cfgnode.cpp revision 1472:c18cbe5936b8
1/* 2 * Copyright (c) 1997, 2009, 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// Portions of code courtesy of Clifford Click 26 27// Optimization - Graph Style 28 29#include "incls/_precompiled.incl" 30#include "incls/_cfgnode.cpp.incl" 31 32//============================================================================= 33//------------------------------Value------------------------------------------ 34// Compute the type of the RegionNode. 35const Type *RegionNode::Value( PhaseTransform *phase ) const { 36 for( uint i=1; i<req(); ++i ) { // For all paths in 37 Node *n = in(i); // Get Control source 38 if( !n ) continue; // Missing inputs are TOP 39 if( phase->type(n) == Type::CONTROL ) 40 return Type::CONTROL; 41 } 42 return Type::TOP; // All paths dead? Then so are we 43} 44 45//------------------------------Identity--------------------------------------- 46// Check for Region being Identity. 47Node *RegionNode::Identity( PhaseTransform *phase ) { 48 // Cannot have Region be an identity, even if it has only 1 input. 49 // Phi users cannot have their Region input folded away for them, 50 // since they need to select the proper data input 51 return this; 52} 53 54//------------------------------merge_region----------------------------------- 55// If a Region flows into a Region, merge into one big happy merge. This is 56// hard to do if there is stuff that has to happen 57static Node *merge_region(RegionNode *region, PhaseGVN *phase) { 58 if( region->Opcode() != Op_Region ) // Do not do to LoopNodes 59 return NULL; 60 Node *progress = NULL; // Progress flag 61 PhaseIterGVN *igvn = phase->is_IterGVN(); 62 63 uint rreq = region->req(); 64 for( uint i = 1; i < rreq; i++ ) { 65 Node *r = region->in(i); 66 if( r && r->Opcode() == Op_Region && // Found a region? 67 r->in(0) == r && // Not already collapsed? 68 r != region && // Avoid stupid situations 69 r->outcnt() == 2 ) { // Self user and 'region' user only? 70 assert(!r->as_Region()->has_phi(), "no phi users"); 71 if( !progress ) { // No progress 72 if (region->has_phi()) { 73 return NULL; // Only flatten if no Phi users 74 // igvn->hash_delete( phi ); 75 } 76 igvn->hash_delete( region ); 77 progress = region; // Making progress 78 } 79 igvn->hash_delete( r ); 80 81 // Append inputs to 'r' onto 'region' 82 for( uint j = 1; j < r->req(); j++ ) { 83 // Move an input from 'r' to 'region' 84 region->add_req(r->in(j)); 85 r->set_req(j, phase->C->top()); 86 // Update phis of 'region' 87 //for( uint k = 0; k < max; k++ ) { 88 // Node *phi = region->out(k); 89 // if( phi->is_Phi() ) { 90 // phi->add_req(phi->in(i)); 91 // } 92 //} 93 94 rreq++; // One more input to Region 95 } // Found a region to merge into Region 96 // Clobber pointer to the now dead 'r' 97 region->set_req(i, phase->C->top()); 98 } 99 } 100 101 return progress; 102} 103 104 105 106//--------------------------------has_phi-------------------------------------- 107// Helper function: Return any PhiNode that uses this region or NULL 108PhiNode* RegionNode::has_phi() const { 109 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 110 Node* phi = fast_out(i); 111 if (phi->is_Phi()) { // Check for Phi users 112 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)"); 113 return phi->as_Phi(); // this one is good enough 114 } 115 } 116 117 return NULL; 118} 119 120 121//-----------------------------has_unique_phi---------------------------------- 122// Helper function: Return the only PhiNode that uses this region or NULL 123PhiNode* RegionNode::has_unique_phi() const { 124 // Check that only one use is a Phi 125 PhiNode* only_phi = NULL; 126 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 127 Node* phi = fast_out(i); 128 if (phi->is_Phi()) { // Check for Phi users 129 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)"); 130 if (only_phi == NULL) { 131 only_phi = phi->as_Phi(); 132 } else { 133 return NULL; // multiple phis 134 } 135 } 136 } 137 138 return only_phi; 139} 140 141 142//------------------------------check_phi_clipping----------------------------- 143// Helper function for RegionNode's identification of FP clipping 144// Check inputs to the Phi 145static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) { 146 min = NULL; 147 max = NULL; 148 val = NULL; 149 min_idx = 0; 150 max_idx = 0; 151 val_idx = 0; 152 uint phi_max = phi->req(); 153 if( phi_max == 4 ) { 154 for( uint j = 1; j < phi_max; ++j ) { 155 Node *n = phi->in(j); 156 int opcode = n->Opcode(); 157 switch( opcode ) { 158 case Op_ConI: 159 { 160 if( min == NULL ) { 161 min = n->Opcode() == Op_ConI ? (ConNode*)n : NULL; 162 min_idx = j; 163 } else { 164 max = n->Opcode() == Op_ConI ? (ConNode*)n : NULL; 165 max_idx = j; 166 if( min->get_int() > max->get_int() ) { 167 // Swap min and max 168 ConNode *temp; 169 uint temp_idx; 170 temp = min; min = max; max = temp; 171 temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx; 172 } 173 } 174 } 175 break; 176 default: 177 { 178 val = n; 179 val_idx = j; 180 } 181 break; 182 } 183 } 184 } 185 return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) ); 186} 187 188 189//------------------------------check_if_clipping------------------------------ 190// Helper function for RegionNode's identification of FP clipping 191// Check that inputs to Region come from two IfNodes, 192// 193// If 194// False True 195// If | 196// False True | 197// | | | 198// RegionNode_inputs 199// 200static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) { 201 top_if = NULL; 202 bot_if = NULL; 203 204 // Check control structure above RegionNode for (if ( if ) ) 205 Node *in1 = region->in(1); 206 Node *in2 = region->in(2); 207 Node *in3 = region->in(3); 208 // Check that all inputs are projections 209 if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) { 210 Node *in10 = in1->in(0); 211 Node *in20 = in2->in(0); 212 Node *in30 = in3->in(0); 213 // Check that #1 and #2 are ifTrue and ifFalse from same If 214 if( in10 != NULL && in10->is_If() && 215 in20 != NULL && in20->is_If() && 216 in30 != NULL && in30->is_If() && in10 == in20 && 217 (in1->Opcode() != in2->Opcode()) ) { 218 Node *in100 = in10->in(0); 219 Node *in1000 = (in100 != NULL && in100->is_Proj()) ? in100->in(0) : NULL; 220 // Check that control for in10 comes from other branch of IF from in3 221 if( in1000 != NULL && in1000->is_If() && 222 in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) { 223 // Control pattern checks 224 top_if = (IfNode*)in1000; 225 bot_if = (IfNode*)in10; 226 } 227 } 228 } 229 230 return (top_if != NULL); 231} 232 233 234//------------------------------check_convf2i_clipping------------------------- 235// Helper function for RegionNode's identification of FP clipping 236// Verify that the value input to the phi comes from "ConvF2I; LShift; RShift" 237static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) { 238 convf2i = NULL; 239 240 // Check for the RShiftNode 241 Node *rshift = phi->in(idx); 242 assert( rshift, "Previous checks ensure phi input is present"); 243 if( rshift->Opcode() != Op_RShiftI ) { return false; } 244 245 // Check for the LShiftNode 246 Node *lshift = rshift->in(1); 247 assert( lshift, "Previous checks ensure phi input is present"); 248 if( lshift->Opcode() != Op_LShiftI ) { return false; } 249 250 // Check for the ConvF2INode 251 Node *conv = lshift->in(1); 252 if( conv->Opcode() != Op_ConvF2I ) { return false; } 253 254 // Check that shift amounts are only to get sign bits set after F2I 255 jint max_cutoff = max->get_int(); 256 jint min_cutoff = min->get_int(); 257 jint left_shift = lshift->in(2)->get_int(); 258 jint right_shift = rshift->in(2)->get_int(); 259 jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1); 260 if( left_shift != right_shift || 261 0 > left_shift || left_shift >= BitsPerJavaInteger || 262 max_post_shift < max_cutoff || 263 max_post_shift < -min_cutoff ) { 264 // Shifts are necessary but current transformation eliminates them 265 return false; 266 } 267 268 // OK to return the result of ConvF2I without shifting 269 convf2i = (ConvF2INode*)conv; 270 return true; 271} 272 273 274//------------------------------check_compare_clipping------------------------- 275// Helper function for RegionNode's identification of FP clipping 276static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) { 277 Node *i1 = iff->in(1); 278 if ( !i1->is_Bool() ) { return false; } 279 BoolNode *bool1 = i1->as_Bool(); 280 if( less_than && bool1->_test._test != BoolTest::le ) { return false; } 281 else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; } 282 const Node *cmpF = bool1->in(1); 283 if( cmpF->Opcode() != Op_CmpF ) { return false; } 284 // Test that the float value being compared against 285 // is equivalent to the int value used as a limit 286 Node *nodef = cmpF->in(2); 287 if( nodef->Opcode() != Op_ConF ) { return false; } 288 jfloat conf = nodef->getf(); 289 jint coni = limit->get_int(); 290 if( ((int)conf) != coni ) { return false; } 291 input = cmpF->in(1); 292 return true; 293} 294 295//------------------------------is_unreachable_region-------------------------- 296// Find if the Region node is reachable from the root. 297bool RegionNode::is_unreachable_region(PhaseGVN *phase) const { 298 assert(req() == 2, ""); 299 300 // First, cut the simple case of fallthrough region when NONE of 301 // region's phis references itself directly or through a data node. 302 uint max = outcnt(); 303 uint i; 304 for (i = 0; i < max; i++) { 305 Node* phi = raw_out(i); 306 if (phi != NULL && phi->is_Phi()) { 307 assert(phase->eqv(phi->in(0), this) && phi->req() == 2, ""); 308 if (phi->outcnt() == 0) 309 continue; // Safe case - no loops 310 if (phi->outcnt() == 1) { 311 Node* u = phi->raw_out(0); 312 // Skip if only one use is an other Phi or Call or Uncommon trap. 313 // It is safe to consider this case as fallthrough. 