1 /* 2 * Copyright (c) 1997, 2010, 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 assert(!this->is_Loop() || cnt_orig == 3, "Loop node should have 3 inputs"); 464 if (this->is_Loop() && del_it == LoopNode::EntryControl || 465 !this->is_Loop() && has_phis && is_unreachable_region(phase)) { 466 // Yes, the region will be removed during the next step below. 467 // Cut the backedge input and remove phis since no data paths left. 468 // We don't cut outputs to other nodes here since we need to put them 469 // on the worklist. 470 del_req(1); 471 cnt = 0; 472 assert( req() == 1, "no more inputs expected" ); 473 uint max = outcnt(); 474 bool progress = true; 475 Node *top = phase->C->top(); 476 PhaseIterGVN *igvn = phase->is_IterGVN(); 477 DUIterator j; 478 while(progress) { 479 progress = false; 480 for (j = outs(); has_out(j); j++) { 481 Node *n = out(j); 482 if( n->is_Phi() ) { 483 assert( igvn->eqv(n->in(0), this), "" ); 484 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" ); 485 // Break dead loop data path. 486 // Eagerly replace phis with top to avoid phis copies generation. 487 igvn->replace_node(n, top); 488 if( max != outcnt() ) { 489 progress = true; 490 j = refresh_out_pos(j); 491 max = outcnt(); 492 } 493 } 494 } 495 } 496 add_to_worklist = true; 497 } 498 } 499 if (add_to_worklist) { 500 phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis 501 } 502 503 if( cnt <= 1 ) { // Only 1 path in? 504 set_req(0, NULL); // Null control input for region copy 505 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is. 506 // No inputs or all inputs are NULL. 507 return NULL; 508 } else if (can_reshape) { // Optimization phase - remove the node 509 PhaseIterGVN *igvn = phase->is_IterGVN(); 510 Node *parent_ctrl; 511 if( cnt == 0 ) { 512 assert( req() == 1, "no inputs expected" ); 513 // During IGVN phase such region will be subsumed by TOP node 514 // so region's phis will have TOP as control node. 515 // Kill phis here to avoid it. PhiNode::is_copy() will be always false. 516 // Also set other user's input to top. 517 parent_ctrl = phase->C->top(); 518 } else { 519 // The fallthrough case since we already checked dead loops above. 520 parent_ctrl = in(1); 521 assert(parent_ctrl != NULL, "Region is a copy of some non-null control"); 522 assert(!igvn->eqv(parent_ctrl, this), "Close dead loop"); 523 } 524 if (!add_to_worklist) 525 igvn->add_users_to_worklist(this); // Check for further allowed opts 526 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) { 527 Node* n = last_out(i); 528 igvn->hash_delete(n); // Remove from worklist before modifying edges 529 if( n->is_Phi() ) { // Collapse all Phis 530 // Eagerly replace phis to avoid copies generation. 531 Node* in; 532 if( cnt == 0 ) { 533 assert( n->req() == 1, "No data inputs expected" ); 534 in = parent_ctrl; // replaced by top 535 } else { 536 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" ); 537 in = n->in(1); // replaced by unique input 538 if( n->as_Phi()->is_unsafe_data_reference(in) ) 539 in = phase->C->top(); // replaced by top 540 } 541 igvn->replace_node(n, in); 542 } 543 else if( n->is_Region() ) { // Update all incoming edges 544 assert( !igvn->eqv(n, this), "Must be removed from DefUse edges"); 545 uint uses_found = 0; 546 for( uint k=1; k < n->req(); k++ ) { 547 if( n->in(k) == this ) { 548 n->set_req(k, parent_ctrl); 549 uses_found++; 550 } 551 } 552 if( uses_found > 1 ) { // (--i) done at the end of the loop. 553 i -= (uses_found - 1); 554 } 555 } 556 else { 557 assert( igvn->eqv(n->in(0), this), "Expect RegionNode to be control parent"); 558 n->set_req(0, parent_ctrl); 559 } 560 #ifdef ASSERT 561 for( uint k=0; k < n->req(); k++ ) { 562 assert( !igvn->eqv(n->in(k), this), "All uses of RegionNode should be gone"); 563 } 564 #endif 565 } 566 // Remove the RegionNode itself from DefUse info 567 igvn->remove_dead_node(this); 568 return NULL; 569 } 570 return this; // Record progress 571 } 572 573 574 // If a Region flows into a Region, merge into one big happy merge. 575 if (can_reshape) { 576 Node *m = merge_region(this, phase); 577 if (m != NULL) return m; 578 } 579 580 // Check if this region is the root of a clipping idiom on floats 581 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) { 582 // Check that only one use is a Phi and that it simplifies to two constants + 583 PhiNode* phi = has_unique_phi(); 584 if (phi != NULL) { // One Phi user 585 // Check inputs to the Phi 586 ConNode *min; 587 ConNode *max; 588 Node *val; 589 uint min_idx; 590 uint max_idx; 591 uint val_idx; 592 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) { 593 IfNode *top_if; 594 IfNode *bot_if; 595 if( check_if_clipping( this, bot_if, top_if ) ) { 596 // Control pattern checks, now verify compares 597 Node *top_in = NULL; // value being compared against 598 Node *bot_in = NULL; 599 if( check_compare_clipping( true, bot_if, min, bot_in ) && 600 check_compare_clipping( false, top_if, max, top_in ) ) { 601 if( bot_in == top_in ) { 602 PhaseIterGVN *gvn = phase->is_IterGVN(); 603 assert( gvn != NULL, "Only had DefUse info in IterGVN"); 604 // Only remaining check is that bot_in == top_in == (Phi's val + mods) 605 606 // Check for the ConvF2INode 607 ConvF2INode *convf2i; 608 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) && 609 convf2i->in(1) == bot_in ) { 610 // Matched pattern, including LShiftI; RShiftI, replace with integer compares 611 // max test 612 Node *cmp = gvn->register_new_node_with_optimizer(new (phase->C, 3) CmpINode( convf2i, min )); 613 Node *boo = gvn->register_new_node_with_optimizer(new (phase->C, 2) BoolNode( cmp, BoolTest::lt )); 614 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new (phase->C, 2) IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt )); 615 Node *if_min= gvn->register_new_node_with_optimizer(new (phase->C, 1) IfTrueNode (iff)); 616 Node *ifF = gvn->register_new_node_with_optimizer(new (phase->C, 1) IfFalseNode(iff)); 617 // min test 618 cmp = gvn->register_new_node_with_optimizer(new (phase->C, 3) CmpINode( convf2i, max )); 619 boo = gvn->register_new_node_with_optimizer(new (phase->C, 2) BoolNode( cmp, BoolTest::gt )); 620 iff = (IfNode*)gvn->register_new_node_with_optimizer(new (phase->C, 2) IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt )); 621 Node *if_max= gvn->register_new_node_with_optimizer(new (phase->C, 1) IfTrueNode (iff)); 622 ifF = gvn->register_new_node_with_optimizer(new (phase->C, 1) IfFalseNode(iff)); 623 // update input edges to region node 624 set_req_X( min_idx, if_min, gvn ); 625 set_req_X( max_idx, if_max, gvn ); 626 set_req_X( val_idx, ifF, gvn ); 627 // remove unnecessary 'LShiftI; RShiftI' idiom 628 gvn->hash_delete(phi); 629 phi->set_req_X( val_idx, convf2i, gvn ); 630 gvn->hash_find_insert(phi); 631 // Return transformed region node 632 return this; 633 } 634 } 635 } 636 } 637 } 638 } 639 } 640 641 return NULL; 642 } 643 644 645 646 const RegMask &RegionNode::out_RegMask() const { 647 return RegMask::Empty; 648 } 649 650 // Find the one non-null required input. RegionNode only 651 Node *Node::nonnull_req() const { 652 assert( is_Region(), "" ); 653 for( uint i = 1; i < _cnt; i++ ) 654 if( in(i) ) 655 return in(i); 656 ShouldNotReachHere(); 657 return NULL; 658 } 659 660 661 //============================================================================= 662 // note that these functions assume that the _adr_type field is flattened 663 uint PhiNode::hash() const { 664 const Type* at = _adr_type; 665 return TypeNode::hash() + (at ? at->hash() : 0); 666 } 667 uint PhiNode::cmp( const Node &n ) const { 668 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type; 669 } 670 static inline 671 const TypePtr* flatten_phi_adr_type(const TypePtr* at) { 672 if (at == NULL || at == TypePtr::BOTTOM) return at; 673 return Compile::current()->alias_type(at)->adr_type(); 674 } 675 676 //----------------------------make--------------------------------------------- 677 // create a new phi with edges matching r and set (initially) to