1 /* 2 * Copyright (c) 1998, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #ifndef SHARE_VM_OPTO_LOOPNODE_HPP 26 #define SHARE_VM_OPTO_LOOPNODE_HPP 27 28 #include "opto/cfgnode.hpp" 29 #include "opto/multnode.hpp" 30 #include "opto/phaseX.hpp" 31 #include "opto/subnode.hpp" 32 #include "opto/type.hpp" 33 34 class CmpNode; 35 class CountedLoopEndNode; 36 class CountedLoopNode; 37 class IdealLoopTree; 38 class LoopNode; 39 class Node; 40 class PhaseIdealLoop; 41 class VectorSet; 42 class Invariance; 43 struct small_cache; 44 45 // 46 // I D E A L I Z E D L O O P S 47 // 48 // Idealized loops are the set of loops I perform more interesting 49 // transformations on, beyond simple hoisting. 50 51 //------------------------------LoopNode--------------------------------------- 52 // Simple loop header. Fall in path on left, loop-back path on right. 53 class LoopNode : public RegionNode { 54 // Size is bigger to hold the flags. However, the flags do not change 55 // the semantics so it does not appear in the hash & cmp functions. 56 virtual uint size_of() const { return sizeof(*this); } 57 protected: 58 short _loop_flags; 59 // Names for flag bitfields 60 enum { Normal=0, Pre=1, Main=2, Post=3, PreMainPostFlagsMask=3, 61 MainHasNoPreLoop=4, 62 HasExactTripCount=8, 63 InnerLoop=16, 64 PartialPeelLoop=32, 65 PartialPeelFailed=64, 66 HasReductions=128, 67 PassedSlpAnalysis=256 }; 68 char _unswitch_count; 69 enum { _unswitch_max=3 }; 70 71 public: 72 // Names for edge indices 73 enum { Self=0, EntryControl, LoopBackControl }; 74 75 int is_inner_loop() const { return _loop_flags & InnerLoop; } 76 void set_inner_loop() { _loop_flags |= InnerLoop; } 77 78 int is_partial_peel_loop() const { return _loop_flags & PartialPeelLoop; } 79 void set_partial_peel_loop() { _loop_flags |= PartialPeelLoop; } 80 int partial_peel_has_failed() const { return _loop_flags & PartialPeelFailed; } 81 void mark_partial_peel_failed() { _loop_flags |= PartialPeelFailed; } 82 void mark_has_reductions() { _loop_flags |= HasReductions; } 83 void mark_passed_slp() { _loop_flags |= PassedSlpAnalysis; } 84 85 int unswitch_max() { return _unswitch_max; } 86 int unswitch_count() { return _unswitch_count; } 87 void set_unswitch_count(int val) { 88 assert (val <= unswitch_max(), "too many unswitches"); 89 _unswitch_count = val; 90 } 91 92 LoopNode( Node *entry, Node *backedge ) : RegionNode(3), _loop_flags(0), _unswitch_count(0) { 93 init_class_id(Class_Loop); 94 init_req(EntryControl, entry); 95 init_req(LoopBackControl, backedge); 96 } 97 98 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); 99 virtual int Opcode() const; 100 bool can_be_counted_loop(PhaseTransform* phase) const { 101 return req() == 3 && in(0) != NULL && 102 in(1) != NULL && phase->type(in(1)) != Type::TOP && 103 in(2) != NULL && phase->type(in(2)) != Type::TOP; 104 } 105 bool is_valid_counted_loop() const; 106 #ifndef PRODUCT 107 virtual void dump_spec(outputStream *st) const; 108 #endif 109 }; 110 111 //------------------------------Counted Loops---------------------------------- 112 // Counted loops are all trip-counted loops, with exactly 1 trip-counter exit 113 // path (and maybe some other exit paths). The trip-counter exit is always 114 // last in the loop. The trip-counter have to stride by a constant; 115 // the exit value is also loop invariant. 116 117 // CountedLoopNodes and CountedLoopEndNodes come in matched pairs. The 118 // CountedLoopNode has the incoming loop control and the loop-back-control 119 // which is always the IfTrue before the matching CountedLoopEndNode. The 120 // CountedLoopEndNode has an incoming control (possibly not the 121 // CountedLoopNode if there is control flow in the loop), the post-increment 122 // trip-counter value, and the limit. The trip-counter value is always of 123 // the form (Op old-trip-counter stride). The old-trip-counter is produced 124 // by a Phi connected to the CountedLoopNode. The stride is constant. 125 // The Op is any commutable opcode, including Add, Mul, Xor. The 126 // CountedLoopEndNode also takes in the loop-invariant limit value. 127 128 // From a CountedLoopNode I can reach the matching CountedLoopEndNode via the 129 // loop-back control. From CountedLoopEndNodes I can reach CountedLoopNodes 130 // via the old-trip-counter from the Op node. 131 132 //------------------------------CountedLoopNode-------------------------------- 133 // CountedLoopNodes head simple counted loops. CountedLoopNodes have as 134 // inputs the incoming loop-start control and the loop-back control, so they 135 // act like RegionNodes. They also take in the initial trip counter, the 136 // loop-invariant stride and the loop-invariant limit value. CountedLoopNodes 137 // produce a loop-body control and the trip counter value. Since 138 // CountedLoopNodes behave like RegionNodes I still have a standard CFG model. 139 140 class CountedLoopNode : public LoopNode { 141 // Size is bigger to hold _main_idx. However, _main_idx does not change 142 // the semantics so it does not appear in the hash & cmp functions. 143 virtual uint size_of() const { return sizeof(*this); } 144 145 // For Pre- and Post-loops during debugging ONLY, this holds the index of 146 // the Main CountedLoop. Used to assert that we understand the graph shape. 147 node_idx_t _main_idx; 148 149 // Known trip count calculated by compute_exact_trip_count() 150 uint _trip_count; 151 152 // Expected trip count from profile data 153 float _profile_trip_cnt; 154 155 // Log2 of original loop bodies in unrolled loop 156 int _unrolled_count_log2; 157 158 // Node count prior to last unrolling - used to decide if 159 // unroll,optimize,unroll,optimize,... is making progress 160 int _node_count_before_unroll; 161 162 // If slp analysis is performed we record the maximum 163 // vector mapped unroll factor here 164 int _slp_maximum_unroll_factor; 165 166 public: 167 CountedLoopNode( Node *entry, Node *backedge ) 168 : LoopNode(entry, backedge), _main_idx(0), _trip_count(max_juint), 169 _profile_trip_cnt(COUNT_UNKNOWN), _unrolled_count_log2(0), 170 _node_count_before_unroll(0), _slp_maximum_unroll_factor(0) { 171 init_class_id(Class_CountedLoop); 172 // Initialize _trip_count to the largest possible value. 