1 /*
2 * Copyright (c) 1998, 2017, 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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13 * accompanied this code).
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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 VectorSet;
42 class Invariance;
43 struct small_cache;
44
45 //
46 // I D E A L I Z E D L O O P S
47 //
48 // Idealized loops are the set of loops I perform more interesting
49 // transformations on, beyond simple hoisting.
50
51 //------------------------------LoopNode---------------------------------------
52 // Simple loop header. Fall in path on left, loop-back path on right.
53 class LoopNode : public RegionNode {
54 // Size is bigger to hold the flags. However, the flags do not change
55 // the semantics so it does not appear in the hash & cmp functions.
56 virtual uint size_of() const { return sizeof(*this); }
57 protected:
58 short _loop_flags;
59 // Names for flag bitfields
60 enum { Normal=0, Pre=1, Main=2, Post=3, PreMainPostFlagsMask=3,
61 MainHasNoPreLoop=4,
62 HasExactTripCount=8,
63 InnerLoop=16,
64 PartialPeelLoop=32,
65 PartialPeelFailed=64 };
66 char _unswitch_count;
67 enum { _unswitch_max=3 };
68
69 public:
70 // Names for edge indices
71 enum { Self=0, EntryControl, LoopBackControl };
72
73 int is_inner_loop() const { return _loop_flags & InnerLoop; }
74 void set_inner_loop() { _loop_flags |= InnerLoop; }
75
76 int is_partial_peel_loop() const { return _loop_flags & PartialPeelLoop; }
77 void set_partial_peel_loop() { _loop_flags |= PartialPeelLoop; }
78 int partial_peel_has_failed() const { return _loop_flags & PartialPeelFailed; }
79 void mark_partial_peel_failed() { _loop_flags |= PartialPeelFailed; }
80
81 int unswitch_max() { return _unswitch_max; }
82 int unswitch_count() { return _unswitch_count; }
83 void set_unswitch_count(int val) {
84 assert (val <= unswitch_max(), "too many unswitches");
85 _unswitch_count = val;
86 }
87
88 LoopNode( Node *entry, Node *backedge ) : RegionNode(3), _loop_flags(0), _unswitch_count(0) {
89 init_class_id(Class_Loop);
90 init_req(EntryControl, entry);
91 init_req(LoopBackControl, backedge);
92 }
93
94 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
95 virtual int Opcode() const;
96 bool can_be_counted_loop(PhaseTransform* phase) const {
97 return req() == 3 && in(0) != NULL &&
98 in(1) != NULL && phase->type(in(1)) != Type::TOP &&
99 in(2) != NULL && phase->type(in(2)) != Type::TOP;
100 }
101 bool is_valid_counted_loop() const;
102 #ifndef PRODUCT
103 virtual void dump_spec(outputStream *st) const;
104 #endif
105 };
106
107 //------------------------------Counted Loops----------------------------------
108 // Counted loops are all trip-counted loops, with exactly 1 trip-counter exit
109 // path (and maybe some other exit paths). The trip-counter exit is always
110 // last in the loop. The trip-counter have to stride by a constant;
111 // the exit value is also loop invariant.
112
113 // CountedLoopNodes and CountedLoopEndNodes come in matched pairs. The
114 // CountedLoopNode has the incoming loop control and the loop-back-control
115 // which is always the IfTrue before the matching CountedLoopEndNode. The
116 // CountedLoopEndNode has an incoming control (possibly not the
117 // CountedLoopNode if there is control flow in the loop), the post-increment
118 // trip-counter value, and the limit. The trip-counter value is always of
119 // the form (Op old-trip-counter stride). The old-trip-counter is produced
120 // by a Phi connected to the CountedLoopNode. The stride is constant.
121 // The Op is any commutable opcode, including Add, Mul, Xor. The
122 // CountedLoopEndNode also takes in the loop-invariant limit value.
123
124 // From a CountedLoopNode I can reach the matching CountedLoopEndNode via the
125 // loop-back control. From CountedLoopEndNodes I can reach CountedLoopNodes
126 // via the old-trip-counter from the Op node.
127
128 //------------------------------CountedLoopNode--------------------------------
129 // CountedLoopNodes head simple counted loops. CountedLoopNodes have as
130 // inputs the incoming loop-start control and the loop-back control, so they
131 // act like RegionNodes. They also take in the initial trip counter, the
132 // loop-invariant stride and the loop-invariant limit value. CountedLoopNodes
133 // produce a loop-body control and the trip counter value. Since
134 // CountedLoopNodes behave like RegionNodes I still have a standard CFG model.
135
136 class CountedLoopNode : public LoopNode {
137 // Size is bigger to hold _main_idx. However, _main_idx does not change
138 // the semantics so it does not appear in the hash & cmp functions.
139 virtual uint size_of() const { return sizeof(*this); }
140
141 // For Pre- and Post-loops during debugging ONLY, this holds the index of
142 // the Main CountedLoop. Used to assert that we understand the graph shape.
143 node_idx_t _main_idx;
144
145 // Known trip count calculated by compute_exact_trip_count()
146 uint _trip_count;
147
148 // Expected trip count from profile data
149 float _profile_trip_cnt;
150
151 // Log2 of original loop bodies in unrolled loop
152 int _unrolled_count_log2;
153
154 // Node count prior to last unrolling - used to decide if
155 // unroll,optimize,unroll,optimize,... is making progress
156 int _node_count_before_unroll;
157
158 public:
159 CountedLoopNode( Node *entry, Node *backedge )
160 : LoopNode(entry, backedge), _main_idx(0), _trip_count(max_juint),
161 _profile_trip_cnt(COUNT_UNKNOWN), _unrolled_count_log2(0),
162 _node_count_before_unroll(0) {
163 init_class_id(Class_CountedLoop);
164 // Initialize _trip_count to the largest possible value.
165 // Will be reset (lower) if the loop's trip count is known.
