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
78 public:
79 // Names for edge indices
80 enum { Self=0, EntryControl, LoopBackControl };
81
82 int is_inner_loop() const { return _loop_flags & InnerLoop; }
83 void set_inner_loop() { _loop_flags |= InnerLoop; }
84
85 int has_range_checks() const { return _loop_flags & HasRangeChecks; }
86 int is_multiversioned() const { return _loop_flags & IsMultiversioned; }
87 int is_vectorized_loop() const { return _loop_flags & VectorizedLoop; }
88 int is_partial_peel_loop() const { return _loop_flags & PartialPeelLoop; }
89 void set_partial_peel_loop() { _loop_flags |= PartialPeelLoop; }
90 int partial_peel_has_failed() const { return _loop_flags & PartialPeelFailed; }
91
92 void mark_partial_peel_failed() { _loop_flags |= PartialPeelFailed; }
93 void mark_has_reductions() { _loop_flags |= HasReductions; }
94 void mark_was_slp() { _loop_flags |= WasSlpAnalyzed; }
95 void mark_passed_slp() { _loop_flags |= PassedSlpAnalysis; }
96 void mark_do_unroll_only() { _loop_flags |= DoUnrollOnly; }
97 void mark_loop_vectorized() { _loop_flags |= VectorizedLoop; }
98 void mark_has_atomic_post_loop() { _loop_flags |= HasAtomicPostLoop; }
99 void mark_has_range_checks() { _loop_flags |= HasRangeChecks; }
100 void mark_is_multiversioned() { _loop_flags |= IsMultiversioned; }
101
102 int unswitch_max() { return _unswitch_max; }
103 int unswitch_count() { return _unswitch_count; }
104 void set_unswitch_count(int val) {
105 assert (val <= unswitch_max(), "too many unswitches");
106 _unswitch_count = val;
107 }
108
109 LoopNode( Node *entry, Node *backedge ) : RegionNode(3), _loop_flags(0), _unswitch_count(0) {
110 init_class_id(Class_Loop);
111 init_req(EntryControl, entry);
112 init_req(LoopBackControl, backedge);
113 }
114
115 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
116 virtual int Opcode() const;
117 bool can_be_counted_loop(PhaseTransform* phase) const {
118 return req() == 3 && in(0) != NULL &&
119 in(1) != NULL && phase->type(in(1)) != Type::TOP &&
120 in(2) != NULL && phase->type(in(2)) != Type::TOP;
121 }
122 bool is_valid_counted_loop() const;
123 #ifndef PRODUCT
124 virtual void dump_spec(outputStream *st) const;
125 #endif
126 };
127
128 //------------------------------Counted Loops----------------------------------
129 // Counted loops are all trip-counted loops, with exactly 1 trip-counter exit
130 // path (and maybe some other exit paths). The trip-counter exit is always
131 // last in the loop. The trip-counter have to stride by a constant;
132 // the exit value is also loop invariant.
133
134 // CountedLoopNodes and CountedLoopEndNodes come in matched pairs. The
135 // CountedLoopNode has the incoming loop control and the loop-back-control
136 // which is always the IfTrue before the matching CountedLoopEndNode. The
137 // CountedLoopEndNode has an incoming control (possibly not the
138 // CountedLoopNode if there is control flow in the loop), the post-increment
139 // trip-counter value, and the limit. The trip-counter value is always of
140 // the form (Op old-trip-counter stride). The old-trip-counter is produced
141 // by a Phi connected to the CountedLoopNode. The stride is constant.
142 // The Op is any commutable opcode, including Add, Mul, Xor. The
143 // CountedLoopEndNode also takes in the loop-invariant limit value.
144
145 // From a CountedLoopNode I can reach the matching CountedLoopEndNode via the
146 // loop-back control. From CountedLoopEndNodes I can reach CountedLoopNodes
147 // via the old-trip-counter from the Op node.
148
149 //------------------------------CountedLoopNode--------------------------------
150 // CountedLoopNodes head simple counted loops. CountedLoopNodes have as
151 // inputs the incoming loop-start control and the loop-back control, so they
152 // act like RegionNodes. They also take in the initial trip counter, the
153 // loop-invariant stride and the loop-invariant limit value. CountedLoopNodes
154 // produce a loop-body control and the trip counter value. Since
155 // CountedLoopNodes behave like RegionNodes I still have a standard CFG model.
156
157 class CountedLoopNode : public LoopNode {
158 // Size is bigger to hold _main_idx. However, _main_idx does not change
159 // the semantics so it does not appear in the hash & cmp functions.
160 virtual uint size_of() const { return sizeof(*this); }
161
162 // For Pre- and Post-loops during debugging ONLY, this holds the index of
163 // the Main CountedLoop. Used to assert that we understand the graph shape.
164 node_idx_t _main_idx;
165
166 // Known trip count calculated by compute_exact_trip_count()
167 uint _trip_count;
168
169 // Expected trip count from profile data
170 float _profile_trip_cnt;
171
172 // Log2 of original loop bodies in unrolled loop
173 int _unrolled_count_log2;
174
175 // Node count prior to last unrolling - used to decide if
176 // unroll,optimize,unroll,optimize,... is making progress
177 int _node_count_before_unroll;
178
179 // If slp analysis is performed we record the maximum
180 // vector mapped unroll factor here
181 int _slp_maximum_unroll_factor;
182
183 public:
184 CountedLoopNode( Node *entry, Node *backedge )
185 : LoopNode(entry, backedge), _main_idx(0), _trip_count(max_juint),
186 _profile_trip_cnt(COUNT_UNKNOWN), _unrolled_count_log2(0),
187 _node_count_before_unroll(0), _slp_maximum_unroll_factor(0) {
188 init_class_id(Class_CountedLoop);
189 // Initialize _trip_count to the largest possible value.
190 // Will be reset (lower) if the loop's trip count is known.
191 }
192
193 virtual int Opcode() const;
194 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
195
196 Node *init_control() const { return in(EntryControl); }
197 Node *back_control() const { return in(LoopBackControl); }
198 CountedLoopEndNode *loopexit() const;
199 Node *init_trip() const;
200 Node *stride() const;
201 int stride_con() const;
202 bool stride_is_con() const;
203 Node *limit() const;
204 Node *incr() const;
205 Node *phi() const;
206
207 // Match increment with optional truncation
208 static Node* match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type);
209
210 // A 'main' loop has a pre-loop and a post-loop. The 'main' loop
211 // can run short a few iterations and may start a few iterations in.
212 // It will be RCE'd and unrolled and aligned.
