1 /*
2 * Copyright (c) 1998, 2024, 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.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
24
25 #ifndef SHARE_OPTO_LOOPNODE_HPP
26 #define SHARE_OPTO_LOOPNODE_HPP
27
28 #include "opto/cfgnode.hpp"
29 #include "opto/multnode.hpp"
30 #include "opto/phaseX.hpp"
31 #include "opto/predicates.hpp"
32 #include "opto/subnode.hpp"
33 #include "opto/type.hpp"
34 #include "utilities/checkedCast.hpp"
35
36 class CmpNode;
37 class BaseCountedLoopEndNode;
38 class CountedLoopNode;
39 class IdealLoopTree;
40 class LoopNode;
41 class Node;
42 class OuterStripMinedLoopEndNode;
43 class PredicateBlock;
44 class PathFrequency;
45 class PhaseIdealLoop;
46 class UnswitchedLoopSelector;
47 class VectorSet;
48 class VSharedData;
49 class Invariance;
50 struct small_cache;
51
52 //
53 // I D E A L I Z E D L O O P S
54 //
55 // Idealized loops are the set of loops I perform more interesting
56 // transformations on, beyond simple hoisting.
57
58 //------------------------------LoopNode---------------------------------------
59 // Simple loop header. Fall in path on left, loop-back path on right.
60 class LoopNode : public RegionNode {
61 // Size is bigger to hold the flags. However, the flags do not change
62 // the semantics so it does not appear in the hash & cmp functions.
63 virtual uint size_of() const { return sizeof(*this); }
64 protected:
65 uint _loop_flags;
66 // Names for flag bitfields
67 enum { Normal=0, Pre=1, Main=2, Post=3, PreMainPostFlagsMask=3,
68 MainHasNoPreLoop = 1<<2,
69 HasExactTripCount = 1<<3,
70 InnerLoop = 1<<4,
71 PartialPeelLoop = 1<<5,
72 PartialPeelFailed = 1<<6,
73 WasSlpAnalyzed = 1<<7,
74 PassedSlpAnalysis = 1<<8,
75 DoUnrollOnly = 1<<9,
76 VectorizedLoop = 1<<10,
77 HasAtomicPostLoop = 1<<11,
78 StripMined = 1<<12,
79 SubwordLoop = 1<<13,
80 ProfileTripFailed = 1<<14,
81 LoopNestInnerLoop = 1<<15,
82 LoopNestLongOuterLoop = 1<<16 };
83 char _unswitch_count;
84 enum { _unswitch_max=3 };
85
86 // Expected trip count from profile data
87 float _profile_trip_cnt;
88
89 public:
90 // Names for edge indices
91 enum { Self=0, EntryControl, LoopBackControl };
92
93 bool is_inner_loop() const { return _loop_flags & InnerLoop; }
94 void set_inner_loop() { _loop_flags |= InnerLoop; }
95
96 bool is_vectorized_loop() const { return _loop_flags & VectorizedLoop; }
97 bool is_partial_peel_loop() const { return _loop_flags & PartialPeelLoop; }
98 void set_partial_peel_loop() { _loop_flags |= PartialPeelLoop; }
99 bool partial_peel_has_failed() const { return _loop_flags & PartialPeelFailed; }
100 bool is_strip_mined() const { return _loop_flags & StripMined; }
101 bool is_profile_trip_failed() const { return _loop_flags & ProfileTripFailed; }
102 bool is_subword_loop() const { return _loop_flags & SubwordLoop; }
103 bool is_loop_nest_inner_loop() const { return _loop_flags & LoopNestInnerLoop; }
104 bool is_loop_nest_outer_loop() const { return _loop_flags & LoopNestLongOuterLoop; }
105
106 void mark_partial_peel_failed() { _loop_flags |= PartialPeelFailed; }
107 void mark_was_slp() { _loop_flags |= WasSlpAnalyzed; }
108 void mark_passed_slp() { _loop_flags |= PassedSlpAnalysis; }
109 void mark_do_unroll_only() { _loop_flags |= DoUnrollOnly; }
110 void mark_loop_vectorized() { _loop_flags |= VectorizedLoop; }
111 void mark_has_atomic_post_loop() { _loop_flags |= HasAtomicPostLoop; }
112 void mark_strip_mined() { _loop_flags |= StripMined; }
113 void clear_strip_mined() { _loop_flags &= ~StripMined; }
114 void mark_profile_trip_failed() { _loop_flags |= ProfileTripFailed; }
115 void mark_subword_loop() { _loop_flags |= SubwordLoop; }
116 void mark_loop_nest_inner_loop() { _loop_flags |= LoopNestInnerLoop; }
117 void mark_loop_nest_outer_loop() { _loop_flags |= LoopNestLongOuterLoop; }
118
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 public:
238 CountedLoopNode(Node *entry, Node *backedge)
239 : BaseCountedLoopNode(entry, backedge), _main_idx(0), _trip_count(max_juint),
240 _unrolled_count_log2(0), _node_count_before_unroll(0),
241 _slp_maximum_unroll_factor(0) {
242 init_class_id(Class_CountedLoop);
243 // Initialize _trip_count to the largest possible value.
244 // Will be reset (lower) if the loop's trip count is known.
245 }
246
247 virtual int Opcode() const;
248 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
249
250 CountedLoopEndNode* loopexit_or_null() const { return (CountedLoopEndNode*) BaseCountedLoopNode::loopexit_or_null(); }
251 CountedLoopEndNode* loopexit() const { return (CountedLoopEndNode*) BaseCountedLoopNode::loopexit(); }
252 int stride_con() const;
253
254 // Match increment with optional truncation
255 static Node*
256 match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInteger** trunc_type,
257 BasicType bt);
258
259 // A 'main' loop has a pre-loop and a post-loop. The 'main' loop
260 // can run short a few iterations and may start a few iterations in.
261 // It will be RCE'd and unrolled and aligned.
262
263 // A following 'post' loop will run any remaining iterations. Used
264 // during Range Check Elimination, the 'post' loop will do any final
265 // iterations with full checks. Also used by Loop Unrolling, where
266 // the 'post' loop will do any epilog iterations needed. Basically,
267 // a 'post' loop can not profitably be further unrolled or RCE'd.
268
269 // A preceding 'pre' loop will run at least 1 iteration (to do peeling),
270 // it may do under-flow checks for RCE and may do alignment iterations
271 // so the following main loop 'knows' that it is striding down cache
272 // lines.
273
274 // A 'main' loop that is ONLY unrolled or peeled, never RCE'd or
275 // Aligned, may be missing it's pre-loop.
276 bool is_normal_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Normal; }
277 bool is_pre_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Pre; }
278 bool is_main_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Main; }
279 bool is_post_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Post; }
280 bool was_slp_analyzed () const { return (_loop_flags&WasSlpAnalyzed) == WasSlpAnalyzed; }
281 bool has_passed_slp () const { return (_loop_flags&PassedSlpAnalysis) == PassedSlpAnalysis; }
282 bool is_unroll_only () const { return (_loop_flags&DoUnrollOnly) == DoUnrollOnly; }
283 bool is_main_no_pre_loop() const { return _loop_flags & MainHasNoPreLoop; }
284 bool has_atomic_post_loop () const { return (_loop_flags & HasAtomicPostLoop) == HasAtomicPostLoop; }
285 void set_main_no_pre_loop() { _loop_flags |= MainHasNoPreLoop; }
286
287 int main_idx() const { return _main_idx; }
288
289
290 void set_pre_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; }
291 void set_main_loop ( ) { assert(is_normal_loop(),""); _loop_flags |= Main; }
292 void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; }
293 void set_normal_loop( ) { _loop_flags &= ~PreMainPostFlagsMask; }
294
295 void set_trip_count(uint tc) { _trip_count = tc; }
296 uint trip_count() { return _trip_count; }
297
298 bool has_exact_trip_count() const { return (_loop_flags & HasExactTripCount) != 0; }
299 void set_exact_trip_count(uint tc) {
300 _trip_count = tc;
301 _loop_flags |= HasExactTripCount;
302 }
303 void set_nonexact_trip_count() {
304 _loop_flags &= ~HasExactTripCount;
305 }
306 void set_notpassed_slp() {
307 _loop_flags &= ~PassedSlpAnalysis;
308 }
309
310 void double_unrolled_count() { _unrolled_count_log2++; }
311 int unrolled_count() { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); }
312
313 void set_node_count_before_unroll(int ct) { _node_count_before_unroll = ct; }
314 int node_count_before_unroll() { return _node_count_before_unroll; }
315 void set_slp_max_unroll(int unroll_factor) { _slp_maximum_unroll_factor = unroll_factor; }
316 int slp_max_unroll() const { return _slp_maximum_unroll_factor; }
317
318 virtual LoopNode* skip_strip_mined(int expect_skeleton = 1);
319 OuterStripMinedLoopNode* outer_loop() const;
320 virtual IfTrueNode* outer_loop_tail() const;
321 virtual OuterStripMinedLoopEndNode* outer_loop_end() const;
322 virtual IfFalseNode* outer_loop_exit() const;
323 virtual SafePointNode* outer_safepoint() const;
324
325 Node* skip_assertion_predicates_with_halt();
326
327 virtual BasicType bt() const {
328 return T_INT;
329 }
330
331 Node* is_canonical_loop_entry();
332 CountedLoopEndNode* find_pre_loop_end();
333
334 #ifndef PRODUCT
335 virtual void dump_spec(outputStream *st) const;
336 #endif
337 };
338
339 class LongCountedLoopNode : public BaseCountedLoopNode {
340 public:
341 LongCountedLoopNode(Node *entry, Node *backedge)
342 : BaseCountedLoopNode(entry, backedge) {
343 init_class_id(Class_LongCountedLoop);
344 }
345
346 virtual int Opcode() const;
347
348 virtual BasicType bt() const {
349 return T_LONG;
350 }
351
352 LongCountedLoopEndNode* loopexit_or_null() const { return (LongCountedLoopEndNode*) BaseCountedLoopNode::loopexit_or_null(); }
353 LongCountedLoopEndNode* loopexit() const { return (LongCountedLoopEndNode*) BaseCountedLoopNode::loopexit(); }
354 };
355
356
357 //------------------------------CountedLoopEndNode-----------------------------
358 // CountedLoopEndNodes end simple trip counted loops. They act much like
359 // IfNodes.