314 if (u != NULL && (u->is_Phi() || u->is_CFG())) 315 continue; 316 } 317 // Check when phi references itself directly or through an other node. 318 if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe) 319 break; // Found possible unsafe data loop. 320 } 321 } 322 if (i >= max) 323 return false; // An unsafe case was NOT found - don't need graph walk. 324 325 // Unsafe case - check if the Region node is reachable from root. 326 ResourceMark rm; 327 328 Arena *a = Thread::current()->resource_area(); 329 Node_List nstack(a); 330 VectorSet visited(a); 331 332 // Mark all control nodes reachable from root outputs 333 Node *n = (Node*)phase->C->root(); 334 nstack.push(n); 335 visited.set(n->_idx); 336 while (nstack.size() != 0) { 337 n = nstack.pop(); 338 uint max = n->outcnt(); 339 for (uint i = 0; i < max; i++) { 340 Node* m = n->raw_out(i); 341 if (m != NULL && m->is_CFG()) { 342 if (phase->eqv(m, this)) { 343 return false; // We reached the Region node - it is not dead. 344 } 345 if (!visited.test_set(m->_idx)) 346 nstack.push(m); 347 } 348 } 349 } 350 351 return true; // The Region node is unreachable - it is dead. 352} 353 354//------------------------------Ideal------------------------------------------ 355// Return a node which is more "ideal" than the current node. Must preserve 356// the CFG, but we can still strip out dead paths. 357Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) { 358 if( !can_reshape && !in(0) ) return NULL; // Already degraded to a Copy 359 assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge"); 360 361 // Check for RegionNode with no Phi users and both inputs come from either 362 // arm of the same IF. If found, then the control-flow split is useless. 363 bool has_phis = false; 364 if (can_reshape) { // Need DU info to check for Phi users 365 has_phis = (has_phi() != NULL); // Cache result 366 if (!has_phis) { // No Phi users? Nothing merging? 367 for (uint i = 1; i < req()-1; i++) { 368 Node *if1 = in(i); 369 if( !if1 ) continue; 370 Node *iff = if1->in(0); 371 if( !iff || !iff->is_If() ) continue; 372 for( uint j=i+1; j<req(); j++ ) { 373 if( in(j) && in(j)->in(0) == iff && 374 if1->Opcode() != in(j)->Opcode() ) { 375 // Add the IF Projections to the worklist. They (and the IF itself) 376 // will be eliminated if dead. 377 phase->is_IterGVN()->add_users_to_worklist(iff); 378 set_req(i, iff->in(0));// Skip around the useless IF diamond 379 set_req(j, NULL); 380 return this; // Record progress 381 } 382 } 383 } 384 } 385 } 386 387 // Remove TOP or NULL input paths. If only 1 input path remains, this Region 388 // degrades to a copy. 389 bool add_to_worklist = false; 390 int cnt = 0; // Count of values merging 391 DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count 392 int del_it = 0; // The last input path we delete 393 // For all inputs... 394 for( uint i=1; i<req(); ++i ){// For all paths in 395 Node *n = in(i); // Get the input 396 if( n != NULL ) { 397 // Remove useless control copy inputs 398 if( n->is_Region() && n->as_Region()->is_copy() ) { 399 set_req(i, n->nonnull_req()); 400 i--; 401 continue; 402 } 403 if( n->is_Proj() ) { // Remove useless rethrows 404 Node *call = n->in(0); 405 if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) { 406 set_req(i, call->in(0)); 407 i--; 408 continue; 409 } 410 } 411 if( phase->type(n) == Type::TOP ) { 412 set_req(i, NULL); // Ignore TOP inputs 413 i--; 414 continue; 415 } 416 cnt++; // One more value merging 417 418 } else if (can_reshape) { // Else found dead path with DU info 419 PhaseIterGVN *igvn = phase->is_IterGVN(); 420 del_req(i); // Yank path from self 421 del_it = i; 422 uint max = outcnt(); 423 DUIterator j; 424 bool progress = true; 425 while(progress) { // Need to establish property over all users 426 progress = false; 427 for (j = outs(); has_out(j); j++) { 428 Node *n = out(j); 429 if( n->req() != req() && n->is_Phi() ) { 430 assert( n->in(0) == this, "" ); 431 igvn->hash_delete(n); // Yank from hash before hacking edges 432 n->set_req_X(i,NULL,igvn);// Correct DU info 433 n->del_req(i); // Yank path from Phis 434 if( max != outcnt() ) { 435 progress = true; 436 j = refresh_out_pos(j); 437 max = outcnt(); 438 } 439 } 440 } 441 } 442 add_to_worklist = true; 443 i--; 444 } 445 } 446 447 if (can_reshape && cnt == 1) { 448 // Is it dead loop? 449 // If it is LoopNopde it had 2 (+1 itself) inputs and 450 // one of them was cut. The loop is dead if it was EntryContol. 451 assert(!this->is_Loop() || cnt_orig == 3, "Loop node should have 3 inputs"); 452 if (this->is_Loop() && del_it == LoopNode::EntryControl || 453 !this->is_Loop() && has_phis && is_unreachable_region(phase)) { 454 // Yes, the region will be removed during the next step below. 455 // Cut the backedge input and remove phis since no data paths left. 456 // We don't cut outputs to other nodes here since we need to put them 457 // on the worklist. 458 del_req(1); 459 cnt = 0; 460 assert( req() == 1, "no more inputs expected" ); 461 uint max = outcnt(); 462 bool progress = true; 463 Node *top = phase->C->top(); 464 PhaseIterGVN *igvn = phase->is_IterGVN(); 465 DUIterator j; 466 while(progress) { 467 progress = false; 468 for (j = outs(); has_out(j); j++) { 469 Node *n = out(j); 470 if( n->is_Phi() ) { 471 assert( igvn->eqv(n->in(0), this), "" ); 472 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" ); 473 // Break dead loop data path. 474 // Eagerly replace phis with top to avoid phis copies generation. 475 igvn->add_users_to_worklist(n); 476 igvn->hash_delete(n); // Yank from hash before hacking edges 477 igvn->subsume_node(n, top); 478 if( max != outcnt() ) { 479 progress = true; 480 j = refresh_out_pos(j); 481 max = outcnt(); 482 } 483 } 484 } 485 } 486 add_to_worklist = true; 487 } 488 } 489 if (add_to_worklist) { 490 phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis 491 } 492 493 if( cnt <= 1 ) { // Only 1 path in? 494 set_req(0, NULL); // Null control input for region copy 495 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is. 496 // No inputs or all inputs are NULL. 497 return NULL; 498 } else if (can_reshape) { // Optimization phase - remove the node 499 PhaseIterGVN *igvn = phase->is_IterGVN(); 500 Node *parent_ctrl; 501 if( cnt == 0 ) { 502 assert( req() == 1, "no inputs expected" ); 503 // During IGVN phase such region will be subsumed by TOP node 504 // so region's phis will have TOP as control node. 505 // Kill phis here to avoid it. PhiNode::is_copy() will be always false. 506 // Also set other user's input to top. 507 parent_ctrl = phase->C->top(); 508 } else { 509 // The fallthrough case since we already checked dead loops above. 510 parent_ctrl = in(1); 511 assert(parent_ctrl != NULL, "Region is a copy of some non-null control"); 512 assert(!igvn->eqv(parent_ctrl, this), "Close dead loop"); 513 } 514 if (!add_to_worklist) 515 igvn->add_users_to_worklist(this); // Check for further allowed opts 516 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) { 517 Node* n = last_out(i); 518 igvn->hash_delete(n); // Remove from worklist before modifying edges 519 if( n->is_Phi() ) { // Collapse all Phis 520 // Eagerly replace phis to avoid copies generation. 521 igvn->add_users_to_worklist(n); 522 igvn->hash_delete(n); // Yank from hash before hacking edges 523 if( cnt == 0 ) { 524 assert( n->req() == 1, "No data inputs expected" ); 525 igvn->subsume_node(n, parent_ctrl); // replaced by top 526 } else { 527 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" ); 528 Node* in1 = n->in(1); // replaced by unique input 529 if( n->as_Phi()->is_unsafe_data_reference(in1) ) 530 in1 = phase->C->top(); // replaced by top 531 igvn->subsume_node(n, in1); 532 } 533 } 534 else if( n->is_Region() ) { // Update all incoming edges 535 assert( !igvn->eqv(n, this), "Must be removed from DefUse edges"); 536 uint uses_found = 0; 537 for( uint k=1; k < n->req(); k++ ) { 538 if( n->in(k) == this ) { 539 n->set_req(k, parent_ctrl); 540 uses_found++; 541 } 542 } 543 if( uses_found > 1 ) { // (--i) done at the end of the loop. 544 i -= (uses_found - 1); 545 } 546 } 547 else { 548 assert( igvn->eqv(n->in(0), this), "Expect RegionNode to be control parent"); 549 n->set_req(0, parent_ctrl); 550 } 551#ifdef ASSERT 552 for( uint k=0; k < n->req(); k++ ) { 553 assert( !igvn->eqv(n->in(k), this), "All uses of RegionNode should be gone"); 554 } 555#endif 556 } 557 // Remove the RegionNode itself from DefUse info 558 igvn->remove_dead_node(this); 559 return NULL; 560 } 561 return this; // Record progress 562 } 563 564 565 // If a Region flows into a Region, merge into one big happy merge. 