173 // Will be reset (lower) if the loop's trip count is known. 174 } 175 176 virtual int Opcode() const; 177 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); 178 179 Node *init_control() const { return in(EntryControl); } 180 Node *back_control() const { return in(LoopBackControl); } 181 CountedLoopEndNode *loopexit() const; 182 Node *init_trip() const; 183 Node *stride() const; 184 int stride_con() const; 185 bool stride_is_con() const; 186 Node *limit() const; 187 Node *incr() const; 188 Node *phi() const; 189 190 // Match increment with optional truncation 191 static Node* match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type); 192 193 // A 'main' loop has a pre-loop and a post-loop. The 'main' loop 194 // can run short a few iterations and may start a few iterations in. 195 // It will be RCE'd and unrolled and aligned. 196 197 // A following 'post' loop will run any remaining iterations. Used 198 // during Range Check Elimination, the 'post' loop will do any final 199 // iterations with full checks. Also used by Loop Unrolling, where 200 // the 'post' loop will do any epilog iterations needed. Basically, 201 // a 'post' loop can not profitably be further unrolled or RCE'd. 202 203 // A preceding 'pre' loop will run at least 1 iteration (to do peeling), 204 // it may do under-flow checks for RCE and may do alignment iterations 205 // so the following main loop 'knows' that it is striding down cache 206 // lines. 207 208 // A 'main' loop that is ONLY unrolled or peeled, never RCE'd or 209 // Aligned, may be missing it's pre-loop. 210 int is_normal_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Normal; } 211 int is_pre_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Pre; } 212 int is_main_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Main; } 213 int is_post_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Post; } 214 int is_reduction_loop() const { return (_loop_flags&HasReductions) == HasReductions; } 215 int has_passed_slp () const { return (_loop_flags&PassedSlpAnalysis) == PassedSlpAnalysis; } 216 int is_main_no_pre_loop() const { return _loop_flags & MainHasNoPreLoop; } 217 void set_main_no_pre_loop() { _loop_flags |= MainHasNoPreLoop; } 218 219 int main_idx() const { return _main_idx; } 220 221 222 void set_pre_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; } 223 void set_main_loop ( ) { assert(is_normal_loop(),""); _loop_flags |= Main; } 224 void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; } 225 void set_normal_loop( ) { _loop_flags &= ~PreMainPostFlagsMask; } 226 227 void set_trip_count(uint tc) { _trip_count = tc; } 228 uint trip_count() { return _trip_count; } 229 230 bool has_exact_trip_count() const { return (_loop_flags & HasExactTripCount) != 0; } 231 void set_exact_trip_count(uint tc) { 232 _trip_count = tc; 233 _loop_flags |= HasExactTripCount; 234 } 235 void set_nonexact_trip_count() { 236 _loop_flags &= ~HasExactTripCount; 237 } 238 239 void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; } 240 float profile_trip_cnt() { return _profile_trip_cnt; } 241 242 void double_unrolled_count() { _unrolled_count_log2++; } 243 int unrolled_count() { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); } 244 245 void set_node_count_before_unroll(int ct) { _node_count_before_unroll = ct; } 246 int node_count_before_unroll() { return _node_count_before_unroll; } 247 void set_slp_max_unroll(int unroll_factor) { _slp_maximum_unroll_factor = unroll_factor; } 248 int slp_max_unroll() const { return _slp_maximum_unroll_factor; } 249 250 #ifndef PRODUCT 251 virtual void dump_spec(outputStream *st) const; 252 #endif 253 }; 254 255 //------------------------------CountedLoopEndNode----------------------------- 256 // CountedLoopEndNodes end simple trip counted loops. They act much like 257 // IfNodes. 258 class CountedLoopEndNode : public IfNode { 259 public: 260 enum { TestControl, TestValue }; 261 262 CountedLoopEndNode( Node *control, Node *test, float prob, float cnt ) 263 : IfNode( control, test, prob, cnt) { 264 init_class_id(Class_CountedLoopEnd); 265 } 266 virtual int Opcode() const; 267 268 Node *cmp_node() const { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : NULL; } 269 Node *incr() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; } 270 Node *limit() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; } 271 Node *stride() const { Node *tmp = incr (); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; } 272 Node *phi() const { Node *tmp = incr (); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; } 273 Node *init_trip() const { Node *tmp = phi (); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; } 274 int stride_con() const; 275 bool stride_is_con() const { Node *tmp = stride (); return (tmp != NULL && tmp->is_Con()); } 276 BoolTest::mask test_trip() const { return in(TestValue)->as_Bool()->_test._test; } 277 CountedLoopNode *loopnode() const { 278 // The CountedLoopNode that goes with this CountedLoopEndNode may 279 // have been optimized out by the IGVN so be cautious with the 280 // pattern matching on the graph 281 if (phi() == NULL) { 282 return NULL; 283 } 284 Node *ln = phi()->in(0); 285 if (ln->is_CountedLoop() && ln->as_CountedLoop()->loopexit() == this) { 286 return (CountedLoopNode*)ln; 287 } 288 return NULL; 289 } 290 291 #ifndef PRODUCT 292 virtual void dump_spec(outputStream *st) const; 293 #endif 294 }; 295 296 297 inline CountedLoopEndNode *CountedLoopNode::loopexit() const { 298 Node *bc = back_control(); 299 if( bc == NULL ) return NULL; 300 Node *le = bc->in(0); 301 if( le->Opcode() != Op_CountedLoopEnd ) 302 return NULL; 303 return (CountedLoopEndNode*)le; 304 } 305 inline