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