566 if (can_reshape) { 567 Node *m = merge_region(this, phase); 568 if (m != NULL) return m; 569 } 570 571 // Check if this region is the root of a clipping idiom on floats 572 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) { 573 // Check that only one use is a Phi and that it simplifies to two constants + 574 PhiNode* phi = has_unique_phi(); 575 if (phi != NULL) { // One Phi user 576 // Check inputs to the Phi 577 ConNode *min; 578 ConNode *max; 579 Node *val; 580 uint min_idx; 581 uint max_idx; 582 uint val_idx; 583 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) { 584 IfNode *top_if; 585 IfNode *bot_if; 586 if( check_if_clipping( this, bot_if, top_if ) ) { 587 // Control pattern checks, now verify compares 588 Node *top_in = NULL; // value being compared against 589 Node *bot_in = NULL; 590 if( check_compare_clipping( true, bot_if, min, bot_in ) && 591 check_compare_clipping( false, top_if, max, top_in ) ) { 592 if( bot_in == top_in ) { 593 PhaseIterGVN *gvn = phase->is_IterGVN(); 594 assert( gvn != NULL, "Only had DefUse info in IterGVN"); 595 // Only remaining check is that bot_in == top_in == (Phi's val + mods) 596 597 // Check for the ConvF2INode 598 ConvF2INode *convf2i; 599 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) && 600 convf2i->in(1) == bot_in ) { 601 // Matched pattern, including LShiftI; RShiftI, replace with integer compares 602 // max test 603 Node *cmp = gvn->register_new_node_with_optimizer(new (phase->C, 3) CmpINode( convf2i, min )); 604 Node *boo = gvn->register_new_node_with_optimizer(new (phase->C, 2) BoolNode( cmp, BoolTest::lt )); 605 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 )); 606 Node *if_min= gvn->register_new_node_with_optimizer(new (phase->C, 1) IfTrueNode (iff)); 607 Node *ifF = gvn->register_new_node_with_optimizer(new (phase->C, 1) IfFalseNode(iff)); 608 // min test 609 cmp = gvn->register_new_node_with_optimizer(new (phase->C, 3) CmpINode( convf2i, max )); 610 boo = gvn->register_new_node_with_optimizer(new (phase->C, 2) BoolNode( cmp, BoolTest::gt )); 611 iff = (IfNode*)gvn->register_new_node_with_optimizer(new (phase->C, 2) IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt )); 612 Node *if_max= gvn->register_new_node_with_optimizer(new (phase->C, 1) IfTrueNode (iff)); 613 ifF = gvn->register_new_node_with_optimizer(new (phase->C, 1) IfFalseNode(iff)); 614 // update input edges to region node 615 set_req_X( min_idx, if_min, gvn ); 616 set_req_X( max_idx, if_max, gvn ); 617 set_req_X( val_idx, ifF, gvn ); 618 // remove unnecessary 'LShiftI; RShiftI' idiom 619 gvn->hash_delete(phi); 620 phi->set_req_X( val_idx, convf2i, gvn ); 621 gvn->hash_find_insert(phi); 622 // Return transformed region node 623 return this; 624 } 625 } 626 } 627 } 628 } 629 } 630 } 631 632 return NULL; 633} 634 635 636 637const RegMask &RegionNode::out_RegMask() const { 638 return RegMask::Empty; 639} 640 641// Find the one non-null required input. RegionNode only 642Node *Node::nonnull_req() const { 643 assert( is_Region(), "" ); 644 for( uint i = 1; i < _cnt; i++ ) 645 if( in(i) ) 646 return in(i); 647 ShouldNotReachHere(); 648 return NULL; 649} 650 651 652//============================================================================= 653// note that these functions assume that the _adr_type field is flattened 654uint PhiNode::hash() const { 655 const Type* at = _adr_type; 656 return TypeNode::hash() + (at ? at->hash() : 0); 657} 658uint PhiNode::cmp( const Node &n ) const { 659 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type; 660} 661static inline 662const TypePtr* flatten_phi_adr_type(const TypePtr* at) { 663 if (at == NULL || at == TypePtr::BOTTOM) return at; 664 return Compile::current()->alias_type(at)->adr_type(); 665} 666 667//----------------------------make--------------------------------------------- 668// create a new phi with edges matching r and set (initially) to x 669PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) { 670 uint preds = r->req(); // Number of predecessor paths 671 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at"); 672 PhiNode* p = new (Compile::current(), preds) PhiNode(r, t, at); 673 for (uint j = 1; j < preds; j++) { 674 // Fill in all inputs, except those which the region does not yet have 675 if (r->in(j) != NULL) 676 p->init_req(j, x); 677 } 678 return p; 679} 680PhiNode* PhiNode::make(Node* r, Node* x) { 681 const Type* t = x->bottom_type(); 682 const TypePtr* at = NULL; 683 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type()); 684 return make(r, x, t, at); 685} 686PhiNode* PhiNode::make_blank(Node* r, Node* x) { 687 const Type* t = x->bottom_type(); 688 const TypePtr* at = NULL; 689 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type()); 690 return new (Compile::current(), r->req()) PhiNode(r, t, at); 691} 692 693 694//------------------------slice_memory----------------------------------------- 695// create a new phi with narrowed memory type 696PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const { 697 PhiNode* mem = (PhiNode*) clone(); 698 *(const TypePtr**)&mem->_adr_type = adr_type; 699 // convert self-loops, or else we get a bad graph 700 for (uint i = 1; i < req(); i++) { 701 if ((const Node*)in(i) == this) mem->set_req(i, mem); 702 } 703 mem->verify_adr_type(); 704 return mem; 705} 706 707//------------------------split_out_instance----------------------------------- 708// Split out an instance type from a bottom phi. 709PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const { 710 const TypeOopPtr *t_oop = at->isa_oopptr(); 711 assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr"); 712 const TypePtr *t = adr_type(); 713 assert(type() == Type::MEMORY && 714 (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM || 715 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() && 716 t->is_oopptr()->cast_to_exactness(true) 717 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr()) 718 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop), 719 "bottom or raw memory required"); 720 721 // Check if an appropriate node already exists. 722 Node *region = in(0); 723 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) { 724 Node* use = region->fast_out(k); 725 if( use->is_Phi()) { 726 PhiNode *phi2 = use->as_Phi(); 727 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) { 728 return phi2; 729 } 730 } 731 } 732 Compile *C = igvn->C; 733 Arena *a = Thread::current()->resource_area(); 734 Node_Array node_map = new Node_Array(a); 735 Node_Stack stack(a, C->unique() >> 4); 736 PhiNode *nphi = slice_memory(at); 737 igvn->register_new_node_with_optimizer( nphi ); 738 node_map.map(_idx, nphi); 739 stack.push((Node *)this, 1); 740 while(!stack.is_empty()) { 741 PhiNode *ophi = stack.node()->as_Phi(); 742 uint i = stack.index(); 743 assert(i >= 1, "not control edge"); 744 stack.pop(); 745 nphi = node_map[ophi->_idx]->as_Phi(); 746 for (; i < ophi->req(); i++) { 747 Node *in = ophi->in(i); 748 if (in == NULL || igvn->type(in) == Type::TOP) 749 continue; 750 Node *opt = MemNode::optimize_simple_memory_chain(in, at, igvn); 751 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL; 752 if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) { 753 opt = node_map[optphi->_idx]; 754 if (opt == NULL) { 755 stack.push(ophi, i); 756 nphi = optphi->slice_memory(at); 757 igvn->register_new_node_with_optimizer( nphi ); 758 node_map.map(optphi->_idx, nphi); 759 ophi = optphi; 760 i = 0; // will get incremented at top of loop 761 continue; 762 } 763 } 764 nphi->set_req(i, opt); 765 } 766 } 767 return nphi; 768} 769 770//------------------------verify_adr_type-------------------------------------- 771#ifdef ASSERT 772void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const { 773 if (visited.test_set(_idx)) return; //already visited 774 775 // recheck constructor invariants: 776 verify_adr_type(false); 777 778 // recheck local phi/phi consistency: 779 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM, 780 "adr_type must be consistent across phi nest"); 781 782 // walk around 783 for (uint i = 1; i < req(); i++) { 784 Node* n = in(i); 785 if (n == NULL) continue; 786 const Node* np = in(i); 787 if (np->is_Phi()) { 788 np->as_Phi()->verify_adr_type(visited, at); 789 } else if (n->bottom_type() == Type::TOP 790 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) { 791 // ignore top inputs 792 } else { 793 const TypePtr* nat = flatten_phi_adr_type(n->adr_type()); 794 // recheck phi/non-phi consistency at leaves: 795 assert((nat != NULL) == (at != NULL), ""); 796 assert(nat == at || nat == TypePtr::BOTTOM, 797 "adr_type must be consistent at leaves of phi nest"); 798 } 799 } 800} 801 802// Verify a whole nest of phis rooted at this one. 803void PhiNode::verify_adr_type(bool recursive) const { 804 if (is_error_reported()) return; // muzzle asserts when debugging an error 805 if (Node::in_dump()) return; // muzzle asserts when printing 806 807 assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only"); 808 809 if (!VerifyAliases) return; // verify thoroughly only if requested 810 811 assert(_adr_type == flatten_phi_adr_type(_adr_type), 812 "Phi::adr_type must be pre-normalized"); 813 814 if (recursive) { 815 VectorSet visited(Thread::current()->resource_area()); 816 verify_adr_type(visited, _adr_type); 817 } 818} 819#endif 820 821 822//------------------------------Value------------------------------------------ 823// Compute the type of the PhiNode 824const Type *PhiNode::Value( PhaseTransform *phase ) const { 825 Node *r = in(0); // RegionNode 826 if( !r ) // Copy or dead 827 return in(1) ? phase->type(in(1)) : Type::TOP; 828 829 // Note: During parsing, phis are often transformed before their regions. 830 // This means we have to use type_or_null to defend against untyped regions. 831 if( phase->type_or_null(r) == Type::TOP ) // Dead code? 832 return Type::TOP; 833 834 // Check for trip-counted loop. If so, be smarter. 835 CountedLoopNode *l = r->is_CountedLoop() ? r->as_CountedLoop() : NULL; 836 if( l && l->can_be_counted_loop(phase) && 837 ((const Node*)l->phi() == this) ) { // Trip counted loop! 838 // protect against init_trip() or limit() returning NULL 839 const Node *init = l->init_trip(); 840 const Node *limit = l->limit(); 841 if( init != NULL && limit != NULL && l->stride_is_con() ) { 842 const TypeInt *lo = init ->bottom_type()->isa_int(); 843 const TypeInt *hi = limit->bottom_type()->isa_int(); 844 if( lo && hi ) { // Dying loops might have TOP here 845 int stride = l->stride_con(); 846 if( stride < 0 ) { // Down-counter loop 847 const TypeInt *tmp = lo; lo = hi; hi = tmp; 848 stride = -stride; 849 } 850 if( lo->_hi < hi->_lo ) // Reversed endpoints are well defined :-( 851 return TypeInt::make(lo->_lo,hi->_hi,3); 852 } 853 } 854 } 855 856 // Until we have harmony between classes and interfaces in the type 857 // lattice, we must tread carefully around phis which implicitly 858 // convert the one to the other. 