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
34 class CmpNode;
35 class BaseCountedLoopEndNode;
36 class CountedLoopNode;
37 class IdealLoopTree;
38 class LoopNode;
39 class Node;
40 class OuterStripMinedLoopEndNode;
41 class PathFrequency;
42 class PhaseIdealLoop;
43 class CountedLoopReserveKit;
44 class VectorSet;
45 class Invariance;
46 struct small_cache;
47
48 //
49 // I D E A L I Z E D L O O P S
50 //
51 // Idealized loops are the set of loops I perform more interesting
52 // transformations on, beyond simple hoisting.
53
54 //------------------------------LoopNode---------------------------------------
55 // Simple loop header. Fall in path on left, loop-back path on right.
56 class LoopNode : public RegionNode {
57 // Size is bigger to hold the flags. However, the flags do not change
58 // the semantics so it does not appear in the hash & cmp functions.
59 virtual uint size_of() const { return sizeof(*this); }
60 protected:
61 uint _loop_flags;
62 // Names for flag bitfields
63 enum { Normal=0, Pre=1, Main=2, Post=3, PreMainPostFlagsMask=3,
64 MainHasNoPreLoop = 1<<2,
65 HasExactTripCount = 1<<3,
66 InnerLoop = 1<<4,
67 PartialPeelLoop = 1<<5,
68 PartialPeelFailed = 1<<6,
69 HasReductions = 1<<7,
70 WasSlpAnalyzed = 1<<8,
71 PassedSlpAnalysis = 1<<9,
72 DoUnrollOnly = 1<<10,
73 VectorizedLoop = 1<<11,
74 HasAtomicPostLoop = 1<<12,
75 HasRangeChecks = 1<<13,
76 IsMultiversioned = 1<<14,
77 StripMined = 1<<15,
78 SubwordLoop = 1<<16,
79 ProfileTripFailed = 1<<17,
80 LoopNestInnerLoop = 1<< 18,
81 LoopNestLongOuterLoop = 1<< 19,
82 FlattenedArrays = 1<<20};
83
84 char _unswitch_count;
85 enum { _unswitch_max=3 };
86 char _postloop_flags;
87 enum { LoopNotRCEChecked = 0, LoopRCEChecked = 1, RCEPostLoop = 2 };
88
89 // Expected trip count from profile data
90 float _profile_trip_cnt;
91
92 public:
93 // Names for edge indices
94 enum { Self=0, EntryControl, LoopBackControl };
95
96 bool is_inner_loop() const { return _loop_flags & InnerLoop; }
97 void set_inner_loop() { _loop_flags |= InnerLoop; }
98
99 bool range_checks_present() const { return _loop_flags & HasRangeChecks; }
100 bool is_multiversioned() const { return _loop_flags & IsMultiversioned; }
101 bool is_vectorized_loop() const { return _loop_flags & VectorizedLoop; }
102 bool is_partial_peel_loop() const { return _loop_flags & PartialPeelLoop; }
103 void set_partial_peel_loop() { _loop_flags |= PartialPeelLoop; }
104 bool partial_peel_has_failed() const { return _loop_flags & PartialPeelFailed; }
105 bool is_strip_mined() const { return _loop_flags & StripMined; }
106 bool is_profile_trip_failed() const { return _loop_flags & ProfileTripFailed; }
107 bool is_subword_loop() const { return _loop_flags & SubwordLoop; }
108 bool is_loop_nest_inner_loop() const { return _loop_flags & LoopNestInnerLoop; }
109 bool is_loop_nest_outer_loop() const { return _loop_flags & LoopNestLongOuterLoop; }
110 bool is_flattened_arrays() const { return _loop_flags & FlattenedArrays; }
111
112 void mark_partial_peel_failed() { _loop_flags |= PartialPeelFailed; }
113 void mark_has_reductions() { _loop_flags |= HasReductions; }
114 void mark_was_slp() { _loop_flags |= WasSlpAnalyzed; }
115 void mark_passed_slp() { _loop_flags |= PassedSlpAnalysis; }
116 void mark_do_unroll_only() { _loop_flags |= DoUnrollOnly; }
117 void mark_loop_vectorized() { _loop_flags |= VectorizedLoop; }
118 void mark_has_atomic_post_loop() { _loop_flags |= HasAtomicPostLoop; }
119 void mark_has_range_checks() { _loop_flags |= HasRangeChecks; }
120 void clear_has_range_checks() { _loop_flags &= ~HasRangeChecks; }
121 void mark_is_multiversioned() { _loop_flags |= IsMultiversioned; }
122 void mark_strip_mined() { _loop_flags |= StripMined; }
123 void clear_strip_mined() { _loop_flags &= ~StripMined; }
124 void mark_profile_trip_failed() { _loop_flags |= ProfileTripFailed; }
125 void mark_subword_loop() { _loop_flags |= SubwordLoop; }
126 void mark_loop_nest_inner_loop() { _loop_flags |= LoopNestInnerLoop; }
127 void mark_loop_nest_outer_loop() { _loop_flags |= LoopNestLongOuterLoop; }
128 void mark_flattened_arrays() { _loop_flags |= FlattenedArrays; }
129
130 int unswitch_max() { return _unswitch_max; }
131 int unswitch_count() { return _unswitch_count; }
132
133 int has_been_range_checked() const { return _postloop_flags & LoopRCEChecked; }
134 void set_has_been_range_checked() { _postloop_flags |= LoopRCEChecked; }
135 int is_rce_post_loop() const { return _postloop_flags & RCEPostLoop; }
136 void set_is_rce_post_loop() { _postloop_flags |= RCEPostLoop; }
137
138 void set_unswitch_count(int val) {
139 assert (val <= unswitch_max(), "too many unswitches");
140 _unswitch_count = val;
141 }
142
143 void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; }
144 float profile_trip_cnt() { return _profile_trip_cnt; }
145
146 LoopNode(Node *entry, Node *backedge)
147 : RegionNode(3), _loop_flags(0), _unswitch_count(0),
148 _postloop_flags(0), _profile_trip_cnt(COUNT_UNKNOWN) {
149 init_class_id(Class_Loop);
150 init_req(EntryControl, entry);
151 init_req(LoopBackControl, backedge);
152 }
153
154 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
155 virtual int Opcode() const;
156 bool can_be_counted_loop(PhaseTransform* phase) const {
157 return req() == 3 && in(0) != NULL &&
158 in(1) != NULL && phase->type(in(1)) != Type::TOP &&
159 in(2) != NULL && phase->type(in(2)) != Type::TOP;
160 }
161 bool is_valid_counted_loop(BasicType bt) const;
162 #ifndef PRODUCT
163 virtual void dump_spec(outputStream *st) const;
164 #endif
165
166 void verify_strip_mined(int expect_skeleton) const NOT_DEBUG_RETURN;
167 virtual LoopNode* skip_strip_mined(int expect_skeleton = 1) { return this; }
168 virtual IfTrueNode* outer_loop_tail() const { ShouldNotReachHere(); return NULL; }
169 virtual OuterStripMinedLoopEndNode* outer_loop_end() const { ShouldNotReachHere(); return NULL; }
170 virtual IfFalseNode* outer_loop_exit() const { ShouldNotReachHere(); return NULL; }
171 virtual SafePointNode* outer_safepoint() const { ShouldNotReachHere(); return NULL; }
172 };
173
174 //------------------------------Counted Loops----------------------------------
175 // Counted loops are all trip-counted loops, with exactly 1 trip-counter exit
176 // path (and maybe some other exit paths). The trip-counter exit is always
177 // last in the loop. The trip-counter have to stride by a constant;
178 // the exit value is also loop invariant.
179
180 // CountedLoopNodes and CountedLoopEndNodes come in matched pairs. The
181 // CountedLoopNode has the incoming loop control and the loop-back-control
182 // which is always the IfTrue before the matching CountedLoopEndNode. The
183 // CountedLoopEndNode has an incoming control (possibly not the
184 // CountedLoopNode if there is control flow in the loop), the post-increment
185 // trip-counter value, and the limit. The trip-counter value is always of
186 // the form (Op old-trip-counter stride). The old-trip-counter is produced
187 // by a Phi connected to the CountedLoopNode. The stride is constant.
188 // The Op is any commutable opcode, including Add, Mul, Xor. The
189 // CountedLoopEndNode also takes in the loop-invariant limit value.
190
191 // From a CountedLoopNode I can reach the matching CountedLoopEndNode via the
192 // loop-back control. From CountedLoopEndNodes I can reach CountedLoopNodes
193 // via the old-trip-counter from the Op node.
194
195 //------------------------------CountedLoopNode--------------------------------
196 // CountedLoopNodes head simple counted loops. CountedLoopNodes have as
197 // inputs the incoming loop-start control and the loop-back control, so they
198 // act like RegionNodes. They also take in the initial trip counter, the
199 // loop-invariant stride and the loop-invariant limit value. CountedLoopNodes
200 // produce a loop-body control and the trip counter value. Since
201 // CountedLoopNodes behave like RegionNodes I still have a standard CFG model.
202
203 class BaseCountedLoopNode : public LoopNode {
204 public:
205 BaseCountedLoopNode(Node *entry, Node *backedge)
206 : LoopNode(entry, backedge) {
207 }
208
209 Node *init_control() const { return in(EntryControl); }
210 Node *back_control() const { return in(LoopBackControl); }
211
212 Node* init_trip() const;
213 Node* stride() const;
214 bool stride_is_con() const;
215 Node* limit() const;
216 Node* incr() const;
217 Node* phi() const;
218
219 BaseCountedLoopEndNode* loopexit_or_null() const;
220 BaseCountedLoopEndNode* loopexit() const;
221
222 virtual BasicType bt() const = 0;
223
224 jlong stride_con() const;
225
226 static BaseCountedLoopNode* make(Node* entry, Node* backedge, BasicType bt);
227 };
228
229
230 class CountedLoopNode : public BaseCountedLoopNode {
231 // Size is bigger to hold _main_idx. However, _main_idx does not change
232 // the semantics so it does not appear in the hash & cmp functions.
233 virtual uint size_of() const { return sizeof(*this); }
234
235 // For Pre- and Post-loops during debugging ONLY, this holds the index of
236 // the Main CountedLoop. Used to assert that we understand the graph shape.