x 678 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) { 679 uint preds = r->req(); // Number of predecessor paths 680 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at"); 681 PhiNode* p = new (Compile::current(), preds) PhiNode(r, t, at); 682 for (uint j = 1; j < preds; j++) { 683 // Fill in all inputs, except those which the region does not yet have 684 if (r->in(j) != NULL) 685 p->init_req(j, x); 686 } 687 return p; 688 } 689 PhiNode* PhiNode::make(Node* r, Node* x) { 690 const Type* t = x->bottom_type(); 691 const TypePtr* at = NULL; 692 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type()); 693 return make(r, x, t, at); 694 } 695 PhiNode* PhiNode::make_blank(Node* r, Node* x) { 696 const Type* t = x->bottom_type(); 697 const TypePtr* at = NULL; 698 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type()); 699 return new (Compile::current(), r->req()) PhiNode(r, t, at); 700 } 701 702 703 //------------------------slice_memory----------------------------------------- 704 // create a new phi with narrowed memory type 705 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const { 706 PhiNode* mem = (PhiNode*) clone(); 707 *(const TypePtr**)&mem->_adr_type = adr_type; 708 // convert self-loops, or else we get a bad graph 709 for (uint i = 1; i < req(); i++) { 710 if ((const Node*)in(i) == this) mem->set_req(i, mem); 711 } 712 mem->verify_adr_type(); 713 return mem; 714 } 715 716 //------------------------split_out_instance----------------------------------- 717 // Split out an instance type from a bottom phi. 718 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const { 719 const TypeOopPtr *t_oop = at->isa_oopptr(); 720 assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr"); 721 const TypePtr *t = adr_type(); 722 assert(type() == Type::MEMORY && 723 (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM || 724 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() && 725 t->is_oopptr()->cast_to_exactness(true) 726 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr()) 727 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop), 728 "bottom or raw memory required"); 729 730 // Check if an appropriate node already exists. 731 Node *region = in(0); 732 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) { 733 Node* use = region->fast_out(k); 734 if( use->is_Phi()) { 735 PhiNode *phi2 = use->as_Phi(); 736 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) { 737 return phi2; 738 } 739 } 740 } 741 Compile *C = igvn->C; 742 Arena *a = Thread::current()->resource_area(); 743 Node_Array node_map = new Node_Array(a); 744 Node_Stack stack(a, C->unique() >> 4); 745 PhiNode *nphi = slice_memory(at); 746 igvn->register_new_node_with_optimizer( nphi ); 747 node_map.map(_idx, nphi); 748 stack.push((Node *)this, 1); 749 while(!stack.is_empty()) { 750 PhiNode *ophi = stack.node()->as_Phi(); 751 uint i = stack.index(); 752 assert(i >= 1, "not control edge"); 753 stack.pop(); 754 nphi = node_map[ophi->_idx]->as_Phi(); 755 for (; i < ophi->req(); i++) { 756 Node *in = ophi->in(i); 757 if (in == NULL || igvn->type(in) == Type::TOP) 758 continue; 759 Node *opt = MemNode::optimize_simple_memory_chain(in, at, igvn); 760 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL; 761 if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) { 762 opt = node_map[optphi->_idx]; 763 if (opt == NULL) { 764 stack.push(ophi, i); 765 nphi = optphi->slice_memory(at); 766 igvn->register_new_node_with_optimizer( nphi ); 767 node_map.map(optphi->_idx, nphi); 768 ophi = optphi; 769 i = 0; // will get incremented at top of loop 770 continue; 771 } 772 } 773 nphi->set_req(i, opt); 774 } 775 } 776 return nphi; 777 } 778 779 //------------------------verify_adr_type-------------------------------------- 780 #ifdef ASSERT 781 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const { 782 if (visited.test_set(_idx)) return; //already visited 783 784 // recheck constructor invariants: 785 verify_adr_type(false); 786 787 // recheck local phi/phi consistency: 788 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM, 789 "adr_type must be consistent across phi nest"); 790 791 // walk around 792 for (uint i = 1; i < req(); i++) { 793 Node* n = in(i); 794 if (n == NULL) continue; 795 const Node* np = in(i); 796 if (np->is_Phi()) { 797 np->as_Phi()->verify_adr_type(visited, at); 798 } else if (n->bottom_type() == Type::TOP 799 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) { 800 // ignore top inputs 801 } else { 802 const TypePtr* nat = flatten_phi_adr_type(n->adr_type()); 803 // recheck phi/non-phi consistency at leaves: 804 assert((nat != NULL) == (at != NULL), ""); 805 assert(nat == at || nat == TypePtr::BOTTOM, 806 "adr_type must be consistent at leaves of phi nest"); 807 } 808 } 809 } 810 811 // Verify a whole nest of phis rooted at this one. 812 void PhiNode::verify_adr_type(bool recursive) const { 813 if (is_error_reported()) return; // muzzle asserts when debugging an error 814 if (Node::in_dump()) return; // muzzle asserts when printing 815 816 assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only"); 817 818 if (!VerifyAliases) return; // verify thoroughly only if requested 819 820 assert(_adr_type == flatten_phi_adr_type(_adr_type), 821 "Phi::adr_type must be pre-normalized"); 822 823 if (recursive) { 824 VectorSet visited(Thread::current()->resource_area()); 825 verify_adr_type(visited, _adr_type); 826 } 827 } 828 #endif 829 830 831 //------------------------------Value------------------------------------------ 832 // Compute the type of the PhiNode 833 const Type *PhiNode::Value( PhaseTransform *phase ) const { 834 Node *r = in(0); // RegionNode 835 if( !r ) // Copy or dead 836 return in(1) ? phase->type(in(1)) : Type::TOP; 837 838 // Note: During parsing, phis are often transformed before their regions. 839 // This means we have to use type_or_null to defend against untyped regions. 840 if( phase->type_or_null(r) == Type::TOP ) // Dead code? 841 return Type::TOP; 842 843 // Check for trip-counted loop. If so, be smarter. 844 CountedLoopNode *l = r->is_CountedLoop() ? r->as_CountedLoop() : NULL; 845 if( l && l->can_be_counted_loop(phase) && 846 ((const Node*)l->phi() == this) ) { // Trip counted loop! 847 // protect against init_trip() or limit() returning NULL 848 const Node *init = l->init_trip(); 849 const Node *limit = l->limit(); 850 if( init != NULL && limit != NULL && l->stride_is_con() ) { 851 const TypeInt *lo = init ->bottom_type()->isa_int(); 852 const TypeInt *hi = limit->bottom_type()->isa_int(); 853 if( lo && hi ) { // Dying loops might have TOP here 854 int stride = l->stride_con(); 855 if( stride < 0 ) { // Down-counter loop 856 const TypeInt *tmp = lo; lo = hi; hi = tmp; 857 stride = -stride; 858 } 859 if( lo->_hi < hi->_lo ) // Reversed endpoints are well defined :-( 860 return TypeInt::make(lo->_lo,hi->_hi,3); 861 } 862 } 863 } 864 865 // Until we have harmony between classes and interfaces in the type 866 // lattice, we must tread carefully around phis which implicitly 867 // convert the one to the other. 868 const TypePtr* ttp = _type->make_ptr(); 869 const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL; 870 const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_klassptr() : NULL; 871 bool is_intf = false; 872 if (ttip != NULL) { 873 ciKlass* k = ttip->klass(); 874 if (k->is_loaded() && k->is_interface()) 875 is_intf = true; 876 } 877 if (ttkp != NULL) { 878 ciKlass* k = ttkp->klass(); 879 if (k->is_loaded() && k->is_interface()) 880 is_intf = true; 881 } 882 883 // Default case: merge all inputs 884 const Type *t = Type::TOP; // Merged type starting value 885 for (uint i = 1; i < req(); ++i) {// For all paths in 886 // Reachable control path? 887 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) { 888 const Type* ti = phase->type(in(i)); 889 // We assume that each input of an interface-valued Phi is a true 890 // subtype of that interface. This might not be true of the meet 891 // of all the input types. The lattice is not distributive in 892 // such cases. Ward off asserts in type.cpp by refusing to do 893 // meets between interfaces and proper classes. 