1 /*
2 * Copyright (c) 1998, 2023, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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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/subnode.hpp"
32 #include "opto/type.hpp"
33
34 class CmpNode;
35 class BaseCountedLoopEndNode;
36 class CountedLoopNode;
37 class IdealLoopTree;
38 class LoopNode;
39 class Node;
40 class OuterStripMinedLoopEndNode;
41 class ParsePredicates;
42 class PathFrequency;
43 class PhaseIdealLoop;
44 class CountedLoopReserveKit;
45 class VectorSet;
46 class Invariance;
47 struct small_cache;
48
49 //
50 // I D E A L I Z E D L O O P S
51 //
52 // Idealized loops are the set of loops I perform more interesting
53 // transformations on, beyond simple hoisting.
54
55 //------------------------------LoopNode---------------------------------------
56 // Simple loop header. Fall in path on left, loop-back path on right.
57 class LoopNode : public RegionNode {
58 // Size is bigger to hold the flags. However, the flags do not change
59 // the semantics so it does not appear in the hash & cmp functions.
60 virtual uint size_of() const { return sizeof(*this); }
61 protected:
62 uint _loop_flags;
63 // Names for flag bitfields
64 enum { Normal=0, Pre=1, Main=2, Post=3, PreMainPostFlagsMask=3,
65 MainHasNoPreLoop = 1<<2,
66 HasExactTripCount = 1<<3,
67 InnerLoop = 1<<4,
68 PartialPeelLoop = 1<<5,
69 PartialPeelFailed = 1<<6,
70 WasSlpAnalyzed = 1<<7,
71 PassedSlpAnalysis = 1<<8,
72 DoUnrollOnly = 1<<9,
73 VectorizedLoop = 1<<10,
74 HasAtomicPostLoop = 1<<11,
75 StripMined = 1<<12,
76 SubwordLoop = 1<<13,
77 ProfileTripFailed = 1<<14,
78 LoopNestInnerLoop = 1<<15,
79 LoopNestLongOuterLoop = 1<<16,
80 FlatArrays = 1<<17};
81 char _unswitch_count;
82 enum { _unswitch_max=3 };
83
84 // Expected trip count from profile data
85 float _profile_trip_cnt;
86
87 public:
88 // Names for edge indices
89 enum { Self=0, EntryControl, LoopBackControl };
90
91 bool is_inner_loop() const { return _loop_flags & InnerLoop; }
92 void set_inner_loop() { _loop_flags |= InnerLoop; }
93
94 bool is_vectorized_loop() const { return _loop_flags & VectorizedLoop; }
95 bool is_partial_peel_loop() const { return _loop_flags & PartialPeelLoop; }
96 void set_partial_peel_loop() { _loop_flags |= PartialPeelLoop; }
97 bool partial_peel_has_failed() const { return _loop_flags & PartialPeelFailed; }
98 bool is_strip_mined() const { return _loop_flags & StripMined; }
99 bool is_profile_trip_failed() const { return _loop_flags & ProfileTripFailed; }
100 bool is_subword_loop() const { return _loop_flags & SubwordLoop; }
101 bool is_loop_nest_inner_loop() const { return _loop_flags & LoopNestInnerLoop; }
102 bool is_loop_nest_outer_loop() const { return _loop_flags & LoopNestLongOuterLoop; }
103 bool is_flat_arrays() const { return _loop_flags & FlatArrays; }
104
105 void mark_partial_peel_failed() { _loop_flags |= PartialPeelFailed; }
106 void mark_was_slp() { _loop_flags |= WasSlpAnalyzed; }
107 void mark_passed_slp() { _loop_flags |= PassedSlpAnalysis; }
108 void mark_do_unroll_only() { _loop_flags |= DoUnrollOnly; }
109 void mark_loop_vectorized() { _loop_flags |= VectorizedLoop; }
110 void mark_has_atomic_post_loop() { _loop_flags |= HasAtomicPostLoop; }
111 void mark_strip_mined() { _loop_flags |= StripMined; }
112 void clear_strip_mined() { _loop_flags &= ~StripMined; }
113 void mark_profile_trip_failed() { _loop_flags |= ProfileTripFailed; }
114 void mark_subword_loop() { _loop_flags |= SubwordLoop; }
115 void mark_loop_nest_inner_loop() { _loop_flags |= LoopNestInnerLoop; }
116 void mark_loop_nest_outer_loop() { _loop_flags |= LoopNestLongOuterLoop; }
117 void mark_flat_arrays() { _loop_flags |= FlatArrays; }
118
119 int unswitch_max() { return _unswitch_max; }
120 int unswitch_count() { return _unswitch_count; }
121
122 void set_unswitch_count(int val) {
123 assert (val <= unswitch_max(), "too many unswitches");
124 _unswitch_count = val;
125 }
126
127 void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; }
128 float profile_trip_cnt() { return _profile_trip_cnt; }
129
130 LoopNode(Node *entry, Node *backedge)
131 : RegionNode(3), _loop_flags(0), _unswitch_count(0),
132 _profile_trip_cnt(COUNT_UNKNOWN) {
133 init_class_id(Class_Loop);
134 init_req(EntryControl, entry);
135 init_req(LoopBackControl, backedge);
136 }
137
138 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
139 virtual int Opcode() const;
140 bool can_be_counted_loop(PhaseValues* phase) const {
141 return req() == 3 && in(0) != nullptr &&
142 in(1) != nullptr && phase->type(in(1)) != Type::TOP &&
143 in(2) != nullptr && phase->type(in(2)) != Type::TOP;
144 }
145 bool is_valid_counted_loop(BasicType bt) const;
146 #ifndef PRODUCT
147 virtual void dump_spec(outputStream *st) const;
148 #endif
149
150 void verify_strip_mined(int expect_skeleton) const NOT_DEBUG_RETURN;
151 virtual LoopNode* skip_strip_mined(int expect_skeleton = 1) { return this; }
152 virtual IfTrueNode* outer_loop_tail() const { ShouldNotReachHere(); return nullptr; }
153 virtual OuterStripMinedLoopEndNode* outer_loop_end() const { ShouldNotReachHere(); return nullptr; }
154 virtual IfFalseNode* outer_loop_exit() const { ShouldNotReachHere(); return nullptr; }
155 virtual SafePointNode* outer_safepoint() const { ShouldNotReachHere(); return nullptr; }
156 };
157
158 //------------------------------Counted Loops----------------------------------
159 // Counted loops are all trip-counted loops, with exactly 1 trip-counter exit
160 // path (and maybe some other exit paths). The trip-counter exit is always
161 // last in the loop. The trip-counter have to stride by a constant;
162 // the exit value is also loop invariant.
163
164 // CountedLoopNodes and CountedLoopEndNodes come in matched pairs. The
165 // CountedLoopNode has the incoming loop control and the loop-back-control
166 // which is always the IfTrue before the matching CountedLoopEndNode. The
167 // CountedLoopEndNode has an incoming control (possibly not the
168 // CountedLoopNode if there is control flow in the loop), the post-increment
169 // trip-counter value, and the limit. The trip-counter value is always of
170 // the form (Op old-trip-counter stride). The old-trip-counter is produced
171 // by a Phi connected to the CountedLoopNode. The stride is constant.
172 // The Op is any commutable opcode, including Add, Mul, Xor. The
173 // CountedLoopEndNode also takes in the loop-invariant limit value.
174
175 // From a CountedLoopNode I can reach the matching CountedLoopEndNode via the
176 // loop-back control. From CountedLoopEndNodes I can reach CountedLoopNodes
177 // via the old-trip-counter from the Op node.
178
179 //------------------------------CountedLoopNode--------------------------------
180 // CountedLoopNodes head simple counted loops. CountedLoopNodes have as
181 // inputs the incoming loop-start control and the loop-back control, so they
182 // act like RegionNodes. They also take in the initial trip counter, the
183 // loop-invariant stride and the loop-invariant limit value. CountedLoopNodes
184 // produce a loop-body control and the trip counter value. Since
185 // CountedLoopNodes behave like RegionNodes I still have a standard CFG model.
186
187 class BaseCountedLoopNode : public LoopNode {
188 public:
189 BaseCountedLoopNode(Node *entry, Node *backedge)
190 : LoopNode(entry, backedge) {
191 }
192
193 Node *init_control() const { return in(EntryControl); }
194 Node *back_control() const { return in(LoopBackControl); }
195
196 Node* init_trip() const;
197 Node* stride() const;
198 bool stride_is_con() const;
199 Node* limit() const;
200 Node* incr() const;
201 Node* phi() const;
202
203 BaseCountedLoopEndNode* loopexit_or_null() const;
204 BaseCountedLoopEndNode* loopexit() const;
205
206 virtual BasicType bt() const = 0;
207
208 jlong stride_con() const;
209
210 static BaseCountedLoopNode* make(Node* entry, Node* backedge, BasicType bt);
211 };
212
213
214 class CountedLoopNode : public BaseCountedLoopNode {
215 // Size is bigger to hold _main_idx. However, _main_idx does not change
216 // the semantics so it does not appear in the hash & cmp functions.
217 virtual uint size_of() const { return sizeof(*this); }
218
219 // For Pre- and Post-loops during debugging ONLY, this holds the index of
220 // the Main CountedLoop. Used to assert that we understand the graph shape.
221 node_idx_t _main_idx;
222
223 // Known trip count calculated by compute_exact_trip_count()
224 uint _trip_count;
225
226 // Log2 of original loop bodies in unrolled loop
227 int _unrolled_count_log2;
228
229 // Node count prior to last unrolling - used to decide if
230 // unroll,optimize,unroll,optimize,... is making progress
231 int _node_count_before_unroll;
232
233 // If slp analysis is performed we record the maximum
234 // vector mapped unroll factor here
235 int _slp_maximum_unroll_factor;
236
237 // The eventual count of vectorizable packs in slp
238 int _slp_vector_pack_count;
239
240 public:
241 CountedLoopNode(Node *entry, Node *backedge)
242 : BaseCountedLoopNode(entry, backedge), _main_idx(0), _trip_count(max_juint),
243 _unrolled_count_log2(0), _node_count_before_unroll(0),
244 _slp_maximum_unroll_factor(0), _slp_vector_pack_count(0) {
245 init_class_id(Class_CountedLoop);
246 // Initialize _trip_count to the largest possible value.
247 // Will be reset (lower) if the loop's trip count is known.
248 }
249
250 virtual int Opcode() const;
251 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
252
253 CountedLoopEndNode* loopexit_or_null() const { return (CountedLoopEndNode*) BaseCountedLoopNode::loopexit_or_null(); }
254 CountedLoopEndNode* loopexit() const { return (CountedLoopEndNode*) BaseCountedLoopNode::loopexit(); }
255 int stride_con() const;
256
257 // Match increment with optional truncation
258 static Node*
259 match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInteger** trunc_type,
260 BasicType bt);
261
262 // A 'main' loop has a pre-loop and a post-loop. The 'main' loop
263 // can run short a few iterations and may start a few iterations in.
264 // It will be RCE'd and unrolled and aligned.
