1 /*
2 * Copyright (c) 1998, 2013, 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) && !n->is_expensive()) {
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 if (n->is_expensive()) {
136 assert(n->in(0), "should have control input");
137 early = get_early_ctrl_for_expensive(n, early);
138 }
139
140 return early;
141 }
142
143 //------------------------------get_early_ctrl_for_expensive---------------------------------
144 // Move node up the dominator tree as high as legal while still beneficial
145 Node *PhaseIdealLoop::get_early_ctrl_for_expensive(Node *n, Node* earliest) {
146 assert(n->in(0) && n->is_expensive(), "expensive node with control input here");
147 assert(OptimizeExpensiveOps, "optimization off?");
148
149 Node* ctl = n->in(0);
150 assert(ctl->is_CFG(), "expensive input 0 must be cfg");
151 uint min_dom_depth = dom_depth(earliest);
152 #ifdef ASSERT
153 if (!is_dominator(ctl, earliest) && !is_dominator(earliest, ctl)) {
154 dump_bad_graph("Bad graph detected in get_early_ctrl_for_expensive", n, earliest, ctl);
155 assert(false, "Bad graph detected in get_early_ctrl_for_expensive");
156 }
157 #endif
158 if (dom_depth(ctl) < min_dom_depth) {
159 return earliest;
160 }
161
162 while (1) {
163 Node *next = ctl;
164 // Moving the node out of a loop on the projection of a If
165 // confuses loop predication. So once we hit a Loop in a If branch
166 // that doesn't branch to an UNC, we stop. The code that process
167 // expensive nodes will notice the loop and skip over it to try to
168 // move the node further up.
169 if (ctl->is_CountedLoop() && ctl->in(1) != NULL && ctl->in(1)->in(0) != NULL && ctl->in(1)->in(0)->is_If()) {
170 if (!ctl->in(1)->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) {
171 break;
172 }
173 next = idom(ctl->in(1)->in(0));
174 } else if (ctl->is_Proj()) {
175 // We only move it up along a projection if the projection is
176 // the single control projection for its parent: same code path,
177 // if it's a If with UNC or fallthrough of a call.
178 Node* parent_ctl = ctl->in(0);
179 if (parent_ctl == NULL) {
180 break;
181 } else if (parent_ctl->is_CountedLoopEnd() && parent_ctl->as_CountedLoopEnd()->loopnode() != NULL) {
182 next = parent_ctl->as_CountedLoopEnd()->loopnode()->init_control();
183 } else if (parent_ctl->is_If()) {
184 if (!ctl->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) {
185 break;
186 }
187 assert(idom(ctl) == parent_ctl, "strange");
188 next = idom(parent_ctl);
189 } else if (ctl->is_CatchProj()) {
190 if (ctl->as_Proj()->_con != CatchProjNode::fall_through_index) {
191 break;
192 }
193 assert(parent_ctl->in(0)->in(0)->is_Call(), "strange graph");
194 next = parent_ctl->in(0)->in(0)->in(0);
195 } else {
196 // Check if parent control has a single projection (this
197 // control is the only possible successor of the parent
198 // control). If so, we can try to move the node above the
199 // parent control.
200 int nb_ctl_proj = 0;
201 for (DUIterator_Fast imax, i = parent_ctl->fast_outs(imax); i < imax; i++) {
202 Node *p = parent_ctl->fast_out(i);
203 if (p->is_Proj() && p->is_CFG()) {
204 nb_ctl_proj++;
205 if (nb_ctl_proj > 1) {
206 break;
207 }
208 }
209 }
210
211 if (nb_ctl_proj > 1) {
212 break;
213 }
214 assert(parent_ctl->is_Start() || parent_ctl->is_MemBar() || parent_ctl->is_Call(), "unexpected node");
215 assert(idom(ctl) == parent_ctl, "strange");
216 next = idom(parent_ctl);
217 }
218 } else {
219 next = idom(ctl);
220 }
221 if (next->is_Root() || next->is_Start() || dom_depth(next) < min_dom_depth) {
222 break;
223 }
224 ctl = next;
225 }
226
227 if (ctl != n->in(0)) {
228 _igvn.hash_delete(n);
229 n->set_req(0, ctl);
230 _igvn.hash_insert(n);
231 }
232
233 return ctl;
234 }
235
236
237 //------------------------------set_early_ctrl---------------------------------
238 // Set earliest legal control
239 void PhaseIdealLoop::set_early_ctrl( Node *n ) {
240 Node *early = get_early_ctrl(n);
241
242 // Record earliest legal location
243 set_ctrl(n, early);
244 }
245
246 //------------------------------set_subtree_ctrl-------------------------------
247 // set missing _ctrl entries on new nodes
248 void PhaseIdealLoop::set_subtree_ctrl( Node *n ) {
249 // Already set? Get out.
250 if( _nodes[n->_idx] ) return;
251 // Recursively set _nodes array to indicate where the Node goes
252 uint i;
253 for( i = 0; i < n->req(); ++i ) {
254 Node *m = n->in(i);
255 if( m && m != C->root() )
256 set_subtree_ctrl( m );
257 }
258
259 // Fixup self
260 set_early_ctrl( n );
261 }
262
263 //------------------------------is_counted_loop--------------------------------
264 bool PhaseIdealLoop::is_counted_loop( Node *x, IdealLoopTree *loop ) {
265 PhaseGVN *gvn = &_igvn;
266
267 // Counted loop head must be a good RegionNode with only 3 not NULL
268 // control input edges: Self, Entry, LoopBack.
269 if (x->in(LoopNode::Self) == NULL || x->req() != 3)
270 return false;
271
272 Node *init_control = x->in(LoopNode::EntryControl);
273 Node *back_control = x->in(LoopNode::LoopBackControl);
274 if (init_control == NULL || back_control == NULL) // Partially dead
275 return false;
276 // Must also check for TOP when looking for a dead loop
277 if (init_control->is_top() || back_control->is_top())
278 return false;
279
280 // Allow funny placement of Safepoint
281 if (back_control->Opcode() == Op_SafePoint)
282 back_control = back_control->in(TypeFunc::Control);
283
284 // Controlling test for loop
285 Node *iftrue = back_control;
286 uint iftrue_op = iftrue->Opcode();
287 if (iftrue_op != Op_IfTrue &&
288 iftrue_op != Op_IfFalse)
289 // I have a weird back-control. Probably the loop-exit test is in
290 // the middle of the loop and I am looking at some trailing control-flow
291 // merge point. To fix this I would have to partially peel the loop.
292 return false; // Obscure back-control
293
294 // Get boolean guarding loop-back test
295 Node *iff = iftrue->in(0);
296 if (get_loop(iff) != loop || !iff->in(1)->is_Bool())
297 return false;
298 BoolNode *test = iff->in(1)->as_Bool();
299 BoolTest::mask bt = test->_test._test;
300 float cl_prob = iff->as_If()->_prob;
301 if (iftrue_op == Op_IfFalse) {
302 bt = BoolTest(bt).negate();
303 cl_prob = 1.0 - cl_prob;
304 }
305 // Get backedge compare
306 Node *cmp = test->in(1);
307 int cmp_op = cmp->Opcode();
308 if (cmp_op != Op_CmpI)
309 return false; // Avoid pointer & float compares
310
311 // Find the trip-counter increment & limit. Limit must be loop invariant.
312 Node *incr = cmp->in(1);
313 Node *limit = cmp->in(2);
314
315 // ---------
316 // need 'loop()' test to tell if limit is loop invariant
317 // ---------
318
319 if (!is_member(loop, get_ctrl(incr))) { // Swapped trip counter and limit?
320 Node *tmp = incr; // Then reverse order into the CmpI
321 incr = limit;
322 limit = tmp;
323 bt = BoolTest(bt).commute(); // And commute the exit test
324 }
325 if (is_member(loop, get_ctrl(limit))) // Limit must be loop-invariant
326 return false;
327 if (!is_member(loop, get_ctrl(incr))) // Trip counter must be loop-variant
328 return false;
329
330 Node* phi_incr = NULL;
331 // Trip-counter increment must be commutative & associative.
332 if (incr->is_Phi()) {
333 if (incr->as_Phi()->region() != x || incr->req() != 3)
334 return false; // Not simple trip counter expression
335 phi_incr = incr;
336 incr = phi_incr->in(LoopNode::LoopBackControl); // Assume incr is on backedge of Phi
337 if (!is_member(loop, get_ctrl(incr))) // Trip counter must be loop-variant
338 return false;
339 }
340
341 Node* trunc1 = NULL;
342 Node* trunc2 = NULL;
343 const TypeInt* iv_trunc_t = NULL;
344 if (!(incr = CountedLoopNode::match_incr_with_optional_truncation(incr, &trunc1, &trunc2, &iv_trunc_t))) {
345 return false; // Funny increment opcode
346 }
347 assert(incr->Opcode() == Op_AddI, "wrong increment code");
348
349 // Get merge point
350 Node *xphi = incr->in(1);
351 Node *stride = incr->in(2);
352 if (!stride->is_Con()) { // Oops, swap these
353 if (!xphi->is_Con()) // Is the other guy a constant?
