1 /* 2 * Copyright (c) 1998, 2018, 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 OuterStripMinedLoopEndNode; 41 class PhaseIdealLoop; 42 class CountedLoopReserveKit; 43 class VectorSet; 44 class Invariance; 45 struct small_cache; 46 47 // 48 // I D E A L I Z E D L O O P S 49 // 50 // Idealized loops are the set of loops I perform more interesting 51 // transformations on, beyond simple hoisting. 52 53 //------------------------------LoopNode--------------------------------------- 54 // Simple loop header. Fall in path on left, loop-back path on right. 55 class LoopNode : public RegionNode { 56 // Size is bigger to hold the flags. However, the flags do not change 57 // the semantics so it does not appear in the hash & cmp functions. 58 virtual uint size_of() const { return sizeof(*this); } 59 protected: 60 short _loop_flags; 61 // Names for flag bitfields 62 enum { Normal=0, Pre=1, Main=2, Post=3, PreMainPostFlagsMask=3, 63 MainHasNoPreLoop=4, 64 HasExactTripCount=8, 65 InnerLoop=16, 66 PartialPeelLoop=32, 67 PartialPeelFailed=64, 68 HasReductions=128, 69 WasSlpAnalyzed=256, 70 PassedSlpAnalysis=512, 71 DoUnrollOnly=1024, 72 VectorizedLoop=2048, 73 HasAtomicPostLoop=4096, 74 HasRangeChecks=8192, 75 IsMultiversioned=16384, 76 StripMined=32768}; 77 char _unswitch_count; 78 enum { _unswitch_max=3 }; 79 char _postloop_flags; 80 enum { LoopNotRCEChecked = 0, LoopRCEChecked = 1, RCEPostLoop = 2 }; 81 82 public: 83 // Names for edge indices 84 enum { Self=0, EntryControl, LoopBackControl }; 85 86 int is_inner_loop() const { return _loop_flags & InnerLoop; } 87 void set_inner_loop() { _loop_flags |= InnerLoop; } 88 89 int range_checks_present() const { return _loop_flags & HasRangeChecks; } 90 int is_multiversioned() const { return _loop_flags & IsMultiversioned; } 91 int is_vectorized_loop() const { return _loop_flags & VectorizedLoop; } 92 int is_partial_peel_loop() const { return _loop_flags & PartialPeelLoop; } 93 void set_partial_peel_loop() { _loop_flags |= PartialPeelLoop; } 94 int partial_peel_has_failed() const { return _loop_flags & PartialPeelFailed; } 95 int is_strip_mined() const { return _loop_flags & StripMined; } 96 97 void mark_partial_peel_failed() { _loop_flags |= PartialPeelFailed; } 98 void mark_has_reductions() { _loop_flags |= HasReductions; } 99 void mark_was_slp() { _loop_flags |= WasSlpAnalyzed; } 100 void mark_passed_slp() { _loop_flags |= PassedSlpAnalysis; } 101 void mark_do_unroll_only() { _loop_flags |= DoUnrollOnly; } 102 void mark_loop_vectorized() { _loop_flags |= VectorizedLoop; } 103 void mark_has_atomic_post_loop() { _loop_flags |= HasAtomicPostLoop; } 104 void mark_has_range_checks() { _loop_flags |= HasRangeChecks; } 105 void mark_is_multiversioned() { _loop_flags |= IsMultiversioned; } 106 void mark_strip_mined() { _loop_flags |= StripMined; } 107 void clear_strip_mined() { _loop_flags &= ~StripMined; } 108 109 int unswitch_max() { return _unswitch_max; } 110 int unswitch_count() { return _unswitch_count; } 111 112 int has_been_range_checked() const { return _postloop_flags & LoopRCEChecked; } 113 void set_has_been_range_checked() { _postloop_flags |= LoopRCEChecked; } 114 int is_rce_post_loop() const { return _postloop_flags & RCEPostLoop; } 115 void set_is_rce_post_loop() { _postloop_flags |= RCEPostLoop; } 116 117 void set_unswitch_count(int val) { 118 assert (val <= unswitch_max(), "too many unswitches"); 119 _unswitch_count = val; 120 } 121 122 LoopNode(Node *entry, Node *backedge) : RegionNode(3), _loop_flags(0), _unswitch_count(0), _postloop_flags(0) { 123 init_class_id(Class_Loop); 124 init_req(EntryControl, entry); 125 init_req(LoopBackControl, backedge); 126 } 127 128 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); 129 virtual int Opcode() const; 130 bool can_be_counted_loop(PhaseTransform* phase) const { 131 return req() == 3 && in(0) != NULL && 132 in(1) != NULL && phase->type(in(1)) != Type::TOP && 133 in(2) != NULL && phase->type(in(2)) != Type::TOP; 134 } 135 bool is_valid_counted_loop() const; 136 #ifndef PRODUCT 137 virtual void dump_spec(outputStream *st) const; 138 #endif 139 140 void verify_strip_mined(int expect_skeleton) const; 141 virtual LoopNode* skip_strip_mined(int expect_skeleton = 1) { return this; } 142 virtual IfTrueNode* outer_loop_tail() const { ShouldNotReachHere(); return NULL; } 143 virtual OuterStripMinedLoopEndNode* outer_loop_end() const { ShouldNotReachHere(); return NULL; } 144 virtual IfFalseNode* outer_loop_exit() const { ShouldNotReachHere(); return NULL; } 145 virtual SafePointNode* outer_safepoint() const { ShouldNotReachHere(); return NULL; } 146 }; 147 148 //------------------------------Counted Loops---------------------------------- 149 // Counted loops are all trip-counted loops, with exactly 1 trip-counter exit 150 // path (and maybe some other exit paths). The trip-counter exit is always 151 // last in the loop. The trip-counter have to stride by a constant; 152 // the exit value is also loop invariant. 153 154 // CountedLoopNodes and CountedLoopEndNodes come in matched pairs. The 155 // CountedLoopNode has the incoming loop control and the loop-back-control 156 // which is always the IfTrue before the matching CountedLoopEndNode. The 157 // CountedLoopEndNode has an incoming control (possibly not the 158 // CountedLoopNode if there is control flow in the loop), the post-increment 159 // trip-counter value, and the limit. The trip-counter value is always of 160 // the form (Op old-trip-counter stride). The old-trip-counter is produced 161 // by a Phi connected to the CountedLoopNode. The stride is constant. 162 // The Op is any commutable opcode, including Add, Mul, Xor. The 163 // CountedLoopEndNode also takes in the loop-invariant limit value. 164 165 // From a CountedLoopNode I can reach the matching CountedLoopEndNode via the 166 // loop-back control. From CountedLoopEndNodes I can reach CountedLoopNodes 167 // via the old-trip-counter from the Op node. 168 169 //------------------------------CountedLoopNode-------------------------------- 170 // CountedLoopNodes head simple counted loops. CountedLoopNodes have as 171 // inputs the incoming loop-start control and the loop-back control, so they 172 // act like RegionNodes. They also take in the initial trip counter, the 173 // loop-invariant stride and the loop-invariant limit value. CountedLoopNodes 174 // produce a loop-body control and the trip counter value. Since 175 // CountedLoopNodes behave like RegionNodes I still have a standard CFG model. 176 177 class CountedLoopNode : public LoopNode { 178 // Size is bigger to hold _main_idx. However, _main_idx does not change 179 // the semantics so it does not appear in the hash & cmp functions. 180 virtual uint size_of() const { return sizeof(*this); } 181 182 // For Pre- and Post-loops during debugging ONLY, this holds the index of 183 // the Main CountedLoop. Used to assert that we understand the graph shape. 