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 ShenandoahBarrierNode; 42 class ShenandoahWriteBarrierNode; 43 class PathFrequency; 44 class PhaseIdealLoop; 45 class CountedLoopReserveKit; 46 class VectorSet; 47 class Invariance; 48 struct small_cache; 49 50 // 51 // I D E A L I Z E D L O O P S 52 // 53 // Idealized loops are the set of loops I perform more interesting 54 // transformations on, beyond simple hoisting. 55 56 //------------------------------LoopNode--------------------------------------- 57 // Simple loop header. Fall in path on left, loop-back path on right. 58 class LoopNode : public RegionNode { 59 // Size is bigger to hold the flags. However, the flags do not change 60 // the semantics so it does not appear in the hash & cmp functions. 61 virtual uint size_of() const { return sizeof(*this); } 62 protected: 63 uint _loop_flags; 64 // Names for flag bitfields 65 enum { Normal=0, Pre=1, Main=2, Post=3, PreMainPostFlagsMask=3, 66 MainHasNoPreLoop=4, 67 HasExactTripCount=8, 68 InnerLoop=16, 69 PartialPeelLoop=32, 70 PartialPeelFailed=64, 71 HasReductions=128, 72 WasSlpAnalyzed=256, 73 PassedSlpAnalysis=512, 74 DoUnrollOnly=1024, 75 VectorizedLoop=2048, 76 HasAtomicPostLoop=4096, 77 HasRangeChecks=8192, 78 IsMultiversioned=16384, 79 StripMined=32768, 80 SubwordLoop=65536, 81 ProfileTripFailed=131072}; 82 char _unswitch_count; 83 enum { _unswitch_max=3 }; 84 char _postloop_flags; 85 enum { LoopNotRCEChecked = 0, LoopRCEChecked = 1, RCEPostLoop = 2 }; 86 87 // Expected trip count from profile data 88 float _profile_trip_cnt; 89 90 public: 91 // Names for edge indices 92 enum { Self=0, EntryControl, LoopBackControl }; 93 94 bool is_inner_loop() const { return _loop_flags & InnerLoop; } 95 void set_inner_loop() { _loop_flags |= InnerLoop; } 96 97 bool range_checks_present() const { return _loop_flags & HasRangeChecks; } 98 bool is_multiversioned() const { return _loop_flags & IsMultiversioned; } 99 bool is_vectorized_loop() const { return _loop_flags & VectorizedLoop; } 100 bool is_partial_peel_loop() const { return _loop_flags & PartialPeelLoop; } 101 void set_partial_peel_loop() { _loop_flags |= PartialPeelLoop; } 102 bool partial_peel_has_failed() const { return _loop_flags & PartialPeelFailed; } 103 bool is_strip_mined() const { return _loop_flags & StripMined; } 104 bool is_profile_trip_failed() const { return _loop_flags & ProfileTripFailed; } 105 bool is_subword_loop() const { return _loop_flags & SubwordLoop; } 106 107 void mark_partial_peel_failed() { _loop_flags |= PartialPeelFailed; } 108 void mark_has_reductions() { _loop_flags |= HasReductions; } 109 void mark_was_slp() { _loop_flags |= WasSlpAnalyzed; } 110 void mark_passed_slp() { _loop_flags |= PassedSlpAnalysis; } 111 void mark_do_unroll_only() { _loop_flags |= DoUnrollOnly; } 112 void mark_loop_vectorized() { _loop_flags |= VectorizedLoop; } 113 void mark_has_atomic_post_loop() { _loop_flags |= HasAtomicPostLoop; } 114 void mark_has_range_checks() { _loop_flags |= HasRangeChecks; } 115 void mark_is_multiversioned() { _loop_flags |= IsMultiversioned; } 116 void mark_strip_mined() { _loop_flags |= StripMined; } 117 void clear_strip_mined() { _loop_flags &= ~StripMined; } 118 void mark_profile_trip_failed() { _loop_flags |= ProfileTripFailed; } 119 void mark_subword_loop() { _loop_flags |= SubwordLoop; } 120 121 int unswitch_max() { return _unswitch_max; } 122 int unswitch_count() { return _unswitch_count; } 123 124 int has_been_range_checked() const { return _postloop_flags & LoopRCEChecked; } 125 void set_has_been_range_checked() { _postloop_flags |= LoopRCEChecked; } 126 int is_rce_post_loop() const { return _postloop_flags & RCEPostLoop; } 127 void set_is_rce_post_loop() { _postloop_flags |= RCEPostLoop; } 128 129 void set_unswitch_count(int val) { 130 assert (val <= unswitch_max(), "too many unswitches"); 131 _unswitch_count = val; 132 } 133 134 void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; } 135 float profile_trip_cnt() { return _profile_trip_cnt; } 136 137 LoopNode(Node *entry, Node *backedge) 138 : RegionNode(3), _loop_flags(0), _unswitch_count(0), 139 _postloop_flags(0), _profile_trip_cnt(COUNT_UNKNOWN) { 140 init_class_id(Class_Loop); 141 init_req(EntryControl, entry); 142 init_req(LoopBackControl, backedge); 143 } 144 145 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); 146 virtual int Opcode() const; 147 bool can_be_counted_loop(PhaseTransform* phase) const { 148 return req() == 3 && in(0) != NULL && 149 in(1) != NULL && phase->type(in(1)) != Type::TOP && 150 in(2) != NULL && phase->type(in(2)) != Type::TOP; 151 } 152 bool is_valid_counted_loop() const; 153 #ifndef PRODUCT 154 virtual void dump_spec(outputStream *st) const; 155 #endif 156 157 void verify_strip_mined(int expect_skeleton) const; 158 virtual LoopNode* skip_strip_mined(int expect_skeleton = 1) { return this; } 159 virtual IfTrueNode* outer_loop_tail() const { ShouldNotReachHere(); return NULL; } 160 virtual OuterStripMinedLoopEndNode* outer_loop_end() const { ShouldNotReachHere(); return NULL; } 161 virtual IfFalseNode* outer_loop_exit() const { ShouldNotReachHere(); return NULL; } 162 virtual SafePointNode* outer_safepoint() const { ShouldNotReachHere(); return NULL; } 163 }; 164 165 //------------------------------Counted Loops---------------------------------- 166 // Counted loops are all trip-counted loops, with exactly 1 trip-counter exit 167 // path (and maybe some other exit paths). The trip-counter exit is always 168 // last in the loop. The trip-counter have to stride by a constant; 169 // the exit value is also loop invariant. 170 171 // CountedLoopNodes and CountedLoopEndNodes come in matched pairs. The 172 // CountedLoopNode has the incoming loop control and the loop-back-control 173 // which is always the IfTrue before the matching CountedLoopEndNode. The 174 // CountedLoopEndNode has an incoming control (possibly not the 175 // CountedLoopNode if there is control flow in the loop), the post-increment 176 // trip-counter value, and the limit. The trip-counter value is always of 177 // the form (Op old-trip-counter stride). The old-trip-counter is produced 178 // by a Phi connected to the CountedLoopNode. The stride is constant. 179 // The Op is any commutable opcode, including Add, Mul, Xor. The 180 // CountedLoopEndNode also takes in the loop-invariant limit value. 181 182 // From a CountedLoopNode I can reach the matching CountedLoopEndNode via the 183 // loop-back control. From CountedLoopEndNodes I can reach CountedLoopNodes 184 // via the old-trip-counter from the Op node. 185 186 //------------------------------CountedLoopNode-------------------------------- 187 // CountedLoopNodes head simple counted loops. CountedLoopNodes have as 188 // inputs the incoming loop-start control and the loop-back control, so they 189 // act like RegionNodes. They also take in the initial trip counter, the 190 // loop-invariant stride and the loop-invariant limit value. CountedLoopNodes 191 // produce a loop-body control and the trip counter value. Since 192 // CountedLoopNodes behave like RegionNodes I still have a standard CFG model. 193 194 class CountedLoopNode : public LoopNode { 195 // Size is bigger to hold _main_idx. However, _main_idx does not change 196 // the semantics so it does not appear in the hash & cmp functions. 197 virtual uint size_of() const { return sizeof(*this); } 198 199 // For Pre- and Post-loops during debugging ONLY, this holds the index of 200 // the Main CountedLoop. Used to assert that we understand the graph shape. 