1 /*
2 * Copyright (c) 1998, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "ci/ciMethodData.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "libadt/vectset.hpp"
29 #include "memory/allocation.inline.hpp"
30 #include "opto/addnode.hpp"
31 #include "opto/callnode.hpp"
32 #include "opto/connode.hpp"
33 #include "opto/divnode.hpp"
34 #include "opto/idealGraphPrinter.hpp"
35 #include "opto/loopnode.hpp"
36 #include "opto/mulnode.hpp"
37 #include "opto/rootnode.hpp"
38 #include "opto/superword.hpp"
39
40 //=============================================================================
41 //------------------------------is_loop_iv-------------------------------------
42 // Determine if a node is Counted loop induction variable.
43 // The method is declared in node.hpp.
44 const Node* Node::is_loop_iv() const {
45 if (this->is_Phi() && !this->as_Phi()->is_copy() &&
46 this->as_Phi()->region()->is_CountedLoop() &&
47 this->as_Phi()->region()->as_CountedLoop()->phi() == this) {
48 return this;
49 } else {
50 return NULL;
51 }
52 }
53
54 //=============================================================================
55 //------------------------------dump_spec--------------------------------------
56 // Dump special per-node info
57 #ifndef PRODUCT
58 void LoopNode::dump_spec(outputStream *st) const {
59 if (is_inner_loop()) st->print( "inner " );
60 if (is_partial_peel_loop()) st->print( "partial_peel " );
61 if (partial_peel_has_failed()) st->print( "partial_peel_failed " );
62 }
63 #endif
64
65 //------------------------------is_valid_counted_loop-------------------------
66 bool LoopNode::is_valid_counted_loop() const {
67 if (is_CountedLoop()) {
68 CountedLoopNode* l = as_CountedLoop();
69 CountedLoopEndNode* le = l->loopexit();
70 if (le != NULL &&
71 le->proj_out(1 /* true */) == l->in(LoopNode::LoopBackControl)) {
72 Node* phi = l->phi();
73 Node* exit = le->proj_out(0 /* false */);
74 if (exit != NULL && exit->Opcode() == Op_IfFalse &&
75 phi != NULL && phi->is_Phi() &&
76 phi->in(LoopNode::LoopBackControl) == l->incr() &&
77 le->loopnode() == l && le->stride_is_con()) {
78 return true;
79 }
80 }
81 }
82 return false;
83 }
84
85 //------------------------------get_early_ctrl---------------------------------
86 // Compute earliest legal control
87 Node *PhaseIdealLoop::get_early_ctrl( Node *n ) {
88 assert( !n->is_Phi() && !n->is_CFG(), "this code only handles data nodes" );
89 uint i;
90 Node *early;
91 if( n->in(0) ) {
92 early = n->in(0);
93 if( !early->is_CFG() ) // Might be a non-CFG multi-def
94 early = get_ctrl(early); // So treat input as a straight data input
95 i = 1;
96 } else {
97 early = get_ctrl(n->in(1));
98 i = 2;
99 }
100 uint e_d = dom_depth(early);
101 assert( early, "" );
102 for( ; i < n->req(); i++ ) {
103 Node *cin = get_ctrl(n->in(i));
104 assert( cin, "" );
105 // Keep deepest dominator depth
106 uint c_d = dom_depth(cin);
107 if( c_d > e_d ) { // Deeper guy?
108 early = cin; // Keep deepest found so far
109 e_d = c_d;
110 } else if( c_d == e_d && // Same depth?
111 early != cin ) { // If not equal, must use slower algorithm
112 // If same depth but not equal, one _must_ dominate the other
113 // and we want the deeper (i.e., dominated) guy.
114 Node *n1 = early;
115 Node *n2 = cin;
116 while( 1 ) {
117 n1 = idom(n1); // Walk up until break cycle
118 n2 = idom(n2);
119 if( n1 == cin || // Walked early up to cin
120 dom_depth(n2) < c_d )
121 break; // early is deeper; keep him
122 if( n2 == early || // Walked cin up to early
123 dom_depth(n1) < c_d ) {
124 early = cin; // cin is deeper; keep him
125 break;
126 }
127 }
128 e_d = dom_depth(early); // Reset depth register cache
129 }
130 }
131
132 // Return earliest legal location
133 assert(early == find_non_split_ctrl(early), "unexpected early control");
134
135 return early;
136 }
137
138 //------------------------------set_early_ctrl---------------------------------
139 // Set earliest legal control
140 void PhaseIdealLoop::set_early_ctrl( Node *n ) {
141 Node *early = get_early_ctrl(n);
142
143 // Record earliest legal location
144 set_ctrl(n, early);
145 }
146
147 //------------------------------set_subtree_ctrl-------------------------------
148 // set missing _ctrl entries on new nodes
149 void PhaseIdealLoop::set_subtree_ctrl( Node *n ) {
150 // Already set? Get out.
151 if( _nodes[n->_idx] ) return;
152 // Recursively set _nodes array to indicate where the Node goes
153 uint i;
154 for( i = 0; i < n->req(); ++i ) {
155 Node *m = n->in(i);
156 if( m && m != C->root() )
157 set_subtree_ctrl( m );
158 }
159
160 // Fixup self
161 set_early_ctrl( n );
162 }
163
164 //------------------------------is_counted_loop--------------------------------
165 bool PhaseIdealLoop::is_counted_loop( Node *x, IdealLoopTree *loop ) {
166 PhaseGVN *gvn = &_igvn;
167
168 // Counted loop head must be a good RegionNode with only 3 not NULL
169 // control input edges: Self, Entry, LoopBack.
170 if (x->in(LoopNode::Self) == NULL || x->req() != 3)
171 return false;
172
173 Node *init_control = x->in(LoopNode::EntryControl);
174 Node *back_control = x->in(LoopNode::LoopBackControl);
175 if (init_control == NULL || back_control == NULL) // Partially dead
176 return false;
177 // Must also check for TOP when looking for a dead loop
178 if (init_control->is_top() || back_control->is_top())
179 return false;
180
181 // Allow funny placement of Safepoint
182 if (back_control->Opcode() == Op_SafePoint)
183 back_control = back_control->in(TypeFunc::Control);
184
185 // Controlling test for loop
186 Node *iftrue = back_control;
187 uint iftrue_op = iftrue->Opcode();
188 if (iftrue_op != Op_IfTrue &&
189 iftrue_op != Op_IfFalse)
190 // I have a weird back-control. Probably the loop-exit test is in
191 // the middle of the loop and I am looking at some trailing control-flow
192 // merge point. To fix this I would have to partially peel the loop.
193 return false; // Obscure back-control
194
195 // Get boolean guarding loop-back test
196 Node *iff = iftrue->in(0);
197 if (get_loop(iff) != loop || !iff->in(1)->is_Bool())
198 return false;
199 BoolNode *test = iff->in(1)->as_Bool();
200 BoolTest::mask bt = test->_test._test;
201 float cl_prob = iff->as_If()->_prob;
202 if (iftrue_op == Op_IfFalse) {
203 bt = BoolTest(bt).negate();
204 cl_prob = 1.0 - cl_prob;
205 }
206 // Get backedge compare
207 Node *cmp = test->in(1);
208 int cmp_op = cmp->Opcode();
209 if (cmp_op != Op_CmpI)
210 return false; // Avoid pointer & float compares
211
212 // Find the trip-counter increment & limit. Limit must be loop invariant.
213 Node *incr = cmp->in(1);
214 Node *limit = cmp->in(2);
215
216 // ---------
217 // need 'loop()' test to tell if limit is loop invariant
218 // ---------
219
220 if (!is_member(loop, get_ctrl(incr))) { // Swapped trip counter and limit?
221 Node *tmp = incr; // Then reverse order into the CmpI
222 incr = limit;
223 limit = tmp;
224 bt = BoolTest(bt).commute(); // And commute the exit test
225 }
226 if (is_member(loop, get_ctrl(limit))) // Limit must be loop-invariant
227 return false;
228 if (!is_member(loop, get_ctrl(incr))) // Trip counter must be loop-variant
229 return false;
230
231 Node* phi_incr = NULL;
232 // Trip-counter increment must be commutative & associative.
233 if (incr->is_Phi()) {
234 if (incr->as_Phi()->region() != x || incr->req() != 3)
235 return false; // Not simple trip counter expression
236 phi_incr = incr;
237 incr = phi_incr->in(LoopNode::LoopBackControl); // Assume incr is on backedge of Phi
238 if (!is_member(loop, get_ctrl(incr))) // Trip counter must be loop-variant
239 return false;
240 }
241
242 Node* trunc1 = NULL;
243 Node* trunc2 = NULL;
244 const TypeInt* iv_trunc_t = NULL;
245 if (!(incr = CountedLoopNode::match_incr_with_optional_truncation(incr, &trunc1, &trunc2, &iv_trunc_t))) {
246 return false; // Funny increment opcode
247 }
248 assert(incr->Opcode() == Op_AddI, "wrong increment code");
249
250 // Get merge point
251 Node *xphi = incr->in(1);
252 Node *stride = incr->in(2);
253 if (!stride->is_Con()) { // Oops, swap these
254 if (!xphi->is_Con()) // Is the other guy a constant?
255 return false; // Nope, unknown stride, bail out
256 Node *tmp = xphi; // 'incr' is commutative, so ok to swap
257 xphi = stride;
258 stride = tmp;
259 }
260 // Stride must be constant
261 int stride_con = stride->get_int();
262 if (stride_con == 0)
263 return false; // missed some peephole opt
264
265 if (!xphi->is_Phi())
266 return false; // Too much math on the trip counter
267 if (phi_incr != NULL && phi_incr != xphi)
268 return false;
269 PhiNode *phi = xphi->as_Phi();
270
271 // Phi must be of loop header; backedge must wrap to increment
272 if (phi->region() != x)
273 return false;
274 if (trunc1 == NULL && phi->in(LoopNode::LoopBackControl) != incr ||
275 trunc1 != NULL && phi->in(LoopNode::LoopBackControl) != trunc1) {
276 return false;
277 }
278 Node *init_trip = phi->in(LoopNode::EntryControl);
279
280 // If iv trunc type is smaller than int, check for possible wrap.
281 if (!TypeInt::INT->higher_equal(iv_trunc_t)) {
282 assert(trunc1 != NULL, "must have found some truncation");
283
284 // Get a better type for the phi (filtered thru if's)
285 const TypeInt* phi_ft = filtered_type(phi);
286
287 // Can iv take on a value that will wrap?
288 //
289 // Ensure iv's limit is not within "stride" of the wrap value.
290 //
291 // Example for "short" type
292 // Truncation ensures value is in the range -32768..32767 (iv_trunc_t)
293 // If the stride is +10, then the last value of the induction
294 // variable before the increment (phi_ft->_hi) must be
295 // <= 32767 - 10 and (phi_ft->_lo) must be >= -32768 to
296 // ensure no truncation occurs after the increment.
297
298 if (stride_con > 0) {
299 if (iv_trunc_t->_hi - phi_ft->_hi < stride_con ||
300 iv_trunc_t->_lo > phi_ft->_lo) {
301 return false; // truncation may occur
302 }
303 } else if (stride_con < 0) {
304 if (iv_trunc_t->_lo - phi_ft->_lo > stride_con ||
305 iv_trunc_t->_hi < phi_ft->_hi) {
306 return false; // truncation may occur
307 }
308 }
309 // No possibility of wrap so truncation can be discarded
310 // Promote iv type to Int
311 } else {
312 assert(trunc1 == NULL && trunc2 == NULL, "no truncation for int");
313 }
314
315 // If the condition is inverted and we will be rolling
316 // through MININT to MAXINT, then bail out.
317 if (bt == BoolTest::eq || // Bail out, but this loop trips at most twice!
318 // Odd stride
319 bt == BoolTest::ne && stride_con != 1 && stride_con != -1 ||
320 // Count down loop rolls through MAXINT
321 (bt == BoolTest::le || bt == BoolTest::lt) && stride_con < 0 ||
322 // Count up loop rolls through MININT
323 (bt == BoolTest::ge || bt == BoolTest::gt) && stride_con > 0) {
324 return false; // Bail out
325 }
326
327 const TypeInt* init_t = gvn->type(init_trip)->is_int();
328 const TypeInt* limit_t = gvn->type(limit)->is_int();
329
330 if (stride_con > 0) {
331 long init_p = (long)init_t->_lo + stride_con;
332 if (init_p > (long)max_jint || init_p > (long)limit_t->_hi)
333 return false; // cyclic loop or this loop trips only once
334 } else {
335 long init_p = (long)init_t->_hi + stride_con;
336 if (init_p < (long)min_jint || init_p < (long)limit_t->_lo)
337 return false; // cyclic loop or this loop trips only once
338 }
339
340 // =================================================
341 // ---- SUCCESS! Found A Trip-Counted Loop! -----
342 //
343 assert(x->Opcode() == Op_Loop, "regular loops only");
344 C->print_method("Before CountedLoop", 3);
345
346 Node *hook = new (C, 6) Node(6);
347
348 if (LoopLimitCheck) {
349
350 // ===================================================
351 // Generate loop limit check to avoid integer overflow
352 // in cases like next (cyclic loops):
353 //
354 // for (i=0; i <= max_jint; i++) {}
355 // for (i=0; i < max_jint; i+=2) {}
356 //
357 //
358 // Limit check predicate depends on the loop test:
359 //
360 // for(;i != limit; i++) --> limit <= (max_jint)
361 // for(;i < limit; i+=stride) --> limit <= (max_jint - stride + 1)
362 // for(;i <= limit; i+=stride) --> limit <= (max_jint - stride )
363 //
364
365 // Check if limit is excluded to do more precise int overflow check.
366 bool incl_limit = (bt == BoolTest::le || bt == BoolTest::ge);
367 int stride_m = stride_con - (incl_limit ? 0 : (stride_con > 0 ? 1 : -1));
368
369 // If compare points directly to the phi we need to adjust
370 // the compare so that it points to the incr. Limit have
371 // to be adjusted to keep trip count the same and the
372 // adjusted limit should be checked for int overflow.
373 if (phi_incr != NULL) {
374 stride_m += stride_con;
375 }
376
377 if (limit->is_Con()) {
378 int limit_con = limit->get_int();
379 if ((stride_con > 0 && limit_con > (max_jint - stride_m)) ||
380 (stride_con < 0 && limit_con < (min_jint - stride_m))) {
381 // Bailout: it could be integer overflow.
382 return false;
383 }
384 } else if ((stride_con > 0 && limit_t->_hi <= (max_jint - stride_m)) ||
385 (stride_con < 0 && limit_t->_lo >= (min_jint - stride_m))) {
386 // Limit's type may satisfy the condition, for example,
387 // when it is an array length.
388 } else {
389 // Generate loop's limit check.
390 // Loop limit check predicate should be near the loop.
391 ProjNode *limit_check_proj = find_predicate_insertion_point(init_control, Deoptimization::Reason_loop_limit_check);
392 if (!limit_check_proj) {
393 // The limit check predicate is not generated if this method trapped here before.
394 #ifdef ASSERT
395 if (TraceLoopLimitCheck) {
396 tty->print("missing loop limit check:");
397 loop->dump_head();
398 x->dump(1);
399 }
400 #endif
401 return false;
402 }
403
404 IfNode* check_iff = limit_check_proj->in(0)->as_If();
405 Node* cmp_limit;
406 Node* bol;
407
408 if (stride_con > 0) {
409 cmp_limit = new (C, 3) CmpINode(limit, _igvn.intcon(max_jint - stride_m));
410 bol = new (C, 2) BoolNode(cmp_limit, BoolTest::le);
411 } else {
412 cmp_limit = new (C, 3) CmpINode(limit, _igvn.intcon(min_jint - stride_m));
413 bol = new (C, 2) BoolNode(cmp_limit, BoolTest::ge);
414 }
415 cmp_limit = _igvn.register_new_node_with_optimizer(cmp_limit);
416 bol = _igvn.register_new_node_with_optimizer(bol);
417 set_subtree_ctrl(bol);
418
419 // Replace condition in original predicate but preserve Opaque node
420 // so that previous predicates could be found.
421 assert(check_iff->in(1)->Opcode() == Op_Conv2B &&
422 check_iff->in(1)->in(1)->Opcode() == Op_Opaque1, "");
423 Node* opq = check_iff->in(1)->in(1);
424 _igvn.hash_delete(opq);
425 opq->set_req(1, bol);
426 // Update ctrl.
427 set_ctrl(opq, check_iff->in(0));
428 set_ctrl(check_iff->in(1), check_iff->in(0));
429
430 #ifndef PRODUCT
431 // report that the loop predication has been actually performed
432 // for this loop
433 if (TraceLoopLimitCheck) {
434 tty->print_cr("Counted Loop Limit Check generated:");
435 debug_only( bol->dump(2); )
436 }
437 #endif
438 }
439
440 if (phi_incr != NULL) {
441 // If compare points directly to the phi we need to adjust
442 // the compare so that it points to the incr. Limit have
443 // to be adjusted to keep trip count the same and we
444 // should avoid int overflow.
445 //
446 // i = init; do {} while(i++ < limit);
447 // is converted to
448 // i = init; do {} while(++i < limit+1);
449 //
450 limit = gvn->transform(new (C, 3) AddINode(limit, stride));
451 }
452
453 // Now we need to canonicalize loop condition.
454 if (bt == BoolTest::ne) {
455 assert(stride_con == 1 || stride_con == -1, "simple increment only");
456 // 'ne' can be replaced with 'lt' only when init < limit.
457 if (stride_con > 0 && init_t->_hi < limit_t->_lo)
458 bt = BoolTest::lt;
459 // 'ne' can be replaced with 'gt' only when init > limit.
460 if (stride_con < 0 && init_t->_lo > limit_t->_hi)
461 bt = BoolTest::gt;
462 }
463
464 if (incl_limit) {
465 // The limit check guaranties that 'limit <= (max_jint - stride)' so
466 // we can convert 'i <= limit' to 'i < limit+1' since stride != 0.
467 //
468 Node* one = (stride_con > 0) ? gvn->intcon( 1) : gvn->intcon(-1);
469 limit = gvn->transform(new (C, 3) AddINode(limit, one));
470 if (bt == BoolTest::le)
471 bt = BoolTest::lt;
472 else if (bt == BoolTest::ge)
473 bt = BoolTest::gt;
474 else
475 ShouldNotReachHere();
476 }
477 set_subtree_ctrl( limit );
478
479 } else { // LoopLimitCheck
480
481 // If compare points to incr, we are ok. Otherwise the compare
482 // can directly point to the phi; in this case adjust the compare so that
483 // it points to the incr by adjusting the limit.
