1 /* 2 * Copyright (c) 1998, 2015, 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 VectorizedLoop=2048, 72 HasAtomicPostLoop=4096, 73 HasRangeChecks=8192, 74 IsMultiversioned=16384}; 75 char _unswitch_count; 76 enum { _unswitch_max=3 }; 77 char _postloop_flags; 78 enum { LoopNotRCEChecked = 0, LoopRCEChecked = 1, RCEPostLoop = 2 }; 79 80 public: 81 // Names for edge indices 82 enum { Self=0, EntryControl, LoopBackControl }; 83 84 int is_inner_loop() const { return _loop_flags & InnerLoop; } 85 void set_inner_loop() { _loop_flags |= InnerLoop; } 86 87 int range_checks_present() const { return _loop_flags & HasRangeChecks; } 88 int is_multiversioned() const { return _loop_flags & IsMultiversioned; } 89 int is_vectorized_loop() const { return _loop_flags & VectorizedLoop; } 90 int is_partial_peel_loop() const { return _loop_flags & PartialPeelLoop; } 91 void set_partial_peel_loop() { _loop_flags |= PartialPeelLoop; } 92 int partial_peel_has_failed() const { return _loop_flags & PartialPeelFailed; } 93 94 void mark_partial_peel_failed() { _loop_flags |= PartialPeelFailed; } 95 void mark_has_reductions() { _loop_flags |= HasReductions; } 96 void mark_was_slp() { _loop_flags |= WasSlpAnalyzed; } 97 void mark_passed_slp() { _loop_flags |= PassedSlpAnalysis; } 98 void mark_do_unroll_only() { _loop_flags |= DoUnrollOnly; } 99 void mark_loop_vectorized() { _loop_flags |= VectorizedLoop; } 100 void mark_has_atomic_post_loop() { _loop_flags |= HasAtomicPostLoop; } 101 void mark_has_range_checks() { _loop_flags |= HasRangeChecks; } 102 void mark_is_multiversioned() { _loop_flags |= IsMultiversioned; } 103 104 int unswitch_max() { return _unswitch_max; } 105 int unswitch_count() { return _unswitch_count; } 106 107 int has_been_range_checked() const { return _postloop_flags & LoopRCEChecked; } 108 void set_has_been_range_checked() { _postloop_flags |= LoopRCEChecked; } 109 int is_rce_post_loop() const { return _postloop_flags & RCEPostLoop; } 110 void set_is_rce_post_loop() { _postloop_flags |= RCEPostLoop; } 111 112 void set_unswitch_count(int val) { 113 assert (val <= unswitch_max(), "too many unswitches"); 114 _unswitch_count = val; 115 } 116 117 LoopNode(Node *entry, Node *backedge) : RegionNode(3), _loop_flags(0), _unswitch_count(0), _postloop_flags(0) { 118 init_class_id(Class_Loop); 119 init_req(EntryControl, entry); 120 init_req(LoopBackControl, backedge); 121 } 122 123 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); 124 virtual int Opcode() const; 125 bool can_be_counted_loop(PhaseTransform* phase) const { 126 return req() == 3 && in(0) != NULL && 127 in(1) != NULL && phase->type(in(1)) != Type::TOP && 128 in(2) != NULL && phase->type(in(2)) != Type::TOP; 129 } 130 bool is_valid_counted_loop() const; 131 #ifndef PRODUCT 132 virtual void dump_spec(outputStream *st) const; 133 #endif 134 }; 135 136 //------------------------------Counted Loops---------------------------------- 137 // Counted loops are all trip-counted loops, with exactly 1 trip-counter exit 138 // path (and maybe some other exit paths). The trip-counter exit is always 139 // last in the loop. The trip-counter have to stride by a constant; 140 // the exit value is also loop invariant. 141 142 // CountedLoopNodes and CountedLoopEndNodes come in matched pairs. The 143 // CountedLoopNode has the incoming loop control and the loop-back-control 144 // which is always the IfTrue before the matching CountedLoopEndNode. The 145 // CountedLoopEndNode has an incoming control (possibly not the 146 // CountedLoopNode if there is control flow in the loop), the post-increment 147 // trip-counter value, and the limit. The trip-counter value is always of 148 // the form (Op old-trip-counter stride). The old-trip-counter is produced 149 // by a Phi connected to the CountedLoopNode. The stride is constant. 150 // The Op is any commutable opcode, including Add, Mul, Xor. The 151 // CountedLoopEndNode also takes in the loop-invariant limit value. 152 153 // From a CountedLoopNode I can reach the matching CountedLoopEndNode via the 154 // loop-back control. From CountedLoopEndNodes I can reach CountedLoopNodes 155 // via the old-trip-counter from the Op node. 156 157 //------------------------------CountedLoopNode-------------------------------- 158 // CountedLoopNodes head simple counted loops. CountedLoopNodes have as 159 // inputs the incoming loop-start control and the loop-back control, so they 160 // act like RegionNodes. They also take in the initial trip counter, the 161 // loop-invariant stride and the loop-invariant limit value. CountedLoopNodes 162 // produce a loop-body control and the trip counter value. Since 163 // CountedLoopNodes behave like RegionNodes I still have a standard CFG model. 164 165 class CountedLoopNode : public LoopNode { 166 // Size is bigger to hold _main_idx. However, _main_idx does not change 167 // the semantics so it does not appear in the hash & cmp functions. 168 virtual uint size_of() const { return sizeof(*this); } 169 170 // For Pre- and Post-loops during debugging ONLY, this holds the index of 171 // the Main CountedLoop. Used to assert that we understand the graph shape. 172 node_idx_t _main_idx; 173 174 // Known trip count calculated by compute_exact_trip_count() 175 uint _trip_count; 176 177 // Expected trip count from profile data 178 float _profile_trip_cnt; 179 180 // Log2 of original loop bodies in unrolled loop 181 int _unrolled_count_log2; 182 183 // Node count prior to last unrolling - used to decide if 184 // unroll,optimize,unroll,optimize,... is making progress 185 int _node_count_before_unroll; 186 187 // If slp analysis is performed we record the maximum 188 // vector mapped unroll factor here 189 int _slp_maximum_unroll_factor; 190 191 public: 192 CountedLoopNode( Node *entry, Node *backedge ) 193 : LoopNode(entry, backedge), _main_idx(0), _trip_count(max_juint), 194 _profile_trip_cnt(COUNT_UNKNOWN), _unrolled_count_log2(0), 195 _node_count_before_unroll(0), _slp_maximum_unroll_factor(0) { 196 init_class_id(Class_CountedLoop); 197 // Initialize _trip_count to the largest possible value. 198 // Will be reset (lower) if the loop's trip count is known. 