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.
22 *
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 #include "utilities/checkedCast.hpp"
34
35 class CmpNode;
36 class BaseCountedLoopEndNode;
37 class CountedLoopNode;
38 class IdealLoopTree;
39 class LoopNode;
40 class Node;
41 class OuterStripMinedLoopEndNode;
42 class PredicateBlock;
43 class PathFrequency;
44 class PhaseIdealLoop;
45 class VectorSet;
46 class VSharedData;
47 class Invariance;
48 struct small_cache;
49
50 //
51 // I D E A L I Z E D L O O P S
52 //
53 // Idealized loops are the set of loops I perform more interesting
54 // transformations on, beyond simple hoisting.
55
56 //------------------------------LoopNode---------------------------------------
57 // Simple loop header. Fall in path on left, loop-back path on right.
58 class LoopNode : public RegionNode {
59 // Size is bigger to hold the flags. However, the flags do not change
60 // the semantics so it does not appear in the hash & cmp functions.
61 virtual uint size_of() const { return sizeof(*this); }
62 protected:
63 uint _loop_flags;
64 // Names for flag bitfields
65 enum { Normal=0, Pre=1, Main=2, Post=3, PreMainPostFlagsMask=3,
66 MainHasNoPreLoop = 1<<2,
67 HasExactTripCount = 1<<3,
68 InnerLoop = 1<<4,
69 PartialPeelLoop = 1<<5,
70 PartialPeelFailed = 1<<6,
71 WasSlpAnalyzed = 1<<7,
72 PassedSlpAnalysis = 1<<8,
73 DoUnrollOnly = 1<<9,
74 VectorizedLoop = 1<<10,
75 HasAtomicPostLoop = 1<<11,
76 StripMined = 1<<12,
77 SubwordLoop = 1<<13,
78 ProfileTripFailed = 1<<14,
79 LoopNestInnerLoop = 1<<15,
80 LoopNestLongOuterLoop = 1<<16,
81 FlatArrays = 1<<17};
82 char _unswitch_count;
83 enum { _unswitch_max=3 };
84
85 // Expected trip count from profile data
86 float _profile_trip_cnt;
87
88 public:
89 // Names for edge indices
90 enum { Self=0, EntryControl, LoopBackControl };
91
92 bool is_inner_loop() const { return _loop_flags & InnerLoop; }
93 void set_inner_loop() { _loop_flags |= InnerLoop; }
94
95 bool is_vectorized_loop() const { return _loop_flags & VectorizedLoop; }
96 bool is_partial_peel_loop() const { return _loop_flags & PartialPeelLoop; }
97 void set_partial_peel_loop() { _loop_flags |= PartialPeelLoop; }
98 bool partial_peel_has_failed() const { return _loop_flags & PartialPeelFailed; }
99 bool is_strip_mined() const { return _loop_flags & StripMined; }
100 bool is_profile_trip_failed() const { return _loop_flags & ProfileTripFailed; }
101 bool is_subword_loop() const { return _loop_flags & SubwordLoop; }
102 bool is_loop_nest_inner_loop() const { return _loop_flags & LoopNestInnerLoop; }
103 bool is_loop_nest_outer_loop() const { return _loop_flags & LoopNestLongOuterLoop; }
104 bool is_flat_arrays() const { return _loop_flags & FlatArrays; }
105
106 void mark_partial_peel_failed() { _loop_flags |= PartialPeelFailed; }
107 void mark_was_slp() { _loop_flags |= WasSlpAnalyzed; }
108 void mark_passed_slp() { _loop_flags |= PassedSlpAnalysis; }
109 void mark_do_unroll_only() { _loop_flags |= DoUnrollOnly; }
110 void mark_loop_vectorized() { _loop_flags |= VectorizedLoop; }
111 void mark_has_atomic_post_loop() { _loop_flags |= HasAtomicPostLoop; }
112 void mark_strip_mined() { _loop_flags |= StripMined; }
113 void clear_strip_mined() { _loop_flags &= ~StripMined; }
114 void mark_profile_trip_failed() { _loop_flags |= ProfileTripFailed; }
115 void mark_subword_loop() { _loop_flags |= SubwordLoop; }
116 void mark_loop_nest_inner_loop() { _loop_flags |= LoopNestInnerLoop; }
117 void mark_loop_nest_outer_loop() { _loop_flags |= LoopNestLongOuterLoop; }
118 void mark_flat_arrays() { _loop_flags |= FlatArrays; }
119
120 int unswitch_max() { return _unswitch_max; }
121 int unswitch_count() { return _unswitch_count; }
122
123 void set_unswitch_count(int val) {
124 assert (val <= unswitch_max(), "too many unswitches");
125 _unswitch_count = val;
126 }
127
128 void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; }
129 float profile_trip_cnt() { return _profile_trip_cnt; }
130
131 LoopNode(Node *entry, Node *backedge)
132 : RegionNode(3), _loop_flags(0), _unswitch_count(0),
133 _profile_trip_cnt(COUNT_UNKNOWN) {
134 init_class_id(Class_Loop);
135 init_req(EntryControl, entry);
136 init_req(LoopBackControl, backedge);
137 }
138
139 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
140 virtual int Opcode() const;
141 bool can_be_counted_loop(PhaseValues* phase) const {
142 return req() == 3 && in(0) != nullptr &&
143 in(1) != nullptr && phase->type(in(1)) != Type::TOP &&
144 in(2) != nullptr && phase->type(in(2)) != Type::TOP;
145 }
146 bool is_valid_counted_loop(BasicType bt) const;
147 #ifndef PRODUCT
148 virtual void dump_spec(outputStream *st) const;
149 #endif
150
151 void verify_strip_mined(int expect_skeleton) const NOT_DEBUG_RETURN;
152 virtual LoopNode* skip_strip_mined(int expect_skeleton = 1) { return this; }
153 virtual IfTrueNode* outer_loop_tail() const { ShouldNotReachHere(); return nullptr; }
154 virtual OuterStripMinedLoopEndNode* outer_loop_end() const { ShouldNotReachHere(); return nullptr; }
155 virtual IfFalseNode* outer_loop_exit() const { ShouldNotReachHere(); return nullptr; }
156 virtual SafePointNode* outer_safepoint() const { ShouldNotReachHere(); return nullptr; }
157 };
158
159 //------------------------------Counted Loops----------------------------------
160 // Counted loops are all trip-counted loops, with exactly 1 trip-counter exit
161 // path (and maybe some other exit paths). The trip-counter exit is always
162 // last in the loop. The trip-counter have to stride by a constant;
163 // the exit value is also loop invariant.
164
165 // CountedLoopNodes and CountedLoopEndNodes come in matched pairs. The
166 // CountedLoopNode has the incoming loop control and the loop-back-control
167 // which is always the IfTrue before the matching CountedLoopEndNode. The
168 // CountedLoopEndNode has an incoming control (possibly not the
169 // CountedLoopNode if there is control flow in the loop), the post-increment
170 // trip-counter value, and the limit. The trip-counter value is always of
171 // the form (Op old-trip-counter stride). The old-trip-counter is produced
172 // by a Phi connected to the CountedLoopNode. The stride is constant.
173 // The Op is any commutable opcode, including Add, Mul, Xor. The
174 // CountedLoopEndNode also takes in the loop-invariant limit value.
175
176 // From a CountedLoopNode I can reach the matching CountedLoopEndNode via the
177 // loop-back control. From CountedLoopEndNodes I can reach CountedLoopNodes
178 // via the old-trip-counter from the Op node.
179
180 //------------------------------CountedLoopNode--------------------------------
181 // CountedLoopNodes head simple counted loops. CountedLoopNodes have as
182 // inputs the incoming loop-start control and the loop-back control, so they
183 // act like RegionNodes. They also take in the initial trip counter, the
184 // loop-invariant stride and the loop-invariant limit value. CountedLoopNodes
185 // produce a loop-body control and the trip counter value. Since
186 // CountedLoopNodes behave like RegionNodes I still have a standard CFG model.
187
188 class BaseCountedLoopNode : public LoopNode {
189 public:
190 BaseCountedLoopNode(Node *entry, Node *backedge)
191 : LoopNode(entry, backedge) {
192 }
193
194 Node *init_control() const { return in(EntryControl); }
195 Node *back_control() const { return in(LoopBackControl); }
196
197 Node* init_trip() const;
198 Node* stride() const;
199 bool stride_is_con() const;
200 Node* limit() const;
201 Node* incr() const;
202 Node* phi() const;
203
204 BaseCountedLoopEndNode* loopexit_or_null() const;
205 BaseCountedLoopEndNode* loopexit() const;
206
207 virtual BasicType bt() const = 0;
208
209 jlong stride_con() const;
210
211 static BaseCountedLoopNode* make(Node* entry, Node* backedge, BasicType bt);
212 };
213
214
215 class CountedLoopNode : public BaseCountedLoopNode {
216 // Size is bigger to hold _main_idx. However, _main_idx does not change
217 // the semantics so it does not appear in the hash & cmp functions.
218 virtual uint size_of() const { return sizeof(*this); }
219
220 // For Pre- and Post-loops during debugging ONLY, this holds the index of
221 // the Main CountedLoop. Used to assert that we understand the graph shape.
222 node_idx_t _main_idx;
223
224 // Known trip count calculated by compute_exact_trip_count()
225 uint _trip_count;
226
227 // Log2 of original loop bodies in unrolled loop
228 int _unrolled_count_log2;
229
230 // Node count prior to last unrolling - used to decide if
231 // unroll,optimize,unroll,optimize,... is making progress
232 int _node_count_before_unroll;
233
234 // If slp analysis is performed we record the maximum
235 // vector mapped unroll factor here
236 int _slp_maximum_unroll_factor;
237
238 public:
239 CountedLoopNode(Node *entry, Node *backedge)
240 : BaseCountedLoopNode(entry, backedge), _main_idx(0), _trip_count(max_juint),
241 _unrolled_count_log2(0), _node_count_before_unroll(0),
242 _slp_maximum_unroll_factor(0) {
243 init_class_id(Class_CountedLoop);
244 // Initialize _trip_count to the largest possible value.
245 // Will be reset (lower) if the loop's trip count is known.
246 }
247
248 virtual int Opcode() const;
249 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
250
251 CountedLoopEndNode* loopexit_or_null() const { return (CountedLoopEndNode*) BaseCountedLoopNode::loopexit_or_null(); }
252 CountedLoopEndNode* loopexit() const { return (CountedLoopEndNode*) BaseCountedLoopNode::loopexit(); }
253 int stride_con() const;
254
255 // Match increment with optional truncation
256 static Node*
257 match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInteger** trunc_type,
258 BasicType bt);
259
260 // A 'main' loop has a pre-loop and a post-loop. The 'main' loop
261 // can run short a few iterations and may start a few iterations in.
