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 WasSlpAnalyzed=256, 68 PassedSlpAnalysis=512, 69 DoUnrollOnly=1024 }; 70 char _unswitch_count; 71 enum { _unswitch_max=3 }; 72 73 public: 74 // Names for edge indices 75 enum { Self=0, EntryControl, LoopBackControl }; 76 77 int is_inner_loop() const { return _loop_flags & InnerLoop; } 78 void set_inner_loop() { _loop_flags |= InnerLoop; } 79 80 int is_partial_peel_loop() const { return _loop_flags & PartialPeelLoop; } 81 void set_partial_peel_loop() { _loop_flags |= PartialPeelLoop; } 82 int partial_peel_has_failed() const { return _loop_flags & PartialPeelFailed; } 83 void mark_partial_peel_failed() { _loop_flags |= PartialPeelFailed; } 84 void mark_has_reductions() { _loop_flags |= HasReductions; } 85 void mark_was_slp() { _loop_flags |= WasSlpAnalyzed; } 86 void mark_passed_slp() { _loop_flags |= PassedSlpAnalysis; } 87 void mark_do_unroll_only() { _loop_flags |= DoUnrollOnly; } 88 89 int unswitch_max() { return _unswitch_max; } 90 int unswitch_count() { return _unswitch_count; } 91 void set_unswitch_count(int val) { 92 assert (val <= unswitch_max(), "too many unswitches"); 93 _unswitch_count = val; 94 } 95 96 LoopNode( Node *entry, Node *backedge ) : RegionNode(3), _loop_flags(0), _unswitch_count(0) { 97 init_class_id(Class_Loop); 98 init_req(EntryControl, entry); 99 init_req(LoopBackControl, backedge); 100 } 101 102 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); 103 virtual int Opcode() const; 104 bool can_be_counted_loop(PhaseTransform* phase) const { 105 return req() == 3 && in(0) != NULL && 106 in(1) != NULL && phase->type(in(1)) != Type::TOP && 107 in(2) != NULL && phase->type(in(2)) != Type::TOP; 108 } 109 bool is_valid_counted_loop() const; 110 #ifndef PRODUCT 111 virtual void dump_spec(outputStream *st) const; 112 #endif 113 }; 114 115 //------------------------------Counted Loops---------------------------------- 116 // Counted loops are all trip-counted loops, with exactly 1 trip-counter exit 117 // path (and maybe some other exit paths). The trip-counter exit is always 118 // last in the loop. The trip-counter have to stride by a constant; 119 // the exit value is also loop invariant. 120 121 // CountedLoopNodes and CountedLoopEndNodes come in matched pairs. The 122 // CountedLoopNode has the incoming loop control and the loop-back-control 123 // which is always the IfTrue before the matching CountedLoopEndNode. The 124 // CountedLoopEndNode has an incoming control (possibly not the 125 // CountedLoopNode if there is control flow in the loop), the post-increment 126 // trip-counter value, and the limit. The trip-counter value is always of 127 // the form (Op old-trip-counter stride). The old-trip-counter is produced 128 // by a Phi connected to the CountedLoopNode. The stride is constant. 129 // The Op is any commutable opcode, including Add, Mul, Xor. The 130 // CountedLoopEndNode also takes in the loop-invariant limit value. 131 132 // From a CountedLoopNode I can reach the matching CountedLoopEndNode via the 133 // loop-back control. From CountedLoopEndNodes I can reach CountedLoopNodes 134 // via the old-trip-counter from the Op node. 135 136 //------------------------------CountedLoopNode-------------------------------- 137 // CountedLoopNodes head simple counted loops. CountedLoopNodes have as 138 // inputs the incoming loop-start control and the loop-back control, so they 139 // act like RegionNodes. They also take in the initial trip counter, the 140 // loop-invariant stride and the loop-invariant limit value. CountedLoopNodes 141 // produce a loop-body control and the trip counter value. Since 142 // CountedLoopNodes behave like RegionNodes I still have a standard CFG model. 143 144 class CountedLoopNode : public LoopNode { 145 // Size is bigger to hold _main_idx. However, _main_idx does not change 146 // the semantics so it does not appear in the hash & cmp functions. 147 virtual uint size_of() const { return sizeof(*this); } 148 149 // For Pre- and Post-loops during debugging ONLY, this holds the index of 150 // the Main CountedLoop. Used to assert that we understand the graph shape. 151 node_idx_t _main_idx; 152 153 // Known trip count calculated by compute_exact_trip_count() 154 uint _trip_count; 155 156 // Expected trip count from profile data 157 float _profile_trip_cnt; 158 159 // Log2 of original loop bodies in unrolled loop 160 int _unrolled_count_log2; 161 162 // Node count prior to last unrolling - used to decide if 163 // unroll,optimize,unroll,optimize,... is making progress 164 int _node_count_before_unroll; 165 166 // If slp analysis is performed we record the maximum 167 // vector mapped unroll factor here 168 int _slp_maximum_unroll_factor; 169 170 public: 171 CountedLoopNode( Node *entry, Node *backedge ) 172 : LoopNode(entry, backedge), _main_idx(0), _trip_count(max_juint), 173 _profile_trip_cnt(COUNT_UNKNOWN), _unrolled_count_log2(0), 174 _node_count_before_unroll(0), _slp_maximum_unroll_factor(0) { 175 init_class_id(Class_CountedLoop); 176 // Initialize _trip_count to the largest possible value. 177 // Will be reset (lower) if the loop's trip count is known. 178 } 179 180 virtual int Opcode() const; 181 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); 182 183 Node *init_control() const { return in(EntryControl); } 184 Node *back_control() const { return in(LoopBackControl); } 185 CountedLoopEndNode *loopexit() const; 186 Node *init_trip() const; 187 Node *stride() const; 188 int stride_con() const; 189 bool stride_is_con() const; 190 Node *limit() const; 191 Node *incr() const; 192 Node *phi() const; 193 194 // Match increment with optional truncation 195 static Node* match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type); 196 197 // A 'main' loop has a pre-loop and a post-loop. The 'main' loop 198 // can run short a few iterations and may start a few iterations in. 199 // It will be RCE'd and unrolled and aligned. 