1 /*
2 * Copyright (c) 1998, 2025, 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 *
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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.
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21 * questions.
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23 */
24
25 #ifndef SHARE_OPTO_LOOPNODE_HPP
26 #define SHARE_OPTO_LOOPNODE_HPP
27
28 #include "opto/cfgnode.hpp"
29 #include "opto/multnode.hpp"
30 #include "opto/phaseX.hpp"
31 #include "opto/predicates.hpp"
32 #include "opto/subnode.hpp"
33 #include "opto/type.hpp"
34 #include "utilities/checkedCast.hpp"
35
36 class CmpNode;
37 class BaseCountedLoopEndNode;
38 class CountedLoopNode;
39 class IdealLoopTree;
40 class LoopNode;
41 class Node;
42 class OuterStripMinedLoopEndNode;
43 class PredicateBlock;
44 class PathFrequency;
45 class PhaseIdealLoop;
46 class UnswitchCandidate;
47 class LoopSelector;
48 class UnswitchedLoopSelector;
49 class VectorSet;
50 class VSharedData;
51 class Invariance;
52 struct small_cache;
53
54 //
55 // I D E A L I Z E D L O O P S
56 //
57 // Idealized loops are the set of loops I perform more interesting
58 // transformations on, beyond simple hoisting.
59
60 //------------------------------LoopNode---------------------------------------
61 // Simple loop header. Fall in path on left, loop-back path on right.
62 class LoopNode : public RegionNode {
63 // Size is bigger to hold the flags. However, the flags do not change
64 // the semantics so it does not appear in the hash & cmp functions.
65 virtual uint size_of() const { return sizeof(*this); }
66 protected:
67 uint _loop_flags;
68 // Names for flag bitfields
69 enum { Normal=0, Pre=1, Main=2, Post=3, PreMainPostFlagsMask=3,
70 MainHasNoPreLoop = 1<<2,
71 HasExactTripCount = 1<<3,
72 InnerLoop = 1<<4,
73 PartialPeelLoop = 1<<5,
74 PartialPeelFailed = 1<<6,
75 WasSlpAnalyzed = 1<<7,
76 PassedSlpAnalysis = 1<<8,
77 DoUnrollOnly = 1<<9,
78 VectorizedLoop = 1<<10,
79 HasAtomicPostLoop = 1<<11,
80 StripMined = 1<<12,
81 SubwordLoop = 1<<13,
82 ProfileTripFailed = 1<<14,
83 LoopNestInnerLoop = 1<<15,
84 LoopNestLongOuterLoop = 1<<16,
85 MultiversionFastLoop = 1<<17,
86 MultiversionSlowLoop = 2<<17,
87 MultiversionDelayedSlowLoop = 3<<17,
88 MultiversionFlagsMask = 3<<17,
89 FlatArrays = 1<<18};
90 char _unswitch_count;
91 enum { _unswitch_max=3 };
92
93 // Expected trip count from profile data
94 float _profile_trip_cnt;
95
96 public:
97 // Names for edge indices
98 enum { Self=0, EntryControl, LoopBackControl };
99
100 bool is_inner_loop() const { return _loop_flags & InnerLoop; }
101 void set_inner_loop() { _loop_flags |= InnerLoop; }
102
103 bool is_vectorized_loop() const { return _loop_flags & VectorizedLoop; }
104 bool is_partial_peel_loop() const { return _loop_flags & PartialPeelLoop; }
105 void set_partial_peel_loop() { _loop_flags |= PartialPeelLoop; }
106 bool partial_peel_has_failed() const { return _loop_flags & PartialPeelFailed; }
107 bool is_strip_mined() const { return _loop_flags & StripMined; }
108 bool is_profile_trip_failed() const { return _loop_flags & ProfileTripFailed; }
109 bool is_subword_loop() const { return _loop_flags & SubwordLoop; }
110 bool is_loop_nest_inner_loop() const { return _loop_flags & LoopNestInnerLoop; }
111 bool is_loop_nest_outer_loop() const { return _loop_flags & LoopNestLongOuterLoop; }
112 bool is_flat_arrays() const { return _loop_flags & FlatArrays; }
113
114 void mark_partial_peel_failed() { _loop_flags |= PartialPeelFailed; }
115 void mark_was_slp() { _loop_flags |= WasSlpAnalyzed; }
116 void mark_passed_slp() { _loop_flags |= PassedSlpAnalysis; }
117 void mark_do_unroll_only() { _loop_flags |= DoUnrollOnly; }
118 void mark_loop_vectorized() { _loop_flags |= VectorizedLoop; }
119 void mark_has_atomic_post_loop() { _loop_flags |= HasAtomicPostLoop; }
120 void mark_strip_mined() { _loop_flags |= StripMined; }
121 void clear_strip_mined() { _loop_flags &= ~StripMined; }
122 void mark_profile_trip_failed() { _loop_flags |= ProfileTripFailed; }
123 void mark_subword_loop() { _loop_flags |= SubwordLoop; }
124 void mark_loop_nest_inner_loop() { _loop_flags |= LoopNestInnerLoop; }
125 void mark_loop_nest_outer_loop() { _loop_flags |= LoopNestLongOuterLoop; }
126 void mark_flat_arrays() { _loop_flags |= FlatArrays; }
127
128 int unswitch_max() { return _unswitch_max; }
129 int unswitch_count() { return _unswitch_count; }
130
131 void set_unswitch_count(int val) {
132 assert (val <= unswitch_max(), "too many unswitches");
133 _unswitch_count = val;
134 }
135
136 void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; }
137 float profile_trip_cnt() { return _profile_trip_cnt; }
138
139 #ifndef PRODUCT
140 uint _stress_peeling_attempts = 0;
141 #endif
142
143 LoopNode(Node *entry, Node *backedge)
144 : RegionNode(3), _loop_flags(0), _unswitch_count(0),
145 _profile_trip_cnt(COUNT_UNKNOWN) {
146 init_class_id(Class_Loop);
147 init_req(EntryControl, entry);
148 init_req(LoopBackControl, backedge);
149 }
150
151 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
152 virtual int Opcode() const;
153 bool can_be_counted_loop(PhaseValues* phase) const {
154 return req() == 3 && in(0) != nullptr &&
155 in(1) != nullptr && phase->type(in(1)) != Type::TOP &&
156 in(2) != nullptr && phase->type(in(2)) != Type::TOP;
157 }
158 bool is_valid_counted_loop(BasicType bt) const;
159 #ifndef PRODUCT
160 virtual void dump_spec(outputStream *st) const;
161 #endif
162
163 void verify_strip_mined(int expect_skeleton) const NOT_DEBUG_RETURN;
164 virtual LoopNode* skip_strip_mined(int expect_skeleton = 1) { return this; }
165 virtual IfTrueNode* outer_loop_tail() const { ShouldNotReachHere(); return nullptr; }
166 virtual OuterStripMinedLoopEndNode* outer_loop_end() const { ShouldNotReachHere(); return nullptr; }
167 virtual IfFalseNode* outer_loop_exit() const { ShouldNotReachHere(); return nullptr; }
168 virtual SafePointNode* outer_safepoint() const { ShouldNotReachHere(); return nullptr; }
169 };
170
171 //------------------------------Counted Loops----------------------------------
172 // Counted loops are all trip-counted loops, with exactly 1 trip-counter exit
173 // path (and maybe some other exit paths). The trip-counter exit is always
174 // last in the loop. The trip-counter have to stride by a constant;
175 // the exit value is also loop invariant.
176
177 // CountedLoopNodes and CountedLoopEndNodes come in matched pairs. The
178 // CountedLoopNode has the incoming loop control and the loop-back-control
179 // which is always the IfTrue before the matching CountedLoopEndNode. The
180 // CountedLoopEndNode has an incoming control (possibly not the
181 // CountedLoopNode if there is control flow in the loop), the post-increment
182 // trip-counter value, and the limit. The trip-counter value is always of
183 // the form (Op old-trip-counter stride). The old-trip-counter is produced
184 // by a Phi connected to the CountedLoopNode. The stride is constant.
185 // The Op is any commutable opcode, including Add, Mul, Xor. The
186 // CountedLoopEndNode also takes in the loop-invariant limit value.
187
188 // From a CountedLoopNode I can reach the matching CountedLoopEndNode via the
189 // loop-back control. From CountedLoopEndNodes I can reach CountedLoopNodes
190 // via the old-trip-counter from the Op node.
191
192 //------------------------------CountedLoopNode--------------------------------
193 // CountedLoopNodes head simple counted loops. CountedLoopNodes have as
194 // inputs the incoming loop-start control and the loop-back control, so they
195 // act like RegionNodes. They also take in the initial trip counter, the
196 // loop-invariant stride and the loop-invariant limit value. CountedLoopNodes
197 // produce a loop-body control and the trip counter value. Since
198 // CountedLoopNodes behave like RegionNodes I still have a standard CFG model.
199
200 class BaseCountedLoopNode : public LoopNode {
201 public:
202 BaseCountedLoopNode(Node *entry, Node *backedge)
203 : LoopNode(entry, backedge) {
204 }
205
206 Node *init_control() const { return in(EntryControl); }
207 Node *back_control() const { return in(LoopBackControl); }
208
209 Node* init_trip() const;
210 Node* stride() const;
211 bool stride_is_con() const;
212 Node* limit() const;
213 Node* incr() const;
214 Node* phi() const;
215
216 BaseCountedLoopEndNode* loopexit_or_null() const;
217 BaseCountedLoopEndNode* loopexit() const;
218
219 virtual BasicType bt() const = 0;
220
221 jlong stride_con() const;
222
223 static BaseCountedLoopNode* make(Node* entry, Node* backedge, BasicType bt);
224
225 virtual void set_trip_count(julong tc) = 0;
226 virtual julong trip_count() const = 0;
227
228 bool has_exact_trip_count() const { return (_loop_flags & HasExactTripCount) != 0; }
229 void set_exact_trip_count(julong tc) {
230 set_trip_count(tc);
231 _loop_flags |= HasExactTripCount;
232 }
233 void set_nonexact_trip_count() {
234 _loop_flags &= ~HasExactTripCount;
235 }
236 };
237
238
239 class CountedLoopNode : public BaseCountedLoopNode {
240 // Size is bigger to hold _main_idx. However, _main_idx does not change
241 // the semantics so it does not appear in the hash & cmp functions.
242 virtual uint size_of() const { return sizeof(*this); }
243
244 // For Pre- and Post-loops during debugging ONLY, this holds the index of
245 // the Main CountedLoop. Used to assert that we understand the graph shape.
246 node_idx_t _main_idx;
247
248 // Known trip count calculated by compute_exact_trip_count()
249 uint _trip_count;
250
251 // Log2 of original loop bodies in unrolled loop
252 int _unrolled_count_log2;
253
254 // Node count prior to last unrolling - used to decide if
255 // unroll,optimize,unroll,optimize,... is making progress
256 int _node_count_before_unroll;
257
258 // If slp analysis is performed we record the maximum
259 // vector mapped unroll factor here
260 int _slp_maximum_unroll_factor;
261
262 public:
263 CountedLoopNode(Node *entry, Node *backedge)
264 : BaseCountedLoopNode(entry, backedge), _main_idx(0), _trip_count(max_juint),
265 _unrolled_count_log2(0), _node_count_before_unroll(0),
266 _slp_maximum_unroll_factor(0) {
267 init_class_id(Class_CountedLoop);
268 // Initialize _trip_count to the largest possible value.
269 // Will be reset (lower) if the loop's trip count is known.
270 }
271
272 virtual int Opcode() const;
273 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
274
275 CountedLoopEndNode* loopexit_or_null() const { return (CountedLoopEndNode*) BaseCountedLoopNode::loopexit_or_null(); }
276 CountedLoopEndNode* loopexit() const { return (CountedLoopEndNode*) BaseCountedLoopNode::loopexit(); }
277 int stride_con() const;
278
279 // Match increment with optional truncation
280 static Node*
281 match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInteger** trunc_type,
282 BasicType bt);
283
284 // A 'main' loop has a pre-loop and a post-loop. The 'main' loop
285 // can run short a few iterations and may start a few iterations in.
286 // It will be RCE'd and unrolled and aligned.