262 // It will be RCE'd and unrolled and aligned.
263
264 // A following 'post' loop will run any remaining iterations. Used
265 // during Range Check Elimination, the 'post' loop will do any final
266 // iterations with full checks. Also used by Loop Unrolling, where
267 // the 'post' loop will do any epilog iterations needed. Basically,
268 // a 'post' loop can not profitably be further unrolled or RCE'd.
269
270 // A preceding 'pre' loop will run at least 1 iteration (to do peeling),
271 // it may do under-flow checks for RCE and may do alignment iterations
272 // so the following main loop 'knows' that it is striding down cache
273 // lines.
274
275 // A 'main' loop that is ONLY unrolled or peeled, never RCE'd or
276 // Aligned, may be missing it's pre-loop.
277 bool is_normal_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Normal; }
278 bool is_pre_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Pre; }
279 bool is_main_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Main; }
280 bool is_post_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Post; }
281 bool was_slp_analyzed () const { return (_loop_flags&WasSlpAnalyzed) == WasSlpAnalyzed; }
282 bool has_passed_slp () const { return (_loop_flags&PassedSlpAnalysis) == PassedSlpAnalysis; }
283 bool is_unroll_only () const { return (_loop_flags&DoUnrollOnly) == DoUnrollOnly; }
284 bool is_main_no_pre_loop() const { return _loop_flags & MainHasNoPreLoop; }
285 bool has_atomic_post_loop () const { return (_loop_flags & HasAtomicPostLoop) == HasAtomicPostLoop; }
286 void set_main_no_pre_loop() { _loop_flags |= MainHasNoPreLoop; }
287
288 int main_idx() const { return _main_idx; }
289
290
291 void set_pre_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; }
292 void set_main_loop ( ) { assert(is_normal_loop(),""); _loop_flags |= Main; }
293 void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; }
294 void set_normal_loop( ) { _loop_flags &= ~PreMainPostFlagsMask; }
295
296 void set_trip_count(uint tc) { _trip_count = tc; }
297 uint trip_count() { return _trip_count; }
298
299 bool has_exact_trip_count() const { return (_loop_flags & HasExactTripCount) != 0; }
300 void set_exact_trip_count(uint tc) {
301 _trip_count = tc;
302 _loop_flags |= HasExactTripCount;
303 }
304 void set_nonexact_trip_count() {
305 _loop_flags &= ~HasExactTripCount;
306 }
307 void set_notpassed_slp() {
308 _loop_flags &= ~PassedSlpAnalysis;
309 }
310
311 void double_unrolled_count() { _unrolled_count_log2++; }
312 int unrolled_count() { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); }
313
314 void set_node_count_before_unroll(int ct) { _node_count_before_unroll = ct; }
315 int node_count_before_unroll() { return _node_count_before_unroll; }
316 void set_slp_max_unroll(int unroll_factor) { _slp_maximum_unroll_factor = unroll_factor; }
317 int slp_max_unroll() const { return _slp_maximum_unroll_factor; }
318
319 virtual LoopNode* skip_strip_mined(int expect_skeleton = 1);
320 OuterStripMinedLoopNode* outer_loop() const;
321 virtual IfTrueNode* outer_loop_tail() const;
322 virtual OuterStripMinedLoopEndNode* outer_loop_end() const;
323 virtual IfFalseNode* outer_loop_exit() const;
324 virtual SafePointNode* outer_safepoint() const;
325
326 Node* skip_assertion_predicates_with_halt();
327
328 virtual BasicType bt() const {
329 return T_INT;
330 }
331
332 Node* is_canonical_loop_entry();
333 CountedLoopEndNode* find_pre_loop_end();
334
335 #ifndef PRODUCT
336 virtual void dump_spec(outputStream *st) const;
337 #endif
338 };
339
340 class LongCountedLoopNode : public BaseCountedLoopNode {
341 public:
342 LongCountedLoopNode(Node *entry, Node *backedge)
343 : BaseCountedLoopNode(entry, backedge) {
344 init_class_id(Class_LongCountedLoop);
345 }
346
347 virtual int Opcode() const;
348
349 virtual BasicType bt() const {
350 return T_LONG;
351 }
352
353 LongCountedLoopEndNode* loopexit_or_null() const { return (LongCountedLoopEndNode*) BaseCountedLoopNode::loopexit_or_null(); }
354 LongCountedLoopEndNode* loopexit() const { return (LongCountedLoopEndNode*) BaseCountedLoopNode::loopexit(); }
355 };
356
357
358 //------------------------------CountedLoopEndNode-----------------------------
359 // CountedLoopEndNodes end simple trip counted loops. They act much like
360 // IfNodes.
361
362 class BaseCountedLoopEndNode : public IfNode {
363 public:
364 enum { TestControl, TestValue };
365 BaseCountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
366 : IfNode(control, test, prob, cnt) {
367 init_class_id(Class_BaseCountedLoopEnd);
368 }
369
370 Node *cmp_node() const { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : nullptr; }
371 Node* incr() const { Node* tmp = cmp_node(); return (tmp && tmp->req() == 3) ? tmp->in(1) : nullptr; }
372 Node* limit() const { Node* tmp = cmp_node(); return (tmp && tmp->req() == 3) ? tmp->in(2) : nullptr; }
373 Node* stride() const { Node* tmp = incr(); return (tmp && tmp->req() == 3) ? tmp->in(2) : nullptr; }
374 Node* init_trip() const { Node* tmp = phi(); return (tmp && tmp->req() == 3) ? tmp->in(1) : nullptr; }
375 bool stride_is_con() const { Node *tmp = stride(); return (tmp != nullptr && tmp->is_Con()); }
376
377 PhiNode* phi() const {
378 Node* tmp = incr();
379 if (tmp && tmp->req() == 3) {
380 Node* phi = tmp->in(1);
381 if (phi->is_Phi()) {
382 return phi->as_Phi();
383 }
384 }
385 return nullptr;
386 }
387
388 BaseCountedLoopNode* loopnode() const {
389 // The CountedLoopNode that goes with this CountedLoopEndNode may
390 // have been optimized out by the IGVN so be cautious with the
391 // pattern matching on the graph
392 PhiNode* iv_phi = phi();
393 if (iv_phi == nullptr) {
394 return nullptr;
395 }
396 Node* ln = iv_phi->in(0);
397 if (!ln->is_BaseCountedLoop() || ln->as_BaseCountedLoop()->loopexit_or_null() != this) {
398 return nullptr;
399 }
400 if (ln->as_BaseCountedLoop()->bt() != bt()) {
401 return nullptr;
402 }
403 return ln->as_BaseCountedLoop();
404 }
405
406 BoolTest::mask test_trip() const { return in(TestValue)->as_Bool()->_test._test; }
407
408 jlong stride_con() const;
409 virtual BasicType bt() const = 0;
410
411 static BaseCountedLoopEndNode* make(Node* control, Node* test, float prob, float cnt, BasicType bt);
412 };
413
414 class CountedLoopEndNode : public BaseCountedLoopEndNode {
415 public:
416
417 CountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
418 : BaseCountedLoopEndNode(control, test, prob, cnt) {
419 init_class_id(Class_CountedLoopEnd);
420 }
421 virtual int Opcode() const;
422
423 CountedLoopNode* loopnode() const {
424 return (CountedLoopNode*) BaseCountedLoopEndNode::loopnode();
425 }
426
427 virtual BasicType bt() const {
428 return T_INT;
429 }
430
431 #ifndef PRODUCT
432 virtual void dump_spec(outputStream *st) const;
433 #endif
434 };
435
436 class LongCountedLoopEndNode : public BaseCountedLoopEndNode {
437 public:
438 LongCountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
439 : BaseCountedLoopEndNode(control, test, prob, cnt) {
440 init_class_id(Class_LongCountedLoopEnd);
441 }
442
443 LongCountedLoopNode* loopnode() const {
444 return (LongCountedLoopNode*) BaseCountedLoopEndNode::loopnode();
445 }
446
447 virtual int Opcode() const;
448
449 virtual BasicType bt() const {
450 return T_LONG;
451 }
452 };
453
454
455 inline BaseCountedLoopEndNode* BaseCountedLoopNode::loopexit_or_null() const {
456 Node* bctrl = back_control();
457 if (bctrl == nullptr) return nullptr;
458
459 Node* lexit = bctrl->in(0);
460 if (!lexit->is_BaseCountedLoopEnd()) {
461 return nullptr;
462 }
463 BaseCountedLoopEndNode* result = lexit->as_BaseCountedLoopEnd();
464 if (result->bt() != bt()) {
465 return nullptr;
466 }
467 return result;
468 }
469
470 inline BaseCountedLoopEndNode* BaseCountedLoopNode::loopexit() const {
471 BaseCountedLoopEndNode* cle = loopexit_or_null();
472 assert(cle != nullptr, "loopexit is null");
473 return cle;
474 }
475
476 inline Node* BaseCountedLoopNode::init_trip() const {
477 BaseCountedLoopEndNode* cle = loopexit_or_null();
478 return cle != nullptr ? cle->init_trip() : nullptr;
479 }
480 inline Node* BaseCountedLoopNode::stride() const {
481 BaseCountedLoopEndNode* cle = loopexit_or_null();
482 return cle != nullptr ? cle->stride() : nullptr;
483 }
484
485 inline bool BaseCountedLoopNode::stride_is_con() const {
486 BaseCountedLoopEndNode* cle = loopexit_or_null();
487 return cle != nullptr && cle->stride_is_con();
488 }
489 inline Node* BaseCountedLoopNode::limit() const {
490 BaseCountedLoopEndNode* cle = loopexit_or_null();
491 return cle != nullptr ? cle->limit() : nullptr;
492 }
493 inline Node* BaseCountedLoopNode::incr() const {
494 BaseCountedLoopEndNode* cle = loopexit_or_null();
495 return cle != nullptr ? cle->incr() : nullptr;
496 }
497 inline Node* BaseCountedLoopNode::phi() const {
498 BaseCountedLoopEndNode* cle = loopexit_or_null();
499 return cle != nullptr ? cle->phi() : nullptr;
500 }
501
502 inline jlong BaseCountedLoopNode::stride_con() const {
503 BaseCountedLoopEndNode* cle = loopexit_or_null();
504 return cle != nullptr ? cle->stride_con() : 0;
505 }
506
507
508 //------------------------------LoopLimitNode-----------------------------
509 // Counted Loop limit node which represents exact final iterator value:
510 // trip_count = (limit - init_trip + stride - 1)/stride
511 // final_value= trip_count * stride + init_trip.