265
266 // A following 'post' loop will run any remaining iterations. Used
267 // during Range Check Elimination, the 'post' loop will do any final
268 // iterations with full checks. Also used by Loop Unrolling, where
269 // the 'post' loop will do any epilog iterations needed. Basically,
270 // a 'post' loop can not profitably be further unrolled or RCE'd.
271
272 // A preceding 'pre' loop will run at least 1 iteration (to do peeling),
273 // it may do under-flow checks for RCE and may do alignment iterations
274 // so the following main loop 'knows' that it is striding down cache
275 // lines.
276
277 // A 'main' loop that is ONLY unrolled or peeled, never RCE'd or
278 // Aligned, may be missing it's pre-loop.
279 bool is_normal_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Normal; }
280 bool is_pre_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Pre; }
281 bool is_main_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Main; }
282 bool is_post_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Post; }
283 bool was_slp_analyzed () const { return (_loop_flags&WasSlpAnalyzed) == WasSlpAnalyzed; }
284 bool has_passed_slp () const { return (_loop_flags&PassedSlpAnalysis) == PassedSlpAnalysis; }
285 bool is_unroll_only () const { return (_loop_flags&DoUnrollOnly) == DoUnrollOnly; }
286 bool is_main_no_pre_loop() const { return _loop_flags & MainHasNoPreLoop; }
287 bool has_atomic_post_loop () const { return (_loop_flags & HasAtomicPostLoop) == HasAtomicPostLoop; }
288 void set_main_no_pre_loop() { _loop_flags |= MainHasNoPreLoop; }
289
290 int main_idx() const { return _main_idx; }
291
292
293 void set_pre_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; }
294 void set_main_loop ( ) { assert(is_normal_loop(),""); _loop_flags |= Main; }
295 void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; }
296 void set_normal_loop( ) { _loop_flags &= ~PreMainPostFlagsMask; }
297
298 void set_trip_count(uint tc) { _trip_count = tc; }
299 uint trip_count() { return _trip_count; }
300
301 bool has_exact_trip_count() const { return (_loop_flags & HasExactTripCount) != 0; }
302 void set_exact_trip_count(uint tc) {
303 _trip_count = tc;
304 _loop_flags |= HasExactTripCount;
305 }
306 void set_nonexact_trip_count() {
307 _loop_flags &= ~HasExactTripCount;
308 }
309 void set_notpassed_slp() {
310 _loop_flags &= ~PassedSlpAnalysis;
311 }
312
313 void double_unrolled_count() { _unrolled_count_log2++; }
314 int unrolled_count() { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); }
315
316 void set_node_count_before_unroll(int ct) { _node_count_before_unroll = ct; }
317 int node_count_before_unroll() { return _node_count_before_unroll; }
318 void set_slp_max_unroll(int unroll_factor) { _slp_maximum_unroll_factor = unroll_factor; }
319 int slp_max_unroll() const { return _slp_maximum_unroll_factor; }
320
321 virtual LoopNode* skip_strip_mined(int expect_skeleton = 1);
322 OuterStripMinedLoopNode* outer_loop() const;
323 virtual IfTrueNode* outer_loop_tail() const;
324 virtual OuterStripMinedLoopEndNode* outer_loop_end() const;
325 virtual IfFalseNode* outer_loop_exit() const;
326 virtual SafePointNode* outer_safepoint() const;
327
328 // If this is a main loop in a pre/main/post loop nest, walk over
329 // the predicates that were inserted by
330 // duplicate_predicates()/add_range_check_predicate()
331 static Node* skip_predicates_from_entry(Node* ctrl);
332 Node* skip_predicates();
333
334 virtual BasicType bt() const {
335 return T_INT;
336 }
337
338 Node* is_canonical_loop_entry();
339
340 #ifndef PRODUCT
341 virtual void dump_spec(outputStream *st) const;
342 #endif
343
344 static bool is_zero_trip_guard_if(const IfNode* iff);
345 };
346
347 class LongCountedLoopNode : public BaseCountedLoopNode {
348 public:
349 LongCountedLoopNode(Node *entry, Node *backedge)
350 : BaseCountedLoopNode(entry, backedge) {
351 init_class_id(Class_LongCountedLoop);
352 }
353
354 virtual int Opcode() const;
355
356 virtual BasicType bt() const {
357 return T_LONG;
358 }
359
360 LongCountedLoopEndNode* loopexit_or_null() const { return (LongCountedLoopEndNode*) BaseCountedLoopNode::loopexit_or_null(); }
361 LongCountedLoopEndNode* loopexit() const { return (LongCountedLoopEndNode*) BaseCountedLoopNode::loopexit(); }
362 };
363
364
365 //------------------------------CountedLoopEndNode-----------------------------
366 // CountedLoopEndNodes end simple trip counted loops. They act much like
367 // IfNodes.
368
369 class BaseCountedLoopEndNode : public IfNode {
370 public:
371 enum { TestControl, TestValue };
372 BaseCountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
373 : IfNode(control, test, prob, cnt) {
374 init_class_id(Class_BaseCountedLoopEnd);
375 }
376
377 Node *cmp_node() const { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : nullptr; }
378 Node* incr() const { Node* tmp = cmp_node(); return (tmp && tmp->req() == 3) ? tmp->in(1) : nullptr; }
379 Node* limit() const { Node* tmp = cmp_node(); return (tmp && tmp->req() == 3) ? tmp->in(2) : nullptr; }
380 Node* stride() const { Node* tmp = incr(); return (tmp && tmp->req() == 3) ? tmp->in(2) : nullptr; }
381 Node* init_trip() const { Node* tmp = phi(); return (tmp && tmp->req() == 3) ? tmp->in(1) : nullptr; }
382 bool stride_is_con() const { Node *tmp = stride(); return (tmp != nullptr && tmp->is_Con()); }
383
384 PhiNode* phi() const {
385 Node* tmp = incr();
386 if (tmp && tmp->req() == 3) {
387 Node* phi = tmp->in(1);
388 if (phi->is_Phi()) {
389 return phi->as_Phi();
390 }
391 }
392 return nullptr;
393 }
394
395 BaseCountedLoopNode* loopnode() const {
396 // The CountedLoopNode that goes with this CountedLoopEndNode may
397 // have been optimized out by the IGVN so be cautious with the
398 // pattern matching on the graph
399 PhiNode* iv_phi = phi();
400 if (iv_phi == nullptr) {
401 return nullptr;
402 }
403 Node* ln = iv_phi->in(0);
404 if (!ln->is_BaseCountedLoop() || ln->as_BaseCountedLoop()->loopexit_or_null() != this) {
405 return nullptr;
406 }
407 if (ln->as_BaseCountedLoop()->bt() != bt()) {
408 return nullptr;
409 }
410 return ln->as_BaseCountedLoop();
411 }
412
413 BoolTest::mask test_trip() const { return in(TestValue)->as_Bool()->_test._test; }
414
415 jlong stride_con() const;
416 virtual BasicType bt() const = 0;
417
418 static BaseCountedLoopEndNode* make(Node* control, Node* test, float prob, float cnt, BasicType bt);
419 };
420
421 class CountedLoopEndNode : public BaseCountedLoopEndNode {
422 public:
423
424 CountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
425 : BaseCountedLoopEndNode(control, test, prob, cnt) {
426 init_class_id(Class_CountedLoopEnd);
427 }
428 virtual int Opcode() const;
429
430 CountedLoopNode* loopnode() const {
431 return (CountedLoopNode*) BaseCountedLoopEndNode::loopnode();
432 }
433
434 virtual BasicType bt() const {
435 return T_INT;
436 }
437
438 #ifndef PRODUCT
439 virtual void dump_spec(outputStream *st) const;
440 #endif
441 };
442
443 class LongCountedLoopEndNode : public BaseCountedLoopEndNode {
444 public:
445 LongCountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
446 : BaseCountedLoopEndNode(control, test, prob, cnt) {
447 init_class_id(Class_LongCountedLoopEnd);
448 }
449
450 LongCountedLoopNode* loopnode() const {
451 return (LongCountedLoopNode*) BaseCountedLoopEndNode::loopnode();
452 }
453
454 virtual int Opcode() const;
455
456 virtual BasicType bt() const {
457 return T_LONG;
458 }
459 };
460
461
462 inline BaseCountedLoopEndNode* BaseCountedLoopNode::loopexit_or_null() const {
463 Node* bctrl = back_control();
464 if (bctrl == nullptr) return nullptr;
465
466 Node* lexit = bctrl->in(0);
467 if (!lexit->is_BaseCountedLoopEnd()) {
468 return nullptr;
469 }
470 BaseCountedLoopEndNode* result = lexit->as_BaseCountedLoopEnd();
471 if (result->bt() != bt()) {
472 return nullptr;
473 }
474 return result;
475 }
476
477 inline BaseCountedLoopEndNode* BaseCountedLoopNode::loopexit() const {
478 BaseCountedLoopEndNode* cle = loopexit_or_null();
479 assert(cle != nullptr, "loopexit is null");
480 return cle;
481 }
482
483 inline Node* BaseCountedLoopNode::init_trip() const {
484 BaseCountedLoopEndNode* cle = loopexit_or_null();
485 return cle != nullptr ? cle->init_trip() : nullptr;
486 }
487 inline Node* BaseCountedLoopNode::stride() const {
488 BaseCountedLoopEndNode* cle = loopexit_or_null();
489 return cle != nullptr ? cle->stride() : nullptr;
490 }
491
492 inline bool BaseCountedLoopNode::stride_is_con() const {
493 BaseCountedLoopEndNode* cle = loopexit_or_null();
494 return cle != nullptr && cle->stride_is_con();
495 }
496 inline Node* BaseCountedLoopNode::limit() const {
497 BaseCountedLoopEndNode* cle = loopexit_or_null();
498 return cle != nullptr ? cle->limit() : nullptr;
499 }
500 inline Node* BaseCountedLoopNode::incr() const {
501 BaseCountedLoopEndNode* cle = loopexit_or_null();
502 return cle != nullptr ? cle->incr() : nullptr;
503 }
504 inline Node* BaseCountedLoopNode::phi() const {
505 BaseCountedLoopEndNode* cle = loopexit_or_null();
506 return cle != nullptr ? cle->phi() : nullptr;
507 }
508
509 inline jlong BaseCountedLoopNode::stride_con() const {
510 BaseCountedLoopEndNode* cle = loopexit_or_null();
511 return cle != nullptr ? cle->stride_con() : 0;
512 }
513
514
515 //------------------------------LoopLimitNode-----------------------------
516 // Counted Loop limit node which represents exact final iterator value:
517 // trip_count = (limit - init_trip + stride - 1)/stride
518 // final_value= trip_count * stride + init_trip.
519 // Use HW instructions to calculate it when it can overflow in integer.
520 // Note, final_value should fit into integer since counted loop has
521 // limit check: limit <= max_int-stride.
522 class LoopLimitNode : public Node {
523 enum { Init=1, Limit=2, Stride=3 };
524 public:
525 LoopLimitNode( Compile* C, Node *init, Node *limit, Node *stride ) : Node(0,init,limit,stride) {
526 // Put it on the Macro nodes list to optimize during macro nodes expansion.