Node *CountedLoopNode::init_trip() const { return loopexit() ? loopexit()->init_trip() : NULL; } 306 inline Node *CountedLoopNode::stride() const { return loopexit() ? loopexit()->stride() : NULL; } 307 inline int CountedLoopNode::stride_con() const { return loopexit() ? loopexit()->stride_con() : 0; } 308 inline bool CountedLoopNode::stride_is_con() const { return loopexit() && loopexit()->stride_is_con(); } 309 inline Node *CountedLoopNode::limit() const { return loopexit() ? loopexit()->limit() : NULL; } 310 inline Node *CountedLoopNode::incr() const { return loopexit() ? loopexit()->incr() : NULL; } 311 inline Node *CountedLoopNode::phi() const { return loopexit() ? loopexit()->phi() : NULL; } 312 313 //------------------------------LoopLimitNode----------------------------- 314 // Counted Loop limit node which represents exact final iterator value: 315 // trip_count = (limit - init_trip + stride - 1)/stride 316 // final_value= trip_count * stride + init_trip. 317 // Use HW instructions to calculate it when it can overflow in integer. 318 // Note, final_value should fit into integer since counted loop has 319 // limit check: limit <= max_int-stride. 320 class LoopLimitNode : public Node { 321 enum { Init=1, Limit=2, Stride=3 }; 322 public: 323 LoopLimitNode( Compile* C, Node *init, Node *limit, Node *stride ) : Node(0,init,limit,stride) { 324 // Put it on the Macro nodes list to optimize during macro nodes expansion. 325 init_flags(Flag_is_macro); 326 C->add_macro_node(this); 327 } 328 virtual int Opcode() const; 329 virtual const Type *bottom_type() const { return TypeInt::INT; } 330 virtual uint ideal_reg() const { return Op_RegI; } 331 virtual const Type *Value( PhaseTransform *phase ) const; 332 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); 333 virtual Node *Identity( PhaseTransform *phase ); 334 }; 335 336 // -----------------------------IdealLoopTree---------------------------------- 337 class IdealLoopTree : public ResourceObj { 338 public: 339 IdealLoopTree *_parent; // Parent in loop tree 340 IdealLoopTree *_next; // Next sibling in loop tree 341 IdealLoopTree *_child; // First child in loop tree 342 343 // The head-tail backedge defines the loop. 344 // If tail is NULL then this loop has multiple backedges as part of the 345 // same loop. During cleanup I'll peel off the multiple backedges; merge 346 // them at the loop bottom and flow 1 real backedge into the loop. 347 Node *_head; // Head of loop 348 Node *_tail; // Tail of loop 349 inline Node *tail(); // Handle lazy update of _tail field 350 PhaseIdealLoop* _phase; 351 int _local_loop_unroll_limit; 352 int _local_loop_unroll_factor; 353 354 Node_List _body; // Loop body for inner loops 355 356 uint8_t _nest; // Nesting depth 357 uint8_t _irreducible:1, // True if irreducible 358 _has_call:1, // True if has call safepoint 359 _has_sfpt:1, // True if has non-call safepoint 360 _rce_candidate:1; // True if candidate for range check elimination 361 362 Node_List* _safepts; // List of safepoints in this loop 363 Node_List* _required_safept; // A inner loop cannot delete these safepts; 364 bool _allow_optimizations; // Allow loop optimizations 365 366 IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail ) 367 : _parent(0), _next(0), _child(0), 368 _head(head), _tail(tail), 369 _phase(phase), 370 _safepts(NULL), 371 _required_safept(NULL), 372 _allow_optimizations(true), 373 _nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0), 374 _local_loop_unroll_limit(0), _local_loop_unroll_factor(0) 375 { } 376 377 // Is 'l' a member of 'this'? 378 int is_member( const IdealLoopTree *l ) const; // Test for nested membership 379 380 // Set loop nesting depth. Accumulate has_call bits. 381 int set_nest( uint depth ); 382 383 // Split out multiple fall-in edges from the loop header. Move them to a 384 // private RegionNode before the loop. This becomes the loop landing pad. 385 void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ); 386 387 // Split out the outermost loop from this shared header. 388 void split_outer_loop( PhaseIdealLoop *phase ); 389 390 // Merge all the backedges from the shared header into a private Region. 391 // Feed that region as the one backedge to this loop. 392 void merge_many_backedges( PhaseIdealLoop *phase ); 393 394 // Split shared headers and insert loop landing pads. 395 // Insert a LoopNode to replace the RegionNode. 396 // Returns TRUE if loop tree is structurally changed. 397 bool beautify_loops( PhaseIdealLoop *phase ); 398 399 // Perform optimization to use the loop predicates for null checks and range checks. 400 // Applies to any loop level (not just the innermost one) 401 bool loop_predication( PhaseIdealLoop *phase); 402 403 // Perform iteration-splitting on inner loops. Split iterations to 404 // avoid range checks or one-shot null checks. Returns false if the 405 // current round of loop opts should stop. 406 bool iteration_split( PhaseIdealLoop *phase, Node_List &old_new ); 407 408 // Driver for various flavors of iteration splitting. Returns false 409 // if the current round of loop opts should stop. 410 bool iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new ); 411 412 // Given dominators, try to find loops with calls that must always be 413 // executed (call dominates loop tail). These loops do not need non-call 414 // safepoints (ncsfpt). 415 void check_safepts(VectorSet &visited, Node_List &stack); 416 417 // Allpaths backwards scan from loop tail, terminating each path at first safepoint 418 // encountered. 419 void allpaths_check_safepts(VectorSet &visited, Node_List &stack); 420 421 // Convert to counted loops where possible 422 void counted_loop( PhaseIdealLoop *phase ); 423 424 // Check for Node being a loop-breaking test 425 Node *is_loop_exit(Node *iff) const; 426 427 // Returns true if ctrl is executed on every complete iteration 428 bool dominates_backedge(Node* ctrl); 429 430 // Remove simplistic dead code from loop body 431 void DCE_loop_body(); 432 433 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage. 434 // Replace with a 1-in-10 exit guess. 