237 node_idx_t _main_idx;
238
239 // Known trip count calculated by compute_exact_trip_count()
240 uint _trip_count;
241
242 // Log2 of original loop bodies in unrolled loop
243 int _unrolled_count_log2;
244
245 // Node count prior to last unrolling - used to decide if
246 // unroll,optimize,unroll,optimize,... is making progress
247 int _node_count_before_unroll;
248
249 // If slp analysis is performed we record the maximum
250 // vector mapped unroll factor here
251 int _slp_maximum_unroll_factor;
252
253 // The eventual count of vectorizable packs in slp
254 int _slp_vector_pack_count;
255
256 public:
257 CountedLoopNode(Node *entry, Node *backedge)
258 : BaseCountedLoopNode(entry, backedge), _main_idx(0), _trip_count(max_juint),
259 _unrolled_count_log2(0), _node_count_before_unroll(0),
260 _slp_maximum_unroll_factor(0), _slp_vector_pack_count(0) {
261 init_class_id(Class_CountedLoop);
262 // Initialize _trip_count to the largest possible value.
263 // Will be reset (lower) if the loop's trip count is known.
264 }
265
266 virtual int Opcode() const;
267 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
268
269 CountedLoopEndNode* loopexit_or_null() const { return (CountedLoopEndNode*) BaseCountedLoopNode::loopexit_or_null(); }
270 CountedLoopEndNode* loopexit() const { return (CountedLoopEndNode*) BaseCountedLoopNode::loopexit(); }
271 int stride_con() const;
272
273 // Match increment with optional truncation
274 static Node*
275 match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInteger** trunc_type,
276 BasicType bt);
277
278 // A 'main' loop has a pre-loop and a post-loop. The 'main' loop
279 // can run short a few iterations and may start a few iterations in.
280 // It will be RCE'd and unrolled and aligned.
281
282 // A following 'post' loop will run any remaining iterations. Used
283 // during Range Check Elimination, the 'post' loop will do any final
284 // iterations with full checks. Also used by Loop Unrolling, where
285 // the 'post' loop will do any epilog iterations needed. Basically,
286 // a 'post' loop can not profitably be further unrolled or RCE'd.
287
288 // A preceding 'pre' loop will run at least 1 iteration (to do peeling),
289 // it may do under-flow checks for RCE and may do alignment iterations
290 // so the following main loop 'knows' that it is striding down cache
291 // lines.
292
293 // A 'main' loop that is ONLY unrolled or peeled, never RCE'd or
294 // Aligned, may be missing it's pre-loop.
295 bool is_normal_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Normal; }
296 bool is_pre_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Pre; }
297 bool is_main_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Main; }
298 bool is_post_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Post; }
299 bool is_reduction_loop() const { return (_loop_flags&HasReductions) == HasReductions; }
300 bool was_slp_analyzed () const { return (_loop_flags&WasSlpAnalyzed) == WasSlpAnalyzed; }
301 bool has_passed_slp () const { return (_loop_flags&PassedSlpAnalysis) == PassedSlpAnalysis; }
302 bool is_unroll_only () const { return (_loop_flags&DoUnrollOnly) == DoUnrollOnly; }
303 bool is_main_no_pre_loop() const { return _loop_flags & MainHasNoPreLoop; }
304 bool has_atomic_post_loop () const { return (_loop_flags & HasAtomicPostLoop) == HasAtomicPostLoop; }
305 void set_main_no_pre_loop() { _loop_flags |= MainHasNoPreLoop; }
306
307 int main_idx() const { return _main_idx; }
308
309
310 void set_pre_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; }
311 void set_main_loop ( ) { assert(is_normal_loop(),""); _loop_flags |= Main; }
312 void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; }
313 void set_normal_loop( ) { _loop_flags &= ~PreMainPostFlagsMask; }
314
315 void set_trip_count(uint tc) { _trip_count = tc; }
316 uint trip_count() { return _trip_count; }
317
318 bool has_exact_trip_count() const { return (_loop_flags & HasExactTripCount) != 0; }
319 void set_exact_trip_count(uint tc) {
320 _trip_count = tc;
321 _loop_flags |= HasExactTripCount;
322 }
323 void set_nonexact_trip_count() {
324 _loop_flags &= ~HasExactTripCount;
325 }
326 void set_notpassed_slp() {
327 _loop_flags &= ~PassedSlpAnalysis;
328 }
329
330 void double_unrolled_count() { _unrolled_count_log2++; }
331 int unrolled_count() { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); }
332
333 void set_node_count_before_unroll(int ct) { _node_count_before_unroll = ct; }
334 int node_count_before_unroll() { return _node_count_before_unroll; }
335 void set_slp_max_unroll(int unroll_factor) { _slp_maximum_unroll_factor = unroll_factor; }
336 int slp_max_unroll() const { return _slp_maximum_unroll_factor; }
337 void set_slp_pack_count(int pack_count) { _slp_vector_pack_count = pack_count; }
338 int slp_pack_count() const { return _slp_vector_pack_count; }
339
340 virtual LoopNode* skip_strip_mined(int expect_skeleton = 1);
341 OuterStripMinedLoopNode* outer_loop() const;
342 virtual IfTrueNode* outer_loop_tail() const;
343 virtual OuterStripMinedLoopEndNode* outer_loop_end() const;
344 virtual IfFalseNode* outer_loop_exit() const;
345 virtual SafePointNode* outer_safepoint() const;
346
347 // If this is a main loop in a pre/main/post loop nest, walk over
348 // the predicates that were inserted by
349 // duplicate_predicates()/add_range_check_predicate()
350 static Node* skip_predicates_from_entry(Node* ctrl);
351 Node* skip_predicates();
352
353 virtual BasicType bt() const {
354 return T_INT;
355 }
356
357 Node* is_canonical_loop_entry();
358
359 #ifndef PRODUCT
360 virtual void dump_spec(outputStream *st) const;
361 #endif
362
363 static bool is_zero_trip_guard_if(const IfNode* iff);
364 };
365
366 class LongCountedLoopNode : public BaseCountedLoopNode {
367 public:
368 LongCountedLoopNode(Node *entry, Node *backedge)
369 : BaseCountedLoopNode(entry, backedge) {
370 init_class_id(Class_LongCountedLoop);
371 }
372
373 virtual int Opcode() const;
374
375 virtual BasicType bt() const {
376 return T_LONG;
377 }
378
379 LongCountedLoopEndNode* loopexit_or_null() const { return (LongCountedLoopEndNode*) BaseCountedLoopNode::loopexit_or_null(); }
380 LongCountedLoopEndNode* loopexit() const { return (LongCountedLoopEndNode*) BaseCountedLoopNode::loopexit(); }
381 };
382
383
384 //------------------------------CountedLoopEndNode-----------------------------
385 // CountedLoopEndNodes end simple trip counted loops. They act much like
386 // IfNodes.
387
388 class BaseCountedLoopEndNode : public IfNode {
389 public:
390 enum { TestControl, TestValue };
391 BaseCountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
392 : IfNode(control, test, prob, cnt) {
393 init_class_id(Class_BaseCountedLoopEnd);
394 }
395
396 Node *cmp_node() const { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : NULL; }
397 Node* incr() const { Node* tmp = cmp_node(); return (tmp && tmp->req() == 3) ? tmp->in(1) : NULL; }
398 Node* limit() const { Node* tmp = cmp_node(); return (tmp && tmp->req() == 3) ? tmp->in(2) : NULL; }
399 Node* stride() const { Node* tmp = incr(); return (tmp && tmp->req() == 3) ? tmp->in(2) : NULL; }
400 Node* init_trip() const { Node* tmp = phi(); return (tmp && tmp->req() == 3) ? tmp->in(1) : NULL; }
401 bool stride_is_con() const { Node *tmp = stride(); return (tmp != NULL && tmp->is_Con()); }
402
403 PhiNode* phi() const {
404 Node* tmp = incr();
405 if (tmp && tmp->req() == 3) {
406 Node* phi = tmp->in(1);
407 if (phi->is_Phi()) {
408 return phi->as_Phi();
409 }
410 }
411 return NULL;
412 }
413
414 BaseCountedLoopNode* loopnode() const {
415 // The CountedLoopNode that goes with this CountedLoopEndNode may
416 // have been optimized out by the IGVN so be cautious with the
417 // pattern matching on the graph
418 PhiNode* iv_phi = phi();
419 if (iv_phi == NULL) {
420 return NULL;
421 }
422 Node* ln = iv_phi->in(0);
423 if (!ln->is_BaseCountedLoop() || ln->as_BaseCountedLoop()->loopexit_or_null() != this) {
424 return NULL;
425 }
426 if (ln->as_BaseCountedLoop()->bt() != bt()) {
427 return NULL;
428 }
429 return ln->as_BaseCountedLoop();
430 }
431
432 BoolTest::mask test_trip() const { return in(TestValue)->as_Bool()->_test._test; }
433
434 jlong stride_con() const;
435 virtual BasicType bt() const = 0;
436
437 static BaseCountedLoopEndNode* make(Node* control, Node* test, float prob, float cnt, BasicType bt);
438 };
439
440 class CountedLoopEndNode : public BaseCountedLoopEndNode {
441 public:
442
443 CountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
444 : BaseCountedLoopEndNode(control, test, prob, cnt) {
445 init_class_id(Class_CountedLoopEnd);
446 }
447 virtual int Opcode() const;
448
449 CountedLoopNode* loopnode() const {
450 return (CountedLoopNode*) BaseCountedLoopEndNode::loopnode();
451 }
452
453 virtual BasicType bt() const {
454 return T_INT;
455 }
456
457 #ifndef PRODUCT
458 virtual void dump_spec(outputStream *st) const;
459 #endif
460 };
461
462 class LongCountedLoopEndNode : public BaseCountedLoopEndNode {
463 public:
464 LongCountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
465 : BaseCountedLoopEndNode(control, test, prob, cnt) {
466 init_class_id(Class_LongCountedLoopEnd);
467 }
468
469 LongCountedLoopNode* loopnode() const {
470 return (LongCountedLoopNode*) BaseCountedLoopEndNode::loopnode();
471 }
472
473 virtual int Opcode() const;
474
475 virtual BasicType bt() const {
476 return T_LONG;
477 }
478 };
479
480
481 inline BaseCountedLoopEndNode* BaseCountedLoopNode::loopexit_or_null() const {
482 Node* bctrl = back_control();
483 if (bctrl == NULL) return NULL;
484
485 Node* lexit = bctrl->in(0);
486 if (!lexit->is_BaseCountedLoopEnd()) {
487 return NULL;
488 }
489 BaseCountedLoopEndNode* result = lexit->as_BaseCountedLoopEnd();
490 if (result->bt() != bt()) {
491 return NULL;
492 }
493 return result;
494 }
495
496 inline BaseCountedLoopEndNode* BaseCountedLoopNode::loopexit() const {
497 BaseCountedLoopEndNode* cle = loopexit_or_null();
498 assert(cle != NULL, "loopexit is NULL");
499 return cle;
500 }
501
502 inline Node* BaseCountedLoopNode::init_trip() const {
503 BaseCountedLoopEndNode* cle = loopexit_or_null();
504 return cle != NULL ? cle->init_trip() : NULL;
505 }
506 inline Node* BaseCountedLoopNode::stride() const {
507 BaseCountedLoopEndNode* cle = loopexit_or_null();
508 return cle != NULL ? cle->stride() : NULL;
509 }
510
511 inline bool BaseCountedLoopNode::stride_is_con() const {
512 BaseCountedLoopEndNode* cle = loopexit_or_null();
513 return cle != NULL && cle->stride_is_con();
514 }
515 inline Node* BaseCountedLoopNode::limit() const {
516 BaseCountedLoopEndNode* cle = loopexit_or_null();
517 return cle != NULL ? cle->limit() : NULL;
518 }
519 inline Node* BaseCountedLoopNode::incr() const {
520 BaseCountedLoopEndNode* cle = loopexit_or_null();
521 return cle != NULL ? cle->incr() : NULL;
522 }
523 inline Node* BaseCountedLoopNode::phi() const {
524 BaseCountedLoopEndNode* cle = loopexit_or_null();
525 return cle != NULL ? cle->phi() : NULL;
526 }
527
528 inline jlong BaseCountedLoopNode::stride_con() const {
529 BaseCountedLoopEndNode* cle = loopexit_or_null();
530 return cle != NULL ? cle->stride_con() : 0;
531 }
532
533
534 //------------------------------LoopLimitNode-----------------------------
535 // Counted Loop limit node which represents exact final iterator value:
536 // trip_count = (limit - init_trip + stride - 1)/stride
537 // final_value= trip_count * stride + init_trip.