527 init_flags(Flag_is_macro);
528 C->add_macro_node(this);
529 }
530 virtual int Opcode() const;
531 virtual const Type *bottom_type() const { return TypeInt::INT; }
532 virtual uint ideal_reg() const { return Op_RegI; }
533 virtual const Type* Value(PhaseGVN* phase) const;
534 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
535 virtual Node* Identity(PhaseGVN* phase);
536 };
537
538 // Support for strip mining
539 class OuterStripMinedLoopNode : public LoopNode {
540 private:
541 static void fix_sunk_stores(CountedLoopEndNode* inner_cle, LoopNode* inner_cl, PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
542
543 public:
544 OuterStripMinedLoopNode(Compile* C, Node *entry, Node *backedge)
545 : LoopNode(entry, backedge) {
546 init_class_id(Class_OuterStripMinedLoop);
547 init_flags(Flag_is_macro);
548 C->add_macro_node(this);
549 }
550
551 virtual int Opcode() const;
552
553 virtual IfTrueNode* outer_loop_tail() const;
554 virtual OuterStripMinedLoopEndNode* outer_loop_end() const;
555 virtual IfFalseNode* outer_loop_exit() const;
556 virtual SafePointNode* outer_safepoint() const;
557 void adjust_strip_mined_loop(PhaseIterGVN* igvn);
558
559 void remove_outer_loop_and_safepoint(PhaseIterGVN* igvn) const;
560
561 void transform_to_counted_loop(PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
562
563 static Node* register_new_node(Node* node, LoopNode* ctrl, PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
564
565 Node* register_control(Node* node, Node* loop, Node* idom, PhaseIterGVN* igvn,
566 PhaseIdealLoop* iloop);
567 };
568
569 class OuterStripMinedLoopEndNode : public IfNode {
570 public:
571 OuterStripMinedLoopEndNode(Node *control, Node *test, float prob, float cnt)
572 : IfNode(control, test, prob, cnt) {
573 init_class_id(Class_OuterStripMinedLoopEnd);
574 }
575
576 virtual int Opcode() const;
577
578 virtual const Type* Value(PhaseGVN* phase) const;
579 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
580
581 bool is_expanded(PhaseGVN *phase) const;
582 };
583
584 // -----------------------------IdealLoopTree----------------------------------
585 class IdealLoopTree : public ResourceObj {
586 public:
587 IdealLoopTree *_parent; // Parent in loop tree
588 IdealLoopTree *_next; // Next sibling in loop tree
589 IdealLoopTree *_child; // First child in loop tree
590
591 // The head-tail backedge defines the loop.
592 // If a loop has multiple backedges, this is addressed during cleanup where
593 // we peel off the multiple backedges, merging all edges at the bottom and
594 // ensuring that one proper backedge flow into the loop.
595 Node *_head; // Head of loop
596 Node *_tail; // Tail of loop
597 inline Node *tail(); // Handle lazy update of _tail field
598 inline Node *head(); // Handle lazy update of _head field
599 PhaseIdealLoop* _phase;
600 int _local_loop_unroll_limit;
601 int _local_loop_unroll_factor;
602
603 Node_List _body; // Loop body for inner loops
604
605 uint16_t _nest; // Nesting depth
606 uint8_t _irreducible:1, // True if irreducible
607 _has_call:1, // True if has call safepoint
608 _has_sfpt:1, // True if has non-call safepoint
609 _rce_candidate:1, // True if candidate for range check elimination
610 _has_range_checks:1,
611 _has_range_checks_computed:1;
612
613 Node_List* _safepts; // List of safepoints in this loop
614 Node_List* _required_safept; // A inner loop cannot delete these safepts;
615 bool _allow_optimizations; // Allow loop optimizations
616
617 IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail )
618 : _parent(0), _next(0), _child(0),
619 _head(head), _tail(tail),
620 _phase(phase),
621 _local_loop_unroll_limit(0), _local_loop_unroll_factor(0),
622 _nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0),
623 _has_range_checks(0), _has_range_checks_computed(0),
624 _safepts(nullptr),
625 _required_safept(nullptr),
626 _allow_optimizations(true)
627 {
628 precond(_head != nullptr);
629 precond(_tail != nullptr);
630 }
631
632 // Is 'l' a member of 'this'?
633 bool is_member(const IdealLoopTree *l) const; // Test for nested membership
634
635 // Set loop nesting depth. Accumulate has_call bits.
636 int set_nest( uint depth );
637
638 // Split out multiple fall-in edges from the loop header. Move them to a
639 // private RegionNode before the loop. This becomes the loop landing pad.
640 void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt );
641
642 // Split out the outermost loop from this shared header.
643 void split_outer_loop( PhaseIdealLoop *phase );
644
645 // Merge all the backedges from the shared header into a private Region.
646 // Feed that region as the one backedge to this loop.
647 void merge_many_backedges( PhaseIdealLoop *phase );
648
649 // Split shared headers and insert loop landing pads.
650 // Insert a LoopNode to replace the RegionNode.
651 // Returns TRUE if loop tree is structurally changed.
652 bool beautify_loops( PhaseIdealLoop *phase );
653
654 // Perform optimization to use the loop predicates for null checks and range checks.
655 // Applies to any loop level (not just the innermost one)
656 bool loop_predication( PhaseIdealLoop *phase);
657
658 // Perform iteration-splitting on inner loops. Split iterations to
659 // avoid range checks or one-shot null checks. Returns false if the
660 // current round of loop opts should stop.
661 bool iteration_split( PhaseIdealLoop *phase, Node_List &old_new );
662
663 // Driver for various flavors of iteration splitting. Returns false
664 // if the current round of loop opts should stop.
665 bool iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new );
666
667 // Given dominators, try to find loops with calls that must always be
668 // executed (call dominates loop tail). These loops do not need non-call
669 // safepoints (ncsfpt).
670 void check_safepts(VectorSet &visited, Node_List &stack);
671
672 // Allpaths backwards scan from loop tail, terminating each path at first safepoint
673 // encountered.
674 void allpaths_check_safepts(VectorSet &visited, Node_List &stack);
675
676 // Remove safepoints from loop. Optionally keeping one.
677 void remove_safepoints(PhaseIdealLoop* phase, bool keep_one);
678
679 // Convert to counted loops where possible
680 void counted_loop( PhaseIdealLoop *phase );
681
682 // Check for Node being a loop-breaking test
683 Node *is_loop_exit(Node *iff) const;
684
685 // Remove simplistic dead code from loop body
686 void DCE_loop_body();
687
688 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage.
689 // Replace with a 1-in-10 exit guess.
690 void adjust_loop_exit_prob( PhaseIdealLoop *phase );
691
692 // Return TRUE or FALSE if the loop should never be RCE'd or aligned.
693 // Useful for unrolling loops with NO array accesses.
694 bool policy_peel_only( PhaseIdealLoop *phase ) const;
695
696 // Return TRUE or FALSE if the loop should be unswitched -- clone
697 // loop with an invariant test
698 bool policy_unswitching( PhaseIdealLoop *phase ) const;
699
700 // Micro-benchmark spamming. Remove empty loops.
701 bool do_remove_empty_loop( PhaseIdealLoop *phase );
702
703 // Convert one iteration loop into normal code.
704 bool do_one_iteration_loop( PhaseIdealLoop *phase );
705
706 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can
707 // move some loop-invariant test (usually a null-check) before the loop.
708 bool policy_peeling(PhaseIdealLoop *phase);
709
710 uint estimate_peeling(PhaseIdealLoop *phase);
711
712 // Return TRUE or FALSE if the loop should be maximally unrolled. Stash any
713 // known trip count in the counted loop node.
714 bool policy_maximally_unroll(PhaseIdealLoop *phase) const;
715
716 // Return TRUE or FALSE if the loop should be unrolled or not. Apply unroll
717 // if the loop is a counted loop and the loop body is small enough.
718 bool policy_unroll(PhaseIdealLoop *phase);
719
720 // Loop analyses to map to a maximal superword unrolling for vectorization.
721 void policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_ct);
722
723 // Return TRUE or FALSE if the loop should be range-check-eliminated.
724 // Gather a list of IF tests that are dominated by iteration splitting;
725 // also gather the end of the first split and the start of the 2nd split.
726 bool policy_range_check(PhaseIdealLoop* phase, bool provisional, BasicType bt) const;
727
728 // Return TRUE if "iff" is a range check.
729 bool is_range_check_if(IfProjNode* if_success_proj, PhaseIdealLoop* phase, Invariance& invar DEBUG_ONLY(COMMA ProjNode* predicate_proj)) const;
730 bool is_range_check_if(IfProjNode* if_success_proj, PhaseIdealLoop* phase, BasicType bt, Node* iv, Node*& range, Node*& offset,
731 jlong& scale) const;
732
733 // Estimate the number of nodes required when cloning a loop (body).
734 uint est_loop_clone_sz(uint factor) const;
735 // Estimate the number of nodes required when unrolling a loop (body).
736 uint est_loop_unroll_sz(uint factor) const;
737
738 // Compute loop trip count if possible
739 void compute_trip_count(PhaseIdealLoop* phase);
740
741 // Compute loop trip count from profile data
742 float compute_profile_trip_cnt_helper(Node* n);
743 void compute_profile_trip_cnt( PhaseIdealLoop *phase );
744
745 // Reassociate invariant expressions.
746 void reassociate_invariants(PhaseIdealLoop *phase);
747 // Reassociate invariant binary expressions.
748 Node* reassociate(Node* n1, PhaseIdealLoop *phase);
749 // Reassociate invariant add and subtract expressions.
750 Node* reassociate_add_sub(Node* n1, int inv1_idx, int inv2_idx, PhaseIdealLoop *phase);
751 // Return nonzero index of invariant operand if invariant and variant
752 // are combined with an associative binary. Helper for reassociate_invariants.
753 int find_invariant(Node* n, PhaseIdealLoop *phase);
754 // Return TRUE if "n" is associative.
755 bool is_associative(Node* n, Node* base=nullptr);
756
757 // Return true if n is invariant
758 bool is_invariant(Node* n) const;
759
760 // Put loop body on igvn work list
761 void record_for_igvn();
762
763 bool is_root() { return _parent == nullptr; }
764 // A proper/reducible loop w/o any (occasional) dead back-edge.
765 bool is_loop() { return !_irreducible && !tail()->is_top(); }
766 bool is_counted() { return is_loop() && _head->is_CountedLoop(); }
767 bool is_innermost() { return is_loop() && _child == nullptr; }
768
769 void remove_main_post_loops(CountedLoopNode *cl, PhaseIdealLoop *phase);
770
771 bool compute_has_range_checks() const;
772 bool range_checks_present() {
773 if (!_has_range_checks_computed) {
774 if (compute_has_range_checks()) {
775 _has_range_checks = 1;
776 }
777 _has_range_checks_computed = 1;
778 }
779 return _has_range_checks;
780 }
781
782 #ifndef PRODUCT
783 void dump_head(); // Dump loop head only
784 void dump(); // Dump this loop recursively
785 #endif
786
787 #ifdef ASSERT
788 GrowableArray<IdealLoopTree*> collect_sorted_children() const;
789 bool verify_tree(IdealLoopTree* loop_verify) const;
790 #endif
791
792 private:
793 enum { EMPTY_LOOP_SIZE = 7 }; // Number of nodes in an empty loop.