354 return false; // Nope, unknown stride, bail out
355 Node *tmp = xphi; // 'incr' is commutative, so ok to swap
356 xphi = stride;
357 stride = tmp;
358 }
359 // Stride must be constant
360 int stride_con = stride->get_int();
361 if (stride_con == 0)
362 return false; // missed some peephole opt
363
364 if (!xphi->is_Phi())
365 return false; // Too much math on the trip counter
366 if (phi_incr != NULL && phi_incr != xphi)
367 return false;
368 PhiNode *phi = xphi->as_Phi();
369
370 // Phi must be of loop header; backedge must wrap to increment
371 if (phi->region() != x)
372 return false;
373 if (trunc1 == NULL && phi->in(LoopNode::LoopBackControl) != incr ||
374 trunc1 != NULL && phi->in(LoopNode::LoopBackControl) != trunc1) {
375 return false;
376 }
377 Node *init_trip = phi->in(LoopNode::EntryControl);
378
379 // If iv trunc type is smaller than int, check for possible wrap.
380 if (!TypeInt::INT->higher_equal(iv_trunc_t)) {
381 assert(trunc1 != NULL, "must have found some truncation");
382
383 // Get a better type for the phi (filtered thru if's)
384 const TypeInt* phi_ft = filtered_type(phi);
385
386 // Can iv take on a value that will wrap?
387 //
388 // Ensure iv's limit is not within "stride" of the wrap value.
389 //
390 // Example for "short" type
391 // Truncation ensures value is in the range -32768..32767 (iv_trunc_t)
392 // If the stride is +10, then the last value of the induction
393 // variable before the increment (phi_ft->_hi) must be
394 // <= 32767 - 10 and (phi_ft->_lo) must be >= -32768 to
395 // ensure no truncation occurs after the increment.
396
397 if (stride_con > 0) {
398 if (iv_trunc_t->_hi - phi_ft->_hi < stride_con ||
399 iv_trunc_t->_lo > phi_ft->_lo) {
400 return false; // truncation may occur
401 }
402 } else if (stride_con < 0) {
403 if (iv_trunc_t->_lo - phi_ft->_lo > stride_con ||
404 iv_trunc_t->_hi < phi_ft->_hi) {
405 return false; // truncation may occur
406 }
407 }
408 // No possibility of wrap so truncation can be discarded
409 // Promote iv type to Int
410 } else {
411 assert(trunc1 == NULL && trunc2 == NULL, "no truncation for int");
412 }
413
414 // If the condition is inverted and we will be rolling
415 // through MININT to MAXINT, then bail out.
416 if (bt == BoolTest::eq || // Bail out, but this loop trips at most twice!
417 // Odd stride
418 bt == BoolTest::ne && stride_con != 1 && stride_con != -1 ||
419 // Count down loop rolls through MAXINT
420 (bt == BoolTest::le || bt == BoolTest::lt) && stride_con < 0 ||
421 // Count up loop rolls through MININT
422 (bt == BoolTest::ge || bt == BoolTest::gt) && stride_con > 0) {
423 return false; // Bail out
424 }
425
426 const TypeInt* init_t = gvn->type(init_trip)->is_int();
427 const TypeInt* limit_t = gvn->type(limit)->is_int();
428
429 if (stride_con > 0) {
430 jlong init_p = (jlong)init_t->_lo + stride_con;
431 if (init_p > (jlong)max_jint || init_p > (jlong)limit_t->_hi)
432 return false; // cyclic loop or this loop trips only once
433 } else {
434 jlong init_p = (jlong)init_t->_hi + stride_con;
435 if (init_p < (jlong)min_jint || init_p < (jlong)limit_t->_lo)
436 return false; // cyclic loop or this loop trips only once
437 }
438
439 // =================================================
440 // ---- SUCCESS! Found A Trip-Counted Loop! -----
441 //
442 assert(x->Opcode() == Op_Loop, "regular loops only");
443 C->print_method(PHASE_BEFORE_CLOOPS, 3);
444
445 Node *hook = new (C) Node(6);
446
447 if (LoopLimitCheck) {
448
449 // ===================================================
450 // Generate loop limit check to avoid integer overflow
451 // in cases like next (cyclic loops):
452 //
453 // for (i=0; i <= max_jint; i++) {}
454 // for (i=0; i < max_jint; i+=2) {}
455 //
456 //
457 // Limit check predicate depends on the loop test:
458 //
459 // for(;i != limit; i++) --> limit <= (max_jint)
460 // for(;i < limit; i+=stride) --> limit <= (max_jint - stride + 1)
461 // for(;i <= limit; i+=stride) --> limit <= (max_jint - stride )
462 //
463
464 // Check if limit is excluded to do more precise int overflow check.
465 bool incl_limit = (bt == BoolTest::le || bt == BoolTest::ge);
466 int stride_m = stride_con - (incl_limit ? 0 : (stride_con > 0 ? 1 : -1));
467
468 // If compare points directly to the phi we need to adjust
469 // the compare so that it points to the incr. Limit have
470 // to be adjusted to keep trip count the same and the
471 // adjusted limit should be checked for int overflow.
472 if (phi_incr != NULL) {
473 stride_m += stride_con;
474 }
475
476 if (limit->is_Con()) {
477 int limit_con = limit->get_int();
478 if ((stride_con > 0 && limit_con > (max_jint - stride_m)) ||
479 (stride_con < 0 && limit_con < (min_jint - stride_m))) {
480 // Bailout: it could be integer overflow.
481 return false;
482 }
483 } else if ((stride_con > 0 && limit_t->_hi <= (max_jint - stride_m)) ||
484 (stride_con < 0 && limit_t->_lo >= (min_jint - stride_m))) {
485 // Limit's type may satisfy the condition, for example,
486 // when it is an array length.
487 } else {
488 // Generate loop's limit check.
489 // Loop limit check predicate should be near the loop.
490 ProjNode *limit_check_proj = find_predicate_insertion_point(init_control, Deoptimization::Reason_loop_limit_check);
491 if (!limit_check_proj) {
492 // The limit check predicate is not generated if this method trapped here before.
493 #ifdef ASSERT
494 if (TraceLoopLimitCheck) {
495 tty->print("missing loop limit check:");
496 loop->dump_head();
497 x->dump(1);
498 }
499 #endif
500 return false;
501 }
502
503 IfNode* check_iff = limit_check_proj->in(0)->as_If();
504 Node* cmp_limit;
505 Node* bol;
506
507 if (stride_con > 0) {
508 cmp_limit = new (C) CmpINode(limit, _igvn.intcon(max_jint - stride_m));
509 bol = new (C) BoolNode(cmp_limit, BoolTest::le);
510 } else {
511 cmp_limit = new (C) CmpINode(limit, _igvn.intcon(min_jint - stride_m));
512 bol = new (C) BoolNode(cmp_limit, BoolTest::ge);
513 }
514 cmp_limit = _igvn.register_new_node_with_optimizer(cmp_limit);
515 bol = _igvn.register_new_node_with_optimizer(bol);
516 set_subtree_ctrl(bol);
517
518 // Replace condition in original predicate but preserve Opaque node
519 // so that previous predicates could be found.
520 assert(check_iff->in(1)->Opcode() == Op_Conv2B &&
521 check_iff->in(1)->in(1)->Opcode() == Op_Opaque1, "");
522 Node* opq = check_iff->in(1)->in(1);
523 _igvn.hash_delete(opq);
524 opq->set_req(1, bol);
525 // Update ctrl.
526 set_ctrl(opq, check_iff->in(0));
527 set_ctrl(check_iff->in(1), check_iff->in(0));
528
529 #ifndef PRODUCT
530 // report that the loop predication has been actually performed
531 // for this loop
532 if (TraceLoopLimitCheck) {
533 tty->print_cr("Counted Loop Limit Check generated:");
534 debug_only( bol->dump(2); )
535 }
536 #endif
537 }
538
539 if (phi_incr != NULL) {
540 // If compare points directly to the phi we need to adjust
541 // the compare so that it points to the incr. Limit have
542 // to be adjusted to keep trip count the same and we
543 // should avoid int overflow.
544 //
545 // i = init; do {} while(i++ < limit);
546 // is converted to
547 // i = init; do {} while(++i < limit+1);
548 //
549 limit = gvn->transform(new (C) AddINode(limit, stride));
550 }
551
552 // Now we need to canonicalize loop condition.
553 if (bt == BoolTest::ne) {
554 assert(stride_con == 1 || stride_con == -1, "simple increment only");
555 // 'ne' can be replaced with 'lt' only when init < limit.
556 if (stride_con > 0 && init_t->_hi < limit_t->_lo)
557 bt = BoolTest::lt;
558 // 'ne' can be replaced with 'gt' only when init > limit.
559 if (stride_con < 0 && init_t->_lo > limit_t->_hi)
560 bt = BoolTest::gt;
561 }
562
563 if (incl_limit) {
564 // The limit check guaranties that 'limit <= (max_jint - stride)' so
565 // we can convert 'i <= limit' to 'i < limit+1' since stride != 0.
566 //
567 Node* one = (stride_con > 0) ? gvn->intcon( 1) : gvn->intcon(-1);
568 limit = gvn->transform(new (C) AddINode(limit, one));
569 if (bt == BoolTest::le)
570 bt = BoolTest::lt;
571 else if (bt == BoolTest::ge)
572 bt = BoolTest::gt;
573 else
574 ShouldNotReachHere();
575 }
576 set_subtree_ctrl( limit );
577
578 } else { // LoopLimitCheck
579
580 // If compare points to incr, we are ok. Otherwise the compare
581 // can directly point to the phi; in this case adjust the compare so that
582 // it points to the incr by adjusting the limit.