859 const TypePtr* ttp = _type->make_ptr(); 860 const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL; 861 const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_klassptr() : NULL; 862 bool is_intf = false; 863 if (ttip != NULL) { 864 ciKlass* k = ttip->klass(); 865 if (k->is_loaded() && k->is_interface()) 866 is_intf = true; 867 } 868 if (ttkp != NULL) { 869 ciKlass* k = ttkp->klass(); 870 if (k->is_loaded() && k->is_interface()) 871 is_intf = true; 872 } 873 874 // Default case: merge all inputs 875 const Type *t = Type::TOP; // Merged type starting value 876 for (uint i = 1; i < req(); ++i) {// For all paths in 877 // Reachable control path? 878 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) { 879 const Type* ti = phase->type(in(i)); 880 // We assume that each input of an interface-valued Phi is a true 881 // subtype of that interface. This might not be true of the meet 882 // of all the input types. The lattice is not distributive in 883 // such cases. Ward off asserts in type.cpp by refusing to do 884 // meets between interfaces and proper classes. 885 const TypePtr* tip = ti->make_ptr(); 886 const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL; 887 if (tiip) { 888 bool ti_is_intf = false; 889 ciKlass* k = tiip->klass(); 890 if (k->is_loaded() && k->is_interface()) 891 ti_is_intf = true; 892 if (is_intf != ti_is_intf) 893 { t = _type; break; } 894 } 895 t = t->meet(ti); 896 } 897 } 898 899 // The worst-case type (from ciTypeFlow) should be consistent with "t". 900 // That is, we expect that "t->higher_equal(_type)" holds true. 901 // There are various exceptions: 902 // - Inputs which are phis might in fact be widened unnecessarily. 903 // For example, an input might be a widened int while the phi is a short. 904 // - Inputs might be BotPtrs but this phi is dependent on a null check, 905 // and postCCP has removed the cast which encodes the result of the check. 906 // - The type of this phi is an interface, and the inputs are classes. 907 // - Value calls on inputs might produce fuzzy results. 908 // (Occurrences of this case suggest improvements to Value methods.) 909 // 910 // It is not possible to see Type::BOTTOM values as phi inputs, 911 // because the ciTypeFlow pre-pass produces verifier-quality types. 912 const Type* ft = t->filter(_type); // Worst case type 913 914#ifdef ASSERT 915 // The following logic has been moved into TypeOopPtr::filter. 916 const Type* jt = t->join(_type); 917 if( jt->empty() ) { // Emptied out??? 918 919 // Check for evil case of 't' being a class and '_type' expecting an 920 // interface. This can happen because the bytecodes do not contain 921 // enough type info to distinguish a Java-level interface variable 922 // from a Java-level object variable. If we meet 2 classes which 923 // both implement interface I, but their meet is at 'j/l/O' which 924 // doesn't implement I, we have no way to tell if the result should 925 // be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows 926 // into a Phi which "knows" it's an Interface type we'll have to 927 // uplift the type. 928 if( !t->empty() && ttip && ttip->is_loaded() && ttip->klass()->is_interface() ) 929 { assert(ft == _type, ""); } // Uplift to interface 930 else if( !t->empty() && ttkp && ttkp->is_loaded() && ttkp->klass()->is_interface() ) 931 { assert(ft == _type, ""); } // Uplift to interface 932 // Otherwise it's something stupid like non-overlapping int ranges 933 // found on dying counted loops. 934 else 935 { assert(ft == Type::TOP, ""); } // Canonical empty value 936 } 937 938 else { 939 940 // If we have an interface-typed Phi and we narrow to a class type, the join 941 // should report back the class. However, if we have a J/L/Object 942 // class-typed Phi and an interface flows in, it's possible that the meet & 943 // join report an interface back out. This isn't possible but happens 944 // because the type system doesn't interact well with interfaces. 945 const TypePtr *jtp = jt->make_ptr(); 946 const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL; 947 const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_klassptr() : NULL; 948 if( jtip && ttip ) { 949 if( jtip->is_loaded() && jtip->klass()->is_interface() && 950 ttip->is_loaded() && !ttip->klass()->is_interface() ) { 951 // Happens in a CTW of rt.jar, 320-341, no extra flags 952 assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) || 953 ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), ""); 954 jt = ft; 955 } 956 } 957 if( jtkp && ttkp ) { 958 if( jtkp->is_loaded() && jtkp->klass()->is_interface() && 959 !jtkp->klass_is_exact() && // Keep exact interface klass (6894807) 960 ttkp->is_loaded() && !ttkp->klass()->is_interface() ) { 961 assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) || 962 ft->isa_narrowoop() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), ""); 963 jt = ft; 964 } 965 } 966 if (jt != ft && jt->base() == ft->base()) { 967 if (jt->isa_int() && 968 jt->is_int()->_lo == ft->is_int()->_lo && 969 jt->is_int()->_hi == ft->is_int()->_hi) 970 jt = ft; 971 if (jt->isa_long() && 972 jt->is_long()->_lo == ft->is_long()->_lo && 973 jt->is_long()->_hi == ft->is_long()->_hi) 974 jt = ft; 975 } 976 if (jt != ft) { 977 tty->print("merge type: "); t->dump(); tty->cr(); 978 tty->print("kill type: "); _type->dump(); tty->cr(); 979 tty->print("join type: "); jt->dump(); tty->cr(); 980 tty->print("filter type: "); ft->dump(); tty->cr(); 981 } 982 assert(jt == ft, ""); 983 } 984#endif //ASSERT 985 986 // Deal with conversion problems found in data loops. 987 ft = phase->saturate(ft, phase->type_or_null(this), _type); 988 989 return ft; 990} 991 992 993//------------------------------is_diamond_phi--------------------------------- 994// Does this Phi represent a simple well-shaped diamond merge? Return the 995// index of the true path or 0 otherwise. 996int PhiNode::is_diamond_phi() const { 997 // Check for a 2-path merge 998 Node *region = in(0); 999 if( !region ) return 0; 1000 if( region->req() != 3 ) return 0; 1001 if( req() != 3 ) return 0; 1002 // Check that both paths come from the same If 1003 Node *ifp1 = region->in(1); 1004 Node *ifp2 = region->in(2); 1005 if( !ifp1 || !ifp2 ) return 0; 1006 Node *iff = ifp1->in(0); 1007 if( !iff || !iff->is_If() ) return 0; 1008 if( iff != ifp2->in(0) ) return 0; 1009 // Check for a proper bool/cmp 1010 const Node *b = iff->in(1); 1011 if( !b->is_Bool() ) return 0; 1012 const Node *cmp = b->in(1); 1013 if( !cmp->is_Cmp() ) return 0; 1014 1015 // Check for branching opposite expected 1016 if( ifp2->Opcode() == Op_IfTrue ) { 1017 assert( ifp1->Opcode() == Op_IfFalse, "" ); 1018 return 2; 1019 } else { 1020 assert( ifp1->Opcode() == Op_IfTrue, "" ); 1021 return 1; 1022 } 1023} 1024 1025//----------------------------check_cmove_id----------------------------------- 1026// Check for CMove'ing a constant after comparing against the constant. 1027// Happens all the time now, since if we compare equality vs a constant in 1028// the parser, we "know" the variable is constant on one path and we force 1029// it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a 1030// conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more 1031// general in that we don't need constants. Since CMove's are only inserted 1032// in very special circumstances, we do it here on generic Phi's. 1033Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) { 1034 assert(true_path !=0, "only diamond shape graph expected"); 1035 1036 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1037 // phi->region->if_proj->ifnode->bool->cmp 1038 Node* region = in(0); 1039 Node* iff = region->in(1)->in(0); 1040 BoolNode* b = iff->in(1)->as_Bool(); 1041 Node* cmp = b->in(1); 1042 Node* tval = in(true_path); 1043 Node* fval = in(3-true_path); 1044 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b); 1045 if (id == NULL) 1046 return NULL; 1047 1048 // Either value might be a cast that depends on a branch of 'iff'. 1049 // Since the 'id' value will float free of the diamond, either 1050 // decast or return failure. 1051 Node* ctl = id->in(0); 1052 if (ctl != NULL && ctl->in(0) == iff) { 1053 if (id->is_ConstraintCast()) { 1054 return id->in(1); 1055 } else { 1056 // Don't know how to disentangle this value. 1057 return NULL; 1058 } 1059 } 1060 1061 return id; 1062} 1063 1064//------------------------------Identity--------------------------------------- 1065// Check for Region being Identity. 1066Node *PhiNode::Identity( PhaseTransform *phase ) { 1067 // Check for no merging going on 1068 // (There used to be special-case code here when this->region->is_Loop. 1069 // It would check for a tributary phi on the backedge that the main phi 1070 // trivially, perhaps with a single cast. The unique_input method 1071 // does all this and more, by reducing such tributaries to 'this'.) 1072 Node* uin = unique_input(phase); 1073 if (uin != NULL) { 1074 return uin; 1075 } 1076 1077 int true_path = is_diamond_phi(); 1078 if (true_path != 0) { 1079 Node* id = is_cmove_id(phase, true_path); 1080 if (id != NULL) return id; 1081 } 1082 1083 return this; // No identity 1084} 1085 1086//-----------------------------unique_input------------------------------------ 1087// Find the unique value, discounting top, self-loops, and casts. 1088// Return top if there are no inputs, and self if there are multiple. 