166 }
167
168 virtual int Opcode() const;
169 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
170
171 Node *init_control() const { return in(EntryControl); }
172 Node *back_control() const { return in(LoopBackControl); }
173 CountedLoopEndNode *loopexit() const;
174 Node *init_trip() const;
175 Node *stride() const;
176 int stride_con() const;
177 bool stride_is_con() const;
178 Node *limit() const;
179 Node *incr() const;
180 Node *phi() const;
181
182 // Match increment with optional truncation
183 static Node* match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type);
184
185 // A 'main' loop has a pre-loop and a post-loop. The 'main' loop
186 // can run short a few iterations and may start a few iterations in.
187 // It will be RCE'd and unrolled and aligned.
188
189 // A following 'post' loop will run any remaining iterations. Used
190 // during Range Check Elimination, the 'post' loop will do any final
191 // iterations with full checks. Also used by Loop Unrolling, where
192 // the 'post' loop will do any epilog iterations needed. Basically,
193 // a 'post' loop can not profitably be further unrolled or RCE'd.
194
195 // A preceding 'pre' loop will run at least 1 iteration (to do peeling),
196 // it may do under-flow checks for RCE and may do alignment iterations
197 // so the following main loop 'knows' that it is striding down cache
198 // lines.
199
200 // A 'main' loop that is ONLY unrolled or peeled, never RCE'd or
201 // Aligned, may be missing it's pre-loop.
202 int is_normal_loop() const { return (_loop_flags&PreMainPostFlagsMask) == Normal; }
203 int is_pre_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Pre; }
204 int is_main_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Main; }
205 int is_post_loop () const { return (_loop_flags&PreMainPostFlagsMask) == Post; }
206 int is_main_no_pre_loop() const { return _loop_flags & MainHasNoPreLoop; }
207 void set_main_no_pre_loop() { _loop_flags |= MainHasNoPreLoop; }
208
209 int main_idx() const { return _main_idx; }
210
211
212 void set_pre_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; }
213 void set_main_loop ( ) { assert(is_normal_loop(),""); _loop_flags |= Main; }
214 void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; }
215 void set_normal_loop( ) { _loop_flags &= ~PreMainPostFlagsMask; }
216
217 void set_trip_count(uint tc) { _trip_count = tc; }
218 uint trip_count() { return _trip_count; }
219
220 bool has_exact_trip_count() const { return (_loop_flags & HasExactTripCount) != 0; }
221 void set_exact_trip_count(uint tc) {
222 _trip_count = tc;
223 _loop_flags |= HasExactTripCount;
224 }
225 void set_nonexact_trip_count() {
226 _loop_flags &= ~HasExactTripCount;
227 }
228
229 void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; }
230 float profile_trip_cnt() { return _profile_trip_cnt; }
231
232 void double_unrolled_count() { _unrolled_count_log2++; }
233 int unrolled_count() { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); }
234
235 void set_node_count_before_unroll(int ct) { _node_count_before_unroll = ct; }
236 int node_count_before_unroll() { return _node_count_before_unroll; }
237
238 #ifndef PRODUCT
239 virtual void dump_spec(outputStream *st) const;
240 #endif
241 };
242
243 //------------------------------CountedLoopEndNode-----------------------------
244 // CountedLoopEndNodes end simple trip counted loops. They act much like
245 // IfNodes.
246 class CountedLoopEndNode : public IfNode {
247 public:
248 enum { TestControl, TestValue };
249
250 CountedLoopEndNode( Node *control, Node *test, float prob, float cnt )
251 : IfNode( control, test, prob, cnt) {
252 init_class_id(Class_CountedLoopEnd);
253 }
254 virtual int Opcode() const;
255
256 Node *cmp_node() const { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : NULL; }
257 Node *incr() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; }
258 Node *limit() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; }
259 Node *stride() const { Node *tmp = incr (); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; }
260 Node *init_trip() const { Node *tmp = phi (); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; }
261 int stride_con() const;
262 bool stride_is_con() const { Node *tmp = stride (); return (tmp != NULL && tmp->is_Con()); }
263 BoolTest::mask test_trip() const { return in(TestValue)->as_Bool()->_test._test; }
264 PhiNode *phi() const {
265 Node *tmp = incr();
266 if (tmp && tmp->req() == 3) {
267 Node* phi = tmp->in(1);
268 if (phi->is_Phi()) {
269 return phi->as_Phi();
270 }
271 }
272 return NULL;
273 }
274 CountedLoopNode *loopnode() const {
275 // The CountedLoopNode that goes with this CountedLoopEndNode may
276 // have been optimized out by the IGVN so be cautious with the
277 // pattern matching on the graph
278 PhiNode* iv_phi = phi();
279 if (iv_phi == NULL) {
280 return NULL;
281 }
282 assert(iv_phi->is_Phi(), "should be PhiNode");
283 Node *ln = iv_phi->in(0);
284 if (ln->is_CountedLoop() && ln->as_CountedLoop()->loopexit() == this) {
285 return (CountedLoopNode*)ln;
286 }
287 return NULL;
288 }
289
290 #ifndef PRODUCT
291 virtual void dump_spec(outputStream *st) const;
292 #endif
293 };
294
295
296 inline CountedLoopEndNode *CountedLoopNode::loopexit() const {
297 Node *bc = back_control();
298 if( bc == NULL ) return NULL;
299 Node *le = bc->in(0);
300 if( le->Opcode() != Op_CountedLoopEnd )
301 return NULL;
302 return (CountedLoopEndNode*)le;
303 }
304 inline Node *CountedLoopNode::init_trip() const { return loopexit() ? loopexit()->init_trip() : NULL; }
305 inline Node *CountedLoopNode::stride() const { return loopexit() ? loopexit()->stride() : NULL; }
306 inline int CountedLoopNode::stride_con() const { return loopexit() ? loopexit()->stride_con() : 0; }
307 inline bool CountedLoopNode::stride_is_con() const { return loopexit() && loopexit()->stride_is_con(); }
308 inline Node *CountedLoopNode::limit() const { return loopexit() ? loopexit()->limit() : NULL; }
309 inline Node *CountedLoopNode::incr() const { return loopexit() ? loopexit()->incr() : NULL; }
310 inline Node *CountedLoopNode::phi() const { return loopexit() ? loopexit()->phi() : NULL; }
311
312 //------------------------------LoopLimitNode-----------------------------
313 // Counted Loop limit node which represents exact final iterator value:
314 // trip_count = (limit - init_trip + stride - 1)/stride
315 // final_value= trip_count * stride + init_trip.