583 if (cmp->in(1) == phi || cmp->in(2) == phi)
584 limit = gvn->transform(new (C) AddINode(limit,stride));
585
586 // trip-count for +-tive stride should be: (limit - init_trip + stride - 1)/stride.
587 // Final value for iterator should be: trip_count * stride + init_trip.
588 Node *one_p = gvn->intcon( 1);
589 Node *one_m = gvn->intcon(-1);
590
591 Node *trip_count = NULL;
592 switch( bt ) {
593 case BoolTest::eq:
594 ShouldNotReachHere();
595 case BoolTest::ne: // Ahh, the case we desire
596 if (stride_con == 1)
597 trip_count = gvn->transform(new (C) SubINode(limit,init_trip));
598 else if (stride_con == -1)
599 trip_count = gvn->transform(new (C) SubINode(init_trip,limit));
600 else
601 ShouldNotReachHere();
602 set_subtree_ctrl(trip_count);
603 //_loop.map(trip_count->_idx,loop(limit));
604 break;
605 case BoolTest::le: // Maybe convert to '<' case
606 limit = gvn->transform(new (C) AddINode(limit,one_p));
607 set_subtree_ctrl( limit );
608 hook->init_req(4, limit);
609
610 bt = BoolTest::lt;
611 // Make the new limit be in the same loop nest as the old limit
612 //_loop.map(limit->_idx,limit_loop);
613 // Fall into next case
614 case BoolTest::lt: { // Maybe convert to '!=' case
615 if (stride_con < 0) // Count down loop rolls through MAXINT
616 ShouldNotReachHere();
617 Node *range = gvn->transform(new (C) SubINode(limit,init_trip));
618 set_subtree_ctrl( range );
619 hook->init_req(0, range);
620
621 Node *bias = gvn->transform(new (C) AddINode(range,stride));
622 set_subtree_ctrl( bias );
623 hook->init_req(1, bias);
624
625 Node *bias1 = gvn->transform(new (C) AddINode(bias,one_m));
626 set_subtree_ctrl( bias1 );
627 hook->init_req(2, bias1);
628
629 trip_count = gvn->transform(new (C) DivINode(0,bias1,stride));
630 set_subtree_ctrl( trip_count );
631 hook->init_req(3, trip_count);
632 break;
633 }
634
635 case BoolTest::ge: // Maybe convert to '>' case
636 limit = gvn->transform(new (C) AddINode(limit,one_m));
637 set_subtree_ctrl( limit );
638 hook->init_req(4 ,limit);
639
640 bt = BoolTest::gt;
641 // Make the new limit be in the same loop nest as the old limit
642 //_loop.map(limit->_idx,limit_loop);
643 // Fall into next case
644 case BoolTest::gt: { // Maybe convert to '!=' case
645 if (stride_con > 0) // count up loop rolls through MININT
646 ShouldNotReachHere();
647 Node *range = gvn->transform(new (C) SubINode(limit,init_trip));
648 set_subtree_ctrl( range );
649 hook->init_req(0, range);
650
651 Node *bias = gvn->transform(new (C) AddINode(range,stride));
652 set_subtree_ctrl( bias );
653 hook->init_req(1, bias);
654
655 Node *bias1 = gvn->transform(new (C) AddINode(bias,one_p));
656 set_subtree_ctrl( bias1 );
657 hook->init_req(2, bias1);
658
659 trip_count = gvn->transform(new (C) DivINode(0,bias1,stride));
660 set_subtree_ctrl( trip_count );
661 hook->init_req(3, trip_count);
662 break;
663 }
664 } // switch( bt )
665
666 Node *span = gvn->transform(new (C) MulINode(trip_count,stride));
667 set_subtree_ctrl( span );
668 hook->init_req(5, span);
669
670 limit = gvn->transform(new (C) AddINode(span,init_trip));
671 set_subtree_ctrl( limit );
672
673 } // LoopLimitCheck
674
675 // Check for SafePoint on backedge and remove
676 Node *sfpt = x->in(LoopNode::LoopBackControl);
677 if (sfpt->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt)) {
678 lazy_replace( sfpt, iftrue );
679 if (loop->_safepts != NULL) {
680 loop->_safepts->yank(sfpt);
681 }
682 loop->_tail = iftrue;
683 }
684
685 // Build a canonical trip test.
686 // Clone code, as old values may be in use.
687 incr = incr->clone();
688 incr->set_req(1,phi);
689 incr->set_req(2,stride);
690 incr = _igvn.register_new_node_with_optimizer(incr);
691 set_early_ctrl( incr );
692 _igvn.hash_delete(phi);
693 phi->set_req_X( LoopNode::LoopBackControl, incr, &_igvn );
694
695 // If phi type is more restrictive than Int, raise to
696 // Int to prevent (almost) infinite recursion in igvn
697 // which can only handle integer types for constants or minint..maxint.
698 if (!TypeInt::INT->higher_equal(phi->bottom_type())) {
699 Node* nphi = PhiNode::make(phi->in(0), phi->in(LoopNode::EntryControl), TypeInt::INT);
700 nphi->set_req(LoopNode::LoopBackControl, phi->in(LoopNode::LoopBackControl));
701 nphi = _igvn.register_new_node_with_optimizer(nphi);
702 set_ctrl(nphi, get_ctrl(phi));
703 _igvn.replace_node(phi, nphi);
704 phi = nphi->as_Phi();
705 }
706 cmp = cmp->clone();
707 cmp->set_req(1,incr);
708 cmp->set_req(2,limit);
709 cmp = _igvn.register_new_node_with_optimizer(cmp);
710 set_ctrl(cmp, iff->in(0));
711
712 test = test->clone()->as_Bool();
713 (*(BoolTest*)&test->_test)._test = bt;
714 test->set_req(1,cmp);
715 _igvn.register_new_node_with_optimizer(test);
716 set_ctrl(test, iff->in(0));
717
718 // Replace the old IfNode with a new LoopEndNode
719 Node *lex = _igvn.register_new_node_with_optimizer(new (C) CountedLoopEndNode( iff->in(0), test, cl_prob, iff->as_If()->_fcnt ));
720 IfNode *le = lex->as_If();
721 uint dd = dom_depth(iff);
722 set_idom(le, le->in(0), dd); // Update dominance for loop exit
723 set_loop(le, loop);
724
725 // Get the loop-exit control
726 Node *iffalse = iff->as_If()->proj_out(!(iftrue_op == Op_IfTrue));
727
728 // Need to swap loop-exit and loop-back control?
729 if (iftrue_op == Op_IfFalse) {
730 Node *ift2=_igvn.register_new_node_with_optimizer(new (C) IfTrueNode (le));
731 Node *iff2=_igvn.register_new_node_with_optimizer(new (C) IfFalseNode(le));
732
733 loop->_tail = back_control = ift2;
734 set_loop(ift2, loop);
735 set_loop(iff2, get_loop(iffalse));
736
737 // Lazy update of 'get_ctrl' mechanism.
738 lazy_replace_proj( iffalse, iff2 );
739 lazy_replace_proj( iftrue, ift2 );
740
741 // Swap names
742 iffalse = iff2;
743 iftrue = ift2;
744 } else {
745 _igvn.hash_delete(iffalse);
746 _igvn.hash_delete(iftrue);
747 iffalse->set_req_X( 0, le, &_igvn );
748 iftrue ->set_req_X( 0, le, &_igvn );
749 }
750
751 set_idom(iftrue, le, dd+1);
752 set_idom(iffalse, le, dd+1);
753 assert(iff->outcnt() == 0, "should be dead now");
754 lazy_replace( iff, le ); // fix 'get_ctrl'
755
756 // Now setup a new CountedLoopNode to replace the existing LoopNode
757 CountedLoopNode *l = new (C) CountedLoopNode(init_control, back_control);
758 l->set_unswitch_count(x->as_Loop()->unswitch_count()); // Preserve
759 // The following assert is approximately true, and defines the intention
760 // of can_be_counted_loop. It fails, however, because phase->type
761 // is not yet initialized for this loop and its parts.
762 //assert(l->can_be_counted_loop(this), "sanity");
763 _igvn.register_new_node_with_optimizer(l);
764 set_loop(l, loop);
765 loop->_head = l;
766 // Fix all data nodes placed at the old loop head.
767 // Uses the lazy-update mechanism of 'get_ctrl'.
768 lazy_replace( x, l );
769 set_idom(l, init_control, dom_depth(x));
770
771 // Check for immediately preceding SafePoint and remove
772 Node *sfpt2 = le->in(0);
773 if (sfpt2->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt2)) {
774 lazy_replace( sfpt2, sfpt2->in(TypeFunc::Control));
775 if (loop->_safepts != NULL) {
776 loop->_safepts->yank(sfpt2);
777 }
778 }
779
780 // Free up intermediate goo
781 _igvn.remove_dead_node(hook);
782
783 #ifdef ASSERT
784 assert(l->is_valid_counted_loop(), "counted loop shape is messed up");
785 assert(l == loop->_head && l->phi() == phi && l->loopexit() == lex, "" );
786 #endif
787 #ifndef PRODUCT
788 if (TraceLoopOpts) {
789 tty->print("Counted ");
790 loop->dump_head();
791 }
792 #endif
793
794 C->print_method(PHASE_AFTER_CLOOPS, 3);
795
796 return true;
797 }
798
799 //----------------------exact_limit-------------------------------------------
800 Node* PhaseIdealLoop::exact_limit( IdealLoopTree *loop ) {
801 assert(loop->_head->is_CountedLoop(), "");
802 CountedLoopNode *cl = loop->_head->as_CountedLoop();
803 assert(cl->is_valid_counted_loop(), "");
804
805 if (!LoopLimitCheck || ABS(cl->stride_con()) == 1 ||
806 cl->limit()->Opcode() == Op_LoopLimit) {
807 // Old code has exact limit (it could be incorrect in case of int overflow).
