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