512 // Use HW instructions to calculate it when it can overflow in integer.
513 // Note, final_value should fit into integer since counted loop has
514 // limit check: limit <= max_int-stride.
515 class LoopLimitNode : public Node {
516 enum { Init=1, Limit=2, Stride=3 };
517 public:
518 LoopLimitNode( Compile* C, Node *init, Node *limit, Node *stride ) : Node(0,init,limit,stride) {
519 // Put it on the Macro nodes list to optimize during macro nodes expansion.
520 init_flags(Flag_is_macro);
521 C->add_macro_node(this);
522 }
523 virtual int Opcode() const;
524 virtual const Type *bottom_type() const { return TypeInt::INT; }
525 virtual uint ideal_reg() const { return Op_RegI; }
526 virtual const Type* Value(PhaseGVN* phase) const;
527 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
528 virtual Node* Identity(PhaseGVN* phase);
529 };
530
531 // Support for strip mining
532 class OuterStripMinedLoopNode : public LoopNode {
533 private:
534 static void fix_sunk_stores(CountedLoopEndNode* inner_cle, LoopNode* inner_cl, PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
535
536 public:
537 OuterStripMinedLoopNode(Compile* C, Node *entry, Node *backedge)
538 : LoopNode(entry, backedge) {
539 init_class_id(Class_OuterStripMinedLoop);
540 init_flags(Flag_is_macro);
541 C->add_macro_node(this);
542 }
543
544 virtual int Opcode() const;
545
546 virtual IfTrueNode* outer_loop_tail() const;
547 virtual OuterStripMinedLoopEndNode* outer_loop_end() const;
548 virtual IfFalseNode* outer_loop_exit() const;
549 virtual SafePointNode* outer_safepoint() const;
550 void adjust_strip_mined_loop(PhaseIterGVN* igvn);
551
552 void remove_outer_loop_and_safepoint(PhaseIterGVN* igvn) const;
553
554 void transform_to_counted_loop(PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
555
556 static Node* register_new_node(Node* node, LoopNode* ctrl, PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
557
558 Node* register_control(Node* node, Node* loop, Node* idom, PhaseIterGVN* igvn,
559 PhaseIdealLoop* iloop);
560 };
561
562 class OuterStripMinedLoopEndNode : public IfNode {
563 public:
564 OuterStripMinedLoopEndNode(Node *control, Node *test, float prob, float cnt)
565 : IfNode(control, test, prob, cnt) {
566 init_class_id(Class_OuterStripMinedLoopEnd);
567 }
568
569 virtual int Opcode() const;
570
571 virtual const Type* Value(PhaseGVN* phase) const;
572 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
573
574 bool is_expanded(PhaseGVN *phase) const;
575 };
576
577 // -----------------------------IdealLoopTree----------------------------------
578 class IdealLoopTree : public ResourceObj {
579 public:
580 IdealLoopTree *_parent; // Parent in loop tree
581 IdealLoopTree *_next; // Next sibling in loop tree
582 IdealLoopTree *_child; // First child in loop tree
583
584 // The head-tail backedge defines the loop.
585 // If a loop has multiple backedges, this is addressed during cleanup where
586 // we peel off the multiple backedges, merging all edges at the bottom and
587 // ensuring that one proper backedge flow into the loop.
588 Node *_head; // Head of loop
589 Node *_tail; // Tail of loop
590 inline Node *tail(); // Handle lazy update of _tail field
591 inline Node *head(); // Handle lazy update of _head field
592 PhaseIdealLoop* _phase;
593 int _local_loop_unroll_limit;
594 int _local_loop_unroll_factor;
595
596 Node_List _body; // Loop body for inner loops
597
598 uint16_t _nest; // Nesting depth
599 uint8_t _irreducible:1, // True if irreducible
600 _has_call:1, // True if has call safepoint
601 _has_sfpt:1, // True if has non-call safepoint
602 _rce_candidate:1, // True if candidate for range check elimination
603 _has_range_checks:1,
604 _has_range_checks_computed:1;
605
606 Node_List* _safepts; // List of safepoints in this loop
607 Node_List* _required_safept; // A inner loop cannot delete these safepts;
608 bool _allow_optimizations; // Allow loop optimizations
609
610 IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail )
611 : _parent(0), _next(0), _child(0),
612 _head(head), _tail(tail),
613 _phase(phase),
614 _local_loop_unroll_limit(0), _local_loop_unroll_factor(0),
615 _nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0),
616 _has_range_checks(0), _has_range_checks_computed(0),
617 _safepts(nullptr),
618 _required_safept(nullptr),
619 _allow_optimizations(true)
620 {
621 precond(_head != nullptr);
622 precond(_tail != nullptr);
623 }
624
625 // Is 'l' a member of 'this'?
626 bool is_member(const IdealLoopTree *l) const; // Test for nested membership
627
628 // Set loop nesting depth. Accumulate has_call bits.
629 int set_nest( uint depth );
630
631 // Split out multiple fall-in edges from the loop header. Move them to a
632 // private RegionNode before the loop. This becomes the loop landing pad.
633 void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt );
634
635 // Split out the outermost loop from this shared header.
636 void split_outer_loop( PhaseIdealLoop *phase );
637
638 // Merge all the backedges from the shared header into a private Region.
639 // Feed that region as the one backedge to this loop.
640 void merge_many_backedges( PhaseIdealLoop *phase );
641
642 // Split shared headers and insert loop landing pads.
643 // Insert a LoopNode to replace the RegionNode.
644 // Returns TRUE if loop tree is structurally changed.
645 bool beautify_loops( PhaseIdealLoop *phase );
646
647 // Perform optimization to use the loop predicates for null checks and range checks.
648 // Applies to any loop level (not just the innermost one)
649 bool loop_predication( PhaseIdealLoop *phase);
650 bool can_apply_loop_predication();
651
652 // Perform iteration-splitting on inner loops. Split iterations to
653 // avoid range checks or one-shot null checks. Returns false if the
654 // current round of loop opts should stop.
655 bool iteration_split( PhaseIdealLoop *phase, Node_List &old_new );
656
657 // Driver for various flavors of iteration splitting. Returns false
658 // if the current round of loop opts should stop.
659 bool iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new );
660
661 // Given dominators, try to find loops with calls that must always be
662 // executed (call dominates loop tail). These loops do not need non-call
663 // safepoints (ncsfpt).
664 void check_safepts(VectorSet &visited, Node_List &stack);
665
666 // Allpaths backwards scan from loop tail, terminating each path at first safepoint
667 // encountered.
668 void allpaths_check_safepts(VectorSet &visited, Node_List &stack);
669
670 // Remove safepoints from loop. Optionally keeping one.
671 void remove_safepoints(PhaseIdealLoop* phase, bool keep_one);
672
673 // Convert to counted loops where possible
674 void counted_loop( PhaseIdealLoop *phase );
675
676 // Check for Node being a loop-breaking test
677 Node *is_loop_exit(Node *iff) const;
678
679 // Remove simplistic dead code from loop body
680 void DCE_loop_body();
681
682 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage.
683 // Replace with a 1-in-10 exit guess.
684 void adjust_loop_exit_prob( PhaseIdealLoop *phase );
685
686 // Return TRUE or FALSE if the loop should never be RCE'd or aligned.
687 // Useful for unrolling loops with NO array accesses.
688 bool policy_peel_only( PhaseIdealLoop *phase ) const;
689
690 // Return TRUE or FALSE if the loop should be unswitched -- clone
691 // loop with an invariant test
692 bool policy_unswitching( PhaseIdealLoop *phase ) const;
693
694 // Micro-benchmark spamming. Remove empty loops.
695 bool do_remove_empty_loop( PhaseIdealLoop *phase );
696
697 // Convert one iteration loop into normal code.
698 bool do_one_iteration_loop( PhaseIdealLoop *phase );
699
700 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can
701 // move some loop-invariant test (usually a null-check) before the loop.
702 bool policy_peeling(PhaseIdealLoop *phase);
703
704 uint estimate_peeling(PhaseIdealLoop *phase);
705
706 // Return TRUE or FALSE if the loop should be maximally unrolled. Stash any
707 // known trip count in the counted loop node.
708 bool policy_maximally_unroll(PhaseIdealLoop *phase) const;
709
710 // Return TRUE or FALSE if the loop should be unrolled or not. Apply unroll
711 // if the loop is a counted loop and the loop body is small enough.
712 bool policy_unroll(PhaseIdealLoop *phase);
713
714 // Loop analyses to map to a maximal superword unrolling for vectorization.
715 void policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_ct);
716
717 // Return TRUE or FALSE if the loop should be range-check-eliminated.
718 // Gather a list of IF tests that are dominated by iteration splitting;
719 // also gather the end of the first split and the start of the 2nd split.
720 bool policy_range_check(PhaseIdealLoop* phase, bool provisional, BasicType bt) const;
721
722 // Return TRUE if "iff" is a range check.
723 bool is_range_check_if(IfProjNode* if_success_proj, PhaseIdealLoop* phase, Invariance& invar DEBUG_ONLY(COMMA ProjNode* predicate_proj)) const;
724 bool is_range_check_if(IfProjNode* if_success_proj, PhaseIdealLoop* phase, BasicType bt, Node* iv, Node*& range, Node*& offset,
725 jlong& scale) const;
726
727 // Estimate the number of nodes required when cloning a loop (body).
728 uint est_loop_clone_sz(uint factor) const;
729 // Estimate the number of nodes required when unrolling a loop (body).
730 uint est_loop_unroll_sz(uint factor) const;
731
732 // Compute loop trip count if possible
733 void compute_trip_count(PhaseIdealLoop* phase);
734
735 // Compute loop trip count from profile data
736 float compute_profile_trip_cnt_helper(Node* n);
737 void compute_profile_trip_cnt( PhaseIdealLoop *phase );
738
739 // Reassociate invariant expressions.
740 void reassociate_invariants(PhaseIdealLoop *phase);
741 // Reassociate invariant binary expressions.
742 Node* reassociate(Node* n1, PhaseIdealLoop *phase);
743 // Reassociate invariant add and subtract expressions.
744 Node* reassociate_add_sub(Node* n1, int inv1_idx, int inv2_idx, PhaseIdealLoop *phase);
745 // Return nonzero index of invariant operand if invariant and variant
746 // are combined with an associative binary. Helper for reassociate_invariants.
747 int find_invariant(Node* n, PhaseIdealLoop *phase);
748 // Return TRUE if "n" is associative.
