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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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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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 LoopSelector;
47 class UnswitchedLoopSelector;
48 class VectorSet;
49 class VSharedData;
50 class Invariance;
51 struct small_cache;
52
53 //
54 // I D E A L I Z E D L O O P S
55 //
56 // Idealized loops are the set of loops I perform more interesting
57 // transformations on, beyond simple hoisting.
58
59 //------------------------------LoopNode---------------------------------------
60 // Simple loop header. Fall in path on left, loop-back path on right.
61 class LoopNode : public RegionNode {
62 // Size is bigger to hold the flags. However, the flags do not change
63 // the semantics so it does not appear in the hash & cmp functions.
64 virtual uint size_of() const { return sizeof(*this); }
65 protected:
66 uint _loop_flags;
67 // Names for flag bitfields
68 enum { Normal=0, Pre=1, Main=2, Post=3, PreMainPostFlagsMask=3,
69 MainHasNoPreLoop = 1<<2,
70 HasExactTripCount = 1<<3,
71 InnerLoop = 1<<4,
72 PartialPeelLoop = 1<<5,
73 PartialPeelFailed = 1<<6,
74 WasSlpAnalyzed = 1<<7,
75 PassedSlpAnalysis = 1<<8,
76 DoUnrollOnly = 1<<9,
77 VectorizedLoop = 1<<10,
78 HasAtomicPostLoop = 1<<11,
79 StripMined = 1<<12,
80 SubwordLoop = 1<<13,
81 ProfileTripFailed = 1<<14,
82 LoopNestInnerLoop = 1<<15,
83 LoopNestLongOuterLoop = 1<<16,
84 MultiversionFastLoop = 1<<17,
85 MultiversionSlowLoop = 2<<17,
86 MultiversionDelayedSlowLoop = 3<<17,
87 MultiversionFlagsMask = 3<<17,
88 };
89 char _unswitch_count;
90 enum { _unswitch_max=3 };
91
92 // Expected trip count from profile data
93 float _profile_trip_cnt;
94
95 public:
96 // Names for edge indices
97 enum { Self=0, EntryControl, LoopBackControl };
98
99 bool is_inner_loop() const { return _loop_flags & InnerLoop; }
100 void set_inner_loop() { _loop_flags |= InnerLoop; }
101
102 bool is_vectorized_loop() const { return _loop_flags & VectorizedLoop; }
103 bool is_partial_peel_loop() const { return _loop_flags & PartialPeelLoop; }
104 void set_partial_peel_loop() { _loop_flags |= PartialPeelLoop; }
105 bool partial_peel_has_failed() const { return _loop_flags & PartialPeelFailed; }
106 bool is_strip_mined() const { return _loop_flags & StripMined; }
107 bool is_profile_trip_failed() const { return _loop_flags & ProfileTripFailed; }
108 bool is_subword_loop() const { return _loop_flags & SubwordLoop; }
109 bool is_loop_nest_inner_loop() const { return _loop_flags & LoopNestInnerLoop; }
110 bool is_loop_nest_outer_loop() const { return _loop_flags & LoopNestLongOuterLoop; }
111
112 void mark_partial_peel_failed() { _loop_flags |= PartialPeelFailed; }
113 void mark_was_slp() { _loop_flags |= WasSlpAnalyzed; }
114 void mark_passed_slp() { _loop_flags |= PassedSlpAnalysis; }
115 void mark_do_unroll_only() { _loop_flags |= DoUnrollOnly; }
116 void mark_loop_vectorized() { _loop_flags |= VectorizedLoop; }
117 void mark_has_atomic_post_loop() { _loop_flags |= HasAtomicPostLoop; }
118 void mark_strip_mined() { _loop_flags |= StripMined; }
119 void clear_strip_mined() { _loop_flags &= ~StripMined; }
120 void mark_profile_trip_failed() { _loop_flags |= ProfileTripFailed; }
121 void mark_subword_loop() { _loop_flags |= SubwordLoop; }
122 void mark_loop_nest_inner_loop() { _loop_flags |= LoopNestInnerLoop; }
123 void mark_loop_nest_outer_loop() { _loop_flags |= LoopNestLongOuterLoop; }
124
125 int unswitch_max() { return _unswitch_max; }
126 int unswitch_count() { return _unswitch_count; }
127
128 void set_unswitch_count(int val) {
129 assert (val <= unswitch_max(), "too many unswitches");
130 _unswitch_count = val;
131 }
132
133 void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; }
134 float profile_trip_cnt() { return _profile_trip_cnt; }
135
136 LoopNode(Node *entry, Node *backedge)
137 : RegionNode(3), _loop_flags(0), _unswitch_count(0),
138 _profile_trip_cnt(COUNT_UNKNOWN) {
139 init_class_id(Class_Loop);
140 init_req(EntryControl, entry);
141 init_req(LoopBackControl, backedge);
142 }
143
144 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
145 virtual int Opcode() const;
146 bool can_be_counted_loop(PhaseValues* phase) const {
147 return req() == 3 && in(0) != nullptr &&
148 in(1) != nullptr && phase->type(in(1)) != Type::TOP &&
149 in(2) != nullptr && phase->type(in(2)) != Type::TOP;
150 }
151 bool is_valid_counted_loop(BasicType bt) const;
152 #ifndef PRODUCT
153 virtual void dump_spec(outputStream *st) const;
154 #endif
155
156 void verify_strip_mined(int expect_skeleton) const NOT_DEBUG_RETURN;
157 virtual LoopNode* skip_strip_mined(int expect_skeleton = 1) { return this; }
158 virtual IfTrueNode* outer_loop_tail() const { ShouldNotReachHere(); return nullptr; }
159 virtual OuterStripMinedLoopEndNode* outer_loop_end() const { ShouldNotReachHere(); return nullptr; }
160 virtual IfFalseNode* outer_loop_exit() const { ShouldNotReachHere(); return nullptr; }
161 virtual SafePointNode* outer_safepoint() const { ShouldNotReachHere(); return nullptr; }
162 };
163
164 //------------------------------Counted Loops----------------------------------
165 // Counted loops are all trip-counted loops, with exactly 1 trip-counter exit
166 // path (and maybe some other exit paths). The trip-counter exit is always
167 // last in the loop. The trip-counter have to stride by a constant;
168 // the exit value is also loop invariant.
169
170 // CountedLoopNodes and CountedLoopEndNodes come in matched pairs. The
171 // CountedLoopNode has the incoming loop control and the loop-back-control
172 // which is always the IfTrue before the matching CountedLoopEndNode. The
173 // CountedLoopEndNode has an incoming control (possibly not the
174 // CountedLoopNode if there is control flow in the loop), the post-increment
175 // trip-counter value, and the limit. The trip-counter value is always of
176 // the form (Op old-trip-counter stride). The old-trip-counter is produced
177 // by a Phi connected to the CountedLoopNode. The stride is constant.
178 // The Op is any commutable opcode, including Add, Mul, Xor. The
179 // CountedLoopEndNode also takes in the loop-invariant limit value.
180
181 // From a CountedLoopNode I can reach the matching CountedLoopEndNode via the
182 // loop-back control. From CountedLoopEndNodes I can reach CountedLoopNodes
183 // via the old-trip-counter from the Op node.
184
185 //------------------------------CountedLoopNode--------------------------------
186 // CountedLoopNodes head simple counted loops. CountedLoopNodes have as
187 // inputs the incoming loop-start control and the loop-back control, so they
188 // act like RegionNodes. They also take in the initial trip counter, the
189 // loop-invariant stride and the loop-invariant limit value. CountedLoopNodes
190 // produce a loop-body control and the trip counter value. Since
191 // CountedLoopNodes behave like RegionNodes I still have a standard CFG model.
192
193 class BaseCountedLoopNode : public LoopNode {
194 public:
195 BaseCountedLoopNode(Node *entry, Node *backedge)
196 : LoopNode(entry, backedge) {
197 }
198
199 Node *init_control() const { return in(EntryControl); }
200 Node *back_control() const { return in(LoopBackControl); }
201
202 Node* init_trip() const;
203 Node* stride() const;
204 bool stride_is_con() const;
205 Node* limit() const;
206 Node* incr() const;
207 Node* phi() const;
208
209 BaseCountedLoopEndNode* loopexit_or_null() const;
210 BaseCountedLoopEndNode* loopexit() const;
211
212 virtual BasicType bt() const = 0;
213
214 jlong stride_con() const;
215
216 static BaseCountedLoopNode* make(Node* entry, Node* backedge, BasicType bt);
217 };
218
219
220 class CountedLoopNode : public BaseCountedLoopNode {
221 // Size is bigger to hold _main_idx. However, _main_idx does not change
222 // the semantics so it does not appear in the hash & cmp functions.
223 virtual uint size_of() const { return sizeof(*this); }
224
225 // For Pre- and Post-loops during debugging ONLY, this holds the index of
226 // the Main CountedLoop. Used to assert that we understand the graph shape.
227 node_idx_t _main_idx;
228
229 // Known trip count calculated by compute_exact_trip_count()
230 uint _trip_count;
231
232 // Log2 of original loop bodies in unrolled loop
233 int _unrolled_count_log2;
234
235 // Node count prior to last unrolling - used to decide if
236 // unroll,optimize,unroll,optimize,... is making progress
237 int _node_count_before_unroll;
238
239 // If slp analysis is performed we record the maximum
240 // vector mapped unroll factor here
241 int _slp_maximum_unroll_factor;
242
243 public:
244 CountedLoopNode(Node *entry, Node *backedge)
245 : BaseCountedLoopNode(entry, backedge), _main_idx(0), _trip_count(max_juint),
246 _unrolled_count_log2(0), _node_count_before_unroll(0),
247 _slp_maximum_unroll_factor(0) {
248 init_class_id(Class_CountedLoop);
249 // Initialize _trip_count to the largest possible value.
250 // Will be reset (lower) if the loop's trip count is known.
251 }
252
253 virtual int Opcode() const;
254 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
255
256 CountedLoopEndNode* loopexit_or_null() const { return (CountedLoopEndNode*) BaseCountedLoopNode::loopexit_or_null(); }
257 CountedLoopEndNode* loopexit() const { return (CountedLoopEndNode*) BaseCountedLoopNode::loopexit(); }
258 int stride_con() const;
259
260 // Match increment with optional truncation
261 static Node*
262 match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInteger** trunc_type,
263 BasicType bt);
264
265 // A 'main' loop has a pre-loop and a post-loop. The 'main' loop
266 // can run short a few iterations and may start a few iterations in.
267 // It will be RCE'd and unrolled and aligned.
268
269 // A following 'post' loop will run any remaining iterations. Used
270 // during Range Check Elimination, the 'post' loop will do any final
271 // iterations with full checks. Also used by Loop Unrolling, where
272 // the 'post' loop will do any epilog iterations needed. Basically,
273 // a 'post' loop can not profitably be further unrolled or RCE'd.
274
275 // A preceding 'pre' loop will run at least 1 iteration (to do peeling),
276 // it may do under-flow checks for RCE and may do alignment iterations
277 // so the following main loop 'knows' that it is striding down cache
278 // lines.
279
280 // A 'main' loop that is ONLY unrolled or peeled, never RCE'd or
281 // Aligned, may be missing it's pre-loop.
