 615 if( uses_found > 1 ) { // (--i) done at the end of the loop. 616 i -= (uses_found - 1); 617 } 618 } 619 else { 620 assert( igvn->eqv(n->in(0), this), "Expect RegionNode to be control parent"); 621 n->set_req(0, parent_ctrl); 622 } 623 #ifdef ASSERT 624 for( uint k=0; k < n->req(); k++ ) { 625 assert( !igvn->eqv(n->in(k), this), "All uses of RegionNode should be gone"); 626 } 627 #endif 628 } 629 // Remove the RegionNode itself from DefUse info 630 igvn->remove_dead_node(this); 631 return NULL; 632 } 633 return this; // Record progress 634 } 635 636 637 // If a Region flows into a Region, merge into one big happy merge. 638 if (can_reshape) { 639 Node *m = merge_region(this, phase); 640 if (m != NULL) return m; 641 } 642 643 // Check if this region is the root of a clipping idiom on floats 644 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) { 645 // Check that only one use is a Phi and that it simplifies to two constants + 646 PhiNode* phi = has_unique_phi(); 647 if (phi != NULL) { // One Phi user 648 // Check inputs to the Phi 649 ConNode *min; 650 ConNode *max; 651 Node *val; 652 uint min_idx; 653 uint max_idx; 654 uint val_idx; 655 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) { 656 IfNode *top_if; 657 IfNode *bot_if; 658 if( check_if_clipping( this, bot_if, top_if ) ) { 659 // Control pattern checks, now verify compares 660 Node *top_in = NULL; // value being compared against 661 Node *bot_in = NULL; 662 if( check_compare_clipping( true, bot_if, min, bot_in ) && 663 check_compare_clipping( false, top_if, max, top_in ) ) { 664 if( bot_in == top_in ) { 665 PhaseIterGVN *gvn = phase->is_IterGVN(); 666 assert( gvn != NULL, "Only had DefUse info in IterGVN"); 667 // Only remaining check is that bot_in == top_in == (Phi's val + mods) 668 669 // Check for the ConvF2INode 670 ConvF2INode *convf2i; 671 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) && 672 convf2i->in(1) == bot_in ) { 673 // Matched pattern, including LShiftI; RShiftI, replace with integer compares 674 // max test 675 Node *cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, min )); 676 Node *boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::lt )); 677 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt )); 678 Node *if_min= gvn->register_new_node_with_optimizer(new IfTrueNode (iff)); 679 Node *ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff)); 680 // min test 681 cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, max )); 682 boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::gt )); 683 iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt )); 684 Node *if_max= gvn->register_new_node_with_optimizer(new IfTrueNode (iff)); 685 ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff)); 686 // update input edges to region node 687 set_req_X( min_idx, if_min, gvn ); 688 set_req_X( max_idx, if_max, gvn ); 689 set_req_X( val_idx, ifF, gvn ); 690 // remove unnecessary 'LShiftI; RShiftI' idiom 691 gvn->hash_delete(phi); 692 phi->set_req_X( val_idx, convf2i, gvn ); 693 gvn->hash_find_insert(phi); 694 // Return transformed region node 695 return this; 696 } 697 } 698 } 699 } 700 } 701 } 702 } 703 704 return modified ? this : NULL; 705 } 706 707 708 709 const RegMask &RegionNode::out_RegMask() const { 710 return RegMask::Empty; 711 } 712 713 // Find the one non-null required input. RegionNode only 714 Node *Node::nonnull_req() const { 715 assert( is_Region(), "" ); 716 for( uint i = 1; i < _cnt; i++ ) 717 if( in(i) ) 718 return in(i); 719 ShouldNotReachHere(); 720 return NULL; 721 } 722 723 724 //============================================================================= 725 // note that these functions assume that the _adr_type field is flattened 726 uint PhiNode::hash() const { 727 const Type* at = _adr_type; 728 return TypeNode::hash() + (at ? at->hash() : 0); 729 } 730 uint PhiNode::cmp( const Node &n ) const { 731 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type; 732 } 733 static inline 734 const TypePtr* flatten_phi_adr_type(const TypePtr* at) { 735 if (at == NULL || at == TypePtr::BOTTOM) return at; 736 return Compile::current()->alias_type(at)->adr_type(); 737 } 738 739 //----------------------------make--------------------------------------------- 740 // create a new phi with edges matching r and set (initially) to x 741 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) { 742 uint preds = r->req(); // Number of predecessor paths 743 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at"); 744 PhiNode* p = new PhiNode(r, t, at); 745 for (uint j = 1; j < preds; j++) { 746 // Fill in all inputs, except those which the region does not yet have 747 if (r->in(j) != NULL) 748 p->init_req(j, x); 749 } 750 return p; 751 } 752 PhiNode* PhiNode::make(Node* r, Node* x) { 753 const Type* t = x->bottom_type(); 754 const TypePtr* at = NULL; 755 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type()); 756 return make(r, x, t, at); 757 } 758 PhiNode* PhiNode::make_blank(Node* r, Node* x) { 759 const Type* t = x->bottom_type(); 760 const TypePtr* at = NULL; 761 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type()); 762 return new PhiNode(r, t, at); 763 } 764 765 766 //------------------------slice_memory----------------------------------------- 767 // create a new phi with narrowed memory type 768 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const { 769 PhiNode* mem = (PhiNode*) clone(); 770 *(const TypePtr**)&mem->_adr_type = adr_type; 771 // convert self-loops, or else we get a bad graph 772 for (uint i = 1; i < req(); i++) { 773 if ((const Node*)in(i) == this) mem->set_req(i, mem); 774 } 775 mem->verify_adr_type(); 776 return mem; 777 } 778 779 //------------------------split_out_instance----------------------------------- 780 // Split out an instance type from a bottom phi. 781 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const { 782 const TypeOopPtr *t_oop = at->isa_oopptr(); 783 assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr"); 784 const TypePtr *t = adr_type(); 785 assert(type() == Type::MEMORY && 786 (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM || 787 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() && 788 t->is_oopptr()->cast_to_exactness(true) 789 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr()) 790 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop), 791 "bottom or raw memory required"); 792 793 // Check if an appropriate node already exists. 794 Node *region = in(0); 795 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) { 796 Node* use = region->fast_out(k); 797 if( use->is_Phi()) { 798 PhiNode *phi2 = use->as_Phi(); 799 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) { 800 return phi2; 801 } 802 } 803 } 804 Compile *C = igvn->C; 805 Arena *a = Thread::current()->resource_area(); 806 Node_Array node_map = new Node_Array(a); 807 Node_Stack stack(a, C->live_nodes() >> 4); 808 PhiNode *nphi = slice_memory(at); 809 igvn->register_new_node_with_optimizer( nphi ); 810 node_map.map(_idx, nphi); 811 stack.push((Node *)this, 1); 812 while(!stack.is_empty()) { 813 PhiNode *ophi = stack.node()->as_Phi(); 814 uint i = stack.index(); 815 assert(i >= 1, "not control edge"); 816 stack.pop(); 817 nphi = node_map[ophi->_idx]->as_Phi(); 818 for (; i < ophi->req(); i++) { 819 Node *in = ophi->in(i); 820 if (in == NULL || igvn->type(in) == Type::TOP) 821 continue; 822 Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, NULL, igvn); 823 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL; 824 if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) { 825 opt = node_map[optphi->_idx]; 826 if (opt == NULL) { 827 stack.push(ophi, i); 828 nphi = optphi->slice_memory(at); 829 igvn->register_new_node_with_optimizer( nphi ); 830 node_map.map(optphi->_idx, nphi); 831 ophi = optphi; 832 i = 0; // will get incremented at top of loop 833 continue; 834 } 835 } 836 nphi->set_req(i, opt); 837 } 838 } 839 return nphi; 840 } 841 842 //------------------------verify_adr_type-------------------------------------- 843 #ifdef ASSERT 844 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const { 845 if (visited.test_set(_idx)) return; //already visited 846 847 // recheck constructor invariants: 848 verify_adr_type(false); 849 850 // recheck local phi/phi consistency: 851 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM, 852 "adr_type must be consistent across phi nest"); 853 854 // walk around 855 for (uint i = 1; i < req(); i++) { 856 Node* n = in(i); 857 if (n == NULL) continue; 858 const Node* np = in(i); 859 if (np->is_Phi()) { 860 np->as_Phi()->verify_adr_type(visited, at); 861 } else if (n->bottom_type() == Type::TOP 862 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) { 863 // ignore top inputs 864 } else { 865 const TypePtr* nat = flatten_phi_adr_type(n->adr_type()); 866 // recheck phi/non-phi consistency at leaves: 867 assert((nat != NULL) == (at != NULL), ""); 868 assert(nat == at || nat == TypePtr::BOTTOM, 869 "adr_type must be consistent at leaves of phi nest"); 870 } 871 } 872 } 873 874 // Verify a whole nest of phis rooted at this one. 875 void PhiNode::verify_adr_type(bool recursive) const { 876 if (is_error_reported()) return; // muzzle asserts when debugging an error 877 if (Node::in_dump()) return; // muzzle asserts when printing 878 879 assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only"); 880 881 if (!VerifyAliases) return; // verify thoroughly only if requested 882 883 assert(_adr_type == flatten_phi_adr_type(_adr_type), 884 "Phi::adr_type must be pre-normalized"); 885 886 if (recursive) { 887 VectorSet visited(Thread::current()->resource_area()); 888 verify_adr_type(visited, _adr_type); 889 } 890 } 891 #endif 892 893 894 //------------------------------Value------------------------------------------ 895 // Compute the type of the PhiNode 896 const Type* PhiNode::Value(PhaseGVN* phase) const { 897 Node *r = in(0); // RegionNode 898 if( !r ) // Copy or dead 899 return in(1) ? phase->type(in(1)) : Type::TOP; 900 901 // Note: During parsing, phis are often transformed before their regions. 902 // This means we have to use type_or_null to defend against untyped regions. 903 if( phase->type_or_null(r) == Type::TOP ) // Dead code? 904 return Type::TOP; 905 906 // Check for trip-counted loop. If so, be smarter. 907 CountedLoopNode* l = r->is_CountedLoop() ? r->as_CountedLoop() : NULL; 908 if (l && ((const Node*)l->phi() == this)) { // Trip counted loop! 909 // protect against init_trip() or limit() returning NULL 910 if (l->can_be_counted_loop(phase)) { 911 const Node *init = l->init_trip(); 912 const Node *limit = l->limit(); 913 const Node* stride = l->stride(); 914 if (init != NULL && limit != NULL && stride != NULL) { 915 const TypeInt* lo = phase->type(init)->isa_int(); 916 const TypeInt* hi = phase->type(limit)->isa_int(); 917 const TypeInt* stride_t = phase->type(stride)->isa_int(); 918 if (lo != NULL && hi != NULL && stride_t != NULL) { // Dying loops might have TOP here 919 assert(stride_t->_hi >= stride_t->_lo, "bad stride type"); 920 if (stride_t->_hi < 0) { // Down-counter loop 921 swap(lo, hi); 922 return TypeInt::make(MIN2(lo->_lo, hi->_lo) , hi->_hi, 3); 923 } else if (stride_t->_lo >= 0) { 924 return TypeInt::make(lo->_lo, MAX2(lo->_hi, hi->_hi), 3); 925 } 926 } 927 } 928 } else if (l->in(LoopNode::LoopBackControl) != NULL && 929 in(LoopNode::EntryControl) != NULL && 930 phase->type(l->in(LoopNode::LoopBackControl)) == Type::TOP) { 931 // During CCP, if we saturate the type of a counted loop's Phi 932 // before the special code for counted loop above has a chance 933 // to run (that is as long as the type of the backedge's control 934 // is top), we might end up with non monotonic types 935 return phase->type(in(LoopNode::EntryControl)); 936 } 937 } 938 939 // Until we have harmony between classes and interfaces in the type 940 // lattice, we must tread carefully around phis which implicitly 941 // convert the one to the other. 942 const TypePtr* ttp = _type->make_ptr(); 943 const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL; 944 const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_klassptr() : NULL; 945 bool is_intf = false; 946 if (ttip != NULL) { 947 ciKlass* k = ttip->klass(); 948 if (k->is_loaded() && k->is_interface()) 949 is_intf = true; 950 } 951 if (ttkp != NULL) { 952 ciKlass* k = ttkp->klass(); 953 if (k->is_loaded() && k->is_interface()) 954 is_intf = true; 955 } 956 957 // Default case: merge all inputs 958 const Type *t = Type::TOP; // Merged type starting value 959 for (uint i = 1; i < req(); ++i) {// For all paths in 960 // Reachable control path? 961 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) { 962 const Type* ti = phase->type(in(i)); 963 // We assume that each input of an interface-valued Phi is a true 964 // subtype of that interface. This might not be true of the meet 965 // of all the input types. The lattice is not distributive in 966 // such cases. Ward off asserts in type.cpp by refusing to do 967 // meets between interfaces and proper classes. 968 const TypePtr* tip = ti->make_ptr(); 969 const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL; 970 if (tiip) { 971 bool ti_is_intf = false; 972 ciKlass* k = tiip->klass(); 973 if (k->is_loaded() && k->is_interface()) 974 ti_is_intf = true; 975 if (is_intf != ti_is_intf) 976 { t = _type; break; } 977 } 978 t = t->meet_speculative(ti); 979 } 980 } 981 982 // The worst-case type (from ciTypeFlow) should be consistent with "t". 983 // That is, we expect that "t->higher_equal(_type)" holds true. 984 // There are various exceptions: 985 // - Inputs which are phis might in fact be widened unnecessarily. 986 // For example, an input might be a widened int while the phi is a short. 987 // - Inputs might be BotPtrs but this phi is dependent on a null check, 988 // and postCCP has removed the cast which encodes the result of the check. 989 // - The type of this phi is an interface, and the inputs are classes. 990 // - Value calls on inputs might produce fuzzy results. 991 // (Occurrences of this case suggest improvements to Value methods.) 992 // 993 // It is not possible to see Type::BOTTOM values as phi inputs, 994 // because the ciTypeFlow pre-pass produces verifier-quality types. 995 const Type* ft = t->filter_speculative(_type); // Worst case type 996 997 #ifdef ASSERT 998 // The following logic has been moved into TypeOopPtr::filter. 999 const Type* jt = t->join_speculative(_type); 1000 if (jt->empty()) { // Emptied out??? 1001 1002 // Check for evil case of 't' being a class and '_type' expecting an 1003 // interface. This can happen because the bytecodes do not contain 1004 // enough type info to distinguish a Java-level interface variable 1005 // from a Java-level object variable. If we meet 2 classes which 1006 // both implement interface I, but their meet is at 'j/l/O' which 1007 // doesn't implement I, we have no way to tell if the result should 1008 // be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows 1009 // into a Phi which "knows" it's an Interface type we'll have to 1010 // uplift the type. 1011 if (!t->empty() && ttip && ttip->is_loaded() && ttip->klass()->is_interface()) { 1012 assert(ft == _type, ""); // Uplift to interface 1013 } else if (!t->empty() && ttkp && ttkp->is_loaded() && ttkp->klass()->is_interface()) { 1014 assert(ft == _type, ""); // Uplift to interface 1015 } else { 1016 // We also have to handle 'evil cases' of interface- vs. class-arrays 1017 Type::get_arrays_base_elements(jt, _type, NULL, &ttip); 1018 if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) { 1019 assert(ft == _type, ""); // Uplift to array of interface 1020 } else { 1021 // Otherwise it's something stupid like non-overlapping int ranges 1022 // found on dying counted loops. 1023 assert(ft == Type::TOP, ""); // Canonical empty value 1024 } 1025 } 1026 } 1027 1028 else { 1029 1030 // If we have an interface-typed Phi and we narrow to a class type, the join 1031 // should report back the class. However, if we have a J/L/Object 1032 // class-typed Phi and an interface flows in, it's possible that the meet & 1033 // join report an interface back out. This isn't possible but happens 1034 // because the type system doesn't interact well with interfaces. 