538 // Use HW instructions to calculate it when it can overflow in integer.
539 // Note, final_value should fit into integer since counted loop has
540 // limit check: limit <= max_int-stride.
541 class LoopLimitNode : public Node {
542 enum { Init=1, Limit=2, Stride=3 };
543 public:
544 LoopLimitNode( Compile* C, Node *init, Node *limit, Node *stride ) : Node(0,init,limit,stride) {
545 // Put it on the Macro nodes list to optimize during macro nodes expansion.
546 init_flags(Flag_is_macro);
547 C->add_macro_node(this);
548 }
549 virtual int Opcode() const;
550 virtual const Type *bottom_type() const { return TypeInt::INT; }
551 virtual uint ideal_reg() const { return Op_RegI; }
552 virtual const Type* Value(PhaseGVN* phase) const;
553 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
554 virtual Node* Identity(PhaseGVN* phase);
555 };
556
557 // Support for strip mining
558 class OuterStripMinedLoopNode : public LoopNode {
559 private:
560 static void fix_sunk_stores(CountedLoopEndNode* inner_cle, LoopNode* inner_cl, PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
561
562 public:
563 OuterStripMinedLoopNode(Compile* C, Node *entry, Node *backedge)
564 : LoopNode(entry, backedge) {
565 init_class_id(Class_OuterStripMinedLoop);
566 init_flags(Flag_is_macro);
567 C->add_macro_node(this);
568 }
569
570 virtual int Opcode() const;
571
572 virtual IfTrueNode* outer_loop_tail() const;
573 virtual OuterStripMinedLoopEndNode* outer_loop_end() const;
574 virtual IfFalseNode* outer_loop_exit() const;
575 virtual SafePointNode* outer_safepoint() const;
576 void adjust_strip_mined_loop(PhaseIterGVN* igvn);
577
578 void remove_outer_loop_and_safepoint(PhaseIterGVN* igvn) const;
579
580 void transform_to_counted_loop(PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
581
582 static Node* register_new_node(Node* node, LoopNode* ctrl, PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
583
584 Node* register_control(Node* node, Node* loop, Node* idom, PhaseIterGVN* igvn,
585 PhaseIdealLoop* iloop);
586 };
587
588 class OuterStripMinedLoopEndNode : public IfNode {
589 public:
590 OuterStripMinedLoopEndNode(Node *control, Node *test, float prob, float cnt)
591 : IfNode(control, test, prob, cnt) {
592 init_class_id(Class_OuterStripMinedLoopEnd);
593 }
594
595 virtual int Opcode() const;
596
597 virtual const Type* Value(PhaseGVN* phase) const;
598 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
599
600 bool is_expanded(PhaseGVN *phase) const;
601 };
602
603 // -----------------------------IdealLoopTree----------------------------------
604 class IdealLoopTree : public ResourceObj {
605 public:
606 IdealLoopTree *_parent; // Parent in loop tree
607 IdealLoopTree *_next; // Next sibling in loop tree
608 IdealLoopTree *_child; // First child in loop tree
609
610 // The head-tail backedge defines the loop.
611 // If a loop has multiple backedges, this is addressed during cleanup where
612 // we peel off the multiple backedges, merging all edges at the bottom and
613 // ensuring that one proper backedge flow into the loop.
614 Node *_head; // Head of loop
615 Node *_tail; // Tail of loop
616 inline Node *tail(); // Handle lazy update of _tail field
617 inline Node *head(); // Handle lazy update of _head field
618 PhaseIdealLoop* _phase;
619 int _local_loop_unroll_limit;
620 int _local_loop_unroll_factor;
621
622 Node_List _body; // Loop body for inner loops
623
624 uint16_t _nest; // Nesting depth
625 uint8_t _irreducible:1, // True if irreducible
626 _has_call:1, // True if has call safepoint
627 _has_sfpt:1, // True if has non-call safepoint
628 _rce_candidate:1; // True if candidate for range check elimination
629
630 Node_List* _safepts; // List of safepoints in this loop
631 Node_List* _required_safept; // A inner loop cannot delete these safepts;
632 bool _allow_optimizations; // Allow loop optimizations
633
634 IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail )
635 : _parent(0), _next(0), _child(0),
636 _head(head), _tail(tail),
637 _phase(phase),
638 _local_loop_unroll_limit(0), _local_loop_unroll_factor(0),
639 _nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0),
640 _safepts(NULL),
641 _required_safept(NULL),
642 _allow_optimizations(true)
643 {
644 precond(_head != NULL);
645 precond(_tail != NULL);
646 }
647
648 // Is 'l' a member of 'this'?
649 bool is_member(const IdealLoopTree *l) const; // Test for nested membership
650
651 // Set loop nesting depth. Accumulate has_call bits.
652 int set_nest( uint depth );
653
654 // Split out multiple fall-in edges from the loop header. Move them to a
655 // private RegionNode before the loop. This becomes the loop landing pad.
656 void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt );
657
658 // Split out the outermost loop from this shared header.
659 void split_outer_loop( PhaseIdealLoop *phase );
660
661 // Merge all the backedges from the shared header into a private Region.
662 // Feed that region as the one backedge to this loop.
663 void merge_many_backedges( PhaseIdealLoop *phase );
664
665 // Split shared headers and insert loop landing pads.
666 // Insert a LoopNode to replace the RegionNode.
667 // Returns TRUE if loop tree is structurally changed.
668 bool beautify_loops( PhaseIdealLoop *phase );
669
670 // Perform optimization to use the loop predicates for null checks and range checks.
671 // Applies to any loop level (not just the innermost one)
672 bool loop_predication( PhaseIdealLoop *phase);
673
674 // Perform iteration-splitting on inner loops. Split iterations to
675 // avoid range checks or one-shot null checks. Returns false if the
676 // current round of loop opts should stop.
677 bool iteration_split( PhaseIdealLoop *phase, Node_List &old_new );
678
679 // Driver for various flavors of iteration splitting. Returns false
680 // if the current round of loop opts should stop.
681 bool iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new );
682
683 // Given dominators, try to find loops with calls that must always be
684 // executed (call dominates loop tail). These loops do not need non-call
685 // safepoints (ncsfpt).
686 void check_safepts(VectorSet &visited, Node_List &stack);
687
688 // Allpaths backwards scan from loop tail, terminating each path at first safepoint
689 // encountered.
690 void allpaths_check_safepts(VectorSet &visited, Node_List &stack);
691
692 // Remove safepoints from loop. Optionally keeping one.
693 void remove_safepoints(PhaseIdealLoop* phase, bool keep_one);
694
695 // Convert to counted loops where possible
696 void counted_loop( PhaseIdealLoop *phase );
697
698 // Check for Node being a loop-breaking test
699 Node *is_loop_exit(Node *iff) const;
700
701 // Remove simplistic dead code from loop body
702 void DCE_loop_body();
703
704 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage.
705 // Replace with a 1-in-10 exit guess.
706 void adjust_loop_exit_prob( PhaseIdealLoop *phase );
707
708 // Return TRUE or FALSE if the loop should never be RCE'd or aligned.
709 // Useful for unrolling loops with NO array accesses.
710 bool policy_peel_only( PhaseIdealLoop *phase ) const;
711
712 // Return TRUE or FALSE if the loop should be unswitched -- clone
713 // loop with an invariant test
714 bool policy_unswitching( PhaseIdealLoop *phase ) const;
715
716 // Micro-benchmark spamming. Remove empty loops.
717 bool do_remove_empty_loop( PhaseIdealLoop *phase );
718
719 // Convert one iteration loop into normal code.
720 bool do_one_iteration_loop( PhaseIdealLoop *phase );
721
722 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can
723 // move some loop-invariant test (usually a null-check) before the loop.
724 bool policy_peeling(PhaseIdealLoop *phase);
725
726 uint estimate_peeling(PhaseIdealLoop *phase);
727
728 // Return TRUE or FALSE if the loop should be maximally unrolled. Stash any
729 // known trip count in the counted loop node.
730 bool policy_maximally_unroll(PhaseIdealLoop *phase) const;
731
732 // Return TRUE or FALSE if the loop should be unrolled or not. Apply unroll
733 // if the loop is a counted loop and the loop body is small enough.
734 bool policy_unroll(PhaseIdealLoop *phase);
735
736 // Loop analyses to map to a maximal superword unrolling for vectorization.
737 void policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_ct);
738
739 // Return TRUE or FALSE if the loop should be range-check-eliminated.
740 // Gather a list of IF tests that are dominated by iteration splitting;
741 // also gather the end of the first split and the start of the 2nd split.
742 bool policy_range_check(PhaseIdealLoop* phase, bool provisional, BasicType bt) const;
743
744 // Return TRUE if "iff" is a range check.
745 bool is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar DEBUG_ONLY(COMMA ProjNode *predicate_proj)) const;
746 bool is_range_check_if(IfNode* iff, PhaseIdealLoop* phase, BasicType bt, Node* iv, Node*& range, Node*& offset,
747 jlong& scale) const;
748
749 // Estimate the number of nodes required when cloning a loop (body).
750 uint est_loop_clone_sz(uint factor) const;
751 // Estimate the number of nodes required when unrolling a loop (body).