894 const TypePtr* tip = ti->make_ptr(); 895 const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL; 896 if (tiip) { 897 bool ti_is_intf = false; 898 ciKlass* k = tiip->klass(); 899 if (k->is_loaded() && k->is_interface()) 900 ti_is_intf = true; 901 if (is_intf != ti_is_intf) 902 { t = _type; break; } 903 } 904 t = t->meet(ti); 905 } 906 } 907 908 // The worst-case type (from ciTypeFlow) should be consistent with "t". 909 // That is, we expect that "t->higher_equal(_type)" holds true. 910 // There are various exceptions: 911 // - Inputs which are phis might in fact be widened unnecessarily. 912 // For example, an input might be a widened int while the phi is a short. 913 // - Inputs might be BotPtrs but this phi is dependent on a null check, 914 // and postCCP has removed the cast which encodes the result of the check. 915 // - The type of this phi is an interface, and the inputs are classes. 916 // - Value calls on inputs might produce fuzzy results. 917 // (Occurrences of this case suggest improvements to Value methods.) 918 // 919 // It is not possible to see Type::BOTTOM values as phi inputs, 920 // because the ciTypeFlow pre-pass produces verifier-quality types. 921 const Type* ft = t->filter(_type); // Worst case type 922 923 #ifdef ASSERT 924 // The following logic has been moved into TypeOopPtr::filter. 925 const Type* jt = t->join(_type); 926 if( jt->empty() ) { // Emptied out??? 927 928 // Check for evil case of 't' being a class and '_type' expecting an 929 // interface. This can happen because the bytecodes do not contain 930 // enough type info to distinguish a Java-level interface variable 931 // from a Java-level object variable. If we meet 2 classes which 932 // both implement interface I, but their meet is at 'j/l/O' which 933 // doesn't implement I, we have no way to tell if the result should 934 // be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows 935 // into a Phi which "knows" it's an Interface type we'll have to 936 // uplift the type. 937 if( !t->empty() && ttip && ttip->is_loaded() && ttip->klass()->is_interface() ) 938 { assert(ft == _type, ""); } // Uplift to interface 939 else if( !t->empty() && ttkp && ttkp->is_loaded() && ttkp->klass()->is_interface() ) 940 { assert(ft == _type, ""); } // Uplift to interface 941 // Otherwise it's something stupid like non-overlapping int ranges 942 // found on dying counted loops. 943 else 944 { assert(ft == Type::TOP, ""); } // Canonical empty value 945 } 946 947 else { 948 949 // If we have an interface-typed Phi and we narrow to a class type, the join 950 // should report back the class. However, if we have a J/L/Object 951 // class-typed Phi and an interface flows in, it's possible that the meet & 952 // join report an interface back out. This isn't possible but happens 953 // because the type system doesn't interact well with interfaces. 954 const TypePtr *jtp = jt->make_ptr(); 955 const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL; 956 const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_klassptr() : NULL; 957 if( jtip && ttip ) { 958 if( jtip->is_loaded() && jtip->klass()->is_interface() && 959 ttip->is_loaded() && !ttip->klass()->is_interface() ) { 960 // Happens in a CTW of rt.jar, 320-341, no extra flags 961 assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) || 962 ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), ""); 963 jt = ft; 964 } 965 } 966 if( jtkp && ttkp ) { 967 if( jtkp->is_loaded() && jtkp->klass()->is_interface() && 968 !jtkp->klass_is_exact() && // Keep exact interface klass (6894807) 969 ttkp->is_loaded() && !ttkp->klass()->is_interface() ) { 970 assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) || 971 ft->isa_narrowoop() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), ""); 972 jt = ft; 973 } 974 } 975 if (jt != ft && jt->base() == ft->base()) { 976 if (jt->isa_int() && 977 jt->is_int()->_lo == ft->is_int()->_lo && 978 jt->is_int()->_hi == ft->is_int()->_hi) 979 jt = ft; 980 if (jt->isa_long() && 981 jt->is_long()->_lo == ft->is_long()->_lo && 982 jt->is_long()->_hi == ft->is_long()->_hi) 983 jt = ft; 984 } 985 if (jt != ft) { 986 tty->print("merge type: "); t->dump(); tty->cr(); 987 tty->print("kill type: "); _type->dump(); tty->cr(); 988 tty->print("join type: "); jt->dump(); tty->cr(); 989 tty->print("filter type: "); ft->dump(); tty->cr(); 990 } 991 assert(jt == ft, ""); 992 } 993 #endif //ASSERT 994 995 // Deal with conversion problems found in data loops. 996 ft = phase->saturate(ft, phase->type_or_null(this), _type); 997 998 return ft; 999 } 1000 1001 1002 //------------------------------is_diamond_phi--------------------------------- 1003 // Does this Phi represent a simple well-shaped diamond merge? Return the 1004 // index of the true path or 0 otherwise. 1005 int PhiNode::is_diamond_phi() const { 1006 // Check for a 2-path merge 1007 Node *region = in(0); 1008 if( !region ) return 0; 1009 if( region->req() != 3 ) return 0; 1010 if( req() != 3 ) return 0; 1011 // Check that both paths come from the same If 1012 Node *ifp1 = region->in(1); 1013 Node *ifp2 = region->in(2); 1014 if( !ifp1 || !ifp2 ) return 0; 1015 Node *iff = ifp1->in(0); 1016 if( !iff || !iff->is_If() ) return 0; 1017 if( iff != ifp2->in(0) ) return 0; 1018 // Check for a proper bool/cmp 1019 const Node *b = iff->in(1); 1020 if( !b->is_Bool() ) return 0; 1021 const Node *cmp = b->in(1); 1022 if( !cmp->is_Cmp() ) return 0; 1023 1024 // Check for branching opposite expected 1025 if( ifp2->Opcode() == Op_IfTrue ) { 1026 assert( ifp1->Opcode() == Op_IfFalse, "" ); 1027 return 2; 1028 } else { 1029 assert( ifp1->Opcode() == Op_IfTrue, "" ); 1030 return 1; 1031 } 1032 } 1033 1034 //----------------------------check_cmove_id----------------------------------- 1035 // Check for CMove'ing a constant after comparing against the constant. 1036 // Happens all the time now, since if we compare equality vs a constant in 1037 // the parser, we "know" the variable is constant on one path and we force 1038 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a 1039 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more 1040 // general in that we don't need constants. Since CMove's are only inserted 1041 // in very special circumstances, we do it here on generic Phi's. 1042 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) { 1043 assert(true_path !=0, "only diamond shape graph expected"); 1044 1045 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1046 // phi->region->if_proj->ifnode->bool->cmp 1047 Node* region = in(0); 1048 Node* iff = region->in(1)->in(0); 1049 BoolNode* b = iff->in(1)->as_Bool(); 1050 Node* cmp = b->in(1); 1051 Node* tval = in(true_path); 1052 Node* fval = in(3-true_path); 1053 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b); 1054 if (id == NULL) 1055 return NULL; 1056 1057 // Either value might be a cast that depends on a branch of 'iff'. 1058 // Since the 'id' value will float free of the diamond, either 1059 // decast or return failure. 1060 Node* ctl = id->in(0); 1061 if (ctl != NULL && ctl->in(0) == iff) { 1062 if (id->is_ConstraintCast()) { 1063 return id->in(1); 1064 } else { 1065 // Don't know how to disentangle this value. 1066 return NULL; 1067 } 1068 } 1069 1070 return id; 1071 } 1072 1073 //------------------------------Identity--------------------------------------- 1074 // Check for Region being Identity. 1075 Node *PhiNode::Identity( PhaseTransform *phase ) { 1076 // Check for no merging going on 1077 // (There used to be special-case code here when this->region->is_Loop. 1078 // It would check for a tributary phi on the backedge that the main phi 1079 // trivially, perhaps with a single cast. The unique_input method 1080 // does all this and more, by reducing such tributaries to 'this'.) 