213
214 // A following 'post' loop will run any remaining iterations. Used
215 // during Range Check Elimination, the 'post' loop will do any final
216 // iterations with full checks. Also used by Loop Unrolling, where
217 // the 'post' loop will do any epilog iterations needed. Basically,
218 // a 'post' loop can not profitably be further unrolled or RCE'd.
219
220 // A preceding 'pre' loop will run at least 1 iteration (to do peeling),
221 // it may do under-flow checks for RCE and may do alignment iterations
222 // so the following main loop 'knows' that it is striding down cache
223 // lines.
224
225 // A 'main' loop that is ONLY unrolled or peeled, never RCE'd or
226 // Aligned, may be missing it's pre-loop.
227 int is_normal_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Normal; }
228 int is_pre_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Pre; }
229 int is_main_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Main; }
230 int is_post_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Post; }
231 int is_reduction_loop() const { return (_loop_flags&HasReductions) == HasReductions; }
232 int was_slp_analyzed () const { return (_loop_flags&WasSlpAnalyzed) == WasSlpAnalyzed; }
233 int has_passed_slp () const { return (_loop_flags&PassedSlpAnalysis) == PassedSlpAnalysis; }
234 int do_unroll_only () const { return (_loop_flags&DoUnrollOnly) == DoUnrollOnly; }
235 int is_main_no_pre_loop() const { return _loop_flags & MainHasNoPreLoop; }
236 int has_atomic_post_loop () const { return (_loop_flags & HasAtomicPostLoop) == HasAtomicPostLoop; }
237 void set_main_no_pre_loop() { _loop_flags |= MainHasNoPreLoop; }
238
239 int main_idx() const { return _main_idx; }
240
241
242 void set_pre_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; }
243 void set_main_loop ( ) { assert(is_normal_loop(),""); _loop_flags |= Main; }
244 void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; }
245 void set_normal_loop( ) { _loop_flags &= ~PreMainPostFlagsMask; }
246
247 void set_trip_count(uint tc) { _trip_count = tc; }
248 uint trip_count() { return _trip_count; }
249
250 bool has_exact_trip_count() const { return (_loop_flags & HasExactTripCount) != 0; }
251 void set_exact_trip_count(uint tc) {
252 _trip_count = tc;
253 _loop_flags |= HasExactTripCount;
254 }
255 void set_nonexact_trip_count() {
256 _loop_flags &= ~HasExactTripCount;
257 }
258 void set_notpassed_slp() {
259 _loop_flags &= ~PassedSlpAnalysis;
260 }
261
262 void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; }
263 float profile_trip_cnt() { return _profile_trip_cnt; }
264
265 void double_unrolled_count() { _unrolled_count_log2++; }
266 int unrolled_count() { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); }
267
268 void set_node_count_before_unroll(int ct) { _node_count_before_unroll = ct; }
269 int node_count_before_unroll() { return _node_count_before_unroll; }
270 void set_slp_max_unroll(int unroll_factor) { _slp_maximum_unroll_factor = unroll_factor; }
271 int slp_max_unroll() const { return _slp_maximum_unroll_factor; }
272
273 #ifndef PRODUCT
274 virtual void dump_spec(outputStream *st) const;
275 #endif
276 };
277
278 //------------------------------CountedLoopEndNode-----------------------------
279 // CountedLoopEndNodes end simple trip counted loops. They act much like
280 // IfNodes.
281 class CountedLoopEndNode : public IfNode {
282 public:
283 enum { TestControl, TestValue };
284
285 CountedLoopEndNode( Node *control, Node *test, float prob, float cnt )
286 : IfNode( control, test, prob, cnt) {
287 init_class_id(Class_CountedLoopEnd);
288 }
289 virtual int Opcode() const;
290
291 Node *cmp_node() const { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : NULL; }
292 Node *incr() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; }
293 Node *limit() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; }
294 Node *stride() const { Node *tmp = incr (); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; }
295 Node *init_trip() const { Node *tmp = phi (); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; }
296 int stride_con() const;
297 bool stride_is_con() const { Node *tmp = stride (); return (tmp != NULL && tmp->is_Con()); }
298 BoolTest::mask test_trip() const { return in(TestValue)->as_Bool()->_test._test; }
299 PhiNode *phi() const {
300 Node *tmp = incr();
301 if (tmp && tmp->req() == 3) {
302 Node* phi = tmp->in(1);
303 if (phi->is_Phi()) {
304 return phi->as_Phi();
305 }
306 }
307 return NULL;
308 }
309 CountedLoopNode *loopnode() const {
310 // The CountedLoopNode that goes with this CountedLoopEndNode may
311 // have been optimized out by the IGVN so be cautious with the
312 // pattern matching on the graph
313 PhiNode* iv_phi = phi();
314 if (iv_phi == NULL) {
315 return NULL;
316 }
317 Node *ln = iv_phi->in(0);
318 if (ln->is_CountedLoop() && ln->as_CountedLoop()->loopexit() == this) {
319 return (CountedLoopNode*)ln;
320 }
321 return NULL;
322 }
323
324 #ifndef PRODUCT
325 virtual void dump_spec(outputStream *st) const;
326 #endif
327 };
328
329
330 inline CountedLoopEndNode *CountedLoopNode::loopexit() const {
331 Node *bc = back_control();
332 if( bc == NULL ) return NULL;
333 Node *le = bc->in(0);
334 if( le->Opcode() != Op_CountedLoopEnd )
335 return NULL;
336 return (CountedLoopEndNode*)le;
337 }
338 inline Node *CountedLoopNode::init_trip() const { return loopexit() ? loopexit()->init_trip() : NULL; }
339 inline Node *CountedLoopNode::stride() const { return loopexit() ? loopexit()->stride() : NULL; }
340 inline int CountedLoopNode::stride_con() const { return loopexit() ? loopexit()->stride_con() : 0; }
341 inline bool CountedLoopNode::stride_is_con() const { return loopexit() && loopexit()->stride_is_con(); }
342 inline Node *CountedLoopNode::limit() const { return loopexit() ? loopexit()->limit() : NULL; }
343 inline Node *CountedLoopNode::incr() const { return loopexit() ? loopexit()->incr() : NULL; }
344 inline Node *CountedLoopNode::phi() const { return loopexit() ? loopexit()->phi() : NULL; }
345
346 //------------------------------LoopLimitNode-----------------------------
347 // Counted Loop limit node which represents exact final iterator value:
348 // trip_count = (limit - init_trip + stride - 1)/stride
349 // final_value= trip_count * stride + init_trip.
350 // Use HW instructions to calculate it when it can overflow in integer.
351 // Note, final_value should fit into integer since counted loop has
352 // limit check: limit <= max_int-stride.