752 uint est_loop_unroll_sz(uint factor) const;
753
754 // Compute loop trip count if possible
755 void compute_trip_count(PhaseIdealLoop* phase);
756
757 // Compute loop trip count from profile data
758 float compute_profile_trip_cnt_helper(Node* n);
759 void compute_profile_trip_cnt( PhaseIdealLoop *phase );
760
761 // Reassociate invariant expressions.
762 void reassociate_invariants(PhaseIdealLoop *phase);
763 // Reassociate invariant binary expressions.
764 Node* reassociate(Node* n1, PhaseIdealLoop *phase);
765 // Reassociate invariant add and subtract expressions.
766 Node* reassociate_add_sub(Node* n1, int inv1_idx, int inv2_idx, PhaseIdealLoop *phase);
767 // Return nonzero index of invariant operand if invariant and variant
768 // are combined with an associative binary. Helper for reassociate_invariants.
769 int find_invariant(Node* n, PhaseIdealLoop *phase);
770 // Return TRUE if "n" is associative.
771 bool is_associative(Node* n, Node* base=NULL);
772
773 // Return true if n is invariant
774 bool is_invariant(Node* n) const;
775
776 // Put loop body on igvn work list
777 void record_for_igvn();
778
779 bool is_root() { return _parent == NULL; }
780 // A proper/reducible loop w/o any (occasional) dead back-edge.
781 bool is_loop() { return !_irreducible && !tail()->is_top(); }
782 bool is_counted() { return is_loop() && _head->is_CountedLoop(); }
783 bool is_innermost() { return is_loop() && _child == NULL; }
784
785 void remove_main_post_loops(CountedLoopNode *cl, PhaseIdealLoop *phase);
786
787 #ifndef PRODUCT
788 void dump_head() const; // Dump loop head only
789 void dump() const; // Dump this loop recursively
790 void verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const;
791 #endif
792
793 private:
794 enum { EMPTY_LOOP_SIZE = 7 }; // Number of nodes in an empty loop.
795
796 // Estimate the number of nodes resulting from control and data flow merge.
797 uint est_loop_flow_merge_sz() const;
798
799 // Check if the number of residual iterations is large with unroll_cnt.
800 // Return true if the residual iterations are more than 10% of the trip count.
801 bool is_residual_iters_large(int unroll_cnt, CountedLoopNode *cl) const {
802 return (unroll_cnt - 1) * (100.0 / LoopPercentProfileLimit) > cl->profile_trip_cnt();
803 }
804
805 void collect_loop_core_nodes(PhaseIdealLoop* phase, Unique_Node_List& wq) const;
806
807 bool empty_loop_with_data_nodes(PhaseIdealLoop* phase) const;
808
809 void enqueue_data_nodes(PhaseIdealLoop* phase, Unique_Node_List& empty_loop_nodes, Unique_Node_List& wq) const;
810
811 bool process_safepoint(PhaseIdealLoop* phase, Unique_Node_List& empty_loop_nodes, Unique_Node_List& wq,
812 Node* sfpt) const;
813
814 bool empty_loop_candidate(PhaseIdealLoop* phase) const;
815
816 bool empty_loop_with_extra_nodes_candidate(PhaseIdealLoop* phase) const;
817 };
818
819 // -----------------------------PhaseIdealLoop---------------------------------
820 // Computes the mapping from Nodes to IdealLoopTrees. Organizes IdealLoopTrees
821 // into a loop tree. Drives the loop-based transformations on the ideal graph.
822 class PhaseIdealLoop : public PhaseTransform {
823 friend class IdealLoopTree;
824 friend class SuperWord;
825 friend class CountedLoopReserveKit;
826 friend class ShenandoahBarrierC2Support;
827 friend class AutoNodeBudget;
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( Node *n ) const { return ((intptr_t)_nodes[n->_idx]) & 1; }
891
892 private:
893 // clear out dead code after build_loop_late
894 Node_List _deadlist;
895
896 // Support for faster execution of get_late_ctrl()/dom_lca()
897 // when a node has many uses and dominator depth is deep.
898 GrowableArray<jlong> _dom_lca_tags;
899 uint _dom_lca_tags_round;
900 void init_dom_lca_tags();
901
902 // Helper for debugging bad dominance relationships
903 bool verify_dominance(Node* n, Node* use, Node* LCA, Node* early);
904
905 Node* compute_lca_of_uses(Node* n, Node* early, bool verify = false);
906
907 // Inline wrapper for frequent cases:
908 // 1) only one use
909 // 2) a use is the same as the current LCA passed as 'n1'
910 Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) {
911 assert( n->is_CFG(), "" );
912 // Fast-path NULL lca
913 if( lca != NULL && lca != n ) {
914 assert( lca->is_CFG(), "" );
915 // find LCA of all uses
916 n = dom_lca_for_get_late_ctrl_internal( lca, n, tag );
917 }
918 return find_non_split_ctrl(n);
919 }
920 Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag );
921
922 // Helper function for directing control inputs away from CFG split points.
923 Node *find_non_split_ctrl( Node *ctrl ) const {
924 if (ctrl != NULL) {
925 if (ctrl->is_MultiBranch()) {
926 ctrl = ctrl->in(0);
927 }
928 assert(ctrl->is_CFG(), "CFG");
929 }
930 return ctrl;
931 }
932
933 Node* cast_incr_before_loop(Node* incr, Node* ctrl, Node* loop);
934
935 #ifdef ASSERT
936 void ensure_zero_trip_guard_proj(Node* node, bool is_main_loop);
937 #endif
938 void copy_skeleton_predicates_to_main_loop_helper(Node* predicate, Node* init, Node* stride, IdealLoopTree* outer_loop, LoopNode* outer_main_head,
939 uint dd_main_head, const uint idx_before_pre_post, const uint idx_after_post_before_pre,
940 Node* zero_trip_guard_proj_main, Node* zero_trip_guard_proj_post, const Node_List &old_new);
941 void copy_skeleton_predicates_to_main_loop(CountedLoopNode* pre_head, Node* init, Node* stride, IdealLoopTree* outer_loop, LoopNode* outer_main_head,
942 uint dd_main_head, const uint idx_before_pre_post, const uint idx_after_post_before_pre,
943 Node* zero_trip_guard_proj_main, Node* zero_trip_guard_proj_post, const Node_List &old_new);
944 Node* clone_skeleton_predicate_and_initialize(Node* iff, Node* new_init, Node* new_stride, Node* predicate, Node* uncommon_proj, Node* control,
945 IdealLoopTree* outer_loop, Node* input_proj);
946 Node* clone_skeleton_predicate_bool(Node* iff, Node* new_init, Node* new_stride, Node* control);
947 static bool skeleton_predicate_has_opaque(IfNode* iff);
948 static void count_opaque_loop_nodes(Node* n, uint& init, uint& stride);
949 static bool subgraph_has_opaque(Node* n);
950 static void get_skeleton_predicates(Node* predicate, Unique_Node_List& list, bool get_opaque = false);
951 void update_main_loop_skeleton_predicates(Node* ctrl, CountedLoopNode* loop_head, Node* init, int stride_con);
952 void copy_skeleton_predicates_to_post_loop(LoopNode* main_loop_head, CountedLoopNode* post_loop_head, Node* init, Node* stride);
953 void initialize_skeleton_predicates_for_peeled_loop(ProjNode* predicate, LoopNode* outer_loop_head, int dd_outer_loop_head,
954 Node* init, Node* stride, IdealLoopTree* outer_loop,
955 const uint idx_before_clone, const Node_List& old_new);
956 void insert_loop_limit_check(ProjNode* limit_check_proj, Node* cmp_limit, Node* bol);
957 #ifdef ASSERT
958 bool only_has_infinite_loops();
959 #endif
960
961 void log_loop_tree();
962
963 public:
964
965 PhaseIterGVN &igvn() const { return _igvn; }
966
967 bool has_node( Node* n ) const {
968 guarantee(n != NULL, "No Node.");
969 return _nodes[n->_idx] != NULL;
970 }
971 // check if transform created new nodes that need _ctrl recorded
972 Node *get_late_ctrl( Node *n, Node *early );
973 Node *get_early_ctrl( Node *n );
974 Node *get_early_ctrl_for_expensive(Node *n, Node* earliest);
975 void set_early_ctrl(Node* n, bool update_body);
976 void set_subtree_ctrl(Node* n, bool update_body);
977 void set_ctrl( Node *n, Node *ctrl ) {
978 assert( !has_node(n) || has_ctrl(n), "" );
979 assert( ctrl->in(0), "cannot set dead control node" );
980 assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" );
981 _nodes.map( n->_idx, (Node*)((intptr_t)ctrl + 1) );
982 }
983 // Set control and update loop membership
984 void set_ctrl_and_loop(Node* n, Node* ctrl) {
985 IdealLoopTree* old_loop = get_loop(get_ctrl(n));
986 IdealLoopTree* new_loop = get_loop(ctrl);
987 if (old_loop != new_loop) {
988 if (old_loop->_child == NULL) old_loop->_body.yank(n);
989 if (new_loop->_child == NULL) new_loop->_body.push(n);
990 }
991 set_ctrl(n, ctrl);
992 }
993 // Control nodes can be replaced or subsumed. During this pass they
994 // get their replacement Node in slot 1. Instead of updating the block
995 // location of all Nodes in the subsumed block, we lazily do it. As we
996 // pull such a subsumed block out of the array, we write back the final
997 // correct block.
998 Node *get_ctrl( Node *i ) {
999
1000 assert(has_node(i), "");
1001 Node *n = get_ctrl_no_update(i);
1002 _nodes.map( i->_idx, (Node*)((intptr_t)n + 1) );
1003 assert(has_node(i) && has_ctrl(i), "");
1004 assert(n == find_non_split_ctrl(n), "must return legal ctrl" );
1005 return n;
1006 }
1007 // true if CFG node d dominates CFG node n
1008 bool is_dominator(Node *d, Node *n);
1009 // return get_ctrl for a data node and self(n) for a CFG node
1010 Node* ctrl_or_self(Node* n) {
1011 if (has_ctrl(n))
1012 return get_ctrl(n);
1013 else {
1014 assert (n->is_CFG(), "must be a CFG node");
1015 return n;
1016 }
1017 }
1018
1019 Node *get_ctrl_no_update_helper(Node *i) const {
1020 assert(has_ctrl(i), "should be control, not loop");
1021 return (Node*)(((intptr_t)_nodes[i->_idx]) & ~1);
1022 }
1023
1024 Node *get_ctrl_no_update(Node *i) const {
1025 assert( has_ctrl(i), "" );
1026 Node *n = get_ctrl_no_update_helper(i);
1027 if (!n->in(0)) {
1028 // Skip dead CFG nodes
1029 do {
1030 n = get_ctrl_no_update_helper(n);
1031 } while (!n->in(0));
1032 n = find_non_split_ctrl(n);
1033 }
1034 return n;
1035 }
1036
1037 // Check for loop being set
1038 // "n" must be a control node. Returns true if "n" is known to be in a loop.