484 if (cmp->in(1) == phi || cmp->in(2) == phi)
485 limit = gvn->transform(new (C, 3) AddINode(limit,stride));
486
487 // trip-count for +-tive stride should be: (limit - init_trip + stride - 1)/stride.
488 // Final value for iterator should be: trip_count * stride + init_trip.
489 Node *one_p = gvn->intcon( 1);
490 Node *one_m = gvn->intcon(-1);
491
492 Node *trip_count = NULL;
493 switch( bt ) {
494 case BoolTest::eq:
495 ShouldNotReachHere();
496 case BoolTest::ne: // Ahh, the case we desire
497 if (stride_con == 1)
498 trip_count = gvn->transform(new (C, 3) SubINode(limit,init_trip));
499 else if (stride_con == -1)
500 trip_count = gvn->transform(new (C, 3) SubINode(init_trip,limit));
501 else
502 ShouldNotReachHere();
503 set_subtree_ctrl(trip_count);
504 //_loop.map(trip_count->_idx,loop(limit));
505 break;
506 case BoolTest::le: // Maybe convert to '<' case
507 limit = gvn->transform(new (C, 3) AddINode(limit,one_p));
508 set_subtree_ctrl( limit );
509 hook->init_req(4, limit);
510
511 bt = BoolTest::lt;
512 // Make the new limit be in the same loop nest as the old limit
513 //_loop.map(limit->_idx,limit_loop);
514 // Fall into next case
515 case BoolTest::lt: { // Maybe convert to '!=' case
516 if (stride_con < 0) // Count down loop rolls through MAXINT
517 ShouldNotReachHere();
518 Node *range = gvn->transform(new (C, 3) SubINode(limit,init_trip));
519 set_subtree_ctrl( range );
520 hook->init_req(0, range);
521
522 Node *bias = gvn->transform(new (C, 3) AddINode(range,stride));
523 set_subtree_ctrl( bias );
524 hook->init_req(1, bias);
525
526 Node *bias1 = gvn->transform(new (C, 3) AddINode(bias,one_m));
527 set_subtree_ctrl( bias1 );
528 hook->init_req(2, bias1);
529
530 trip_count = gvn->transform(new (C, 3) DivINode(0,bias1,stride));
531 set_subtree_ctrl( trip_count );
532 hook->init_req(3, trip_count);
533 break;
534 }
535
536 case BoolTest::ge: // Maybe convert to '>' case
537 limit = gvn->transform(new (C, 3) AddINode(limit,one_m));
538 set_subtree_ctrl( limit );
539 hook->init_req(4 ,limit);
540
541 bt = BoolTest::gt;
542 // Make the new limit be in the same loop nest as the old limit
543 //_loop.map(limit->_idx,limit_loop);
544 // Fall into next case
545 case BoolTest::gt: { // Maybe convert to '!=' case
546 if (stride_con > 0) // count up loop rolls through MININT
547 ShouldNotReachHere();
548 Node *range = gvn->transform(new (C, 3) SubINode(limit,init_trip));
549 set_subtree_ctrl( range );
550 hook->init_req(0, range);
551
552 Node *bias = gvn->transform(new (C, 3) AddINode(range,stride));
553 set_subtree_ctrl( bias );
554 hook->init_req(1, bias);
555
556 Node *bias1 = gvn->transform(new (C, 3) AddINode(bias,one_p));
557 set_subtree_ctrl( bias1 );
558 hook->init_req(2, bias1);
559
560 trip_count = gvn->transform(new (C, 3) DivINode(0,bias1,stride));
561 set_subtree_ctrl( trip_count );
562 hook->init_req(3, trip_count);
563 break;
564 }
565 } // switch( bt )
566
567 Node *span = gvn->transform(new (C, 3) MulINode(trip_count,stride));
568 set_subtree_ctrl( span );
569 hook->init_req(5, span);
570
571 limit = gvn->transform(new (C, 3) AddINode(span,init_trip));
572 set_subtree_ctrl( limit );
573
574 } // LoopLimitCheck
575
576 // Check for SafePoint on backedge and remove
577 Node *sfpt = x->in(LoopNode::LoopBackControl);
578 if (sfpt->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt)) {
579 lazy_replace( sfpt, iftrue );
580 loop->_tail = iftrue;
581 }
582
583 // Build a canonical trip test.
584 // Clone code, as old values may be in use.
585 incr = incr->clone();
586 incr->set_req(1,phi);
587 incr->set_req(2,stride);
588 incr = _igvn.register_new_node_with_optimizer(incr);
589 set_early_ctrl( incr );
590 _igvn.hash_delete(phi);
591 phi->set_req_X( LoopNode::LoopBackControl, incr, &_igvn );
592
593 // If phi type is more restrictive than Int, raise to
594 // Int to prevent (almost) infinite recursion in igvn
595 // which can only handle integer types for constants or minint..maxint.
596 if (!TypeInt::INT->higher_equal(phi->bottom_type())) {
597 Node* nphi = PhiNode::make(phi->in(0), phi->in(LoopNode::EntryControl), TypeInt::INT);
598 nphi->set_req(LoopNode::LoopBackControl, phi->in(LoopNode::LoopBackControl));
599 nphi = _igvn.register_new_node_with_optimizer(nphi);
600 set_ctrl(nphi, get_ctrl(phi));
601 _igvn.replace_node(phi, nphi);
602 phi = nphi->as_Phi();
603 }
604 cmp = cmp->clone();
605 cmp->set_req(1,incr);
606 cmp->set_req(2,limit);
607 cmp = _igvn.register_new_node_with_optimizer(cmp);
608 set_ctrl(cmp, iff->in(0));
609
610 test = test->clone()->as_Bool();
611 (*(BoolTest*)&test->_test)._test = bt;
612 test->set_req(1,cmp);
613 _igvn.register_new_node_with_optimizer(test);
614 set_ctrl(test, iff->in(0));
615
616 // Replace the old IfNode with a new LoopEndNode
617 Node *lex = _igvn.register_new_node_with_optimizer(new (C, 2) CountedLoopEndNode( iff->in(0), test, cl_prob, iff->as_If()->_fcnt ));
618 IfNode *le = lex->as_If();
619 uint dd = dom_depth(iff);
620 set_idom(le, le->in(0), dd); // Update dominance for loop exit
621 set_loop(le, loop);
622
623 // Get the loop-exit control
624 Node *iffalse = iff->as_If()->proj_out(!(iftrue_op == Op_IfTrue));
625
626 // Need to swap loop-exit and loop-back control?
627 if (iftrue_op == Op_IfFalse) {
628 Node *ift2=_igvn.register_new_node_with_optimizer(new (C, 1) IfTrueNode (le));
629 Node *iff2=_igvn.register_new_node_with_optimizer(new (C, 1) IfFalseNode(le));
630
631 loop->_tail = back_control = ift2;
632 set_loop(ift2, loop);
633 set_loop(iff2, get_loop(iffalse));
634
635 // Lazy update of 'get_ctrl' mechanism.
636 lazy_replace_proj( iffalse, iff2 );
637 lazy_replace_proj( iftrue, ift2 );
638
639 // Swap names
640 iffalse = iff2;
641 iftrue = ift2;
642 } else {
643 _igvn.hash_delete(iffalse);
644 _igvn.hash_delete(iftrue);
645 iffalse->set_req_X( 0, le, &_igvn );
646 iftrue ->set_req_X( 0, le, &_igvn );
647 }
648
649 set_idom(iftrue, le, dd+1);
650 set_idom(iffalse, le, dd+1);
651 assert(iff->outcnt() == 0, "should be dead now");
652 lazy_replace( iff, le ); // fix 'get_ctrl'
653
654 // Now setup a new CountedLoopNode to replace the existing LoopNode
655 CountedLoopNode *l = new (C, 3) CountedLoopNode(init_control, back_control);
656 l->set_unswitch_count(x->as_Loop()->unswitch_count()); // Preserve
657 // The following assert is approximately true, and defines the intention
658 // of can_be_counted_loop. It fails, however, because phase->type
659 // is not yet initialized for this loop and its parts.
660 //assert(l->can_be_counted_loop(this), "sanity");
661 _igvn.register_new_node_with_optimizer(l);
662 set_loop(l, loop);
663 loop->_head = l;
664 // Fix all data nodes placed at the old loop head.
665 // Uses the lazy-update mechanism of 'get_ctrl'.
666 lazy_replace( x, l );
667 set_idom(l, init_control, dom_depth(x));
668
669 // Check for immediately preceding SafePoint and remove
670 Node *sfpt2 = le->in(0);
671 if (sfpt2->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt2))
672 lazy_replace( sfpt2, sfpt2->in(TypeFunc::Control));
673
674 // Free up intermediate goo
675 _igvn.remove_dead_node(hook);
676
677 #ifdef ASSERT
678 assert(l->is_valid_counted_loop(), "counted loop shape is messed up");
679 assert(l == loop->_head && l->phi() == phi && l->loopexit() == lex, "" );
680 #endif
681 #ifndef PRODUCT
682 if (TraceLoopOpts) {
683 tty->print("Counted ");
684 loop->dump_head();
685 }
686 #endif
687
688 C->print_method("After CountedLoop", 3);
689
690 return true;
691 }
692
693 //----------------------exact_limit-------------------------------------------
694 Node* PhaseIdealLoop::exact_limit( IdealLoopTree *loop ) {
695 assert(loop->_head->is_CountedLoop(), "");
696 CountedLoopNode *cl = loop->_head->as_CountedLoop();
697 assert(cl->is_valid_counted_loop(), "");
698
699 if (!LoopLimitCheck || ABS(cl->stride_con()) == 1 ||
700 cl->limit()->Opcode() == Op_LoopLimit) {
701 // Old code has exact limit (it could be incorrect in case of int overflow).
702 // Loop limit is exact with stride == 1. And loop may already have exact limit.
703 return cl->limit();
704 }
705 Node *limit = NULL;
706 #ifdef ASSERT
707 BoolTest::mask bt = cl->loopexit()->test_trip();
708 assert(bt == BoolTest::lt || bt == BoolTest::gt, "canonical test is expected");
709 #endif
710 if (cl->has_exact_trip_count()) {
711 // Simple case: loop has constant boundaries.
712 // Use longs to avoid integer overflow.
713 int stride_con = cl->stride_con();
714 long init_con = cl->init_trip()->get_int();
715 long limit_con = cl->limit()->get_int();
716 julong trip_cnt = cl->trip_count();
717 long final_con = init_con + trip_cnt*stride_con;
718 int final_int = (int)final_con;
719 // The final value should be in integer range since the loop
720 // is counted and the limit was checked for overflow.
721 assert(final_con == (long)final_int, "final value should be integer");
722 limit = _igvn.intcon(final_int);
723 } else {
724 // Create new LoopLimit node to get exact limit (final iv value).
725 limit = new (C, 4) LoopLimitNode(C, cl->init_trip(), cl->limit(), cl->stride());
726 register_new_node(limit, cl->in(LoopNode::EntryControl));
727 }
728 assert(limit != NULL, "sanity");
729 return limit;
730 }
731
732 //------------------------------Ideal------------------------------------------
733 // Return a node which is more "ideal" than the current node.
734 // Attempt to convert into a counted-loop.
735 Node *LoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
736 if (!can_be_counted_loop(phase)) {
737 phase->C->set_major_progress();
738 }
739 return RegionNode::Ideal(phase, can_reshape);
740 }
741
742
743 //=============================================================================
744 //------------------------------Ideal------------------------------------------
745 // Return a node which is more "ideal" than the current node.
746 // Attempt to convert into a counted-loop.
747 Node *CountedLoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
748 return RegionNode::Ideal(phase, can_reshape);
749 }
750
751 //------------------------------dump_spec--------------------------------------
752 // Dump special per-node info
753 #ifndef PRODUCT
754 void CountedLoopNode::dump_spec(outputStream *st) const {
755 LoopNode::dump_spec(st);
756 if (stride_is_con()) {
757 st->print("stride: %d ",stride_con());
758 }
759 if (is_pre_loop ()) st->print("pre of N%d" , _main_idx);
760 if (is_main_loop()) st->print("main of N%d", _idx);
761 if (is_post_loop()) st->print("post of N%d", _main_idx);
762 }
763 #endif
764
765 //=============================================================================
766 int CountedLoopEndNode::stride_con() const {
767 return stride()->bottom_type()->is_int()->get_con();
768 }
769
770 //=============================================================================
771 //------------------------------Value-----------------------------------------
772 const Type *LoopLimitNode::Value( PhaseTransform *phase ) const {
773 const Type* init_t = phase->type(in(Init));
774 const Type* limit_t = phase->type(in(Limit));
775 const Type* stride_t = phase->type(in(Stride));
776 // Either input is TOP ==> the result is TOP
777 if (init_t == Type::TOP) return Type::TOP;
778 if (limit_t == Type::TOP) return Type::TOP;
779 if (stride_t == Type::TOP) return Type::TOP;
780
781 int stride_con = stride_t->is_int()->get_con();
782 if (stride_con == 1)
783 return NULL; // Identity
784
785 if (init_t->is_int()->is_con() && limit_t->is_int()->is_con()) {
786 // Use longs to avoid integer overflow.
787 long init_con = init_t->is_int()->get_con();
788 long limit_con = limit_t->is_int()->get_con();
789 int stride_m = stride_con - (stride_con > 0 ? 1 : -1);
790 long trip_count = (limit_con - init_con + stride_m)/stride_con;
791 long final_con = init_con + stride_con*trip_count;
792 int final_int = (int)final_con;
793 // The final value should be in integer range since the loop
794 // is counted and the limit was checked for overflow.
795 assert(final_con == (long)final_int, "final value should be integer");
796 return TypeInt::make(final_int);
797 }
798
799 return bottom_type(); // TypeInt::INT
800 }
801
802 //------------------------------Ideal------------------------------------------
803 // Return a node which is more "ideal" than the current node.
804 Node *LoopLimitNode::Ideal(PhaseGVN *phase, bool can_reshape) {
805 if (phase->type(in(Init)) == Type::TOP ||
806 phase->type(in(Limit)) == Type::TOP ||
807 phase->type(in(Stride)) == Type::TOP)
808 return NULL; // Dead
809
810 int stride_con = phase->type(in(Stride))->is_int()->get_con();
811 if (stride_con == 1)
812 return NULL; // Identity
813
814 if (in(Init)->is_Con() && in(Limit)->is_Con())
815 return NULL; // Value
816
817 // Delay following optimizations until all loop optimizations
818 // done to keep Ideal graph simple.
819 if (!can_reshape || phase->C->major_progress())
820 return NULL;
821
822 const TypeInt* init_t = phase->type(in(Init) )->is_int();
823 const TypeInt* limit_t = phase->type(in(Limit))->is_int();
824 int stride_p;
825 long lim, ini;
826 julong max;
827 if (stride_con > 0) {
828 stride_p = stride_con;
829 lim = limit_t->_hi;
830 ini = init_t->_lo;
831 max = (julong)max_jint;
832 } else {
833 stride_p = -stride_con;
834 lim = init_t->_hi;
835 ini = limit_t->_lo;
836 max = (julong)min_jint;
837 }
838 julong range = lim - ini + stride_p;
839 if (range <= max) {
840 // Convert to integer expression if it is not overflow.
841 Node* stride_m = phase->intcon(stride_con - (stride_con > 0 ? 1 : -1));
842 Node *range = phase->transform(new (phase->C, 3) SubINode(in(Limit), in(Init)));
843 Node *bias = phase->transform(new (phase->C, 3) AddINode(range, stride_m));
844 Node *trip = phase->transform(new (phase->C, 3) DivINode(0, bias, in(Stride)));
845 Node *span = phase->transform(new (phase->C, 3) MulINode(trip, in(Stride)));
846 return new (phase->C, 3) AddINode(span, in(Init)); // exact limit
847 }
848
849 if (is_power_of_2(stride_p) || // divisor is 2^n
850 !Matcher::has_match_rule(Op_LoopLimit)) { // or no specialized Mach node?
851 // Convert to long expression to avoid integer overflow
852 // and let igvn optimizer convert this division.
853 //
854 Node* init = phase->transform( new (phase->C, 2) ConvI2LNode(in(Init)));
855 Node* limit = phase->transform( new (phase->C, 2) ConvI2LNode(in(Limit)));
856 Node* stride = phase->longcon(stride_con);
857 Node* stride_m = phase->longcon(stride_con - (stride_con > 0 ? 1 : -1));
858
859 Node *range = phase->transform(new (phase->C, 3) SubLNode(limit, init));
860 Node *bias = phase->transform(new (phase->C, 3) AddLNode(range, stride_m));
861 Node *span;
862 if (stride_con > 0 && is_power_of_2(stride_p)) {
863 // bias >= 0 if stride >0, so if stride is 2^n we can use &(-stride)
864 // and avoid generating rounding for division. Zero trip guard should
865 // guarantee that init < limit but sometimes the guard is missing and
866 // we can get situation when init > limit. Note, for the empty loop
867 // optimization zero trip guard is generated explicitly which leaves
868 // only RCE predicate where exact limit is used and the predicate
869 // will simply fail forcing recompilation.
870 Node* neg_stride = phase->longcon(-stride_con);
871 span = phase->transform(new (phase->C, 3) AndLNode(bias, neg_stride));
872 } else {
873 Node *trip = phase->transform(new (phase->C, 3) DivLNode(0, bias, stride));
874 span = phase->transform(new (phase->C, 3) MulLNode(trip, stride));
875 }
876 // Convert back to int
877 Node *span_int = phase->transform(new (phase->C, 2) ConvL2INode(span));
878 return new (phase->C, 3) AddINode(span_int, in(Init)); // exact limit
879 }
880
881 return NULL; // No progress
882 }
883
884 //------------------------------Identity---------------------------------------
885 // If stride == 1 return limit node.
886 Node *LoopLimitNode::Identity( PhaseTransform *phase ) {
887 int stride_con = phase->type(in(Stride))->is_int()->get_con();
888 if (stride_con == 1 || stride_con == -1)
889 return in(Limit);
890 return this;
891 }
892
893 //=============================================================================
894 //----------------------match_incr_with_optional_truncation--------------------
895 // Match increment with optional truncation:
896 // CHAR: (i+1)&0x7fff, BYTE: ((i+1)<<8)>>8, or SHORT: ((i+1)<<16)>>16
897 // Return NULL for failure. Success returns the increment node.
898 Node* CountedLoopNode::match_incr_with_optional_truncation(
899 Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type) {
900 // Quick cutouts:
901 if (expr == NULL || expr->req() != 3) return NULL;
902
903 Node *t1 = NULL;
904 Node *t2 = NULL;
905 const TypeInt* trunc_t = TypeInt::INT;
906 Node* n1 = expr;
907 int n1op = n1->Opcode();
908
909 // Try to strip (n1 & M) or (n1 << N >> N) from n1.
