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 CountedLoopReserveKit; 42 class VectorSet; 43 class Invariance; 44 struct small_cache; 45 46 // 47 // I D E A L I Z E D L O O P S 48 // 49 // Idealized loops are the set of loops I perform more interesting 50 // transformations on, beyond simple hoisting. 51 52 //------------------------------LoopNode--------------------------------------- 53 // Simple loop header. Fall in path on left, loop-back path on right. 54 class LoopNode : public RegionNode { 55 // Size is bigger to hold the flags. However, the flags do not change 56 // the semantics so it does not appear in the hash & cmp functions. 57 virtual uint size_of() const { return sizeof(*this); } 58 protected: 59 short _loop_flags; 60 // Names for flag bitfields 61 enum { Normal=0, Pre=1, Main=2, Post=3, PreMainPostFlagsMask=3, 62 MainHasNoPreLoop=4, 63 HasExactTripCount=8, 64 InnerLoop=16, 65 PartialPeelLoop=32, 66 PartialPeelFailed=64, 67 HasReductions=128, 68 WasSlpAnalyzed=256, 69 PassedSlpAnalysis=512, 70 DoUnrollOnly=1024 }; 71 char _unswitch_count; 72 enum { _unswitch_max=3 }; 73 74 public: 75 // Names for edge indices 76 enum { Self=0, EntryControl, LoopBackControl }; 77 78 int is_inner_loop() const { return _loop_flags & InnerLoop; } 79 void set_inner_loop() { _loop_flags |= InnerLoop; } 80 81 int is_partial_peel_loop() const { return _loop_flags & PartialPeelLoop; } 82 void set_partial_peel_loop() { _loop_flags |= PartialPeelLoop; } 83 int partial_peel_has_failed() const { return _loop_flags & PartialPeelFailed; } 84 void mark_partial_peel_failed() { _loop_flags |= PartialPeelFailed; } 85 void mark_has_reductions() { _loop_flags |= HasReductions; } 86 void mark_was_slp() { _loop_flags |= WasSlpAnalyzed; } 87 void mark_passed_slp() { _loop_flags |= PassedSlpAnalysis; } 88 void mark_do_unroll_only() { _loop_flags |= DoUnrollOnly; } 89 90 int unswitch_max() { return _unswitch_max; } 91 int unswitch_count() { return _unswitch_count; } 92 void set_unswitch_count(int val) { 93 assert (val <= unswitch_max(), "too many unswitches"); 94 _unswitch_count = val; 95 } 96 97 LoopNode( Node *entry, Node *backedge ) : RegionNode(3), _loop_flags(0), _unswitch_count(0) { 98 init_class_id(Class_Loop); 99 init_req(EntryControl, entry); 100 init_req(LoopBackControl, backedge); 101 } 102 103 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); 104 virtual int Opcode() const; 105 bool can_be_counted_loop(PhaseTransform* phase) const { 106 return req() == 3 && in(0) != NULL && 107 in(1) != NULL && phase->type(in(1)) != Type::TOP && 108 in(2) != NULL && phase->type(in(2)) != Type::TOP; 109 } 110 bool is_valid_counted_loop() const; 111 #ifndef PRODUCT 112 virtual void dump_spec(outputStream *st) const; 113 #endif 114 }; 115 116 //------------------------------Counted Loops---------------------------------- 117 // Counted loops are all trip-counted loops, with exactly 1 trip-counter exit 118 // path (and maybe some other exit paths). The trip-counter exit is always 119 // last in the loop. The trip-counter have to stride by a constant; 120 // the exit value is also loop invariant. 121 122 // CountedLoopNodes and CountedLoopEndNodes come in matched pairs. The 123 // CountedLoopNode has the incoming loop control and the loop-back-control 124 // which is always the IfTrue before the matching CountedLoopEndNode. The 125 // CountedLoopEndNode has an incoming control (possibly not the 126 // CountedLoopNode if there is control flow in the loop), the post-increment 127 // trip-counter value, and the limit. The trip-counter value is always of 128 // the form (Op old-trip-counter stride). The old-trip-counter is produced 129 // by a Phi connected to the CountedLoopNode. The stride is constant. 130 // The Op is any commutable opcode, including Add, Mul, Xor. The 131 // CountedLoopEndNode also takes in the loop-invariant limit value. 132 133 // From a CountedLoopNode I can reach the matching CountedLoopEndNode via the 134 // loop-back control. From CountedLoopEndNodes I can reach CountedLoopNodes 135 // via the old-trip-counter from the Op node. 136 137 //------------------------------CountedLoopNode-------------------------------- 138 // CountedLoopNodes head simple counted loops. CountedLoopNodes have as 139 // inputs the incoming loop-start control and the loop-back control, so they 140 // act like RegionNodes. They also take in the initial trip counter, the 141 // loop-invariant stride and the loop-invariant limit value. CountedLoopNodes 142 // produce a loop-body control and the trip counter value. Since 143 // CountedLoopNodes behave like RegionNodes I still have a standard CFG model. 144 145 class CountedLoopNode : public LoopNode { 146 // Size is bigger to hold _main_idx. However, _main_idx does not change 147 // the semantics so it does not appear in the hash & cmp functions. 148 virtual uint size_of() const { return sizeof(*this); } 149 150 // For Pre- and Post-loops during debugging ONLY, this holds the index of 151 // the Main CountedLoop. Used to assert that we understand the graph shape. 152 node_idx_t _main_idx; 153 154 // Known trip count calculated by compute_exact_trip_count() 155 uint _trip_count; 156 157 // Expected trip count from profile data 158 float _profile_trip_cnt; 159 160 // Log2 of original loop bodies in unrolled loop 161 int _unrolled_count_log2; 162 163 // Node count prior to last unrolling - used to decide if 164 // unroll,optimize,unroll,optimize,... is making progress 165 int _node_count_before_unroll; 166 167 // If slp analysis is performed we record the maximum 168 // vector mapped unroll factor here 169 int _slp_maximum_unroll_factor; 170 171 public: 172 CountedLoopNode( Node *entry, Node *backedge ) 173 : LoopNode(entry, backedge), _main_idx(0), _trip_count(max_juint), 174 _profile_trip_cnt(COUNT_UNKNOWN), _unrolled_count_log2(0), 175 _node_count_before_unroll(0), _slp_maximum_unroll_factor(0) { 176 init_class_id(Class_CountedLoop); 177 // Initialize _trip_count to the largest possible value. 178 // Will be reset (lower) if the loop's trip count is known. 