287
288 // A following 'post' loop will run any remaining iterations. Used
289 // during Range Check Elimination, the 'post' loop will do any final
290 // iterations with full checks. Also used by Loop Unrolling, where
291 // the 'post' loop will do any epilog iterations needed. Basically,
292 // a 'post' loop can not profitably be further unrolled or RCE'd.
293
294 // A preceding 'pre' loop will run at least 1 iteration (to do peeling),
295 // it may do under-flow checks for RCE and may do alignment iterations
296 // so the following main loop 'knows' that it is striding down cache
297 // lines.
298
299 // A 'main' loop that is ONLY unrolled or peeled, never RCE'd or
300 // Aligned, may be missing it's pre-loop.
301 bool is_normal_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Normal; }
302 bool is_pre_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Pre; }
303 bool is_main_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Main; }
304 bool is_post_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Post; }
305 bool was_slp_analyzed () const { return (_loop_flags&WasSlpAnalyzed) == WasSlpAnalyzed; }
306 bool has_passed_slp () const { return (_loop_flags&PassedSlpAnalysis) == PassedSlpAnalysis; }
307 bool is_unroll_only () const { return (_loop_flags&DoUnrollOnly) == DoUnrollOnly; }
308 bool is_main_no_pre_loop() const { return _loop_flags & MainHasNoPreLoop; }
309 bool has_atomic_post_loop () const { return (_loop_flags & HasAtomicPostLoop) == HasAtomicPostLoop; }
310 void set_main_no_pre_loop() { _loop_flags |= MainHasNoPreLoop; }
311
312 IfNode* find_multiversion_if_from_multiversion_fast_main_loop();
313
314 int main_idx() const { return _main_idx; }
315
316 void set_trip_count(julong tc) {
317 assert(tc < max_juint, "Cannot set trip count to max_juint");
318 _trip_count = checked_cast<uint>(tc);
319 }
320 julong trip_count() const { return _trip_count; }
321
322 void set_pre_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; }
323 void set_main_loop ( ) { assert(is_normal_loop(),""); _loop_flags |= Main; }
324 void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; }
325 void set_normal_loop( ) { _loop_flags &= ~PreMainPostFlagsMask; }
326
327 void set_notpassed_slp() {
328 _loop_flags &= ~PassedSlpAnalysis;
329 }
330
331 void double_unrolled_count() { _unrolled_count_log2++; }
332 int unrolled_count() { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); }
333
334 void set_node_count_before_unroll(int ct) { _node_count_before_unroll = ct; }
335 int node_count_before_unroll() { return _node_count_before_unroll; }
336 void set_slp_max_unroll(int unroll_factor) { _slp_maximum_unroll_factor = unroll_factor; }
337 int slp_max_unroll() const { return _slp_maximum_unroll_factor; }
338
339 // Multiversioning allows us to duplicate a CountedLoop, and have two versions, and the multiversion_if
340 // decides which one is taken:
341 // (1) fast_loop: We enter this loop by default, by default the multiversion_if has its condition set to
342 // "true", guarded by a OpaqueMultiversioning. If we want to make a speculative assumption
343 // for an optimization, we can add the runtime-check to the multiversion_if, and if the
344 // assumption fails we take the slow_loop instead, where we do not make the same speculative
345 // assumption.
346 // We call it the "fast_loop" because it has more optimizations, enabled by the speculative
347 // runtime-checks at the multiversion_if, and we expect the fast_loop to execute faster.
348 // (2) slow_loop: By default, it is not taken, until a runtime-check is added to the multiversion_if while
349 // optimizing the fast_looop. If such a runtime-check is never added, then after loop-opts
350 // the multiversion_if constant folds to true, and the slow_loop is folded away. To save
351 // compile time, we delay the optimization of the slow_loop until a runtime-check is added
352 // to the multiversion_if, at which point we resume optimizations for the slow_loop.
353 // We call it the "slow_loop" because it has fewer optimizations, since this is the fall-back
354 // loop where we do not make any of the speculative assumptions we make for the fast_loop.
355 // Hence, we expect the slow_loop to execute slower.
356 bool is_multiversion() const { return (_loop_flags & MultiversionFlagsMask) != Normal; }
357 bool is_multiversion_fast_loop() const { return (_loop_flags & MultiversionFlagsMask) == MultiversionFastLoop; }
358 bool is_multiversion_slow_loop() const { return (_loop_flags & MultiversionFlagsMask) == MultiversionSlowLoop; }
359 bool is_multiversion_delayed_slow_loop() const { return (_loop_flags & MultiversionFlagsMask) == MultiversionDelayedSlowLoop; }
360 void set_multiversion_fast_loop() { assert(!is_multiversion(), ""); _loop_flags |= MultiversionFastLoop; }
361 void set_multiversion_slow_loop() { assert(!is_multiversion(), ""); _loop_flags |= MultiversionSlowLoop; }
362 void set_multiversion_delayed_slow_loop() { assert(!is_multiversion(), ""); _loop_flags |= MultiversionDelayedSlowLoop; }
363 void set_no_multiversion() { assert( is_multiversion(), ""); _loop_flags &= ~MultiversionFlagsMask; }
364
365 virtual LoopNode* skip_strip_mined(int expect_skeleton = 1);
366 OuterStripMinedLoopNode* outer_loop() const;
367 virtual IfTrueNode* outer_loop_tail() const;
368 virtual OuterStripMinedLoopEndNode* outer_loop_end() const;
369 virtual IfFalseNode* outer_loop_exit() const;
370 virtual SafePointNode* outer_safepoint() const;
371
372 Node* skip_assertion_predicates_with_halt();
373
374 virtual BasicType bt() const {
375 return T_INT;
376 }
377
378 Node* is_canonical_loop_entry();
379 CountedLoopEndNode* find_pre_loop_end();
380
381 Node* uncasted_init_trip(bool uncasted);
382
383 #ifndef PRODUCT
384 virtual void dump_spec(outputStream *st) const;
385 #endif
386 };
387
388 class LongCountedLoopNode : public BaseCountedLoopNode {
389 private:
390 virtual uint size_of() const { return sizeof(*this); }
391
392 // Known trip count calculated by compute_exact_trip_count()
393 julong _trip_count;
394
395 public:
396 LongCountedLoopNode(Node *entry, Node *backedge)
397 : BaseCountedLoopNode(entry, backedge), _trip_count(max_julong) {
398 init_class_id(Class_LongCountedLoop);
399 }
400
401 virtual int Opcode() const;
402
403 virtual BasicType bt() const {
404 return T_LONG;
405 }
406
407 void set_trip_count(julong tc) {
408 assert(tc < max_julong, "Cannot set trip count to max_julong");
409 _trip_count = tc;
410 }
411 julong trip_count() const { return _trip_count; }
412
413 LongCountedLoopEndNode* loopexit_or_null() const { return (LongCountedLoopEndNode*) BaseCountedLoopNode::loopexit_or_null(); }
414 LongCountedLoopEndNode* loopexit() const { return (LongCountedLoopEndNode*) BaseCountedLoopNode::loopexit(); }
415 };
416
417
418 //------------------------------CountedLoopEndNode-----------------------------
419 // CountedLoopEndNodes end simple trip counted loops. They act much like
420 // IfNodes.
421
422 class BaseCountedLoopEndNode : public IfNode {
423 public:
424 enum { TestControl, TestValue };
425 BaseCountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
426 : IfNode(control, test, prob, cnt) {
427 init_class_id(Class_BaseCountedLoopEnd);
428 }
429
430 Node *cmp_node() const { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : nullptr; }
431 Node* incr() const { Node* tmp = cmp_node(); return (tmp && tmp->req() == 3) ? tmp->in(1) : nullptr; }
432 Node* limit() const { Node* tmp = cmp_node(); return (tmp && tmp->req() == 3) ? tmp->in(2) : nullptr; }
433 Node* stride() const { Node* tmp = incr(); return (tmp && tmp->req() == 3) ? tmp->in(2) : nullptr; }
434 Node* init_trip() const { Node* tmp = phi(); return (tmp && tmp->req() == 3) ? tmp->in(1) : nullptr; }
435 bool stride_is_con() const { Node *tmp = stride(); return (tmp != nullptr && tmp->is_Con()); }
436
437 PhiNode* phi() const {
438 Node* tmp = incr();
439 if (tmp && tmp->req() == 3) {
440 Node* phi = tmp->in(1);
441 if (phi->is_Phi()) {
442 return phi->as_Phi();
443 }
444 }
445 return nullptr;
446 }
447
448 BaseCountedLoopNode* loopnode() const {
449 // The CountedLoopNode that goes with this CountedLoopEndNode may
450 // have been optimized out by the IGVN so be cautious with the
451 // pattern matching on the graph
452 PhiNode* iv_phi = phi();
453 if (iv_phi == nullptr) {
454 return nullptr;
455 }
456 Node* ln = iv_phi->in(0);
457 if (!ln->is_BaseCountedLoop() || ln->as_BaseCountedLoop()->loopexit_or_null() != this) {
458 return nullptr;
459 }
460 if (ln->as_BaseCountedLoop()->bt() != bt()) {
461 return nullptr;
462 }
463 return ln->as_BaseCountedLoop();
464 }
465
466 BoolTest::mask test_trip() const { return in(TestValue)->as_Bool()->_test._test; }
467
468 jlong stride_con() const;
469 virtual BasicType bt() const = 0;
470
471 static BaseCountedLoopEndNode* make(Node* control, Node* test, float prob, float cnt, BasicType bt);
472 };
473
474 class CountedLoopEndNode : public BaseCountedLoopEndNode {
475 public:
476
477 CountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
478 : BaseCountedLoopEndNode(control, test, prob, cnt) {
479 init_class_id(Class_CountedLoopEnd);
480 }
481 virtual int Opcode() const;
482
483 CountedLoopNode* loopnode() const {
484 return (CountedLoopNode*) BaseCountedLoopEndNode::loopnode();
485 }
486
487 virtual BasicType bt() const {
488 return T_INT;
489 }
490
491 #ifndef PRODUCT
492 virtual void dump_spec(outputStream *st) const;
493 #endif
494 };
495
496 class LongCountedLoopEndNode : public BaseCountedLoopEndNode {
497 public:
498 LongCountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
499 : BaseCountedLoopEndNode(control, test, prob, cnt) {
500 init_class_id(Class_LongCountedLoopEnd);
501 }
502
503 LongCountedLoopNode* loopnode() const {
504 return (LongCountedLoopNode*) BaseCountedLoopEndNode::loopnode();
505 }
506
507 virtual int Opcode() const;
508
509 virtual BasicType bt() const {
510 return T_LONG;
511 }
512 };
513
514
515 inline BaseCountedLoopEndNode* BaseCountedLoopNode::loopexit_or_null() const {
516 Node* bctrl = back_control();
517 if (bctrl == nullptr) return nullptr;
518
519 Node* lexit = bctrl->in(0);
520 if (!lexit->is_BaseCountedLoopEnd()) {
521 return nullptr;
522 }
523 BaseCountedLoopEndNode* result = lexit->as_BaseCountedLoopEnd();
524 if (result->bt() != bt()) {
525 return nullptr;
526 }
527 return result;
528 }
529
530 inline BaseCountedLoopEndNode* BaseCountedLoopNode::loopexit() const {
531 BaseCountedLoopEndNode* cle = loopexit_or_null();
532 assert(cle != nullptr, "loopexit is null");
533 return cle;
534 }
535
536 inline Node* BaseCountedLoopNode::init_trip() const {
537 BaseCountedLoopEndNode* cle = loopexit_or_null();
538 return cle != nullptr ? cle->init_trip() : nullptr;
539 }
540 inline Node* BaseCountedLoopNode::stride() const {
541 BaseCountedLoopEndNode* cle = loopexit_or_null();
542 return cle != nullptr ? cle->stride() : nullptr;
543 }
544
545 inline bool BaseCountedLoopNode::stride_is_con() const {
546 BaseCountedLoopEndNode* cle = loopexit_or_null();
547 return cle != nullptr && cle->stride_is_con();
548 }
549 inline Node* BaseCountedLoopNode::limit() const {
550 BaseCountedLoopEndNode* cle = loopexit_or_null();
551 return cle != nullptr ? cle->limit() : nullptr;
552 }
553 inline Node* BaseCountedLoopNode::incr() const {
554 BaseCountedLoopEndNode* cle = loopexit_or_null();
555 return cle != nullptr ? cle->incr() : nullptr;
556 }
557 inline Node* BaseCountedLoopNode::phi() const {
558 BaseCountedLoopEndNode* cle = loopexit_or_null();
559 return cle != nullptr ? cle->phi() : nullptr;
560 }
561
562 inline jlong BaseCountedLoopNode::stride_con() const {
563 BaseCountedLoopEndNode* cle = loopexit_or_null();
564 return cle != nullptr ? cle->stride_con() : 0;
565 }
566
567
568 //------------------------------LoopLimitNode-----------------------------
569 // Counted Loop limit node which represents exact final iterator value:
570 // trip_count = (limit - init_trip + stride - 1)/stride
571 // final_value= trip_count * stride + init_trip.