282 bool is_normal_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Normal; }
283 bool is_pre_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Pre; }
284 bool is_main_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Main; }
285 bool is_post_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Post; }
286 bool was_slp_analyzed () const { return (_loop_flags&WasSlpAnalyzed) == WasSlpAnalyzed; }
287 bool has_passed_slp () const { return (_loop_flags&PassedSlpAnalysis) == PassedSlpAnalysis; }
288 bool is_unroll_only () const { return (_loop_flags&DoUnrollOnly) == DoUnrollOnly; }
289 bool is_main_no_pre_loop() const { return _loop_flags & MainHasNoPreLoop; }
290 bool has_atomic_post_loop () const { return (_loop_flags & HasAtomicPostLoop) == HasAtomicPostLoop; }
291 void set_main_no_pre_loop() { _loop_flags |= MainHasNoPreLoop; }
292
293 IfNode* find_multiversion_if_from_multiversion_fast_main_loop();
294
295 int main_idx() const { return _main_idx; }
296
297
298 void set_pre_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; }
299 void set_main_loop ( ) { assert(is_normal_loop(),""); _loop_flags |= Main; }
300 void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; }
301 void set_normal_loop( ) { _loop_flags &= ~PreMainPostFlagsMask; }
302
303 void set_trip_count(uint tc) { _trip_count = tc; }
304 uint trip_count() { return _trip_count; }
305
306 bool has_exact_trip_count() const { return (_loop_flags & HasExactTripCount) != 0; }
307 void set_exact_trip_count(uint tc) {
308 _trip_count = tc;
309 _loop_flags |= HasExactTripCount;
310 }
311 void set_nonexact_trip_count() {
312 _loop_flags &= ~HasExactTripCount;
313 }
314 void set_notpassed_slp() {
315 _loop_flags &= ~PassedSlpAnalysis;
316 }
317
318 void double_unrolled_count() { _unrolled_count_log2++; }
319 int unrolled_count() { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); }
320
321 void set_node_count_before_unroll(int ct) { _node_count_before_unroll = ct; }
322 int node_count_before_unroll() { return _node_count_before_unroll; }
323 void set_slp_max_unroll(int unroll_factor) { _slp_maximum_unroll_factor = unroll_factor; }
324 int slp_max_unroll() const { return _slp_maximum_unroll_factor; }
325
326 // Multiversioning allows us to duplicate a CountedLoop, and have two versions, and the multiversion_if
327 // decides which one is taken:
328 // (1) fast_loop: We enter this loop by default, by default the multiversion_if has its condition set to
329 // "true", guarded by a OpaqueMultiversioning. If we want to make a speculative assumption
330 // for an optimization, we can add the runtime-check to the multiversion_if, and if the
331 // assumption fails we take the slow_loop instead, where we do not make the same speculative
332 // assumption.
333 // We call it the "fast_loop" because it has more optimizations, enabled by the speculative
334 // runtime-checks at the multiversion_if, and we expect the fast_loop to execute faster.
335 // (2) slow_loop: By default, it is not taken, until a runtime-check is added to the multiversion_if while
336 // optimizing the fast_looop. If such a runtime-check is never added, then after loop-opts
337 // the multiversion_if constant folds to true, and the slow_loop is folded away. To save
338 // compile time, we delay the optimization of the slow_loop until a runtime-check is added
339 // to the multiversion_if, at which point we resume optimizations for the slow_loop.
340 // We call it the "slow_loop" because it has fewer optimizations, since this is the fall-back
341 // loop where we do not make any of the speculative assumptions we make for the fast_loop.
342 // Hence, we expect the slow_loop to execute slower.
343 bool is_multiversion() const { return (_loop_flags & MultiversionFlagsMask) != Normal; }
344 bool is_multiversion_fast_loop() const { return (_loop_flags & MultiversionFlagsMask) == MultiversionFastLoop; }
345 bool is_multiversion_slow_loop() const { return (_loop_flags & MultiversionFlagsMask) == MultiversionSlowLoop; }
346 bool is_multiversion_delayed_slow_loop() const { return (_loop_flags & MultiversionFlagsMask) == MultiversionDelayedSlowLoop; }
347 void set_multiversion_fast_loop() { assert(!is_multiversion(), ""); _loop_flags |= MultiversionFastLoop; }
348 void set_multiversion_slow_loop() { assert(!is_multiversion(), ""); _loop_flags |= MultiversionSlowLoop; }
349 void set_multiversion_delayed_slow_loop() { assert(!is_multiversion(), ""); _loop_flags |= MultiversionDelayedSlowLoop; }
350 void set_no_multiversion() { assert( is_multiversion(), ""); _loop_flags &= ~MultiversionFlagsMask; }
351
352 virtual LoopNode* skip_strip_mined(int expect_skeleton = 1);
353 OuterStripMinedLoopNode* outer_loop() const;
354 virtual IfTrueNode* outer_loop_tail() const;
355 virtual OuterStripMinedLoopEndNode* outer_loop_end() const;
356 virtual IfFalseNode* outer_loop_exit() const;
357 virtual SafePointNode* outer_safepoint() const;
358
359 Node* skip_assertion_predicates_with_halt();
360
361 virtual BasicType bt() const {
362 return T_INT;
363 }
364
365 Node* is_canonical_loop_entry();
366 CountedLoopEndNode* find_pre_loop_end();
367
368 Node* uncasted_init_trip(bool uncasted);
369
370 #ifndef PRODUCT
371 virtual void dump_spec(outputStream *st) const;
372 #endif
373 };
374
375 class LongCountedLoopNode : public BaseCountedLoopNode {
376 public:
377 LongCountedLoopNode(Node *entry, Node *backedge)
378 : BaseCountedLoopNode(entry, backedge) {
379 init_class_id(Class_LongCountedLoop);
380 }
381
382 virtual int Opcode() const;
383
384 virtual BasicType bt() const {
385 return T_LONG;
386 }
387
388 LongCountedLoopEndNode* loopexit_or_null() const { return (LongCountedLoopEndNode*) BaseCountedLoopNode::loopexit_or_null(); }
389 LongCountedLoopEndNode* loopexit() const { return (LongCountedLoopEndNode*) BaseCountedLoopNode::loopexit(); }
390 };
391
392
393 //------------------------------CountedLoopEndNode-----------------------------
394 // CountedLoopEndNodes end simple trip counted loops. They act much like
395 // IfNodes.
396
397 class BaseCountedLoopEndNode : public IfNode {
398 public:
399 enum { TestControl, TestValue };
400 BaseCountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
401 : IfNode(control, test, prob, cnt) {
402 init_class_id(Class_BaseCountedLoopEnd);
403 }
404
405 Node *cmp_node() const { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : nullptr; }
406 Node* incr() const { Node* tmp = cmp_node(); return (tmp && tmp->req() == 3) ? tmp->in(1) : nullptr; }
407 Node* limit() const { Node* tmp = cmp_node(); return (tmp && tmp->req() == 3) ? tmp->in(2) : nullptr; }
408 Node* stride() const { Node* tmp = incr(); return (tmp && tmp->req() == 3) ? tmp->in(2) : nullptr; }
409 Node* init_trip() const { Node* tmp = phi(); return (tmp && tmp->req() == 3) ? tmp->in(1) : nullptr; }
410 bool stride_is_con() const { Node *tmp = stride(); return (tmp != nullptr && tmp->is_Con()); }
411
412 PhiNode* phi() const {
413 Node* tmp = incr();
414 if (tmp && tmp->req() == 3) {
415 Node* phi = tmp->in(1);
416 if (phi->is_Phi()) {
417 return phi->as_Phi();
418 }
419 }
420 return nullptr;
421 }
422
423 BaseCountedLoopNode* loopnode() const {
424 // The CountedLoopNode that goes with this CountedLoopEndNode may
425 // have been optimized out by the IGVN so be cautious with the
426 // pattern matching on the graph
427 PhiNode* iv_phi = phi();
428 if (iv_phi == nullptr) {
429 return nullptr;
430 }
431 Node* ln = iv_phi->in(0);
432 if (!ln->is_BaseCountedLoop() || ln->as_BaseCountedLoop()->loopexit_or_null() != this) {
433 return nullptr;
434 }
435 if (ln->as_BaseCountedLoop()->bt() != bt()) {
436 return nullptr;
437 }
438 return ln->as_BaseCountedLoop();
439 }
440
441 BoolTest::mask test_trip() const { return in(TestValue)->as_Bool()->_test._test; }
442
443 jlong stride_con() const;
444 virtual BasicType bt() const = 0;
445
446 static BaseCountedLoopEndNode* make(Node* control, Node* test, float prob, float cnt, BasicType bt);
447 };
448
449 class CountedLoopEndNode : public BaseCountedLoopEndNode {
450 public:
451
452 CountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
453 : BaseCountedLoopEndNode(control, test, prob, cnt) {
454 init_class_id(Class_CountedLoopEnd);
455 }
456 virtual int Opcode() const;
457
458 CountedLoopNode* loopnode() const {
459 return (CountedLoopNode*) BaseCountedLoopEndNode::loopnode();
460 }
461
462 virtual BasicType bt() const {
463 return T_INT;
464 }
465
466 #ifndef PRODUCT
467 virtual void dump_spec(outputStream *st) const;
468 #endif
469 };
470
471 class LongCountedLoopEndNode : public BaseCountedLoopEndNode {
472 public:
473 LongCountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
474 : BaseCountedLoopEndNode(control, test, prob, cnt) {
475 init_class_id(Class_LongCountedLoopEnd);
476 }
477
478 LongCountedLoopNode* loopnode() const {
479 return (LongCountedLoopNode*) BaseCountedLoopEndNode::loopnode();
480 }
481
482 virtual int Opcode() const;
483
484 virtual BasicType bt() const {
485 return T_LONG;
486 }
487 };
488
489
490 inline BaseCountedLoopEndNode* BaseCountedLoopNode::loopexit_or_null() const {
491 Node* bctrl = back_control();
492 if (bctrl == nullptr) return nullptr;
493
494 Node* lexit = bctrl->in(0);
495 if (!lexit->is_BaseCountedLoopEnd()) {
496 return nullptr;
497 }
498 BaseCountedLoopEndNode* result = lexit->as_BaseCountedLoopEnd();
499 if (result->bt() != bt()) {
500 return nullptr;
501 }
502 return result;
503 }
504
505 inline BaseCountedLoopEndNode* BaseCountedLoopNode::loopexit() const {
506 BaseCountedLoopEndNode* cle = loopexit_or_null();
507 assert(cle != nullptr, "loopexit is null");
508 return cle;
509 }
510
511 inline Node* BaseCountedLoopNode::init_trip() const {
512 BaseCountedLoopEndNode* cle = loopexit_or_null();
513 return cle != nullptr ? cle->init_trip() : nullptr;
514 }
515 inline Node* BaseCountedLoopNode::stride() const {
516 BaseCountedLoopEndNode* cle = loopexit_or_null();
517 return cle != nullptr ? cle->stride() : nullptr;
518 }
519
520 inline bool BaseCountedLoopNode::stride_is_con() const {
521 BaseCountedLoopEndNode* cle = loopexit_or_null();
522 return cle != nullptr && cle->stride_is_con();
523 }
524 inline Node* BaseCountedLoopNode::limit() const {
525 BaseCountedLoopEndNode* cle = loopexit_or_null();
526 return cle != nullptr ? cle->limit() : nullptr;
527 }
528 inline Node* BaseCountedLoopNode::incr() const {
529 BaseCountedLoopEndNode* cle = loopexit_or_null();
530 return cle != nullptr ? cle->incr() : nullptr;
531 }
532 inline Node* BaseCountedLoopNode::phi() const {
533 BaseCountedLoopEndNode* cle = loopexit_or_null();
534 return cle != nullptr ? cle->phi() : nullptr;
535 }
536
537 inline jlong BaseCountedLoopNode::stride_con() const {
538 BaseCountedLoopEndNode* cle = loopexit_or_null();
539 return cle != nullptr ? cle->stride_con() : 0;
540 }
541
542
543 //------------------------------LoopLimitNode-----------------------------
544 // Counted Loop limit node which represents exact final iterator value:
545 // trip_count = (limit - init_trip + stride - 1)/stride
546 // final_value= trip_count * stride + init_trip.