360
361 class BaseCountedLoopEndNode : public IfNode {
362 public:
363 enum { TestControl, TestValue };
364 BaseCountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
365 : IfNode(control, test, prob, cnt) {
366 init_class_id(Class_BaseCountedLoopEnd);
367 }
368
369 Node *cmp_node() const { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : nullptr; }
370 Node* incr() const { Node* tmp = cmp_node(); return (tmp && tmp->req() == 3) ? tmp->in(1) : nullptr; }
371 Node* limit() const { Node* tmp = cmp_node(); return (tmp && tmp->req() == 3) ? tmp->in(2) : nullptr; }
372 Node* stride() const { Node* tmp = incr(); return (tmp && tmp->req() == 3) ? tmp->in(2) : nullptr; }
373 Node* init_trip() const { Node* tmp = phi(); return (tmp && tmp->req() == 3) ? tmp->in(1) : nullptr; }
374 bool stride_is_con() const { Node *tmp = stride(); return (tmp != nullptr && tmp->is_Con()); }
375
376 PhiNode* phi() const {
377 Node* tmp = incr();
378 if (tmp && tmp->req() == 3) {
379 Node* phi = tmp->in(1);
380 if (phi->is_Phi()) {
381 return phi->as_Phi();
382 }
383 }
384 return nullptr;
385 }
386
387 BaseCountedLoopNode* loopnode() const {
388 // The CountedLoopNode that goes with this CountedLoopEndNode may
389 // have been optimized out by the IGVN so be cautious with the
390 // pattern matching on the graph
391 PhiNode* iv_phi = phi();
392 if (iv_phi == nullptr) {
393 return nullptr;
394 }
395 Node* ln = iv_phi->in(0);
396 if (!ln->is_BaseCountedLoop() || ln->as_BaseCountedLoop()->loopexit_or_null() != this) {
397 return nullptr;
398 }
399 if (ln->as_BaseCountedLoop()->bt() != bt()) {
400 return nullptr;
401 }
402 return ln->as_BaseCountedLoop();
403 }
404
405 BoolTest::mask test_trip() const { return in(TestValue)->as_Bool()->_test._test; }
406
407 jlong stride_con() const;
408 virtual BasicType bt() const = 0;
409
410 static BaseCountedLoopEndNode* make(Node* control, Node* test, float prob, float cnt, BasicType bt);
411 };
412
413 class CountedLoopEndNode : public BaseCountedLoopEndNode {
414 public:
415
416 CountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
417 : BaseCountedLoopEndNode(control, test, prob, cnt) {
418 init_class_id(Class_CountedLoopEnd);
419 }
420 virtual int Opcode() const;
421
422 CountedLoopNode* loopnode() const {
423 return (CountedLoopNode*) BaseCountedLoopEndNode::loopnode();
424 }
425
426 virtual BasicType bt() const {
427 return T_INT;
428 }
429
430 #ifndef PRODUCT
431 virtual void dump_spec(outputStream *st) const;
432 #endif
433 };
434
435 class LongCountedLoopEndNode : public BaseCountedLoopEndNode {
436 public:
437 LongCountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
438 : BaseCountedLoopEndNode(control, test, prob, cnt) {
439 init_class_id(Class_LongCountedLoopEnd);
440 }
441
442 LongCountedLoopNode* loopnode() const {
443 return (LongCountedLoopNode*) BaseCountedLoopEndNode::loopnode();
444 }
445
446 virtual int Opcode() const;
447
448 virtual BasicType bt() const {
449 return T_LONG;
450 }
451 };
452
453
454 inline BaseCountedLoopEndNode* BaseCountedLoopNode::loopexit_or_null() const {
455 Node* bctrl = back_control();
456 if (bctrl == nullptr) return nullptr;
457
458 Node* lexit = bctrl->in(0);
459 if (!lexit->is_BaseCountedLoopEnd()) {
460 return nullptr;
461 }
462 BaseCountedLoopEndNode* result = lexit->as_BaseCountedLoopEnd();
463 if (result->bt() != bt()) {
464 return nullptr;
465 }
466 return result;
467 }
468
469 inline BaseCountedLoopEndNode* BaseCountedLoopNode::loopexit() const {
470 BaseCountedLoopEndNode* cle = loopexit_or_null();
471 assert(cle != nullptr, "loopexit is null");
472 return cle;
473 }
474
475 inline Node* BaseCountedLoopNode::init_trip() const {
476 BaseCountedLoopEndNode* cle = loopexit_or_null();
477 return cle != nullptr ? cle->init_trip() : nullptr;
478 }
479 inline Node* BaseCountedLoopNode::stride() const {
480 BaseCountedLoopEndNode* cle = loopexit_or_null();
481 return cle != nullptr ? cle->stride() : nullptr;
482 }
483
484 inline bool BaseCountedLoopNode::stride_is_con() const {
485 BaseCountedLoopEndNode* cle = loopexit_or_null();
486 return cle != nullptr && cle->stride_is_con();
487 }
488 inline Node* BaseCountedLoopNode::limit() const {
489 BaseCountedLoopEndNode* cle = loopexit_or_null();
490 return cle != nullptr ? cle->limit() : nullptr;
491 }
492 inline Node* BaseCountedLoopNode::incr() const {
493 BaseCountedLoopEndNode* cle = loopexit_or_null();
494 return cle != nullptr ? cle->incr() : nullptr;
495 }
496 inline Node* BaseCountedLoopNode::phi() const {
497 BaseCountedLoopEndNode* cle = loopexit_or_null();
498 return cle != nullptr ? cle->phi() : nullptr;
499 }
500
501 inline jlong BaseCountedLoopNode::stride_con() const {
502 BaseCountedLoopEndNode* cle = loopexit_or_null();
503 return cle != nullptr ? cle->stride_con() : 0;
504 }
505
506
507 //------------------------------LoopLimitNode-----------------------------
508 // Counted Loop limit node which represents exact final iterator value:
509 // trip_count = (limit - init_trip + stride - 1)/stride
510 // final_value= trip_count * stride + init_trip.
511 // Use HW instructions to calculate it when it can overflow in integer.
512 // Note, final_value should fit into integer since counted loop has
513 // limit check: limit <= max_int-stride.
514 class LoopLimitNode : public Node {
515 enum { Init=1, Limit=2, Stride=3 };
516 public:
517 LoopLimitNode( Compile* C, Node *init, Node *limit, Node *stride ) : Node(nullptr,init,limit,stride) {
518 // Put it on the Macro nodes list to optimize during macro nodes expansion.
519 init_flags(Flag_is_macro);
520 C->add_macro_node(this);
521 }
522 virtual int Opcode() const;
523 virtual const Type *bottom_type() const { return TypeInt::INT; }
524 virtual uint ideal_reg() const { return Op_RegI; }
525 virtual const Type* Value(PhaseGVN* phase) const;
526 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
527 virtual Node* Identity(PhaseGVN* phase);
528 };
529
530 // Support for strip mining
531 class OuterStripMinedLoopNode : public LoopNode {
532 private:
533 static void fix_sunk_stores(CountedLoopEndNode* inner_cle, LoopNode* inner_cl, PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
534
535 public:
536 OuterStripMinedLoopNode(Compile* C, Node *entry, Node *backedge)
537 : LoopNode(entry, backedge) {
538 init_class_id(Class_OuterStripMinedLoop);
539 init_flags(Flag_is_macro);
540 C->add_macro_node(this);
541 }
542
543 virtual int Opcode() const;
544
545 virtual IfTrueNode* outer_loop_tail() const;
546 virtual OuterStripMinedLoopEndNode* outer_loop_end() const;
547 virtual IfFalseNode* outer_loop_exit() const;
548 virtual SafePointNode* outer_safepoint() const;
549 void adjust_strip_mined_loop(PhaseIterGVN* igvn);
550
551 void remove_outer_loop_and_safepoint(PhaseIterGVN* igvn) const;
552
553 void transform_to_counted_loop(PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
554
555 static Node* register_new_node(Node* node, LoopNode* ctrl, PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
556
557 Node* register_control(Node* node, Node* loop, Node* idom, PhaseIterGVN* igvn,
558 PhaseIdealLoop* iloop);
559 };
560
561 class OuterStripMinedLoopEndNode : public IfNode {
562 public:
563 OuterStripMinedLoopEndNode(Node *control, Node *test, float prob, float cnt)
564 : IfNode(control, test, prob, cnt) {
565 init_class_id(Class_OuterStripMinedLoopEnd);
566 }
567
568 virtual int Opcode() const;
569
570 virtual const Type* Value(PhaseGVN* phase) const;
571 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
572
573 bool is_expanded(PhaseGVN *phase) const;
574 };
575
576 // -----------------------------IdealLoopTree----------------------------------
577 class IdealLoopTree : public ResourceObj {
578 public:
579 IdealLoopTree *_parent; // Parent in loop tree
580 IdealLoopTree *_next; // Next sibling in loop tree
581 IdealLoopTree *_child; // First child in loop tree
582
583 // The head-tail backedge defines the loop.
584 // If a loop has multiple backedges, this is addressed during cleanup where
585 // we peel off the multiple backedges, merging all edges at the bottom and
586 // ensuring that one proper backedge flow into the loop.
587 Node *_head; // Head of loop
588 Node *_tail; // Tail of loop
589 inline Node *tail(); // Handle lazy update of _tail field
590 inline Node *head(); // Handle lazy update of _head field
591 PhaseIdealLoop* _phase;
592 int _local_loop_unroll_limit;
593 int _local_loop_unroll_factor;
594
595 Node_List _body; // Loop body for inner loops
596
597 uint16_t _nest; // Nesting depth
598 uint8_t _irreducible:1, // True if irreducible
599 _has_call:1, // True if has call safepoint
600 _has_sfpt:1, // True if has non-call safepoint
601 _rce_candidate:1, // True if candidate for range check elimination
602 _has_range_checks:1,
603 _has_range_checks_computed:1;
604
605 Node_List* _safepts; // List of safepoints in this loop
606 Node_List* _required_safept; // A inner loop cannot delete these safepts;
607 bool _allow_optimizations; // Allow loop optimizations
608
609 IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail )
610 : _parent(nullptr), _next(nullptr), _child(nullptr),
611 _head(head), _tail(tail),
612 _phase(phase),
613 _local_loop_unroll_limit(0), _local_loop_unroll_factor(0),
614 _body(Compile::current()->comp_arena()),
615 _nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0),
616 _has_range_checks(0), _has_range_checks_computed(0),
617 _safepts(nullptr),
618 _required_safept(nullptr),
619 _allow_optimizations(true)
620 {
621 precond(_head != nullptr);
622 precond(_tail != nullptr);
623 }
624
625 // Is 'l' a member of 'this'?
626 bool is_member(const IdealLoopTree *l) const; // Test for nested membership
627
628 // Set loop nesting depth. Accumulate has_call bits.
629 int set_nest( uint depth );
630
631 // Split out multiple fall-in edges from the loop header. Move them to a
632 // private RegionNode before the loop. This becomes the loop landing pad.