353 class LoopLimitNode : public Node {
354 enum { Init=1, Limit=2, Stride=3 };
355 public:
356 LoopLimitNode( Compile* C, Node *init, Node *limit, Node *stride ) : Node(0,init,limit,stride) {
357 // Put it on the Macro nodes list to optimize during macro nodes expansion.
358 init_flags(Flag_is_macro);
359 C->add_macro_node(this);
360 }
361 virtual int Opcode() const;
362 virtual const Type *bottom_type() const { return TypeInt::INT; }
363 virtual uint ideal_reg() const { return Op_RegI; }
364 virtual const Type* Value(PhaseGVN* phase) const;
365 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
366 virtual Node* Identity(PhaseGVN* phase);
367 };
368
369 // -----------------------------IdealLoopTree----------------------------------
370 class IdealLoopTree : public ResourceObj {
371 public:
372 IdealLoopTree *_parent; // Parent in loop tree
373 IdealLoopTree *_next; // Next sibling in loop tree
374 IdealLoopTree *_child; // First child in loop tree
375
376 // The head-tail backedge defines the loop.
377 // If tail is NULL then this loop has multiple backedges as part of the
378 // same loop. During cleanup I'll peel off the multiple backedges; merge
379 // them at the loop bottom and flow 1 real backedge into the loop.
380 Node *_head; // Head of loop
381 Node *_tail; // Tail of loop
382 inline Node *tail(); // Handle lazy update of _tail field
383 PhaseIdealLoop* _phase;
384 int _local_loop_unroll_limit;
385 int _local_loop_unroll_factor;
386
387 Node_List _body; // Loop body for inner loops
388
389 uint8_t _nest; // Nesting depth
390 uint8_t _irreducible:1, // True if irreducible
391 _has_call:1, // True if has call safepoint
392 _has_sfpt:1, // True if has non-call safepoint
393 _rce_candidate:1; // True if candidate for range check elimination
394
395 Node_List* _safepts; // List of safepoints in this loop
396 Node_List* _required_safept; // A inner loop cannot delete these safepts;
397 bool _allow_optimizations; // Allow loop optimizations
398
399 IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail )
400 : _parent(0), _next(0), _child(0),
401 _head(head), _tail(tail),
402 _phase(phase),
403 _safepts(NULL),
404 _required_safept(NULL),
405 _allow_optimizations(true),
406 _nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0),
407 _local_loop_unroll_limit(0), _local_loop_unroll_factor(0)
408 { }
409
410 // Is 'l' a member of 'this'?
411 bool is_member(const IdealLoopTree *l) const; // Test for nested membership
412
413 // Set loop nesting depth. Accumulate has_call bits.
414 int set_nest( uint depth );
415
416 // Split out multiple fall-in edges from the loop header. Move them to a
417 // private RegionNode before the loop. This becomes the loop landing pad.
418 void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt );
419
420 // Split out the outermost loop from this shared header.
421 void split_outer_loop( PhaseIdealLoop *phase );
422
423 // Merge all the backedges from the shared header into a private Region.
424 // Feed that region as the one backedge to this loop.
425 void merge_many_backedges( PhaseIdealLoop *phase );
426
427 // Split shared headers and insert loop landing pads.
428 // Insert a LoopNode to replace the RegionNode.
429 // Returns TRUE if loop tree is structurally changed.
430 bool beautify_loops( PhaseIdealLoop *phase );
431
432 // Perform optimization to use the loop predicates for null checks and range checks.
433 // Applies to any loop level (not just the innermost one)
434 bool loop_predication( PhaseIdealLoop *phase);
435
436 // Perform iteration-splitting on inner loops. Split iterations to
437 // avoid range checks or one-shot null checks. Returns false if the
438 // current round of loop opts should stop.
439 bool iteration_split( PhaseIdealLoop *phase, Node_List &old_new );
440
441 // Driver for various flavors of iteration splitting. Returns false
442 // if the current round of loop opts should stop.
443 bool iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new );
444
445 // Given dominators, try to find loops with calls that must always be
446 // executed (call dominates loop tail). These loops do not need non-call
447 // safepoints (ncsfpt).
448 void check_safepts(VectorSet &visited, Node_List &stack);
449
450 // Allpaths backwards scan from loop tail, terminating each path at first safepoint
451 // encountered.
452 void allpaths_check_safepts(VectorSet &visited, Node_List &stack);
453
454 // Remove safepoints from loop. Optionally keeping one.
455 void remove_safepoints(PhaseIdealLoop* phase, bool keep_one);
456
457 // Convert to counted loops where possible
458 void counted_loop( PhaseIdealLoop *phase );
459
460 // Check for Node being a loop-breaking test
461 Node *is_loop_exit(Node *iff) const;
462
463 // Returns true if ctrl is executed on every complete iteration
464 bool dominates_backedge(Node* ctrl);
465
466 // Remove simplistic dead code from loop body
467 void DCE_loop_body();
468
469 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage.
470 // Replace with a 1-in-10 exit guess.
471 void adjust_loop_exit_prob( PhaseIdealLoop *phase );
472
473 // Return TRUE or FALSE if the loop should never be RCE'd or aligned.
474 // Useful for unrolling loops with NO array accesses.
475 bool policy_peel_only( PhaseIdealLoop *phase ) const;
476
477 // Return TRUE or FALSE if the loop should be unswitched -- clone
478 // loop with an invariant test
479 bool policy_unswitching( PhaseIdealLoop *phase ) const;
480
481 // Micro-benchmark spamming. Remove empty loops.
482 bool policy_do_remove_empty_loop( PhaseIdealLoop *phase );
483
484 // Convert one iteration loop into normal code.
485 bool policy_do_one_iteration_loop( PhaseIdealLoop *phase );
486
487 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can
488 // make some loop-invariant test (usually a null-check) happen before the
489 // loop.
490 bool policy_peeling( PhaseIdealLoop *phase ) const;
491
492 // Return TRUE or FALSE if the loop should be maximally unrolled. Stash any
493 // known trip count in the counted loop node.
494 bool policy_maximally_unroll( PhaseIdealLoop *phase ) const;
495
496 // Return TRUE or FALSE if the loop should be unrolled or not. Unroll if
497 // the loop is a CountedLoop and the body is small enough.
498 bool policy_unroll(PhaseIdealLoop *phase);
499
500 // Loop analyses to map to a maximal superword unrolling for vectorization.
501 void policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_ct);
502
503 // Return TRUE or FALSE if the loop should be range-check-eliminated.
504 // Gather a list of IF tests that are dominated by iteration splitting;
505 // also gather the end of the first split and the start of the 2nd split.
506 bool policy_range_check( PhaseIdealLoop *phase ) const;
507
508 // Return TRUE or FALSE if the loop should be cache-line aligned.