184 node_idx_t _main_idx; 185 186 // Known trip count calculated by compute_exact_trip_count() 187 uint _trip_count; 188 189 // Expected trip count from profile data 190 float _profile_trip_cnt; 191 192 // Log2 of original loop bodies in unrolled loop 193 int _unrolled_count_log2; 194 195 // Node count prior to last unrolling - used to decide if 196 // unroll,optimize,unroll,optimize,... is making progress 197 int _node_count_before_unroll; 198 199 // If slp analysis is performed we record the maximum 200 // vector mapped unroll factor here 201 int _slp_maximum_unroll_factor; 202 203 public: 204 CountedLoopNode( Node *entry, Node *backedge ) 205 : LoopNode(entry, backedge), _main_idx(0), _trip_count(max_juint), 206 _profile_trip_cnt(COUNT_UNKNOWN), _unrolled_count_log2(0), 207 _node_count_before_unroll(0), _slp_maximum_unroll_factor(0) { 208 init_class_id(Class_CountedLoop); 209 // Initialize _trip_count to the largest possible value. 210 // Will be reset (lower) if the loop's trip count is known. 211 } 212 213 virtual int Opcode() const; 214 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); 215 216 Node *init_control() const { return in(EntryControl); } 217 Node *back_control() const { return in(LoopBackControl); } 218 CountedLoopEndNode *loopexit_or_null() const; 219 CountedLoopEndNode *loopexit() const; 220 Node *init_trip() const; 221 Node *stride() const; 222 int stride_con() const; 223 bool stride_is_con() const; 224 Node *limit() const; 225 Node *incr() const; 226 Node *phi() const; 227 228 // Match increment with optional truncation 229 static Node* match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type); 230 231 // A 'main' loop has a pre-loop and a post-loop. The 'main' loop 232 // can run short a few iterations and may start a few iterations in. 233 // It will be RCE'd and unrolled and aligned. 234 235 // A following 'post' loop will run any remaining iterations. Used 236 // during Range Check Elimination, the 'post' loop will do any final 237 // iterations with full checks. Also used by Loop Unrolling, where 238 // the 'post' loop will do any epilog iterations needed. Basically, 239 // a 'post' loop can not profitably be further unrolled or RCE'd. 240 241 // A preceding 'pre' loop will run at least 1 iteration (to do peeling), 242 // it may do under-flow checks for RCE and may do alignment iterations 243 // so the following main loop 'knows' that it is striding down cache 244 // lines. 245 246 // A 'main' loop that is ONLY unrolled or peeled, never RCE'd or 247 // Aligned, may be missing it's pre-loop. 248 int is_normal_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Normal; } 249 int is_pre_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Pre; } 250 int is_main_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Main; } 251 int is_post_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Post; } 252 int is_reduction_loop() const { return (_loop_flags&HasReductions) == HasReductions; } 253 int was_slp_analyzed () const { return (_loop_flags&WasSlpAnalyzed) == WasSlpAnalyzed; } 254 int has_passed_slp () const { return (_loop_flags&PassedSlpAnalysis) == PassedSlpAnalysis; } 255 int do_unroll_only () const { return (_loop_flags&DoUnrollOnly) == DoUnrollOnly; } 256 int is_main_no_pre_loop() const { return _loop_flags & MainHasNoPreLoop; } 257 int has_atomic_post_loop () const { return (_loop_flags & HasAtomicPostLoop) == HasAtomicPostLoop; } 258 void set_main_no_pre_loop() { _loop_flags |= MainHasNoPreLoop; } 259 260 int main_idx() const { return _main_idx; } 261 262 263 void set_pre_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; } 264 void set_main_loop ( ) { assert(is_normal_loop(),""); _loop_flags |= Main; } 265 void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; } 266 void set_normal_loop( ) { _loop_flags &= ~PreMainPostFlagsMask; } 267 268 void set_trip_count(uint tc) { _trip_count = tc; } 269 uint trip_count() { return _trip_count; } 270 271 bool has_exact_trip_count() const { return (_loop_flags & HasExactTripCount) != 0; } 272 void set_exact_trip_count(uint tc) { 273 _trip_count = tc; 274 _loop_flags |= HasExactTripCount; 275 } 276 void set_nonexact_trip_count() { 277 _loop_flags &= ~HasExactTripCount; 278 } 279 void set_notpassed_slp() { 280 _loop_flags &= ~PassedSlpAnalysis; 281 } 282 283 void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; } 284 float profile_trip_cnt() { return _profile_trip_cnt; } 285 286 void double_unrolled_count() { _unrolled_count_log2++; } 287 int unrolled_count() { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); } 288 289 void set_node_count_before_unroll(int ct) { _node_count_before_unroll = ct; } 290 int node_count_before_unroll() { return _node_count_before_unroll; } 291 void set_slp_max_unroll(int unroll_factor) { _slp_maximum_unroll_factor = unroll_factor; } 292 int slp_max_unroll() const { return _slp_maximum_unroll_factor; } 293 294 virtual LoopNode* skip_strip_mined(int expect_opaq = 1); 295 OuterStripMinedLoopNode* outer_loop() const; 296 virtual IfTrueNode* outer_loop_tail() const; 297 virtual OuterStripMinedLoopEndNode* outer_loop_end() const; 298 virtual IfFalseNode* outer_loop_exit() const; 299 virtual SafePointNode* outer_safepoint() const; 300 301 // If this is a main loop in a pre/main/post loop nest, walk over 302 // the predicates that were inserted by 303 // duplicate_predicates()/add_range_check_predicate() 304 Node* skip_predicates(); 305 306 #ifndef PRODUCT 307 virtual void dump_spec(outputStream *st) const; 308 #endif 309 }; 310 311 //------------------------------CountedLoopEndNode----------------------------- 312 // CountedLoopEndNodes end simple trip counted loops. They act much like 313 // IfNodes. 314 class CountedLoopEndNode : public IfNode { 315 public: 316 enum { TestControl, TestValue }; 317 318 CountedLoopEndNode( Node *control, Node *test, float prob, float cnt ) 319 : IfNode( control, test, prob, cnt) { 320 init_class_id(Class_CountedLoopEnd); 321 } 322 virtual int Opcode() const; 323 324 Node *cmp_node() const { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : NULL; } 325 Node *incr() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; } 326 Node *limit() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; } 327 Node *stride() const { Node *tmp = incr (); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; } 328 Node *init_trip() const { Node *tmp = phi (); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; } 329 int stride_con() const; 330 bool stride_is_con() const { Node *tmp = stride (); return (tmp != NULL && tmp->is_Con()); } 331 BoolTest::mask test_trip() const { return in(TestValue)->as_Bool()->_test._test; } 332 PhiNode *phi() const { 333 Node *tmp = incr(); 334 if (tmp && tmp->req() == 3) { 335 Node* phi = tmp->in(1); 336 if (phi->is_Phi()) { 337 return phi->as_Phi(); 338 } 339 } 340 return NULL; 341 } 342 CountedLoopNode *loopnode() const { 343 // The CountedLoopNode that goes with this CountedLoopEndNode may 344 // have been optimized out by the IGVN so be cautious with the 345 // pattern matching on the graph 346 PhiNode* iv_phi = phi(); 347 if (iv_phi == NULL) { 348 return NULL; 349 } 350 Node *ln = iv_phi->in(0); 351 if (ln->is_CountedLoop() && ln->as_CountedLoop()->loopexit_or_null() == this) { 352 return (CountedLoopNode*)ln; 353 } 354 return NULL; 355 } 356 357 #ifndef PRODUCT 358 virtual void dump_spec(outputStream *st) const; 359 #endif 360 }; 361 362 363 inline CountedLoopEndNode *CountedLoopNode::loopexit_or_null() const { 364 Node *bc = back_control(); 365 if( bc == NULL ) return