201 node_idx_t _main_idx; 202 203 // Known trip count calculated by compute_exact_trip_count() 204 uint _trip_count; 205 206 // Log2 of original loop bodies in unrolled loop 207 int _unrolled_count_log2; 208 209 // Node count prior to last unrolling - used to decide if 210 // unroll,optimize,unroll,optimize,... is making progress 211 int _node_count_before_unroll; 212 213 // If slp analysis is performed we record the maximum 214 // vector mapped unroll factor here 215 int _slp_maximum_unroll_factor; 216 217 public: 218 CountedLoopNode( Node *entry, Node *backedge ) 219 : LoopNode(entry, backedge), _main_idx(0), _trip_count(max_juint), 220 _unrolled_count_log2(0), _node_count_before_unroll(0), 221 _slp_maximum_unroll_factor(0) { 222 init_class_id(Class_CountedLoop); 223 // Initialize _trip_count to the largest possible value. 224 // Will be reset (lower) if the loop's trip count is known. 225 } 226 227 virtual int Opcode() const; 228 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); 229 230 Node *init_control() const { return in(EntryControl); } 231 Node *back_control() const { return in(LoopBackControl); } 232 CountedLoopEndNode *loopexit_or_null() const; 233 CountedLoopEndNode *loopexit() const; 234 Node *init_trip() const; 235 Node *stride() const; 236 int stride_con() const; 237 bool stride_is_con() const; 238 Node *limit() const; 239 Node *incr() const; 240 Node *phi() const; 241 242 // Match increment with optional truncation 243 static Node* match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type); 244 245 // A 'main' loop has a pre-loop and a post-loop. The 'main' loop 246 // can run short a few iterations and may start a few iterations in. 247 // It will be RCE'd and unrolled and aligned. 248 249 // A following 'post' loop will run any remaining iterations. Used 250 // during Range Check Elimination, the 'post' loop will do any final 251 // iterations with full checks. Also used by Loop Unrolling, where 252 // the 'post' loop will do any epilog iterations needed. Basically, 253 // a 'post' loop can not profitably be further unrolled or RCE'd. 254 255 // A preceding 'pre' loop will run at least 1 iteration (to do peeling), 256 // it may do under-flow checks for RCE and may do alignment iterations 257 // so the following main loop 'knows' that it is striding down cache 258 // lines. 259 260 // A 'main' loop that is ONLY unrolled or peeled, never RCE'd or 261 // Aligned, may be missing it's pre-loop. 262 bool is_normal_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Normal; } 263 bool is_pre_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Pre; } 264 bool is_main_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Main; } 265 bool is_post_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Post; } 266 bool is_reduction_loop() const { return (_loop_flags&HasReductions) == HasReductions; } 267 bool was_slp_analyzed () const { return (_loop_flags&WasSlpAnalyzed) == WasSlpAnalyzed; } 268 bool has_passed_slp () const { return (_loop_flags&PassedSlpAnalysis) == PassedSlpAnalysis; } 269 bool do_unroll_only () const { return (_loop_flags&DoUnrollOnly) == DoUnrollOnly; } 270 bool is_main_no_pre_loop() const { return _loop_flags & MainHasNoPreLoop; } 271 bool has_atomic_post_loop () const { return (_loop_flags & HasAtomicPostLoop) == HasAtomicPostLoop; } 272 void set_main_no_pre_loop() { _loop_flags |= MainHasNoPreLoop; } 273 274 int main_idx() const { return _main_idx; } 275 276 277 void set_pre_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; } 278 void set_main_loop ( ) { assert(is_normal_loop(),""); _loop_flags |= Main; } 279 void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; } 280 void set_normal_loop( ) { _loop_flags &= ~PreMainPostFlagsMask; } 281 282 void set_trip_count(uint tc) { _trip_count = tc; } 283 uint trip_count() { return _trip_count; } 284 285 bool has_exact_trip_count() const { return (_loop_flags & HasExactTripCount) != 0; } 286 void set_exact_trip_count(uint tc) { 287 _trip_count = tc; 288 _loop_flags |= HasExactTripCount; 289 } 290 void set_nonexact_trip_count() { 291 _loop_flags &= ~HasExactTripCount; 292 } 293 void set_notpassed_slp() { 294 _loop_flags &= ~PassedSlpAnalysis; 295 } 296 297 void double_unrolled_count() { _unrolled_count_log2++; } 298 int unrolled_count() { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); } 299 300 void set_node_count_before_unroll(int ct) { _node_count_before_unroll = ct; } 301 int node_count_before_unroll() { return _node_count_before_unroll; } 302 void set_slp_max_unroll(int unroll_factor) { _slp_maximum_unroll_factor = unroll_factor; } 303 int slp_max_unroll() const { return _slp_maximum_unroll_factor; } 304 305 virtual LoopNode* skip_strip_mined(int expect_skeleton = 1); 306 OuterStripMinedLoopNode* outer_loop() const; 307 virtual IfTrueNode* outer_loop_tail() const; 308 virtual OuterStripMinedLoopEndNode* outer_loop_end() const; 309 virtual IfFalseNode* outer_loop_exit() const; 310 virtual SafePointNode* outer_safepoint() const; 311 312 // If this is a main loop in a pre/main/post loop nest, walk over 313 // the predicates that were inserted by 314 // duplicate_predicates()/add_range_check_predicate() 315 static Node* skip_predicates_from_entry(Node* ctrl); 316 Node* skip_predicates(); 317 318 #ifndef PRODUCT 319 virtual void dump_spec(outputStream *st) const; 320 #endif 321 }; 322 323 //------------------------------CountedLoopEndNode----------------------------- 324 // CountedLoopEndNodes end simple trip counted loops. They act much like 325 // IfNodes. 326 class CountedLoopEndNode : public IfNode { 327 public: 328 enum { TestControl, TestValue }; 329 330 CountedLoopEndNode( Node *control, Node *test, float prob, float cnt ) 331 : IfNode( control, test, prob, cnt) { 332 init_class_id(Class_CountedLoopEnd); 333 } 334 virtual int Opcode() const; 335 336 Node *cmp_node() const { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : NULL; } 337 Node *incr() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; } 338 Node *limit() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; } 339 Node *stride() const { Node *tmp = incr (); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; } 340 Node *init_trip() const { Node *tmp = phi (); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; } 341 int stride_con() const; 342 bool stride_is_con() const { Node *tmp = stride (); return (tmp != NULL && tmp->is_Con()); } 343 BoolTest::mask test_trip() const { return in(TestValue)->as_Bool()->_test._test; } 344 PhiNode *phi() const { 345 Node *tmp = incr(); 346 if (tmp && tmp->req() == 3) { 347 Node* phi = tmp->in(1); 348 if (phi->is_Phi()) { 349 return phi->as_Phi(); 350 } 351 } 352 return NULL; 353 } 354 CountedLoopNode *loopnode() const { 355 // The CountedLoopNode that goes with this CountedLoopEndNode may 356 // have been optimized out by the IGVN so be cautious with the 357 // pattern matching on the graph 358 PhiNode* iv_phi = phi(); 359 if (iv_phi == NULL) { 360 return NULL; 361 } 362 Node *ln = iv_phi->in(0); 363 if (ln->is_CountedLoop() && ln->as_CountedLoop()->loopexit_or_null() == this) { 364 return (CountedLoopNode*)ln; 365 } 366 return NULL; 367 } 368 369 #ifndef PRODUCT 370 virtual void dump_spec(outputStream *st) const; 371 #endif 372 }; 373 374 375 inline CountedLoopEndNode *CountedLoopNode::loopexit_or_null() const { 376 Node *bc = back_control(); 377 if( bc == NULL ) return NULL; 378 Node *le = bc->in(0); 379 if( le->Opcode() != Op_CountedLoopEnd ) 380 return NULL; 381 return (CountedLoopEndNode*)le; 382 } 383 inline CountedLoopEndNode *CountedLoopNode::loopexit() const { 384 CountedLoopEndNode* cle = loopexit_or_null(); 385 assert(cle != NULL, "loopexit is NULL"); 386 return cle; 387 } 388 inline Node *CountedLoopNode::init_trip() const { return loopexit_or_null() ? loopexit()->init_trip() : NULL; } 389 inline Node *CountedLoopNode::stride() const { return loopexit_or_null() ? loopexit()->stride() : NULL; } 390 inline int CountedLoopNode::stride_con() const { return loopexit_or_null() ? loopexit()->stride_con() : 0; } 391 inline bool CountedLoopNode::stride_is_con() const { return loopexit_or_null() && loopexit()->stride_is_con(); } 392 inline Node *CountedLoopNode::limit() const { return loopexit_or_null() ? loopexit()->limit() : NULL; } 393 inline Node *CountedLoopNode::incr() const { return loopexit_or_null() ? loopexit()->incr() : NULL; } 394 inline Node *CountedLoopNode::phi() const { return loopexit_or_null() ? loopexit()->phi() : NULL; } 395 396 //------------------------------LoopLimitNode----------------------------- 397 // Counted Loop limit node which represents exact final iterator value: 398 // trip_count = (limit - init_trip + stride - 1)/stride 399 // final_value= trip_count * stride + init_trip. 400 // Use HW instructions to calculate it when it can overflow in integer. 401 // Note, final_value should fit into integer since counted loop has 402 // limit check: limit <= max_int-stride. 403 class LoopLimitNode : public Node { 404 enum { Init=1, Limit=2, Stride=3 }; 405 public: 406 LoopLimitNode( Compile* C, Node *init, Node *limit, Node *stride ) : Node(0,init,limit,stride) { 407 // Put it on the Macro nodes list to optimize during macro nodes expansion. 408 init_flags(Flag_is_macro); 409 C->add_macro_node(this); 410 } 411 virtual int Opcode() const; 412 virtual const Type *bottom_type() const { return TypeInt::INT; } 413 virtual uint ideal_reg() const { return Op_RegI; } 414 virtual const Type* Value(PhaseGVN* phase) const; 415 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); 416 virtual Node* Identity(PhaseGVN* phase); 417 }; 418 419 // Support for strip mining 420 class OuterStripMinedLoopNode : public LoopNode { 421 private: 422 CountedLoopNode* inner_loop() const; 423 public: 424 OuterStripMinedLoopNode(Compile* C, Node *entry, Node *backedge) 425 : LoopNode(entry, backedge) { 426 init_class_id(Class_OuterStripMinedLoop); 427 init_flags(Flag_is_macro); 428 C->add_macro_node(this); 429 } 430 431 virtual int Opcode() const; 432 433 virtual IfTrueNode* outer_loop_tail() const; 434 virtual OuterStripMinedLoopEndNode* outer_loop_end() const; 435 virtual IfFalseNode* outer_loop_exit() const; 436 virtual SafePointNode* outer_safepoint() const; 437 void adjust_strip_mined_loop(PhaseIterGVN* igvn); 438 }; 439 440 class OuterStripMinedLoopEndNode : public IfNode { 441 public: 442 OuterStripMinedLoopEndNode(Node *control, Node *test, float prob, float cnt) 443 : IfNode(control, test, prob, cnt) { 444 init_class_id(Class_OuterStripMinedLoopEnd); 445 } 446 447 virtual int Opcode() const; 448 449 virtual const Type* Value(PhaseGVN* phase) const; 450 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); 451 }; 452 453 // -----------------------------IdealLoopTree---------------------------------- 454 class IdealLoopTree : public ResourceObj { 455 public: 456 IdealLoopTree *_parent; // Parent in loop tree 457 IdealLoopTree *_next; // Next sibling in loop tree 458 IdealLoopTree *_child; // First child in loop tree 459 460 // The head-tail backedge defines the loop. 461 // If tail is NULL then this loop has multiple backedges as part of the 462 // same loop. During cleanup I'll peel off the multiple backedges; merge 463 // them at the loop bottom and flow 1 real backedge into the loop. 464 Node *_head; // Head of loop 465 Node *_tail; // Tail of loop 466 inline Node *tail(); // Handle lazy update of _tail field 467 PhaseIdealLoop* _phase; 468 int _local_loop_unroll_limit; 469 int _local_loop_unroll_factor; 470 471 Node_List _body; // Loop body for inner loops 472 473 uint8_t _nest; // Nesting depth 474 uint8_t _irreducible:1, // True if irreducible 475 _has_call:1, // True if has call safepoint 476 _has_sfpt:1, // True if has non-call safepoint 477 _rce_candidate:1; // True if candidate for range check elimination 478 479 Node_List* _safepts; // List of safepoints in this loop 480 Node_List* _required_safept; // A inner loop cannot delete these safepts; 481 bool _allow_optimizations; // Allow loop optimizations 482 483 IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail ) 484 : _parent(0), _next(0), _child(0), 485 _head(head), _tail(tail), 486 _phase(phase), 487 _local_loop_unroll_limit(0), _local_loop_unroll_factor(0), 488 _nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0), 489 _safepts(NULL), 490 _required_safept(NULL), 491 _allow_optimizations(true) 492 { } 493 494 // Is 'l' a member of 'this'? 495 bool is_member(const IdealLoopTree *l) const; // Test for nested membership 496 497 // Set loop nesting depth. Accumulate has_call bits. 498 int set_nest( uint depth ); 499 500 // Split out multiple fall-in edges from the loop header. Move them to a 501 // private RegionNode before the loop. This becomes the loop landing pad. 502 void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ); 503 504 // Split out the outermost loop from this shared header. 505 void split_outer_loop( PhaseIdealLoop *phase ); 506 507 // Merge all the backedges from the shared header into a private Region. 508 // Feed that region as the one backedge to this loop. 509 void merge_many_backedges( PhaseIdealLoop *phase ); 510 511 // Split shared headers and insert loop landing pads. 512 // Insert a LoopNode to replace the RegionNode. 513 // Returns TRUE if loop tree is structurally changed. 514 bool beautify_loops( PhaseIdealLoop *phase ); 515 516 // Perform optimization to use the loop predicates for null checks and range checks. 517 // Applies to any loop level (not just the innermost one) 518 bool loop_predication( PhaseIdealLoop *phase); 519 520 // Perform iteration-splitting on inner loops. Split iterations to 521 // avoid range checks or one-shot null checks. Returns false if the 522 // current round of loop opts should stop. 523 bool iteration_split( PhaseIdealLoop *phase, Node_List &old_new ); 524 525 // Driver for various flavors of iteration splitting. Returns false 526 // if the current round of loop opts should stop. 527 bool iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new ); 528 529 // Given dominators, try to find loops with calls that must always be 530 // executed (call dominates loop tail). These loops do not need non-call 531 // safepoints (ncsfpt). 532 void check_safepts(VectorSet &visited, Node_List &stack); 533 534 // Allpaths backwards scan from loop tail, terminating each path at first safepoint 535 // encountered. 536 void allpaths_check_safepts(VectorSet &visited, Node_List &stack); 537 538 // Remove safepoints from loop. Optionally keeping one. 539 void remove_safepoints(PhaseIdealLoop* phase, bool keep_one); 540 541 // Convert to counted loops where possible 542 void counted_loop( PhaseIdealLoop *phase ); 543 544 // Check for Node being a loop-breaking test 545 Node *is_loop_exit(Node *iff) const; 546 547 // Remove simplistic dead code from loop body 548 void DCE_loop_body(); 549 550 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage. 551 // Replace with a 1-in-10 exit guess. 