509 // Gather the expression that does the alignment. Note that only
510 // one array base can be aligned in a loop (unless the VM guarantees
511 // mutual alignment). Note that if we vectorize short memory ops
512 // into longer memory ops, we may want to increase alignment.
513 bool policy_align( PhaseIdealLoop *phase ) const;
514
515 // Return TRUE if "iff" is a range check.
516 bool is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const;
517
518 // Compute loop exact trip count if possible
519 void compute_exact_trip_count( PhaseIdealLoop *phase );
520
521 // Compute loop trip count from profile data
522 void compute_profile_trip_cnt( PhaseIdealLoop *phase );
523
524 // Reassociate invariant expressions.
525 void reassociate_invariants(PhaseIdealLoop *phase);
526 // Reassociate invariant add and subtract expressions.
527 Node* reassociate_add_sub(Node* n1, PhaseIdealLoop *phase);
528 // Return nonzero index of invariant operand if invariant and variant
529 // are combined with an Add or Sub. Helper for reassociate_invariants.
530 int is_invariant_addition(Node* n, PhaseIdealLoop *phase);
531
532 // Return true if n is invariant
533 bool is_invariant(Node* n) const;
534
535 // Put loop body on igvn work list
536 void record_for_igvn();
537
538 bool is_loop() { return !_irreducible && _tail && !_tail->is_top(); }
539 bool is_inner() { return is_loop() && _child == NULL; }
540 bool is_counted() { return is_loop() && _head != NULL && _head->is_CountedLoop(); }
541
542 void remove_main_post_loops(CountedLoopNode *cl, PhaseIdealLoop *phase);
543
544 #ifndef PRODUCT
545 void dump_head( ) const; // Dump loop head only
546 void dump() const; // Dump this loop recursively
547 void verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const;
548 #endif
549
550 };
551
552 class PostLoopInfo {
553 public:
554 Node *new_main_exit;
555 CountedLoopNode *post_head;
556
557 PostLoopInfo() { init(); }
558
559 void init() { new_main_exit = NULL; post_head = NULL; }
560 };
561
562 // -----------------------------PhaseIdealLoop---------------------------------
563 // Computes the mapping from Nodes to IdealLoopTrees. Organizes IdealLoopTrees into a
564 // loop tree. Drives the loop-based transformations on the ideal graph.
565 class PhaseIdealLoop : public PhaseTransform {
566 friend class IdealLoopTree;
567 friend class SuperWord;
568 friend class CountedLoopReserveKit;
569
570 // Pre-computed def-use info
571 PhaseIterGVN &_igvn;
572
573 // Head of loop tree
574 IdealLoopTree *_ltree_root;
575
576 // Array of pre-order numbers, plus post-visited bit.
577 // ZERO for not pre-visited. EVEN for pre-visited but not post-visited.
578 // ODD for post-visited. Other bits are the pre-order number.
579 uint *_preorders;
580 uint _max_preorder;
581
582 const PhaseIdealLoop* _verify_me;
583 bool _verify_only;
584
585 // Allocate _preorders[] array
586 void allocate_preorders() {
587 _max_preorder = C->unique()+8;
588 _preorders = NEW_RESOURCE_ARRAY(uint, _max_preorder);
589 memset(_preorders, 0, sizeof(uint) * _max_preorder);
590 }
591
592 // Allocate _preorders[] array
593 void reallocate_preorders() {
594 if ( _max_preorder < C->unique() ) {
595 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique());
596 _max_preorder = C->unique();
597 }
598 memset(_preorders, 0, sizeof(uint) * _max_preorder);
599 }
600
601 // Check to grow _preorders[] array for the case when build_loop_tree_impl()
602 // adds new nodes.
603 void check_grow_preorders( ) {
604 if ( _max_preorder < C->unique() ) {
605 uint newsize = _max_preorder<<1; // double size of array
606 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize);
607 memset(&_preorders[_max_preorder],0,sizeof(uint)*(newsize-_max_preorder));
608 _max_preorder = newsize;
609 }
610 }
611 // Check for pre-visited. Zero for NOT visited; non-zero for visited.
612 int is_visited( Node *n ) const { return _preorders[n->_idx]; }
613 // Pre-order numbers are written to the Nodes array as low-bit-set values.
614 void set_preorder_visited( Node *n, int pre_order ) {
615 assert( !is_visited( n ), "already set" );
616 _preorders[n->_idx] = (pre_order<<1);
617 };
618 // Return pre-order number.
619 int get_preorder( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]>>1; }
620
621 // Check for being post-visited.
622 // Should be previsited already (checked with assert(is_visited(n))).
623 int is_postvisited( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]&1; }
624
625 // Mark as post visited
626 void set_postvisited( Node *n ) { assert( !is_postvisited( n ), "" ); _preorders[n->_idx] |= 1; }
627
628 // Set/get control node out. Set lower bit to distinguish from IdealLoopTree
629 // Returns true if "n" is a data node, false if it's a control node.
630 bool has_ctrl( Node *n ) const { return ((intptr_t)_nodes[n->_idx]) & 1; }
631
632 // clear out dead code after build_loop_late
633 Node_List _deadlist;
634
635 // Support for faster execution of get_late_ctrl()/dom_lca()
636 // when a node has many uses and dominator depth is deep.
637 Node_Array _dom_lca_tags;
638 void init_dom_lca_tags();
639 void clear_dom_lca_tags();
640
641 // Helper for debugging bad dominance relationships
642 bool verify_dominance(Node* n, Node* use, Node* LCA, Node* early);
643
644 Node* compute_lca_of_uses(Node* n, Node* early, bool verify = false);
645
646 // Inline wrapper for frequent cases:
647 // 1) only one use
648 // 2) a use is the same as the current LCA passed as 'n1'
649 Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) {
650 assert( n->is_CFG(), "" );
651 // Fast-path NULL lca
652 if( lca != NULL && lca != n ) {
653 assert( lca->is_CFG(), "" );
654 // find LCA of all uses
655 n = dom_lca_for_get_late_ctrl_internal( lca, n, tag );
656 }
657 return find_non_split_ctrl(n);
658 }
659 Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag );
660
661 // Helper function for directing control inputs away from CFG split
662 // points.