808 // Loop limit is exact with stride == 1. And loop may already have exact limit.
809 return cl->limit();
810 }
811 Node *limit = NULL;
812 #ifdef ASSERT
813 BoolTest::mask bt = cl->loopexit()->test_trip();
814 assert(bt == BoolTest::lt || bt == BoolTest::gt, "canonical test is expected");
815 #endif
816 if (cl->has_exact_trip_count()) {
817 // Simple case: loop has constant boundaries.
818 // Use jlongs to avoid integer overflow.
819 int stride_con = cl->stride_con();
820 jlong init_con = cl->init_trip()->get_int();
821 jlong limit_con = cl->limit()->get_int();
822 julong trip_cnt = cl->trip_count();
823 jlong final_con = init_con + trip_cnt*stride_con;
824 int final_int = (int)final_con;
825 // The final value should be in integer range since the loop
826 // is counted and the limit was checked for overflow.
827 assert(final_con == (jlong)final_int, "final value should be integer");
828 limit = _igvn.intcon(final_int);
829 } else {
830 // Create new LoopLimit node to get exact limit (final iv value).
831 limit = new (C) LoopLimitNode(C, cl->init_trip(), cl->limit(), cl->stride());
832 register_new_node(limit, cl->in(LoopNode::EntryControl));
833 }
834 assert(limit != NULL, "sanity");
835 return limit;
836 }
837
838 //------------------------------Ideal------------------------------------------
839 // Return a node which is more "ideal" than the current node.
840 // Attempt to convert into a counted-loop.
841 Node *LoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
842 if (!can_be_counted_loop(phase)) {
843 phase->C->set_major_progress();
844 }
845 return RegionNode::Ideal(phase, can_reshape);
846 }
847
848
849 //=============================================================================
850 //------------------------------Ideal------------------------------------------
851 // Return a node which is more "ideal" than the current node.
852 // Attempt to convert into a counted-loop.
853 Node *CountedLoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
854 return RegionNode::Ideal(phase, can_reshape);
855 }
856
857 //------------------------------dump_spec--------------------------------------
858 // Dump special per-node info
859 #ifndef PRODUCT
860 void CountedLoopNode::dump_spec(outputStream *st) const {
861 LoopNode::dump_spec(st);
862 if (stride_is_con()) {
863 st->print("stride: %d ",stride_con());
864 }
865 if (is_pre_loop ()) st->print("pre of N%d" , _main_idx);
866 if (is_main_loop()) st->print("main of N%d", _idx);
867 if (is_post_loop()) st->print("post of N%d", _main_idx);
868 }
869 #endif
870
871 //=============================================================================
872 int CountedLoopEndNode::stride_con() const {
873 return stride()->bottom_type()->is_int()->get_con();
874 }
875
876 //=============================================================================
877 //------------------------------Value-----------------------------------------
878 const Type *LoopLimitNode::Value( PhaseTransform *phase ) const {
879 const Type* init_t = phase->type(in(Init));
880 const Type* limit_t = phase->type(in(Limit));
881 const Type* stride_t = phase->type(in(Stride));
882 // Either input is TOP ==> the result is TOP
883 if (init_t == Type::TOP) return Type::TOP;
884 if (limit_t == Type::TOP) return Type::TOP;
885 if (stride_t == Type::TOP) return Type::TOP;
886
887 int stride_con = stride_t->is_int()->get_con();
888 if (stride_con == 1)
889 return NULL; // Identity
890
891 if (init_t->is_int()->is_con() && limit_t->is_int()->is_con()) {
892 // Use jlongs to avoid integer overflow.
893 jlong init_con = init_t->is_int()->get_con();
894 jlong limit_con = limit_t->is_int()->get_con();
895 int stride_m = stride_con - (stride_con > 0 ? 1 : -1);
896 jlong trip_count = (limit_con - init_con + stride_m)/stride_con;
897 jlong final_con = init_con + stride_con*trip_count;
898 int final_int = (int)final_con;
899 // The final value should be in integer range since the loop
900 // is counted and the limit was checked for overflow.
901 assert(final_con == (jlong)final_int, "final value should be integer");
902 return TypeInt::make(final_int);
903 }
904
905 return bottom_type(); // TypeInt::INT
906 }
907
908 //------------------------------Ideal------------------------------------------
909 // Return a node which is more "ideal" than the current node.
910 Node *LoopLimitNode::Ideal(PhaseGVN *phase, bool can_reshape) {
911 if (phase->type(in(Init)) == Type::TOP ||
912 phase->type(in(Limit)) == Type::TOP ||
913 phase->type(in(Stride)) == Type::TOP)
914 return NULL; // Dead
915
916 int stride_con = phase->type(in(Stride))->is_int()->get_con();
917 if (stride_con == 1)
918 return NULL; // Identity
919
920 if (in(Init)->is_Con() && in(Limit)->is_Con())
921 return NULL; // Value
922
923 // Delay following optimizations until all loop optimizations
924 // done to keep Ideal graph simple.
925 if (!can_reshape || phase->C->major_progress())
926 return NULL;
927
928 const TypeInt* init_t = phase->type(in(Init) )->is_int();
929 const TypeInt* limit_t = phase->type(in(Limit))->is_int();
930 int stride_p;
931 jlong lim, ini;
932 julong max;
933 if (stride_con > 0) {
934 stride_p = stride_con;
935 lim = limit_t->_hi;
936 ini = init_t->_lo;
937 max = (julong)max_jint;
938 } else {
939 stride_p = -stride_con;
940 lim = init_t->_hi;
941 ini = limit_t->_lo;
942 max = (julong)min_jint;
943 }
944 julong range = lim - ini + stride_p;
945 if (range <= max) {
946 // Convert to integer expression if it is not overflow.
947 Node* stride_m = phase->intcon(stride_con - (stride_con > 0 ? 1 : -1));
948 Node *range = phase->transform(new (phase->C) SubINode(in(Limit), in(Init)));
949 Node *bias = phase->transform(new (phase->C) AddINode(range, stride_m));
950 Node *trip = phase->transform(new (phase->C) DivINode(0, bias, in(Stride)));
951 Node *span = phase->transform(new (phase->C) MulINode(trip, in(Stride)));
952 return new (phase->C) AddINode(span, in(Init)); // exact limit
953 }
954
955 if (is_power_of_2(stride_p) || // divisor is 2^n
956 !Matcher::has_match_rule(Op_LoopLimit)) { // or no specialized Mach node?
957 // Convert to long expression to avoid integer overflow
958 // and let igvn optimizer convert this division.
959 //
960 Node* init = phase->transform( new (phase->C) ConvI2LNode(in(Init)));
961 Node* limit = phase->transform( new (phase->C) ConvI2LNode(in(Limit)));
962 Node* stride = phase->longcon(stride_con);
963 Node* stride_m = phase->longcon(stride_con - (stride_con > 0 ? 1 : -1));
964
965 Node *range = phase->transform(new (phase->C) SubLNode(limit, init));
966 Node *bias = phase->transform(new (phase->C) AddLNode(range, stride_m));
967 Node *span;
968 if (stride_con > 0 && is_power_of_2(stride_p)) {
969 // bias >= 0 if stride >0, so if stride is 2^n we can use &(-stride)
970 // and avoid generating rounding for division. Zero trip guard should
971 // guarantee that init < limit but sometimes the guard is missing and
972 // we can get situation when init > limit. Note, for the empty loop
973 // optimization zero trip guard is generated explicitly which leaves
974 // only RCE predicate where exact limit is used and the predicate
975 // will simply fail forcing recompilation.
976 Node* neg_stride = phase->longcon(-stride_con);
977 span = phase->transform(new (phase->C) AndLNode(bias, neg_stride));
978 } else {
979 Node *trip = phase->transform(new (phase->C) DivLNode(0, bias, stride));
980 span = phase->transform(new (phase->C) MulLNode(trip, stride));
981 }
982 // Convert back to int
983 Node *span_int = phase->transform(new (phase->C) ConvL2INode(span));
984 return new (phase->C) AddINode(span_int, in(Init)); // exact limit
985 }
986
987 return NULL; // No progress
988 }
989
990 //------------------------------Identity---------------------------------------
991 // If stride == 1 return limit node.
992 Node *LoopLimitNode::Identity( PhaseTransform *phase ) {
993 int stride_con = phase->type(in(Stride))->is_int()->get_con();
994 if (stride_con == 1 || stride_con == -1)
995 return in(Limit);
996 return this;
997 }
998
999 //=============================================================================
1000 //----------------------match_incr_with_optional_truncation--------------------
1001 // Match increment with optional truncation:
1002 // CHAR: (i+1)&0x7fff, BYTE: ((i+1)<<8)>>8, or SHORT: ((i+1)<<16)>>16
1003 // Return NULL for failure. Success returns the increment node.