910 if (n1op == Op_AndI &&
911 n1->in(2)->is_Con() &&
912 n1->in(2)->bottom_type()->is_int()->get_con() == 0x7fff) {
913 // %%% This check should match any mask of 2**K-1.
914 t1 = n1;
915 n1 = t1->in(1);
916 n1op = n1->Opcode();
917 trunc_t = TypeInt::CHAR;
918 } else if (n1op == Op_RShiftI &&
919 n1->in(1) != NULL &&
920 n1->in(1)->Opcode() == Op_LShiftI &&
921 n1->in(2) == n1->in(1)->in(2) &&
922 n1->in(2)->is_Con()) {
923 jint shift = n1->in(2)->bottom_type()->is_int()->get_con();
924 // %%% This check should match any shift in [1..31].
925 if (shift == 16 || shift == 8) {
926 t1 = n1;
927 t2 = t1->in(1);
928 n1 = t2->in(1);
929 n1op = n1->Opcode();
930 if (shift == 16) {
931 trunc_t = TypeInt::SHORT;
932 } else if (shift == 8) {
933 trunc_t = TypeInt::BYTE;
934 }
935 }
936 }
937
938 // If (maybe after stripping) it is an AddI, we won:
939 if (n1op == Op_AddI) {
940 *trunc1 = t1;
941 *trunc2 = t2;
942 *trunc_type = trunc_t;
943 return n1;
944 }
945
946 // failed
947 return NULL;
948 }
949
950
951 //------------------------------filtered_type--------------------------------
952 // Return a type based on condition control flow
953 // A successful return will be a type that is restricted due
954 // to a series of dominating if-tests, such as:
955 // if (i < 10) {
956 // if (i > 0) {
957 // here: "i" type is [1..10)
958 // }
959 // }
960 // or a control flow merge
961 // if (i < 10) {
962 // do {
963 // phi( , ) -- at top of loop type is [min_int..10)
964 // i = ?
965 // } while ( i < 10)
966 //
967 const TypeInt* PhaseIdealLoop::filtered_type( Node *n, Node* n_ctrl) {
968 assert(n && n->bottom_type()->is_int(), "must be int");
969 const TypeInt* filtered_t = NULL;
970 if (!n->is_Phi()) {
971 assert(n_ctrl != NULL || n_ctrl == C->top(), "valid control");
972 filtered_t = filtered_type_from_dominators(n, n_ctrl);
973
974 } else {
975 Node* phi = n->as_Phi();
976 Node* region = phi->in(0);
977 assert(n_ctrl == NULL || n_ctrl == region, "ctrl parameter must be region");
978 if (region && region != C->top()) {
979 for (uint i = 1; i < phi->req(); i++) {
980 Node* val = phi->in(i);
981 Node* use_c = region->in(i);
982 const TypeInt* val_t = filtered_type_from_dominators(val, use_c);
983 if (val_t != NULL) {
984 if (filtered_t == NULL) {
985 filtered_t = val_t;
986 } else {
987 filtered_t = filtered_t->meet(val_t)->is_int();
988 }
989 }
990 }
991 }
992 }
993 const TypeInt* n_t = _igvn.type(n)->is_int();
994 if (filtered_t != NULL) {
995 n_t = n_t->join(filtered_t)->is_int();
996 }
997 return n_t;
998 }
999
1000
1001 //------------------------------filtered_type_from_dominators--------------------------------
1002 // Return a possibly more restrictive type for val based on condition control flow of dominators
1003 const TypeInt* PhaseIdealLoop::filtered_type_from_dominators( Node* val, Node *use_ctrl) {
1004 if (val->is_Con()) {
1005 return val->bottom_type()->is_int();
1006 }
1007 uint if_limit = 10; // Max number of dominating if's visited
1008 const TypeInt* rtn_t = NULL;
1009
1010 if (use_ctrl && use_ctrl != C->top()) {
1011 Node* val_ctrl = get_ctrl(val);
1012 uint val_dom_depth = dom_depth(val_ctrl);
1013 Node* pred = use_ctrl;
1014 uint if_cnt = 0;
1015 while (if_cnt < if_limit) {
1016 if ((pred->Opcode() == Op_IfTrue || pred->Opcode() == Op_IfFalse)) {
1017 if_cnt++;
1018 const TypeInt* if_t = IfNode::filtered_int_type(&_igvn, val, pred);
1019 if (if_t != NULL) {
1020 if (rtn_t == NULL) {
1021 rtn_t = if_t;
1022 } else {
1023 rtn_t = rtn_t->join(if_t)->is_int();
1024 }
1025 }
1026 }
1027 pred = idom(pred);
1028 if (pred == NULL || pred == C->top()) {
1029 break;
1030 }
1031 // Stop if going beyond definition block of val
1032 if (dom_depth(pred) < val_dom_depth) {
1033 break;
1034 }
1035 }
1036 }
1037 return rtn_t;
1038 }
1039
1040
1041 //------------------------------dump_spec--------------------------------------
1042 // Dump special per-node info
1043 #ifndef PRODUCT
1044 void CountedLoopEndNode::dump_spec(outputStream *st) const {
1045 if( in(TestValue)->is_Bool() ) {
1046 BoolTest bt( test_trip()); // Added this for g++.
1047
1048 st->print("[");
1049 bt.dump_on(st);
1050 st->print("]");
1051 }
1052 st->print(" ");
1053 IfNode::dump_spec(st);
1054 }
1055 #endif
1056
1057 //=============================================================================
1058 //------------------------------is_member--------------------------------------
1059 // Is 'l' a member of 'this'?
1060 int IdealLoopTree::is_member( const IdealLoopTree *l ) const {
1061 while( l->_nest > _nest ) l = l->_parent;
1062 return l == this;
1063 }
1064
1065 //------------------------------set_nest---------------------------------------
1066 // Set loop tree nesting depth. Accumulate _has_call bits.
1067 int IdealLoopTree::set_nest( uint depth ) {
1068 _nest = depth;
1069 int bits = _has_call;
1070 if( _child ) bits |= _child->set_nest(depth+1);
1071 if( bits ) _has_call = 1;
1072 if( _next ) bits |= _next ->set_nest(depth );
1073 return bits;
1074 }
1075
1076 //------------------------------split_fall_in----------------------------------
1077 // Split out multiple fall-in edges from the loop header. Move them to a
1078 // private RegionNode before the loop. This becomes the loop landing pad.
1079 void IdealLoopTree::split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ) {
1080 PhaseIterGVN &igvn = phase->_igvn;
1081 uint i;
1082
1083 // Make a new RegionNode to be the landing pad.
1084 Node *landing_pad = new (phase->C, fall_in_cnt+1) RegionNode( fall_in_cnt+1 );
1085 phase->set_loop(landing_pad,_parent);
1086 // Gather all the fall-in control paths into the landing pad
1087 uint icnt = fall_in_cnt;
1088 uint oreq = _head->req();
1089 for( i = oreq-1; i>0; i-- )
1090 if( !phase->is_member( this, _head->in(i) ) )
1091 landing_pad->set_req(icnt--,_head->in(i));
1092
1093 // Peel off PhiNode edges as well
1094 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1095 Node *oj = _head->fast_out(j);
1096 if( oj->is_Phi() ) {
1097 PhiNode* old_phi = oj->as_Phi();
1098 assert( old_phi->region() == _head, "" );
1099 igvn.hash_delete(old_phi); // Yank from hash before hacking edges
1100 Node *p = PhiNode::make_blank(landing_pad, old_phi);
1101 uint icnt = fall_in_cnt;
1102 for( i = oreq-1; i>0; i-- ) {
1103 if( !phase->is_member( this, _head->in(i) ) ) {
1104 p->init_req(icnt--, old_phi->in(i));
1105 // Go ahead and clean out old edges from old phi
1106 old_phi->del_req(i);
1107 }
1108 }
1109 // Search for CSE's here, because ZKM.jar does a lot of
1110 // loop hackery and we need to be a little incremental
1111 // with the CSE to avoid O(N^2) node blow-up.
1112 Node *p2 = igvn.hash_find_insert(p); // Look for a CSE
1113 if( p2 ) { // Found CSE
1114 p->destruct(); // Recover useless new node
1115 p = p2; // Use old node
1116 } else {
1117 igvn.register_new_node_with_optimizer(p, old_phi);
1118 }
1119 // Make old Phi refer to new Phi.
1120 old_phi->add_req(p);
1121 // Check for the special case of making the old phi useless and
1122 // disappear it. In JavaGrande I have a case where this useless
1123 // Phi is the loop limit and prevents recognizing a CountedLoop
1124 // which in turn prevents removing an empty loop.
1125 Node *id_old_phi = old_phi->Identity( &igvn );
1126 if( id_old_phi != old_phi ) { // Found a simple identity?
1127 // Note that I cannot call 'replace_node' here, because
1128 // that will yank the edge from old_phi to the Region and
1129 // I'm mid-iteration over the Region's uses.
1130 for (DUIterator_Last imin, i = old_phi->last_outs(imin); i >= imin; ) {
1131 Node* use = old_phi->last_out(i);
1132 igvn.hash_delete(use);
1133 igvn._worklist.push(use);
1134 uint uses_found = 0;
1135 for (uint j = 0; j < use->len(); j++) {
1136 if (use->in(j) == old_phi) {
1137 if (j < use->req()) use->set_req (j, id_old_phi);
1138 else use->set_prec(j, id_old_phi);
1139 uses_found++;
1140 }
1141 }
1142 i -= uses_found; // we deleted 1 or more copies of this edge
1143 }
1144 }
1145 igvn._worklist.push(old_phi);
1146 }
1147 }
1148 // Finally clean out the fall-in edges from the RegionNode
1149 for( i = oreq-1; i>0; i-- ) {
1150 if( !phase->is_member( this, _head->in(i) ) ) {
1151 _head->del_req(i);
1152 }
1153 }
1154 // Transform landing pad
1155 igvn.register_new_node_with_optimizer(landing_pad, _head);
1156 // Insert landing pad into the header
1157 _head->add_req(landing_pad);
1158 }
1159
1160 //------------------------------split_outer_loop-------------------------------
1161 // Split out the outermost loop from this shared header.
1162 void IdealLoopTree::split_outer_loop( PhaseIdealLoop *phase ) {
1163 PhaseIterGVN &igvn = phase->_igvn;
1164
1165 // Find index of outermost loop; it should also be my tail.
1166 uint outer_idx = 1;
1167 while( _head->in(outer_idx) != _tail ) outer_idx++;
1168
1169 // Make a LoopNode for the outermost loop.
1170 Node *ctl = _head->in(LoopNode::EntryControl);
1171 Node *outer = new (phase->C, 3) LoopNode( ctl, _head->in(outer_idx) );
1172 outer = igvn.register_new_node_with_optimizer(outer, _head);
1173 phase->set_created_loop_node();
1174
1175 // Outermost loop falls into '_head' loop
1176 _head->set_req(LoopNode::EntryControl, outer);
1177 _head->del_req(outer_idx);
1178 // Split all the Phis up between '_head' loop and 'outer' loop.
1179 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1180 Node *out = _head->fast_out(j);
1181 if( out->is_Phi() ) {
1182 PhiNode *old_phi = out->as_Phi();
1183 assert( old_phi->region() == _head, "" );
1184 Node *phi = PhiNode::make_blank(outer, old_phi);
1185 phi->init_req(LoopNode::EntryControl, old_phi->in(LoopNode::EntryControl));
1186 phi->init_req(LoopNode::LoopBackControl, old_phi->in(outer_idx));
1187 phi = igvn.register_new_node_with_optimizer(phi, old_phi);
1188 // Make old Phi point to new Phi on the fall-in path
1189 igvn.hash_delete(old_phi);
1190 old_phi->set_req(LoopNode::EntryControl, phi);
1191 old_phi->del_req(outer_idx);
1192 igvn._worklist.push(old_phi);
1193 }
1194 }
1195
1196 // Use the new loop head instead of the old shared one
1197 _head = outer;
1198 phase->set_loop(_head, this);
1199 }
1200
1201 //------------------------------fix_parent-------------------------------------
1202 static void fix_parent( IdealLoopTree *loop, IdealLoopTree *parent ) {
1203 loop->_parent = parent;
1204 if( loop->_child ) fix_parent( loop->_child, loop );
1205 if( loop->_next ) fix_parent( loop->_next , parent );
1206 }
1207
1208 //------------------------------estimate_path_freq-----------------------------
1209 static float estimate_path_freq( Node *n ) {
1210 // Try to extract some path frequency info
1211 IfNode *iff;
1212 for( int i = 0; i < 50; i++ ) { // Skip through a bunch of uncommon tests
1213 uint nop = n->Opcode();
1214 if( nop == Op_SafePoint ) { // Skip any safepoint
1215 n = n->in(0);
1216 continue;
1217 }
1218 if( nop == Op_CatchProj ) { // Get count from a prior call
1219 // Assume call does not always throw exceptions: means the call-site
1220 // count is also the frequency of the fall-through path.
1221 assert( n->is_CatchProj(), "" );
1222 if( ((CatchProjNode*)n)->_con != CatchProjNode::fall_through_index )
1223 return 0.0f; // Assume call exception path is rare
1224 Node *call = n->in(0)->in(0)->in(0);
1225 assert( call->is_Call(), "expect a call here" );
1226 const JVMState *jvms = ((CallNode*)call)->jvms();
1227 ciMethodData* methodData = jvms->method()->method_data();
1228 if (!methodData->is_mature()) return 0.0f; // No call-site data
1229 ciProfileData* data = methodData->bci_to_data(jvms->bci());
1230 if ((data == NULL) || !data->is_CounterData()) {
1231 // no call profile available, try call's control input
1232 n = n->in(0);
1233 continue;
1234 }
1235 return data->as_CounterData()->count()/FreqCountInvocations;
1236 }
1237 // See if there's a gating IF test
1238 Node *n_c = n->in(0);
1239 if( !n_c->is_If() ) break; // No estimate available
1240 iff = n_c->as_If();
1241 if( iff->_fcnt != COUNT_UNKNOWN ) // Have a valid count?
1242 // Compute how much count comes on this path
1243 return ((nop == Op_IfTrue) ? iff->_prob : 1.0f - iff->_prob) * iff->_fcnt;
1244 // Have no count info. Skip dull uncommon-trap like branches.
1245 if( (nop == Op_IfTrue && iff->_prob < PROB_LIKELY_MAG(5)) ||
1246 (nop == Op_IfFalse && iff->_prob > PROB_UNLIKELY_MAG(5)) )
1247 break;
1248 // Skip through never-taken branch; look for a real loop exit.
1249 n = iff->in(0);
1250 }
1251 return 0.0f; // No estimate available
1252 }
1253
1254 //------------------------------merge_many_backedges---------------------------
1255 // Merge all the backedges from the shared header into a private Region.
1256 // Feed that region as the one backedge to this loop.
1257 void IdealLoopTree::merge_many_backedges( PhaseIdealLoop *phase ) {
1258 uint i;
1259
1260 // Scan for the top 2 hottest backedges
1261 float hotcnt = 0.0f;
1262 float warmcnt = 0.0f;
1263 uint hot_idx = 0;
1264 // Loop starts at 2 because slot 1 is the fall-in path
1265 for( i = 2; i < _head->req(); i++ ) {
1266 float cnt = estimate_path_freq(_head->in(i));
1267 if( cnt > hotcnt ) { // Grab hottest path
1268 warmcnt = hotcnt;
1269 hotcnt = cnt;
1270 hot_idx = i;
1271 } else if( cnt > warmcnt ) { // And 2nd hottest path
1272 warmcnt = cnt;
1273 }
1274 }
1275
1276 // See if the hottest backedge is worthy of being an inner loop
1277 // by being much hotter than the next hottest backedge.
1278 if( hotcnt <= 0.0001 ||
1279 hotcnt < 2.0*warmcnt ) hot_idx = 0;// No hot backedge
1280
1281 // Peel out the backedges into a private merge point; peel
1282 // them all except optionally hot_idx.
1283 PhaseIterGVN &igvn = phase->_igvn;
1284
1285 Node *hot_tail = NULL;
1286 // Make a Region for the merge point
1287 Node *r = new (phase->C, 1) RegionNode(1);
1288 for( i = 2; i < _head->req(); i++ ) {
1289 if( i != hot_idx )
1290 r->add_req( _head->in(i) );
1291 else hot_tail = _head->in(i);
1292 }
1293 igvn.register_new_node_with_optimizer(r, _head);
1294 // Plug region into end of loop _head, followed by hot_tail
1295 while( _head->req() > 3 ) _head->del_req( _head->req()-1 );
1296 _head->set_req(2, r);
1297 if( hot_idx ) _head->add_req(hot_tail);
1298
1299 // Split all the Phis up between '_head' loop and the Region 'r'
1300 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1301 Node *out = _head->fast_out(j);
1302 if( out->is_Phi() ) {
1303 PhiNode* n = out->as_Phi();
1304 igvn.hash_delete(n); // Delete from hash before hacking edges
1305 Node *hot_phi = NULL;
1306 Node *phi = new (phase->C, r->req()) PhiNode(r, n->type(), n->adr_type());
1307 // Check all inputs for the ones to peel out
1308 uint j = 1;
1309 for( uint i = 2; i < n->req(); i++ ) {
1310 if( i != hot_idx )
1311 phi->set_req( j++, n->in(i) );
1312 else hot_phi = n->in(i);
1313 }
1314 // Register the phi but do not transform until whole place transforms
1315 igvn.register_new_node_with_optimizer(phi, n);
1316 // Add the merge phi to the old Phi
1317 while( n->req() > 3 ) n->del_req( n->req()-1 );
1318 n->set_req(2, phi);
1319 if( hot_idx ) n->add_req(hot_phi);
1320 }
1321 }
1322
1323
1324 // Insert a new IdealLoopTree inserted below me. Turn it into a clone
1325 // of self loop tree. Turn self into a loop headed by _head and with
1326 // tail being the new merge point.
1327 IdealLoopTree *ilt = new IdealLoopTree( phase, _head, _tail );
1328 phase->set_loop(_tail,ilt); // Adjust tail
1329 _tail = r; // Self's tail is new merge point
1330 phase->set_loop(r,this);
1331 ilt->_child = _child; // New guy has my children
1332 _child = ilt; // Self has new guy as only child
1333 ilt->_parent = this; // new guy has self for parent
1334 ilt->_nest = _nest; // Same nesting depth (for now)
1335
1336 // Starting with 'ilt', look for child loop trees using the same shared
1337 // header. Flatten these out; they will no longer be loops in the end.