179 } 180 181 virtual int Opcode() const; 182 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); 183 184 Node *init_control() const { return in(EntryControl); } 185 Node *back_control() const { return in(LoopBackControl); } 186 CountedLoopEndNode *loopexit() const; 187 Node *init_trip() const; 188 Node *stride() const; 189 int stride_con() const; 190 bool stride_is_con() const; 191 Node *limit() const; 192 Node *incr() const; 193 Node *phi() const; 194 195 // Match increment with optional truncation 196 static Node* match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type); 197 198 // A 'main' loop has a pre-loop and a post-loop. The 'main' loop 199 // can run short a few iterations and may start a few iterations in. 200 // It will be RCE'd and unrolled and aligned. 201 202 // A following 'post' loop will run any remaining iterations. Used 203 // during Range Check Elimination, the 'post' loop will do any final 204 // iterations with full checks. Also used by Loop Unrolling, where 205 // the 'post' loop will do any epilog iterations needed. Basically, 206 // a 'post' loop can not profitably be further unrolled or RCE'd. 207 208 // A preceding 'pre' loop will run at least 1 iteration (to do peeling), 209 // it may do under-flow checks for RCE and may do alignment iterations 210 // so the following main loop 'knows' that it is striding down cache 211 // lines. 212 213 // A 'main' loop that is ONLY unrolled or peeled, never RCE'd or 214 // Aligned, may be missing it's pre-loop. 215 int is_normal_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Normal; } 216 int is_pre_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Pre; } 217 int is_main_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Main; } 218 int is_post_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Post; } 219 int is_reduction_loop() const { return (_loop_flags&HasReductions) == HasReductions; } 220 int was_slp_analyzed () const { return (_loop_flags&WasSlpAnalyzed) == WasSlpAnalyzed; } 221 int has_passed_slp () const { return (_loop_flags&PassedSlpAnalysis) == PassedSlpAnalysis; } 222 int do_unroll_only () const { return (_loop_flags&DoUnrollOnly) == DoUnrollOnly; } 223 int is_main_no_pre_loop() const { return _loop_flags & MainHasNoPreLoop; } 224 void set_main_no_pre_loop() { _loop_flags |= MainHasNoPreLoop; } 225 226 int main_idx() const { return _main_idx; } 227 228 229 void set_pre_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; } 230 void set_main_loop ( ) { assert(is_normal_loop(),""); _loop_flags |= Main; } 231 void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; } 232 void set_normal_loop( ) { _loop_flags &= ~PreMainPostFlagsMask; } 233 234 void set_trip_count(uint tc) { _trip_count = tc; } 235 uint trip_count() { return _trip_count; } 236 237 bool has_exact_trip_count() const { return (_loop_flags & HasExactTripCount) != 0; } 238 void set_exact_trip_count(uint tc) { 239 _trip_count = tc; 240 _loop_flags |= HasExactTripCount; 241 } 242 void set_nonexact_trip_count() { 243 _loop_flags &= ~HasExactTripCount; 244 } 245 void set_notpassed_slp() { 246 _loop_flags &= ~PassedSlpAnalysis; 247 } 248 249 void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; } 250 float profile_trip_cnt() { return _profile_trip_cnt; } 251 252 void double_unrolled_count() { _unrolled_count_log2++; } 253 int unrolled_count() { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); } 254 255 void set_node_count_before_unroll(int ct) { _node_count_before_unroll = ct; } 256 int node_count_before_unroll() { return _node_count_before_unroll; } 257 void set_slp_max_unroll(int unroll_factor) { _slp_maximum_unroll_factor = unroll_factor; } 258 int slp_max_unroll() const { return _slp_maximum_unroll_factor; } 259 260 #ifndef PRODUCT 261 virtual void dump_spec(outputStream *st) const; 262 #endif 263 }; 264 265 //------------------------------CountedLoopEndNode----------------------------- 266 // CountedLoopEndNodes end simple trip counted loops. They act much like 267 // IfNodes. 268 class CountedLoopEndNode : public IfNode { 269 public: 270 enum { TestControl, TestValue }; 271 272 CountedLoopEndNode( Node *control, Node *test, float prob, float cnt ) 273 : IfNode( control, test, prob, cnt) { 274 init_class_id(Class_CountedLoopEnd); 275 } 276 virtual int Opcode() const; 277 278 Node *cmp_node() const { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : NULL; } 279 Node *incr() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; } 280 Node *limit() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; } 281 Node *stride() const { Node *tmp = incr (); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; } 282 Node *phi() const { Node *tmp = incr (); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; } 283 Node *init_trip() const { Node *tmp = phi (); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; } 284 int stride_con() const; 285 bool stride_is_con() const { Node *tmp = stride (); return (tmp != NULL && tmp->is_Con()); } 286 BoolTest::mask test_trip() const { return in(TestValue)->as_Bool()->_test._test; } 287 CountedLoopNode *loopnode() const { 288 // The CountedLoopNode that goes with this CountedLoopEndNode may 289 // have been optimized out by the IGVN so be cautious with the 290 // pattern matching on the graph 291 if (phi() == NULL) { 292 return NULL; 293 } 294 assert(phi()->is_Phi(), "should be PhiNode"); 295 Node *ln = phi()->in(0); 296 if (ln->is_CountedLoop() && ln->as_CountedLoop()->loopexit() == this) { 297 return (CountedLoopNode*)ln; 298 } 299 return NULL; 300 } 301 302 #ifndef PRODUCT 303 virtual void dump_spec(outputStream *st) const; 304 #endif 305 }; 306 307 308 inline CountedLoopEndNode *CountedLoopNode::loopexit() const { 309 Node *bc = back_control(); 310 if( bc == NULL ) return NULL; 311 Node *le = bc->in(0); 312 if( le->Opcode() != Op_CountedLoopEnd ) 313 return NULL; 314 return (CountedLoopEndNode*)le; 315 } 316 inline Node *CountedLoopNode::init_trip() const { return loopexit() ? loopexit()->init_trip() : NULL; } 317 inline Node *CountedLoopNode::stride() const { return loopexit() ? loopexit()->stride() : NULL; } 318 inline int CountedLoopNode::stride_con() const { return loopexit() ? loopexit()->stride_con() : 0; } 319 inline bool CountedLoopNode::stride_is_con() const { return loopexit() && loopexit()->stride_is_con(); } 320 inline Node *CountedLoopNode::limit() const { return loopexit() ? loopexit()->limit() : NULL; } 321 inline Node *CountedLoopNode::incr() const { return loopexit() ? loopexit()->incr() : NULL; } 322 inline Node *CountedLoopNode::phi() const { return loopexit() ? loopexit()->phi() : NULL; } 323 324 //------------------------------LoopLimitNode----------------------------- 325 // Counted Loop limit node which represents exact final iterator value: 326 // trip_count = (limit - init_trip + stride - 1)/stride 327 // final_value= trip_count * stride + init_trip. 328 // Use HW instructions to calculate it when it can overflow in integer. 