316 // Use HW instructions to calculate it when it can overflow in integer.
317 // Note, final_value should fit into integer since counted loop has
318 // limit check: limit <= max_int-stride.
319 class LoopLimitNode : public Node {
320 enum { Init=1, Limit=2, Stride=3 };
321 public:
322 LoopLimitNode( Compile* C, Node *init, Node *limit, Node *stride ) : Node(0,init,limit,stride) {
323 // Put it on the Macro nodes list to optimize during macro nodes expansion.
324 init_flags(Flag_is_macro);
325 C->add_macro_node(this);
326 }
327 virtual int Opcode() const;
328 virtual const Type *bottom_type() const { return TypeInt::INT; }
329 virtual uint ideal_reg() const { return Op_RegI; }
330 virtual const Type *Value( PhaseTransform *phase ) const;
331 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
332 virtual Node *Identity( PhaseTransform *phase );
333 };
334
335 // -----------------------------IdealLoopTree----------------------------------
336 class IdealLoopTree : public ResourceObj {
337 public:
338 IdealLoopTree *_parent; // Parent in loop tree
339 IdealLoopTree *_next; // Next sibling in loop tree
340 IdealLoopTree *_child; // First child in loop tree
341
342 // The head-tail backedge defines the loop.
343 // If tail is NULL then this loop has multiple backedges as part of the
344 // same loop. During cleanup I'll peel off the multiple backedges; merge
345 // them at the loop bottom and flow 1 real backedge into the loop.
346 Node *_head; // Head of loop
347 Node *_tail; // Tail of loop
348 inline Node *tail(); // Handle lazy update of _tail field
349 PhaseIdealLoop* _phase;
350
351 Node_List _body; // Loop body for inner loops
352
353 uint8 _nest; // Nesting depth
354 uint8 _irreducible:1, // True if irreducible
355 _has_call:1, // True if has call safepoint
356 _has_sfpt:1, // True if has non-call safepoint
357 _rce_candidate:1; // True if candidate for range check elimination
358
359 Node_List* _safepts; // List of safepoints in this loop
360 Node_List* _required_safept; // A inner loop cannot delete these safepts;
361 bool _allow_optimizations; // Allow loop optimizations
362
363 IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail )
364 : _parent(0), _next(0), _child(0),
365 _head(head), _tail(tail),
366 _phase(phase),
367 _safepts(NULL),
368 _required_safept(NULL),
369 _allow_optimizations(true),
370 _nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0)
371 { }
372
373 // Is 'l' a member of 'this'?
374 int is_member( const IdealLoopTree *l ) const; // Test for nested membership
375
376 // Set loop nesting depth. Accumulate has_call bits.
377 int set_nest( uint depth );
378
379 // Split out multiple fall-in edges from the loop header. Move them to a
380 // private RegionNode before the loop. This becomes the loop landing pad.
381 void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt );
382
383 // Split out the outermost loop from this shared header.
384 void split_outer_loop( PhaseIdealLoop *phase );
385
386 // Merge all the backedges from the shared header into a private Region.
387 // Feed that region as the one backedge to this loop.
388 void merge_many_backedges( PhaseIdealLoop *phase );
389
390 // Split shared headers and insert loop landing pads.
391 // Insert a LoopNode to replace the RegionNode.
392 // Returns TRUE if loop tree is structurally changed.
393 bool beautify_loops( PhaseIdealLoop *phase );
394
395 // Perform optimization to use the loop predicates for null checks and range checks.
396 // Applies to any loop level (not just the innermost one)
397 bool loop_predication( PhaseIdealLoop *phase);
398
399 // Perform iteration-splitting on inner loops. Split iterations to
400 // avoid range checks or one-shot null checks. Returns false if the
401 // current round of loop opts should stop.
402 bool iteration_split( PhaseIdealLoop *phase, Node_List &old_new );
403
404 // Driver for various flavors of iteration splitting. Returns false
405 // if the current round of loop opts should stop.
406 bool iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new );
407
408 // Given dominators, try to find loops with calls that must always be
409 // executed (call dominates loop tail). These loops do not need non-call
410 // safepoints (ncsfpt).
411 void check_safepts(VectorSet &visited, Node_List &stack);
412
413 // Allpaths backwards scan from loop tail, terminating each path at first safepoint
414 // encountered.
415 void allpaths_check_safepts(VectorSet &visited, Node_List &stack);
416
417 // Remove safepoints from loop. Optionally keeping one.
418 void remove_safepoints(PhaseIdealLoop* phase, bool keep_one);
419
420 // Convert to counted loops where possible
421 void counted_loop( PhaseIdealLoop *phase );
422
423 // Check for Node being a loop-breaking test
424 Node *is_loop_exit(Node *iff) const;
425
426 // Returns true if ctrl is executed on every complete iteration
427 bool dominates_backedge(Node* ctrl);
428
429 // Remove simplistic dead code from loop body
430 void DCE_loop_body();
431
432 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage.
433 // Replace with a 1-in-10 exit guess.
434 void adjust_loop_exit_prob( PhaseIdealLoop *phase );
435
436 // Return TRUE or FALSE if the loop should never be RCE'd or aligned.