435 void adjust_loop_exit_prob( PhaseIdealLoop *phase ); 436 437 // Return TRUE or FALSE if the loop should never be RCE'd or aligned. 438 // Useful for unrolling loops with NO array accesses. 439 bool policy_peel_only( PhaseIdealLoop *phase ) const; 440 441 // Return TRUE or FALSE if the loop should be unswitched -- clone 442 // loop with an invariant test 443 bool policy_unswitching( PhaseIdealLoop *phase ) const; 444 445 // Micro-benchmark spamming. Remove empty loops. 446 bool policy_do_remove_empty_loop( PhaseIdealLoop *phase ); 447 448 // Convert one iteration loop into normal code. 449 bool policy_do_one_iteration_loop( PhaseIdealLoop *phase ); 450 451 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can 452 // make some loop-invariant test (usually a null-check) happen before the 453 // loop. 454 bool policy_peeling( PhaseIdealLoop *phase ) const; 455 456 // Return TRUE or FALSE if the loop should be maximally unrolled. Stash any 457 // known trip count in the counted loop node. 458 bool policy_maximally_unroll( PhaseIdealLoop *phase ) const; 459 460 // Return TRUE or FALSE if the loop should be unrolled or not. Unroll if 461 // the loop is a CountedLoop and the body is small enough. 462 bool policy_unroll(PhaseIdealLoop *phase); 463 464 // Loop analyses to map to a maximal superword unrolling for vectorization. 465 void policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_ct); 466 467 // Return TRUE or FALSE if the loop should be range-check-eliminated. 468 // Gather a list of IF tests that are dominated by iteration splitting; 469 // also gather the end of the first split and the start of the 2nd split. 470 bool policy_range_check( PhaseIdealLoop *phase ) const; 471 472 // Return TRUE or FALSE if the loop should be cache-line aligned. 473 // Gather the expression that does the alignment. Note that only 474 // one array base can be aligned in a loop (unless the VM guarantees 475 // mutual alignment). Note that if we vectorize short memory ops 476 // into longer memory ops, we may want to increase alignment. 477 bool policy_align( PhaseIdealLoop *phase ) const; 478 479 // Return TRUE if "iff" is a range check. 480 bool is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const; 481 482 // Compute loop exact trip count if possible 483 void compute_exact_trip_count( PhaseIdealLoop *phase ); 484 485 // Compute loop trip count from profile data 486 void compute_profile_trip_cnt( PhaseIdealLoop *phase ); 487 488 // Reassociate invariant expressions. 489 void reassociate_invariants(PhaseIdealLoop *phase); 490 // Reassociate invariant add and subtract expressions. 491 Node* reassociate_add_sub(Node* n1, PhaseIdealLoop *phase); 492 // Return nonzero index of invariant operand if invariant and variant 493 // are combined with an Add or Sub. Helper for reassociate_invariants. 494 int is_invariant_addition(Node* n, PhaseIdealLoop *phase); 495 496 // Return true if n is invariant 497 bool is_invariant(Node* n) const; 498 499 // Put loop body on igvn work list 500 void record_for_igvn(); 501 502 bool is_loop() { return !_irreducible && _tail && !_tail->is_top(); } 503 bool is_inner() { return is_loop() && _child == NULL; } 504 bool is_counted() { return is_loop() && _head != NULL && _head->is_CountedLoop(); } 505 506 #ifndef PRODUCT 507 void dump_head( ) const; // Dump loop head only 508 void dump() const; // Dump this loop recursively 509 void verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const; 510 #endif 511 512 }; 513 514 // -----------------------------PhaseIdealLoop--------------------------------- 515 // Computes the mapping from Nodes to IdealLoopTrees. Organizes IdealLoopTrees into a 516 // loop tree. Drives the loop-based transformations on the ideal graph. 517 class PhaseIdealLoop : public PhaseTransform { 518 friend class IdealLoopTree; 519 friend class SuperWord; 520 // Pre-computed def-use info 521 PhaseIterGVN &_igvn; 522 523 // Head of loop tree 524 IdealLoopTree *_ltree_root; 525 526 // Array of pre-order numbers, plus post-visited bit. 527 // ZERO for not pre-visited. EVEN for pre-visited but not post-visited. 528 // ODD for post-visited. Other bits are the pre-order number. 529 uint *_preorders; 530 uint _max_preorder; 531 532 const PhaseIdealLoop* _verify_me; 533 bool _verify_only; 534 535 // Allocate _preorders[] array 536 void allocate_preorders() { 537 _max_preorder = C->unique()+8; 538 _preorders = NEW_RESOURCE_ARRAY(uint, _max_preorder); 539 memset(_preorders, 0, sizeof(uint) * _max_preorder); 540 } 541 542 // Allocate _preorders[] array 543 void reallocate_preorders() { 544 if ( _max_preorder < C->unique() ) { 545 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique()); 546 _max_preorder = C->unique(); 547 } 548 memset(_preorders, 0, sizeof(uint) * _max_preorder); 549 } 550 551 // Check to grow _preorders[] array for the case when build_loop_tree_impl() 552 // adds new nodes. 553 void check_grow_preorders( ) { 554 if ( _max_preorder < C->unique() ) { 555 uint newsize = _max_preorder<<1; // double size of array 556 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize); 557 memset(&_preorders[_max_preorder],0,sizeof(uint)*(newsize-_max_preorder)); 558 _max_preorder = newsize; 559 } 560 } 561 // Check for pre-visited. Zero for NOT visited; non-zero for visited. 562 int is_visited( Node *n ) const { return _preorders[n->_idx]; } 563 // Pre-order numbers are written to the Nodes array as low-bit-set values. 564 void set_preorder_visited( Node *n, int pre_order ) { 565 assert( !is_visited( n ), "already set" ); 566 _preorders[n->_idx] = (pre_order<<1); 567 }; 568 // Return pre-order number. 569 int get_preorder( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]>>1; } 570 571 // Check for being post-visited. 572 // Should be previsited already (checked with assert(is_visited(n))). 