199 } 200 201 virtual int Opcode() const; 202 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); 203 204 Node *init_control() const { return in(EntryControl); } 205 Node *back_control() const { return in(LoopBackControl); } 206 CountedLoopEndNode *loopexit() const; 207 Node *init_trip() const; 208 Node *stride() const; 209 int stride_con() const; 210 bool stride_is_con() const; 211 Node *limit() const; 212 Node *incr() const; 213 Node *phi() const; 214 215 // Match increment with optional truncation 216 static Node* match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type); 217 218 // A 'main' loop has a pre-loop and a post-loop. The 'main' loop 219 // can run short a few iterations and may start a few iterations in. 220 // It will be RCE'd and unrolled and aligned. 221 222 // A following 'post' loop will run any remaining iterations. Used 223 // during Range Check Elimination, the 'post' loop will do any final 224 // iterations with full checks. Also used by Loop Unrolling, where 225 // the 'post' loop will do any epilog iterations needed. Basically, 226 // a 'post' loop can not profitably be further unrolled or RCE'd. 227 228 // A preceding 'pre' loop will run at least 1 iteration (to do peeling), 229 // it may do under-flow checks for RCE and may do alignment iterations 230 // so the following main loop 'knows' that it is striding down cache 231 // lines. 232 233 // A 'main' loop that is ONLY unrolled or peeled, never RCE'd or 234 // Aligned, may be missing it's pre-loop. 235 int is_normal_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Normal; } 236 int is_pre_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Pre; } 237 int is_main_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Main; } 238 int is_post_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Post; } 239 int is_reduction_loop() const { return (_loop_flags&HasReductions) == HasReductions; } 240 int was_slp_analyzed () const { return (_loop_flags&WasSlpAnalyzed) == WasSlpAnalyzed; } 241 int has_passed_slp () const { return (_loop_flags&PassedSlpAnalysis) == PassedSlpAnalysis; } 242 int do_unroll_only () const { return (_loop_flags&DoUnrollOnly) == DoUnrollOnly; } 243 int is_main_no_pre_loop() const { return _loop_flags & MainHasNoPreLoop; } 244 int has_atomic_post_loop () const { return (_loop_flags & HasAtomicPostLoop) == HasAtomicPostLoop; } 245 void set_main_no_pre_loop() { _loop_flags |= MainHasNoPreLoop; } 246 247 int main_idx() const { return _main_idx; } 248 249 250 void set_pre_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; } 251 void set_main_loop ( ) { assert(is_normal_loop(),""); _loop_flags |= Main; } 252 void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; } 253 void set_normal_loop( ) { _loop_flags &= ~PreMainPostFlagsMask; } 254 255 void set_trip_count(uint tc) { _trip_count = tc; } 256 uint trip_count() { return _trip_count; } 257 258 bool has_exact_trip_count() const { return (_loop_flags & HasExactTripCount) != 0; } 259 void set_exact_trip_count(uint tc) { 260 _trip_count = tc; 261 _loop_flags |= HasExactTripCount; 262 } 263 void set_nonexact_trip_count() { 264 _loop_flags &= ~HasExactTripCount; 265 } 266 void set_notpassed_slp() { 267 _loop_flags &= ~PassedSlpAnalysis; 268 } 269 270 void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; } 271 float profile_trip_cnt() { return _profile_trip_cnt; } 272 273 void double_unrolled_count() { _unrolled_count_log2++; } 274 int unrolled_count() { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); } 275 276 void set_node_count_before_unroll(int ct) { _node_count_before_unroll = ct; } 277 int node_count_before_unroll() { return _node_count_before_unroll; } 278 void set_slp_max_unroll(int unroll_factor) { _slp_maximum_unroll_factor = unroll_factor; } 279 int slp_max_unroll() const { return _slp_maximum_unroll_factor; } 280 281 #ifndef PRODUCT 282 virtual void dump_spec(outputStream *st) const; 283 #endif 284 }; 285 286 //------------------------------CountedLoopEndNode----------------------------- 287 // CountedLoopEndNodes end simple trip counted loops. They act much like 288 // IfNodes. 289 class CountedLoopEndNode : public IfNode { 290 public: 291 enum { TestControl, TestValue }; 292 293 CountedLoopEndNode( Node *control, Node *test, float prob, float cnt ) 294 : IfNode( control, test, prob, cnt) { 295 init_class_id(Class_CountedLoopEnd); 296 } 297 virtual int Opcode() const; 298 299 Node *cmp_node() const { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : NULL; } 300 Node *incr() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; } 301 Node *limit() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; } 302 Node *stride() const { Node *tmp = incr (); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; } 303 Node *init_trip() const { Node *tmp = phi (); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; } 304 int stride_con() const; 305 bool stride_is_con() const { Node *tmp = stride (); return (tmp != NULL && tmp->is_Con()); } 306 BoolTest::mask test_trip() const { return in(TestValue)->as_Bool()->_test._test; } 307 PhiNode *phi() const { 308 Node *tmp = incr(); 309 if (tmp && tmp->req() == 3) { 310 Node* phi = tmp->in(1); 311 if (phi->is_Phi()) { 312 return phi->as_Phi(); 313 } 314 } 315 return NULL; 316 } 317 CountedLoopNode *loopnode() const { 318 // The CountedLoopNode that goes with this CountedLoopEndNode may 319 // have been optimized out by the IGVN so be cautious with the 320 // pattern matching on the graph 321 PhiNode* iv_phi = phi(); 322 if (iv_phi == NULL) { 323 return NULL; 324 } 325 Node *ln = iv_phi->in(0); 326 if (ln->is_CountedLoop() && ln->as_CountedLoop()->loopexit() == this) { 327 return (CountedLoopNode*)ln; 328 } 329 return NULL; 330 } 331 332 #ifndef PRODUCT 333 virtual void dump_spec(outputStream *st) const; 334 #endif 335 }; 336 337 338 inline CountedLoopEndNode *CountedLoopNode::loopexit() const { 339 Node *bc = back_control(); 340 if( bc == NULL ) return NULL; 341 Node *le = bc->in(0); 342 if( le->Opcode() != Op_CountedLoopEnd ) 343 return NULL; 344 return (CountedLoopEndNode*)le; 345 } 346 inline Node *CountedLoopNode::init_trip() const { return loopexit() ? loopexit()->init_trip() : NULL; } 347 inline Node *CountedLoopNode::stride() const { return loopexit() ? loopexit()->stride() : NULL; } 348 inline int CountedLoopNode::stride_con() const { return loopexit() ? loopexit()->stride_con() : 0; } 349 inline bool CountedLoopNode::stride_is_con() const { return loopexit() && loopexit()->stride_is_con(); } 350 inline Node *CountedLoopNode::limit() const { return loopexit() ? loopexit()->limit() : NULL; } 351 inline Node *CountedLoopNode::incr() const { return loopexit() ? loopexit()->incr() : NULL; } 352 inline Node *CountedLoopNode::phi() const { return loopexit() ? loopexit()->phi() : NULL; } 353 354 //------------------------------LoopLimitNode----------------------------- 355 // Counted Loop limit node which represents exact final iterator value: 356 // trip_count = (limit - init_trip + stride - 1)/stride 357 // final_value= trip_count * stride + init_trip. 358 // Use HW instructions to calculate it when it can overflow in integer. 