437 // Useful for unrolling loops with NO array accesses.
438 bool policy_peel_only( PhaseIdealLoop *phase ) const;
439
440 // Return TRUE or FALSE if the loop should be unswitched -- clone
441 // loop with an invariant test
442 bool policy_unswitching( PhaseIdealLoop *phase ) const;
443
444 // Micro-benchmark spamming. Remove empty loops.
445 bool policy_do_remove_empty_loop( PhaseIdealLoop *phase );
446
447 // Convert one iteration loop into normal code.
448 bool policy_do_one_iteration_loop( PhaseIdealLoop *phase );
449
450 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can
451 // make some loop-invariant test (usually a null-check) happen before the
452 // loop.
453 bool policy_peeling( PhaseIdealLoop *phase ) const;
454
455 // Return TRUE or FALSE if the loop should be maximally unrolled. Stash any
456 // known trip count in the counted loop node.
457 bool policy_maximally_unroll( PhaseIdealLoop *phase ) const;
458
459 // Return TRUE or FALSE if the loop should be unrolled or not. Unroll if
460 // the loop is a CountedLoop and the body is small enough.
461 bool policy_unroll( PhaseIdealLoop *phase ) const;
462
463 // Return TRUE or FALSE if the loop should be range-check-eliminated.
464 // Gather a list of IF tests that are dominated by iteration splitting;
465 // also gather the end of the first split and the start of the 2nd split.
466 bool policy_range_check( PhaseIdealLoop *phase ) const;
467
468 // Return TRUE or FALSE if the loop should be cache-line aligned.
469 // Gather the expression that does the alignment. Note that only
470 // one array base can be aligned in a loop (unless the VM guarantees
471 // mutual alignment). Note that if we vectorize short memory ops
472 // into longer memory ops, we may want to increase alignment.
473 bool policy_align( PhaseIdealLoop *phase ) const;
474
475 // Return TRUE if "iff" is a range check.
476 bool is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const;
477
478 // Compute loop exact trip count if possible
479 void compute_exact_trip_count( PhaseIdealLoop *phase );
480
481 // Compute loop trip count from profile data
482 void compute_profile_trip_cnt( PhaseIdealLoop *phase );
483
484 // Reassociate invariant expressions.
485 void reassociate_invariants(PhaseIdealLoop *phase);
486 // Reassociate invariant add and subtract expressions.
487 Node* reassociate_add_sub(Node* n1, PhaseIdealLoop *phase);
488 // Return nonzero index of invariant operand if invariant and variant
489 // are combined with an Add or Sub. Helper for reassociate_invariants.
490 int is_invariant_addition(Node* n, PhaseIdealLoop *phase);
491
492 // Return true if n is invariant
493 bool is_invariant(Node* n) const;
494
495 // Put loop body on igvn work list
496 void record_for_igvn();
497
498 bool is_loop() { return !_irreducible && _tail && !_tail->is_top(); }
499 bool is_inner() { return is_loop() && _child == NULL; }
500 bool is_counted() { return is_loop() && _head != NULL && _head->is_CountedLoop(); }
501
502 #ifndef PRODUCT
503 void dump_head( ) const; // Dump loop head only
504 void dump() const; // Dump this loop recursively
505 void verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const;
506 #endif
507
508 };
509
510 // -----------------------------PhaseIdealLoop---------------------------------
511 // Computes the mapping from Nodes to IdealLoopTrees. Organizes IdealLoopTrees into a
512 // loop tree. Drives the loop-based transformations on the ideal graph.
513 class PhaseIdealLoop : public PhaseTransform {
514 friend class IdealLoopTree;
515 friend class SuperWord;
516 // Pre-computed def-use info
517 PhaseIterGVN &_igvn;
518
519 // Head of loop tree
520 IdealLoopTree *_ltree_root;
521
522 // Array of pre-order numbers, plus post-visited bit.
523 // ZERO for not pre-visited. EVEN for pre-visited but not post-visited.
524 // ODD for post-visited. Other bits are the pre-order number.
525 uint *_preorders;
526 uint _max_preorder;
527
528 const PhaseIdealLoop* _verify_me;
529 bool _verify_only;
530
531 // Allocate _preorders[] array
532 void allocate_preorders() {
533 _max_preorder = C->unique()+8;
534 _preorders = NEW_RESOURCE_ARRAY(uint, _max_preorder);
535 memset(_preorders, 0, sizeof(uint) * _max_preorder);
536 }
537
538 // Allocate _preorders[] array
539 void reallocate_preorders() {
540 if ( _max_preorder < C->unique() ) {
541 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique());
542 _max_preorder = C->unique();
543 }
544 memset(_preorders, 0, sizeof(uint) * _max_preorder);
545 }
546
547 // Check to grow _preorders[] array for the case when build_loop_tree_impl()
548 // adds new nodes.
549 void check_grow_preorders( ) {
550 if ( _max_preorder < C->unique() ) {
551 uint newsize = _max_preorder<<1; // double size of array
552 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize);
553 memset(&_preorders[_max_preorder],0,sizeof(uint)*(newsize-_max_preorder));
554 _max_preorder = newsize;
555 }
556 }
557 // Check for pre-visited. Zero for NOT visited; non-zero for visited.
558 int is_visited( Node *n ) const { return _preorders[n->_idx]; }
559 // Pre-order numbers are written to the Nodes array as low-bit-set values.
560 void set_preorder_visited( Node *n, int pre_order ) {
561 assert( !is_visited( n ), "already set" );
562 _preorders[n->_idx] = (pre_order<<1);
563 };
564 // Return pre-order number.
565 int get_preorder( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]>>1; }
566
567 // Check for being post-visited.
568 // Should be previsited already (checked with assert(is_visited(n))).