200 201 // A following 'post' loop will run any remaining iterations. Used 202 // during Range Check Elimination, the 'post' loop will do any final 203 // iterations with full checks. Also used by Loop Unrolling, where 204 // the 'post' loop will do any epilog iterations needed. Basically, 205 // a 'post' loop can not profitably be further unrolled or RCE'd. 206 207 // A preceding 'pre' loop will run at least 1 iteration (to do peeling), 208 // it may do under-flow checks for RCE and may do alignment iterations 209 // so the following main loop 'knows' that it is striding down cache 210 // lines. 211 212 // A 'main' loop that is ONLY unrolled or peeled, never RCE'd or 213 // Aligned, may be missing it's pre-loop. 214 int is_normal_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Normal; } 215 int is_pre_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Pre; } 216 int is_main_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Main; } 217 int is_post_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Post; } 218 int is_reduction_loop() const { return (_loop_flags&HasReductions) == HasReductions; } 219 int was_slp_analyzed () const { return (_loop_flags&WasSlpAnalyzed) == WasSlpAnalyzed; } 220 int has_passed_slp () const { return (_loop_flags&PassedSlpAnalysis) == PassedSlpAnalysis; } 221 int do_unroll_only () const { return (_loop_flags&DoUnrollOnly) == DoUnrollOnly; } 222 int is_main_no_pre_loop() const { return _loop_flags & MainHasNoPreLoop; } 223 void set_main_no_pre_loop() { _loop_flags |= MainHasNoPreLoop; } 224 225 int main_idx() const { return _main_idx; } 226 227 228 void set_pre_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; } 229 void set_main_loop ( ) { assert(is_normal_loop(),""); _loop_flags |= Main; } 230 void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; } 231 void set_normal_loop( ) { _loop_flags &= ~PreMainPostFlagsMask; } 232 233 void set_trip_count(uint tc) { _trip_count = tc; } 234 uint trip_count() { return _trip_count; } 235 236 bool has_exact_trip_count() const { return (_loop_flags & HasExactTripCount) != 0; } 237 void set_exact_trip_count(uint tc) { 238 _trip_count = tc; 239 _loop_flags |= HasExactTripCount; 240 } 241 void set_nonexact_trip_count() { 242 _loop_flags &= ~HasExactTripCount; 243 } 244 void set_notpassed_slp() { 245 _loop_flags &= ~PassedSlpAnalysis; 246 } 247 248 void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; } 249 float profile_trip_cnt() { return _profile_trip_cnt; } 250 251 void double_unrolled_count() { _unrolled_count_log2++; } 252 int unrolled_count() { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); } 253 254 void set_node_count_before_unroll(int ct) { _node_count_before_unroll = ct; } 255 int node_count_before_unroll() { return _node_count_before_unroll; } 256 void set_slp_max_unroll(int unroll_factor) { _slp_maximum_unroll_factor = unroll_factor; } 257 int slp_max_unroll() const { return _slp_maximum_unroll_factor; } 258 259 #ifndef PRODUCT 260 virtual void dump_spec(outputStream *st) const; 261 #endif 262 }; 263 264 //------------------------------CountedLoopEndNode----------------------------- 265 // CountedLoopEndNodes end simple trip counted loops. They act much like 266 // IfNodes. 267 class CountedLoopEndNode : public IfNode { 268 public: 269 enum { TestControl, TestValue }; 270 271 CountedLoopEndNode( Node *control, Node *test, float prob, float cnt ) 272 : IfNode( control, test, prob, cnt) { 273 init_class_id(Class_CountedLoopEnd); 274 } 275 virtual int Opcode() const; 276 277 Node *cmp_node() const { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : NULL; } 278 Node *incr() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; } 279 Node *limit() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; } 280 Node *stride() const { Node *tmp = incr (); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; } 281 Node *phi() const { Node *tmp = incr (); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; } 282 Node *init_trip() const { Node *tmp = phi (); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; } 283 int stride_con() const; 284 bool stride_is_con() const { Node *tmp = stride (); return (tmp != NULL && tmp->is_Con()); } 285 BoolTest::mask test_trip() const { return in(TestValue)->as_Bool()->_test._test; } 286 CountedLoopNode *loopnode() const { 287 // The CountedLoopNode that goes with this CountedLoopEndNode may 288 // have been optimized out by the IGVN so be cautious with the 289 // pattern matching on the graph 290 if (phi() == NULL) { 291 return NULL; 292 } 293 assert(phi()->is_Phi(), "should be PhiNode"); 294 Node *ln = phi()->in(0); 295 if (ln->is_CountedLoop() && ln->as_CountedLoop()->loopexit() == this) { 296 return (CountedLoopNode*)ln; 297 } 298 return NULL; 299 } 300 301 #ifndef PRODUCT 302 virtual void dump_spec(outputStream *st) const; 303 #endif 304 }; 305 306 307 inline CountedLoopEndNode *CountedLoopNode::loopexit() const { 308 Node *bc = back_control(); 309 if( bc == NULL ) return NULL; 310 Node *le = bc->in(0); 311 if( le->Opcode() != Op_CountedLoopEnd ) 312 return NULL; 313 return (CountedLoopEndNode*)le; 314 } 315 inline Node *CountedLoopNode::init_trip() const { return loopexit() ? loopexit()->init_trip() : NULL; } 316 inline Node *CountedLoopNode::stride() const { return loopexit() ? loopexit()->stride() : NULL; } 317 inline int CountedLoopNode::stride_con() const { return loopexit() ? loopexit()->stride_con() : 0; } 318 inline bool CountedLoopNode::stride_is_con() const { return loopexit() && loopexit()->stride_is_con(); } 319 inline Node *CountedLoopNode::limit() const { return loopexit() ? loopexit()->limit() : NULL; } 320 inline Node *CountedLoopNode::incr() const { return loopexit() ? loopexit()->incr() : NULL; } 321 inline Node *CountedLoopNode::phi() const { return loopexit() ? loopexit()->phi() : NULL; } 322 323 //------------------------------LoopLimitNode----------------------------- 324 // Counted Loop limit node which represents exact final iterator value: 325 // trip_count = (limit - init_trip + stride - 1)/stride 326 // final_value= trip_count * stride + init_trip. 327 // Use HW instructions to calculate it when it can overflow in integer. 