1081 Node* uin = unique_input(phase); 1082 if (uin != NULL) { 1083 return uin; 1084 } 1085 1086 int true_path = is_diamond_phi(); 1087 if (true_path != 0) { 1088 Node* id = is_cmove_id(phase, true_path); 1089 if (id != NULL) return id; 1090 } 1091 1092 return this; // No identity 1093 } 1094 1095 //-----------------------------unique_input------------------------------------ 1096 // Find the unique value, discounting top, self-loops, and casts. 1097 // Return top if there are no inputs, and self if there are multiple. 1098 Node* PhiNode::unique_input(PhaseTransform* phase) { 1099 // 1) One unique direct input, or 1100 // 2) some of the inputs have an intervening ConstraintCast and 1101 // the type of input is the same or sharper (more specific) 1102 // than the phi's type. 1103 // 3) an input is a self loop 1104 // 1105 // 1) input or 2) input or 3) input __ 1106 // / \ / \ \ / \ 1107 // \ / | cast phi cast 1108 // phi \ / / \ / 1109 // phi / -- 1110 1111 Node* r = in(0); // RegionNode 1112 if (r == NULL) return in(1); // Already degraded to a Copy 1113 Node* uncasted_input = NULL; // The unique uncasted input (ConstraintCasts removed) 1114 Node* direct_input = NULL; // The unique direct input 1115 1116 for (uint i = 1, cnt = req(); i < cnt; ++i) { 1117 Node* rc = r->in(i); 1118 if (rc == NULL || phase->type(rc) == Type::TOP) 1119 continue; // ignore unreachable control path 1120 Node* n = in(i); 1121 if (n == NULL) 1122 continue; 1123 Node* un = n->uncast(); 1124 if (un == NULL || un == this || phase->type(un) == Type::TOP) { 1125 continue; // ignore if top, or in(i) and "this" are in a data cycle 1126 } 1127 // Check for a unique uncasted input 1128 if (uncasted_input == NULL) { 1129 uncasted_input = un; 1130 } else if (uncasted_input != un) { 1131 uncasted_input = NodeSentinel; // no unique uncasted input 1132 } 1133 // Check for a unique direct input 1134 if (direct_input == NULL) { 1135 direct_input = n; 1136 } else if (direct_input != n) { 1137 direct_input = NodeSentinel; // no unique direct input 1138 } 1139 } 1140 if (direct_input == NULL) { 1141 return phase->C->top(); // no inputs 1142 } 1143 assert(uncasted_input != NULL,""); 1144 1145 if (direct_input != NodeSentinel) { 1146 return direct_input; // one unique direct input 1147 } 1148 if (uncasted_input != NodeSentinel && 1149 phase->type(uncasted_input)->higher_equal(type())) { 1150 return uncasted_input; // one unique uncasted input 1151 } 1152 1153 // Nothing. 1154 return NULL; 1155 } 1156 1157 //------------------------------is_x2logic------------------------------------- 1158 // Check for simple convert-to-boolean pattern 1159 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1) 1160 // Convert Phi to an ConvIB. 1161 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) { 1162 assert(true_path !=0, "only diamond shape graph expected"); 1163 // Convert the true/false index into an expected 0/1 return. 1164 // Map 2->0 and 1->1. 1165 int flipped = 2-true_path; 1166 1167 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1168 // phi->region->if_proj->ifnode->bool->cmp 1169 Node *region = phi->in(0); 1170 Node *iff = region->in(1)->in(0); 1171 BoolNode *b = (BoolNode*)iff->in(1); 1172 const CmpNode *cmp = (CmpNode*)b->in(1); 1173 1174 Node *zero = phi->in(1); 1175 Node *one = phi->in(2); 1176 const Type *tzero = phase->type( zero ); 1177 const Type *tone = phase->type( one ); 1178 1179 // Check for compare vs 0 1180 const Type *tcmp = phase->type(cmp->in(2)); 1181 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) { 1182 // Allow cmp-vs-1 if the other input is bounded by 0-1 1183 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) ) 1184 return NULL; 1185 flipped = 1-flipped; // Test is vs 1 instead of 0! 1186 } 1187 1188 // Check for setting zero/one opposite expected 1189 if( tzero == TypeInt::ZERO ) { 1190 if( tone == TypeInt::ONE ) { 1191 } else return NULL; 1192 } else if( tzero == TypeInt::ONE ) { 1193 if( tone == TypeInt::ZERO ) { 1194 flipped = 1-flipped; 1195 } else return NULL; 1196 } else return NULL; 1197 1198 // Check for boolean test backwards 1199 if( b->_test._test == BoolTest::ne ) { 1200 } else if( b->_test._test == BoolTest::eq ) { 1201 flipped = 1-flipped; 1202 } else return NULL; 1203 1204 // Build int->bool conversion 1205 Node *n = new (phase->C, 2) Conv2BNode( cmp->in(1) ); 1206 if( flipped ) 1207 n = new (phase->C, 3) XorINode( phase->transform(n), phase->intcon(1) ); 1208 1209 return n; 1210 } 1211 1212 //------------------------------is_cond_add------------------------------------ 1213 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;" 1214 // To be profitable the control flow has to disappear; there can be no other 1215 // values merging here. We replace the test-and-branch with: 1216 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by 1217 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'. 1218 // Then convert Y to 0-or-Y and finally add. 1219 // This is a key transform for SpecJava _201_compress. 1220 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) { 1221 assert(true_path !=0, "only diamond shape graph expected"); 1222 1223 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1224 // phi->region->if_proj->ifnode->bool->cmp 1225 RegionNode *region = (RegionNode*)phi->in(0); 1226 Node *iff = region->in(1)->in(0); 1227 BoolNode* b = iff->in(1)->as_Bool(); 1228 const CmpNode *cmp = (CmpNode*)b->in(1); 1229 1230 // Make sure only merging this one phi here 1231 if (region->has_unique_phi() != phi) return NULL; 1232 1233 // Make sure each arm of the diamond has exactly one output, which we assume 1234 // is the region. Otherwise, the control flow won't disappear. 1235 if (region->in(1)->outcnt() != 1) return NULL; 1236 if (region->in(2)->outcnt() != 1) return NULL; 1237 1238 // Check for "(P < Q)" of type signed int 1239 if (b->_test._test != BoolTest::lt) return NULL; 1240 if (cmp->Opcode() != Op_CmpI) return NULL; 1241 1242 Node *p = cmp->in(1); 1243 Node *q = cmp->in(2); 1244 Node *n1 = phi->in( true_path); 1245 Node *n2 = phi->in(3-true_path); 1246 1247 int op = n1->Opcode(); 1248 if( op != Op_AddI // Need zero as additive identity 1249 /*&&op != Op_SubI && 1250 op != Op_AddP && 1251 op != Op_XorI && 1252 op != Op_OrI*/ ) 1253 return NULL; 1254 1255 Node *x = n2; 1256 Node *y = n1->in(1); 1257 if( n2 == n1->in(1) ) { 1258 y = n1->in(2); 1259 } else if( n2 == n1->in(1) ) { 1260 } else return NULL; 1261 1262 // Not so profitable if compare and add are constants 1263 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() ) 1264 return NULL; 1265 1266 Node *cmplt = phase->transform( new (phase->C, 3) CmpLTMaskNode(p,q) ); 1267 Node *j_and = phase->transform( new (phase->C, 3) AndINode(cmplt,y) ); 1268 return new (phase->C, 3) AddINode(j_and,x); 1269 } 1270 1271 //------------------------------is_absolute------------------------------------ 1272 // Check for absolute value. 1273 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) { 1274 assert(true_path !=0, "only diamond shape graph expected"); 1275 1276 int cmp_zero_idx = 0; // Index of compare input where to look for zero 1277 int phi_x_idx = 0; // Index of phi input where to find naked x 1278 1279 // ABS ends with the merge of 2 control flow paths. 1280 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely. 1281 int false_path = 3 - true_path; 1282 1283 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1284 // phi->region->if_proj->ifnode->bool->cmp 1285 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool(); 1286 1287 // Check bool sense 1288 switch( bol->_test._test ) { 1289 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break; 1290 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break; 1291 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break; 1292 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break; 1293 default: return NULL; break; 1294 } 1295 1296 // Test is next 1297 Node *cmp = bol->in(1); 1298 const Type *tzero = NULL; 1299 switch( cmp->Opcode() ) { 1300 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS 1301 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS 1302 default: return NULL; 1303 } 1304 1305 // Find zero input of compare; the other input is being abs'd 1306 Node *x = NULL; 1307 bool flip = false; 1308 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) { 1309 x = cmp->in(3 - cmp_zero_idx); 1310 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) { 1311 // The test is inverted, we should invert the result... 