663 Node *find_non_split_ctrl( Node *ctrl ) const {
664 if (ctrl != NULL) {
665 if (ctrl->is_MultiBranch()) {
666 ctrl = ctrl->in(0);
667 }
668 assert(ctrl->is_CFG(), "CFG");
669 }
670 return ctrl;
671 }
672
673 bool cast_incr_before_loop(Node* incr, Node* ctrl, Node* loop);
674
675 public:
676 bool has_node( Node* n ) const {
677 guarantee(n != NULL, "No Node.");
678 return _nodes[n->_idx] != NULL;
679 }
680 // check if transform created new nodes that need _ctrl recorded
681 Node *get_late_ctrl( Node *n, Node *early );
682 Node *get_early_ctrl( Node *n );
683 Node *get_early_ctrl_for_expensive(Node *n, Node* earliest);
684 void set_early_ctrl( Node *n );
685 void set_subtree_ctrl( Node *root );
686 void set_ctrl( Node *n, Node *ctrl ) {
687 assert( !has_node(n) || has_ctrl(n), "" );
688 assert( ctrl->in(0), "cannot set dead control node" );
689 assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" );
690 _nodes.map( n->_idx, (Node*)((intptr_t)ctrl + 1) );
691 }
692 // Set control and update loop membership
693 void set_ctrl_and_loop(Node* n, Node* ctrl) {
694 IdealLoopTree* old_loop = get_loop(get_ctrl(n));
695 IdealLoopTree* new_loop = get_loop(ctrl);
696 if (old_loop != new_loop) {
697 if (old_loop->_child == NULL) old_loop->_body.yank(n);
698 if (new_loop->_child == NULL) new_loop->_body.push(n);
699 }
700 set_ctrl(n, ctrl);
701 }
702 // Control nodes can be replaced or subsumed. During this pass they
703 // get their replacement Node in slot 1. Instead of updating the block
704 // location of all Nodes in the subsumed block, we lazily do it. As we
705 // pull such a subsumed block out of the array, we write back the final
706 // correct block.
707 Node *get_ctrl( Node *i ) {
708 assert(has_node(i), "");
709 Node *n = get_ctrl_no_update(i);
710 _nodes.map( i->_idx, (Node*)((intptr_t)n + 1) );
711 assert(has_node(i) && has_ctrl(i), "");
712 assert(n == find_non_split_ctrl(n), "must return legal ctrl" );
713 return n;
714 }
715 // true if CFG node d dominates CFG node n
716 bool is_dominator(Node *d, Node *n);
717 // return get_ctrl for a data node and self(n) for a CFG node
718 Node* ctrl_or_self(Node* n) {
719 if (has_ctrl(n))
720 return get_ctrl(n);
721 else {
722 assert (n->is_CFG(), "must be a CFG node");
723 return n;
724 }
725 }
726
727 private:
728 Node *get_ctrl_no_update_helper(Node *i) const {
729 assert(has_ctrl(i), "should be control, not loop");
730 return (Node*)(((intptr_t)_nodes[i->_idx]) & ~1);
731 }
732
733 Node *get_ctrl_no_update(Node *i) const {
734 assert( has_ctrl(i), "" );
735 Node *n = get_ctrl_no_update_helper(i);
736 if (!n->in(0)) {
737 // Skip dead CFG nodes
738 do {
739 n = get_ctrl_no_update_helper(n);
740 } while (!n->in(0));
741 n = find_non_split_ctrl(n);
742 }
743 return n;
744 }
745
746 // Check for loop being set
747 // "n" must be a control node. Returns true if "n" is known to be in a loop.
748 bool has_loop( Node *n ) const {
749 assert(!has_node(n) || !has_ctrl(n), "");
750 return has_node(n);
751 }
752 // Set loop
753 void set_loop( Node *n, IdealLoopTree *loop ) {
754 _nodes.map(n->_idx, (Node*)loop);
755 }
756 // Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms. Replace
757 // the 'old_node' with 'new_node'. Kill old-node. Add a reference
758 // from old_node to new_node to support the lazy update. Reference
759 // replaces loop reference, since that is not needed for dead node.
760 public:
761 void lazy_update(Node *old_node, Node *new_node) {
762 assert(old_node != new_node, "no cycles please");
763 // Re-use the side array slot for this node to provide the
764 // forwarding pointer.
765 _nodes.map(old_node->_idx, (Node*)((intptr_t)new_node + 1));
766 }
767 void lazy_replace(Node *old_node, Node *new_node) {
768 _igvn.replace_node(old_node, new_node);
769 lazy_update(old_node, new_node);
770 }
771
772 private:
773
774 // Place 'n' in some loop nest, where 'n' is a CFG node
775 void build_loop_tree();
776 int build_loop_tree_impl( Node *n, int pre_order );
777 // Insert loop into the existing loop tree. 'innermost' is a leaf of the
778 // loop tree, not the root.
779 IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost );
780
781 // Place Data nodes in some loop nest
782 void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
783 void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
784 void build_loop_late_post ( Node* n );
785
786 // Array of immediate dominance info for each CFG node indexed by node idx
787 private:
788 uint _idom_size;
789 Node **_idom; // Array of immediate dominators
790 uint *_dom_depth; // Used for fast LCA test
791 GrowableArray<uint>* _dom_stk; // For recomputation of dom depth
792
793 Node* idom_no_update(Node* d) const {
794 assert(d->_idx < _idom_size, "oob");
795 Node* n = _idom[d->_idx];
796 assert(n != NULL,"Bad immediate dominator info.");
797 while (n->in(0) == NULL) { // Skip dead CFG nodes
798 //n = n->in(1);
799 n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1);
800 assert(n != NULL,"Bad immediate dominator info.");
801 }
802 return n;
803 }
804 Node *idom(Node* d) const {
805 uint didx = d->_idx;
806 Node *n = idom_no_update(d);
807 _idom[didx] = n; // Lazily remove dead CFG nodes from table.
808 return n;
809 }
810 uint dom_depth(Node* d) const {
811 guarantee(d != NULL, "Null dominator info.");
812 guarantee(d->_idx < _idom_size, "");
813 return _dom_depth[d->_idx];
814 }
815 void set_idom(Node* d, Node* n, uint dom_depth);
816 // Locally compute IDOM using dom_lca call
817 Node *compute_idom( Node *region ) const;
818 // Recompute dom_depth
819 void recompute_dom_depth();
820
821 // Is safept not required by an outer loop?
822 bool is_deleteable_safept(Node* sfpt);
823
824 // Replace parallel induction variable (parallel to trip counter)
825 void replace_parallel_iv(IdealLoopTree *loop);
826
827 // Perform verification that the graph is valid.