359 // Note, final_value should fit into integer since counted loop has 360 // limit check: limit <= max_int-stride. 361 class LoopLimitNode : public Node { 362 enum { Init=1, Limit=2, Stride=3 }; 363 public: 364 LoopLimitNode( Compile* C, Node *init, Node *limit, Node *stride ) : Node(0,init,limit,stride) { 365 // Put it on the Macro nodes list to optimize during macro nodes expansion. 366 init_flags(Flag_is_macro); 367 C->add_macro_node(this); 368 } 369 virtual int Opcode() const; 370 virtual const Type *bottom_type() const { return TypeInt::INT; } 371 virtual uint ideal_reg() const { return Op_RegI; } 372 virtual const Type* Value(PhaseGVN* phase) const; 373 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); 374 virtual Node* Identity(PhaseGVN* phase); 375 }; 376 377 // -----------------------------IdealLoopTree---------------------------------- 378 class IdealLoopTree : public ResourceObj { 379 public: 380 IdealLoopTree *_parent; // Parent in loop tree 381 IdealLoopTree *_next; // Next sibling in loop tree 382 IdealLoopTree *_child; // First child in loop tree 383 384 // The head-tail backedge defines the loop. 385 // If tail is NULL then this loop has multiple backedges as part of the 386 // same loop. During cleanup I'll peel off the multiple backedges; merge 387 // them at the loop bottom and flow 1 real backedge into the loop. 388 Node *_head; // Head of loop 389 Node *_tail; // Tail of loop 390 inline Node *tail(); // Handle lazy update of _tail field 391 PhaseIdealLoop* _phase; 392 int _local_loop_unroll_limit; 393 int _local_loop_unroll_factor; 394 395 Node_List _body; // Loop body for inner loops 396 397 uint8_t _nest; // Nesting depth 398 uint8_t _irreducible:1, // True if irreducible 399 _has_call:1, // True if has call safepoint 400 _has_sfpt:1, // True if has non-call safepoint 401 _rce_candidate:1; // True if candidate for range check elimination 402 403 Node_List* _safepts; // List of safepoints in this loop 404 Node_List* _required_safept; // A inner loop cannot delete these safepts; 405 bool _allow_optimizations; // Allow loop optimizations 406 407 IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail ) 408 : _parent(0), _next(0), _child(0), 409 _head(head), _tail(tail), 410 _phase(phase), 411 _safepts(NULL), 412 _required_safept(NULL), 413 _allow_optimizations(true), 414 _nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0), 415 _local_loop_unroll_limit(0), _local_loop_unroll_factor(0) 416 { } 417 418 // Is 'l' a member of 'this'? 419 bool is_member(const IdealLoopTree *l) const; // Test for nested membership 420 421 // Set loop nesting depth. Accumulate has_call bits. 422 int set_nest( uint depth ); 423 424 // Split out multiple fall-in edges from the loop header. Move them to a 425 // private RegionNode before the loop. This becomes the loop landing pad. 426 void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ); 427 428 // Split out the outermost loop from this shared header. 429 void split_outer_loop( PhaseIdealLoop *phase ); 430 431 // Merge all the backedges from the shared header into a private Region. 432 // Feed that region as the one backedge to this loop. 433 void merge_many_backedges( PhaseIdealLoop *phase ); 434 435 // Split shared headers and insert loop landing pads. 436 // Insert a LoopNode to replace the RegionNode. 437 // Returns TRUE if loop tree is structurally changed. 438 bool beautify_loops( PhaseIdealLoop *phase ); 439 440 // Perform optimization to use the loop predicates for null checks and range checks. 441 // Applies to any loop level (not just the innermost one) 442 bool loop_predication( PhaseIdealLoop *phase); 443 444 // Perform iteration-splitting on inner loops. Split iterations to 445 // avoid range checks or one-shot null checks. Returns false if the 446 // current round of loop opts should stop. 447 bool iteration_split( PhaseIdealLoop *phase, Node_List &old_new ); 448 449 // Driver for various flavors of iteration splitting. Returns false 450 // if the current round of loop opts should stop. 451 bool iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new ); 452 453 // Given dominators, try to find loops with calls that must always be 454 // executed (call dominates loop tail). These loops do not need non-call 455 // safepoints (ncsfpt). 456 void check_safepts(VectorSet &visited, Node_List &stack); 457 458 // Allpaths backwards scan from loop tail, terminating each path at first safepoint 459 // encountered. 460 void allpaths_check_safepts(VectorSet &visited, Node_List &stack); 461 462 // Remove safepoints from loop. Optionally keeping one. 463 void remove_safepoints(PhaseIdealLoop* phase, bool keep_one); 464 465 // Convert to counted loops where possible 466 void counted_loop( PhaseIdealLoop *phase ); 467 468 // Check for Node being a loop-breaking test 469 Node *is_loop_exit(Node *iff) const; 470 471 // Remove simplistic dead code from loop body 472 void DCE_loop_body(); 473 474 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage. 475 // Replace with a 1-in-10 exit guess. 476 void adjust_loop_exit_prob( PhaseIdealLoop *phase ); 477 478 // Return TRUE or FALSE if the loop should never be RCE'd or aligned. 479 // Useful for unrolling loops with NO array accesses. 480 bool policy_peel_only( PhaseIdealLoop *phase ) const; 481 482 // Return TRUE or FALSE if the loop should be unswitched -- clone 483 // loop with an invariant test 484 bool policy_unswitching( PhaseIdealLoop *phase ) const; 485 486 // Micro-benchmark spamming. Remove empty loops. 487 bool policy_do_remove_empty_loop( PhaseIdealLoop *phase ); 488 489 // Convert one iteration loop into normal code. 490 bool policy_do_one_iteration_loop( PhaseIdealLoop *phase ); 491 492 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can 493 // make some loop-invariant test (usually a null-check) happen before the 494 // loop. 495 bool policy_peeling( PhaseIdealLoop *phase ) const; 496 497 // Return TRUE or FALSE if the loop should be maximally unrolled. Stash any 498 // known trip count in the counted loop node. 499 bool policy_maximally_unroll( PhaseIdealLoop *phase ) const; 500 501 // Return TRUE or FALSE if the loop should be unrolled or not. Unroll if 502 // the loop is a CountedLoop and the body is small enough. 503 bool policy_unroll(PhaseIdealLoop *phase); 504 505 // Loop analyses to map to a maximal superword unrolling for vectorization. 