1089Node* PhiNode::unique_input(PhaseTransform* phase) { 1090 // 1) One unique direct input, or 1091 // 2) some of the inputs have an intervening ConstraintCast and 1092 // the type of input is the same or sharper (more specific) 1093 // than the phi's type. 1094 // 3) an input is a self loop 1095 // 1096 // 1) input or 2) input or 3) input __ 1097 // / \ / \ \ / \ 1098 // \ / | cast phi cast 1099 // phi \ / / \ / 1100 // phi / -- 1101 1102 Node* r = in(0); // RegionNode 1103 if (r == NULL) return in(1); // Already degraded to a Copy 1104 Node* uncasted_input = NULL; // The unique uncasted input (ConstraintCasts removed) 1105 Node* direct_input = NULL; // The unique direct input 1106 1107 for (uint i = 1, cnt = req(); i < cnt; ++i) { 1108 Node* rc = r->in(i); 1109 if (rc == NULL || phase->type(rc) == Type::TOP) 1110 continue; // ignore unreachable control path 1111 Node* n = in(i); 1112 if (n == NULL) 1113 continue; 1114 Node* un = n->uncast(); 1115 if (un == NULL || un == this || phase->type(un) == Type::TOP) { 1116 continue; // ignore if top, or in(i) and "this" are in a data cycle 1117 } 1118 // Check for a unique uncasted input 1119 if (uncasted_input == NULL) { 1120 uncasted_input = un; 1121 } else if (uncasted_input != un) { 1122 uncasted_input = NodeSentinel; // no unique uncasted input 1123 } 1124 // Check for a unique direct input 1125 if (direct_input == NULL) { 1126 direct_input = n; 1127 } else if (direct_input != n) { 1128 direct_input = NodeSentinel; // no unique direct input 1129 } 1130 } 1131 if (direct_input == NULL) { 1132 return phase->C->top(); // no inputs 1133 } 1134 assert(uncasted_input != NULL,""); 1135 1136 if (direct_input != NodeSentinel) { 1137 return direct_input; // one unique direct input 1138 } 1139 if (uncasted_input != NodeSentinel && 1140 phase->type(uncasted_input)->higher_equal(type())) { 1141 return uncasted_input; // one unique uncasted input 1142 } 1143 1144 // Nothing. 1145 return NULL; 1146} 1147 1148//------------------------------is_x2logic------------------------------------- 1149// Check for simple convert-to-boolean pattern 1150// If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1) 1151// Convert Phi to an ConvIB. 1152static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) { 1153 assert(true_path !=0, "only diamond shape graph expected"); 1154 // Convert the true/false index into an expected 0/1 return. 1155 // Map 2->0 and 1->1. 1156 int flipped = 2-true_path; 1157 1158 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1159 // phi->region->if_proj->ifnode->bool->cmp 1160 Node *region = phi->in(0); 1161 Node *iff = region->in(1)->in(0); 1162 BoolNode *b = (BoolNode*)iff->in(1); 1163 const CmpNode *cmp = (CmpNode*)b->in(1); 1164 1165 Node *zero = phi->in(1); 1166 Node *one = phi->in(2); 1167 const Type *tzero = phase->type( zero ); 1168 const Type *tone = phase->type( one ); 1169 1170 // Check for compare vs 0 1171 const Type *tcmp = phase->type(cmp->in(2)); 1172 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) { 1173 // Allow cmp-vs-1 if the other input is bounded by 0-1 1174 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) ) 1175 return NULL; 1176 flipped = 1-flipped; // Test is vs 1 instead of 0! 1177 } 1178 1179 // Check for setting zero/one opposite expected 1180 if( tzero == TypeInt::ZERO ) { 1181 if( tone == TypeInt::ONE ) { 1182 } else return NULL; 1183 } else if( tzero == TypeInt::ONE ) { 1184 if( tone == TypeInt::ZERO ) { 1185 flipped = 1-flipped; 1186 } else return NULL; 1187 } else return NULL; 1188 1189 // Check for boolean test backwards 1190 if( b->_test._test == BoolTest::ne ) { 1191 } else if( b->_test._test == BoolTest::eq ) { 1192 flipped = 1-flipped; 1193 } else return NULL; 1194 1195 // Build int->bool conversion 1196 Node *n = new (phase->C, 2) Conv2BNode( cmp->in(1) ); 1197 if( flipped ) 1198 n = new (phase->C, 3) XorINode( phase->transform(n), phase->intcon(1) ); 1199 1200 return n; 1201} 1202 1203//------------------------------is_cond_add------------------------------------ 1204// Check for simple conditional add pattern: "(P < Q) ? X+Y : X;" 1205// To be profitable the control flow has to disappear; there can be no other 1206// values merging here. We replace the test-and-branch with: 1207// "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by 1208// moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'. 1209// Then convert Y to 0-or-Y and finally add. 1210// This is a key transform for SpecJava _201_compress. 1211static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) { 1212 assert(true_path !=0, "only diamond shape graph expected"); 1213 1214 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1215 // phi->region->if_proj->ifnode->bool->cmp 1216 RegionNode *region = (RegionNode*)phi->in(0); 1217 Node *iff = region->in(1)->in(0); 1218 BoolNode* b = iff->in(1)->as_Bool(); 1219 const CmpNode *cmp = (CmpNode*)b->in(1); 1220 1221 // Make sure only merging this one phi here 1222 if (region->has_unique_phi() != phi) return NULL; 1223 1224 // Make sure each arm of the diamond has exactly one output, which we assume 1225 // is the region. Otherwise, the control flow won't disappear. 1226 if (region->in(1)->outcnt() != 1) return NULL; 1227 if (region->in(2)->outcnt() != 1) return NULL; 1228 1229 // Check for "(P < Q)" of type signed int 1230 if (b->_test._test != BoolTest::lt) return NULL; 1231 if (cmp->Opcode() != Op_CmpI) return NULL; 1232 1233 Node *p = cmp->in(1); 1234 Node *q = cmp->in(2); 1235 Node *n1 = phi->in( true_path); 1236 Node *n2 = phi->in(3-true_path); 1237 1238 int op = n1->Opcode(); 1239 if( op != Op_AddI // Need zero as additive identity 1240 /*&&op != Op_SubI && 1241 op != Op_AddP && 1242 op != Op_XorI && 1243 op != Op_OrI*/ ) 1244 return NULL; 1245 1246 Node *x = n2; 1247 Node *y = n1->in(1); 1248 if( n2 == n1->in(1) ) { 1249 y = n1->in(2); 1250 } else if( n2 == n1->in(1) ) { 1251 } else return NULL; 1252 1253 // Not so profitable if compare and add are constants 1254 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() ) 1255 return NULL; 1256 1257 Node *cmplt = phase->transform( new (phase->C, 3) CmpLTMaskNode(p,q) ); 1258 Node *j_and = phase->transform( new (phase->C, 3) AndINode(cmplt,y) ); 1259 return new (phase->C, 3) AddINode(j_and,x); 1260} 1261 1262//------------------------------is_absolute------------------------------------ 1263// Check for absolute value. 1264static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) { 1265 assert(true_path !=0, "only diamond shape graph expected"); 1266 1267 int cmp_zero_idx = 0; // Index of compare input where to look for zero 1268 int phi_x_idx = 0; // Index of phi input where to find naked x 1269 1270 // ABS ends with the merge of 2 control flow paths. 1271 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely. 1272 int false_path = 3 - true_path; 1273 1274 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1275 // phi->region->if_proj->ifnode->bool->cmp 1276 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool(); 1277 1278 // Check bool sense 1279 switch( bol->_test._test ) { 1280 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break; 1281 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break; 1282 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break; 1283 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break; 1284 default: return NULL; break; 1285 } 1286 1287 // Test is next 1288 Node *cmp = bol->in(1); 1289 const Type *tzero = NULL; 1290 switch( cmp->Opcode() ) { 1291 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS 1292 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS 1293 default: return NULL; 1294 } 1295 1296 // Find zero input of compare; the other input is being abs'd 1297 Node *x = NULL; 1298 bool flip = false; 1299 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) { 1300 x = cmp->in(3 - cmp_zero_idx); 1301 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) { 1302 // The test is inverted, we should invert the result... 1303 x = cmp->in(cmp_zero_idx); 1304 flip = true; 1305 } else { 1306 return NULL; 1307 } 1308 1309 // Next get the 2 pieces being selected, one is the original value 1310 // and the other is the negated value. 1311 if( phi_root->in(phi_x_idx) != x ) return NULL; 1312 1313 // Check other phi input for subtract node 1314 Node *sub = phi_root->in(3 - phi_x_idx); 1315 1316 // Allow only Sub(0,X) and fail out for all others; Neg is not OK 1317 if( tzero == TypeF::ZERO ) { 1318 if( sub->Opcode() != Op_SubF || 1319 sub->in(2) != x || 1320 phase->type(sub->in(1)) != tzero ) return NULL; 1321 x = new (phase->C, 2) AbsFNode(x); 1322 if (flip) { 1323 x = new (phase->C, 3) SubFNode(sub->in(1), phase->transform(x)); 1324 } 1325 } else { 1326 if( sub->Opcode() != Op_SubD || 1327 sub->in(2) != x || 1328 phase->type(sub->in(1)) != tzero ) return NULL; 1329 x = new (phase->C, 2) AbsDNode(x); 1330 if (flip) { 1331 x = new (phase->C, 3) SubDNode(sub->in(1), phase->transform(x)); 1332 } 1333 } 1334 1335 return x; 1336} 1337 1338//------------------------------split_once------------------------------------- 1339// Helper for split_flow_path 1340static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) { 1341 igvn->hash_delete(n); // Remove from hash before hacking edges 1342 1343 uint j = 1; 1344 for( uint i = phi->req()-1; i > 0; i-- ) { 1345 if( phi->in(i) == val ) { // Found a path with val? 1346 // Add to NEW Region/Phi, no DU info 1347 newn->set_req( j++, n->in(i) ); 1348 // Remove from OLD Region/Phi 1349 n->del_req(i); 1350 } 1351 } 1352 1353 // Register the new node but do not transform it. Cannot transform until the 1354 // entire Region/Phi conglomerate has been hacked as a single huge transform. 