1035 const TypePtr *jtp = jt->make_ptr(); 1036 const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL; 1037 const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_klassptr() : NULL; 1038 if( jtip && ttip ) { 1039 if( jtip->is_loaded() && jtip->klass()->is_interface() && 1040 ttip->is_loaded() && !ttip->klass()->is_interface() ) { 1041 assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) || 1042 ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), ""); 1043 jt = ft; 1044 } 1045 } 1046 if( jtkp && ttkp ) { 1047 if( jtkp->is_loaded() && jtkp->klass()->is_interface() && 1048 !jtkp->klass_is_exact() && // Keep exact interface klass (6894807) 1049 ttkp->is_loaded() && !ttkp->klass()->is_interface() ) { 1050 assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) || 1051 ft->isa_narrowklass() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), ""); 1052 jt = ft; 1053 } 1054 } 1055 if (jt != ft && jt->base() == ft->base()) { 1056 if (jt->isa_int() && 1057 jt->is_int()->_lo == ft->is_int()->_lo && 1058 jt->is_int()->_hi == ft->is_int()->_hi) 1059 jt = ft; 1060 if (jt->isa_long() && 1061 jt->is_long()->_lo == ft->is_long()->_lo && 1062 jt->is_long()->_hi == ft->is_long()->_hi) 1063 jt = ft; 1064 } 1065 if (jt != ft) { 1066 tty->print("merge type: "); t->dump(); tty->cr(); 1067 tty->print("kill type: "); _type->dump(); tty->cr(); 1068 tty->print("join type: "); jt->dump(); tty->cr(); 1069 tty->print("filter type: "); ft->dump(); tty->cr(); 1070 } 1071 assert(jt == ft, ""); 1072 } 1073 #endif //ASSERT 1074 1075 // Deal with conversion problems found in data loops. 1076 ft = phase->saturate(ft, phase->type_or_null(this), _type); 1077 1078 return ft; 1079 } 1080 1081 1082 //------------------------------is_diamond_phi--------------------------------- 1083 // Does this Phi represent a simple well-shaped diamond merge? Return the 1084 // index of the true path or 0 otherwise. 1085 // If check_control_only is true, do not inspect the If node at the 1086 // top, and return -1 (not an edge number) on success. 1087 int PhiNode::is_diamond_phi(bool check_control_only) const { 1088 // Check for a 2-path merge 1089 Node *region = in(0); 1090 if( !region ) return 0; 1091 if( region->req() != 3 ) return 0; 1092 if( req() != 3 ) return 0; 1093 // Check that both paths come from the same If 1094 Node *ifp1 = region->in(1); 1095 Node *ifp2 = region->in(2); 1096 if( !ifp1 || !ifp2 ) return 0; 1097 Node *iff = ifp1->in(0); 1098 if( !iff || !iff->is_If() ) return 0; 1099 if( iff != ifp2->in(0) ) return 0; 1100 if (check_control_only) return -1; 1101 // Check for a proper bool/cmp 1102 const Node *b = iff->in(1); 1103 if( !b->is_Bool() ) return 0; 1104 const Node *cmp = b->in(1); 1105 if( !cmp->is_Cmp() ) return 0; 1106 1107 // Check for branching opposite expected 1108 if( ifp2->Opcode() == Op_IfTrue ) { 1109 assert( ifp1->Opcode() == Op_IfFalse, "" ); 1110 return 2; 1111 } else { 1112 assert( ifp1->Opcode() == Op_IfTrue, "" ); 1113 return 1; 1114 } 1115 } 1116 1117 //----------------------------check_cmove_id----------------------------------- 1118 // Check for CMove'ing a constant after comparing against the constant. 1119 // Happens all the time now, since if we compare equality vs a constant in 1120 // the parser, we "know" the variable is constant on one path and we force 1121 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a 1122 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more 1123 // general in that we don't need constants. Since CMove's are only inserted 1124 // in very special circumstances, we do it here on generic Phi's. 1125 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) { 1126 assert(true_path !=0, "only diamond shape graph expected"); 1127 1128 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1129 // phi->region->if_proj->ifnode->bool->cmp 1130 Node* region = in(0); 1131 Node* iff = region->in(1)->in(0); 1132 BoolNode* b = iff->in(1)->as_Bool(); 1133 Node* cmp = b->in(1); 1134 Node* tval = in(true_path); 1135 Node* fval = in(3-true_path); 1136 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b); 1137 if (id == NULL) 1138 return NULL; 1139 1140 // Either value might be a cast that depends on a branch of 'iff'. 1141 // Since the 'id' value will float free of the diamond, either 1142 // decast or return failure. 1143 Node* ctl = id->in(0); 1144 if (ctl != NULL && ctl->in(0) == iff) { 1145 if (id->is_ConstraintCast()) { 1146 return id->in(1); 1147 } else { 1148 // Don't know how to disentangle this value. 1149 return NULL; 1150 } 1151 } 1152 1153 return id; 1154 } 1155 1156 //------------------------------Identity--------------------------------------- 1157 // Check for Region being Identity. 1158 Node* PhiNode::Identity(PhaseGVN* phase) { 1159 // Check for no merging going on 1160 // (There used to be special-case code here when this->region->is_Loop. 1161 // It would check for a tributary phi on the backedge that the main phi 1162 // trivially, perhaps with a single cast. The unique_input method 1163 // does all this and more, by reducing such tributaries to 'this'.) 1164 Node* uin = unique_input(phase, false); 1165 if (uin != NULL) { 1166 return uin; 1167 } 1168 1169 int true_path = is_diamond_phi(); 1170 if (true_path != 0) { 1171 Node* id = is_cmove_id(phase, true_path); 1172 if (id != NULL) return id; 1173 } 1174 1175 return this; // No identity 1176 } 1177 1178 //-----------------------------unique_input------------------------------------ 1179 // Find the unique value, discounting top, self-loops, and casts. 1180 // Return top if there are no inputs, and self if there are multiple. 1181 Node* PhiNode::unique_input(PhaseTransform* phase, bool uncast) { 1182 // 1) One unique direct input, 1183 // or if uncast is true: 1184 // 2) some of the inputs have an intervening ConstraintCast 1185 // 3) an input is a self loop 1186 // 1187 // 1) input or 2) input or 3) input __ 1188 // / \ / \ \ / \ 1189 // \ / | cast phi cast 1190 // phi \ / / \ / 1191 // phi / -- 1192 1193 Node* r = in(0); // RegionNode 1194 if (r == NULL) return in(1); // Already degraded to a Copy 1195 Node* input = NULL; // The unique direct input (maybe uncasted = ConstraintCasts removed) 1196 1197 for (uint i = 1, cnt = req(); i < cnt; ++i) { 1198 Node* rc = r->in(i); 1199 if (rc == NULL || phase->type(rc) == Type::TOP) 1200 continue; // ignore unreachable control path 1201 Node* n = in(i); 1202 if (n == NULL) 1203 continue; 1204 Node* un = n; 1205 if (uncast) { 1206 #ifdef ASSERT 1207 Node* m = un->uncast(); 1208 #endif 1209 while (un != NULL && un->req() == 2 && un->is_ConstraintCast()) { 1210 Node* next = un->in(1); 1211 if (phase->type(next)->isa_rawptr() && phase->type(un)->isa_oopptr()) { 1212 // risk exposing raw ptr at safepoint 1213 break; 1214 } 1215 un = next; 1216 } 1217 assert(m == un || un->in(1) == m, "Only expected at CheckCastPP from allocation"); 1218 } 1219 if (un == NULL || un == this || phase->type(un) == Type::TOP) { 1220 continue; // ignore if top, or in(i) and "this" are in a data cycle 1221 } 1222 // Check for a unique input (maybe uncasted) 1223 if (input == NULL) { 1224 input = un; 1225 } else if (input != un) { 1226 input = NodeSentinel; // no unique input 1227 } 1228 } 1229 if (input == NULL) { 1230 return phase->C->top(); // no inputs 1231 } 1232 1233 if (input != NodeSentinel) { 1234 return input; // one unique direct input 1235 } 1236 1237 // Nothing. 1238 return NULL; 1239 } 1240 1241 //------------------------------is_x2logic------------------------------------- 1242 // Check for simple convert-to-boolean pattern 1243 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1) 1244 // Convert Phi to an ConvIB. 1245 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) { 1246 assert(true_path !=0, "only diamond shape graph expected"); 1247 // Convert the true/false index into an expected 0/1 return. 