506 void policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_ct); 507 508 // Return TRUE or FALSE if the loop should be range-check-eliminated. 509 // Gather a list of IF tests that are dominated by iteration splitting; 510 // also gather the end of the first split and the start of the 2nd split. 511 bool policy_range_check( PhaseIdealLoop *phase ) const; 512 513 // Return TRUE or FALSE if the loop should be cache-line aligned. 514 // Gather the expression that does the alignment. Note that only 515 // one array base can be aligned in a loop (unless the VM guarantees 516 // mutual alignment). Note that if we vectorize short memory ops 517 // into longer memory ops, we may want to increase alignment. 518 bool policy_align( PhaseIdealLoop *phase ) const; 519 520 // Return TRUE if "iff" is a range check. 521 bool is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const; 522 523 // Compute loop exact trip count if possible 524 void compute_exact_trip_count( PhaseIdealLoop *phase ); 525 526 // Compute loop trip count from profile data 527 void compute_profile_trip_cnt( PhaseIdealLoop *phase ); 528 529 // Reassociate invariant expressions. 530 void reassociate_invariants(PhaseIdealLoop *phase); 531 // Reassociate invariant add and subtract expressions. 532 Node* reassociate_add_sub(Node* n1, PhaseIdealLoop *phase); 533 // Return nonzero index of invariant operand if invariant and variant 534 // are combined with an Add or Sub. Helper for reassociate_invariants. 535 int is_invariant_addition(Node* n, PhaseIdealLoop *phase); 536 537 // Return true if n is invariant 538 bool is_invariant(Node* n) const; 539 540 // Put loop body on igvn work list 541 void record_for_igvn(); 542 543 bool is_loop() { return !_irreducible && _tail && !_tail->is_top(); } 544 bool is_inner() { return is_loop() && _child == NULL; } 545 bool is_counted() { return is_loop() && _head != NULL && _head->is_CountedLoop(); } 546 547 void remove_main_post_loops(CountedLoopNode *cl, PhaseIdealLoop *phase); 548 549 #ifndef PRODUCT 550 void dump_head( ) const; // Dump loop head only 551 void dump() const; // Dump this loop recursively 552 void verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const; 553 #endif 554 555 }; 556 557 // -----------------------------PhaseIdealLoop--------------------------------- 558 // Computes the mapping from Nodes to IdealLoopTrees. Organizes IdealLoopTrees into a 559 // loop tree. Drives the loop-based transformations on the ideal graph. 560 class PhaseIdealLoop : public PhaseTransform { 561 friend class IdealLoopTree; 562 friend class SuperWord; 563 friend class CountedLoopReserveKit; 564 565 // Pre-computed def-use info 566 PhaseIterGVN &_igvn; 567 568 // Head of loop tree 569 IdealLoopTree *_ltree_root; 570 571 // Array of pre-order numbers, plus post-visited bit. 572 // ZERO for not pre-visited. EVEN for pre-visited but not post-visited. 573 // ODD for post-visited. Other bits are the pre-order number. 574 uint *_preorders; 575 uint _max_preorder; 576 577 const PhaseIdealLoop* _verify_me; 578 bool _verify_only; 579 580 // Allocate _preorders[] array 581 void allocate_preorders() { 582 _max_preorder = C->unique()+8; 583 _preorders = NEW_RESOURCE_ARRAY(uint, _max_preorder); 584 memset(_preorders, 0, sizeof(uint) * _max_preorder); 585 } 586 587 // Allocate _preorders[] array 588 void reallocate_preorders() { 589 if ( _max_preorder < C->unique() ) { 590 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique()); 591 _max_preorder = C->unique(); 592 } 593 memset(_preorders, 0, sizeof(uint) * _max_preorder); 594 } 595 596 // Check to grow _preorders[] array for the case when build_loop_tree_impl() 597 // adds new nodes. 598 void check_grow_preorders( ) { 599 if ( _max_preorder < C->unique() ) { 600 uint newsize = _max_preorder<<1; // double size of array 601 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize); 602 memset(&_preorders[_max_preorder],0,sizeof(uint)*(newsize-_max_preorder)); 603 _max_preorder = newsize; 604 } 605 } 606 // Check for pre-visited. Zero for NOT visited; non-zero for visited. 607 int is_visited( Node *n ) const { return _preorders[n->_idx]; } 608 // Pre-order numbers are written to the Nodes array as low-bit-set values. 609 void set_preorder_visited( Node *n, int pre_order ) { 610 assert( !is_visited( n ), "already set" ); 611 _preorders[n->_idx] = (pre_order<<1); 612 }; 613 // Return pre-order number. 614 int get_preorder( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]>>1; } 615 616 // Check for being post-visited. 617 // Should be previsited already (checked with assert(is_visited(n))). 618 int is_postvisited( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]&1; } 619 620 // Mark as post visited 621 void set_postvisited( Node *n ) { assert( !is_postvisited( n ), "" ); _preorders[n->_idx] |= 1; } 622 623 // Set/get control node out. Set lower bit to distinguish from IdealLoopTree 624 // Returns true if "n" is a data node, false if it's a control node. 625 bool has_ctrl( Node *n ) const { return ((intptr_t)_nodes[n->_idx]) & 1; } 626 627 // clear out dead code after build_loop_late 628 Node_List _deadlist; 629 630 // Support for faster execution of get_late_ctrl()/dom_lca() 631 // when a node has many uses and dominator depth is deep. 632 Node_Array _dom_lca_tags; 633 void init_dom_lca_tags(); 634 void clear_dom_lca_tags(); 635 636 // Helper for debugging bad dominance relationships 637 bool verify_dominance(Node* n, Node* use, Node* LCA, Node* early); 638 639 Node* compute_lca_of_uses(Node* n, Node* early, bool verify = false); 640 641 // Inline wrapper for frequent cases: 642 // 1) only one use 643 // 2) a use is the same as the current LCA passed as 'n1' 644 Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) { 645 assert( n->is_CFG(), "" ); 646 // Fast-path NULL lca 647 if( lca != NULL && lca != n ) { 648 assert( lca->is_CFG(), "" ); 649 // find LCA of all uses 650 n = dom_lca_for_get_late_ctrl_internal( lca, n, tag ); 651 } 652 return find_non_split_ctrl(n); 653 } 654 Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag ); 655 656 // Helper function for directing control inputs away from CFG split 657 // points. 