1 /*
2 * Copyright (c) 1998, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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24
25 #ifndef SHARE_VM_OPTO_LOOPNODE_HPP
26 #define SHARE_VM_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 CountedLoopEndNode;
36 class CountedLoopNode;
37 class IdealLoopTree;
38 class LoopNode;
39 class Node;
40 class PhaseIdealLoop;
41 class CountedLoopReserveKit;
42 class VectorSet;
43 class Invariance;
44 struct small_cache;
45
46 //
47 // I D E A L I Z E D L O O P S
48 //
49 // Idealized loops are the set of loops I perform more interesting
50 // transformations on, beyond simple hoisting.
51
52 //------------------------------LoopNode---------------------------------------
53 // Simple loop header. Fall in path on left, loop-back path on right.
54 class LoopNode : public RegionNode {
55 // Size is bigger to hold the flags. However, the flags do not change
56 // the semantics so it does not appear in the hash & cmp functions.
57 virtual uint size_of() const { return sizeof(*this); }
58 protected:
59 short _loop_flags;
60 // Names for flag bitfields
61 enum { Normal=0, Pre=1, Main=2, Post=3, PreMainPostFlagsMask=3,
62 MainHasNoPreLoop=4,
63 HasExactTripCount=8,
64 InnerLoop=16,
65 PartialPeelLoop=32,
66 PartialPeelFailed=64,
67 HasReductions=128,
68 WasSlpAnalyzed=256,
69 PassedSlpAnalysis=512,
70 DoUnrollOnly=1024,
71 VectorizedLoop=2048,
72 HasAtomicPostLoop=4096,
73 HasRangeChecks=8192,
74 IsMultiversioned=16384};
75 char _unswitch_count;
76 enum { _unswitch_max=3 };
77 char _postloop_flags;
78 enum { LoopNotRCEChecked = 0, LoopRCEChecked = 1, RCEPostLoop = 2 };
79
80 public:
81 // Names for edge indices
82 enum { Self=0, EntryControl, LoopBackControl };
83
84 int is_inner_loop() const { return _loop_flags & InnerLoop; }
85 void set_inner_loop() { _loop_flags |= InnerLoop; }
86
87 int range_checks_present() const { return _loop_flags & HasRangeChecks; }
88 int is_multiversioned() const { return _loop_flags & IsMultiversioned; }
89 int is_vectorized_loop() const { return _loop_flags & VectorizedLoop; }
90 int is_partial_peel_loop() const { return _loop_flags & PartialPeelLoop; }
91 void set_partial_peel_loop() { _loop_flags |= PartialPeelLoop; }
92 int partial_peel_has_failed() const { return _loop_flags & PartialPeelFailed; }
93
94 void mark_partial_peel_failed() { _loop_flags |= PartialPeelFailed; }
95 void mark_has_reductions() { _loop_flags |= HasReductions; }
96 void mark_was_slp() { _loop_flags |= WasSlpAnalyzed; }
97 void mark_passed_slp() { _loop_flags |= PassedSlpAnalysis; }
98 void mark_do_unroll_only() { _loop_flags |= DoUnrollOnly; }
99 void mark_loop_vectorized() { _loop_flags |= VectorizedLoop; }
100 void mark_has_atomic_post_loop() { _loop_flags |= HasAtomicPostLoop; }
101 void mark_has_range_checks() { _loop_flags |= HasRangeChecks; }
102 void mark_is_multiversioned() { _loop_flags |= IsMultiversioned; }
103
104 int unswitch_max() { return _unswitch_max; }
105 int unswitch_count() { return _unswitch_count; }
106
107 int has_been_range_checked() const { return _postloop_flags & LoopRCEChecked; }
108 void set_has_been_range_checked() { _postloop_flags |= LoopRCEChecked; }
109 int is_rce_post_loop() const { return _postloop_flags & RCEPostLoop; }
110 void set_is_rce_post_loop() { _postloop_flags |= RCEPostLoop; }
111
112 void set_unswitch_count(int val) {
113 assert (val <= unswitch_max(), "too many unswitches");
114 _unswitch_count = val;
115 }
116
117 LoopNode(Node *entry, Node *backedge) : RegionNode(3), _loop_flags(0), _unswitch_count(0), _postloop_flags(0) {
118 init_class_id(Class_Loop);
119 init_req(EntryControl, entry);
120 init_req(LoopBackControl, backedge);
121 }
122
123 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
124 virtual int Opcode() const;
125 bool can_be_counted_loop(PhaseTransform* phase) const {
126 return req() == 3 && in(0) != NULL &&
127 in(1) != NULL && phase->type(in(1)) != Type::TOP &&
128 in(2) != NULL && phase->type(in(2)) != Type::TOP;
129 }
130 bool is_valid_counted_loop() const;
131 #ifndef PRODUCT
132 virtual void dump_spec(outputStream *st) const;
133 #endif
134 };
135
136 //------------------------------Counted Loops----------------------------------
137 // Counted loops are all trip-counted loops, with exactly 1 trip-counter exit
138 // path (and maybe some other exit paths). The trip-counter exit is always
139 // last in the loop. The trip-counter have to stride by a constant;
140 // the exit value is also loop invariant.
141
142 // CountedLoopNodes and CountedLoopEndNodes come in matched pairs. The
143 // CountedLoopNode has the incoming loop control and the loop-back-control
144 // which is always the IfTrue before the matching CountedLoopEndNode. The
145 // CountedLoopEndNode has an incoming control (possibly not the
146 // CountedLoopNode if there is control flow in the loop), the post-increment
147 // trip-counter value, and the limit. The trip-counter value is always of
148 // the form (Op old-trip-counter stride). The old-trip-counter is produced
149 // by a Phi connected to the CountedLoopNode. The stride is constant.
150 // The Op is any commutable opcode, including Add, Mul, Xor. The
151 // CountedLoopEndNode also takes in the loop-invariant limit value.
152
153 // From a CountedLoopNode I can reach the matching CountedLoopEndNode via the
154 // loop-back control. From CountedLoopEndNodes I can reach CountedLoopNodes
155 // via the old-trip-counter from the Op node.
156
157 //------------------------------CountedLoopNode--------------------------------
158 // CountedLoopNodes head simple counted loops. CountedLoopNodes have as
159 // inputs the incoming loop-start control and the loop-back control, so they
160 // act like RegionNodes. They also take in the initial trip counter, the
161 // loop-invariant stride and the loop-invariant limit value. CountedLoopNodes
162 // produce a loop-body control and the trip counter value. Since
163 // CountedLoopNodes behave like RegionNodes I still have a standard CFG model.
164
165 class CountedLoopNode : public LoopNode {
166 // Size is bigger to hold _main_idx. However, _main_idx does not change
167 // the semantics so it does not appear in the hash & cmp functions.
168 virtual uint size_of() const { return sizeof(*this); }
169
170 // For Pre- and Post-loops during debugging ONLY, this holds the index of
171 // the Main CountedLoop. Used to assert that we understand the graph shape.