828 PhaseIdealLoop( PhaseIterGVN &igvn) :
829 PhaseTransform(Ideal_Loop),
830 _igvn(igvn),
831 _dom_lca_tags(arena()), // Thread::resource_area
832 _verify_me(NULL),
833 _verify_only(true) {
834 build_and_optimize(false, false);
835 }
836
837 // build the loop tree and perform any requested optimizations
838 void build_and_optimize(bool do_split_if, bool skip_loop_opts);
839
840 public:
841 // Dominators for the sea of nodes
842 void Dominators();
843 Node *dom_lca( Node *n1, Node *n2 ) const {
844 return find_non_split_ctrl(dom_lca_internal(n1, n2));
845 }
846 Node *dom_lca_internal( Node *n1, Node *n2 ) const;
847
848 // Compute the Ideal Node to Loop mapping
849 PhaseIdealLoop( PhaseIterGVN &igvn, bool do_split_ifs, bool skip_loop_opts = false) :
850 PhaseTransform(Ideal_Loop),
851 _igvn(igvn),
852 _dom_lca_tags(arena()), // Thread::resource_area
853 _verify_me(NULL),
854 _verify_only(false) {
855 build_and_optimize(do_split_ifs, skip_loop_opts);
856 }
857
858 // Verify that verify_me made the same decisions as a fresh run.
859 PhaseIdealLoop( PhaseIterGVN &igvn, const PhaseIdealLoop *verify_me) :
860 PhaseTransform(Ideal_Loop),
861 _igvn(igvn),
862 _dom_lca_tags(arena()), // Thread::resource_area
863 _verify_me(verify_me),
864 _verify_only(false) {
865 build_and_optimize(false, false);
866 }
867
868 // Build and verify the loop tree without modifying the graph. This
869 // is useful to verify that all inputs properly dominate their uses.
870 static void verify(PhaseIterGVN& igvn) {
871 #ifdef ASSERT
872 PhaseIdealLoop v(igvn);
873 #endif
874 }
875
876 // True if the method has at least 1 irreducible loop
877 bool _has_irreducible_loops;
878
879 // Per-Node transform
880 virtual Node *transform( Node *a_node ) { return 0; }
881
882 bool is_counted_loop( Node *x, IdealLoopTree *loop );
883
884 Node* exact_limit( IdealLoopTree *loop );
885
886 // Return a post-walked LoopNode
887 IdealLoopTree *get_loop( Node *n ) const {
888 // Dead nodes have no loop, so return the top level loop instead
889 if (!has_node(n)) return _ltree_root;
890 assert(!has_ctrl(n), "");
891 return (IdealLoopTree*)_nodes[n->_idx];
892 }
893
894 // Is 'n' a (nested) member of 'loop'?
895 int is_member( const IdealLoopTree *loop, Node *n ) const {
896 return loop->is_member(get_loop(n)); }
897
898 // This is the basic building block of the loop optimizations. It clones an
899 // entire loop body. It makes an old_new loop body mapping; with this
900 // mapping you can find the new-loop equivalent to an old-loop node. All
901 // new-loop nodes are exactly equal to their old-loop counterparts, all
902 // edges are the same. All exits from the old-loop now have a RegionNode
903 // that merges the equivalent new-loop path. This is true even for the
904 // normal "loop-exit" condition. All uses of loop-invariant old-loop values
905 // now come from (one or more) Phis that merge their new-loop equivalents.
906 // Parameter side_by_side_idom:
907 // When side_by_size_idom is NULL, the dominator tree is constructed for
908 // the clone loop to dominate the original. Used in construction of
909 // pre-main-post loop sequence.
910 // When nonnull, the clone and original are side-by-side, both are
911 // dominated by the passed in side_by_side_idom node. Used in
912 // construction of unswitched loops.
913 void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth,
914 Node* side_by_side_idom = NULL);
915
916 // If we got the effect of peeling, either by actually peeling or by
917 // making a pre-loop which must execute at least once, we can remove
918 // all loop-invariant dominated tests in the main body.
919 void peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new );
920
921 // Generate code to do a loop peel for the given loop (and body).
922 // old_new is a temp array.
923 void do_peeling( IdealLoopTree *loop, Node_List &old_new );
924
925 // Add pre and post loops around the given loop. These loops are used
926 // during RCE, unrolling and aligning loops.
927 void insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only );
928
929 // Add post loop after the given loop.
930 void insert_post_loop( IdealLoopTree *loop, Node_List &old_new,
931 CountedLoopNode *main_head, CountedLoopEndNode *main_end,
932 Node *incr, Node *limit, PostLoopInfo &post_loop_info );
933
934 // Add an RCE'd post loop which we will multi-version adapt for run time test path usage
935 void insert_scalar_rced_post_loop( IdealLoopTree *loop, Node_List &old_new );
936
937 // Add a vector post loop between a vector main loop and the current post loop
938 void insert_vector_post_loop(IdealLoopTree *loop, Node_List &old_new);
939 // If Node n lives in the back_ctrl block, we clone a private version of n
940 // in preheader_ctrl block and return that, otherwise return n.
941 Node *clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones );
942
943 // Take steps to maximally unroll the loop. Peel any odd iterations, then
944 // unroll to do double iterations. The next round of major loop transforms
945 // will repeat till the doubled loop body does all remaining iterations in 1
946 // pass.
947 void do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new );
948
949 // Unroll the loop body one step - make each trip do 2 iterations.
950 void do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip );
951
952 // Mark vector reduction candidates before loop unrolling
953 void mark_reductions( IdealLoopTree *loop );
954
955 // Return true if exp is a constant times an induction var
956 bool is_scaled_iv(Node* exp, Node* iv, int* p_scale);
957
958 // Return true if exp is a scaled induction var plus (or minus) constant
959 bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth = 0);
960
961 // Create a new if above the uncommon_trap_if_pattern for the predicate to be promoted
962 ProjNode* create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry,
963 Deoptimization::DeoptReason reason,
964 int opcode);
965 void register_control(Node* n, IdealLoopTree *loop, Node* pred);
966
967 // Clone loop predicates to cloned loops (peeled, unswitched)
968 static ProjNode* clone_predicate(ProjNode* predicate_proj, Node* new_entry,
969 Deoptimization::DeoptReason reason,
970 PhaseIdealLoop* loop_phase,
971 PhaseIterGVN* igvn);
972
973 static Node* clone_loop_predicates(Node* old_entry, Node* new_entry,
974 bool clone_limit_check,
975 PhaseIdealLoop* loop_phase,
976 PhaseIterGVN* igvn);
977 Node* clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check);
978
979 static Node* skip_loop_predicates(Node* entry);
980
981 // Find a good location to insert a predicate
982 static ProjNode* find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason);
983 // Find a predicate
984 static Node* find_predicate(Node* entry);
985 // Construct a range check for a predicate if
986 BoolNode* rc_predicate(IdealLoopTree *loop, Node* ctrl,
987 int scale, Node* offset,
988 Node* init, Node* limit, Node* stride,
989 Node* range, bool upper);
990
991 // Implementation of the loop predication to promote checks outside the loop
992 bool loop_predication_impl(IdealLoopTree *loop);
993
994 // Helper function to collect predicate for eliminating the useless ones
995 void collect_potentially_useful_predicates(IdealLoopTree *loop, Unique_Node_List &predicate_opaque1);
996 void eliminate_useless_predicates();
997
998 // Change the control input of expensive nodes to allow commoning by
999 // IGVN when it is guaranteed to not result in a more frequent
1000 // execution of the expensive node. Return true if progress.