569 int is_postvisited( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]&1; }
570
571 // Mark as post visited
572 void set_postvisited( Node *n ) { assert( !is_postvisited( n ), "" ); _preorders[n->_idx] |= 1; }
573
574 // Set/get control node out. Set lower bit to distinguish from IdealLoopTree
575 // Returns true if "n" is a data node, false if it's a control node.
576 bool has_ctrl( Node *n ) const { return ((intptr_t)_nodes[n->_idx]) & 1; }
577
578 // clear out dead code after build_loop_late
579 Node_List _deadlist;
580
581 // Support for faster execution of get_late_ctrl()/dom_lca()
582 // when a node has many uses and dominator depth is deep.
583 Node_Array _dom_lca_tags;
584 void init_dom_lca_tags();
585 void clear_dom_lca_tags();
586
587 // Helper for debugging bad dominance relationships
588 bool verify_dominance(Node* n, Node* use, Node* LCA, Node* early);
589
590 Node* compute_lca_of_uses(Node* n, Node* early, bool verify = false);
591
592 // Inline wrapper for frequent cases:
593 // 1) only one use
594 // 2) a use is the same as the current LCA passed as 'n1'
595 Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) {
596 assert( n->is_CFG(), "" );
597 // Fast-path NULL lca
598 if( lca != NULL && lca != n ) {
599 assert( lca->is_CFG(), "" );
600 // find LCA of all uses
601 n = dom_lca_for_get_late_ctrl_internal( lca, n, tag );
602 }
603 return find_non_split_ctrl(n);
604 }
605 Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag );
606
607 // Helper function for directing control inputs away from CFG split
608 // points.
609 Node *find_non_split_ctrl( Node *ctrl ) const {
610 if (ctrl != NULL) {
611 if (ctrl->is_MultiBranch()) {
612 ctrl = ctrl->in(0);
613 }
614 assert(ctrl->is_CFG(), "CFG");
615 }
616 return ctrl;
617 }
618
619 bool cast_incr_before_loop(Node* incr, Node* ctrl, Node* loop);
620
621 public:
622 bool has_node( Node* n ) const {
623 guarantee(n != NULL, "No Node.");
624 return _nodes[n->_idx] != NULL;
625 }
626 // check if transform created new nodes that need _ctrl recorded
627 Node *get_late_ctrl( Node *n, Node *early );
628 Node *get_early_ctrl( Node *n );
629 Node *get_early_ctrl_for_expensive(Node *n, Node* earliest);
630 void set_early_ctrl( Node *n );
631 void set_subtree_ctrl( Node *root );
632 void set_ctrl( Node *n, Node *ctrl ) {
633 assert( !has_node(n) || has_ctrl(n), "" );
634 assert( ctrl->in(0), "cannot set dead control node" );
635 assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" );
636 _nodes.map( n->_idx, (Node*)((intptr_t)ctrl + 1) );
637 }
638 // Set control and update loop membership
639 void set_ctrl_and_loop(Node* n, Node* ctrl) {
640 IdealLoopTree* old_loop = get_loop(get_ctrl(n));
641 IdealLoopTree* new_loop = get_loop(ctrl);
642 if (old_loop != new_loop) {
643 if (old_loop->_child == NULL) old_loop->_body.yank(n);
644 if (new_loop->_child == NULL) new_loop->_body.push(n);
645 }
646 set_ctrl(n, ctrl);
647 }
648 // Control nodes can be replaced or subsumed. During this pass they
649 // get their replacement Node in slot 1. Instead of updating the block
650 // location of all Nodes in the subsumed block, we lazily do it. As we
651 // pull such a subsumed block out of the array, we write back the final
652 // correct block.
653 Node *get_ctrl( Node *i ) {
654 assert(has_node(i), "");
655 Node *n = get_ctrl_no_update(i);
656 _nodes.map( i->_idx, (Node*)((intptr_t)n + 1) );
657 assert(has_node(i) && has_ctrl(i), "");
658 assert(n == find_non_split_ctrl(n), "must return legal ctrl" );
659 return n;
660 }
661 // true if CFG node d dominates CFG node n
662 bool is_dominator(Node *d, Node *n);
663 // return get_ctrl for a data node and self(n) for a CFG node
664 Node* ctrl_or_self(Node* n) {
665 if (has_ctrl(n))
666 return get_ctrl(n);
667 else {
668 assert (n->is_CFG(), "must be a CFG node");
669 return n;
670 }
671 }
672
673 private:
674 Node *get_ctrl_no_update_helper(Node *i) const {
675 assert(has_ctrl(i), "should be control, not loop");
676 return (Node*)(((intptr_t)_nodes[i->_idx]) & ~1);
677 }
678
679 Node *get_ctrl_no_update(Node *i) const {
680 assert( has_ctrl(i), "" );
681 Node *n = get_ctrl_no_update_helper(i);
682 if (!n->in(0)) {
683 // Skip dead CFG nodes
684 do {
685 n = get_ctrl_no_update_helper(n);
686 } while (!n->in(0));
687 n = find_non_split_ctrl(n);
688 }
689 return n;
690 }
691
692 // Check for loop being set
693 // "n" must be a control node. Returns true if "n" is known to be in a loop.
694 bool has_loop( Node *n ) const {
695 assert(!has_node(n) || !has_ctrl(n), "");
696 return has_node(n);
697 }
698 // Set loop
699 void set_loop( Node *n, IdealLoopTree *loop ) {
700 _nodes.map(n->_idx, (Node*)loop);
701 }
702 // Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms. Replace
703 // the 'old_node' with 'new_node'. Kill old-node. Add a reference
704 // from old_node to new_node to support the lazy update. Reference
705 // replaces loop reference, since that is not needed for dead node.
706 public:
707 void lazy_update(Node *old_node, Node *new_node) {
708 assert(old_node != new_node, "no cycles please");
709 // Re-use the side array slot for this node to provide the
710 // forwarding pointer.