329 // Note, final_value should fit into integer since counted loop has 330 // limit check: limit <= max_int-stride. 331 class LoopLimitNode : public Node { 332 enum { Init=1, Limit=2, Stride=3 }; 333 public: 334 LoopLimitNode( Compile* C, Node *init, Node *limit, Node *stride ) : Node(0,init,limit,stride) { 335 // Put it on the Macro nodes list to optimize during macro nodes expansion. 336 init_flags(Flag_is_macro); 337 C->add_macro_node(this); 338 } 339 virtual int Opcode() const; 340 virtual const Type *bottom_type() const { return TypeInt::INT; } 341 virtual uint ideal_reg() const { return Op_RegI; } 342 virtual const Type *Value( PhaseTransform *phase ) const; 343 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); 344 virtual Node *Identity( PhaseTransform *phase ); 345 }; 346 347 // -----------------------------IdealLoopTree---------------------------------- 348 class IdealLoopTree : public ResourceObj { 349 public: 350 IdealLoopTree *_parent; // Parent in loop tree 351 IdealLoopTree *_next; // Next sibling in loop tree 352 IdealLoopTree *_child; // First child in loop tree 353 354 // The head-tail backedge defines the loop. 355 // If tail is NULL then this loop has multiple backedges as part of the 356 // same loop. During cleanup I'll peel off the multiple backedges; merge 357 // them at the loop bottom and flow 1 real backedge into the loop. 358 Node *_head; // Head of loop 359 Node *_tail; // Tail of loop 360 inline Node *tail(); // Handle lazy update of _tail field 361 PhaseIdealLoop* _phase; 362 int _local_loop_unroll_limit; 363 int _local_loop_unroll_factor; 364 365 Node_List _body; // Loop body for inner loops 366 367 uint8_t _nest; // Nesting depth 368 uint8_t _irreducible:1, // True if irreducible 369 _has_call:1, // True if has call safepoint 370 _has_sfpt:1, // True if has non-call safepoint 371 _rce_candidate:1; // True if candidate for range check elimination 372 373 Node_List* _safepts; // List of safepoints in this loop 374 Node_List* _required_safept; // A inner loop cannot delete these safepts; 375 bool _allow_optimizations; // Allow loop optimizations 376 377 IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail ) 378 : _parent(0), _next(0), _child(0), 379 _head(head), _tail(tail), 380 _phase(phase), 381 _safepts(NULL), 382 _required_safept(NULL), 383 _allow_optimizations(true), 384 _nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0), 385 _local_loop_unroll_limit(0), _local_loop_unroll_factor(0) 386 { } 387 388 // Is 'l' a member of 'this'? 389 bool is_member(const IdealLoopTree *l) const; // Test for nested membership 390 391 // Set loop nesting depth. Accumulate has_call bits. 392 int set_nest( uint depth ); 393 394 // Split out multiple fall-in edges from the loop header. Move them to a 395 // private RegionNode before the loop. This becomes the loop landing pad. 396 void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ); 397 398 // Split out the outermost loop from this shared header. 399 void split_outer_loop( PhaseIdealLoop *phase ); 400 401 // Merge all the backedges from the shared header into a private Region. 402 // Feed that region as the one backedge to this loop. 403 void merge_many_backedges( PhaseIdealLoop *phase ); 404 405 // Split shared headers and insert loop landing pads. 406 // Insert a LoopNode to replace the RegionNode. 407 // Returns TRUE if loop tree is structurally changed. 408 bool beautify_loops( PhaseIdealLoop *phase ); 409 410 // Perform optimization to use the loop predicates for null checks and range checks. 411 // Applies to any loop level (not just the innermost one) 412 bool loop_predication( PhaseIdealLoop *phase); 413 414 // Perform iteration-splitting on inner loops. Split iterations to 415 // avoid range checks or one-shot null checks. Returns false if the 416 // current round of loop opts should stop. 417 bool iteration_split( PhaseIdealLoop *phase, Node_List &old_new ); 418 419 // Driver for various flavors of iteration splitting. Returns false 420 // if the current round of loop opts should stop. 421 bool iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new ); 422 423 // Given dominators, try to find loops with calls that must always be 424 // executed (call dominates loop tail). These loops do not need non-call 425 // safepoints (ncsfpt). 426 void check_safepts(VectorSet &visited, Node_List &stack); 427 428 // Allpaths backwards scan from loop tail, terminating each path at first safepoint 429 // encountered. 430 void allpaths_check_safepts(VectorSet &visited, Node_List &stack); 431 432 // Convert to counted loops where possible 433 void counted_loop( PhaseIdealLoop *phase ); 434 435 // Check for Node being a loop-breaking test 436 Node *is_loop_exit(Node *iff) const; 437 438 // Returns true if ctrl is executed on every complete iteration 439 bool dominates_backedge(Node* ctrl); 440 441 // Remove simplistic dead code from loop body 442 void DCE_loop_body(); 443 444 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage. 445 // Replace with a 1-in-10 exit guess. 446 void adjust_loop_exit_prob( PhaseIdealLoop *phase ); 447 448 // Return TRUE or FALSE if the loop should never be RCE'd or aligned. 449 // Useful for unrolling loops with NO array accesses. 450 bool policy_peel_only( PhaseIdealLoop *phase ) const; 451 452 // Return TRUE or FALSE if the loop should be unswitched -- clone 453 // loop with an invariant test 454 bool policy_unswitching( PhaseIdealLoop *phase ) const; 455 456 // Micro-benchmark spamming. Remove empty loops. 457 bool policy_do_remove_empty_loop( PhaseIdealLoop *phase ); 458 459 // Convert one iteration loop into normal code. 460 bool policy_do_one_iteration_loop( PhaseIdealLoop *phase ); 461 462 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can 463 // make some loop-invariant test (usually a null-check) happen before the 464 // loop. 465 bool policy_peeling( PhaseIdealLoop *phase ) const; 466 467 // Return TRUE or FALSE if the loop should be maximally unrolled. Stash any 468 // known trip count in the counted loop node. 469 bool policy_maximally_unroll( PhaseIdealLoop *phase ) const; 470 471 // Return TRUE or FALSE if the loop should be unrolled or not. Unroll if 472 // the loop is a CountedLoop and the body is small enough. 