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 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 char _unswitch_count;
81 enum { _unswitch_max=3 };
82
83 // Expected trip count from profile data
84 float _profile_trip_cnt;
85
86 public:
87 // Names for edge indices
88 enum { Self=0, EntryControl, LoopBackControl };
89
90 bool is_inner_loop() const { return _loop_flags & InnerLoop; }
91 void set_inner_loop() { _loop_flags |= InnerLoop; }
92
93 bool is_vectorized_loop() const { return _loop_flags & VectorizedLoop; }
94 bool is_partial_peel_loop() const { return _loop_flags & PartialPeelLoop; }
95 void set_partial_peel_loop() { _loop_flags |= PartialPeelLoop; }
96 bool partial_peel_has_failed() const { return _loop_flags & PartialPeelFailed; }
97 bool is_strip_mined() const { return _loop_flags & StripMined; }
98 bool is_profile_trip_failed() const { return _loop_flags & ProfileTripFailed; }
99 bool is_subword_loop() const { return _loop_flags & SubwordLoop; }
100 bool is_loop_nest_inner_loop() const { return _loop_flags & LoopNestInnerLoop; }
101 bool is_loop_nest_outer_loop() const { return _loop_flags & LoopNestLongOuterLoop; }
102
103 void mark_partial_peel_failed() { _loop_flags |= PartialPeelFailed; }
104 void mark_was_slp() { _loop_flags |= WasSlpAnalyzed; }
105 void mark_passed_slp() { _loop_flags |= PassedSlpAnalysis; }
106 void mark_do_unroll_only() { _loop_flags |= DoUnrollOnly; }
107 void mark_loop_vectorized() { _loop_flags |= VectorizedLoop; }
108 void mark_has_atomic_post_loop() { _loop_flags |= HasAtomicPostLoop; }
109 void mark_strip_mined() { _loop_flags |= StripMined; }
110 void clear_strip_mined() { _loop_flags &= ~StripMined; }
111 void mark_profile_trip_failed() { _loop_flags |= ProfileTripFailed; }
112 void mark_subword_loop() { _loop_flags |= SubwordLoop; }
113 void mark_loop_nest_inner_loop() { _loop_flags |= LoopNestInnerLoop; }
114 void mark_loop_nest_outer_loop() { _loop_flags |= LoopNestLongOuterLoop; }
115
116 int unswitch_max() { return _unswitch_max; }
117 int unswitch_count() { return _unswitch_count; }
118
119 void set_unswitch_count(int val) {
120 assert (val <= unswitch_max(), "too many unswitches");
121 _unswitch_count = val;
122 }
123
124 void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; }
125 float profile_trip_cnt() { return _profile_trip_cnt; }
126
127 LoopNode(Node *entry, Node *backedge)
128 : RegionNode(3), _loop_flags(0), _unswitch_count(0),
129 _profile_trip_cnt(COUNT_UNKNOWN) {
130 init_class_id(Class_Loop);
131 init_req(EntryControl, entry);
132 init_req(LoopBackControl, backedge);
133 }
134
135 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
136 virtual int Opcode() const;
137 bool can_be_counted_loop(PhaseValues* phase) const {
138 return req() == 3 && in(0) != nullptr &&
139 in(1) != nullptr && phase->type(in(1)) != Type::TOP &&
140 in(2) != nullptr && phase->type(in(2)) != Type::TOP;
141 }
142 bool is_valid_counted_loop(BasicType bt) const;
143 #ifndef PRODUCT
144 virtual void dump_spec(outputStream *st) const;
145 #endif
146
147 void verify_strip_mined(int expect_skeleton) const NOT_DEBUG_RETURN;
148 virtual LoopNode* skip_strip_mined(int expect_skeleton = 1) { return this; }
149 virtual IfTrueNode* outer_loop_tail() const { ShouldNotReachHere(); return nullptr; }
150 virtual OuterStripMinedLoopEndNode* outer_loop_end() const { ShouldNotReachHere(); return nullptr; }
151 virtual IfFalseNode* outer_loop_exit() const { ShouldNotReachHere(); return nullptr; }
152 virtual SafePointNode* outer_safepoint() const { ShouldNotReachHere(); return nullptr; }
153 };
154
155 //------------------------------Counted Loops----------------------------------
156 // Counted loops are all trip-counted loops, with exactly 1 trip-counter exit
157 // path (and maybe some other exit paths). The trip-counter exit is always
158 // last in the loop. The trip-counter have to stride by a constant;
159 // the exit value is also loop invariant.
160
161 // CountedLoopNodes and CountedLoopEndNodes come in matched pairs. The
162 // CountedLoopNode has the incoming loop control and the loop-back-control
163 // which is always the IfTrue before the matching CountedLoopEndNode. The
164 // CountedLoopEndNode has an incoming control (possibly not the
165 // CountedLoopNode if there is control flow in the loop), the post-increment
166 // trip-counter value, and the limit. The trip-counter value is always of
167 // the form (Op old-trip-counter stride). The old-trip-counter is produced
168 // by a Phi connected to the CountedLoopNode. The stride is constant.
169 // The Op is any commutable opcode, including Add, Mul, Xor. The
170 // CountedLoopEndNode also takes in the loop-invariant limit value.
171
172 // From a CountedLoopNode I can reach the matching CountedLoopEndNode via the
173 // loop-back control. From CountedLoopEndNodes I can reach CountedLoopNodes
174 // via the old-trip-counter from the Op node.
175
176 //------------------------------CountedLoopNode--------------------------------
177 // CountedLoopNodes head simple counted loops. CountedLoopNodes have as
178 // inputs the incoming loop-start control and the loop-back control, so they
179 // act like RegionNodes. They also take in the initial trip counter, the
180 // loop-invariant stride and the loop-invariant limit value. CountedLoopNodes
181 // produce a loop-body control and the trip counter value. Since
182 // CountedLoopNodes behave like RegionNodes I still have a standard CFG model.
183
184 class BaseCountedLoopNode : public LoopNode {
185 public:
186 BaseCountedLoopNode(Node *entry, Node *backedge)
187 : LoopNode(entry, backedge) {
188 }
189
190 Node *init_control() const { return in(EntryControl); }
191 Node *back_control() const { return in(LoopBackControl); }
192
193 Node* init_trip() const;
194 Node* stride() const;
195 bool stride_is_con() const;
196 Node* limit() const;
197 Node* incr() const;
198 Node* phi() const;
199
200 BaseCountedLoopEndNode* loopexit_or_null() const;
201 BaseCountedLoopEndNode* loopexit() const;
202
203 virtual BasicType bt() const = 0;
204
205 jlong stride_con() const;
206
207 static BaseCountedLoopNode* make(Node* entry, Node* backedge, BasicType bt);
208 };
209
210
211 class CountedLoopNode : public BaseCountedLoopNode {
212 // Size is bigger to hold _main_idx. However, _main_idx does not change
213 // the semantics so it does not appear in the hash & cmp functions.
214 virtual uint size_of() const { return sizeof(*this); }
215
216 // For Pre- and Post-loops during debugging ONLY, this holds the index of
217 // the Main CountedLoop. Used to assert that we understand the graph shape.
218 node_idx_t _main_idx;
219
220 // Known trip count calculated by compute_exact_trip_count()
221 uint _trip_count;
222
223 // Log2 of original loop bodies in unrolled loop
224 int _unrolled_count_log2;
225
226 // Node count prior to last unrolling - used to decide if
227 // unroll,optimize,unroll,optimize,... is making progress
228 int _node_count_before_unroll;
229
230 // If slp analysis is performed we record the maximum
231 // vector mapped unroll factor here
232 int _slp_maximum_unroll_factor;
233
234 // Cached CountedLoopEndNode of pre loop for main loops
235 CountedLoopEndNode* _pre_loop_end;
236
237 public:
238 CountedLoopNode(Node *entry, Node *backedge)
239 : BaseCountedLoopNode(entry, backedge), _main_idx(0), _trip_count(max_juint),
240 _unrolled_count_log2(0), _node_count_before_unroll(0),
241 _slp_maximum_unroll_factor(0), _pre_loop_end(nullptr) {
242 init_class_id(Class_CountedLoop);
243 // Initialize _trip_count to the largest possible value.
244 // Will be reset (lower) if the loop's trip count is known.
245 }
246
247 virtual int Opcode() const;
248 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
249
250 CountedLoopEndNode* loopexit_or_null() const { return (CountedLoopEndNode*) BaseCountedLoopNode::loopexit_or_null(); }
251 CountedLoopEndNode* loopexit() const { return (CountedLoopEndNode*) BaseCountedLoopNode::loopexit(); }
252 int stride_con() const;
253
254 // Match increment with optional truncation
255 static Node*
256 match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInteger** trunc_type,
257 BasicType bt);
258
259 // A 'main' loop has a pre-loop and a post-loop. The 'main' loop
260 // can run short a few iterations and may start a few iterations in.
261 // It will be RCE'd and unrolled and aligned.