572 // Use HW instructions to calculate it when it can overflow in integer.
573 // Note, final_value should fit into integer since counted loop has
574 // limit check: limit <= max_int-stride.
575 class LoopLimitNode : public Node {
576 enum { Init=1, Limit=2, Stride=3 };
577 public:
578 LoopLimitNode( Compile* C, Node *init, Node *limit, Node *stride ) : Node(nullptr,init,limit,stride) {
579 // Put it on the Macro nodes list to optimize during macro nodes expansion.
580 init_flags(Flag_is_macro);
581 C->add_macro_node(this);
582 }
583 virtual int Opcode() const;
584 virtual const Type *bottom_type() const { return TypeInt::INT; }
585 virtual uint ideal_reg() const { return Op_RegI; }
586 virtual const Type* Value(PhaseGVN* phase) const;
587 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
588 virtual Node* Identity(PhaseGVN* phase);
589 };
590
591 // Support for strip mining
592 class OuterStripMinedLoopNode : public LoopNode {
593 private:
594 void fix_sunk_stores_when_back_to_counted_loop(PhaseIterGVN* igvn, PhaseIdealLoop* iloop) const;
595 void handle_sunk_stores_when_finishing_construction(PhaseIterGVN* igvn);
596
597 public:
598 OuterStripMinedLoopNode(Compile* C, Node *entry, Node *backedge)
599 : LoopNode(entry, backedge) {
600 init_class_id(Class_OuterStripMinedLoop);
601 init_flags(Flag_is_macro);
602 C->add_macro_node(this);
603 }
604
605 virtual int Opcode() const;
606
607 virtual IfTrueNode* outer_loop_tail() const;
608 virtual OuterStripMinedLoopEndNode* outer_loop_end() const;
609 virtual IfFalseNode* outer_loop_exit() const;
610 virtual SafePointNode* outer_safepoint() const;
611 CountedLoopNode* inner_counted_loop() const { return unique_ctrl_out()->as_CountedLoop(); }
612 CountedLoopEndNode* inner_counted_loop_end() const { return inner_counted_loop()->loopexit(); }
613 IfFalseNode* inner_loop_exit() const { return inner_counted_loop_end()->proj_out(false)->as_IfFalse(); }
614
615 void adjust_strip_mined_loop(PhaseIterGVN* igvn);
616
617 void remove_outer_loop_and_safepoint(PhaseIterGVN* igvn) const;
618
619 void transform_to_counted_loop(PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
620
621 static Node* register_new_node(Node* node, LoopNode* ctrl, PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
622
623 Node* register_control(Node* node, Node* loop, Node* idom, PhaseIterGVN* igvn,
624 PhaseIdealLoop* iloop);
625 };
626
627 class OuterStripMinedLoopEndNode : public IfNode {
628 public:
629 OuterStripMinedLoopEndNode(Node *control, Node *test, float prob, float cnt)
630 : IfNode(control, test, prob, cnt) {
631 init_class_id(Class_OuterStripMinedLoopEnd);
632 }
633
634 virtual int Opcode() const;
635
636 virtual const Type* Value(PhaseGVN* phase) const;
637 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
638
639 bool is_expanded(PhaseGVN *phase) const;
640 };
641
642 // -----------------------------IdealLoopTree----------------------------------
643 class IdealLoopTree : public ResourceObj {
644 public:
645 IdealLoopTree *_parent; // Parent in loop tree
646 IdealLoopTree *_next; // Next sibling in loop tree
647 IdealLoopTree *_child; // First child in loop tree
648
649 // The head-tail backedge defines the loop.
650 // If a loop has multiple backedges, this is addressed during cleanup where
651 // we peel off the multiple backedges, merging all edges at the bottom and
652 // ensuring that one proper backedge flow into the loop.
653 Node *_head; // Head of loop
654 Node *_tail; // Tail of loop
655 inline Node *tail(); // Handle lazy update of _tail field
656 inline Node *head(); // Handle lazy update of _head field
657 PhaseIdealLoop* _phase;
658 int _local_loop_unroll_limit;
659 int _local_loop_unroll_factor;
660
661 Node_List _body; // Loop body for inner loops
662
663 uint16_t _nest; // Nesting depth
664 uint8_t _irreducible:1, // True if irreducible
665 _has_call:1, // True if has call safepoint
666 _has_sfpt:1, // True if has non-call safepoint
667 _rce_candidate:1, // True if candidate for range check elimination
668 _has_range_checks:1,
669 _has_range_checks_computed:1;
670
671 Node_List* _safepts; // List of safepoints in this loop
672 Node_List* _required_safept; // A inner loop cannot delete these safepts;
673 bool _allow_optimizations; // Allow loop optimizations
674
675 IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail )
676 : _parent(nullptr), _next(nullptr), _child(nullptr),
677 _head(head), _tail(tail),
678 _phase(phase),
679 _local_loop_unroll_limit(0), _local_loop_unroll_factor(0),
680 _body(Compile::current()->comp_arena()),
681 _nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0),
682 _has_range_checks(0), _has_range_checks_computed(0),
683 _safepts(nullptr),
684 _required_safept(nullptr),
685 _allow_optimizations(true)
686 {
687 precond(_head != nullptr);
688 precond(_tail != nullptr);
689 }
690
691 // Is 'l' a member of 'this'?
692 bool is_member(const IdealLoopTree *l) const; // Test for nested membership
693
694 // Set loop nesting depth. Accumulate has_call bits.
695 int set_nest( uint depth );
696
697 // Split out multiple fall-in edges from the loop header. Move them to a
698 // private RegionNode before the loop. This becomes the loop landing pad.
699 void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt );
700
701 // Split out the outermost loop from this shared header.
702 void split_outer_loop( PhaseIdealLoop *phase );
703
704 // Merge all the backedges from the shared header into a private Region.
705 // Feed that region as the one backedge to this loop.
706 void merge_many_backedges( PhaseIdealLoop *phase );
707
708 // Split shared headers and insert loop landing pads.
709 // Insert a LoopNode to replace the RegionNode.
710 // Returns TRUE if loop tree is structurally changed.
711 bool beautify_loops( PhaseIdealLoop *phase );
712
713 // Perform optimization to use the loop predicates for null checks and range checks.
714 // Applies to any loop level (not just the innermost one)
715 bool loop_predication( PhaseIdealLoop *phase);
716 bool can_apply_loop_predication();
717
718 // Perform iteration-splitting on inner loops. Split iterations to
719 // avoid range checks or one-shot null checks. Returns false if the
720 // current round of loop opts should stop.
721 bool iteration_split( PhaseIdealLoop *phase, Node_List &old_new );
722
723 // Driver for various flavors of iteration splitting. Returns false
724 // if the current round of loop opts should stop.
725 bool iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new );
726
727 // Given dominators, try to find loops with calls that must always be
728 // executed (call dominates loop tail). These loops do not need non-call
729 // safepoints (ncsfpt).
730 void check_safepts(VectorSet &visited, Node_List &stack);
731
732 // Allpaths backwards scan from loop tail, terminating each path at first safepoint
733 // encountered.
734 void allpaths_check_safepts(VectorSet &visited, Node_List &stack);
735
736 // Remove safepoints from loop. Optionally keeping one.
737 void remove_safepoints(PhaseIdealLoop* phase, bool keep_one);
738
739 // Convert to counted loops where possible
740 void counted_loop( PhaseIdealLoop *phase );
741
742 // Check for Node being a loop-breaking test
743 Node *is_loop_exit(Node *iff) const;
744
745 // Remove simplistic dead code from loop body
746 void DCE_loop_body();
747
748 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage.
749 // Replace with a 1-in-10 exit guess.
750 void adjust_loop_exit_prob( PhaseIdealLoop *phase );
751
752 // Return TRUE or FALSE if the loop should never be RCE'd or aligned.
753 // Useful for unrolling loops with NO array accesses.
754 bool policy_peel_only( PhaseIdealLoop *phase ) const;
755
756 // Return TRUE or FALSE if the loop should be unswitched -- clone
757 // loop with an invariant test
758 bool policy_unswitching( PhaseIdealLoop *phase ) const;
759 bool no_unswitch_candidate() const;
760
761 // Micro-benchmark spamming. Remove empty loops.
762 bool do_remove_empty_loop( PhaseIdealLoop *phase );
763
764 // Convert one-iteration loop into normal code.
765 bool do_one_iteration_loop( PhaseIdealLoop *phase );
766
767 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can
768 // move some loop-invariant test (usually a null-check) before the loop.
769 bool policy_peeling(PhaseIdealLoop *phase);
770
771 uint estimate_peeling(PhaseIdealLoop *phase);
772
773 // Return TRUE or FALSE if the loop should be maximally unrolled. Stash any
774 // known trip count in the counted loop node.
775 bool policy_maximally_unroll(PhaseIdealLoop *phase) const;
776
777 // Return TRUE or FALSE if the loop should be unrolled or not. Apply unroll
778 // if the loop is a counted loop and the loop body is small enough.
779 bool policy_unroll(PhaseIdealLoop *phase);
780
781 // Loop analyses to map to a maximal superword unrolling for vectorization.
782 void policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_ct);
783
784 // Return TRUE or FALSE if the loop should be range-check-eliminated.
785 // Gather a list of IF tests that are dominated by iteration splitting;
786 // also gather the end of the first split and the start of the 2nd split.
787 bool policy_range_check(PhaseIdealLoop* phase, bool provisional, BasicType bt) const;
788
789 // Return TRUE if "iff" is a range check.
790 bool is_range_check_if(IfProjNode* if_success_proj, PhaseIdealLoop* phase, Invariance& invar DEBUG_ONLY(COMMA ProjNode* predicate_proj)) const;
791 bool is_range_check_if(IfProjNode* if_success_proj, PhaseIdealLoop* phase, BasicType bt, Node* iv, Node*& range, Node*& offset,
792 jlong& scale) const;
793
794 // Estimate the number of nodes required when cloning a loop (body).
795 uint est_loop_clone_sz(uint factor) const;
796 // Estimate the number of nodes required when unrolling a loop (body).
797 uint est_loop_unroll_sz(uint factor) const;
798
799 // Compute loop trip count if possible
800 void compute_trip_count(PhaseIdealLoop* phase, BasicType bt);
801
802 // Compute loop trip count from profile data
803 float compute_profile_trip_cnt_helper(Node* n);
804 void compute_profile_trip_cnt( PhaseIdealLoop *phase );
805
806 // Reassociate invariant expressions.
807 void reassociate_invariants(PhaseIdealLoop *phase);
808 // Reassociate invariant binary expressions.
809 Node* reassociate(Node* n1, PhaseIdealLoop *phase);
810 // Reassociate invariant add, subtract, and compare expressions.
811 Node* reassociate_add_sub_cmp(Node* n1, int inv1_idx, int inv2_idx, PhaseIdealLoop* phase);
812 // Return nonzero index of invariant operand if invariant and variant
813 // are combined with an associative binary. Helper for reassociate_invariants.
814 int find_invariant(Node* n, PhaseIdealLoop *phase);
815 // Return TRUE if "n" is associative.
816 bool is_associative(Node* n, Node* base=nullptr);
817 // Return TRUE if "n" is an associative cmp node.