328 // Note, final_value should fit into integer since counted loop has 329 // limit check: limit <= max_int-stride. 330 class LoopLimitNode : public Node { 331 enum { Init=1, Limit=2, Stride=3 }; 332 public: 333 LoopLimitNode( Compile* C, Node *init, Node *limit, Node *stride ) : Node(0,init,limit,stride) { 334 // Put it on the Macro nodes list to optimize during macro nodes expansion. 335 init_flags(Flag_is_macro); 336 C->add_macro_node(this); 337 } 338 virtual int Opcode() const; 339 virtual const Type *bottom_type() const { return TypeInt::INT; } 340 virtual uint ideal_reg() const { return Op_RegI; } 341 virtual const Type *Value( PhaseTransform *phase ) const; 342 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); 343 virtual Node *Identity( PhaseTransform *phase ); 344 }; 345 346 // -----------------------------IdealLoopTree---------------------------------- 347 class IdealLoopTree : public ResourceObj { 348 public: 349 IdealLoopTree *_parent; // Parent in loop tree 350 IdealLoopTree *_next; // Next sibling in loop tree 351 IdealLoopTree *_child; // First child in loop tree 352 353 // The head-tail backedge defines the loop. 354 // If tail is NULL then this loop has multiple backedges as part of the 355 // same loop. During cleanup I'll peel off the multiple backedges; merge 356 // them at the loop bottom and flow 1 real backedge into the loop. 357 Node *_head; // Head of loop 358 Node *_tail; // Tail of loop 359 inline Node *tail(); // Handle lazy update of _tail field 360 PhaseIdealLoop* _phase; 361 int _local_loop_unroll_limit; 362 int _local_loop_unroll_factor; 363 364 Node_List _body; // Loop body for inner loops 365 366 uint8_t _nest; // Nesting depth 367 uint8_t _irreducible:1, // True if irreducible 368 _has_call:1, // True if has call safepoint 369 _has_sfpt:1, // True if has non-call safepoint 370 _rce_candidate:1; // True if candidate for range check elimination 371 372 Node_List* _safepts; // List of safepoints in this loop 373 Node_List* _required_safept; // A inner loop cannot delete these safepts; 374 bool _allow_optimizations; // Allow loop optimizations 375 376 IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail ) 377 : _parent(0), _next(0), _child(0), 378 _head(head), _tail(tail), 379 _phase(phase), 380 _safepts(NULL), 381 _required_safept(NULL), 382 _allow_optimizations(true), 383 _nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0), 384 _local_loop_unroll_limit(0), _local_loop_unroll_factor(0) 385 { } 386 387 // Is 'l' a member of 'this'? 388 bool is_member(const IdealLoopTree *l) const; // Test for nested membership 389 390 // Set loop nesting depth. Accumulate has_call bits. 391 int set_nest( uint depth ); 392 393 // Split out multiple fall-in edges from the loop header. Move them to a 394 // private RegionNode before the loop. This becomes the loop landing pad. 395 void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ); 396 397 // Split out the outermost loop from this shared header. 398 void split_outer_loop( PhaseIdealLoop *phase ); 399 400 // Merge all the backedges from the shared header into a private Region. 401 // Feed that region as the one backedge to this loop. 402 void merge_many_backedges( PhaseIdealLoop *phase ); 403 404 // Split shared headers and insert loop landing pads. 405 // Insert a LoopNode to replace the RegionNode. 406 // Returns TRUE if loop tree is structurally changed. 407 bool beautify_loops( PhaseIdealLoop *phase ); 408 409 // Perform optimization to use the loop predicates for null checks and range checks. 410 // Applies to any loop level (not just the innermost one) 411 bool loop_predication( PhaseIdealLoop *phase); 412 413 // Perform iteration-splitting on inner loops. Split iterations to 414 // avoid range checks or one-shot null checks. Returns false if the 415 // current round of loop opts should stop. 416 bool iteration_split( PhaseIdealLoop *phase, Node_List &old_new ); 417 418 // Driver for various flavors of iteration splitting. Returns false 419 // if the current round of loop opts should stop. 420 bool iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new ); 421 422 // Given dominators, try to find loops with calls that must always be 423 // executed (call dominates loop tail). These loops do not need non-call 424 // safepoints (ncsfpt). 425 void check_safepts(VectorSet &visited, Node_List &stack); 426 427 // Allpaths backwards scan from loop tail, terminating each path at first safepoint 428 // encountered. 429 void allpaths_check_safepts(VectorSet &visited, Node_List &stack); 430 431 // Convert to counted loops where possible 432 void counted_loop( PhaseIdealLoop *phase ); 433 434 // Check for Node being a loop-breaking test 435 Node *is_loop_exit(Node *iff) const; 436 437 // Returns true if ctrl is executed on every complete iteration 438 bool dominates_backedge(Node* ctrl); 439 440 // Remove simplistic dead code from loop body 441 void DCE_loop_body(); 442 443 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage. 444 // Replace with a 1-in-10 exit guess. 445 void adjust_loop_exit_prob( PhaseIdealLoop *phase ); 446 447 // Return TRUE or FALSE if the loop should never be RCE'd or aligned. 448 // Useful for unrolling loops with NO array accesses. 449 bool policy_peel_only( PhaseIdealLoop *phase ) const; 450 451 // Return TRUE or FALSE if the loop should be unswitched -- clone 452 // loop with an invariant test 453 bool policy_unswitching( PhaseIdealLoop *phase ) const; 454 455 // Micro-benchmark spamming. Remove empty loops. 