1248 // Map 2->0 and 1->1. 1249 int flipped = 2-true_path; 1250 1251 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1252 // phi->region->if_proj->ifnode->bool->cmp 1253 Node *region = phi->in(0); 1254 Node *iff = region->in(1)->in(0); 1255 BoolNode *b = (BoolNode*)iff->in(1); 1256 const CmpNode *cmp = (CmpNode*)b->in(1); 1257 1258 Node *zero = phi->in(1); 1259 Node *one = phi->in(2); 1260 const Type *tzero = phase->type( zero ); 1261 const Type *tone = phase->type( one ); 1262 1263 // Check for compare vs 0 1264 const Type *tcmp = phase->type(cmp->in(2)); 1265 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) { 1266 // Allow cmp-vs-1 if the other input is bounded by 0-1 1267 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) ) 1268 return NULL; 1269 flipped = 1-flipped; // Test is vs 1 instead of 0! 1270 } 1271 1272 // Check for setting zero/one opposite expected 1273 if( tzero == TypeInt::ZERO ) { 1274 if( tone == TypeInt::ONE ) { 1275 } else return NULL; 1276 } else if( tzero == TypeInt::ONE ) { 1277 if( tone == TypeInt::ZERO ) { 1278 flipped = 1-flipped; 1279 } else return NULL; 1280 } else return NULL; 1281 1282 // Check for boolean test backwards 1283 if( b->_test._test == BoolTest::ne ) { 1284 } else if( b->_test._test == BoolTest::eq ) { 1285 flipped = 1-flipped; 1286 } else return NULL; 1287 1288 // Build int->bool conversion 1289 Node *n = new Conv2BNode( cmp->in(1) ); 1290 if( flipped ) 1291 n = new XorINode( phase->transform(n), phase->intcon(1) ); 1292 1293 return n; 1294 } 1295 1296 //------------------------------is_cond_add------------------------------------ 1297 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;" 1298 // To be profitable the control flow has to disappear; there can be no other 1299 // values merging here. We replace the test-and-branch with: 1300 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by 1301 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'. 1302 // Then convert Y to 0-or-Y and finally add. 1303 // This is a key transform for SpecJava _201_compress. 1304 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) { 1305 assert(true_path !=0, "only diamond shape graph expected"); 1306 1307 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1308 // phi->region->if_proj->ifnode->bool->cmp 1309 RegionNode *region = (RegionNode*)phi->in(0); 1310 Node *iff = region->in(1)->in(0); 1311 BoolNode* b = iff->in(1)->as_Bool(); 1312 const CmpNode *cmp = (CmpNode*)b->in(1); 1313 1314 // Make sure only merging this one phi here 1315 if (region->has_unique_phi() != phi) return NULL; 1316 1317 // Make sure each arm of the diamond has exactly one output, which we assume 1318 // is the region. Otherwise, the control flow won't disappear. 1319 if (region->in(1)->outcnt() != 1) return NULL; 1320 if (region->in(2)->outcnt() != 1) return NULL; 1321 1322 // Check for "(P < Q)" of type signed int 1323 if (b->_test._test != BoolTest::lt) return NULL; 1324 if (cmp->Opcode() != Op_CmpI) return NULL; 1325 1326 Node *p = cmp->in(1); 1327 Node *q = cmp->in(2); 1328 Node *n1 = phi->in( true_path); 1329 Node *n2 = phi->in(3-true_path); 1330 1331 int op = n1->Opcode(); 1332 if( op != Op_AddI // Need zero as additive identity 1333 /*&&op != Op_SubI && 1334 op != Op_AddP && 1335 op != Op_XorI && 1336 op != Op_OrI*/ ) 1337 return NULL; 1338 1339 Node *x = n2; 1340 Node *y = NULL; 1341 if( x == n1->in(1) ) { 1342 y = n1->in(2); 1343 } else if( x == n1->in(2) ) { 1344 y = n1->in(1); 1345 } else return NULL; 1346 1347 // Not so profitable if compare and add are constants 1348 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() ) 1349 return NULL; 1350 1351 Node *cmplt = phase->transform( new CmpLTMaskNode(p,q) ); 1352 Node *j_and = phase->transform( new AndINode(cmplt,y) ); 1353 return new AddINode(j_and,x); 1354 } 1355 1356 //------------------------------is_absolute------------------------------------ 1357 // Check for absolute value. 1358 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) { 1359 assert(true_path !=0, "only diamond shape graph expected"); 1360 1361 int cmp_zero_idx = 0; // Index of compare input where to look for zero 1362 int phi_x_idx = 0; // Index of phi input where to find naked x 1363 1364 // ABS ends with the merge of 2 control flow paths. 1365 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely. 1366 int false_path = 3 - true_path; 1367 1368 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1369 // phi->region->if_proj->ifnode->bool->cmp 1370 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool(); 1371 1372 // Check bool sense 1373 switch( bol->_test._test ) { 1374 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break; 1375 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break; 1376 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break; 1377 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break; 1378 default: return NULL; break; 1379 } 1380 1381 // Test is next 1382 Node *cmp = bol->in(1); 1383 const Type *tzero = NULL; 1384 switch( cmp->Opcode() ) { 1385 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS 1386 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS 1387 default: return NULL; 1388 } 1389 1390 // Find zero input of compare; the other input is being abs'd 1391 Node *x = NULL; 1392 bool flip = false; 1393 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) { 1394 x = cmp->in(3 - cmp_zero_idx); 1395 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) { 1396 // The test is inverted, we should invert the result... 1397 x = cmp->in(cmp_zero_idx); 1398 flip = true; 1399 } else { 1400 return NULL; 1401 } 1402 1403 // Next get the 2 pieces being selected, one is the original value 1404 // and the other is the negated value. 1405 if( phi_root->in(phi_x_idx) != x ) return NULL; 1406 1407 // Check other phi input for subtract node 1408 Node *sub = phi_root->in(3 - phi_x_idx); 1409 1410 // Allow only Sub(0,X) and fail out for all others; Neg is not OK 1411 if( tzero == TypeF::ZERO ) { 1412 if( sub->Opcode() != Op_SubF || 1413 sub->in(2) != x || 1414 phase->type(sub->in(1)) != tzero ) return NULL; 1415 x = new AbsFNode(x); 1416 if (flip) { 1417 x = new SubFNode(sub->in(1), phase->transform(x)); 1418 } 1419 } else { 1420 if( sub->Opcode() != Op_SubD || 1421 sub->in(2) != x || 1422 phase->type(sub->in(1)) != tzero ) return NULL; 1423 x = new AbsDNode(x); 1424 if (flip) { 1425 x = new SubDNode(sub->in(1), phase->transform(x)); 1426 } 1427 } 1428 1429 return x; 1430 } 1431 1432 //------------------------------split_once------------------------------------- 1433 // Helper for split_flow_path 1434 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) { 1435 igvn->hash_delete(n); // Remove from hash before hacking edges 1436 1437 uint j = 1; 1438 for (uint i = phi->req()-1; i > 0; i--) { 1439 if (phi->in(i) == val) { // Found a path with val? 1440 // Add to NEW Region/Phi, no DU info 1441 newn->set_req( j++, n->in(i) ); 1442 // Remove from OLD Region/Phi 1443 n->del_req(i); 1444 } 1445 } 1446 1447 // Register the new node but do not transform it. Cannot transform until the 1448 // entire Region/Phi conglomerate has been hacked as a single huge transform. 