552 void adjust_loop_exit_prob( PhaseIdealLoop *phase ); 553 554 // Return TRUE or FALSE if the loop should never be RCE'd or aligned. 555 // Useful for unrolling loops with NO array accesses. 556 bool policy_peel_only( PhaseIdealLoop *phase ) const; 557 558 // Return TRUE or FALSE if the loop should be unswitched -- clone 559 // loop with an invariant test 560 bool policy_unswitching( PhaseIdealLoop *phase ) const; 561 562 // Micro-benchmark spamming. Remove empty loops. 563 bool policy_do_remove_empty_loop( PhaseIdealLoop *phase ); 564 565 // Convert one iteration loop into normal code. 566 bool policy_do_one_iteration_loop( PhaseIdealLoop *phase ); 567 568 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can 569 // make some loop-invariant test (usually a null-check) happen before the 570 // loop. 571 bool policy_peeling( PhaseIdealLoop *phase ) const; 572 573 // Return TRUE or FALSE if the loop should be maximally unrolled. Stash any 574 // known trip count in the counted loop node. 575 bool policy_maximally_unroll( PhaseIdealLoop *phase ) const; 576 577 // Return TRUE or FALSE if the loop should be unrolled or not. Unroll if 578 // the loop is a CountedLoop and the body is small enough. 579 bool policy_unroll(PhaseIdealLoop *phase); 580 581 // Loop analyses to map to a maximal superword unrolling for vectorization. 582 void policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_ct); 583 584 // Return TRUE or FALSE if the loop should be range-check-eliminated. 585 // Gather a list of IF tests that are dominated by iteration splitting; 586 // also gather the end of the first split and the start of the 2nd split. 587 bool policy_range_check( PhaseIdealLoop *phase ) const; 588 589 // Return TRUE or FALSE if the loop should be cache-line aligned. 590 // Gather the expression that does the alignment. Note that only 591 // one array base can be aligned in a loop (unless the VM guarantees 592 // mutual alignment). Note that if we vectorize short memory ops 593 // into longer memory ops, we may want to increase alignment. 594 bool policy_align( PhaseIdealLoop *phase ) const; 595 596 // Return TRUE if "iff" is a range check. 597 bool is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const; 598 599 // Compute loop trip count if possible 600 void compute_trip_count(PhaseIdealLoop* phase); 601 602 // Compute loop trip count from profile data 603 float compute_profile_trip_cnt_helper(Node* n); 604 void compute_profile_trip_cnt( PhaseIdealLoop *phase ); 605 606 // Reassociate invariant expressions. 607 void reassociate_invariants(PhaseIdealLoop *phase); 608 // Reassociate invariant add and subtract expressions. 609 Node* reassociate_add_sub(Node* n1, PhaseIdealLoop *phase); 610 // Return nonzero index of invariant operand if invariant and variant 611 // are combined with an Add or Sub. Helper for reassociate_invariants. 612 int is_invariant_addition(Node* n, PhaseIdealLoop *phase); 613 614 // Return true if n is invariant 615 bool is_invariant(Node* n) const; 616 617 // Put loop body on igvn work list 618 void record_for_igvn(); 619 620 bool is_loop() { return !_irreducible && _tail && !_tail->is_top(); } 621 bool is_inner() { return is_loop() && _child == NULL; } 622 bool is_counted() { return is_loop() && _head != NULL && _head->is_CountedLoop(); } 623 624 void remove_main_post_loops(CountedLoopNode *cl, PhaseIdealLoop *phase); 625 626 #ifndef PRODUCT 627 void dump_head( ) const; // Dump loop head only 628 void dump() const; // Dump this loop recursively 629 void verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const; 630 #endif 631 632 }; 633 634 // -----------------------------PhaseIdealLoop--------------------------------- 635 // Computes the mapping from Nodes to IdealLoopTrees. Organizes IdealLoopTrees into a 636 // loop tree. Drives the loop-based transformations on the ideal graph. 637 class PhaseIdealLoop : public PhaseTransform { 638 friend class IdealLoopTree; 639 friend class SuperWord; 640 friend class CountedLoopReserveKit; 641 friend class ShenandoahBarrierNode; 642 friend class ShenandoahWriteBarrierNode; 643 644 // Pre-computed def-use info 645 PhaseIterGVN &_igvn; 646 647 // Head of loop tree 648 IdealLoopTree *_ltree_root; 649 650 // Array of pre-order numbers, plus post-visited bit. 651 // ZERO for not pre-visited. EVEN for pre-visited but not post-visited. 652 // ODD for post-visited. Other bits are the pre-order number. 653 uint *_preorders; 654 uint _max_preorder; 655 656 const PhaseIdealLoop* _verify_me; 657 bool _verify_only; 658 659 // Allocate _preorders[] array 660 void allocate_preorders() { 661 _max_preorder = C->unique()+8; 662 _preorders = NEW_RESOURCE_ARRAY(uint, _max_preorder); 663 memset(_preorders, 0, sizeof(uint) * _max_preorder); 664 } 665 666 // Allocate _preorders[] array 667 void reallocate_preorders() { 668 if ( _max_preorder < C->unique() ) { 669 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique()); 670 _max_preorder = C->unique(); 671 } 672 memset(_preorders, 0, sizeof(uint) * _max_preorder); 673 } 674 675 // Check to grow _preorders[] array for the case when build_loop_tree_impl() 676 // adds new nodes. 677 void check_grow_preorders( ) { 678 if ( _max_preorder < C->unique() ) { 679 uint newsize = _max_preorder<<1; // double size of array 680 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize); 681 memset(&_preorders[_max_preorder],0,sizeof(uint)*(newsize-_max_preorder)); 682 _max_preorder = newsize; 683 } 684 } 685 // Check for pre-visited. Zero for NOT visited; non-zero for visited. 686 int is_visited( Node *n ) const { return _preorders[n->_idx]; } 687 // Pre-order numbers are written to the Nodes array as low-bit-set values. 688 void set_preorder_visited( Node *n, int pre_order ) { 689 assert( !is_visited( n ), "already set" ); 690 _preorders[n->_idx] = (pre_order<<1); 691 }; 692 // Return pre-order number. 693 int get_preorder( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]>>1; } 694 695 // Check for being post-visited. 696 // Should be previsited already (checked with assert(is_visited(n))). 697 int is_postvisited( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]&1; } 698 699 // Mark as post visited 700 void set_postvisited( Node *n ) { assert( !is_postvisited( n ), "" ); _preorders[n->_idx] |= 1; } 701 702 public: 703 // Set/get control node out. Set lower bit to distinguish from IdealLoopTree 704 // Returns true if "n" is a data node, false if it's a control node. 705 bool has_ctrl( Node *n ) const { return ((intptr_t)_nodes[n->_idx]) & 1; } 706 707 private: 708 // clear out dead code after build_loop_late 709 Node_List _deadlist; 710 711 // Support for faster execution of get_late_ctrl()/dom_lca() 712 // when a node has many uses and dominator depth is deep. 713 Node_Array _dom_lca_tags; 714 void init_dom_lca_tags(); 715 void clear_dom_lca_tags(); 716 717 // Helper for debugging bad dominance relationships 718 bool verify_dominance(Node* n, Node* use, Node* LCA, Node* early); 719 720 Node* compute_lca_of_uses(Node* n, Node* early, bool verify = false); 721 722 // Inline wrapper for frequent cases: 723 // 1) only one use 724 // 2) a use is the same as the current LCA passed as 'n1' 725 Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) { 726 assert( n->is_CFG(), "" ); 727 // Fast-path NULL lca 728 if( lca != NULL && lca != n ) { 729 assert( lca->is_CFG(), "" ); 730 // find LCA of all uses 731 n = dom_lca_for_get_late_ctrl_internal( lca, n, tag ); 732 } 733 return find_non_split_ctrl(n); 734 } 735 Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag ); 736 737 // Helper function for directing control inputs away from CFG split 738 // points. 