1338 IdealLoopTree **pilt = &_child;
1339 while( ilt ) {
1340 if( ilt->_head == _head ) {
1341 uint i;
1342 for( i = 2; i < _head->req(); i++ )
1343 if( _head->in(i) == ilt->_tail )
1344 break; // Still a loop
1345 if( i == _head->req() ) { // No longer a loop
1346 // Flatten ilt. Hang ilt's "_next" list from the end of
1347 // ilt's '_child' list. Move the ilt's _child up to replace ilt.
1348 IdealLoopTree **cp = &ilt->_child;
1349 while( *cp ) cp = &(*cp)->_next; // Find end of child list
1350 *cp = ilt->_next; // Hang next list at end of child list
1351 *pilt = ilt->_child; // Move child up to replace ilt
1352 ilt->_head = NULL; // Flag as a loop UNIONED into parent
1353 ilt = ilt->_child; // Repeat using new ilt
1354 continue; // do not advance over ilt->_child
1355 }
1356 assert( ilt->_tail == hot_tail, "expected to only find the hot inner loop here" );
1357 phase->set_loop(_head,ilt);
1358 }
1359 pilt = &ilt->_child; // Advance to next
1360 ilt = *pilt;
1361 }
1362
1363 if( _child ) fix_parent( _child, this );
1364 }
1365
1366 //------------------------------beautify_loops---------------------------------
1367 // Split shared headers and insert loop landing pads.
1368 // Insert a LoopNode to replace the RegionNode.
1369 // Return TRUE if loop tree is structurally changed.
1370 bool IdealLoopTree::beautify_loops( PhaseIdealLoop *phase ) {
1371 bool result = false;
1372 // Cache parts in locals for easy
1373 PhaseIterGVN &igvn = phase->_igvn;
1374
1375 igvn.hash_delete(_head); // Yank from hash before hacking edges
1376
1377 // Check for multiple fall-in paths. Peel off a landing pad if need be.
1378 int fall_in_cnt = 0;
1379 for( uint i = 1; i < _head->req(); i++ )
1380 if( !phase->is_member( this, _head->in(i) ) )
1381 fall_in_cnt++;
1382 assert( fall_in_cnt, "at least 1 fall-in path" );
1383 if( fall_in_cnt > 1 ) // Need a loop landing pad to merge fall-ins
1384 split_fall_in( phase, fall_in_cnt );
1385
1386 // Swap inputs to the _head and all Phis to move the fall-in edge to
1387 // the left.
1388 fall_in_cnt = 1;
1389 while( phase->is_member( this, _head->in(fall_in_cnt) ) )
1390 fall_in_cnt++;
1391 if( fall_in_cnt > 1 ) {
1392 // Since I am just swapping inputs I do not need to update def-use info
1393 Node *tmp = _head->in(1);
1394 _head->set_req( 1, _head->in(fall_in_cnt) );
1395 _head->set_req( fall_in_cnt, tmp );
1396 // Swap also all Phis
1397 for (DUIterator_Fast imax, i = _head->fast_outs(imax); i < imax; i++) {
1398 Node* phi = _head->fast_out(i);
1399 if( phi->is_Phi() ) {
1400 igvn.hash_delete(phi); // Yank from hash before hacking edges
1401 tmp = phi->in(1);
1402 phi->set_req( 1, phi->in(fall_in_cnt) );
1403 phi->set_req( fall_in_cnt, tmp );
1404 }
1405 }
1406 }
1407 assert( !phase->is_member( this, _head->in(1) ), "left edge is fall-in" );
1408 assert( phase->is_member( this, _head->in(2) ), "right edge is loop" );
1409
1410 // If I am a shared header (multiple backedges), peel off the many
1411 // backedges into a private merge point and use the merge point as
1412 // the one true backedge.
1413 if( _head->req() > 3 ) {
1414 // Merge the many backedges into a single backedge but leave
1415 // the hottest backedge as separate edge for the following peel.
1416 merge_many_backedges( phase );
1417 result = true;
1418 }
1419
1420 // If I have one hot backedge, peel off myself loop.
1421 // I better be the outermost loop.
1422 if( _head->req() > 3 ) {
1423 split_outer_loop( phase );
1424 result = true;
1425
1426 } else if( !_head->is_Loop() && !_irreducible ) {
1427 // Make a new LoopNode to replace the old loop head
1428 Node *l = new (phase->C, 3) LoopNode( _head->in(1), _head->in(2) );
1429 l = igvn.register_new_node_with_optimizer(l, _head);
1430 phase->set_created_loop_node();
1431 // Go ahead and replace _head
1432 phase->_igvn.replace_node( _head, l );
1433 _head = l;
1434 phase->set_loop(_head, this);
1435 }
1436
1437 // Now recursively beautify nested loops
1438 if( _child ) result |= _child->beautify_loops( phase );
1439 if( _next ) result |= _next ->beautify_loops( phase );
1440 return result;
1441 }
1442
1443 //------------------------------allpaths_check_safepts----------------------------
1444 // Allpaths backwards scan from loop tail, terminating each path at first safepoint
1445 // encountered. Helper for check_safepts.
1446 void IdealLoopTree::allpaths_check_safepts(VectorSet &visited, Node_List &stack) {
1447 assert(stack.size() == 0, "empty stack");
1448 stack.push(_tail);
1449 visited.Clear();
1450 visited.set(_tail->_idx);
1451 while (stack.size() > 0) {
1452 Node* n = stack.pop();
1453 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
1454 // Terminate this path
1455 } else if (n->Opcode() == Op_SafePoint) {
1456 if (_phase->get_loop(n) != this) {
1457 if (_required_safept == NULL) _required_safept = new Node_List();
1458 _required_safept->push(n); // save the one closest to the tail
1459 }
1460 // Terminate this path
1461 } else {
1462 uint start = n->is_Region() ? 1 : 0;
1463 uint end = n->is_Region() && !n->is_Loop() ? n->req() : start + 1;
1464 for (uint i = start; i < end; i++) {
1465 Node* in = n->in(i);
1466 assert(in->is_CFG(), "must be");
1467 if (!visited.test_set(in->_idx) && is_member(_phase->get_loop(in))) {
1468 stack.push(in);
1469 }
1470 }
1471 }
1472 }
1473 }
1474
1475 //------------------------------check_safepts----------------------------
1476 // Given dominators, try to find loops with calls that must always be
1477 // executed (call dominates loop tail). These loops do not need non-call
1478 // safepoints (ncsfpt).
1479 //
1480 // A complication is that a safepoint in a inner loop may be needed
1481 // by an outer loop. In the following, the inner loop sees it has a
1482 // call (block 3) on every path from the head (block 2) to the
1483 // backedge (arc 3->2). So it deletes the ncsfpt (non-call safepoint)
1484 // in block 2, _but_ this leaves the outer loop without a safepoint.
1485 //
1486 // entry 0
1487 // |
1488 // v
1489 // outer 1,2 +->1
1490 // | |
1491 // | v
1492 // | 2<---+ ncsfpt in 2
1493 // |_/|\ |
1494 // | v |
1495 // inner 2,3 / 3 | call in 3
1496 // / | |
1497 // v +--+
1498 // exit 4
1499 //
1500 //
1501 // This method creates a list (_required_safept) of ncsfpt nodes that must
1502 // be protected is created for each loop. When a ncsfpt maybe deleted, it
1503 // is first looked for in the lists for the outer loops of the current loop.
1504 //
1505 // The insights into the problem:
1506 // A) counted loops are okay
1507 // B) innermost loops are okay (only an inner loop can delete
1508 // a ncsfpt needed by an outer loop)
1509 // C) a loop is immune from an inner loop deleting a safepoint
1510 // if the loop has a call on the idom-path
1511 // D) a loop is also immune if it has a ncsfpt (non-call safepoint) on the
1512 // idom-path that is not in a nested loop
1513 // E) otherwise, an ncsfpt on the idom-path that is nested in an inner
1514 // loop needs to be prevented from deletion by an inner loop
1515 //
1516 // There are two analyses:
1517 // 1) The first, and cheaper one, scans the loop body from
1518 // tail to head following the idom (immediate dominator)
1519 // chain, looking for the cases (C,D,E) above.
1520 // Since inner loops are scanned before outer loops, there is summary
1521 // information about inner loops. Inner loops can be skipped over
1522 // when the tail of an inner loop is encountered.
1523 //
1524 // 2) The second, invoked if the first fails to find a call or ncsfpt on
1525 // the idom path (which is rare), scans all predecessor control paths
1526 // from the tail to the head, terminating a path when a call or sfpt
1527 // is encountered, to find the ncsfpt's that are closest to the tail.
1528 //
1529 void IdealLoopTree::check_safepts(VectorSet &visited, Node_List &stack) {
1530 // Bottom up traversal
1531 IdealLoopTree* ch = _child;
1532 while (ch != NULL) {
1533 ch->check_safepts(visited, stack);
1534 ch = ch->_next;
1535 }
1536
1537 if (!_head->is_CountedLoop() && !_has_sfpt && _parent != NULL && !_irreducible) {
1538 bool has_call = false; // call on dom-path
1539 bool has_local_ncsfpt = false; // ncsfpt on dom-path at this loop depth
1540 Node* nonlocal_ncsfpt = NULL; // ncsfpt on dom-path at a deeper depth
1541 // Scan the dom-path nodes from tail to head
1542 for (Node* n = tail(); n != _head; n = _phase->idom(n)) {
1543 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
1544 has_call = true;
1545 _has_sfpt = 1; // Then no need for a safept!
1546 break;
1547 } else if (n->Opcode() == Op_SafePoint) {
1548 if (_phase->get_loop(n) == this) {
1549 has_local_ncsfpt = true;
1550 break;
1551 }
1552 if (nonlocal_ncsfpt == NULL) {
1553 nonlocal_ncsfpt = n; // save the one closest to the tail
1554 }
1555 } else {
1556 IdealLoopTree* nlpt = _phase->get_loop(n);
1557 if (this != nlpt) {
1558 // If at an inner loop tail, see if the inner loop has already
1559 // recorded seeing a call on the dom-path (and stop.) If not,
1560 // jump to the head of the inner loop.
1561 assert(is_member(nlpt), "nested loop");
1562 Node* tail = nlpt->_tail;
1563 if (tail->in(0)->is_If()) tail = tail->in(0);
1564 if (n == tail) {
1565 // If inner loop has call on dom-path, so does outer loop
1566 if (nlpt->_has_sfpt) {
1567 has_call = true;
1568 _has_sfpt = 1;
1569 break;
1570 }
1571 // Skip to head of inner loop
1572 assert(_phase->is_dominator(_head, nlpt->_head), "inner head dominated by outer head");
1573 n = nlpt->_head;
1574 }
1575 }
1576 }
1577 }
1578 // Record safept's that this loop needs preserved when an
1579 // inner loop attempts to delete it's safepoints.
1580 if (_child != NULL && !has_call && !has_local_ncsfpt) {
1581 if (nonlocal_ncsfpt != NULL) {
1582 if (_required_safept == NULL) _required_safept = new Node_List();
1583 _required_safept->push(nonlocal_ncsfpt);
1584 } else {
1585 // Failed to find a suitable safept on the dom-path. Now use
1586 // an all paths walk from tail to head, looking for safepoints to preserve.
1587 allpaths_check_safepts(visited, stack);
1588 }
1589 }
1590 }
1591 }
1592
1593 //---------------------------is_deleteable_safept----------------------------
1594 // Is safept not required by an outer loop?
1595 bool PhaseIdealLoop::is_deleteable_safept(Node* sfpt) {
1596 assert(sfpt->Opcode() == Op_SafePoint, "");
1597 IdealLoopTree* lp = get_loop(sfpt)->_parent;
1598 while (lp != NULL) {
1599 Node_List* sfpts = lp->_required_safept;
1600 if (sfpts != NULL) {
1601 for (uint i = 0; i < sfpts->size(); i++) {
1602 if (sfpt == sfpts->at(i))
1603 return false;
1604 }
1605 }
1606 lp = lp->_parent;
1607 }
1608 return true;
1609 }
1610
1611 //---------------------------replace_parallel_iv-------------------------------
1612 // Replace parallel induction variable (parallel to trip counter)
1613 void PhaseIdealLoop::replace_parallel_iv(IdealLoopTree *loop) {
1614 assert(loop->_head->is_CountedLoop(), "");
1615 CountedLoopNode *cl = loop->_head->as_CountedLoop();
1616 if (!cl->is_valid_counted_loop())
1617 return; // skip malformed counted loop
1618 Node *incr = cl->incr();
1619 if (incr == NULL)
1620 return; // Dead loop?
1621 Node *init = cl->init_trip();
1622 Node *phi = cl->phi();
1623 int stride_con = cl->stride_con();
1624
1625 // Visit all children, looking for Phis
1626 for (DUIterator i = cl->outs(); cl->has_out(i); i++) {
1627 Node *out = cl->out(i);
1628 // Look for other phis (secondary IVs). Skip dead ones
1629 if (!out->is_Phi() || out == phi || !has_node(out))
1630 continue;
1631 PhiNode* phi2 = out->as_Phi();
1632 Node *incr2 = phi2->in( LoopNode::LoopBackControl );
1633 // Look for induction variables of the form: X += constant
1634 if (phi2->region() != loop->_head ||
1635 incr2->req() != 3 ||
1636 incr2->in(1) != phi2 ||
1637 incr2 == incr ||
1638 incr2->Opcode() != Op_AddI ||
1639 !incr2->in(2)->is_Con())
1640 continue;
1641
1642 // Check for parallel induction variable (parallel to trip counter)
1643 // via an affine function. In particular, count-down loops with
1644 // count-up array indices are common. We only RCE references off
1645 // the trip-counter, so we need to convert all these to trip-counter
1646 // expressions.
1647 Node *init2 = phi2->in( LoopNode::EntryControl );
1648 int stride_con2 = incr2->in(2)->get_int();
1649
1650 // The general case here gets a little tricky. We want to find the
1651 // GCD of all possible parallel IV's and make a new IV using this
1652 // GCD for the loop. Then all possible IVs are simple multiples of
1653 // the GCD. In practice, this will cover very few extra loops.
1654 // Instead we require 'stride_con2' to be a multiple of 'stride_con',
1655 // where +/-1 is the common case, but other integer multiples are
1656 // also easy to handle.
1657 int ratio_con = stride_con2/stride_con;
1658
1659 if ((ratio_con * stride_con) == stride_con2) { // Check for exact
1660 #ifndef PRODUCT
1661 if (TraceLoopOpts) {
1662 tty->print("Parallel IV: %d ", phi2->_idx);
1663 loop->dump_head();
1664 }
1665 #endif
1666 // Convert to using the trip counter. The parallel induction
1667 // variable differs from the trip counter by a loop-invariant
1668 // amount, the difference between their respective initial values.
1669 // It is scaled by the 'ratio_con'.
1670 Node* ratio = _igvn.intcon(ratio_con);
1671 set_ctrl(ratio, C->root());
1672 Node* ratio_init = new (C, 3) MulINode(init, ratio);
1673 _igvn.register_new_node_with_optimizer(ratio_init, init);
1674 set_early_ctrl(ratio_init);
1675 Node* diff = new (C, 3) SubINode(init2, ratio_init);
1676 _igvn.register_new_node_with_optimizer(diff, init2);
1677 set_early_ctrl(diff);
1678 Node* ratio_idx = new (C, 3) MulINode(phi, ratio);
1679 _igvn.register_new_node_with_optimizer(ratio_idx, phi);
1680 set_ctrl(ratio_idx, cl);
1681 Node* add = new (C, 3) AddINode(ratio_idx, diff);
1682 _igvn.register_new_node_with_optimizer(add);
1683 set_ctrl(add, cl);
1684 _igvn.replace_node( phi2, add );
1685 // Sometimes an induction variable is unused
1686 if (add->outcnt() == 0) {
1687 _igvn.remove_dead_node(add);
1688 }
1689 --i; // deleted this phi; rescan starting with next position
1690 continue;
1691 }
1692 }
1693 }
1694
1695 //------------------------------counted_loop-----------------------------------
1696 // Convert to counted loops where possible
1697 void IdealLoopTree::counted_loop( PhaseIdealLoop *phase ) {
1698
1699 // For grins, set the inner-loop flag here
1700 if (!_child) {
1701 if (_head->is_Loop()) _head->as_Loop()->set_inner_loop();
1702 }
1703
1704 if (_head->is_CountedLoop() ||
1705 phase->is_counted_loop(_head, this)) {
1706 _has_sfpt = 1; // Indicate we do not need a safepoint here
1707
1708 // Look for a safepoint to remove
1709 for (Node* n = tail(); n != _head; n = phase->idom(n))
1710 if (n->Opcode() == Op_SafePoint && phase->get_loop(n) == this &&
1711 phase->is_deleteable_safept(n))
1712 phase->lazy_replace(n,n->in(TypeFunc::Control));
1713
1714 // Look for induction variables
1715 phase->replace_parallel_iv(this);
1716
1717 } else if (_parent != NULL && !_irreducible) {
1718 // Not a counted loop.