1449 igvn->register_new_node_with_optimizer( newn ); 1450 1451 // Now I can point to the new node. 1452 n->add_req(newn); 1453 igvn->_worklist.push(n); 1454 } 1455 1456 //------------------------------split_flow_path-------------------------------- 1457 // Check for merging identical values and split flow paths 1458 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) { 1459 BasicType bt = phi->type()->basic_type(); 1460 if( bt == T_ILLEGAL || type2size[bt] <= 0 ) 1461 return NULL; // Bail out on funny non-value stuff 1462 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a 1463 return NULL; // third unequal input to be worth doing 1464 1465 // Scan for a constant 1466 uint i; 1467 for( i = 1; i < phi->req()-1; i++ ) { 1468 Node *n = phi->in(i); 1469 if( !n ) return NULL; 1470 if( phase->type(n) == Type::TOP ) return NULL; 1471 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN || n->Opcode() == Op_ConNKlass ) 1472 break; 1473 } 1474 if( i >= phi->req() ) // Only split for constants 1475 return NULL; 1476 1477 Node *val = phi->in(i); // Constant to split for 1478 uint hit = 0; // Number of times it occurs 1479 Node *r = phi->region(); 1480 1481 for( ; i < phi->req(); i++ ){ // Count occurrences of constant 1482 Node *n = phi->in(i); 1483 if( !n ) return NULL; 1484 if( phase->type(n) == Type::TOP ) return NULL; 1485 if( phi->in(i) == val ) { 1486 hit++; 1487 if (PhaseIdealLoop::find_predicate(r->in(i)) != NULL) { 1488 return NULL; // don't split loop entry path 1489 } 1490 } 1491 } 1492 1493 if( hit <= 1 || // Make sure we find 2 or more 1494 hit == phi->req()-1 ) // and not ALL the same value 1495 return NULL; 1496 1497 // Now start splitting out the flow paths that merge the same value. 1498 // Split first the RegionNode. 1499 PhaseIterGVN *igvn = phase->is_IterGVN(); 1500 RegionNode *newr = new RegionNode(hit+1); 1501 split_once(igvn, phi, val, r, newr); 1502 1503 // Now split all other Phis than this one 1504 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) { 1505 Node* phi2 = r->fast_out(k); 1506 if( phi2->is_Phi() && phi2->as_Phi() != phi ) { 1507 PhiNode *newphi = PhiNode::make_blank(newr, phi2); 1508 split_once(igvn, phi, val, phi2, newphi); 1509 } 1510 } 1511 1512 // Clean up this guy 1513 igvn->hash_delete(phi); 1514 for( i = phi->req()-1; i > 0; i-- ) { 1515 if( phi->in(i) == val ) { 1516 phi->del_req(i); 1517 } 1518 } 1519 phi->add_req(val); 1520 1521 return phi; 1522 } 1523 1524 //============================================================================= 1525 //------------------------------simple_data_loop_check------------------------- 1526 // Try to determining if the phi node in a simple safe/unsafe data loop. 1527 // Returns: 1528 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop }; 1529 // Safe - safe case when the phi and it's inputs reference only safe data 1530 // nodes; 1531 // Unsafe - the phi and it's inputs reference unsafe data nodes but there 1532 // is no reference back to the phi - need a graph walk 1533 // to determine if it is in a loop; 1534 // UnsafeLoop - unsafe case when the phi references itself directly or through 1535 // unsafe data node. 1536 // Note: a safe data node is a node which could/never reference itself during 1537 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP. 1538 // I mark Phi nodes as safe node not only because they can reference itself 1539 // but also to prevent mistaking the fallthrough case inside an outer loop 1540 // as dead loop when the phi references itselfs through an other phi. 1541 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const { 1542 // It is unsafe loop if the phi node references itself directly. 1543 if (in == (Node*)this) 1544 return UnsafeLoop; // Unsafe loop 1545 // Unsafe loop if the phi node references itself through an unsafe data node. 1546 // Exclude cases with null inputs or data nodes which could reference 1547 // itself (safe for dead loops). 1548 if (in != NULL && !in->is_dead_loop_safe()) { 1549 // Check inputs of phi's inputs also. 1550 // It is much less expensive then full graph walk. 1551 uint cnt = in->req(); 1552 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1; 1553 for (; i < cnt; ++i) { 1554 Node* m = in->in(i); 1555 if (m == (Node*)this) 1556 return UnsafeLoop; // Unsafe loop 1557 if (m != NULL && !m->is_dead_loop_safe()) { 1558 // Check the most common case (about 30% of all cases): 1559 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con). 1560 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL; 1561 if (m1 == (Node*)this) 1562 return UnsafeLoop; // Unsafe loop 1563 if (m1 != NULL && m1 == m->in(2) && 1564 m1->is_dead_loop_safe() && m->in(3)->is_Con()) { 1565 continue; // Safe case 1566 } 1567 // The phi references an unsafe node - need full analysis. 1568 return Unsafe; 1569 } 1570 } 1571 } 1572 return Safe; // Safe case - we can optimize the phi node. 1573 } 1574 1575 //------------------------------is_unsafe_data_reference----------------------- 1576 // If phi can be reached through the data input - it is data loop. 1577 bool PhiNode::is_unsafe_data_reference(Node *in) const { 1578 assert(req() > 1, ""); 1579 // First, check simple cases when phi references itself directly or 1580 // through an other node. 1581 LoopSafety safety = simple_data_loop_check(in); 1582 if (safety == UnsafeLoop) 1583 return true; // phi references itself - unsafe loop 1584 else if (safety == Safe) 1585 return false; // Safe case - phi could be replaced with the unique input. 1586 1587 // Unsafe case when we should go through data graph to determine 1588 // if the phi references itself. 1589 1590 ResourceMark rm; 1591 1592 Arena *a = Thread::current()->resource_area(); 1593 Node_List nstack(a); 1594 VectorSet visited(a); 1595 1596 nstack.push(in); // Start with unique input. 1597 visited.set(in->_idx); 1598 while (nstack.size() != 0) { 1599 Node* n = nstack.pop(); 1600 uint cnt = n->req(); 1601 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1; 1602 for (; i < cnt; i++) { 1603 Node* m = n->in(i); 1604 if (m == (Node*)this) { 1605 return true; // Data loop 1606 } 1607 if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases. 1608 if (!visited.test_set(m->_idx)) 1609 nstack.push(m); 1610 } 1611 } 1612 } 1613 return false; // The phi is not reachable from its inputs 1614 } 1615 1616 1617 //------------------------------Ideal------------------------------------------ 1618 // Return a node which is more "ideal" than the current node. Must preserve 1619 // the CFG, but we can still strip out dead paths. 1620 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1621 // The next should never happen after 6297035 fix. 1622 if( is_copy() ) // Already degraded to a Copy ? 1623 return NULL; // No change 1624 1625 Node *r = in(0); // RegionNode 1626 assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge"); 1627 1628 // Note: During parsing, phis are often transformed before their regions. 1629 // This means we have to use type_or_null to defend against untyped regions. 1630 if( phase->type_or_null(r) == Type::TOP ) // Dead code? 1631 return NULL; // No change 1632 1633 Node *top = phase->C->top(); 1634 bool new_phi = (outcnt() == 0); // transforming new Phi 1635 // No change for igvn if new phi is not hooked 1636 if (new_phi && can_reshape) 1637 return NULL; 1638 1639 // The are 2 situations when only one valid phi's input is left 1640 // (in addition to Region input). 1641 // One: region is not loop - replace phi with this input. 1642 // Two: region is loop - replace phi with top since this data path is dead 1643 // and we need to break the dead data loop. 1644 Node* progress = NULL; // Record if any progress made 1645 for( uint j = 1; j < req(); ++j ){ // For all paths in 1646 // Check unreachable control paths 1647 Node* rc = r->in(j); 1648 Node* n = in(j); // Get the input 1649 if (rc == NULL || phase->type(rc) == Type::TOP) { 1650 if (n != top) { // Not already top? 1651 PhaseIterGVN *igvn = phase->is_IterGVN(); 1652 if (can_reshape && igvn != NULL) { 1653 igvn->_worklist.push(r); 1654 } 1655 set_req(j, top); // Nuke it down 1656 progress = this; // Record progress 1657 } 1658 } 1659 } 1660 1661 if (can_reshape && outcnt() == 0) { 1662 // set_req() above may kill outputs if Phi is referenced 1663 // only by itself on the dead (top) control path. 1664 return top; 1665 } 1666 1667 bool uncasted = false; 1668 Node* uin = unique_input(phase, false); 1669 if (uin == NULL) { 1670 uncasted = true; 1671 uin = unique_input(phase, true); 1672 } 1673 if (uin == top) { // Simplest case: no alive inputs. 1674 if (can_reshape) // IGVN transformation 1675 return top; 1676 else 1677 return NULL; // Identity will return TOP 1678 } else if (uin != NULL) { 1679 // Only one not-NULL unique input path is left. 1680 // Determine if this input is backedge of a loop. 1681 // (Skip new phis which have no uses and dead regions). 