172 node_idx_t _main_idx;
173
174 // Known trip count calculated by compute_exact_trip_count()
175 uint _trip_count;
176
177 // Expected trip count from profile data
178 float _profile_trip_cnt;
179
180 // Log2 of original loop bodies in unrolled loop
181 int _unrolled_count_log2;
182
183 // Node count prior to last unrolling - used to decide if
184 // unroll,optimize,unroll,optimize,... is making progress
185 int _node_count_before_unroll;
186
187 // If slp analysis is performed we record the maximum
188 // vector mapped unroll factor here
189 int _slp_maximum_unroll_factor;
190
191 public:
192 CountedLoopNode( Node *entry, Node *backedge )
193 : LoopNode(entry, backedge), _main_idx(0), _trip_count(max_juint),
194 _profile_trip_cnt(COUNT_UNKNOWN), _unrolled_count_log2(0),
195 _node_count_before_unroll(0), _slp_maximum_unroll_factor(0) {
196 init_class_id(Class_CountedLoop);
197 // Initialize _trip_count to the largest possible value.
198 // Will be reset (lower) if the loop's trip count is known.
199 }
200
201 virtual int Opcode() const;
202 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
203
204 Node *init_control() const { return in(EntryControl); }
205 Node *back_control() const { return in(LoopBackControl); }
206 CountedLoopEndNode *loopexit() const;
207 Node *init_trip() const;
208 Node *stride() const;
209 int stride_con() const;
210 bool stride_is_con() const;
211 Node *limit() const;
212 Node *incr() const;
213 Node *phi() const;
214
215 // Match increment with optional truncation
216 static Node* match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type);
217
218 // A 'main' loop has a pre-loop and a post-loop. The 'main' loop
219 // can run short a few iterations and may start a few iterations in.
220 // It will be RCE'd and unrolled and aligned.
221
222 // A following 'post' loop will run any remaining iterations. Used
223 // during Range Check Elimination, the 'post' loop will do any final
224 // iterations with full checks. Also used by Loop Unrolling, where
225 // the 'post' loop will do any epilog iterations needed. Basically,
226 // a 'post' loop can not profitably be further unrolled or RCE'd.
227
228 // A preceding 'pre' loop will run at least 1 iteration (to do peeling),
229 // it may do under-flow checks for RCE and may do alignment iterations
230 // so the following main loop 'knows' that it is striding down cache
231 // lines.
232
233 // A 'main' loop that is ONLY unrolled or peeled, never RCE'd or
234 // Aligned, may be missing it's pre-loop.
235 int is_normal_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Normal; }
236 int is_pre_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Pre; }
237 int is_main_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Main; }
238 int is_post_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Post; }
239 int is_reduction_loop() const { return (_loop_flags&HasReductions) == HasReductions; }
240 int was_slp_analyzed () const { return (_loop_flags&WasSlpAnalyzed) == WasSlpAnalyzed; }
241 int has_passed_slp () const { return (_loop_flags&PassedSlpAnalysis) == PassedSlpAnalysis; }
242 int do_unroll_only () const { return (_loop_flags&DoUnrollOnly) == DoUnrollOnly; }
243 int is_main_no_pre_loop() const { return _loop_flags & MainHasNoPreLoop; }
244 int has_atomic_post_loop () const { return (_loop_flags & HasAtomicPostLoop) == HasAtomicPostLoop; }
245 void set_main_no_pre_loop() { _loop_flags |= MainHasNoPreLoop; }
246
247 int main_idx() const { return _main_idx; }
248
249
250 void set_pre_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; }
251 void set_main_loop ( ) { assert(is_normal_loop(),""); _loop_flags |= Main; }
252 void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; }
253 void set_normal_loop( ) { _loop_flags &= ~PreMainPostFlagsMask; }
254
255 void set_trip_count(uint tc) { _trip_count = tc; }
256 uint trip_count() { return _trip_count; }
257
258 bool has_exact_trip_count() const { return (_loop_flags & HasExactTripCount) != 0; }
259 void set_exact_trip_count(uint tc) {
260 _trip_count = tc;
261 _loop_flags |= HasExactTripCount;
262 }
263 void set_nonexact_trip_count() {
264 _loop_flags &= ~HasExactTripCount;
265 }
266 void set_notpassed_slp() {
267 _loop_flags &= ~PassedSlpAnalysis;
268 }
269
270 void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; }
271 float profile_trip_cnt() { return _profile_trip_cnt; }
272
273 void double_unrolled_count() { _unrolled_count_log2++; }
274 int unrolled_count() { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); }
275
276 void set_node_count_before_unroll(int ct) { _node_count_before_unroll = ct; }
277 int node_count_before_unroll() { return _node_count_before_unroll; }
278 void set_slp_max_unroll(int unroll_factor) { _slp_maximum_unroll_factor = unroll_factor; }
279 int slp_max_unroll() const { return _slp_maximum_unroll_factor; }
280
281 #ifndef PRODUCT
282 virtual void dump_spec(outputStream *st) const;
283 #endif
284 };
285
286 //------------------------------CountedLoopEndNode-----------------------------
287 // CountedLoopEndNodes end simple trip counted loops. They act much like
288 // IfNodes.
289 class CountedLoopEndNode : public IfNode {
290 public:
291 enum { TestControl, TestValue };
292
293 CountedLoopEndNode( Node *control, Node *test, float prob, float cnt )
294 : IfNode( control, test, prob, cnt) {
295 init_class_id(Class_CountedLoopEnd);
296 }
297 virtual int Opcode() const;
298
299 Node *cmp_node() const { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : NULL; }
300 Node *incr() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; }
301 Node *limit() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; }
302 Node *stride() const { Node *tmp = incr (); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; }
303 Node *init_trip() const { Node *tmp = phi (); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; }
304 int stride_con() const;
305 bool stride_is_con() const { Node *tmp = stride (); return (tmp != NULL && tmp->is_Con()); }
306 BoolTest::mask test_trip() const { return in(TestValue)->as_Bool()->_test._test; }
307 PhiNode *phi() const {
308 Node *tmp = incr();
309 if (tmp && tmp->req() == 3) {
310 Node* phi = tmp->in(1);
311 if (phi->is_Phi()) {
312 return phi->as_Phi();
313 }
314 }
315 return NULL;
316 }
317 CountedLoopNode *loopnode() const {
318 // The CountedLoopNode that goes with this CountedLoopEndNode may
319 // have been optimized out by the IGVN so be cautious with the
320 // pattern matching on the graph
321 PhiNode* iv_phi = phi();
322 if (iv_phi == NULL) {
323 return NULL;
324 }
325 Node *ln = iv_phi->in(0);
326 if (ln->is_CountedLoop() && ln->as_CountedLoop()->loopexit() == this) {
327 return (CountedLoopNode*)ln;
328 }
329 return NULL;
330 }
331
332 #ifndef PRODUCT
333 virtual void dump_spec(outputStream *st) const;
334 #endif
335 };
336
337
338 inline CountedLoopEndNode *CountedLoopNode::loopexit() const {
339 Node *bc = back_control();
340 if( bc == NULL ) return NULL;
341 Node *le = bc->in(0);
342 if( le->Opcode() != Op_CountedLoopEnd )
343 return NULL;
344 return (CountedLoopEndNode*)le;
345 }
346 inline Node *CountedLoopNode::init_trip() const { return loopexit() ? loopexit()->init_trip() : NULL; }
347 inline Node *CountedLoopNode::stride() const { return loopexit() ? loopexit()->stride() : NULL; }
348 inline int CountedLoopNode::stride_con() const { return loopexit() ? loopexit()->stride_con() : 0; }
349 inline bool CountedLoopNode::stride_is_con() const { return loopexit() && loopexit()->stride_is_con(); }
350 inline Node *CountedLoopNode::limit() const { return loopexit() ? loopexit()->limit() : NULL; }
351 inline Node *CountedLoopNode::incr() const { return loopexit() ? loopexit()->incr() : NULL; }
352 inline Node *CountedLoopNode::phi() const { return loopexit() ? loopexit()->phi() : NULL; }
353
354 //------------------------------LoopLimitNode-----------------------------
355 // Counted Loop limit node which represents exact final iterator value:
356 // trip_count = (limit - init_trip + stride - 1)/stride
357 // final_value= trip_count * stride + init_trip.