1312 x = cmp->in(cmp_zero_idx); 1313 flip = true; 1314 } else { 1315 return NULL; 1316 } 1317 1318 // Next get the 2 pieces being selected, one is the original value 1319 // and the other is the negated value. 1320 if( phi_root->in(phi_x_idx) != x ) return NULL; 1321 1322 // Check other phi input for subtract node 1323 Node *sub = phi_root->in(3 - phi_x_idx); 1324 1325 // Allow only Sub(0,X) and fail out for all others; Neg is not OK 1326 if( tzero == TypeF::ZERO ) { 1327 if( sub->Opcode() != Op_SubF || 1328 sub->in(2) != x || 1329 phase->type(sub->in(1)) != tzero ) return NULL; 1330 x = new (phase->C, 2) AbsFNode(x); 1331 if (flip) { 1332 x = new (phase->C, 3) SubFNode(sub->in(1), phase->transform(x)); 1333 } 1334 } else { 1335 if( sub->Opcode() != Op_SubD || 1336 sub->in(2) != x || 1337 phase->type(sub->in(1)) != tzero ) return NULL; 1338 x = new (phase->C, 2) AbsDNode(x); 1339 if (flip) { 1340 x = new (phase->C, 3) SubDNode(sub->in(1), phase->transform(x)); 1341 } 1342 } 1343 1344 return x; 1345 } 1346 1347 //------------------------------split_once------------------------------------- 1348 // Helper for split_flow_path 1349 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) { 1350 igvn->hash_delete(n); // Remove from hash before hacking edges 1351 1352 Node* predicate_proj = NULL; 1353 uint j = 1; 1354 for (uint i = phi->req()-1; i > 0; i--) { 1355 if (phi->in(i) == val) { // Found a path with val? 1356 if (n->is_Region()) { 1357 Node* proj = PhaseIdealLoop::find_predicate(n->in(i)); 1358 if (proj != NULL) { 1359 assert(predicate_proj == NULL, "only one predicate entry expected"); 1360 predicate_proj = proj; 1361 } 1362 } 1363 // Add to NEW Region/Phi, no DU info 1364 newn->set_req( j++, n->in(i) ); 1365 // Remove from OLD Region/Phi 1366 n->del_req(i); 1367 } 1368 } 1369 1370 // Register the new node but do not transform it. Cannot transform until the 1371 // entire Region/Phi conglomerate has been hacked as a single huge transform. 1372 igvn->register_new_node_with_optimizer( newn ); 1373 1374 // Clone loop predicates 1375 if (predicate_proj != NULL) { 1376 newn = igvn->clone_loop_predicates(predicate_proj, newn, !n->is_CountedLoop()); 1377 } 1378 1379 // Now I can point to the new node. 1380 n->add_req(newn); 1381 igvn->_worklist.push(n); 1382 } 1383 1384 //------------------------------split_flow_path-------------------------------- 1385 // Check for merging identical values and split flow paths 1386 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) { 1387 BasicType bt = phi->type()->basic_type(); 1388 if( bt == T_ILLEGAL || type2size[bt] <= 0 ) 1389 return NULL; // Bail out on funny non-value stuff 1390 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a 1391 return NULL; // third unequal input to be worth doing 1392 1393 // Scan for a constant 1394 uint i; 1395 for( i = 1; i < phi->req()-1; i++ ) { 1396 Node *n = phi->in(i); 1397 if( !n ) return NULL; 1398 if( phase->type(n) == Type::TOP ) return NULL; 1399 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN ) 1400 break; 1401 } 1402 if( i >= phi->req() ) // Only split for constants 1403 return NULL; 1404 1405 Node *val = phi->in(i); // Constant to split for 1406 uint hit = 0; // Number of times it occurs 1407 1408 for( ; i < phi->req(); i++ ){ // Count occurrences of constant 1409 Node *n = phi->in(i); 1410 if( !n ) return NULL; 1411 if( phase->type(n) == Type::TOP ) return NULL; 1412 if( phi->in(i) == val ) 1413 hit++; 1414 } 1415 1416 if( hit <= 1 || // Make sure we find 2 or more 1417 hit == phi->req()-1 ) // and not ALL the same value 1418 return NULL; 1419 1420 // Now start splitting out the flow paths that merge the same value. 1421 // Split first the RegionNode. 1422 PhaseIterGVN *igvn = phase->is_IterGVN(); 1423 Node *r = phi->region(); 1424 RegionNode *newr = new (phase->C, hit+1) RegionNode(hit+1); 1425 split_once(igvn, phi, val, r, newr); 1426 1427 // Now split all other Phis than this one 1428 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) { 1429 Node* phi2 = r->fast_out(k); 1430 if( phi2->is_Phi() && phi2->as_Phi() != phi ) { 1431 PhiNode *newphi = PhiNode::make_blank(newr, phi2); 1432 split_once(igvn, phi, val, phi2, newphi); 1433 } 1434 } 1435 1436 // Clean up this guy 1437 igvn->hash_delete(phi); 1438 for( i = phi->req()-1; i > 0; i-- ) { 1439 if( phi->in(i) == val ) { 1440 phi->del_req(i); 1441 } 1442 } 1443 phi->add_req(val); 1444 1445 return phi; 1446 } 1447 1448 //============================================================================= 1449 //------------------------------simple_data_loop_check------------------------- 1450 // Try to determining if the phi node in a simple safe/unsafe data loop. 1451 // Returns: 1452 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop }; 1453 // Safe - safe case when the phi and it's inputs reference only safe data 1454 // nodes; 1455 // Unsafe - the phi and it's inputs reference unsafe data nodes but there 1456 // is no reference back to the phi - need a graph walk 1457 // to determine if it is in a loop; 1458 // UnsafeLoop - unsafe case when the phi references itself directly or through 1459 // unsafe data node. 1460 // Note: a safe data node is a node which could/never reference itself during 1461 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP. 1462 // I mark Phi nodes as safe node not only because they can reference itself 1463 // but also to prevent mistaking the fallthrough case inside an outer loop 1464 // as dead loop when the phi references itselfs through an other phi. 1465 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const { 1466 // It is unsafe loop if the phi node references itself directly. 1467 if (in == (Node*)this) 1468 return UnsafeLoop; // Unsafe loop 1469 // Unsafe loop if the phi node references itself through an unsafe data node. 1470 // Exclude cases with null inputs or data nodes which could reference 1471 // itself (safe for dead loops). 1472 if (in != NULL && !in->is_dead_loop_safe()) { 1473 // Check inputs of phi's inputs also. 1474 // It is much less expensive then full graph walk. 1475 uint cnt = in->req(); 1476 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1; 1477 for (; i < cnt; ++i) { 1478 Node* m = in->in(i); 1479 if (m == (Node*)this) 1480 return UnsafeLoop; // Unsafe loop 1481 if (m != NULL && !m->is_dead_loop_safe()) { 1482 // Check the most common case (about 30% of all cases): 1483 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con). 1484 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL; 1485 if (m1 == (Node*)this) 1486 return UnsafeLoop; // Unsafe loop 1487 if (m1 != NULL && m1 == m->in(2) && 1488 m1->is_dead_loop_safe() && m->in(3)->is_Con()) { 1489 continue; // Safe case 1490 } 1491 // The phi references an unsafe node - need full analysis. 1492 return Unsafe; 1493 } 1494 } 1495 } 1496 return Safe; // Safe case - we can optimize the phi node. 1497 } 1498 1499 //------------------------------is_unsafe_data_reference----------------------- 1500 // If phi can be reached through the data input - it is data loop. 1501 bool PhiNode::is_unsafe_data_reference(Node *in) const { 1502 assert(req() > 1, ""); 1503 // First, check simple cases when phi references itself directly or 1504 // through an other node. 1505 LoopSafety safety = simple_data_loop_check(in); 1506 if (safety == UnsafeLoop) 1507 return true; // phi references itself - unsafe loop 1508 else if (safety == Safe) 1509 return false; // Safe case - phi could be replaced with the unique input. 1510 1511 // Unsafe case when we should go through data graph to determine 1512 // if the phi references itself. 