1039 bool has_loop( Node *n ) const {
1040 assert(!has_node(n) || !has_ctrl(n), "");
1041 return has_node(n);
1042 }
1043 // Set loop
1044 void set_loop( Node *n, IdealLoopTree *loop ) {
1045 _nodes.map(n->_idx, (Node*)loop);
1046 }
1047 // Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms. Replace
1048 // the 'old_node' with 'new_node'. Kill old-node. Add a reference
1049 // from old_node to new_node to support the lazy update. Reference
1050 // replaces loop reference, since that is not needed for dead node.
1051 void lazy_update(Node *old_node, Node *new_node) {
1052 assert(old_node != new_node, "no cycles please");
1053 // Re-use the side array slot for this node to provide the
1054 // forwarding pointer.
1055 _nodes.map(old_node->_idx, (Node*)((intptr_t)new_node + 1));
1056 }
1057 void lazy_replace(Node *old_node, Node *new_node) {
1058 _igvn.replace_node(old_node, new_node);
1059 lazy_update(old_node, new_node);
1060 }
1061
1062 private:
1063
1064 // Place 'n' in some loop nest, where 'n' is a CFG node
1065 void build_loop_tree();
1066 int build_loop_tree_impl( Node *n, int pre_order );
1067 // Insert loop into the existing loop tree. 'innermost' is a leaf of the
1068 // loop tree, not the root.
1069 IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost );
1070
1071 // Place Data nodes in some loop nest
1072 void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
1073 void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
1074 void build_loop_late_post_work(Node* n, bool pinned);
1075 void build_loop_late_post(Node* n);
1076 void verify_strip_mined_scheduling(Node *n, Node* least);
1077
1078 // Array of immediate dominance info for each CFG node indexed by node idx
1079 private:
1080 uint _idom_size;
1081 Node **_idom; // Array of immediate dominators
1082 uint *_dom_depth; // Used for fast LCA test
1083 GrowableArray<uint>* _dom_stk; // For recomputation of dom depth
1084 LoopOptsMode _mode;
1085
1086 // build the loop tree and perform any requested optimizations
1087 void build_and_optimize();
1088
1089 // Dominators for the sea of nodes
1090 void Dominators();
1091
1092 // Compute the Ideal Node to Loop mapping
1093 PhaseIdealLoop(PhaseIterGVN& igvn, LoopOptsMode mode) :
1094 PhaseTransform(Ideal_Loop),
1095 _igvn(igvn),
1096 _verify_me(nullptr),
1097 _verify_only(false),
1098 _mode(mode),
1099 _nodes_required(UINT_MAX) {
1100 assert(mode != LoopOptsVerify, "wrong constructor to verify IdealLoop");
1101 build_and_optimize();
1102 }
1103
1104 #ifndef PRODUCT
1105 // Verify that verify_me made the same decisions as a fresh run
1106 // or only verify that the graph is valid if verify_me is null.
1107 PhaseIdealLoop(PhaseIterGVN& igvn, const PhaseIdealLoop* verify_me = nullptr) :
1108 PhaseTransform(Ideal_Loop),
1109 _igvn(igvn),
1110 _verify_me(verify_me),
1111 _verify_only(verify_me == nullptr),
1112 _mode(LoopOptsVerify),
1113 _nodes_required(UINT_MAX) {
1114 build_and_optimize();
1115 }
1116 #endif
1117
1118 public:
1119 Node* idom_no_update(Node* d) const {
1120 return idom_no_update(d->_idx);
1121 }
1122
1123 Node* idom_no_update(uint didx) const {
1124 assert(didx < _idom_size, "oob");
1125 Node* n = _idom[didx];
1126 assert(n != NULL,"Bad immediate dominator info.");
1127 while (n->in(0) == NULL) { // Skip dead CFG nodes
1128 n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1);
1129 assert(n != NULL,"Bad immediate dominator info.");
1130 }
1131 return n;
1132 }
1133
1134 Node *idom(Node* d) const {
1135 return idom(d->_idx);
1136 }
1137
1138 Node *idom(uint didx) const {
1139 Node *n = idom_no_update(didx);
1140 _idom[didx] = n; // Lazily remove dead CFG nodes from table.
1141 return n;
1142 }
1143
1144 uint dom_depth(Node* d) const {
1145 guarantee(d != NULL, "Null dominator info.");
1146 guarantee(d->_idx < _idom_size, "");
1147 return _dom_depth[d->_idx];
1148 }
1149 void set_idom(Node* d, Node* n, uint dom_depth);
1150 // Locally compute IDOM using dom_lca call
1151 Node *compute_idom( Node *region ) const;
1152 // Recompute dom_depth
1153 void recompute_dom_depth();
1154
1155 // Is safept not required by an outer loop?
1156 bool is_deleteable_safept(Node* sfpt);
1157
1158 // Replace parallel induction variable (parallel to trip counter)
1159 void replace_parallel_iv(IdealLoopTree *loop);
1160
1161 Node *dom_lca( Node *n1, Node *n2 ) const {
1162 return find_non_split_ctrl(dom_lca_internal(n1, n2));
1163 }
1164 Node *dom_lca_internal( Node *n1, Node *n2 ) const;
1165
1166 // Build and verify the loop tree without modifying the graph. This
1167 // is useful to verify that all inputs properly dominate their uses.
1168 static void verify(PhaseIterGVN& igvn) {
1169 #ifdef ASSERT
1170 ResourceMark rm;
1171 Compile::TracePhase tp("idealLoopVerify", &timers[_t_idealLoopVerify]);
1172 PhaseIdealLoop v(igvn);
1173 #endif
1174 }
1175
1176 // Recommended way to use PhaseIdealLoop.
1177 // Run PhaseIdealLoop in some mode and allocates a local scope for memory allocations.
1178 static void optimize(PhaseIterGVN &igvn, LoopOptsMode mode) {
1179 ResourceMark rm;
1180 PhaseIdealLoop v(igvn, mode);
1181
1182 Compile* C = Compile::current();
1183 if (!C->failing()) {
1184 // Cleanup any modified bits
1185 igvn.optimize();
1186
1187 v.log_loop_tree();
1188 }
1189 }
1190
1191 // True if the method has at least 1 irreducible loop
1192 bool _has_irreducible_loops;
1193
1194 // Per-Node transform
1195 virtual Node* transform(Node* n) { return NULL; }
1196
1197 Node* loop_exit_control(Node* x, IdealLoopTree* loop);
1198 Node* loop_exit_test(Node* back_control, IdealLoopTree* loop, Node*& incr, Node*& limit, BoolTest::mask& bt, float& cl_prob);
1199 Node* loop_iv_incr(Node* incr, Node* x, IdealLoopTree* loop, Node*& phi_incr);
1200 Node* loop_iv_stride(Node* incr, IdealLoopTree* loop, Node*& xphi);
1201 PhiNode* loop_iv_phi(Node* xphi, Node* phi_incr, Node* x, IdealLoopTree* loop);
1202
1203 bool is_counted_loop(Node* x, IdealLoopTree*&loop, BasicType iv_bt);
1204
1205 Node* loop_nest_replace_iv(Node* iv_to_replace, Node* inner_iv, Node* outer_phi, Node* inner_head, BasicType bt);
1206 bool create_loop_nest(IdealLoopTree* loop, Node_List &old_new);
1207 #ifdef ASSERT
1208 bool convert_to_long_loop(Node* cmp, Node* phi, IdealLoopTree* loop);
1209 #endif
1210 void add_empty_predicate(Deoptimization::DeoptReason reason, Node* inner_head, IdealLoopTree* loop, SafePointNode* sfpt);
1211 SafePointNode* find_safepoint(Node* back_control, Node* x, IdealLoopTree* loop);
1212 IdealLoopTree* insert_outer_loop(IdealLoopTree* loop, LoopNode* outer_l, Node* outer_ift);
1213 IdealLoopTree* create_outer_strip_mined_loop(BoolNode *test, Node *cmp, Node *init_control,
1214 IdealLoopTree* loop, float cl_prob, float le_fcnt,
1215 Node*& entry_control, Node*& iffalse);
1216
1217 Node* exact_limit( IdealLoopTree *loop );
1218
1219 // Return a post-walked LoopNode
1220 IdealLoopTree *get_loop( Node *n ) const {
1221 // Dead nodes have no loop, so return the top level loop instead
1222 if (!has_node(n)) return _ltree_root;
1223 assert(!has_ctrl(n), "");
1224 return (IdealLoopTree*)_nodes[n->_idx];
1225 }
1226
1227 IdealLoopTree* ltree_root() const { return _ltree_root; }
1228
1229 // Is 'n' a (nested) member of 'loop'?
1230 int is_member( const IdealLoopTree *loop, Node *n ) const {
1231 return loop->is_member(get_loop(n)); }
1232
1233 // This is the basic building block of the loop optimizations. It clones an
1234 // entire loop body. It makes an old_new loop body mapping; with this
1235 // mapping you can find the new-loop equivalent to an old-loop node. All
1236 // new-loop nodes are exactly equal to their old-loop counterparts, all
1237 // edges are the same. All exits from the old-loop now have a RegionNode
1238 // that merges the equivalent new-loop path. This is true even for the
1239 // normal "loop-exit" condition. All uses of loop-invariant old-loop values
1240 // now come from (one or more) Phis that merge their new-loop equivalents.
1241 // Parameter side_by_side_idom:
1242 // When side_by_size_idom is NULL, the dominator tree is constructed for
1243 // the clone loop to dominate the original. Used in construction of
1244 // pre-main-post loop sequence.
1245 // When nonnull, the clone and original are side-by-side, both are
1246 // dominated by the passed in side_by_side_idom node. Used in
1247 // construction of unswitched loops.
1248 enum CloneLoopMode {
1249 IgnoreStripMined = 0, // Only clone inner strip mined loop
1250 CloneIncludesStripMined = 1, // clone both inner and outer strip mined loops
1251 ControlAroundStripMined = 2 // Only clone inner strip mined loop,
1252 // result control flow branches
1253 // either to inner clone or outer
1254 // strip mined loop.