1001 bool process_expensive_nodes();
1002
1003 // Check whether node has become unreachable
1004 bool is_node_unreachable(Node *n) const {
1005 return !has_node(n) || n->is_unreachable(_igvn);
1006 }
1007
1008 // Eliminate range-checks and other trip-counter vs loop-invariant tests.
1009 void do_range_check( IdealLoopTree *loop, Node_List &old_new );
1010
1011 // Check to see if do_range_check(...) cleaned the main loop of range-checks
1012 void has_range_checks(IdealLoopTree *loop);
1013
1014 // Process post loops which have range checks and try to build a multi-version
1015 // guard to safely determine if we can execute the post loop which was RCE'd.
1016 bool multi_version_post_loops(IdealLoopTree *rce_loop, IdealLoopTree *legacy_loop);
1017
1018 // Cause the rce'd post loop to optimized away, this happens if we cannot complete multiverioning
1019 void poison_rce_post_loop(IdealLoopTree *rce_loop);
1020
1021 // Create a slow version of the loop by cloning the loop
1022 // and inserting an if to select fast-slow versions.
1023 ProjNode* create_slow_version_of_loop(IdealLoopTree *loop,
1024 Node_List &old_new,
1025 int opcode);
1026
1027 // Clone a loop and return the clone head (clone_loop_head).
1028 // Added nodes include int(1), int(0) - disconnected, If, IfTrue, IfFalse,
1029 // This routine was created for usage in CountedLoopReserveKit.
1030 //
1031 // int(1) -> If -> IfTrue -> original_loop_head
1032 // |
1033 // V
1034 // IfFalse -> clone_loop_head (returned by function pointer)
1035 //
1036 LoopNode* create_reserve_version_of_loop(IdealLoopTree *loop, CountedLoopReserveKit* lk);
1037 // Clone loop with an invariant test (that does not exit) and
1038 // insert a clone of the test that selects which version to
1039 // execute.
1040 void do_unswitching (IdealLoopTree *loop, Node_List &old_new);
1041
1042 // Find candidate "if" for unswitching
1043 IfNode* find_unswitching_candidate(const IdealLoopTree *loop) const;
1044
1045 // Range Check Elimination uses this function!
1046 // Constrain the main loop iterations so the affine function:
1047 // low_limit <= scale_con * I + offset < upper_limit
1048 // always holds true. That is, either increase the number of iterations in
1049 // the pre-loop or the post-loop until the condition holds true in the main
1050 // loop. Scale_con, offset and limit are all loop invariant.
1051 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 );
1052 // Helper function for add_constraint().
1053 Node* adjust_limit( int stride_con, Node * scale, Node *offset, Node *rc_limit, Node *loop_limit, Node *pre_ctrl );
1054
1055 // Partially peel loop up through last_peel node.
1056 bool partial_peel( IdealLoopTree *loop, Node_List &old_new );
1057
1058 // Create a scheduled list of nodes control dependent on ctrl set.
1059 void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched );
1060 // Has a use in the vector set
1061 bool has_use_in_set( Node* n, VectorSet& vset );
1062 // Has use internal to the vector set (ie. not in a phi at the loop head)
1063 bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop );
1064 // clone "n" for uses that are outside of loop
1065 int clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist );
1066 // clone "n" for special uses that are in the not_peeled region
1067 void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
1068 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist );
1069 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
1070 void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp );
1071 #ifdef ASSERT
1072 // Validate the loop partition sets: peel and not_peel
1073 bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel );
1074 // Ensure that uses outside of loop are of the right form
1075 bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
1076 uint orig_exit_idx, uint clone_exit_idx);
1077 bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx);
1078 #endif
1079
1080 // Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.)
1081 int stride_of_possible_iv( Node* iff );
1082 bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; }
1083 // Return the (unique) control output node that's in the loop (if it exists.)
1084 Node* stay_in_loop( Node* n, IdealLoopTree *loop);
1085 // Insert a signed compare loop exit cloned from an unsigned compare.
1086 IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop);
1087 void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop);
1088 // Utility to register node "n" with PhaseIdealLoop
1089 void register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth);
1090 // Utility to create an if-projection
1091 ProjNode* proj_clone(ProjNode* p, IfNode* iff);
1092 // Force the iff control output to be the live_proj
1093 Node* short_circuit_if(IfNode* iff, ProjNode* live_proj);
1094 // Insert a region before an if projection
1095 RegionNode* insert_region_before_proj(ProjNode* proj);
1096 // Insert a new if before an if projection
1097 ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj);
1098
1099 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1100 // "Nearly" because all Nodes have been cloned from the original in the loop,
1101 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1102 // through the Phi recursively, and return a Bool.
1103 BoolNode *clone_iff( PhiNode *phi, IdealLoopTree *loop );
1104 CmpNode *clone_bool( PhiNode *phi, IdealLoopTree *loop );
1105
1106
1107 // Rework addressing expressions to get the most loop-invariant stuff
1108 // moved out. We'd like to do all associative operators, but it's especially
1109 // important (common) to do address expressions.
1110 Node *remix_address_expressions( Node *n );
1111
1112 // Attempt to use a conditional move instead of a phi/branch
1113 Node *conditional_move( Node *n );
1114
1115 // Reorganize offset computations to lower register pressure.
1116 // Mostly prevent loop-fallout uses of the pre-incremented trip counter
1117 // (which are then alive with the post-incremented trip counter
1118 // forcing an extra register move)
1119 void reorg_offsets( IdealLoopTree *loop );
1120
1121 // Check for aggressive application of 'split-if' optimization,
1122 // using basic block level info.
1123 void split_if_with_blocks ( VectorSet &visited, Node_Stack &nstack );
1124 Node *split_if_with_blocks_pre ( Node *n );
1125 void split_if_with_blocks_post( Node *n );
1126 Node *has_local_phi_input( Node *n );
1127 // Mark an IfNode as being dominated by a prior test,
1128 // without actually altering the CFG (and hence IDOM info).
1129 void dominated_by( Node *prevdom, Node *iff, bool flip = false, bool exclude_loop_predicate = false );
1130
1131 // Split Node 'n' through merge point
1132 Node *split_thru_region( Node *n, Node *region );
1133 // Split Node 'n' through merge point if there is enough win.