262
263 // A following 'post' loop will run any remaining iterations. Used
264 // during Range Check Elimination, the 'post' loop will do any final
265 // iterations with full checks. Also used by Loop Unrolling, where
266 // the 'post' loop will do any epilog iterations needed. Basically,
267 // a 'post' loop can not profitably be further unrolled or RCE'd.
268
269 // A preceding 'pre' loop will run at least 1 iteration (to do peeling),
270 // it may do under-flow checks for RCE and may do alignment iterations
271 // so the following main loop 'knows' that it is striding down cache
272 // lines.
273
274 // A 'main' loop that is ONLY unrolled or peeled, never RCE'd or
275 // Aligned, may be missing it's pre-loop.
276 bool is_normal_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Normal; }
277 bool is_pre_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Pre; }
278 bool is_main_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Main; }
279 bool is_post_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Post; }
280 bool was_slp_analyzed () const { return (_loop_flags&WasSlpAnalyzed) == WasSlpAnalyzed; }
281 bool has_passed_slp () const { return (_loop_flags&PassedSlpAnalysis) == PassedSlpAnalysis; }
282 bool is_unroll_only () const { return (_loop_flags&DoUnrollOnly) == DoUnrollOnly; }
283 bool is_main_no_pre_loop() const { return _loop_flags & MainHasNoPreLoop; }
284 bool has_atomic_post_loop () const { return (_loop_flags & HasAtomicPostLoop) == HasAtomicPostLoop; }
285 void set_main_no_pre_loop() { _loop_flags |= MainHasNoPreLoop; }
286
287 int main_idx() const { return _main_idx; }
288
289
290 void set_pre_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; }
291 void set_main_loop ( ) { assert(is_normal_loop(),""); _loop_flags |= Main; }
292 void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; }
293 void set_normal_loop( ) { _loop_flags &= ~PreMainPostFlagsMask; }
294
295 void set_trip_count(uint tc) { _trip_count = tc; }
296 uint trip_count() { return _trip_count; }
297
298 bool has_exact_trip_count() const { return (_loop_flags & HasExactTripCount) != 0; }
299 void set_exact_trip_count(uint tc) {
300 _trip_count = tc;
301 _loop_flags |= HasExactTripCount;
302 }
303 void set_nonexact_trip_count() {
304 _loop_flags &= ~HasExactTripCount;
305 }
306 void set_notpassed_slp() {
307 _loop_flags &= ~PassedSlpAnalysis;
308 }
309
310 void double_unrolled_count() { _unrolled_count_log2++; }
311 int unrolled_count() { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); }
312
313 void set_node_count_before_unroll(int ct) { _node_count_before_unroll = ct; }
314 int node_count_before_unroll() { return _node_count_before_unroll; }
315 void set_slp_max_unroll(int unroll_factor) { _slp_maximum_unroll_factor = unroll_factor; }
316 int slp_max_unroll() const { return _slp_maximum_unroll_factor; }
317
318 virtual LoopNode* skip_strip_mined(int expect_skeleton = 1);
319 OuterStripMinedLoopNode* outer_loop() const;
320 virtual IfTrueNode* outer_loop_tail() const;
321 virtual OuterStripMinedLoopEndNode* outer_loop_end() const;
322 virtual IfFalseNode* outer_loop_exit() const;
323 virtual SafePointNode* outer_safepoint() const;
324
325 Node* skip_assertion_predicates_with_halt();
326
327 virtual BasicType bt() const {
328 return T_INT;
329 }
330
331 Node* is_canonical_loop_entry();
332 CountedLoopEndNode* find_pre_loop_end();
333 CountedLoopNode* pre_loop_head() const;
334 CountedLoopEndNode* pre_loop_end();
335 void set_pre_loop_end(CountedLoopEndNode* pre_loop_end);
336
337 #ifndef PRODUCT
338 virtual void dump_spec(outputStream *st) const;
339 #endif
340 };
341
342 class LongCountedLoopNode : public BaseCountedLoopNode {
343 public:
344 LongCountedLoopNode(Node *entry, Node *backedge)
345 : BaseCountedLoopNode(entry, backedge) {
346 init_class_id(Class_LongCountedLoop);
347 }
348
349 virtual int Opcode() const;
350
351 virtual BasicType bt() const {
352 return T_LONG;
353 }
354
355 LongCountedLoopEndNode* loopexit_or_null() const { return (LongCountedLoopEndNode*) BaseCountedLoopNode::loopexit_or_null(); }
356 LongCountedLoopEndNode* loopexit() const { return (LongCountedLoopEndNode*) BaseCountedLoopNode::loopexit(); }
357 };
358
359
360 //------------------------------CountedLoopEndNode-----------------------------
361 // CountedLoopEndNodes end simple trip counted loops. They act much like
362 // IfNodes.
363
364 class BaseCountedLoopEndNode : public IfNode {
365 public:
366 enum { TestControl, TestValue };
367 BaseCountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
368 : IfNode(control, test, prob, cnt) {
369 init_class_id(Class_BaseCountedLoopEnd);
370 }
371
372 Node *cmp_node() const { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : nullptr; }
373 Node* incr() const { Node* tmp = cmp_node(); return (tmp && tmp->req() == 3) ? tmp->in(1) : nullptr; }
374 Node* limit() const { Node* tmp = cmp_node(); return (tmp && tmp->req() == 3) ? tmp->in(2) : nullptr; }
375 Node* stride() const { Node* tmp = incr(); return (tmp && tmp->req() == 3) ? tmp->in(2) : nullptr; }
376 Node* init_trip() const { Node* tmp = phi(); return (tmp && tmp->req() == 3) ? tmp->in(1) : nullptr; }
377 bool stride_is_con() const { Node *tmp = stride(); return (tmp != nullptr && tmp->is_Con()); }
378
379 PhiNode* phi() const {
380 Node* tmp = incr();
381 if (tmp && tmp->req() == 3) {
382 Node* phi = tmp->in(1);
383 if (phi->is_Phi()) {
384 return phi->as_Phi();
385 }
386 }
387 return nullptr;
388 }
389
390 BaseCountedLoopNode* loopnode() const {
391 // The CountedLoopNode that goes with this CountedLoopEndNode may
392 // have been optimized out by the IGVN so be cautious with the
393 // pattern matching on the graph
394 PhiNode* iv_phi = phi();
395 if (iv_phi == nullptr) {
396 return nullptr;
397 }
398 Node* ln = iv_phi->in(0);
399 if (!ln->is_BaseCountedLoop() || ln->as_BaseCountedLoop()->loopexit_or_null() != this) {
400 return nullptr;
401 }
402 if (ln->as_BaseCountedLoop()->bt() != bt()) {
403 return nullptr;
404 }
405 return ln->as_BaseCountedLoop();
406 }
407
408 BoolTest::mask test_trip() const { return in(TestValue)->as_Bool()->_test._test; }
409
410 jlong stride_con() const;
411 virtual BasicType bt() const = 0;
412
413 static BaseCountedLoopEndNode* make(Node* control, Node* test, float prob, float cnt, BasicType bt);
414 };
415
416 class CountedLoopEndNode : public BaseCountedLoopEndNode {
417 public:
418
419 CountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
420 : BaseCountedLoopEndNode(control, test, prob, cnt) {
421 init_class_id(Class_CountedLoopEnd);
422 }
423 virtual int Opcode() const;
424
425 CountedLoopNode* loopnode() const {
426 return (CountedLoopNode*) BaseCountedLoopEndNode::loopnode();
427 }
428
429 virtual BasicType bt() const {
430 return T_INT;
431 }
432
433 #ifndef PRODUCT
434 virtual void dump_spec(outputStream *st) const;
435 #endif
436 };
437
438 class LongCountedLoopEndNode : public BaseCountedLoopEndNode {
439 public:
440 LongCountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
441 : BaseCountedLoopEndNode(control, test, prob, cnt) {
442 init_class_id(Class_LongCountedLoopEnd);
443 }
444
445 LongCountedLoopNode* loopnode() const {
446 return (LongCountedLoopNode*) BaseCountedLoopEndNode::loopnode();
447 }
448
449 virtual int Opcode() const;
450
451 virtual BasicType bt() const {
452 return T_LONG;
453 }
454 };
455
456
457 inline BaseCountedLoopEndNode* BaseCountedLoopNode::loopexit_or_null() const {
458 Node* bctrl = back_control();
459 if (bctrl == nullptr) return nullptr;
460
461 Node* lexit = bctrl->in(0);
462 if (!lexit->is_BaseCountedLoopEnd()) {
463 return nullptr;
464 }
465 BaseCountedLoopEndNode* result = lexit->as_BaseCountedLoopEnd();
466 if (result->bt() != bt()) {
467 return nullptr;
468 }
469 return result;
470 }
471
472 inline BaseCountedLoopEndNode* BaseCountedLoopNode::loopexit() const {
473 BaseCountedLoopEndNode* cle = loopexit_or_null();
474 assert(cle != nullptr, "loopexit is null");
475 return cle;
476 }
477
478 inline Node* BaseCountedLoopNode::init_trip() const {
479 BaseCountedLoopEndNode* cle = loopexit_or_null();
480 return cle != nullptr ? cle->init_trip() : nullptr;
481 }
482 inline Node* BaseCountedLoopNode::stride() const {
483 BaseCountedLoopEndNode* cle = loopexit_or_null();
484 return cle != nullptr ? cle->stride() : nullptr;
485 }
486
487 inline bool BaseCountedLoopNode::stride_is_con() const {
488 BaseCountedLoopEndNode* cle = loopexit_or_null();
489 return cle != nullptr && cle->stride_is_con();
490 }
491 inline Node* BaseCountedLoopNode::limit() const {
492 BaseCountedLoopEndNode* cle = loopexit_or_null();
493 return cle != nullptr ? cle->limit() : nullptr;
494 }
495 inline Node* BaseCountedLoopNode::incr() const {
496 BaseCountedLoopEndNode* cle = loopexit_or_null();
497 return cle != nullptr ? cle->incr() : nullptr;
498 }
499 inline Node* BaseCountedLoopNode::phi() const {
500 BaseCountedLoopEndNode* cle = loopexit_or_null();
501 return cle != nullptr ? cle->phi() : nullptr;
502 }
503
504 inline jlong BaseCountedLoopNode::stride_con() const {
505 BaseCountedLoopEndNode* cle = loopexit_or_null();
506 return cle != nullptr ? cle->stride_con() : 0;
507 }
508
509
510 //------------------------------LoopLimitNode-----------------------------
511 // Counted Loop limit node which represents exact final iterator value:
512 // trip_count = (limit - init_trip + stride - 1)/stride
513 // final_value= trip_count * stride + init_trip.
