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