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