456 bool policy_do_remove_empty_loop( PhaseIdealLoop *phase ); 457 458 // Convert one iteration loop into normal code. 459 bool policy_do_one_iteration_loop( PhaseIdealLoop *phase ); 460 461 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can 462 // make some loop-invariant test (usually a null-check) happen before the 463 // loop. 464 bool policy_peeling( PhaseIdealLoop *phase ) const; 465 466 // Return TRUE or FALSE if the loop should be maximally unrolled. Stash any 467 // known trip count in the counted loop node. 468 bool policy_maximally_unroll( PhaseIdealLoop *phase ) const; 469 470 // Return TRUE or FALSE if the loop should be unrolled or not. Unroll if 471 // the loop is a CountedLoop and the body is small enough. 472 bool policy_unroll(PhaseIdealLoop *phase); 473 474 // Loop analyses to map to a maximal superword unrolling for vectorization. 475 void policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_ct); 476 477 // Return TRUE or FALSE if the loop should be range-check-eliminated. 478 // Gather a list of IF tests that are dominated by iteration splitting; 479 // also gather the end of the first split and the start of the 2nd split. 480 bool policy_range_check( PhaseIdealLoop *phase ) const; 481 482 // Return TRUE or FALSE if the loop should be cache-line aligned. 483 // Gather the expression that does the alignment. Note that only 484 // one array base can be aligned in a loop (unless the VM guarantees 485 // mutual alignment). Note that if we vectorize short memory ops 486 // into longer memory ops, we may want to increase alignment. 487 bool policy_align( PhaseIdealLoop *phase ) const; 488 489 // Return TRUE if "iff" is a range check. 490 bool is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const; 491 492 // Compute loop exact trip count if possible 493 void compute_exact_trip_count( PhaseIdealLoop *phase ); 494 495 // Compute loop trip count from profile data 496 void compute_profile_trip_cnt( PhaseIdealLoop *phase ); 497 498 // Reassociate invariant expressions. 499 void reassociate_invariants(PhaseIdealLoop *phase); 500 // Reassociate invariant add and subtract expressions. 501 Node* reassociate_add_sub(Node* n1, PhaseIdealLoop *phase); 502 // Return nonzero index of invariant operand if invariant and variant 503 // are combined with an Add or Sub. Helper for reassociate_invariants. 504 int is_invariant_addition(Node* n, PhaseIdealLoop *phase); 505 506 // Return true if n is invariant 507 bool is_invariant(Node* n) const; 508 509 // Put loop body on igvn work list 510 void record_for_igvn(); 511 512 bool is_loop() { return !_irreducible && _tail && !_tail->is_top(); } 513 bool is_inner() { return is_loop() && _child == NULL; } 514 bool is_counted() { return is_loop() && _head != NULL && _head->is_CountedLoop(); } 515 516 void remove_main_post_loops(CountedLoopNode *cl, PhaseIdealLoop *phase); 517 518 #ifndef PRODUCT 519 void dump_head( ) const; // Dump loop head only 520 void dump() const; // Dump this loop recursively 521 void verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const; 522 #endif 523 524 }; 525 526 // -----------------------------PhaseIdealLoop--------------------------------- 527 // Computes the mapping from Nodes to IdealLoopTrees. Organizes IdealLoopTrees into a 528 // loop tree. Drives the loop-based transformations on the ideal graph. 529 class PhaseIdealLoop : public PhaseTransform { 530 friend class IdealLoopTree; 531 friend class SuperWord; 532 // Pre-computed def-use info 533 PhaseIterGVN &_igvn; 534 535 // Head of loop tree 536 IdealLoopTree *_ltree_root; 537 538 // Array of pre-order numbers, plus post-visited bit. 539 // ZERO for not pre-visited. EVEN for pre-visited but not post-visited. 540 // ODD for post-visited. Other bits are the pre-order number. 541 uint *_preorders; 542 uint _max_preorder; 543 544 const PhaseIdealLoop* _verify_me; 545 bool _verify_only; 546 547 // Allocate _preorders[] array 548 void allocate_preorders() { 549 _max_preorder = C->unique()+8; 550 _preorders = NEW_RESOURCE_ARRAY(uint, _max_preorder); 551 memset(_preorders, 0, sizeof(uint) * _max_preorder); 552 } 553 554 // Allocate _preorders[] array 555 void reallocate_preorders() { 556 if ( _max_preorder < C->unique() ) { 557 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique()); 558 _max_preorder = C->unique(); 559 } 560 memset(_preorders, 0, sizeof(uint) * _max_preorder); 561 } 562 563 // Check to grow _preorders[] array for the case when build_loop_tree_impl() 564 // adds new nodes. 565 void check_grow_preorders( ) { 566 if ( _max_preorder < C->unique() ) { 567 uint newsize = _max_preorder<<1; // double size of array 568 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize); 569 memset(&_preorders[_max_preorder],0,sizeof(uint)*(newsize-_max_preorder)); 570 _max_preorder = newsize; 571 } 572 } 573 // Check for pre-visited. Zero for NOT visited; non-zero for visited. 574 int is_visited( Node *n ) const { return _preorders[n->_idx]; } 575 // Pre-order numbers are written to the Nodes array as low-bit-set values. 576 void set_preorder_visited( Node *n, int pre_order ) { 577 assert( !is_visited( n ), "already set" ); 578 _preorders[n->_idx] = (pre_order<<1); 579 }; 580 // Return pre-order number. 581 int get_preorder( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]>>1; } 582 583 // Check for being post-visited. 584 // Should be previsited already (checked with assert(is_visited(n))). 