1682 if (outcnt() > 0 && r->in(0) != NULL) { 1683 // First, take the short cut when we know it is a loop and 1684 // the EntryControl data path is dead. 1685 // Loop node may have only one input because entry path 1686 // is removed in PhaseIdealLoop::Dominators(). 1687 assert(!r->is_Loop() || r->req() <= 3, "Loop node should have 3 or less inputs"); 1688 bool is_loop = (r->is_Loop() && r->req() == 3); 1689 // Then, check if there is a data loop when phi references itself directly 1690 // or through other data nodes. 1691 if (is_loop && !uin->eqv_uncast(in(LoopNode::EntryControl)) || 1692 !is_loop && is_unsafe_data_reference(uin)) { 1693 // Break this data loop to avoid creation of a dead loop. 1694 if (can_reshape) { 1695 return top; 1696 } else { 1697 // We can't return top if we are in Parse phase - cut inputs only 1698 // let Identity to handle the case. 1699 replace_edge(uin, top); 1700 return NULL; 1701 } 1702 } 1703 } 1704 1705 if (uncasted) { 1706 const Type* phi_type = bottom_type(); 1707 assert(phi_type->isa_int() || phi_type->isa_ptr(), "bad phi type"); 1708 int opcode; 1709 if (phi_type->isa_int()) { 1710 opcode = Op_CastII; 1711 } else { 1712 const Type* uin_type = phase->type(uin); 1713 if (phi_type->join(TypePtr::NOTNULL) == uin_type->join(TypePtr::NOTNULL)) { 1714 opcode = Op_CastPP; 1715 } else { 1716 opcode = Op_CheckCastPP; 1717 } 1718 } 1719 // Add a cast to carry the control dependency of the Phi that is 1720 // going away 1721 Node* cast = ConstraintCastNode::make_cast(opcode, r, uin, phi_type, true); 1722 cast = phase->transform(cast); 1723 // set all inputs to the new cast so the Phi is removed by Identity 1724 for (uint i = 1; i < req(); i++) { 1725 set_req(i, cast); 1726 } 1727 uin = cast; 1728 } 1729 1730 // One unique input. 1731 debug_only(Node* ident = Identity(phase)); 1732 // The unique input must eventually be detected by the Identity call. 1733 #ifdef ASSERT 1734 if (ident != uin && !ident->is_top()) { 1735 // print this output before failing assert 1736 r->dump(3); 1737 this->dump(3); 1738 ident->dump(); 1739 uin->dump(); 1740 } 1741 #endif 1742 assert(ident == uin || ident->is_top(), "Identity must clean this up"); 1743 return NULL; 1744 } 1745 1746 Node* opt = NULL; 1747 int true_path = is_diamond_phi(); 1748 if( true_path != 0 ) { 1749 // Check for CMove'ing identity. If it would be unsafe, 1750 // handle it here. In the safe case, let Identity handle it. 1751 Node* unsafe_id = is_cmove_id(phase, true_path); 1752 if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) ) 1753 opt = unsafe_id; 1754 1755 // Check for simple convert-to-boolean pattern 1756 if( opt == NULL ) 1757 opt = is_x2logic(phase, this, true_path); 1758 1759 // Check for absolute value 1760 if( opt == NULL ) 1761 opt = is_absolute(phase, this, true_path); 1762 1763 // Check for conditional add 1764 if( opt == NULL && can_reshape ) 1765 opt = is_cond_add(phase, this, true_path); 1766 1767 // These 4 optimizations could subsume the phi: 1768 // have to check for a dead data loop creation. 1769 if( opt != NULL ) { 1770 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) { 1771 // Found dead loop. 1772 if( can_reshape ) 1773 return top; 1774 // We can't return top if we are in Parse phase - cut inputs only 1775 // to stop further optimizations for this phi. Identity will return TOP. 1776 assert(req() == 3, "only diamond merge phi here"); 1777 set_req(1, top); 1778 set_req(2, top); 1779 return NULL; 1780 } else { 1781 return opt; 1782 } 1783 } 1784 } 1785 1786 // Check for merging identical values and split flow paths 1787 if (can_reshape) { 1788 opt = split_flow_path(phase, this); 1789 // This optimization only modifies phi - don't need to check for dead loop. 1790 assert(opt == NULL || phase->eqv(opt, this), "do not elide phi"); 1791 if (opt != NULL) return opt; 1792 } 1793 1794 if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) { 1795 // Try to undo Phi of AddP: 1796 // (Phi (AddP base base y) (AddP base2 base2 y)) 1797 // becomes: 1798 // newbase := (Phi base base2) 1799 // (AddP newbase newbase y) 1800 // 1801 // This occurs as a result of unsuccessful split_thru_phi and 1802 // interferes with taking advantage of addressing modes. See the 1803 // clone_shift_expressions code in matcher.cpp 1804 Node* addp = in(1); 1805 const Type* type = addp->in(AddPNode::Base)->bottom_type(); 1806 Node* y = addp->in(AddPNode::Offset); 1807 if (y != NULL && addp->in(AddPNode::Base) == addp->in(AddPNode::Address)) { 1808 // make sure that all the inputs are similar to the first one, 1809 // i.e. AddP with base == address and same offset as first AddP 1810 bool doit = true; 1811 for (uint i = 2; i < req(); i++) { 1812 if (in(i) == NULL || 1813 in(i)->Opcode() != Op_AddP || 1814 in(i)->in(AddPNode::Base) != in(i)->in(AddPNode::Address) || 1815 in(i)->in(AddPNode::Offset) != y) { 1816 doit = false; 1817 break; 1818 } 1819 // Accumulate type for resulting Phi 1820 type = type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type()); 1821 } 1822 Node* base = NULL; 1823 if (doit) { 1824 // Check for neighboring AddP nodes in a tree. 1825 // If they have a base, use that it. 1826 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) { 1827 Node* u = this->fast_out(k); 1828 if (u->is_AddP()) { 1829 Node* base2 = u->in(AddPNode::Base); 1830 if (base2 != NULL && !base2->is_top()) { 1831 if (base == NULL) 1832 base = base2; 1833 else if (base != base2) 1834 { doit = false; break; } 1835 } 1836 } 1837 } 1838 } 1839 if (doit) { 1840 if (base == NULL) { 1841 base = new PhiNode(in(0), type, NULL); 1842 for (uint i = 1; i < req(); i++) { 1843 base->init_req(i, in(i)->in(AddPNode::Base)); 1844 } 1845 phase->is_IterGVN()->register_new_node_with_optimizer(base); 1846 } 1847 return new AddPNode(base, base, y); 1848 } 1849 } 1850 } 1851 1852 // Split phis through memory merges, so that the memory merges will go away. 1853 // Piggy-back this transformation on the search for a unique input.... 1854 // It will be as if the merged memory is the unique value of the phi. 1855 // (Do not attempt this optimization unless parsing is complete. 1856 // It would make the parser's memory-merge logic sick.) 1857 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.) 1858 if (progress == NULL && can_reshape && type() == Type::MEMORY) { 1859 // see if this phi should be sliced 1860 uint merge_width = 0; 1861 bool saw_self = false; 1862 for( uint i=1; i<req(); ++i ) {// For all paths in 1863 Node *ii = in(i); 1864 if (ii->is_MergeMem()) { 1865 MergeMemNode* n = ii->as_MergeMem(); 1866 merge_width = MAX2(merge_width, n->req()); 1867 saw_self = saw_self || phase->eqv(n->base_memory(), this); 1868 } 1869 } 1870 1871 // This restriction is temporarily necessary to ensure termination: 1872 if (!saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0; 1873 1874 if (merge_width > Compile::AliasIdxRaw) { 1875 // found at least one non-empty MergeMem 1876 const TypePtr* at = adr_type(); 1877 if (at != TypePtr::BOTTOM) { 1878 // Patch the existing phi to select an input from the merge: 1879 // Phi:AT1(...MergeMem(m0, m1, m2)...) into 1880 // Phi:AT1(...m1...) 1881 int alias_idx = phase->C->get_alias_index(at); 1882 for (uint i=1; i<req(); ++i) { 1883 Node *ii = in(i); 1884 if (ii->is_MergeMem()) { 1885 MergeMemNode* n = ii->as_MergeMem(); 1886 // compress paths and change unreachable cycles to TOP 1887 // If not, we can update the input infinitely along a MergeMem cycle 1888 // Equivalent code is in MemNode::Ideal_common 1889 Node *m = phase->transform(n); 1890 if (outcnt() == 0) { // Above transform() may kill us! 1891 return top; 1892 } 1893 // If transformed to a MergeMem, get the desired slice 1894 // Otherwise the returned node represents memory for every slice 1895 Node *new_mem = (m->is_MergeMem()) ? 