1004 Node* CountedLoopNode::match_incr_with_optional_truncation(
1005 Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type) {
1006 // Quick cutouts:
1007 if (expr == NULL || expr->req() != 3) return NULL;
1008
1009 Node *t1 = NULL;
1010 Node *t2 = NULL;
1011 const TypeInt* trunc_t = TypeInt::INT;
1012 Node* n1 = expr;
1013 int n1op = n1->Opcode();
1014
1015 // Try to strip (n1 & M) or (n1 << N >> N) from n1.
1016 if (n1op == Op_AndI &&
1017 n1->in(2)->is_Con() &&
1018 n1->in(2)->bottom_type()->is_int()->get_con() == 0x7fff) {
1019 // %%% This check should match any mask of 2**K-1.
1020 t1 = n1;
1021 n1 = t1->in(1);
1022 n1op = n1->Opcode();
1023 trunc_t = TypeInt::CHAR;
1024 } else if (n1op == Op_RShiftI &&
1025 n1->in(1) != NULL &&
1026 n1->in(1)->Opcode() == Op_LShiftI &&
1027 n1->in(2) == n1->in(1)->in(2) &&
1028 n1->in(2)->is_Con()) {
1029 jint shift = n1->in(2)->bottom_type()->is_int()->get_con();
1030 // %%% This check should match any shift in [1..31].
1031 if (shift == 16 || shift == 8) {
1032 t1 = n1;
1033 t2 = t1->in(1);
1034 n1 = t2->in(1);
1035 n1op = n1->Opcode();
1036 if (shift == 16) {
1037 trunc_t = TypeInt::SHORT;
1038 } else if (shift == 8) {
1039 trunc_t = TypeInt::BYTE;
1040 }
1041 }
1042 }
1043
1044 // If (maybe after stripping) it is an AddI, we won:
1045 if (n1op == Op_AddI) {
1046 *trunc1 = t1;
1047 *trunc2 = t2;
1048 *trunc_type = trunc_t;
1049 return n1;
1050 }
1051
1052 // failed
1053 return NULL;
1054 }
1055
1056
1057 //------------------------------filtered_type--------------------------------
1058 // Return a type based on condition control flow
1059 // A successful return will be a type that is restricted due
1060 // to a series of dominating if-tests, such as:
1061 // if (i < 10) {
1062 // if (i > 0) {
1063 // here: "i" type is [1..10)
1064 // }
1065 // }
1066 // or a control flow merge
1067 // if (i < 10) {
1068 // do {
1069 // phi( , ) -- at top of loop type is [min_int..10)
1070 // i = ?
1071 // } while ( i < 10)
1072 //
1073 const TypeInt* PhaseIdealLoop::filtered_type( Node *n, Node* n_ctrl) {
1074 assert(n && n->bottom_type()->is_int(), "must be int");
1075 const TypeInt* filtered_t = NULL;
1076 if (!n->is_Phi()) {
1077 assert(n_ctrl != NULL || n_ctrl == C->top(), "valid control");
1078 filtered_t = filtered_type_from_dominators(n, n_ctrl);
1079
1080 } else {
1081 Node* phi = n->as_Phi();
1082 Node* region = phi->in(0);
1083 assert(n_ctrl == NULL || n_ctrl == region, "ctrl parameter must be region");
1084 if (region && region != C->top()) {
1085 for (uint i = 1; i < phi->req(); i++) {
1086 Node* val = phi->in(i);
1087 Node* use_c = region->in(i);
1088 const TypeInt* val_t = filtered_type_from_dominators(val, use_c);
1089 if (val_t != NULL) {
1090 if (filtered_t == NULL) {
1091 filtered_t = val_t;
1092 } else {
1093 filtered_t = filtered_t->meet(val_t)->is_int();
1094 }
1095 }
1096 }
1097 }
1098 }
1099 const TypeInt* n_t = _igvn.type(n)->is_int();
1100 if (filtered_t != NULL) {
1101 n_t = n_t->join(filtered_t)->is_int();
1102 }
1103 return n_t;
1104 }
1105
1106
1107 //------------------------------filtered_type_from_dominators--------------------------------
1108 // Return a possibly more restrictive type for val based on condition control flow of dominators
1109 const TypeInt* PhaseIdealLoop::filtered_type_from_dominators( Node* val, Node *use_ctrl) {
1110 if (val->is_Con()) {
1111 return val->bottom_type()->is_int();
1112 }
1113 uint if_limit = 10; // Max number of dominating if's visited
1114 const TypeInt* rtn_t = NULL;
1115
1116 if (use_ctrl && use_ctrl != C->top()) {
1117 Node* val_ctrl = get_ctrl(val);
1118 uint val_dom_depth = dom_depth(val_ctrl);
1119 Node* pred = use_ctrl;
1120 uint if_cnt = 0;
1121 while (if_cnt < if_limit) {
1122 if ((pred->Opcode() == Op_IfTrue || pred->Opcode() == Op_IfFalse)) {
1123 if_cnt++;
1124 const TypeInt* if_t = IfNode::filtered_int_type(&_igvn, val, pred);
1125 if (if_t != NULL) {
1126 if (rtn_t == NULL) {
1127 rtn_t = if_t;
1128 } else {
1129 rtn_t = rtn_t->join(if_t)->is_int();
1130 }
1131 }
1132 }
1133 pred = idom(pred);
1134 if (pred == NULL || pred == C->top()) {
1135 break;
1136 }
1137 // Stop if going beyond definition block of val
1138 if (dom_depth(pred) < val_dom_depth) {
1139 break;
1140 }
1141 }
1142 }
1143 return rtn_t;
1144 }
1145
1146
1147 //------------------------------dump_spec--------------------------------------
1148 // Dump special per-node info
1149 #ifndef PRODUCT
1150 void CountedLoopEndNode::dump_spec(outputStream *st) const {
1151 if( in(TestValue)->is_Bool() ) {
1152 BoolTest bt( test_trip()); // Added this for g++.
1153
1154 st->print("[");
1155 bt.dump_on(st);
1156 st->print("]");
1157 }
1158 st->print(" ");
1159 IfNode::dump_spec(st);
1160 }
1161 #endif
1162
1163 //=============================================================================
1164 //------------------------------is_member--------------------------------------
1165 // Is 'l' a member of 'this'?
1166 int IdealLoopTree::is_member( const IdealLoopTree *l ) const {
1167 while( l->_nest > _nest ) l = l->_parent;
1168 return l == this;
1169 }
1170
1171 //------------------------------set_nest---------------------------------------
1172 // Set loop tree nesting depth. Accumulate _has_call bits.
1173 int IdealLoopTree::set_nest( uint depth ) {
1174 _nest = depth;
1175 int bits = _has_call;
1176 if( _child ) bits |= _child->set_nest(depth+1);
1177 if( bits ) _has_call = 1;
1178 if( _next ) bits |= _next ->set_nest(depth );
1179 return bits;
1180 }
1181
1182 //------------------------------split_fall_in----------------------------------
1183 // Split out multiple fall-in edges from the loop header. Move them to a
1184 // private RegionNode before the loop. This becomes the loop landing pad.
1185 void IdealLoopTree::split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ) {
1186 PhaseIterGVN &igvn = phase->_igvn;
1187 uint i;
1188
1189 // Make a new RegionNode to be the landing pad.
1190 Node *landing_pad = new (phase->C) RegionNode( fall_in_cnt+1 );
1191 phase->set_loop(landing_pad,_parent);
1192 // Gather all the fall-in control paths into the landing pad
1193 uint icnt = fall_in_cnt;
1194 uint oreq = _head->req();
1195 for( i = oreq-1; i>0; i-- )
1196 if( !phase->is_member( this, _head->in(i) ) )
1197 landing_pad->set_req(icnt--,_head->in(i));
1198
1199 // Peel off PhiNode edges as well
1200 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1201 Node *oj = _head->fast_out(j);
1202 if( oj->is_Phi() ) {
1203 PhiNode* old_phi = oj->as_Phi();
1204 assert( old_phi->region() == _head, "" );
1205 igvn.hash_delete(old_phi); // Yank from hash before hacking edges
1206 Node *p = PhiNode::make_blank(landing_pad, old_phi);
1207 uint icnt = fall_in_cnt;
1208 for( i = oreq-1; i>0; i-- ) {
1209 if( !phase->is_member( this, _head->in(i) ) ) {
1210 p->init_req(icnt--, old_phi->in(i));
1211 // Go ahead and clean out old edges from old phi
1212 old_phi->del_req(i);
1213 }
1214 }
1215 // Search for CSE's here, because ZKM.jar does a lot of
1216 // loop hackery and we need to be a little incremental
1217 // with the CSE to avoid O(N^2) node blow-up.
1218 Node *p2 = igvn.hash_find_insert(p); // Look for a CSE
1219 if( p2 ) { // Found CSE
1220 p->destruct(); // Recover useless new node
1221 p = p2; // Use old node
1222 } else {
1223 igvn.register_new_node_with_optimizer(p, old_phi);
1224 }
1225 // Make old Phi refer to new Phi.
1226 old_phi->add_req(p);
1227 // Check for the special case of making the old phi useless and
1228 // disappear it. In JavaGrande I have a case where this useless
1229 // Phi is the loop limit and prevents recognizing a CountedLoop
1230 // which in turn prevents removing an empty loop.