585 int is_postvisited( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]&1; } 586 587 // Mark as post visited 588 void set_postvisited( Node *n ) { assert( !is_postvisited( n ), "" ); _preorders[n->_idx] |= 1; } 589 590 // Set/get control node out. Set lower bit to distinguish from IdealLoopTree 591 // Returns true if "n" is a data node, false if it's a control node. 592 bool has_ctrl( Node *n ) const { return ((intptr_t)_nodes[n->_idx]) & 1; } 593 594 // clear out dead code after build_loop_late 595 Node_List _deadlist; 596 597 // Support for faster execution of get_late_ctrl()/dom_lca() 598 // when a node has many uses and dominator depth is deep. 599 Node_Array _dom_lca_tags; 600 void init_dom_lca_tags(); 601 void clear_dom_lca_tags(); 602 603 // Helper for debugging bad dominance relationships 604 bool verify_dominance(Node* n, Node* use, Node* LCA, Node* early); 605 606 Node* compute_lca_of_uses(Node* n, Node* early, bool verify = false); 607 608 // Inline wrapper for frequent cases: 609 // 1) only one use 610 // 2) a use is the same as the current LCA passed as 'n1' 611 Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) { 612 assert( n->is_CFG(), "" ); 613 // Fast-path NULL lca 614 if( lca != NULL && lca != n ) { 615 assert( lca->is_CFG(), "" ); 616 // find LCA of all uses 617 n = dom_lca_for_get_late_ctrl_internal( lca, n, tag ); 618 } 619 return find_non_split_ctrl(n); 620 } 621 Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag ); 622 623 // Helper function for directing control inputs away from CFG split 624 // points. 625 Node *find_non_split_ctrl( Node *ctrl ) const { 626 if (ctrl != NULL) { 627 if (ctrl->is_MultiBranch()) { 628 ctrl = ctrl->in(0); 629 } 630 assert(ctrl->is_CFG(), "CFG"); 631 } 632 return ctrl; 633 } 634 635 bool cast_incr_before_loop(Node* incr, Node* ctrl, Node* loop); 636 637 public: 638 bool has_node( Node* n ) const { 639 guarantee(n != NULL, "No Node."); 640 return _nodes[n->_idx] != NULL; 641 } 642 // check if transform created new nodes that need _ctrl recorded 643 Node *get_late_ctrl( Node *n, Node *early ); 644 Node *get_early_ctrl( Node *n ); 645 Node *get_early_ctrl_for_expensive(Node *n, Node* earliest); 646 void set_early_ctrl( Node *n ); 647 void set_subtree_ctrl( Node *root ); 648 void set_ctrl( Node *n, Node *ctrl ) { 649 assert( !has_node(n) || has_ctrl(n), "" ); 650 assert( ctrl->in(0), "cannot set dead control node" ); 651 assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" ); 652 _nodes.map( n->_idx, (Node*)((intptr_t)ctrl + 1) ); 653 } 654 // Set control and update loop membership 655 void set_ctrl_and_loop(Node* n, Node* ctrl) { 656 IdealLoopTree* old_loop = get_loop(get_ctrl(n)); 657 IdealLoopTree* new_loop = get_loop(ctrl); 658 if (old_loop != new_loop) { 659 if (old_loop->_child == NULL) old_loop->_body.yank(n); 660 if (new_loop->_child == NULL) new_loop->_body.push(n); 661 } 662 set_ctrl(n, ctrl); 663 } 664 // Control nodes can be replaced or subsumed. During this pass they 665 // get their replacement Node in slot 1. Instead of updating the block 666 // location of all Nodes in the subsumed block, we lazily do it. As we 667 // pull such a subsumed block out of the array, we write back the final 668 // correct block. 669 Node *get_ctrl( Node *i ) { 670 assert(has_node(i), ""); 671 Node *n = get_ctrl_no_update(i); 672 _nodes.map( i->_idx, (Node*)((intptr_t)n + 1) ); 673 assert(has_node(i) && has_ctrl(i), ""); 674 assert(n == find_non_split_ctrl(n), "must return legal ctrl" ); 675 return n; 676 } 677 // true if CFG node d dominates CFG node n 678 bool is_dominator(Node *d, Node *n); 679 // return get_ctrl for a data node and self(n) for a CFG node 680 Node* ctrl_or_self(Node* n) { 681 if (has_ctrl(n)) 682 return get_ctrl(n); 683 else { 684 assert (n->is_CFG(), "must be a CFG node"); 685 return n; 686 } 687 } 688 689 private: 690 Node *get_ctrl_no_update( Node *i ) const { 691 assert( has_ctrl(i), "" ); 692 Node *n = (Node*)(((intptr_t)_nodes[i->_idx]) & ~1); 693 if (!n->in(0)) { 694 // Skip dead CFG nodes 695 do { 696 n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1); 697 } while (!n->in(0)); 698 n = find_non_split_ctrl(n); 699 } 700 return n; 701 } 702 703 // Check for loop being set 704 // "n" must be a control node. Returns true if "n" is known to be in a loop. 705 bool has_loop( Node *n ) const { 706 assert(!has_node(n) || !has_ctrl(n), ""); 707 return has_node(n); 708 } 709 // Set loop 710 void set_loop( Node *n, IdealLoopTree *loop ) { 711 _nodes.map(n->_idx, (Node*)loop); 712 } 713 // Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms. Replace 714 // the 'old_node' with 'new_node'. Kill old-node. Add a reference 715 // from old_node to new_node to support the lazy update. Reference 716 // replaces loop reference, since that is not needed for dead node. 717 public: 718 void lazy_update( Node *old_node, Node *new_node ) { 719 assert( old_node != new_node, "no cycles please" ); 720 //old_node->set_req( 1, new_node /*NO DU INFO*/ ); 721 // Nodes always have DU info now, so re-use the side array slot 722 // for this node to provide the forwarding pointer. 723 _nodes.map( old_node->_idx, (Node*)((intptr_t)new_node + 1) ); 724 } 725 void lazy_replace( Node *old_node, Node *new_node ) { 726 _igvn.replace_node( old_node, new_node ); 727 lazy_update( old_node, new_node ); 728 } 729 void lazy_replace_proj( Node *old_node, Node *new_node ) { 730 assert( old_node->req() == 1, "use this for Projs" ); 731 _igvn.hash_delete(old_node); // Must hash-delete before hacking edges 732 old_node->add_req( NULL ); 733 lazy_replace( old_node, new_node ); 734 } 735 736 private: 737 738 // Place 'n' in some loop nest, where 'n' is a CFG node 739 void build_loop_tree(); 740 int build_loop_tree_impl( Node *n, int pre_order ); 741 // Insert loop into the existing loop tree. 