473 bool policy_unroll(PhaseIdealLoop *phase); 474 475 // Loop analyses to map to a maximal superword unrolling for vectorization. 476 void policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_ct); 477 478 // Return TRUE or FALSE if the loop should be range-check-eliminated. 479 // Gather a list of IF tests that are dominated by iteration splitting; 480 // also gather the end of the first split and the start of the 2nd split. 481 bool policy_range_check( PhaseIdealLoop *phase ) const; 482 483 // Return TRUE or FALSE if the loop should be cache-line aligned. 484 // Gather the expression that does the alignment. Note that only 485 // one array base can be aligned in a loop (unless the VM guarantees 486 // mutual alignment). Note that if we vectorize short memory ops 487 // into longer memory ops, we may want to increase alignment. 488 bool policy_align( PhaseIdealLoop *phase ) const; 489 490 // Return TRUE if "iff" is a range check. 491 bool is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const; 492 493 // Compute loop exact trip count if possible 494 void compute_exact_trip_count( PhaseIdealLoop *phase ); 495 496 // Compute loop trip count from profile data 497 void compute_profile_trip_cnt( PhaseIdealLoop *phase ); 498 499 // Reassociate invariant expressions. 500 void reassociate_invariants(PhaseIdealLoop *phase); 501 // Reassociate invariant add and subtract expressions. 502 Node* reassociate_add_sub(Node* n1, PhaseIdealLoop *phase); 503 // Return nonzero index of invariant operand if invariant and variant 504 // are combined with an Add or Sub. Helper for reassociate_invariants. 505 int is_invariant_addition(Node* n, PhaseIdealLoop *phase); 506 507 // Return true if n is invariant 508 bool is_invariant(Node* n) const; 509 510 // Put loop body on igvn work list 511 void record_for_igvn(); 512 513 bool is_loop() { return !_irreducible && _tail && !_tail->is_top(); } 514 bool is_inner() { return is_loop() && _child == NULL; } 515 bool is_counted() { return is_loop() && _head != NULL && _head->is_CountedLoop(); } 516 517 void remove_main_post_loops(CountedLoopNode *cl, PhaseIdealLoop *phase); 518 519 #ifndef PRODUCT 520 void dump_head( ) const; // Dump loop head only 521 void dump() const; // Dump this loop recursively 522 void verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const; 523 #endif 524 525 }; 526 527 // -----------------------------PhaseIdealLoop--------------------------------- 528 // Computes the mapping from Nodes to IdealLoopTrees. Organizes IdealLoopTrees into a 529 // loop tree. Drives the loop-based transformations on the ideal graph. 530 class PhaseIdealLoop : public PhaseTransform { 531 friend class IdealLoopTree; 532 friend class SuperWord; 533 friend class CountedLoopReserveKit; 534 535 // Pre-computed def-use info 536 PhaseIterGVN &_igvn; 537 538 // Head of loop tree 539 IdealLoopTree *_ltree_root; 540 541 // Array of pre-order numbers, plus post-visited bit. 542 // ZERO for not pre-visited. EVEN for pre-visited but not post-visited. 543 // ODD for post-visited. Other bits are the pre-order number. 544 uint *_preorders; 545 uint _max_preorder; 546 547 const PhaseIdealLoop* _verify_me; 548 bool _verify_only; 549 550 // Allocate _preorders[] array 551 void allocate_preorders() { 552 _max_preorder = C->unique()+8; 553 _preorders = NEW_RESOURCE_ARRAY(uint, _max_preorder); 554 memset(_preorders, 0, sizeof(uint) * _max_preorder); 555 } 556 557 // Allocate _preorders[] array 558 void reallocate_preorders() { 559 if ( _max_preorder < C->unique() ) { 560 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique()); 561 _max_preorder = C->unique(); 562 } 563 memset(_preorders, 0, sizeof(uint) * _max_preorder); 564 } 565 566 // Check to grow _preorders[] array for the case when build_loop_tree_impl() 567 // adds new nodes. 568 void check_grow_preorders( ) { 569 if ( _max_preorder < C->unique() ) { 570 uint newsize = _max_preorder<<1; // double size of array 571 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize); 572 memset(&_preorders[_max_preorder],0,sizeof(uint)*(newsize-_max_preorder)); 573 _max_preorder = newsize; 574 } 575 } 576 // Check for pre-visited. Zero for NOT visited; non-zero for visited. 577 int is_visited( Node *n ) const { return _preorders[n->_idx]; } 578 // Pre-order numbers are written to the Nodes array as low-bit-set values. 579 void set_preorder_visited( Node *n, int pre_order ) { 580 assert( !is_visited( n ), "already set" ); 581 _preorders[n->_idx] = (pre_order<<1); 582 }; 583 // Return pre-order number. 584 int get_preorder( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]>>1; } 585 586 // Check for being post-visited. 587 // Should be previsited already (checked with assert(is_visited(n))). 588 int is_postvisited( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]&1; } 589 590 // Mark as post visited 591 void set_postvisited( Node *n ) { assert( !is_postvisited( n ), "" ); _preorders[n->_idx] |= 1; } 592 593 // Set/get control node out. Set lower bit to distinguish from IdealLoopTree 594 // Returns true if "n" is a data node, false if it's a control node. 595 bool has_ctrl( Node *n ) const { return ((intptr_t)_nodes[n->_idx]) & 1; } 596 597 // clear out dead code after build_loop_late 598 Node_List _deadlist; 599 600 // Support for faster execution of get_late_ctrl()/dom_lca() 601 // when a node has many uses and dominator depth is deep. 602 Node_Array _dom_lca_tags; 603 void init_dom_lca_tags(); 604 void clear_dom_lca_tags(); 605 606 // Helper for debugging bad dominance relationships 607 bool verify_dominance(Node* n, Node* use, Node* LCA, Node* early); 608 609 Node* compute_lca_of_uses(Node* n, Node* early, bool verify = false); 610 611 // Inline wrapper for frequent cases: 612 // 1) only one use 613 // 2) a use is the same as the current LCA passed as 'n1' 614 Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) { 615 assert( n->is_CFG(), "" ); 616 // Fast-path NULL lca 617 if( lca != NULL && lca != n ) { 618 assert( lca->is_CFG(), "" ); 619 // find LCA of all uses 620 n = dom_lca_for_get_late_ctrl_internal( lca, n, tag ); 621 } 622 return find_non_split_ctrl(n); 623 } 624 Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag ); 625 626 // Helper function for directing control inputs away from CFG split 627 // points. 