573 int is_postvisited( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]&1; } 574 575 // Mark as post visited 576 void set_postvisited( Node *n ) { assert( !is_postvisited( n ), "" ); _preorders[n->_idx] |= 1; } 577 578 // Set/get control node out. Set lower bit to distinguish from IdealLoopTree 579 // Returns true if "n" is a data node, false if it's a control node. 580 bool has_ctrl( Node *n ) const { return ((intptr_t)_nodes[n->_idx]) & 1; } 581 582 // clear out dead code after build_loop_late 583 Node_List _deadlist; 584 585 // Support for faster execution of get_late_ctrl()/dom_lca() 586 // when a node has many uses and dominator depth is deep. 587 Node_Array _dom_lca_tags; 588 void init_dom_lca_tags(); 589 void clear_dom_lca_tags(); 590 591 // Helper for debugging bad dominance relationships 592 bool verify_dominance(Node* n, Node* use, Node* LCA, Node* early); 593 594 Node* compute_lca_of_uses(Node* n, Node* early, bool verify = false); 595 596 // Inline wrapper for frequent cases: 597 // 1) only one use 598 // 2) a use is the same as the current LCA passed as 'n1' 599 Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) { 600 assert( n->is_CFG(), "" ); 601 // Fast-path NULL lca 602 if( lca != NULL && lca != n ) { 603 assert( lca->is_CFG(), "" ); 604 // find LCA of all uses 605 n = dom_lca_for_get_late_ctrl_internal( lca, n, tag ); 606 } 607 return find_non_split_ctrl(n); 608 } 609 Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag ); 610 611 // Helper function for directing control inputs away from CFG split 612 // points. 613 Node *find_non_split_ctrl( Node *ctrl ) const { 614 if (ctrl != NULL) { 615 if (ctrl->is_MultiBranch()) { 616 ctrl = ctrl->in(0); 617 } 618 assert(ctrl->is_CFG(), "CFG"); 619 } 620 return ctrl; 621 } 622 623 bool cast_incr_before_loop(Node* incr, Node* ctrl, Node* loop); 624 625 public: 626 bool has_node( Node* n ) const { 627 guarantee(n != NULL, "No Node."); 628 return _nodes[n->_idx] != NULL; 629 } 630 // check if transform created new nodes that need _ctrl recorded 631 Node *get_late_ctrl( Node *n, Node *early ); 632 Node *get_early_ctrl( Node *n ); 633 Node *get_early_ctrl_for_expensive(Node *n, Node* earliest); 634 void set_early_ctrl( Node *n ); 635 void set_subtree_ctrl( Node *root ); 636 void set_ctrl( Node *n, Node *ctrl ) { 637 assert( !has_node(n) || has_ctrl(n), "" ); 638 assert( ctrl->in(0), "cannot set dead control node" ); 639 assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" ); 640 _nodes.map( n->_idx, (Node*)((intptr_t)ctrl + 1) ); 641 } 642 // Set control and update loop membership 643 void set_ctrl_and_loop(Node* n, Node* ctrl) { 644 IdealLoopTree* old_loop = get_loop(get_ctrl(n)); 645 IdealLoopTree* new_loop = get_loop(ctrl); 646 if (old_loop != new_loop) { 647 if (old_loop->_child == NULL) old_loop->_body.yank(n); 648 if (new_loop->_child == NULL) new_loop->_body.push(n); 649 } 650 set_ctrl(n, ctrl); 651 } 652 // Control nodes can be replaced or subsumed. During this pass they 653 // get their replacement Node in slot 1. Instead of updating the block 654 // location of all Nodes in the subsumed block, we lazily do it. As we 655 // pull such a subsumed block out of the array, we write back the final 656 // correct block. 657 Node *get_ctrl( Node *i ) { 658 assert(has_node(i), ""); 659 Node *n = get_ctrl_no_update(i); 660 _nodes.map( i->_idx, (Node*)((intptr_t)n + 1) ); 661 assert(has_node(i) && has_ctrl(i), ""); 662 assert(n == find_non_split_ctrl(n), "must return legal ctrl" ); 663 return n; 664 } 665 // true if CFG node d dominates CFG node n 666 bool is_dominator(Node *d, Node *n); 667 // return get_ctrl for a data node and self(n) for a CFG node 668 Node* ctrl_or_self(Node* n) { 669 if (has_ctrl(n)) 670 return get_ctrl(n); 671 else { 672 assert (n->is_CFG(), "must be a CFG node"); 673 return n; 674 } 675 } 676 677 private: 678 Node *get_ctrl_no_update( Node *i ) const { 679 assert( has_ctrl(i), "" ); 680 Node *n = (Node*)(((intptr_t)_nodes[i->_idx]) & ~1); 681 if (!n->in(0)) { 682 // Skip dead CFG nodes 683 do { 684 n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1); 685 } while (!n->in(0)); 686 n = find_non_split_ctrl(n); 687 } 688 return n; 689 } 690 691 // Check for loop being set 692 // "n" must be a control node. Returns true if "n" is known to be in a loop. 693 bool has_loop( Node *n ) const { 694 assert(!has_node(n) || !has_ctrl(n), ""); 695 return has_node(n); 696 } 697 // Set loop 698 void set_loop( Node *n, IdealLoopTree *loop ) { 699 _nodes.map(n->_idx, (Node*)loop); 700 } 701 // Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms. Replace 702 // the 'old_node' with 'new_node'. Kill old-node. Add a reference 703 // from old_node to new_node to support the lazy update. Reference 704 // replaces loop reference, since that is not needed for dead node. 705 public: 706 void lazy_update( Node *old_node, Node *new_node ) { 707 assert( old_node != new_node, "no cycles please" ); 708 //old_node->set_req( 1, new_node /*NO DU INFO*/ ); 709 // Nodes always have DU info now, so re-use the side array slot 710 // for this node to provide the forwarding pointer. 711 _nodes.map( old_node->_idx, (Node*)((intptr_t)new_node + 1) ); 712 } 713 void lazy_replace( Node *old_node, Node *new_node ) { 714 _igvn.replace_node( old_node, new_node ); 715 lazy_update( old_node, new_node ); 716 } 717 void lazy_replace_proj( Node *old_node, Node *new_node ) { 718 assert( old_node->req() == 1, "use this for Projs" ); 719 _igvn.hash_delete(old_node); // Must hash-delete before hacking edges 720 old_node->add_req( NULL ); 721 lazy_replace( old_node, new_node ); 722 } 723 724 private: 725 726 // Place 'n' in some loop nest, where 'n' is a CFG node 727 void build_loop_tree(); 728 int build_loop_tree_impl( Node *n, int pre_order ); 729 // Insert loop into the existing loop tree. 