NULL; 366 Node *le = bc->in(0); 367 if( le->Opcode() != Op_CountedLoopEnd ) 368 return NULL; 369 return (CountedLoopEndNode*)le; 370 } 371 inline CountedLoopEndNode *CountedLoopNode::loopexit() const { 372 CountedLoopEndNode* cle = loopexit_or_null(); 373 assert(cle != NULL, "loopexit is NULL"); 374 return cle; 375 } 376 inline Node *CountedLoopNode::init_trip() const { return loopexit_or_null() ? loopexit()->init_trip() : NULL; } 377 inline Node *CountedLoopNode::stride() const { return loopexit_or_null() ? loopexit()->stride() : NULL; } 378 inline int CountedLoopNode::stride_con() const { return loopexit_or_null() ? loopexit()->stride_con() : 0; } 379 inline bool CountedLoopNode::stride_is_con() const { return loopexit_or_null() && loopexit()->stride_is_con(); } 380 inline Node *CountedLoopNode::limit() const { return loopexit_or_null() ? loopexit()->limit() : NULL; } 381 inline Node *CountedLoopNode::incr() const { return loopexit_or_null() ? loopexit()->incr() : NULL; } 382 inline Node *CountedLoopNode::phi() const { return loopexit_or_null() ? loopexit()->phi() : NULL; } 383 384 //------------------------------LoopLimitNode----------------------------- 385 // Counted Loop limit node which represents exact final iterator value: 386 // trip_count = (limit - init_trip + stride - 1)/stride 387 // final_value= trip_count * stride + init_trip. 388 // Use HW instructions to calculate it when it can overflow in integer. 389 // Note, final_value should fit into integer since counted loop has 390 // limit check: limit <= max_int-stride. 391 class LoopLimitNode : public Node { 392 enum { Init=1, Limit=2, Stride=3 }; 393 public: 394 LoopLimitNode( Compile* C, Node *init, Node *limit, Node *stride ) : Node(0,init,limit,stride) { 395 // Put it on the Macro nodes list to optimize during macro nodes expansion. 396 init_flags(Flag_is_macro); 397 C->add_macro_node(this); 398 } 399 virtual int Opcode() const; 400 virtual const Type *bottom_type() const { return TypeInt::INT; } 401 virtual uint ideal_reg() const { return Op_RegI; } 402 virtual const Type* Value(PhaseGVN* phase) const; 403 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); 404 virtual Node* Identity(PhaseGVN* phase); 405 }; 406 407 // Support for strip mining 408 class OuterStripMinedLoopNode : public LoopNode { 409 private: 410 CountedLoopNode* inner_loop() const; 411 public: 412 OuterStripMinedLoopNode(Compile* C, Node *entry, Node *backedge) 413 : LoopNode(entry, backedge) { 414 init_class_id(Class_OuterStripMinedLoop); 415 init_flags(Flag_is_macro); 416 C->add_macro_node(this); 417 } 418 419 virtual int Opcode() const; 420 421 virtual IfTrueNode* outer_loop_tail() const; 422 virtual OuterStripMinedLoopEndNode* outer_loop_end() const; 423 virtual IfFalseNode* outer_loop_exit() const; 424 virtual SafePointNode* outer_safepoint() const; 425 void adjust_strip_mined_loop(PhaseIterGVN* igvn); 426 }; 427 428 class OuterStripMinedLoopEndNode : public IfNode { 429 public: 430 OuterStripMinedLoopEndNode(Node *control, Node *test, float prob, float cnt) 431 : IfNode(control, test, prob, cnt) { 432 init_class_id(Class_OuterStripMinedLoopEnd); 433 } 434 435 virtual int Opcode() const; 436 437 virtual const Type* Value(PhaseGVN* phase) const; 438 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); 439 }; 440 441 // -----------------------------IdealLoopTree---------------------------------- 442 class IdealLoopTree : public ResourceObj { 443 public: 444 IdealLoopTree *_parent; // Parent in loop tree 445 IdealLoopTree *_next; // Next sibling in loop tree 446 IdealLoopTree *_child; // First child in loop tree 447 448 // The head-tail backedge defines the loop. 449 // If tail is NULL then this loop has multiple backedges as part of the 450 // same loop. During cleanup I'll peel off the multiple backedges; merge 451 // them at the loop bottom and flow 1 real backedge into the loop. 452 Node *_head; // Head of loop 453 Node *_tail; // Tail of loop 454 inline Node *tail(); // Handle lazy update of _tail field 455 PhaseIdealLoop* _phase; 456 int _local_loop_unroll_limit; 457 int _local_loop_unroll_factor; 458 459 Node_List _body; // Loop body for inner loops 460 461 uint8_t _nest; // Nesting depth 462 uint8_t _irreducible:1, // True if irreducible 463 _has_call:1, // True if has call safepoint 464 _has_sfpt:1, // True if has non-call safepoint 465 _rce_candidate:1; // True if candidate for range check elimination 466 467 Node_List* _safepts; // List of safepoints in this loop 468 Node_List* _required_safept; // A inner loop cannot delete these safepts; 469 bool _allow_optimizations; // Allow loop optimizations 470 471 IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail ) 472 : _parent(0), _next(0), _child(0), 473 _head(head), _tail(tail), 474 _phase(phase), 475 _safepts(NULL), 476 _required_safept(NULL), 477 _allow_optimizations(true), 478 _nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0), 479 _local_loop_unroll_limit(0), _local_loop_unroll_factor(0) 480 { } 481 482 // Is 'l' a member of 'this'? 483 bool is_member(const IdealLoopTree *l) const; // Test for nested membership 484 485 // Set loop nesting depth. Accumulate has_call bits. 486 int set_nest( uint depth ); 487 488 // Split out multiple fall-in edges from the loop header. Move them to a 489 // private RegionNode before the loop. This becomes the loop landing pad. 490 void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ); 491 492 // Split out the outermost loop from this shared header. 493 void split_outer_loop( PhaseIdealLoop *phase ); 494 495 // Merge all the backedges from the shared header into a private Region. 496 // Feed that region as the one backedge to this loop. 497 void merge_many_backedges( PhaseIdealLoop *phase ); 498 499 // Split shared headers and insert loop landing pads. 500 // Insert a LoopNode to replace the RegionNode. 501 // Returns TRUE if loop tree is structurally changed. 502 bool beautify_loops( PhaseIdealLoop *phase ); 503 504 // Perform optimization to use the loop predicates for null checks and range checks. 505 // Applies to any loop level (not just the innermost one) 506 bool loop_predication( PhaseIdealLoop *phase); 507 508 // Perform iteration-splitting on inner loops. Split iterations to 509 // avoid range checks or one-shot null checks. Returns false if the 510 // current round of loop opts should stop. 511 bool iteration_split( PhaseIdealLoop *phase, Node_List &old_new ); 512 513 // Driver for various flavors of iteration splitting. Returns false 514 // if the current round of loop opts should stop. 515 bool iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new ); 516 517 // Given dominators, try to find loops with calls that must always be 518 // executed (call dominates loop tail). These loops do not need non-call 519 // safepoints (ncsfpt). 520 void check_safepts(VectorSet &visited, Node_List &stack); 521 522 // Allpaths backwards scan from loop tail, terminating each path at first safepoint 523 // encountered. 