794
795 // Estimate the number of nodes resulting from control and data flow merge.
796 uint est_loop_flow_merge_sz() const;
797
798 // Check if the number of residual iterations is large with unroll_cnt.
799 // Return true if the residual iterations are more than 10% of the trip count.
800 bool is_residual_iters_large(int unroll_cnt, CountedLoopNode *cl) const {
801 return (unroll_cnt - 1) * (100.0 / LoopPercentProfileLimit) > cl->profile_trip_cnt();
802 }
803
804 void collect_loop_core_nodes(PhaseIdealLoop* phase, Unique_Node_List& wq) const;
805
806 bool empty_loop_with_data_nodes(PhaseIdealLoop* phase) const;
807
808 void enqueue_data_nodes(PhaseIdealLoop* phase, Unique_Node_List& empty_loop_nodes, Unique_Node_List& wq) const;
809
810 bool process_safepoint(PhaseIdealLoop* phase, Unique_Node_List& empty_loop_nodes, Unique_Node_List& wq,
811 Node* sfpt) const;
812
813 bool empty_loop_candidate(PhaseIdealLoop* phase) const;
814
815 bool empty_loop_with_extra_nodes_candidate(PhaseIdealLoop* phase) const;
816 };
817
818 // -----------------------------PhaseIdealLoop---------------------------------
819 // Computes the mapping from Nodes to IdealLoopTrees. Organizes IdealLoopTrees
820 // into a loop tree. Drives the loop-based transformations on the ideal graph.
821 class PhaseIdealLoop : public PhaseTransform {
822 friend class IdealLoopTree;
823 friend class SuperWord;
824 friend class CountedLoopReserveKit;
825 friend class ShenandoahBarrierC2Support;
826 friend class AutoNodeBudget;
827
828 // Map loop membership for CFG nodes, and ctrl for non-CFG nodes.
829 Node_List _loop_or_ctrl;
830
831 // Pre-computed def-use info
832 PhaseIterGVN &_igvn;
833
834 // Head of loop tree
835 IdealLoopTree* _ltree_root;
836
837 // Array of pre-order numbers, plus post-visited bit.
838 // ZERO for not pre-visited. EVEN for pre-visited but not post-visited.
839 // ODD for post-visited. Other bits are the pre-order number.
840 uint *_preorders;
841 uint _max_preorder;
842
843 const PhaseIdealLoop* _verify_me;
844 bool _verify_only;
845
846 // Allocate _preorders[] array
847 void allocate_preorders() {
848 _max_preorder = C->unique()+8;
849 _preorders = NEW_RESOURCE_ARRAY(uint, _max_preorder);
850 memset(_preorders, 0, sizeof(uint) * _max_preorder);
851 }
852
853 // Allocate _preorders[] array
854 void reallocate_preorders() {
855 if ( _max_preorder < C->unique() ) {
856 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique());
857 _max_preorder = C->unique();
858 }
859 memset(_preorders, 0, sizeof(uint) * _max_preorder);
860 }
861
862 // Check to grow _preorders[] array for the case when build_loop_tree_impl()
863 // adds new nodes.
864 void check_grow_preorders( ) {
865 if ( _max_preorder < C->unique() ) {
866 uint newsize = _max_preorder<<1; // double size of array
867 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize);
868 memset(&_preorders[_max_preorder],0,sizeof(uint)*(newsize-_max_preorder));
869 _max_preorder = newsize;
870 }
871 }
872 // Check for pre-visited. Zero for NOT visited; non-zero for visited.
873 int is_visited( Node *n ) const { return _preorders[n->_idx]; }
874 // Pre-order numbers are written to the Nodes array as low-bit-set values.
875 void set_preorder_visited( Node *n, int pre_order ) {
876 assert( !is_visited( n ), "already set" );
877 _preorders[n->_idx] = (pre_order<<1);
878 };
879 // Return pre-order number.
880 int get_preorder( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]>>1; }
881
882 // Check for being post-visited.
883 // Should be previsited already (checked with assert(is_visited(n))).
884 int is_postvisited( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]&1; }
885
886 // Mark as post visited
887 void set_postvisited( Node *n ) { assert( !is_postvisited( n ), "" ); _preorders[n->_idx] |= 1; }
888
889 public:
890 // Set/get control node out. Set lower bit to distinguish from IdealLoopTree
891 // Returns true if "n" is a data node, false if it's a control node.
892 bool has_ctrl(const Node* n) const { return ((intptr_t)_loop_or_ctrl[n->_idx]) & 1; }
893
894 private:
895 // clear out dead code after build_loop_late
896 Node_List _deadlist;
897 Node_List _zero_trip_guard_opaque_nodes;
898
899 // Support for faster execution of get_late_ctrl()/dom_lca()
900 // when a node has many uses and dominator depth is deep.
901 GrowableArray<jlong> _dom_lca_tags;
902 uint _dom_lca_tags_round;
903 void init_dom_lca_tags();
904
905 // Helper for debugging bad dominance relationships
906 bool verify_dominance(Node* n, Node* use, Node* LCA, Node* early);
907
908 Node* compute_lca_of_uses(Node* n, Node* early, bool verify = false);
909
910 // Inline wrapper for frequent cases:
911 // 1) only one use
912 // 2) a use is the same as the current LCA passed as 'n1'
913 Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) {
914 assert( n->is_CFG(), "" );
915 // Fast-path null lca
916 if( lca != nullptr && lca != n ) {
917 assert( lca->is_CFG(), "" );
918 // find LCA of all uses
919 n = dom_lca_for_get_late_ctrl_internal( lca, n, tag );
920 }
921 return find_non_split_ctrl(n);
922 }
923 Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag );
924
925 // Helper function for directing control inputs away from CFG split points.
926 Node *find_non_split_ctrl( Node *ctrl ) const {
927 if (ctrl != nullptr) {
928 if (ctrl->is_MultiBranch()) {
929 ctrl = ctrl->in(0);
930 }
931 assert(ctrl->is_CFG(), "CFG");
932 }
933 return ctrl;
934 }
935
936 Node* cast_incr_before_loop(Node* incr, Node* ctrl, Node* loop);
937
938 #ifdef ASSERT
939 void ensure_zero_trip_guard_proj(Node* node, bool is_main_loop);
940 #endif
941 void copy_assertion_predicates_to_main_loop_helper(Node* predicate, Node* init, Node* stride, IdealLoopTree* outer_loop,
942 LoopNode* outer_main_head, uint dd_main_head,
943 uint idx_before_pre_post, uint idx_after_post_before_pre,
944 Node* zero_trip_guard_proj_main, Node* zero_trip_guard_proj_post,
945 const Node_List &old_new);
946 void copy_assertion_predicates_to_main_loop(CountedLoopNode* pre_head, Node* init, Node* stride, IdealLoopTree* outer_loop,
947 LoopNode* outer_main_head, uint dd_main_head, uint idx_before_pre_post,
948 uint idx_after_post_before_pre, Node* zero_trip_guard_proj_main,
949 Node* zero_trip_guard_proj_post, const Node_List& old_new);
950 Node* clone_assertion_predicate_and_initialize(Node* iff, Node* new_init, Node* new_stride, Node* predicate,
951 Node* uncommon_proj, Node* control, IdealLoopTree* outer_loop,
952 Node* input_proj);
953 static void count_opaque_loop_nodes(Node* n, uint& init, uint& stride);
954 static bool subgraph_has_opaque(Node* n);
955 Node* create_bool_from_template_assertion_predicate(Node* template_assertion_predicate, Node* new_init, Node* new_stride,
956 Node* control);
957 static bool assertion_predicate_has_loop_opaque_node(IfNode* iff);
958 static void get_assertion_predicates(Node* predicate, Unique_Node_List& list, bool get_opaque = false);
959 void update_main_loop_assertion_predicates(Node* ctrl, CountedLoopNode* loop_head, Node* init, int stride_con);
960 void copy_assertion_predicates_to_post_loop(LoopNode* main_loop_head, CountedLoopNode* post_loop_head, Node* init,
961 Node* stride);
962 void initialize_assertion_predicates_for_peeled_loop(IfProjNode* predicate_proj, LoopNode* outer_loop_head,
963 const int dd_outer_loop_head, Node* init, Node* stride,
964 IdealLoopTree* outer_loop, const uint idx_before_clone,
965 const Node_List& old_new);
966 void insert_loop_limit_check_predicate(ParsePredicateSuccessProj* loop_limit_check_parse_proj, Node* cmp_limit,
967 Node* bol);
968 #ifdef ASSERT
969 bool only_has_infinite_loops();
970 #endif
971
972 void log_loop_tree();
973
974 public:
975
976 PhaseIterGVN &igvn() const { return _igvn; }
977
978 bool has_node(const Node* n) const {
979 guarantee(n != nullptr, "No Node.");
980 return _loop_or_ctrl[n->_idx] != nullptr;
981 }
982 // check if transform created new nodes that need _ctrl recorded
983 Node *get_late_ctrl( Node *n, Node *early );
984 Node *get_early_ctrl( Node *n );
985 Node *get_early_ctrl_for_expensive(Node *n, Node* earliest);
986 void set_early_ctrl(Node* n, bool update_body);
987 void set_subtree_ctrl(Node* n, bool update_body);
988 void set_ctrl( Node *n, Node *ctrl ) {
989 assert( !has_node(n) || has_ctrl(n), "" );
990 assert( ctrl->in(0), "cannot set dead control node" );
991 assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" );
992 _loop_or_ctrl.map(n->_idx, (Node*)((intptr_t)ctrl + 1));
993 }
994 // Set control and update loop membership
995 void set_ctrl_and_loop(Node* n, Node* ctrl) {
996 IdealLoopTree* old_loop = get_loop(get_ctrl(n));
997 IdealLoopTree* new_loop = get_loop(ctrl);
998 if (old_loop != new_loop) {
999 if (old_loop->_child == nullptr) old_loop->_body.yank(n);
1000 if (new_loop->_child == nullptr) new_loop->_body.push(n);
1001 }
1002 set_ctrl(n, ctrl);
1003 }
1004 // Control nodes can be replaced or subsumed. During this pass they
1005 // get their replacement Node in slot 1. Instead of updating the block
1006 // location of all Nodes in the subsumed block, we lazily do it. As we
1007 // pull such a subsumed block out of the array, we write back the final
1008 // correct block.
1009 Node* get_ctrl(const Node* i) {
1010 assert(has_node(i), "");
1011 Node *n = get_ctrl_no_update(i);
1012 _loop_or_ctrl.map(i->_idx, (Node*)((intptr_t)n + 1));
1013 assert(has_node(i) && has_ctrl(i), "");
1014 assert(n == find_non_split_ctrl(n), "must return legal ctrl" );
1015 return n;
1016 }
1017 // true if CFG node d dominates CFG node n
1018 bool is_dominator(Node *d, Node *n);
1019 // return get_ctrl for a data node and self(n) for a CFG node
1020 Node* ctrl_or_self(Node* n) {
1021 if (has_ctrl(n))
1022 return get_ctrl(n);
1023 else {
1024 assert (n->is_CFG(), "must be a CFG node");
1025 return n;
1026 }
1027 }
1028
1029 Node* get_ctrl_no_update_helper(const Node* i) const {
1030 assert(has_ctrl(i), "should be control, not loop");
1031 return (Node*)(((intptr_t)_loop_or_ctrl[i->_idx]) & ~1);
1032 }
1033
1034 Node* get_ctrl_no_update(const Node* i) const {
1035 assert( has_ctrl(i), "" );
1036 Node *n = get_ctrl_no_update_helper(i);
1037 if (!n->in(0)) {
1038 // Skip dead CFG nodes
1039 do {
1040 n = get_ctrl_no_update_helper(n);
1041 } while (!n->in(0));
1042 n = find_non_split_ctrl(n);
1043 }
1044 return n;
1045 }
1046
1047 // Check for loop being set
1048 // "n" must be a control node. Returns true if "n" is known to be in a loop.
