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