358 // Use HW instructions to calculate it when it can overflow in integer.
359 // Note, final_value should fit into integer since counted loop has
360 // limit check: limit <= max_int-stride.
361 class LoopLimitNode : public Node {
362 enum { Init=1, Limit=2, Stride=3 };
363 public:
364 LoopLimitNode( Compile* C, Node *init, Node *limit, Node *stride ) : Node(0,init,limit,stride) {
365 // Put it on the Macro nodes list to optimize during macro nodes expansion.
366 init_flags(Flag_is_macro);
367 C->add_macro_node(this);
368 }
369 virtual int Opcode() const;
370 virtual const Type *bottom_type() const { return TypeInt::INT; }
371 virtual uint ideal_reg() const { return Op_RegI; }
372 virtual const Type* Value(PhaseGVN* phase) const;
373 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
374 virtual Node* Identity(PhaseGVN* phase);
375 };
376
377 // -----------------------------IdealLoopTree----------------------------------
378 class IdealLoopTree : public ResourceObj {
379 public:
380 IdealLoopTree *_parent; // Parent in loop tree
381 IdealLoopTree *_next; // Next sibling in loop tree
382 IdealLoopTree *_child; // First child in loop tree
383
384 // The head-tail backedge defines the loop.
385 // If tail is NULL then this loop has multiple backedges as part of the
386 // same loop. During cleanup I'll peel off the multiple backedges; merge
387 // them at the loop bottom and flow 1 real backedge into the loop.
388 Node *_head; // Head of loop
389 Node *_tail; // Tail of loop
390 inline Node *tail(); // Handle lazy update of _tail field
391 PhaseIdealLoop* _phase;
392 int _local_loop_unroll_limit;
393 int _local_loop_unroll_factor;
394
395 Node_List _body; // Loop body for inner loops
396
397 uint8_t _nest; // Nesting depth
398 uint8_t _irreducible:1, // True if irreducible
399 _has_call:1, // True if has call safepoint
400 _has_sfpt:1, // True if has non-call safepoint
401 _rce_candidate:1; // True if candidate for range check elimination
402
403 Node_List* _safepts; // List of safepoints in this loop
404 Node_List* _required_safept; // A inner loop cannot delete these safepts;
405 bool _allow_optimizations; // Allow loop optimizations
406
407 IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail )
408 : _parent(0), _next(0), _child(0),
409 _head(head), _tail(tail),
410 _phase(phase),
411 _safepts(NULL),
412 _required_safept(NULL),
413 _allow_optimizations(true),
414 _nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0),
415 _local_loop_unroll_limit(0), _local_loop_unroll_factor(0)
416 { }
417
418 // Is 'l' a member of 'this'?
419 bool is_member(const IdealLoopTree *l) const; // Test for nested membership
420
421 // Set loop nesting depth. Accumulate has_call bits.
422 int set_nest( uint depth );
423
424 // Split out multiple fall-in edges from the loop header. Move them to a
425 // private RegionNode before the loop. This becomes the loop landing pad.
426 void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt );
427
428 // Split out the outermost loop from this shared header.
429 void split_outer_loop( PhaseIdealLoop *phase );
430
431 // Merge all the backedges from the shared header into a private Region.
432 // Feed that region as the one backedge to this loop.
433 void merge_many_backedges( PhaseIdealLoop *phase );
434
435 // Split shared headers and insert loop landing pads.
436 // Insert a LoopNode to replace the RegionNode.
437 // Returns TRUE if loop tree is structurally changed.
438 bool beautify_loops( PhaseIdealLoop *phase );
439
440 // Perform optimization to use the loop predicates for null checks and range checks.
441 // Applies to any loop level (not just the innermost one)
442 bool loop_predication( PhaseIdealLoop *phase);
443
444 // Perform iteration-splitting on inner loops. Split iterations to
445 // avoid range checks or one-shot null checks. Returns false if the
446 // current round of loop opts should stop.
447 bool iteration_split( PhaseIdealLoop *phase, Node_List &old_new );
448
449 // Driver for various flavors of iteration splitting. Returns false
450 // if the current round of loop opts should stop.
451 bool iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new );
452
453 // Given dominators, try to find loops with calls that must always be
454 // executed (call dominates loop tail). These loops do not need non-call
455 // safepoints (ncsfpt).
456 void check_safepts(VectorSet &visited, Node_List &stack);
457
458 // Allpaths backwards scan from loop tail, terminating each path at first safepoint
459 // encountered.
460 void allpaths_check_safepts(VectorSet &visited, Node_List &stack);
461
462 // Remove safepoints from loop. Optionally keeping one.
463 void remove_safepoints(PhaseIdealLoop* phase, bool keep_one);
464
465 // Convert to counted loops where possible
466 void counted_loop( PhaseIdealLoop *phase );
467
468 // Check for Node being a loop-breaking test
469 Node *is_loop_exit(Node *iff) const;
470
471 // Remove simplistic dead code from loop body
472 void DCE_loop_body();
473
474 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage.
475 // Replace with a 1-in-10 exit guess.
476 void adjust_loop_exit_prob( PhaseIdealLoop *phase );
477
478 // Return TRUE or FALSE if the loop should never be RCE'd or aligned.
479 // Useful for unrolling loops with NO array accesses.
480 bool policy_peel_only( PhaseIdealLoop *phase ) const;
481
482 // Return TRUE or FALSE if the loop should be unswitched -- clone
483 // loop with an invariant test
484 bool policy_unswitching( PhaseIdealLoop *phase ) const;
485
486 // Micro-benchmark spamming. Remove empty loops.