'innermost' is a leaf of the 742 // loop tree, not the root. 743 IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost ); 744 745 // Place Data nodes in some loop nest 746 void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ); 747 void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ); 748 void build_loop_late_post ( Node* n ); 749 750 // Array of immediate dominance info for each CFG node indexed by node idx 751 private: 752 uint _idom_size; 753 Node **_idom; // Array of immediate dominators 754 uint *_dom_depth; // Used for fast LCA test 755 GrowableArray<uint>* _dom_stk; // For recomputation of dom depth 756 757 Node* idom_no_update(Node* d) const { 758 assert(d->_idx < _idom_size, "oob"); 759 Node* n = _idom[d->_idx]; 760 assert(n != NULL,"Bad immediate dominator info."); 761 while (n->in(0) == NULL) { // Skip dead CFG nodes 762 //n = n->in(1); 763 n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1); 764 assert(n != NULL,"Bad immediate dominator info."); 765 } 766 return n; 767 } 768 Node *idom(Node* d) const { 769 uint didx = d->_idx; 770 Node *n = idom_no_update(d); 771 _idom[didx] = n; // Lazily remove dead CFG nodes from table. 772 return n; 773 } 774 uint dom_depth(Node* d) const { 775 guarantee(d != NULL, "Null dominator info."); 776 guarantee(d->_idx < _idom_size, ""); 777 return _dom_depth[d->_idx]; 778 } 779 void set_idom(Node* d, Node* n, uint dom_depth); 780 // Locally compute IDOM using dom_lca call 781 Node *compute_idom( Node *region ) const; 782 // Recompute dom_depth 783 void recompute_dom_depth(); 784 785 // Is safept not required by an outer loop? 786 bool is_deleteable_safept(Node* sfpt); 787 788 // Replace parallel induction variable (parallel to trip counter) 789 void replace_parallel_iv(IdealLoopTree *loop); 790 791 // Perform verification that the graph is valid. 792 PhaseIdealLoop( PhaseIterGVN &igvn) : 793 PhaseTransform(Ideal_Loop), 794 _igvn(igvn), 795 _dom_lca_tags(arena()), // Thread::resource_area 796 _verify_me(NULL), 797 _verify_only(true) { 798 build_and_optimize(false, false); 799 } 800 801 // build the loop tree and perform any requested optimizations 802 void build_and_optimize(bool do_split_if, bool skip_loop_opts); 803 804 public: 805 // Dominators for the sea of nodes 806 void Dominators(); 807 Node *dom_lca( Node *n1, Node *n2 ) const { 808 return find_non_split_ctrl(dom_lca_internal(n1, n2)); 809 } 810 Node *dom_lca_internal( Node *n1, Node *n2 ) const; 811 812 // Compute the Ideal Node to Loop mapping 813 PhaseIdealLoop( PhaseIterGVN &igvn, bool do_split_ifs, bool skip_loop_opts = false) : 814 PhaseTransform(Ideal_Loop), 815 _igvn(igvn), 816 _dom_lca_tags(arena()), // Thread::resource_area 817 _verify_me(NULL), 818 _verify_only(false) { 819 build_and_optimize(do_split_ifs, skip_loop_opts); 820 } 821 822 // Verify that verify_me made the same decisions as a fresh run. 823 PhaseIdealLoop( PhaseIterGVN &igvn, const PhaseIdealLoop *verify_me) : 824 PhaseTransform(Ideal_Loop), 825 _igvn(igvn), 826 _dom_lca_tags(arena()), // Thread::resource_area 827 _verify_me(verify_me), 828 _verify_only(false) { 829 build_and_optimize(false, false); 830 } 831 832 // Build and verify the loop tree without modifying the graph. This 833 // is useful to verify that all inputs properly dominate their uses. 834 static void verify(PhaseIterGVN& igvn) { 835 #ifdef ASSERT 836 PhaseIdealLoop v(igvn); 837 #endif 838 } 839 840 // True if the method has at least 1 irreducible loop 841 bool _has_irreducible_loops; 842 843 // Per-Node transform 844 virtual Node *transform( Node *a_node ) { return 0; } 845 846 bool is_counted_loop( Node *x, IdealLoopTree *loop ); 847 848 Node* exact_limit( IdealLoopTree *loop ); 849 850 // Return a post-walked LoopNode 851 IdealLoopTree *get_loop( Node *n ) const { 852 // Dead nodes have no loop, so return the top level loop instead 853 if (!has_node(n)) return _ltree_root; 854 assert(!has_ctrl(n), ""); 855 return (IdealLoopTree*)_nodes[n->_idx]; 856 } 857 858 // Is 'n' a (nested) member of 'loop'? 859 int is_member( const IdealLoopTree *loop, Node *n ) const { 860 return loop->is_member(get_loop(n)); } 861 862 // This is the basic building block of the loop optimizations. It clones an 863 // entire loop body. It makes an old_new loop body mapping; with this 864 // mapping you can find the new-loop equivalent to an old-loop node. All 865 // new-loop nodes are exactly equal to their old-loop counterparts, all 866 // edges are the same. All exits from the old-loop now have a RegionNode 867 // that merges the equivalent new-loop path. This is true even for the 868 // normal "loop-exit" condition. All uses of loop-invariant old-loop values 869 // now come from (one or more) Phis that merge their new-loop equivalents. 870 // Parameter side_by_side_idom: 871 // When side_by_size_idom is NULL, the dominator tree is constructed for 872 // the clone loop to dominate the original. Used in construction of 873 // pre-main-post loop sequence. 874 // When nonnull, the clone and original are side-by-side, both are 875 // dominated by the passed in side_by_side_idom node. Used in 876 // construction of unswitched loops. 877 void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth, 878 Node* side_by_side_idom = NULL); 879 880 // If we got the effect of peeling, either by actually peeling or by 881 // making a pre-loop which must execute at least once, we can remove 882 // all loop-invariant dominated tests in the main body. 883 void peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new ); 884 885 // Generate code to do a loop peel for the given loop (and body). 886 // old_new is a temp array. 887 void do_peeling( IdealLoopTree *loop, Node_List &old_new ); 888 889 // Add pre and post loops around the given loop. These loops are used 890 // during RCE, unrolling and aligning loops. 891 void insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only ); 892 // If Node n lives in the back_ctrl block, we clone a private version of n 893 // in preheader_ctrl block and return that, otherwise return n. 894 Node *clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones ); 895 896 // Take steps to maximally unroll the loop. Peel any odd iterations, then 897 // unroll to do double iterations. The next round of major loop transforms 898 // will repeat till the doubled loop body does all remaining iterations in 1 899 // pass. 900 void do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new ); 901 902 // Unroll the loop body one step - make each trip do 2 iterations. 