1719 // Look for a safepoint on the idom-path to remove, preserving the first one
1720 bool found = false;
1721 Node* n = tail();
1722 for (; n != _head && !found; n = phase->idom(n)) {
1723 if (n->Opcode() == Op_SafePoint && phase->get_loop(n) == this)
1724 found = true; // Found one
1725 }
1726 // Skip past it and delete the others
1727 for (; n != _head; n = phase->idom(n)) {
1728 if (n->Opcode() == Op_SafePoint && phase->get_loop(n) == this &&
1729 phase->is_deleteable_safept(n))
1730 phase->lazy_replace(n,n->in(TypeFunc::Control));
1731 }
1732 }
1733
1734 // Recursively
1735 if (_child) _child->counted_loop( phase );
1736 if (_next) _next ->counted_loop( phase );
1737 }
1738
1739 #ifndef PRODUCT
1740 //------------------------------dump_head--------------------------------------
1741 // Dump 1 liner for loop header info
1742 void IdealLoopTree::dump_head( ) const {
1743 for (uint i=0; i<_nest; i++)
1744 tty->print(" ");
1745 tty->print("Loop: N%d/N%d ",_head->_idx,_tail->_idx);
1746 if (_irreducible) tty->print(" IRREDUCIBLE");
1747 Node* entry = _head->in(LoopNode::EntryControl);
1748 if (LoopLimitCheck) {
1749 Node* predicate = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
1750 if (predicate != NULL ) {
1751 tty->print(" limit_check");
1752 entry = entry->in(0)->in(0);
1753 }
1754 }
1755 if (UseLoopPredicate) {
1756 entry = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
1757 if (entry != NULL) {
1758 tty->print(" predicated");
1759 }
1760 }
1761 if (_head->is_CountedLoop()) {
1762 CountedLoopNode *cl = _head->as_CountedLoop();
1763 tty->print(" counted");
1764
1765 Node* init_n = cl->init_trip();
1766 if (init_n != NULL && init_n->is_Con())
1767 tty->print(" [%d,", cl->init_trip()->get_int());
1768 else
1769 tty->print(" [int,");
1770 Node* limit_n = cl->limit();
1771 if (limit_n != NULL && limit_n->is_Con())
1772 tty->print("%d),", cl->limit()->get_int());
1773 else
1774 tty->print("int),");
1775 int stride_con = cl->stride_con();
1776 if (stride_con > 0) tty->print("+");
1777 tty->print("%d", stride_con);
1778
1779 if (cl->is_pre_loop ()) tty->print(" pre" );
1780 if (cl->is_main_loop()) tty->print(" main");
1781 if (cl->is_post_loop()) tty->print(" post");
1782 }
1783 tty->cr();
1784 }
1785
1786 //------------------------------dump-------------------------------------------
1787 // Dump loops by loop tree
1788 void IdealLoopTree::dump( ) const {
1789 dump_head();
1790 if (_child) _child->dump();
1791 if (_next) _next ->dump();
1792 }
1793
1794 #endif
1795
1796 static void log_loop_tree(IdealLoopTree* root, IdealLoopTree* loop, CompileLog* log) {
1797 if (loop == root) {
1798 if (loop->_child != NULL) {
1799 log->begin_head("loop_tree");
1800 log->end_head();
1801 if( loop->_child ) log_loop_tree(root, loop->_child, log);
1802 log->tail("loop_tree");
1803 assert(loop->_next == NULL, "what?");
1804 }
1805 } else {
1806 Node* head = loop->_head;
1807 log->begin_head("loop");
1808 log->print(" idx='%d' ", head->_idx);
1809 if (loop->_irreducible) log->print("irreducible='1' ");
1810 if (head->is_Loop()) {
1811 if (head->as_Loop()->is_inner_loop()) log->print("inner_loop='1' ");
1812 if (head->as_Loop()->is_partial_peel_loop()) log->print("partial_peel_loop='1' ");
1813 }
1814 if (head->is_CountedLoop()) {
1815 CountedLoopNode* cl = head->as_CountedLoop();
1816 if (cl->is_pre_loop()) log->print("pre_loop='%d' ", cl->main_idx());
1817 if (cl->is_main_loop()) log->print("main_loop='%d' ", cl->_idx);
1818 if (cl->is_post_loop()) log->print("post_loop='%d' ", cl->main_idx());
1819 }
1820 log->end_head();
1821 if( loop->_child ) log_loop_tree(root, loop->_child, log);
1822 log->tail("loop");
1823 if( loop->_next ) log_loop_tree(root, loop->_next, log);
1824 }
1825 }
1826
1827 //---------------------collect_potentially_useful_predicates-----------------------
1828 // Helper function to collect potentially useful predicates to prevent them from
1829 // being eliminated by PhaseIdealLoop::eliminate_useless_predicates
1830 void PhaseIdealLoop::collect_potentially_useful_predicates(
1831 IdealLoopTree * loop, Unique_Node_List &useful_predicates) {
1832 if (loop->_child) { // child
1833 collect_potentially_useful_predicates(loop->_child, useful_predicates);
1834 }
1835
1836 // self (only loops that we can apply loop predication may use their predicates)
1837 if (loop->_head->is_Loop() &&
1838 !loop->_irreducible &&
1839 !loop->tail()->is_top()) {
1840 LoopNode* lpn = loop->_head->as_Loop();
1841 Node* entry = lpn->in(LoopNode::EntryControl);
1842 Node* predicate_proj = find_predicate(entry); // loop_limit_check first
1843 if (predicate_proj != NULL ) { // right pattern that can be used by loop predication
1844 assert(entry->in(0)->in(1)->in(1)->Opcode() == Op_Opaque1, "must be");
1845 useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one
1846 entry = entry->in(0)->in(0);
1847 }
1848 predicate_proj = find_predicate(entry); // Predicate
1849 if (predicate_proj != NULL ) {
1850 useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one
1851 }
1852 }
1853
1854 if (loop->_next) { // sibling
1855 collect_potentially_useful_predicates(loop->_next, useful_predicates);
1856 }
1857 }
1858
1859 //------------------------eliminate_useless_predicates-----------------------------
1860 // Eliminate all inserted predicates if they could not be used by loop predication.
1861 // Note: it will also eliminates loop limits check predicate since it also uses
1862 // Opaque1 node (see Parse::add_predicate()).
1863 void PhaseIdealLoop::eliminate_useless_predicates() {
1864 if (C->predicate_count() == 0)
1865 return; // no predicate left
1866
1867 Unique_Node_List useful_predicates; // to store useful predicates
1868 if (C->has_loops()) {
1869 collect_potentially_useful_predicates(_ltree_root->_child, useful_predicates);
1870 }
1871
1872 for (int i = C->predicate_count(); i > 0; i--) {
1873 Node * n = C->predicate_opaque1_node(i-1);
1874 assert(n->Opcode() == Op_Opaque1, "must be");
1875 if (!useful_predicates.member(n)) { // not in the useful list
1876 _igvn.replace_node(n, n->in(1));
1877 }
1878 }
1879 }
1880
1881 //=============================================================================
1882 //----------------------------build_and_optimize-------------------------------
1883 // Create a PhaseLoop. Build the ideal Loop tree. Map each Ideal Node to
1884 // its corresponding LoopNode. If 'optimize' is true, do some loop cleanups.
1885 void PhaseIdealLoop::build_and_optimize(bool do_split_ifs, bool skip_loop_opts) {
1886 ResourceMark rm;
1887
1888 int old_progress = C->major_progress();
1889 uint orig_worklist_size = _igvn._worklist.size();
1890
1891 // Reset major-progress flag for the driver's heuristics
1892 C->clear_major_progress();
1893
1894 #ifndef PRODUCT
1895 // Capture for later assert
1896 uint unique = C->unique();
1897 _loop_invokes++;
1898 _loop_work += unique;
1899 #endif
1900
1901 // True if the method has at least 1 irreducible loop
1902 _has_irreducible_loops = false;
1903
1904 _created_loop_node = false;
1905
1906 Arena *a = Thread::current()->resource_area();
1907 VectorSet visited(a);
1908 // Pre-grow the mapping from Nodes to IdealLoopTrees.
1909 _nodes.map(C->unique(), NULL);
1910 memset(_nodes.adr(), 0, wordSize * C->unique());
1911
1912 // Pre-build the top-level outermost loop tree entry
1913 _ltree_root = new IdealLoopTree( this, C->root(), C->root() );
1914 // Do not need a safepoint at the top level
1915 _ltree_root->_has_sfpt = 1;
1916
1917 // Initialize Dominators.
1918 // Checked in clone_loop_predicate() during beautify_loops().
1919 _idom_size = 0;
1920 _idom = NULL;
1921 _dom_depth = NULL;
1922 _dom_stk = NULL;
1923
1924 // Empty pre-order array
1925 allocate_preorders();
1926
1927 // Build a loop tree on the fly. Build a mapping from CFG nodes to
1928 // IdealLoopTree entries. Data nodes are NOT walked.
1929 build_loop_tree();
1930 // Check for bailout, and return
1931 if (C->failing()) {
1932 return;
1933 }
1934
1935 // No loops after all
1936 if( !_ltree_root->_child && !_verify_only ) C->set_has_loops(false);
1937
1938 // There should always be an outer loop containing the Root and Return nodes.
1939 // If not, we have a degenerate empty program. Bail out in this case.
1940 if (!has_node(C->root())) {
1941 if (!_verify_only) {
1942 C->clear_major_progress();
1943 C->record_method_not_compilable("empty program detected during loop optimization");
1944 }
1945 return;
1946 }
1947
1948 // Nothing to do, so get out
1949 if( !C->has_loops() && !skip_loop_opts && !do_split_ifs && !_verify_me && !_verify_only ) {
1950 _igvn.optimize(); // Cleanup NeverBranches
1951 return;
1952 }
1953
1954 // Set loop nesting depth
1955 _ltree_root->set_nest( 0 );
1956
1957 // Split shared headers and insert loop landing pads.
1958 // Do not bother doing this on the Root loop of course.
1959 if( !_verify_me && !_verify_only && _ltree_root->_child ) {
1960 C->print_method("Before beautify loops", 3);
1961 if( _ltree_root->_child->beautify_loops( this ) ) {
1962 // Re-build loop tree!
1963 _ltree_root->_child = NULL;
1964 _nodes.clear();
1965 reallocate_preorders();
1966 build_loop_tree();
1967 // Check for bailout, and return
1968 if (C->failing()) {
1969 return;
1970 }
1971 // Reset loop nesting depth
1972 _ltree_root->set_nest( 0 );
1973
1974 C->print_method("After beautify loops", 3);
1975 }
1976 }
1977
1978 // Build Dominators for elision of NULL checks & loop finding.
1979 // Since nodes do not have a slot for immediate dominator, make
1980 // a persistent side array for that info indexed on node->_idx.
1981 _idom_size = C->unique();
1982 _idom = NEW_RESOURCE_ARRAY( Node*, _idom_size );
1983 _dom_depth = NEW_RESOURCE_ARRAY( uint, _idom_size );
1984 _dom_stk = NULL; // Allocated on demand in recompute_dom_depth
1985 memset( _dom_depth, 0, _idom_size * sizeof(uint) );
1986
1987 Dominators();
1988
1989 if (!_verify_only) {
1990 // As a side effect, Dominators removed any unreachable CFG paths
1991 // into RegionNodes. It doesn't do this test against Root, so
1992 // we do it here.
1993 for( uint i = 1; i < C->root()->req(); i++ ) {
1994 if( !_nodes[C->root()->in(i)->_idx] ) { // Dead path into Root?
1995 _igvn.hash_delete(C->root());
1996 C->root()->del_req(i);
1997 _igvn._worklist.push(C->root());
1998 i--; // Rerun same iteration on compressed edges
1999 }
2000 }
2001
2002 // Given dominators, try to find inner loops with calls that must
2003 // always be executed (call dominates loop tail). These loops do
2004 // not need a separate safepoint.
2005 Node_List cisstack(a);
2006 _ltree_root->check_safepts(visited, cisstack);
2007 }
2008
2009 // Walk the DATA nodes and place into loops. Find earliest control
2010 // node. For CFG nodes, the _nodes array starts out and remains
2011 // holding the associated IdealLoopTree pointer. For DATA nodes, the
2012 // _nodes array holds the earliest legal controlling CFG node.
2013
2014 // Allocate stack with enough space to avoid frequent realloc
2015 int stack_size = (C->unique() >> 1) + 16; // (unique>>1)+16 from Java2D stats
2016 Node_Stack nstack( a, stack_size );
2017
2018 visited.Clear();
2019 Node_List worklist(a);
2020 // Don't need C->root() on worklist since
2021 // it will be processed among C->top() inputs
2022 worklist.push( C->top() );
2023 visited.set( C->top()->_idx ); // Set C->top() as visited now
2024 build_loop_early( visited, worklist, nstack );
2025
2026 // Given early legal placement, try finding counted loops. This placement
2027 // is good enough to discover most loop invariants.
2028 if( !_verify_me && !_verify_only )
2029 _ltree_root->counted_loop( this );
2030
2031 // Find latest loop placement. Find ideal loop placement.
2032 visited.Clear();
2033 init_dom_lca_tags();
2034 // Need C->root() on worklist when processing outs
2035 worklist.push( C->root() );
2036 NOT_PRODUCT( C->verify_graph_edges(); )
2037 worklist.push( C->top() );
2038 build_loop_late( visited, worklist, nstack );
2039
2040 if (_verify_only) {
2041 // restore major progress flag
2042 for (int i = 0; i < old_progress; i++)
2043 C->set_major_progress();
2044 assert(C->unique() == unique, "verification mode made Nodes? ? ?");
2045 assert(_igvn._worklist.size() == orig_worklist_size, "shouldn't push anything");
2046 return;
2047 }
2048
2049 // Some parser-inserted loop predicates could never be used by loop
2050 // predication or they were moved away from loop during some optimizations.
2051 // For example, peeling. Eliminate them before next loop optimizations.
2052 if (UseLoopPredicate || LoopLimitCheck) {
2053 eliminate_useless_predicates();
2054 }
2055
2056 // clear out the dead code
2057 while(_deadlist.size()) {
2058 _igvn.remove_globally_dead_node(_deadlist.pop());
2059 }
2060
2061 #ifndef PRODUCT
2062 C->verify_graph_edges();
2063 if (_verify_me) { // Nested verify pass?
2064 // Check to see if the verify mode is broken
2065 assert(C->unique() == unique, "non-optimize mode made Nodes? ? ?");
2066 return;
2067 }
2068 if(VerifyLoopOptimizations) verify();
2069 if(TraceLoopOpts && C->has_loops()) {
2070 _ltree_root->dump();
2071 }
2072 #endif
2073
2074 if (skip_loop_opts) {
2075 // Cleanup any modified bits
2076 _igvn.optimize();
2077
2078 if (C->log() != NULL) {
2079 log_loop_tree(_ltree_root, _ltree_root, C->log());
2080 }
2081 return;
2082 }
2083
2084 if (ReassociateInvariants) {
2085 // Reassociate invariants and prep for split_thru_phi
2086 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
2087 IdealLoopTree* lpt = iter.current();
2088 if (!lpt->is_counted() || !lpt->is_inner()) continue;
2089
2090 lpt->reassociate_invariants(this);
2091
2092 // Because RCE opportunities can be masked by split_thru_phi,
2093 // look for RCE candidates and inhibit split_thru_phi
2094 // on just their loop-phi's for this pass of loop opts
2095 if (SplitIfBlocks && do_split_ifs) {
2096 if (lpt->policy_range_check(this)) {
2097 lpt->_rce_candidate = 1; // = true
2098 }
2099 }
2100 }
2101 }
2102
2103 // Check for aggressive application of split-if and other transforms
2104 // that require basic-block info (like cloning through Phi's)
2105 if( SplitIfBlocks && do_split_ifs ) {
2106 visited.Clear();
2107 split_if_with_blocks( visited, nstack );
2108 NOT_PRODUCT( if( VerifyLoopOptimizations ) verify(); );
2109 }
2110
2111 // Perform loop predication before iteration splitting
2112 if (C->has_loops() && !C->major_progress() && (C->predicate_count() > 0)) {
2113 _ltree_root->_child->loop_predication(this);
2114 }
2115
2116 if (OptimizeFill && UseLoopPredicate && C->has_loops() && !C->major_progress()) {
2117 if (do_intrinsify_fill()) {
2118 C->set_major_progress();
2119 }
2120 }
2121
2122 // Perform iteration-splitting on inner loops. Split iterations to avoid
2123 // range checks or one-shot null checks.
2124
2125 // If split-if's didn't hack the graph too bad (no CFG changes)
2126 // then do loop opts.
2127 if (C->has_loops() && !C->major_progress()) {
2128 memset( worklist.adr(), 0, worklist.Size()*sizeof(Node*) );
2129 _ltree_root->_child->iteration_split( this, worklist );
2130 // No verify after peeling! GCM has hoisted code out of the loop.
2131 // After peeling, the hoisted code could sink inside the peeled area.
2132 // The peeling code does not try to recompute the best location for
2133 // all the code before the peeled area, so the verify pass will always
2134 // complain about it.
2135 }
2136 // Do verify graph edges in any case
2137 NOT_PRODUCT( C->verify_graph_edges(); );
2138
2139 if (!do_split_ifs) {
2140 // We saw major progress in Split-If to get here. We forced a
2141 // pass with unrolling and not split-if, however more split-if's
2142 // might make progress. If the unrolling didn't make progress
2143 // then the major-progress flag got cleared and we won't try
2144 // another round of Split-If. In particular the ever-common
2145 // instance-of/check-cast pattern requires at least 2 rounds of
2146 // Split-If to clear out.
2147 C->set_major_progress();
2148 }
2149
2150 // Repeat loop optimizations if new loops were seen
2151 if (created_loop_node()) {
2152 C->set_major_progress();
2153 }
2154
2155 // Keep loop predicates and perform optimizations with them
2156 // until no more loop optimizations could be done.
2157 // After that switch predicates off and do more loop optimizations.
2158 if (!C->major_progress() && (C->predicate_count() > 0)) {
2159 C->cleanup_loop_predicates(_igvn);
2160 #ifndef PRODUCT
2161 if (TraceLoopOpts) {
2162 tty->print_cr("PredicatesOff");
2163 }
2164 #endif
2165 C->set_major_progress();
2166 }
2167
2168 // Convert scalar to superword operations at the end of all loop opts.
2169 if (UseSuperWord && C->has_loops() && !C->major_progress()) {
2170 // SuperWord transform
2171 SuperWord sw(this);
2172 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
2173 IdealLoopTree* lpt = iter.current();
2174 if (lpt->is_counted()) {
2175 sw.transform_loop(lpt);
2176 }
2177 }
2178 }
2179
2180 // Cleanup any modified bits
2181 _igvn.optimize();
2182
2183 // disable assert until issue with split_flow_path is resolved (6742111)
2184 // assert(!_has_irreducible_loops || C->parsed_irreducible_loop() || C->is_osr_compilation(),
2185 // "shouldn't introduce irreducible loops");
2186
2187 if (C->log() != NULL) {
2188 log_loop_tree(_ltree_root, _ltree_root, C->log());
2189 }
2190 }
2191
2192 #ifndef PRODUCT
2193 //------------------------------print_statistics-------------------------------
2194 int PhaseIdealLoop::_loop_invokes=0;// Count of PhaseIdealLoop invokes
2195 int PhaseIdealLoop::_loop_work=0; // Sum of PhaseIdealLoop x unique
2196 void PhaseIdealLoop::print_statistics() {
2197 tty->print_cr("PhaseIdealLoop=%d, sum _unique=%d", _loop_invokes, _loop_work);
2198 }
2199
2200 //------------------------------verify-----------------------------------------
2201 // Build a verify-only PhaseIdealLoop, and see that it agrees with me.
2202 static int fail; // debug only, so its multi-thread dont care
2203 void PhaseIdealLoop::verify() const {
2204 int old_progress = C->major_progress();
2205 ResourceMark rm;
2206 PhaseIdealLoop loop_verify( _igvn, this );
2207 VectorSet visited(Thread::current()->resource_area());
2208
2209 fail = 0;
2210 verify_compare( C->root(), &loop_verify, visited );
2211 assert( fail == 0, "verify loops failed" );
2212 // Verify loop structure is the same
2213 _ltree_root->verify_tree(loop_verify._ltree_root, NULL);
2214 // Reset major-progress. It was cleared by creating a verify version of
2215 // PhaseIdealLoop.