524 void allpaths_check_safepts(VectorSet &visited, Node_List &stack); 525 526 // Remove safepoints from loop. Optionally keeping one. 527 void remove_safepoints(PhaseIdealLoop* phase, bool keep_one); 528 529 // Convert to counted loops where possible 530 void counted_loop( PhaseIdealLoop *phase ); 531 532 // Check for Node being a loop-breaking test 533 Node *is_loop_exit(Node *iff) const; 534 535 // Remove simplistic dead code from loop body 536 void DCE_loop_body(); 537 538 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage. 539 // Replace with a 1-in-10 exit guess. 540 void adjust_loop_exit_prob( PhaseIdealLoop *phase ); 541 542 // Return TRUE or FALSE if the loop should never be RCE'd or aligned. 543 // Useful for unrolling loops with NO array accesses. 544 bool policy_peel_only( PhaseIdealLoop *phase ) const; 545 546 // Return TRUE or FALSE if the loop should be unswitched -- clone 547 // loop with an invariant test 548 bool policy_unswitching( PhaseIdealLoop *phase ) const; 549 550 // Micro-benchmark spamming. Remove empty loops. 551 bool policy_do_remove_empty_loop( PhaseIdealLoop *phase ); 552 553 // Convert one iteration loop into normal code. 554 bool policy_do_one_iteration_loop( PhaseIdealLoop *phase ); 555 556 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can 557 // make some loop-invariant test (usually a null-check) happen before the 558 // loop. 559 bool policy_peeling( PhaseIdealLoop *phase ) const; 560 561 // Return TRUE or FALSE if the loop should be maximally unrolled. Stash any 562 // known trip count in the counted loop node. 563 bool policy_maximally_unroll( PhaseIdealLoop *phase ) const; 564 565 // Return TRUE or FALSE if the loop should be unrolled or not. Unroll if 566 // the loop is a CountedLoop and the body is small enough. 567 bool policy_unroll(PhaseIdealLoop *phase); 568 569 // Loop analyses to map to a maximal superword unrolling for vectorization. 570 void policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_ct); 571 572 // Return TRUE or FALSE if the loop should be range-check-eliminated. 573 // Gather a list of IF tests that are dominated by iteration splitting; 574 // also gather the end of the first split and the start of the 2nd split. 575 bool policy_range_check( PhaseIdealLoop *phase ) const; 576 577 // Return TRUE or FALSE if the loop should be cache-line aligned. 578 // Gather the expression that does the alignment. Note that only 579 // one array base can be aligned in a loop (unless the VM guarantees 580 // mutual alignment). Note that if we vectorize short memory ops 581 // into longer memory ops, we may want to increase alignment. 582 bool policy_align( PhaseIdealLoop *phase ) const; 583 584 // Return TRUE if "iff" is a range check. 585 bool is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const; 586 587 // Compute loop trip count if possible 588 void compute_trip_count(PhaseIdealLoop* phase); 589 590 // Compute loop trip count from profile data 591 void compute_profile_trip_cnt( PhaseIdealLoop *phase ); 592 593 // Reassociate invariant expressions. 594 void reassociate_invariants(PhaseIdealLoop *phase); 595 // Reassociate invariant add and subtract expressions. 596 Node* reassociate_add_sub(Node* n1, PhaseIdealLoop *phase); 597 // Return nonzero index of invariant operand if invariant and variant 598 // are combined with an Add or Sub. Helper for reassociate_invariants. 599 int is_invariant_addition(Node* n, PhaseIdealLoop *phase); 600 601 // Return true if n is invariant 602 bool is_invariant(Node* n) const; 603 604 // Put loop body on igvn work list 605 void record_for_igvn(); 606 607 bool is_loop() { return !_irreducible && _tail && !_tail->is_top(); } 608 bool is_inner() { return is_loop() && _child == NULL; } 609 bool is_counted() { return is_loop() && _head != NULL && _head->is_CountedLoop(); } 610 611 void remove_main_post_loops(CountedLoopNode *cl, PhaseIdealLoop *phase); 612 613 #ifndef PRODUCT 614 void dump_head( ) const; // Dump loop head only 615 void dump() const; // Dump this loop recursively 616 void verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const; 617 #endif 618 619 }; 620 621 // -----------------------------PhaseIdealLoop--------------------------------- 622 // Computes the mapping from Nodes to IdealLoopTrees. Organizes IdealLoopTrees into a 623 // loop tree. Drives the loop-based transformations on the ideal graph. 624 class PhaseIdealLoop : public PhaseTransform { 625 friend class IdealLoopTree; 626 friend class SuperWord; 627 friend class CountedLoopReserveKit; 628 629 // Pre-computed def-use info 630 PhaseIterGVN &_igvn; 631 632 // Head of loop tree 633 IdealLoopTree *_ltree_root; 634 635 // Array of pre-order numbers, plus post-visited bit. 636 // ZERO for not pre-visited. EVEN for pre-visited but not post-visited. 637 // ODD for post-visited. Other bits are the pre-order number. 638 uint *_preorders; 639 uint _max_preorder; 640 641 const PhaseIdealLoop* _verify_me; 642 bool _verify_only; 643 644 // Allocate _preorders[] array 645 void allocate_preorders() { 646 _max_preorder = C->unique()+8; 647 _preorders = NEW_RESOURCE_ARRAY(uint, _max_preorder); 648 memset(_preorders, 0, sizeof(uint) * _max_preorder); 649 } 650 651 // Allocate _preorders[] array 652 void reallocate_preorders() { 653 if ( _max_preorder < C->unique() ) { 654 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique()); 655 _max_preorder = C->unique(); 656 } 657 memset(_preorders, 0, sizeof(uint) * _max_preorder); 658 } 659 660 // Check to grow _preorders[] array for the case when build_loop_tree_impl() 661 // adds new nodes. 662 void check_grow_preorders( ) { 663 if ( _max_preorder < C->unique() ) { 664 uint newsize = _max_preorder<<1; // double size of array 665 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize); 666 memset(&_preorders[_max_preorder],0,sizeof(uint)*(newsize-_max_preorder)); 667 _max_preorder = newsize; 668 } 669 } 670 // Check for pre-visited. Zero for NOT visited; non-zero for visited. 671 int is_visited( Node *n ) const { return _preorders[n->_idx]; } 672 // Pre-order numbers are written to the Nodes array as low-bit-set values. 673 void set_preorder_visited( Node *n, int pre_order ) { 674 assert( !is_visited( n ), "already set" ); 675 _preorders[n->_idx] = (pre_order<<1); 676 }; 677 // Return pre-order number. 678 int get_preorder( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]>>1; } 679 680 // Check for being post-visited. 681 // Should be previsited already (checked with assert(is_visited(n))). 682 int is_postvisited( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]&1; } 683 684 // Mark as post visited 685 void set_postvisited( Node *n ) { assert( !is_postvisited( n ), "" ); _preorders[n->_idx] |= 1; } 686 687 public: 688 // Set/get control node out. Set lower bit to distinguish from IdealLoopTree 689 // Returns true if "n" is a data node, false if it's a control node. 690 bool has_ctrl( Node *n ) const { return ((intptr_t)_nodes[n->_idx]) & 1; } 691 692 private: 693 // clear out dead code after build_loop_late 694 Node_List _deadlist; 695 696 // Support for faster execution of get_late_ctrl()/dom_lca() 697 // when a node has many uses and dominator depth is deep. 698 Node_Array _dom_lca_tags; 699 void init_dom_lca_tags(); 700 void clear_dom_lca_tags(); 701 702 // Helper for debugging bad dominance relationships 703 bool verify_dominance(Node* n, Node* use, Node* LCA, Node* early); 704 705 Node* compute_lca_of_uses(Node* n, Node* early, bool verify = false); 706 707 // Inline wrapper for frequent cases: 708 // 1) only one use 709 // 2) a use is the same as the current LCA passed as 'n1' 710 Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) { 711 assert( n->is_CFG(), "" ); 712 // Fast-path NULL lca 713 if( lca != NULL && lca != n ) { 714 assert( lca->is_CFG(), "" ); 715 // find LCA of all uses 716 n = dom_lca_for_get_late_ctrl_internal( lca, n, tag ); 717 } 718 return find_non_split_ctrl(n); 719 } 720 Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag ); 721 722 // Helper function for directing control inputs away from CFG split 723 // points. 