1513 1514 ResourceMark rm; 1515 1516 Arena *a = Thread::current()->resource_area(); 1517 Node_List nstack(a); 1518 VectorSet visited(a); 1519 1520 nstack.push(in); // Start with unique input. 1521 visited.set(in->_idx); 1522 while (nstack.size() != 0) { 1523 Node* n = nstack.pop(); 1524 uint cnt = n->req(); 1525 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1; 1526 for (; i < cnt; i++) { 1527 Node* m = n->in(i); 1528 if (m == (Node*)this) { 1529 return true; // Data loop 1530 } 1531 if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases. 1532 if (!visited.test_set(m->_idx)) 1533 nstack.push(m); 1534 } 1535 } 1536 } 1537 return false; // The phi is not reachable from its inputs 1538 } 1539 1540 1541 //------------------------------Ideal------------------------------------------ 1542 // Return a node which is more "ideal" than the current node. Must preserve 1543 // the CFG, but we can still strip out dead paths. 1544 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1545 // The next should never happen after 6297035 fix. 1546 if( is_copy() ) // Already degraded to a Copy ? 1547 return NULL; // No change 1548 1549 Node *r = in(0); // RegionNode 1550 assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge"); 1551 1552 // Note: During parsing, phis are often transformed before their regions. 1553 // This means we have to use type_or_null to defend against untyped regions. 1554 if( phase->type_or_null(r) == Type::TOP ) // Dead code? 1555 return NULL; // No change 1556 1557 Node *top = phase->C->top(); 1558 bool new_phi = (outcnt() == 0); // transforming new Phi 1559 // No change for igvn if new phi is not hooked 1560 if (new_phi && can_reshape) 1561 return NULL; 1562 1563 // The are 2 situations when only one valid phi's input is left 1564 // (in addition to Region input). 1565 // One: region is not loop - replace phi with this input. 1566 // Two: region is loop - replace phi with top since this data path is dead 1567 // and we need to break the dead data loop. 1568 Node* progress = NULL; // Record if any progress made 1569 for( uint j = 1; j < req(); ++j ){ // For all paths in 1570 // Check unreachable control paths 1571 Node* rc = r->in(j); 1572 Node* n = in(j); // Get the input 1573 if (rc == NULL || phase->type(rc) == Type::TOP) { 1574 if (n != top) { // Not already top? 1575 set_req(j, top); // Nuke it down 1576 progress = this; // Record progress 1577 } 1578 } 1579 } 1580 1581 if (can_reshape && outcnt() == 0) { 1582 // set_req() above may kill outputs if Phi is referenced 1583 // only by itself on the dead (top) control path. 1584 return top; 1585 } 1586 1587 Node* uin = unique_input(phase); 1588 if (uin == top) { // Simplest case: no alive inputs. 1589 if (can_reshape) // IGVN transformation 1590 return top; 1591 else 1592 return NULL; // Identity will return TOP 1593 } else if (uin != NULL) { 1594 // Only one not-NULL unique input path is left. 1595 // Determine if this input is backedge of a loop. 1596 // (Skip new phis which have no uses and dead regions). 1597 if( outcnt() > 0 && r->in(0) != NULL ) { 1598 // First, take the short cut when we know it is a loop and 1599 // the EntryControl data path is dead. 1600 assert(!r->is_Loop() || r->req() == 3, "Loop node should have 3 inputs"); 1601 // Then, check if there is a data loop when phi references itself directly 1602 // or through other data nodes. 1603 if( r->is_Loop() && !phase->eqv_uncast(uin, in(LoopNode::EntryControl)) || 1604 !r->is_Loop() && is_unsafe_data_reference(uin) ) { 1605 // Break this data loop to avoid creation of a dead loop. 1606 if (can_reshape) { 1607 return top; 1608 } else { 1609 // We can't return top if we are in Parse phase - cut inputs only 1610 // let Identity to handle the case. 1611 replace_edge(uin, top); 1612 return NULL; 1613 } 1614 } 1615 } 1616 1617 // One unique input. 1618 debug_only(Node* ident = Identity(phase)); 1619 // The unique input must eventually be detected by the Identity call. 1620 #ifdef ASSERT 1621 if (ident != uin && !ident->is_top()) { 1622 // print this output before failing assert 1623 r->dump(3); 1624 this->dump(3); 1625 ident->dump(); 1626 uin->dump(); 1627 } 1628 #endif 1629 assert(ident == uin || ident->is_top(), "Identity must clean this up"); 1630 return NULL; 1631 } 1632 1633 1634 Node* opt = NULL; 1635 int true_path = is_diamond_phi(); 1636 if( true_path != 0 ) { 1637 // Check for CMove'ing identity. If it would be unsafe, 1638 // handle it here. In the safe case, let Identity handle it. 1639 Node* unsafe_id = is_cmove_id(phase, true_path); 1640 if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) ) 1641 opt = unsafe_id; 1642 1643 // Check for simple convert-to-boolean pattern 1644 if( opt == NULL ) 1645 opt = is_x2logic(phase, this, true_path); 1646 1647 // Check for absolute value 1648 if( opt == NULL ) 1649 opt = is_absolute(phase, this, true_path); 1650 1651 // Check for conditional add 1652 if( opt == NULL && can_reshape ) 1653 opt = is_cond_add(phase, this, true_path); 1654 1655 // These 4 optimizations could subsume the phi: 1656 // have to check for a dead data loop creation. 1657 if( opt != NULL ) { 1658 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) { 1659 // Found dead loop. 1660 if( can_reshape ) 1661 return top; 1662 // We can't return top if we are in Parse phase - cut inputs only 1663 // to stop further optimizations for this phi. Identity will return TOP. 1664 assert(req() == 3, "only diamond merge phi here"); 1665 set_req(1, top); 1666 set_req(2, top); 1667 return NULL; 1668 } else { 1669 return opt; 1670 } 1671 } 1672 } 1673 1674 // Check for merging identical values and split flow paths 1675 if (can_reshape) { 1676 opt = split_flow_path(phase, this); 1677 // This optimization only modifies phi - don't need to check for dead loop. 1678 assert(opt == NULL || phase->eqv(opt, this), "do not elide phi"); 1679 if (opt != NULL) return opt; 1680 } 1681 1682 if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) { 1683 // Try to undo Phi of AddP: 1684 // (Phi (AddP base base y) (AddP base2 base2 y)) 1685 // becomes: 1686 // newbase := (Phi base base2) 1687 // (AddP newbase newbase y) 1688 // 1689 // This occurs as a result of unsuccessful split_thru_phi and 1690 // interferes with taking advantage of addressing modes. See the 1691 // clone_shift_expressions code in matcher.cpp 1692 Node* addp = in(1); 1693 const Type* type = addp->in(AddPNode::Base)->bottom_type(); 1694 Node* y = addp->in(AddPNode::Offset); 1695 if (y != NULL && addp->in(AddPNode::Base) == addp->in(AddPNode::Address)) { 1696 // make sure that all the inputs are similar to the first one, 1697 // i.e. AddP with base == address and same offset as first AddP 1698 bool doit = true; 1699 for (uint i = 2; i < req(); i++) { 1700 if (in(i) == NULL || 1701 in(i)->Opcode() != Op_AddP || 1702 in(i)->in(AddPNode::Base) != in(i)->in(AddPNode::Address) || 1703 in(i)->in(AddPNode::Offset) != y) { 1704 doit = false; 1705 break; 1706 } 1707 // Accumulate type for resulting Phi 1708 type = type->meet(in(i)->in(AddPNode::Base)->bottom_type()); 1709 } 1710 Node* base = NULL; 1711 if (doit) { 1712 // Check for neighboring AddP nodes in a tree. 1713 // If they have a base, use that it. 1714 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) { 1715 Node* u = this->fast_out(k); 1716 if (u->is_AddP()) { 1717 Node* base2 = u->in(AddPNode::Base); 1718 if (base2 != NULL && !base2->is_top()) { 1719 if (base == NULL) 1720 base = base2; 1721 else if (base != base2) 1722 { doit = false; break; } 1723 } 1724 } 1725 } 1726 } 1727 if (doit) { 1728 if (base == NULL) { 1729 base = new (phase->C, in(0)->req()) PhiNode(in(0), type, NULL); 1730 for (uint i = 1; i < req(); i++) { 1731 base->init_req(i, in(i)->in(AddPNode::Base)); 1732 } 1733 phase->is_IterGVN()->register_new_node_with_optimizer(base); 1734 } 1735 return new (phase->C, 4) AddPNode(base, base, y); 1736 } 1737 } 1738 } 1739 1740 // Split phis through memory merges, so that the memory merges will go away. 1741 // Piggy-back this transformation on the search for a unique input.... 