658 Node *find_non_split_ctrl( Node *ctrl ) const { 659 if (ctrl != NULL) { 660 if (ctrl->is_MultiBranch()) { 661 ctrl = ctrl->in(0); 662 } 663 assert(ctrl->is_CFG(), "CFG"); 664 } 665 return ctrl; 666 } 667 668 bool cast_incr_before_loop(Node* incr, Node* ctrl, Node* loop); 669 670 public: 671 672 static bool is_canonical_loop_entry(CountedLoopNode* cl); 673 674 bool has_node( Node* n ) const { 675 guarantee(n != NULL, "No Node."); 676 return _nodes[n->_idx] != NULL; 677 } 678 // check if transform created new nodes that need _ctrl recorded 679 Node *get_late_ctrl( Node *n, Node *early ); 680 Node *get_early_ctrl( Node *n ); 681 Node *get_early_ctrl_for_expensive(Node *n, Node* earliest); 682 void set_early_ctrl( Node *n ); 683 void set_subtree_ctrl( Node *root ); 684 void set_ctrl( Node *n, Node *ctrl ) { 685 assert( !has_node(n) || has_ctrl(n), "" ); 686 assert( ctrl->in(0), "cannot set dead control node" ); 687 assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" ); 688 _nodes.map( n->_idx, (Node*)((intptr_t)ctrl + 1) ); 689 } 690 // Set control and update loop membership 691 void set_ctrl_and_loop(Node* n, Node* ctrl) { 692 IdealLoopTree* old_loop = get_loop(get_ctrl(n)); 693 IdealLoopTree* new_loop = get_loop(ctrl); 694 if (old_loop != new_loop) { 695 if (old_loop->_child == NULL) old_loop->_body.yank(n); 696 if (new_loop->_child == NULL) new_loop->_body.push(n); 697 } 698 set_ctrl(n, ctrl); 699 } 700 // Control nodes can be replaced or subsumed. During this pass they 701 // get their replacement Node in slot 1. Instead of updating the block 702 // location of all Nodes in the subsumed block, we lazily do it. As we 703 // pull such a subsumed block out of the array, we write back the final 704 // correct block. 705 Node *get_ctrl( Node *i ) { 706 assert(has_node(i), ""); 707 Node *n = get_ctrl_no_update(i); 708 _nodes.map( i->_idx, (Node*)((intptr_t)n + 1) ); 709 assert(has_node(i) && has_ctrl(i), ""); 710 assert(n == find_non_split_ctrl(n), "must return legal ctrl" ); 711 return n; 712 } 713 // true if CFG node d dominates CFG node n 714 bool is_dominator(Node *d, Node *n); 715 // return get_ctrl for a data node and self(n) for a CFG node 716 Node* ctrl_or_self(Node* n) { 717 if (has_ctrl(n)) 718 return get_ctrl(n); 719 else { 720 assert (n->is_CFG(), "must be a CFG node"); 721 return n; 722 } 723 } 724 725 private: 726 Node *get_ctrl_no_update_helper(Node *i) const { 727 assert(has_ctrl(i), "should be control, not loop"); 728 return (Node*)(((intptr_t)_nodes[i->_idx]) & ~1); 729 } 730 731 Node *get_ctrl_no_update(Node *i) const { 732 assert( has_ctrl(i), "" ); 733 Node *n = get_ctrl_no_update_helper(i); 734 if (!n->in(0)) { 735 // Skip dead CFG nodes 736 do { 737 n = get_ctrl_no_update_helper(n); 738 } while (!n->in(0)); 739 n = find_non_split_ctrl(n); 740 } 741 return n; 742 } 743 744 // Check for loop being set 745 // "n" must be a control node. Returns true if "n" is known to be in a loop. 746 bool has_loop( Node *n ) const { 747 assert(!has_node(n) || !has_ctrl(n), ""); 748 return has_node(n); 749 } 750 // Set loop 751 void set_loop( Node *n, IdealLoopTree *loop ) { 752 _nodes.map(n->_idx, (Node*)loop); 753 } 754 // Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms. Replace 755 // the 'old_node' with 'new_node'. Kill old-node. Add a reference 756 // from old_node to new_node to support the lazy update. Reference 757 // replaces loop reference, since that is not needed for dead node. 758 public: 759 void lazy_update(Node *old_node, Node *new_node) { 760 assert(old_node != new_node, "no cycles please"); 761 // Re-use the side array slot for this node to provide the 762 // forwarding pointer. 763 _nodes.map(old_node->_idx, (Node*)((intptr_t)new_node + 1)); 764 } 765 void lazy_replace(Node *old_node, Node *new_node) { 766 _igvn.replace_node(old_node, new_node); 767 lazy_update(old_node, new_node); 768 } 769 770 private: 771 772 // Place 'n' in some loop nest, where 'n' is a CFG node 773 void build_loop_tree(); 774 int build_loop_tree_impl( Node *n, int pre_order ); 775 // Insert loop into the existing loop tree. 'innermost' is a leaf of the 776 // loop tree, not the root. 777 IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost ); 778 779 // Place Data nodes in some loop nest 780 void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ); 781 void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ); 782 void build_loop_late_post ( Node* n ); 783 784 // Array of immediate dominance info for each CFG node indexed by node idx 785 private: 786 uint _idom_size; 787 Node **_idom; // Array of immediate dominators 788 uint *_dom_depth; // Used for fast LCA test 789 GrowableArray<uint>* _dom_stk; // For recomputation of dom depth 790 791 Node* idom_no_update(Node* d) const { 792 assert(d->_idx < _idom_size, "oob"); 793 Node* n = _idom[d->_idx]; 794 assert(n != NULL,"Bad immediate dominator info."); 795 while (n->in(0) == NULL) { // Skip dead CFG nodes 796 //n = n->in(1); 797 n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1); 798 assert(n != NULL,"Bad immediate dominator info."); 799 } 800 return n; 801 } 802 Node *idom(Node* d) const { 803 uint didx = d->_idx; 804 Node *n = idom_no_update(d); 805 _idom[didx] = n; // Lazily remove dead CFG nodes from table. 806 return n; 807 } 808 uint dom_depth(Node* d) const { 809 guarantee(d != NULL, "Null dominator info."); 810 guarantee(d->_idx < _idom_size, ""); 811 return _dom_depth[d->_idx]; 812 } 813 void set_idom(Node* d, Node* n, uint dom_depth); 814 // Locally compute IDOM using dom_lca call 815 Node *compute_idom( Node *region ) const; 816 // Recompute dom_depth 817 void recompute_dom_depth(); 818 819 // Is safept not required by an outer loop? 820 bool is_deleteable_safept(Node* sfpt); 821 822 // Replace parallel induction variable (parallel to trip counter) 823 void replace_parallel_iv(IdealLoopTree *loop); 824 825 // Perform verification that the graph is valid. 