'innermost' is a leaf of the 730 // loop tree, not the root. 731 IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost ); 732 733 // Place Data nodes in some loop nest 734 void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ); 735 void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ); 736 void build_loop_late_post ( Node* n ); 737 738 // Array of immediate dominance info for each CFG node indexed by node idx 739 private: 740 uint _idom_size; 741 Node **_idom; // Array of immediate dominators 742 uint *_dom_depth; // Used for fast LCA test 743 GrowableArray<uint>* _dom_stk; // For recomputation of dom depth 744 745 Node* idom_no_update(Node* d) const { 746 assert(d->_idx < _idom_size, "oob"); 747 Node* n = _idom[d->_idx]; 748 assert(n != NULL,"Bad immediate dominator info."); 749 while (n->in(0) == NULL) { // Skip dead CFG nodes 750 //n = n->in(1); 751 n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1); 752 assert(n != NULL,"Bad immediate dominator info."); 753 } 754 return n; 755 } 756 Node *idom(Node* d) const { 757 uint didx = d->_idx; 758 Node *n = idom_no_update(d); 759 _idom[didx] = n; // Lazily remove dead CFG nodes from table. 760 return n; 761 } 762 uint dom_depth(Node* d) const { 763 guarantee(d != NULL, "Null dominator info."); 764 guarantee(d->_idx < _idom_size, ""); 765 return _dom_depth[d->_idx]; 766 } 767 void set_idom(Node* d, Node* n, uint dom_depth); 768 // Locally compute IDOM using dom_lca call 769 Node *compute_idom( Node *region ) const; 770 // Recompute dom_depth 771 void recompute_dom_depth(); 772 773 // Is safept not required by an outer loop? 774 bool is_deleteable_safept(Node* sfpt); 775 776 // Replace parallel induction variable (parallel to trip counter) 777 void replace_parallel_iv(IdealLoopTree *loop); 778 779 // Perform verification that the graph is valid. 780 PhaseIdealLoop( PhaseIterGVN &igvn) : 781 PhaseTransform(Ideal_Loop), 782 _igvn(igvn), 783 _dom_lca_tags(arena()), // Thread::resource_area 784 _verify_me(NULL), 785 _verify_only(true) { 786 build_and_optimize(false, false); 787 } 788 789 // build the loop tree and perform any requested optimizations 790 void build_and_optimize(bool do_split_if, bool skip_loop_opts); 791 792 public: 793 // Dominators for the sea of nodes 794 void Dominators(); 795 Node *dom_lca( Node *n1, Node *n2 ) const { 796 return find_non_split_ctrl(dom_lca_internal(n1, n2)); 797 } 798 Node *dom_lca_internal( Node *n1, Node *n2 ) const; 799 800 // Compute the Ideal Node to Loop mapping 801 PhaseIdealLoop( PhaseIterGVN &igvn, bool do_split_ifs, bool skip_loop_opts = false) : 802 PhaseTransform(Ideal_Loop), 803 _igvn(igvn), 804 _dom_lca_tags(arena()), // Thread::resource_area 805 _verify_me(NULL), 806 _verify_only(false) { 807 build_and_optimize(do_split_ifs, skip_loop_opts); 808 } 809 810 // Verify that verify_me made the same decisions as a fresh run. 811 PhaseIdealLoop( PhaseIterGVN &igvn, const PhaseIdealLoop *verify_me) : 812 PhaseTransform(Ideal_Loop), 813 _igvn(igvn), 814 _dom_lca_tags(arena()), // Thread::resource_area 815 _verify_me(verify_me), 816 _verify_only(false) { 817 build_and_optimize(false, false); 818 } 819 820 // Build and verify the loop tree without modifying the graph. This 821 // is useful to verify that all inputs properly dominate their uses. 822 static void verify(PhaseIterGVN& igvn) { 823 #ifdef ASSERT 824 PhaseIdealLoop v(igvn); 825 #endif 826 } 827 828 // True if the method has at least 1 irreducible loop 829 bool _has_irreducible_loops; 830 831 // Per-Node transform 832 virtual Node *transform( Node *a_node ) { return 0; } 833 834 bool is_counted_loop( Node *x, IdealLoopTree *loop ); 835 836 Node* exact_limit( IdealLoopTree *loop ); 837 838 // Return a post-walked LoopNode 839 IdealLoopTree *get_loop( Node *n ) const { 840 // Dead nodes have no loop, so return the top level loop instead 841 if (!has_node(n)) return _ltree_root; 842 assert(!has_ctrl(n), ""); 843 return (IdealLoopTree*)_nodes[n->_idx]; 844 } 845 846 // Is 'n' a (nested) member of 'loop'? 847 int is_member( const IdealLoopTree *loop, Node *n ) const { 848 return loop->is_member(get_loop(n)); } 849 850 // This is the basic building block of the loop optimizations. It clones an 851 // entire loop body. It makes an old_new loop body mapping; with this 852 // mapping you can find the new-loop equivalent to an old-loop node. All 853 // new-loop nodes are exactly equal to their old-loop counterparts, all 854 // edges are the same. All exits from the old-loop now have a RegionNode 855 // that merges the equivalent new-loop path. This is true even for the 856 // normal "loop-exit" condition. All uses of loop-invariant old-loop values 857 // now come from (one or more) Phis that merge their new-loop equivalents. 858 // Parameter side_by_side_idom: 859 // When side_by_size_idom is NULL, the dominator tree is constructed for 860 // the clone loop to dominate the original. Used in construction of 861 // pre-main-post loop sequence. 862 // When nonnull, the clone and original are side-by-side, both are 863 // dominated by the passed in side_by_side_idom node. Used in 864 // construction of unswitched loops. 865 void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth, 866 Node* side_by_side_idom = NULL); 867 868 // If we got the effect of peeling, either by actually peeling or by 869 // making a pre-loop which must execute at least once, we can remove 870 // all loop-invariant dominated tests in the main body. 871 void peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new ); 872 873 // Generate code to do a loop peel for the given loop (and body). 874 // old_new is a temp array. 875 void do_peeling( IdealLoopTree *loop, Node_List &old_new ); 876 877 // Add pre and post loops around the given loop. These loops are used 878 // during RCE, unrolling and aligning loops. 