1231 Node *id_old_phi = old_phi->Identity( &igvn );
1232 if( id_old_phi != old_phi ) { // Found a simple identity?
1233 // Note that I cannot call 'replace_node' here, because
1234 // that will yank the edge from old_phi to the Region and
1235 // I'm mid-iteration over the Region's uses.
1236 for (DUIterator_Last imin, i = old_phi->last_outs(imin); i >= imin; ) {
1237 Node* use = old_phi->last_out(i);
1238 igvn.rehash_node_delayed(use);
1239 uint uses_found = 0;
1240 for (uint j = 0; j < use->len(); j++) {
1241 if (use->in(j) == old_phi) {
1242 if (j < use->req()) use->set_req (j, id_old_phi);
1243 else use->set_prec(j, id_old_phi);
1244 uses_found++;
1245 }
1246 }
1247 i -= uses_found; // we deleted 1 or more copies of this edge
1248 }
1249 }
1250 igvn._worklist.push(old_phi);
1251 }
1252 }
1253 // Finally clean out the fall-in edges from the RegionNode
1254 for( i = oreq-1; i>0; i-- ) {
1255 if( !phase->is_member( this, _head->in(i) ) ) {
1256 _head->del_req(i);
1257 }
1258 }
1259 // Transform landing pad
1260 igvn.register_new_node_with_optimizer(landing_pad, _head);
1261 // Insert landing pad into the header
1262 _head->add_req(landing_pad);
1263 }
1264
1265 //------------------------------split_outer_loop-------------------------------
1266 // Split out the outermost loop from this shared header.
1267 void IdealLoopTree::split_outer_loop( PhaseIdealLoop *phase ) {
1268 PhaseIterGVN &igvn = phase->_igvn;
1269
1270 // Find index of outermost loop; it should also be my tail.
1271 uint outer_idx = 1;
1272 while( _head->in(outer_idx) != _tail ) outer_idx++;
1273
1274 // Make a LoopNode for the outermost loop.
1275 Node *ctl = _head->in(LoopNode::EntryControl);
1276 Node *outer = new (phase->C) LoopNode( ctl, _head->in(outer_idx) );
1277 outer = igvn.register_new_node_with_optimizer(outer, _head);
1278 phase->set_created_loop_node();
1279
1280 // Outermost loop falls into '_head' loop
1281 _head->set_req(LoopNode::EntryControl, outer);
1282 _head->del_req(outer_idx);
1283 // Split all the Phis up between '_head' loop and 'outer' loop.
1284 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1285 Node *out = _head->fast_out(j);
1286 if( out->is_Phi() ) {
1287 PhiNode *old_phi = out->as_Phi();
1288 assert( old_phi->region() == _head, "" );
1289 Node *phi = PhiNode::make_blank(outer, old_phi);
1290 phi->init_req(LoopNode::EntryControl, old_phi->in(LoopNode::EntryControl));
1291 phi->init_req(LoopNode::LoopBackControl, old_phi->in(outer_idx));
1292 phi = igvn.register_new_node_with_optimizer(phi, old_phi);
1293 // Make old Phi point to new Phi on the fall-in path
1294 igvn.replace_input_of(old_phi, LoopNode::EntryControl, phi);
1295 old_phi->del_req(outer_idx);
1296 }
1297 }
1298
1299 // Use the new loop head instead of the old shared one
1300 _head = outer;
1301 phase->set_loop(_head, this);
1302 }
1303
1304 //------------------------------fix_parent-------------------------------------
1305 static void fix_parent( IdealLoopTree *loop, IdealLoopTree *parent ) {
1306 loop->_parent = parent;
1307 if( loop->_child ) fix_parent( loop->_child, loop );
1308 if( loop->_next ) fix_parent( loop->_next , parent );
1309 }
1310
1311 //------------------------------estimate_path_freq-----------------------------
1312 static float estimate_path_freq( Node *n ) {
1313 // Try to extract some path frequency info
1314 IfNode *iff;
1315 for( int i = 0; i < 50; i++ ) { // Skip through a bunch of uncommon tests
1316 uint nop = n->Opcode();
1317 if( nop == Op_SafePoint ) { // Skip any safepoint
1318 n = n->in(0);
1319 continue;
1320 }
1321 if( nop == Op_CatchProj ) { // Get count from a prior call
1322 // Assume call does not always throw exceptions: means the call-site
1323 // count is also the frequency of the fall-through path.
1324 assert( n->is_CatchProj(), "" );
1325 if( ((CatchProjNode*)n)->_con != CatchProjNode::fall_through_index )
1326 return 0.0f; // Assume call exception path is rare
1327 Node *call = n->in(0)->in(0)->in(0);
1328 assert( call->is_Call(), "expect a call here" );
1329 const JVMState *jvms = ((CallNode*)call)->jvms();
1330 ciMethodData* methodData = jvms->method()->method_data();
1331 if (!methodData->is_mature()) return 0.0f; // No call-site data
1332 ciProfileData* data = methodData->bci_to_data(jvms->bci());
1333 if ((data == NULL) || !data->is_CounterData()) {
1334 // no call profile available, try call's control input
1335 n = n->in(0);
1336 continue;
1337 }
1338 return data->as_CounterData()->count()/FreqCountInvocations;
1339 }
1340 // See if there's a gating IF test
1341 Node *n_c = n->in(0);
1342 if( !n_c->is_If() ) break; // No estimate available
1343 iff = n_c->as_If();
1344 if( iff->_fcnt != COUNT_UNKNOWN ) // Have a valid count?
1345 // Compute how much count comes on this path
1346 return ((nop == Op_IfTrue) ? iff->_prob : 1.0f - iff->_prob) * iff->_fcnt;
1347 // Have no count info. Skip dull uncommon-trap like branches.
1348 if( (nop == Op_IfTrue && iff->_prob < PROB_LIKELY_MAG(5)) ||
1349 (nop == Op_IfFalse && iff->_prob > PROB_UNLIKELY_MAG(5)) )
1350 break;
1351 // Skip through never-taken branch; look for a real loop exit.
1352 n = iff->in(0);
1353 }
1354 return 0.0f; // No estimate available
1355 }
1356
1357 //------------------------------merge_many_backedges---------------------------
1358 // Merge all the backedges from the shared header into a private Region.
1359 // Feed that region as the one backedge to this loop.
1360 void IdealLoopTree::merge_many_backedges( PhaseIdealLoop *phase ) {
1361 uint i;
1362
1363 // Scan for the top 2 hottest backedges
1364 float hotcnt = 0.0f;
1365 float warmcnt = 0.0f;
1366 uint hot_idx = 0;
1367 // Loop starts at 2 because slot 1 is the fall-in path
1368 for( i = 2; i < _head->req(); i++ ) {
1369 float cnt = estimate_path_freq(_head->in(i));
1370 if( cnt > hotcnt ) { // Grab hottest path
1371 warmcnt = hotcnt;
1372 hotcnt = cnt;
1373 hot_idx = i;
1374 } else if( cnt > warmcnt ) { // And 2nd hottest path
1375 warmcnt = cnt;
1376 }
1377 }
1378
1379 // See if the hottest backedge is worthy of being an inner loop
1380 // by being much hotter than the next hottest backedge.
1381 if( hotcnt <= 0.0001 ||
1382 hotcnt < 2.0*warmcnt ) hot_idx = 0;// No hot backedge
1383
1384 // Peel out the backedges into a private merge point; peel
1385 // them all except optionally hot_idx.
1386 PhaseIterGVN &igvn = phase->_igvn;
1387
1388 Node *hot_tail = NULL;
1389 // Make a Region for the merge point
1390 Node *r = new (phase->C) RegionNode(1);
1391 for( i = 2; i < _head->req(); i++ ) {
1392 if( i != hot_idx )
1393 r->add_req( _head->in(i) );
1394 else hot_tail = _head->in(i);
1395 }
1396 igvn.register_new_node_with_optimizer(r, _head);
1397 // Plug region into end of loop _head, followed by hot_tail
1398 while( _head->req() > 3 ) _head->del_req( _head->req()-1 );
1399 _head->set_req(2, r);
1400 if( hot_idx ) _head->add_req(hot_tail);
1401
1402 // Split all the Phis up between '_head' loop and the Region 'r'
1403 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1404 Node *out = _head->fast_out(j);
1405 if( out->is_Phi() ) {
1406 PhiNode* n = out->as_Phi();
1407 igvn.hash_delete(n); // Delete from hash before hacking edges
1408 Node *hot_phi = NULL;
1409 Node *phi = new (phase->C) PhiNode(r, n->type(), n->adr_type());
1410 // Check all inputs for the ones to peel out
1411 uint j = 1;
1412 for( uint i = 2; i < n->req(); i++ ) {
1413 if( i != hot_idx )
1414 phi->set_req( j++, n->in(i) );
1415 else hot_phi = n->in(i);
1416 }
1417 // Register the phi but do not transform until whole place transforms
1418 igvn.register_new_node_with_optimizer(phi, n);
1419 // Add the merge phi to the old Phi
1420 while( n->req() > 3 ) n->del_req( n->req()-1 );
1421 n->set_req(2, phi);
1422 if( hot_idx ) n->add_req(hot_phi);
1423 }
1424 }
1425
1426
1427 // Insert a new IdealLoopTree inserted below me. Turn it into a clone
1428 // of self loop tree. Turn self into a loop headed by _head and with
1429 // tail being the new merge point.