633 void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt );
634
635 // Split out the outermost loop from this shared header.
636 void split_outer_loop( PhaseIdealLoop *phase );
637
638 // Merge all the backedges from the shared header into a private Region.
639 // Feed that region as the one backedge to this loop.
640 void merge_many_backedges( PhaseIdealLoop *phase );
641
642 // Split shared headers and insert loop landing pads.
643 // Insert a LoopNode to replace the RegionNode.
644 // Returns TRUE if loop tree is structurally changed.
645 bool beautify_loops( PhaseIdealLoop *phase );
646
647 // Perform optimization to use the loop predicates for null checks and range checks.
648 // Applies to any loop level (not just the innermost one)
649 bool loop_predication( PhaseIdealLoop *phase);
650 bool can_apply_loop_predication();
651
652 // Perform iteration-splitting on inner loops. Split iterations to
653 // avoid range checks or one-shot null checks. Returns false if the
654 // current round of loop opts should stop.
655 bool iteration_split( PhaseIdealLoop *phase, Node_List &old_new );
656
657 // Driver for various flavors of iteration splitting. Returns false
658 // if the current round of loop opts should stop.
659 bool iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new );
660
661 // Given dominators, try to find loops with calls that must always be
662 // executed (call dominates loop tail). These loops do not need non-call
663 // safepoints (ncsfpt).
664 void check_safepts(VectorSet &visited, Node_List &stack);
665
666 // Allpaths backwards scan from loop tail, terminating each path at first safepoint
667 // encountered.
668 void allpaths_check_safepts(VectorSet &visited, Node_List &stack);
669
670 // Remove safepoints from loop. Optionally keeping one.
671 void remove_safepoints(PhaseIdealLoop* phase, bool keep_one);
672
673 // Convert to counted loops where possible
674 void counted_loop( PhaseIdealLoop *phase );
675
676 // Check for Node being a loop-breaking test
677 Node *is_loop_exit(Node *iff) const;
678
679 // Remove simplistic dead code from loop body
680 void DCE_loop_body();
681
682 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage.
683 // Replace with a 1-in-10 exit guess.
684 void adjust_loop_exit_prob( PhaseIdealLoop *phase );
685
686 // Return TRUE or FALSE if the loop should never be RCE'd or aligned.
687 // Useful for unrolling loops with NO array accesses.
688 bool policy_peel_only( PhaseIdealLoop *phase ) const;
689
690 // Return TRUE or FALSE if the loop should be unswitched -- clone
691 // loop with an invariant test
692 bool policy_unswitching( PhaseIdealLoop *phase ) const;
693
694 // Micro-benchmark spamming. Remove empty loops.
695 bool do_remove_empty_loop( PhaseIdealLoop *phase );
696
697 // Convert one iteration loop into normal code.
698 bool do_one_iteration_loop( PhaseIdealLoop *phase );
699
700 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can
701 // move some loop-invariant test (usually a null-check) before the loop.
702 bool policy_peeling(PhaseIdealLoop *phase);
703
704 uint estimate_peeling(PhaseIdealLoop *phase);
705
706 // Return TRUE or FALSE if the loop should be maximally unrolled. Stash any
707 // known trip count in the counted loop node.
708 bool policy_maximally_unroll(PhaseIdealLoop *phase) const;
709
710 // Return TRUE or FALSE if the loop should be unrolled or not. Apply unroll
711 // if the loop is a counted loop and the loop body is small enough.
712 bool policy_unroll(PhaseIdealLoop *phase);
713
714 // Loop analyses to map to a maximal superword unrolling for vectorization.
715 void policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_ct);
716
717 // Return TRUE or FALSE if the loop should be range-check-eliminated.
718 // Gather a list of IF tests that are dominated by iteration splitting;
719 // also gather the end of the first split and the start of the 2nd split.
720 bool policy_range_check(PhaseIdealLoop* phase, bool provisional, BasicType bt) const;
721
722 // Return TRUE if "iff" is a range check.
723 bool is_range_check_if(IfProjNode* if_success_proj, PhaseIdealLoop* phase, Invariance& invar DEBUG_ONLY(COMMA ProjNode* predicate_proj)) const;
724 bool is_range_check_if(IfProjNode* if_success_proj, PhaseIdealLoop* phase, BasicType bt, Node* iv, Node*& range, Node*& offset,
725 jlong& scale) const;
726
727 // Estimate the number of nodes required when cloning a loop (body).
728 uint est_loop_clone_sz(uint factor) const;
729 // Estimate the number of nodes required when unrolling a loop (body).
730 uint est_loop_unroll_sz(uint factor) const;
731
732 // Compute loop trip count if possible
733 void compute_trip_count(PhaseIdealLoop* phase);
734
735 // Compute loop trip count from profile data
736 float compute_profile_trip_cnt_helper(Node* n);
737 void compute_profile_trip_cnt( PhaseIdealLoop *phase );
738
739 // Reassociate invariant expressions.
740 void reassociate_invariants(PhaseIdealLoop *phase);
741 // Reassociate invariant binary expressions.
742 Node* reassociate(Node* n1, PhaseIdealLoop *phase);
743 // Reassociate invariant add, subtract, and compare expressions.
744 Node* reassociate_add_sub_cmp(Node* n1, int inv1_idx, int inv2_idx, PhaseIdealLoop* phase);
745 // Return nonzero index of invariant operand if invariant and variant
746 // are combined with an associative binary. Helper for reassociate_invariants.
747 int find_invariant(Node* n, PhaseIdealLoop *phase);
748 // Return TRUE if "n" is associative.
749 bool is_associative(Node* n, Node* base=nullptr);
750 // Return TRUE if "n" is an associative cmp node.
751 bool is_associative_cmp(Node* n);
752
753 // Return true if n is invariant
754 bool is_invariant(Node* n) const;
755
756 // Put loop body on igvn work list
757 void record_for_igvn();
758
759 bool is_root() { return _parent == nullptr; }
760 // A proper/reducible loop w/o any (occasional) dead back-edge.
761 bool is_loop() { return !_irreducible && !tail()->is_top(); }
762 bool is_counted() { return is_loop() && _head->is_CountedLoop(); }
763 bool is_innermost() { return is_loop() && _child == nullptr; }
764
765 void remove_main_post_loops(CountedLoopNode *cl, PhaseIdealLoop *phase);
766
767 bool compute_has_range_checks() const;
768 bool range_checks_present() {
769 if (!_has_range_checks_computed) {
770 if (compute_has_range_checks()) {
771 _has_range_checks = 1;
772 }
773 _has_range_checks_computed = 1;
774 }
775 return _has_range_checks;
776 }
777
778 // Return the parent's IdealLoopTree for a strip mined loop which is the outer strip mined loop.
779 // In all other cases, return this.
780 IdealLoopTree* skip_strip_mined() {
781 return _head->as_Loop()->is_strip_mined() ? _parent : this;
782 }
783
784 #ifndef PRODUCT
785 void dump_head(); // Dump loop head only
786 void dump(); // Dump this loop recursively
787 #endif
788
789 #ifdef ASSERT
790 GrowableArray<IdealLoopTree*> collect_sorted_children() const;
791 bool verify_tree(IdealLoopTree* loop_verify) const;
792 #endif
793
794 private:
795 enum { EMPTY_LOOP_SIZE = 7 }; // Number of nodes in an empty loop.
796
797 // Estimate the number of nodes resulting from control and data flow merge.
798 uint est_loop_flow_merge_sz() const;
799
800 // Check if the number of residual iterations is large with unroll_cnt.
801 // Return true if the residual iterations are more than 10% of the trip count.
802 bool is_residual_iters_large(int unroll_cnt, CountedLoopNode *cl) const {
803 return (unroll_cnt - 1) * (100.0 / LoopPercentProfileLimit) > cl->profile_trip_cnt();
804 }
805
806 void collect_loop_core_nodes(PhaseIdealLoop* phase, Unique_Node_List& wq) const;
807
808 bool empty_loop_with_data_nodes(PhaseIdealLoop* phase) const;
809
810 void enqueue_data_nodes(PhaseIdealLoop* phase, Unique_Node_List& empty_loop_nodes, Unique_Node_List& wq) const;
811
812 bool process_safepoint(PhaseIdealLoop* phase, Unique_Node_List& empty_loop_nodes, Unique_Node_List& wq,
813 Node* sfpt) const;
814
815 bool empty_loop_candidate(PhaseIdealLoop* phase) const;
816
817 bool empty_loop_with_extra_nodes_candidate(PhaseIdealLoop* phase) const;
818 };
819
820 // -----------------------------PhaseIdealLoop---------------------------------
821 // Computes the mapping from Nodes to IdealLoopTrees. Organizes IdealLoopTrees
822 // into a loop tree. Drives the loop-based transformations on the ideal graph.
823 class PhaseIdealLoop : public PhaseTransform {
824 friend class IdealLoopTree;
825 friend class SuperWord;
826 friend class ShenandoahBarrierC2Support;
827 friend class AutoNodeBudget;
828
829 // Map loop membership for CFG nodes, and ctrl for non-CFG nodes.
830 Node_List _loop_or_ctrl;
831
832 // Pre-computed def-use info
833 PhaseIterGVN &_igvn;
834
835 // Head of loop tree
836 IdealLoopTree* _ltree_root;
837
838 // Array of pre-order numbers, plus post-visited bit.
839 // ZERO for not pre-visited. EVEN for pre-visited but not post-visited.
840 // ODD for post-visited. Other bits are the pre-order number.
841 uint *_preorders;
842 uint _max_preorder;
843
844 ReallocMark _nesting; // Safety checks for arena reallocation
845
846 const PhaseIdealLoop* _verify_me;
847 bool _verify_only;
848
849 // Allocate _preorders[] array
850 void allocate_preorders() {
851 _max_preorder = C->unique()+8;
852 _preorders = NEW_RESOURCE_ARRAY(uint, _max_preorder);
853 memset(_preorders, 0, sizeof(uint) * _max_preorder);
854 }
855
856 // Allocate _preorders[] array
857 void reallocate_preorders() {
858 _nesting.check(); // Check if a potential re-allocation in the resource arena is safe
859 if ( _max_preorder < C->unique() ) {
860 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique());
861 _max_preorder = C->unique();
862 }
863 memset(_preorders, 0, sizeof(uint) * _max_preorder);
864 }
865
866 // Check to grow _preorders[] array for the case when build_loop_tree_impl()
867 // adds new nodes.