879 void insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only ); 880 // If Node n lives in the back_ctrl block, we clone a private version of n 881 // in preheader_ctrl block and return that, otherwise return n. 882 Node *clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones ); 883 884 // Take steps to maximally unroll the loop. Peel any odd iterations, then 885 // unroll to do double iterations. The next round of major loop transforms 886 // will repeat till the doubled loop body does all remaining iterations in 1 887 // pass. 888 void do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new ); 889 890 // Unroll the loop body one step - make each trip do 2 iterations. 891 void do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip ); 892 893 // Mark vector reduction candidates before loop unrolling 894 void mark_reductions( IdealLoopTree *loop ); 895 896 // Return true if exp is a constant times an induction var 897 bool is_scaled_iv(Node* exp, Node* iv, int* p_scale); 898 899 // Return true if exp is a scaled induction var plus (or minus) constant 900 bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth = 0); 901 902 // Create a new if above the uncommon_trap_if_pattern for the predicate to be promoted 903 ProjNode* create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry, 904 Deoptimization::DeoptReason reason); 905 void register_control(Node* n, IdealLoopTree *loop, Node* pred); 906 907 // Clone loop predicates to cloned loops (peeled, unswitched) 908 static ProjNode* clone_predicate(ProjNode* predicate_proj, Node* new_entry, 909 Deoptimization::DeoptReason reason, 910 PhaseIdealLoop* loop_phase, 911 PhaseIterGVN* igvn); 912 913 static Node* clone_loop_predicates(Node* old_entry, Node* new_entry, 914 bool clone_limit_check, 915 PhaseIdealLoop* loop_phase, 916 PhaseIterGVN* igvn); 917 Node* clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check); 918 919 static Node* skip_loop_predicates(Node* entry); 920 921 // Find a good location to insert a predicate 922 static ProjNode* find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason); 923 // Find a predicate 924 static Node* find_predicate(Node* entry); 925 // Construct a range check for a predicate if 926 BoolNode* rc_predicate(IdealLoopTree *loop, Node* ctrl, 927 int scale, Node* offset, 928 Node* init, Node* limit, Node* stride, 929 Node* range, bool upper); 930 931 // Implementation of the loop predication to promote checks outside the loop 932 bool loop_predication_impl(IdealLoopTree *loop); 933 934 // Helper function to collect predicate for eliminating the useless ones 935 void collect_potentially_useful_predicates(IdealLoopTree *loop, Unique_Node_List &predicate_opaque1); 936 void eliminate_useless_predicates(); 937 938 // Change the control input of expensive nodes to allow commoning by 939 // IGVN when it is guaranteed to not result in a more frequent 940 // execution of the expensive node. Return true if progress. 941 bool process_expensive_nodes(); 942 943 // Check whether node has become unreachable 944 bool is_node_unreachable(Node *n) const { 945 return !has_node(n) || n->is_unreachable(_igvn); 946 } 947 948 // Eliminate range-checks and other trip-counter vs loop-invariant tests. 949 void do_range_check( IdealLoopTree *loop, Node_List &old_new ); 950 951 // Create a slow version of the loop by cloning the loop 952 // and inserting an if to select fast-slow versions. 953 ProjNode* create_slow_version_of_loop(IdealLoopTree *loop, 954 Node_List &old_new); 955 956 // Clone loop with an invariant test (that does not exit) and 957 // insert a clone of the test that selects which version to 958 // execute. 959 void do_unswitching (IdealLoopTree *loop, Node_List &old_new); 960 961 // Find candidate "if" for unswitching 962 IfNode* find_unswitching_candidate(const IdealLoopTree *loop) const; 963 964 // Range Check Elimination uses this function! 965 // Constrain the main loop iterations so the affine function: 966 // low_limit <= scale_con * I + offset < upper_limit 967 // always holds true. That is, either increase the number of iterations in 968 // the pre-loop or the post-loop until the condition holds true in the main 969 // loop. Scale_con, offset and limit are all loop invariant. 970 void add_constraint( int stride_con, int scale_con, Node *offset, Node *low_limit, Node *upper_limit, Node *pre_ctrl, Node **pre_limit, Node **main_limit ); 971 // Helper function for add_constraint(). 972 Node* adjust_limit( int stride_con, Node * scale, Node *offset, Node *rc_limit, Node *loop_limit, Node *pre_ctrl ); 973 974 // Partially peel loop up through last_peel node. 975 bool partial_peel( IdealLoopTree *loop, Node_List &old_new ); 976 977 // Create a scheduled list of nodes control dependent on ctrl set. 978 void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched ); 979 // Has a use in the vector set 980 bool has_use_in_set( Node* n, VectorSet& vset ); 981 // Has use internal to the vector set (ie. not in a phi at the loop head) 982 bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ); 983 // clone "n" for uses that are outside of loop 984 int clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ); 985 // clone "n" for special uses that are in the not_peeled region 986 void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n, 987 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ); 988 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist 989 void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ); 990 #ifdef ASSERT 991 // Validate the loop partition sets: peel and not_peel 992 bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel ); 993 // Ensure that uses outside of loop are of the right form 994 bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list, 995 uint orig_exit_idx, uint clone_exit_idx); 996 bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx); 997 #endif 998 999 // Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.) 1000 int stride_of_possible_iv( Node* iff ); 1001 bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; } 1002 // Return the (unique) control output node that's in the loop (if it exists.) 1003 Node* stay_in_loop( Node* n, IdealLoopTree *loop); 1004 // Insert a signed compare loop exit cloned from an unsigned compare. 