818 bool is_associative_cmp(Node* n);
819
820 // Return true if n is invariant
821 bool is_invariant(Node* n) const;
822
823 // Put loop body on igvn work list
824 void record_for_igvn();
825
826 bool is_root() { return _parent == nullptr; }
827 // A proper/reducible loop w/o any (occasional) dead back-edge.
828 bool is_loop() { return !_irreducible && !tail()->is_top(); }
829 bool is_counted() { return is_loop() && _head->is_CountedLoop(); }
830 bool is_innermost() { return is_loop() && _child == nullptr; }
831
832 void remove_main_post_loops(CountedLoopNode *cl, PhaseIdealLoop *phase);
833
834 bool compute_has_range_checks() const;
835 bool range_checks_present() {
836 if (!_has_range_checks_computed) {
837 if (compute_has_range_checks()) {
838 _has_range_checks = 1;
839 }
840 _has_range_checks_computed = 1;
841 }
842 return _has_range_checks;
843 }
844
845 // Return the parent's IdealLoopTree for a strip mined loop which is the outer strip mined loop.
846 // In all other cases, return this.
847 IdealLoopTree* skip_strip_mined() {
848 return _head->as_Loop()->is_strip_mined() ? _parent : this;
849 }
850
851 #ifndef PRODUCT
852 void dump_head(); // Dump loop head only
853 void dump(); // Dump this loop recursively
854 #endif
855
856 #ifdef ASSERT
857 GrowableArray<IdealLoopTree*> collect_sorted_children() const;
858 bool verify_tree(IdealLoopTree* loop_verify) const;
859 #endif
860
861 private:
862 enum { EMPTY_LOOP_SIZE = 7 }; // Number of nodes in an empty loop.
863
864 // Estimate the number of nodes resulting from control and data flow merge.
865 uint est_loop_flow_merge_sz() const;
866
867 // Check if the number of residual iterations is large with unroll_cnt.
868 // Return true if the residual iterations are more than 10% of the trip count.
869 bool is_residual_iters_large(int unroll_cnt, CountedLoopNode *cl) const {
870 return (unroll_cnt - 1) * (100.0 / LoopPercentProfileLimit) > cl->profile_trip_cnt();
871 }
872
873 void collect_loop_core_nodes(PhaseIdealLoop* phase, Unique_Node_List& wq) const;
874
875 bool empty_loop_with_data_nodes(PhaseIdealLoop* phase) const;
876
877 void enqueue_data_nodes(PhaseIdealLoop* phase, Unique_Node_List& empty_loop_nodes, Unique_Node_List& wq) const;
878
879 bool process_safepoint(PhaseIdealLoop* phase, Unique_Node_List& empty_loop_nodes, Unique_Node_List& wq,
880 Node* sfpt) const;
881
882 bool empty_loop_candidate(PhaseIdealLoop* phase) const;
883
884 bool empty_loop_with_extra_nodes_candidate(PhaseIdealLoop* phase) const;
885 };
886
887 // -----------------------------PhaseIdealLoop---------------------------------
888 // Computes the mapping from Nodes to IdealLoopTrees. Organizes IdealLoopTrees
889 // into a loop tree. Drives the loop-based transformations on the ideal graph.
890 class PhaseIdealLoop : public PhaseTransform {
891 friend class IdealLoopTree;
892 friend class SuperWord;
893 friend class ShenandoahBarrierC2Support;
894 friend class AutoNodeBudget;
895
896 // Map loop membership for CFG nodes, and ctrl for non-CFG nodes.
897 Node_List _loop_or_ctrl;
898
899 // Pre-computed def-use info
900 PhaseIterGVN &_igvn;
901
902 // Head of loop tree
903 IdealLoopTree* _ltree_root;
904
905 // Array of pre-order numbers, plus post-visited bit.
906 // ZERO for not pre-visited. EVEN for pre-visited but not post-visited.
907 // ODD for post-visited. Other bits are the pre-order number.
908 uint *_preorders;
909 uint _max_preorder;
910
911 ReallocMark _nesting; // Safety checks for arena reallocation
912
913 const PhaseIdealLoop* _verify_me;
914 bool _verify_only;
915
916 // Allocate _preorders[] array
917 void allocate_preorders() {
918 _max_preorder = C->unique()+8;
919 _preorders = NEW_RESOURCE_ARRAY(uint, _max_preorder);
920 memset(_preorders, 0, sizeof(uint) * _max_preorder);
921 }
922
923 // Allocate _preorders[] array
924 void reallocate_preorders() {
925 _nesting.check(); // Check if a potential re-allocation in the resource arena is safe
926 if ( _max_preorder < C->unique() ) {
927 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique());
928 _max_preorder = C->unique();
929 }
930 memset(_preorders, 0, sizeof(uint) * _max_preorder);
931 }
932
933 // Check to grow _preorders[] array for the case when build_loop_tree_impl()
934 // adds new nodes.
935 void check_grow_preorders( ) {
936 _nesting.check(); // Check if a potential re-allocation in the resource arena is safe
937 if ( _max_preorder < C->unique() ) {
938 uint newsize = _max_preorder<<1; // double size of array
939 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize);
940 memset(&_preorders[_max_preorder],0,sizeof(uint)*(newsize-_max_preorder));
941 _max_preorder = newsize;
942 }
943 }
944 // Check for pre-visited. Zero for NOT visited; non-zero for visited.
945 int is_visited( Node *n ) const { return _preorders[n->_idx]; }
946 // Pre-order numbers are written to the Nodes array as low-bit-set values.
947 void set_preorder_visited( Node *n, int pre_order ) {
948 assert( !is_visited( n ), "already set" );
949 _preorders[n->_idx] = (pre_order<<1);
950 };
951 // Return pre-order number.
952 int get_preorder( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]>>1; }
953
954 // Check for being post-visited.
955 // Should be previsited already (checked with assert(is_visited(n))).
956 int is_postvisited( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]&1; }
957
958 // Mark as post visited
959 void set_postvisited( Node *n ) { assert( !is_postvisited( n ), "" ); _preorders[n->_idx] |= 1; }
960
961 public:
962 // Set/get control node out. Set lower bit to distinguish from IdealLoopTree
963 // Returns true if "n" is a data node, false if it's a control node.
964 bool has_ctrl(const Node* n) const { return ((intptr_t)_loop_or_ctrl[n->_idx]) & 1; }
965
966 private:
967 // clear out dead code after build_loop_late
968 Node_List _deadlist;
969 Node_List _zero_trip_guard_opaque_nodes;
970 Node_List _multiversion_opaque_nodes;
971
972 // Support for faster execution of get_late_ctrl()/dom_lca()
973 // when a node has many uses and dominator depth is deep.
974 GrowableArray<jlong> _dom_lca_tags;
975 uint _dom_lca_tags_round;
976 void init_dom_lca_tags();
977
978 // Helper for debugging bad dominance relationships
979 bool verify_dominance(Node* n, Node* use, Node* LCA, Node* early);
980
981 Node* compute_lca_of_uses(Node* n, Node* early, bool verify = false);
982
983 // Inline wrapper for frequent cases:
984 // 1) only one use
985 // 2) a use is the same as the current LCA passed as 'n1'
986 Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) {
987 assert( n->is_CFG(), "" );
988 // Fast-path null lca
989 if( lca != nullptr && lca != n ) {
990 assert( lca->is_CFG(), "" );
991 // find LCA of all uses
992 n = dom_lca_for_get_late_ctrl_internal( lca, n, tag );
993 }
994 return find_non_split_ctrl(n);
995 }
996 Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag );
997
998 // Helper function for directing control inputs away from CFG split points.
999 Node *find_non_split_ctrl( Node *ctrl ) const {
1000 if (ctrl != nullptr) {
1001 if (ctrl->is_MultiBranch()) {
1002 ctrl = ctrl->in(0);
1003 }
1004 assert(ctrl->is_CFG(), "CFG");
1005 }
1006 return ctrl;
1007 }
1008
1009 void cast_incr_before_loop(Node* incr, Node* ctrl, CountedLoopNode* loop);
1010
1011 #ifdef ASSERT
1012 static void ensure_zero_trip_guard_proj(Node* node, bool is_main_loop);
1013 #endif
1014 private:
1015 static void get_opaque_template_assertion_predicate_nodes(ParsePredicateSuccessProj* parse_predicate_proj,
1016 Unique_Node_List& list);
1017 void update_main_loop_assertion_predicates(CountedLoopNode* new_main_loop_head, int stride_con_before_unroll);
1018 void initialize_assertion_predicates_for_peeled_loop(CountedLoopNode* peeled_loop_head,
1019 CountedLoopNode* remaining_loop_head,
1020 uint first_node_index_in_cloned_loop_body,
1021 const Node_List& old_new);
1022 void initialize_assertion_predicates_for_main_loop(CountedLoopNode* pre_loop_head,
1023 CountedLoopNode* main_loop_head,
1024 uint first_node_index_in_pre_loop_body,
1025 uint last_node_index_in_pre_loop_body,
1026 DEBUG_ONLY(uint last_node_index_from_backedge_goo COMMA)
1027 const Node_List& old_new);
1028 void initialize_assertion_predicates_for_post_loop(CountedLoopNode* main_loop_head, CountedLoopNode* post_loop_head,
1029 uint first_node_index_in_cloned_loop_body);
1030 void create_assertion_predicates_at_loop(CountedLoopNode* source_loop_head, CountedLoopNode* target_loop_head,
1031 const NodeInLoopBody& _node_in_loop_body, bool kill_old_template);
1032 void create_assertion_predicates_at_main_or_post_loop(CountedLoopNode* source_loop_head,
1033 CountedLoopNode* target_loop_head,
1034 const NodeInLoopBody& _node_in_loop_body,
1035 bool kill_old_template);
1036 void rewire_old_target_loop_entry_dependency_to_new_entry(CountedLoopNode* target_loop_head,
1037 const Node* old_target_loop_entry,
1038 uint node_index_before_new_assertion_predicate_nodes);
1039 void insert_loop_limit_check_predicate(ParsePredicateSuccessProj* loop_limit_check_parse_proj, Node* cmp_limit,
1040 Node* bol);
1041 void log_loop_tree();
1042
1043 public:
1044
1045 PhaseIterGVN &igvn() const { return _igvn; }
1046
1047 bool has_node(const Node* n) const {
1048 guarantee(n != nullptr, "No Node.");
1049 return _loop_or_ctrl[n->_idx] != nullptr;
1050 }
1051 // check if transform created new nodes that need _ctrl recorded
1052 Node *get_late_ctrl( Node *n, Node *early );
1053 Node *get_early_ctrl( Node *n );
1054 Node *get_early_ctrl_for_expensive(Node *n, Node* earliest);
1055 void set_early_ctrl(Node* n, bool update_body);
1056 void set_subtree_ctrl(Node* n, bool update_body);
1057 void set_ctrl( Node *n, Node *ctrl ) {
1058 assert( !has_node(n) || has_ctrl(n), "" );
1059 assert( ctrl->in(0), "cannot set dead control node" );
1060 assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" );
1061 _loop_or_ctrl.map(n->_idx, (Node*)((intptr_t)ctrl + 1));
1062 }
1063 void set_root_as_ctrl(Node* n) {
1064 assert(!has_node(n) || has_ctrl(n), "");
1065 _loop_or_ctrl.map(n->_idx, (Node*)((intptr_t)C->root() + 1));
1066 }
1067 // Set control and update loop membership
1068 void set_ctrl_and_loop(Node* n, Node* ctrl) {
1069 IdealLoopTree* old_loop = get_loop(get_ctrl(n));
1070 IdealLoopTree* new_loop = get_loop(ctrl);
1071 if (old_loop != new_loop) {
1072 if (old_loop->_child == nullptr) old_loop->_body.yank(n);
1073 if (new_loop->_child == nullptr) new_loop->_body.push(n);
1074 }
1075 set_ctrl(n, ctrl);
1076 }
1077 // Control nodes can be replaced or subsumed. During this pass they
1078 // get their replacement Node in slot 1. Instead of updating the block
1079 // location of all Nodes in the subsumed block, we lazily do it. As we
1080 // pull such a subsumed block out of the array, we write back the final
1081 // correct block.