487 bool policy_do_remove_empty_loop( PhaseIdealLoop *phase );
488
489 // Convert one iteration loop into normal code.
490 bool policy_do_one_iteration_loop( PhaseIdealLoop *phase );
491
492 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can
493 // make some loop-invariant test (usually a null-check) happen before the
494 // loop.
495 bool policy_peeling( PhaseIdealLoop *phase ) const;
496
497 // Return TRUE or FALSE if the loop should be maximally unrolled. Stash any
498 // known trip count in the counted loop node.
499 bool policy_maximally_unroll( PhaseIdealLoop *phase ) const;
500
501 // Return TRUE or FALSE if the loop should be unrolled or not. Unroll if
502 // the loop is a CountedLoop and the body is small enough.
503 bool policy_unroll(PhaseIdealLoop *phase);
504
505 // Loop analyses to map to a maximal superword unrolling for vectorization.
506 void policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_ct);
507
508 // Return TRUE or FALSE if the loop should be range-check-eliminated.
509 // Gather a list of IF tests that are dominated by iteration splitting;
510 // also gather the end of the first split and the start of the 2nd split.
511 bool policy_range_check( PhaseIdealLoop *phase ) const;
512
513 // Return TRUE or FALSE if the loop should be cache-line aligned.
514 // Gather the expression that does the alignment. Note that only
515 // one array base can be aligned in a loop (unless the VM guarantees
516 // mutual alignment). Note that if we vectorize short memory ops
517 // into longer memory ops, we may want to increase alignment.
518 bool policy_align( PhaseIdealLoop *phase ) const;
519
520 // Return TRUE if "iff" is a range check.
521 bool is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const;
522
523 // Compute loop exact trip count if possible
524 void compute_exact_trip_count( PhaseIdealLoop *phase );
525
526 // Compute loop trip count from profile data
527 void compute_profile_trip_cnt( PhaseIdealLoop *phase );
528
529 // Reassociate invariant expressions.
530 void reassociate_invariants(PhaseIdealLoop *phase);
531 // Reassociate invariant add and subtract expressions.
532 Node* reassociate_add_sub(Node* n1, PhaseIdealLoop *phase);
533 // Return nonzero index of invariant operand if invariant and variant
534 // are combined with an Add or Sub. Helper for reassociate_invariants.
535 int is_invariant_addition(Node* n, PhaseIdealLoop *phase);
536
537 // Return true if n is invariant
538 bool is_invariant(Node* n) const;
539
540 // Put loop body on igvn work list
541 void record_for_igvn();
542
543 bool is_loop() { return !_irreducible && _tail && !_tail->is_top(); }
544 bool is_inner() { return is_loop() && _child == NULL; }
545 bool is_counted() { return is_loop() && _head != NULL && _head->is_CountedLoop(); }
546
547 void remove_main_post_loops(CountedLoopNode *cl, PhaseIdealLoop *phase);
548
549 #ifndef PRODUCT
550 void dump_head( ) const; // Dump loop head only
551 void dump() const; // Dump this loop recursively
552 void verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const;
553 #endif
554
555 };
556
557 // -----------------------------PhaseIdealLoop---------------------------------
558 // Computes the mapping from Nodes to IdealLoopTrees. Organizes IdealLoopTrees into a
559 // loop tree. Drives the loop-based transformations on the ideal graph.
560 class PhaseIdealLoop : public PhaseTransform {
561 friend class IdealLoopTree;
562 friend class SuperWord;
563 friend class CountedLoopReserveKit;
564
565 // Pre-computed def-use info
566 PhaseIterGVN &_igvn;
567
568 // Head of loop tree
569 IdealLoopTree *_ltree_root;
570
571 // Array of pre-order numbers, plus post-visited bit.
572 // ZERO for not pre-visited. EVEN for pre-visited but not post-visited.
573 // ODD for post-visited. Other bits are the pre-order number.
574 uint *_preorders;
575 uint _max_preorder;
576
577 const PhaseIdealLoop* _verify_me;
578 bool _verify_only;
579
580 // Allocate _preorders[] array
581 void allocate_preorders() {
582 _max_preorder = C->unique()+8;
583 _preorders = NEW_RESOURCE_ARRAY(uint, _max_preorder);
584 memset(_preorders, 0, sizeof(uint) * _max_preorder);
585 }
586
587 // Allocate _preorders[] array
588 void reallocate_preorders() {
589 if ( _max_preorder < C->unique() ) {
590 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique());
591 _max_preorder = C->unique();
592 }
593 memset(_preorders, 0, sizeof(uint) * _max_preorder);
594 }
595
596 // Check to grow _preorders[] array for the case when build_loop_tree_impl()
597 // adds new nodes.
598 void check_grow_preorders( ) {
599 if ( _max_preorder < C->unique() ) {
600 uint newsize = _max_preorder<<1; // double size of array
601 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize);
602 memset(&_preorders[_max_preorder],0,sizeof(uint)*(newsize-_max_preorder));
603 _max_preorder = newsize;
604 }
605 }
606 // Check for pre-visited. Zero for NOT visited; non-zero for visited.
607 int is_visited( Node *n ) const { return _preorders[n->_idx]; }
608 // Pre-order numbers are written to the Nodes array as low-bit-set values.
609 void set_preorder_visited( Node *n, int pre_order ) {
610 assert( !is_visited( n ), "already set" );
611 _preorders[n->_idx] = (pre_order<<1);
612 };
613 // Return pre-order number.
614 int get_preorder( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]>>1; }
615
616 // Check for being post-visited.
617 // Should be previsited already (checked with assert(is_visited(n))).
618 int is_postvisited( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]&1; }
619
620 // Mark as post visited
621 void set_postvisited( Node *n ) { assert( !is_postvisited( n ), "" ); _preorders[n->_idx] |= 1; }
622
623 // Set/get control node out. Set lower bit to distinguish from IdealLoopTree
624 // Returns true if "n" is a data node, false if it's a control node.
625 bool has_ctrl( Node *n ) const { return ((intptr_t)_nodes[n->_idx]) & 1; }
626
627 // clear out dead code after build_loop_late
628 Node_List _deadlist;
629
630 // Support for faster execution of get_late_ctrl()/dom_lca()
631 // when a node has many uses and dominator depth is deep.
632 Node_Array _dom_lca_tags;
633 void init_dom_lca_tags();
634 void clear_dom_lca_tags();
635
636 // Helper for debugging bad dominance relationships
637 bool verify_dominance(Node* n, Node* use, Node* LCA, Node* early);
638
639 Node* compute_lca_of_uses(Node* n, Node* early, bool verify = false);
640
641 // Inline wrapper for frequent cases:
642 // 1) only one use
643 // 2) a use is the same as the current LCA passed as 'n1'
644 Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) {
645 assert( n->is_CFG(), "" );
646 // Fast-path NULL lca
647 if( lca != NULL && lca != n ) {
648 assert( lca->is_CFG(), "" );
649 // find LCA of all uses
650 n = dom_lca_for_get_late_ctrl_internal( lca, n, tag );
651 }
652 return find_non_split_ctrl(n);
653 }
654 Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag );
655
656 // Helper function for directing control inputs away from CFG split
657 // points.