628 Node *find_non_split_ctrl( Node *ctrl ) const { 629 if (ctrl != NULL) { 630 if (ctrl->is_MultiBranch()) { 631 ctrl = ctrl->in(0); 632 } 633 assert(ctrl->is_CFG(), "CFG"); 634 } 635 return ctrl; 636 } 637 638 bool cast_incr_before_loop(Node* incr, Node* ctrl, Node* loop); 639 640 public: 641 bool has_node( Node* n ) const { 642 guarantee(n != NULL, "No Node."); 643 return _nodes[n->_idx] != NULL; 644 } 645 // check if transform created new nodes that need _ctrl recorded 646 Node *get_late_ctrl( Node *n, Node *early ); 647 Node *get_early_ctrl( Node *n ); 648 Node *get_early_ctrl_for_expensive(Node *n, Node* earliest); 649 void set_early_ctrl( Node *n ); 650 void set_subtree_ctrl( Node *root ); 651 void set_ctrl( Node *n, Node *ctrl ) { 652 assert( !has_node(n) || has_ctrl(n), "" ); 653 assert( ctrl->in(0), "cannot set dead control node" ); 654 assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" ); 655 _nodes.map( n->_idx, (Node*)((intptr_t)ctrl + 1) ); 656 } 657 // Set control and update loop membership 658 void set_ctrl_and_loop(Node* n, Node* ctrl) { 659 IdealLoopTree* old_loop = get_loop(get_ctrl(n)); 660 IdealLoopTree* new_loop = get_loop(ctrl); 661 if (old_loop != new_loop) { 662 if (old_loop->_child == NULL) old_loop->_body.yank(n); 663 if (new_loop->_child == NULL) new_loop->_body.push(n); 664 } 665 set_ctrl(n, ctrl); 666 } 667 // Control nodes can be replaced or subsumed. During this pass they 668 // get their replacement Node in slot 1. Instead of updating the block 669 // location of all Nodes in the subsumed block, we lazily do it. As we 670 // pull such a subsumed block out of the array, we write back the final 671 // correct block. 672 Node *get_ctrl( Node *i ) { 673 assert(has_node(i), ""); 674 Node *n = get_ctrl_no_update(i); 675 _nodes.map( i->_idx, (Node*)((intptr_t)n + 1) ); 676 assert(has_node(i) && has_ctrl(i), ""); 677 assert(n == find_non_split_ctrl(n), "must return legal ctrl" ); 678 return n; 679 } 680 // true if CFG node d dominates CFG node n 681 bool is_dominator(Node *d, Node *n); 682 // return get_ctrl for a data node and self(n) for a CFG node 683 Node* ctrl_or_self(Node* n) { 684 if (has_ctrl(n)) 685 return get_ctrl(n); 686 else { 687 assert (n->is_CFG(), "must be a CFG node"); 688 return n; 689 } 690 } 691 692 private: 693 Node *get_ctrl_no_update( Node *i ) const { 694 assert( has_ctrl(i), "" ); 695 Node *n = (Node*)(((intptr_t)_nodes[i->_idx]) & ~1); 696 if (!n->in(0)) { 697 // Skip dead CFG nodes 698 do { 699 n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1); 700 } while (!n->in(0)); 701 n = find_non_split_ctrl(n); 702 } 703 return n; 704 } 705 706 // Check for loop being set 707 // "n" must be a control node. Returns true if "n" is known to be in a loop. 708 bool has_loop( Node *n ) const { 709 assert(!has_node(n) || !has_ctrl(n), ""); 710 return has_node(n); 711 } 712 // Set loop 713 void set_loop( Node *n, IdealLoopTree *loop ) { 714 _nodes.map(n->_idx, (Node*)loop); 715 } 716 // Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms. Replace 717 // the 'old_node' with 'new_node'. Kill old-node. Add a reference 718 // from old_node to new_node to support the lazy update. Reference 719 // replaces loop reference, since that is not needed for dead node. 720 public: 721 void lazy_update( Node *old_node, Node *new_node ) { 722 assert( old_node != new_node, "no cycles please" ); 723 //old_node->set_req( 1, new_node /*NO DU INFO*/ ); 724 // Nodes always have DU info now, so re-use the side array slot 725 // for this node to provide the forwarding pointer. 726 _nodes.map( old_node->_idx, (Node*)((intptr_t)new_node + 1) ); 727 } 728 void lazy_replace( Node *old_node, Node *new_node ) { 729 _igvn.replace_node( old_node, new_node ); 730 lazy_update( old_node, new_node ); 731 } 732 void lazy_replace_proj( Node *old_node, Node *new_node ) { 733 assert( old_node->req() == 1, "use this for Projs" ); 734 _igvn.hash_delete(old_node); // Must hash-delete before hacking edges 735 old_node->add_req( NULL ); 736 lazy_replace( old_node, new_node ); 737 } 738 739 private: 740 741 // Place 'n' in some loop nest, where 'n' is a CFG node 742 void build_loop_tree(); 743 int build_loop_tree_impl( Node *n, int pre_order ); 744 // Insert loop into the existing loop tree. 'innermost' is a leaf of the 745 // loop tree, not the root. 746 IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost ); 747 748 // Place Data nodes in some loop nest 749 void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ); 750 void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ); 751 void build_loop_late_post ( Node* n ); 752 753 // Array of immediate dominance info for each CFG node indexed by node idx 754 private: 755 uint _idom_size; 756 Node **_idom; // Array of immediate dominators 757 uint *_dom_depth; // Used for fast LCA test 758 GrowableArray<uint>* _dom_stk; // For recomputation of dom depth 759 760 Node* idom_no_update(Node* d) const { 761 assert(d->_idx < _idom_size, "oob"); 762 Node* n = _idom[d->_idx]; 763 assert(n != NULL,"Bad immediate dominator info."); 764 while (n->in(0) == NULL) { // Skip dead CFG nodes 765 //n = n->in(1); 766 n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1); 767 assert(n != NULL,"Bad immediate dominator info."); 768 } 769 return n; 770 } 771 Node *idom(Node* d) const { 772 uint didx = d->_idx; 773 Node *n = idom_no_update(d); 774 _idom[didx] = n; // Lazily remove dead CFG nodes from table. 775 return n; 776 } 777 uint dom_depth(Node* d) const { 778 guarantee(d != NULL, "Null dominator info."); 779 guarantee(d->_idx < _idom_size, ""); 780 return _dom_depth[d->_idx]; 781 } 782 void set_idom(Node* d, Node* n, uint dom_depth); 783 // Locally compute IDOM using dom_lca call 784 Node *compute_idom( Node *region ) const; 785 // Recompute dom_depth 786 void recompute_dom_depth(); 787 788 // Is safept not required by an outer loop? 789 bool is_deleteable_safept(Node* sfpt); 790 791 // Replace parallel induction variable (parallel to trip counter) 792 void replace_parallel_iv(IdealLoopTree *loop); 793 794 // Perform verification that the graph is valid. 