1430 IdealLoopTree *ilt = new IdealLoopTree( phase, _head, _tail );
1431 phase->set_loop(_tail,ilt); // Adjust tail
1432 _tail = r; // Self's tail is new merge point
1433 phase->set_loop(r,this);
1434 ilt->_child = _child; // New guy has my children
1435 _child = ilt; // Self has new guy as only child
1436 ilt->_parent = this; // new guy has self for parent
1437 ilt->_nest = _nest; // Same nesting depth (for now)
1438
1439 // Starting with 'ilt', look for child loop trees using the same shared
1440 // header. Flatten these out; they will no longer be loops in the end.
1441 IdealLoopTree **pilt = &_child;
1442 while( ilt ) {
1443 if( ilt->_head == _head ) {
1444 uint i;
1445 for( i = 2; i < _head->req(); i++ )
1446 if( _head->in(i) == ilt->_tail )
1447 break; // Still a loop
1448 if( i == _head->req() ) { // No longer a loop
1449 // Flatten ilt. Hang ilt's "_next" list from the end of
1450 // ilt's '_child' list. Move the ilt's _child up to replace ilt.
1451 IdealLoopTree **cp = &ilt->_child;
1452 while( *cp ) cp = &(*cp)->_next; // Find end of child list
1453 *cp = ilt->_next; // Hang next list at end of child list
1454 *pilt = ilt->_child; // Move child up to replace ilt
1455 ilt->_head = NULL; // Flag as a loop UNIONED into parent
1456 ilt = ilt->_child; // Repeat using new ilt
1457 continue; // do not advance over ilt->_child
1458 }
1459 assert( ilt->_tail == hot_tail, "expected to only find the hot inner loop here" );
1460 phase->set_loop(_head,ilt);
1461 }
1462 pilt = &ilt->_child; // Advance to next
1463 ilt = *pilt;
1464 }
1465
1466 if( _child ) fix_parent( _child, this );
1467 }
1468
1469 //------------------------------beautify_loops---------------------------------
1470 // Split shared headers and insert loop landing pads.
1471 // Insert a LoopNode to replace the RegionNode.
1472 // Return TRUE if loop tree is structurally changed.
1473 bool IdealLoopTree::beautify_loops( PhaseIdealLoop *phase ) {
1474 bool result = false;
1475 // Cache parts in locals for easy
1476 PhaseIterGVN &igvn = phase->_igvn;
1477
1478 igvn.hash_delete(_head); // Yank from hash before hacking edges
1479
1480 // Check for multiple fall-in paths. Peel off a landing pad if need be.
1481 int fall_in_cnt = 0;
1482 for( uint i = 1; i < _head->req(); i++ )
1483 if( !phase->is_member( this, _head->in(i) ) )
1484 fall_in_cnt++;
1485 assert( fall_in_cnt, "at least 1 fall-in path" );
1486 if( fall_in_cnt > 1 ) // Need a loop landing pad to merge fall-ins
1487 split_fall_in( phase, fall_in_cnt );
1488
1489 // Swap inputs to the _head and all Phis to move the fall-in edge to
1490 // the left.
1491 fall_in_cnt = 1;
1492 while( phase->is_member( this, _head->in(fall_in_cnt) ) )
1493 fall_in_cnt++;
1494 if( fall_in_cnt > 1 ) {
1495 // Since I am just swapping inputs I do not need to update def-use info
1496 Node *tmp = _head->in(1);
1497 _head->set_req( 1, _head->in(fall_in_cnt) );
1498 _head->set_req( fall_in_cnt, tmp );
1499 // Swap also all Phis
1500 for (DUIterator_Fast imax, i = _head->fast_outs(imax); i < imax; i++) {
1501 Node* phi = _head->fast_out(i);
1502 if( phi->is_Phi() ) {
1503 igvn.hash_delete(phi); // Yank from hash before hacking edges
1504 tmp = phi->in(1);
1505 phi->set_req( 1, phi->in(fall_in_cnt) );
1506 phi->set_req( fall_in_cnt, tmp );
1507 }
1508 }
1509 }
1510 assert( !phase->is_member( this, _head->in(1) ), "left edge is fall-in" );
1511 assert( phase->is_member( this, _head->in(2) ), "right edge is loop" );
1512
1513 // If I am a shared header (multiple backedges), peel off the many
1514 // backedges into a private merge point and use the merge point as
1515 // the one true backedge.
1516 if( _head->req() > 3 ) {
1517 // Merge the many backedges into a single backedge but leave
1518 // the hottest backedge as separate edge for the following peel.
1519 merge_many_backedges( phase );
1520 result = true;
1521 }
1522
1523 // If I have one hot backedge, peel off myself loop.
1524 // I better be the outermost loop.
1525 if( _head->req() > 3 ) {
1526 split_outer_loop( phase );
1527 result = true;
1528
1529 } else if( !_head->is_Loop() && !_irreducible ) {
1530 // Make a new LoopNode to replace the old loop head
1531 Node *l = new (phase->C) LoopNode( _head->in(1), _head->in(2) );
1532 l = igvn.register_new_node_with_optimizer(l, _head);
1533 phase->set_created_loop_node();
1534 // Go ahead and replace _head
1535 phase->_igvn.replace_node( _head, l );
1536 _head = l;
1537 phase->set_loop(_head, this);
1538 }
1539
1540 // Now recursively beautify nested loops
1541 if( _child ) result |= _child->beautify_loops( phase );
1542 if( _next ) result |= _next ->beautify_loops( phase );
1543 return result;
1544 }
1545
1546 //------------------------------allpaths_check_safepts----------------------------
1547 // Allpaths backwards scan from loop tail, terminating each path at first safepoint
1548 // encountered. Helper for check_safepts.
1549 void IdealLoopTree::allpaths_check_safepts(VectorSet &visited, Node_List &stack) {
1550 assert(stack.size() == 0, "empty stack");
1551 stack.push(_tail);
1552 visited.Clear();
1553 visited.set(_tail->_idx);
1554 while (stack.size() > 0) {
1555 Node* n = stack.pop();
1556 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
1557 // Terminate this path
1558 } else if (n->Opcode() == Op_SafePoint) {
1559 if (_phase->get_loop(n) != this) {
1560 if (_required_safept == NULL) _required_safept = new Node_List();
1561 _required_safept->push(n); // save the one closest to the tail
1562 }
1563 // Terminate this path
1564 } else {
1565 uint start = n->is_Region() ? 1 : 0;
1566 uint end = n->is_Region() && !n->is_Loop() ? n->req() : start + 1;
1567 for (uint i = start; i < end; i++) {
1568 Node* in = n->in(i);
1569 assert(in->is_CFG(), "must be");
1570 if (!visited.test_set(in->_idx) && is_member(_phase->get_loop(in))) {
1571 stack.push(in);
1572 }
1573 }
1574 }
1575 }
1576 }
1577
1578 //------------------------------check_safepts----------------------------
1579 // Given dominators, try to find loops with calls that must always be
1580 // executed (call dominates loop tail). These loops do not need non-call
1581 // safepoints (ncsfpt).
1582 //
1583 // A complication is that a safepoint in a inner loop may be needed
1584 // by an outer loop. In the following, the inner loop sees it has a
1585 // call (block 3) on every path from the head (block 2) to the
1586 // backedge (arc 3->2). So it deletes the ncsfpt (non-call safepoint)
1587 // in block 2, _but_ this leaves the outer loop without a safepoint.
1588 //
1589 // entry 0
1590 // |
1591 // v
1592 // outer 1,2 +->1
1593 // | |
1594 // | v
1595 // | 2<---+ ncsfpt in 2
1596 // |_/|\ |
1597 // | v |
1598 // inner 2,3 / 3 | call in 3
1599 // / | |
1600 // v +--+
1601 // exit 4
1602 //
1603 //
1604 // This method creates a list (_required_safept) of ncsfpt nodes that must
1605 // be protected is created for each loop. When a ncsfpt maybe deleted, it
1606 // is first looked for in the lists for the outer loops of the current loop.
1607 //
1608 // The insights into the problem:
1609 // A) counted loops are okay
1610 // B) innermost loops are okay (only an inner loop can delete
1611 // a ncsfpt needed by an outer loop)
1612 // C) a loop is immune from an inner loop deleting a safepoint
1613 // if the loop has a call on the idom-path
1614 // D) a loop is also immune if it has a ncsfpt (non-call safepoint) on the
1615 // idom-path that is not in a nested loop
1616 // E) otherwise, an ncsfpt on the idom-path that is nested in an inner
1617 // loop needs to be prevented from deletion by an inner loop
1618 //
1619 // There are two analyses:
1620 // 1) The first, and cheaper one, scans the loop body from
1621 // tail to head following the idom (immediate dominator)
1622 // chain, looking for the cases (C,D,E) above.
1623 // Since inner loops are scanned before outer loops, there is summary
1624 // information about inner loops. Inner loops can be skipped over
1625 // when the tail of an inner loop is encountered.
1626 //
1627 // 2) The second, invoked if the first fails to find a call or ncsfpt on
1628 // the idom path (which is rare), scans all predecessor control paths
1629 // from the tail to the head, terminating a path when a call or sfpt
1630 // is encountered, to find the ncsfpt's that are closest to the tail.