547 // Use HW instructions to calculate it when it can overflow in integer.
548 // Note, final_value should fit into integer since counted loop has
549 // limit check: limit <= max_int-stride.
550 class LoopLimitNode : public Node {
551 enum { Init=1, Limit=2, Stride=3 };
552 public:
553 LoopLimitNode( Compile* C, Node *init, Node *limit, Node *stride ) : Node(nullptr,init,limit,stride) {
554 // Put it on the Macro nodes list to optimize during macro nodes expansion.
555 init_flags(Flag_is_macro);
556 C->add_macro_node(this);
557 }
558 virtual int Opcode() const;
559 virtual const Type *bottom_type() const { return TypeInt::INT; }
560 virtual uint ideal_reg() const { return Op_RegI; }
561 virtual const Type* Value(PhaseGVN* phase) const;
562 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
563 virtual Node* Identity(PhaseGVN* phase);
564 };
565
566 // Support for strip mining
567 class OuterStripMinedLoopNode : public LoopNode {
568 private:
569 static void fix_sunk_stores(CountedLoopEndNode* inner_cle, LoopNode* inner_cl, PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
570
571 public:
572 OuterStripMinedLoopNode(Compile* C, Node *entry, Node *backedge)
573 : LoopNode(entry, backedge) {
574 init_class_id(Class_OuterStripMinedLoop);
575 init_flags(Flag_is_macro);
576 C->add_macro_node(this);
577 }
578
579 virtual int Opcode() const;
580
581 virtual IfTrueNode* outer_loop_tail() const;
582 virtual OuterStripMinedLoopEndNode* outer_loop_end() const;
583 virtual IfFalseNode* outer_loop_exit() const;
584 virtual SafePointNode* outer_safepoint() const;
585 void adjust_strip_mined_loop(PhaseIterGVN* igvn);
586
587 void remove_outer_loop_and_safepoint(PhaseIterGVN* igvn) const;
588
589 void transform_to_counted_loop(PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
590
591 static Node* register_new_node(Node* node, LoopNode* ctrl, PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
592
593 Node* register_control(Node* node, Node* loop, Node* idom, PhaseIterGVN* igvn,
594 PhaseIdealLoop* iloop);
595 };
596
597 class OuterStripMinedLoopEndNode : public IfNode {
598 public:
599 OuterStripMinedLoopEndNode(Node *control, Node *test, float prob, float cnt)
600 : IfNode(control, test, prob, cnt) {
601 init_class_id(Class_OuterStripMinedLoopEnd);
602 }
603
604 virtual int Opcode() const;
605
606 virtual const Type* Value(PhaseGVN* phase) const;
607 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
608
609 bool is_expanded(PhaseGVN *phase) const;
610 };
611
612 // -----------------------------IdealLoopTree----------------------------------
613 class IdealLoopTree : public ResourceObj {
614 public:
615 IdealLoopTree *_parent; // Parent in loop tree
616 IdealLoopTree *_next; // Next sibling in loop tree
617 IdealLoopTree *_child; // First child in loop tree
618
619 // The head-tail backedge defines the loop.
620 // If a loop has multiple backedges, this is addressed during cleanup where
621 // we peel off the multiple backedges, merging all edges at the bottom and
622 // ensuring that one proper backedge flow into the loop.
623 Node *_head; // Head of loop
624 Node *_tail; // Tail of loop
625 inline Node *tail(); // Handle lazy update of _tail field
626 inline Node *head(); // Handle lazy update of _head field
627 PhaseIdealLoop* _phase;
628 int _local_loop_unroll_limit;
629 int _local_loop_unroll_factor;
630
631 Node_List _body; // Loop body for inner loops
632
633 uint16_t _nest; // Nesting depth
634 uint8_t _irreducible:1, // True if irreducible
635 _has_call:1, // True if has call safepoint
636 _has_sfpt:1, // True if has non-call safepoint
637 _rce_candidate:1, // True if candidate for range check elimination
638 _has_range_checks:1,
639 _has_range_checks_computed:1;
640
641 Node_List* _safepts; // List of safepoints in this loop
642 Node_List* _required_safept; // A inner loop cannot delete these safepts;
643 bool _allow_optimizations; // Allow loop optimizations
644
645 IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail )
646 : _parent(nullptr), _next(nullptr), _child(nullptr),
647 _head(head), _tail(tail),
648 _phase(phase),
649 _local_loop_unroll_limit(0), _local_loop_unroll_factor(0),
650 _body(Compile::current()->comp_arena()),
651 _nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0),
652 _has_range_checks(0), _has_range_checks_computed(0),
653 _safepts(nullptr),
654 _required_safept(nullptr),
655 _allow_optimizations(true)
656 {
657 precond(_head != nullptr);
658 precond(_tail != nullptr);
659 }
660
661 // Is 'l' a member of 'this'?
662 bool is_member(const IdealLoopTree *l) const; // Test for nested membership
663
664 // Set loop nesting depth. Accumulate has_call bits.
665 int set_nest( uint depth );
666
667 // Split out multiple fall-in edges from the loop header. Move them to a
668 // private RegionNode before the loop. This becomes the loop landing pad.
669 void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt );
670
671 // Split out the outermost loop from this shared header.
672 void split_outer_loop( PhaseIdealLoop *phase );
673
674 // Merge all the backedges from the shared header into a private Region.
675 // Feed that region as the one backedge to this loop.
676 void merge_many_backedges( PhaseIdealLoop *phase );
677
678 // Split shared headers and insert loop landing pads.
679 // Insert a LoopNode to replace the RegionNode.
680 // Returns TRUE if loop tree is structurally changed.
681 bool beautify_loops( PhaseIdealLoop *phase );
682
683 // Perform optimization to use the loop predicates for null checks and range checks.
684 // Applies to any loop level (not just the innermost one)
685 bool loop_predication( PhaseIdealLoop *phase);
686 bool can_apply_loop_predication();
687
688 // Perform iteration-splitting on inner loops. Split iterations to
689 // avoid range checks or one-shot null checks. Returns false if the
690 // current round of loop opts should stop.
691 bool iteration_split( PhaseIdealLoop *phase, Node_List &old_new );
692
693 // Driver for various flavors of iteration splitting. Returns false
694 // if the current round of loop opts should stop.
695 bool iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new );
696
697 // Given dominators, try to find loops with calls that must always be
698 // executed (call dominates loop tail). These loops do not need non-call
699 // safepoints (ncsfpt).
700 void check_safepts(VectorSet &visited, Node_List &stack);
701
702 // Allpaths backwards scan from loop tail, terminating each path at first safepoint
703 // encountered.
704 void allpaths_check_safepts(VectorSet &visited, Node_List &stack);
705
706 // Remove safepoints from loop. Optionally keeping one.
707 void remove_safepoints(PhaseIdealLoop* phase, bool keep_one);
708
709 // Convert to counted loops where possible
710 void counted_loop( PhaseIdealLoop *phase );
711
712 // Check for Node being a loop-breaking test
713 Node *is_loop_exit(Node *iff) const;
714
715 // Remove simplistic dead code from loop body
716 void DCE_loop_body();
717
718 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage.
719 // Replace with a 1-in-10 exit guess.
720 void adjust_loop_exit_prob( PhaseIdealLoop *phase );
721
722 // Return TRUE or FALSE if the loop should never be RCE'd or aligned.
723 // Useful for unrolling loops with NO array accesses.
724 bool policy_peel_only( PhaseIdealLoop *phase ) const;
725
726 // Return TRUE or FALSE if the loop should be unswitched -- clone
727 // loop with an invariant test
728 bool policy_unswitching( PhaseIdealLoop *phase ) const;
729
730 // Micro-benchmark spamming. Remove empty loops.
731 bool do_remove_empty_loop( PhaseIdealLoop *phase );
732
733 // Convert one iteration loop into normal code.
734 bool do_one_iteration_loop( PhaseIdealLoop *phase );
735
736 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can
737 // move some loop-invariant test (usually a null-check) before the loop.
738 bool policy_peeling(PhaseIdealLoop *phase);
739
740 uint estimate_peeling(PhaseIdealLoop *phase);
741
742 // Return TRUE or FALSE if the loop should be maximally unrolled. Stash any
743 // known trip count in the counted loop node.
744 bool policy_maximally_unroll(PhaseIdealLoop *phase) const;
745
746 // Return TRUE or FALSE if the loop should be unrolled or not. Apply unroll
747 // if the loop is a counted loop and the loop body is small enough.
748 bool policy_unroll(PhaseIdealLoop *phase);
749
750 // Loop analyses to map to a maximal superword unrolling for vectorization.
751 void policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_ct);
752
753 // Return TRUE or FALSE if the loop should be range-check-eliminated.
754 // Gather a list of IF tests that are dominated by iteration splitting;
755 // also gather the end of the first split and the start of the 2nd split.
756 bool policy_range_check(PhaseIdealLoop* phase, bool provisional, BasicType bt) const;
757
758 // Return TRUE if "iff" is a range check.
759 bool is_range_check_if(IfProjNode* if_success_proj, PhaseIdealLoop* phase, Invariance& invar DEBUG_ONLY(COMMA ProjNode* predicate_proj)) const;
760 bool is_range_check_if(IfProjNode* if_success_proj, PhaseIdealLoop* phase, BasicType bt, Node* iv, Node*& range, Node*& offset,
761 jlong& scale) const;
762
763 // Estimate the number of nodes required when cloning a loop (body).
764 uint est_loop_clone_sz(uint factor) const;
765 // Estimate the number of nodes required when unrolling a loop (body).
766 uint est_loop_unroll_sz(uint factor) const;
767
768 // Compute loop trip count if possible
769 void compute_trip_count(PhaseIdealLoop* phase);
770
771 // Compute loop trip count from profile data
772 float compute_profile_trip_cnt_helper(Node* n);
773 void compute_profile_trip_cnt( PhaseIdealLoop *phase );
774
775 // Reassociate invariant expressions.
776 void reassociate_invariants(PhaseIdealLoop *phase);
777 // Reassociate invariant binary expressions.
778 Node* reassociate(Node* n1, PhaseIdealLoop *phase);
779 // Reassociate invariant add, subtract, and compare expressions.
780 Node* reassociate_add_sub_cmp(Node* n1, int inv1_idx, int inv2_idx, PhaseIdealLoop* phase);
781 // Return nonzero index of invariant operand if invariant and variant
782 // are combined with an associative binary. Helper for reassociate_invariants.
783 int find_invariant(Node* n, PhaseIdealLoop *phase);
784 // Return TRUE if "n" is associative.
785 bool is_associative(Node* n, Node* base=nullptr);
786 // Return TRUE if "n" is an associative cmp node.