795 PhaseIdealLoop( PhaseIterGVN &igvn) : 796 PhaseTransform(Ideal_Loop), 797 _igvn(igvn), 798 _dom_lca_tags(arena()), // Thread::resource_area 799 _verify_me(NULL), 800 _verify_only(true) { 801 build_and_optimize(false, false); 802 } 803 804 // build the loop tree and perform any requested optimizations 805 void build_and_optimize(bool do_split_if, bool skip_loop_opts); 806 807 public: 808 // Dominators for the sea of nodes 809 void Dominators(); 810 Node *dom_lca( Node *n1, Node *n2 ) const { 811 return find_non_split_ctrl(dom_lca_internal(n1, n2)); 812 } 813 Node *dom_lca_internal( Node *n1, Node *n2 ) const; 814 815 // Compute the Ideal Node to Loop mapping 816 PhaseIdealLoop( PhaseIterGVN &igvn, bool do_split_ifs, bool skip_loop_opts = false) : 817 PhaseTransform(Ideal_Loop), 818 _igvn(igvn), 819 _dom_lca_tags(arena()), // Thread::resource_area 820 _verify_me(NULL), 821 _verify_only(false) { 822 build_and_optimize(do_split_ifs, skip_loop_opts); 823 } 824 825 // Verify that verify_me made the same decisions as a fresh run. 826 PhaseIdealLoop( PhaseIterGVN &igvn, const PhaseIdealLoop *verify_me) : 827 PhaseTransform(Ideal_Loop), 828 _igvn(igvn), 829 _dom_lca_tags(arena()), // Thread::resource_area 830 _verify_me(verify_me), 831 _verify_only(false) { 832 build_and_optimize(false, false); 833 } 834 835 // Build and verify the loop tree without modifying the graph. This 836 // is useful to verify that all inputs properly dominate their uses. 837 static void verify(PhaseIterGVN& igvn) { 838 #ifdef ASSERT 839 PhaseIdealLoop v(igvn); 840 #endif 841 } 842 843 // True if the method has at least 1 irreducible loop 844 bool _has_irreducible_loops; 845 846 // Per-Node transform 847 virtual Node *transform( Node *a_node ) { return 0; } 848 849 bool is_counted_loop( Node *x, IdealLoopTree *loop ); 850 851 Node* exact_limit( IdealLoopTree *loop ); 852 853 // Return a post-walked LoopNode 854 IdealLoopTree *get_loop( Node *n ) const { 855 // Dead nodes have no loop, so return the top level loop instead 856 if (!has_node(n)) return _ltree_root; 857 assert(!has_ctrl(n), ""); 858 return (IdealLoopTree*)_nodes[n->_idx]; 859 } 860 861 // Is 'n' a (nested) member of 'loop'? 862 int is_member( const IdealLoopTree *loop, Node *n ) const { 863 return loop->is_member(get_loop(n)); } 864 865 // This is the basic building block of the loop optimizations. It clones an 866 // entire loop body. It makes an old_new loop body mapping; with this 867 // mapping you can find the new-loop equivalent to an old-loop node. All 868 // new-loop nodes are exactly equal to their old-loop counterparts, all 869 // edges are the same. All exits from the old-loop now have a RegionNode 870 // that merges the equivalent new-loop path. This is true even for the 871 // normal "loop-exit" condition. All uses of loop-invariant old-loop values 872 // now come from (one or more) Phis that merge their new-loop equivalents. 873 // Parameter side_by_side_idom: 874 // When side_by_size_idom is NULL, the dominator tree is constructed for 875 // the clone loop to dominate the original. Used in construction of 876 // pre-main-post loop sequence. 877 // When nonnull, the clone and original are side-by-side, both are 878 // dominated by the passed in side_by_side_idom node. Used in 879 // construction of unswitched loops. 880 void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth, 881 Node* side_by_side_idom = NULL); 882 883 // If we got the effect of peeling, either by actually peeling or by 884 // making a pre-loop which must execute at least once, we can remove 885 // all loop-invariant dominated tests in the main body. 886 void peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new ); 887 888 // Generate code to do a loop peel for the given loop (and body). 889 // old_new is a temp array. 890 void do_peeling( IdealLoopTree *loop, Node_List &old_new ); 891 892 // Add pre and post loops around the given loop. These loops are used 893 // during RCE, unrolling and aligning loops. 894 void insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only ); 895 // If Node n lives in the back_ctrl block, we clone a private version of n 896 // in preheader_ctrl block and return that, otherwise return n. 897 Node *clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones ); 898 899 // Take steps to maximally unroll the loop. Peel any odd iterations, then 900 // unroll to do double iterations. The next round of major loop transforms 901 // will repeat till the doubled loop body does all remaining iterations in 1 902 // pass. 903 void do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new ); 904 905 // Unroll the loop body one step - make each trip do 2 iterations. 906 void do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip ); 907 908 // Mark vector reduction candidates before loop unrolling 909 void mark_reductions( IdealLoopTree *loop ); 910 911 // Return true if exp is a constant times an induction var 912 bool is_scaled_iv(Node* exp, Node* iv, int* p_scale); 913 914 // Return true if exp is a scaled induction var plus (or minus) constant 915 bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth = 0); 916 917 // Create a new if above the uncommon_trap_if_pattern for the predicate to be promoted 918 ProjNode* create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry, 919 Deoptimization::DeoptReason reason, 920 int opcode); 921 void register_control(Node* n, IdealLoopTree *loop, Node* pred); 922 923 // Clone loop predicates to cloned loops (peeled, unswitched) 924 static ProjNode* clone_predicate(ProjNode* predicate_proj, Node* new_entry, 925 Deoptimization::DeoptReason reason, 926 PhaseIdealLoop* loop_phase, 927 PhaseIterGVN* igvn); 928 929 static Node* clone_loop_predicates(Node* old_entry, Node* new_entry, 930 bool clone_limit_check, 931 PhaseIdealLoop* loop_phase, 932 PhaseIterGVN* igvn); 933 Node* clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check); 934 935 static Node* skip_loop_predicates(Node* entry); 936 937 // Find a good location to insert a predicate 938 static ProjNode* find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason); 939 // Find a predicate 940 static Node* find_predicate(Node* entry); 941 // Construct a range check for a predicate if 942 BoolNode* rc_predicate(IdealLoopTree *loop, Node* ctrl, 943 int scale, Node* offset, 944 Node* init, Node* limit, Node* stride, 945 Node* range, bool upper); 946 947 // Implementation of the loop predication to promote checks outside the loop 948 bool loop_predication_impl(IdealLoopTree *loop); 949 950 // Helper function to collect predicate for eliminating the useless ones 951 void collect_potentially_useful_predicates(IdealLoopTree *loop, Unique_Node_List &predicate_opaque1); 952 void eliminate_useless_predicates(); 953 954 // Change the control input of expensive nodes to allow commoning by 955 // IGVN when it is guaranteed to not result in a more frequent 956 // execution of the expensive node. Return true if progress. 