658 Node *find_non_split_ctrl( Node *ctrl ) const {
659 if (ctrl != NULL) {
660 if (ctrl->is_MultiBranch()) {
661 ctrl = ctrl->in(0);
662 }
663 assert(ctrl->is_CFG(), "CFG");
664 }
665 return ctrl;
666 }
667
668 bool cast_incr_before_loop(Node* incr, Node* ctrl, Node* loop);
669
670 public:
671
672 static bool is_canonical_loop_entry(CountedLoopNode* cl);
673
674 bool has_node( Node* n ) const {
675 guarantee(n != NULL, "No Node.");
676 return _nodes[n->_idx] != NULL;
677 }
678 // check if transform created new nodes that need _ctrl recorded
679 Node *get_late_ctrl( Node *n, Node *early );
680 Node *get_early_ctrl( Node *n );
681 Node *get_early_ctrl_for_expensive(Node *n, Node* earliest);
682 void set_early_ctrl( Node *n );
683 void set_subtree_ctrl( Node *root );
684 void set_ctrl( Node *n, Node *ctrl ) {
685 assert( !has_node(n) || has_ctrl(n), "" );
686 assert( ctrl->in(0), "cannot set dead control node" );
687 assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" );
688 _nodes.map( n->_idx, (Node*)((intptr_t)ctrl + 1) );
689 }
690 // Set control and update loop membership
691 void set_ctrl_and_loop(Node* n, Node* ctrl) {
692 IdealLoopTree* old_loop = get_loop(get_ctrl(n));
693 IdealLoopTree* new_loop = get_loop(ctrl);
694 if (old_loop != new_loop) {
695 if (old_loop->_child == NULL) old_loop->_body.yank(n);
696 if (new_loop->_child == NULL) new_loop->_body.push(n);
697 }
698 set_ctrl(n, ctrl);
699 }
700 // Control nodes can be replaced or subsumed. During this pass they
701 // get their replacement Node in slot 1. Instead of updating the block
702 // location of all Nodes in the subsumed block, we lazily do it. As we
703 // pull such a subsumed block out of the array, we write back the final
704 // correct block.
705 Node *get_ctrl( Node *i ) {
706 assert(has_node(i), "");
707 Node *n = get_ctrl_no_update(i);
708 _nodes.map( i->_idx, (Node*)((intptr_t)n + 1) );
709 assert(has_node(i) && has_ctrl(i), "");
710 assert(n == find_non_split_ctrl(n), "must return legal ctrl" );
711 return n;
712 }
713 // true if CFG node d dominates CFG node n
714 bool is_dominator(Node *d, Node *n);
715 // return get_ctrl for a data node and self(n) for a CFG node
716 Node* ctrl_or_self(Node* n) {
717 if (has_ctrl(n))
718 return get_ctrl(n);
719 else {
720 assert (n->is_CFG(), "must be a CFG node");
721 return n;
722 }
723 }
724
725 private:
726 Node *get_ctrl_no_update_helper(Node *i) const {
727 assert(has_ctrl(i), "should be control, not loop");
728 return (Node*)(((intptr_t)_nodes[i->_idx]) & ~1);
729 }
730
731 Node *get_ctrl_no_update(Node *i) const {
732 assert( has_ctrl(i), "" );
733 Node *n = get_ctrl_no_update_helper(i);
734 if (!n->in(0)) {
735 // Skip dead CFG nodes
736 do {
737 n = get_ctrl_no_update_helper(n);
738 } while (!n->in(0));
739 n = find_non_split_ctrl(n);
740 }
741 return n;
742 }
743
744 // Check for loop being set
745 // "n" must be a control node. Returns true if "n" is known to be in a loop.
746 bool has_loop( Node *n ) const {
747 assert(!has_node(n) || !has_ctrl(n), "");
748 return has_node(n);
749 }
750 // Set loop
751 void set_loop( Node *n, IdealLoopTree *loop ) {
752 _nodes.map(n->_idx, (Node*)loop);
753 }
754 // Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms. Replace
755 // the 'old_node' with 'new_node'. Kill old-node. Add a reference
756 // from old_node to new_node to support the lazy update. Reference
757 // replaces loop reference, since that is not needed for dead node.
758 public:
759 void lazy_update(Node *old_node, Node *new_node) {
760 assert(old_node != new_node, "no cycles please");
761 // Re-use the side array slot for this node to provide the
762 // forwarding pointer.
763 _nodes.map(old_node->_idx, (Node*)((intptr_t)new_node + 1));
764 }
765 void lazy_replace(Node *old_node, Node *new_node) {
766 _igvn.replace_node(old_node, new_node);
767 lazy_update(old_node, new_node);
768 }
769
770 private:
771
772 // Place 'n' in some loop nest, where 'n' is a CFG node
773 void build_loop_tree();
774 int build_loop_tree_impl( Node *n, int pre_order );
775 // Insert loop into the existing loop tree. 'innermost' is a leaf of the
776 // loop tree, not the root.
777 IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost );
778
779 // Place Data nodes in some loop nest
780 void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
781 void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
782 void build_loop_late_post ( Node* n );
783
784 // Array of immediate dominance info for each CFG node indexed by node idx
785 private:
786 uint _idom_size;
787 Node **_idom; // Array of immediate dominators
788 uint *_dom_depth; // Used for fast LCA test
789 GrowableArray<uint>* _dom_stk; // For recomputation of dom depth
790
791 Node* idom_no_update(Node* d) const {
792 assert(d->_idx < _idom_size, "oob");
793 Node* n = _idom[d->_idx];
794 assert(n != NULL,"Bad immediate dominator info.");
795 while (n->in(0) == NULL) { // Skip dead CFG nodes
796 //n = n->in(1);
797 n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1);
798 assert(n != NULL,"Bad immediate dominator info.");
799 }
800 return n;
801 }
802 Node *idom(Node* d) const {
803 uint didx = d->_idx;
804 Node *n = idom_no_update(d);
805 _idom[didx] = n; // Lazily remove dead CFG nodes from table.
806 return n;
807 }
808 uint dom_depth(Node* d) const {
809 guarantee(d != NULL, "Null dominator info.");
810 guarantee(d->_idx < _idom_size, "");
811 return _dom_depth[d->_idx];
812 }
813 void set_idom(Node* d, Node* n, uint dom_depth);
814 // Locally compute IDOM using dom_lca call
815 Node *compute_idom( Node *region ) const;
816 // Recompute dom_depth
817 void recompute_dom_depth();
818
819 // Is safept not required by an outer loop?