749 bool is_associative(Node* n, Node* base=nullptr);
750
751 // Return true if n is invariant
752 bool is_invariant(Node* n) const;
753
754 // Put loop body on igvn work list
755 void record_for_igvn();
756
757 bool is_root() { return _parent == nullptr; }
758 // A proper/reducible loop w/o any (occasional) dead back-edge.
759 bool is_loop() { return !_irreducible && !tail()->is_top(); }
760 bool is_counted() { return is_loop() && _head->is_CountedLoop(); }
761 bool is_innermost() { return is_loop() && _child == nullptr; }
762
763 void remove_main_post_loops(CountedLoopNode *cl, PhaseIdealLoop *phase);
764
765 bool compute_has_range_checks() const;
766 bool range_checks_present() {
767 if (!_has_range_checks_computed) {
768 if (compute_has_range_checks()) {
769 _has_range_checks = 1;
770 }
771 _has_range_checks_computed = 1;
772 }
773 return _has_range_checks;
774 }
775
776 #ifndef PRODUCT
777 void dump_head(); // Dump loop head only
778 void dump(); // Dump this loop recursively
779 #endif
780
781 #ifdef ASSERT
782 GrowableArray<IdealLoopTree*> collect_sorted_children() const;
783 bool verify_tree(IdealLoopTree* loop_verify) const;
784 #endif
785
786 private:
787 enum { EMPTY_LOOP_SIZE = 7 }; // Number of nodes in an empty loop.
788
789 // Estimate the number of nodes resulting from control and data flow merge.
790 uint est_loop_flow_merge_sz() const;
791
792 // Check if the number of residual iterations is large with unroll_cnt.
793 // Return true if the residual iterations are more than 10% of the trip count.
794 bool is_residual_iters_large(int unroll_cnt, CountedLoopNode *cl) const {
795 return (unroll_cnt - 1) * (100.0 / LoopPercentProfileLimit) > cl->profile_trip_cnt();
796 }
797
798 void collect_loop_core_nodes(PhaseIdealLoop* phase, Unique_Node_List& wq) const;
799
800 bool empty_loop_with_data_nodes(PhaseIdealLoop* phase) const;
801
802 void enqueue_data_nodes(PhaseIdealLoop* phase, Unique_Node_List& empty_loop_nodes, Unique_Node_List& wq) const;
803
804 bool process_safepoint(PhaseIdealLoop* phase, Unique_Node_List& empty_loop_nodes, Unique_Node_List& wq,
805 Node* sfpt) const;
806
807 bool empty_loop_candidate(PhaseIdealLoop* phase) const;
808
809 bool empty_loop_with_extra_nodes_candidate(PhaseIdealLoop* phase) const;
810 };
811
812 // -----------------------------PhaseIdealLoop---------------------------------
813 // Computes the mapping from Nodes to IdealLoopTrees. Organizes IdealLoopTrees
814 // into a loop tree. Drives the loop-based transformations on the ideal graph.
815 class PhaseIdealLoop : public PhaseTransform {
816 friend class IdealLoopTree;
817 friend class SuperWord;
818 friend class ShenandoahBarrierC2Support;
819 friend class AutoNodeBudget;
820
821 // Map loop membership for CFG nodes, and ctrl for non-CFG nodes.
822 Node_List _loop_or_ctrl;
823
824 // Pre-computed def-use info
825 PhaseIterGVN &_igvn;
826
827 // Head of loop tree
828 IdealLoopTree* _ltree_root;
829
830 // Array of pre-order numbers, plus post-visited bit.
831 // ZERO for not pre-visited. EVEN for pre-visited but not post-visited.
832 // ODD for post-visited. Other bits are the pre-order number.
833 uint *_preorders;
834 uint _max_preorder;
835
836 const PhaseIdealLoop* _verify_me;
837 bool _verify_only;
838
839 // Allocate _preorders[] array
840 void allocate_preorders() {
841 _max_preorder = C->unique()+8;
842 _preorders = NEW_RESOURCE_ARRAY(uint, _max_preorder);
843 memset(_preorders, 0, sizeof(uint) * _max_preorder);
844 }
845
846 // Allocate _preorders[] array
847 void reallocate_preorders() {
848 if ( _max_preorder < C->unique() ) {
849 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique());
850 _max_preorder = C->unique();
851 }
852 memset(_preorders, 0, sizeof(uint) * _max_preorder);
853 }
854
855 // Check to grow _preorders[] array for the case when build_loop_tree_impl()
856 // adds new nodes.
857 void check_grow_preorders( ) {
858 if ( _max_preorder < C->unique() ) {
859 uint newsize = _max_preorder<<1; // double size of array
860 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize);
861 memset(&_preorders[_max_preorder],0,sizeof(uint)*(newsize-_max_preorder));
862 _max_preorder = newsize;
863 }
864 }
865 // Check for pre-visited. Zero for NOT visited; non-zero for visited.
866 int is_visited( Node *n ) const { return _preorders[n->_idx]; }
867 // Pre-order numbers are written to the Nodes array as low-bit-set values.
868 void set_preorder_visited( Node *n, int pre_order ) {
869 assert( !is_visited( n ), "already set" );
870 _preorders[n->_idx] = (pre_order<<1);
871 };
872 // Return pre-order number.
873 int get_preorder( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]>>1; }
874
875 // Check for being post-visited.
876 // Should be previsited already (checked with assert(is_visited(n))).
877 int is_postvisited( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]&1; }
878
879 // Mark as post visited
880 void set_postvisited( Node *n ) { assert( !is_postvisited( n ), "" ); _preorders[n->_idx] |= 1; }
881
882 public:
883 // Set/get control node out. Set lower bit to distinguish from IdealLoopTree
884 // Returns true if "n" is a data node, false if it's a control node.
885 bool has_ctrl(const Node* n) const { return ((intptr_t)_loop_or_ctrl[n->_idx]) & 1; }
886
887 private:
888 // clear out dead code after build_loop_late
889 Node_List _deadlist;
890 Node_List _zero_trip_guard_opaque_nodes;
891
892 // Support for faster execution of get_late_ctrl()/dom_lca()
893 // when a node has many uses and dominator depth is deep.
894 GrowableArray<jlong> _dom_lca_tags;
895 uint _dom_lca_tags_round;
896 void init_dom_lca_tags();
897
898 // Helper for debugging bad dominance relationships
899 bool verify_dominance(Node* n, Node* use, Node* LCA, Node* early);
900
901 Node* compute_lca_of_uses(Node* n, Node* early, bool verify = false);
902
903 // Inline wrapper for frequent cases:
904 // 1) only one use
905 // 2) a use is the same as the current LCA passed as 'n1'
906 Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) {
907 assert( n->is_CFG(), "" );
908 // Fast-path null lca
909 if( lca != nullptr && lca != n ) {
910 assert( lca->is_CFG(), "" );
911 // find LCA of all uses
912 n = dom_lca_for_get_late_ctrl_internal( lca, n, tag );
913 }
914 return find_non_split_ctrl(n);
915 }
916 Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag );
917
918 // Helper function for directing control inputs away from CFG split points.
919 Node *find_non_split_ctrl( Node *ctrl ) const {
920 if (ctrl != nullptr) {
921 if (ctrl->is_MultiBranch()) {
922 ctrl = ctrl->in(0);
923 }
924 assert(ctrl->is_CFG(), "CFG");
925 }
926 return ctrl;
927 }
928
929 Node* cast_incr_before_loop(Node* incr, Node* ctrl, Node* loop);
930
931 #ifdef ASSERT
932 void ensure_zero_trip_guard_proj(Node* node, bool is_main_loop);
933 #endif
934 void copy_assertion_predicates_to_main_loop_helper(const PredicateBlock* predicate_block, Node* init, Node* stride,
935 IdealLoopTree* outer_loop, LoopNode* outer_main_head,
936 uint dd_main_head, uint idx_before_pre_post,
937 uint idx_after_post_before_pre, Node* zero_trip_guard_proj_main,
938 Node* zero_trip_guard_proj_post, const Node_List &old_new);
939 void copy_assertion_predicates_to_main_loop(CountedLoopNode* pre_head, Node* init, Node* stride, IdealLoopTree* outer_loop,
940 LoopNode* outer_main_head, uint dd_main_head, uint idx_before_pre_post,
941 uint idx_after_post_before_pre, Node* zero_trip_guard_proj_main,
942 Node* zero_trip_guard_proj_post, const Node_List& old_new);
943 Node* clone_assertion_predicate_and_initialize(Node* iff, Node* new_init, Node* new_stride, Node* predicate,
944 Node* uncommon_proj, Node* control, IdealLoopTree* outer_loop,
945 Node* input_proj);
946 static void count_opaque_loop_nodes(Node* n, uint& init, uint& stride);
947 static bool subgraph_has_opaque(Node* n);
948 Node* create_bool_from_template_assertion_predicate(Node* template_assertion_predicate, Node* new_init, Node* new_stride,
949 Node* control);
950 static bool assertion_predicate_has_loop_opaque_node(IfNode* iff);
951 static void get_assertion_predicates(Node* predicate, Unique_Node_List& list, bool get_opaque = false);
952 void update_main_loop_assertion_predicates(Node* ctrl, CountedLoopNode* loop_head, Node* init, int stride_con);
953 void copy_assertion_predicates_to_post_loop(LoopNode* main_loop_head, CountedLoopNode* post_loop_head, Node* init,
954 Node* stride);
955 void initialize_assertion_predicates_for_peeled_loop(const PredicateBlock* predicate_block, LoopNode* outer_loop_head,
956 int dd_outer_loop_head, Node* init, Node* stride,
957 IdealLoopTree* outer_loop, uint idx_before_clone,
958 const Node_List& old_new);
959 void insert_loop_limit_check_predicate(ParsePredicateSuccessProj* loop_limit_check_parse_proj, Node* cmp_limit,
960 Node* bol);
961 #ifdef ASSERT
962 bool only_has_infinite_loops();
963 #endif
964
965 void log_loop_tree();
966
967 public:
968
969 PhaseIterGVN &igvn() const { return _igvn; }
970
971 bool has_node(const Node* n) const {
972 guarantee(n != nullptr, "No Node.");
973 return _loop_or_ctrl[n->_idx] != nullptr;
974 }
975 // check if transform created new nodes that need _ctrl recorded
976 Node *get_late_ctrl( Node *n, Node *early );
977 Node *get_early_ctrl( Node *n );
978 Node *get_early_ctrl_for_expensive(Node *n, Node* earliest);
979 void set_early_ctrl(Node* n, bool update_body);
980 void set_subtree_ctrl(Node* n, bool update_body);
981 void set_ctrl( Node *n, Node *ctrl ) {
982 assert( !has_node(n) || has_ctrl(n), "" );
983 assert( ctrl->in(0), "cannot set dead control node" );
984 assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" );
985 _loop_or_ctrl.map(n->_idx, (Node*)((intptr_t)ctrl + 1));
986 }
987 // Set control and update loop membership
988 void set_ctrl_and_loop(Node* n, Node* ctrl) {
989 IdealLoopTree* old_loop = get_loop(get_ctrl(n));
990 IdealLoopTree* new_loop = get_loop(ctrl);
991 if (old_loop != new_loop) {
992 if (old_loop->_child == nullptr) old_loop->_body.yank(n);
993 if (new_loop->_child == nullptr) new_loop->_body.push(n);
994 }
995 set_ctrl(n, ctrl);
996 }
997 // Control nodes can be replaced or subsumed. During this pass they
998 // get their replacement Node in slot 1. Instead of updating the block
999 // location of all Nodes in the subsumed block, we lazily do it. As we
1000 // pull such a subsumed block out of the array, we write back the final
1001 // correct block.