711 _nodes.map(old_node->_idx, (Node*)((intptr_t)new_node + 1));
712 }
713 void lazy_replace(Node *old_node, Node *new_node) {
714 _igvn.replace_node(old_node, new_node);
715 lazy_update(old_node, new_node);
716 }
717
718 private:
719
720 // Place 'n' in some loop nest, where 'n' is a CFG node
721 void build_loop_tree();
722 int build_loop_tree_impl( Node *n, int pre_order );
723 // Insert loop into the existing loop tree. 'innermost' is a leaf of the
724 // loop tree, not the root.
725 IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost );
726
727 // Place Data nodes in some loop nest
728 void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
729 void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
730 void build_loop_late_post ( Node* n );
731
732 // Array of immediate dominance info for each CFG node indexed by node idx
733 private:
734 uint _idom_size;
735 Node **_idom; // Array of immediate dominators
736 uint *_dom_depth; // Used for fast LCA test
737 GrowableArray<uint>* _dom_stk; // For recomputation of dom depth
738
739 Node* idom_no_update(Node* d) const {
740 assert(d->_idx < _idom_size, "oob");
741 Node* n = _idom[d->_idx];
742 assert(n != NULL,"Bad immediate dominator info.");
743 while (n->in(0) == NULL) { // Skip dead CFG nodes
744 //n = n->in(1);
745 n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1);
746 assert(n != NULL,"Bad immediate dominator info.");
747 }
748 return n;
749 }
750 Node *idom(Node* d) const {
751 uint didx = d->_idx;
752 Node *n = idom_no_update(d);
753 _idom[didx] = n; // Lazily remove dead CFG nodes from table.
754 return n;
755 }
756 uint dom_depth(Node* d) const {
757 guarantee(d != NULL, "Null dominator info.");
758 guarantee(d->_idx < _idom_size, "");
759 return _dom_depth[d->_idx];
760 }
761 void set_idom(Node* d, Node* n, uint dom_depth);
762 // Locally compute IDOM using dom_lca call
763 Node *compute_idom( Node *region ) const;
764 // Recompute dom_depth
765 void recompute_dom_depth();
766
767 // Is safept not required by an outer loop?
768 bool is_deleteable_safept(Node* sfpt);
769
770 // Replace parallel induction variable (parallel to trip counter)
771 void replace_parallel_iv(IdealLoopTree *loop);
772
773 // Perform verification that the graph is valid.
774 PhaseIdealLoop( PhaseIterGVN &igvn) :
775 PhaseTransform(Ideal_Loop),
776 _igvn(igvn),
777 _dom_lca_tags(arena()), // Thread::resource_area
778 _verify_me(NULL),
779 _verify_only(true) {
780 build_and_optimize(false, false);
781 }
782
783 // build the loop tree and perform any requested optimizations
784 void build_and_optimize(bool do_split_if, bool skip_loop_opts);
785
786 public:
787 // Dominators for the sea of nodes
788 void Dominators();
789 Node *dom_lca( Node *n1, Node *n2 ) const {
790 return find_non_split_ctrl(dom_lca_internal(n1, n2));
791 }
792 Node *dom_lca_internal( Node *n1, Node *n2 ) const;
793
794 // Compute the Ideal Node to Loop mapping
795 PhaseIdealLoop( PhaseIterGVN &igvn, bool do_split_ifs, bool skip_loop_opts = false) :
796 PhaseTransform(Ideal_Loop),
797 _igvn(igvn),
798 _dom_lca_tags(arena()), // Thread::resource_area
799 _verify_me(NULL),
800 _verify_only(false) {
801 build_and_optimize(do_split_ifs, skip_loop_opts);
802 }
803
804 // Verify that verify_me made the same decisions as a fresh run.
805 PhaseIdealLoop( PhaseIterGVN &igvn, const PhaseIdealLoop *verify_me) :
806 PhaseTransform(Ideal_Loop),
807 _igvn(igvn),
808 _dom_lca_tags(arena()), // Thread::resource_area
809 _verify_me(verify_me),
810 _verify_only(false) {
811 build_and_optimize(false, false);
812 }
813
814 // Build and verify the loop tree without modifying the graph. This
815 // is useful to verify that all inputs properly dominate their uses.
816 static void verify(PhaseIterGVN& igvn) {
817 #ifdef ASSERT
818 PhaseIdealLoop v(igvn);
819 #endif
820 }
821
822 // True if the method has at least 1 irreducible loop
823 bool _has_irreducible_loops;
824
825 // Per-Node transform
826 virtual Node *transform( Node *a_node ) { return 0; }
827
828 bool is_counted_loop( Node *x, IdealLoopTree *loop );
829
830 Node* exact_limit( IdealLoopTree *loop );
831
832 // Return a post-walked LoopNode
833 IdealLoopTree *get_loop( Node *n ) const {
834 // Dead nodes have no loop, so return the top level loop instead
835 if (!has_node(n)) return _ltree_root;
836 assert(!has_ctrl(n), "");
837 return (IdealLoopTree*)_nodes[n->_idx];
838 }
839
840 // Is 'n' a (nested) member of 'loop'?
841 int is_member( const IdealLoopTree *loop, Node *n ) const {
842 return loop->is_member(get_loop(n)); }
843
844 // This is the basic building block of the loop optimizations. It clones an
845 // entire loop body. It makes an old_new loop body mapping; with this
846 // mapping you can find the new-loop equivalent to an old-loop node. All
847 // new-loop nodes are exactly equal to their old-loop counterparts, all
848 // edges are the same. All exits from the old-loop now have a RegionNode
849 // that merges the equivalent new-loop path. This is true even for the
850 // normal "loop-exit" condition. All uses of loop-invariant old-loop values
851 // now come from (one or more) Phis that merge their new-loop equivalents.