2216 for( int i=0; i<old_progress; i++ )
2217 C->set_major_progress();
2218 }
2219
2220 //------------------------------verify_compare---------------------------------
2221 // Make sure me and the given PhaseIdealLoop agree on key data structures
2222 void PhaseIdealLoop::verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const {
2223 if( !n ) return;
2224 if( visited.test_set( n->_idx ) ) return;
2225 if( !_nodes[n->_idx] ) { // Unreachable
2226 assert( !loop_verify->_nodes[n->_idx], "both should be unreachable" );
2227 return;
2228 }
2229
2230 uint i;
2231 for( i = 0; i < n->req(); i++ )
2232 verify_compare( n->in(i), loop_verify, visited );
2233
2234 // Check the '_nodes' block/loop structure
2235 i = n->_idx;
2236 if( has_ctrl(n) ) { // We have control; verify has loop or ctrl
2237 if( _nodes[i] != loop_verify->_nodes[i] &&
2238 get_ctrl_no_update(n) != loop_verify->get_ctrl_no_update(n) ) {
2239 tty->print("Mismatched control setting for: ");
2240 n->dump();
2241 if( fail++ > 10 ) return;
2242 Node *c = get_ctrl_no_update(n);
2243 tty->print("We have it as: ");
2244 if( c->in(0) ) c->dump();
2245 else tty->print_cr("N%d",c->_idx);
2246 tty->print("Verify thinks: ");
2247 if( loop_verify->has_ctrl(n) )
2248 loop_verify->get_ctrl_no_update(n)->dump();
2249 else
2250 loop_verify->get_loop_idx(n)->dump();
2251 tty->cr();
2252 }
2253 } else { // We have a loop
2254 IdealLoopTree *us = get_loop_idx(n);
2255 if( loop_verify->has_ctrl(n) ) {
2256 tty->print("Mismatched loop setting for: ");
2257 n->dump();
2258 if( fail++ > 10 ) return;
2259 tty->print("We have it as: ");
2260 us->dump();
2261 tty->print("Verify thinks: ");
2262 loop_verify->get_ctrl_no_update(n)->dump();
2263 tty->cr();
2264 } else if (!C->major_progress()) {
2265 // Loop selection can be messed up if we did a major progress
2266 // operation, like split-if. Do not verify in that case.
2267 IdealLoopTree *them = loop_verify->get_loop_idx(n);
2268 if( us->_head != them->_head || us->_tail != them->_tail ) {
2269 tty->print("Unequals loops for: ");
2270 n->dump();
2271 if( fail++ > 10 ) return;
2272 tty->print("We have it as: ");
2273 us->dump();
2274 tty->print("Verify thinks: ");
2275 them->dump();
2276 tty->cr();
2277 }
2278 }
2279 }
2280
2281 // Check for immediate dominators being equal
2282 if( i >= _idom_size ) {
2283 if( !n->is_CFG() ) return;
2284 tty->print("CFG Node with no idom: ");
2285 n->dump();
2286 return;
2287 }
2288 if( !n->is_CFG() ) return;
2289 if( n == C->root() ) return; // No IDOM here
2290
2291 assert(n->_idx == i, "sanity");
2292 Node *id = idom_no_update(n);
2293 if( id != loop_verify->idom_no_update(n) ) {
2294 tty->print("Unequals idoms for: ");
2295 n->dump();
2296 if( fail++ > 10 ) return;
2297 tty->print("We have it as: ");
2298 id->dump();
2299 tty->print("Verify thinks: ");
2300 loop_verify->idom_no_update(n)->dump();
2301 tty->cr();
2302 }
2303
2304 }
2305
2306 //------------------------------verify_tree------------------------------------
2307 // Verify that tree structures match. Because the CFG can change, siblings
2308 // within the loop tree can be reordered. We attempt to deal with that by
2309 // reordering the verify's loop tree if possible.
2310 void IdealLoopTree::verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const {
2311 assert( _parent == parent, "Badly formed loop tree" );
2312
2313 // Siblings not in same order? Attempt to re-order.
2314 if( _head != loop->_head ) {
2315 // Find _next pointer to update
2316 IdealLoopTree **pp = &loop->_parent->_child;
2317 while( *pp != loop )
2318 pp = &((*pp)->_next);
2319 // Find proper sibling to be next
2320 IdealLoopTree **nn = &loop->_next;
2321 while( (*nn) && (*nn)->_head != _head )
2322 nn = &((*nn)->_next);
2323
2324 // Check for no match.
2325 if( !(*nn) ) {
2326 // Annoyingly, irreducible loops can pick different headers
2327 // after a major_progress operation, so the rest of the loop
2328 // tree cannot be matched.
2329 if (_irreducible && Compile::current()->major_progress()) return;
2330 assert( 0, "failed to match loop tree" );
2331 }
2332
2333 // Move (*nn) to (*pp)
2334 IdealLoopTree *hit = *nn;
2335 *nn = hit->_next;
2336 hit->_next = loop;
2337 *pp = loop;
2338 loop = hit;
2339 // Now try again to verify
2340 }
2341
2342 assert( _head == loop->_head , "mismatched loop head" );
2343 Node *tail = _tail; // Inline a non-updating version of
2344 while( !tail->in(0) ) // the 'tail()' call.
2345 tail = tail->in(1);
2346 assert( tail == loop->_tail, "mismatched loop tail" );
2347
2348 // Counted loops that are guarded should be able to find their guards
2349 if( _head->is_CountedLoop() && _head->as_CountedLoop()->is_main_loop() ) {
2350 CountedLoopNode *cl = _head->as_CountedLoop();
2351 Node *init = cl->init_trip();
2352 Node *ctrl = cl->in(LoopNode::EntryControl);
2353 assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" );
2354 Node *iff = ctrl->in(0);
2355 assert( iff->Opcode() == Op_If, "" );
2356 Node *bol = iff->in(1);
2357 assert( bol->Opcode() == Op_Bool, "" );
2358 Node *cmp = bol->in(1);
2359 assert( cmp->Opcode() == Op_CmpI, "" );
2360 Node *add = cmp->in(1);
2361 Node *opaq;
2362 if( add->Opcode() == Op_Opaque1 ) {
2363 opaq = add;
2364 } else {
2365 assert( add->Opcode() == Op_AddI || add->Opcode() == Op_ConI , "" );
2366 assert( add == init, "" );
2367 opaq = cmp->in(2);
2368 }
2369 assert( opaq->Opcode() == Op_Opaque1, "" );
2370
2371 }
2372
2373 if (_child != NULL) _child->verify_tree(loop->_child, this);
2374 if (_next != NULL) _next ->verify_tree(loop->_next, parent);
2375 // Innermost loops need to verify loop bodies,
2376 // but only if no 'major_progress'
2377 int fail = 0;
2378 if (!Compile::current()->major_progress() && _child == NULL) {
2379 for( uint i = 0; i < _body.size(); i++ ) {
2380 Node *n = _body.at(i);
2381 if (n->outcnt() == 0) continue; // Ignore dead
2382 uint j;
2383 for( j = 0; j < loop->_body.size(); j++ )
2384 if( loop->_body.at(j) == n )
2385 break;
2386 if( j == loop->_body.size() ) { // Not found in loop body
2387 // Last ditch effort to avoid assertion: Its possible that we
2388 // have some users (so outcnt not zero) but are still dead.
2389 // Try to find from root.
2390 if (Compile::current()->root()->find(n->_idx)) {
2391 fail++;
2392 tty->print("We have that verify does not: ");
2393 n->dump();
2394 }
2395 }
2396 }
2397 for( uint i2 = 0; i2 < loop->_body.size(); i2++ ) {
2398 Node *n = loop->_body.at(i2);
2399 if (n->outcnt() == 0) continue; // Ignore dead
2400 uint j;
2401 for( j = 0; j < _body.size(); j++ )
2402 if( _body.at(j) == n )
2403 break;
2404 if( j == _body.size() ) { // Not found in loop body
2405 // Last ditch effort to avoid assertion: Its possible that we
2406 // have some users (so outcnt not zero) but are still dead.
2407 // Try to find from root.
2408 if (Compile::current()->root()->find(n->_idx)) {
2409 fail++;
2410 tty->print("Verify has that we do not: ");
2411 n->dump();
2412 }
2413 }
2414 }
2415 assert( !fail, "loop body mismatch" );
2416 }
2417 }
2418
2419 #endif
2420
2421 //------------------------------set_idom---------------------------------------
2422 void PhaseIdealLoop::set_idom(Node* d, Node* n, uint dom_depth) {
2423 uint idx = d->_idx;
2424 if (idx >= _idom_size) {
2425 uint newsize = _idom_size<<1;
2426 while( idx >= newsize ) {
2427 newsize <<= 1;
2428 }
2429 _idom = REALLOC_RESOURCE_ARRAY( Node*, _idom,_idom_size,newsize);
2430 _dom_depth = REALLOC_RESOURCE_ARRAY( uint, _dom_depth,_idom_size,newsize);
2431 memset( _dom_depth + _idom_size, 0, (newsize - _idom_size) * sizeof(uint) );
2432 _idom_size = newsize;
2433 }
2434 _idom[idx] = n;
2435 _dom_depth[idx] = dom_depth;
2436 }
2437
2438 //------------------------------recompute_dom_depth---------------------------------------
2439 // The dominator tree is constructed with only parent pointers.
2440 // This recomputes the depth in the tree by first tagging all
2441 // nodes as "no depth yet" marker. The next pass then runs up
2442 // the dom tree from each node marked "no depth yet", and computes
2443 // the depth on the way back down.
2444 void PhaseIdealLoop::recompute_dom_depth() {
2445 uint no_depth_marker = C->unique();
2446 uint i;
2447 // Initialize depth to "no depth yet"
2448 for (i = 0; i < _idom_size; i++) {
2449 if (_dom_depth[i] > 0 && _idom[i] != NULL) {
2450 _dom_depth[i] = no_depth_marker;
2451 }
2452 }
2453 if (_dom_stk == NULL) {
2454 uint init_size = C->unique() / 100; // Guess that 1/100 is a reasonable initial size.
2455 if (init_size < 10) init_size = 10;
2456 _dom_stk = new GrowableArray<uint>(init_size);
2457 }
2458 // Compute new depth for each node.
2459 for (i = 0; i < _idom_size; i++) {
2460 uint j = i;
2461 // Run up the dom tree to find a node with a depth
2462 while (_dom_depth[j] == no_depth_marker) {
2463 _dom_stk->push(j);
2464 j = _idom[j]->_idx;
2465 }
2466 // Compute the depth on the way back down this tree branch
2467 uint dd = _dom_depth[j] + 1;
2468 while (_dom_stk->length() > 0) {
2469 uint j = _dom_stk->pop();
2470 _dom_depth[j] = dd;
2471 dd++;
2472 }
2473 }
2474 }
2475
2476 //------------------------------sort-------------------------------------------
2477 // Insert 'loop' into the existing loop tree. 'innermost' is a leaf of the
2478 // loop tree, not the root.
2479 IdealLoopTree *PhaseIdealLoop::sort( IdealLoopTree *loop, IdealLoopTree *innermost ) {
2480 if( !innermost ) return loop; // New innermost loop
2481
2482 int loop_preorder = get_preorder(loop->_head); // Cache pre-order number
2483 assert( loop_preorder, "not yet post-walked loop" );
2484 IdealLoopTree **pp = &innermost; // Pointer to previous next-pointer
2485 IdealLoopTree *l = *pp; // Do I go before or after 'l'?
2486
2487 // Insert at start of list
2488 while( l ) { // Insertion sort based on pre-order
2489 if( l == loop ) return innermost; // Already on list!
2490 int l_preorder = get_preorder(l->_head); // Cache pre-order number
2491 assert( l_preorder, "not yet post-walked l" );
2492 // Check header pre-order number to figure proper nesting
2493 if( loop_preorder > l_preorder )
2494 break; // End of insertion
2495 // If headers tie (e.g., shared headers) check tail pre-order numbers.
2496 // Since I split shared headers, you'd think this could not happen.
2497 // BUT: I must first do the preorder numbering before I can discover I
2498 // have shared headers, so the split headers all get the same preorder
2499 // number as the RegionNode they split from.
2500 if( loop_preorder == l_preorder &&
2501 get_preorder(loop->_tail) < get_preorder(l->_tail) )
2502 break; // Also check for shared headers (same pre#)
2503 pp = &l->_parent; // Chain up list
2504 l = *pp;
2505 }
2506 // Link into list
2507 // Point predecessor to me
2508 *pp = loop;
2509 // Point me to successor
2510 IdealLoopTree *p = loop->_parent;
2511 loop->_parent = l; // Point me to successor
2512 if( p ) sort( p, innermost ); // Insert my parents into list as well
2513 return innermost;
2514 }
2515
2516 //------------------------------build_loop_tree--------------------------------
2517 // I use a modified Vick/Tarjan algorithm. I need pre- and a post- visit
2518 // bits. The _nodes[] array is mapped by Node index and holds a NULL for
2519 // not-yet-pre-walked, pre-order # for pre-but-not-post-walked and holds the
2520 // tightest enclosing IdealLoopTree for post-walked.
2521 //
2522 // During my forward walk I do a short 1-layer lookahead to see if I can find
2523 // a loop backedge with that doesn't have any work on the backedge. This
2524 // helps me construct nested loops with shared headers better.
2525 //
2526 // Once I've done the forward recursion, I do the post-work. For each child
2527 // I check to see if there is a backedge. Backedges define a loop! I
2528 // insert an IdealLoopTree at the target of the backedge.
2529 //
2530 // During the post-work I also check to see if I have several children
2531 // belonging to different loops. If so, then this Node is a decision point
2532 // where control flow can choose to change loop nests. It is at this
2533 // decision point where I can figure out how loops are nested. At this
2534 // time I can properly order the different loop nests from my children.
2535 // Note that there may not be any backedges at the decision point!
2536 //
2537 // Since the decision point can be far removed from the backedges, I can't
2538 // order my loops at the time I discover them. Thus at the decision point
2539 // I need to inspect loop header pre-order numbers to properly nest my
2540 // loops. This means I need to sort my childrens' loops by pre-order.
2541 // The sort is of size number-of-control-children, which generally limits
2542 // it to size 2 (i.e., I just choose between my 2 target loops).
2543 void PhaseIdealLoop::build_loop_tree() {
2544 // Allocate stack of size C->unique()/2 to avoid frequent realloc
2545 GrowableArray <Node *> bltstack(C->unique() >> 1);
2546 Node *n = C->root();
2547 bltstack.push(n);
2548 int pre_order = 1;
2549 int stack_size;
2550
2551 while ( ( stack_size = bltstack.length() ) != 0 ) {
2552 n = bltstack.top(); // Leave node on stack
2553 if ( !is_visited(n) ) {
2554 // ---- Pre-pass Work ----
2555 // Pre-walked but not post-walked nodes need a pre_order number.
2556
2557 set_preorder_visited( n, pre_order ); // set as visited
2558
2559 // ---- Scan over children ----
2560 // Scan first over control projections that lead to loop headers.
2561 // This helps us find inner-to-outer loops with shared headers better.
2562
2563 // Scan children's children for loop headers.
2564 for ( int i = n->outcnt() - 1; i >= 0; --i ) {
2565 Node* m = n->raw_out(i); // Child
2566 if( m->is_CFG() && !is_visited(m) ) { // Only for CFG children
2567 // Scan over children's children to find loop
2568 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
2569 Node* l = m->fast_out(j);
2570 if( is_visited(l) && // Been visited?
2571 !is_postvisited(l) && // But not post-visited
2572 get_preorder(l) < pre_order ) { // And smaller pre-order
2573 // Found! Scan the DFS down this path before doing other paths
2574 bltstack.push(m);
2575 break;
2576 }
2577 }
2578 }
2579 }
2580 pre_order++;
2581 }
2582 else if ( !is_postvisited(n) ) {
2583 // Note: build_loop_tree_impl() adds out edges on rare occasions,
2584 // such as com.sun.rsasign.am::a.
2585 // For non-recursive version, first, process current children.
2586 // On next iteration, check if additional children were added.
2587 for ( int k = n->outcnt() - 1; k >= 0; --k ) {
2588 Node* u = n->raw_out(k);
2589 if ( u->is_CFG() && !is_visited(u) ) {
2590 bltstack.push(u);
2591 }
2592 }
2593 if ( bltstack.length() == stack_size ) {
2594 // There were no additional children, post visit node now
2595 (void)bltstack.pop(); // Remove node from stack
2596 pre_order = build_loop_tree_impl( n, pre_order );
2597 // Check for bailout
2598 if (C->failing()) {
2599 return;
2600 }
2601 // Check to grow _preorders[] array for the case when
2602 // build_loop_tree_impl() adds new nodes.
2603 check_grow_preorders();
2604 }
2605 }
2606 else {
2607 (void)bltstack.pop(); // Remove post-visited node from stack
2608 }
2609 }
2610 }
2611
2612 //------------------------------build_loop_tree_impl---------------------------
2613 int PhaseIdealLoop::build_loop_tree_impl( Node *n, int pre_order ) {
2614 // ---- Post-pass Work ----
2615 // Pre-walked but not post-walked nodes need a pre_order number.
2616
2617 // Tightest enclosing loop for this Node
2618 IdealLoopTree *innermost = NULL;
2619
2620 // For all children, see if any edge is a backedge. If so, make a loop
2621 // for it. Then find the tightest enclosing loop for the self Node.
2622 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2623 Node* m = n->fast_out(i); // Child
2624 if( n == m ) continue; // Ignore control self-cycles
2625 if( !m->is_CFG() ) continue;// Ignore non-CFG edges
2626
2627 IdealLoopTree *l; // Child's loop
2628 if( !is_postvisited(m) ) { // Child visited but not post-visited?
2629 // Found a backedge
2630 assert( get_preorder(m) < pre_order, "should be backedge" );
2631 // Check for the RootNode, which is already a LoopNode and is allowed
2632 // to have multiple "backedges".
2633 if( m == C->root()) { // Found the root?
2634 l = _ltree_root; // Root is the outermost LoopNode
2635 } else { // Else found a nested loop
2636 // Insert a LoopNode to mark this loop.
2637 l = new IdealLoopTree(this, m, n);
2638 } // End of Else found a nested loop
2639 if( !has_loop(m) ) // If 'm' does not already have a loop set
2640 set_loop(m, l); // Set loop header to loop now
2641
2642 } else { // Else not a nested loop
2643 if( !_nodes[m->_idx] ) continue; // Dead code has no loop
2644 l = get_loop(m); // Get previously determined loop
2645 // If successor is header of a loop (nest), move up-loop till it
2646 // is a member of some outer enclosing loop. Since there are no
2647 // shared headers (I've split them already) I only need to go up
2648 // at most 1 level.