1255 };
1256 void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth,
1257 CloneLoopMode mode, Node* side_by_side_idom = NULL);
1258 void clone_loop_handle_data_uses(Node* old, Node_List &old_new,
1259 IdealLoopTree* loop, IdealLoopTree* companion_loop,
1260 Node_List*& split_if_set, Node_List*& split_bool_set,
1261 Node_List*& split_cex_set, Node_List& worklist,
1262 uint new_counter, CloneLoopMode mode);
1263 void clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
1264 IdealLoopTree* outer_loop, int dd, Node_List &old_new,
1265 Node_List& extra_data_nodes);
1266
1267 // If we got the effect of peeling, either by actually peeling or by
1268 // making a pre-loop which must execute at least once, we can remove
1269 // all loop-invariant dominated tests in the main body.
1270 void peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new );
1271
1272 // Generate code to do a loop peel for the given loop (and body).
1273 // old_new is a temp array.
1274 void do_peeling( IdealLoopTree *loop, Node_List &old_new );
1275
1276 // Add pre and post loops around the given loop. These loops are used
1277 // during RCE, unrolling and aligning loops.
1278 void insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only );
1279
1280 // Add post loop after the given loop.
1281 Node *insert_post_loop(IdealLoopTree* loop, Node_List& old_new,
1282 CountedLoopNode* main_head, CountedLoopEndNode* main_end,
1283 Node*& incr, Node* limit, CountedLoopNode*& post_head);
1284
1285 // Add an RCE'd post loop which we will multi-version adapt for run time test path usage
1286 void insert_scalar_rced_post_loop( IdealLoopTree *loop, Node_List &old_new );
1287
1288 // Add a vector post loop between a vector main loop and the current post loop
1289 void insert_vector_post_loop(IdealLoopTree *loop, Node_List &old_new);
1290 // If Node n lives in the back_ctrl block, we clone a private version of n
1291 // in preheader_ctrl block and return that, otherwise return n.
1292 Node *clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones );
1293
1294 // Take steps to maximally unroll the loop. Peel any odd iterations, then
1295 // unroll to do double iterations. The next round of major loop transforms
1296 // will repeat till the doubled loop body does all remaining iterations in 1
1297 // pass.
1298 void do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new );
1299
1300 // Unroll the loop body one step - make each trip do 2 iterations.
1301 void do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip );
1302
1303 // Mark vector reduction candidates before loop unrolling
1304 void mark_reductions( IdealLoopTree *loop );
1305
1306 // Return true if exp is a constant times an induction var
1307 bool is_scaled_iv(Node* exp, Node* iv, BasicType bt, jlong* p_scale, bool* p_short_scale, int depth = 0);
1308
1309 bool is_iv(Node* exp, Node* iv, BasicType bt);
1310
1311 // Return true if exp is a scaled induction var plus (or minus) constant
1312 bool is_scaled_iv_plus_offset(Node* exp, Node* iv, BasicType bt, jlong* p_scale, Node** p_offset, bool* p_short_scale = NULL, int depth = 0);
1313 bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset) {
1314 jlong long_scale;
1315 if (is_scaled_iv_plus_offset(exp, iv, T_INT, &long_scale, p_offset)) {
1316 int int_scale = checked_cast<int>(long_scale);
1317 if (p_scale != NULL) {
1318 *p_scale = int_scale;
1319 }
1320 return true;
1321 }
1322 return false;
1323 }
1324 // Helper for finding more complex matches to is_scaled_iv_plus_offset.
1325 bool is_scaled_iv_plus_extra_offset(Node* exp1, Node* offset2, Node* iv,
1326 BasicType bt,
1327 jlong* p_scale, Node** p_offset,
1328 bool* p_short_scale, int depth);
1329
1330 // Create a new if above the uncommon_trap_if_pattern for the predicate to be promoted
1331 ProjNode* create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry, Deoptimization::DeoptReason reason,
1332 int opcode, bool rewire_uncommon_proj_phi_inputs = false,
1333 bool if_cont_is_true_proj = true);
1334
1335 private:
1336 // Helper functions for create_new_if_for_predicate()
1337 void set_ctrl_of_nodes_with_same_ctrl(Node* node, ProjNode* old_ctrl, Node* new_ctrl);
1338 Unique_Node_List find_nodes_with_same_ctrl(Node* node, const ProjNode* ctrl);
1339 Node* clone_nodes_with_same_ctrl(Node* node, ProjNode* old_ctrl, Node* new_ctrl);
1340 Dict clone_nodes(const Node_List& list_to_clone);
1341 void rewire_cloned_nodes_to_ctrl(const ProjNode* old_ctrl, Node* new_ctrl, const Node_List& nodes_with_same_ctrl,
1342 const Dict& old_new_mapping);
1343 void rewire_inputs_of_clones_to_clones(Node* new_ctrl, Node* clone, const Dict& old_new_mapping, const Node* next);
1344
1345 public:
1346 void register_control(Node* n, IdealLoopTree *loop, Node* pred, bool update_body = true);
1347
1348 static Node* skip_all_loop_predicates(Node* entry);
1349 static Node* skip_loop_predicates(Node* entry);
1350 static ProjNode* next_predicate(ProjNode* predicate);
1351
1352 // Find a good location to insert a predicate
1353 static ProjNode* find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason);
1354
1355 class Predicates {
1356 public:
1357 // given loop entry, find all predicates above loop
1358 Predicates(Node* entry);
1359
1360 // Proj of empty loop limit check predicate
1361 ProjNode* loop_limit_check() {
1362 return _loop_limit_check;
1363 }
1364
1365 // Proj of empty profile predicate
1366 ProjNode* profile_predicate() {
1367 return _profile_predicate;
1368 }
1369
1370 // Proj of empty predicate
1371 ProjNode* predicate() {
1372 return _predicate;
1373 }
1374
1375 // First control node above all predicates
1376 Node* skip_all() {
1377 return _entry_to_all_predicates;
1378 }
1379
1380 private:
1381 ProjNode*_loop_limit_check = nullptr;
1382 ProjNode* _profile_predicate = nullptr;
1383 ProjNode* _predicate = nullptr;
1384 Node* _entry_to_all_predicates = nullptr;
1385 };
1386
1387 // Find a predicate
1388 static Node* find_predicate(Node* entry);
1389 // Construct a range check for a predicate if
1390 BoolNode* rc_predicate(IdealLoopTree *loop, Node* ctrl,
1391 int scale, Node* offset,
1392 Node* init, Node* limit, jint stride,
1393 Node* range, bool upper, bool &overflow,
1394 bool negate);
1395
1396 // Implementation of the loop predication to promote checks outside the loop
1397 bool loop_predication_impl(IdealLoopTree *loop);
1398 bool loop_predication_impl_helper(IdealLoopTree *loop, ProjNode* proj, ProjNode *predicate_proj,
1399 CountedLoopNode *cl, ConNode* zero, Invariance& invar,
1400 Deoptimization::DeoptReason reason);
1401 bool loop_predication_should_follow_branches(IdealLoopTree *loop, ProjNode *predicate_proj, float& loop_trip_cnt);
1402 void loop_predication_follow_branches(Node *c, IdealLoopTree *loop, float loop_trip_cnt,
1403 PathFrequency& pf, Node_Stack& stack, VectorSet& seen,
1404 Node_List& if_proj_list);
1405 ProjNode* insert_initial_skeleton_predicate(IfNode* iff, IdealLoopTree *loop,
1406 ProjNode* proj, ProjNode *predicate_proj,
1407 ProjNode* upper_bound_proj,
1408 int scale, Node* offset,
1409 Node* init, Node* limit, jint stride,
1410 Node* rng, bool& overflow,
1411 Deoptimization::DeoptReason reason);
1412 Node* add_range_check_predicate(IdealLoopTree* loop, CountedLoopNode* cl,
1413 Node* predicate_proj, int scale_con, Node* offset,
1414 Node* limit, jint stride_con, Node* value);
1415
1416 // Helper function to collect predicate for eliminating the useless ones
1417 void collect_potentially_useful_predicates(IdealLoopTree *loop, Unique_Node_List &predicate_opaque1);
1418 void eliminate_useless_predicates();
1419
1420 // Change the control input of expensive nodes to allow commoning by
1421 // IGVN when it is guaranteed to not result in a more frequent
1422 // execution of the expensive node. Return true if progress.
1423 bool process_expensive_nodes();
1424
1425 // Check whether node has become unreachable
1426 bool is_node_unreachable(Node *n) const {
1427 return !has_node(n) || n->is_unreachable(_igvn);
1428 }
1429
1430 // Eliminate range-checks and other trip-counter vs loop-invariant tests.
1431 int do_range_check( IdealLoopTree *loop, Node_List &old_new );
1432
1433 // Check to see if do_range_check(...) cleaned the main loop of range-checks
1434 void has_range_checks(IdealLoopTree *loop);
1435
1436 // Process post loops which have range checks and try to build a multi-version
1437 // guard to safely determine if we can execute the post loop which was RCE'd.
1438 bool multi_version_post_loops(IdealLoopTree *rce_loop, IdealLoopTree *legacy_loop);
1439
1440 // Cause the rce'd post loop to optimized away, this happens if we cannot complete multiverioning
1441 void poison_rce_post_loop(IdealLoopTree *rce_loop);
1442
1443 // Create a slow version of the loop by cloning the loop
1444 // and inserting an if to select fast-slow versions.
1445 // Return the inserted if.
1446 IfNode* create_slow_version_of_loop(IdealLoopTree *loop,
1447 Node_List &old_new,
1448 Node_List &unswitch_iffs,
1449 CloneLoopMode mode);
1450
1451 // Clone a loop and return the clone head (clone_loop_head).
1452 // Added nodes include int(1), int(0) - disconnected, If, IfTrue, IfFalse,
1453 // This routine was created for usage in CountedLoopReserveKit.
1454 //
1455 // int(1) -> If -> IfTrue -> original_loop_head
1456 // |
1457 // V
1458 // IfFalse -> clone_loop_head (returned by function pointer)
1459 //
1460 LoopNode* create_reserve_version_of_loop(IdealLoopTree *loop, CountedLoopReserveKit* lk);
1461 // Clone loop with an invariant test (that does not exit) and
1462 // insert a clone of the test that selects which version to
1463 // execute.
1464 void do_unswitching (IdealLoopTree *loop, Node_List &old_new);
1465
1466 // Find candidate "if" for unswitching
1467 IfNode* find_unswitching_candidate(const IdealLoopTree *loop, Node_List& unswitch_iffs) const;
1468
1469 // Range Check Elimination uses this function!
1470 // Constrain the main loop iterations so the affine function:
1471 // low_limit <= scale_con * I + offset < upper_limit
1472 // always holds true. That is, either increase the number of iterations in
1473 // the pre-loop or the post-loop until the condition holds true in the main
1474 // loop. Scale_con, offset and limit are all loop invariant.
1475 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);
1476 // Helper function for add_constraint().