739 Node *find_non_split_ctrl( Node *ctrl ) const { 740 if (ctrl != NULL) { 741 if (ctrl->is_MultiBranch()) { 742 ctrl = ctrl->in(0); 743 } 744 assert(ctrl->is_CFG(), "CFG"); 745 } 746 return ctrl; 747 } 748 749 Node* cast_incr_before_loop(Node* incr, Node* ctrl, Node* loop); 750 void duplicate_predicates_helper(Node* predicate, Node* start, Node* end, IdealLoopTree* outer_loop, 751 LoopNode* outer_main_head, uint dd_main_head); 752 void duplicate_predicates(CountedLoopNode* pre_head, Node* start, Node* end, IdealLoopTree* outer_loop, 753 LoopNode* outer_main_head, uint dd_main_head); 754 Node* clone_skeleton_predicate(Node* iff, Node* value, Node* predicate, Node* uncommon_proj, 755 Node* current_proj, IdealLoopTree* outer_loop, Node* prev_proj); 756 bool skeleton_predicate_has_opaque(IfNode* iff); 757 void update_skeleton_predicates(Node* ctrl, CountedLoopNode* loop_head, Node* init, int stride_con); 758 void insert_loop_limit_check(ProjNode* limit_check_proj, Node* cmp_limit, Node* bol); 759 760 public: 761 762 PhaseIterGVN &igvn() const { return _igvn; } 763 764 static bool is_canonical_loop_entry(CountedLoopNode* cl); 765 766 bool has_node( Node* n ) const { 767 guarantee(n != NULL, "No Node."); 768 return _nodes[n->_idx] != NULL; 769 } 770 // check if transform created new nodes that need _ctrl recorded 771 Node *get_late_ctrl( Node *n, Node *early ); 772 Node *get_early_ctrl( Node *n ); 773 Node *get_early_ctrl_for_expensive(Node *n, Node* earliest); 774 void set_early_ctrl( Node *n ); 775 void set_subtree_ctrl( Node *root ); 776 void set_ctrl( Node *n, Node *ctrl ) { 777 assert( !has_node(n) || has_ctrl(n), "" ); 778 assert( ctrl->in(0), "cannot set dead control node" ); 779 assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" ); 780 _nodes.map( n->_idx, (Node*)((intptr_t)ctrl + 1) ); 781 } 782 // Set control and update loop membership 783 void set_ctrl_and_loop(Node* n, Node* ctrl) { 784 IdealLoopTree* old_loop = get_loop(get_ctrl(n)); 785 IdealLoopTree* new_loop = get_loop(ctrl); 786 if (old_loop != new_loop) { 787 if (old_loop->_child == NULL) old_loop->_body.yank(n); 788 if (new_loop->_child == NULL) new_loop->_body.push(n); 789 } 790 set_ctrl(n, ctrl); 791 } 792 // Control nodes can be replaced or subsumed. During this pass they 793 // get their replacement Node in slot 1. Instead of updating the block 794 // location of all Nodes in the subsumed block, we lazily do it. As we 795 // pull such a subsumed block out of the array, we write back the final 796 // correct block. 797 Node *get_ctrl( Node *i ) { 798 assert(has_node(i), ""); 799 Node *n = get_ctrl_no_update(i); 800 _nodes.map( i->_idx, (Node*)((intptr_t)n + 1) ); 801 assert(has_node(i) && has_ctrl(i), ""); 802 assert(n == find_non_split_ctrl(n), "must return legal ctrl" ); 803 return n; 804 } 805 // true if CFG node d dominates CFG node n 806 bool is_dominator(Node *d, Node *n); 807 // return get_ctrl for a data node and self(n) for a CFG node 808 Node* ctrl_or_self(Node* n) { 809 if (has_ctrl(n)) 810 return get_ctrl(n); 811 else { 812 assert (n->is_CFG(), "must be a CFG node"); 813 return n; 814 } 815 } 816 817 Node *get_ctrl_no_update_helper(Node *i) const { 818 assert(has_ctrl(i), "should be control, not loop"); 819 return (Node*)(((intptr_t)_nodes[i->_idx]) & ~1); 820 } 821 822 Node *get_ctrl_no_update(Node *i) const { 823 assert( has_ctrl(i), "" ); 824 Node *n = get_ctrl_no_update_helper(i); 825 if (!n->in(0)) { 826 // Skip dead CFG nodes 827 do { 828 n = get_ctrl_no_update_helper(n); 829 } while (!n->in(0)); 830 n = find_non_split_ctrl(n); 831 } 832 return n; 833 } 834 835 // Check for loop being set 836 // "n" must be a control node. Returns true if "n" is known to be in a loop. 837 bool has_loop( Node *n ) const { 838 assert(!has_node(n) || !has_ctrl(n), ""); 839 return has_node(n); 840 } 841 // Set loop 842 void set_loop( Node *n, IdealLoopTree *loop ) { 843 _nodes.map(n->_idx, (Node*)loop); 844 } 845 // Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms. Replace 846 // the 'old_node' with 'new_node'. Kill old-node. Add a reference 847 // from old_node to new_node to support the lazy update. Reference 848 // replaces loop reference, since that is not needed for dead node. 849 void lazy_update(Node *old_node, Node *new_node) { 850 assert(old_node != new_node, "no cycles please"); 851 // Re-use the side array slot for this node to provide the 852 // forwarding pointer. 853 _nodes.map(old_node->_idx, (Node*)((intptr_t)new_node + 1)); 854 } 855 void lazy_replace(Node *old_node, Node *new_node) { 856 _igvn.replace_node(old_node, new_node); 857 lazy_update(old_node, new_node); 858 } 859 860 private: 861 862 // Place 'n' in some loop nest, where 'n' is a CFG node 863 void build_loop_tree(); 864 int build_loop_tree_impl( Node *n, int pre_order ); 865 // Insert loop into the existing loop tree. 'innermost' is a leaf of the 866 // loop tree, not the root. 867 IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost ); 868 869 // Place Data nodes in some loop nest 870 void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ); 871 void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ); 872 void build_loop_late_post_work(Node* n, bool pinned); 873 void build_loop_late_post(Node* n); 874 void verify_strip_mined_scheduling(Node *n, Node* least); 875 876 // Array of immediate dominance info for each CFG node indexed by node idx 877 private: 878 uint _idom_size; 879 Node **_idom; // Array of immediate dominators 880 uint *_dom_depth; // Used for fast LCA test 881 GrowableArray<uint>* _dom_stk; // For recomputation of dom depth 882 883 public: 884 Node* idom_no_update(Node* d) const { 885 return idom_no_update(d->_idx); 886 } 887 888 Node* idom_no_update(uint didx) const { 889 assert(didx < _idom_size, "oob"); 890 Node* n = _idom[didx]; 891 assert(n != NULL,"Bad immediate dominator info."); 892 while (n->in(0) == NULL) { // Skip dead CFG nodes 893 n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1); 894 assert(n != NULL,"Bad immediate dominator info."); 895 } 896 return n; 897 } 898 899 Node *idom(Node* d) const { 900 return idom(d->_idx); 901 } 902 903 Node *idom(uint didx) const { 904 Node *n = idom_no_update(didx); 905 _idom[didx] = n; // Lazily remove dead CFG nodes from table. 906 return n; 907 } 908 909 uint dom_depth(Node* d) const { 910 guarantee(d != NULL, "Null dominator info."); 911 guarantee(d->_idx < _idom_size, ""); 912 return _dom_depth[d->_idx]; 913 } 914 void set_idom(Node* d, Node* n, uint dom_depth); 915 // Locally compute IDOM using dom_lca call 916 Node *compute_idom( Node *region ) const; 917 // Recompute dom_depth 918 void recompute_dom_depth(); 919 920 // Is safept not required by an outer loop? 921 bool is_deleteable_safept(Node* sfpt); 922 923 // Replace parallel induction variable (parallel to trip counter) 924 void replace_parallel_iv(IdealLoopTree *loop); 925 926 // Perform verification that the graph is valid. 