1896 m->as_MergeMem()->memory_at(alias_idx) : m; 1897 // Update input if it is progress over what we have now 1898 if (new_mem != ii) { 1899 set_req(i, new_mem); 1900 progress = this; 1901 } 1902 } 1903 } 1904 } else { 1905 // We know that at least one MergeMem->base_memory() == this 1906 // (saw_self == true). If all other inputs also references this phi 1907 // (directly or through data nodes) - it is dead loop. 1908 bool saw_safe_input = false; 1909 for (uint j = 1; j < req(); ++j) { 1910 Node *n = in(j); 1911 if (n->is_MergeMem() && n->as_MergeMem()->base_memory() == this) 1912 continue; // skip known cases 1913 if (!is_unsafe_data_reference(n)) { 1914 saw_safe_input = true; // found safe input 1915 break; 1916 } 1917 } 1918 if (!saw_safe_input) 1919 return top; // all inputs reference back to this phi - dead loop 1920 1921 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into 1922 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...)) 1923 PhaseIterGVN *igvn = phase->is_IterGVN(); 1924 Node* hook = new Node(1); 1925 PhiNode* new_base = (PhiNode*) clone(); 1926 // Must eagerly register phis, since they participate in loops. 1927 if (igvn) { 1928 igvn->register_new_node_with_optimizer(new_base); 1929 hook->add_req(new_base); 1930 } 1931 MergeMemNode* result = MergeMemNode::make(new_base); 1932 for (uint i = 1; i < req(); ++i) { 1933 Node *ii = in(i); 1934 if (ii->is_MergeMem()) { 1935 MergeMemNode* n = ii->as_MergeMem(); 1936 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) { 1937 // If we have not seen this slice yet, make a phi for it. 1938 bool made_new_phi = false; 1939 if (mms.is_empty()) { 1940 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C)); 1941 made_new_phi = true; 1942 if (igvn) { 1943 igvn->register_new_node_with_optimizer(new_phi); 1944 hook->add_req(new_phi); 1945 } 1946 mms.set_memory(new_phi); 1947 } 1948 Node* phi = mms.memory(); 1949 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice"); 1950 phi->set_req(i, mms.memory2()); 1951 } 1952 } 1953 } 1954 // Distribute all self-loops. 1955 { // (Extra braces to hide mms.) 1956 for (MergeMemStream mms(result); mms.next_non_empty(); ) { 1957 Node* phi = mms.memory(); 1958 for (uint i = 1; i < req(); ++i) { 1959 if (phi->in(i) == this) phi->set_req(i, phi); 1960 } 1961 } 1962 } 1963 // now transform the new nodes, and return the mergemem 1964 for (MergeMemStream mms(result); mms.next_non_empty(); ) { 1965 Node* phi = mms.memory(); 1966 mms.set_memory(phase->transform(phi)); 1967 } 1968 if (igvn) { // Unhook. 1969 igvn->hash_delete(hook); 1970 for (uint i = 1; i < hook->req(); i++) { 1971 hook->set_req(i, NULL); 1972 } 1973 } 1974 // Replace self with the result. 1975 return result; 1976 } 1977 } 1978 // 1979 // Other optimizations on the memory chain 1980 // 1981 const TypePtr* at = adr_type(); 1982 for( uint i=1; i<req(); ++i ) {// For all paths in 1983 Node *ii = in(i); 1984 Node *new_in = MemNode::optimize_memory_chain(ii, at, NULL, phase); 1985 if (ii != new_in ) { 1986 set_req(i, new_in); 1987 progress = this; 1988 } 1989 } 1990 } 1991 1992 #ifdef _LP64 1993 // Push DecodeN/DecodeNKlass down through phi. 1994 // The rest of phi graph will transform by split EncodeP node though phis up. 1995 if ((UseCompressedOops || UseCompressedClassPointers) && can_reshape && progress == NULL) { 1996 bool may_push = true; 1997 bool has_decodeN = false; 1998 bool is_decodeN = false; 1999 for (uint i=1; i<req(); ++i) {// For all paths in 2000 Node *ii = in(i); 2001 if (ii->is_DecodeNarrowPtr() && ii->bottom_type() == bottom_type()) { 2002 // Do optimization if a non dead path exist. 2003 if (ii->in(1)->bottom_type() != Type::TOP) { 2004 has_decodeN = true; 2005 is_decodeN = ii->is_DecodeN(); 2006 } 2007 } else if (!ii->is_Phi()) { 2008 may_push = false; 2009 } 2010 } 2011 2012 if (has_decodeN && may_push) { 2013 PhaseIterGVN *igvn = phase->is_IterGVN(); 2014 // Make narrow type for new phi. 2015 const Type* narrow_t; 2016 if (is_decodeN) { 2017 narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr()); 2018 } else { 2019 narrow_t = TypeNarrowKlass::make(this->bottom_type()->is_ptr()); 2020 } 2021 PhiNode* new_phi = new PhiNode(r, narrow_t); 2022 uint orig_cnt = req(); 2023 for (uint i=1; i<req(); ++i) {// For all paths in 2024 Node *ii = in(i); 2025 Node* new_ii = NULL; 2026 if (ii->is_DecodeNarrowPtr()) { 2027 assert(ii->bottom_type() == bottom_type(), "sanity"); 2028 new_ii = ii->in(1); 2029 } else { 2030 assert(ii->is_Phi(), "sanity"); 2031 if (ii->as_Phi() == this) { 2032 new_ii = new_phi; 2033 } else { 2034 if (is_decodeN) { 2035 new_ii = new EncodePNode(ii, narrow_t); 2036 } else { 2037 new_ii = new EncodePKlassNode(ii, narrow_t); 2038 } 2039 igvn->register_new_node_with_optimizer(new_ii); 2040 } 2041 } 2042 new_phi->set_req(i, new_ii); 2043 } 2044 igvn->register_new_node_with_optimizer(new_phi, this); 2045 if (is_decodeN) { 2046 progress = new DecodeNNode(new_phi, bottom_type()); 2047 } else { 2048 progress = new DecodeNKlassNode(new_phi, bottom_type()); 2049 } 2050 } 2051 } 2052 #endif 2053 2054 return progress; // Return any progress 2055 } 2056 2057 //------------------------------is_tripcount----------------------------------- 2058 bool PhiNode::is_tripcount() const { 2059 return (in(0) != NULL && in(0)->is_CountedLoop() && 2060 in(0)->as_CountedLoop()->phi() == this); 2061 } 2062 2063 //------------------------------out_RegMask------------------------------------ 2064 const RegMask &PhiNode::in_RegMask(uint i) const { 2065 return i ? out_RegMask() : RegMask::Empty; 2066 } 2067 2068 const RegMask &PhiNode::out_RegMask() const { 2069 uint ideal_reg = _type->ideal_reg(); 2070 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" ); 2071 if( ideal_reg == 0 ) return RegMask::Empty; 2072 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]); 2073 } 2074 2075 #ifndef PRODUCT 2076 void PhiNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const { 2077 // For a PhiNode, the set of related nodes includes all inputs till level 2, 2078 // and all outputs till level 1. In compact mode, inputs till level 1 are 2079 // collected. 2080 this->collect_nodes(in_rel, compact ? 1 : 2, false, false); 2081 this->collect_nodes(out_rel, -1, false, false); 2082 } 2083 2084 void PhiNode::dump_spec(outputStream *st) const { 2085 TypeNode::dump_spec(st); 2086 if (is_tripcount()) { 2087 st->print(" #tripcount"); 2088 } 2089 } 2090 #endif 2091 2092 2093 //============================================================================= 2094 const Type* GotoNode::Value(PhaseGVN* phase) const { 2095 // If the input is reachable, then we are executed. 2096 // If the input is not reachable, then we are not executed. 2097 return phase->type(in(0)); 2098 } 2099 2100 Node* GotoNode::Identity(PhaseGVN* phase) { 2101 return in(0); // Simple copy of incoming control 2102 } 2103 2104 const RegMask &GotoNode::out_RegMask() const { 2105 return RegMask::Empty; 2106 } 2107 2108 #ifndef PRODUCT 2109 //-----------------------------related----------------------------------------- 2110 // The related nodes of a GotoNode are all inputs at level 1, as well as the 2111 // outputs at level 1. This is regardless of compact mode. 2112 void GotoNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const { 2113 this->collect_nodes(in_rel, 1, false, false); 2114 this->collect_nodes(out_rel, -1, false, false); 2115 } 2116 #endif 2117 2118 2119 //============================================================================= 2120 const RegMask &JumpNode::out_RegMask() const { 2121 return RegMask::Empty; 2122 } 2123 2124 #ifndef PRODUCT 2125 //-----------------------------related----------------------------------------- 2126 // The related nodes of a JumpNode are all inputs at level 1, as well as the 2127 // outputs at level 2 (to include actual jump targets beyond projection nodes). 