820 bool is_deleteable_safept(Node* sfpt);
821
822 // Replace parallel induction variable (parallel to trip counter)
823 void replace_parallel_iv(IdealLoopTree *loop);
824
825 // Perform verification that the graph is valid.
826 PhaseIdealLoop( PhaseIterGVN &igvn) :
827 PhaseTransform(Ideal_Loop),
828 _igvn(igvn),
829 _dom_lca_tags(arena()), // Thread::resource_area
830 _verify_me(NULL),
831 _verify_only(true) {
832 build_and_optimize(false, false);
833 }
834
835 // build the loop tree and perform any requested optimizations
836 void build_and_optimize(bool do_split_if, bool skip_loop_opts);
837
838 public:
839 // Dominators for the sea of nodes
840 void Dominators();
841 Node *dom_lca( Node *n1, Node *n2 ) const {
842 return find_non_split_ctrl(dom_lca_internal(n1, n2));
843 }
844 Node *dom_lca_internal( Node *n1, Node *n2 ) const;
845
846 // Compute the Ideal Node to Loop mapping
847 PhaseIdealLoop( PhaseIterGVN &igvn, bool do_split_ifs, bool skip_loop_opts = false) :
848 PhaseTransform(Ideal_Loop),
849 _igvn(igvn),
850 _dom_lca_tags(arena()), // Thread::resource_area
851 _verify_me(NULL),
852 _verify_only(false) {
853 build_and_optimize(do_split_ifs, skip_loop_opts);
854 }
855
856 // Verify that verify_me made the same decisions as a fresh run.
857 PhaseIdealLoop( PhaseIterGVN &igvn, const PhaseIdealLoop *verify_me) :
858 PhaseTransform(Ideal_Loop),
859 _igvn(igvn),
860 _dom_lca_tags(arena()), // Thread::resource_area
861 _verify_me(verify_me),
862 _verify_only(false) {
863 build_and_optimize(false, false);
864 }
865
866 // Build and verify the loop tree without modifying the graph. This
867 // is useful to verify that all inputs properly dominate their uses.
868 static void verify(PhaseIterGVN& igvn) {
869 #ifdef ASSERT
870 PhaseIdealLoop v(igvn);
871 #endif
872 }
873
874 // True if the method has at least 1 irreducible loop
875 bool _has_irreducible_loops;
876
877 // Per-Node transform
878 virtual Node *transform( Node *a_node ) { return 0; }
879
880 bool is_counted_loop( Node *x, IdealLoopTree *loop );
881
882 Node* exact_limit( IdealLoopTree *loop );
883
884 // Return a post-walked LoopNode
885 IdealLoopTree *get_loop( Node *n ) const {
886 // Dead nodes have no loop, so return the top level loop instead
887 if (!has_node(n)) return _ltree_root;
888 assert(!has_ctrl(n), "");
889 return (IdealLoopTree*)_nodes[n->_idx];
890 }
891
892 // Is 'n' a (nested) member of 'loop'?
893 int is_member( const IdealLoopTree *loop, Node *n ) const {
894 return loop->is_member(get_loop(n)); }
895
896 // This is the basic building block of the loop optimizations. It clones an
897 // entire loop body. It makes an old_new loop body mapping; with this
898 // mapping you can find the new-loop equivalent to an old-loop node. All
899 // new-loop nodes are exactly equal to their old-loop counterparts, all
900 // edges are the same. All exits from the old-loop now have a RegionNode
901 // that merges the equivalent new-loop path. This is true even for the
902 // normal "loop-exit" condition. All uses of loop-invariant old-loop values
903 // now come from (one or more) Phis that merge their new-loop equivalents.
904 // Parameter side_by_side_idom:
905 // When side_by_size_idom is NULL, the dominator tree is constructed for
906 // the clone loop to dominate the original. Used in construction of
907 // pre-main-post loop sequence.
908 // When nonnull, the clone and original are side-by-side, both are
909 // dominated by the passed in side_by_side_idom node. Used in
910 // construction of unswitched loops.
911 void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth,
912 Node* side_by_side_idom = NULL);
913
914 // If we got the effect of peeling, either by actually peeling or by
915 // making a pre-loop which must execute at least once, we can remove
916 // all loop-invariant dominated tests in the main body.
917 void peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new );
918
919 // Generate code to do a loop peel for the given loop (and body).
920 // old_new is a temp array.
921 void do_peeling( IdealLoopTree *loop, Node_List &old_new );
922
923 // Add pre and post loops around the given loop. These loops are used
924 // during RCE, unrolling and aligning loops.
925 void insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only );
926
927 // Add post loop after the given loop.
928 Node *insert_post_loop(IdealLoopTree *loop, Node_List &old_new,
929 CountedLoopNode *main_head, CountedLoopEndNode *main_end,
930 Node *incr, Node *limit, CountedLoopNode *&post_head);
931
932 // Add an RCE'd post loop which we will multi-version adapt for run time test path usage
933 void insert_scalar_rced_post_loop( IdealLoopTree *loop, Node_List &old_new );
934
935 // Add a vector post loop between a vector main loop and the current post loop
936 void insert_vector_post_loop(IdealLoopTree *loop, Node_List &old_new);
937 // If Node n lives in the back_ctrl block, we clone a private version of n
938 // in preheader_ctrl block and return that, otherwise return n.
939 Node *clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones );
940
941 // Take steps to maximally unroll the loop. Peel any odd iterations, then
942 // unroll to do double iterations. The next round of major loop transforms
943 // will repeat till the doubled loop body does all remaining iterations in 1
944 // pass.
945 void do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new );
946
947 // Unroll the loop body one step - make each trip do 2 iterations.
948 void do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip );
949
950 // Mark vector reduction candidates before loop unrolling
951 void mark_reductions( IdealLoopTree *loop );
952
953 // Return true if exp is a constant times an induction var
954 bool is_scaled_iv(Node* exp, Node* iv, int* p_scale);
955
956 // Return true if exp is a scaled induction var plus (or minus) constant
957 bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth = 0);
958
959 // Create a new if above the uncommon_trap_if_pattern for the predicate to be promoted
960 ProjNode* create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry,
961 Deoptimization::DeoptReason reason,
962 int opcode);
963 void register_control(Node* n, IdealLoopTree *loop, Node* pred);
964
965 // Clone loop predicates to cloned loops (peeled, unswitched)
966 static ProjNode* clone_predicate(ProjNode* predicate_proj, Node* new_entry,
967 Deoptimization::DeoptReason reason,
968 PhaseIdealLoop* loop_phase,
969 PhaseIterGVN* igvn);
970
971 static Node* clone_loop_predicates(Node* old_entry, Node* new_entry,
972 bool clone_limit_check,
973 PhaseIdealLoop* loop_phase,
974 PhaseIterGVN* igvn);
975 Node* clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check);
976
977 static Node* skip_loop_predicates(Node* entry);
978
979 // Find a good location to insert a predicate
980 static ProjNode* find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason);
981 // Find a predicate
982 static Node* find_predicate(Node* entry);
983 // Construct a range check for a predicate if
984 BoolNode* rc_predicate(IdealLoopTree *loop, Node* ctrl,
985 int scale, Node* offset,
986 Node* init, Node* limit, Node* stride,
987 Node* range, bool upper);
988
989 // Implementation of the loop predication to promote checks outside the loop
990 bool loop_predication_impl(IdealLoopTree *loop);
991
992 // Helper function to collect predicate for eliminating the useless ones
993 void collect_potentially_useful_predicates(IdealLoopTree *loop, Unique_Node_List &predicate_opaque1);
994 void eliminate_useless_predicates();
995
996 // Change the control input of expensive nodes to allow commoning by
997 // IGVN when it is guaranteed to not result in a more frequent
998 // execution of the expensive node. Return true if progress.