514 // Use HW instructions to calculate it when it can overflow in integer.
515 // Note, final_value should fit into integer since counted loop has
516 // limit check: limit <= max_int-stride.
517 class LoopLimitNode : public Node {
518 enum { Init=1, Limit=2, Stride=3 };
519 public:
520 LoopLimitNode( Compile* C, Node *init, Node *limit, Node *stride ) : Node(0,init,limit,stride) {
521 // Put it on the Macro nodes list to optimize during macro nodes expansion.
522 init_flags(Flag_is_macro);
523 C->add_macro_node(this);
524 }
525 virtual int Opcode() const;
526 virtual const Type *bottom_type() const { return TypeInt::INT; }
527 virtual uint ideal_reg() const { return Op_RegI; }
528 virtual const Type* Value(PhaseGVN* phase) const;
529 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
530 virtual Node* Identity(PhaseGVN* phase);
531 };
532
533 // Support for strip mining
534 class OuterStripMinedLoopNode : public LoopNode {
535 private:
536 static void fix_sunk_stores(CountedLoopEndNode* inner_cle, LoopNode* inner_cl, PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
537
538 public:
539 OuterStripMinedLoopNode(Compile* C, Node *entry, Node *backedge)
540 : LoopNode(entry, backedge) {
541 init_class_id(Class_OuterStripMinedLoop);
542 init_flags(Flag_is_macro);
543 C->add_macro_node(this);
544 }
545
546 virtual int Opcode() const;
547
548 virtual IfTrueNode* outer_loop_tail() const;
549 virtual OuterStripMinedLoopEndNode* outer_loop_end() const;
550 virtual IfFalseNode* outer_loop_exit() const;
551 virtual SafePointNode* outer_safepoint() const;
552 void adjust_strip_mined_loop(PhaseIterGVN* igvn);
553
554 void remove_outer_loop_and_safepoint(PhaseIterGVN* igvn) const;
555
556 void transform_to_counted_loop(PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
557
558 static Node* register_new_node(Node* node, LoopNode* ctrl, PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
559
560 Node* register_control(Node* node, Node* loop, Node* idom, PhaseIterGVN* igvn,
561 PhaseIdealLoop* iloop);
562 };
563
564 class OuterStripMinedLoopEndNode : public IfNode {
565 public:
566 OuterStripMinedLoopEndNode(Node *control, Node *test, float prob, float cnt)
567 : IfNode(control, test, prob, cnt) {
568 init_class_id(Class_OuterStripMinedLoopEnd);
569 }
570
571 virtual int Opcode() const;
572
573 virtual const Type* Value(PhaseGVN* phase) const;
574 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
575
576 bool is_expanded(PhaseGVN *phase) const;
577 };
578
579 // -----------------------------IdealLoopTree----------------------------------
580 class IdealLoopTree : public ResourceObj {
581 public:
582 IdealLoopTree *_parent; // Parent in loop tree
583 IdealLoopTree *_next; // Next sibling in loop tree
584 IdealLoopTree *_child; // First child in loop tree
585
586 // The head-tail backedge defines the loop.
587 // If a loop has multiple backedges, this is addressed during cleanup where
588 // we peel off the multiple backedges, merging all edges at the bottom and
589 // ensuring that one proper backedge flow into the loop.
590 Node *_head; // Head of loop
591 Node *_tail; // Tail of loop
592 inline Node *tail(); // Handle lazy update of _tail field
593 inline Node *head(); // Handle lazy update of _head field
594 PhaseIdealLoop* _phase;
595 int _local_loop_unroll_limit;
596 int _local_loop_unroll_factor;
597
598 Node_List _body; // Loop body for inner loops
599
600 uint16_t _nest; // Nesting depth
601 uint8_t _irreducible:1, // True if irreducible
602 _has_call:1, // True if has call safepoint
603 _has_sfpt:1, // True if has non-call safepoint
604 _rce_candidate:1, // True if candidate for range check elimination
605 _has_range_checks:1,
606 _has_range_checks_computed:1;
607
608 Node_List* _safepts; // List of safepoints in this loop
609 Node_List* _required_safept; // A inner loop cannot delete these safepts;
610 bool _allow_optimizations; // Allow loop optimizations
611
612 IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail )
613 : _parent(0), _next(0), _child(0),
614 _head(head), _tail(tail),
615 _phase(phase),
616 _local_loop_unroll_limit(0), _local_loop_unroll_factor(0),
617 _nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0),
618 _has_range_checks(0), _has_range_checks_computed(0),
619 _safepts(nullptr),
620 _required_safept(nullptr),
621 _allow_optimizations(true)
622 {
623 precond(_head != nullptr);
624 precond(_tail != nullptr);
625 }
626
627 // Is 'l' a member of 'this'?
628 bool is_member(const IdealLoopTree *l) const; // Test for nested membership
629
630 // Set loop nesting depth. Accumulate has_call bits.
631 int set_nest( uint depth );
632
633 // Split out multiple fall-in edges from the loop header. Move them to a
634 // private RegionNode before the loop. This becomes the loop landing pad.
635 void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt );
636
637 // Split out the outermost loop from this shared header.
638 void split_outer_loop( PhaseIdealLoop *phase );
639
640 // Merge all the backedges from the shared header into a private Region.
641 // Feed that region as the one backedge to this loop.
642 void merge_many_backedges( PhaseIdealLoop *phase );
643
644 // Split shared headers and insert loop landing pads.
645 // Insert a LoopNode to replace the RegionNode.
646 // Returns TRUE if loop tree is structurally changed.
647 bool beautify_loops( PhaseIdealLoop *phase );
648
649 // Perform optimization to use the loop predicates for null checks and range checks.
650 // Applies to any loop level (not just the innermost one)
651 bool loop_predication( PhaseIdealLoop *phase);
652 bool can_apply_loop_predication();
653
654 // Perform iteration-splitting on inner loops. Split iterations to
655 // avoid range checks or one-shot null checks. Returns false if the
656 // current round of loop opts should stop.
657 bool iteration_split( PhaseIdealLoop *phase, Node_List &old_new );
658
659 // Driver for various flavors of iteration splitting. Returns false
660 // if the current round of loop opts should stop.
661 bool iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new );
662
663 // Given dominators, try to find loops with calls that must always be
664 // executed (call dominates loop tail). These loops do not need non-call
665 // safepoints (ncsfpt).
666 void check_safepts(VectorSet &visited, Node_List &stack);
667
668 // Allpaths backwards scan from loop tail, terminating each path at first safepoint
669 // encountered.
670 void allpaths_check_safepts(VectorSet &visited, Node_List &stack);
671
672 // Remove safepoints from loop. Optionally keeping one.
673 void remove_safepoints(PhaseIdealLoop* phase, bool keep_one);
674
675 // Convert to counted loops where possible
676 void counted_loop( PhaseIdealLoop *phase );
677
678 // Check for Node being a loop-breaking test
679 Node *is_loop_exit(Node *iff) const;
680
681 // Remove simplistic dead code from loop body
682 void DCE_loop_body();
683
684 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage.
685 // Replace with a 1-in-10 exit guess.
686 void adjust_loop_exit_prob( PhaseIdealLoop *phase );
687
688 // Return TRUE or FALSE if the loop should never be RCE'd or aligned.