1002 Node* get_ctrl(const Node* i) {
1003 assert(has_node(i), "");
1004 Node *n = get_ctrl_no_update(i);
1005 _loop_or_ctrl.map(i->_idx, (Node*)((intptr_t)n + 1));
1006 assert(has_node(i) && has_ctrl(i), "");
1007 assert(n == find_non_split_ctrl(n), "must return legal ctrl" );
1008 return n;
1009 }
1010 // true if CFG node d dominates CFG node n
1011 bool is_dominator(Node *d, Node *n);
1012 // return get_ctrl for a data node and self(n) for a CFG node
1013 Node* ctrl_or_self(Node* n) {
1014 if (has_ctrl(n))
1015 return get_ctrl(n);
1016 else {
1017 assert (n->is_CFG(), "must be a CFG node");
1018 return n;
1019 }
1020 }
1021
1022 Node* get_ctrl_no_update_helper(const Node* i) const {
1023 assert(has_ctrl(i), "should be control, not loop");
1024 return (Node*)(((intptr_t)_loop_or_ctrl[i->_idx]) & ~1);
1025 }
1026
1027 Node* get_ctrl_no_update(const Node* i) const {
1028 assert( has_ctrl(i), "" );
1029 Node *n = get_ctrl_no_update_helper(i);
1030 if (!n->in(0)) {
1031 // Skip dead CFG nodes
1032 do {
1033 n = get_ctrl_no_update_helper(n);
1034 } while (!n->in(0));
1035 n = find_non_split_ctrl(n);
1036 }
1037 return n;
1038 }
1039
1040 // Check for loop being set
1041 // "n" must be a control node. Returns true if "n" is known to be in a loop.
1042 bool has_loop( Node *n ) const {
1043 assert(!has_node(n) || !has_ctrl(n), "");
1044 return has_node(n);
1045 }
1046 // Set loop
1047 void set_loop( Node *n, IdealLoopTree *loop ) {
1048 _loop_or_ctrl.map(n->_idx, (Node*)loop);
1049 }
1050 // Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms. Replace
1051 // the 'old_node' with 'new_node'. Kill old-node. Add a reference
1052 // from old_node to new_node to support the lazy update. Reference
1053 // replaces loop reference, since that is not needed for dead node.
1054 void lazy_update(Node *old_node, Node *new_node) {
1055 assert(old_node != new_node, "no cycles please");
1056 // Re-use the side array slot for this node to provide the
1057 // forwarding pointer.
1058 _loop_or_ctrl.map(old_node->_idx, (Node*)((intptr_t)new_node + 1));
1059 }
1060 void lazy_replace(Node *old_node, Node *new_node) {
1061 _igvn.replace_node(old_node, new_node);
1062 lazy_update(old_node, new_node);
1063 }
1064
1065 private:
1066
1067 // Place 'n' in some loop nest, where 'n' is a CFG node
1068 void build_loop_tree();
1069 int build_loop_tree_impl( Node *n, int pre_order );
1070 // Insert loop into the existing loop tree. 'innermost' is a leaf of the
1071 // loop tree, not the root.
1072 IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost );
1073
1074 #ifdef ASSERT
1075 // verify that regions in irreducible loops are marked is_in_irreducible_loop
1076 void verify_regions_in_irreducible_loops();
1077 bool is_in_irreducible_loop(RegionNode* region);
1078 #endif
1079
1080 // Place Data nodes in some loop nest
1081 void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
1082 void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
1083 void build_loop_late_post_work(Node* n, bool pinned);
1084 void build_loop_late_post(Node* n);
1085 void verify_strip_mined_scheduling(Node *n, Node* least);
1086
1087 // Array of immediate dominance info for each CFG node indexed by node idx
1088 private:
1089 uint _idom_size;
1090 Node **_idom; // Array of immediate dominators
1091 uint *_dom_depth; // Used for fast LCA test
1092 GrowableArray<uint>* _dom_stk; // For recomputation of dom depth
1093 LoopOptsMode _mode;
1094
1095 // build the loop tree and perform any requested optimizations
1096 void build_and_optimize();
1097
1098 // Dominators for the sea of nodes
1099 void Dominators();
1100
1101 // Compute the Ideal Node to Loop mapping
1102 PhaseIdealLoop(PhaseIterGVN& igvn, LoopOptsMode mode) :
1103 PhaseTransform(Ideal_Loop),
1104 _loop_or_ctrl(igvn.C->comp_arena()),
1105 _igvn(igvn),
1106 _verify_me(nullptr),
1107 _verify_only(false),
1108 _mode(mode),
1109 _nodes_required(UINT_MAX) {
1110 assert(mode != LoopOptsVerify, "wrong constructor to verify IdealLoop");
1111 build_and_optimize();
1112 }
1113
1114 #ifndef PRODUCT
1115 // Verify that verify_me made the same decisions as a fresh run
1116 // or only verify that the graph is valid if verify_me is null.
1117 PhaseIdealLoop(PhaseIterGVN& igvn, const PhaseIdealLoop* verify_me = nullptr) :
1118 PhaseTransform(Ideal_Loop),
1119 _loop_or_ctrl(igvn.C->comp_arena()),
1120 _igvn(igvn),
1121 _verify_me(verify_me),
1122 _verify_only(verify_me == nullptr),
1123 _mode(LoopOptsVerify),
1124 _nodes_required(UINT_MAX) {
1125 build_and_optimize();
1126 }
1127 #endif
1128
1129 public:
1130 Node* idom_no_update(Node* d) const {
1131 return idom_no_update(d->_idx);
1132 }
1133
1134 Node* idom_no_update(uint didx) const {
1135 assert(didx < _idom_size, "oob");
1136 Node* n = _idom[didx];
1137 assert(n != nullptr,"Bad immediate dominator info.");
1138 while (n->in(0) == nullptr) { // Skip dead CFG nodes
1139 n = (Node*)(((intptr_t)_loop_or_ctrl[n->_idx]) & ~1);
1140 assert(n != nullptr,"Bad immediate dominator info.");
1141 }
1142 return n;
1143 }
1144
1145 Node *idom(Node* d) const {
1146 return idom(d->_idx);
1147 }
1148
1149 Node *idom(uint didx) const {
1150 Node *n = idom_no_update(didx);
1151 _idom[didx] = n; // Lazily remove dead CFG nodes from table.
1152 return n;
1153 }
1154
1155 uint dom_depth(Node* d) const {
1156 guarantee(d != nullptr, "Null dominator info.");
1157 guarantee(d->_idx < _idom_size, "");
1158 return _dom_depth[d->_idx];
1159 }
1160 void set_idom(Node* d, Node* n, uint dom_depth);
1161 // Locally compute IDOM using dom_lca call
1162 Node *compute_idom( Node *region ) const;
1163 // Recompute dom_depth
1164 void recompute_dom_depth();
1165
1166 // Is safept not required by an outer loop?
1167 bool is_deleteable_safept(Node* sfpt);
1168
1169 // Replace parallel induction variable (parallel to trip counter)
1170 void replace_parallel_iv(IdealLoopTree *loop);
1171
1172 Node *dom_lca( Node *n1, Node *n2 ) const {
1173 return find_non_split_ctrl(dom_lca_internal(n1, n2));
1174 }
1175 Node *dom_lca_internal( Node *n1, Node *n2 ) const;
1176
1177 // Build and verify the loop tree without modifying the graph. This
1178 // is useful to verify that all inputs properly dominate their uses.
1179 static void verify(PhaseIterGVN& igvn) {
1180 #ifdef ASSERT
1181 ResourceMark rm;
1182 Compile::TracePhase tp("idealLoopVerify", &timers[_t_idealLoopVerify]);
1183 PhaseIdealLoop v(igvn);
1184 #endif
1185 }
1186
1187 // Recommended way to use PhaseIdealLoop.
1188 // Run PhaseIdealLoop in some mode and allocates a local scope for memory allocations.
1189 static void optimize(PhaseIterGVN &igvn, LoopOptsMode mode) {
1190 ResourceMark rm;
1191 PhaseIdealLoop v(igvn, mode);
1192
1193 Compile* C = Compile::current();
1194 if (!C->failing()) {
1195 // Cleanup any modified bits
1196 igvn.optimize();
1197 if (C->failing()) { return; }
1198 v.log_loop_tree();
1199 }
1200 }
1201
1202 // True if the method has at least 1 irreducible loop
1203 bool _has_irreducible_loops;
1204
1205 // Per-Node transform
1206 virtual Node* transform(Node* n) { return nullptr; }
1207
1208 Node* loop_exit_control(Node* x, IdealLoopTree* loop);
1209 Node* loop_exit_test(Node* back_control, IdealLoopTree* loop, Node*& incr, Node*& limit, BoolTest::mask& bt, float& cl_prob);
1210 Node* loop_iv_incr(Node* incr, Node* x, IdealLoopTree* loop, Node*& phi_incr);
1211 Node* loop_iv_stride(Node* incr, IdealLoopTree* loop, Node*& xphi);
1212 PhiNode* loop_iv_phi(Node* xphi, Node* phi_incr, Node* x, IdealLoopTree* loop);
1213
1214 bool is_counted_loop(Node* x, IdealLoopTree*&loop, BasicType iv_bt);
1215
1216 Node* loop_nest_replace_iv(Node* iv_to_replace, Node* inner_iv, Node* outer_phi, Node* inner_head, BasicType bt);
1217 bool create_loop_nest(IdealLoopTree* loop, Node_List &old_new);
1218 #ifdef ASSERT
1219 bool convert_to_long_loop(Node* cmp, Node* phi, IdealLoopTree* loop);
1220 #endif
1221 void add_parse_predicate(Deoptimization::DeoptReason reason, Node* inner_head, IdealLoopTree* loop, SafePointNode* sfpt);
1222 SafePointNode* find_safepoint(Node* back_control, Node* x, IdealLoopTree* loop);
1223 IdealLoopTree* insert_outer_loop(IdealLoopTree* loop, LoopNode* outer_l, Node* outer_ift);
1224 IdealLoopTree* create_outer_strip_mined_loop(BoolNode *test, Node *cmp, Node *init_control,
1225 IdealLoopTree* loop, float cl_prob, float le_fcnt,
1226 Node*& entry_control, Node*& iffalse);
1227
1228 Node* exact_limit( IdealLoopTree *loop );
1229
1230 // Return a post-walked LoopNode
1231 IdealLoopTree *get_loop( Node *n ) const {
1232 // Dead nodes have no loop, so return the top level loop instead
1233 if (!has_node(n)) return _ltree_root;
1234 assert(!has_ctrl(n), "");
1235 return (IdealLoopTree*)_loop_or_ctrl[n->_idx];
1236 }
1237
1238 IdealLoopTree* ltree_root() const { return _ltree_root; }
1239
1240 // Is 'n' a (nested) member of 'loop'?