927 PhaseIdealLoop( PhaseIterGVN &igvn) : 928 PhaseTransform(Ideal_Loop), 929 _igvn(igvn), 930 _verify_me(NULL), 931 _verify_only(true), 932 _dom_lca_tags(arena()) { // Thread::resource_area 933 build_and_optimize(LoopOptsVerify); 934 } 935 936 // build the loop tree and perform any requested optimizations 937 void build_and_optimize(LoopOptsMode mode); 938 939 // Dominators for the sea of nodes 940 void Dominators(); 941 Node *dom_lca( Node *n1, Node *n2 ) const { 942 return find_non_split_ctrl(dom_lca_internal(n1, n2)); 943 } 944 Node *dom_lca_internal( Node *n1, Node *n2 ) const; 945 946 // Compute the Ideal Node to Loop mapping 947 PhaseIdealLoop(PhaseIterGVN &igvn, LoopOptsMode mode) : 948 PhaseTransform(Ideal_Loop), 949 _igvn(igvn), 950 _verify_me(NULL), 951 _verify_only(false), 952 _dom_lca_tags(arena()) { // Thread::resource_area 953 build_and_optimize(mode); 954 } 955 956 // Verify that verify_me made the same decisions as a fresh run. 957 PhaseIdealLoop(PhaseIterGVN &igvn, const PhaseIdealLoop *verify_me) : 958 PhaseTransform(Ideal_Loop), 959 _igvn(igvn), 960 _verify_me(verify_me), 961 _verify_only(false), 962 _dom_lca_tags(arena()) { // Thread::resource_area 963 build_and_optimize(LoopOptsVerify); 964 } 965 966 // Build and verify the loop tree without modifying the graph. This 967 // is useful to verify that all inputs properly dominate their uses. 968 static void verify(PhaseIterGVN& igvn) { 969 #ifdef ASSERT 970 PhaseIdealLoop v(igvn); 971 #endif 972 } 973 974 // True if the method has at least 1 irreducible loop 975 bool _has_irreducible_loops; 976 977 // Per-Node transform 978 virtual Node *transform( Node *a_node ) { return 0; } 979 980 bool is_counted_loop(Node* x, IdealLoopTree*& loop); 981 IdealLoopTree* create_outer_strip_mined_loop(BoolNode *test, Node *cmp, Node *init_control, 982 IdealLoopTree* loop, float cl_prob, float le_fcnt, 983 Node*& entry_control, Node*& iffalse); 984 985 Node* exact_limit( IdealLoopTree *loop ); 986 987 // Return a post-walked LoopNode 988 IdealLoopTree *get_loop( Node *n ) const { 989 // Dead nodes have no loop, so return the top level loop instead 990 if (!has_node(n)) return _ltree_root; 991 assert(!has_ctrl(n), ""); 992 return (IdealLoopTree*)_nodes[n->_idx]; 993 } 994 995 IdealLoopTree *ltree_root() const { return _ltree_root; } 996 997 // Is 'n' a (nested) member of 'loop'? 998 int is_member( const IdealLoopTree *loop, Node *n ) const { 999 return loop->is_member(get_loop(n)); } 1000 1001 // This is the basic building block of the loop optimizations. It clones an 1002 // entire loop body. It makes an old_new loop body mapping; with this 1003 // mapping you can find the new-loop equivalent to an old-loop node. All 1004 // new-loop nodes are exactly equal to their old-loop counterparts, all 1005 // edges are the same. All exits from the old-loop now have a RegionNode 1006 // that merges the equivalent new-loop path. This is true even for the 1007 // normal "loop-exit" condition. All uses of loop-invariant old-loop values 1008 // now come from (one or more) Phis that merge their new-loop equivalents. 1009 // Parameter side_by_side_idom: 1010 // When side_by_size_idom is NULL, the dominator tree is constructed for 1011 // the clone loop to dominate the original. Used in construction of 1012 // pre-main-post loop sequence. 1013 // When nonnull, the clone and original are side-by-side, both are 1014 // dominated by the passed in side_by_side_idom node. Used in 1015 // construction of unswitched loops. 1016 enum CloneLoopMode { 1017 IgnoreStripMined = 0, // Only clone inner strip mined loop 1018 CloneIncludesStripMined = 1, // clone both inner and outer strip mined loops 1019 ControlAroundStripMined = 2 // Only clone inner strip mined loop, 1020 // result control flow branches 1021 // either to inner clone or outer 1022 // strip mined loop. 1023 }; 1024 void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth, 1025 CloneLoopMode mode, Node* side_by_side_idom = NULL); 1026 void clone_loop_handle_data_uses(Node* old, Node_List &old_new, 1027 IdealLoopTree* loop, IdealLoopTree* companion_loop, 1028 Node_List*& split_if_set, Node_List*& split_bool_set, 1029 Node_List*& split_cex_set, Node_List& worklist, 1030 uint new_counter, CloneLoopMode mode); 1031 void clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop, 1032 IdealLoopTree* outer_loop, int dd, Node_List &old_new, 1033 Node_List& extra_data_nodes); 1034 1035 // If we got the effect of peeling, either by actually peeling or by 1036 // making a pre-loop which must execute at least once, we can remove 1037 // all loop-invariant dominated tests in the main body. 1038 void peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new ); 1039 1040 // Generate code to do a loop peel for the given loop (and body). 1041 // old_new is a temp array. 1042 void do_peeling( IdealLoopTree *loop, Node_List &old_new ); 1043 1044 // Add pre and post loops around the given loop. These loops are used 1045 // during RCE, unrolling and aligning loops. 1046 void insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only ); 1047 1048 // Add post loop after the given loop. 1049 Node *insert_post_loop(IdealLoopTree *loop, Node_List &old_new, 1050 CountedLoopNode *main_head, CountedLoopEndNode *main_end, 1051 Node *incr, Node *limit, CountedLoopNode *&post_head); 1052 1053 // Add an RCE'd post loop which we will multi-version adapt for run time test path usage 1054 void insert_scalar_rced_post_loop( IdealLoopTree *loop, Node_List &old_new ); 1055 1056 // Add a vector post loop between a vector main loop and the current post loop 1057 void insert_vector_post_loop(IdealLoopTree *loop, Node_List &old_new); 1058 // If Node n lives in the back_ctrl block, we clone a private version of n 1059 // in preheader_ctrl block and return that, otherwise return n. 1060 Node *clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones ); 1061 1062 // Take steps to maximally unroll the loop. Peel any odd iterations, then 1063 // unroll to do double iterations. The next round of major loop transforms 1064 // will repeat till the doubled loop body does all remaining iterations in 1 1065 // pass. 1066 void do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new ); 1067 1068 // Unroll the loop body one step - make each trip do 2 iterations. 1069 void do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip ); 1070 1071 // Mark vector reduction candidates before loop unrolling 1072 void mark_reductions( IdealLoopTree *loop ); 1073 1074 // Return true if exp is a constant times an induction var 1075 bool is_scaled_iv(Node* exp, Node* iv, int* p_scale); 1076 1077 // Return true if exp is a scaled induction var plus (or minus) constant 1078 bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth = 0); 1079 1080 // Create a new if above the uncommon_trap_if_pattern for the predicate to be promoted 1081 ProjNode* create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry, 1082 Deoptimization::DeoptReason reason, 1083 int opcode); 1084 void register_control(Node* n, IdealLoopTree *loop, Node* pred); 1085 1086 // Clone loop predicates to cloned loops (peeled, unswitched) 1087 static ProjNode* clone_predicate(ProjNode* predicate_proj, Node* new_entry, 1088 Deoptimization::DeoptReason reason, 1089 PhaseIdealLoop* loop_phase, 1090 PhaseIterGVN* igvn); 1091 1092 static void clone_loop_predicates_fix_mem(ProjNode* dom_proj , ProjNode* proj, 1093 PhaseIdealLoop* loop_phase, 1094 PhaseIterGVN* igvn); 1095 1096 static Node* clone_loop_predicates(Node* old_entry, Node* new_entry, 1097 bool clone_limit_check, 1098 PhaseIdealLoop* loop_phase, 1099 PhaseIterGVN* igvn); 1100 Node* clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check); 1101 1102 static Node* skip_all_loop_predicates(Node* entry); 1103 static Node* skip_loop_predicates(Node* entry); 1104 1105 // Find a good location to insert a predicate 1106 static ProjNode* find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason); 1107 // Find a predicate 1108 static Node* find_predicate(Node* entry); 