903 void do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip ); 904 905 // Mark vector reduction candidates before loop unrolling 906 void mark_reductions( IdealLoopTree *loop ); 907 908 // Return true if exp is a constant times an induction var 909 bool is_scaled_iv(Node* exp, Node* iv, int* p_scale); 910 911 // Return true if exp is a scaled induction var plus (or minus) constant 912 bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth = 0); 913 914 // Create a new if above the uncommon_trap_if_pattern for the predicate to be promoted 915 ProjNode* create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry, 916 Deoptimization::DeoptReason reason, 917 int opcode); 918 void register_control(Node* n, IdealLoopTree *loop, Node* pred); 919 920 // Clone loop predicates to cloned loops (peeled, unswitched) 921 static ProjNode* clone_predicate(ProjNode* predicate_proj, Node* new_entry, 922 Deoptimization::DeoptReason reason, 923 PhaseIdealLoop* loop_phase, 924 PhaseIterGVN* igvn); 925 926 static Node* clone_loop_predicates(Node* old_entry, Node* new_entry, 927 bool clone_limit_check, 928 PhaseIdealLoop* loop_phase, 929 PhaseIterGVN* igvn); 930 Node* clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check); 931 932 static Node* skip_loop_predicates(Node* entry); 933 934 // Find a good location to insert a predicate 935 static ProjNode* find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason); 936 // Find a predicate 937 static Node* find_predicate(Node* entry); 938 // Construct a range check for a predicate if 939 BoolNode* rc_predicate(IdealLoopTree *loop, Node* ctrl, 940 int scale, Node* offset, 941 Node* init, Node* limit, Node* stride, 942 Node* range, bool upper); 943 944 // Implementation of the loop predication to promote checks outside the loop 945 bool loop_predication_impl(IdealLoopTree *loop); 946 947 // Helper function to collect predicate for eliminating the useless ones 948 void collect_potentially_useful_predicates(IdealLoopTree *loop, Unique_Node_List &predicate_opaque1); 949 void eliminate_useless_predicates(); 950 951 // Change the control input of expensive nodes to allow commoning by 952 // IGVN when it is guaranteed to not result in a more frequent 953 // execution of the expensive node. Return true if progress. 954 bool process_expensive_nodes(); 955 956 // Check whether node has become unreachable 957 bool is_node_unreachable(Node *n) const { 958 return !has_node(n) || n->is_unreachable(_igvn); 959 } 960 961 // Eliminate range-checks and other trip-counter vs loop-invariant tests. 962 void do_range_check( IdealLoopTree *loop, Node_List &old_new ); 963 964 // Create a slow version of the loop by cloning the loop 965 // and inserting an if to select fast-slow versions. 966 ProjNode* create_slow_version_of_loop(IdealLoopTree *loop, 967 Node_List &old_new, 968 int opcode); 969 970 // Clone loop with an invariant test (that does not exit) and 971 // insert a clone of the test that selects which version to 972 // execute. 973 void do_unswitching (IdealLoopTree *loop, Node_List &old_new); 974 975 // Find candidate "if" for unswitching 976 IfNode* find_unswitching_candidate(const IdealLoopTree *loop) const; 977 978 // Range Check Elimination uses this function! 979 // Constrain the main loop iterations so the affine function: 980 // low_limit <= scale_con * I + offset < upper_limit 981 // always holds true. That is, either increase the number of iterations in 982 // the pre-loop or the post-loop until the condition holds true in the main 983 // loop. Scale_con, offset and limit are all loop invariant. 984 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 ); 985 // Helper function for add_constraint(). 986 Node* adjust_limit( int stride_con, Node * scale, Node *offset, Node *rc_limit, Node *loop_limit, Node *pre_ctrl ); 987 988 // Partially peel loop up through last_peel node. 989 bool partial_peel( IdealLoopTree *loop, Node_List &old_new ); 990 991 // Create a scheduled list of nodes control dependent on ctrl set. 992 void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched ); 993 // Has a use in the vector set 994 bool has_use_in_set( Node* n, VectorSet& vset ); 995 // Has use internal to the vector set (ie. not in a phi at the loop head) 996 bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ); 997 // clone "n" for uses that are outside of loop 998 int clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ); 999 // clone "n" for special uses that are in the not_peeled region 1000 void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n, 1001 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ); 1002 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist 1003 void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ); 1004 #ifdef ASSERT 1005 // Validate the loop partition sets: peel and not_peel 1006 bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel ); 1007 // Ensure that uses outside of loop are of the right form 1008 bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list, 1009 uint orig_exit_idx, uint clone_exit_idx); 1010 bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx); 1011 #endif 1012 1013 // Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.) 1014 int stride_of_possible_iv( Node* iff ); 1015 bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; } 1016 // Return the (unique) control output node that's in the loop (if it exists.) 1017 Node* stay_in_loop( Node* n, IdealLoopTree *loop); 1018 // Insert a signed compare loop exit cloned from an unsigned compare. 