724 Node *find_non_split_ctrl( Node *ctrl ) const { 725 if (ctrl != NULL) { 726 if (ctrl->is_MultiBranch()) { 727 ctrl = ctrl->in(0); 728 } 729 assert(ctrl->is_CFG(), "CFG"); 730 } 731 return ctrl; 732 } 733 734 Node* cast_incr_before_loop(Node* incr, Node* ctrl, Node* loop); 735 void duplicate_predicates(CountedLoopNode* pre_head, Node *min_taken, Node* castii, 736 IdealLoopTree* outer_loop, LoopNode* outer_main_head, 737 uint dd_main_head); 738 739 public: 740 741 PhaseIterGVN &igvn() const { return _igvn; } 742 743 static bool is_canonical_loop_entry(CountedLoopNode* cl); 744 745 bool has_node( Node* n ) const { 746 guarantee(n != NULL, "No Node."); 747 return _nodes[n->_idx] != NULL; 748 } 749 // check if transform created new nodes that need _ctrl recorded 750 Node *get_late_ctrl( Node *n, Node *early ); 751 Node *get_early_ctrl( Node *n ); 752 Node *get_early_ctrl_for_expensive(Node *n, Node* earliest); 753 void set_early_ctrl( Node *n ); 754 void set_subtree_ctrl( Node *root ); 755 void set_ctrl( Node *n, Node *ctrl ) { 756 assert( !has_node(n) || has_ctrl(n), "" ); 757 assert( ctrl->in(0), "cannot set dead control node" ); 758 assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" ); 759 _nodes.map( n->_idx, (Node*)((intptr_t)ctrl + 1) ); 760 } 761 // Set control and update loop membership 762 void set_ctrl_and_loop(Node* n, Node* ctrl) { 763 IdealLoopTree* old_loop = get_loop(get_ctrl(n)); 764 IdealLoopTree* new_loop = get_loop(ctrl); 765 if (old_loop != new_loop) { 766 if (old_loop->_child == NULL) old_loop->_body.yank(n); 767 if (new_loop->_child == NULL) new_loop->_body.push(n); 768 } 769 set_ctrl(n, ctrl); 770 } 771 // Control nodes can be replaced or subsumed. During this pass they 772 // get their replacement Node in slot 1. Instead of updating the block 773 // location of all Nodes in the subsumed block, we lazily do it. As we 774 // pull such a subsumed block out of the array, we write back the final 775 // correct block. 776 Node *get_ctrl( Node *i ) { 777 assert(has_node(i), ""); 778 Node *n = get_ctrl_no_update(i); 779 _nodes.map( i->_idx, (Node*)((intptr_t)n + 1) ); 780 assert(has_node(i) && has_ctrl(i), ""); 781 assert(n == find_non_split_ctrl(n), "must return legal ctrl" ); 782 return n; 783 } 784 // true if CFG node d dominates CFG node n 785 bool is_dominator(Node *d, Node *n); 786 // return get_ctrl for a data node and self(n) for a CFG node 787 Node* ctrl_or_self(Node* n) { 788 if (has_ctrl(n)) 789 return get_ctrl(n); 790 else { 791 assert (n->is_CFG(), "must be a CFG node"); 792 return n; 793 } 794 } 795 796 Node *get_ctrl_no_update_helper(Node *i) const { 797 assert(has_ctrl(i), "should be control, not loop"); 798 return (Node*)(((intptr_t)_nodes[i->_idx]) & ~1); 799 } 800 801 Node *get_ctrl_no_update(Node *i) const { 802 assert( has_ctrl(i), "" ); 803 Node *n = get_ctrl_no_update_helper(i); 804 if (!n->in(0)) { 805 // Skip dead CFG nodes 806 do { 807 n = get_ctrl_no_update_helper(n); 808 } while (!n->in(0)); 809 n = find_non_split_ctrl(n); 810 } 811 return n; 812 } 813 814 // Check for loop being set 815 // "n" must be a control node. Returns true if "n" is known to be in a loop. 816 bool has_loop( Node *n ) const { 817 assert(!has_node(n) || !has_ctrl(n), ""); 818 return has_node(n); 819 } 820 // Set loop 821 void set_loop( Node *n, IdealLoopTree *loop ) { 822 _nodes.map(n->_idx, (Node*)loop); 823 } 824 // Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms. Replace 825 // the 'old_node' with 'new_node'. Kill old-node. Add a reference 826 // from old_node to new_node to support the lazy update. Reference 827 // replaces loop reference, since that is not needed for dead node. 828 void lazy_update(Node *old_node, Node *new_node) { 829 assert(old_node != new_node, "no cycles please"); 830 // Re-use the side array slot for this node to provide the 831 // forwarding pointer. 832 _nodes.map(old_node->_idx, (Node*)((intptr_t)new_node + 1)); 833 } 834 void lazy_replace(Node *old_node, Node *new_node) { 835 _igvn.replace_node(old_node, new_node); 836 lazy_update(old_node, new_node); 837 } 838 839 private: 840 841 // Place 'n' in some loop nest, where 'n' is a CFG node 842 void build_loop_tree(); 843 int build_loop_tree_impl( Node *n, int pre_order ); 844 // Insert loop into the existing loop tree. 'innermost' is a leaf of the 845 // loop tree, not the root. 846 IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost ); 847 848 // Place Data nodes in some loop nest 849 void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ); 850 void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ); 851 void build_loop_late_post ( Node* n ); 852 void verify_strip_mined_scheduling(Node *n, Node* least); 853 854 // Array of immediate dominance info for each CFG node indexed by node idx 855 private: 856 uint _idom_size; 857 Node **_idom; // Array of immediate dominators 858 uint *_dom_depth; // Used for fast LCA test 859 GrowableArray<uint>* _dom_stk; // For recomputation of dom depth 860 861 public: 862 Node* idom_no_update(Node* d) const { 863 assert(d->_idx < _idom_size, "oob"); 864 Node* n = _idom[d->_idx]; 865 assert(n != NULL,"Bad immediate dominator info."); 866 while (n->in(0) == NULL) { // Skip dead CFG nodes 867 //n = n->in(1); 868 n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1); 869 assert(n != NULL,"Bad immediate dominator info."); 870 } 871 return n; 872 } 873 Node *idom(Node* d) const { 874 uint didx = d->_idx; 875 Node *n = idom_no_update(d); 876 _idom[didx] = n; // Lazily remove dead CFG nodes from table. 877 return n; 878 } 879 uint dom_depth(Node* d) const { 880 guarantee(d != NULL, "Null dominator info."); 881 guarantee(d->_idx < _idom_size, ""); 882 return _dom_depth[d->_idx]; 883 } 884 void set_idom(Node* d, Node* n, uint dom_depth); 885 // Locally compute IDOM using dom_lca call 886 Node *compute_idom( Node *region ) const; 887 // Recompute dom_depth 888 void recompute_dom_depth(); 889 890 // Is safept not required by an outer loop? 891 bool is_deleteable_safept(Node* sfpt); 892 893 // Replace parallel induction variable (parallel to trip counter) 894 void replace_parallel_iv(IdealLoopTree *loop); 895 896 // Perform verification that the graph is valid. 