787 bool is_associative_cmp(Node* n);
788
789 // Return true if n is invariant
790 bool is_invariant(Node* n) const;
791
792 // Put loop body on igvn work list
793 void record_for_igvn();
794
795 bool is_root() { return _parent == nullptr; }
796 // A proper/reducible loop w/o any (occasional) dead back-edge.
797 bool is_loop() { return !_irreducible && !tail()->is_top(); }
798 bool is_counted() { return is_loop() && _head->is_CountedLoop(); }
799 bool is_innermost() { return is_loop() && _child == nullptr; }
800
801 void remove_main_post_loops(CountedLoopNode *cl, PhaseIdealLoop *phase);
802
803 bool compute_has_range_checks() const;
804 bool range_checks_present() {
805 if (!_has_range_checks_computed) {
806 if (compute_has_range_checks()) {
807 _has_range_checks = 1;
808 }
809 _has_range_checks_computed = 1;
810 }
811 return _has_range_checks;
812 }
813
814 // Return the parent's IdealLoopTree for a strip mined loop which is the outer strip mined loop.
815 // In all other cases, return this.
816 IdealLoopTree* skip_strip_mined() {
817 return _head->as_Loop()->is_strip_mined() ? _parent : this;
818 }
819
820 #ifndef PRODUCT
821 void dump_head(); // Dump loop head only
822 void dump(); // Dump this loop recursively
823 #endif
824
825 #ifdef ASSERT
826 GrowableArray<IdealLoopTree*> collect_sorted_children() const;
827 bool verify_tree(IdealLoopTree* loop_verify) const;
828 #endif
829
830 private:
831 enum { EMPTY_LOOP_SIZE = 7 }; // Number of nodes in an empty loop.
832
833 // Estimate the number of nodes resulting from control and data flow merge.
834 uint est_loop_flow_merge_sz() const;
835
836 // Check if the number of residual iterations is large with unroll_cnt.
837 // Return true if the residual iterations are more than 10% of the trip count.
838 bool is_residual_iters_large(int unroll_cnt, CountedLoopNode *cl) const {
839 return (unroll_cnt - 1) * (100.0 / LoopPercentProfileLimit) > cl->profile_trip_cnt();
840 }
841
842 void collect_loop_core_nodes(PhaseIdealLoop* phase, Unique_Node_List& wq) const;
843
844 bool empty_loop_with_data_nodes(PhaseIdealLoop* phase) const;
845
846 void enqueue_data_nodes(PhaseIdealLoop* phase, Unique_Node_List& empty_loop_nodes, Unique_Node_List& wq) const;
847
848 bool process_safepoint(PhaseIdealLoop* phase, Unique_Node_List& empty_loop_nodes, Unique_Node_List& wq,
849 Node* sfpt) const;
850
851 bool empty_loop_candidate(PhaseIdealLoop* phase) const;
852
853 bool empty_loop_with_extra_nodes_candidate(PhaseIdealLoop* phase) const;
854 };
855
856 // -----------------------------PhaseIdealLoop---------------------------------
857 // Computes the mapping from Nodes to IdealLoopTrees. Organizes IdealLoopTrees
858 // into a loop tree. Drives the loop-based transformations on the ideal graph.
859 class PhaseIdealLoop : public PhaseTransform {
860 friend class IdealLoopTree;
861 friend class SuperWord;
862 friend class ShenandoahBarrierC2Support;
863 friend class AutoNodeBudget;
864
865 // Map loop membership for CFG nodes, and ctrl for non-CFG nodes.
866 Node_List _loop_or_ctrl;
867
868 // Pre-computed def-use info
869 PhaseIterGVN &_igvn;
870
871 // Head of loop tree
872 IdealLoopTree* _ltree_root;
873
874 // Array of pre-order numbers, plus post-visited bit.
875 // ZERO for not pre-visited. EVEN for pre-visited but not post-visited.
876 // ODD for post-visited. Other bits are the pre-order number.
877 uint *_preorders;
878 uint _max_preorder;
879
880 ReallocMark _nesting; // Safety checks for arena reallocation
881
882 const PhaseIdealLoop* _verify_me;
883 bool _verify_only;
884
885 // Allocate _preorders[] array
886 void allocate_preorders() {
887 _max_preorder = C->unique()+8;
888 _preorders = NEW_RESOURCE_ARRAY(uint, _max_preorder);
889 memset(_preorders, 0, sizeof(uint) * _max_preorder);
890 }
891
892 // Allocate _preorders[] array
893 void reallocate_preorders() {
894 _nesting.check(); // Check if a potential re-allocation in the resource arena is safe
895 if ( _max_preorder < C->unique() ) {
896 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique());
897 _max_preorder = C->unique();
898 }
899 memset(_preorders, 0, sizeof(uint) * _max_preorder);
900 }
901
902 // Check to grow _preorders[] array for the case when build_loop_tree_impl()
903 // adds new nodes.
904 void check_grow_preorders( ) {
905 _nesting.check(); // Check if a potential re-allocation in the resource arena is safe
906 if ( _max_preorder < C->unique() ) {
907 uint newsize = _max_preorder<<1; // double size of array
908 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize);
909 memset(&_preorders[_max_preorder],0,sizeof(uint)*(newsize-_max_preorder));
910 _max_preorder = newsize;
911 }
912 }
913 // Check for pre-visited. Zero for NOT visited; non-zero for visited.
914 int is_visited( Node *n ) const { return _preorders[n->_idx]; }
915 // Pre-order numbers are written to the Nodes array as low-bit-set values.
916 void set_preorder_visited( Node *n, int pre_order ) {
917 assert( !is_visited( n ), "already set" );
918 _preorders[n->_idx] = (pre_order<<1);
919 };
920 // Return pre-order number.
921 int get_preorder( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]>>1; }
922
923 // Check for being post-visited.
924 // Should be previsited already (checked with assert(is_visited(n))).
925 int is_postvisited( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]&1; }
926
927 // Mark as post visited
928 void set_postvisited( Node *n ) { assert( !is_postvisited( n ), "" ); _preorders[n->_idx] |= 1; }
929
930 public:
931 // Set/get control node out. Set lower bit to distinguish from IdealLoopTree
932 // Returns true if "n" is a data node, false if it's a control node.
933 bool has_ctrl(const Node* n) const { return ((intptr_t)_loop_or_ctrl[n->_idx]) & 1; }
934
935 private:
936 // clear out dead code after build_loop_late
937 Node_List _deadlist;
938 Node_List _zero_trip_guard_opaque_nodes;
939 Node_List _multiversion_opaque_nodes;
940
941 // Support for faster execution of get_late_ctrl()/dom_lca()
942 // when a node has many uses and dominator depth is deep.
943 GrowableArray<jlong> _dom_lca_tags;
944 uint _dom_lca_tags_round;
945 void init_dom_lca_tags();
946
947 // Helper for debugging bad dominance relationships
948 bool verify_dominance(Node* n, Node* use, Node* LCA, Node* early);
949
950 Node* compute_lca_of_uses(Node* n, Node* early, bool verify = false);
951
952 // Inline wrapper for frequent cases:
953 // 1) only one use
954 // 2) a use is the same as the current LCA passed as 'n1'
955 Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) {
956 assert( n->is_CFG(), "" );
957 // Fast-path null lca
958 if( lca != nullptr && lca != n ) {
959 assert( lca->is_CFG(), "" );
960 // find LCA of all uses
961 n = dom_lca_for_get_late_ctrl_internal( lca, n, tag );
962 }
963 return find_non_split_ctrl(n);
964 }
965 Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag );
966
967 // Helper function for directing control inputs away from CFG split points.
968 Node *find_non_split_ctrl( Node *ctrl ) const {
969 if (ctrl != nullptr) {
970 if (ctrl->is_MultiBranch()) {
971 ctrl = ctrl->in(0);
972 }
973 assert(ctrl->is_CFG(), "CFG");
974 }
975 return ctrl;
976 }
977
978 void cast_incr_before_loop(Node* incr, Node* ctrl, CountedLoopNode* loop);
979
980 #ifdef ASSERT
981 static void ensure_zero_trip_guard_proj(Node* node, bool is_main_loop);
982 #endif
983 private:
984 static void get_opaque_template_assertion_predicate_nodes(ParsePredicateSuccessProj* parse_predicate_proj,
985 Unique_Node_List& list);
986 void update_main_loop_assertion_predicates(CountedLoopNode* new_main_loop_head, int stride_con_before_unroll);
987 void initialize_assertion_predicates_for_peeled_loop(CountedLoopNode* peeled_loop_head,
988 CountedLoopNode* remaining_loop_head,
989 uint first_node_index_in_cloned_loop_body,
990 const Node_List& old_new);
991 void initialize_assertion_predicates_for_main_loop(CountedLoopNode* pre_loop_head,
992 CountedLoopNode* main_loop_head,
993 uint first_node_index_in_pre_loop_body,
994 uint last_node_index_in_pre_loop_body,
995 DEBUG_ONLY(uint last_node_index_from_backedge_goo COMMA)
996 const Node_List& old_new);
997 void initialize_assertion_predicates_for_post_loop(CountedLoopNode* main_loop_head, CountedLoopNode* post_loop_head,
998 uint first_node_index_in_cloned_loop_body);
999 void create_assertion_predicates_at_loop(CountedLoopNode* source_loop_head, CountedLoopNode* target_loop_head,
1000 const NodeInLoopBody& _node_in_loop_body, bool kill_old_template);
1001 void create_assertion_predicates_at_main_or_post_loop(CountedLoopNode* source_loop_head,
1002 CountedLoopNode* target_loop_head,
1003 const NodeInLoopBody& _node_in_loop_body,
1004 bool kill_old_template);
1005 void rewire_old_target_loop_entry_dependency_to_new_entry(CountedLoopNode* target_loop_head,
1006 const Node* old_target_loop_entry,
1007 uint node_index_before_new_assertion_predicate_nodes);
1008 void insert_loop_limit_check_predicate(ParsePredicateSuccessProj* loop_limit_check_parse_proj, Node* cmp_limit,
1009 Node* bol);
1010 void log_loop_tree();
1011
1012 public:
1013
1014 PhaseIterGVN &igvn() const { return _igvn; }
1015
1016 bool has_node(const Node* n) const {
1017 guarantee(n != nullptr, "No Node.");
1018 return _loop_or_ctrl[n->_idx] != nullptr;
1019 }
1020 // check if transform created new nodes that need _ctrl recorded
1021 Node *get_late_ctrl( Node *n, Node *early );
1022 Node *get_early_ctrl( Node *n );
1023 Node *get_early_ctrl_for_expensive(Node *n, Node* earliest);
1024 void set_early_ctrl(Node* n, bool update_body);
1025 void set_subtree_ctrl(Node* n, bool update_body);
1026 void set_ctrl( Node *n, Node *ctrl ) {
1027 assert( !has_node(n) || has_ctrl(n), "" );
1028 assert( ctrl->in(0), "cannot set dead control node" );
1029 assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" );
1030 _loop_or_ctrl.map(n->_idx, (Node*)((intptr_t)ctrl + 1));
1031 }
1032 void set_root_as_ctrl(Node* n) {
1033 assert(!has_node(n) || has_ctrl(n), "");
1034 _loop_or_ctrl.map(n->_idx, (Node*)((intptr_t)C->root() + 1));
1035 }
1036 // Set control and update loop membership
1037 void set_ctrl_and_loop(Node* n, Node* ctrl) {
1038 IdealLoopTree* old_loop = get_loop(get_ctrl(n));
1039 IdealLoopTree* new_loop = get_loop(ctrl);
1040 if (old_loop != new_loop) {
1041 if (old_loop->_child == nullptr) old_loop->_body.yank(n);
1042 if (new_loop->_child == nullptr) new_loop->_body.push(n);
1043 }
1044 set_ctrl(n, ctrl);
1045 }
1046 // Control nodes can be replaced or subsumed. During this pass they
1047 // get their replacement Node in slot 1. Instead of updating the block
1048 // location of all Nodes in the subsumed block, we lazily do it. As we
1049 // pull such a subsumed block out of the array, we write back the final
1050 // correct block.