1049 bool has_loop( Node *n ) const {
1050 assert(!has_node(n) || !has_ctrl(n), "");
1051 return has_node(n);
1052 }
1053 // Set loop
1054 void set_loop( Node *n, IdealLoopTree *loop ) {
1055 _loop_or_ctrl.map(n->_idx, (Node*)loop);
1056 }
1057 // Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms. Replace
1058 // the 'old_node' with 'new_node'. Kill old-node. Add a reference
1059 // from old_node to new_node to support the lazy update. Reference
1060 // replaces loop reference, since that is not needed for dead node.
1061 void lazy_update(Node *old_node, Node *new_node) {
1062 assert(old_node != new_node, "no cycles please");
1063 // Re-use the side array slot for this node to provide the
1064 // forwarding pointer.
1065 _loop_or_ctrl.map(old_node->_idx, (Node*)((intptr_t)new_node + 1));
1066 }
1067 void lazy_replace(Node *old_node, Node *new_node) {
1068 _igvn.replace_node(old_node, new_node);
1069 lazy_update(old_node, new_node);
1070 }
1071
1072 private:
1073
1074 // Place 'n' in some loop nest, where 'n' is a CFG node
1075 void build_loop_tree();
1076 int build_loop_tree_impl( Node *n, int pre_order );
1077 // Insert loop into the existing loop tree. 'innermost' is a leaf of the
1078 // loop tree, not the root.
1079 IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost );
1080
1081 #ifdef ASSERT
1082 // verify that regions in irreducible loops are marked is_in_irreducible_loop
1083 void verify_regions_in_irreducible_loops();
1084 bool is_in_irreducible_loop(RegionNode* region);
1085 #endif
1086
1087 // Place Data nodes in some loop nest
1088 void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
1089 void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
1090 void build_loop_late_post_work(Node* n, bool pinned);
1091 void build_loop_late_post(Node* n);
1092 void verify_strip_mined_scheduling(Node *n, Node* least);
1093
1094 // Array of immediate dominance info for each CFG node indexed by node idx
1095 private:
1096 uint _idom_size;
1097 Node **_idom; // Array of immediate dominators
1098 uint *_dom_depth; // Used for fast LCA test
1099 GrowableArray<uint>* _dom_stk; // For recomputation of dom depth
1100 LoopOptsMode _mode;
1101
1102 // build the loop tree and perform any requested optimizations
1103 void build_and_optimize();
1104
1105 // Dominators for the sea of nodes
1106 void Dominators();
1107
1108 // Compute the Ideal Node to Loop mapping
1109 PhaseIdealLoop(PhaseIterGVN& igvn, LoopOptsMode mode) :
1110 PhaseTransform(Ideal_Loop),
1111 _igvn(igvn),
1112 _verify_me(nullptr),
1113 _verify_only(false),
1114 _mode(mode),
1115 _nodes_required(UINT_MAX) {
1116 assert(mode != LoopOptsVerify, "wrong constructor to verify IdealLoop");
1117 build_and_optimize();
1118 }
1119
1120 #ifndef PRODUCT
1121 // Verify that verify_me made the same decisions as a fresh run
1122 // or only verify that the graph is valid if verify_me is null.
1123 PhaseIdealLoop(PhaseIterGVN& igvn, const PhaseIdealLoop* verify_me = nullptr) :
1124 PhaseTransform(Ideal_Loop),
1125 _igvn(igvn),
1126 _verify_me(verify_me),
1127 _verify_only(verify_me == nullptr),
1128 _mode(LoopOptsVerify),
1129 _nodes_required(UINT_MAX) {
1130 build_and_optimize();
1131 }
1132 #endif
1133
1134 public:
1135 Node* idom_no_update(Node* d) const {
1136 return idom_no_update(d->_idx);
1137 }
1138
1139 Node* idom_no_update(uint didx) const {
1140 assert(didx < _idom_size, "oob");
1141 Node* n = _idom[didx];
1142 assert(n != nullptr,"Bad immediate dominator info.");
1143 while (n->in(0) == nullptr) { // Skip dead CFG nodes
1144 n = (Node*)(((intptr_t)_loop_or_ctrl[n->_idx]) & ~1);
1145 assert(n != nullptr,"Bad immediate dominator info.");
1146 }
1147 return n;
1148 }
1149
1150 Node *idom(Node* d) const {
1151 return idom(d->_idx);
1152 }
1153
1154 Node *idom(uint didx) const {
1155 Node *n = idom_no_update(didx);
1156 _idom[didx] = n; // Lazily remove dead CFG nodes from table.
1157 return n;
1158 }
1159
1160 uint dom_depth(Node* d) const {
1161 guarantee(d != nullptr, "Null dominator info.");
1162 guarantee(d->_idx < _idom_size, "");
1163 return _dom_depth[d->_idx];
1164 }
1165 void set_idom(Node* d, Node* n, uint dom_depth);
1166 // Locally compute IDOM using dom_lca call
1167 Node *compute_idom( Node *region ) const;
1168 // Recompute dom_depth
1169 void recompute_dom_depth();
1170
1171 // Is safept not required by an outer loop?
1172 bool is_deleteable_safept(Node* sfpt);
1173
1174 // Replace parallel induction variable (parallel to trip counter)
1175 void replace_parallel_iv(IdealLoopTree *loop);
1176
1177 Node *dom_lca( Node *n1, Node *n2 ) const {
1178 return find_non_split_ctrl(dom_lca_internal(n1, n2));
1179 }
1180 Node *dom_lca_internal( Node *n1, Node *n2 ) const;
1181
1182 // Build and verify the loop tree without modifying the graph. This
1183 // is useful to verify that all inputs properly dominate their uses.
1184 static void verify(PhaseIterGVN& igvn) {
1185 #ifdef ASSERT
1186 ResourceMark rm;
1187 Compile::TracePhase tp("idealLoopVerify", &timers[_t_idealLoopVerify]);
1188 PhaseIdealLoop v(igvn);
1189 #endif
1190 }
1191
1192 // Recommended way to use PhaseIdealLoop.
1193 // Run PhaseIdealLoop in some mode and allocates a local scope for memory allocations.
1194 static void optimize(PhaseIterGVN &igvn, LoopOptsMode mode) {
1195 ResourceMark rm;
1196 PhaseIdealLoop v(igvn, mode);
1197
1198 Compile* C = Compile::current();
1199 if (!C->failing()) {
1200 // Cleanup any modified bits
1201 igvn.optimize();
1202
1203 v.log_loop_tree();
1204 }
1205 }
1206
1207 // True if the method has at least 1 irreducible loop
1208 bool _has_irreducible_loops;
1209
1210 // Per-Node transform
1211 virtual Node* transform(Node* n) { return nullptr; }
1212
1213 Node* loop_exit_control(Node* x, IdealLoopTree* loop);
1214 Node* loop_exit_test(Node* back_control, IdealLoopTree* loop, Node*& incr, Node*& limit, BoolTest::mask& bt, float& cl_prob);
1215 Node* loop_iv_incr(Node* incr, Node* x, IdealLoopTree* loop, Node*& phi_incr);
1216 Node* loop_iv_stride(Node* incr, IdealLoopTree* loop, Node*& xphi);
1217 PhiNode* loop_iv_phi(Node* xphi, Node* phi_incr, Node* x, IdealLoopTree* loop);
1218
1219 bool is_counted_loop(Node* x, IdealLoopTree*&loop, BasicType iv_bt);
1220
1221 Node* loop_nest_replace_iv(Node* iv_to_replace, Node* inner_iv, Node* outer_phi, Node* inner_head, BasicType bt);
1222 bool create_loop_nest(IdealLoopTree* loop, Node_List &old_new);
1223 #ifdef ASSERT
1224 bool convert_to_long_loop(Node* cmp, Node* phi, IdealLoopTree* loop);
1225 #endif
1226 void add_parse_predicate(Deoptimization::DeoptReason reason, Node* inner_head, IdealLoopTree* loop, SafePointNode* sfpt);
1227 SafePointNode* find_safepoint(Node* back_control, Node* x, IdealLoopTree* loop);
1228 IdealLoopTree* insert_outer_loop(IdealLoopTree* loop, LoopNode* outer_l, Node* outer_ift);
1229 IdealLoopTree* create_outer_strip_mined_loop(BoolNode *test, Node *cmp, Node *init_control,
1230 IdealLoopTree* loop, float cl_prob, float le_fcnt,
1231 Node*& entry_control, Node*& iffalse);
1232
1233 Node* exact_limit( IdealLoopTree *loop );
1234
1235 // Return a post-walked LoopNode
1236 IdealLoopTree *get_loop( Node *n ) const {
1237 // Dead nodes have no loop, so return the top level loop instead
1238 if (!has_node(n)) return _ltree_root;
1239 assert(!has_ctrl(n), "");
1240 return (IdealLoopTree*)_loop_or_ctrl[n->_idx];
1241 }
1242
1243 IdealLoopTree* ltree_root() const { return _ltree_root; }
1244
1245 // Is 'n' a (nested) member of 'loop'?
1246 int is_member( const IdealLoopTree *loop, Node *n ) const {
1247 return loop->is_member(get_loop(n)); }
1248
1249 // This is the basic building block of the loop optimizations. It clones an
1250 // entire loop body. It makes an old_new loop body mapping; with this
1251 // mapping you can find the new-loop equivalent to an old-loop node. All
1252 // new-loop nodes are exactly equal to their old-loop counterparts, all
1253 // edges are the same. All exits from the old-loop now have a RegionNode
1254 // that merges the equivalent new-loop path. This is true even for the
1255 // normal "loop-exit" condition. All uses of loop-invariant old-loop values
1256 // now come from (one or more) Phis that merge their new-loop equivalents.
1257 // Parameter side_by_side_idom:
1258 // When side_by_size_idom is null, the dominator tree is constructed for
1259 // the clone loop to dominate the original. Used in construction of
1260 // pre-main-post loop sequence.
1261 // When nonnull, the clone and original are side-by-side, both are
1262 // dominated by the passed in side_by_side_idom node. Used in
1263 // construction of unswitched loops.
1264 enum CloneLoopMode {
1265 IgnoreStripMined = 0, // Only clone inner strip mined loop
1266 CloneIncludesStripMined = 1, // clone both inner and outer strip mined loops
1267 ControlAroundStripMined = 2 // Only clone inner strip mined loop,
1268 // result control flow branches
1269 // either to inner clone or outer
1270 // strip mined loop.