1355 igvn->register_new_node_with_optimizer( newn ); 1356 // Now I can point to the new node. 1357 n->add_req(newn); 1358 igvn->_worklist.push(n); 1359} 1360 1361//------------------------------split_flow_path-------------------------------- 1362// Check for merging identical values and split flow paths 1363static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) { 1364 BasicType bt = phi->type()->basic_type(); 1365 if( bt == T_ILLEGAL || type2size[bt] <= 0 ) 1366 return NULL; // Bail out on funny non-value stuff 1367 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a 1368 return NULL; // third unequal input to be worth doing 1369 1370 // Scan for a constant 1371 uint i; 1372 for( i = 1; i < phi->req()-1; i++ ) { 1373 Node *n = phi->in(i); 1374 if( !n ) return NULL; 1375 if( phase->type(n) == Type::TOP ) return NULL; 1376 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN ) 1377 break; 1378 } 1379 if( i >= phi->req() ) // Only split for constants 1380 return NULL; 1381 1382 Node *val = phi->in(i); // Constant to split for 1383 uint hit = 0; // Number of times it occurs 1384 1385 for( ; i < phi->req(); i++ ){ // Count occurrences of constant 1386 Node *n = phi->in(i); 1387 if( !n ) return NULL; 1388 if( phase->type(n) == Type::TOP ) return NULL; 1389 if( phi->in(i) == val ) 1390 hit++; 1391 } 1392 1393 if( hit <= 1 || // Make sure we find 2 or more 1394 hit == phi->req()-1 ) // and not ALL the same value 1395 return NULL; 1396 1397 // Now start splitting out the flow paths that merge the same value. 1398 // Split first the RegionNode. 1399 PhaseIterGVN *igvn = phase->is_IterGVN(); 1400 Node *r = phi->region(); 1401 RegionNode *newr = new (phase->C, hit+1) RegionNode(hit+1); 1402 split_once(igvn, phi, val, r, newr); 1403 1404 // Now split all other Phis than this one 1405 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) { 1406 Node* phi2 = r->fast_out(k); 1407 if( phi2->is_Phi() && phi2->as_Phi() != phi ) { 1408 PhiNode *newphi = PhiNode::make_blank(newr, phi2); 1409 split_once(igvn, phi, val, phi2, newphi); 1410 } 1411 } 1412 1413 // Clean up this guy 1414 igvn->hash_delete(phi); 1415 for( i = phi->req()-1; i > 0; i-- ) { 1416 if( phi->in(i) == val ) { 1417 phi->del_req(i); 1418 } 1419 } 1420 phi->add_req(val); 1421 1422 return phi; 1423} 1424 1425//============================================================================= 1426//------------------------------simple_data_loop_check------------------------- 1427// Try to determining if the phi node in a simple safe/unsafe data loop. 1428// Returns: 1429// enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop }; 1430// Safe - safe case when the phi and it's inputs reference only safe data 1431// nodes; 1432// Unsafe - the phi and it's inputs reference unsafe data nodes but there 1433// is no reference back to the phi - need a graph walk 1434// to determine if it is in a loop; 1435// UnsafeLoop - unsafe case when the phi references itself directly or through 1436// unsafe data node. 1437// Note: a safe data node is a node which could/never reference itself during 1438// GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP. 1439// I mark Phi nodes as safe node not only because they can reference itself 1440// but also to prevent mistaking the fallthrough case inside an outer loop 1441// as dead loop when the phi references itselfs through an other phi. 1442PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const { 1443 // It is unsafe loop if the phi node references itself directly. 1444 if (in == (Node*)this) 1445 return UnsafeLoop; // Unsafe loop 1446 // Unsafe loop if the phi node references itself through an unsafe data node. 1447 // Exclude cases with null inputs or data nodes which could reference 1448 // itself (safe for dead loops). 1449 if (in != NULL && !in->is_dead_loop_safe()) { 1450 // Check inputs of phi's inputs also. 1451 // It is much less expensive then full graph walk. 1452 uint cnt = in->req(); 1453 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1; 1454 for (; i < cnt; ++i) { 1455 Node* m = in->in(i); 1456 if (m == (Node*)this) 1457 return UnsafeLoop; // Unsafe loop 1458 if (m != NULL && !m->is_dead_loop_safe()) { 1459 // Check the most common case (about 30% of all cases): 1460 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con). 1461 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL; 1462 if (m1 == (Node*)this) 1463 return UnsafeLoop; // Unsafe loop 1464 if (m1 != NULL && m1 == m->in(2) && 1465 m1->is_dead_loop_safe() && m->in(3)->is_Con()) { 1466 continue; // Safe case 1467 } 1468 // The phi references an unsafe node - need full analysis. 1469 return Unsafe; 1470 } 1471 } 1472 } 1473 return Safe; // Safe case - we can optimize the phi node. 1474} 1475 1476//------------------------------is_unsafe_data_reference----------------------- 1477// If phi can be reached through the data input - it is data loop. 1478bool PhiNode::is_unsafe_data_reference(Node *in) const { 1479 assert(req() > 1, ""); 1480 // First, check simple cases when phi references itself directly or 1481 // through an other node. 1482 LoopSafety safety = simple_data_loop_check(in); 1483 if (safety == UnsafeLoop) 1484 return true; // phi references itself - unsafe loop 1485 else if (safety == Safe) 1486 return false; // Safe case - phi could be replaced with the unique input. 1487 1488 // Unsafe case when we should go through data graph to determine 1489 // if the phi references itself. 1490 1491 ResourceMark rm; 1492 1493 Arena *a = Thread::current()->resource_area(); 1494 Node_List nstack(a); 1495 VectorSet visited(a); 1496 1497 nstack.push(in); // Start with unique input. 1498 visited.set(in->_idx); 1499 while (nstack.size() != 0) { 1500 Node* n = nstack.pop(); 1501 uint cnt = n->req(); 1502 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1; 1503 for (; i < cnt; i++) { 1504 Node* m = n->in(i); 1505 if (m == (Node*)this) { 1506 return true; // Data loop 1507 } 1508 if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases. 1509 if (!visited.test_set(m->_idx)) 1510 nstack.push(m); 1511 } 1512 } 1513 } 1514 return false; // The phi is not reachable from its inputs 1515} 1516 1517 1518//------------------------------Ideal------------------------------------------ 1519// Return a node which is more "ideal" than the current node. Must preserve 1520// the CFG, but we can still strip out dead paths. 1521Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1522 // The next should never happen after 6297035 fix. 1523 if( is_copy() ) // Already degraded to a Copy ? 1524 return NULL; // No change 1525 1526 Node *r = in(0); // RegionNode 1527 assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge"); 1528 1529 // Note: During parsing, phis are often transformed before their regions. 1530 // This means we have to use type_or_null to defend against untyped regions. 1531 if( phase->type_or_null(r) == Type::TOP ) // Dead code? 1532 return NULL; // No change 1533 1534 Node *top = phase->C->top(); 1535 bool new_phi = (outcnt() == 0); // transforming new Phi 1536 assert(!can_reshape || !new_phi, "for igvn new phi should be hooked"); 1537 1538 // The are 2 situations when only one valid phi's input is left 1539 // (in addition to Region input). 1540 // One: region is not loop - replace phi with this input. 1541 // Two: region is loop - replace phi with top since this data path is dead 1542 // and we need to break the dead data loop. 1543 Node* progress = NULL; // Record if any progress made 1544 for( uint j = 1; j < req(); ++j ){ // For all paths in 1545 // Check unreachable control paths 1546 Node* rc = r->in(j); 1547 Node* n = in(j); // Get the input 1548 if (rc == NULL || phase->type(rc) == Type::TOP) { 1549 if (n != top) { // Not already top? 1550 set_req(j, top); // Nuke it down 1551 progress = this; // Record progress 1552 } 1553 } 1554 } 1555 1556 if (can_reshape && outcnt() == 0) { 1557 // set_req() above may kill outputs if Phi is referenced 1558 // only by itself on the dead (top) control path. 1559 return top; 1560 } 1561 1562 Node* uin = unique_input(phase); 1563 if (uin == top) { // Simplest case: no alive inputs. 1564 if (can_reshape) // IGVN transformation 1565 return top; 1566 else 1567 return NULL; // Identity will return TOP 1568 } else if (uin != NULL) { 1569 // Only one not-NULL unique input path is left. 1570 // Determine if this input is backedge of a loop. 1571 // (Skip new phis which have no uses and dead regions). 1572 if( outcnt() > 0 && r->in(0) != NULL ) { 1573 // First, take the short cut when we know it is a loop and 1574 // the EntryControl data path is dead. 1575 assert(!r->is_Loop() || r->req() == 3, "Loop node should have 3 inputs"); 1576 // Then, check if there is a data loop when phi references itself directly 1577 // or through other data nodes. 1578 if( r->is_Loop() && !phase->eqv_uncast(uin, in(LoopNode::EntryControl)) || 1579 !r->is_Loop() && is_unsafe_data_reference(uin) ) { 1580 // Break this data loop to avoid creation of a dead loop. 1581 if (can_reshape) { 1582 return top; 1583 } else { 1584 // We can't return top if we are in Parse phase - cut inputs only 1585 // let Identity to handle the case. 1586 replace_edge(uin, top); 1587 return NULL; 1588 } 1589 } 1590 } 1591 1592 // One unique input. 1593 debug_only(Node* ident = Identity(phase)); 1594 // The unique input must eventually be detected by the Identity call. 1595#ifdef ASSERT 1596 if (ident != uin && !ident->is_top()) { 1597 // print this output before failing assert 1598 r->dump(3); 1599 this->dump(3); 1600 ident->dump(); 1601 uin->dump(); 1602 } 1603#endif 1604 assert(ident == uin || ident->is_top(), "Identity must clean this up"); 1605 return NULL; 1606 } 1607 1608 1609 Node* opt = NULL; 1610 int true_path = is_diamond_phi(); 1611 if( true_path != 0 ) { 1612 // Check for CMove'ing identity. If it would be unsafe, 1613 // handle it here. In the safe case, let Identity handle it. 1614 Node* unsafe_id = is_cmove_id(phase, true_path); 1615 if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) ) 1616 opt = unsafe_id; 1617 1618 // Check for simple convert-to-boolean pattern 1619 if( opt == NULL ) 1620 opt = is_x2logic(phase, this, true_path); 1621 1622 // Check for absolute value 1623 if( opt == NULL ) 1624 opt = is_absolute(phase, this, true_path); 1625 1626 // Check for conditional add 1627 if( opt == NULL && can_reshape ) 1628 opt = is_cond_add(phase, this, true_path); 1629 1630 // These 4 optimizations could subsume the phi: 1631 // have to check for a dead data loop creation. 