1082 Node* get_ctrl(const Node* i) {
1083 assert(has_node(i), "");
1084 Node *n = get_ctrl_no_update(i);
1085 _loop_or_ctrl.map(i->_idx, (Node*)((intptr_t)n + 1));
1086 assert(has_node(i) && has_ctrl(i), "");
1087 assert(n == find_non_split_ctrl(n), "must return legal ctrl" );
1088 return n;
1089 }
1090
1091 bool is_dominator(Node* dominator, Node* n);
1092 bool is_strict_dominator(Node* dominator, Node* n);
1093
1094 // return get_ctrl for a data node and self(n) for a CFG node
1095 Node* ctrl_or_self(Node* n) {
1096 if (has_ctrl(n))
1097 return get_ctrl(n);
1098 else {
1099 assert (n->is_CFG(), "must be a CFG node");
1100 return n;
1101 }
1102 }
1103
1104 Node* get_ctrl_no_update_helper(const Node* i) const {
1105 assert(has_ctrl(i), "should be control, not loop");
1106 return (Node*)(((intptr_t)_loop_or_ctrl[i->_idx]) & ~1);
1107 }
1108
1109 Node* get_ctrl_no_update(const Node* i) const {
1110 assert( has_ctrl(i), "" );
1111 Node *n = get_ctrl_no_update_helper(i);
1112 if (!n->in(0)) {
1113 // Skip dead CFG nodes
1114 do {
1115 n = get_ctrl_no_update_helper(n);
1116 } while (!n->in(0));
1117 n = find_non_split_ctrl(n);
1118 }
1119 return n;
1120 }
1121
1122 // Check for loop being set
1123 // "n" must be a control node. Returns true if "n" is known to be in a loop.
1124 bool has_loop( Node *n ) const {
1125 assert(!has_node(n) || !has_ctrl(n), "");
1126 return has_node(n);
1127 }
1128 // Set loop
1129 void set_loop( Node *n, IdealLoopTree *loop ) {
1130 _loop_or_ctrl.map(n->_idx, (Node*)loop);
1131 }
1132 // Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms. Replace
1133 // the 'old_node' with 'new_node'. Kill old-node. Add a reference
1134 // from old_node to new_node to support the lazy update. Reference
1135 // replaces loop reference, since that is not needed for dead node.
1136 void lazy_update(Node *old_node, Node *new_node) {
1137 assert(old_node != new_node, "no cycles please");
1138 // Re-use the side array slot for this node to provide the
1139 // forwarding pointer.
1140 _loop_or_ctrl.map(old_node->_idx, (Node*)((intptr_t)new_node + 1));
1141 }
1142 void lazy_replace(Node *old_node, Node *new_node) {
1143 _igvn.replace_node(old_node, new_node);
1144 lazy_update(old_node, new_node);
1145 }
1146
1147 private:
1148
1149 // Place 'n' in some loop nest, where 'n' is a CFG node
1150 void build_loop_tree();
1151 int build_loop_tree_impl(Node* n, int pre_order);
1152 // Insert loop into the existing loop tree. 'innermost' is a leaf of the
1153 // loop tree, not the root.
1154 IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost );
1155
1156 #ifdef ASSERT
1157 // verify that regions in irreducible loops are marked is_in_irreducible_loop
1158 void verify_regions_in_irreducible_loops();
1159 bool is_in_irreducible_loop(RegionNode* region);
1160 #endif
1161
1162 // Place Data nodes in some loop nest
1163 void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
1164 void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
1165 void build_loop_late_post_work(Node* n, bool pinned);
1166 void build_loop_late_post(Node* n);
1167 void verify_strip_mined_scheduling(Node *n, Node* least);
1168
1169 // Array of immediate dominance info for each CFG node indexed by node idx
1170 private:
1171 uint _idom_size;
1172 Node **_idom; // Array of immediate dominators
1173 uint *_dom_depth; // Used for fast LCA test
1174 GrowableArray<uint>* _dom_stk; // For recomputation of dom depth
1175 LoopOptsMode _mode;
1176
1177 // build the loop tree and perform any requested optimizations
1178 void build_and_optimize();
1179
1180 // Dominators for the sea of nodes
1181 void Dominators();
1182
1183 // Compute the Ideal Node to Loop mapping
1184 PhaseIdealLoop(PhaseIterGVN& igvn, LoopOptsMode mode) :
1185 PhaseTransform(Ideal_Loop),
1186 _loop_or_ctrl(igvn.C->comp_arena()),
1187 _igvn(igvn),
1188 _verify_me(nullptr),
1189 _verify_only(false),
1190 _mode(mode),
1191 _nodes_required(UINT_MAX) {
1192 assert(mode != LoopOptsVerify, "wrong constructor to verify IdealLoop");
1193 build_and_optimize();
1194 }
1195
1196 #ifndef PRODUCT
1197 // Verify that verify_me made the same decisions as a fresh run
1198 // or only verify that the graph is valid if verify_me is null.
1199 PhaseIdealLoop(PhaseIterGVN& igvn, const PhaseIdealLoop* verify_me = nullptr) :
1200 PhaseTransform(Ideal_Loop),
1201 _loop_or_ctrl(igvn.C->comp_arena()),
1202 _igvn(igvn),
1203 _verify_me(verify_me),
1204 _verify_only(verify_me == nullptr),
1205 _mode(LoopOptsVerify),
1206 _nodes_required(UINT_MAX) {
1207 DEBUG_ONLY(C->set_phase_verify_ideal_loop();)
1208 build_and_optimize();
1209 DEBUG_ONLY(C->reset_phase_verify_ideal_loop();)
1210 }
1211 #endif
1212
1213 Node* insert_convert_node_if_needed(BasicType target, Node* input);
1214
1215 public:
1216 Node* idom_no_update(Node* d) const {
1217 return idom_no_update(d->_idx);
1218 }
1219
1220 Node* idom_no_update(uint didx) const {
1221 assert(didx < _idom_size, "oob");
1222 Node* n = _idom[didx];
1223 assert(n != nullptr,"Bad immediate dominator info.");
1224 while (n->in(0) == nullptr) { // Skip dead CFG nodes
1225 n = (Node*)(((intptr_t)_loop_or_ctrl[n->_idx]) & ~1);
1226 assert(n != nullptr,"Bad immediate dominator info.");
1227 }
1228 return n;
1229 }
1230
1231 Node *idom(Node* d) const {
1232 return idom(d->_idx);
1233 }
1234
1235 Node *idom(uint didx) const {
1236 Node *n = idom_no_update(didx);
1237 _idom[didx] = n; // Lazily remove dead CFG nodes from table.
1238 return n;
1239 }
1240
1241 uint dom_depth(Node* d) const {
1242 guarantee(d != nullptr, "Null dominator info.");
1243 guarantee(d->_idx < _idom_size, "");
1244 return _dom_depth[d->_idx];
1245 }
1246 void set_idom(Node* d, Node* n, uint dom_depth);
1247 // Locally compute IDOM using dom_lca call
1248 Node *compute_idom( Node *region ) const;
1249 // Recompute dom_depth
1250 void recompute_dom_depth();
1251
1252 // Is safept not required by an outer loop?
1253 bool is_deleteable_safept(Node* sfpt);
1254
1255 // Replace parallel induction variable (parallel to trip counter)
1256 void replace_parallel_iv(IdealLoopTree *loop);
1257
1258 Node *dom_lca( Node *n1, Node *n2 ) const {
1259 return find_non_split_ctrl(dom_lca_internal(n1, n2));
1260 }
1261 Node *dom_lca_internal( Node *n1, Node *n2 ) const;
1262
1263 Node* dominated_node(Node* c1, Node* c2) {
1264 assert(is_dominator(c1, c2) || is_dominator(c2, c1), "nodes must be related");
1265 return is_dominator(c1, c2) ? c2 : c1;
1266 }
1267
1268 // Return control node that's dominated by the 2 others
1269 Node* dominated_node(Node* c1, Node* c2, Node* c3) {
1270 return dominated_node(c1, dominated_node(c2, c3));
1271 }
1272
1273 // Build and verify the loop tree without modifying the graph. This
1274 // is useful to verify that all inputs properly dominate their uses.
1275 static void verify(PhaseIterGVN& igvn) {
1276 #ifdef ASSERT
1277 ResourceMark rm;
1278 Compile::TracePhase tp(_t_idealLoopVerify);
1279 PhaseIdealLoop v(igvn);
1280 #endif
1281 }
1282
1283 // Recommended way to use PhaseIdealLoop.
1284 // Run PhaseIdealLoop in some mode and allocates a local scope for memory allocations.
1285 static void optimize(PhaseIterGVN &igvn, LoopOptsMode mode) {
1286 ResourceMark rm;
1287 PhaseIdealLoop v(igvn, mode);
1288
1289 Compile* C = Compile::current();
1290 if (!C->failing()) {
1291 // Cleanup any modified bits
1292 igvn.optimize();
1293 if (C->failing()) { return; }
1294 v.log_loop_tree();
1295 }
1296 }
1297
1298 // True if the method has at least 1 irreducible loop
1299 bool _has_irreducible_loops;
1300
1301 // Per-Node transform
1302 virtual Node* transform(Node* n) { return nullptr; }
1303
1304 Node* loop_exit_control(Node* x, IdealLoopTree* loop);
1305 Node* loop_exit_test(Node* back_control, IdealLoopTree* loop, Node*& incr, Node*& limit, BoolTest::mask& bt, float& cl_prob);
1306 Node* loop_iv_incr(Node* incr, Node* x, IdealLoopTree* loop, Node*& phi_incr);
1307 Node* loop_iv_stride(Node* incr, Node*& xphi);
1308 PhiNode* loop_iv_phi(Node* xphi, Node* phi_incr, Node* x);
1309
1310 bool is_counted_loop(Node* x, IdealLoopTree*&loop, BasicType iv_bt);
1311
1312 Node* loop_nest_replace_iv(Node* iv_to_replace, Node* inner_iv, Node* outer_phi, Node* inner_head, BasicType bt);
1313 bool create_loop_nest(IdealLoopTree* loop, Node_List &old_new);
1314 #ifdef ASSERT
1315 bool convert_to_long_loop(Node* cmp, Node* phi, IdealLoopTree* loop);
1316 #endif
1317 void add_parse_predicate(Deoptimization::DeoptReason reason, Node* inner_head, IdealLoopTree* loop, SafePointNode* sfpt);
1318 SafePointNode* find_safepoint(Node* back_control, Node* x, IdealLoopTree* loop);
1319 IdealLoopTree* insert_outer_loop(IdealLoopTree* loop, LoopNode* outer_l, Node* outer_ift);
1320 IdealLoopTree* create_outer_strip_mined_loop(Node* init_control,
1321 IdealLoopTree* loop, float cl_prob, float le_fcnt,
1322 Node*& entry_control, Node*& iffalse);
1323
1324 Node* exact_limit( IdealLoopTree *loop );
1325
1326 // Return a post-walked LoopNode
1327 IdealLoopTree *get_loop( Node *n ) const {
1328 // Dead nodes have no loop, so return the top level loop instead
1329 if (!has_node(n)) return _ltree_root;
1330 assert(!has_ctrl(n), "");
1331 return (IdealLoopTree*)_loop_or_ctrl[n->_idx];
1332 }
1333
1334 IdealLoopTree* ltree_root() const { return _ltree_root; }
1335
1336 // Is 'n' a (nested) member of 'loop'?
1337 int is_member( const IdealLoopTree *loop, Node *n ) const {
1338 return loop->is_member(get_loop(n)); }
1339
1340 // This is the basic building block of the loop optimizations. It clones an
1341 // entire loop body. It makes an old_new loop body mapping; with this
1342 // mapping you can find the new-loop equivalent to an old-loop node. All
1343 // new-loop nodes are exactly equal to their old-loop counterparts, all
1344 // edges are the same. All exits from the old-loop now have a RegionNode
1345 // that merges the equivalent new-loop path. This is true even for the
1346 // normal "loop-exit" condition. All uses of loop-invariant old-loop values
1347 // now come from (one or more) Phis that merge their new-loop equivalents.
1348 // Parameter side_by_side_idom:
1349 // When side_by_size_idom is null, the dominator tree is constructed for
1350 // the clone loop to dominate the original. Used in construction of
1351 // pre-main-post loop sequence.