1271 };
1272 void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth,
1273 CloneLoopMode mode, Node* side_by_side_idom = nullptr);
1274 void clone_loop_handle_data_uses(Node* old, Node_List &old_new,
1275 IdealLoopTree* loop, IdealLoopTree* companion_loop,
1276 Node_List*& split_if_set, Node_List*& split_bool_set,
1277 Node_List*& split_cex_set, Node_List& worklist,
1278 uint new_counter, CloneLoopMode mode);
1279 void clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
1280 IdealLoopTree* outer_loop, int dd, Node_List &old_new,
1281 Node_List& extra_data_nodes);
1282
1283 // If we got the effect of peeling, either by actually peeling or by
1284 // making a pre-loop which must execute at least once, we can remove
1285 // all loop-invariant dominated tests in the main body.
1286 void peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new );
1287
1288 // Generate code to do a loop peel for the given loop (and body).
1289 // old_new is a temp array.
1290 void do_peeling( IdealLoopTree *loop, Node_List &old_new );
1291
1292 // Add pre and post loops around the given loop. These loops are used
1293 // during RCE, unrolling and aligning loops.
1294 void insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only );
1295
1296 // Add post loop after the given loop.
1297 Node *insert_post_loop(IdealLoopTree* loop, Node_List& old_new,
1298 CountedLoopNode* main_head, CountedLoopEndNode* main_end,
1299 Node*& incr, Node* limit, CountedLoopNode*& post_head);
1300
1301 // Add a vector post loop between a vector main loop and the current post loop
1302 void insert_vector_post_loop(IdealLoopTree *loop, Node_List &old_new);
1303 // If Node n lives in the back_ctrl block, we clone a private version of n
1304 // in preheader_ctrl block and return that, otherwise return n.
1305 Node *clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones );
1306
1307 // Take steps to maximally unroll the loop. Peel any odd iterations, then
1308 // unroll to do double iterations. The next round of major loop transforms
1309 // will repeat till the doubled loop body does all remaining iterations in 1
1310 // pass.
1311 void do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new );
1312
1313 // Unroll the loop body one step - make each trip do 2 iterations.
1314 void do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip );
1315
1316 // Return true if exp is a constant times an induction var
1317 bool is_scaled_iv(Node* exp, Node* iv, BasicType bt, jlong* p_scale, bool* p_short_scale, int depth = 0);
1318
1319 bool is_iv(Node* exp, Node* iv, BasicType bt);
1320
1321 // Return true if exp is a scaled induction var plus (or minus) constant
1322 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);
1323 bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset) {
1324 jlong long_scale;
1325 if (is_scaled_iv_plus_offset(exp, iv, T_INT, &long_scale, p_offset)) {
1326 int int_scale = checked_cast<int>(long_scale);
1327 if (p_scale != nullptr) {
1328 *p_scale = int_scale;
1329 }
1330 return true;
1331 }
1332 return false;
1333 }
1334 // Helper for finding more complex matches to is_scaled_iv_plus_offset.
1335 bool is_scaled_iv_plus_extra_offset(Node* exp1, Node* offset2, Node* iv,
1336 BasicType bt,
1337 jlong* p_scale, Node** p_offset,
1338 bool* p_short_scale, int depth);
1339
1340 // Create a new if above the uncommon_trap_if_pattern for the predicate to be promoted
1341 IfProjNode* create_new_if_for_predicate(IfProjNode* cont_proj, Node* new_entry, Deoptimization::DeoptReason reason,
1342 int opcode, bool rewire_uncommon_proj_phi_inputs = false,
1343 bool if_cont_is_true_proj = true);
1344
1345 private:
1346 // Helper functions for create_new_if_for_predicate()
1347 void set_ctrl_of_nodes_with_same_ctrl(Node* node, ProjNode* old_ctrl, Node* new_ctrl);
1348 Unique_Node_List find_nodes_with_same_ctrl(Node* node, const ProjNode* ctrl);
1349 Node* clone_nodes_with_same_ctrl(Node* node, ProjNode* old_ctrl, Node* new_ctrl);
1350 Dict clone_nodes(const Node_List& list_to_clone);
1351 void rewire_cloned_nodes_to_ctrl(const ProjNode* old_ctrl, Node* new_ctrl, const Node_List& nodes_with_same_ctrl,
1352 const Dict& old_new_mapping);
1353 void rewire_inputs_of_clones_to_clones(Node* new_ctrl, Node* clone, const Dict& old_new_mapping, const Node* next);
1354
1355 public:
1356 void register_control(Node* n, IdealLoopTree *loop, Node* pred, bool update_body = true);
1357
1358 // Construct a range check for a predicate if
1359 BoolNode* rc_predicate(IdealLoopTree* loop, Node* ctrl, int scale, Node* offset, Node* init, Node* limit,
1360 jint stride, Node* range, bool upper, bool& overflow);
1361
1362 // Implementation of the loop predication to promote checks outside the loop
1363 bool loop_predication_impl(IdealLoopTree *loop);
1364 bool loop_predication_impl_helper(IdealLoopTree* loop, IfProjNode* if_success_proj,
1365 ParsePredicateSuccessProj* parse_predicate_proj, CountedLoopNode* cl, ConNode* zero,
1366 Invariance& invar, Deoptimization::DeoptReason reason);
1367 bool loop_predication_should_follow_branches(IdealLoopTree* loop, IfProjNode* predicate_proj, float& loop_trip_cnt);
1368 void loop_predication_follow_branches(Node *c, IdealLoopTree *loop, float loop_trip_cnt,
1369 PathFrequency& pf, Node_Stack& stack, VectorSet& seen,
1370 Node_List& if_proj_list);
1371 IfProjNode* add_template_assertion_predicate(IfNode* iff, IdealLoopTree* loop, IfProjNode* if_proj, IfProjNode* predicate_proj,
1372 IfProjNode* upper_bound_proj, int scale, Node* offset, Node* init, Node* limit,
1373 jint stride, Node* rng, bool& overflow, Deoptimization::DeoptReason reason);
1374 Node* add_range_check_elimination_assertion_predicate(IdealLoopTree* loop, Node* predicate_proj, int scale_con,
1375 Node* offset, Node* limit, jint stride_con, Node* value);
1376
1377 // Helper function to collect predicate for eliminating the useless ones
1378 void collect_potentially_useful_predicates(IdealLoopTree *loop, Unique_Node_List &predicate_opaque1);
1379 void eliminate_useless_predicates();
1380 void eliminate_useless_zero_trip_guard();
1381
1382 // Change the control input of expensive nodes to allow commoning by
1383 // IGVN when it is guaranteed to not result in a more frequent
1384 // execution of the expensive node. Return true if progress.
1385 bool process_expensive_nodes();
1386
1387 // Check whether node has become unreachable
1388 bool is_node_unreachable(Node *n) const {
1389 return !has_node(n) || n->is_unreachable(_igvn);
1390 }
1391
1392 // Eliminate range-checks and other trip-counter vs loop-invariant tests.
1393 void do_range_check(IdealLoopTree *loop, Node_List &old_new);
1394
1395 // Create a slow version of the loop by cloning the loop
1396 // and inserting an if to select fast-slow versions.
1397 // Return the inserted if.
1398 IfNode* create_slow_version_of_loop(IdealLoopTree *loop,
1399 Node_List &old_new,
1400 Node_List &unswitch_iffs,
1401 CloneLoopMode mode);
1402
1403 // Clone a loop and return the clone head (clone_loop_head).
1404 // Added nodes include int(1), int(0) - disconnected, If, IfTrue, IfFalse,
1405 // This routine was created for usage in CountedLoopReserveKit.
1406 //
1407 // int(1) -> If -> IfTrue -> original_loop_head
1408 // |
1409 // V
1410 // IfFalse -> clone_loop_head (returned by function pointer)
1411 //
1412 LoopNode* create_reserve_version_of_loop(IdealLoopTree *loop, CountedLoopReserveKit* lk);
1413 // Clone loop with an invariant test (that does not exit) and
1414 // insert a clone of the test that selects which version to
1415 // execute.
1416 void do_unswitching (IdealLoopTree *loop, Node_List &old_new);
1417
1418 // Find candidate "if" for unswitching
1419 IfNode* find_unswitching_candidate(const IdealLoopTree *loop, Node_List& unswitch_iffs) const;
1420
1421 // Range Check Elimination uses this function!
1422 // Constrain the main loop iterations so the affine function:
1423 // low_limit <= scale_con * I + offset < upper_limit
1424 // always holds true. That is, either increase the number of iterations in
1425 // the pre-loop or the post-loop until the condition holds true in the main
1426 // loop. Scale_con, offset and limit are all loop invariant.
1427 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);
1428 // Helper function for add_constraint().
1429 Node* adjust_limit(bool reduce, Node* scale, Node* offset, Node* rc_limit, Node* old_limit, Node* pre_ctrl, bool round);
1430
1431 // Partially peel loop up through last_peel node.
1432 bool partial_peel( IdealLoopTree *loop, Node_List &old_new );
1433 bool duplicate_loop_backedge(IdealLoopTree *loop, Node_List &old_new);
1434
1435 // Move UnorderedReduction out of loop if possible
1436 void move_unordered_reduction_out_of_loop(IdealLoopTree* loop);
1437
1438 // Create a scheduled list of nodes control dependent on ctrl set.
1439 void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched );
1440 // Has a use in the vector set
1441 bool has_use_in_set( Node* n, VectorSet& vset );
1442 // Has use internal to the vector set (ie. not in a phi at the loop head)
1443 bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop );
1444 // clone "n" for uses that are outside of loop
1445 int clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist );
1446 // clone "n" for special uses that are in the not_peeled region
1447 void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
1448 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist );
1449 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
1450 void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp );
1451 #ifdef ASSERT
1452 // Validate the loop partition sets: peel and not_peel
1453 bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel );
1454 // Ensure that uses outside of loop are of the right form
1455 bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
1456 uint orig_exit_idx, uint clone_exit_idx);
1457 bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx);
1458 #endif
1459
1460 // Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.)
1461 int stride_of_possible_iv( Node* iff );
1462 bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; }
1463 // Return the (unique) control output node that's in the loop (if it exists.)
1464 Node* stay_in_loop( Node* n, IdealLoopTree *loop);
1465 // Insert a signed compare loop exit cloned from an unsigned compare.
1466 IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop);
1467 void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop);
1468 // Utility to register node "n" with PhaseIdealLoop
1469 void register_node(Node* n, IdealLoopTree* loop, Node* pred, uint ddepth);
1470 // Utility to create an if-projection
1471 ProjNode* proj_clone(ProjNode* p, IfNode* iff);
1472 // Force the iff control output to be the live_proj
1473 Node* short_circuit_if(IfNode* iff, ProjNode* live_proj);
1474 // Insert a region before an if projection
1475 RegionNode* insert_region_before_proj(ProjNode* proj);
1476 // Insert a new if before an if projection
1477 ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj);
1478
1479 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1480 // "Nearly" because all Nodes have been cloned from the original in the loop,
1481 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1482 // through the Phi recursively, and return a Bool.