1241 int is_member( const IdealLoopTree *loop, Node *n ) const {
1242 return loop->is_member(get_loop(n)); }
1243
1244 // This is the basic building block of the loop optimizations. It clones an
1245 // entire loop body. It makes an old_new loop body mapping; with this
1246 // mapping you can find the new-loop equivalent to an old-loop node. All
1247 // new-loop nodes are exactly equal to their old-loop counterparts, all
1248 // edges are the same. All exits from the old-loop now have a RegionNode
1249 // that merges the equivalent new-loop path. This is true even for the
1250 // normal "loop-exit" condition. All uses of loop-invariant old-loop values
1251 // now come from (one or more) Phis that merge their new-loop equivalents.
1252 // Parameter side_by_side_idom:
1253 // When side_by_size_idom is null, the dominator tree is constructed for
1254 // the clone loop to dominate the original. Used in construction of
1255 // pre-main-post loop sequence.
1256 // When nonnull, the clone and original are side-by-side, both are
1257 // dominated by the passed in side_by_side_idom node. Used in
1258 // construction of unswitched loops.
1259 enum CloneLoopMode {
1260 IgnoreStripMined = 0, // Only clone inner strip mined loop
1261 CloneIncludesStripMined = 1, // clone both inner and outer strip mined loops
1262 ControlAroundStripMined = 2 // Only clone inner strip mined loop,
1263 // result control flow branches
1264 // either to inner clone or outer
1265 // strip mined loop.
1266 };
1267 void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth,
1268 CloneLoopMode mode, Node* side_by_side_idom = nullptr);
1269 void clone_loop_handle_data_uses(Node* old, Node_List &old_new,
1270 IdealLoopTree* loop, IdealLoopTree* companion_loop,
1271 Node_List*& split_if_set, Node_List*& split_bool_set,
1272 Node_List*& split_cex_set, Node_List& worklist,
1273 uint new_counter, CloneLoopMode mode);
1274 void clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
1275 IdealLoopTree* outer_loop, int dd, Node_List &old_new,
1276 Node_List& extra_data_nodes);
1277
1278 // If we got the effect of peeling, either by actually peeling or by
1279 // making a pre-loop which must execute at least once, we can remove
1280 // all loop-invariant dominated tests in the main body.
1281 void peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new );
1282
1283 // Generate code to do a loop peel for the given loop (and body).
1284 // old_new is a temp array.
1285 void do_peeling( IdealLoopTree *loop, Node_List &old_new );
1286
1287 // Add pre and post loops around the given loop. These loops are used
1288 // during RCE, unrolling and aligning loops.
1289 void insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only );
1290
1291 // Add post loop after the given loop.
1292 Node *insert_post_loop(IdealLoopTree* loop, Node_List& old_new,
1293 CountedLoopNode* main_head, CountedLoopEndNode* main_end,
1294 Node*& incr, Node* limit, CountedLoopNode*& post_head);
1295
1296 // Add a vector post loop between a vector main loop and the current post loop
1297 void insert_vector_post_loop(IdealLoopTree *loop, Node_List &old_new);
1298 // If Node n lives in the back_ctrl block, we clone a private version of n
1299 // in preheader_ctrl block and return that, otherwise return n.
1300 Node *clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones );
1301
1302 // Take steps to maximally unroll the loop. Peel any odd iterations, then
1303 // unroll to do double iterations. The next round of major loop transforms
1304 // will repeat till the doubled loop body does all remaining iterations in 1
1305 // pass.
1306 void do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new );
1307
1308 // Unroll the loop body one step - make each trip do 2 iterations.
1309 void do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip );
1310
1311 // Return true if exp is a constant times an induction var
1312 bool is_scaled_iv(Node* exp, Node* iv, BasicType bt, jlong* p_scale, bool* p_short_scale, int depth = 0);
1313
1314 bool is_iv(Node* exp, Node* iv, BasicType bt);
1315
1316 // Return true if exp is a scaled induction var plus (or minus) constant
1317 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);
1318 bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset) {
1319 jlong long_scale;
1320 if (is_scaled_iv_plus_offset(exp, iv, T_INT, &long_scale, p_offset)) {
1321 int int_scale = checked_cast<int>(long_scale);
1322 if (p_scale != nullptr) {
1323 *p_scale = int_scale;
1324 }
1325 return true;
1326 }
1327 return false;
1328 }
1329 // Helper for finding more complex matches to is_scaled_iv_plus_offset.
1330 bool is_scaled_iv_plus_extra_offset(Node* exp1, Node* offset2, Node* iv,
1331 BasicType bt,
1332 jlong* p_scale, Node** p_offset,
1333 bool* p_short_scale, int depth);
1334
1335 // Create a new if above the uncommon_trap_if_pattern for the predicate to be promoted
1336 IfProjNode* create_new_if_for_predicate(ParsePredicateSuccessProj* parse_predicate_proj, Node* new_entry,
1337 Deoptimization::DeoptReason reason, int opcode,
1338 bool rewire_uncommon_proj_phi_inputs = false);
1339
1340 private:
1341 // Helper functions for create_new_if_for_predicate()
1342 void set_ctrl_of_nodes_with_same_ctrl(Node* node, ProjNode* old_ctrl, Node* new_ctrl);
1343 Unique_Node_List find_nodes_with_same_ctrl(Node* node, const ProjNode* ctrl);
1344 Node* clone_nodes_with_same_ctrl(Node* node, ProjNode* old_ctrl, Node* new_ctrl);
1345 Dict clone_nodes(const Node_List& list_to_clone);
1346 void rewire_cloned_nodes_to_ctrl(const ProjNode* old_ctrl, Node* new_ctrl, const Node_List& nodes_with_same_ctrl,
1347 const Dict& old_new_mapping);
1348 void rewire_inputs_of_clones_to_clones(Node* new_ctrl, Node* clone, const Dict& old_new_mapping, const Node* next);
1349 bool has_dominating_loop_limit_check(Node* init_trip, Node* limit, jlong stride_con, BasicType iv_bt,
1350 Node* loop_entry);
1351
1352 public:
1353 void register_control(Node* n, IdealLoopTree *loop, Node* pred, bool update_body = true);
1354
1355 // Construct a range check for a predicate if
1356 BoolNode* rc_predicate(IdealLoopTree* loop, Node* ctrl, int scale, Node* offset, Node* init, Node* limit,
1357 jint stride, Node* range, bool upper, bool& overflow);
1358
1359 // Implementation of the loop predication to promote checks outside the loop
1360 bool loop_predication_impl(IdealLoopTree *loop);
1361
1362 private:
1363 bool loop_predication_impl_helper(IdealLoopTree* loop, IfProjNode* if_success_proj,
1364 ParsePredicateSuccessProj* parse_predicate_proj, CountedLoopNode* cl, ConNode* zero,
1365 Invariance& invar, Deoptimization::DeoptReason reason);
1366 bool can_create_loop_predicates(const PredicateBlock* profiled_loop_predicate_block) const;
1367 bool loop_predication_should_follow_branches(IdealLoopTree* loop, 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,
1372 ParsePredicateSuccessProj* parse_predicate_proj,
1373 IfProjNode* upper_bound_proj, int scale, Node* offset, Node* init, Node* limit,
1374 jint stride, Node* rng, bool& overflow, Deoptimization::DeoptReason reason);
1375 Node* add_range_check_elimination_assertion_predicate(IdealLoopTree* loop, Node* predicate_proj, int scale_con,
1376 Node* offset, Node* limit, jint stride_con, Node* value);
1377
1378 // Helper function to collect predicate for eliminating the useless ones
1379 void eliminate_useless_predicates();
1380
1381 void eliminate_useless_parse_predicates();
1382 void mark_all_parse_predicates_useless() const;
1383 void mark_loop_associated_parse_predicates_useful();
1384 static void mark_useful_parse_predicates_for_loop(IdealLoopTree* loop);
1385 void add_useless_parse_predicates_to_igvn_worklist();
1386
1387 void eliminate_useless_template_assertion_predicates();
1388 void collect_useful_template_assertion_predicates(Unique_Node_List& useful_predicates);
1389 static void collect_useful_template_assertion_predicates_for_loop(IdealLoopTree* loop, Unique_Node_List& useful_predicates);
1390 void eliminate_useless_template_assertion_predicates(Unique_Node_List& useful_predicates);
1391
1392 void eliminate_useless_zero_trip_guard();
1393
1394 bool has_control_dependencies_from_predicates(LoopNode* head) const;
1395 void verify_fast_loop(LoopNode* head, const ProjNode* proj_true) const NOT_DEBUG_RETURN;
1396 public:
1397 // Change the control input of expensive nodes to allow commoning by
1398 // IGVN when it is guaranteed to not result in a more frequent
1399 // execution of the expensive node. Return true if progress.
1400 bool process_expensive_nodes();
1401
1402 // Check whether node has become unreachable
1403 bool is_node_unreachable(Node *n) const {
1404 return !has_node(n) || n->is_unreachable(_igvn);
1405 }
1406
1407 // Eliminate range-checks and other trip-counter vs loop-invariant tests.
1408 void do_range_check(IdealLoopTree *loop, Node_List &old_new);
1409
1410 // Create a slow version of the loop by cloning the loop
1411 // and inserting an if to select fast-slow versions.
1412 // Return the inserted if.
1413 IfNode* create_slow_version_of_loop(IdealLoopTree *loop,
1414 Node_List &old_new,
1415 Node_List &unswitch_iffs,
1416 CloneLoopMode mode);
1417
1418 // Clone loop with an invariant test (that does not exit) and
1419 // insert a clone of the test that selects which version to
1420 // execute.