1051 Node* get_ctrl(const Node* i) {
1052 assert(has_node(i), "");
1053 Node *n = get_ctrl_no_update(i);
1054 _loop_or_ctrl.map(i->_idx, (Node*)((intptr_t)n + 1));
1055 assert(has_node(i) && has_ctrl(i), "");
1056 assert(n == find_non_split_ctrl(n), "must return legal ctrl" );
1057 return n;
1058 }
1059
1060 bool is_dominator(Node* dominator, Node* n);
1061 bool is_strict_dominator(Node* dominator, Node* n);
1062
1063 // return get_ctrl for a data node and self(n) for a CFG node
1064 Node* ctrl_or_self(Node* n) {
1065 if (has_ctrl(n))
1066 return get_ctrl(n);
1067 else {
1068 assert (n->is_CFG(), "must be a CFG node");
1069 return n;
1070 }
1071 }
1072
1073 Node* get_ctrl_no_update_helper(const Node* i) const {
1074 assert(has_ctrl(i), "should be control, not loop");
1075 return (Node*)(((intptr_t)_loop_or_ctrl[i->_idx]) & ~1);
1076 }
1077
1078 Node* get_ctrl_no_update(const Node* i) const {
1079 assert( has_ctrl(i), "" );
1080 Node *n = get_ctrl_no_update_helper(i);
1081 if (!n->in(0)) {
1082 // Skip dead CFG nodes
1083 do {
1084 n = get_ctrl_no_update_helper(n);
1085 } while (!n->in(0));
1086 n = find_non_split_ctrl(n);
1087 }
1088 return n;
1089 }
1090
1091 // Check for loop being set
1092 // "n" must be a control node. Returns true if "n" is known to be in a loop.
1093 bool has_loop( Node *n ) const {
1094 assert(!has_node(n) || !has_ctrl(n), "");
1095 return has_node(n);
1096 }
1097 // Set loop
1098 void set_loop( Node *n, IdealLoopTree *loop ) {
1099 _loop_or_ctrl.map(n->_idx, (Node*)loop);
1100 }
1101 // Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms. Replace
1102 // the 'old_node' with 'new_node'. Kill old-node. Add a reference
1103 // from old_node to new_node to support the lazy update. Reference
1104 // replaces loop reference, since that is not needed for dead node.
1105 void lazy_update(Node *old_node, Node *new_node) {
1106 assert(old_node != new_node, "no cycles please");
1107 // Re-use the side array slot for this node to provide the
1108 // forwarding pointer.
1109 _loop_or_ctrl.map(old_node->_idx, (Node*)((intptr_t)new_node + 1));
1110 }
1111 void lazy_replace(Node *old_node, Node *new_node) {
1112 _igvn.replace_node(old_node, new_node);
1113 lazy_update(old_node, new_node);
1114 }
1115
1116 private:
1117
1118 // Place 'n' in some loop nest, where 'n' is a CFG node
1119 void build_loop_tree();
1120 int build_loop_tree_impl(Node* n, int pre_order);
1121 // Insert loop into the existing loop tree. 'innermost' is a leaf of the
1122 // loop tree, not the root.
1123 IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost );
1124
1125 #ifdef ASSERT
1126 // verify that regions in irreducible loops are marked is_in_irreducible_loop
1127 void verify_regions_in_irreducible_loops();
1128 bool is_in_irreducible_loop(RegionNode* region);
1129 #endif
1130
1131 // Place Data nodes in some loop nest
1132 void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
1133 void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
1134 void build_loop_late_post_work(Node* n, bool pinned);
1135 void build_loop_late_post(Node* n);
1136 void verify_strip_mined_scheduling(Node *n, Node* least);
1137
1138 // Array of immediate dominance info for each CFG node indexed by node idx
1139 private:
1140 uint _idom_size;
1141 Node **_idom; // Array of immediate dominators
1142 uint *_dom_depth; // Used for fast LCA test
1143 GrowableArray<uint>* _dom_stk; // For recomputation of dom depth
1144 LoopOptsMode _mode;
1145
1146 // build the loop tree and perform any requested optimizations
1147 void build_and_optimize();
1148
1149 // Dominators for the sea of nodes
1150 void Dominators();
1151
1152 // Compute the Ideal Node to Loop mapping
1153 PhaseIdealLoop(PhaseIterGVN& igvn, LoopOptsMode mode) :
1154 PhaseTransform(Ideal_Loop),
1155 _loop_or_ctrl(igvn.C->comp_arena()),
1156 _igvn(igvn),
1157 _verify_me(nullptr),
1158 _verify_only(false),
1159 _mode(mode),
1160 _nodes_required(UINT_MAX) {
1161 assert(mode != LoopOptsVerify, "wrong constructor to verify IdealLoop");
1162 build_and_optimize();
1163 }
1164
1165 #ifndef PRODUCT
1166 // Verify that verify_me made the same decisions as a fresh run
1167 // or only verify that the graph is valid if verify_me is null.
1168 PhaseIdealLoop(PhaseIterGVN& igvn, const PhaseIdealLoop* verify_me = nullptr) :
1169 PhaseTransform(Ideal_Loop),
1170 _loop_or_ctrl(igvn.C->comp_arena()),
1171 _igvn(igvn),
1172 _verify_me(verify_me),
1173 _verify_only(verify_me == nullptr),
1174 _mode(LoopOptsVerify),
1175 _nodes_required(UINT_MAX) {
1176 DEBUG_ONLY(C->set_phase_verify_ideal_loop();)
1177 build_and_optimize();
1178 DEBUG_ONLY(C->reset_phase_verify_ideal_loop();)
1179 }
1180 #endif
1181
1182 Node* insert_convert_node_if_needed(BasicType target, Node* input);
1183
1184 public:
1185 Node* idom_no_update(Node* d) const {
1186 return idom_no_update(d->_idx);
1187 }
1188
1189 Node* idom_no_update(uint didx) const {
1190 assert(didx < _idom_size, "oob");
1191 Node* n = _idom[didx];
1192 assert(n != nullptr,"Bad immediate dominator info.");
1193 while (n->in(0) == nullptr) { // Skip dead CFG nodes
1194 n = (Node*)(((intptr_t)_loop_or_ctrl[n->_idx]) & ~1);
1195 assert(n != nullptr,"Bad immediate dominator info.");
1196 }
1197 return n;
1198 }
1199
1200 Node *idom(Node* d) const {
1201 return idom(d->_idx);
1202 }
1203
1204 Node *idom(uint didx) const {
1205 Node *n = idom_no_update(didx);
1206 _idom[didx] = n; // Lazily remove dead CFG nodes from table.
1207 return n;
1208 }
1209
1210 uint dom_depth(Node* d) const {
1211 guarantee(d != nullptr, "Null dominator info.");
1212 guarantee(d->_idx < _idom_size, "");
1213 return _dom_depth[d->_idx];
1214 }
1215 void set_idom(Node* d, Node* n, uint dom_depth);
1216 // Locally compute IDOM using dom_lca call
1217 Node *compute_idom( Node *region ) const;
1218 // Recompute dom_depth
1219 void recompute_dom_depth();
1220
1221 // Is safept not required by an outer loop?
1222 bool is_deleteable_safept(Node* sfpt);
1223
1224 // Replace parallel induction variable (parallel to trip counter)
1225 void replace_parallel_iv(IdealLoopTree *loop);
1226
1227 Node *dom_lca( Node *n1, Node *n2 ) const {
1228 return find_non_split_ctrl(dom_lca_internal(n1, n2));
1229 }
1230 Node *dom_lca_internal( Node *n1, Node *n2 ) const;
1231
1232 Node* dominated_node(Node* c1, Node* c2) {
1233 assert(is_dominator(c1, c2) || is_dominator(c2, c1), "nodes must be related");
1234 return is_dominator(c1, c2) ? c2 : c1;
1235 }
1236
1237 // Return control node that's dominated by the 2 others
1238 Node* dominated_node(Node* c1, Node* c2, Node* c3) {
1239 return dominated_node(c1, dominated_node(c2, c3));
1240 }
1241
1242 // Build and verify the loop tree without modifying the graph. This
1243 // is useful to verify that all inputs properly dominate their uses.
1244 static void verify(PhaseIterGVN& igvn) {
1245 #ifdef ASSERT
1246 ResourceMark rm;
1247 Compile::TracePhase tp(_t_idealLoopVerify);
1248 PhaseIdealLoop v(igvn);
1249 #endif
1250 }
1251
1252 // Recommended way to use PhaseIdealLoop.
1253 // Run PhaseIdealLoop in some mode and allocates a local scope for memory allocations.
1254 static void optimize(PhaseIterGVN &igvn, LoopOptsMode mode) {
1255 ResourceMark rm;
1256 PhaseIdealLoop v(igvn, mode);
1257
1258 Compile* C = Compile::current();
1259 if (!C->failing()) {
1260 // Cleanup any modified bits
1261 igvn.optimize();
1262 if (C->failing()) { return; }
1263 v.log_loop_tree();
1264 }
1265 }
1266
1267 // True if the method has at least 1 irreducible loop
1268 bool _has_irreducible_loops;
1269
1270 // Per-Node transform
1271 virtual Node* transform(Node* n) { return nullptr; }
1272
1273 Node* loop_exit_control(Node* x, IdealLoopTree* loop);
1274 Node* loop_exit_test(Node* back_control, IdealLoopTree* loop, Node*& incr, Node*& limit, BoolTest::mask& bt, float& cl_prob);
1275 Node* loop_iv_incr(Node* incr, Node* x, IdealLoopTree* loop, Node*& phi_incr);
1276 Node* loop_iv_stride(Node* incr, IdealLoopTree* loop, Node*& xphi);
1277 PhiNode* loop_iv_phi(Node* xphi, Node* phi_incr, Node* x, IdealLoopTree* loop);
1278
1279 bool is_counted_loop(Node* x, IdealLoopTree*&loop, BasicType iv_bt);
1280
1281 Node* loop_nest_replace_iv(Node* iv_to_replace, Node* inner_iv, Node* outer_phi, Node* inner_head, BasicType bt);
1282 bool create_loop_nest(IdealLoopTree* loop, Node_List &old_new);
1283 #ifdef ASSERT
1284 bool convert_to_long_loop(Node* cmp, Node* phi, IdealLoopTree* loop);
1285 #endif
1286 void add_parse_predicate(Deoptimization::DeoptReason reason, Node* inner_head, IdealLoopTree* loop, SafePointNode* sfpt);
1287 SafePointNode* find_safepoint(Node* back_control, Node* x, IdealLoopTree* loop);
1288 IdealLoopTree* insert_outer_loop(IdealLoopTree* loop, LoopNode* outer_l, Node* outer_ift);
1289 IdealLoopTree* create_outer_strip_mined_loop(BoolNode *test, Node *cmp, Node *init_control,
1290 IdealLoopTree* loop, float cl_prob, float le_fcnt,
1291 Node*& entry_control, Node*& iffalse);
1292
1293 Node* exact_limit( IdealLoopTree *loop );
1294
1295 // Return a post-walked LoopNode
1296 IdealLoopTree *get_loop( Node *n ) const {
1297 // Dead nodes have no loop, so return the top level loop instead
1298 if (!has_node(n)) return _ltree_root;
1299 assert(!has_ctrl(n), "");
1300 return (IdealLoopTree*)_loop_or_ctrl[n->_idx];
1301 }
1302
1303 IdealLoopTree* ltree_root() const { return _ltree_root; }
1304
1305 // Is 'n' a (nested) member of 'loop'?