2649 while( l && l->_head == m ) // Successor heads loop?
2650 l = l->_parent; // Move up 1 for me
2651 // If this loop is not properly parented, then this loop
2652 // has no exit path out, i.e. its an infinite loop.
2653 if( !l ) {
2654 // Make loop "reachable" from root so the CFG is reachable. Basically
2655 // insert a bogus loop exit that is never taken. 'm', the loop head,
2656 // points to 'n', one (of possibly many) fall-in paths. There may be
2657 // many backedges as well.
2658
2659 // Here I set the loop to be the root loop. I could have, after
2660 // inserting a bogus loop exit, restarted the recursion and found my
2661 // new loop exit. This would make the infinite loop a first-class
2662 // loop and it would then get properly optimized. What's the use of
2663 // optimizing an infinite loop?
2664 l = _ltree_root; // Oops, found infinite loop
2665
2666 if (!_verify_only) {
2667 // Insert the NeverBranch between 'm' and it's control user.
2668 NeverBranchNode *iff = new (C, 1) NeverBranchNode( m );
2669 _igvn.register_new_node_with_optimizer(iff);
2670 set_loop(iff, l);
2671 Node *if_t = new (C, 1) CProjNode( iff, 0 );
2672 _igvn.register_new_node_with_optimizer(if_t);
2673 set_loop(if_t, l);
2674
2675 Node* cfg = NULL; // Find the One True Control User of m
2676 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
2677 Node* x = m->fast_out(j);
2678 if (x->is_CFG() && x != m && x != iff)
2679 { cfg = x; break; }
2680 }
2681 assert(cfg != NULL, "must find the control user of m");
2682 uint k = 0; // Probably cfg->in(0)
2683 while( cfg->in(k) != m ) k++; // But check incase cfg is a Region
2684 cfg->set_req( k, if_t ); // Now point to NeverBranch
2685
2686 // Now create the never-taken loop exit
2687 Node *if_f = new (C, 1) CProjNode( iff, 1 );
2688 _igvn.register_new_node_with_optimizer(if_f);
2689 set_loop(if_f, l);
2690 // Find frame ptr for Halt. Relies on the optimizer
2691 // V-N'ing. Easier and quicker than searching through
2692 // the program structure.
2693 Node *frame = new (C, 1) ParmNode( C->start(), TypeFunc::FramePtr );
2694 _igvn.register_new_node_with_optimizer(frame);
2695 // Halt & Catch Fire
2696 Node *halt = new (C, TypeFunc::Parms) HaltNode( if_f, frame );
2697 _igvn.register_new_node_with_optimizer(halt);
2698 set_loop(halt, l);
2699 C->root()->add_req(halt);
2700 }
2701 set_loop(C->root(), _ltree_root);
2702 }
2703 }
2704 // Weeny check for irreducible. This child was already visited (this
2705 // IS the post-work phase). Is this child's loop header post-visited
2706 // as well? If so, then I found another entry into the loop.
2707 if (!_verify_only) {
2708 while( is_postvisited(l->_head) ) {
2709 // found irreducible
2710 l->_irreducible = 1; // = true
2711 l = l->_parent;
2712 _has_irreducible_loops = true;
2713 // Check for bad CFG here to prevent crash, and bailout of compile
2714 if (l == NULL) {
2715 C->record_method_not_compilable("unhandled CFG detected during loop optimization");
2716 return pre_order;
2717 }
2718 }
2719 }
2720
2721 // This Node might be a decision point for loops. It is only if
2722 // it's children belong to several different loops. The sort call
2723 // does a trivial amount of work if there is only 1 child or all
2724 // children belong to the same loop. If however, the children
2725 // belong to different loops, the sort call will properly set the
2726 // _parent pointers to show how the loops nest.
2727 //
2728 // In any case, it returns the tightest enclosing loop.
2729 innermost = sort( l, innermost );
2730 }
2731
2732 // Def-use info will have some dead stuff; dead stuff will have no
2733 // loop decided on.
2734
2735 // Am I a loop header? If so fix up my parent's child and next ptrs.
2736 if( innermost && innermost->_head == n ) {
2737 assert( get_loop(n) == innermost, "" );
2738 IdealLoopTree *p = innermost->_parent;
2739 IdealLoopTree *l = innermost;
2740 while( p && l->_head == n ) {
2741 l->_next = p->_child; // Put self on parents 'next child'
2742 p->_child = l; // Make self as first child of parent
2743 l = p; // Now walk up the parent chain
2744 p = l->_parent;
2745 }
2746 } else {
2747 // Note that it is possible for a LoopNode to reach here, if the
2748 // backedge has been made unreachable (hence the LoopNode no longer
2749 // denotes a Loop, and will eventually be removed).
2750
2751 // Record tightest enclosing loop for self. Mark as post-visited.
2752 set_loop(n, innermost);
2753 // Also record has_call flag early on
2754 if( innermost ) {
2755 if( n->is_Call() && !n->is_CallLeaf() && !n->is_macro() ) {
2756 // Do not count uncommon calls
2757 if( !n->is_CallStaticJava() || !n->as_CallStaticJava()->_name ) {
2758 Node *iff = n->in(0)->in(0);
2759 // No any calls for vectorized loops.
2760 if( UseSuperWord || !iff->is_If() ||
2761 (n->in(0)->Opcode() == Op_IfFalse &&
2762 (1.0 - iff->as_If()->_prob) >= 0.01) ||
2763 (iff->as_If()->_prob >= 0.01) )
2764 innermost->_has_call = 1;
2765 }
2766 } else if( n->is_Allocate() && n->as_Allocate()->_is_scalar_replaceable ) {
2767 // Disable loop optimizations if the loop has a scalar replaceable
2768 // allocation. This disabling may cause a potential performance lost
2769 // if the allocation is not eliminated for some reason.
2770 innermost->_allow_optimizations = false;
2771 innermost->_has_call = 1; // = true
2772 }
2773 }
2774 }
2775
2776 // Flag as post-visited now
2777 set_postvisited(n);
2778 return pre_order;
2779 }
2780
2781
2782 //------------------------------build_loop_early-------------------------------
2783 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
2784 // First pass computes the earliest controlling node possible. This is the
2785 // controlling input with the deepest dominating depth.
2786 void PhaseIdealLoop::build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) {
2787 while (worklist.size() != 0) {
2788 // Use local variables nstack_top_n & nstack_top_i to cache values
2789 // on nstack's top.
2790 Node *nstack_top_n = worklist.pop();
2791 uint nstack_top_i = 0;
2792 //while_nstack_nonempty:
2793 while (true) {
2794 // Get parent node and next input's index from stack's top.
2795 Node *n = nstack_top_n;
2796 uint i = nstack_top_i;
2797 uint cnt = n->req(); // Count of inputs
2798 if (i == 0) { // Pre-process the node.
2799 if( has_node(n) && // Have either loop or control already?
2800 !has_ctrl(n) ) { // Have loop picked out already?
2801 // During "merge_many_backedges" we fold up several nested loops
2802 // into a single loop. This makes the members of the original
2803 // loop bodies pointing to dead loops; they need to move up
2804 // to the new UNION'd larger loop. I set the _head field of these
2805 // dead loops to NULL and the _parent field points to the owning
2806 // loop. Shades of UNION-FIND algorithm.
2807 IdealLoopTree *ilt;
2808 while( !(ilt = get_loop(n))->_head ) {
2809 // Normally I would use a set_loop here. But in this one special
2810 // case, it is legal (and expected) to change what loop a Node
2811 // belongs to.
2812 _nodes.map(n->_idx, (Node*)(ilt->_parent) );
2813 }
2814 // Remove safepoints ONLY if I've already seen I don't need one.
2815 // (the old code here would yank a 2nd safepoint after seeing a
2816 // first one, even though the 1st did not dominate in the loop body
2817 // and thus could be avoided indefinitely)
2818 if( !_verify_only && !_verify_me && ilt->_has_sfpt && n->Opcode() == Op_SafePoint &&
2819 is_deleteable_safept(n)) {
2820 Node *in = n->in(TypeFunc::Control);
2821 lazy_replace(n,in); // Pull safepoint now
2822 // Carry on with the recursion "as if" we are walking
2823 // only the control input
2824 if( !visited.test_set( in->_idx ) ) {
2825 worklist.push(in); // Visit this guy later, using worklist
2826 }
2827 // Get next node from nstack:
2828 // - skip n's inputs processing by setting i > cnt;
2829 // - we also will not call set_early_ctrl(n) since
2830 // has_node(n) == true (see the condition above).
2831 i = cnt + 1;
2832 }
2833 }
2834 } // if (i == 0)
2835
2836 // Visit all inputs
2837 bool done = true; // Assume all n's inputs will be processed
2838 while (i < cnt) {
2839 Node *in = n->in(i);
2840 ++i;
2841 if (in == NULL) continue;
2842 if (in->pinned() && !in->is_CFG())
2843 set_ctrl(in, in->in(0));
2844 int is_visited = visited.test_set( in->_idx );
2845 if (!has_node(in)) { // No controlling input yet?
2846 assert( !in->is_CFG(), "CFG Node with no controlling input?" );
2847 assert( !is_visited, "visit only once" );
2848 nstack.push(n, i); // Save parent node and next input's index.
2849 nstack_top_n = in; // Process current input now.
2850 nstack_top_i = 0;
2851 done = false; // Not all n's inputs processed.
2852 break; // continue while_nstack_nonempty;
2853 } else if (!is_visited) {
2854 // This guy has a location picked out for him, but has not yet
2855 // been visited. Happens to all CFG nodes, for instance.
2856 // Visit him using the worklist instead of recursion, to break
2857 // cycles. Since he has a location already we do not need to
2858 // find his location before proceeding with the current Node.
2859 worklist.push(in); // Visit this guy later, using worklist
2860 }
2861 }
2862 if (done) {
2863 // All of n's inputs have been processed, complete post-processing.
2864
2865 // Compute earliest point this Node can go.
2866 // CFG, Phi, pinned nodes already know their controlling input.
2867 if (!has_node(n)) {
2868 // Record earliest legal location
2869 set_early_ctrl( n );
2870 }
2871 if (nstack.is_empty()) {
2872 // Finished all nodes on stack.
2873 // Process next node on the worklist.
2874 break;
2875 }
2876 // Get saved parent node and next input's index.
2877 nstack_top_n = nstack.node();
2878 nstack_top_i = nstack.index();
2879 nstack.pop();
2880 }
2881 } // while (true)
2882 }
2883 }
2884
2885 //------------------------------dom_lca_internal--------------------------------
2886 // Pair-wise LCA
2887 Node *PhaseIdealLoop::dom_lca_internal( Node *n1, Node *n2 ) const {
2888 if( !n1 ) return n2; // Handle NULL original LCA
2889 assert( n1->is_CFG(), "" );
2890 assert( n2->is_CFG(), "" );
2891 // find LCA of all uses
2892 uint d1 = dom_depth(n1);
2893 uint d2 = dom_depth(n2);
2894 while (n1 != n2) {
2895 if (d1 > d2) {
2896 n1 = idom(n1);
2897 d1 = dom_depth(n1);
2898 } else if (d1 < d2) {
2899 n2 = idom(n2);
2900 d2 = dom_depth(n2);
2901 } else {
2902 // Here d1 == d2. Due to edits of the dominator-tree, sections
2903 // of the tree might have the same depth. These sections have
2904 // to be searched more carefully.
2905
2906 // Scan up all the n1's with equal depth, looking for n2.
2907 Node *t1 = idom(n1);
2908 while (dom_depth(t1) == d1) {
2909 if (t1 == n2) return n2;
2910 t1 = idom(t1);
2911 }
2912 // Scan up all the n2's with equal depth, looking for n1.
2913 Node *t2 = idom(n2);
2914 while (dom_depth(t2) == d2) {
2915 if (t2 == n1) return n1;
2916 t2 = idom(t2);
2917 }
2918 // Move up to a new dominator-depth value as well as up the dom-tree.
2919 n1 = t1;
2920 n2 = t2;
2921 d1 = dom_depth(n1);
2922 d2 = dom_depth(n2);
2923 }
2924 }
2925 return n1;
2926 }
2927
2928 //------------------------------compute_idom-----------------------------------
2929 // Locally compute IDOM using dom_lca call. Correct only if the incoming
2930 // IDOMs are correct.
2931 Node *PhaseIdealLoop::compute_idom( Node *region ) const {
2932 assert( region->is_Region(), "" );
2933 Node *LCA = NULL;
2934 for( uint i = 1; i < region->req(); i++ ) {
2935 if( region->in(i) != C->top() )
2936 LCA = dom_lca( LCA, region->in(i) );
2937 }
2938 return LCA;
2939 }
2940
2941 bool PhaseIdealLoop::verify_dominance(Node* n, Node* use, Node* LCA, Node* early) {
2942 bool had_error = false;
2943 #ifdef ASSERT
2944 if (early != C->root()) {
2945 // Make sure that there's a dominance path from use to LCA
2946 Node* d = use;
2947 while (d != LCA) {
2948 d = idom(d);
2949 if (d == C->root()) {
2950 tty->print_cr("*** Use %d isn't dominated by def %s", use->_idx, n->_idx);
2951 n->dump();
2952 use->dump();
2953 had_error = true;
2954 break;
2955 }
2956 }
2957 }
2958 #endif
2959 return had_error;
2960 }
2961
2962
2963 Node* PhaseIdealLoop::compute_lca_of_uses(Node* n, Node* early, bool verify) {
2964 // Compute LCA over list of uses
2965 bool had_error = false;
2966 Node *LCA = NULL;
2967 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax && LCA != early; i++) {
2968 Node* c = n->fast_out(i);
2969 if (_nodes[c->_idx] == NULL)
2970 continue; // Skip the occasional dead node
2971 if( c->is_Phi() ) { // For Phis, we must land above on the path
2972 for( uint j=1; j<c->req(); j++ ) {// For all inputs
2973 if( c->in(j) == n ) { // Found matching input?
2974 Node *use = c->in(0)->in(j);
2975 if (_verify_only && use->is_top()) continue;
2976 LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
2977 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error;
2978 }
2979 }
2980 } else {
2981 // For CFG data-users, use is in the block just prior
2982 Node *use = has_ctrl(c) ? get_ctrl(c) : c->in(0);
2983 LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
2984 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error;
2985 }
2986 }
2987 assert(!had_error, "bad dominance");
2988 return LCA;
2989 }
2990
2991 //------------------------------get_late_ctrl----------------------------------
2992 // Compute latest legal control.
2993 Node *PhaseIdealLoop::get_late_ctrl( Node *n, Node *early ) {
2994 assert(early != NULL, "early control should not be NULL");
2995
2996 Node* LCA = compute_lca_of_uses(n, early);
2997 #ifdef ASSERT
2998 if (LCA == C->root() && LCA != early) {
2999 // def doesn't dominate uses so print some useful debugging output
3000 compute_lca_of_uses(n, early, true);
3001 }
3002 #endif
3003
3004 // if this is a load, check for anti-dependent stores
3005 // We use a conservative algorithm to identify potential interfering
3006 // instructions and for rescheduling the load. The users of the memory
3007 // input of this load are examined. Any use which is not a load and is
3008 // dominated by early is considered a potentially interfering store.
3009 // This can produce false positives.
3010 if (n->is_Load() && LCA != early) {
3011 Node_List worklist;
3012
3013 Node *mem = n->in(MemNode::Memory);
3014 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
3015 Node* s = mem->fast_out(i);
3016 worklist.push(s);
3017 }
3018 while(worklist.size() != 0 && LCA != early) {
3019 Node* s = worklist.pop();
3020 if (s->is_Load()) {
3021 continue;
3022 } else if (s->is_MergeMem()) {
3023 for (DUIterator_Fast imax, i = s->fast_outs(imax); i < imax; i++) {
3024 Node* s1 = s->fast_out(i);
3025 worklist.push(s1);
3026 }
3027 } else {
3028 Node *sctrl = has_ctrl(s) ? get_ctrl(s) : s->in(0);
3029 assert(sctrl != NULL || s->outcnt() == 0, "must have control");
3030 if (sctrl != NULL && !sctrl->is_top() && is_dominator(early, sctrl)) {
3031 LCA = dom_lca_for_get_late_ctrl(LCA, sctrl, n);
3032 }
3033 }
3034 }
3035 }
3036
3037 assert(LCA == find_non_split_ctrl(LCA), "unexpected late control");
3038 return LCA;
3039 }
3040
3041 // true if CFG node d dominates CFG node n
3042 bool PhaseIdealLoop::is_dominator(Node *d, Node *n) {
3043 if (d == n)
3044 return true;
3045 assert(d->is_CFG() && n->is_CFG(), "must have CFG nodes");
3046 uint dd = dom_depth(d);
3047 while (dom_depth(n) >= dd) {
3048 if (n == d)
3049 return true;
3050 n = idom(n);
3051 }
3052 return false;
3053 }
3054
3055 //------------------------------dom_lca_for_get_late_ctrl_internal-------------
3056 // Pair-wise LCA with tags.
3057 // Tag each index with the node 'tag' currently being processed
3058 // before advancing up the dominator chain using idom().
3059 // Later calls that find a match to 'tag' know that this path has already
3060 // been considered in the current LCA (which is input 'n1' by convention).
3061 // Since get_late_ctrl() is only called once for each node, the tag array
3062 // does not need to be cleared between calls to get_late_ctrl().
3063 // Algorithm trades a larger constant factor for better asymptotic behavior
3064 //
3065 Node *PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal( Node *n1, Node *n2, Node *tag ) {
3066 uint d1 = dom_depth(n1);
3067 uint d2 = dom_depth(n2);
3068
3069 do {
3070 if (d1 > d2) {
3071 // current lca is deeper than n2
3072 _dom_lca_tags.map(n1->_idx, tag);
3073 n1 = idom(n1);
3074 d1 = dom_depth(n1);
3075 } else if (d1 < d2) {
3076 // n2 is deeper than current lca
3077 Node *memo = _dom_lca_tags[n2->_idx];
3078 if( memo == tag ) {
3079 return n1; // Return the current LCA
3080 }
3081 _dom_lca_tags.map(n2->_idx, tag);
3082 n2 = idom(n2);
3083 d2 = dom_depth(n2);
3084 } else {
3085 // Here d1 == d2. Due to edits of the dominator-tree, sections
3086 // of the tree might have the same depth. These sections have
3087 // to be searched more carefully.
3088
3089 // Scan up all the n1's with equal depth, looking for n2.