1109 // Construct a range check for a predicate if 1110 BoolNode* rc_predicate(IdealLoopTree *loop, Node* ctrl, 1111 int scale, Node* offset, 1112 Node* init, Node* limit, jint stride, 1113 Node* range, bool upper, bool &overflow); 1114 1115 // Implementation of the loop predication to promote checks outside the loop 1116 bool loop_predication_impl(IdealLoopTree *loop); 1117 bool loop_predication_impl_helper(IdealLoopTree *loop, ProjNode* proj, ProjNode *predicate_proj, 1118 CountedLoopNode *cl, ConNode* zero, Invariance& invar, 1119 Deoptimization::DeoptReason reason); 1120 bool loop_predication_should_follow_branches(IdealLoopTree *loop, ProjNode *predicate_proj, float& loop_trip_cnt); 1121 void loop_predication_follow_branches(Node *c, IdealLoopTree *loop, float loop_trip_cnt, 1122 PathFrequency& pf, Node_Stack& stack, VectorSet& seen, 1123 Node_List& if_proj_list); 1124 ProjNode* insert_skeleton_predicate(IfNode* iff, IdealLoopTree *loop, 1125 ProjNode* proj, ProjNode *predicate_proj, 1126 ProjNode* upper_bound_proj, 1127 int scale, Node* offset, 1128 Node* init, Node* limit, jint stride, 1129 Node* rng, bool& overflow, 1130 Deoptimization::DeoptReason reason); 1131 Node* add_range_check_predicate(IdealLoopTree* loop, CountedLoopNode* cl, 1132 Node* predicate_proj, int scale_con, Node* offset, 1133 Node* limit, jint stride_con, Node* value); 1134 1135 // Helper function to collect predicate for eliminating the useless ones 1136 void collect_potentially_useful_predicates(IdealLoopTree *loop, Unique_Node_List &predicate_opaque1); 1137 void eliminate_useless_predicates(); 1138 1139 // Change the control input of expensive nodes to allow commoning by 1140 // IGVN when it is guaranteed to not result in a more frequent 1141 // execution of the expensive node. Return true if progress. 1142 bool process_expensive_nodes(); 1143 1144 // Check whether node has become unreachable 1145 bool is_node_unreachable(Node *n) const { 1146 return !has_node(n) || n->is_unreachable(_igvn); 1147 } 1148 1149 // Eliminate range-checks and other trip-counter vs loop-invariant tests. 1150 int do_range_check( IdealLoopTree *loop, Node_List &old_new ); 1151 1152 // Check to see if do_range_check(...) cleaned the main loop of range-checks 1153 void has_range_checks(IdealLoopTree *loop); 1154 1155 // Process post loops which have range checks and try to build a multi-version 1156 // guard to safely determine if we can execute the post loop which was RCE'd. 1157 bool multi_version_post_loops(IdealLoopTree *rce_loop, IdealLoopTree *legacy_loop); 1158 1159 // Cause the rce'd post loop to optimized away, this happens if we cannot complete multiverioning 1160 void poison_rce_post_loop(IdealLoopTree *rce_loop); 1161 1162 // Create a slow version of the loop by cloning the loop 1163 // and inserting an if to select fast-slow versions. 1164 ProjNode* create_slow_version_of_loop(IdealLoopTree *loop, 1165 Node_List &old_new, 1166 int opcode, 1167 CloneLoopMode mode); 1168 1169 // Clone a loop and return the clone head (clone_loop_head). 1170 // Added nodes include int(1), int(0) - disconnected, If, IfTrue, IfFalse, 1171 // This routine was created for usage in CountedLoopReserveKit. 1172 // 1173 // int(1) -> If -> IfTrue -> original_loop_head 1174 // | 1175 // V 1176 // IfFalse -> clone_loop_head (returned by function pointer) 1177 // 1178 LoopNode* create_reserve_version_of_loop(IdealLoopTree *loop, CountedLoopReserveKit* lk); 1179 // Clone loop with an invariant test (that does not exit) and 1180 // insert a clone of the test that selects which version to 1181 // execute. 1182 void do_unswitching (IdealLoopTree *loop, Node_List &old_new); 1183 1184 // Find candidate "if" for unswitching 1185 IfNode* find_unswitching_candidate(const IdealLoopTree *loop) const; 1186 1187 // Range Check Elimination uses this function! 1188 // Constrain the main loop iterations so the affine function: 1189 // low_limit <= scale_con * I + offset < upper_limit 1190 // always holds true. That is, either increase the number of iterations in 1191 // the pre-loop or the post-loop until the condition holds true in the main 1192 // loop. Scale_con, offset and limit are all loop invariant. 1193 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 ); 1194 // Helper function for add_constraint(). 1195 Node* adjust_limit(int stride_con, Node * scale, Node *offset, Node *rc_limit, Node *loop_limit, Node *pre_ctrl, bool round_up); 1196 1197 // Partially peel loop up through last_peel node. 1198 bool partial_peel( IdealLoopTree *loop, Node_List &old_new ); 1199 1200 // Create a scheduled list of nodes control dependent on ctrl set. 1201 void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched ); 1202 // Has a use in the vector set 1203 bool has_use_in_set( Node* n, VectorSet& vset ); 1204 // Has use internal to the vector set (ie. not in a phi at the loop head) 1205 bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ); 1206 // clone "n" for uses that are outside of loop 1207 int clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ); 1208 // clone "n" for special uses that are in the not_peeled region 1209 void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n, 1210 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ); 1211 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist 1212 void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ); 1213 #ifdef ASSERT 1214 // Validate the loop partition sets: peel and not_peel 1215 bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel ); 1216 // Ensure that uses outside of loop are of the right form 1217 bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list, 1218 uint orig_exit_idx, uint clone_exit_idx); 1219 bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx); 1220 #endif 1221 1222 // Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.) 1223 int stride_of_possible_iv( Node* iff ); 1224 bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; } 1225 // Return the (unique) control output node that's in the loop (if it exists.) 1226 Node* stay_in_loop( Node* n, IdealLoopTree *loop); 1227 // Insert a signed compare loop exit cloned from an unsigned compare. 1228 IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop); 1229 void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop); 1230 // Utility to register node "n" with PhaseIdealLoop 1231 void register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth); 1232 // Utility to create an if-projection 1233 ProjNode* proj_clone(ProjNode* p, IfNode* iff); 1234 // Force the iff control output to be the live_proj 1235 Node* short_circuit_if(IfNode* iff, ProjNode* live_proj); 1236 // Insert a region before an if projection 1237 RegionNode* insert_region_before_proj(ProjNode* proj); 1238 // Insert a new if before an if projection 1239 ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj); 1240 1241 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps. 1242 // "Nearly" because all Nodes have been cloned from the original in the loop, 1243 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs 1244 // through the Phi recursively, and return a Bool. 1245 Node *clone_iff( PhiNode *phi, IdealLoopTree *loop ); 1246 CmpNode *clone_bool( PhiNode *phi, IdealLoopTree *loop ); 1247 1248 1249 // Rework addressing expressions to get the most loop-invariant stuff 1250 // moved out. We'd like to do all associative operators, but it's especially 1251 // important (common) to do address expressions. 