1742 // It will be as if the merged memory is the unique value of the phi. 1743 // (Do not attempt this optimization unless parsing is complete. 1744 // It would make the parser's memory-merge logic sick.) 1745 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.) 1746 if (progress == NULL && can_reshape && type() == Type::MEMORY) { 1747 // see if this phi should be sliced 1748 uint merge_width = 0; 1749 bool saw_self = false; 1750 for( uint i=1; i<req(); ++i ) {// For all paths in 1751 Node *ii = in(i); 1752 if (ii->is_MergeMem()) { 1753 MergeMemNode* n = ii->as_MergeMem(); 1754 merge_width = MAX2(merge_width, n->req()); 1755 saw_self = saw_self || phase->eqv(n->base_memory(), this); 1756 } 1757 } 1758 1759 // This restriction is temporarily necessary to ensure termination: 1760 if (!saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0; 1761 1762 if (merge_width > Compile::AliasIdxRaw) { 1763 // found at least one non-empty MergeMem 1764 const TypePtr* at = adr_type(); 1765 if (at != TypePtr::BOTTOM) { 1766 // Patch the existing phi to select an input from the merge: 1767 // Phi:AT1(...MergeMem(m0, m1, m2)...) into 1768 // Phi:AT1(...m1...) 1769 int alias_idx = phase->C->get_alias_index(at); 1770 for (uint i=1; i<req(); ++i) { 1771 Node *ii = in(i); 1772 if (ii->is_MergeMem()) { 1773 MergeMemNode* n = ii->as_MergeMem(); 1774 // compress paths and change unreachable cycles to TOP 1775 // If not, we can update the input infinitely along a MergeMem cycle 1776 // Equivalent code is in MemNode::Ideal_common 1777 Node *m = phase->transform(n); 1778 if (outcnt() == 0) { // Above transform() may kill us! 1779 return top; 1780 } 1781 // If transformed to a MergeMem, get the desired slice 1782 // Otherwise the returned node represents memory for every slice 1783 Node *new_mem = (m->is_MergeMem()) ? 1784 m->as_MergeMem()->memory_at(alias_idx) : m; 1785 // Update input if it is progress over what we have now 1786 if (new_mem != ii) { 1787 set_req(i, new_mem); 1788 progress = this; 1789 } 1790 } 1791 } 1792 } else { 1793 // We know that at least one MergeMem->base_memory() == this 1794 // (saw_self == true). If all other inputs also references this phi 1795 // (directly or through data nodes) - it is dead loop. 1796 bool saw_safe_input = false; 1797 for (uint j = 1; j < req(); ++j) { 1798 Node *n = in(j); 1799 if (n->is_MergeMem() && n->as_MergeMem()->base_memory() == this) 1800 continue; // skip known cases 1801 if (!is_unsafe_data_reference(n)) { 1802 saw_safe_input = true; // found safe input 1803 break; 1804 } 1805 } 1806 if (!saw_safe_input) 1807 return top; // all inputs reference back to this phi - dead loop 1808 1809 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into 1810 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...)) 1811 PhaseIterGVN *igvn = phase->is_IterGVN(); 1812 Node* hook = new (phase->C, 1) Node(1); 1813 PhiNode* new_base = (PhiNode*) clone(); 1814 // Must eagerly register phis, since they participate in loops. 1815 if (igvn) { 1816 igvn->register_new_node_with_optimizer(new_base); 1817 hook->add_req(new_base); 1818 } 1819 MergeMemNode* result = MergeMemNode::make(phase->C, new_base); 1820 for (uint i = 1; i < req(); ++i) { 1821 Node *ii = in(i); 1822 if (ii->is_MergeMem()) { 1823 MergeMemNode* n = ii->as_MergeMem(); 1824 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) { 1825 // If we have not seen this slice yet, make a phi for it. 1826 bool made_new_phi = false; 1827 if (mms.is_empty()) { 1828 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C)); 1829 made_new_phi = true; 1830 if (igvn) { 1831 igvn->register_new_node_with_optimizer(new_phi); 1832 hook->add_req(new_phi); 1833 } 1834 mms.set_memory(new_phi); 1835 } 1836 Node* phi = mms.memory(); 1837 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice"); 1838 phi->set_req(i, mms.memory2()); 1839 } 1840 } 1841 } 1842 // Distribute all self-loops. 1843 { // (Extra braces to hide mms.) 1844 for (MergeMemStream mms(result); mms.next_non_empty(); ) { 1845 Node* phi = mms.memory(); 1846 for (uint i = 1; i < req(); ++i) { 1847 if (phi->in(i) == this) phi->set_req(i, phi); 1848 } 1849 } 1850 } 1851 // now transform the new nodes, and return the mergemem 1852 for (MergeMemStream mms(result); mms.next_non_empty(); ) { 1853 Node* phi = mms.memory(); 1854 mms.set_memory(phase->transform(phi)); 1855 } 1856 if (igvn) { // Unhook. 1857 igvn->hash_delete(hook); 1858 for (uint i = 1; i < hook->req(); i++) { 1859 hook->set_req(i, NULL); 1860 } 1861 } 1862 // Replace self with the result. 1863 return result; 1864 } 1865 } 1866 // 1867 // Other optimizations on the memory chain 1868 // 1869 const TypePtr* at = adr_type(); 1870 for( uint i=1; i<req(); ++i ) {// For all paths in 1871 Node *ii = in(i); 1872 Node *new_in = MemNode::optimize_memory_chain(ii, at, phase); 1873 if (ii != new_in ) { 1874 set_req(i, new_in); 1875 progress = this; 1876 } 1877 } 1878 } 1879 1880 #ifdef _LP64 1881 // Push DecodeN down through phi. 1882 // The rest of phi graph will transform by split EncodeP node though phis up. 1883 if (UseCompressedOops && can_reshape && progress == NULL) { 1884 bool may_push = true; 1885 bool has_decodeN = false; 1886 for (uint i=1; i<req(); ++i) {// For all paths in 1887 Node *ii = in(i); 1888 if (ii->is_DecodeN() && ii->bottom_type() == bottom_type()) { 1889 // Do optimization if a non dead path exist. 1890 if (ii->in(1)->bottom_type() != Type::TOP) { 1891 has_decodeN = true; 1892 } 1893 } else if (!ii->is_Phi()) { 1894 may_push = false; 1895 } 1896 } 1897 1898 if (has_decodeN && may_push) { 1899 PhaseIterGVN *igvn = phase->is_IterGVN(); 1900 // Make narrow type for new phi. 1901 const Type* narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr()); 1902 PhiNode* new_phi = new (phase->C, r->req()) PhiNode(r, narrow_t); 1903 uint orig_cnt = req(); 1904 for (uint i=1; i<req(); ++i) {// For all paths in 1905 Node *ii = in(i); 1906 Node* new_ii = NULL; 1907 if (ii->is_DecodeN()) { 1908 assert(ii->bottom_type() == bottom_type(), "sanity"); 1909 new_ii = ii->in(1); 1910 } else { 1911 assert(ii->is_Phi(), "sanity"); 1912 if (ii->as_Phi() == this) { 1913 new_ii = new_phi; 1914 } else { 1915 new_ii = new (phase->C, 2) EncodePNode(ii, narrow_t); 1916 igvn->register_new_node_with_optimizer(new_ii); 1917 } 1918 } 1919 new_phi->set_req(i, new_ii); 1920 } 1921 igvn->register_new_node_with_optimizer(new_phi, this); 1922 progress = new (phase->C, 2) DecodeNNode(new_phi, bottom_type()); 1923 } 1924 } 1925 #endif 1926 1927 return progress; // Return any progress 1928 } 1929 1930 //------------------------------is_tripcount----------------------------------- 1931 bool PhiNode::is_tripcount() const { 1932 return (in(0) != NULL && in(0)->is_CountedLoop() && 1933 in(0)->as_CountedLoop()->phi() == this); 1934 } 1935 1936 //------------------------------out_RegMask------------------------------------ 1937 const RegMask &PhiNode::in_RegMask(uint i) const { 1938 return i ? out_RegMask() : RegMask::Empty; 1939 } 1940 1941 const RegMask &PhiNode::out_RegMask() const { 1942 uint ideal_reg = Matcher::base2reg[_type->base()]; 1943 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" ); 1944 if( ideal_reg == 0 ) return RegMask::Empty; 1945 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]); 1946 } 1947 1948 #ifndef PRODUCT 1949 void PhiNode::dump_spec(outputStream *st) const { 1950 TypeNode::dump_spec(st); 1951 if (is_tripcount()) { 1952 st->print(" #tripcount"); 1953 } 1954 } 1955 #endif 1956 1957 1958 //============================================================================= 1959 const Type *GotoNode::Value( PhaseTransform *phase ) const { 1960 // If the input is reachable, then we are executed. 1961 // If the input is not reachable, then we are not executed. 