1352 // When nonnull, the clone and original are side-by-side, both are
1353 // dominated by the passed in side_by_side_idom node. Used in
1354 // construction of unswitched loops.
1355 enum CloneLoopMode {
1356 IgnoreStripMined = 0, // Only clone inner strip mined loop
1357 CloneIncludesStripMined = 1, // clone both inner and outer strip mined loops
1358 ControlAroundStripMined = 2 // Only clone inner strip mined loop,
1359 // result control flow branches
1360 // either to inner clone or outer
1361 // strip mined loop.
1362 };
1363 void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth,
1364 CloneLoopMode mode, Node* side_by_side_idom = nullptr);
1365 void clone_loop_handle_data_uses(Node* old, Node_List &old_new,
1366 IdealLoopTree* loop, IdealLoopTree* companion_loop,
1367 Node_List*& split_if_set, Node_List*& split_bool_set,
1368 Node_List*& split_cex_set, Node_List& worklist,
1369 uint new_counter, CloneLoopMode mode);
1370 void clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
1371 IdealLoopTree* outer_loop, int dd, Node_List &old_new,
1372 Node_List& extra_data_nodes);
1373
1374 // If we got the effect of peeling, either by actually peeling or by
1375 // making a pre-loop which must execute at least once, we can remove
1376 // all loop-invariant dominated tests in the main body.
1377 void peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new );
1378
1379 // Generate code to do a loop peel for the given loop (and body).
1380 // old_new is a temp array.
1381 void do_peeling( IdealLoopTree *loop, Node_List &old_new );
1382
1383 // Add pre and post loops around the given loop. These loops are used
1384 // during RCE, unrolling and aligning loops.
1385 void insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only );
1386
1387 // Add post loop after the given loop.
1388 Node *insert_post_loop(IdealLoopTree* loop, Node_List& old_new,
1389 CountedLoopNode* main_head, CountedLoopEndNode* main_end,
1390 Node* incr, Node* limit, CountedLoopNode*& post_head);
1391
1392 // Add a vector post loop between a vector main loop and the current post loop
1393 void insert_vector_post_loop(IdealLoopTree *loop, Node_List &old_new);
1394 // If Node n lives in the back_ctrl block, we clone a private version of n
1395 // in preheader_ctrl block and return that, otherwise return n.
1396 Node *clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones );
1397
1398 // Take steps to maximally unroll the loop. Peel any odd iterations, then
1399 // unroll to do double iterations. The next round of major loop transforms
1400 // will repeat till the doubled loop body does all remaining iterations in 1
1401 // pass.
1402 void do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new );
1403
1404 // Unroll the loop body one step - make each trip do 2 iterations.
1405 void do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip );
1406
1407 // Return true if exp is a constant times an induction var
1408 bool is_scaled_iv(Node* exp, Node* iv, BasicType bt, jlong* p_scale, bool* p_short_scale, int depth = 0);
1409
1410 bool is_iv(Node* exp, Node* iv, BasicType bt);
1411
1412 // Return true if exp is a scaled induction var plus (or minus) constant
1413 bool is_scaled_iv_plus_offset(Node* exp, Node* iv, BasicType bt, jlong* p_scale, Node** p_offset, bool* p_short_scale = nullptr, int depth = 0);
1414 bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset) {
1415 jlong long_scale;
1416 if (is_scaled_iv_plus_offset(exp, iv, T_INT, &long_scale, p_offset)) {
1417 int int_scale = checked_cast<int>(long_scale);
1418 if (p_scale != nullptr) {
1419 *p_scale = int_scale;
1420 }
1421 return true;
1422 }
1423 return false;
1424 }
1425 // Helper for finding more complex matches to is_scaled_iv_plus_offset.
1426 bool is_scaled_iv_plus_extra_offset(Node* exp1, Node* offset2, Node* iv,
1427 BasicType bt,
1428 jlong* p_scale, Node** p_offset,
1429 bool* p_short_scale, int depth);
1430
1431 // Create a new if above the uncommon_trap_if_pattern for the predicate to be promoted
1432 IfTrueNode* create_new_if_for_predicate(const ParsePredicateSuccessProj* parse_predicate_proj, Node* new_entry,
1433 Deoptimization::DeoptReason reason, int opcode,
1434 bool rewire_uncommon_proj_phi_inputs = false);
1435
1436 private:
1437 // Helper functions for create_new_if_for_predicate()
1438 void set_ctrl_of_nodes_with_same_ctrl(Node* start_node, ProjNode* old_uncommon_proj, Node* new_uncommon_proj);
1439 Unique_Node_List find_nodes_with_same_ctrl(Node* node, const ProjNode* ctrl);
1440 Node* clone_nodes_with_same_ctrl(Node* start_node, ProjNode* old_uncommon_proj, Node* new_uncommon_proj);
1441 void fix_cloned_data_node_controls(const ProjNode* orig, Node* new_uncommon_proj,
1442 const OrigToNewHashtable& orig_to_clone);
1443 bool has_dominating_loop_limit_check(Node* init_trip, Node* limit, jlong stride_con, BasicType iv_bt,
1444 Node* loop_entry);
1445
1446 public:
1447 void register_control(Node* n, IdealLoopTree *loop, Node* pred, bool update_body = true);
1448
1449 // Replace the control input of 'node' with 'new_control' and set the dom depth to the one of 'new_control'.
1450 void replace_control(Node* node, Node* new_control) {
1451 _igvn.replace_input_of(node, 0, new_control);
1452 set_idom(node, new_control, dom_depth(new_control));
1453 }
1454
1455 void replace_loop_entry(LoopNode* loop_head, Node* new_entry) {
1456 _igvn.replace_input_of(loop_head, LoopNode::EntryControl, new_entry);
1457 set_idom(loop_head, new_entry, dom_depth(new_entry));
1458 }
1459
1460 // Construct a range check for a predicate if
1461 BoolNode* rc_predicate(Node* ctrl, int scale, Node* offset, Node* init, Node* limit,
1462 jint stride, Node* range, bool upper, bool& overflow);
1463
1464 // Implementation of the loop predication to promote checks outside the loop
1465 bool loop_predication_impl(IdealLoopTree *loop);
1466
1467 private:
1468 bool loop_predication_impl_helper(IdealLoopTree* loop, IfProjNode* if_success_proj,
1469 ParsePredicateSuccessProj* parse_predicate_proj, CountedLoopNode* cl, ConNode* zero,
1470 Invariance& invar, Deoptimization::DeoptReason deopt_reason);
1471 bool can_create_loop_predicates(const PredicateBlock* profiled_loop_predicate_block) const;
1472 bool loop_predication_should_follow_branches(IdealLoopTree* loop, float& loop_trip_cnt);
1473 void loop_predication_follow_branches(Node *c, IdealLoopTree *loop, float loop_trip_cnt,
1474 PathFrequency& pf, Node_Stack& stack, VectorSet& seen,
1475 Node_List& if_proj_list);
1476 IfTrueNode* create_template_assertion_predicate(CountedLoopNode* loop_head, ParsePredicateNode* parse_predicate,
1477 IfProjNode* new_control, int scale, Node* offset, Node* range);
1478 void eliminate_hoisted_range_check(IfTrueNode* hoisted_check_proj, IfTrueNode* template_assertion_predicate_proj);
1479
1480 // Helper function to collect predicate for eliminating the useless ones
1481 void eliminate_useless_predicates() const;
1482
1483 void eliminate_useless_zero_trip_guard();
1484 void eliminate_useless_multiversion_if();
1485
1486 public:
1487 // Change the control input of expensive nodes to allow commoning by
1488 // IGVN when it is guaranteed to not result in a more frequent
1489 // execution of the expensive node. Return true if progress.
1490 bool process_expensive_nodes();
1491
1492 // Check whether node has become unreachable
1493 bool is_node_unreachable(Node *n) const {
1494 return !has_node(n) || n->is_unreachable(_igvn);
1495 }
1496
1497 // Eliminate range-checks and other trip-counter vs loop-invariant tests.
1498 void do_range_check(IdealLoopTree* loop);
1499
1500 // Clone loop with an invariant test (that does not exit) and
1501 // insert a clone of the test that selects which version to
1502 // execute.
1503 void do_unswitching(IdealLoopTree* loop, Node_List& old_new);
1504
1505 IfNode* find_unswitch_candidates(const IdealLoopTree* loop, Node_List& flat_array_checks) const;
1506 IfNode* find_unswitch_candidate_from_idoms(const IdealLoopTree* loop) const;
1507
1508 private:
1509 static bool has_control_dependencies_from_predicates(LoopNode* head);
1510 static void revert_to_normal_loop(const LoopNode* loop_head);
1511
1512 void hoist_invariant_check_casts(const IdealLoopTree* loop, const Node_List& old_new,
1513 const UnswitchCandidate& unswitch_candidate, const IfNode* loop_selector);
1514 void add_unswitched_loop_version_bodies_to_igvn(IdealLoopTree* loop, const Node_List& old_new);
1515 static void increment_unswitch_counts(LoopNode* original_head, LoopNode* new_head);
1516 void remove_unswitch_candidate_from_loops(const Node_List& old_new, const UnswitchedLoopSelector& unswitched_loop_selector);
1517 #ifndef PRODUCT
1518 static void trace_loop_unswitching_count(IdealLoopTree* loop, LoopNode* original_head);
1519 static void trace_loop_unswitching_impossible(const LoopNode* original_head);
1520 static void trace_loop_unswitching_result(const UnswitchedLoopSelector& unswitched_loop_selector,
1521 const UnswitchCandidate& unswitch_candidate,
1522 const LoopNode* original_head, const LoopNode* new_head);
1523 static void trace_loop_multiversioning_result(const LoopSelector& loop_selector,
1524 const LoopNode* original_head, const LoopNode* new_head);
1525 #endif
1526
1527 public:
1528
1529 // Range Check Elimination uses this function!
1530 // Constrain the main loop iterations so the affine function:
1531 // low_limit <= scale_con * I + offset < upper_limit
1532 // always holds true. That is, either increase the number of iterations in
1533 // the pre-loop or the post-loop until the condition holds true in the main
1534 // loop. Scale_con, offset and limit are all loop invariant.
1535 void add_constraint(jlong stride_con, jlong scale_con, Node* offset, Node* low_limit, Node* upper_limit, Node* pre_ctrl, Node** pre_limit, Node** main_limit);
1536 // Helper function for add_constraint().
1537 Node* adjust_limit(bool reduce, Node* scale, Node* offset, Node* rc_limit, Node* old_limit, Node* pre_ctrl, bool round);
1538
1539 // Partially peel loop up through last_peel node.
1540 bool partial_peel( IdealLoopTree *loop, Node_List &old_new );
1541 bool duplicate_loop_backedge(IdealLoopTree *loop, Node_List &old_new);
1542
1543 // AutoVectorize the loop: replace scalar ops with vector ops.
1544 enum AutoVectorizeStatus {
1545 Impossible, // This loop has the wrong shape to even try vectorization.
1546 Success, // We just successfully vectorized the loop.
1547 TriedAndFailed, // We tried to vectorize, but failed.
1548 };
1549 AutoVectorizeStatus auto_vectorize(IdealLoopTree* lpt, VSharedData &vshared);
1550
1551 void maybe_multiversion_for_auto_vectorization_runtime_checks(IdealLoopTree* lpt, Node_List& old_new);
1552 void do_multiversioning(IdealLoopTree* lpt, Node_List& old_new);
1553 IfTrueNode* create_new_if_for_multiversion(IfTrueNode* multiversioning_fast_proj);
1554 bool try_resume_optimizations_for_delayed_slow_loop(IdealLoopTree* lpt);
1555
1556 // Move an unordered Reduction out of loop if possible
1557 void move_unordered_reduction_out_of_loop(IdealLoopTree* loop);
1558
1559 // Create a scheduled list of nodes control dependent on ctrl set.
