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