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