1134 Node *split_thru_phi( Node *n, Node *region, int policy );
1135 // Found an If getting its condition-code input from a Phi in the
1136 // same block. Split thru the Region.
1137 void do_split_if( Node *iff );
1138
1139 // Conversion of fill/copy patterns into intrisic versions
1140 bool do_intrinsify_fill();
1141 bool intrinsify_fill(IdealLoopTree* lpt);
1142 bool match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value,
1143 Node*& shift, Node*& offset);
1144
1145 private:
1146 // Return a type based on condition control flow
1147 const TypeInt* filtered_type( Node *n, Node* n_ctrl);
1148 const TypeInt* filtered_type( Node *n ) { return filtered_type(n, NULL); }
1149 // Helpers for filtered type
1150 const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl);
1151
1152 // Helper functions
1153 Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache );
1154 Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true );
1155 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 );
1156 bool split_up( Node *n, Node *blk1, Node *blk2 );
1157 void sink_use( Node *use, Node *post_loop );
1158 Node *place_near_use( Node *useblock ) const;
1159 Node* try_move_store_before_loop(Node* n, Node *n_ctrl);
1160 void try_move_store_after_loop(Node* n);
1161 bool identical_backtoback_ifs(Node *n);
1162 bool can_split_if(Node *n_ctrl);
1163
1164 bool _created_loop_node;
1165 public:
1166 void set_created_loop_node() { _created_loop_node = true; }
1167 bool created_loop_node() { return _created_loop_node; }
1168 void register_new_node( Node *n, Node *blk );
1169
1170 #ifdef ASSERT
1171 void dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA);
1172 #endif
1173
1174 #ifndef PRODUCT
1175 void dump( ) const;
1176 void dump( IdealLoopTree *loop, uint rpo_idx, Node_List &rpo_list ) const;
1177 void rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const;
1178 void verify() const; // Major slow :-)
1179 void verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const;
1180 IdealLoopTree *get_loop_idx(Node* n) const {
1181 // Dead nodes have no loop, so return the top level loop instead
1182 return _nodes[n->_idx] ? (IdealLoopTree*)_nodes[n->_idx] : _ltree_root;
1183 }
1184 // Print some stats
1185 static void print_statistics();
1186 static int _loop_invokes; // Count of PhaseIdealLoop invokes
1187 static int _loop_work; // Sum of PhaseIdealLoop x _unique
1188 #endif
1189 };
1190
1191 // This kit may be used for making of a reserved copy of a loop before this loop
1192 // goes under non-reversible changes.
1193 //
1194 // Function create_reserve() creates a reserved copy (clone) of the loop.
1195 // The reserved copy is created by calling
1196 // PhaseIdealLoop::create_reserve_version_of_loop - see there how
1197 // the original and reserved loops are connected in the outer graph.
1198 // If create_reserve succeeded, it returns 'true' and _has_reserved is set to 'true'.
1199 //
1200 // By default the reserved copy (clone) of the loop is created as dead code - it is
1201 // dominated in the outer loop by this node chain:
1202 // intcon(1)->If->IfFalse->reserved_copy.
1203 // The original loop is dominated by the the same node chain but IfTrue projection:
1204 // intcon(0)->If->IfTrue->original_loop.
1205 //
1206 // In this implementation of CountedLoopReserveKit the ctor includes create_reserve()
1207 // and the dtor, checks _use_new value.
1208 // If _use_new == false, it "switches" control to reserved copy of the loop
1209 // by simple replacing of node intcon(1) with node intcon(0).
1210 //
1211 // Here is a proposed example of usage (see also SuperWord::output in superword.cpp).
1212 //
1213 // void CountedLoopReserveKit_example()
1214 // {
1215 // CountedLoopReserveKit lrk((phase, lpt, DoReserveCopy = true); // create local object
1216 // if (DoReserveCopy && !lrk.has_reserved()) {
1217 // return; //failed to create reserved loop copy
1218 // }
1219 // ...
1220 // //something is wrong, switch to original loop
1221 /// if(something_is_wrong) return; // ~CountedLoopReserveKit makes the switch
1222 // ...
1223 // //everything worked ok, return with the newly modified loop
1224 // lrk.use_new();
1225 // return; // ~CountedLoopReserveKit does nothing once use_new() was called
1226 // }
1227 //
1228 // Keep in mind, that by default if create_reserve() is not followed by use_new()
1229 // the dtor will "switch to the original" loop.
1230 // NOTE. You you modify outside of the original loop this class is no help.
1231 //
1232 class CountedLoopReserveKit {
1233 private:
1234 PhaseIdealLoop* _phase;
1235 IdealLoopTree* _lpt;
1236 LoopNode* _lp;
1237 IfNode* _iff;
1238 LoopNode* _lp_reserved;
1239 bool _has_reserved;
1240 bool _use_new;
1241 const bool _active; //may be set to false in ctor, then the object is dummy
1242
1243 public:
1244 CountedLoopReserveKit(PhaseIdealLoop* phase, IdealLoopTree *loop, bool active);
1245 ~CountedLoopReserveKit();
1246 void use_new() {_use_new = true;}
1247 void set_iff(IfNode* x) {_iff = x;}
1248 bool has_reserved() const { return _active && _has_reserved;}
1249 private:
1250 bool create_reserve();
1251 };// class CountedLoopReserveKit
1252
1253 inline Node* IdealLoopTree::tail() {
1254 // Handle lazy update of _tail field
1255 Node *n = _tail;
1256 //while( !n->in(0) ) // Skip dead CFG nodes
1257 //n = n->in(1);
1258 if (n->in(0) == NULL)
1259 n = _phase->get_ctrl(n);
1260 _tail = n;
1261 return n;
1262 }
1263
1264
1265 // Iterate over the loop tree using a preorder, left-to-right traversal.
1266 //
1267 // Example that visits all counted loops from within PhaseIdealLoop
1268 //
1269 // for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
1270 // IdealLoopTree* lpt = iter.current();
1271 // if (!lpt->is_counted()) continue;
1272 // ...
1273 class LoopTreeIterator : public StackObj {
1274 private:
1275 IdealLoopTree* _root;
1276 IdealLoopTree* _curnt;
1277
1278 public:
1279 LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {}
1280
1281 bool done() { return _curnt == NULL; } // Finished iterating?
1282
1283 void next(); // Advance to next loop tree
1284
1285 IdealLoopTree* current() { return _curnt; } // Return current value of iterator.
1286 };
1287
1288 #endif // SHARE_VM_OPTO_LOOPNODE_HPP