1421 void do_unswitching (IdealLoopTree *loop, Node_List &old_new);
1422
1423 // Find candidate "if" for unswitching
1424 IfNode* find_unswitching_candidate(const IdealLoopTree *loop, Node_List& unswitch_iffs) const;
1425
1426 // Range Check Elimination uses this function!
1427 // Constrain the main loop iterations so the affine function:
1428 // low_limit <= scale_con * I + offset < upper_limit
1429 // always holds true. That is, either increase the number of iterations in
1430 // the pre-loop or the post-loop until the condition holds true in the main
1431 // loop. Scale_con, offset and limit are all loop invariant.
1432 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);
1433 // Helper function for add_constraint().
1434 Node* adjust_limit(bool reduce, Node* scale, Node* offset, Node* rc_limit, Node* old_limit, Node* pre_ctrl, bool round);
1435
1436 // Partially peel loop up through last_peel node.
1437 bool partial_peel( IdealLoopTree *loop, Node_List &old_new );
1438 bool duplicate_loop_backedge(IdealLoopTree *loop, Node_List &old_new);
1439
1440 // AutoVectorize the loop: replace scalar ops with vector ops.
1441 enum AutoVectorizeStatus {
1442 Impossible, // This loop has the wrong shape to even try vectorization.
1443 Success, // We just successfully vectorized the loop.
1444 TriedAndFailed, // We tried to vectorize, but failed.
1445 };
1446 AutoVectorizeStatus auto_vectorize(IdealLoopTree* lpt, VSharedData &vshared);
1447
1448 // Move UnorderedReduction out of loop if possible
1449 void move_unordered_reduction_out_of_loop(IdealLoopTree* loop);
1450
1451 // Create a scheduled list of nodes control dependent on ctrl set.
1452 void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched );
1453 // Has a use in the vector set
1454 bool has_use_in_set( Node* n, VectorSet& vset );
1455 // Has use internal to the vector set (ie. not in a phi at the loop head)
1456 bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop );
1457 // clone "n" for uses that are outside of loop
1458 int clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist );
1459 // clone "n" for special uses that are in the not_peeled region
1460 void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
1461 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist );
1462 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
1463 void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp );
1464 #ifdef ASSERT
1465 // Validate the loop partition sets: peel and not_peel
1466 bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel );
1467 // Ensure that uses outside of loop are of the right form
1468 bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
1469 uint orig_exit_idx, uint clone_exit_idx);
1470 bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx);
1471 #endif
1472
1473 // Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.)
1474 int stride_of_possible_iv( Node* iff );
1475 bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; }
1476 // Return the (unique) control output node that's in the loop (if it exists.)
1477 Node* stay_in_loop( Node* n, IdealLoopTree *loop);
1478 // Insert a signed compare loop exit cloned from an unsigned compare.
1479 IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop);
1480 void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop);
1481 // Utility to register node "n" with PhaseIdealLoop
1482 void register_node(Node* n, IdealLoopTree* loop, Node* pred, uint ddepth);
1483 // Utility to create an if-projection
1484 ProjNode* proj_clone(ProjNode* p, IfNode* iff);
1485 // Force the iff control output to be the live_proj
1486 Node* short_circuit_if(IfNode* iff, ProjNode* live_proj);
1487 // Insert a region before an if projection
1488 RegionNode* insert_region_before_proj(ProjNode* proj);
1489 // Insert a new if before an if projection
1490 ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj);
1491
1492 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1493 // "Nearly" because all Nodes have been cloned from the original in the loop,
1494 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1495 // through the Phi recursively, and return a Bool.
1496 Node* clone_iff(PhiNode* phi);
1497 CmpNode* clone_bool(PhiNode* phi);
1498
1499
1500 // Rework addressing expressions to get the most loop-invariant stuff
1501 // moved out. We'd like to do all associative operators, but it's especially
1502 // important (common) to do address expressions.
1503 Node* remix_address_expressions(Node* n);
1504 Node* remix_address_expressions_add_left_shift(Node* n, IdealLoopTree* n_loop, Node* n_ctrl, BasicType bt);
1505
1506 // Convert add to muladd to generate MuladdS2I under certain criteria
1507 Node * convert_add_to_muladd(Node * n);
1508
1509 // Attempt to use a conditional move instead of a phi/branch
1510 Node *conditional_move( Node *n );
1511
1512 // Check for aggressive application of 'split-if' optimization,
1513 // using basic block level info.
1514 void split_if_with_blocks ( VectorSet &visited, Node_Stack &nstack);
1515 Node *split_if_with_blocks_pre ( Node *n );
1516 void split_if_with_blocks_post( Node *n );
1517 Node *has_local_phi_input( Node *n );
1518 // Mark an IfNode as being dominated by a prior test,
1519 // without actually altering the CFG (and hence IDOM info).
1520 void dominated_by(IfProjNode* prevdom, IfNode* iff, bool flip = false, bool pin_array_access_nodes = false);
1521
1522 // Split Node 'n' through merge point
1523 RegionNode* split_thru_region(Node* n, RegionNode* region);
1524 // Split Node 'n' through merge point if there is enough win.
1525 Node *split_thru_phi( Node *n, Node *region, int policy );
1526 // Found an If getting its condition-code input from a Phi in the
1527 // same block. Split thru the Region.
1528 void do_split_if(Node *iff, RegionNode** new_false_region = nullptr, RegionNode** new_true_region = nullptr);
1529
1530 // Conversion of fill/copy patterns into intrinsic versions
1531 bool do_intrinsify_fill();
1532 bool intrinsify_fill(IdealLoopTree* lpt);
1533 bool match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value,
1534 Node*& shift, Node*& offset);
1535
1536 private:
1537 // Return a type based on condition control flow
1538 const TypeInt* filtered_type( Node *n, Node* n_ctrl);
1539 const TypeInt* filtered_type( Node *n ) { return filtered_type(n, nullptr); }
1540 // Helpers for filtered type
1541 const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl);
1542
1543 // Helper functions
1544 Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache );
1545 Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true );
1546 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 );
1547 bool split_up( Node *n, Node *blk1, Node *blk2 );
1548
1549 Node* place_outside_loop(Node* useblock, IdealLoopTree* loop) const;
1550 Node* try_move_store_before_loop(Node* n, Node *n_ctrl);
1551 void try_move_store_after_loop(Node* n);
1552 void move_flat_array_check_out_of_loop(Node* n);
1553 bool identical_backtoback_ifs(Node *n);
1554 bool flat_array_element_type_check(Node *n);
1555 bool can_split_if(Node *n_ctrl);
1556 bool cannot_split_division(const Node* n, const Node* region) const;
1557 static bool is_divisor_counted_loop_phi(const Node* divisor, const Node* loop);
1558 bool loop_phi_backedge_type_contains_zero(const Node* phi_divisor, const Type* zero) const;
1559
1560 // Determine if a method is too big for a/another round of split-if, based on
1561 // a magic (approximate) ratio derived from the equally magic constant 35000,
1562 // previously used for this purpose (but without relating to the node limit).
1563 bool must_throttle_split_if() {
1564 uint threshold = C->max_node_limit() * 2 / 5;
1565 return C->live_nodes() > threshold;
1566 }
1567
1568 // A simplistic node request tracking mechanism, where
1569 // = UINT_MAX Request not valid or made final.
1570 // < UINT_MAX Nodes currently requested (estimate).
1571 uint _nodes_required;
1572
1573 enum { REQUIRE_MIN = 70 };
1574
1575 uint nodes_required() const { return _nodes_required; }
1576
1577 // Given the _currently_ available number of nodes, check whether there is
1578 // "room" for an additional request or not, considering the already required
1579 // number of nodes. Return TRUE if the new request is exceeding the node
1580 // budget limit, otherwise return FALSE. Note that this interpretation will
1581 // act pessimistic on additional requests when new nodes have already been
1582 // generated since the 'begin'. This behaviour fits with the intention that
1583 // node estimates/requests should be made upfront.
1584 bool exceeding_node_budget(uint required = 0) {
1585 assert(C->live_nodes() < C->max_node_limit(), "sanity");
1586 uint available = C->max_node_limit() - C->live_nodes();
1587 return available < required + _nodes_required + REQUIRE_MIN;
1588 }
1589
1590 uint require_nodes(uint require, uint minreq = REQUIRE_MIN) {
1591 precond(require > 0);
1592 _nodes_required += MAX2(require, minreq);
1593 return _nodes_required;
1594 }
1595
1596 bool may_require_nodes(uint require, uint minreq = REQUIRE_MIN) {
1597 return !exceeding_node_budget(require) && require_nodes(require, minreq) > 0;
1598 }
1599
1600 uint require_nodes_begin() {
1601 assert(_nodes_required == UINT_MAX, "Bad state (begin).");
1602 _nodes_required = 0;
1603 return C->live_nodes();
1604 }
1605
1606 // When a node request is final, optionally check that the requested number
1607 // of nodes was reasonably correct with respect to the number of new nodes
1608 // introduced since the last 'begin'. Always check that we have not exceeded
1609 // the maximum node limit.
1610 void require_nodes_final(uint live_at_begin, bool check_estimate) {
1611 assert(_nodes_required < UINT_MAX, "Bad state (final).");
1612
1613 #ifdef ASSERT
1614 if (check_estimate) {
1615 // Check that the node budget request was not off by too much (x2).
1616 // Should this be the case we _surely_ need to improve the estimates
1617 // used in our budget calculations.
1618 if (C->live_nodes() - live_at_begin > 2 * _nodes_required) {
1619 log_info(compilation)("Bad node estimate: actual = %d >> request = %d",
1620 C->live_nodes() - live_at_begin, _nodes_required);
1621 }
1622 }
1623 #endif
1624 // Assert that we have stayed within the node budget limit.