1560 void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched );
1561 // Has a use in the vector set
1562 bool has_use_in_set( Node* n, VectorSet& vset );
1563 // Has use internal to the vector set (ie. not in a phi at the loop head)
1564 bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop );
1565 // clone "n" for uses that are outside of loop
1566 int clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist );
1567 // clone "n" for special uses that are in the not_peeled region
1568 void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
1569 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist );
1570 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
1571 void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp );
1572 #ifdef ASSERT
1573 // Validate the loop partition sets: peel and not_peel
1574 bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel );
1575 // Ensure that uses outside of loop are of the right form
1576 bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
1577 uint orig_exit_idx, uint clone_exit_idx);
1578 bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx);
1579 #endif
1580
1581 // Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.)
1582 int stride_of_possible_iv( Node* iff );
1583 bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; }
1584 // Return the (unique) control output node that's in the loop (if it exists.)
1585 Node* stay_in_loop( Node* n, IdealLoopTree *loop);
1586 // Insert a signed compare loop exit cloned from an unsigned compare.
1587 IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop);
1588 void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop);
1589 // Utility to register node "n" with PhaseIdealLoop
1590 void register_node(Node* n, IdealLoopTree* loop, Node* pred, uint ddepth);
1591 // Utility to create an if-projection
1592 ProjNode* proj_clone(ProjNode* p, IfNode* iff);
1593 // Force the iff control output to be the live_proj
1594 Node* short_circuit_if(IfNode* iff, ProjNode* live_proj);
1595 // Insert a region before an if projection
1596 RegionNode* insert_region_before_proj(ProjNode* proj);
1597 // Insert a new if before an if projection
1598 ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj);
1599
1600 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1601 // "Nearly" because all Nodes have been cloned from the original in the loop,
1602 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1603 // through the Phi recursively, and return a Bool.
1604 Node* clone_iff(PhiNode* phi);
1605 CmpNode* clone_bool(PhiNode* phi);
1606
1607
1608 // Rework addressing expressions to get the most loop-invariant stuff
1609 // moved out. We'd like to do all associative operators, but it's especially
1610 // important (common) to do address expressions.
1611 Node* remix_address_expressions(Node* n);
1612 Node* remix_address_expressions_add_left_shift(Node* n, IdealLoopTree* n_loop, Node* n_ctrl, BasicType bt);
1613
1614 // Convert add to muladd to generate MuladdS2I under certain criteria
1615 Node * convert_add_to_muladd(Node * n);
1616
1617 // Attempt to use a conditional move instead of a phi/branch
1618 Node *conditional_move( Node *n );
1619
1620 // Check for aggressive application of 'split-if' optimization,
1621 // using basic block level info.
1622 void split_if_with_blocks ( VectorSet &visited, Node_Stack &nstack);
1623 Node *split_if_with_blocks_pre ( Node *n );
1624 void split_if_with_blocks_post( Node *n );
1625 Node *has_local_phi_input( Node *n );
1626 // Mark an IfNode as being dominated by a prior test,
1627 // without actually altering the CFG (and hence IDOM info).
1628 void dominated_by(IfProjNode* prevdom, IfNode* iff, bool flip = false, bool pin_array_access_nodes = false);
1629 void rewire_safe_outputs_to_dominator(Node* source, Node* dominator, bool pin_array_access_nodes);
1630
1631 // Split Node 'n' through merge point
1632 RegionNode* split_thru_region(Node* n, RegionNode* region);
1633 // Split Node 'n' through merge point if there is enough win.
1634 Node *split_thru_phi( Node *n, Node *region, int policy );
1635 // Found an If getting its condition-code input from a Phi in the
1636 // same block. Split thru the Region.
1637 void do_split_if(Node *iff, RegionNode** new_false_region = nullptr, RegionNode** new_true_region = nullptr);
1638
1639 private:
1640 // Class to keep track of wins in split_thru_phi.
1641 class SplitThruPhiWins {
1642 private:
1643 // Region containing the phi we are splitting through.
1644 const Node* _region;
1645
1646 // Sum of all wins regardless of where they happen. This applies to Loops phis as well as non-loop phis.
1647 int _total_wins;
1648
1649 // For Loops, wins have different impact depending on if they happen on loop entry or on the backedge.
1650 // Number of wins on a loop entry edge if the split is through a loop head,
1651 // otherwise 0. Entry edge wins only pay dividends once on loop entry.
1652 int _loop_entry_wins;
1653 // Number of wins on a loop back-edge, which pay dividends on every iteration.
1654 int _loop_back_wins;
1655
1656 public:
1657 SplitThruPhiWins(const Node* region) :
1658 _region(region),
1659 _total_wins(0),
1660 _loop_entry_wins(0),
1661 _loop_back_wins(0) {};
1662
1663 void reset() {_total_wins = 0; _loop_entry_wins = 0; _loop_back_wins = 0;}
1664 void add_win(int ctrl_index) {
1665 if (_region->is_Loop() && ctrl_index == LoopNode::EntryControl) {
1666 _loop_entry_wins++;
1667 } else if (_region->is_Loop() && ctrl_index == LoopNode::LoopBackControl) {
1668 _loop_back_wins++;
1669 }
1670 _total_wins++;
1671 }
1672 // Is this split profitable with respect to the policy?
1673 bool profitable(int policy) const {
1674 assert(_region->is_Loop() || (_loop_entry_wins == 0 && _loop_back_wins == 0), "wins on loop edges without a loop");
1675 assert(!_region->is_Loop() || _total_wins == _loop_entry_wins + _loop_back_wins, "missed some win");
1676 // In general this means that the split has to have more wins than specified
1677 // in the policy. However, for loops we need to take into account where the
1678 // wins happen. We need to be careful when splitting, because splitting nodes
1679 // related to the iv through the phi can sufficiently rearrange the loop
1680 // structure to prevent RCE and thus vectorization. Thus, we only deem splitting
1681 // profitable if the win of a split is not on the entry edge, as such wins
1682 // only pay off once and have a high chance of messing up the loop structure.
1683 return (_loop_entry_wins == 0 && _total_wins > policy) ||
1684 // If there are wins on the entry edge but the backadge also has sufficient wins,
1685 // there is sufficient profitability to spilt regardless of the risk of messing
1686 // up the loop structure.
1687 _loop_back_wins > policy ||
1688 // If the policy is less than 0, a split is always profitable, i.e. we always
1689 // split. This is needed when we split a node and then must also split a
1690 // dependant node, i.e. spliting a Bool node after splitting a Cmp node.
1691 policy < 0;
1692 }
1693 };
1694
1695 public:
1696
1697 // Conversion of fill/copy patterns into intrinsic versions
1698 bool do_intrinsify_fill();
1699 bool intrinsify_fill(IdealLoopTree* lpt);
1700 bool match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value,
1701 Node*& shift, Node*& offset);
1702
1703 private:
1704 // Return a type based on condition control flow
1705 const TypeInt* filtered_type( Node *n, Node* n_ctrl);
1706 const TypeInt* filtered_type( Node *n ) { return filtered_type(n, nullptr); }
1707 // Helpers for filtered type
1708 const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl);
1709
1710 // Helper functions
1711 Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache );
1712 Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true );
1713 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 );
1714 bool split_up( Node *n, Node *blk1, Node *blk2 );
1715
1716 Node* place_outside_loop(Node* useblock, IdealLoopTree* loop) const;
1717 Node* try_move_store_before_loop(Node* n, Node *n_ctrl);
1718 void try_move_store_after_loop(Node* n);
1719 void move_flat_array_check_out_of_loop(Node* n);
1720 bool identical_backtoback_ifs(Node *n);
1721 bool flat_array_element_type_check(Node *n);
1722 bool can_split_if(Node *n_ctrl);
1723 bool cannot_split_division(const Node* n, const Node* region) const;
1724 static bool is_divisor_loop_phi(const Node* divisor, const Node* loop);
1725 bool loop_phi_backedge_type_contains_zero(const Node* phi_divisor, const Type* zero) const;
1726
1727 // Determine if a method is too big for a/another round of split-if, based on
1728 // a magic (approximate) ratio derived from the equally magic constant 35000,
1729 // previously used for this purpose (but without relating to the node limit).
1730 bool must_throttle_split_if() {
1731 uint threshold = C->max_node_limit() * 2 / 5;
1732 return C->live_nodes() > threshold;
1733 }
1734
1735 // A simplistic node request tracking mechanism, where
1736 // = UINT_MAX Request not valid or made final.
1737 // < UINT_MAX Nodes currently requested (estimate).
1738 uint _nodes_required;
1739
1740 enum { REQUIRE_MIN = 70 };
1741
1742 uint nodes_required() const { return _nodes_required; }
1743
1744 // Given the _currently_ available number of nodes, check whether there is
1745 // "room" for an additional request or not, considering the already required
1746 // number of nodes. Return TRUE if the new request is exceeding the node
1747 // budget limit, otherwise return FALSE. Note that this interpretation will
1748 // act pessimistic on additional requests when new nodes have already been
1749 // generated since the 'begin'. This behaviour fits with the intention that
1750 // node estimates/requests should be made upfront.
1751 bool exceeding_node_budget(uint required = 0) {
1752 assert(C->live_nodes() < C->max_node_limit(), "sanity");
1753 uint available = C->max_node_limit() - C->live_nodes();
1754 return available < required + _nodes_required + REQUIRE_MIN;
1755 }
1756
1757 uint require_nodes(uint require, uint minreq = REQUIRE_MIN) {
1758 precond(require > 0);
1759 _nodes_required += MAX2(require, minreq);
1760 return _nodes_required;
1761 }
1762
1763 bool may_require_nodes(uint require, uint minreq = REQUIRE_MIN) {
1764 return !exceeding_node_budget(require) && require_nodes(require, minreq) > 0;
1765 }
1766
1767 uint require_nodes_begin() {
1768 assert(_nodes_required == UINT_MAX, "Bad state (begin).");
1769 _nodes_required = 0;
1770 return C->live_nodes();
1771 }
1772
1773 // When a node request is final, optionally check that the requested number
1774 // of nodes was reasonably correct with respect to the number of new nodes
1775 // introduced since the last 'begin'. Always check that we have not exceeded
1776 // the maximum node limit.
1777 void require_nodes_final(uint live_at_begin, bool check_estimate) {
1778 assert(_nodes_required < UINT_MAX, "Bad state (final).");
1779
1780 #ifdef ASSERT
1781 if (check_estimate) {
1782 // Check that the node budget request was not off by too much (x2).
1783 // Should this be the case we _surely_ need to improve the estimates
1784 // used in our budget calculations.
1785 if (C->live_nodes() - live_at_begin > 2 * _nodes_required) {
1786 log_info(compilation)("Bad node estimate: actual = %d >> request = %d",
1787 C->live_nodes() - live_at_begin, _nodes_required);
1788 }
1789 }
1790 #endif
1791 // Assert that we have stayed within the node budget limit.