868 void check_grow_preorders( ) {
869 _nesting.check(); // Check if a potential re-allocation in the resource arena is safe
870 if ( _max_preorder < C->unique() ) {
871 uint newsize = _max_preorder<<1; // double size of array
872 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize);
873 memset(&_preorders[_max_preorder],0,sizeof(uint)*(newsize-_max_preorder));
874 _max_preorder = newsize;
875 }
876 }
877 // Check for pre-visited. Zero for NOT visited; non-zero for visited.
878 int is_visited( Node *n ) const { return _preorders[n->_idx]; }
879 // Pre-order numbers are written to the Nodes array as low-bit-set values.
880 void set_preorder_visited( Node *n, int pre_order ) {
881 assert( !is_visited( n ), "already set" );
882 _preorders[n->_idx] = (pre_order<<1);
883 };
884 // Return pre-order number.
885 int get_preorder( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]>>1; }
886
887 // Check for being post-visited.
888 // Should be previsited already (checked with assert(is_visited(n))).
889 int is_postvisited( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]&1; }
890
891 // Mark as post visited
892 void set_postvisited( Node *n ) { assert( !is_postvisited( n ), "" ); _preorders[n->_idx] |= 1; }
893
894 public:
895 // Set/get control node out. Set lower bit to distinguish from IdealLoopTree
896 // Returns true if "n" is a data node, false if it's a control node.
897 bool has_ctrl(const Node* n) const { return ((intptr_t)_loop_or_ctrl[n->_idx]) & 1; }
898
899 private:
900 // clear out dead code after build_loop_late
901 Node_List _deadlist;
902 Node_List _zero_trip_guard_opaque_nodes;
903
904 // Support for faster execution of get_late_ctrl()/dom_lca()
905 // when a node has many uses and dominator depth is deep.
906 GrowableArray<jlong> _dom_lca_tags;
907 uint _dom_lca_tags_round;
908 void init_dom_lca_tags();
909
910 // Helper for debugging bad dominance relationships
911 bool verify_dominance(Node* n, Node* use, Node* LCA, Node* early);
912
913 Node* compute_lca_of_uses(Node* n, Node* early, bool verify = false);
914
915 // Inline wrapper for frequent cases:
916 // 1) only one use
917 // 2) a use is the same as the current LCA passed as 'n1'
918 Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) {
919 assert( n->is_CFG(), "" );
920 // Fast-path null lca
921 if( lca != nullptr && lca != n ) {
922 assert( lca->is_CFG(), "" );
923 // find LCA of all uses
924 n = dom_lca_for_get_late_ctrl_internal( lca, n, tag );
925 }
926 return find_non_split_ctrl(n);
927 }
928 Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag );
929
930 // Helper function for directing control inputs away from CFG split points.
931 Node *find_non_split_ctrl( Node *ctrl ) const {
932 if (ctrl != nullptr) {
933 if (ctrl->is_MultiBranch()) {
934 ctrl = ctrl->in(0);
935 }
936 assert(ctrl->is_CFG(), "CFG");
937 }
938 return ctrl;
939 }
940
941 #ifdef ASSERT
942 static void ensure_zero_trip_guard_proj(Node* node, bool is_main_loop);
943 #endif
944 public:
945 IfTrueNode* create_initialized_assertion_predicate(IfNode* template_assertion_predicate, Node* new_init,
946 Node* new_stride, Node* control);
947 DEBUG_ONLY(static bool assertion_predicate_has_loop_opaque_node(IfNode* iff);)
948 private:
949 DEBUG_ONLY(static void count_opaque_loop_nodes(Node* n, uint& init, uint& stride);)
950 static void get_assertion_predicates(Node* predicate, Unique_Node_List& list, bool get_opaque = false);
951 void update_main_loop_assertion_predicates(Node* ctrl, CountedLoopNode* loop_head, Node* init, int stride_con);
952 void initialize_assertion_predicates_for_peeled_loop(CountedLoopNode* peeled_loop_head,
953 CountedLoopNode* remaining_loop_head,
954 uint first_node_index_in_cloned_loop_body,
955 const Node_List& old_new);
956 void initialize_assertion_predicates_for_main_loop(CountedLoopNode* pre_loop_head,
957 CountedLoopNode* main_loop_head,
958 uint first_node_index_in_cloned_loop_body,
959 const Node_List& old_new);
960 void initialize_assertion_predicates_for_post_loop(CountedLoopNode* main_loop_head, CountedLoopNode* post_loop_head,
961 uint first_node_index_in_cloned_loop_body);
962 void create_assertion_predicates_at_loop(CountedLoopNode* source_loop_head, CountedLoopNode* target_loop_head,
963 const NodeInLoopBody& _node_in_loop_body, bool clone_template);
964 void insert_loop_limit_check_predicate(ParsePredicateSuccessProj* loop_limit_check_parse_proj, Node* cmp_limit,
965 Node* bol);
966 void log_loop_tree();
967
968 public:
969
970 PhaseIterGVN &igvn() const { return _igvn; }
971
972 bool has_node(const Node* n) const {
973 guarantee(n != nullptr, "No Node.");
974 return _loop_or_ctrl[n->_idx] != nullptr;
975 }
976 // check if transform created new nodes that need _ctrl recorded
977 Node *get_late_ctrl( Node *n, Node *early );
978 Node *get_early_ctrl( Node *n );
979 Node *get_early_ctrl_for_expensive(Node *n, Node* earliest);
980 void set_early_ctrl(Node* n, bool update_body);
981 void set_subtree_ctrl(Node* n, bool update_body);
982 void set_ctrl( Node *n, Node *ctrl ) {
983 assert( !has_node(n) || has_ctrl(n), "" );
984 assert( ctrl->in(0), "cannot set dead control node" );
985 assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" );
986 _loop_or_ctrl.map(n->_idx, (Node*)((intptr_t)ctrl + 1));
987 }
988 // Set control and update loop membership
989 void set_ctrl_and_loop(Node* n, Node* ctrl) {
990 IdealLoopTree* old_loop = get_loop(get_ctrl(n));
991 IdealLoopTree* new_loop = get_loop(ctrl);
992 if (old_loop != new_loop) {
993 if (old_loop->_child == nullptr) old_loop->_body.yank(n);
994 if (new_loop->_child == nullptr) new_loop->_body.push(n);
995 }
996 set_ctrl(n, ctrl);
997 }
998 // Control nodes can be replaced or subsumed. During this pass they
999 // get their replacement Node in slot 1. Instead of updating the block
1000 // location of all Nodes in the subsumed block, we lazily do it. As we
1001 // pull such a subsumed block out of the array, we write back the final
1002 // correct block.
1003 Node* get_ctrl(const Node* i) {
1004 assert(has_node(i), "");
1005 Node *n = get_ctrl_no_update(i);
1006 _loop_or_ctrl.map(i->_idx, (Node*)((intptr_t)n + 1));
1007 assert(has_node(i) && has_ctrl(i), "");
1008 assert(n == find_non_split_ctrl(n), "must return legal ctrl" );
1009 return n;
1010 }
1011
1012 bool is_dominator(Node* dominator, Node* n);
1013 bool is_strict_dominator(Node* dominator, Node* n);
1014
1015 // return get_ctrl for a data node and self(n) for a CFG node
1016 Node* ctrl_or_self(Node* n) {
1017 if (has_ctrl(n))
1018 return get_ctrl(n);
1019 else {
1020 assert (n->is_CFG(), "must be a CFG node");
1021 return n;
1022 }
1023 }
1024
1025 Node* get_ctrl_no_update_helper(const Node* i) const {
1026 assert(has_ctrl(i), "should be control, not loop");
1027 return (Node*)(((intptr_t)_loop_or_ctrl[i->_idx]) & ~1);
1028 }
1029
1030 Node* get_ctrl_no_update(const Node* i) const {
1031 assert( has_ctrl(i), "" );
1032 Node *n = get_ctrl_no_update_helper(i);
1033 if (!n->in(0)) {
1034 // Skip dead CFG nodes
1035 do {
1036 n = get_ctrl_no_update_helper(n);
1037 } while (!n->in(0));
1038 n = find_non_split_ctrl(n);
1039 }
1040 return n;
1041 }
1042
1043 // Check for loop being set
1044 // "n" must be a control node. Returns true if "n" is known to be in a loop.
1045 bool has_loop( Node *n ) const {
1046 assert(!has_node(n) || !has_ctrl(n), "");
1047 return has_node(n);
1048 }
1049 // Set loop
1050 void set_loop( Node *n, IdealLoopTree *loop ) {
1051 _loop_or_ctrl.map(n->_idx, (Node*)loop);
1052 }
1053 // Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms. Replace
1054 // the 'old_node' with 'new_node'. Kill old-node. Add a reference
1055 // from old_node to new_node to support the lazy update. Reference
1056 // replaces loop reference, since that is not needed for dead node.
1057 void lazy_update(Node *old_node, Node *new_node) {
1058 assert(old_node != new_node, "no cycles please");
1059 // Re-use the side array slot for this node to provide the
1060 // forwarding pointer.
1061 _loop_or_ctrl.map(old_node->_idx, (Node*)((intptr_t)new_node + 1));
1062 }
1063 void lazy_replace(Node *old_node, Node *new_node) {
1064 _igvn.replace_node(old_node, new_node);
1065 lazy_update(old_node, new_node);
1066 }
1067
1068 private:
1069
1070 // Place 'n' in some loop nest, where 'n' is a CFG node
1071 void build_loop_tree();
1072 int build_loop_tree_impl(Node* n, int pre_order);
1073 // Insert loop into the existing loop tree. 'innermost' is a leaf of the
1074 // loop tree, not the root.
1075 IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost );
1076
1077 #ifdef ASSERT
1078 // verify that regions in irreducible loops are marked is_in_irreducible_loop
1079 void verify_regions_in_irreducible_loops();
1080 bool is_in_irreducible_loop(RegionNode* region);
1081 #endif
1082
1083 // Place Data nodes in some loop nest
1084 void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
1085 void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
1086 void build_loop_late_post_work(Node* n, bool pinned);
1087 void build_loop_late_post(Node* n);
1088 void verify_strip_mined_scheduling(Node *n, Node* least);
1089
1090 // Array of immediate dominance info for each CFG node indexed by node idx
1091 private:
1092 uint _idom_size;
1093 Node **_idom; // Array of immediate dominators
1094 uint *_dom_depth; // Used for fast LCA test
1095 GrowableArray<uint>* _dom_stk; // For recomputation of dom depth
1096 LoopOptsMode _mode;
1097
1098 // build the loop tree and perform any requested optimizations
1099 void build_and_optimize();
1100
1101 // Dominators for the sea of nodes
1102 void Dominators();
1103
1104 // Compute the Ideal Node to Loop mapping
1105 PhaseIdealLoop(PhaseIterGVN& igvn, LoopOptsMode mode) :
1106 PhaseTransform(Ideal_Loop),
1107 _loop_or_ctrl(igvn.C->comp_arena()),
1108 _igvn(igvn),
1109 _verify_me(nullptr),
1110 _verify_only(false),
1111 _mode(mode),
1112 _nodes_required(UINT_MAX) {
1113 assert(mode != LoopOptsVerify, "wrong constructor to verify IdealLoop");
1114 build_and_optimize();
1115 }
1116
1117 #ifndef PRODUCT
1118 // Verify that verify_me made the same decisions as a fresh run
1119 // or only verify that the graph is valid if verify_me is null.