1306 int is_member( const IdealLoopTree *loop, Node *n ) const {
1307 return loop->is_member(get_loop(n)); }
1308
1309 // This is the basic building block of the loop optimizations. It clones an
1310 // entire loop body. It makes an old_new loop body mapping; with this
1311 // mapping you can find the new-loop equivalent to an old-loop node. All
1312 // new-loop nodes are exactly equal to their old-loop counterparts, all
1313 // edges are the same. All exits from the old-loop now have a RegionNode
1314 // that merges the equivalent new-loop path. This is true even for the
1315 // normal "loop-exit" condition. All uses of loop-invariant old-loop values
1316 // now come from (one or more) Phis that merge their new-loop equivalents.
1317 // Parameter side_by_side_idom:
1318 // When side_by_size_idom is null, the dominator tree is constructed for
1319 // the clone loop to dominate the original. Used in construction of
1320 // pre-main-post loop sequence.
1321 // When nonnull, the clone and original are side-by-side, both are
1322 // dominated by the passed in side_by_side_idom node. Used in
1323 // construction of unswitched loops.
1324 enum CloneLoopMode {
1325 IgnoreStripMined = 0, // Only clone inner strip mined loop
1326 CloneIncludesStripMined = 1, // clone both inner and outer strip mined loops
1327 ControlAroundStripMined = 2 // Only clone inner strip mined loop,
1328 // result control flow branches
1329 // either to inner clone or outer
1330 // strip mined loop.
1331 };
1332 void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth,
1333 CloneLoopMode mode, Node* side_by_side_idom = nullptr);
1334 void clone_loop_handle_data_uses(Node* old, Node_List &old_new,
1335 IdealLoopTree* loop, IdealLoopTree* companion_loop,
1336 Node_List*& split_if_set, Node_List*& split_bool_set,
1337 Node_List*& split_cex_set, Node_List& worklist,
1338 uint new_counter, CloneLoopMode mode);
1339 void clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
1340 IdealLoopTree* outer_loop, int dd, Node_List &old_new,
1341 Node_List& extra_data_nodes);
1342
1343 // If we got the effect of peeling, either by actually peeling or by
1344 // making a pre-loop which must execute at least once, we can remove
1345 // all loop-invariant dominated tests in the main body.
1346 void peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new );
1347
1348 // Generate code to do a loop peel for the given loop (and body).
1349 // old_new is a temp array.
1350 void do_peeling( IdealLoopTree *loop, Node_List &old_new );
1351
1352 // Add pre and post loops around the given loop. These loops are used
1353 // during RCE, unrolling and aligning loops.
1354 void insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only );
1355
1356 // Add post loop after the given loop.
1357 Node *insert_post_loop(IdealLoopTree* loop, Node_List& old_new,
1358 CountedLoopNode* main_head, CountedLoopEndNode* main_end,
1359 Node* incr, Node* limit, CountedLoopNode*& post_head);
1360
1361 // Add a vector post loop between a vector main loop and the current post loop
1362 void insert_vector_post_loop(IdealLoopTree *loop, Node_List &old_new);
1363 // If Node n lives in the back_ctrl block, we clone a private version of n
1364 // in preheader_ctrl block and return that, otherwise return n.
1365 Node *clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones );
1366
1367 // Take steps to maximally unroll the loop. Peel any odd iterations, then
1368 // unroll to do double iterations. The next round of major loop transforms
1369 // will repeat till the doubled loop body does all remaining iterations in 1
1370 // pass.
1371 void do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new );
1372
1373 // Unroll the loop body one step - make each trip do 2 iterations.
1374 void do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip );
1375
1376 // Return true if exp is a constant times an induction var
1377 bool is_scaled_iv(Node* exp, Node* iv, BasicType bt, jlong* p_scale, bool* p_short_scale, int depth = 0);
1378
1379 bool is_iv(Node* exp, Node* iv, BasicType bt);
1380
1381 // Return true if exp is a scaled induction var plus (or minus) constant
1382 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);
1383 bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset) {
1384 jlong long_scale;
1385 if (is_scaled_iv_plus_offset(exp, iv, T_INT, &long_scale, p_offset)) {
1386 int int_scale = checked_cast<int>(long_scale);
1387 if (p_scale != nullptr) {
1388 *p_scale = int_scale;
1389 }
1390 return true;
1391 }
1392 return false;
1393 }
1394 // Helper for finding more complex matches to is_scaled_iv_plus_offset.
1395 bool is_scaled_iv_plus_extra_offset(Node* exp1, Node* offset2, Node* iv,
1396 BasicType bt,
1397 jlong* p_scale, Node** p_offset,
1398 bool* p_short_scale, int depth);
1399
1400 // Create a new if above the uncommon_trap_if_pattern for the predicate to be promoted
1401 IfTrueNode* create_new_if_for_predicate(const ParsePredicateSuccessProj* parse_predicate_proj, Node* new_entry,
1402 Deoptimization::DeoptReason reason, int opcode,
1403 bool rewire_uncommon_proj_phi_inputs = false);
1404
1405 private:
1406 // Helper functions for create_new_if_for_predicate()
1407 void set_ctrl_of_nodes_with_same_ctrl(Node* start_node, ProjNode* old_uncommon_proj, Node* new_uncommon_proj);
1408 Unique_Node_List find_nodes_with_same_ctrl(Node* node, const ProjNode* ctrl);
1409 Node* clone_nodes_with_same_ctrl(Node* start_node, ProjNode* old_uncommon_proj, Node* new_uncommon_proj);
1410 void fix_cloned_data_node_controls(const ProjNode* orig, Node* new_uncommon_proj,
1411 const OrigToNewHashtable& orig_to_clone);
1412 bool has_dominating_loop_limit_check(Node* init_trip, Node* limit, jlong stride_con, BasicType iv_bt,
1413 Node* loop_entry);
1414
1415 public:
1416 void register_control(Node* n, IdealLoopTree *loop, Node* pred, bool update_body = true);
1417
1418 // Replace the control input of 'node' with 'new_control' and set the dom depth to the one of 'new_control'.
1419 void replace_control(Node* node, Node* new_control) {
1420 _igvn.replace_input_of(node, 0, new_control);
1421 set_idom(node, new_control, dom_depth(new_control));
1422 }
1423
1424 void replace_loop_entry(LoopNode* loop_head, Node* new_entry) {
1425 _igvn.replace_input_of(loop_head, LoopNode::EntryControl, new_entry);
1426 set_idom(loop_head, new_entry, dom_depth(new_entry));
1427 }
1428
1429 // Construct a range check for a predicate if
1430 BoolNode* rc_predicate(Node* ctrl, int scale, Node* offset, Node* init, Node* limit,
1431 jint stride, Node* range, bool upper, bool& overflow);
1432
1433 // Implementation of the loop predication to promote checks outside the loop
1434 bool loop_predication_impl(IdealLoopTree *loop);
1435
1436 private:
1437 bool loop_predication_impl_helper(IdealLoopTree* loop, IfProjNode* if_success_proj,
1438 ParsePredicateSuccessProj* parse_predicate_proj, CountedLoopNode* cl, ConNode* zero,
1439 Invariance& invar, Deoptimization::DeoptReason deopt_reason);
1440 bool can_create_loop_predicates(const PredicateBlock* profiled_loop_predicate_block) const;
1441 bool loop_predication_should_follow_branches(IdealLoopTree* loop, float& loop_trip_cnt);
1442 void loop_predication_follow_branches(Node *c, IdealLoopTree *loop, float loop_trip_cnt,
1443 PathFrequency& pf, Node_Stack& stack, VectorSet& seen,
1444 Node_List& if_proj_list);
1445 IfTrueNode* create_template_assertion_predicate(CountedLoopNode* loop_head, ParsePredicateNode* parse_predicate,
1446 IfProjNode* new_control, int scale, Node* offset, Node* range);
1447 void eliminate_hoisted_range_check(IfTrueNode* hoisted_check_proj, IfTrueNode* template_assertion_predicate_proj);
1448
1449 // Helper function to collect predicate for eliminating the useless ones
1450 void eliminate_useless_predicates() const;
1451
1452 void eliminate_useless_zero_trip_guard();
1453 void eliminate_useless_multiversion_if();
1454
1455 public:
1456 // Change the control input of expensive nodes to allow commoning by
1457 // IGVN when it is guaranteed to not result in a more frequent
1458 // execution of the expensive node. Return true if progress.
1459 bool process_expensive_nodes();
1460
1461 // Check whether node has become unreachable
1462 bool is_node_unreachable(Node *n) const {
1463 return !has_node(n) || n->is_unreachable(_igvn);
1464 }
1465
1466 // Eliminate range-checks and other trip-counter vs loop-invariant tests.
1467 void do_range_check(IdealLoopTree* loop);
1468
1469 // Clone loop with an invariant test (that does not exit) and
1470 // insert a clone of the test that selects which version to
1471 // execute.
1472 void do_unswitching(IdealLoopTree* loop, Node_List& old_new);
1473
1474 IfNode* find_unswitch_candidate(const IdealLoopTree* loop) const;
1475
1476 private:
1477 static bool has_control_dependencies_from_predicates(LoopNode* head);
1478 static void revert_to_normal_loop(const LoopNode* loop_head);
1479
1480 void hoist_invariant_check_casts(const IdealLoopTree* loop, const Node_List& old_new,
1481 const UnswitchedLoopSelector& unswitched_loop_selector);
1482 void add_unswitched_loop_version_bodies_to_igvn(IdealLoopTree* loop, const Node_List& old_new);
1483 static void increment_unswitch_counts(LoopNode* original_head, LoopNode* new_head);
1484 void remove_unswitch_candidate_from_loops(const Node_List& old_new, const UnswitchedLoopSelector& unswitched_loop_selector);
1485 #ifndef PRODUCT
1486 static void trace_loop_unswitching_count(IdealLoopTree* loop, LoopNode* original_head);
1487 static void trace_loop_unswitching_impossible(const LoopNode* original_head);
1488 static void trace_loop_unswitching_result(const UnswitchedLoopSelector& unswitched_loop_selector,
1489 const LoopNode* original_head, const LoopNode* new_head);
1490 static void trace_loop_multiversioning_result(const LoopSelector& loop_selector,
1491 const LoopNode* original_head, const LoopNode* new_head);
1492 #endif
1493
1494 public:
1495
1496 // Range Check Elimination uses this function!
1497 // Constrain the main loop iterations so the affine function:
1498 // low_limit <= scale_con * I + offset < upper_limit
1499 // always holds true. That is, either increase the number of iterations in
1500 // the pre-loop or the post-loop until the condition holds true in the main
1501 // loop. Scale_con, offset and limit are all loop invariant.
1502 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);
1503 // Helper function for add_constraint().