689 // Useful for unrolling loops with NO array accesses.
690 bool policy_peel_only( PhaseIdealLoop *phase ) const;
691
692 // Return TRUE or FALSE if the loop should be unswitched -- clone
693 // loop with an invariant test
694 bool policy_unswitching( PhaseIdealLoop *phase ) const;
695
696 // Micro-benchmark spamming. Remove empty loops.
697 bool do_remove_empty_loop( PhaseIdealLoop *phase );
698
699 // Convert one iteration loop into normal code.
700 bool do_one_iteration_loop( PhaseIdealLoop *phase );
701
702 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can
703 // move some loop-invariant test (usually a null-check) before the loop.
704 bool policy_peeling(PhaseIdealLoop *phase);
705
706 uint estimate_peeling(PhaseIdealLoop *phase);
707
708 // Return TRUE or FALSE if the loop should be maximally unrolled. Stash any
709 // known trip count in the counted loop node.
710 bool policy_maximally_unroll(PhaseIdealLoop *phase) const;
711
712 // Return TRUE or FALSE if the loop should be unrolled or not. Apply unroll
713 // if the loop is a counted loop and the loop body is small enough.
714 bool policy_unroll(PhaseIdealLoop *phase);
715
716 // Loop analyses to map to a maximal superword unrolling for vectorization.
717 void policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_ct);
718
719 // Return TRUE or FALSE if the loop should be range-check-eliminated.
720 // Gather a list of IF tests that are dominated by iteration splitting;
721 // also gather the end of the first split and the start of the 2nd split.
722 bool policy_range_check(PhaseIdealLoop* phase, bool provisional, BasicType bt) const;
723
724 // Return TRUE if "iff" is a range check.
725 bool is_range_check_if(IfProjNode* if_success_proj, PhaseIdealLoop* phase, Invariance& invar DEBUG_ONLY(COMMA ProjNode* predicate_proj)) const;
726 bool is_range_check_if(IfProjNode* if_success_proj, PhaseIdealLoop* phase, BasicType bt, Node* iv, Node*& range, Node*& offset,
727 jlong& scale) const;
728
729 // Estimate the number of nodes required when cloning a loop (body).
730 uint est_loop_clone_sz(uint factor) const;
731 // Estimate the number of nodes required when unrolling a loop (body).
732 uint est_loop_unroll_sz(uint factor) const;
733
734 // Compute loop trip count if possible
735 void compute_trip_count(PhaseIdealLoop* phase);
736
737 // Compute loop trip count from profile data
738 float compute_profile_trip_cnt_helper(Node* n);
739 void compute_profile_trip_cnt( PhaseIdealLoop *phase );
740
741 // Reassociate invariant expressions.
742 void reassociate_invariants(PhaseIdealLoop *phase);
743 // Reassociate invariant binary expressions.
744 Node* reassociate(Node* n1, PhaseIdealLoop *phase);
745 // Reassociate invariant add and subtract expressions.
746 Node* reassociate_add_sub(Node* n1, int inv1_idx, int inv2_idx, PhaseIdealLoop *phase);
747 // Return nonzero index of invariant operand if invariant and variant
748 // are combined with an associative binary. Helper for reassociate_invariants.
749 int find_invariant(Node* n, PhaseIdealLoop *phase);
750 // Return TRUE if "n" is associative.
751 bool is_associative(Node* n, Node* base=nullptr);
752
753 // Return true if n is invariant
754 bool is_invariant(Node* n) const;
755
756 // Put loop body on igvn work list
757 void record_for_igvn();
758
759 bool is_root() { return _parent == nullptr; }
760 // A proper/reducible loop w/o any (occasional) dead back-edge.
761 bool is_loop() { return !_irreducible && !tail()->is_top(); }
762 bool is_counted() { return is_loop() && _head->is_CountedLoop(); }
763 bool is_innermost() { return is_loop() && _child == nullptr; }
764
765 void remove_main_post_loops(CountedLoopNode *cl, PhaseIdealLoop *phase);
766
767 bool compute_has_range_checks() const;
768 bool range_checks_present() {
769 if (!_has_range_checks_computed) {
770 if (compute_has_range_checks()) {
771 _has_range_checks = 1;
772 }
773 _has_range_checks_computed = 1;
774 }
775 return _has_range_checks;
776 }
777
778 #ifndef PRODUCT
779 void dump_head(); // Dump loop head only
780 void dump(); // Dump this loop recursively
781 #endif
782
783 #ifdef ASSERT
784 GrowableArray<IdealLoopTree*> collect_sorted_children() const;
785 bool verify_tree(IdealLoopTree* loop_verify) const;
786 #endif
787
788 private:
789 enum { EMPTY_LOOP_SIZE = 7 }; // Number of nodes in an empty loop.
790
791 // Estimate the number of nodes resulting from control and data flow merge.
792 uint est_loop_flow_merge_sz() const;
793
794 // Check if the number of residual iterations is large with unroll_cnt.
795 // Return true if the residual iterations are more than 10% of the trip count.
796 bool is_residual_iters_large(int unroll_cnt, CountedLoopNode *cl) const {
797 return (unroll_cnt - 1) * (100.0 / LoopPercentProfileLimit) > cl->profile_trip_cnt();
798 }
799
800 void collect_loop_core_nodes(PhaseIdealLoop* phase, Unique_Node_List& wq) const;
801
802 bool empty_loop_with_data_nodes(PhaseIdealLoop* phase) const;
803
804 void enqueue_data_nodes(PhaseIdealLoop* phase, Unique_Node_List& empty_loop_nodes, Unique_Node_List& wq) const;
805
806 bool process_safepoint(PhaseIdealLoop* phase, Unique_Node_List& empty_loop_nodes, Unique_Node_List& wq,
807 Node* sfpt) const;
808
809 bool empty_loop_candidate(PhaseIdealLoop* phase) const;
810
811 bool empty_loop_with_extra_nodes_candidate(PhaseIdealLoop* phase) const;
812 };
813
814 // -----------------------------PhaseIdealLoop---------------------------------
815 // Computes the mapping from Nodes to IdealLoopTrees. Organizes IdealLoopTrees
816 // into a loop tree. Drives the loop-based transformations on the ideal graph.
817 class PhaseIdealLoop : public PhaseTransform {
818 friend class IdealLoopTree;
819 friend class SuperWord;
820 friend class ShenandoahBarrierC2Support;
821 friend class AutoNodeBudget;
822
823 // Map loop membership for CFG nodes, and ctrl for non-CFG nodes.
824 Node_List _loop_or_ctrl;
825
826 // Pre-computed def-use info
827 PhaseIterGVN &_igvn;
828
829 // Head of loop tree
830 IdealLoopTree* _ltree_root;
831
832 // Array of pre-order numbers, plus post-visited bit.
833 // ZERO for not pre-visited. EVEN for pre-visited but not post-visited.
834 // ODD for post-visited. Other bits are the pre-order number.
835 uint *_preorders;
836 uint _max_preorder;
837
838 const PhaseIdealLoop* _verify_me;
839 bool _verify_only;
840
841 // Allocate _preorders[] array
842 void allocate_preorders() {
843 _max_preorder = C->unique()+8;
844 _preorders = NEW_RESOURCE_ARRAY(uint, _max_preorder);
845 memset(_preorders, 0, sizeof(uint) * _max_preorder);
846 }
847
848 // Allocate _preorders[] array
849 void reallocate_preorders() {
850 if ( _max_preorder < C->unique() ) {
851 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique());
852 _max_preorder = C->unique();
853 }
854 memset(_preorders, 0, sizeof(uint) * _max_preorder);
855 }
856
857 // Check to grow _preorders[] array for the case when build_loop_tree_impl()
858 // adds new nodes.
859 void check_grow_preorders( ) {
860 if ( _max_preorder < C->unique() ) {
861 uint newsize = _max_preorder<<1; // double size of array
862 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize);
863 memset(&_preorders[_max_preorder],0,sizeof(uint)*(newsize-_max_preorder));
864 _max_preorder = newsize;
865 }
866 }
867 // Check for pre-visited. Zero for NOT visited; non-zero for visited.
868 int is_visited( Node *n ) const { return _preorders[n->_idx]; }
869 // Pre-order numbers are written to the Nodes array as low-bit-set values.
870 void set_preorder_visited( Node *n, int pre_order ) {
871 assert( !is_visited( n ), "already set" );
872 _preorders[n->_idx] = (pre_order<<1);
873 };
874 // Return pre-order number.
875 int get_preorder( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]>>1; }
876
877 // Check for being post-visited.
878 // Should be previsited already (checked with assert(is_visited(n))).
879 int is_postvisited( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]&1; }
880
881 // Mark as post visited
882 void set_postvisited( Node *n ) { assert( !is_postvisited( n ), "" ); _preorders[n->_idx] |= 1; }
883
884 public:
885 // Set/get control node out. Set lower bit to distinguish from IdealLoopTree
886 // Returns true if "n" is a data node, false if it's a control node.