1962 return phase->type(in(0)); 1963 } 1964 1965 Node *GotoNode::Identity( PhaseTransform *phase ) { 1966 return in(0); // Simple copy of incoming control 1967 } 1968 1969 const RegMask &GotoNode::out_RegMask() const { 1970 return RegMask::Empty; 1971 } 1972 1973 //============================================================================= 1974 const RegMask &JumpNode::out_RegMask() const { 1975 return RegMask::Empty; 1976 } 1977 1978 //============================================================================= 1979 const RegMask &JProjNode::out_RegMask() const { 1980 return RegMask::Empty; 1981 } 1982 1983 //============================================================================= 1984 const RegMask &CProjNode::out_RegMask() const { 1985 return RegMask::Empty; 1986 } 1987 1988 1989 1990 //============================================================================= 1991 1992 uint PCTableNode::hash() const { return Node::hash() + _size; } 1993 uint PCTableNode::cmp( const Node &n ) const 1994 { return _size == ((PCTableNode&)n)._size; } 1995 1996 const Type *PCTableNode::bottom_type() const { 1997 const Type** f = TypeTuple::fields(_size); 1998 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL; 1999 return TypeTuple::make(_size, f); 2000 } 2001 2002 //------------------------------Value------------------------------------------ 2003 // Compute the type of the PCTableNode. If reachable it is a tuple of 2004 // Control, otherwise the table targets are not reachable 2005 const Type *PCTableNode::Value( PhaseTransform *phase ) const { 2006 if( phase->type(in(0)) == Type::CONTROL ) 2007 return bottom_type(); 2008 return Type::TOP; // All paths dead? Then so are we 2009 } 2010 2011 //------------------------------Ideal------------------------------------------ 2012 // Return a node which is more "ideal" than the current node. Strip out 2013 // control copies 2014 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2015 return remove_dead_region(phase, can_reshape) ? this : NULL; 2016 } 2017 2018 //============================================================================= 2019 uint JumpProjNode::hash() const { 2020 return Node::hash() + _dest_bci; 2021 } 2022 2023 uint JumpProjNode::cmp( const Node &n ) const { 2024 return ProjNode::cmp(n) && 2025 _dest_bci == ((JumpProjNode&)n)._dest_bci; 2026 } 2027 2028 #ifndef PRODUCT 2029 void JumpProjNode::dump_spec(outputStream *st) const { 2030 ProjNode::dump_spec(st); 2031 st->print("@bci %d ",_dest_bci); 2032 } 2033 #endif 2034 2035 //============================================================================= 2036 //------------------------------Value------------------------------------------ 2037 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot 2038 // have the default "fall_through_index" path. 2039 const Type *CatchNode::Value( PhaseTransform *phase ) const { 2040 // Unreachable? Then so are all paths from here. 2041 if( phase->type(in(0)) == Type::TOP ) return Type::TOP; 2042 // First assume all paths are reachable 2043 const Type** f = TypeTuple::fields(_size); 2044 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL; 2045 // Identify cases that will always throw an exception 2046 // () rethrow call 2047 // () virtual or interface call with NULL receiver 2048 // () call is a check cast with incompatible arguments 2049 if( in(1)->is_Proj() ) { 2050 Node *i10 = in(1)->in(0); 2051 if( i10->is_Call() ) { 2052 CallNode *call = i10->as_Call(); 2053 // Rethrows always throw exceptions, never return 2054 if (call->entry_point() == OptoRuntime::rethrow_stub()) { 2055 f[CatchProjNode::fall_through_index] = Type::TOP; 2056 } else if( call->req() > TypeFunc::Parms ) { 2057 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) ); 2058 // Check for null receiver to virtual or interface calls 2059 if( call->is_CallDynamicJava() && 2060 arg0->higher_equal(TypePtr::NULL_PTR) ) { 2061 f[CatchProjNode::fall_through_index] = Type::TOP; 2062 } 2063 } // End of if not a runtime stub 2064 } // End of if have call above me 2065 } // End of slot 1 is not a projection 2066 return TypeTuple::make(_size, f); 2067 } 2068 2069 //============================================================================= 2070 uint CatchProjNode::hash() const { 2071 return Node::hash() + _handler_bci; 2072 } 2073 2074 2075 uint CatchProjNode::cmp( const Node &n ) const { 2076 return ProjNode::cmp(n) && 2077 _handler_bci == ((CatchProjNode&)n)._handler_bci; 2078 } 2079 2080 2081 //------------------------------Identity--------------------------------------- 2082 // If only 1 target is possible, choose it if it is the main control 2083 Node *CatchProjNode::Identity( PhaseTransform *phase ) { 2084 // If my value is control and no other value is, then treat as ID 2085 const TypeTuple *t = phase->type(in(0))->is_tuple(); 2086 if (t->field_at(_con) != Type::CONTROL) return this; 2087 // If we remove the last CatchProj and elide the Catch/CatchProj, then we 2088 // also remove any exception table entry. Thus we must know the call 2089 // feeding the Catch will not really throw an exception. This is ok for 2090 // the main fall-thru control (happens when we know a call can never throw 2091 // an exception) or for "rethrow", because a further optimization will 2092 // yank the rethrow (happens when we inline a function that can throw an 2093 // exception and the caller has no handler). Not legal, e.g., for passing 2094 // a NULL receiver to a v-call, or passing bad types to a slow-check-cast. 2095 // These cases MUST throw an exception via the runtime system, so the VM 2096 // will be looking for a table entry. 2097 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode 2098 CallNode *call; 2099 if (_con != TypeFunc::Control && // Bail out if not the main control. 2100 !(proj->is_Proj() && // AND NOT a rethrow 2101 proj->in(0)->is_Call() && 2102 (call = proj->in(0)->as_Call()) && 2103 call->entry_point() == OptoRuntime::rethrow_stub())) 2104 return this; 2105 2106 // Search for any other path being control 2107 for (uint i = 0; i < t->cnt(); i++) { 2108 if (i != _con && t->field_at(i) == Type::CONTROL) 2109 return this; 2110 } 2111 // Only my path is possible; I am identity on control to the jump 2112 return in(0)->in(0); 2113 } 2114 2115 2116 #ifndef PRODUCT 2117 void CatchProjNode::dump_spec(outputStream *st) const { 2118 ProjNode::dump_spec(st); 2119 st->print("@bci %d ",_handler_bci); 2120 } 2121 #endif 2122 2123 //============================================================================= 2124 //------------------------------Identity--------------------------------------- 2125 // Check for CreateEx being Identity. 2126 Node *CreateExNode::Identity( PhaseTransform *phase ) { 2127 if( phase->type(in(1)) == Type::TOP ) return in(1); 2128 if( phase->type(in(0)) == Type::TOP ) return in(0); 2129 // We only come from CatchProj, unless the CatchProj goes away. 2130 // If the CatchProj is optimized away, then we just carry the 2131 // exception oop through. 2132 CallNode *call = in(1)->in(0)->as_Call(); 2133 2134 return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) ) 2135 ? this 2136 : call->in(TypeFunc::Parms); 2137 } 2138 2139 //============================================================================= 2140 //------------------------------Value------------------------------------------ 2141 // Check for being unreachable. 2142 const Type *NeverBranchNode::Value( PhaseTransform *phase ) const { 2143 if (!in(0) || in(0)->is_top()) return Type::TOP; 2144 return bottom_type(); 2145 } 2146 2147 //------------------------------Ideal------------------------------------------ 2148 // Check for no longer being part of a loop 2149 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2150 if (can_reshape && !in(0)->is_Loop()) { 2151 // Dead code elimination can sometimes delete this projection so 2152 // if it's not there, there's nothing to do. 2153 Node* fallthru = proj_out(0); 2154 if (fallthru != NULL) { 2155 phase->is_IterGVN()->replace_node(fallthru, in(0)); 2156 } 2157 return phase->C->top(); 2158 } 2159 return NULL; 2160 } 2161 2162 #ifndef PRODUCT 2163 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const { 2164 st->print("%s", Name()); 2165 } 2166 #endif