1120 PhaseIdealLoop(PhaseIterGVN& igvn, const PhaseIdealLoop* verify_me = nullptr) :
1121 PhaseTransform(Ideal_Loop),
1122 _loop_or_ctrl(igvn.C->comp_arena()),
1123 _igvn(igvn),
1124 _verify_me(verify_me),
1125 _verify_only(verify_me == nullptr),
1126 _mode(LoopOptsVerify),
1127 _nodes_required(UINT_MAX) {
1128 DEBUG_ONLY(C->set_phase_verify_ideal_loop();)
1129 build_and_optimize();
1130 DEBUG_ONLY(C->reset_phase_verify_ideal_loop();)
1131 }
1132 #endif
1133
1134 Node* insert_convert_node_if_needed(BasicType target, Node* input);
1135
1136 public:
1137 Node* idom_no_update(Node* d) const {
1138 return idom_no_update(d->_idx);
1139 }
1140
1141 Node* idom_no_update(uint didx) const {
1142 assert(didx < _idom_size, "oob");
1143 Node* n = _idom[didx];
1144 assert(n != nullptr,"Bad immediate dominator info.");
1145 while (n->in(0) == nullptr) { // Skip dead CFG nodes
1146 n = (Node*)(((intptr_t)_loop_or_ctrl[n->_idx]) & ~1);
1147 assert(n != nullptr,"Bad immediate dominator info.");
1148 }
1149 return n;
1150 }
1151
1152 Node *idom(Node* d) const {
1153 return idom(d->_idx);
1154 }
1155
1156 Node *idom(uint didx) const {
1157 Node *n = idom_no_update(didx);
1158 _idom[didx] = n; // Lazily remove dead CFG nodes from table.
1159 return n;
1160 }
1161
1162 uint dom_depth(Node* d) const {
1163 guarantee(d != nullptr, "Null dominator info.");
1164 guarantee(d->_idx < _idom_size, "");
1165 return _dom_depth[d->_idx];
1166 }
1167 void set_idom(Node* d, Node* n, uint dom_depth);
1168 // Locally compute IDOM using dom_lca call
1169 Node *compute_idom( Node *region ) const;
1170 // Recompute dom_depth
1171 void recompute_dom_depth();
1172
1173 // Is safept not required by an outer loop?
1174 bool is_deleteable_safept(Node* sfpt);
1175
1176 // Replace parallel induction variable (parallel to trip counter)
1177 void replace_parallel_iv(IdealLoopTree *loop);
1178
1179 Node *dom_lca( Node *n1, Node *n2 ) const {
1180 return find_non_split_ctrl(dom_lca_internal(n1, n2));
1181 }
1182 Node *dom_lca_internal( Node *n1, Node *n2 ) const;
1183
1184 Node* dominated_node(Node* c1, Node* c2) {
1185 assert(is_dominator(c1, c2) || is_dominator(c2, c1), "nodes must be related");
1186 return is_dominator(c1, c2) ? c2 : c1;
1187 }
1188
1189 // Return control node that's dominated by the 2 others
1190 Node* dominated_node(Node* c1, Node* c2, Node* c3) {
1191 return dominated_node(c1, dominated_node(c2, c3));
1192 }
1193
1194 // Build and verify the loop tree without modifying the graph. This
1195 // is useful to verify that all inputs properly dominate their uses.
1196 static void verify(PhaseIterGVN& igvn) {
1197 #ifdef ASSERT
1198 ResourceMark rm;
1199 Compile::TracePhase tp("idealLoopVerify", &timers[_t_idealLoopVerify]);
1200 PhaseIdealLoop v(igvn);
1201 #endif
1202 }
1203
1204 // Recommended way to use PhaseIdealLoop.
1205 // Run PhaseIdealLoop in some mode and allocates a local scope for memory allocations.
1206 static void optimize(PhaseIterGVN &igvn, LoopOptsMode mode) {
1207 ResourceMark rm;
1208 PhaseIdealLoop v(igvn, mode);
1209
1210 Compile* C = Compile::current();
1211 if (!C->failing()) {
1212 // Cleanup any modified bits
1213 igvn.optimize();
1214 if (C->failing()) { return; }
1215 v.log_loop_tree();
1216 }
1217 }
1218
1219 // True if the method has at least 1 irreducible loop
1220 bool _has_irreducible_loops;
1221
1222 // Per-Node transform
1223 virtual Node* transform(Node* n) { return nullptr; }
1224
1225 Node* loop_exit_control(Node* x, IdealLoopTree* loop);
1226 Node* loop_exit_test(Node* back_control, IdealLoopTree* loop, Node*& incr, Node*& limit, BoolTest::mask& bt, float& cl_prob);
1227 Node* loop_iv_incr(Node* incr, Node* x, IdealLoopTree* loop, Node*& phi_incr);
1228 Node* loop_iv_stride(Node* incr, IdealLoopTree* loop, Node*& xphi);
1229 PhiNode* loop_iv_phi(Node* xphi, Node* phi_incr, Node* x, IdealLoopTree* loop);
1230
1231 bool is_counted_loop(Node* x, IdealLoopTree*&loop, BasicType iv_bt);
1232
1233 Node* loop_nest_replace_iv(Node* iv_to_replace, Node* inner_iv, Node* outer_phi, Node* inner_head, BasicType bt);
1234 bool create_loop_nest(IdealLoopTree* loop, Node_List &old_new);
1235 #ifdef ASSERT
1236 bool convert_to_long_loop(Node* cmp, Node* phi, IdealLoopTree* loop);
1237 #endif
1238 void add_parse_predicate(Deoptimization::DeoptReason reason, Node* inner_head, IdealLoopTree* loop, SafePointNode* sfpt);
1239 SafePointNode* find_safepoint(Node* back_control, Node* x, IdealLoopTree* loop);
1240 IdealLoopTree* insert_outer_loop(IdealLoopTree* loop, LoopNode* outer_l, Node* outer_ift);
1241 IdealLoopTree* create_outer_strip_mined_loop(BoolNode *test, Node *cmp, Node *init_control,
1242 IdealLoopTree* loop, float cl_prob, float le_fcnt,
1243 Node*& entry_control, Node*& iffalse);
1244
1245 Node* exact_limit( IdealLoopTree *loop );
1246
1247 // Return a post-walked LoopNode
1248 IdealLoopTree *get_loop( Node *n ) const {
1249 // Dead nodes have no loop, so return the top level loop instead
1250 if (!has_node(n)) return _ltree_root;
1251 assert(!has_ctrl(n), "");
1252 return (IdealLoopTree*)_loop_or_ctrl[n->_idx];
1253 }
1254
1255 IdealLoopTree* ltree_root() const { return _ltree_root; }
1256
1257 // Is 'n' a (nested) member of 'loop'?
1258 int is_member( const IdealLoopTree *loop, Node *n ) const {
1259 return loop->is_member(get_loop(n)); }
1260
1261 // This is the basic building block of the loop optimizations. It clones an
1262 // entire loop body. It makes an old_new loop body mapping; with this
1263 // mapping you can find the new-loop equivalent to an old-loop node. All
1264 // new-loop nodes are exactly equal to their old-loop counterparts, all
1265 // edges are the same. All exits from the old-loop now have a RegionNode
1266 // that merges the equivalent new-loop path. This is true even for the
1267 // normal "loop-exit" condition. All uses of loop-invariant old-loop values
1268 // now come from (one or more) Phis that merge their new-loop equivalents.
1269 // Parameter side_by_side_idom:
1270 // When side_by_size_idom is null, the dominator tree is constructed for
1271 // the clone loop to dominate the original. Used in construction of
1272 // pre-main-post loop sequence.
1273 // When nonnull, the clone and original are side-by-side, both are
1274 // dominated by the passed in side_by_side_idom node. Used in
1275 // construction of unswitched loops.
1276 enum CloneLoopMode {
1277 IgnoreStripMined = 0, // Only clone inner strip mined loop
1278 CloneIncludesStripMined = 1, // clone both inner and outer strip mined loops
1279 ControlAroundStripMined = 2 // Only clone inner strip mined loop,
1280 // result control flow branches
1281 // either to inner clone or outer
1282 // strip mined loop.
1283 };
1284 void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth,
1285 CloneLoopMode mode, Node* side_by_side_idom = nullptr);
1286 void clone_loop_handle_data_uses(Node* old, Node_List &old_new,
1287 IdealLoopTree* loop, IdealLoopTree* companion_loop,
1288 Node_List*& split_if_set, Node_List*& split_bool_set,
1289 Node_List*& split_cex_set, Node_List& worklist,
1290 uint new_counter, CloneLoopMode mode);
1291 void clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
1292 IdealLoopTree* outer_loop, int dd, Node_List &old_new,
1293 Node_List& extra_data_nodes);
1294
1295 // If we got the effect of peeling, either by actually peeling or by
1296 // making a pre-loop which must execute at least once, we can remove
1297 // all loop-invariant dominated tests in the main body.
1298 void peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new );
1299
1300 // Generate code to do a loop peel for the given loop (and body).
1301 // old_new is a temp array.
1302 void do_peeling( IdealLoopTree *loop, Node_List &old_new );
1303
1304 // Add pre and post loops around the given loop. These loops are used
1305 // during RCE, unrolling and aligning loops.
1306 void insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only );
1307
1308 // Add post loop after the given loop.
1309 Node *insert_post_loop(IdealLoopTree* loop, Node_List& old_new,
1310 CountedLoopNode* main_head, CountedLoopEndNode* main_end,
1311 Node*& incr, Node* limit, CountedLoopNode*& post_head);
1312
1313 // Add a vector post loop between a vector main loop and the current post loop
1314 void insert_vector_post_loop(IdealLoopTree *loop, Node_List &old_new);
1315 // If Node n lives in the back_ctrl block, we clone a private version of n
1316 // in preheader_ctrl block and return that, otherwise return n.
1317 Node *clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones );
1318
1319 // Take steps to maximally unroll the loop. Peel any odd iterations, then
1320 // unroll to do double iterations. The next round of major loop transforms
1321 // will repeat till the doubled loop body does all remaining iterations in 1
1322 // pass.