826 PhaseIdealLoop( PhaseIterGVN &igvn) : 827 PhaseTransform(Ideal_Loop), 828 _igvn(igvn), 829 _dom_lca_tags(arena()), // Thread::resource_area 830 _verify_me(NULL), 831 _verify_only(true) { 832 build_and_optimize(false, false); 833 } 834 835 // build the loop tree and perform any requested optimizations 836 void build_and_optimize(bool do_split_if, bool skip_loop_opts); 837 838 public: 839 // Dominators for the sea of nodes 840 void Dominators(); 841 Node *dom_lca( Node *n1, Node *n2 ) const { 842 return find_non_split_ctrl(dom_lca_internal(n1, n2)); 843 } 844 Node *dom_lca_internal( Node *n1, Node *n2 ) const; 845 846 // Compute the Ideal Node to Loop mapping 847 PhaseIdealLoop( PhaseIterGVN &igvn, bool do_split_ifs, bool skip_loop_opts = false) : 848 PhaseTransform(Ideal_Loop), 849 _igvn(igvn), 850 _dom_lca_tags(arena()), // Thread::resource_area 851 _verify_me(NULL), 852 _verify_only(false) { 853 build_and_optimize(do_split_ifs, skip_loop_opts); 854 } 855 856 // Verify that verify_me made the same decisions as a fresh run. 857 PhaseIdealLoop( PhaseIterGVN &igvn, const PhaseIdealLoop *verify_me) : 858 PhaseTransform(Ideal_Loop), 859 _igvn(igvn), 860 _dom_lca_tags(arena()), // Thread::resource_area 861 _verify_me(verify_me), 862 _verify_only(false) { 863 build_and_optimize(false, false); 864 } 865 866 // Build and verify the loop tree without modifying the graph. This 867 // is useful to verify that all inputs properly dominate their uses. 868 static void verify(PhaseIterGVN& igvn) { 869 #ifdef ASSERT 870 PhaseIdealLoop v(igvn); 871 #endif 872 } 873 874 // True if the method has at least 1 irreducible loop 875 bool _has_irreducible_loops; 876 877 // Per-Node transform 878 virtual Node *transform( Node *a_node ) { return 0; } 879 880 bool is_counted_loop( Node *x, IdealLoopTree *loop ); 881 882 Node* exact_limit( IdealLoopTree *loop ); 883 884 // Return a post-walked LoopNode 885 IdealLoopTree *get_loop( Node *n ) const { 886 // Dead nodes have no loop, so return the top level loop instead 887 if (!has_node(n)) return _ltree_root; 888 assert(!has_ctrl(n), ""); 889 return (IdealLoopTree*)_nodes[n->_idx]; 890 } 891 892 // Is 'n' a (nested) member of 'loop'? 893 int is_member( const IdealLoopTree *loop, Node *n ) const { 894 return loop->is_member(get_loop(n)); } 895 896 // This is the basic building block of the loop optimizations. It clones an 897 // entire loop body. It makes an old_new loop body mapping; with this 898 // mapping you can find the new-loop equivalent to an old-loop node. All 899 // new-loop nodes are exactly equal to their old-loop counterparts, all 900 // edges are the same. All exits from the old-loop now have a RegionNode 901 // that merges the equivalent new-loop path. This is true even for the 902 // normal "loop-exit" condition. All uses of loop-invariant old-loop values 903 // now come from (one or more) Phis that merge their new-loop equivalents. 904 // Parameter side_by_side_idom: 905 // When side_by_size_idom is NULL, the dominator tree is constructed for 906 // the clone loop to dominate the original. Used in construction of 907 // pre-main-post loop sequence. 908 // When nonnull, the clone and original are side-by-side, both are 909 // dominated by the passed in side_by_side_idom node. Used in 910 // construction of unswitched loops. 911 void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth, 912 Node* side_by_side_idom = NULL); 913 914 // If we got the effect of peeling, either by actually peeling or by 915 // making a pre-loop which must execute at least once, we can remove 916 // all loop-invariant dominated tests in the main body. 917 void peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new ); 918 919 // Generate code to do a loop peel for the given loop (and body). 920 // old_new is a temp array. 921 void do_peeling( IdealLoopTree *loop, Node_List &old_new ); 922 923 // Add pre and post loops around the given loop. These loops are used 924 // during RCE, unrolling and aligning loops. 925 void insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only ); 926 927 // Add post loop after the given loop. 928 Node *insert_post_loop(IdealLoopTree *loop, Node_List &old_new, 929 CountedLoopNode *main_head, CountedLoopEndNode *main_end, 930 Node *incr, Node *limit, CountedLoopNode *&post_head); 931 932 // Add an RCE'd post loop which we will multi-version adapt for run time test path usage 933 void insert_scalar_rced_post_loop( IdealLoopTree *loop, Node_List &old_new ); 934 935 // Add a vector post loop between a vector main loop and the current post loop 936 void insert_vector_post_loop(IdealLoopTree *loop, Node_List &old_new); 937 // If Node n lives in the back_ctrl block, we clone a private version of n 938 // in preheader_ctrl block and return that, otherwise return n. 939 Node *clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones ); 940 941 // Take steps to maximally unroll the loop. Peel any odd iterations, then 942 // unroll to do double iterations. The next round of major loop transforms 943 // will repeat till the doubled loop body does all remaining iterations in 1 944 // pass. 945 void do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new ); 946 947 // Unroll the loop body one step - make each trip do 2 iterations. 948 void do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip ); 949 950 // Mark vector reduction candidates before loop unrolling 951 void mark_reductions( IdealLoopTree *loop ); 952 953 // Return true if exp is a constant times an induction var 954 bool is_scaled_iv(Node* exp, Node* iv, int* p_scale); 955 956 // Return true if exp is a scaled induction var plus (or minus) constant 957 bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth = 0); 958 959 // Create a new if above the uncommon_trap_if_pattern for the predicate to be promoted 960 ProjNode* create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry, 961 Deoptimization::DeoptReason reason, 962 int opcode); 963 void register_control(Node* n, IdealLoopTree *loop, Node* pred); 964 965 // Clone loop predicates to cloned loops (peeled, unswitched) 966 static ProjNode* clone_predicate(ProjNode* predicate_proj, Node* new_entry, 967 Deoptimization::DeoptReason reason, 968 PhaseIdealLoop* loop_phase, 969 PhaseIterGVN* igvn); 970 971 static Node* clone_loop_predicates(Node* old_entry, Node* new_entry, 972 bool clone_limit_check, 973 PhaseIdealLoop* loop_phase, 974 PhaseIterGVN* igvn); 975 Node* clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check); 976 977 static Node* skip_loop_predicates(Node* entry); 978 979 // Find a good location to insert a predicate 980 static ProjNode* find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason); 981 // Find a predicate 982 static Node* find_predicate(Node* entry); 983 // Construct a range check for a predicate if 984 BoolNode* rc_predicate(IdealLoopTree *loop, Node* ctrl, 985 int scale, Node* offset, 986 Node* init, Node* limit, Node* stride, 987 Node* range, bool upper); 988 989 // Implementation of the loop predication to promote checks outside the loop 990 bool loop_predication_impl(IdealLoopTree *loop); 991 992 // Helper function to collect predicate for eliminating the useless ones 993 void collect_potentially_useful_predicates(IdealLoopTree *loop, Unique_Node_List &predicate_opaque1); 994 void eliminate_useless_predicates(); 995 996 // Change the control input of expensive nodes to allow commoning by 997 // IGVN when it is guaranteed to not result in a more frequent 998 // execution of the expensive node. Return true if progress. 