3090 _dom_lca_tags.map(n1->_idx, tag);
3091 Node *t1 = idom(n1);
3092 while (dom_depth(t1) == d1) {
3093 if (t1 == n2) return n2;
3094 _dom_lca_tags.map(t1->_idx, tag);
3095 t1 = idom(t1);
3096 }
3097 // Scan up all the n2's with equal depth, looking for n1.
3098 _dom_lca_tags.map(n2->_idx, tag);
3099 Node *t2 = idom(n2);
3100 while (dom_depth(t2) == d2) {
3101 if (t2 == n1) return n1;
3102 _dom_lca_tags.map(t2->_idx, tag);
3103 t2 = idom(t2);
3104 }
3105 // Move up to a new dominator-depth value as well as up the dom-tree.
3106 n1 = t1;
3107 n2 = t2;
3108 d1 = dom_depth(n1);
3109 d2 = dom_depth(n2);
3110 }
3111 } while (n1 != n2);
3112 return n1;
3113 }
3114
3115 //------------------------------init_dom_lca_tags------------------------------
3116 // Tag could be a node's integer index, 32bits instead of 64bits in some cases
3117 // Intended use does not involve any growth for the array, so it could
3118 // be of fixed size.
3119 void PhaseIdealLoop::init_dom_lca_tags() {
3120 uint limit = C->unique() + 1;
3121 _dom_lca_tags.map( limit, NULL );
3122 #ifdef ASSERT
3123 for( uint i = 0; i < limit; ++i ) {
3124 assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer");
3125 }
3126 #endif // ASSERT
3127 }
3128
3129 //------------------------------clear_dom_lca_tags------------------------------
3130 // Tag could be a node's integer index, 32bits instead of 64bits in some cases
3131 // Intended use does not involve any growth for the array, so it could
3132 // be of fixed size.
3133 void PhaseIdealLoop::clear_dom_lca_tags() {
3134 uint limit = C->unique() + 1;
3135 _dom_lca_tags.map( limit, NULL );
3136 _dom_lca_tags.clear();
3137 #ifdef ASSERT
3138 for( uint i = 0; i < limit; ++i ) {
3139 assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer");
3140 }
3141 #endif // ASSERT
3142 }
3143
3144 //------------------------------build_loop_late--------------------------------
3145 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
3146 // Second pass finds latest legal placement, and ideal loop placement.
3147 void PhaseIdealLoop::build_loop_late( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) {
3148 while (worklist.size() != 0) {
3149 Node *n = worklist.pop();
3150 // Only visit once
3151 if (visited.test_set(n->_idx)) continue;
3152 uint cnt = n->outcnt();
3153 uint i = 0;
3154 while (true) {
3155 assert( _nodes[n->_idx], "no dead nodes" );
3156 // Visit all children
3157 if (i < cnt) {
3158 Node* use = n->raw_out(i);
3159 ++i;
3160 // Check for dead uses. Aggressively prune such junk. It might be
3161 // dead in the global sense, but still have local uses so I cannot
3162 // easily call 'remove_dead_node'.
3163 if( _nodes[use->_idx] != NULL || use->is_top() ) { // Not dead?
3164 // Due to cycles, we might not hit the same fixed point in the verify
3165 // pass as we do in the regular pass. Instead, visit such phis as
3166 // simple uses of the loop head.
3167 if( use->in(0) && (use->is_CFG() || use->is_Phi()) ) {
3168 if( !visited.test(use->_idx) )
3169 worklist.push(use);
3170 } else if( !visited.test_set(use->_idx) ) {
3171 nstack.push(n, i); // Save parent and next use's index.
3172 n = use; // Process all children of current use.
3173 cnt = use->outcnt();
3174 i = 0;
3175 }
3176 } else {
3177 // Do not visit around the backedge of loops via data edges.
3178 // push dead code onto a worklist
3179 _deadlist.push(use);
3180 }
3181 } else {
3182 // All of n's children have been processed, complete post-processing.
3183 build_loop_late_post(n);
3184 if (nstack.is_empty()) {
3185 // Finished all nodes on stack.
3186 // Process next node on the worklist.
3187 break;
3188 }
3189 // Get saved parent node and next use's index. Visit the rest of uses.
3190 n = nstack.node();
3191 cnt = n->outcnt();
3192 i = nstack.index();
3193 nstack.pop();
3194 }
3195 }
3196 }
3197 }
3198
3199 //------------------------------build_loop_late_post---------------------------
3200 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
3201 // Second pass finds latest legal placement, and ideal loop placement.
3202 void PhaseIdealLoop::build_loop_late_post( Node *n ) {
3203
3204 if (n->req() == 2 && n->Opcode() == Op_ConvI2L && !C->major_progress() && !_verify_only) {
3205 _igvn._worklist.push(n); // Maybe we'll normalize it, if no more loops.
3206 }
3207
3208 // CFG and pinned nodes already handled
3209 if( n->in(0) ) {
3210 if( n->in(0)->is_top() ) return; // Dead?
3211
3212 // We'd like +VerifyLoopOptimizations to not believe that Mod's/Loads
3213 // _must_ be pinned (they have to observe their control edge of course).
3214 // Unlike Stores (which modify an unallocable resource, the memory
3215 // state), Mods/Loads can float around. So free them up.
3216 bool pinned = true;
3217 switch( n->Opcode() ) {
3218 case Op_DivI:
3219 case Op_DivF:
3220 case Op_DivD:
3221 case Op_ModI:
3222 case Op_ModF:
3223 case Op_ModD:
3224 case Op_LoadB: // Same with Loads; they can sink
3225 case Op_LoadUS: // during loop optimizations.
3226 case Op_LoadD:
3227 case Op_LoadF:
3228 case Op_LoadI:
3229 case Op_LoadKlass:
3230 case Op_LoadNKlass:
3231 case Op_LoadL:
3232 case Op_LoadS:
3233 case Op_LoadP:
3234 case Op_LoadN:
3235 case Op_LoadRange:
3236 case Op_LoadD_unaligned:
3237 case Op_LoadL_unaligned:
3238 case Op_StrComp: // Does a bunch of load-like effects
3239 case Op_StrEquals:
3240 case Op_StrIndexOf:
3241 case Op_AryEq:
3242 pinned = false;
3243 }
3244 if( pinned ) {
3245 IdealLoopTree *chosen_loop = get_loop(n->is_CFG() ? n : get_ctrl(n));
3246 if( !chosen_loop->_child ) // Inner loop?
3247 chosen_loop->_body.push(n); // Collect inner loops
3248 return;
3249 }
3250 } else { // No slot zero
3251 if( n->is_CFG() ) { // CFG with no slot 0 is dead
3252 _nodes.map(n->_idx,0); // No block setting, it's globally dead
3253 return;
3254 }
3255 assert(!n->is_CFG() || n->outcnt() == 0, "");
3256 }
3257
3258 // Do I have a "safe range" I can select over?
3259 Node *early = get_ctrl(n);// Early location already computed
3260
3261 // Compute latest point this Node can go
3262 Node *LCA = get_late_ctrl( n, early );
3263 // LCA is NULL due to uses being dead
3264 if( LCA == NULL ) {
3265 #ifdef ASSERT
3266 for (DUIterator i1 = n->outs(); n->has_out(i1); i1++) {
3267 assert( _nodes[n->out(i1)->_idx] == NULL, "all uses must also be dead");
3268 }
3269 #endif
3270 _nodes.map(n->_idx, 0); // This node is useless
3271 _deadlist.push(n);
3272 return;
3273 }
3274 assert(LCA != NULL && !LCA->is_top(), "no dead nodes");
3275
3276 Node *legal = LCA; // Walk 'legal' up the IDOM chain
3277 Node *least = legal; // Best legal position so far
3278 while( early != legal ) { // While not at earliest legal
3279 #ifdef ASSERT
3280 if (legal->is_Start() && !early->is_Root()) {
3281 // Bad graph. Print idom path and fail.
3282 dump_bad_graph(n, early, LCA);
3283 assert(false, "Bad graph detected in build_loop_late");
3284 }
3285 #endif
3286 // Find least loop nesting depth
3287 legal = idom(legal); // Bump up the IDOM tree
3288 // Check for lower nesting depth
3289 if( get_loop(legal)->_nest < get_loop(least)->_nest )
3290 least = legal;
3291 }
3292 assert(early == legal || legal != C->root(), "bad dominance of inputs");
3293
3294 // Try not to place code on a loop entry projection
3295 // which can inhibit range check elimination.
3296 if (least != early) {
3297 Node* ctrl_out = least->unique_ctrl_out();
3298 if (ctrl_out && ctrl_out->is_CountedLoop() &&
3299 least == ctrl_out->in(LoopNode::EntryControl)) {
3300 Node* least_dom = idom(least);
3301 if (get_loop(least_dom)->is_member(get_loop(least))) {
3302 least = least_dom;
3303 }
3304 }
3305 }
3306
3307 #ifdef ASSERT
3308 // If verifying, verify that 'verify_me' has a legal location
3309 // and choose it as our location.
3310 if( _verify_me ) {
3311 Node *v_ctrl = _verify_me->get_ctrl_no_update(n);
3312 Node *legal = LCA;
3313 while( early != legal ) { // While not at earliest legal
3314 if( legal == v_ctrl ) break; // Check for prior good location
3315 legal = idom(legal) ;// Bump up the IDOM tree
3316 }
3317 // Check for prior good location
3318 if( legal == v_ctrl ) least = legal; // Keep prior if found
3319 }
3320 #endif
3321
3322 // Assign discovered "here or above" point
3323 least = find_non_split_ctrl(least);
3324 set_ctrl(n, least);
3325
3326 // Collect inner loop bodies
3327 IdealLoopTree *chosen_loop = get_loop(least);
3328 if( !chosen_loop->_child ) // Inner loop?
3329 chosen_loop->_body.push(n);// Collect inner loops
3330 }
3331
3332 #ifdef ASSERT
3333 void PhaseIdealLoop::dump_bad_graph(Node* n, Node* early, Node* LCA) {
3334 tty->print_cr( "Bad graph detected in build_loop_late");
3335 tty->print("n: "); n->dump();
3336 tty->print("early(n): "); early->dump();
3337 if (n->in(0) != NULL && !n->in(0)->is_top() &&
3338 n->in(0) != early && !n->in(0)->is_Root()) {
3339 tty->print("n->in(0): "); n->in(0)->dump();
3340 }
3341 for (uint i = 1; i < n->req(); i++) {
3342 Node* in1 = n->in(i);
3343 if (in1 != NULL && in1 != n && !in1->is_top()) {
3344 tty->print("n->in(%d): ", i); in1->dump();
3345 Node* in1_early = get_ctrl(in1);
3346 tty->print("early(n->in(%d)): ", i); in1_early->dump();
3347 if (in1->in(0) != NULL && !in1->in(0)->is_top() &&
3348 in1->in(0) != in1_early && !in1->in(0)->is_Root()) {
3349 tty->print("n->in(%d)->in(0): ", i); in1->in(0)->dump();
3350 }
3351 for (uint j = 1; j < in1->req(); j++) {
3352 Node* in2 = in1->in(j);
3353 if (in2 != NULL && in2 != n && in2 != in1 && !in2->is_top()) {
3354 tty->print("n->in(%d)->in(%d): ", i, j); in2->dump();
3355 Node* in2_early = get_ctrl(in2);
3356 tty->print("early(n->in(%d)->in(%d)): ", i, j); in2_early->dump();
3357 if (in2->in(0) != NULL && !in2->in(0)->is_top() &&
3358 in2->in(0) != in2_early && !in2->in(0)->is_Root()) {
3359 tty->print("n->in(%d)->in(%d)->in(0): ", i, j); in2->in(0)->dump();
3360 }
3361 }
3362 }
3363 }
3364 }
3365 tty->cr();
3366 tty->print("LCA(n): "); LCA->dump();
3367 for (uint i = 0; i < n->outcnt(); i++) {
3368 Node* u1 = n->raw_out(i);
3369 if (u1 == n)
3370 continue;
3371 tty->print("n->out(%d): ", i); u1->dump();
3372 if (u1->is_CFG()) {
3373 for (uint j = 0; j < u1->outcnt(); j++) {
3374 Node* u2 = u1->raw_out(j);
3375 if (u2 != u1 && u2 != n && u2->is_CFG()) {
3376 tty->print("n->out(%d)->out(%d): ", i, j); u2->dump();
3377 }
3378 }
3379 } else {
3380 Node* u1_later = get_ctrl(u1);
3381 tty->print("later(n->out(%d)): ", i); u1_later->dump();
3382 if (u1->in(0) != NULL && !u1->in(0)->is_top() &&
3383 u1->in(0) != u1_later && !u1->in(0)->is_Root()) {
3384 tty->print("n->out(%d)->in(0): ", i); u1->in(0)->dump();
3385 }
3386 for (uint j = 0; j < u1->outcnt(); j++) {
3387 Node* u2 = u1->raw_out(j);
3388 if (u2 == n || u2 == u1)
3389 continue;
3390 tty->print("n->out(%d)->out(%d): ", i, j); u2->dump();
3391 if (!u2->is_CFG()) {
3392 Node* u2_later = get_ctrl(u2);
3393 tty->print("later(n->out(%d)->out(%d)): ", i, j); u2_later->dump();
3394 if (u2->in(0) != NULL && !u2->in(0)->is_top() &&
3395 u2->in(0) != u2_later && !u2->in(0)->is_Root()) {
3396 tty->print("n->out(%d)->in(0): ", i); u2->in(0)->dump();
3397 }
3398 }
3399 }
3400 }
3401 }
3402 tty->cr();
3403 int ct = 0;
3404 Node *dbg_legal = LCA;
3405 while(!dbg_legal->is_Start() && ct < 100) {
3406 tty->print("idom[%d] ",ct); dbg_legal->dump();
3407 ct++;
3408 dbg_legal = idom(dbg_legal);
3409 }
3410 tty->cr();
3411 }
3412 #endif
3413
3414 #ifndef PRODUCT
3415 //------------------------------dump-------------------------------------------
3416 void PhaseIdealLoop::dump( ) const {
3417 ResourceMark rm;
3418 Arena* arena = Thread::current()->resource_area();
3419 Node_Stack stack(arena, C->unique() >> 2);
3420 Node_List rpo_list;
3421 VectorSet visited(arena);
3422 visited.set(C->top()->_idx);
3423 rpo( C->root(), stack, visited, rpo_list );
3424 // Dump root loop indexed by last element in PO order
3425 dump( _ltree_root, rpo_list.size(), rpo_list );
3426 }
3427
3428 void PhaseIdealLoop::dump( IdealLoopTree *loop, uint idx, Node_List &rpo_list ) const {
3429 loop->dump_head();
3430
3431 // Now scan for CFG nodes in the same loop
3432 for( uint j=idx; j > 0; j-- ) {
3433 Node *n = rpo_list[j-1];
3434 if( !_nodes[n->_idx] ) // Skip dead nodes
3435 continue;
3436 if( get_loop(n) != loop ) { // Wrong loop nest
3437 if( get_loop(n)->_head == n && // Found nested loop?
3438 get_loop(n)->_parent == loop )
3439 dump(get_loop(n),rpo_list.size(),rpo_list); // Print it nested-ly
3440 continue;
3441 }
3442
3443 // Dump controlling node
3444 for( uint x = 0; x < loop->_nest; x++ )
3445 tty->print(" ");
3446 tty->print("C");
3447 if( n == C->root() ) {
3448 n->dump();
3449 } else {
3450 Node* cached_idom = idom_no_update(n);
3451 Node *computed_idom = n->in(0);
3452 if( n->is_Region() ) {
3453 computed_idom = compute_idom(n);
3454 // computed_idom() will return n->in(0) when idom(n) is an IfNode (or
3455 // any MultiBranch ctrl node), so apply a similar transform to
3456 // the cached idom returned from idom_no_update.
3457 cached_idom = find_non_split_ctrl(cached_idom);
3458 }
3459 tty->print(" ID:%d",computed_idom->_idx);
3460 n->dump();
3461 if( cached_idom != computed_idom ) {
3462 tty->print_cr("*** BROKEN IDOM! Computed as: %d, cached as: %d",
3463 computed_idom->_idx, cached_idom->_idx);
3464 }
3465 }
3466 // Dump nodes it controls
3467 for( uint k = 0; k < _nodes.Size(); k++ ) {
3468 // (k < C->unique() && get_ctrl(find(k)) == n)
3469 if (k < C->unique() && _nodes[k] == (Node*)((intptr_t)n + 1)) {
3470 Node *m = C->root()->find(k);
3471 if( m && m->outcnt() > 0 ) {
3472 if (!(has_ctrl(m) && get_ctrl_no_update(m) == n)) {
3473 tty->print_cr("*** BROKEN CTRL ACCESSOR! _nodes[k] is %p, ctrl is %p",
3474 _nodes[k], has_ctrl(m) ? get_ctrl_no_update(m) : NULL);
3475 }
3476 for( uint j = 0; j < loop->_nest; j++ )
3477 tty->print(" ");
3478 tty->print(" ");
3479 m->dump();
3480 }
3481 }
3482 }
3483 }
3484 }
3485
3486 // Collect a R-P-O for the whole CFG.
3487 // Result list is in post-order (scan backwards for RPO)
3488 void PhaseIdealLoop::rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const {
3489 stk.push(start, 0);
3490 visited.set(start->_idx);
3491
3492 while (stk.is_nonempty()) {
3493 Node* m = stk.node();
3494 uint idx = stk.index();
3495 if (idx < m->outcnt()) {
3496 stk.set_index(idx + 1);
3497 Node* n = m->raw_out(idx);
3498 if (n->is_CFG() && !visited.test_set(n->_idx)) {
3499 stk.push(n, 0);
3500 }
3501 } else {
3502 rpo_list.push(m);
3503 stk.pop();
3504 }
3505 }
3506 }
3507 #endif
3508
3509
3510 //=============================================================================
3511 //------------------------------LoopTreeIterator-----------------------------------
3512
3513 // Advance to next loop tree using a preorder, left-to-right traversal.
3514 void LoopTreeIterator::next() {
3515 assert(!done(), "must not be done.");
3516 if (_curnt->_child != NULL) {
3517 _curnt = _curnt->_child;
3518 } else if (_curnt->_next != NULL) {
3519 _curnt = _curnt->_next;
3520 } else {
3521 while (_curnt != _root && _curnt->_next == NULL) {
3522 _curnt = _curnt->_parent;
3523 }
3524 if (_curnt == _root) {
3525 _curnt = NULL;
3526 assert(done(), "must be done.");
3527 } else {
3528 assert(_curnt->_next != NULL, "must be more to do");
3529 _curnt = _curnt->_next;
3530 }
3531 }
3532 }