999 bool process_expensive_nodes();
1000
1001 // Check whether node has become unreachable
1002 bool is_node_unreachable(Node *n) const {
1003 return !has_node(n) || n->is_unreachable(_igvn);
1004 }
1005
1006 // Eliminate range-checks and other trip-counter vs loop-invariant tests.
1007 int do_range_check( IdealLoopTree *loop, Node_List &old_new );
1008
1009 // Check to see if do_range_check(...) cleaned the main loop of range-checks
1010 void has_range_checks(IdealLoopTree *loop);
1011
1012 // Process post loops which have range checks and try to build a multi-version
1013 // guard to safely determine if we can execute the post loop which was RCE'd.
1014 bool multi_version_post_loops(IdealLoopTree *rce_loop, IdealLoopTree *legacy_loop);
1015
1016 // Cause the rce'd post loop to optimized away, this happens if we cannot complete multiverioning
1017 void poison_rce_post_loop(IdealLoopTree *rce_loop);
1018
1019 // Create a slow version of the loop by cloning the loop
1020 // and inserting an if to select fast-slow versions.
1021 ProjNode* create_slow_version_of_loop(IdealLoopTree *loop,
1022 Node_List &old_new,
1023 int opcode);
1024
1025 // Clone a loop and return the clone head (clone_loop_head).
1026 // Added nodes include int(1), int(0) - disconnected, If, IfTrue, IfFalse,
1027 // This routine was created for usage in CountedLoopReserveKit.
1028 //
1029 // int(1) -> If -> IfTrue -> original_loop_head
1030 // |
1031 // V
1032 // IfFalse -> clone_loop_head (returned by function pointer)
1033 //
1034 LoopNode* create_reserve_version_of_loop(IdealLoopTree *loop, CountedLoopReserveKit* lk);
1035 // Clone loop with an invariant test (that does not exit) and
1036 // insert a clone of the test that selects which version to
1037 // execute.
1038 void do_unswitching (IdealLoopTree *loop, Node_List &old_new);
1039
1040 // Find candidate "if" for unswitching
1041 IfNode* find_unswitching_candidate(const IdealLoopTree *loop) const;
1042
1043 // Range Check Elimination uses this function!
1044 // Constrain the main loop iterations so the affine function:
1045 // low_limit <= scale_con * I + offset < upper_limit
1046 // always holds true. That is, either increase the number of iterations in
1047 // the pre-loop or the post-loop until the condition holds true in the main
1048 // loop. Scale_con, offset and limit are all loop invariant.
1049 void add_constraint( int stride_con, int scale_con, Node *offset, Node *low_limit, Node *upper_limit, Node *pre_ctrl, Node **pre_limit, Node **main_limit );
1050 // Helper function for add_constraint().
1051 Node* adjust_limit( int stride_con, Node * scale, Node *offset, Node *rc_limit, Node *loop_limit, Node *pre_ctrl );
1052
1053 // Partially peel loop up through last_peel node.
1054 bool partial_peel( IdealLoopTree *loop, Node_List &old_new );
1055
1056 // Create a scheduled list of nodes control dependent on ctrl set.
1057 void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched );
1058 // Has a use in the vector set
1059 bool has_use_in_set( Node* n, VectorSet& vset );
1060 // Has use internal to the vector set (ie. not in a phi at the loop head)
1061 bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop );
1062 // clone "n" for uses that are outside of loop
1063 int clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist );
1064 // clone "n" for special uses that are in the not_peeled region
1065 void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
1066 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist );
1067 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
1068 void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp );
1069 #ifdef ASSERT
1070 // Validate the loop partition sets: peel and not_peel
1071 bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel );
1072 // Ensure that uses outside of loop are of the right form
1073 bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
1074 uint orig_exit_idx, uint clone_exit_idx);
1075 bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx);
1076 #endif
1077
1078 // Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.)
1079 int stride_of_possible_iv( Node* iff );
1080 bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; }
1081 // Return the (unique) control output node that's in the loop (if it exists.)
1082 Node* stay_in_loop( Node* n, IdealLoopTree *loop);
1083 // Insert a signed compare loop exit cloned from an unsigned compare.
1084 IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop);
1085 void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop);
1086 // Utility to register node "n" with PhaseIdealLoop
1087 void register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth);
1088 // Utility to create an if-projection
1089 ProjNode* proj_clone(ProjNode* p, IfNode* iff);
1090 // Force the iff control output to be the live_proj
1091 Node* short_circuit_if(IfNode* iff, ProjNode* live_proj);
1092 // Insert a region before an if projection
1093 RegionNode* insert_region_before_proj(ProjNode* proj);
1094 // Insert a new if before an if projection
1095 ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj);
1096
1097 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1098 // "Nearly" because all Nodes have been cloned from the original in the loop,
1099 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1100 // through the Phi recursively, and return a Bool.
1101 BoolNode *clone_iff( PhiNode *phi, IdealLoopTree *loop );
1102 CmpNode *clone_bool( PhiNode *phi, IdealLoopTree *loop );
1103
1104
1105 // Rework addressing expressions to get the most loop-invariant stuff
1106 // moved out. We'd like to do all associative operators, but it's especially
1107 // important (common) to do address expressions.
1108 Node *remix_address_expressions( Node *n );
1109
1110 // Attempt to use a conditional move instead of a phi/branch
1111 Node *conditional_move( Node *n );
1112
1113 // Reorganize offset computations to lower register pressure.
1114 // Mostly prevent loop-fallout uses of the pre-incremented trip counter
1115 // (which are then alive with the post-incremented trip counter
1116 // forcing an extra register move)
1117 void reorg_offsets( IdealLoopTree *loop );
1118
1119 // Check for aggressive application of 'split-if' optimization,
1120 // using basic block level info.
1121 void split_if_with_blocks ( VectorSet &visited, Node_Stack &nstack );
1122 Node *split_if_with_blocks_pre ( Node *n );
1123 void split_if_with_blocks_post( Node *n );
1124 Node *has_local_phi_input( Node *n );
1125 // Mark an IfNode as being dominated by a prior test,
1126 // without actually altering the CFG (and hence IDOM info).