1625 assert(C->live_nodes() < C->max_node_limit(),
1626 "Exceeding node budget limit: %d + %d > %d (request = %d)",
1627 C->live_nodes() - live_at_begin, live_at_begin,
1628 C->max_node_limit(), _nodes_required);
1629
1630 _nodes_required = UINT_MAX;
1631 }
1632
1633 // Clone Parse Predicates to slow and fast loop when unswitching a loop
1634 void clone_parse_and_assertion_predicates_to_unswitched_loop(IdealLoopTree* loop, Node_List& old_new,
1635 IfProjNode*& iffast_pred, IfProjNode*& ifslow_pred);
1636 void clone_loop_predication_predicates_to_unswitched_loop(IdealLoopTree* loop, const Node_List& old_new,
1637 const PredicateBlock* predicate_block,
1638 Deoptimization::DeoptReason reason, IfProjNode*& iffast_pred,
1639 IfProjNode*& ifslow_pred);
1640 void clone_parse_predicate_to_unswitched_loops(const PredicateBlock* predicate_block, Deoptimization::DeoptReason reason,
1641 IfProjNode*& iffast_pred, IfProjNode*& ifslow_pred);
1642 IfProjNode* clone_parse_predicate_to_unswitched_loop(ParsePredicateSuccessProj* parse_predicate_proj, Node* new_entry,
1643 Deoptimization::DeoptReason reason, bool slow_loop);
1644 void clone_assertion_predicates_to_unswitched_loop(IdealLoopTree* loop, const Node_List& old_new,
1645 Deoptimization::DeoptReason reason, IfProjNode* old_predicate_proj,
1646 ParsePredicateSuccessProj* fast_loop_parse_predicate_proj,
1647 ParsePredicateSuccessProj* slow_loop_parse_predicate_proj);
1648 IfProjNode* clone_assertion_predicate_for_unswitched_loops(Node* iff, IfProjNode* predicate,
1649 Deoptimization::DeoptReason reason,
1650 ParsePredicateSuccessProj* parse_predicate_proj);
1651 static void check_cloned_parse_predicate_for_unswitching(const Node* new_entry, bool is_fast_loop) PRODUCT_RETURN;
1652
1653 bool _created_loop_node;
1654 DEBUG_ONLY(void dump_idoms(Node* early, Node* wrong_lca);)
1655 NOT_PRODUCT(void dump_idoms_in_reverse(const Node* n, const Node_List& idom_list) const;)
1656
1657 public:
1658 void set_created_loop_node() { _created_loop_node = true; }
1659 bool created_loop_node() { return _created_loop_node; }
1660 void register_new_node(Node* n, Node* blk);
1661
1662 #ifdef ASSERT
1663 void dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA);
1664 #endif
1665
1666 #ifndef PRODUCT
1667 void dump() const;
1668 void dump_idom(Node* n) const { dump_idom(n, 1000); } // For debugging
1669 void dump_idom(Node* n, uint count) const;
1670 void get_idoms(Node* n, uint count, Unique_Node_List& idoms) const;
1671 void dump(IdealLoopTree* loop, uint rpo_idx, Node_List &rpo_list) const;
1672 IdealLoopTree* get_loop_idx(Node* n) const {
1673 // Dead nodes have no loop, so return the top level loop instead
1674 return _loop_or_ctrl[n->_idx] ? (IdealLoopTree*)_loop_or_ctrl[n->_idx] : _ltree_root;
1675 }
1676 // Print some stats
1677 static void print_statistics();
1678 static int _loop_invokes; // Count of PhaseIdealLoop invokes
1679 static int _loop_work; // Sum of PhaseIdealLoop x _unique
1680 static volatile int _long_loop_candidates;
1681 static volatile int _long_loop_nests;
1682 static volatile int _long_loop_counted_loops;
1683 #endif
1684
1685 #ifdef ASSERT
1686 void verify() const;
1687 bool verify_idom_and_nodes(Node* root, const PhaseIdealLoop* phase_verify) const;
1688 bool verify_idom(Node* n, const PhaseIdealLoop* phase_verify) const;
1689 bool verify_loop_ctrl(Node* n, const PhaseIdealLoop* phase_verify) const;
1690 #endif
1691
1692 void rpo(Node* start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list) const;
1693
1694 void check_counted_loop_shape(IdealLoopTree* loop, Node* x, BasicType bt) NOT_DEBUG_RETURN;
1695
1696 LoopNode* create_inner_head(IdealLoopTree* loop, BaseCountedLoopNode* head, IfNode* exit_test);
1697
1698
1699 int extract_long_range_checks(const IdealLoopTree* loop, jlong stride_con, int iters_limit, PhiNode* phi,
1700 Node_List &range_checks);
1701
1702 void transform_long_range_checks(int stride_con, const Node_List &range_checks, Node* outer_phi,
1703 Node* inner_iters_actual_int, Node* inner_phi,
1704 Node* iv_add, LoopNode* inner_head);
1705
1706 Node* get_late_ctrl_with_anti_dep(LoadNode* n, Node* early, Node* LCA);
1707
1708 bool ctrl_of_use_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop, Node* ctrl);
1709
1710 bool ctrl_of_all_uses_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop);
1711
1712 Node* compute_early_ctrl(Node* n, Node* n_ctrl);
1713
1714 void try_sink_out_of_loop(Node* n);
1715
1716 Node* clamp(Node* R, Node* L, Node* H);
1717
1718 bool safe_for_if_replacement(const Node* dom) const;
1719
1720 void push_pinned_nodes_thru_region(IfNode* dom_if, Node* region);
1721
1722 bool try_merge_identical_ifs(Node* n);
1723
1724 void clone_loop_body(const Node_List& body, Node_List &old_new, CloneMap* cm);
1725
1726 void fix_body_edges(const Node_List &body, IdealLoopTree* loop, const Node_List &old_new, int dd,
1727 IdealLoopTree* parent, bool partial);
1728
1729 void fix_ctrl_uses(const Node_List& body, const IdealLoopTree* loop, Node_List &old_new, CloneLoopMode mode,
1730 Node* side_by_side_idom, CloneMap* cm, Node_List &worklist);
1731
1732 void fix_data_uses(Node_List& body, IdealLoopTree* loop, CloneLoopMode mode, IdealLoopTree* outer_loop,
1733 uint new_counter, Node_List& old_new, Node_List& worklist, Node_List*& split_if_set,
1734 Node_List*& split_bool_set, Node_List*& split_cex_set);
1735
1736 void finish_clone_loop(Node_List* split_if_set, Node_List* split_bool_set, Node_List* split_cex_set);
1737
1738 bool clone_cmp_down(Node* n, const Node* blk1, const Node* blk2);
1739
1740 void clone_loadklass_nodes_at_cmp_index(const Node* n, Node* cmp, int i);
1741
1742 bool clone_cmp_loadklass_down(Node* n, const Node* blk1, const Node* blk2);
1743
1744 bool at_relevant_ctrl(Node* n, const Node* blk1, const Node* blk2);
1745
1746
1747 Node* similar_subtype_check(const Node* x, Node* r_in);
1748
1749 void update_addp_chain_base(Node* x, Node* old_base, Node* new_base);
1750
1751 bool can_move_to_inner_loop(Node* n, LoopNode* n_loop, Node* x);
1752 };
1753
1754
1755 class AutoNodeBudget : public StackObj
1756 {
1757 public:
1758 enum budget_check_t { BUDGET_CHECK, NO_BUDGET_CHECK };
1759
1760 AutoNodeBudget(PhaseIdealLoop* phase, budget_check_t chk = BUDGET_CHECK)
1761 : _phase(phase),
1762 _check_at_final(chk == BUDGET_CHECK),
1763 _nodes_at_begin(0)
1764 {
1765 precond(_phase != nullptr);
1766
1767 _nodes_at_begin = _phase->require_nodes_begin();
1768 }
1769
1770 ~AutoNodeBudget() {
1771 #ifndef PRODUCT
1772 if (TraceLoopOpts) {
1773 uint request = _phase->nodes_required();
1774 uint delta = _phase->C->live_nodes() - _nodes_at_begin;
1775
1776 if (request < delta) {
1777 tty->print_cr("Exceeding node budget: %d < %d", request, delta);
1778 } else {
1779 uint const REQUIRE_MIN = PhaseIdealLoop::REQUIRE_MIN;
1780 // Identify the worst estimates as "poor" ones.
1781 if (request > REQUIRE_MIN && delta > 0) {
1782 if ((delta > REQUIRE_MIN && request > 3 * delta) ||
1783 (delta <= REQUIRE_MIN && request > 10 * delta)) {
1784 tty->print_cr("Poor node estimate: %d >> %d", request, delta);
1785 }
1786 }
1787 }
1788 }
1789 #endif // PRODUCT
1790 _phase->require_nodes_final(_nodes_at_begin, _check_at_final);
1791 }
1792
1793 private:
1794 PhaseIdealLoop* _phase;
1795 bool _check_at_final;
1796 uint _nodes_at_begin;
1797 };
1798
1799 inline Node* IdealLoopTree::tail() {
1800 // Handle lazy update of _tail field.
1801 if (_tail->in(0) == nullptr) {
1802 _tail = _phase->get_ctrl(_tail);
1803 }
1804 return _tail;
1805 }
1806
1807 inline Node* IdealLoopTree::head() {
1808 // Handle lazy update of _head field.
1809 if (_head->in(0) == nullptr) {
1810 _head = _phase->get_ctrl(_head);
1811 }
1812 return _head;
1813 }
1814
1815 // Iterate over the loop tree using a preorder, left-to-right traversal.
1816 //
1817 // Example that visits all counted loops from within PhaseIdealLoop
1818 //
1819 // for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
1820 // IdealLoopTree* lpt = iter.current();
1821 // if (!lpt->is_counted()) continue;
1822 // ...
1823 class LoopTreeIterator : public StackObj {
1824 private:
1825 IdealLoopTree* _root;
1826 IdealLoopTree* _curnt;
1827
1828 public:
1829 LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {}
1830
1831 bool done() { return _curnt == nullptr; } // Finished iterating?
1832
1833 void next(); // Advance to next loop tree
1834
1835 IdealLoopTree* current() { return _curnt; } // Return current value of iterator.
1836 };
1837
1838 // Compute probability of reaching some CFG node from a fixed
1839 // dominating CFG node
1840 class PathFrequency {
1841 private:
1842 Node* _dom; // frequencies are computed relative to this node
1843 Node_Stack _stack;
1844 GrowableArray<float> _freqs_stack; // keep track of intermediate result at regions
1845 GrowableArray<float> _freqs; // cache frequencies
1846 PhaseIdealLoop* _phase;
1847
1848 float check_and_truncate_frequency(float f) {
1849 assert(f >= 0, "Incorrect frequency");
1850 // We do not perform an exact (f <= 1) check
1851 // this would be error prone with rounding of floats.
1852 // Performing a check like (f <= 1+eps) would be of benefit,
1853 // however, it is not evident how to determine such an eps,
1854 // given that an arbitrary number of add/mul operations
1855 // are performed on these frequencies.
1856 return (f > 1) ? 1 : f;
1857 }
1858
1859 public:
1860 PathFrequency(Node* dom, PhaseIdealLoop* phase)
1861 : _dom(dom), _stack(0), _phase(phase) {
1862 }
1863
1864 float to(Node* n);
1865 };
1866
1867 #endif // SHARE_OPTO_LOOPNODE_HPP