1019 IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop); 1020 void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop); 1021 // Utility to register node "n" with PhaseIdealLoop 1022 void register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth); 1023 // Utility to create an if-projection 1024 ProjNode* proj_clone(ProjNode* p, IfNode* iff); 1025 // Force the iff control output to be the live_proj 1026 Node* short_circuit_if(IfNode* iff, ProjNode* live_proj); 1027 // Insert a region before an if projection 1028 RegionNode* insert_region_before_proj(ProjNode* proj); 1029 // Insert a new if before an if projection 1030 ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj); 1031 1032 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps. 1033 // "Nearly" because all Nodes have been cloned from the original in the loop, 1034 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs 1035 // through the Phi recursively, and return a Bool. 1036 BoolNode *clone_iff( PhiNode *phi, IdealLoopTree *loop ); 1037 CmpNode *clone_bool( PhiNode *phi, IdealLoopTree *loop ); 1038 1039 1040 // Rework addressing expressions to get the most loop-invariant stuff 1041 // moved out. We'd like to do all associative operators, but it's especially 1042 // important (common) to do address expressions. 1043 Node *remix_address_expressions( Node *n ); 1044 1045 // Attempt to use a conditional move instead of a phi/branch 1046 Node *conditional_move( Node *n ); 1047 1048 // Reorganize offset computations to lower register pressure. 1049 // Mostly prevent loop-fallout uses of the pre-incremented trip counter 1050 // (which are then alive with the post-incremented trip counter 1051 // forcing an extra register move) 1052 void reorg_offsets( IdealLoopTree *loop ); 1053 1054 // Check for aggressive application of 'split-if' optimization, 1055 // using basic block level info. 1056 void split_if_with_blocks ( VectorSet &visited, Node_Stack &nstack ); 1057 Node *split_if_with_blocks_pre ( Node *n ); 1058 void split_if_with_blocks_post( Node *n ); 1059 Node *has_local_phi_input( Node *n ); 1060 // Mark an IfNode as being dominated by a prior test, 1061 // without actually altering the CFG (and hence IDOM info). 1062 void dominated_by( Node *prevdom, Node *iff, bool flip = false, bool exclude_loop_predicate = false ); 1063 1064 // Split Node 'n' through merge point 1065 Node *split_thru_region( Node *n, Node *region ); 1066 // Split Node 'n' through merge point if there is enough win. 1067 Node *split_thru_phi( Node *n, Node *region, int policy ); 1068 // Found an If getting its condition-code input from a Phi in the 1069 // same block. Split thru the Region. 1070 void do_split_if( Node *iff ); 1071 1072 // Conversion of fill/copy patterns into intrisic versions 1073 bool do_intrinsify_fill(); 1074 bool intrinsify_fill(IdealLoopTree* lpt); 1075 bool match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value, 1076 Node*& shift, Node*& offset); 1077 1078 private: 1079 // Return a type based on condition control flow 1080 const TypeInt* filtered_type( Node *n, Node* n_ctrl); 1081 const TypeInt* filtered_type( Node *n ) { return filtered_type(n, NULL); } 1082 // Helpers for filtered type 1083 const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl); 1084 1085 // Helper functions 1086 Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache ); 1087 Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true ); 1088 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 ); 1089 bool split_up( Node *n, Node *blk1, Node *blk2 ); 1090 void sink_use( Node *use, Node *post_loop ); 1091 Node *place_near_use( Node *useblock ) const; 1092 Node* try_move_store_before_loop(Node* n, Node *n_ctrl); 1093 void try_move_store_after_loop(Node* n); 1094 1095 bool _created_loop_node; 1096 public: 1097 void set_created_loop_node() { _created_loop_node = true; } 1098 bool created_loop_node() { return _created_loop_node; } 1099 void register_new_node( Node *n, Node *blk ); 1100 1101 #ifdef ASSERT 1102 void dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA); 1103 #endif 1104 1105 #ifndef PRODUCT 1106 void dump( ) const; 1107 void dump( IdealLoopTree *loop, uint rpo_idx, Node_List &rpo_list ) const; 1108 void rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const; 1109 void verify() const; // Major slow :-) 1110 void verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const; 1111 IdealLoopTree *get_loop_idx(Node* n) const { 1112 // Dead nodes have no loop, so return the top level loop instead 1113 return _nodes[n->_idx] ? (IdealLoopTree*)_nodes[n->_idx] : _ltree_root; 1114 } 1115 // Print some stats 1116 static void print_statistics(); 1117 static int _loop_invokes; // Count of PhaseIdealLoop invokes 1118 static int _loop_work; // Sum of PhaseIdealLoop x _unique 1119 #endif 1120 }; 1121 1122 inline Node* IdealLoopTree::tail() { 1123 // Handle lazy update of _tail field 1124 Node *n = _tail; 1125 //while( !n->in(0) ) // Skip dead CFG nodes 1126 //n = n->in(1); 1127 if (n->in(0) == NULL) 1128 n = _phase->get_ctrl(n); 1129 _tail = n; 1130 return n; 1131 } 1132 1133 1134 // Iterate over the loop tree using a preorder, left-to-right traversal. 1135 // 1136 // Example that visits all counted loops from within PhaseIdealLoop 1137 // 1138 // for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) { 1139 // IdealLoopTree* lpt = iter.current(); 1140 // if (!lpt->is_counted()) continue; 1141 // ... 1142 class LoopTreeIterator : public StackObj { 1143 private: 1144 IdealLoopTree* _root; 1145 IdealLoopTree* _curnt; 1146 1147 public: 1148 LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {} 1149 1150 bool done() { return _curnt == NULL; } // Finished iterating? 1151 1152 void next(); // Advance to next loop tree 1153 1154 IdealLoopTree* current() { return _curnt; } // Return current value of iterator. 1155 }; 1156 1157 #endif // SHARE_VM_OPTO_LOOPNODE_HPP