1504 Node* adjust_limit(bool reduce, Node* scale, Node* offset, Node* rc_limit, Node* old_limit, Node* pre_ctrl, bool round);
1505
1506 // Partially peel loop up through last_peel node.
1507 bool partial_peel( IdealLoopTree *loop, Node_List &old_new );
1508 bool duplicate_loop_backedge(IdealLoopTree *loop, Node_List &old_new);
1509
1510 // AutoVectorize the loop: replace scalar ops with vector ops.
1511 enum AutoVectorizeStatus {
1512 Impossible, // This loop has the wrong shape to even try vectorization.
1513 Success, // We just successfully vectorized the loop.
1514 TriedAndFailed, // We tried to vectorize, but failed.
1515 };
1516 AutoVectorizeStatus auto_vectorize(IdealLoopTree* lpt, VSharedData &vshared);
1517
1518 void maybe_multiversion_for_auto_vectorization_runtime_checks(IdealLoopTree* lpt, Node_List& old_new);
1519 void do_multiversioning(IdealLoopTree* lpt, Node_List& old_new);
1520 IfTrueNode* create_new_if_for_multiversion(IfTrueNode* multiversioning_fast_proj);
1521 bool try_resume_optimizations_for_delayed_slow_loop(IdealLoopTree* lpt);
1522
1523 // Move an unordered Reduction out of loop if possible
1524 void move_unordered_reduction_out_of_loop(IdealLoopTree* loop);
1525
1526 // Create a scheduled list of nodes control dependent on ctrl set.
1527 void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched );
1528 // Has a use in the vector set
1529 bool has_use_in_set( Node* n, VectorSet& vset );
1530 // Has use internal to the vector set (ie. not in a phi at the loop head)
1531 bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop );
1532 // clone "n" for uses that are outside of loop
1533 int clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist );
1534 // clone "n" for special uses that are in the not_peeled region
1535 void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
1536 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist );
1537 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
1538 void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp );
1539 #ifdef ASSERT
1540 // Validate the loop partition sets: peel and not_peel
1541 bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel );
1542 // Ensure that uses outside of loop are of the right form
1543 bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
1544 uint orig_exit_idx, uint clone_exit_idx);
1545 bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx);
1546 #endif
1547
1548 // Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.)
1549 int stride_of_possible_iv( Node* iff );
1550 bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; }
1551 // Return the (unique) control output node that's in the loop (if it exists.)
1552 Node* stay_in_loop( Node* n, IdealLoopTree *loop);
1553 // Insert a signed compare loop exit cloned from an unsigned compare.
1554 IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop);
1555 void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop);
1556 // Utility to register node "n" with PhaseIdealLoop
1557 void register_node(Node* n, IdealLoopTree* loop, Node* pred, uint ddepth);
1558 // Utility to create an if-projection
1559 ProjNode* proj_clone(ProjNode* p, IfNode* iff);
1560 // Force the iff control output to be the live_proj
1561 Node* short_circuit_if(IfNode* iff, ProjNode* live_proj);
1562 // Insert a region before an if projection
1563 RegionNode* insert_region_before_proj(ProjNode* proj);
1564 // Insert a new if before an if projection
1565 ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj);
1566
1567 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1568 // "Nearly" because all Nodes have been cloned from the original in the loop,
1569 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1570 // through the Phi recursively, and return a Bool.
1571 Node* clone_iff(PhiNode* phi);
1572 CmpNode* clone_bool(PhiNode* phi);
1573
1574
1575 // Rework addressing expressions to get the most loop-invariant stuff
1576 // moved out. We'd like to do all associative operators, but it's especially
1577 // important (common) to do address expressions.
1578 Node* remix_address_expressions(Node* n);
1579 Node* remix_address_expressions_add_left_shift(Node* n, IdealLoopTree* n_loop, Node* n_ctrl, BasicType bt);
1580
1581 // Convert add to muladd to generate MuladdS2I under certain criteria
1582 Node * convert_add_to_muladd(Node * n);
1583
1584 // Attempt to use a conditional move instead of a phi/branch
1585 Node *conditional_move( Node *n );
1586
1587 // Check for aggressive application of 'split-if' optimization,
1588 // using basic block level info.
1589 void split_if_with_blocks ( VectorSet &visited, Node_Stack &nstack);
1590 Node *split_if_with_blocks_pre ( Node *n );
1591 void split_if_with_blocks_post( Node *n );
1592 Node *has_local_phi_input( Node *n );
1593 // Mark an IfNode as being dominated by a prior test,
1594 // without actually altering the CFG (and hence IDOM info).
1595 void dominated_by(IfProjNode* prevdom, IfNode* iff, bool flip = false, bool pin_array_access_nodes = false);
1596 void rewire_safe_outputs_to_dominator(Node* source, Node* dominator, bool pin_array_access_nodes);
1597
1598 // Split Node 'n' through merge point
1599 RegionNode* split_thru_region(Node* n, RegionNode* region);
1600 // Split Node 'n' through merge point if there is enough win.
1601 Node *split_thru_phi( Node *n, Node *region, int policy );
1602 // Found an If getting its condition-code input from a Phi in the
1603 // same block. Split thru the Region.
1604 void do_split_if(Node *iff, RegionNode** new_false_region = nullptr, RegionNode** new_true_region = nullptr);
1605
1606 // Conversion of fill/copy patterns into intrinsic versions
1607 bool do_intrinsify_fill();
1608 bool intrinsify_fill(IdealLoopTree* lpt);
1609 bool match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value,
1610 Node*& shift, Node*& offset);
1611
1612 private:
1613 // Return a type based on condition control flow
1614 const TypeInt* filtered_type( Node *n, Node* n_ctrl);
1615 const TypeInt* filtered_type( Node *n ) { return filtered_type(n, nullptr); }
1616 // Helpers for filtered type
1617 const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl);
1618
1619 // Helper functions
1620 Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache );
1621 Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true );
1622 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 );
1623 bool split_up( Node *n, Node *blk1, Node *blk2 );
1624
1625 Node* place_outside_loop(Node* useblock, IdealLoopTree* loop) const;
1626 Node* try_move_store_before_loop(Node* n, Node *n_ctrl);
1627 void try_move_store_after_loop(Node* n);
1628 bool identical_backtoback_ifs(Node *n);
1629 bool can_split_if(Node *n_ctrl);
1630 bool cannot_split_division(const Node* n, const Node* region) const;
1631 static bool is_divisor_loop_phi(const Node* divisor, const Node* loop);
1632 bool loop_phi_backedge_type_contains_zero(const Node* phi_divisor, const Type* zero) const;
1633
1634 // Determine if a method is too big for a/another round of split-if, based on
1635 // a magic (approximate) ratio derived from the equally magic constant 35000,
1636 // previously used for this purpose (but without relating to the node limit).
1637 bool must_throttle_split_if() {
1638 uint threshold = C->max_node_limit() * 2 / 5;
1639 return C->live_nodes() > threshold;
1640 }
1641
1642 // A simplistic node request tracking mechanism, where
1643 // = UINT_MAX Request not valid or made final.
1644 // < UINT_MAX Nodes currently requested (estimate).
1645 uint _nodes_required;
1646
1647 enum { REQUIRE_MIN = 70 };
1648
1649 uint nodes_required() const { return _nodes_required; }
1650
1651 // Given the _currently_ available number of nodes, check whether there is
1652 // "room" for an additional request or not, considering the already required
1653 // number of nodes. Return TRUE if the new request is exceeding the node
1654 // budget limit, otherwise return FALSE. Note that this interpretation will
1655 // act pessimistic on additional requests when new nodes have already been
1656 // generated since the 'begin'. This behaviour fits with the intention that
1657 // node estimates/requests should be made upfront.
1658 bool exceeding_node_budget(uint required = 0) {
1659 assert(C->live_nodes() < C->max_node_limit(), "sanity");
1660 uint available = C->max_node_limit() - C->live_nodes();
1661 return available < required + _nodes_required + REQUIRE_MIN;
1662 }
1663
1664 uint require_nodes(uint require, uint minreq = REQUIRE_MIN) {
1665 precond(require > 0);
1666 _nodes_required += MAX2(require, minreq);
1667 return _nodes_required;
1668 }
1669
1670 bool may_require_nodes(uint require, uint minreq = REQUIRE_MIN) {
1671 return !exceeding_node_budget(require) && require_nodes(require, minreq) > 0;
1672 }
1673
1674 uint require_nodes_begin() {
1675 assert(_nodes_required == UINT_MAX, "Bad state (begin).");
1676 _nodes_required = 0;
1677 return C->live_nodes();
1678 }
1679
1680 // When a node request is final, optionally check that the requested number
1681 // of nodes was reasonably correct with respect to the number of new nodes
1682 // introduced since the last 'begin'. Always check that we have not exceeded
1683 // the maximum node limit.
1684 void require_nodes_final(uint live_at_begin, bool check_estimate) {
1685 assert(_nodes_required < UINT_MAX, "Bad state (final).");
1686
1687 #ifdef ASSERT
1688 if (check_estimate) {
1689 // Check that the node budget request was not off by too much (x2).
1690 // Should this be the case we _surely_ need to improve the estimates
1691 // used in our budget calculations.
1692 if (C->live_nodes() - live_at_begin > 2 * _nodes_required) {
1693 log_info(compilation)("Bad node estimate: actual = %d >> request = %d",
1694 C->live_nodes() - live_at_begin, _nodes_required);
1695 }
1696 }
1697 #endif
1698 // Assert that we have stayed within the node budget limit.