1632 if( opt != NULL ) { 1633 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) { 1634 // Found dead loop. 1635 if( can_reshape ) 1636 return top; 1637 // We can't return top if we are in Parse phase - cut inputs only 1638 // to stop further optimizations for this phi. Identity will return TOP. 1639 assert(req() == 3, "only diamond merge phi here"); 1640 set_req(1, top); 1641 set_req(2, top); 1642 return NULL; 1643 } else { 1644 return opt; 1645 } 1646 } 1647 } 1648 1649 // Check for merging identical values and split flow paths 1650 if (can_reshape) { 1651 opt = split_flow_path(phase, this); 1652 // This optimization only modifies phi - don't need to check for dead loop. 1653 assert(opt == NULL || phase->eqv(opt, this), "do not elide phi"); 1654 if (opt != NULL) return opt; 1655 } 1656 1657 if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) { 1658 // Try to undo Phi of AddP: 1659 // (Phi (AddP base base y) (AddP base2 base2 y)) 1660 // becomes: 1661 // newbase := (Phi base base2) 1662 // (AddP newbase newbase y) 1663 // 1664 // This occurs as a result of unsuccessful split_thru_phi and 1665 // interferes with taking advantage of addressing modes. See the 1666 // clone_shift_expressions code in matcher.cpp 1667 Node* addp = in(1); 1668 const Type* type = addp->in(AddPNode::Base)->bottom_type(); 1669 Node* y = addp->in(AddPNode::Offset); 1670 if (y != NULL && addp->in(AddPNode::Base) == addp->in(AddPNode::Address)) { 1671 // make sure that all the inputs are similar to the first one, 1672 // i.e. AddP with base == address and same offset as first AddP 1673 bool doit = true; 1674 for (uint i = 2; i < req(); i++) { 1675 if (in(i) == NULL || 1676 in(i)->Opcode() != Op_AddP || 1677 in(i)->in(AddPNode::Base) != in(i)->in(AddPNode::Address) || 1678 in(i)->in(AddPNode::Offset) != y) { 1679 doit = false; 1680 break; 1681 } 1682 // Accumulate type for resulting Phi 1683 type = type->meet(in(i)->in(AddPNode::Base)->bottom_type()); 1684 } 1685 Node* base = NULL; 1686 if (doit) { 1687 // Check for neighboring AddP nodes in a tree. 1688 // If they have a base, use that it. 1689 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) { 1690 Node* u = this->fast_out(k); 1691 if (u->is_AddP()) { 1692 Node* base2 = u->in(AddPNode::Base); 1693 if (base2 != NULL && !base2->is_top()) { 1694 if (base == NULL) 1695 base = base2; 1696 else if (base != base2) 1697 { doit = false; break; } 1698 } 1699 } 1700 } 1701 } 1702 if (doit) { 1703 if (base == NULL) { 1704 base = new (phase->C, in(0)->req()) PhiNode(in(0), type, NULL); 1705 for (uint i = 1; i < req(); i++) { 1706 base->init_req(i, in(i)->in(AddPNode::Base)); 1707 } 1708 phase->is_IterGVN()->register_new_node_with_optimizer(base); 1709 } 1710 return new (phase->C, 4) AddPNode(base, base, y); 1711 } 1712 } 1713 } 1714 1715 // Split phis through memory merges, so that the memory merges will go away. 1716 // Piggy-back this transformation on the search for a unique input.... 1717 // It will be as if the merged memory is the unique value of the phi. 1718 // (Do not attempt this optimization unless parsing is complete. 1719 // It would make the parser's memory-merge logic sick.) 1720 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.) 1721 if (progress == NULL && can_reshape && type() == Type::MEMORY) { 1722 // see if this phi should be sliced 1723 uint merge_width = 0; 1724 bool saw_self = false; 1725 for( uint i=1; i<req(); ++i ) {// For all paths in 1726 Node *ii = in(i); 1727 if (ii->is_MergeMem()) { 1728 MergeMemNode* n = ii->as_MergeMem(); 1729 merge_width = MAX2(merge_width, n->req()); 1730 saw_self = saw_self || phase->eqv(n->base_memory(), this); 1731 } 1732 } 1733 1734 // This restriction is temporarily necessary to ensure termination: 1735 if (!saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0; 1736 1737 if (merge_width > Compile::AliasIdxRaw) { 1738 // found at least one non-empty MergeMem 1739 const TypePtr* at = adr_type(); 1740 if (at != TypePtr::BOTTOM) { 1741 // Patch the existing phi to select an input from the merge: 1742 // Phi:AT1(...MergeMem(m0, m1, m2)...) into 1743 // Phi:AT1(...m1...) 1744 int alias_idx = phase->C->get_alias_index(at); 1745 for (uint i=1; i<req(); ++i) { 1746 Node *ii = in(i); 1747 if (ii->is_MergeMem()) { 1748 MergeMemNode* n = ii->as_MergeMem(); 1749 // compress paths and change unreachable cycles to TOP 1750 // If not, we can update the input infinitely along a MergeMem cycle 1751 // Equivalent code is in MemNode::Ideal_common 1752 Node *m = phase->transform(n); 1753 if (outcnt() == 0) { // Above transform() may kill us! 1754 return top; 1755 } 1756 // If transformed to a MergeMem, get the desired slice 1757 // Otherwise the returned node represents memory for every slice 1758 Node *new_mem = (m->is_MergeMem()) ? 1759 m->as_MergeMem()->memory_at(alias_idx) : m; 1760 // Update input if it is progress over what we have now 1761 if (new_mem != ii) { 1762 set_req(i, new_mem); 1763 progress = this; 1764 } 1765 } 1766 } 1767 } else { 1768 // We know that at least one MergeMem->base_memory() == this 1769 // (saw_self == true). If all other inputs also references this phi 1770 // (directly or through data nodes) - it is dead loop. 1771 bool saw_safe_input = false; 1772 for (uint j = 1; j < req(); ++j) { 1773 Node *n = in(j); 1774 if (n->is_MergeMem() && n->as_MergeMem()->base_memory() == this) 1775 continue; // skip known cases 1776 if (!is_unsafe_data_reference(n)) { 1777 saw_safe_input = true; // found safe input 1778 break; 1779 } 1780 } 1781 if (!saw_safe_input) 1782 return top; // all inputs reference back to this phi - dead loop 1783 1784 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into 1785 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...)) 1786 PhaseIterGVN *igvn = phase->is_IterGVN(); 1787 Node* hook = new (phase->C, 1) Node(1); 1788 PhiNode* new_base = (PhiNode*) clone(); 1789 // Must eagerly register phis, since they participate in loops. 1790 if (igvn) { 1791 igvn->register_new_node_with_optimizer(new_base); 1792 hook->add_req(new_base); 1793 } 1794 MergeMemNode* result = MergeMemNode::make(phase->C, new_base); 1795 for (uint i = 1; i < req(); ++i) { 1796 Node *ii = in(i); 1797 if (ii->is_MergeMem()) { 1798 MergeMemNode* n = ii->as_MergeMem(); 1799 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) { 1800 // If we have not seen this slice yet, make a phi for it. 1801 bool made_new_phi = false; 1802 if (mms.is_empty()) { 1803 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C)); 1804 made_new_phi = true; 1805 if (igvn) { 1806 igvn->register_new_node_with_optimizer(new_phi); 1807 hook->add_req(new_phi); 1808 } 1809 mms.set_memory(new_phi); 1810 } 1811 Node* phi = mms.memory(); 1812 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice"); 1813 phi->set_req(i, mms.memory2()); 1814 } 1815 } 1816 } 1817 // Distribute all self-loops. 1818 { // (Extra braces to hide mms.) 1819 for (MergeMemStream mms(result); mms.next_non_empty(); ) { 1820 Node* phi = mms.memory(); 1821 for (uint i = 1; i < req(); ++i) { 1822 if (phi->in(i) == this) phi->set_req(i, phi); 1823 } 1824 } 1825 } 1826 // now transform the new nodes, and return the mergemem 1827 for (MergeMemStream mms(result); mms.next_non_empty(); ) { 1828 Node* phi = mms.memory(); 1829 mms.set_memory(phase->transform(phi)); 1830 } 1831 if (igvn) { // Unhook. 1832 igvn->hash_delete(hook); 1833 for (uint i = 1; i < hook->req(); i++) { 1834 hook->set_req(i, NULL); 1835 } 1836 } 1837 // Replace self with the result. 1838 return result; 1839 } 1840 } 1841 // 1842 // Other optimizations on the memory chain 1843 // 1844 const TypePtr* at = adr_type(); 1845 for( uint i=1; i<req(); ++i ) {// For all paths in 1846 Node *ii = in(i); 1847 Node *new_in = MemNode::optimize_memory_chain(ii, at, phase); 1848 if (ii != new_in ) { 1849 set_req(i, new_in); 1850 progress = this; 1851 } 1852 } 1853 } 1854 1855#ifdef _LP64 1856 // Push DecodeN down through phi. 1857 // The rest of phi graph will transform by split EncodeP node though phis up. 1858 if (UseCompressedOops && can_reshape && progress == NULL) { 1859 bool may_push = true; 1860 bool has_decodeN = false; 1861 for (uint i=1; i<req(); ++i) {// For all paths in 1862 Node *ii = in(i); 1863 if (ii->is_DecodeN() && ii->bottom_type() == bottom_type()) { 1864 // Do optimization if a non dead path exist. 