897 PhaseIdealLoop( PhaseIterGVN &igvn) : 898 PhaseTransform(Ideal_Loop), 899 _igvn(igvn), 900 _dom_lca_tags(arena()), // Thread::resource_area 901 _verify_me(NULL), 902 _verify_only(true) { 903 build_and_optimize(false, false); 904 } 905 906 // build the loop tree and perform any requested optimizations 907 void build_and_optimize(bool do_split_if, bool skip_loop_opts); 908 909 // Dominators for the sea of nodes 910 void Dominators(); 911 Node *dom_lca( Node *n1, Node *n2 ) const { 912 return find_non_split_ctrl(dom_lca_internal(n1, n2)); 913 } 914 Node *dom_lca_internal( Node *n1, Node *n2 ) const; 915 916 // Compute the Ideal Node to Loop mapping 917 PhaseIdealLoop( PhaseIterGVN &igvn, bool do_split_ifs, bool skip_loop_opts = false) : 918 PhaseTransform(Ideal_Loop), 919 _igvn(igvn), 920 _dom_lca_tags(arena()), // Thread::resource_area 921 _verify_me(NULL), 922 _verify_only(false) { 923 build_and_optimize(do_split_ifs, skip_loop_opts); 924 } 925 926 // Verify that verify_me made the same decisions as a fresh run. 927 PhaseIdealLoop( PhaseIterGVN &igvn, const PhaseIdealLoop *verify_me) : 928 PhaseTransform(Ideal_Loop), 929 _igvn(igvn), 930 _dom_lca_tags(arena()), // Thread::resource_area 931 _verify_me(verify_me), 932 _verify_only(false) { 933 build_and_optimize(false, false); 934 } 935 936 // Build and verify the loop tree without modifying the graph. This 937 // is useful to verify that all inputs properly dominate their uses. 938 static void verify(PhaseIterGVN& igvn) { 939 #ifdef ASSERT 940 PhaseIdealLoop v(igvn); 941 #endif 942 } 943 944 // True if the method has at least 1 irreducible loop 945 bool _has_irreducible_loops; 946 947 // Per-Node transform 948 virtual Node *transform( Node *a_node ) { return 0; } 949 950 bool is_counted_loop(Node* x, IdealLoopTree*& loop); 951 IdealLoopTree* create_outer_strip_mined_loop(BoolNode *test, Node *cmp, Node *init_control, 952 IdealLoopTree* loop, float cl_prob, float le_fcnt, 953 Node*& entry_control, Node*& iffalse); 954 955 Node* exact_limit( IdealLoopTree *loop ); 956 957 // Return a post-walked LoopNode 958 IdealLoopTree *get_loop( Node *n ) const { 959 // Dead nodes have no loop, so return the top level loop instead 960 if (!has_node(n)) return _ltree_root; 961 assert(!has_ctrl(n), ""); 962 return (IdealLoopTree*)_nodes[n->_idx]; 963 } 964 965 IdealLoopTree *ltree_root() const { return _ltree_root; } 966 967 // Is 'n' a (nested) member of 'loop'? 968 int is_member( const IdealLoopTree *loop, Node *n ) const { 969 return loop->is_member(get_loop(n)); } 970 971 // This is the basic building block of the loop optimizations. It clones an 972 // entire loop body. It makes an old_new loop body mapping; with this 973 // mapping you can find the new-loop equivalent to an old-loop node. All 974 // new-loop nodes are exactly equal to their old-loop counterparts, all 975 // edges are the same. All exits from the old-loop now have a RegionNode 976 // that merges the equivalent new-loop path. This is true even for the 977 // normal "loop-exit" condition. All uses of loop-invariant old-loop values 978 // now come from (one or more) Phis that merge their new-loop equivalents. 979 // Parameter side_by_side_idom: 980 // When side_by_size_idom is NULL, the dominator tree is constructed for 981 // the clone loop to dominate the original. Used in construction of 982 // pre-main-post loop sequence. 983 // When nonnull, the clone and original are side-by-side, both are 984 // dominated by the passed in side_by_side_idom node. Used in 985 // construction of unswitched loops. 986 enum CloneLoopMode { 987 IgnoreStripMined = 0, // Only clone inner strip mined loop 988 CloneIncludesStripMined = 1, // clone both inner and outer strip mined loops 989 ControlAroundStripMined = 2 // Only clone inner strip mined loop, 990 // result control flow branches 991 // either to inner clone or outer 992 // strip mined loop. 993 }; 994 void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth, 995 CloneLoopMode mode, Node* side_by_side_idom = NULL); 996 void clone_loop_handle_data_uses(Node* old, Node_List &old_new, 997 IdealLoopTree* loop, IdealLoopTree* companion_loop, 998 Node_List*& split_if_set, Node_List*& split_bool_set, 999 Node_List*& split_cex_set, Node_List& worklist, 1000 uint new_counter, CloneLoopMode mode); 1001 void clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop, 1002 IdealLoopTree* outer_loop, int dd, Node_List &old_new, 1003 Node_List& extra_data_nodes); 1004 1005 // If we got the effect of peeling, either by actually peeling or by 1006 // making a pre-loop which must execute at least once, we can remove 1007 // all loop-invariant dominated tests in the main body. 1008 void peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new ); 1009 1010 // Generate code to do a loop peel for the given loop (and body). 1011 // old_new is a temp array. 1012 void do_peeling( IdealLoopTree *loop, Node_List &old_new ); 1013 1014 // Add pre and post loops around the given loop. These loops are used 1015 // during RCE, unrolling and aligning loops. 1016 void insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only ); 1017 1018 // Add post loop after the given loop. 1019 Node *insert_post_loop(IdealLoopTree *loop, Node_List &old_new, 1020 CountedLoopNode *main_head, CountedLoopEndNode *main_end, 1021 Node *incr, Node *limit, CountedLoopNode *&post_head); 1022 1023 // Add an RCE'd post loop which we will multi-version adapt for run time test path usage 1024 void insert_scalar_rced_post_loop( IdealLoopTree *loop, Node_List &old_new ); 1025 1026 // Add a vector post loop between a vector main loop and the current post loop 1027 void insert_vector_post_loop(IdealLoopTree *loop, Node_List &old_new); 1028 // If Node n lives in the back_ctrl block, we clone a private version of n 1029 // in preheader_ctrl block and return that, otherwise return n. 1030 Node *clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones ); 1031 1032 // Take steps to maximally unroll the loop. Peel any odd iterations, then 1033 // unroll to do double iterations. The next round of major loop transforms 1034 // will repeat till the doubled loop body does all remaining iterations in 1 1035 // pass. 1036 void do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new ); 1037 1038 // Unroll the loop body one step - make each trip do 2 iterations. 1039 void do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip ); 1040 1041 // Mark vector reduction candidates before loop unrolling 1042 void mark_reductions( IdealLoopTree *loop ); 1043 1044 // Return true if exp is a constant times an induction var 1045 bool is_scaled_iv(Node* exp, Node* iv, int* p_scale); 1046 1047 // Return true if exp is a scaled induction var plus (or minus) constant 1048 bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth = 0); 1049 1050 // Create a new if above the uncommon_trap_if_pattern for the predicate to be promoted 1051 ProjNode* create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry, 1052 Deoptimization::DeoptReason reason, 1053 int opcode); 1054 void register_control(Node* n, IdealLoopTree *loop, Node* pred); 1055 1056 // Clone loop predicates to cloned loops (peeled, unswitched) 1057 static ProjNode* clone_predicate(ProjNode* predicate_proj, Node* new_entry, 1058 Deoptimization::DeoptReason reason, 1059 PhaseIdealLoop* loop_phase, 1060 PhaseIterGVN* igvn); 1061 1062 static Node* clone_loop_predicates(Node* old_entry, Node* new_entry, 1063 bool clone_limit_check, 1064 PhaseIdealLoop* loop_phase, 1065 PhaseIterGVN* igvn); 1066 Node* clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check); 1067 1068 static Node* skip_loop_predicates(Node* entry); 1069 1070 // Find a good