887 bool has_ctrl(const Node* n) const { return ((intptr_t)_loop_or_ctrl[n->_idx]) & 1; }
888
889 private:
890 // clear out dead code after build_loop_late
891 Node_List _deadlist;
892 Node_List _zero_trip_guard_opaque_nodes;
893
894 // Support for faster execution of get_late_ctrl()/dom_lca()
895 // when a node has many uses and dominator depth is deep.
896 GrowableArray<jlong> _dom_lca_tags;
897 uint _dom_lca_tags_round;
898 void init_dom_lca_tags();
899
900 // Helper for debugging bad dominance relationships
901 bool verify_dominance(Node* n, Node* use, Node* LCA, Node* early);
902
903 Node* compute_lca_of_uses(Node* n, Node* early, bool verify = false);
904
905 // Inline wrapper for frequent cases:
906 // 1) only one use
907 // 2) a use is the same as the current LCA passed as 'n1'
908 Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) {
909 assert( n->is_CFG(), "" );
910 // Fast-path null lca
911 if( lca != nullptr && lca != n ) {
912 assert( lca->is_CFG(), "" );
913 // find LCA of all uses
914 n = dom_lca_for_get_late_ctrl_internal( lca, n, tag );
915 }
916 return find_non_split_ctrl(n);
917 }
918 Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag );
919
920 // Helper function for directing control inputs away from CFG split points.
921 Node *find_non_split_ctrl( Node *ctrl ) const {
922 if (ctrl != nullptr) {
923 if (ctrl->is_MultiBranch()) {
924 ctrl = ctrl->in(0);
925 }
926 assert(ctrl->is_CFG(), "CFG");
927 }
928 return ctrl;
929 }
930
931 Node* cast_incr_before_loop(Node* incr, Node* ctrl, Node* loop);
932
933 #ifdef ASSERT
934 void ensure_zero_trip_guard_proj(Node* node, bool is_main_loop);
935 #endif
936 void copy_assertion_predicates_to_main_loop_helper(const PredicateBlock* predicate_block, Node* init, Node* stride,
937 IdealLoopTree* outer_loop, LoopNode* outer_main_head,
938 uint dd_main_head, uint idx_before_pre_post,
939 uint idx_after_post_before_pre, Node* zero_trip_guard_proj_main,
940 Node* zero_trip_guard_proj_post, const Node_List &old_new);
941 void copy_assertion_predicates_to_main_loop(CountedLoopNode* pre_head, Node* init, Node* stride, IdealLoopTree* outer_loop,
942 LoopNode* outer_main_head, uint dd_main_head, uint idx_before_pre_post,
943 uint idx_after_post_before_pre, Node* zero_trip_guard_proj_main,
944 Node* zero_trip_guard_proj_post, const Node_List& old_new);
945 Node* clone_assertion_predicate_and_initialize(Node* iff, Node* new_init, Node* new_stride, Node* predicate,
946 Node* uncommon_proj, Node* control, IdealLoopTree* outer_loop,
947 Node* input_proj);
948 static void count_opaque_loop_nodes(Node* n, uint& init, uint& stride);
949 static bool subgraph_has_opaque(Node* n);
950 Node* create_bool_from_template_assertion_predicate(Node* template_assertion_predicate, Node* new_init, Node* new_stride,
951 Node* control);
952 static bool assertion_predicate_has_loop_opaque_node(IfNode* iff);
953 static void get_assertion_predicates(Node* predicate, Unique_Node_List& list, bool get_opaque = false);
954 void update_main_loop_assertion_predicates(Node* ctrl, CountedLoopNode* loop_head, Node* init, int stride_con);
955 void copy_assertion_predicates_to_post_loop(LoopNode* main_loop_head, CountedLoopNode* post_loop_head, Node* init,
956 Node* stride);
957 void initialize_assertion_predicates_for_peeled_loop(const PredicateBlock* predicate_block, LoopNode* outer_loop_head,
958 int dd_outer_loop_head, Node* init, Node* stride,
959 IdealLoopTree* outer_loop, uint idx_before_clone,
960 const Node_List& old_new);
961 void insert_loop_limit_check_predicate(ParsePredicateSuccessProj* loop_limit_check_parse_proj, Node* cmp_limit,
962 Node* bol);
963 #ifdef ASSERT
964 bool only_has_infinite_loops();
965 #endif
966
967 void log_loop_tree();
968
969 public:
970
971 PhaseIterGVN &igvn() const { return _igvn; }
972
973 bool has_node(const Node* n) const {
974 guarantee(n != nullptr, "No Node.");
975 return _loop_or_ctrl[n->_idx] != nullptr;
976 }
977 // check if transform created new nodes that need _ctrl recorded
978 Node *get_late_ctrl( Node *n, Node *early );
979 Node *get_early_ctrl( Node *n );
980 Node *get_early_ctrl_for_expensive(Node *n, Node* earliest);
981 void set_early_ctrl(Node* n, bool update_body);
982 void set_subtree_ctrl(Node* n, bool update_body);
983 void set_ctrl( Node *n, Node *ctrl ) {
984 assert( !has_node(n) || has_ctrl(n), "" );
985 assert( ctrl->in(0), "cannot set dead control node" );
986 assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" );
987 _loop_or_ctrl.map(n->_idx, (Node*)((intptr_t)ctrl + 1));
988 }
989 // Set control and update loop membership
990 void set_ctrl_and_loop(Node* n, Node* ctrl) {
991 IdealLoopTree* old_loop = get_loop(get_ctrl(n));
992 IdealLoopTree* new_loop = get_loop(ctrl);
993 if (old_loop != new_loop) {
994 if (old_loop->_child == nullptr) old_loop->_body.yank(n);
995 if (new_loop->_child == nullptr) new_loop->_body.push(n);
996 }
997 set_ctrl(n, ctrl);
998 }
999 // Control nodes can be replaced or subsumed. During this pass they
1000 // get their replacement Node in slot 1. Instead of updating the block
1001 // location of all Nodes in the subsumed block, we lazily do it. As we
1002 // pull such a subsumed block out of the array, we write back the final
1003 // correct block.
1004 Node* get_ctrl(const Node* i) {
1005 assert(has_node(i), "");
1006 Node *n = get_ctrl_no_update(i);
1007 _loop_or_ctrl.map(i->_idx, (Node*)((intptr_t)n + 1));
1008 assert(has_node(i) && has_ctrl(i), "");
1009 assert(n == find_non_split_ctrl(n), "must return legal ctrl" );
1010 return n;
1011 }
1012 // true if CFG node d dominates CFG node n
1013 bool is_dominator(Node *d, Node *n);
1014 // return get_ctrl for a data node and self(n) for a CFG node
1015 Node* ctrl_or_self(Node* n) {
1016 if (has_ctrl(n))
1017 return get_ctrl(n);
1018 else {
1019 assert (n->is_CFG(), "must be a CFG node");
1020 return n;
1021 }
1022 }
1023
1024 Node* get_ctrl_no_update_helper(const Node* i) const {
1025 assert(has_ctrl(i), "should be control, not loop");
1026 return (Node*)(((intptr_t)_loop_or_ctrl[i->_idx]) & ~1);
1027 }
1028
1029 Node* get_ctrl_no_update(const Node* i) const {
1030 assert( has_ctrl(i), "" );
1031 Node *n = get_ctrl_no_update_helper(i);
1032 if (!n->in(0)) {
1033 // Skip dead CFG nodes
1034 do {
1035 n = get_ctrl_no_update_helper(n);
1036 } while (!n->in(0));
1037 n = find_non_split_ctrl(n);
1038 }
1039 return n;
1040 }
1041
1042 // Check for loop being set
1043 // "n" must be a control node. Returns true if "n" is known to be in a loop.
1044 bool has_loop( Node *n ) const {
1045 assert(!has_node(n) || !has_ctrl(n), "");
1046 return has_node(n);
1047 }
1048 // Set loop
1049 void set_loop( Node *n, IdealLoopTree *loop ) {
1050 _loop_or_ctrl.map(n->_idx, (Node*)loop);
1051 }
1052 // Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms. Replace
1053 // the 'old_node' with 'new_node'. Kill old-node. Add a reference
1054 // from old_node to new_node to support the lazy update. Reference
1055 // replaces loop reference, since that is not needed for dead node.
1056 void lazy_update(Node *old_node, Node *new_node) {
1057 assert(old_node != new_node, "no cycles please");
1058 // Re-use the side array slot for this node to provide the
1059 // forwarding pointer.
1060 _loop_or_ctrl.map(old_node->_idx, (Node*)((intptr_t)new_node + 1));
1061 }
1062 void lazy_replace(Node *old_node, Node *new_node) {
1063 _igvn.replace_node(old_node, new_node);
1064 lazy_update(old_node, new_node);
1065 }
1066
1067 private:
1068
1069 // Place 'n' in some loop nest, where 'n' is a CFG node
1070 void build_loop_tree();
1071 int build_loop_tree_impl( Node *n, int pre_order );
1072 // Insert loop into the existing loop tree. 'innermost' is a leaf of the
1073 // loop tree, not the root.