1792 assert(C->live_nodes() < C->max_node_limit(),
1793 "Exceeding node budget limit: %d + %d > %d (request = %d)",
1794 C->live_nodes() - live_at_begin, live_at_begin,
1795 C->max_node_limit(), _nodes_required);
1796
1797 _nodes_required = UINT_MAX;
1798 }
1799
1800 private:
1801
1802 bool _created_loop_node;
1803 DEBUG_ONLY(void dump_idoms(Node* early, Node* wrong_lca);)
1804 NOT_PRODUCT(void dump_idoms_in_reverse(const Node* n, const Node_List& idom_list) const;)
1805
1806 public:
1807 void set_created_loop_node() { _created_loop_node = true; }
1808 bool created_loop_node() { return _created_loop_node; }
1809 void register_new_node(Node* n, Node* blk);
1810 void register_new_node_with_ctrl_of(Node* new_node, Node* ctrl_of) {
1811 register_new_node(new_node, get_ctrl(ctrl_of));
1812 }
1813
1814 Node* clone_and_register(Node* n, Node* ctrl) {
1815 n = n->clone();
1816 register_new_node(n, ctrl);
1817 return n;
1818 }
1819
1820 #ifdef ASSERT
1821 void dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA);
1822 #endif
1823
1824 #ifndef PRODUCT
1825 void dump() const;
1826 void dump_idom(Node* n) const { dump_idom(n, 1000); } // For debugging
1827 void dump_idom(Node* n, uint count) const;
1828 void get_idoms(Node* n, uint count, Unique_Node_List& idoms) const;
1829 void dump(IdealLoopTree* loop, uint rpo_idx, Node_List &rpo_list) const;
1830 IdealLoopTree* get_loop_idx(Node* n) const {
1831 // Dead nodes have no loop, so return the top level loop instead
1832 return _loop_or_ctrl[n->_idx] ? (IdealLoopTree*)_loop_or_ctrl[n->_idx] : _ltree_root;
1833 }
1834 // Print some stats
1835 static void print_statistics();
1836 static int _loop_invokes; // Count of PhaseIdealLoop invokes
1837 static int _loop_work; // Sum of PhaseIdealLoop x _unique
1838 static volatile int _long_loop_candidates;
1839 static volatile int _long_loop_nests;
1840 static volatile int _long_loop_counted_loops;
1841 #endif
1842
1843 #ifdef ASSERT
1844 void verify() const;
1845 bool verify_idom_and_nodes(Node* root, const PhaseIdealLoop* phase_verify) const;
1846 bool verify_idom(Node* n, const PhaseIdealLoop* phase_verify) const;
1847 bool verify_loop_ctrl(Node* n, const PhaseIdealLoop* phase_verify) const;
1848 #endif
1849
1850 void rpo(Node* start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list) const;
1851
1852 void check_counted_loop_shape(IdealLoopTree* loop, Node* x, BasicType bt) NOT_DEBUG_RETURN;
1853
1854 LoopNode* create_inner_head(IdealLoopTree* loop, BaseCountedLoopNode* head, IfNode* exit_test);
1855
1856
1857 int extract_long_range_checks(const IdealLoopTree* loop, jint stride_con, int iters_limit, PhiNode* phi,
1858 Node_List &range_checks);
1859
1860 void transform_long_range_checks(int stride_con, const Node_List &range_checks, Node* outer_phi,
1861 Node* inner_iters_actual_int, Node* inner_phi,
1862 Node* iv_add, LoopNode* inner_head);
1863
1864 Node* get_late_ctrl_with_anti_dep(LoadNode* n, Node* early, Node* LCA);
1865
1866 bool ctrl_of_use_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop, Node* ctrl);
1867
1868 bool ctrl_of_all_uses_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop);
1869
1870 Node* compute_early_ctrl(Node* n, Node* n_ctrl);
1871
1872 void try_sink_out_of_loop(Node* n);
1873
1874 Node* clamp(Node* R, Node* L, Node* H);
1875
1876 bool safe_for_if_replacement(const Node* dom) const;
1877
1878 void push_pinned_nodes_thru_region(IfNode* dom_if, Node* region);
1879
1880 bool try_merge_identical_ifs(Node* n);
1881
1882 void clone_loop_body(const Node_List& body, Node_List &old_new, CloneMap* cm);
1883
1884 void fix_body_edges(const Node_List &body, IdealLoopTree* loop, const Node_List &old_new, int dd,
1885 IdealLoopTree* parent, bool partial);
1886
1887 void fix_ctrl_uses(const Node_List& body, const IdealLoopTree* loop, Node_List &old_new, CloneLoopMode mode,
1888 Node* side_by_side_idom, CloneMap* cm, Node_List &worklist);
1889
1890 void fix_data_uses(Node_List& body, IdealLoopTree* loop, CloneLoopMode mode, IdealLoopTree* outer_loop,
1891 uint new_counter, Node_List& old_new, Node_List& worklist, Node_List*& split_if_set,
1892 Node_List*& split_bool_set, Node_List*& split_cex_set);
1893
1894 void finish_clone_loop(Node_List* split_if_set, Node_List* split_bool_set, Node_List* split_cex_set);
1895
1896 bool at_relevant_ctrl(Node* n, const Node* blk1, const Node* blk2);
1897
1898 bool clone_cmp_loadklass_down(Node* n, const Node* blk1, const Node* blk2);
1899 void clone_loadklass_nodes_at_cmp_index(const Node* n, Node* cmp, int i);
1900 bool clone_cmp_down(Node* n, const Node* blk1, const Node* blk2);
1901 void clone_template_assertion_expression_down(Node* node);
1902
1903 Node* similar_subtype_check(const Node* x, Node* r_in);
1904
1905 void update_addp_chain_base(Node* x, Node* old_base, Node* new_base);
1906
1907 bool can_move_to_inner_loop(Node* n, LoopNode* n_loop, Node* x);
1908
1909 void pin_array_access_nodes_dependent_on(Node* ctrl);
1910
1911 void collect_flat_array_checks(const IdealLoopTree* loop, Node_List& flat_array_checks) const;
1912
1913 Node* ensure_node_and_inputs_are_above_pre_end(CountedLoopEndNode* pre_end, Node* node);
1914
1915 bool try_make_short_running_loop(IdealLoopTree* loop, jint stride_con, const Node_List& range_checks, const uint iters_limit);
1916
1917 ConINode* intcon(jint i);
1918
1919 ConLNode* longcon(jlong i);
1920
1921 ConNode* makecon(const Type* t);
1922
1923 ConNode* integercon(jlong l, BasicType bt);
1924
1925 ConNode* zerocon(BasicType bt);
1926 };
1927
1928
1929 class AutoNodeBudget : public StackObj
1930 {
1931 public:
1932 enum budget_check_t { BUDGET_CHECK, NO_BUDGET_CHECK };
1933
1934 AutoNodeBudget(PhaseIdealLoop* phase, budget_check_t chk = BUDGET_CHECK)
1935 : _phase(phase),
1936 _check_at_final(chk == BUDGET_CHECK),
1937 _nodes_at_begin(0)
1938 {
1939 precond(_phase != nullptr);
1940
1941 _nodes_at_begin = _phase->require_nodes_begin();
1942 }
1943
1944 ~AutoNodeBudget() {
1945 #ifndef PRODUCT
1946 if (TraceLoopOpts) {
1947 uint request = _phase->nodes_required();
1948 uint delta = _phase->C->live_nodes() - _nodes_at_begin;
1949
1950 if (request < delta) {
1951 tty->print_cr("Exceeding node budget: %d < %d", request, delta);
1952 } else {
1953 uint const REQUIRE_MIN = PhaseIdealLoop::REQUIRE_MIN;
1954 // Identify the worst estimates as "poor" ones.
1955 if (request > REQUIRE_MIN && delta > 0) {
1956 if ((delta > REQUIRE_MIN && request > 3 * delta) ||
1957 (delta <= REQUIRE_MIN && request > 10 * delta)) {
1958 tty->print_cr("Poor node estimate: %d >> %d", request, delta);
1959 }
1960 }
1961 }
1962 }
1963 #endif // PRODUCT
1964 _phase->require_nodes_final(_nodes_at_begin, _check_at_final);
1965 }
1966
1967 private:
1968 PhaseIdealLoop* _phase;
1969 bool _check_at_final;
1970 uint _nodes_at_begin;
1971 };
1972
1973 inline Node* IdealLoopTree::tail() {
1974 // Handle lazy update of _tail field.
1975 if (_tail->in(0) == nullptr) {
1976 _tail = _phase->get_ctrl(_tail);
1977 }
1978 return _tail;
1979 }
1980
1981 inline Node* IdealLoopTree::head() {
1982 // Handle lazy update of _head field.
1983 if (_head->in(0) == nullptr) {
1984 _head = _phase->get_ctrl(_head);
1985 }
1986 return _head;
1987 }
1988
1989 // Iterate over the loop tree using a preorder, left-to-right traversal.
1990 //
1991 // Example that visits all counted loops from within PhaseIdealLoop
1992 //
1993 // for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
1994 // IdealLoopTree* lpt = iter.current();
1995 // if (!lpt->is_counted()) continue;
1996 // ...
1997 class LoopTreeIterator : public StackObj {
1998 private:
1999 IdealLoopTree* _root;
2000 IdealLoopTree* _curnt;
2001
2002 public:
2003 LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {}
2004
2005 bool done() { return _curnt == nullptr; } // Finished iterating?
2006
2007 void next(); // Advance to next loop tree
2008
2009 IdealLoopTree* current() { return _curnt; } // Return current value of iterator.
2010 };
2011
2012 // Compute probability of reaching some CFG node from a fixed
2013 // dominating CFG node
2014 class PathFrequency {
2015 private:
2016 Node* _dom; // frequencies are computed relative to this node
2017 Node_Stack _stack;
2018 GrowableArray<float> _freqs_stack; // keep track of intermediate result at regions
2019 GrowableArray<float> _freqs; // cache frequencies
2020 PhaseIdealLoop* _phase;
2021
2022 float check_and_truncate_frequency(float f) {
2023 assert(f >= 0, "Incorrect frequency");
2024 // We do not perform an exact (f <= 1) check
2025 // this would be error prone with rounding of floats.
2026 // Performing a check like (f <= 1+eps) would be of benefit,
2027 // however, it is not evident how to determine such an eps,
2028 // given that an arbitrary number of add/mul operations
2029 // are performed on these frequencies.
2030 return (f > 1) ? 1 : f;
2031 }
2032
2033 public:
2034 PathFrequency(Node* dom, PhaseIdealLoop* phase)
2035 : _dom(dom), _stack(0), _phase(phase) {
2036 }
2037
2038 float to(Node* n);
2039 };
2040
2041 // Class to clone a data node graph by taking a list of data nodes. This is done in 2 steps:
2042 // 1. Clone the data nodes
2043 // 2. Fix the cloned data inputs pointing to the old nodes to the cloned inputs by using an old->new mapping.
2044 class DataNodeGraph : public StackObj {
2045 PhaseIdealLoop* const _phase;
2046 const Unique_Node_List& _data_nodes;
2047 OrigToNewHashtable _orig_to_new;
2048
2049 public:
2050 DataNodeGraph(const Unique_Node_List& data_nodes, PhaseIdealLoop* phase)
2051 : _phase(phase),
2052 _data_nodes(data_nodes),
2053 // Use 107 as best guess which is the first resize value in ResizeableHashTable::large_table_sizes.
2054 _orig_to_new(107, MaxNodeLimit)
2055 {
2056 #ifdef ASSERT
2057 for (uint i = 0; i < data_nodes.size(); i++) {
2058 assert(!data_nodes[i]->is_CFG(), "only data nodes");
2059 }
2060 #endif
2061 }
2062 NONCOPYABLE(DataNodeGraph);
2063
2064 private:
2065 void clone(Node* node, Node* new_ctrl);
2066 void clone_data_nodes(Node* new_ctrl);
2067 void clone_data_nodes_and_transform_opaque_loop_nodes(const TransformStrategyForOpaqueLoopNodes& transform_strategy,
2068 Node* new_ctrl);
2069 void rewire_clones_to_cloned_inputs();
2070 void transform_opaque_node(const TransformStrategyForOpaqueLoopNodes& transform_strategy, Node* node);
2071
2072 public:
2073 // Clone the provided data node collection and rewire the clones in such a way to create an identical graph copy.
2074 // Set 'new_ctrl' as ctrl for the cloned nodes.
2075 const OrigToNewHashtable& clone(Node* new_ctrl) {
2076 assert(_orig_to_new.number_of_entries() == 0, "should not call this method twice in a row");
2077 clone_data_nodes(new_ctrl);
2078 rewire_clones_to_cloned_inputs();
2079 return _orig_to_new;
2080 }
2081
2082 // Create a copy of the data nodes provided to the constructor by doing the following:
2083 // Clone all non-OpaqueLoop* nodes and rewire them to create an identical subgraph copy. For the OpaqueLoop* nodes,
2084 // apply the provided transformation strategy and include the transformed node into the subgraph copy to get a complete
2085 // "cloned-and-transformed" graph copy. For all newly cloned nodes (which could also be new OpaqueLoop* nodes), set
2086 // `new_ctrl` as ctrl.
2087 const OrigToNewHashtable& clone_with_opaque_loop_transform_strategy(
2088 const TransformStrategyForOpaqueLoopNodes& transform_strategy,
2089 Node* new_ctrl) {
2090 clone_data_nodes_and_transform_opaque_loop_nodes(transform_strategy, new_ctrl);
2091 rewire_clones_to_cloned_inputs();
2092 return _orig_to_new;
2093 }
2094 };
2095 #endif // SHARE_OPTO_LOOPNODE_HPP