1483 Node* clone_iff(PhiNode* phi);
1484 CmpNode* clone_bool(PhiNode* phi);
1485
1486
1487 // Rework addressing expressions to get the most loop-invariant stuff
1488 // moved out. We'd like to do all associative operators, but it's especially
1489 // important (common) to do address expressions.
1490 Node* remix_address_expressions(Node* n);
1491 Node* remix_address_expressions_add_left_shift(Node* n, IdealLoopTree* n_loop, Node* n_ctrl, BasicType bt);
1492
1493 // Convert add to muladd to generate MuladdS2I under certain criteria
1494 Node * convert_add_to_muladd(Node * n);
1495
1496 // Attempt to use a conditional move instead of a phi/branch
1497 Node *conditional_move( Node *n );
1498
1499 // Check for aggressive application of 'split-if' optimization,
1500 // using basic block level info.
1501 void split_if_with_blocks ( VectorSet &visited, Node_Stack &nstack);
1502 Node *split_if_with_blocks_pre ( Node *n );
1503 void split_if_with_blocks_post( Node *n );
1504 Node *has_local_phi_input( Node *n );
1505 // Mark an IfNode as being dominated by a prior test,
1506 // without actually altering the CFG (and hence IDOM info).
1507 void dominated_by(IfProjNode* prevdom, IfNode* iff, bool flip = false, bool exclude_loop_predicate = false);
1508
1509 // Split Node 'n' through merge point
1510 RegionNode* split_thru_region(Node* n, RegionNode* region);
1511 // Split Node 'n' through merge point if there is enough win.
1512 Node *split_thru_phi( Node *n, Node *region, int policy );
1513 // Found an If getting its condition-code input from a Phi in the
1514 // same block. Split thru the Region.
1515 void do_split_if(Node *iff, RegionNode** new_false_region = nullptr, RegionNode** new_true_region = nullptr);
1516
1517 // Conversion of fill/copy patterns into intrinsic versions
1518 bool do_intrinsify_fill();
1519 bool intrinsify_fill(IdealLoopTree* lpt);
1520 bool match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value,
1521 Node*& shift, Node*& offset);
1522
1523 private:
1524 // Return a type based on condition control flow
1525 const TypeInt* filtered_type( Node *n, Node* n_ctrl);
1526 const TypeInt* filtered_type( Node *n ) { return filtered_type(n, nullptr); }
1527 // Helpers for filtered type
1528 const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl);
1529
1530 // Helper functions
1531 Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache );
1532 Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true );
1533 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 );
1534 bool split_up( Node *n, Node *blk1, Node *blk2 );
1535 void sink_use( Node *use, Node *post_loop );
1536 Node* place_outside_loop(Node* useblock, IdealLoopTree* loop) const;
1537 Node* try_move_store_before_loop(Node* n, Node *n_ctrl);
1538 void try_move_store_after_loop(Node* n);
1539 void move_flat_array_check_out_of_loop(Node* n);
1540 bool identical_backtoback_ifs(Node *n);
1541 bool flat_array_element_type_check(Node *n);
1542 bool can_split_if(Node *n_ctrl);
1543 bool cannot_split_division(const Node* n, const Node* region) const;
1544 static bool is_divisor_counted_loop_phi(const Node* divisor, const Node* loop);
1545 bool loop_phi_backedge_type_contains_zero(const Node* phi_divisor, const Type* zero) const;
1546
1547 // Determine if a method is too big for a/another round of split-if, based on
1548 // a magic (approximate) ratio derived from the equally magic constant 35000,
1549 // previously used for this purpose (but without relating to the node limit).
1550 bool must_throttle_split_if() {
1551 uint threshold = C->max_node_limit() * 2 / 5;
1552 return C->live_nodes() > threshold;
1553 }
1554
1555 // A simplistic node request tracking mechanism, where
1556 // = UINT_MAX Request not valid or made final.
1557 // < UINT_MAX Nodes currently requested (estimate).
1558 uint _nodes_required;
1559
1560 enum { REQUIRE_MIN = 70 };
1561
1562 uint nodes_required() const { return _nodes_required; }
1563
1564 // Given the _currently_ available number of nodes, check whether there is
1565 // "room" for an additional request or not, considering the already required
1566 // number of nodes. Return TRUE if the new request is exceeding the node
1567 // budget limit, otherwise return FALSE. Note that this interpretation will
1568 // act pessimistic on additional requests when new nodes have already been
1569 // generated since the 'begin'. This behaviour fits with the intention that
1570 // node estimates/requests should be made upfront.
1571 bool exceeding_node_budget(uint required = 0) {
1572 assert(C->live_nodes() < C->max_node_limit(), "sanity");
1573 uint available = C->max_node_limit() - C->live_nodes();
1574 return available < required + _nodes_required + REQUIRE_MIN;
1575 }
1576
1577 uint require_nodes(uint require, uint minreq = REQUIRE_MIN) {
1578 precond(require > 0);
1579 _nodes_required += MAX2(require, minreq);
1580 return _nodes_required;
1581 }
1582
1583 bool may_require_nodes(uint require, uint minreq = REQUIRE_MIN) {
1584 return !exceeding_node_budget(require) && require_nodes(require, minreq) > 0;
1585 }
1586
1587 uint require_nodes_begin() {
1588 assert(_nodes_required == UINT_MAX, "Bad state (begin).");
1589 _nodes_required = 0;
1590 return C->live_nodes();
1591 }
1592
1593 // When a node request is final, optionally check that the requested number
1594 // of nodes was reasonably correct with respect to the number of new nodes
1595 // introduced since the last 'begin'. Always check that we have not exceeded
1596 // the maximum node limit.
1597 void require_nodes_final(uint live_at_begin, bool check_estimate) {
1598 assert(_nodes_required < UINT_MAX, "Bad state (final).");
1599
1600 #ifdef ASSERT
1601 if (check_estimate) {
1602 // Check that the node budget request was not off by too much (x2).
1603 // Should this be the case we _surely_ need to improve the estimates
1604 // used in our budget calculations.
1605 if (C->live_nodes() - live_at_begin > 2 * _nodes_required) {
1606 log_info(compilation)("Bad node estimate: actual = %d >> request = %d",
1607 C->live_nodes() - live_at_begin, _nodes_required);
1608 }
1609 }
1610 #endif
1611 // Assert that we have stayed within the node budget limit.
1612 assert(C->live_nodes() < C->max_node_limit(),
1613 "Exceeding node budget limit: %d + %d > %d (request = %d)",
1614 C->live_nodes() - live_at_begin, live_at_begin,
1615 C->max_node_limit(), _nodes_required);
1616
1617 _nodes_required = UINT_MAX;
1618 }
1619
1620 // Clone Parse Predicates to slow and fast loop when unswitching a loop
1621 void clone_parse_and_assertion_predicates_to_unswitched_loop(IdealLoopTree* loop, Node_List& old_new,
1622 IfProjNode*& iffast_pred, IfProjNode*& ifslow_pred);
1623 IfProjNode* clone_parse_predicate_to_unswitched_loop(ParsePredicateSuccessProj* predicate_proj, Node* new_entry,
1624 Deoptimization::DeoptReason reason, bool slow_loop);
1625 void clone_assertion_predicates_to_unswitched_loop(IdealLoopTree* loop, const Node_List& old_new,
1626 Deoptimization::DeoptReason reason, IfProjNode* old_predicate_proj,
1627 IfProjNode* iffast_pred, IfProjNode* ifslow_pred);
1628 IfProjNode* clone_assertion_predicate_for_unswitched_loops(Node* iff, IfProjNode* predicate,
1629 Deoptimization::DeoptReason reason,
1630 IfProjNode* output_proj);
1631 static void check_cloned_parse_predicate_for_unswitching(const Node* new_entry, bool is_fast_loop) PRODUCT_RETURN;
1632
1633 bool _created_loop_node;
1634 DEBUG_ONLY(void dump_idoms(Node* early, Node* wrong_lca);)
1635 NOT_PRODUCT(void dump_idoms_in_reverse(const Node* n, const Node_List& idom_list) const;)
1636
1637 public:
1638 void set_created_loop_node() { _created_loop_node = true; }
1639 bool created_loop_node() { return _created_loop_node; }
1640 void register_new_node(Node* n, Node* blk);
1641
1642 #ifdef ASSERT
1643 void dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA);
1644 #endif
1645
1646 #ifndef PRODUCT
1647 void dump() const;
1648 void dump_idom(Node* n) const { dump_idom(n, 1000); } // For debugging
1649 void dump_idom(Node* n, uint count) const;
1650 void get_idoms(Node* n, uint count, Unique_Node_List& idoms) const;
1651 void dump(IdealLoopTree* loop, uint rpo_idx, Node_List &rpo_list) const;
1652 IdealLoopTree* get_loop_idx(Node* n) const {
1653 // Dead nodes have no loop, so return the top level loop instead
1654 return _loop_or_ctrl[n->_idx] ? (IdealLoopTree*)_loop_or_ctrl[n->_idx] : _ltree_root;
1655 }
1656 // Print some stats
1657 static void print_statistics();
1658 static int _loop_invokes; // Count of PhaseIdealLoop invokes
1659 static int _loop_work; // Sum of PhaseIdealLoop x _unique
1660 static volatile int _long_loop_candidates;
1661 static volatile int _long_loop_nests;
1662 static volatile int _long_loop_counted_loops;
1663 #endif
1664
1665 #ifdef ASSERT
1666 void verify() const;
1667 bool verify_idom_and_nodes(Node* root, const PhaseIdealLoop* phase_verify) const;
1668 bool verify_idom(Node* n, const PhaseIdealLoop* phase_verify) const;
1669 bool verify_loop_ctrl(Node* n, const PhaseIdealLoop* phase_verify) const;
1670 #endif
1671
1672 void rpo(Node* start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list) const;
1673
1674 void check_counted_loop_shape(IdealLoopTree* loop, Node* x, BasicType bt) NOT_DEBUG_RETURN;
1675
1676 LoopNode* create_inner_head(IdealLoopTree* loop, BaseCountedLoopNode* head, IfNode* exit_test);
1677
1678
1679 int extract_long_range_checks(const IdealLoopTree* loop, jlong stride_con, int iters_limit, PhiNode* phi,
1680 Node_List &range_checks);
1681
1682 void transform_long_range_checks(int stride_con, const Node_List &range_checks, Node* outer_phi,
1683 Node* inner_iters_actual_int, Node* inner_phi,
1684 Node* iv_add, LoopNode* inner_head);
1685
1686 Node* get_late_ctrl_with_anti_dep(LoadNode* n, Node* early, Node* LCA);
1687
1688 bool ctrl_of_use_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop, Node* ctrl);
1689
1690 bool ctrl_of_all_uses_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop);
1691
1692 Node* compute_early_ctrl(Node* n, Node* n_ctrl);
1693
1694 void try_sink_out_of_loop(Node* n);
1695
1696 Node* clamp(Node* R, Node* L, Node* H);
1697
1698 bool safe_for_if_replacement(const Node* dom) const;
1699
1700 void push_pinned_nodes_thru_region(IfNode* dom_if, Node* region);
1701
1702 bool try_merge_identical_ifs(Node* n);
1703
1704 void clone_loop_body(const Node_List& body, Node_List &old_new, CloneMap* cm);
1705
1706 void fix_body_edges(const Node_List &body, IdealLoopTree* loop, const Node_List &old_new, int dd,
1707 IdealLoopTree* parent, bool partial);
1708
1709 void fix_ctrl_uses(const Node_List& body, const IdealLoopTree* loop, Node_List &old_new, CloneLoopMode mode,
1710 Node* side_by_side_idom, CloneMap* cm, Node_List &worklist);
1711
1712 void fix_data_uses(Node_List& body, IdealLoopTree* loop, CloneLoopMode mode, IdealLoopTree* outer_loop,
1713 uint new_counter, Node_List& old_new, Node_List& worklist, Node_List*& split_if_set,
1714 Node_List*& split_bool_set, Node_List*& split_cex_set);
1715
1716 void finish_clone_loop(Node_List* split_if_set, Node_List* split_bool_set, Node_List* split_cex_set);
1717
1718 bool clone_cmp_down(Node* n, const Node* blk1, const Node* blk2);
1719
1720 void clone_loadklass_nodes_at_cmp_index(const Node* n, Node* cmp, int i);
1721
1722 bool clone_cmp_loadklass_down(Node* n, const Node* blk1, const Node* blk2);
1723
1724 bool at_relevant_ctrl(Node* n, const Node* blk1, const Node* blk2);
1725 };
1726
1727
1728 class AutoNodeBudget : public StackObj
1729 {
1730 public:
1731 enum budget_check_t { BUDGET_CHECK, NO_BUDGET_CHECK };
1732
1733 AutoNodeBudget(PhaseIdealLoop* phase, budget_check_t chk = BUDGET_CHECK)
1734 : _phase(phase),
1735 _check_at_final(chk == BUDGET_CHECK),
1736 _nodes_at_begin(0)
1737 {
1738 precond(_phase != nullptr);
1739
1740 _nodes_at_begin = _phase->require_nodes_begin();
1741 }
1742
1743 ~AutoNodeBudget() {
1744 #ifndef PRODUCT
1745 if (TraceLoopOpts) {
1746 uint request = _phase->nodes_required();
1747 uint delta = _phase->C->live_nodes() - _nodes_at_begin;
1748
1749 if (request < delta) {
1750 tty->print_cr("Exceeding node budget: %d < %d", request, delta);
1751 } else {
1752 uint const REQUIRE_MIN = PhaseIdealLoop::REQUIRE_MIN;
1753 // Identify the worst estimates as "poor" ones.