1323 void do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new );
1324
1325 // Unroll the loop body one step - make each trip do 2 iterations.
1326 void do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip );
1327
1328 // Return true if exp is a constant times an induction var
1329 bool is_scaled_iv(Node* exp, Node* iv, BasicType bt, jlong* p_scale, bool* p_short_scale, int depth = 0);
1330
1331 bool is_iv(Node* exp, Node* iv, BasicType bt);
1332
1333 // Return true if exp is a scaled induction var plus (or minus) constant
1334 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);
1335 bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset) {
1336 jlong long_scale;
1337 if (is_scaled_iv_plus_offset(exp, iv, T_INT, &long_scale, p_offset)) {
1338 int int_scale = checked_cast<int>(long_scale);
1339 if (p_scale != nullptr) {
1340 *p_scale = int_scale;
1341 }
1342 return true;
1343 }
1344 return false;
1345 }
1346 // Helper for finding more complex matches to is_scaled_iv_plus_offset.
1347 bool is_scaled_iv_plus_extra_offset(Node* exp1, Node* offset2, Node* iv,
1348 BasicType bt,
1349 jlong* p_scale, Node** p_offset,
1350 bool* p_short_scale, int depth);
1351
1352 // Create a new if above the uncommon_trap_if_pattern for the predicate to be promoted
1353 IfTrueNode* create_new_if_for_predicate(
1354 ParsePredicateSuccessProj* parse_predicate_proj, Node* new_entry, Deoptimization::DeoptReason reason, int opcode,
1355 bool rewire_uncommon_proj_phi_inputs = false
1356 NOT_PRODUCT (COMMA AssertionPredicateType assertion_predicate_type = AssertionPredicateType::None));
1357
1358 private:
1359 // Helper functions for create_new_if_for_predicate()
1360 void set_ctrl_of_nodes_with_same_ctrl(Node* start_node, ProjNode* old_uncommon_proj, Node* new_uncommon_proj);
1361 Unique_Node_List find_nodes_with_same_ctrl(Node* node, const ProjNode* ctrl);
1362 Node* clone_nodes_with_same_ctrl(Node* start_node, ProjNode* old_uncommon_proj, Node* new_uncommon_proj);
1363 void fix_cloned_data_node_controls(const ProjNode* orig, Node* new_uncommon_proj,
1364 const OrigToNewHashtable& orig_to_clone);
1365 bool has_dominating_loop_limit_check(Node* init_trip, Node* limit, jlong stride_con, BasicType iv_bt,
1366 Node* loop_entry);
1367
1368 public:
1369 void register_control(Node* n, IdealLoopTree *loop, Node* pred, bool update_body = true);
1370
1371 void replace_loop_entry(LoopNode* loop_head, Node* new_entry) {
1372 _igvn.replace_input_of(loop_head, LoopNode::EntryControl, new_entry);
1373 set_idom(loop_head, new_entry, dom_depth(new_entry));
1374 }
1375
1376 // Construct a range check for a predicate if
1377 BoolNode* rc_predicate(Node* ctrl, int scale, Node* offset, Node* init, Node* limit,
1378 jint stride, Node* range, bool upper, bool& overflow);
1379
1380 // Implementation of the loop predication to promote checks outside the loop
1381 bool loop_predication_impl(IdealLoopTree *loop);
1382
1383 private:
1384 bool loop_predication_impl_helper(IdealLoopTree* loop, IfProjNode* if_success_proj,
1385 ParsePredicateSuccessProj* parse_predicate_proj, CountedLoopNode* cl, ConNode* zero,
1386 Invariance& invar, Deoptimization::DeoptReason deopt_reason);
1387 bool can_create_loop_predicates(const PredicateBlock* profiled_loop_predicate_block) const;
1388 bool loop_predication_should_follow_branches(IdealLoopTree* loop, float& loop_trip_cnt);
1389 void loop_predication_follow_branches(Node *c, IdealLoopTree *loop, float loop_trip_cnt,
1390 PathFrequency& pf, Node_Stack& stack, VectorSet& seen,
1391 Node_List& if_proj_list);
1392 IfTrueNode* create_template_assertion_predicate(int if_opcode, CountedLoopNode* loop_head,
1393 ParsePredicateSuccessProj* parse_predicate_proj,
1394 IfProjNode* new_control, int scale, Node* offset,
1395 Node* range, Deoptimization::DeoptReason deopt_reason);
1396 void eliminate_hoisted_range_check(IfTrueNode* hoisted_check_proj, IfTrueNode* template_assertion_predicate_proj);
1397
1398 // Helper function to collect predicate for eliminating the useless ones
1399 void eliminate_useless_predicates();
1400
1401 void eliminate_useless_parse_predicates();
1402 void mark_all_parse_predicates_useless() const;
1403 void mark_loop_associated_parse_predicates_useful();
1404 static void mark_useful_parse_predicates_for_loop(IdealLoopTree* loop);
1405 void add_useless_parse_predicates_to_igvn_worklist();
1406
1407 void eliminate_useless_template_assertion_predicates();
1408 void collect_useful_template_assertion_predicates(Unique_Node_List& useful_predicates);
1409 static void collect_useful_template_assertion_predicates_for_loop(IdealLoopTree* loop, Unique_Node_List& useful_predicates);
1410 void eliminate_useless_template_assertion_predicates(Unique_Node_List& useful_predicates);
1411
1412 void eliminate_useless_zero_trip_guard();
1413
1414 public:
1415 // Change the control input of expensive nodes to allow commoning by
1416 // IGVN when it is guaranteed to not result in a more frequent
1417 // execution of the expensive node. Return true if progress.
1418 bool process_expensive_nodes();
1419
1420 // Check whether node has become unreachable
1421 bool is_node_unreachable(Node *n) const {
1422 return !has_node(n) || n->is_unreachable(_igvn);
1423 }
1424
1425 // Eliminate range-checks and other trip-counter vs loop-invariant tests.
1426 void do_range_check(IdealLoopTree *loop, Node_List &old_new);
1427
1428 // Clone loop with an invariant test (that does not exit) and
1429 // insert a clone of the test that selects which version to
1430 // execute.
1431 void do_unswitching(IdealLoopTree* loop, Node_List& old_new);
1432
1433 IfNode* find_unswitch_candidate(const IdealLoopTree* loop) const;
1434
1435 private:
1436 static bool has_control_dependencies_from_predicates(LoopNode* head);
1437 static void revert_to_normal_loop(const LoopNode* loop_head);
1438
1439 void hoist_invariant_check_casts(const IdealLoopTree* loop, const Node_List& old_new,
1440 const UnswitchedLoopSelector& unswitched_loop_selector);
1441 void add_unswitched_loop_version_bodies_to_igvn(IdealLoopTree* loop, const Node_List& old_new);
1442 static void increment_unswitch_counts(LoopNode* original_head, LoopNode* new_head);
1443 void remove_unswitch_candidate_from_loops(const Node_List& old_new, const UnswitchedLoopSelector& unswitched_loop_selector);
1444 #ifndef PRODUCT
1445 static void trace_loop_unswitching_count(IdealLoopTree* loop, LoopNode* original_head);
1446 static void trace_loop_unswitching_impossible(const LoopNode* original_head);
1447 static void trace_loop_unswitching_result(const UnswitchedLoopSelector& unswitched_loop_selector,
1448 const LoopNode* original_head, const LoopNode* new_head);
1449 #endif
1450
1451 public:
1452
1453 // Range Check Elimination uses this function!
1454 // Constrain the main loop iterations so the affine function:
1455 // low_limit <= scale_con * I + offset < upper_limit
1456 // always holds true. That is, either increase the number of iterations in
1457 // the pre-loop or the post-loop until the condition holds true in the main
1458 // loop. Scale_con, offset and limit are all loop invariant.
1459 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);
1460 // Helper function for add_constraint().
1461 Node* adjust_limit(bool reduce, Node* scale, Node* offset, Node* rc_limit, Node* old_limit, Node* pre_ctrl, bool round);
1462
1463 // Partially peel loop up through last_peel node.
1464 bool partial_peel( IdealLoopTree *loop, Node_List &old_new );
1465 bool duplicate_loop_backedge(IdealLoopTree *loop, Node_List &old_new);
1466
1467 // AutoVectorize the loop: replace scalar ops with vector ops.
1468 enum AutoVectorizeStatus {
1469 Impossible, // This loop has the wrong shape to even try vectorization.
1470 Success, // We just successfully vectorized the loop.
1471 TriedAndFailed, // We tried to vectorize, but failed.
1472 };
1473 AutoVectorizeStatus auto_vectorize(IdealLoopTree* lpt, VSharedData &vshared);
1474
1475 // Move an unordered Reduction out of loop if possible
1476 void move_unordered_reduction_out_of_loop(IdealLoopTree* loop);
1477
1478 // Create a scheduled list of nodes control dependent on ctrl set.
1479 void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched );
1480 // Has a use in the vector set
1481 bool has_use_in_set( Node* n, VectorSet& vset );
1482 // Has use internal to the vector set (ie. not in a phi at the loop head)
1483 bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop );
1484 // clone "n" for uses that are outside of loop
1485 int clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist );
1486 // clone "n" for special uses that are in the not_peeled region
1487 void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
1488 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist );
1489 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
1490 void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp );
1491 #ifdef ASSERT
1492 // Validate the loop partition sets: peel and not_peel
1493 bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel );
1494 // Ensure that uses outside of loop are of the right form
1495 bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
1496 uint orig_exit_idx, uint clone_exit_idx);
1497 bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx);
1498 #endif
1499
1500 // Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.)
1501 int stride_of_possible_iv( Node* iff );
1502 bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; }
1503 // Return the (unique) control output node that's in the loop (if it exists.)
1504 Node* stay_in_loop( Node* n, IdealLoopTree *loop);
1505 // Insert a signed compare loop exit cloned from an unsigned compare.
1506 IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop);
1507 void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop);
1508 // Utility to register node "n" with PhaseIdealLoop
1509 void register_node(Node* n, IdealLoopTree* loop, Node* pred, uint ddepth);
1510 // Utility to create an if-projection
1511 ProjNode* proj_clone(ProjNode* p, IfNode* iff);
1512 // Force the iff control output to be the live_proj
1513 Node* short_circuit_if(IfNode* iff, ProjNode* live_proj);
1514 // Insert a region before an if projection
1515 RegionNode* insert_region_before_proj(ProjNode* proj);
1516 // Insert a new if before an if projection
1517 ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj);
1518
1519 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1520 // "Nearly" because all Nodes have been cloned from the original in the loop,
1521 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1522 // through the Phi recursively, and return a Bool.