1252 Node *remix_address_expressions( Node *n ); 1253 1254 // Convert add to muladd to generate MuladdS2I under certain criteria 1255 Node * convert_add_to_muladd(Node * n); 1256 1257 // Attempt to use a conditional move instead of a phi/branch 1258 Node *conditional_move( Node *n ); 1259 1260 // Reorganize offset computations to lower register pressure. 1261 // Mostly prevent loop-fallout uses of the pre-incremented trip counter 1262 // (which are then alive with the post-incremented trip counter 1263 // forcing an extra register move) 1264 void reorg_offsets( IdealLoopTree *loop ); 1265 1266 // Check for aggressive application of 'split-if' optimization, 1267 // using basic block level info. 1268 void split_if_with_blocks ( VectorSet &visited, Node_Stack &nstack, bool last_round ); 1269 Node *split_if_with_blocks_pre ( Node *n ); 1270 void split_if_with_blocks_post( Node *n, bool last_round ); 1271 Node *has_local_phi_input( Node *n ); 1272 // Mark an IfNode as being dominated by a prior test, 1273 // without actually altering the CFG (and hence IDOM info). 1274 void dominated_by( Node *prevdom, Node *iff, bool flip = false, bool exclude_loop_predicate = false ); 1275 1276 // Split Node 'n' through merge point 1277 Node *split_thru_region( Node *n, Node *region ); 1278 // Split Node 'n' through merge point if there is enough win. 1279 Node *split_thru_phi( Node *n, Node *region, int policy ); 1280 // Found an If getting its condition-code input from a Phi in the 1281 // same block. Split thru the Region. 1282 void do_split_if( Node *iff ); 1283 1284 // Conversion of fill/copy patterns into intrisic versions 1285 bool do_intrinsify_fill(); 1286 bool intrinsify_fill(IdealLoopTree* lpt); 1287 bool match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value, 1288 Node*& shift, Node*& offset); 1289 1290 private: 1291 // Return a type based on condition control flow 1292 const TypeInt* filtered_type( Node *n, Node* n_ctrl); 1293 const TypeInt* filtered_type( Node *n ) { return filtered_type(n, NULL); } 1294 // Helpers for filtered type 1295 const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl); 1296 1297 // Helper functions 1298 Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache ); 1299 Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true ); 1300 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 ); 1301 bool split_up( Node *n, Node *blk1, Node *blk2 ); 1302 void sink_use( Node *use, Node *post_loop ); 1303 Node *place_near_use( Node *useblock ) const; 1304 Node* try_move_store_before_loop(Node* n, Node *n_ctrl); 1305 void try_move_store_after_loop(Node* n); 1306 bool identical_backtoback_ifs(Node *n); 1307 bool can_split_if(Node *n_ctrl); 1308 1309 bool _created_loop_node; 1310 public: 1311 void set_created_loop_node() { _created_loop_node = true; } 1312 bool created_loop_node() { return _created_loop_node; } 1313 void register_new_node( Node *n, Node *blk ); 1314 1315 #ifdef ASSERT 1316 void dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA); 1317 #endif 1318 1319 #ifndef PRODUCT 1320 void dump( ) const; 1321 void dump( IdealLoopTree *loop, uint rpo_idx, Node_List &rpo_list ) const; 1322 void verify() const; // Major slow :-) 1323 void verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const; 1324 IdealLoopTree *get_loop_idx(Node* n) const { 1325 // Dead nodes have no loop, so return the top level loop instead 1326 return _nodes[n->_idx] ? (IdealLoopTree*)_nodes[n->_idx] : _ltree_root; 1327 } 1328 // Print some stats 1329 static void print_statistics(); 1330 static int _loop_invokes; // Count of PhaseIdealLoop invokes 1331 static int _loop_work; // Sum of PhaseIdealLoop x _unique 1332 #endif 1333 void rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const; 1334 }; 1335 1336 // This kit may be used for making of a reserved copy of a loop before this loop 1337 // goes under non-reversible changes. 1338 // 1339 // Function create_reserve() creates a reserved copy (clone) of the loop. 1340 // The reserved copy is created by calling 1341 // PhaseIdealLoop::create_reserve_version_of_loop - see there how 1342 // the original and reserved loops are connected in the outer graph. 1343 // If create_reserve succeeded, it returns 'true' and _has_reserved is set to 'true'. 1344 // 1345 // By default the reserved copy (clone) of the loop is created as dead code - it is 1346 // dominated in the outer loop by this node chain: 1347 // intcon(1)->If->IfFalse->reserved_copy. 1348 // The original loop is dominated by the the same node chain but IfTrue projection: 1349 // intcon(0)->If->IfTrue->original_loop. 1350 // 1351 // In this implementation of CountedLoopReserveKit the ctor includes create_reserve() 1352 // and the dtor, checks _use_new value. 1353 // If _use_new == false, it "switches" control to reserved copy of the loop 1354 // by simple replacing of node intcon(1) with node intcon(0). 1355 // 1356 // Here is a proposed example of usage (see also SuperWord::output in superword.cpp). 1357 // 1358 // void CountedLoopReserveKit_example() 1359 // { 1360 // CountedLoopReserveKit lrk((phase, lpt, DoReserveCopy = true); // create local object 1361 // if (DoReserveCopy && !lrk.has_reserved()) { 1362 // return; //failed to create reserved loop copy 1363 // } 1364 // ... 1365 // //something is wrong, switch to original loop 1366 /// if(something_is_wrong) return; // ~CountedLoopReserveKit makes the switch 1367 // ... 1368 // //everything worked ok, return with the newly modified loop 1369 // lrk.use_new(); 1370 // return; // ~CountedLoopReserveKit does nothing once use_new() was called 1371 // } 1372 // 1373 // Keep in mind, that by default if create_reserve() is not followed by use_new() 1374 // the dtor will "switch to the original" loop. 1375 // NOTE. You you modify outside of the original loop this class is no help. 1376 // 1377 class CountedLoopReserveKit { 1378 private: 1379 PhaseIdealLoop* _phase; 1380 IdealLoopTree* _lpt; 1381 LoopNode* _lp; 1382 IfNode* _iff; 1383 LoopNode* _lp_reserved; 1384 bool _has_reserved; 1385 bool _use_new; 1386 const bool _active; //may be set to false in ctor, then the object is dummy 1387 1388 public: 1389 CountedLoopReserveKit(PhaseIdealLoop* phase, IdealLoopTree *loop, bool active); 1390 ~CountedLoopReserveKit(); 1391 void use_new() {_use_new = true;} 1392 void set_iff(IfNode* x) {_iff = x;} 1393 bool has_reserved() const { return _active && _has_reserved;} 1394 private: 1395 bool create_reserve(); 1396 };// class CountedLoopReserveKit 1397 1398 inline Node* IdealLoopTree::tail() { 1399 // Handle lazy update of _tail field 1400 Node *n = _tail; 1401 //while( !n->in(0) ) // Skip dead CFG nodes 1402 //n = n->in(1); 1403 if (n->in(0) == NULL) 1404 n = _phase->get_ctrl(n); 1405 _tail = n; 1406 return n; 1407 } 1408 1409 1410 // Iterate over the loop tree using a preorder, left-to-right traversal. 1411 // 1412 // Example that visits all counted loops from within PhaseIdealLoop 1413 // 1414 // for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) { 1415 // IdealLoopTree* lpt = iter.current(); 1416 // if (!lpt->is_counted()) continue; 1417 // ... 1418 class LoopTreeIterator : public StackObj { 1419 private: 1420 IdealLoopTree* _root; 1421 IdealLoopTree* _curnt; 1422 1423 public: 1424 LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {} 1425 1426 bool done() { return _curnt == NULL; } // Finished iterating? 1427 1428 void next(); // Advance to next loop tree 1429 1430 IdealLoopTree* current() { return _curnt; } // Return current value of iterator. 1431 }; 1432 1433 #endif // SHARE_VM_OPTO_LOOPNODE_HPP