1865 if (ii->in(1)->bottom_type() != Type::TOP) { 1866 has_decodeN = true; 1867 } 1868 } else if (!ii->is_Phi()) { 1869 may_push = false; 1870 } 1871 } 1872 1873 if (has_decodeN && may_push) { 1874 PhaseIterGVN *igvn = phase->is_IterGVN(); 1875 // Make narrow type for new phi. 1876 const Type* narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr()); 1877 PhiNode* new_phi = new (phase->C, r->req()) PhiNode(r, narrow_t); 1878 uint orig_cnt = req(); 1879 for (uint i=1; i<req(); ++i) {// For all paths in 1880 Node *ii = in(i); 1881 Node* new_ii = NULL; 1882 if (ii->is_DecodeN()) { 1883 assert(ii->bottom_type() == bottom_type(), "sanity"); 1884 new_ii = ii->in(1); 1885 } else { 1886 assert(ii->is_Phi(), "sanity"); 1887 if (ii->as_Phi() == this) { 1888 new_ii = new_phi; 1889 } else { 1890 new_ii = new (phase->C, 2) EncodePNode(ii, narrow_t); 1891 igvn->register_new_node_with_optimizer(new_ii); 1892 } 1893 } 1894 new_phi->set_req(i, new_ii); 1895 } 1896 igvn->register_new_node_with_optimizer(new_phi, this); 1897 progress = new (phase->C, 2) DecodeNNode(new_phi, bottom_type()); 1898 } 1899 } 1900#endif 1901 1902 return progress; // Return any progress 1903} 1904 1905//------------------------------is_tripcount----------------------------------- 1906bool PhiNode::is_tripcount() const { 1907 return (in(0) != NULL && in(0)->is_CountedLoop() && 1908 in(0)->as_CountedLoop()->phi() == this); 1909} 1910 1911//------------------------------out_RegMask------------------------------------ 1912const RegMask &PhiNode::in_RegMask(uint i) const { 1913 return i ? out_RegMask() : RegMask::Empty; 1914} 1915 1916const RegMask &PhiNode::out_RegMask() const { 1917 uint ideal_reg = Matcher::base2reg[_type->base()]; 1918 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" ); 1919 if( ideal_reg == 0 ) return RegMask::Empty; 1920 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]); 1921} 1922 1923#ifndef PRODUCT 1924void PhiNode::dump_spec(outputStream *st) const { 1925 TypeNode::dump_spec(st); 1926 if (is_tripcount()) { 1927 st->print(" #tripcount"); 1928 } 1929} 1930#endif 1931 1932 1933//============================================================================= 1934const Type *GotoNode::Value( PhaseTransform *phase ) const { 1935 // If the input is reachable, then we are executed. 1936 // If the input is not reachable, then we are not executed. 1937 return phase->type(in(0)); 1938} 1939 1940Node *GotoNode::Identity( PhaseTransform *phase ) { 1941 return in(0); // Simple copy of incoming control 1942} 1943 1944const RegMask &GotoNode::out_RegMask() const { 1945 return RegMask::Empty; 1946} 1947 1948//============================================================================= 1949const RegMask &JumpNode::out_RegMask() const { 1950 return RegMask::Empty; 1951} 1952 1953//============================================================================= 1954const RegMask &JProjNode::out_RegMask() const { 1955 return RegMask::Empty; 1956} 1957 1958//============================================================================= 1959const RegMask &CProjNode::out_RegMask() const { 1960 return RegMask::Empty; 1961} 1962 1963 1964 1965//============================================================================= 1966 1967uint PCTableNode::hash() const { return Node::hash() + _size; } 1968uint PCTableNode::cmp( const Node &n ) const 1969{ return _size == ((PCTableNode&)n)._size; } 1970 1971const Type *PCTableNode::bottom_type() const { 1972 const Type** f = TypeTuple::fields(_size); 1973 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL; 1974 return TypeTuple::make(_size, f); 1975} 1976 1977//------------------------------Value------------------------------------------ 1978// Compute the type of the PCTableNode. If reachable it is a tuple of 1979// Control, otherwise the table targets are not reachable 1980const Type *PCTableNode::Value( PhaseTransform *phase ) const { 1981 if( phase->type(in(0)) == Type::CONTROL ) 1982 return bottom_type(); 1983 return Type::TOP; // All paths dead? Then so are we 1984} 1985 1986//------------------------------Ideal------------------------------------------ 1987// Return a node which is more "ideal" than the current node. Strip out 1988// control copies 1989Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1990 return remove_dead_region(phase, can_reshape) ? this : NULL; 1991} 1992 1993//============================================================================= 1994uint JumpProjNode::hash() const { 1995 return Node::hash() + _dest_bci; 1996} 1997 1998uint JumpProjNode::cmp( const Node &n ) const { 1999 return ProjNode::cmp(n) && 2000 _dest_bci == ((JumpProjNode&)n)._dest_bci; 2001} 2002 2003#ifndef PRODUCT 2004void JumpProjNode::dump_spec(outputStream *st) const { 2005 ProjNode::dump_spec(st); 2006 st->print("@bci %d ",_dest_bci); 2007} 2008#endif 2009 2010//============================================================================= 2011//------------------------------Value------------------------------------------ 2012// Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot 2013// have the default "fall_through_index" path. 2014const Type *CatchNode::Value( PhaseTransform *phase ) const { 2015 // Unreachable? Then so are all paths from here. 2016 if( phase->type(in(0)) == Type::TOP ) return Type::TOP; 2017 // First assume all paths are reachable 2018 const Type** f = TypeTuple::fields(_size); 2019 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL; 2020 // Identify cases that will always throw an exception 2021 // () rethrow call 2022 // () virtual or interface call with NULL receiver 2023 // () call is a check cast with incompatible arguments 2024 if( in(1)->is_Proj() ) { 2025 Node *i10 = in(1)->in(0); 2026 if( i10->is_Call() ) { 2027 CallNode *call = i10->as_Call(); 2028 // Rethrows always throw exceptions, never return 2029 if (call->entry_point() == OptoRuntime::rethrow_stub()) { 2030 f[CatchProjNode::fall_through_index] = Type::TOP; 2031 } else if( call->req() > TypeFunc::Parms ) { 2032 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) ); 2033 // Check for null receiver to virtual or interface calls 2034 if( call->is_CallDynamicJava() && 2035 arg0->higher_equal(TypePtr::NULL_PTR) ) { 2036 f[CatchProjNode::fall_through_index] = Type::TOP; 2037 } 2038 } // End of if not a runtime stub 2039 } // End of if have call above me 2040 } // End of slot 1 is not a projection 2041 return TypeTuple::make(_size, f); 2042} 2043 2044//============================================================================= 2045uint CatchProjNode::hash() const { 2046 return Node::hash() + _handler_bci; 2047} 2048 2049 2050uint CatchProjNode::cmp( const Node &n ) const { 2051 return ProjNode::cmp(n) && 2052 _handler_bci == ((CatchProjNode&)n)._handler_bci; 2053} 2054 2055 2056//------------------------------Identity--------------------------------------- 2057// If only 1 target is possible, choose it if it is the main control 2058Node *CatchProjNode::Identity( PhaseTransform *phase ) { 2059 // If my value is control and no other value is, then treat as ID 2060 const TypeTuple *t = phase->type(in(0))->is_tuple(); 2061 if (t->field_at(_con) != Type::CONTROL) return this; 2062 // If we remove the last CatchProj and elide the Catch/CatchProj, then we 2063 // also remove any exception table entry. Thus we must know the call 2064 // feeding the Catch will not really throw an exception. This is ok for 2065 // the main fall-thru control (happens when we know a call can never throw 2066 // an exception) or for "rethrow", because a further optimization will 2067 // yank the rethrow (happens when we inline a function that can throw an 2068 // exception and the caller has no handler). Not legal, e.g., for passing 2069 // a NULL receiver to a v-call, or passing bad types to a slow-check-cast. 2070 // These cases MUST throw an exception via the runtime system, so the VM 2071 // will be looking for a table entry. 2072 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode 2073 CallNode *call; 2074 if (_con != TypeFunc::Control && // Bail out if not the main control. 2075 !(proj->is_Proj() && // AND NOT a rethrow 2076 proj->in(0)->is_Call() && 2077 (call = proj->in(0)->as_Call()) && 2078 call->entry_point() == OptoRuntime::rethrow_stub())) 2079 return this; 2080 2081 // Search for any other path being control 2082 for (uint i = 0; i < t->cnt(); i++) { 2083 if (i != _con && t->field_at(i) == Type::CONTROL) 2084 return this; 2085 } 2086 // Only my path is possible; I am identity on control to the jump 2087 return in(0)->in(0); 2088} 2089 2090 2091#ifndef PRODUCT 2092void CatchProjNode::dump_spec(outputStream *st) const { 2093 ProjNode::dump_spec(st); 2094 st->print("@bci %d ",_handler_bci); 2095} 2096#endif 2097 2098//============================================================================= 2099//------------------------------Identity--------------------------------------- 2100// Check for CreateEx being Identity. 2101Node *CreateExNode::Identity( PhaseTransform *phase ) { 2102 if( phase->type(in(1)) == Type::TOP ) return in(1); 2103 if( phase->type(in(0)) == Type::TOP ) return in(0); 2104 // We only come from CatchProj, unless the CatchProj goes away. 2105 // If the CatchProj is optimized away, then we just carry the 2106 // exception oop through. 2107 CallNode *call = in(1)->in(0)->as_Call(); 2108 2109 return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) ) 2110 ? this 2111 : call->in(TypeFunc::Parms); 2112} 2113 2114//============================================================================= 2115//------------------------------Value------------------------------------------ 2116// Check for being unreachable. 2117const Type *NeverBranchNode::Value( PhaseTransform *phase ) const { 2118 if (!in(0) || in(0)->is_top()) return Type::TOP; 2119 return bottom_type(); 2120} 2121 2122//------------------------------Ideal------------------------------------------ 2123// Check for no longer being part of a loop 2124Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2125 if (can_reshape && !in(0)->is_Loop()) { 2126 // Dead code elimination can sometimes delete this projection so 2127 // if it's not there, there's nothing to do. 2128 Node* fallthru = proj_out(0); 2129 if (fallthru != NULL) { 2130 phase->is_IterGVN()->subsume_node(fallthru, in(0)); 2131 } 2132 return phase->C->top(); 2133 } 2134 return NULL; 2135} 2136 2137#ifndef PRODUCT 2138void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const { 2139 st->print("%s", Name()); 2140} 2141#endif 2142