957 bool process_expensive_nodes(); 958 959 // Check whether node has become unreachable 960 bool is_node_unreachable(Node *n) const { 961 return !has_node(n) || n->is_unreachable(_igvn); 962 } 963 964 // Eliminate range-checks and other trip-counter vs loop-invariant tests. 965 void do_range_check( IdealLoopTree *loop, Node_List &old_new ); 966 967 // Create a slow version of the loop by cloning the loop 968 // and inserting an if to select fast-slow versions. 969 ProjNode* create_slow_version_of_loop(IdealLoopTree *loop, 970 Node_List &old_new, 971 int opcode); 972 973 // Clone a loop and return the clone head (clone_loop_head). 974 // Added nodes include int(1), int(0) - disconnected, If, IfTrue, IfFalse, 975 // This routine was created for usage in CountedLoopReserveKit. 976 // 977 // int(1) -> If -> IfTrue -> original_loop_head 978 // | 979 // V 980 // IfFalse -> clone_loop_head (returned by function pointer) 981 // 982 LoopNode* create_reserve_version_of_loop(IdealLoopTree *loop, CountedLoopReserveKit* lk); 983 // Clone loop with an invariant test (that does not exit) and 984 // insert a clone of the test that selects which version to 985 // execute. 986 void do_unswitching (IdealLoopTree *loop, Node_List &old_new); 987 988 // Find candidate "if" for unswitching 989 IfNode* find_unswitching_candidate(const IdealLoopTree *loop) const; 990 991 // Range Check Elimination uses this function! 992 // Constrain the main loop iterations so the affine function: 993 // low_limit <= scale_con * I + offset < upper_limit 994 // always holds true. That is, either increase the number of iterations in 995 // the pre-loop or the post-loop until the condition holds true in the main 996 // loop. Scale_con, offset and limit are all loop invariant. 997 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 ); 998 // Helper function for add_constraint(). 999 Node* adjust_limit( int stride_con, Node * scale, Node *offset, Node *rc_limit, Node *loop_limit, Node *pre_ctrl ); 1000 1001 // Partially peel loop up through last_peel node. 1002 bool partial_peel( IdealLoopTree *loop, Node_List &old_new ); 1003 1004 // Create a scheduled list of nodes control dependent on ctrl set. 1005 void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched ); 1006 // Has a use in the vector set 1007 bool has_use_in_set( Node* n, VectorSet& vset ); 1008 // Has use internal to the vector set (ie. not in a phi at the loop head) 1009 bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ); 1010 // clone "n" for uses that are outside of loop 1011 int clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ); 1012 // clone "n" for special uses that are in the not_peeled region 1013 void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n, 1014 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ); 1015 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist 1016 void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ); 1017 #ifdef ASSERT 1018 // Validate the loop partition sets: peel and not_peel 1019 bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel ); 1020 // Ensure that uses outside of loop are of the right form 1021 bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list, 1022 uint orig_exit_idx, uint clone_exit_idx); 1023 bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx); 1024 #endif 1025 1026 // Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.) 1027 int stride_of_possible_iv( Node* iff ); 1028 bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; } 1029 // Return the (unique) control output node that's in the loop (if it exists.) 1030 Node* stay_in_loop( Node* n, IdealLoopTree *loop); 1031 // Insert a signed compare loop exit cloned from an unsigned compare. 1032 IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop); 1033 void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop); 1034 // Utility to register node "n" with PhaseIdealLoop 1035 void register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth); 1036 // Utility to create an if-projection 1037 ProjNode* proj_clone(ProjNode* p, IfNode* iff); 1038 // Force the iff control output to be the live_proj 1039 Node* short_circuit_if(IfNode* iff, ProjNode* live_proj); 1040 // Insert a region before an if projection 1041 RegionNode* insert_region_before_proj(ProjNode* proj); 1042 // Insert a new if before an if projection 1043 ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj); 1044 1045 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps. 1046 // "Nearly" because all Nodes have been cloned from the original in the loop, 1047 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs 1048 // through the Phi recursively, and return a Bool. 1049 BoolNode *clone_iff( PhiNode *phi, IdealLoopTree *loop ); 1050 CmpNode *clone_bool( PhiNode *phi, IdealLoopTree *loop ); 1051 1052 1053 // Rework addressing expressions to get the most loop-invariant stuff 1054 // moved out. We'd like to do all associative operators, but it's especially 1055 // important (common) to do address expressions. 1056 Node *remix_address_expressions( Node *n ); 1057 1058 // Attempt to use a conditional move instead of a phi/branch 1059 Node *conditional_move( Node *n ); 1060 1061 // Reorganize offset computations to lower register pressure. 1062 // Mostly prevent loop-fallout uses of the pre-incremented trip counter 1063 // (which are then alive with the post-incremented trip counter 1064 // forcing an extra register move) 1065 void reorg_offsets( IdealLoopTree *loop ); 1066 1067 // Check for aggressive application of 'split-if' optimization, 1068 // using basic block level info. 1069 void split_if_with_blocks ( VectorSet &visited, Node_Stack &nstack ); 1070 Node *split_if_with_blocks_pre ( Node *n ); 1071 void split_if_with_blocks_post( Node *n ); 1072 Node *has_local_phi_input( Node *n ); 1073 // Mark an IfNode as being dominated by a prior test, 1074 // without actually altering the CFG (and hence IDOM info). 