1699 assert(C->live_nodes() < C->max_node_limit(),
1700 "Exceeding node budget limit: %d + %d > %d (request = %d)",
1701 C->live_nodes() - live_at_begin, live_at_begin,
1702 C->max_node_limit(), _nodes_required);
1703
1704 _nodes_required = UINT_MAX;
1705 }
1706
1707 private:
1708
1709 bool _created_loop_node;
1710 DEBUG_ONLY(void dump_idoms(Node* early, Node* wrong_lca);)
1711 NOT_PRODUCT(void dump_idoms_in_reverse(const Node* n, const Node_List& idom_list) const;)
1712
1713 public:
1714 void set_created_loop_node() { _created_loop_node = true; }
1715 bool created_loop_node() { return _created_loop_node; }
1716 void register_new_node(Node* n, Node* blk);
1717 void register_new_node_with_ctrl_of(Node* new_node, Node* ctrl_of) {
1718 register_new_node(new_node, get_ctrl(ctrl_of));
1719 }
1720
1721 Node* clone_and_register(Node* n, Node* ctrl) {
1722 n = n->clone();
1723 register_new_node(n, ctrl);
1724 return n;
1725 }
1726
1727 #ifdef ASSERT
1728 void dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA);
1729 #endif
1730
1731 #ifndef PRODUCT
1732 void dump() const;
1733 void dump_idom(Node* n) const { dump_idom(n, 1000); } // For debugging
1734 void dump_idom(Node* n, uint count) const;
1735 void get_idoms(Node* n, uint count, Unique_Node_List& idoms) const;
1736 void dump(IdealLoopTree* loop, uint rpo_idx, Node_List &rpo_list) const;
1737 IdealLoopTree* get_loop_idx(Node* n) const {
1738 // Dead nodes have no loop, so return the top level loop instead
1739 return _loop_or_ctrl[n->_idx] ? (IdealLoopTree*)_loop_or_ctrl[n->_idx] : _ltree_root;
1740 }
1741 // Print some stats
1742 static void print_statistics();
1743 static int _loop_invokes; // Count of PhaseIdealLoop invokes
1744 static int _loop_work; // Sum of PhaseIdealLoop x _unique
1745 static volatile int _long_loop_candidates;
1746 static volatile int _long_loop_nests;
1747 static volatile int _long_loop_counted_loops;
1748 #endif
1749
1750 #ifdef ASSERT
1751 void verify() const;
1752 bool verify_idom_and_nodes(Node* root, const PhaseIdealLoop* phase_verify) const;
1753 bool verify_idom(Node* n, const PhaseIdealLoop* phase_verify) const;
1754 bool verify_loop_ctrl(Node* n, const PhaseIdealLoop* phase_verify) const;
1755 #endif
1756
1757 void rpo(Node* start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list) const;
1758
1759 void check_counted_loop_shape(IdealLoopTree* loop, Node* x, BasicType bt) NOT_DEBUG_RETURN;
1760
1761 LoopNode* create_inner_head(IdealLoopTree* loop, BaseCountedLoopNode* head, IfNode* exit_test);
1762
1763
1764 int extract_long_range_checks(const IdealLoopTree* loop, jint stride_con, int iters_limit, PhiNode* phi,
1765 Node_List &range_checks);
1766
1767 void transform_long_range_checks(int stride_con, const Node_List &range_checks, Node* outer_phi,
1768 Node* inner_iters_actual_int, Node* inner_phi,
1769 Node* iv_add, LoopNode* inner_head);
1770
1771 Node* get_late_ctrl_with_anti_dep(LoadNode* n, Node* early, Node* LCA);
1772
1773 bool ctrl_of_use_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop, Node* ctrl);
1774
1775 bool ctrl_of_all_uses_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop);
1776
1777 Node* compute_early_ctrl(Node* n, Node* n_ctrl);
1778
1779 void try_sink_out_of_loop(Node* n);
1780
1781 Node* clamp(Node* R, Node* L, Node* H);
1782
1783 bool safe_for_if_replacement(const Node* dom) const;
1784
1785 void push_pinned_nodes_thru_region(IfNode* dom_if, Node* region);
1786
1787 bool try_merge_identical_ifs(Node* n);
1788
1789 void clone_loop_body(const Node_List& body, Node_List &old_new, CloneMap* cm);
1790
1791 void fix_body_edges(const Node_List &body, IdealLoopTree* loop, const Node_List &old_new, int dd,
1792 IdealLoopTree* parent, bool partial);
1793
1794 void fix_ctrl_uses(const Node_List& body, const IdealLoopTree* loop, Node_List &old_new, CloneLoopMode mode,
1795 Node* side_by_side_idom, CloneMap* cm, Node_List &worklist);
1796
1797 void fix_data_uses(Node_List& body, IdealLoopTree* loop, CloneLoopMode mode, IdealLoopTree* outer_loop,
1798 uint new_counter, Node_List& old_new, Node_List& worklist, Node_List*& split_if_set,
1799 Node_List*& split_bool_set, Node_List*& split_cex_set);
1800
1801 void finish_clone_loop(Node_List* split_if_set, Node_List* split_bool_set, Node_List* split_cex_set);
1802
1803 bool at_relevant_ctrl(Node* n, const Node* blk1, const Node* blk2);
1804
1805 bool clone_cmp_loadklass_down(Node* n, const Node* blk1, const Node* blk2);
1806 void clone_loadklass_nodes_at_cmp_index(const Node* n, Node* cmp, int i);
1807 bool clone_cmp_down(Node* n, const Node* blk1, const Node* blk2);
1808 void clone_template_assertion_expression_down(Node* node);
1809
1810 Node* similar_subtype_check(const Node* x, Node* r_in);
1811
1812 void update_addp_chain_base(Node* x, Node* old_base, Node* new_base);
1813
1814 bool can_move_to_inner_loop(Node* n, LoopNode* n_loop, Node* x);
1815
1816 void pin_array_access_nodes_dependent_on(Node* ctrl);
1817
1818 Node* ensure_node_and_inputs_are_above_pre_end(CountedLoopEndNode* pre_end, Node* node);
1819
1820 ConINode* intcon(jint i);
1821
1822 ConLNode* longcon(jlong i);
1823
1824 ConNode* makecon(const Type* t);
1825
1826 ConNode* integercon(jlong l, BasicType bt);
1827
1828 ConNode* zerocon(BasicType bt);
1829 };
1830
1831
1832 class AutoNodeBudget : public StackObj
1833 {
1834 public:
1835 enum budget_check_t { BUDGET_CHECK, NO_BUDGET_CHECK };
1836
1837 AutoNodeBudget(PhaseIdealLoop* phase, budget_check_t chk = BUDGET_CHECK)
1838 : _phase(phase),
1839 _check_at_final(chk == BUDGET_CHECK),
1840 _nodes_at_begin(0)
1841 {
1842 precond(_phase != nullptr);
1843
1844 _nodes_at_begin = _phase->require_nodes_begin();
1845 }
1846
1847 ~AutoNodeBudget() {
1848 #ifndef PRODUCT
1849 if (TraceLoopOpts) {
1850 uint request = _phase->nodes_required();
1851 uint delta = _phase->C->live_nodes() - _nodes_at_begin;
1852
1853 if (request < delta) {
1854 tty->print_cr("Exceeding node budget: %d < %d", request, delta);
1855 } else {
1856 uint const REQUIRE_MIN = PhaseIdealLoop::REQUIRE_MIN;
1857 // Identify the worst estimates as "poor" ones.
1858 if (request > REQUIRE_MIN && delta > 0) {
1859 if ((delta > REQUIRE_MIN && request > 3 * delta) ||
1860 (delta <= REQUIRE_MIN && request > 10 * delta)) {
1861 tty->print_cr("Poor node estimate: %d >> %d", request, delta);
1862 }
1863 }
1864 }
1865 }
1866 #endif // PRODUCT
1867 _phase->require_nodes_final(_nodes_at_begin, _check_at_final);
1868 }
1869
1870 private:
1871 PhaseIdealLoop* _phase;
1872 bool _check_at_final;
1873 uint _nodes_at_begin;
1874 };
1875
1876 inline Node* IdealLoopTree::tail() {
1877 // Handle lazy update of _tail field.
1878 if (_tail->in(0) == nullptr) {
1879 _tail = _phase->get_ctrl(_tail);
1880 }
1881 return _tail;
1882 }
1883
1884 inline Node* IdealLoopTree::head() {
1885 // Handle lazy update of _head field.
1886 if (_head->in(0) == nullptr) {
1887 _head = _phase->get_ctrl(_head);
1888 }
1889 return _head;
1890 }
1891
1892 // Iterate over the loop tree using a preorder, left-to-right traversal.
1893 //
1894 // Example that visits all counted loops from within PhaseIdealLoop
1895 //
1896 // for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
1897 // IdealLoopTree* lpt = iter.current();
1898 // if (!lpt->is_counted()) continue;
1899 // ...
1900 class LoopTreeIterator : public StackObj {
1901 private:
1902 IdealLoopTree* _root;
1903 IdealLoopTree* _curnt;
1904
1905 public:
1906 LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {}
1907
1908 bool done() { return _curnt == nullptr; } // Finished iterating?
1909
1910 void next(); // Advance to next loop tree
1911
1912 IdealLoopTree* current() { return _curnt; } // Return current value of iterator.
1913 };
1914
1915 // Compute probability of reaching some CFG node from a fixed
1916 // dominating CFG node
1917 class PathFrequency {
1918 private:
1919 Node* _dom; // frequencies are computed relative to this node
1920 Node_Stack _stack;
1921 GrowableArray<float> _freqs_stack; // keep track of intermediate result at regions
1922 GrowableArray<float> _freqs; // cache frequencies
1923 PhaseIdealLoop* _phase;
1924
1925 float check_and_truncate_frequency(float f) {
1926 assert(f >= 0, "Incorrect frequency");
1927 // We do not perform an exact (f <= 1) check
1928 // this would be error prone with rounding of floats.
1929 // Performing a check like (f <= 1+eps) would be of benefit,
1930 // however, it is not evident how to determine such an eps,
1931 // given that an arbitrary number of add/mul operations
1932 // are performed on these frequencies.
1933 return (f > 1) ? 1 : f;
1934 }
1935
1936 public:
1937 PathFrequency(Node* dom, PhaseIdealLoop* phase)
1938 : _dom(dom), _stack(0), _phase(phase) {
1939 }
1940
1941 float to(Node* n);
1942 };
1943
1944 // Class to clone a data node graph by taking a list of data nodes. This is done in 2 steps:
1945 // 1. Clone the data nodes
1946 // 2. Fix the cloned data inputs pointing to the old nodes to the cloned inputs by using an old->new mapping.
1947 class DataNodeGraph : public StackObj {
1948 PhaseIdealLoop* const _phase;
1949 const Unique_Node_List& _data_nodes;
1950 OrigToNewHashtable _orig_to_new;
1951
1952 public:
1953 DataNodeGraph(const Unique_Node_List& data_nodes, PhaseIdealLoop* phase)
1954 : _phase(phase),
1955 _data_nodes(data_nodes),
1956 // Use 107 as best guess which is the first resize value in ResizeableResourceHashtable::large_table_sizes.
1957 _orig_to_new(107, MaxNodeLimit)
1958 {
1959 #ifdef ASSERT
1960 for (uint i = 0; i < data_nodes.size(); i++) {
1961 assert(!data_nodes[i]->is_CFG(), "only data nodes");
1962 }
1963 #endif
1964 }
1965 NONCOPYABLE(DataNodeGraph);
1966
1967 private:
1968 void clone(Node* node, Node* new_ctrl);
1969 void clone_data_nodes(Node* new_ctrl);
1970 void clone_data_nodes_and_transform_opaque_loop_nodes(const TransformStrategyForOpaqueLoopNodes& transform_strategy,
1971 Node* new_ctrl);
1972 void rewire_clones_to_cloned_inputs();
1973 void transform_opaque_node(const TransformStrategyForOpaqueLoopNodes& transform_strategy, Node* node);
1974
1975 public:
1976 // Clone the provided data node collection and rewire the clones in such a way to create an identical graph copy.
1977 // Set 'new_ctrl' as ctrl for the cloned nodes.
1978 const OrigToNewHashtable& clone(Node* new_ctrl) {
1979 assert(_orig_to_new.number_of_entries() == 0, "should not call this method twice in a row");
1980 clone_data_nodes(new_ctrl);
1981 rewire_clones_to_cloned_inputs();
1982 return _orig_to_new;
1983 }
1984
1985 // Create a copy of the data nodes provided to the constructor by doing the following:
1986 // Clone all non-OpaqueLoop* nodes and rewire them to create an identical subgraph copy. For the OpaqueLoop* nodes,
1987 // apply the provided transformation strategy and include the transformed node into the subgraph copy to get a complete
1988 // "cloned-and-transformed" graph copy. For all newly cloned nodes (which could also be new OpaqueLoop* nodes), set
1989 // `new_ctrl` as ctrl.
1990 const OrigToNewHashtable& clone_with_opaque_loop_transform_strategy(
1991 const TransformStrategyForOpaqueLoopNodes& transform_strategy,
1992 Node* new_ctrl) {
1993 clone_data_nodes_and_transform_opaque_loop_nodes(transform_strategy, new_ctrl);
1994 rewire_clones_to_cloned_inputs();
1995 return _orig_to_new;
1996 }
1997 };
1998 #endif // SHARE_OPTO_LOOPNODE_HPP