852 // Parameter side_by_side_idom:
853 // When side_by_size_idom is NULL, the dominator tree is constructed for
854 // the clone loop to dominate the original. Used in construction of
855 // pre-main-post loop sequence.
856 // When nonnull, the clone and original are side-by-side, both are
857 // dominated by the passed in side_by_side_idom node. Used in
858 // construction of unswitched loops.
859 void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth,
860 Node* side_by_side_idom = NULL);
861
862 // If we got the effect of peeling, either by actually peeling or by
863 // making a pre-loop which must execute at least once, we can remove
864 // all loop-invariant dominated tests in the main body.
865 void peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new );
866
867 // Generate code to do a loop peel for the given loop (and body).
868 // old_new is a temp array.
869 void do_peeling( IdealLoopTree *loop, Node_List &old_new );
870
871 // Add pre and post loops around the given loop. These loops are used
872 // during RCE, unrolling and aligning loops.
873 void insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only );
874 // If Node n lives in the back_ctrl block, we clone a private version of n
875 // in preheader_ctrl block and return that, otherwise return n.
876 Node *clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones );
877
878 // Take steps to maximally unroll the loop. Peel any odd iterations, then
879 // unroll to do double iterations. The next round of major loop transforms
880 // will repeat till the doubled loop body does all remaining iterations in 1
881 // pass.
882 void do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new );
883
884 // Unroll the loop body one step - make each trip do 2 iterations.
885 void do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip );
886
887 // Return true if exp is a constant times an induction var
888 bool is_scaled_iv(Node* exp, Node* iv, int* p_scale);
889
890 // Return true if exp is a scaled induction var plus (or minus) constant
891 bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth = 0);
892
893 // Create a new if above the uncommon_trap_if_pattern for the predicate to be promoted
894 ProjNode* create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry,
895 Deoptimization::DeoptReason reason);
896 void register_control(Node* n, IdealLoopTree *loop, Node* pred);
897
898 // Clone loop predicates to cloned loops (peeled, unswitched)
899 static ProjNode* clone_predicate(ProjNode* predicate_proj, Node* new_entry,
900 Deoptimization::DeoptReason reason,
901 PhaseIdealLoop* loop_phase,
902 PhaseIterGVN* igvn);
903
904 static Node* clone_loop_predicates(Node* old_entry, Node* new_entry,
905 bool clone_limit_check,
906 PhaseIdealLoop* loop_phase,
907 PhaseIterGVN* igvn);
908 Node* clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check);
909
910 static Node* skip_loop_predicates(Node* entry);
911
912 // Find a good location to insert a predicate
913 static ProjNode* find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason);
914 // Find a predicate
915 static Node* find_predicate(Node* entry);
916 // Construct a range check for a predicate if
917 BoolNode* rc_predicate(IdealLoopTree *loop, Node* ctrl,
918 int scale, Node* offset,
919 Node* init, Node* limit, jint stride,
920 Node* range, bool upper, bool &overflow);
921
922 // Implementation of the loop predication to promote checks outside the loop
923 bool loop_predication_impl(IdealLoopTree *loop);
924
925 // Helper function to collect predicate for eliminating the useless ones
926 void collect_potentially_useful_predicates(IdealLoopTree *loop, Unique_Node_List &predicate_opaque1);
927 void eliminate_useless_predicates();
928
929 // Change the control input of expensive nodes to allow commoning by
930 // IGVN when it is guaranteed to not result in a more frequent
931 // execution of the expensive node. Return true if progress.
932 bool process_expensive_nodes();
933
934 // Check whether node has become unreachable
935 bool is_node_unreachable(Node *n) const {
936 return !has_node(n) || n->is_unreachable(_igvn);
937 }
938
939 // Eliminate range-checks and other trip-counter vs loop-invariant tests.
940 void do_range_check( IdealLoopTree *loop, Node_List &old_new );
941
942 // Create a slow version of the loop by cloning the loop
943 // and inserting an if to select fast-slow versions.
944 ProjNode* create_slow_version_of_loop(IdealLoopTree *loop,
945 Node_List &old_new);
946
947 // Clone loop with an invariant test (that does not exit) and
948 // insert a clone of the test that selects which version to
949 // execute.
950 void do_unswitching (IdealLoopTree *loop, Node_List &old_new);
951
952 // Find candidate "if" for unswitching
953 IfNode* find_unswitching_candidate(const IdealLoopTree *loop) const;
954
955 // Range Check Elimination uses this function!
956 // Constrain the main loop iterations so the affine function:
957 // low_limit <= scale_con * I + offset < upper_limit
958 // always holds true. That is, either increase the number of iterations in
959 // the pre-loop or the post-loop until the condition holds true in the main
960 // loop. Scale_con, offset and limit are all loop invariant.
961 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 );
962 // Helper function for add_constraint().
963 Node* adjust_limit(int stride_con, Node * scale, Node *offset, Node *rc_limit, Node *loop_limit, Node *pre_ctrl, bool round_up);
964
965 // Partially peel loop up through last_peel node.
966 bool partial_peel( IdealLoopTree *loop, Node_List &old_new );
967
968 // Create a scheduled list of nodes control dependent on ctrl set.
969 void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched );
970 // Has a use in the vector set
971 bool has_use_in_set( Node* n, VectorSet& vset );
972 // Has use internal to the vector set (ie. not in a phi at the loop head)
973 bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop );
974 // clone "n" for uses that are outside of loop
975 int clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist );
976 // clone "n" for special uses that are in the not_peeled region
977 void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
978 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist );
979 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
980 void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp );
981 #ifdef ASSERT
982 // Validate the loop partition sets: peel and not_peel
983 bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel );
984 // Ensure that uses outside of loop are of the right form
985 bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
986 uint orig_exit_idx, uint clone_exit_idx);
987 bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx);
988 #endif
989
990 // Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.)
991 int stride_of_possible_iv( Node* iff );
992 bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; }
993 // Return the (unique) control output node that's in the loop (if it exists.)