1523 Node* clone_iff(PhiNode* phi);
1524 CmpNode* clone_bool(PhiNode* phi);
1525
1526
1527 // Rework addressing expressions to get the most loop-invariant stuff
1528 // moved out. We'd like to do all associative operators, but it's especially
1529 // important (common) to do address expressions.
1530 Node* remix_address_expressions(Node* n);
1531 Node* remix_address_expressions_add_left_shift(Node* n, IdealLoopTree* n_loop, Node* n_ctrl, BasicType bt);
1532
1533 // Convert add to muladd to generate MuladdS2I under certain criteria
1534 Node * convert_add_to_muladd(Node * n);
1535
1536 // Attempt to use a conditional move instead of a phi/branch
1537 Node *conditional_move( Node *n );
1538
1539 bool split_thru_phi_could_prevent_vectorization(Node* n, Node* n_blk);
1540
1541 // Check for aggressive application of 'split-if' optimization,
1542 // using basic block level info.
1543 void split_if_with_blocks ( VectorSet &visited, Node_Stack &nstack);
1544 Node *split_if_with_blocks_pre ( Node *n );
1545 void split_if_with_blocks_post( Node *n );
1546 Node *has_local_phi_input( Node *n );
1547 // Mark an IfNode as being dominated by a prior test,
1548 // without actually altering the CFG (and hence IDOM info).
1549 void dominated_by(IfProjNode* prevdom, IfNode* iff, bool flip = false, bool pin_array_access_nodes = false);
1550 void rewire_safe_outputs_to_dominator(Node* source, Node* dominator, bool pin_array_access_nodes);
1551
1552 // Split Node 'n' through merge point
1553 RegionNode* split_thru_region(Node* n, RegionNode* region);
1554 // Split Node 'n' through merge point if there is enough win.
1555 Node *split_thru_phi( Node *n, Node *region, int policy );
1556 // Found an If getting its condition-code input from a Phi in the
1557 // same block. Split thru the Region.
1558 void do_split_if(Node *iff, RegionNode** new_false_region = nullptr, RegionNode** new_true_region = nullptr);
1559
1560 // Conversion of fill/copy patterns into intrinsic versions
1561 bool do_intrinsify_fill();
1562 bool intrinsify_fill(IdealLoopTree* lpt);
1563 bool match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value,
1564 Node*& shift, Node*& offset);
1565
1566 private:
1567 // Return a type based on condition control flow
1568 const TypeInt* filtered_type( Node *n, Node* n_ctrl);
1569 const TypeInt* filtered_type( Node *n ) { return filtered_type(n, nullptr); }
1570 // Helpers for filtered type
1571 const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl);
1572
1573 // Helper functions
1574 Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache );
1575 Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true );
1576 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 );
1577 bool split_up( Node *n, Node *blk1, Node *blk2 );
1578
1579 Node* place_outside_loop(Node* useblock, IdealLoopTree* loop) const;
1580 Node* try_move_store_before_loop(Node* n, Node *n_ctrl);
1581 void try_move_store_after_loop(Node* n);
1582 bool identical_backtoback_ifs(Node *n);
1583 bool can_split_if(Node *n_ctrl);
1584 bool cannot_split_division(const Node* n, const Node* region) const;
1585 static bool is_divisor_loop_phi(const Node* divisor, const Node* loop);
1586 bool loop_phi_backedge_type_contains_zero(const Node* phi_divisor, const Type* zero) const;
1587
1588 // Determine if a method is too big for a/another round of split-if, based on
1589 // a magic (approximate) ratio derived from the equally magic constant 35000,
1590 // previously used for this purpose (but without relating to the node limit).
1591 bool must_throttle_split_if() {
1592 uint threshold = C->max_node_limit() * 2 / 5;
1593 return C->live_nodes() > threshold;
1594 }
1595
1596 // A simplistic node request tracking mechanism, where
1597 // = UINT_MAX Request not valid or made final.
1598 // < UINT_MAX Nodes currently requested (estimate).
1599 uint _nodes_required;
1600
1601 enum { REQUIRE_MIN = 70 };
1602
1603 uint nodes_required() const { return _nodes_required; }
1604
1605 // Given the _currently_ available number of nodes, check whether there is
1606 // "room" for an additional request or not, considering the already required
1607 // number of nodes. Return TRUE if the new request is exceeding the node
1608 // budget limit, otherwise return FALSE. Note that this interpretation will
1609 // act pessimistic on additional requests when new nodes have already been
1610 // generated since the 'begin'. This behaviour fits with the intention that
1611 // node estimates/requests should be made upfront.
1612 bool exceeding_node_budget(uint required = 0) {
1613 assert(C->live_nodes() < C->max_node_limit(), "sanity");
1614 uint available = C->max_node_limit() - C->live_nodes();
1615 return available < required + _nodes_required + REQUIRE_MIN;
1616 }
1617
1618 uint require_nodes(uint require, uint minreq = REQUIRE_MIN) {
1619 precond(require > 0);
1620 _nodes_required += MAX2(require, minreq);
1621 return _nodes_required;
1622 }
1623
1624 bool may_require_nodes(uint require, uint minreq = REQUIRE_MIN) {
1625 return !exceeding_node_budget(require) && require_nodes(require, minreq) > 0;
1626 }
1627
1628 uint require_nodes_begin() {
1629 assert(_nodes_required == UINT_MAX, "Bad state (begin).");
1630 _nodes_required = 0;
1631 return C->live_nodes();
1632 }
1633
1634 // When a node request is final, optionally check that the requested number
1635 // of nodes was reasonably correct with respect to the number of new nodes
1636 // introduced since the last 'begin'. Always check that we have not exceeded
1637 // the maximum node limit.
1638 void require_nodes_final(uint live_at_begin, bool check_estimate) {
1639 assert(_nodes_required < UINT_MAX, "Bad state (final).");
1640
1641 #ifdef ASSERT
1642 if (check_estimate) {
1643 // Check that the node budget request was not off by too much (x2).
1644 // Should this be the case we _surely_ need to improve the estimates
1645 // used in our budget calculations.
1646 if (C->live_nodes() - live_at_begin > 2 * _nodes_required) {
1647 log_info(compilation)("Bad node estimate: actual = %d >> request = %d",
1648 C->live_nodes() - live_at_begin, _nodes_required);
1649 }
1650 }
1651 #endif
1652 // Assert that we have stayed within the node budget limit.
1653 assert(C->live_nodes() < C->max_node_limit(),
1654 "Exceeding node budget limit: %d + %d > %d (request = %d)",
1655 C->live_nodes() - live_at_begin, live_at_begin,
1656 C->max_node_limit(), _nodes_required);
1657
1658 _nodes_required = UINT_MAX;
1659 }
1660
1661 public:
1662 // Clone Parse Predicates to slow and fast loop when unswitching a loop
1663 void clone_parse_and_assertion_predicates_to_unswitched_loop(IdealLoopTree* loop, Node_List& old_new,
1664 IfProjNode*& iffast_pred, IfProjNode*& ifslow_pred);
1665 private:
1666 void clone_loop_predication_predicates_to_unswitched_loop(IdealLoopTree* loop, const Node_List& old_new,
1667 const PredicateBlock* predicate_block,
1668 Deoptimization::DeoptReason reason, IfProjNode*& iffast_pred,
1669 IfProjNode*& ifslow_pred);
1670 void clone_parse_predicate_to_unswitched_loops(const PredicateBlock* predicate_block, Deoptimization::DeoptReason reason,
1671 IfProjNode*& iffast_pred, IfProjNode*& ifslow_pred);
1672 IfProjNode* clone_parse_predicate_to_unswitched_loop(ParsePredicateSuccessProj* parse_predicate_proj, Node* new_entry,
1673 Deoptimization::DeoptReason reason, bool slow_loop);
1674 void clone_assertion_predicates_to_unswitched_loop(IdealLoopTree* loop, const Node_List& old_new,
1675 Deoptimization::DeoptReason reason, IfProjNode* old_predicate_proj,
1676 ParsePredicateSuccessProj* fast_loop_parse_predicate_proj,
1677 ParsePredicateSuccessProj* slow_loop_parse_predicate_proj);
1678 IfProjNode* clone_assertion_predicate_for_unswitched_loops(IfNode* template_assertion_predicate, IfProjNode* predicate,
1679 Deoptimization::DeoptReason reason,
1680 ParsePredicateSuccessProj* parse_predicate_proj);
1681 static void check_cloned_parse_predicate_for_unswitching(const Node* new_entry, bool is_fast_loop) PRODUCT_RETURN;
1682
1683 bool _created_loop_node;
1684 DEBUG_ONLY(void dump_idoms(Node* early, Node* wrong_lca);)
1685 NOT_PRODUCT(void dump_idoms_in_reverse(const Node* n, const Node_List& idom_list) const;)
1686
1687 public:
1688 void set_created_loop_node() { _created_loop_node = true; }
1689 bool created_loop_node() { return _created_loop_node; }
1690 void register_new_node(Node* n, Node* blk);
1691 void register_new_node_with_ctrl_of(Node* new_node, Node* ctrl_of) {
1692 register_new_node(new_node, get_ctrl(ctrl_of));
1693 }
1694
1695 Node* clone_and_register(Node* n, Node* ctrl) {
1696 n = n->clone();
1697 register_new_node(n, ctrl);
1698 return n;
1699 }
1700
1701 #ifdef ASSERT
1702 void dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA);
1703 #endif
1704
1705 #ifndef PRODUCT
1706 void dump() const;
1707 void dump_idom(Node* n) const { dump_idom(n, 1000); } // For debugging
1708 void dump_idom(Node* n, uint count) const;
1709 void get_idoms(Node* n, uint count, Unique_Node_List& idoms) const;
1710 void dump(IdealLoopTree* loop, uint rpo_idx, Node_List &rpo_list) const;
1711 IdealLoopTree* get_loop_idx(Node* n) const {
1712 // Dead nodes have no loop, so return the top level loop instead
1713 return _loop_or_ctrl[n->_idx] ? (IdealLoopTree*)_loop_or_ctrl[n->_idx] : _ltree_root;
1714 }
1715 // Print some stats
1716 static void print_statistics();
1717 static int _loop_invokes; // Count of PhaseIdealLoop invokes