999 bool process_expensive_nodes(); 1000 1001 // Check whether node has become unreachable 1002 bool is_node_unreachable(Node *n) const { 1003 return !has_node(n) || n->is_unreachable(_igvn); 1004 } 1005 1006 // Eliminate range-checks and other trip-counter vs loop-invariant tests. 1007 int do_range_check( IdealLoopTree *loop, Node_List &old_new ); 1008 1009 // Check to see if do_range_check(...) cleaned the main loop of range-checks 1010 void has_range_checks(IdealLoopTree *loop); 1011 1012 // Process post loops which have range checks and try to build a multi-version 1013 // guard to safely determine if we can execute the post loop which was RCE'd. 1014 bool multi_version_post_loops(IdealLoopTree *rce_loop, IdealLoopTree *legacy_loop); 1015 1016 // Cause the rce'd post loop to optimized away, this happens if we cannot complete multiverioning 1017 void poison_rce_post_loop(IdealLoopTree *rce_loop); 1018 1019 // Create a slow version of the loop by cloning the loop 1020 // and inserting an if to select fast-slow versions. 1021 ProjNode* create_slow_version_of_loop(IdealLoopTree *loop, 1022 Node_List &old_new, 1023 int opcode); 1024 1025 // Clone a loop and return the clone head (clone_loop_head). 1026 // Added nodes include int(1), int(0) - disconnected, If, IfTrue, IfFalse, 1027 // This routine was created for usage in CountedLoopReserveKit. 1028 // 1029 // int(1) -> If -> IfTrue -> original_loop_head 1030 // | 1031 // V 1032 // IfFalse -> clone_loop_head (returned by function pointer) 1033 // 1034 LoopNode* create_reserve_version_of_loop(IdealLoopTree *loop, CountedLoopReserveKit* lk); 1035 // Clone loop with an invariant test (that does not exit) and 1036 // insert a clone of the test that selects which version to 1037 // execute. 1038 void do_unswitching (IdealLoopTree *loop, Node_List &old_new); 1039 1040 // Find candidate "if" for unswitching 1041 IfNode* find_unswitching_candidate(const IdealLoopTree *loop) const; 1042 1043 // Range Check Elimination uses this function! 1044 // Constrain the main loop iterations so the affine function: 1045 // low_limit <= scale_con * I + offset < upper_limit 1046 // always holds true. That is, either increase the number of iterations in 1047 // the pre-loop or the post-loop until the condition holds true in the main 1048 // loop. Scale_con, offset and limit are all loop invariant. 1049 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 ); 1050 // Helper function for add_constraint(). 1051 Node* adjust_limit( int stride_con, Node * scale, Node *offset, Node *rc_limit, Node *loop_limit, Node *pre_ctrl ); 1052 1053 // Partially peel loop up through last_peel node. 1054 bool partial_peel( IdealLoopTree *loop, Node_List &old_new ); 1055 1056 // Create a scheduled list of nodes control dependent on ctrl set. 1057 void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched ); 1058 // Has a use in the vector set 1059 bool has_use_in_set( Node* n, VectorSet& vset ); 1060 // Has use internal to the vector set (ie. not in a phi at the loop head) 1061 bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ); 1062 // clone "n" for uses that are outside of loop 1063 int clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ); 1064 // clone "n" for special uses that are in the not_peeled region 1065 void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n, 1066 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ); 1067 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist 1068 void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ); 1069 #ifdef ASSERT 1070 // Validate the loop partition sets: peel and not_peel 1071 bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel ); 1072 // Ensure that uses outside of loop are of the right form 1073 bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list, 1074 uint orig_exit_idx, uint clone_exit_idx); 1075 bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx); 1076 #endif 1077 1078 // Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.) 1079 int stride_of_possible_iv( Node* iff ); 1080 bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; } 1081 // Return the (unique) control output node that's in the loop (if it exists.) 1082 Node* stay_in_loop( Node* n, IdealLoopTree *loop); 1083 // Insert a signed compare loop exit cloned from an unsigned compare. 1084 IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop); 1085 void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop); 1086 // Utility to register node "n" with PhaseIdealLoop 1087 void register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth); 1088 // Utility to create an if-projection 1089 ProjNode* proj_clone(ProjNode* p, IfNode* iff); 1090 // Force the iff control output to be the live_proj 1091 Node* short_circuit_if(IfNode* iff, ProjNode* live_proj); 1092 // Insert a region before an if projection 1093 RegionNode* insert_region_before_proj(ProjNode* proj); 1094 // Insert a new if before an if projection 1095 ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj); 1096 1097 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps. 1098 // "Nearly" because all Nodes have been cloned from the original in the loop, 1099 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs 1100 // through the Phi recursively, and return a Bool. 1101 BoolNode *clone_iff( PhiNode *phi, IdealLoopTree *loop ); 1102 CmpNode *clone_bool( PhiNode *phi, IdealLoopTree *loop ); 1103 1104 1105 // Rework addressing expressions to get the most loop-invariant stuff 1106 // moved out. We'd like to do all associative operators, but it's especially 1107 // important (common) to do address expressions. 1108 Node *remix_address_expressions( Node *n ); 1109 1110 // Attempt to use a conditional move instead of a phi/branch 1111 Node *conditional_move( Node *n ); 1112 1113 // Reorganize offset computations to lower register pressure. 1114 // Mostly prevent loop-fallout uses of the pre-incremented trip counter 1115 // (which are then alive with the post-incremented trip counter 1116 // forcing an extra register move) 1117 void reorg_offsets( IdealLoopTree *loop ); 1118 1119 // Check for aggressive application of 'split-if' optimization, 1120 // using basic block level info. 1121 void split_if_with_blocks ( VectorSet &visited, Node_Stack &nstack ); 1122 Node *split_if_with_blocks_pre ( Node *n ); 1123 void split_if_with_blocks_post( Node *n ); 1124 Node *has_local_phi_input( Node *n ); 1125 // Mark an IfNode as being dominated by a prior test, 1126 // without actually altering the CFG (and hence IDOM info). 