994 Node* stay_in_loop( Node* n, IdealLoopTree *loop);
995 // Insert a signed compare loop exit cloned from an unsigned compare.
996 IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop);
997 void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop);
998 // Utility to register node "n" with PhaseIdealLoop
999 void register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth);
1000 // Utility to create an if-projection
1001 ProjNode* proj_clone(ProjNode* p, IfNode* iff);
1002 // Force the iff control output to be the live_proj
1003 Node* short_circuit_if(IfNode* iff, ProjNode* live_proj);
1004 // Insert a region before an if projection
1005 RegionNode* insert_region_before_proj(ProjNode* proj);
1006 // Insert a new if before an if projection
1007 ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj);
1008
1009 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1010 // "Nearly" because all Nodes have been cloned from the original in the loop,
1011 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1012 // through the Phi recursively, and return a Bool.
1013 BoolNode *clone_iff( PhiNode *phi, IdealLoopTree *loop );
1014 CmpNode *clone_bool( PhiNode *phi, IdealLoopTree *loop );
1015
1016
1017 // Rework addressing expressions to get the most loop-invariant stuff
1018 // moved out. We'd like to do all associative operators, but it's especially
1019 // important (common) to do address expressions.
1020 Node *remix_address_expressions( Node *n );
1021
1022 // Attempt to use a conditional move instead of a phi/branch
1023 Node *conditional_move( Node *n );
1024
1025 // Reorganize offset computations to lower register pressure.
1026 // Mostly prevent loop-fallout uses of the pre-incremented trip counter
1027 // (which are then alive with the post-incremented trip counter
1028 // forcing an extra register move)
1029 void reorg_offsets( IdealLoopTree *loop );
1030
1031 // Check for aggressive application of 'split-if' optimization,
1032 // using basic block level info.
1033 void split_if_with_blocks ( VectorSet &visited, Node_Stack &nstack );
1034 Node *split_if_with_blocks_pre ( Node *n );
1035 void split_if_with_blocks_post( Node *n );
1036 Node *has_local_phi_input( Node *n );
1037 // Mark an IfNode as being dominated by a prior test,
1038 // without actually altering the CFG (and hence IDOM info).
1039 void dominated_by( Node *prevdom, Node *iff, bool flip = false, bool exclude_loop_predicate = false );
1040
1041 // Split Node 'n' through merge point
1042 Node *split_thru_region( Node *n, Node *region );
1043 // Split Node 'n' through merge point if there is enough win.
1044 Node *split_thru_phi( Node *n, Node *region, int policy );
1045 // Found an If getting its condition-code input from a Phi in the
1046 // same block. Split thru the Region.
1047 void do_split_if( Node *iff );
1048
1049 // Conversion of fill/copy patterns into intrisic versions
1050 bool do_intrinsify_fill();
1051 bool intrinsify_fill(IdealLoopTree* lpt);
1052 bool match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value,
1053 Node*& shift, Node*& offset);
1054
1055 private:
1056 // Return a type based on condition control flow
1057 const TypeInt* filtered_type( Node *n, Node* n_ctrl);
1058 const TypeInt* filtered_type( Node *n ) { return filtered_type(n, NULL); }
1059 // Helpers for filtered type
1060 const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl);
1061
1062 // Helper functions
1063 Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache );
1064 Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true );
1065 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 );
1066 bool split_up( Node *n, Node *blk1, Node *blk2 );
1067 void sink_use( Node *use, Node *post_loop );
1068 Node *place_near_use( Node *useblock ) const;
1069
1070 bool _created_loop_node;
1071 public:
1072 void set_created_loop_node() { _created_loop_node = true; }
1073 bool created_loop_node() { return _created_loop_node; }
1074 void register_new_node( Node *n, Node *blk );
1075
1076 #ifdef ASSERT
1077 void dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA);
1078 #endif
1079
1080 #ifndef PRODUCT
1081 void dump( ) const;
1082 void dump( IdealLoopTree *loop, uint rpo_idx, Node_List &rpo_list ) const;
1083 void rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const;
1084 void verify() const; // Major slow :-)
1085 void verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const;
1086 IdealLoopTree *get_loop_idx(Node* n) const {
1087 // Dead nodes have no loop, so return the top level loop instead
1088 return _nodes[n->_idx] ? (IdealLoopTree*)_nodes[n->_idx] : _ltree_root;
1089 }
1090 // Print some stats
1091 static void print_statistics();
1092 static int _loop_invokes; // Count of PhaseIdealLoop invokes
1093 static int _loop_work; // Sum of PhaseIdealLoop x _unique
1094 #endif
1095 };
1096
1097 inline Node* IdealLoopTree::tail() {
1098 // Handle lazy update of _tail field
1099 Node *n = _tail;
1100 //while( !n->in(0) ) // Skip dead CFG nodes
1101 //n = n->in(1);
1102 if (n->in(0) == NULL)
1103 n = _phase->get_ctrl(n);
1104 _tail = n;
1105 return n;
1106 }
1107
1108
1109 // Iterate over the loop tree using a preorder, left-to-right traversal.
1110 //
1111 // Example that visits all counted loops from within PhaseIdealLoop
1112 //
1113 // for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
1114 // IdealLoopTree* lpt = iter.current();
1115 // if (!lpt->is_counted()) continue;
1116 // ...
1117 class LoopTreeIterator : public StackObj {
1118 private:
1119 IdealLoopTree* _root;
1120 IdealLoopTree* _curnt;
1121
1122 public:
1123 LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {}
1124
1125 bool done() { return _curnt == NULL; } // Finished iterating?
1126
1127 void next(); // Advance to next loop tree
1128
1129 IdealLoopTree* current() { return _curnt; } // Return current value of iterator.
1130 };
1131
1132 #endif // SHARE_VM_OPTO_LOOPNODE_HPP