1074 IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost );
1075
1076 #ifdef ASSERT
1077 // verify that regions in irreducible loops are marked is_in_irreducible_loop
1078 void verify_regions_in_irreducible_loops();
1079 bool is_in_irreducible_loop(RegionNode* region);
1080 #endif
1081
1082 // Place Data nodes in some loop nest
1083 void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
1084 void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
1085 void build_loop_late_post_work(Node* n, bool pinned);
1086 void build_loop_late_post(Node* n);
1087 void verify_strip_mined_scheduling(Node *n, Node* least);
1088
1089 // Array of immediate dominance info for each CFG node indexed by node idx
1090 private:
1091 uint _idom_size;
1092 Node **_idom; // Array of immediate dominators
1093 uint *_dom_depth; // Used for fast LCA test
1094 GrowableArray<uint>* _dom_stk; // For recomputation of dom depth
1095 LoopOptsMode _mode;
1096
1097 // build the loop tree and perform any requested optimizations
1098 void build_and_optimize();
1099
1100 // Dominators for the sea of nodes
1101 void Dominators();
1102
1103 // Compute the Ideal Node to Loop mapping
1104 PhaseIdealLoop(PhaseIterGVN& igvn, LoopOptsMode mode) :
1105 PhaseTransform(Ideal_Loop),
1106 _igvn(igvn),
1107 _verify_me(nullptr),
1108 _verify_only(false),
1109 _mode(mode),
1110 _nodes_required(UINT_MAX) {
1111 assert(mode != LoopOptsVerify, "wrong constructor to verify IdealLoop");
1112 build_and_optimize();
1113 }
1114
1115 #ifndef PRODUCT
1116 // Verify that verify_me made the same decisions as a fresh run
1117 // or only verify that the graph is valid if verify_me is null.
1118 PhaseIdealLoop(PhaseIterGVN& igvn, const PhaseIdealLoop* verify_me = nullptr) :
1119 PhaseTransform(Ideal_Loop),
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
1350 public:
1351 void register_control(Node* n, IdealLoopTree *loop, Node* pred, bool update_body = true);
1352
1353 // Construct a range check for a predicate if
1354 BoolNode* rc_predicate(IdealLoopTree* loop, Node* ctrl, int scale, Node* offset, Node* init, Node* limit,
1355 jint stride, Node* range, bool upper, bool& overflow);
1356
1357 // Implementation of the loop predication to promote checks outside the loop
1358 bool loop_predication_impl(IdealLoopTree *loop);
1359
1360 private:
1361 bool loop_predication_impl_helper(IdealLoopTree* loop, IfProjNode* if_success_proj,
1362 ParsePredicateSuccessProj* parse_predicate_proj, CountedLoopNode* cl, ConNode* zero,
1363 Invariance& invar, Deoptimization::DeoptReason reason);
1364 bool can_create_loop_predicates(const PredicateBlock* profiled_loop_predicate_block) const;
1365 bool loop_predication_should_follow_branches(IdealLoopTree* loop, float& loop_trip_cnt);
1366 void loop_predication_follow_branches(Node *c, IdealLoopTree *loop, float loop_trip_cnt,
1367 PathFrequency& pf, Node_Stack& stack, VectorSet& seen,
1368 Node_List& if_proj_list);
1369 IfProjNode* add_template_assertion_predicate(IfNode* iff, IdealLoopTree* loop, IfProjNode* if_proj,
1370 ParsePredicateSuccessProj* parse_predicate_proj,
1371 IfProjNode* upper_bound_proj, int scale, Node* offset, Node* init, Node* limit,
1372 jint stride, Node* rng, bool& overflow, Deoptimization::DeoptReason reason);
1373 Node* add_range_check_elimination_assertion_predicate(IdealLoopTree* loop, Node* predicate_proj, int scale_con,
1374 Node* offset, Node* limit, jint stride_con, Node* value);
1375
1376 // Helper function to collect predicate for eliminating the useless ones
1377 void eliminate_useless_predicates();
1378
1379 void eliminate_useless_parse_predicates();
1380 void mark_all_parse_predicates_useless() const;
1381 void mark_loop_associated_parse_predicates_useful();
1382 static void mark_useful_parse_predicates_for_loop(IdealLoopTree* loop);
1383 void add_useless_parse_predicates_to_igvn_worklist();
1384
1385 void eliminate_useless_template_assertion_predicates();
1386 void collect_useful_template_assertion_predicates(Unique_Node_List& useful_predicates);
1387 static void collect_useful_template_assertion_predicates_for_loop(IdealLoopTree* loop, Unique_Node_List& useful_predicates);
1388 void eliminate_useless_template_assertion_predicates(Unique_Node_List& useful_predicates);
1389
1390 void eliminate_useless_zero_trip_guard();
1391
1392 bool has_control_dependencies_from_predicates(LoopNode* head) const;
1393 void verify_fast_loop(LoopNode* head, const ProjNode* proj_true) const NOT_DEBUG_RETURN;
1394 public:
1395 // Change the control input of expensive nodes to allow commoning by
1396 // IGVN when it is guaranteed to not result in a more frequent
1397 // execution of the expensive node. Return true if progress.
1398 bool process_expensive_nodes();
1399
1400 // Check whether node has become unreachable
1401 bool is_node_unreachable(Node *n) const {
1402 return !has_node(n) || n->is_unreachable(_igvn);
1403 }
1404
1405 // Eliminate range-checks and other trip-counter vs loop-invariant tests.
1406 void do_range_check(IdealLoopTree *loop, Node_List &old_new);
1407
1408 // Create a slow version of the loop by cloning the loop
1409 // and inserting an if to select fast-slow versions.
1410 // Return the inserted if.
1411 IfNode* create_slow_version_of_loop(IdealLoopTree *loop,
1412 Node_List &old_new,
1413 IfNode* unswitch_iff,
1414 CloneLoopMode mode);
1415
1416 // Clone loop with an invariant test (that does not exit) and
1417 // insert a clone of the test that selects which version to
1418 // execute.
1419 void do_unswitching (IdealLoopTree *loop, Node_List &old_new);
1420
1421 // Find candidate "if" for unswitching
1422 IfNode* find_unswitching_candidate(const IdealLoopTree *loop) const;
1423
1424 // Range Check Elimination uses this function!
1425 // Constrain the main loop iterations so the affine function:
1426 // low_limit <= scale_con * I + offset < upper_limit
1427 // always holds true. That is, either increase the number of iterations in
1428 // the pre-loop or the post-loop until the condition holds true in the main
1429 // loop. Scale_con, offset and limit are all loop invariant.
1430 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);
1431 // Helper function for add_constraint().
1432 Node* adjust_limit(bool reduce, Node* scale, Node* offset, Node* rc_limit, Node* old_limit, Node* pre_ctrl, bool round);
1433
1434 // Partially peel loop up through last_peel node.
1435 bool partial_peel( IdealLoopTree *loop, Node_List &old_new );
1436 bool duplicate_loop_backedge(IdealLoopTree *loop, Node_List &old_new);
1437
1438 // Move UnorderedReduction out of loop if possible
1439 void move_unordered_reduction_out_of_loop(IdealLoopTree* loop);
1440
1441 // Create a scheduled list of nodes control dependent on ctrl set.
1442 void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched );
1443 // Has a use in the vector set
1444 bool has_use_in_set( Node* n, VectorSet& vset );
1445 // Has use internal to the vector set (ie. not in a phi at the loop head)
1446 bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop );
1447 // clone "n" for uses that are outside of loop
1448 int clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist );
1449 // clone "n" for special uses that are in the not_peeled region
1450 void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
1451 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist );
1452 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
1453 void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp );
1454 #ifdef ASSERT
1455 // Validate the loop partition sets: peel and not_peel
1456 bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel );
1457 // Ensure that uses outside of loop are of the right form
1458 bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
1459 uint orig_exit_idx, uint clone_exit_idx);
1460 bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx);
1461 #endif
1462
1463 // Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.)
1464 int stride_of_possible_iv( Node* iff );
1465 bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; }
1466 // Return the (unique) control output node that's in the loop (if it exists.)
1467 Node* stay_in_loop( Node* n, IdealLoopTree *loop);
1468 // Insert a signed compare loop exit cloned from an unsigned compare.
1469 IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop);
1470 void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop);
1471 // Utility to register node "n" with PhaseIdealLoop
1472 void register_node(Node* n, IdealLoopTree* loop, Node* pred, uint ddepth);
1473 // Utility to create an if-projection
1474 ProjNode* proj_clone(ProjNode* p, IfNode* iff);
1475 // Force the iff control output to be the live_proj
1476 Node* short_circuit_if(IfNode* iff, ProjNode* live_proj);
1477 // Insert a region before an if projection
1478 RegionNode* insert_region_before_proj(ProjNode* proj);
1479 // Insert a new if before an if projection
1480 ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj);
1481
1482 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1483 // "Nearly" because all Nodes have been cloned from the original in the loop,
1484 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1485 // through the Phi recursively, and return a Bool.