1127 void dominated_by( Node *prevdom, Node *iff, bool flip = false, bool exclude_loop_predicate = false ); 1128 1129 // Split Node 'n' through merge point 1130 Node *split_thru_region( Node *n, Node *region ); 1131 // Split Node 'n' through merge point if there is enough win. 1132 Node *split_thru_phi( Node *n, Node *region, int policy ); 1133 // Found an If getting its condition-code input from a Phi in the 1134 // same block. Split thru the Region. 1135 void do_split_if( Node *iff ); 1136 1137 // Conversion of fill/copy patterns into intrisic versions 1138 bool do_intrinsify_fill(); 1139 bool intrinsify_fill(IdealLoopTree* lpt); 1140 bool match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value, 1141 Node*& shift, Node*& offset); 1142 1143 private: 1144 // Return a type based on condition control flow 1145 const TypeInt* filtered_type( Node *n, Node* n_ctrl); 1146 const TypeInt* filtered_type( Node *n ) { return filtered_type(n, NULL); } 1147 // Helpers for filtered type 1148 const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl); 1149 1150 // Helper functions 1151 Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache ); 1152 Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true ); 1153 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 ); 1154 bool split_up( Node *n, Node *blk1, Node *blk2 ); 1155 void sink_use( Node *use, Node *post_loop ); 1156 Node *place_near_use( Node *useblock ) const; 1157 Node* try_move_store_before_loop(Node* n, Node *n_ctrl); 1158 void try_move_store_after_loop(Node* n); 1159 bool identical_backtoback_ifs(Node *n); 1160 bool can_split_if(Node *n_ctrl); 1161 1162 bool _created_loop_node; 1163 public: 1164 void set_created_loop_node() { _created_loop_node = true; } 1165 bool created_loop_node() { return _created_loop_node; } 1166 void register_new_node( Node *n, Node *blk ); 1167 1168 #ifdef ASSERT 1169 void dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA); 1170 #endif 1171 1172 #ifndef PRODUCT 1173 void dump( ) const; 1174 void dump( IdealLoopTree *loop, uint rpo_idx, Node_List &rpo_list ) const; 1175 void rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const; 1176 void verify() const; // Major slow :-) 1177 void verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const; 1178 IdealLoopTree *get_loop_idx(Node* n) const { 1179 // Dead nodes have no loop, so return the top level loop instead 1180 return _nodes[n->_idx] ? (IdealLoopTree*)_nodes[n->_idx] : _ltree_root; 1181 } 1182 // Print some stats 1183 static void print_statistics(); 1184 static int _loop_invokes; // Count of PhaseIdealLoop invokes 1185 static int _loop_work; // Sum of PhaseIdealLoop x _unique 1186 #endif 1187 }; 1188 1189 // This kit may be used for making of a reserved copy of a loop before this loop 1190 // goes under non-reversible changes. 1191 // 1192 // Function create_reserve() creates a reserved copy (clone) of the loop. 1193 // The reserved copy is created by calling 1194 // PhaseIdealLoop::create_reserve_version_of_loop - see there how 1195 // the original and reserved loops are connected in the outer graph. 1196 // If create_reserve succeeded, it returns 'true' and _has_reserved is set to 'true'. 1197 // 1198 // By default the reserved copy (clone) of the loop is created as dead code - it is 1199 // dominated in the outer loop by this node chain: 1200 // intcon(1)->If->IfFalse->reserved_copy. 1201 // The original loop is dominated by the the same node chain but IfTrue projection: 1202 // intcon(0)->If->IfTrue->original_loop. 1203 // 1204 // In this implementation of CountedLoopReserveKit the ctor includes create_reserve() 1205 // and the dtor, checks _use_new value. 1206 // If _use_new == false, it "switches" control to reserved copy of the loop 1207 // by simple replacing of node intcon(1) with node intcon(0). 1208 // 1209 // Here is a proposed example of usage (see also SuperWord::output in superword.cpp). 1210 // 1211 // void CountedLoopReserveKit_example() 1212 // { 1213 // CountedLoopReserveKit lrk((phase, lpt, DoReserveCopy = true); // create local object 1214 // if (DoReserveCopy && !lrk.has_reserved()) { 1215 // return; //failed to create reserved loop copy 1216 // } 1217 // ... 1218 // //something is wrong, switch to original loop 1219 /// if(something_is_wrong) return; // ~CountedLoopReserveKit makes the switch 1220 // ... 1221 // //everything worked ok, return with the newly modified loop 1222 // lrk.use_new(); 1223 // return; // ~CountedLoopReserveKit does nothing once use_new() was called 1224 // } 1225 // 1226 // Keep in mind, that by default if create_reserve() is not followed by use_new() 1227 // the dtor will "switch to the original" loop. 1228 // NOTE. You you modify outside of the original loop this class is no help. 1229 // 1230 class CountedLoopReserveKit { 1231 private: 1232 PhaseIdealLoop* _phase; 1233 IdealLoopTree* _lpt; 1234 LoopNode* _lp; 1235 IfNode* _iff; 1236 LoopNode* _lp_reserved; 1237 bool _has_reserved; 1238 bool _use_new; 1239 const bool _active; //may be set to false in ctor, then the object is dummy 1240 1241 public: 1242 CountedLoopReserveKit(PhaseIdealLoop* phase, IdealLoopTree *loop, bool active); 1243 ~CountedLoopReserveKit(); 1244 void use_new() {_use_new = true;} 1245 void set_iff(IfNode* x) {_iff = x;} 1246 bool has_reserved() const { return _active && _has_reserved;} 1247 private: 1248 bool create_reserve(); 1249 };// class CountedLoopReserveKit 1250 1251 inline Node* IdealLoopTree::tail() { 1252 // Handle lazy update of _tail field 1253 Node *n = _tail; 1254 //while( !n->in(0) ) // Skip dead CFG nodes 1255 //n = n->in(1); 1256 if (n->in(0) == NULL) 1257 n = _phase->get_ctrl(n); 1258 _tail = n; 1259 return n; 1260 } 1261 1262 1263 // Iterate over the loop tree using a preorder, left-to-right traversal. 1264 // 1265 // Example that visits all counted loops from within PhaseIdealLoop 1266 // 1267 // for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) { 1268 // IdealLoopTree* lpt = iter.current(); 1269 // if (!lpt->is_counted()) continue; 1270 // ... 1271 class LoopTreeIterator : public StackObj { 1272 private: 1273 IdealLoopTree* _root; 1274 IdealLoopTree* _curnt; 1275 1276 public: 1277 LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {} 1278 1279 bool done() { return _curnt == NULL; } // Finished iterating? 1280 1281 void next(); // Advance to next loop tree 1282 1283 IdealLoopTree* current() { return _curnt; } // Return current value of iterator. 1284 }; 1285 1286 #endif // SHARE_VM_OPTO_LOOPNODE_HPP