location to insert a predicate 1071 static ProjNode* find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason); 1072 // Find a predicate 1073 static Node* find_predicate(Node* entry); 1074 // Construct a range check for a predicate if 1075 BoolNode* rc_predicate(IdealLoopTree *loop, Node* ctrl, 1076 int scale, Node* offset, 1077 Node* init, Node* limit, jint stride, 1078 Node* range, bool upper, bool &overflow); 1079 1080 // Implementation of the loop predication to promote checks outside the loop 1081 bool loop_predication_impl(IdealLoopTree *loop); 1082 ProjNode* insert_skeleton_predicate(IfNode* iff, IdealLoopTree *loop, 1083 ProjNode* proj, ProjNode *predicate_proj, 1084 ProjNode* upper_bound_proj, 1085 int scale, Node* offset, 1086 Node* init, Node* limit, jint stride, 1087 Node* rng, bool& overflow); 1088 Node* add_range_check_predicate(IdealLoopTree* loop, CountedLoopNode* cl, 1089 Node* predicate_proj, int scale_con, Node* offset, 1090 Node* limit, jint stride_con); 1091 1092 // Helper function to collect predicate for eliminating the useless ones 1093 void collect_potentially_useful_predicates(IdealLoopTree *loop, Unique_Node_List &predicate_opaque1); 1094 void eliminate_useless_predicates(); 1095 1096 // Change the control input of expensive nodes to allow commoning by 1097 // IGVN when it is guaranteed to not result in a more frequent 1098 // execution of the expensive node. Return true if progress. 1099 bool process_expensive_nodes(); 1100 1101 // Check whether node has become unreachable 1102 bool is_node_unreachable(Node *n) const { 1103 return !has_node(n) || n->is_unreachable(_igvn); 1104 } 1105 1106 // Eliminate range-checks and other trip-counter vs loop-invariant tests. 1107 int do_range_check( IdealLoopTree *loop, Node_List &old_new ); 1108 1109 // Check to see if do_range_check(...) cleaned the main loop of range-checks 1110 void has_range_checks(IdealLoopTree *loop); 1111 1112 // Process post loops which have range checks and try to build a multi-version 1113 // guard to safely determine if we can execute the post loop which was RCE'd. 1114 bool multi_version_post_loops(IdealLoopTree *rce_loop, IdealLoopTree *legacy_loop); 1115 1116 // Cause the rce'd post loop to optimized away, this happens if we cannot complete multiverioning 1117 void poison_rce_post_loop(IdealLoopTree *rce_loop); 1118 1119 // Create a slow version of the loop by cloning the loop 1120 // and inserting an if to select fast-slow versions. 1121 ProjNode* create_slow_version_of_loop(IdealLoopTree *loop, 1122 Node_List &old_new, 1123 int opcode, 1124 CloneLoopMode mode); 1125 1126 // Clone a loop and return the clone head (clone_loop_head). 1127 // Added nodes include int(1), int(0) - disconnected, If, IfTrue, IfFalse, 1128 // This routine was created for usage in CountedLoopReserveKit. 1129 // 1130 // int(1) -> If -> IfTrue -> original_loop_head 1131 // | 1132 // V 1133 // IfFalse -> clone_loop_head (returned by function pointer) 1134 // 1135 LoopNode* create_reserve_version_of_loop(IdealLoopTree *loop, CountedLoopReserveKit* lk); 1136 // Clone loop with an invariant test (that does not exit) and 1137 // insert a clone of the test that selects which version to 1138 // execute. 1139 void do_unswitching (IdealLoopTree *loop, Node_List &old_new); 1140 1141 // Find candidate "if" for unswitching 1142 IfNode* find_unswitching_candidate(const IdealLoopTree *loop) const; 1143 1144 // Range Check Elimination uses this function! 1145 // Constrain the main loop iterations so the affine function: 1146 // low_limit <= scale_con * I + offset < upper_limit 1147 // always holds true. That is, either increase the number of iterations in 1148 // the pre-loop or the post-loop until the condition holds true in the main 1149 // loop. Scale_con, offset and limit are all loop invariant. 1150 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 ); 1151 // Helper function for add_constraint(). 1152 Node* adjust_limit( int stride_con, Node * scale, Node *offset, Node *rc_limit, Node *loop_limit, Node *pre_ctrl ); 1153 1154 // Partially peel loop up through last_peel node. 1155 bool partial_peel( IdealLoopTree *loop, Node_List &old_new ); 1156 1157 // Create a scheduled list of nodes control dependent on ctrl set. 1158 void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched ); 1159 // Has a use in the vector set 1160 bool has_use_in_set( Node* n, VectorSet& vset ); 1161 // Has use internal to the vector set (ie. not in a phi at the loop head) 1162 bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ); 1163 // clone "n" for uses that are outside of loop 1164 int clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ); 1165 // clone "n" for special uses that are in the not_peeled region 1166 void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n, 1167 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ); 1168 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist 1169 void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ); 1170 #ifdef ASSERT 1171 // Validate the loop partition sets: peel and not_peel 1172 bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel ); 1173 // Ensure that uses outside of loop are of the right form 1174 bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list, 1175 uint orig_exit_idx, uint clone_exit_idx); 1176 bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx); 1177 #endif 1178 1179 // Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.) 1180 int stride_of_possible_iv( Node* iff ); 1181 bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; } 1182 // Return the (unique) control output node that's in the loop (if it exists.) 1183 Node* stay_in_loop( Node* n, IdealLoopTree *loop); 1184 // Insert a signed compare loop exit cloned from an unsigned compare. 1185 IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop); 1186 void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop); 1187 // Utility to register node "n" with PhaseIdealLoop 1188 void register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth); 1189 // Utility to create an if-projection 1190 ProjNode* proj_clone(ProjNode* p, IfNode* iff); 1191 // Force the iff control output to be the live_proj 1192 Node* short_circuit_if(IfNode* iff, ProjNode* live_proj); 1193 // Insert a region before an if projection 1194 RegionNode* insert_region_before_proj(ProjNode* proj); 1195 // Insert a new if before an if projection 1196 ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj); 1197 1198 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps. 1199 // "Nearly" because all Nodes have been cloned from the original in the loop, 1200 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs 1201 // through the Phi recursively, and return a Bool. 1202 Node *clone_iff( PhiNode *phi, IdealLoopTree *loop ); 1203 CmpNode *clone_bool( PhiNode *phi, IdealLoopTree *loop ); 1204 1205 1206 // Rework addressing expressions to get the most loop-invariant stuff 1207 // moved out. We'd like to do all associative operators, but it's especially 1208 // important (common) to do address expressions. 1209 Node *remix_address_expressions( Node *n ); 1210 1211 // Attempt to use a conditional move instead of a phi/branch 1212 Node *conditional_move( Node *n ); 1213 1214 // Reorganize offset computations to lower register pressure. 