1486 Node* clone_iff(PhiNode* phi);
1487 CmpNode* clone_bool(PhiNode* phi);
1488
1489
1490 // Rework addressing expressions to get the most loop-invariant stuff
1491 // moved out. We'd like to do all associative operators, but it's especially
1492 // important (common) to do address expressions.
1493 Node* remix_address_expressions(Node* n);
1494 Node* remix_address_expressions_add_left_shift(Node* n, IdealLoopTree* n_loop, Node* n_ctrl, BasicType bt);
1495
1496 // Convert add to muladd to generate MuladdS2I under certain criteria
1497 Node * convert_add_to_muladd(Node * n);
1498
1499 // Attempt to use a conditional move instead of a phi/branch
1500 Node *conditional_move( Node *n );
1501
1502 // Check for aggressive application of 'split-if' optimization,
1503 // using basic block level info.
1504 void split_if_with_blocks ( VectorSet &visited, Node_Stack &nstack);
1505 Node *split_if_with_blocks_pre ( Node *n );
1506 void split_if_with_blocks_post( Node *n );
1507 Node *has_local_phi_input( Node *n );
1508 // Mark an IfNode as being dominated by a prior test,
1509 // without actually altering the CFG (and hence IDOM info).
1510 void dominated_by(IfProjNode* prevdom, IfNode* iff, bool flip = false, bool exclude_loop_predicate = false);
1511
1512 // Split Node 'n' through merge point
1513 RegionNode* split_thru_region(Node* n, RegionNode* region);
1514 // Split Node 'n' through merge point if there is enough win.
1515 Node *split_thru_phi( Node *n, Node *region, int policy );
1516 // Found an If getting its condition-code input from a Phi in the
1517 // same block. Split thru the Region.
1518 void do_split_if(Node *iff, RegionNode** new_false_region = nullptr, RegionNode** new_true_region = nullptr);
1519
1520 // Conversion of fill/copy patterns into intrinsic versions
1521 bool do_intrinsify_fill();
1522 bool intrinsify_fill(IdealLoopTree* lpt);
1523 bool match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value,
1524 Node*& shift, Node*& offset);
1525
1526 private:
1527 // Return a type based on condition control flow
1528 const TypeInt* filtered_type( Node *n, Node* n_ctrl);
1529 const TypeInt* filtered_type( Node *n ) { return filtered_type(n, nullptr); }
1530 // Helpers for filtered type
1531 const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl);
1532
1533 // Helper functions
1534 Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache );
1535 Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true );
1536 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 );
1537 bool split_up( Node *n, Node *blk1, Node *blk2 );
1538
1539 Node* place_outside_loop(Node* useblock, IdealLoopTree* loop) const;
1540 Node* try_move_store_before_loop(Node* n, Node *n_ctrl);
1541 void try_move_store_after_loop(Node* n);
1542 bool identical_backtoback_ifs(Node *n);
1543 bool can_split_if(Node *n_ctrl);
1544 bool cannot_split_division(const Node* n, const Node* region) const;
1545 static bool is_divisor_counted_loop_phi(const Node* divisor, const Node* loop);
1546 bool loop_phi_backedge_type_contains_zero(const Node* phi_divisor, const Type* zero) const;
1547
1548 // Determine if a method is too big for a/another round of split-if, based on
1549 // a magic (approximate) ratio derived from the equally magic constant 35000,
1550 // previously used for this purpose (but without relating to the node limit).
1551 bool must_throttle_split_if() {
1552 uint threshold = C->max_node_limit() * 2 / 5;
1553 return C->live_nodes() > threshold;
1554 }
1555
1556 // A simplistic node request tracking mechanism, where
1557 // = UINT_MAX Request not valid or made final.
1558 // < UINT_MAX Nodes currently requested (estimate).
1559 uint _nodes_required;
1560
1561 enum { REQUIRE_MIN = 70 };
1562
1563 uint nodes_required() const { return _nodes_required; }
1564
1565 // Given the _currently_ available number of nodes, check whether there is
1566 // "room" for an additional request or not, considering the already required
1567 // number of nodes. Return TRUE if the new request is exceeding the node
1568 // budget limit, otherwise return FALSE. Note that this interpretation will
1569 // act pessimistic on additional requests when new nodes have already been
1570 // generated since the 'begin'. This behaviour fits with the intention that
1571 // node estimates/requests should be made upfront.
1572 bool exceeding_node_budget(uint required = 0) {
1573 assert(C->live_nodes() < C->max_node_limit(), "sanity");
1574 uint available = C->max_node_limit() - C->live_nodes();
1575 return available < required + _nodes_required + REQUIRE_MIN;
1576 }
1577
1578 uint require_nodes(uint require, uint minreq = REQUIRE_MIN) {
1579 precond(require > 0);
1580 _nodes_required += MAX2(require, minreq);
1581 return _nodes_required;
1582 }
1583
1584 bool may_require_nodes(uint require, uint minreq = REQUIRE_MIN) {
1585 return !exceeding_node_budget(require) && require_nodes(require, minreq) > 0;
1586 }
1587
1588 uint require_nodes_begin() {
1589 assert(_nodes_required == UINT_MAX, "Bad state (begin).");
1590 _nodes_required = 0;
1591 return C->live_nodes();
1592 }
1593
1594 // When a node request is final, optionally check that the requested number
1595 // of nodes was reasonably correct with respect to the number of new nodes
1596 // introduced since the last 'begin'. Always check that we have not exceeded
1597 // the maximum node limit.
1598 void require_nodes_final(uint live_at_begin, bool check_estimate) {
1599 assert(_nodes_required < UINT_MAX, "Bad state (final).");
1600
1601 #ifdef ASSERT
1602 if (check_estimate) {
1603 // Check that the node budget request was not off by too much (x2).
1604 // Should this be the case we _surely_ need to improve the estimates
1605 // used in our budget calculations.
1606 if (C->live_nodes() - live_at_begin > 2 * _nodes_required) {
1607 log_info(compilation)("Bad node estimate: actual = %d >> request = %d",
1608 C->live_nodes() - live_at_begin, _nodes_required);
1609 }
1610 }
1611 #endif
1612 // Assert that we have stayed within the node budget limit.