1754 if (request > REQUIRE_MIN && delta > 0) {
1755 if ((delta > REQUIRE_MIN && request > 3 * delta) ||
1756 (delta <= REQUIRE_MIN && request > 10 * delta)) {
1757 tty->print_cr("Poor node estimate: %d >> %d", request, delta);
1758 }
1759 }
1760 }
1761 }
1762 #endif // PRODUCT
1763 _phase->require_nodes_final(_nodes_at_begin, _check_at_final);
1764 }
1765
1766 private:
1767 PhaseIdealLoop* _phase;
1768 bool _check_at_final;
1769 uint _nodes_at_begin;
1770 };
1771
1772
1773 // This kit may be used for making of a reserved copy of a loop before this loop
1774 // goes under non-reversible changes.
1775 //
1776 // Function create_reserve() creates a reserved copy (clone) of the loop.
1777 // The reserved copy is created by calling
1778 // PhaseIdealLoop::create_reserve_version_of_loop - see there how
1779 // the original and reserved loops are connected in the outer graph.
1780 // If create_reserve succeeded, it returns 'true' and _has_reserved is set to 'true'.
1781 //
1782 // By default the reserved copy (clone) of the loop is created as dead code - it is
1783 // dominated in the outer loop by this node chain:
1784 // intcon(1)->If->IfFalse->reserved_copy.
1785 // The original loop is dominated by the same node chain but IfTrue projection:
1786 // intcon(0)->If->IfTrue->original_loop.
1787 //
1788 // In this implementation of CountedLoopReserveKit the ctor includes create_reserve()
1789 // and the dtor, checks _use_new value.
1790 // If _use_new == false, it "switches" control to reserved copy of the loop
1791 // by simple replacing of node intcon(1) with node intcon(0).
1792 //
1793 // Here is a proposed example of usage (see also SuperWord::output in superword.cpp).
1794 //
1795 // void CountedLoopReserveKit_example()
1796 // {
1797 // CountedLoopReserveKit lrk((phase, lpt, DoReserveCopy = true); // create local object
1798 // if (DoReserveCopy && !lrk.has_reserved()) {
1799 // return; //failed to create reserved loop copy
1800 // }
1801 // ...
1802 // //something is wrong, switch to original loop
1803 /// if(something_is_wrong) return; // ~CountedLoopReserveKit makes the switch
1804 // ...
1805 // //everything worked ok, return with the newly modified loop
1806 // lrk.use_new();
1807 // return; // ~CountedLoopReserveKit does nothing once use_new() was called
1808 // }
1809 //
1810 // Keep in mind, that by default if create_reserve() is not followed by use_new()
1811 // the dtor will "switch to the original" loop.
1812 // NOTE. You you modify outside of the original loop this class is no help.
1813 //
1814 class CountedLoopReserveKit {
1815 private:
1816 PhaseIdealLoop* _phase;
1817 IdealLoopTree* _lpt;
1818 LoopNode* _lp;
1819 IfNode* _iff;
1820 LoopNode* _lp_reserved;
1821 bool _has_reserved;
1822 bool _use_new;
1823 const bool _active; //may be set to false in ctor, then the object is dummy
1824
1825 public:
1826 CountedLoopReserveKit(PhaseIdealLoop* phase, IdealLoopTree *loop, bool active);
1827 ~CountedLoopReserveKit();
1828 void use_new() {_use_new = true;}
1829 void set_iff(IfNode* x) {_iff = x;}
1830 bool has_reserved() const { return _active && _has_reserved;}
1831 private:
1832 bool create_reserve();
1833 };// class CountedLoopReserveKit
1834
1835 inline Node* IdealLoopTree::tail() {
1836 // Handle lazy update of _tail field.
1837 if (_tail->in(0) == nullptr) {
1838 _tail = _phase->get_ctrl(_tail);
1839 }
1840 return _tail;
1841 }
1842
1843 inline Node* IdealLoopTree::head() {
1844 // Handle lazy update of _head field.
1845 if (_head->in(0) == nullptr) {
1846 _head = _phase->get_ctrl(_head);
1847 }
1848 return _head;
1849 }
1850
1851 // Iterate over the loop tree using a preorder, left-to-right traversal.
1852 //
1853 // Example that visits all counted loops from within PhaseIdealLoop
1854 //
1855 // for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
1856 // IdealLoopTree* lpt = iter.current();
1857 // if (!lpt->is_counted()) continue;
1858 // ...
1859 class LoopTreeIterator : public StackObj {
1860 private:
1861 IdealLoopTree* _root;
1862 IdealLoopTree* _curnt;
1863
1864 public:
1865 LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {}
1866
1867 bool done() { return _curnt == nullptr; } // Finished iterating?
1868
1869 void next(); // Advance to next loop tree
1870
1871 IdealLoopTree* current() { return _curnt; } // Return current value of iterator.
1872 };
1873
1874 // Compute probability of reaching some CFG node from a fixed
1875 // dominating CFG node
1876 class PathFrequency {
1877 private:
1878 Node* _dom; // frequencies are computed relative to this node
1879 Node_Stack _stack;
1880 GrowableArray<float> _freqs_stack; // keep track of intermediate result at regions
1881 GrowableArray<float> _freqs; // cache frequencies
1882 PhaseIdealLoop* _phase;
1883
1884 float check_and_truncate_frequency(float f) {
1885 assert(f >= 0, "Incorrect frequency");
1886 // We do not perform an exact (f <= 1) check
1887 // this would be error prone with rounding of floats.
1888 // Performing a check like (f <= 1+eps) would be of benefit,
1889 // however, it is not evident how to determine such an eps,
1890 // given that an arbitrary number of add/mul operations
1891 // are performed on these frequencies.
1892 return (f > 1) ? 1 : f;
1893 }
1894
1895 public:
1896 PathFrequency(Node* dom, PhaseIdealLoop* phase)
1897 : _dom(dom), _stack(0), _phase(phase) {
1898 }
1899
1900 float to(Node* n);
1901 };
1902
1903 // Utility class to work on predicates.
1904 class Predicates {
1905 public:
1906 static Node* skip_all_predicates(Node* node);
1907 static Node* skip_all_predicates(ParsePredicates& parse_predicates);
1908 static Node* skip_predicates_in_block(ParsePredicateSuccessProj* parse_predicate_success_proj);
1909 static IfProjNode* next_predicate_proj_in_block(IfProjNode* proj);
1910 static bool has_profiled_loop_predicates(ParsePredicates& parse_predicates);
1911 };
1912
1913 // Class representing the Parse Predicates that are added during parsing with ParsePredicateNodes.
1914 class ParsePredicates {
1915 private:
1916 ParsePredicateSuccessProj* _loop_predicate_proj = nullptr;
1917 ParsePredicateSuccessProj* _profiled_loop_predicate_proj = nullptr;
1918 ParsePredicateSuccessProj* _loop_limit_check_predicate_proj = nullptr;
1919 // The success projection of the Parse Predicate that comes first when starting from root.
1920 ParsePredicateSuccessProj* _top_predicate_proj;
1921 ParsePredicateSuccessProj* _starting_proj;
1922
1923 void find_parse_predicate_projections();
1924 static bool is_uct_proj(Node* node, Deoptimization::DeoptReason deopt_reason);
1925 static ParsePredicateNode* get_parse_predicate_or_null(Node* proj);
1926 bool assign_predicate_proj(ParsePredicateSuccessProj* parse_predicate_proj);
1927 public:
1928 ParsePredicates(Node* starting_proj);
1929
1930 // Success projection of Loop Parse Predicate.
1931 ParsePredicateSuccessProj* loop_predicate_proj() {
1932 return _loop_predicate_proj;
1933 }
1934
1935 // Success proj of Profiled Loop Parse Predicate.
1936 ParsePredicateSuccessProj* profiled_loop_predicate_proj() {
1937 return _profiled_loop_predicate_proj;
1938 }
1939
1940 // Success proj of Loop Limit Check Parse Predicate.
1941 ParsePredicateSuccessProj* loop_limit_check_predicate_proj() {
1942 return _loop_limit_check_predicate_proj;
1943 }
1944
1945 // Return the success projection of the Parse Predicate that comes first when starting from root.
1946 ParsePredicateSuccessProj* get_top_predicate_proj() {
1947 return _top_predicate_proj;
1948 }
1949
1950 static bool is_success_proj(Node* node);
1951
1952 // Are there any Parse Predicates?
1953 bool has_any() const {
1954 return _top_predicate_proj != nullptr;
1955 }
1956
1957 static bool is_loop_limit_check_predicate_proj(Node* node) {
1958 ParsePredicateNode* parse_predicate = get_parse_predicate_or_null(node);
1959 return parse_predicate != nullptr && parse_predicate->deopt_reason() == Deoptimization::DeoptReason::Reason_loop_limit_check;
1960 }
1961 };
1962 #endif // SHARE_OPTO_LOOPNODE_HPP