1215 // Mostly prevent loop-fallout uses of the pre-incremented trip counter 1216 // (which are then alive with the post-incremented trip counter 1217 // forcing an extra register move) 1218 void reorg_offsets( IdealLoopTree *loop ); 1219 1220 // Check for aggressive application of 'split-if' optimization, 1221 // using basic block level info. 1222 void split_if_with_blocks ( VectorSet &visited, Node_Stack &nstack ); 1223 Node *split_if_with_blocks_pre ( Node *n ); 1224 void split_if_with_blocks_post( Node *n ); 1225 Node *has_local_phi_input( Node *n ); 1226 // Mark an IfNode as being dominated by a prior test, 1227 // without actually altering the CFG (and hence IDOM info). 1228 void dominated_by( Node *prevdom, Node *iff, bool flip = false, bool exclude_loop_predicate = false ); 1229 1230 // Split Node 'n' through merge point 1231 Node *split_thru_region( Node *n, Node *region ); 1232 // Split Node 'n' through merge point if there is enough win. 1233 Node *split_thru_phi( Node *n, Node *region, int policy ); 1234 // Found an If getting its condition-code input from a Phi in the 1235 // same block. Split thru the Region. 1236 void do_split_if( Node *iff ); 1237 1238 // Conversion of fill/copy patterns into intrisic versions 1239 bool do_intrinsify_fill(); 1240 bool intrinsify_fill(IdealLoopTree* lpt); 1241 bool match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value, 1242 Node*& shift, Node*& offset); 1243 1244 private: 1245 // Return a type based on condition control flow 1246 const TypeInt* filtered_type( Node *n, Node* n_ctrl); 1247 const TypeInt* filtered_type( Node *n ) { return filtered_type(n, NULL); } 1248 // Helpers for filtered type 1249 const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl); 1250 1251 // Helper functions 1252 Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache ); 1253 Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true ); 1254 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 ); 1255 bool split_up( Node *n, Node *blk1, Node *blk2 ); 1256 void sink_use( Node *use, Node *post_loop ); 1257 Node *place_near_use( Node *useblock ) const; 1258 Node* try_move_store_before_loop(Node* n, Node *n_ctrl); 1259 void try_move_store_after_loop(Node* n); 1260 bool identical_backtoback_ifs(Node *n); 1261 bool can_split_if(Node *n_ctrl); 1262 1263 bool _created_loop_node; 1264 public: 1265 void set_created_loop_node() { _created_loop_node = true; } 1266 bool created_loop_node() { return _created_loop_node; } 1267 void register_new_node( Node *n, Node *blk ); 1268 1269 #ifdef ASSERT 1270 void dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA); 1271 #endif 1272 1273 #ifndef PRODUCT 1274 void dump( ) const; 1275 void dump( IdealLoopTree *loop, uint rpo_idx, Node_List &rpo_list ) const; 1276 void rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const; 1277 void verify() const; // Major slow :-) 1278 void verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const; 1279 IdealLoopTree *get_loop_idx(Node* n) const { 1280 // Dead nodes have no loop, so return the top level loop instead 1281 return _nodes[n->_idx] ? (IdealLoopTree*)_nodes[n->_idx] : _ltree_root; 1282 } 1283 // Print some stats 1284 static void print_statistics(); 1285 static int _loop_invokes; // Count of PhaseIdealLoop invokes 1286 static int _loop_work; // Sum of PhaseIdealLoop x _unique 1287 #endif 1288 }; 1289 1290 // This kit may be used for making of a reserved copy of a loop before this loop 1291 // goes under non-reversible changes. 1292 // 1293 // Function create_reserve() creates a reserved copy (clone) of the loop. 1294 // The reserved copy is created by calling 1295 // PhaseIdealLoop::create_reserve_version_of_loop - see there how 1296 // the original and reserved loops are connected in the outer graph. 1297 // If create_reserve succeeded, it returns 'true' and _has_reserved is set to 'true'. 1298 // 1299 // By default the reserved copy (clone) of the loop is created as dead code - it is 1300 // dominated in the outer loop by this node chain: 1301 // intcon(1)->If->IfFalse->reserved_copy. 1302 // The original loop is dominated by the the same node chain but IfTrue projection: 1303 // intcon(0)->If->IfTrue->original_loop. 1304 // 1305 // In this implementation of CountedLoopReserveKit the ctor includes create_reserve() 1306 // and the dtor, checks _use_new value. 1307 // If _use_new == false, it "switches" control to reserved copy of the loop 1308 // by simple replacing of node intcon(1) with node intcon(0). 1309 // 1310 // Here is a proposed example of usage (see also SuperWord::output in superword.cpp). 1311 // 1312 // void CountedLoopReserveKit_example() 1313 // { 1314 // CountedLoopReserveKit lrk((phase, lpt, DoReserveCopy = true); // create local object 1315 // if (DoReserveCopy && !lrk.has_reserved()) { 1316 // return; //failed to create reserved loop copy 1317 // } 1318 // ... 1319 // //something is wrong, switch to original loop 1320 /// if(something_is_wrong) return; // ~CountedLoopReserveKit makes the switch 1321 // ... 1322 // //everything worked ok, return with the newly modified loop 1323 // lrk.use_new(); 1324 // return; // ~CountedLoopReserveKit does nothing once use_new() was called 1325 // } 1326 // 1327 // Keep in mind, that by default if create_reserve() is not followed by use_new() 1328 // the dtor will "switch to the original" loop. 1329 // NOTE. You you modify outside of the original loop this class is no help. 1330 // 1331 class CountedLoopReserveKit { 1332 private: 1333 PhaseIdealLoop* _phase; 1334 IdealLoopTree* _lpt; 1335 LoopNode* _lp; 1336 IfNode* _iff; 1337 LoopNode* _lp_reserved; 1338 bool _has_reserved; 1339 bool _use_new; 1340 const bool _active; //may be set to false in ctor, then the object is dummy 1341 1342 public: 1343 CountedLoopReserveKit(PhaseIdealLoop* phase, IdealLoopTree *loop, bool active); 1344 ~CountedLoopReserveKit(); 1345 void use_new() {_use_new = true;} 1346 void set_iff(IfNode* x) {_iff = x;} 1347 bool has_reserved() const { return _active && _has_reserved;} 1348 private: 1349 bool create_reserve(); 1350 };// class CountedLoopReserveKit 1351 1352 inline Node* IdealLoopTree::tail() { 1353 // Handle lazy update of _tail field 1354 Node *n = _tail; 1355 //while( !n->in(0) ) // Skip dead CFG nodes 1356 //n = n->in(1); 1357 if (n->in(0) == NULL) 1358 n = _phase->get_ctrl(n); 1359 _tail = n; 1360 return n; 1361 } 1362 1363 1364 // Iterate over the loop tree using a preorder, left-to-right traversal. 1365 // 1366 // Example that visits all counted loops from within PhaseIdealLoop 1367 // 1368 // for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) { 1369 // IdealLoopTree* lpt = iter.current(); 1370 // if (!lpt->is_counted()) continue; 1371 // ... 1372 class LoopTreeIterator : public StackObj { 1373 private: 1374 IdealLoopTree* _root; 1375 IdealLoopTree* _curnt; 1376 1377 public: 1378 LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {} 1379 1380 bool done() { return _curnt == NULL; } // Finished iterating? 1381 1382 void next(); // Advance to next loop tree 1383 1384 IdealLoopTree* current() { return _curnt; } // Return current value of iterator. 1385 }; 1386 1387 #endif // SHARE_VM_OPTO_LOOPNODE_HPP