1477 Node* adjust_limit(bool reduce, Node* scale, Node* offset, Node* rc_limit, Node* old_limit, Node* pre_ctrl, bool round);
1478
1479 // Partially peel loop up through last_peel node.
1480 bool partial_peel( IdealLoopTree *loop, Node_List &old_new );
1481 bool duplicate_loop_backedge(IdealLoopTree *loop, Node_List &old_new);
1482
1483 // Create a scheduled list of nodes control dependent on ctrl set.
1484 void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched );
1485 // Has a use in the vector set
1486 bool has_use_in_set( Node* n, VectorSet& vset );
1487 // Has use internal to the vector set (ie. not in a phi at the loop head)
1488 bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop );
1489 // clone "n" for uses that are outside of loop
1490 int clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist );
1491 // clone "n" for special uses that are in the not_peeled region
1492 void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
1493 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist );
1494 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
1495 void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp );
1496 #ifdef ASSERT
1497 // Validate the loop partition sets: peel and not_peel
1498 bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel );
1499 // Ensure that uses outside of loop are of the right form
1500 bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
1501 uint orig_exit_idx, uint clone_exit_idx);
1502 bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx);
1503 #endif
1504
1505 // Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.)
1506 int stride_of_possible_iv( Node* iff );
1507 bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; }
1508 // Return the (unique) control output node that's in the loop (if it exists.)
1509 Node* stay_in_loop( Node* n, IdealLoopTree *loop);
1510 // Insert a signed compare loop exit cloned from an unsigned compare.
1511 IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop);
1512 void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop);
1513 // Utility to register node "n" with PhaseIdealLoop
1514 void register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth);
1515 // Utility to create an if-projection
1516 ProjNode* proj_clone(ProjNode* p, IfNode* iff);
1517 // Force the iff control output to be the live_proj
1518 Node* short_circuit_if(IfNode* iff, ProjNode* live_proj);
1519 // Insert a region before an if projection
1520 RegionNode* insert_region_before_proj(ProjNode* proj);
1521 // Insert a new if before an if projection
1522 ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj);
1523
1524 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1525 // "Nearly" because all Nodes have been cloned from the original in the loop,
1526 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1527 // through the Phi recursively, and return a Bool.
1528 Node* clone_iff(PhiNode* phi);
1529 CmpNode* clone_bool(PhiNode* phi);
1530
1531
1532 // Rework addressing expressions to get the most loop-invariant stuff
1533 // moved out. We'd like to do all associative operators, but it's especially
1534 // important (common) to do address expressions.
1535 Node* remix_address_expressions(Node* n);
1536 Node* remix_address_expressions_add_left_shift(Node* n, IdealLoopTree* n_loop, Node* n_ctrl, BasicType bt);
1537
1538 // Convert add to muladd to generate MuladdS2I under certain criteria
1539 Node * convert_add_to_muladd(Node * n);
1540
1541 // Attempt to use a conditional move instead of a phi/branch
1542 Node *conditional_move( Node *n );
1543
1544 // Check for aggressive application of 'split-if' optimization,
1545 // using basic block level info.
1546 void split_if_with_blocks ( VectorSet &visited, Node_Stack &nstack);
1547 Node *split_if_with_blocks_pre ( Node *n );
1548 void split_if_with_blocks_post( Node *n );
1549 Node *has_local_phi_input( Node *n );
1550 // Mark an IfNode as being dominated by a prior test,
1551 // without actually altering the CFG (and hence IDOM info).
1552 void dominated_by(IfProjNode* prevdom, IfNode* iff, bool flip = false, bool exclude_loop_predicate = false);
1553
1554 // Split Node 'n' through merge point
1555 RegionNode* split_thru_region(Node* n, RegionNode* region);
1556 // Split Node 'n' through merge point if there is enough win.
1557 Node *split_thru_phi( Node *n, Node *region, int policy );
1558 // Found an If getting its condition-code input from a Phi in the
1559 // same block. Split thru the Region.
1560 void do_split_if(Node *iff, RegionNode** new_false_region = NULL, RegionNode** new_true_region = NULL);
1561
1562 // Conversion of fill/copy patterns into intrinsic versions
1563 bool do_intrinsify_fill();
1564 bool intrinsify_fill(IdealLoopTree* lpt);
1565 bool match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value,
1566 Node*& shift, Node*& offset);
1567
1568 private:
1569 // Return a type based on condition control flow
1570 const TypeInt* filtered_type( Node *n, Node* n_ctrl);
1571 const TypeInt* filtered_type( Node *n ) { return filtered_type(n, NULL); }
1572 // Helpers for filtered type
1573 const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl);
1574
1575 // Helper functions
1576 Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache );
1577 Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true );
1578 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 );
1579 bool split_up( Node *n, Node *blk1, Node *blk2 );
1580 void sink_use( Node *use, Node *post_loop );
1581 Node* place_outside_loop(Node* useblock, IdealLoopTree* loop) const;
1582 Node* try_move_store_before_loop(Node* n, Node *n_ctrl);
1583 void try_move_store_after_loop(Node* n);
1584 void move_flat_array_check_out_of_loop(Node* n);
1585 bool identical_backtoback_ifs(Node *n);
1586 bool flatten_array_element_type_check(Node *n);
1587 bool can_split_if(Node *n_ctrl);
1588 bool cannot_split_division(const Node* n, const Node* region) const;
1589 static bool is_divisor_counted_loop_phi(const Node* divisor, const Node* loop);
1590 bool loop_phi_backedge_type_contains_zero(const Node* phi_divisor, const Type* zero) const;
1591
1592 // Determine if a method is too big for a/another round of split-if, based on
1593 // a magic (approximate) ratio derived from the equally magic constant 35000,
1594 // previously used for this purpose (but without relating to the node limit).
1595 bool must_throttle_split_if() {
1596 uint threshold = C->max_node_limit() * 2 / 5;
1597 return C->live_nodes() > threshold;
1598 }
1599
1600 // A simplistic node request tracking mechanism, where
1601 // = UINT_MAX Request not valid or made final.
1602 // < UINT_MAX Nodes currently requested (estimate).
1603 uint _nodes_required;
1604
1605 enum { REQUIRE_MIN = 70 };
1606
1607 uint nodes_required() const { return _nodes_required; }
1608
1609 // Given the _currently_ available number of nodes, check whether there is
1610 // "room" for an additional request or not, considering the already required
1611 // number of nodes. Return TRUE if the new request is exceeding the node
1612 // budget limit, otherwise return FALSE. Note that this interpretation will
1613 // act pessimistic on additional requests when new nodes have already been
1614 // generated since the 'begin'. This behaviour fits with the intention that
1615 // node estimates/requests should be made upfront.
1616 bool exceeding_node_budget(uint required = 0) {
1617 assert(C->live_nodes() < C->max_node_limit(), "sanity");
1618 uint available = C->max_node_limit() - C->live_nodes();
1619 return available < required + _nodes_required + REQUIRE_MIN;
1620 }
1621
1622 uint require_nodes(uint require, uint minreq = REQUIRE_MIN) {
1623 precond(require > 0);
1624 _nodes_required += MAX2(require, minreq);
1625 return _nodes_required;
1626 }
1627
1628 bool may_require_nodes(uint require, uint minreq = REQUIRE_MIN) {
1629 return !exceeding_node_budget(require) && require_nodes(require, minreq) > 0;
1630 }
1631
1632 uint require_nodes_begin() {
1633 assert(_nodes_required == UINT_MAX, "Bad state (begin).");
1634 _nodes_required = 0;
1635 return C->live_nodes();
1636 }
1637
1638 // When a node request is final, optionally check that the requested number
1639 // of nodes was reasonably correct with respect to the number of new nodes
1640 // introduced since the last 'begin'. Always check that we have not exceeded
1641 // the maximum node limit.
1642 void require_nodes_final(uint live_at_begin, bool check_estimate) {
1643 assert(_nodes_required < UINT_MAX, "Bad state (final).");
1644
1645 #ifdef ASSERT
1646 if (check_estimate) {
1647 // Check that the node budget request was not off by too much (x2).
1648 // Should this be the case we _surely_ need to improve the estimates
1649 // used in our budget calculations.
1650 if (C->live_nodes() - live_at_begin > 2 * _nodes_required) {
1651 log_info(compilation)("Bad node estimate: actual = %d >> request = %d",
1652 C->live_nodes() - live_at_begin, _nodes_required);
1653 }
1654 }
1655 #endif
1656 // Assert that we have stayed within the node budget limit.