1075 void dominated_by( Node *prevdom, Node *iff, bool flip = false, bool exclude_loop_predicate = false ); 1076 1077 // Split Node 'n' through merge point 1078 Node *split_thru_region( Node *n, Node *region ); 1079 // Split Node 'n' through merge point if there is enough win. 1080 Node *split_thru_phi( Node *n, Node *region, int policy ); 1081 // Found an If getting its condition-code input from a Phi in the 1082 // same block. Split thru the Region. 1083 void do_split_if( Node *iff ); 1084 1085 // Conversion of fill/copy patterns into intrisic versions 1086 bool do_intrinsify_fill(); 1087 bool intrinsify_fill(IdealLoopTree* lpt); 1088 bool match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value, 1089 Node*& shift, Node*& offset); 1090 1091 private: 1092 // Return a type based on condition control flow 1093 const TypeInt* filtered_type( Node *n, Node* n_ctrl); 1094 const TypeInt* filtered_type( Node *n ) { return filtered_type(n, NULL); } 1095 // Helpers for filtered type 1096 const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl); 1097 1098 // Helper functions 1099 Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache ); 1100 Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true ); 1101 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 ); 1102 bool split_up( Node *n, Node *blk1, Node *blk2 ); 1103 void sink_use( Node *use, Node *post_loop ); 1104 Node *place_near_use( Node *useblock ) const; 1105 Node* try_move_store_before_loop(Node* n, Node *n_ctrl); 1106 void try_move_store_after_loop(Node* n); 1107 1108 bool _created_loop_node; 1109 public: 1110 void set_created_loop_node() { _created_loop_node = true; } 1111 bool created_loop_node() { return _created_loop_node; } 1112 void register_new_node( Node *n, Node *blk ); 1113 1114 #ifdef ASSERT 1115 void dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA); 1116 #endif 1117 1118 #ifndef PRODUCT 1119 void dump( ) const; 1120 void dump( IdealLoopTree *loop, uint rpo_idx, Node_List &rpo_list ) const; 1121 void rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const; 1122 void verify() const; // Major slow :-) 1123 void verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const; 1124 IdealLoopTree *get_loop_idx(Node* n) const { 1125 // Dead nodes have no loop, so return the top level loop instead 1126 return _nodes[n->_idx] ? (IdealLoopTree*)_nodes[n->_idx] : _ltree_root; 1127 } 1128 // Print some stats 1129 static void print_statistics(); 1130 static int _loop_invokes; // Count of PhaseIdealLoop invokes 1131 static int _loop_work; // Sum of PhaseIdealLoop x _unique 1132 #endif 1133 }; 1134 1135 // This kit may be used for making of a reserved copy of a loop before this loop 1136 // goes under non-reversible changes. 1137 // 1138 // Function create_reserve() creates a reserved copy (clone) of the loop. 1139 // The reserved copy is created by calling 1140 // PhaseIdealLoop::create_reserve_version_of_loop - see there how 1141 // the original and reserved loops are connected in the outer graph. 1142 // If create_reserve succeeded, it returns 'true' and _has_reserved is set to 'true'. 1143 // 1144 // By default the reserved copy (clone) of the loop is created as dead code - it is 1145 // dominated in the outer loop by this node chain: 1146 // intcon(1)->If->IfFalse->reserved_copy. 1147 // The original loop is dominated by the the same node chain but IfTrue projection: 1148 // intcon(0)->If->IfTrue->original_loop. 1149 // 1150 // In this implementation of CountedLoopReserveKit the ctor includes create_reserve() 1151 // and the dtor, checks _use_new value. 1152 // If _use_new == false, it "switches" control to reserved copy of the loop 1153 // by simple replacing of node intcon(1) with node intcon(0). 1154 // 1155 // Here is a proposed example of usage (see also SuperWord::output in superword.cpp). 1156 // 1157 // void CountedLoopReserveKit_example() 1158 // { 1159 // CountedLoopReserveKit lrk((phase, lpt, DoReserveCopy = true); // create local object 1160 // if (DoReserveCopy && !lrk.has_reserved()) { 1161 // return; //failed to create reserved loop copy 1162 // } 1163 // ... 1164 // //something is wrong, switch to original loop 1165 /// if(something_is_wrong) return; // ~CountedLoopReserveKit makes the switch 1166 // ... 1167 // //everything worked ok, return with the newly modified loop 1168 // lrk.use_new(); 1169 // return; // ~CountedLoopReserveKit does nothing once use_new() was called 1170 // } 1171 // 1172 // Keep in mind, that by default if create_reserve() is not followed by use_new() 1173 // the dtor will "switch to the original" loop. 1174 // NOTE. You you modify outside of the original loop this class is no help. 1175 // 1176 class CountedLoopReserveKit { 1177 private: 1178 PhaseIdealLoop* _phase; 1179 IdealLoopTree* _lpt; 1180 LoopNode* _lp; 1181 IfNode* _iff; 1182 LoopNode* _lp_reserved; 1183 bool _has_reserved; 1184 bool _use_new; 1185 const bool _active; //may be set to false in ctor, then the object is dummy 1186 1187 public: 1188 CountedLoopReserveKit(PhaseIdealLoop* phase, IdealLoopTree *loop, bool active); 1189 ~CountedLoopReserveKit(); 1190 void use_new() {_use_new = true;} 1191 void set_iff(IfNode* x) {_iff = x;} 1192 bool has_reserved() const { return _active && _has_reserved;} 1193 private: 1194 bool create_reserve(); 1195 };// class CountedLoopReserveKit 1196 1197 inline Node* IdealLoopTree::tail() { 1198 // Handle lazy update of _tail field 1199 Node *n = _tail; 1200 //while( !n->in(0) ) // Skip dead CFG nodes 1201 //n = n->in(1); 1202 if (n->in(0) == NULL) 1203 n = _phase->get_ctrl(n); 1204 _tail = n; 1205 return n; 1206 } 1207 1208 1209 // Iterate over the loop tree using a preorder, left-to-right traversal. 1210 // 1211 // Example that visits all counted loops from within PhaseIdealLoop 1212 // 1213 // for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) { 1214 // IdealLoopTree* lpt = iter.current(); 1215 // if (!lpt->is_counted()) continue; 1216 // ... 1217 class LoopTreeIterator : public StackObj { 1218 private: 1219 IdealLoopTree* _root; 1220 IdealLoopTree* _curnt; 1221 1222 public: 1223 LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {} 1224 1225 bool done() { return _curnt == NULL; } // Finished iterating? 1226 1227 void next(); // Advance to next loop tree 1228 1229 IdealLoopTree* current() { return _curnt; } // Return current value of iterator. 1230 }; 1231 1232 #endif // SHARE_VM_OPTO_LOOPNODE_HPP