1005 IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop); 1006 void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop); 1007 // Utility to register node "n" with PhaseIdealLoop 1008 void register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth); 1009 // Utility to create an if-projection 1010 ProjNode* proj_clone(ProjNode* p, IfNode* iff); 1011 // Force the iff control output to be the live_proj 1012 Node* short_circuit_if(IfNode* iff, ProjNode* live_proj); 1013 // Insert a region before an if projection 1014 RegionNode* insert_region_before_proj(ProjNode* proj); 1015 // Insert a new if before an if projection 1016 ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj); 1017 1018 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps. 1019 // "Nearly" because all Nodes have been cloned from the original in the loop, 1020 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs 1021 // through the Phi recursively, and return a Bool. 1022 BoolNode *clone_iff( PhiNode *phi, IdealLoopTree *loop ); 1023 CmpNode *clone_bool( PhiNode *phi, IdealLoopTree *loop ); 1024 1025 1026 // Rework addressing expressions to get the most loop-invariant stuff 1027 // moved out. We'd like to do all associative operators, but it's especially 1028 // important (common) to do address expressions. 1029 Node *remix_address_expressions( Node *n ); 1030 1031 // Attempt to use a conditional move instead of a phi/branch 1032 Node *conditional_move( Node *n ); 1033 1034 // Reorganize offset computations to lower register pressure. 1035 // Mostly prevent loop-fallout uses of the pre-incremented trip counter 1036 // (which are then alive with the post-incremented trip counter 1037 // forcing an extra register move) 1038 void reorg_offsets( IdealLoopTree *loop ); 1039 1040 // Check for aggressive application of 'split-if' optimization, 1041 // using basic block level info. 1042 void split_if_with_blocks ( VectorSet &visited, Node_Stack &nstack ); 1043 Node *split_if_with_blocks_pre ( Node *n ); 1044 void split_if_with_blocks_post( Node *n ); 1045 Node *has_local_phi_input( Node *n ); 1046 // Mark an IfNode as being dominated by a prior test, 1047 // without actually altering the CFG (and hence IDOM info). 1048 void dominated_by( Node *prevdom, Node *iff, bool flip = false, bool exclude_loop_predicate = false ); 1049 1050 // Split Node 'n' through merge point 1051 Node *split_thru_region( Node *n, Node *region ); 1052 // Split Node 'n' through merge point if there is enough win. 1053 Node *split_thru_phi( Node *n, Node *region, int policy ); 1054 // Found an If getting its condition-code input from a Phi in the 1055 // same block. Split thru the Region. 1056 void do_split_if( Node *iff ); 1057 1058 // Conversion of fill/copy patterns into intrisic versions 1059 bool do_intrinsify_fill(); 1060 bool intrinsify_fill(IdealLoopTree* lpt); 1061 bool match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value, 1062 Node*& shift, Node*& offset); 1063 1064 private: 1065 // Return a type based on condition control flow 1066 const TypeInt* filtered_type( Node *n, Node* n_ctrl); 1067 const TypeInt* filtered_type( Node *n ) { return filtered_type(n, NULL); } 1068 // Helpers for filtered type 1069 const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl); 1070 1071 // Helper functions 1072 Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache ); 1073 Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true ); 1074 void handle_use( Node *use, Node *def, small_cache *cache, Node *region_dom, Node *new_false, Node *new_true, Node *old_false, Node *old_true ); 1075 bool split_up( Node *n, Node *blk1, Node *blk2 ); 1076 void sink_use( Node *use, Node *post_loop ); 1077 Node *place_near_use( Node *useblock ) const; 1078 1079 bool _created_loop_node; 1080 public: 1081 void set_created_loop_node() { _created_loop_node = true; } 1082 bool created_loop_node() { return _created_loop_node; } 1083 void register_new_node( Node *n, Node *blk ); 1084 1085 #ifdef ASSERT 1086 void dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA); 1087 #endif 1088 1089 #ifndef PRODUCT 1090 void dump( ) const; 1091 void dump( IdealLoopTree *loop, uint rpo_idx, Node_List &rpo_list ) const; 1092 void rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const; 1093 void verify() const; // Major slow :-) 1094 void verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const; 1095 IdealLoopTree *get_loop_idx(Node* n) const { 1096 // Dead nodes have no loop, so return the top level loop instead 1097 return _nodes[n->_idx] ? (IdealLoopTree*)_nodes[n->_idx] : _ltree_root; 1098 } 1099 // Print some stats 1100 static void print_statistics(); 1101 static int _loop_invokes; // Count of PhaseIdealLoop invokes 1102 static int _loop_work; // Sum of PhaseIdealLoop x _unique 1103 #endif 1104 }; 1105 1106 inline Node* IdealLoopTree::tail() { 1107 // Handle lazy update of _tail field 1108 Node *n = _tail; 1109 //while( !n->in(0) ) // Skip dead CFG nodes 1110 //n = n->in(1); 1111 if (n->in(0) == NULL) 1112 n = _phase->get_ctrl(n); 1113 _tail = n; 1114 return n; 1115 } 1116 1117 1118 // Iterate over the loop tree using a preorder, left-to-right traversal. 1119 // 1120 // Example that visits all counted loops from within PhaseIdealLoop 1121 // 1122 // for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) { 1123 // IdealLoopTree* lpt = iter.current(); 1124 // if (!lpt->is_counted()) continue; 1125 // ... 1126 class LoopTreeIterator : public StackObj { 1127 private: 1128 IdealLoopTree* _root; 1129 IdealLoopTree* _curnt; 1130 1131 public: 1132 LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {} 1133 1134 bool done() { return _curnt == NULL; } // Finished iterating? 1135 1136 void next(); // Advance to next loop tree 1137 1138 IdealLoopTree* current() { return _curnt; } // Return current value of iterator. 1139 }; 1140 1141 #endif // SHARE_VM_OPTO_LOOPNODE_HPP