1613 assert(C->live_nodes() < C->max_node_limit(),
1614 "Exceeding node budget limit: %d + %d > %d (request = %d)",
1615 C->live_nodes() - live_at_begin, live_at_begin,
1616 C->max_node_limit(), _nodes_required);
1617
1618 _nodes_required = UINT_MAX;
1619 }
1620
1621 // Clone Parse Predicates to slow and fast loop when unswitching a loop
1622 void clone_parse_and_assertion_predicates_to_unswitched_loop(IdealLoopTree* loop, Node_List& old_new,
1623 IfProjNode*& iffast_pred, IfProjNode*& ifslow_pred);
1624 void clone_loop_predication_predicates_to_unswitched_loop(IdealLoopTree* loop, const Node_List& old_new,
1625 const PredicateBlock* predicate_block,
1626 Deoptimization::DeoptReason reason, IfProjNode*& iffast_pred,
1627 IfProjNode*& ifslow_pred);
1628 void clone_parse_predicate_to_unswitched_loops(const PredicateBlock* predicate_block, Deoptimization::DeoptReason reason,
1629 IfProjNode*& iffast_pred, IfProjNode*& ifslow_pred);
1630 IfProjNode* clone_parse_predicate_to_unswitched_loop(ParsePredicateSuccessProj* parse_predicate_proj, Node* new_entry,
1631 Deoptimization::DeoptReason reason, bool slow_loop);
1632 void clone_assertion_predicates_to_unswitched_loop(IdealLoopTree* loop, const Node_List& old_new,
1633 Deoptimization::DeoptReason reason, IfProjNode* old_predicate_proj,
1634 ParsePredicateSuccessProj* fast_loop_parse_predicate_proj,
1635 ParsePredicateSuccessProj* slow_loop_parse_predicate_proj);
1636 IfProjNode* clone_assertion_predicate_for_unswitched_loops(Node* iff, IfProjNode* predicate,
1637 Deoptimization::DeoptReason reason,
1638 ParsePredicateSuccessProj* parse_predicate_proj);
1639 static void check_cloned_parse_predicate_for_unswitching(const Node* new_entry, bool is_fast_loop) PRODUCT_RETURN;
1640
1641 bool _created_loop_node;
1642 DEBUG_ONLY(void dump_idoms(Node* early, Node* wrong_lca);)
1643 NOT_PRODUCT(void dump_idoms_in_reverse(const Node* n, const Node_List& idom_list) const;)
1644
1645 public:
1646 void set_created_loop_node() { _created_loop_node = true; }
1647 bool created_loop_node() { return _created_loop_node; }
1648 void register_new_node(Node* n, Node* blk);
1649
1650 #ifdef ASSERT
1651 void dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA);
1652 #endif
1653
1654 #ifndef PRODUCT
1655 void dump() const;
1656 void dump_idom(Node* n) const { dump_idom(n, 1000); } // For debugging
1657 void dump_idom(Node* n, uint count) const;
1658 void get_idoms(Node* n, uint count, Unique_Node_List& idoms) const;
1659 void dump(IdealLoopTree* loop, uint rpo_idx, Node_List &rpo_list) const;
1660 IdealLoopTree* get_loop_idx(Node* n) const {
1661 // Dead nodes have no loop, so return the top level loop instead
1662 return _loop_or_ctrl[n->_idx] ? (IdealLoopTree*)_loop_or_ctrl[n->_idx] : _ltree_root;
1663 }
1664 // Print some stats
1665 static void print_statistics();
1666 static int _loop_invokes; // Count of PhaseIdealLoop invokes
1667 static int _loop_work; // Sum of PhaseIdealLoop x _unique
1668 static volatile int _long_loop_candidates;
1669 static volatile int _long_loop_nests;
1670 static volatile int _long_loop_counted_loops;
1671 #endif
1672
1673 #ifdef ASSERT
1674 void verify() const;
1675 bool verify_idom_and_nodes(Node* root, const PhaseIdealLoop* phase_verify) const;
1676 bool verify_idom(Node* n, const PhaseIdealLoop* phase_verify) const;
1677 bool verify_loop_ctrl(Node* n, const PhaseIdealLoop* phase_verify) const;
1678 #endif
1679
1680 void rpo(Node* start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list) const;
1681
1682 void check_counted_loop_shape(IdealLoopTree* loop, Node* x, BasicType bt) NOT_DEBUG_RETURN;
1683
1684 LoopNode* create_inner_head(IdealLoopTree* loop, BaseCountedLoopNode* head, IfNode* exit_test);
1685
1686
1687 int extract_long_range_checks(const IdealLoopTree* loop, jlong stride_con, int iters_limit, PhiNode* phi,
1688 Node_List &range_checks);
1689
1690 void transform_long_range_checks(int stride_con, const Node_List &range_checks, Node* outer_phi,
1691 Node* inner_iters_actual_int, Node* inner_phi,
1692 Node* iv_add, LoopNode* inner_head);
1693
1694 Node* get_late_ctrl_with_anti_dep(LoadNode* n, Node* early, Node* LCA);
1695
1696 bool ctrl_of_use_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop, Node* ctrl);
1697
1698 bool ctrl_of_all_uses_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop);
1699
1700 Node* compute_early_ctrl(Node* n, Node* n_ctrl);
1701
1702 void try_sink_out_of_loop(Node* n);
1703
1704 Node* clamp(Node* R, Node* L, Node* H);
1705
1706 bool safe_for_if_replacement(const Node* dom) const;
1707
1708 void push_pinned_nodes_thru_region(IfNode* dom_if, Node* region);
1709
1710 bool try_merge_identical_ifs(Node* n);
1711
1712 void clone_loop_body(const Node_List& body, Node_List &old_new, CloneMap* cm);
1713
1714 void fix_body_edges(const Node_List &body, IdealLoopTree* loop, const Node_List &old_new, int dd,
1715 IdealLoopTree* parent, bool partial);
1716
1717 void fix_ctrl_uses(const Node_List& body, const IdealLoopTree* loop, Node_List &old_new, CloneLoopMode mode,
1718 Node* side_by_side_idom, CloneMap* cm, Node_List &worklist);
1719
1720 void fix_data_uses(Node_List& body, IdealLoopTree* loop, CloneLoopMode mode, IdealLoopTree* outer_loop,
1721 uint new_counter, Node_List& old_new, Node_List& worklist, Node_List*& split_if_set,
1722 Node_List*& split_bool_set, Node_List*& split_cex_set);
1723
1724 void finish_clone_loop(Node_List* split_if_set, Node_List* split_bool_set, Node_List* split_cex_set);
1725
1726 bool clone_cmp_down(Node* n, const Node* blk1, const Node* blk2);
1727
1728 void clone_loadklass_nodes_at_cmp_index(const Node* n, Node* cmp, int i);
1729
1730 bool clone_cmp_loadklass_down(Node* n, const Node* blk1, const Node* blk2);
1731
1732 bool at_relevant_ctrl(Node* n, const Node* blk1, const Node* blk2);
1733
1734
1735 Node* similar_subtype_check(const Node* x, Node* r_in);
1736
1737 void update_addp_chain_base(Node* x, Node* old_base, Node* new_base);
1738
1739 bool can_move_to_inner_loop(Node* n, LoopNode* n_loop, Node* x);
1740 };
1741
1742
1743 class AutoNodeBudget : public StackObj
1744 {
1745 public:
1746 enum budget_check_t { BUDGET_CHECK, NO_BUDGET_CHECK };
1747
1748 AutoNodeBudget(PhaseIdealLoop* phase, budget_check_t chk = BUDGET_CHECK)
1749 : _phase(phase),
1750 _check_at_final(chk == BUDGET_CHECK),
1751 _nodes_at_begin(0)
1752 {
1753 precond(_phase != nullptr);
1754
1755 _nodes_at_begin = _phase->require_nodes_begin();
1756 }
1757
1758 ~AutoNodeBudget() {
1759 #ifndef PRODUCT
1760 if (TraceLoopOpts) {
1761 uint request = _phase->nodes_required();
1762 uint delta = _phase->C->live_nodes() - _nodes_at_begin;
1763
1764 if (request < delta) {
1765 tty->print_cr("Exceeding node budget: %d < %d", request, delta);
1766 } else {
1767 uint const REQUIRE_MIN = PhaseIdealLoop::REQUIRE_MIN;
1768 // Identify the worst estimates as "poor" ones.
1769 if (request > REQUIRE_MIN && delta > 0) {
1770 if ((delta > REQUIRE_MIN && request > 3 * delta) ||
1771 (delta <= REQUIRE_MIN && request > 10 * delta)) {
1772 tty->print_cr("Poor node estimate: %d >> %d", request, delta);
1773 }
1774 }
1775 }
1776 }
1777 #endif // PRODUCT
1778 _phase->require_nodes_final(_nodes_at_begin, _check_at_final);
1779 }
1780
1781 private:
1782 PhaseIdealLoop* _phase;
1783 bool _check_at_final;
1784 uint _nodes_at_begin;
1785 };
1786
1787 inline Node* IdealLoopTree::tail() {
1788 // Handle lazy update of _tail field.
1789 if (_tail->in(0) == nullptr) {
1790 _tail = _phase->get_ctrl(_tail);
1791 }
1792 return _tail;
1793 }
1794
1795 inline Node* IdealLoopTree::head() {
1796 // Handle lazy update of _head field.
1797 if (_head->in(0) == nullptr) {
1798 _head = _phase->get_ctrl(_head);
1799 }
1800 return _head;
1801 }
1802
1803 // Iterate over the loop tree using a preorder, left-to-right traversal.
1804 //
1805 // Example that visits all counted loops from within PhaseIdealLoop
1806 //
1807 // for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
1808 // IdealLoopTree* lpt = iter.current();
1809 // if (!lpt->is_counted()) continue;
1810 // ...
1811 class LoopTreeIterator : public StackObj {
1812 private:
1813 IdealLoopTree* _root;
1814 IdealLoopTree* _curnt;
1815
1816 public:
1817 LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {}
1818
1819 bool done() { return _curnt == nullptr; } // Finished iterating?
1820
1821 void next(); // Advance to next loop tree
1822
1823 IdealLoopTree* current() { return _curnt; } // Return current value of iterator.
1824 };
1825
1826 // Compute probability of reaching some CFG node from a fixed
1827 // dominating CFG node
1828 class PathFrequency {
1829 private:
1830 Node* _dom; // frequencies are computed relative to this node
1831 Node_Stack _stack;
1832 GrowableArray<float> _freqs_stack; // keep track of intermediate result at regions
1833 GrowableArray<float> _freqs; // cache frequencies
1834 PhaseIdealLoop* _phase;
1835
1836 float check_and_truncate_frequency(float f) {
1837 assert(f >= 0, "Incorrect frequency");
1838 // We do not perform an exact (f <= 1) check
1839 // this would be error prone with rounding of floats.
1840 // Performing a check like (f <= 1+eps) would be of benefit,
1841 // however, it is not evident how to determine such an eps,
1842 // given that an arbitrary number of add/mul operations
1843 // are performed on these frequencies.
1844 return (f > 1) ? 1 : f;
1845 }
1846
1847 public:
1848 PathFrequency(Node* dom, PhaseIdealLoop* phase)
1849 : _dom(dom), _stack(0), _phase(phase) {
1850 }
1851
1852 float to(Node* n);
1853 };
1854
1855 #endif // SHARE_OPTO_LOOPNODE_HPP