1127 void dominated_by( Node *prevdom, Node *iff, bool flip = false, bool exclude_loop_predicate = false );
1128
1129 // Split Node 'n' through merge point
1130 Node *split_thru_region( Node *n, Node *region );
1131 // Split Node 'n' through merge point if there is enough win.
1132 Node *split_thru_phi( Node *n, Node *region, int policy );
1133 // Found an If getting its condition-code input from a Phi in the
1134 // same block. Split thru the Region.
1135 void do_split_if( Node *iff );
1136
1137 // Conversion of fill/copy patterns into intrisic versions
1138 bool do_intrinsify_fill();
1139 bool intrinsify_fill(IdealLoopTree* lpt);
1140 bool match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value,
1141 Node*& shift, Node*& offset);
1142
1143 private:
1144 // Return a type based on condition control flow
1145 const TypeInt* filtered_type( Node *n, Node* n_ctrl);
1146 const TypeInt* filtered_type( Node *n ) { return filtered_type(n, NULL); }
1147 // Helpers for filtered type
1148 const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl);
1149
1150 // Helper functions
1151 Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache );
1152 Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true );
1153 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 );
1154 bool split_up( Node *n, Node *blk1, Node *blk2 );
1155 void sink_use( Node *use, Node *post_loop );
1156 Node *place_near_use( Node *useblock ) const;
1157 Node* try_move_store_before_loop(Node* n, Node *n_ctrl);
1158 void try_move_store_after_loop(Node* n);
1159 bool identical_backtoback_ifs(Node *n);
1160 bool can_split_if(Node *n_ctrl);
1161
1162 bool _created_loop_node;
1163 public:
1164 void set_created_loop_node() { _created_loop_node = true; }
1165 bool created_loop_node() { return _created_loop_node; }
1166 void register_new_node( Node *n, Node *blk );
1167
1168 #ifdef ASSERT
1169 void dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA);
1170 #endif
1171
1172 #ifndef PRODUCT
1173 void dump( ) const;
1174 void dump( IdealLoopTree *loop, uint rpo_idx, Node_List &rpo_list ) const;
1175 void rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const;
1176 void verify() const; // Major slow :-)
1177 void verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const;
1178 IdealLoopTree *get_loop_idx(Node* n) const {
1179 // Dead nodes have no loop, so return the top level loop instead
1180 return _nodes[n->_idx] ? (IdealLoopTree*)_nodes[n->_idx] : _ltree_root;
1181 }
1182 // Print some stats
1183 static void print_statistics();
1184 static int _loop_invokes; // Count of PhaseIdealLoop invokes
1185 static int _loop_work; // Sum of PhaseIdealLoop x _unique
1186 #endif
1187 };
1188
1189 // This kit may be used for making of a reserved copy of a loop before this loop
1190 // goes under non-reversible changes.
1191 //
1192 // Function create_reserve() creates a reserved copy (clone) of the loop.
1193 // The reserved copy is created by calling
1194 // PhaseIdealLoop::create_reserve_version_of_loop - see there how
1195 // the original and reserved loops are connected in the outer graph.
1196 // If create_reserve succeeded, it returns 'true' and _has_reserved is set to 'true'.
1197 //
1198 // By default the reserved copy (clone) of the loop is created as dead code - it is
1199 // dominated in the outer loop by this node chain:
1200 // intcon(1)->If->IfFalse->reserved_copy.
1201 // The original loop is dominated by the the same node chain but IfTrue projection:
1202 // intcon(0)->If->IfTrue->original_loop.
1203 //
1204 // In this implementation of CountedLoopReserveKit the ctor includes create_reserve()
1205 // and the dtor, checks _use_new value.
1206 // If _use_new == false, it "switches" control to reserved copy of the loop
1207 // by simple replacing of node intcon(1) with node intcon(0).
1208 //
1209 // Here is a proposed example of usage (see also SuperWord::output in superword.cpp).
1210 //
1211 // void CountedLoopReserveKit_example()
1212 // {
1213 // CountedLoopReserveKit lrk((phase, lpt, DoReserveCopy = true); // create local object
1214 // if (DoReserveCopy && !lrk.has_reserved()) {
1215 // return; //failed to create reserved loop copy
1216 // }
1217 // ...
1218 // //something is wrong, switch to original loop
1219 /// if(something_is_wrong) return; // ~CountedLoopReserveKit makes the switch
1220 // ...
1221 // //everything worked ok, return with the newly modified loop
1222 // lrk.use_new();
1223 // return; // ~CountedLoopReserveKit does nothing once use_new() was called
1224 // }
1225 //
1226 // Keep in mind, that by default if create_reserve() is not followed by use_new()
1227 // the dtor will "switch to the original" loop.
1228 // NOTE. You you modify outside of the original loop this class is no help.
1229 //
1230 class CountedLoopReserveKit {
1231 private:
1232 PhaseIdealLoop* _phase;
1233 IdealLoopTree* _lpt;
1234 LoopNode* _lp;
1235 IfNode* _iff;
1236 LoopNode* _lp_reserved;
1237 bool _has_reserved;
1238 bool _use_new;
1239 const bool _active; //may be set to false in ctor, then the object is dummy
1240
1241 public:
1242 CountedLoopReserveKit(PhaseIdealLoop* phase, IdealLoopTree *loop, bool active);
1243 ~CountedLoopReserveKit();
1244 void use_new() {_use_new = true;}
1245 void set_iff(IfNode* x) {_iff = x;}
1246 bool has_reserved() const { return _active && _has_reserved;}
1247 private:
1248 bool create_reserve();
1249 };// class CountedLoopReserveKit
1250
1251 inline Node* IdealLoopTree::tail() {
1252 // Handle lazy update of _tail field
1253 Node *n = _tail;
1254 //while( !n->in(0) ) // Skip dead CFG nodes
1255 //n = n->in(1);
1256 if (n->in(0) == NULL)
1257 n = _phase->get_ctrl(n);
1258 _tail = n;
1259 return n;
1260 }
1261
1262
1263 // Iterate over the loop tree using a preorder, left-to-right traversal.
1264 //
1265 // Example that visits all counted loops from within PhaseIdealLoop
1266 //
1267 // for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
1268 // IdealLoopTree* lpt = iter.current();
1269 // if (!lpt->is_counted()) continue;
1270 // ...
1271 class LoopTreeIterator : public StackObj {
1272 private:
1273 IdealLoopTree* _root;
1274 IdealLoopTree* _curnt;
1275
1276 public:
1277 LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {}
1278
1279 bool done() { return _curnt == NULL; } // Finished iterating?
1280
1281 void next(); // Advance to next loop tree
1282
1283 IdealLoopTree* current() { return _curnt; } // Return current value of iterator.
1284 };
1285
1286 #endif // SHARE_VM_OPTO_LOOPNODE_HPP