2128 // This is regardless of compact mode. 2129 void JumpNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const { 2130 this->collect_nodes(in_rel, 1, false, false); 2131 this->collect_nodes(out_rel, -2, false, false); 2132 } 2133 #endif 2134 2135 //============================================================================= 2136 const RegMask &JProjNode::out_RegMask() const { 2137 return RegMask::Empty; 2138 } 2139 2140 //============================================================================= 2141 const RegMask &CProjNode::out_RegMask() const { 2142 return RegMask::Empty; 2143 } 2144 2145 2146 2147 //============================================================================= 2148 2149 uint PCTableNode::hash() const { return Node::hash() + _size; } 2150 uint PCTableNode::cmp( const Node &n ) const 2151 { return _size == ((PCTableNode&)n)._size; } 2152 2153 const Type *PCTableNode::bottom_type() const { 2154 const Type** f = TypeTuple::fields(_size); 2155 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL; 2156 return TypeTuple::make(_size, f); 2157 } 2158 2159 //------------------------------Value------------------------------------------ 2160 // Compute the type of the PCTableNode. If reachable it is a tuple of 2161 // Control, otherwise the table targets are not reachable 2162 const Type* PCTableNode::Value(PhaseGVN* phase) const { 2163 if( phase->type(in(0)) == Type::CONTROL ) 2164 return bottom_type(); 2165 return Type::TOP; // All paths dead? Then so are we 2166 } 2167 2168 //------------------------------Ideal------------------------------------------ 2169 // Return a node which is more "ideal" than the current node. Strip out 2170 // control copies 2171 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2172 return remove_dead_region(phase, can_reshape) ? this : NULL; 2173 } 2174 2175 //============================================================================= 2176 uint JumpProjNode::hash() const { 2177 return Node::hash() + _dest_bci; 2178 } 2179 2180 uint JumpProjNode::cmp( const Node &n ) const { 2181 return ProjNode::cmp(n) && 2182 _dest_bci == ((JumpProjNode&)n)._dest_bci; 2183 } 2184 2185 #ifndef PRODUCT 2186 void JumpProjNode::dump_spec(outputStream *st) const { 2187 ProjNode::dump_spec(st); 2188 st->print("@bci %d ",_dest_bci); 2189 } 2190 2191 void JumpProjNode::dump_compact_spec(outputStream *st) const { 2192 ProjNode::dump_compact_spec(st); 2193 st->print("(%d)%d@%d", _switch_val, _proj_no, _dest_bci); 2194 } 2195 2196 void JumpProjNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const { 2197 // The related nodes of a JumpProjNode are its inputs and outputs at level 1. 2198 this->collect_nodes(in_rel, 1, false, false); 2199 this->collect_nodes(out_rel, -1, false, false); 2200 } 2201 #endif 2202 2203 //============================================================================= 2204 //------------------------------Value------------------------------------------ 2205 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot 2206 // have the default "fall_through_index" path. 2207 const Type* CatchNode::Value(PhaseGVN* phase) const { 2208 // Unreachable? Then so are all paths from here. 2209 if( phase->type(in(0)) == Type::TOP ) return Type::TOP; 2210 // First assume all paths are reachable 2211 const Type** f = TypeTuple::fields(_size); 2212 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL; 2213 // Identify cases that will always throw an exception 2214 // () rethrow call 2215 // () virtual or interface call with NULL receiver 2216 // () call is a check cast with incompatible arguments 2217 if( in(1)->is_Proj() ) { 2218 Node *i10 = in(1)->in(0); 2219 if( i10->is_Call() ) { 2220 CallNode *call = i10->as_Call(); 2221 // Rethrows always throw exceptions, never return 2222 if (call->entry_point() == OptoRuntime::rethrow_stub()) { 2223 f[CatchProjNode::fall_through_index] = Type::TOP; 2224 } else if( call->req() > TypeFunc::Parms ) { 2225 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) ); 2226 // Check for null receiver to virtual or interface calls 2227 if( call->is_CallDynamicJava() && 2228 arg0->higher_equal(TypePtr::NULL_PTR) ) { 2229 f[CatchProjNode::fall_through_index] = Type::TOP; 2230 } 2231 } // End of if not a runtime stub 2232 } // End of if have call above me 2233 } // End of slot 1 is not a projection 2234 return TypeTuple::make(_size, f); 2235 } 2236 2237 //============================================================================= 2238 uint CatchProjNode::hash() const { 2239 return Node::hash() + _handler_bci; 2240 } 2241 2242 2243 uint CatchProjNode::cmp( const Node &n ) const { 2244 return ProjNode::cmp(n) && 2245 _handler_bci == ((CatchProjNode&)n)._handler_bci; 2246 } 2247 2248 2249 //------------------------------Identity--------------------------------------- 2250 // If only 1 target is possible, choose it if it is the main control 2251 Node* CatchProjNode::Identity(PhaseGVN* phase) { 2252 // If my value is control and no other value is, then treat as ID 2253 const TypeTuple *t = phase->type(in(0))->is_tuple(); 2254 if (t->field_at(_con) != Type::CONTROL) return this; 2255 // If we remove the last CatchProj and elide the Catch/CatchProj, then we 2256 // also remove any exception table entry. Thus we must know the call 2257 // feeding the Catch will not really throw an exception. This is ok for 2258 // the main fall-thru control (happens when we know a call can never throw 2259 // an exception) or for "rethrow", because a further optimization will 2260 // yank the rethrow (happens when we inline a function that can throw an 2261 // exception and the caller has no handler). Not legal, e.g., for passing 2262 // a NULL receiver to a v-call, or passing bad types to a slow-check-cast. 2263 // These cases MUST throw an exception via the runtime system, so the VM 2264 // will be looking for a table entry. 2265 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode 2266 CallNode *call; 2267 if (_con != TypeFunc::Control && // Bail out if not the main control. 2268 !(proj->is_Proj() && // AND NOT a rethrow 2269 proj->in(0)->is_Call() && 2270 (call = proj->in(0)->as_Call()) && 2271 call->entry_point() == OptoRuntime::rethrow_stub())) 2272 return this; 2273 2274 // Search for any other path being control 2275 for (uint i = 0; i < t->cnt(); i++) { 2276 if (i != _con && t->field_at(i) == Type::CONTROL) 2277 return this; 2278 } 2279 // Only my path is possible; I am identity on control to the jump 2280 return in(0)->in(0); 2281 } 2282 2283 2284 #ifndef PRODUCT 2285 void CatchProjNode::dump_spec(outputStream *st) const { 2286 ProjNode::dump_spec(st); 2287 st->print("@bci %d ",_handler_bci); 2288 } 2289 #endif 2290 2291 //============================================================================= 2292 //------------------------------Identity--------------------------------------- 2293 // Check for CreateEx being Identity. 2294 Node* CreateExNode::Identity(PhaseGVN* phase) { 2295 if( phase->type(in(1)) == Type::TOP ) return in(1); 2296 if( phase->type(in(0)) == Type::TOP ) return in(0); 2297 // We only come from CatchProj, unless the CatchProj goes away. 2298 // If the CatchProj is optimized away, then we just carry the 2299 // exception oop through. 2300 CallNode *call = in(1)->in(0)->as_Call(); 2301 2302 return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) ) 2303 ? this 2304 : call->in(TypeFunc::Parms); 2305 } 2306 2307 //============================================================================= 2308 //------------------------------Value------------------------------------------ 2309 // Check for being unreachable. 2310 const Type* NeverBranchNode::Value(PhaseGVN* phase) const { 2311 if (!in(0) || in(0)->is_top()) return Type::TOP; 2312 return bottom_type(); 2313 } 2314 2315 //------------------------------Ideal------------------------------------------ 2316 // Check for no longer being part of a loop 2317 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2318 if (can_reshape && !in(0)->is_Loop()) { 2319 // Dead code elimination can sometimes delete this projection so 2320 // if it's not there, there's nothing to do. 2321 Node* fallthru = proj_out(0); 2322 if (fallthru != NULL) { 2323 phase->is_IterGVN()->replace_node(fallthru, in(0)); 2324 } 2325 return phase->C->top(); 2326 } 2327 return NULL; 2328 } 2329 2330 #ifndef PRODUCT 2331 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const { 2332 st->print("%s", Name()); 2333 } 2334 #endif