1718 static int _loop_work; // Sum of PhaseIdealLoop x _unique
1719 static volatile int _long_loop_candidates;
1720 static volatile int _long_loop_nests;
1721 static volatile int _long_loop_counted_loops;
1722 #endif
1723
1724 #ifdef ASSERT
1725 void verify() const;
1726 bool verify_idom_and_nodes(Node* root, const PhaseIdealLoop* phase_verify) const;
1727 bool verify_idom(Node* n, const PhaseIdealLoop* phase_verify) const;
1728 bool verify_loop_ctrl(Node* n, const PhaseIdealLoop* phase_verify) const;
1729 #endif
1730
1731 void rpo(Node* start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list) const;
1732
1733 void check_counted_loop_shape(IdealLoopTree* loop, Node* x, BasicType bt) NOT_DEBUG_RETURN;
1734
1735 LoopNode* create_inner_head(IdealLoopTree* loop, BaseCountedLoopNode* head, IfNode* exit_test);
1736
1737
1738 int extract_long_range_checks(const IdealLoopTree* loop, jint stride_con, int iters_limit, PhiNode* phi,
1739 Node_List &range_checks);
1740
1741 void transform_long_range_checks(int stride_con, const Node_List &range_checks, Node* outer_phi,
1742 Node* inner_iters_actual_int, Node* inner_phi,
1743 Node* iv_add, LoopNode* inner_head);
1744
1745 Node* get_late_ctrl_with_anti_dep(LoadNode* n, Node* early, Node* LCA);
1746
1747 bool ctrl_of_use_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop, Node* ctrl);
1748
1749 bool ctrl_of_all_uses_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop);
1750
1751 Node* compute_early_ctrl(Node* n, Node* n_ctrl);
1752
1753 void try_sink_out_of_loop(Node* n);
1754
1755 Node* clamp(Node* R, Node* L, Node* H);
1756
1757 bool safe_for_if_replacement(const Node* dom) const;
1758
1759 void push_pinned_nodes_thru_region(IfNode* dom_if, Node* region);
1760
1761 bool try_merge_identical_ifs(Node* n);
1762
1763 void clone_loop_body(const Node_List& body, Node_List &old_new, CloneMap* cm);
1764
1765 void fix_body_edges(const Node_List &body, IdealLoopTree* loop, const Node_List &old_new, int dd,
1766 IdealLoopTree* parent, bool partial);
1767
1768 void fix_ctrl_uses(const Node_List& body, const IdealLoopTree* loop, Node_List &old_new, CloneLoopMode mode,
1769 Node* side_by_side_idom, CloneMap* cm, Node_List &worklist);
1770
1771 void fix_data_uses(Node_List& body, IdealLoopTree* loop, CloneLoopMode mode, IdealLoopTree* outer_loop,
1772 uint new_counter, Node_List& old_new, Node_List& worklist, Node_List*& split_if_set,
1773 Node_List*& split_bool_set, Node_List*& split_cex_set);
1774
1775 void finish_clone_loop(Node_List* split_if_set, Node_List* split_bool_set, Node_List* split_cex_set);
1776
1777 bool at_relevant_ctrl(Node* n, const Node* blk1, const Node* blk2);
1778
1779 bool clone_cmp_loadklass_down(Node* n, const Node* blk1, const Node* blk2);
1780 void clone_loadklass_nodes_at_cmp_index(const Node* n, Node* cmp, int i);
1781 bool clone_cmp_down(Node* n, const Node* blk1, const Node* blk2);
1782 void clone_template_assertion_expression_down(Node* node);
1783
1784 Node* similar_subtype_check(const Node* x, Node* r_in);
1785
1786 void update_addp_chain_base(Node* x, Node* old_base, Node* new_base);
1787
1788 bool can_move_to_inner_loop(Node* n, LoopNode* n_loop, Node* x);
1789
1790 void pin_array_access_nodes_dependent_on(Node* ctrl);
1791
1792 Node* ensure_node_and_inputs_are_above_pre_end(CountedLoopEndNode* pre_end, Node* node);
1793 };
1794
1795
1796 class AutoNodeBudget : public StackObj
1797 {
1798 public:
1799 enum budget_check_t { BUDGET_CHECK, NO_BUDGET_CHECK };
1800
1801 AutoNodeBudget(PhaseIdealLoop* phase, budget_check_t chk = BUDGET_CHECK)
1802 : _phase(phase),
1803 _check_at_final(chk == BUDGET_CHECK),
1804 _nodes_at_begin(0)
1805 {
1806 precond(_phase != nullptr);
1807
1808 _nodes_at_begin = _phase->require_nodes_begin();
1809 }
1810
1811 ~AutoNodeBudget() {
1812 #ifndef PRODUCT
1813 if (TraceLoopOpts) {
1814 uint request = _phase->nodes_required();
1815 uint delta = _phase->C->live_nodes() - _nodes_at_begin;
1816
1817 if (request < delta) {
1818 tty->print_cr("Exceeding node budget: %d < %d", request, delta);
1819 } else {
1820 uint const REQUIRE_MIN = PhaseIdealLoop::REQUIRE_MIN;
1821 // Identify the worst estimates as "poor" ones.
1822 if (request > REQUIRE_MIN && delta > 0) {
1823 if ((delta > REQUIRE_MIN && request > 3 * delta) ||
1824 (delta <= REQUIRE_MIN && request > 10 * delta)) {
1825 tty->print_cr("Poor node estimate: %d >> %d", request, delta);
1826 }
1827 }
1828 }
1829 }
1830 #endif // PRODUCT
1831 _phase->require_nodes_final(_nodes_at_begin, _check_at_final);
1832 }
1833
1834 private:
1835 PhaseIdealLoop* _phase;
1836 bool _check_at_final;
1837 uint _nodes_at_begin;
1838 };
1839
1840 inline Node* IdealLoopTree::tail() {
1841 // Handle lazy update of _tail field.
1842 if (_tail->in(0) == nullptr) {
1843 _tail = _phase->get_ctrl(_tail);
1844 }
1845 return _tail;
1846 }
1847
1848 inline Node* IdealLoopTree::head() {
1849 // Handle lazy update of _head field.
1850 if (_head->in(0) == nullptr) {
1851 _head = _phase->get_ctrl(_head);
1852 }
1853 return _head;
1854 }
1855
1856 // Iterate over the loop tree using a preorder, left-to-right traversal.
1857 //
1858 // Example that visits all counted loops from within PhaseIdealLoop
1859 //
1860 // for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
1861 // IdealLoopTree* lpt = iter.current();
1862 // if (!lpt->is_counted()) continue;
1863 // ...
1864 class LoopTreeIterator : public StackObj {
1865 private:
1866 IdealLoopTree* _root;
1867 IdealLoopTree* _curnt;
1868
1869 public:
1870 LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {}
1871
1872 bool done() { return _curnt == nullptr; } // Finished iterating?
1873
1874 void next(); // Advance to next loop tree
1875
1876 IdealLoopTree* current() { return _curnt; } // Return current value of iterator.
1877 };
1878
1879 // Compute probability of reaching some CFG node from a fixed
1880 // dominating CFG node
1881 class PathFrequency {
1882 private:
1883 Node* _dom; // frequencies are computed relative to this node
1884 Node_Stack _stack;
1885 GrowableArray<float> _freqs_stack; // keep track of intermediate result at regions
1886 GrowableArray<float> _freqs; // cache frequencies
1887 PhaseIdealLoop* _phase;
1888
1889 float check_and_truncate_frequency(float f) {
1890 assert(f >= 0, "Incorrect frequency");
1891 // We do not perform an exact (f <= 1) check
1892 // this would be error prone with rounding of floats.
1893 // Performing a check like (f <= 1+eps) would be of benefit,
1894 // however, it is not evident how to determine such an eps,
1895 // given that an arbitrary number of add/mul operations
1896 // are performed on these frequencies.
1897 return (f > 1) ? 1 : f;
1898 }
1899
1900 public:
1901 PathFrequency(Node* dom, PhaseIdealLoop* phase)
1902 : _dom(dom), _stack(0), _phase(phase) {
1903 }
1904
1905 float to(Node* n);
1906 };
1907
1908 // Class to clone a data node graph by taking a list of data nodes. This is done in 2 steps:
1909 // 1. Clone the data nodes
1910 // 2. Fix the cloned data inputs pointing to the old nodes to the cloned inputs by using an old->new mapping.
1911 class DataNodeGraph : public StackObj {
1912 PhaseIdealLoop* const _phase;
1913 const Unique_Node_List& _data_nodes;
1914 OrigToNewHashtable _orig_to_new;
1915
1916 public:
1917 DataNodeGraph(const Unique_Node_List& data_nodes, PhaseIdealLoop* phase)
1918 : _phase(phase),
1919 _data_nodes(data_nodes),
1920 // Use 107 as best guess which is the first resize value in ResizeableResourceHashtable::large_table_sizes.
1921 _orig_to_new(107, MaxNodeLimit)
1922 {
1923 #ifdef ASSERT
1924 for (uint i = 0; i < data_nodes.size(); i++) {
1925 assert(!data_nodes[i]->is_CFG(), "only data nodes");
1926 }
1927 #endif
1928 }
1929 NONCOPYABLE(DataNodeGraph);
1930
1931 private:
1932 void clone(Node* node, Node* new_ctrl);
1933 void clone_data_nodes(Node* new_ctrl);
1934 void clone_data_nodes_and_transform_opaque_loop_nodes(const TransformStrategyForOpaqueLoopNodes& transform_strategy,
1935 Node* new_ctrl);
1936 void rewire_clones_to_cloned_inputs();
1937 void transform_opaque_node(const TransformStrategyForOpaqueLoopNodes& transform_strategy, Node* node);
1938
1939 public:
1940 // Clone the provided data node collection and rewire the clones in such a way to create an identical graph copy.
1941 // Set 'new_ctrl' as ctrl for the cloned nodes.
1942 const OrigToNewHashtable& clone(Node* new_ctrl) {
1943 assert(_orig_to_new.number_of_entries() == 0, "should not call this method twice in a row");
1944 clone_data_nodes(new_ctrl);
1945 rewire_clones_to_cloned_inputs();
1946 return _orig_to_new;
1947 }
1948
1949 // Create a copy of the data nodes provided to the constructor by doing the following:
1950 // Clone all non-OpaqueLoop* nodes and rewire them to create an identical subgraph copy. For the OpaqueLoop* nodes,
1951 // apply the provided transformation strategy and include the transformed node into the subgraph copy to get a complete
1952 // "cloned-and-transformed" graph copy. For all newly cloned nodes (which could also be new OpaqueLoop* nodes), set
1953 // `new_ctrl` as ctrl.
1954 const OrigToNewHashtable& clone_with_opaque_loop_transform_strategy(
1955 const TransformStrategyForOpaqueLoopNodes& transform_strategy,
1956 Node* new_ctrl) {
1957 clone_data_nodes_and_transform_opaque_loop_nodes(transform_strategy, new_ctrl);
1958 rewire_clones_to_cloned_inputs();
1959 return _orig_to_new;
1960 }
1961 };
1962 #endif // SHARE_OPTO_LOOPNODE_HPP