1657 assert(C->live_nodes() < C->max_node_limit(),
1658 "Exceeding node budget limit: %d + %d > %d (request = %d)",
1659 C->live_nodes() - live_at_begin, live_at_begin,
1660 C->max_node_limit(), _nodes_required);
1661
1662 _nodes_required = UINT_MAX;
1663 }
1664
1665 // Clone loop predicates to slow and fast loop when unswitching a loop
1666 void clone_predicates_to_unswitched_loop(IdealLoopTree* loop, Node_List& old_new, ProjNode*& iffast_pred, ProjNode*& ifslow_pred);
1667 ProjNode* clone_predicate_to_unswitched_loop(ProjNode* predicate_proj, Node* new_entry,
1668 Deoptimization::DeoptReason reason, bool slow_loop);
1669 void clone_skeleton_predicates_to_unswitched_loop(IdealLoopTree* loop, const Node_List& old_new, Deoptimization::DeoptReason reason,
1670 ProjNode* old_predicate_proj, ProjNode* iffast_pred, ProjNode* ifslow_pred);
1671 ProjNode* clone_skeleton_predicate_for_unswitched_loops(Node* iff, ProjNode* predicate,
1672 Deoptimization::DeoptReason reason,
1673 ProjNode* output_proj);
1674 static void check_created_predicate_for_unswitching(const Node* new_entry) PRODUCT_RETURN;
1675
1676 bool _created_loop_node;
1677 DEBUG_ONLY(void dump_idoms(Node* early, Node* wrong_lca);)
1678 NOT_PRODUCT(void dump_idoms_in_reverse(const Node* n, const Node_List& idom_list) const;)
1679
1680 public:
1681 void set_created_loop_node() { _created_loop_node = true; }
1682 bool created_loop_node() { return _created_loop_node; }
1683 void register_new_node(Node* n, Node* blk);
1684
1685 #ifdef ASSERT
1686 void dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA);
1687 #endif
1688
1689 #ifndef PRODUCT
1690 void dump() const;
1691 void dump_idom(Node* n) const { dump_idom(n, 1000); } // For debugging
1692 void dump_idom(Node* n, uint count) const;
1693 void get_idoms(Node* n, uint count, Unique_Node_List& idoms) const;
1694 void dump(IdealLoopTree* loop, uint rpo_idx, Node_List &rpo_list) const;
1695 void verify() const; // Major slow :-)
1696 void verify_compare(Node* n, const PhaseIdealLoop* loop_verify, VectorSet &visited) const;
1697 IdealLoopTree* get_loop_idx(Node* n) const {
1698 // Dead nodes have no loop, so return the top level loop instead
1699 return _nodes[n->_idx] ? (IdealLoopTree*)_nodes[n->_idx] : _ltree_root;
1700 }
1701 // Print some stats
1702 static void print_statistics();
1703 static int _loop_invokes; // Count of PhaseIdealLoop invokes
1704 static int _loop_work; // Sum of PhaseIdealLoop x _unique
1705 static volatile int _long_loop_candidates;
1706 static volatile int _long_loop_nests;
1707 static volatile int _long_loop_counted_loops;
1708 #endif
1709
1710 void rpo(Node* start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list) const;
1711
1712 void check_counted_loop_shape(IdealLoopTree* loop, Node* x, BasicType bt) NOT_DEBUG_RETURN;
1713
1714 LoopNode* create_inner_head(IdealLoopTree* loop, BaseCountedLoopNode* head, IfNode* exit_test);
1715
1716
1717 int extract_long_range_checks(const IdealLoopTree* loop, jlong stride_con, int iters_limit, PhiNode* phi,
1718 Node_List &range_checks);
1719
1720 void transform_long_range_checks(int stride_con, const Node_List &range_checks, Node* outer_phi,
1721 Node* inner_iters_actual_int, Node* inner_phi,
1722 Node* iv_add, LoopNode* inner_head);
1723
1724 Node* get_late_ctrl_with_anti_dep(LoadNode* n, Node* early, Node* LCA);
1725
1726 bool ctrl_of_use_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop, Node* ctrl);
1727
1728 bool ctrl_of_all_uses_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop);
1729
1730 Node* compute_early_ctrl(Node* n, Node* n_ctrl);
1731
1732 void try_sink_out_of_loop(Node* n);
1733
1734 Node* clamp(Node* R, Node* L, Node* H);
1735
1736 bool safe_for_if_replacement(const Node* dom) const;
1737
1738 void push_pinned_nodes_thru_region(IfNode* dom_if, Node* region);
1739
1740 bool try_merge_identical_ifs(Node* n);
1741
1742 void clone_loop_body(const Node_List& body, Node_List &old_new, CloneMap* cm);
1743
1744 void fix_body_edges(const Node_List &body, IdealLoopTree* loop, const Node_List &old_new, int dd,
1745 IdealLoopTree* parent, bool partial);
1746
1747 void fix_ctrl_uses(const Node_List& body, const IdealLoopTree* loop, Node_List &old_new, CloneLoopMode mode,
1748 Node* side_by_side_idom, CloneMap* cm, Node_List &worklist);
1749
1750 void fix_data_uses(Node_List& body, IdealLoopTree* loop, CloneLoopMode mode, IdealLoopTree* outer_loop,
1751 uint new_counter, Node_List& old_new, Node_List& worklist, Node_List*& split_if_set,
1752 Node_List*& split_bool_set, Node_List*& split_cex_set);
1753
1754 void finish_clone_loop(Node_List* split_if_set, Node_List* split_bool_set, Node_List* split_cex_set);
1755
1756 bool clone_cmp_down(Node* n, const Node* blk1, const Node* blk2);
1757
1758 void clone_loadklass_nodes_at_cmp_index(const Node* n, Node* cmp, int i);
1759
1760 bool clone_cmp_loadklass_down(Node* n, const Node* blk1, const Node* blk2);
1761
1762 bool at_relevant_ctrl(Node* n, const Node* blk1, const Node* blk2);
1763 };
1764
1765
1766 class AutoNodeBudget : public StackObj
1767 {
1768 public:
1769 enum budget_check_t { BUDGET_CHECK, NO_BUDGET_CHECK };
1770
1771 AutoNodeBudget(PhaseIdealLoop* phase, budget_check_t chk = BUDGET_CHECK)
1772 : _phase(phase),
1773 _check_at_final(chk == BUDGET_CHECK),
1774 _nodes_at_begin(0)
1775 {
1776 precond(_phase != NULL);
1777
1778 _nodes_at_begin = _phase->require_nodes_begin();
1779 }
1780
1781 ~AutoNodeBudget() {
1782 #ifndef PRODUCT
1783 if (TraceLoopOpts) {
1784 uint request = _phase->nodes_required();
1785 uint delta = _phase->C->live_nodes() - _nodes_at_begin;
1786
1787 if (request < delta) {
1788 tty->print_cr("Exceeding node budget: %d < %d", request, delta);
1789 } else {
1790 uint const REQUIRE_MIN = PhaseIdealLoop::REQUIRE_MIN;
1791 // Identify the worst estimates as "poor" ones.
1792 if (request > REQUIRE_MIN && delta > 0) {
1793 if ((delta > REQUIRE_MIN && request > 3 * delta) ||
1794 (delta <= REQUIRE_MIN && request > 10 * delta)) {
1795 tty->print_cr("Poor node estimate: %d >> %d", request, delta);
1796 }
1797 }
1798 }
1799 }
1800 #endif // PRODUCT
1801 _phase->require_nodes_final(_nodes_at_begin, _check_at_final);
1802 }
1803
1804 private:
1805 PhaseIdealLoop* _phase;
1806 bool _check_at_final;
1807 uint _nodes_at_begin;
1808 };
1809
1810
1811 // This kit may be used for making of a reserved copy of a loop before this loop
1812 // goes under non-reversible changes.
1813 //
1814 // Function create_reserve() creates a reserved copy (clone) of the loop.
1815 // The reserved copy is created by calling
1816 // PhaseIdealLoop::create_reserve_version_of_loop - see there how
1817 // the original and reserved loops are connected in the outer graph.
1818 // If create_reserve succeeded, it returns 'true' and _has_reserved is set to 'true'.
1819 //
1820 // By default the reserved copy (clone) of the loop is created as dead code - it is
1821 // dominated in the outer loop by this node chain:
1822 // intcon(1)->If->IfFalse->reserved_copy.
1823 // The original loop is dominated by the same node chain but IfTrue projection:
1824 // intcon(0)->If->IfTrue->original_loop.
1825 //
1826 // In this implementation of CountedLoopReserveKit the ctor includes create_reserve()
1827 // and the dtor, checks _use_new value.
1828 // If _use_new == false, it "switches" control to reserved copy of the loop
1829 // by simple replacing of node intcon(1) with node intcon(0).
1830 //
1831 // Here is a proposed example of usage (see also SuperWord::output in superword.cpp).
1832 //
1833 // void CountedLoopReserveKit_example()
1834 // {
1835 // CountedLoopReserveKit lrk((phase, lpt, DoReserveCopy = true); // create local object
1836 // if (DoReserveCopy && !lrk.has_reserved()) {
1837 // return; //failed to create reserved loop copy
1838 // }
1839 // ...
1840 // //something is wrong, switch to original loop
1841 /// if(something_is_wrong) return; // ~CountedLoopReserveKit makes the switch
1842 // ...
1843 // //everything worked ok, return with the newly modified loop
1844 // lrk.use_new();
1845 // return; // ~CountedLoopReserveKit does nothing once use_new() was called
1846 // }
1847 //
1848 // Keep in mind, that by default if create_reserve() is not followed by use_new()
1849 // the dtor will "switch to the original" loop.
1850 // NOTE. You you modify outside of the original loop this class is no help.
1851 //
1852 class CountedLoopReserveKit {
1853 private:
1854 PhaseIdealLoop* _phase;
1855 IdealLoopTree* _lpt;
1856 LoopNode* _lp;
1857 IfNode* _iff;
1858 LoopNode* _lp_reserved;
1859 bool _has_reserved;
1860 bool _use_new;
1861 const bool _active; //may be set to false in ctor, then the object is dummy
1862
1863 public:
1864 CountedLoopReserveKit(PhaseIdealLoop* phase, IdealLoopTree *loop, bool active);
1865 ~CountedLoopReserveKit();
1866 void use_new() {_use_new = true;}
1867 void set_iff(IfNode* x) {_iff = x;}
1868 bool has_reserved() const { return _active && _has_reserved;}
1869 private:
1870 bool create_reserve();
1871 };// class CountedLoopReserveKit
1872
1873 inline Node* IdealLoopTree::tail() {
1874 // Handle lazy update of _tail field.
1875 if (_tail->in(0) == NULL) {
1876 _tail = _phase->get_ctrl(_tail);
1877 }
1878 return _tail;
1879 }
1880
1881 inline Node* IdealLoopTree::head() {
1882 // Handle lazy update of _head field.
1883 if (_head->in(0) == NULL) {
1884 _head = _phase->get_ctrl(_head);
1885 }
1886 return _head;
1887 }
1888
1889 // Iterate over the loop tree using a preorder, left-to-right traversal.
1890 //
1891 // Example that visits all counted loops from within PhaseIdealLoop
1892 //
1893 // for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
1894 // IdealLoopTree* lpt = iter.current();
1895 // if (!lpt->is_counted()) continue;
1896 // ...
1897 class LoopTreeIterator : public StackObj {
1898 private:
1899 IdealLoopTree* _root;
1900 IdealLoopTree* _curnt;
1901
1902 public:
1903 LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {}
1904
1905 bool done() { return _curnt == NULL; } // Finished iterating?
1906
1907 void next(); // Advance to next loop tree
1908
1909 IdealLoopTree* current() { return _curnt; } // Return current value of iterator.
1910 };
1911
1912 // Compute probability of reaching some CFG node from a fixed
1913 // dominating CFG node
1914 class PathFrequency {
1915 private:
1916 Node* _dom; // frequencies are computed relative to this node
1917 Node_Stack _stack;
1918 GrowableArray<float> _freqs_stack; // keep track of intermediate result at regions
1919 GrowableArray<float> _freqs; // cache frequencies
1920 PhaseIdealLoop* _phase;
1921
1922 float check_and_truncate_frequency(float f) {
1923 assert(f >= 0, "Incorrect frequency");
1924 // We do not perform an exact (f <= 1) check
1925 // this would be error prone with rounding of floats.
1926 // Performing a check like (f <= 1+eps) would be of benefit,
1927 // however, it is not evident how to determine such an eps,
1928 // given that an arbitrary number of add/mul operations
1929 // are performed on these frequencies.
1930 return (f > 1) ? 1 : f;
1931 }
1932
1933 public:
1934 PathFrequency(Node* dom, PhaseIdealLoop* phase)
1935 : _dom(dom), _stack(0), _phase(phase) {
1936 }
1937
1938 float to(Node* n);
1939 };
1940
1941 #endif // SHARE_OPTO_LOOPNODE_HPP