1631 //
1632 void IdealLoopTree::check_safepts(VectorSet &visited, Node_List &stack) {
1633 // Bottom up traversal
1634 IdealLoopTree* ch = _child;
1635 if (_child) _child->check_safepts(visited, stack);
1636 if (_next) _next ->check_safepts(visited, stack);
1637
1638 if (!_head->is_CountedLoop() && !_has_sfpt && _parent != NULL && !_irreducible) {
1639 bool has_call = false; // call on dom-path
1640 bool has_local_ncsfpt = false; // ncsfpt on dom-path at this loop depth
1641 Node* nonlocal_ncsfpt = NULL; // ncsfpt on dom-path at a deeper depth
1642 // Scan the dom-path nodes from tail to head
1643 for (Node* n = tail(); n != _head; n = _phase->idom(n)) {
1644 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
1645 has_call = true;
1646 _has_sfpt = 1; // Then no need for a safept!
1647 break;
1648 } else if (n->Opcode() == Op_SafePoint) {
1649 if (_phase->get_loop(n) == this) {
1650 has_local_ncsfpt = true;
1651 break;
1652 }
1653 if (nonlocal_ncsfpt == NULL) {
1654 nonlocal_ncsfpt = n; // save the one closest to the tail
1655 }
1656 } else {
1657 IdealLoopTree* nlpt = _phase->get_loop(n);
1658 if (this != nlpt) {
1659 // If at an inner loop tail, see if the inner loop has already
1660 // recorded seeing a call on the dom-path (and stop.) If not,
1661 // jump to the head of the inner loop.
1662 assert(is_member(nlpt), "nested loop");
1663 Node* tail = nlpt->_tail;
1664 if (tail->in(0)->is_If()) tail = tail->in(0);
1665 if (n == tail) {
1666 // If inner loop has call on dom-path, so does outer loop
1667 if (nlpt->_has_sfpt) {
1668 has_call = true;
1669 _has_sfpt = 1;
1670 break;
1671 }
1672 // Skip to head of inner loop
1673 assert(_phase->is_dominator(_head, nlpt->_head), "inner head dominated by outer head");
1674 n = nlpt->_head;
1675 }
1676 }
1677 }
1678 }
1679 // Record safept's that this loop needs preserved when an
1680 // inner loop attempts to delete it's safepoints.
1681 if (_child != NULL && !has_call && !has_local_ncsfpt) {
1682 if (nonlocal_ncsfpt != NULL) {
1683 if (_required_safept == NULL) _required_safept = new Node_List();
1684 _required_safept->push(nonlocal_ncsfpt);
1685 } else {
1686 // Failed to find a suitable safept on the dom-path. Now use
1687 // an all paths walk from tail to head, looking for safepoints to preserve.
1688 allpaths_check_safepts(visited, stack);
1689 }
1690 }
1691 }
1692 }
1693
1694 //---------------------------is_deleteable_safept----------------------------
1695 // Is safept not required by an outer loop?
1696 bool PhaseIdealLoop::is_deleteable_safept(Node* sfpt) {
1697 assert(sfpt->Opcode() == Op_SafePoint, "");
1698 IdealLoopTree* lp = get_loop(sfpt)->_parent;
1699 while (lp != NULL) {
1700 Node_List* sfpts = lp->_required_safept;
1701 if (sfpts != NULL) {
1702 for (uint i = 0; i < sfpts->size(); i++) {
1703 if (sfpt == sfpts->at(i))
1704 return false;
1705 }
1706 }
1707 lp = lp->_parent;
1708 }
1709 return true;
1710 }
1711
1712 //---------------------------replace_parallel_iv-------------------------------
1713 // Replace parallel induction variable (parallel to trip counter)
1714 void PhaseIdealLoop::replace_parallel_iv(IdealLoopTree *loop) {
1715 assert(loop->_head->is_CountedLoop(), "");
1716 CountedLoopNode *cl = loop->_head->as_CountedLoop();
1717 if (!cl->is_valid_counted_loop())
1718 return; // skip malformed counted loop
1719 Node *incr = cl->incr();
1720 if (incr == NULL)
1721 return; // Dead loop?
1722 Node *init = cl->init_trip();
1723 Node *phi = cl->phi();
1724 int stride_con = cl->stride_con();
1725
1726 // Visit all children, looking for Phis
1727 for (DUIterator i = cl->outs(); cl->has_out(i); i++) {
1728 Node *out = cl->out(i);
1729 // Look for other phis (secondary IVs). Skip dead ones
1730 if (!out->is_Phi() || out == phi || !has_node(out))
1731 continue;
1732 PhiNode* phi2 = out->as_Phi();
1733 Node *incr2 = phi2->in( LoopNode::LoopBackControl );
1734 // Look for induction variables of the form: X += constant
1735 if (phi2->region() != loop->_head ||
1736 incr2->req() != 3 ||
1737 incr2->in(1) != phi2 ||
1738 incr2 == incr ||
1739 incr2->Opcode() != Op_AddI ||
1740 !incr2->in(2)->is_Con())
1741 continue;
1742
1743 // Check for parallel induction variable (parallel to trip counter)
1744 // via an affine function. In particular, count-down loops with
1745 // count-up array indices are common. We only RCE references off
1746 // the trip-counter, so we need to convert all these to trip-counter
1747 // expressions.
1748 Node *init2 = phi2->in( LoopNode::EntryControl );
1749 int stride_con2 = incr2->in(2)->get_int();
1750
1751 // The general case here gets a little tricky. We want to find the
1752 // GCD of all possible parallel IV's and make a new IV using this
1753 // GCD for the loop. Then all possible IVs are simple multiples of
1754 // the GCD. In practice, this will cover very few extra loops.
1755 // Instead we require 'stride_con2' to be a multiple of 'stride_con',
1756 // where +/-1 is the common case, but other integer multiples are
1757 // also easy to handle.
1758 int ratio_con = stride_con2/stride_con;
1759
1760 if ((ratio_con * stride_con) == stride_con2) { // Check for exact
1761 #ifndef PRODUCT
1762 if (TraceLoopOpts) {
1763 tty->print("Parallel IV: %d ", phi2->_idx);
1764 loop->dump_head();
1765 }
1766 #endif
1767 // Convert to using the trip counter. The parallel induction
1768 // variable differs from the trip counter by a loop-invariant
1769 // amount, the difference between their respective initial values.
1770 // It is scaled by the 'ratio_con'.
1771 Node* ratio = _igvn.intcon(ratio_con);
1772 set_ctrl(ratio, C->root());
1773 Node* ratio_init = new (C) MulINode(init, ratio);
1774 _igvn.register_new_node_with_optimizer(ratio_init, init);
1775 set_early_ctrl(ratio_init);
1776 Node* diff = new (C) SubINode(init2, ratio_init);
1777 _igvn.register_new_node_with_optimizer(diff, init2);
1778 set_early_ctrl(diff);
1779 Node* ratio_idx = new (C) MulINode(phi, ratio);
1780 _igvn.register_new_node_with_optimizer(ratio_idx, phi);
1781 set_ctrl(ratio_idx, cl);
1782 Node* add = new (C) AddINode(ratio_idx, diff);
1783 _igvn.register_new_node_with_optimizer(add);
1784 set_ctrl(add, cl);
1785 _igvn.replace_node( phi2, add );
1786 // Sometimes an induction variable is unused
1787 if (add->outcnt() == 0) {
1788 _igvn.remove_dead_node(add);
1789 }
1790 --i; // deleted this phi; rescan starting with next position
1791 continue;
1792 }
1793 }
1794 }
1795
1796 //------------------------------counted_loop-----------------------------------
1797 // Convert to counted loops where possible
1798 void IdealLoopTree::counted_loop( PhaseIdealLoop *phase ) {
1799
1800 // For grins, set the inner-loop flag here
1801 if (!_child) {
1802 if (_head->is_Loop()) _head->as_Loop()->set_inner_loop();
1803 }
1804
1805 if (_head->is_CountedLoop() ||
1806 phase->is_counted_loop(_head, this)) {
1807 _has_sfpt = 1; // Indicate we do not need a safepoint here
1808
1809 // Look for safepoints to remove.
1810 Node_List* sfpts = _safepts;
1811 if (sfpts != NULL) {
1812 for (uint i = 0; i < sfpts->size(); i++) {
1813 Node* n = sfpts->at(i);
1814 assert(phase->get_loop(n) == this, "");
1815 if (phase->is_deleteable_safept(n)) {
1816 phase->lazy_replace(n, n->in(TypeFunc::Control));
1817 }
1818 }
1819 }
1820
1821 // Look for induction variables
1822 phase->replace_parallel_iv(this);
1823
1824 } else if (_parent != NULL && !_irreducible) {
1825 // Not a counted loop.
1826 // Look for a safepoint on the idom-path.
1827 Node* sfpt = tail();
1828 for (; sfpt != _head; sfpt = phase->idom(sfpt)) {
1829 if (sfpt->Opcode() == Op_SafePoint && phase->get_loop(sfpt) == this)
1830 break; // Found one
1831 }
1832 // Delete other safepoints in this loop.
1833 Node_List* sfpts = _safepts;
1834 if (sfpts != NULL && sfpt != _head && sfpt->Opcode() == Op_SafePoint) {
1835 for (uint i = 0; i < sfpts->size(); i++) {
1836 Node* n = sfpts->at(i);
1837 assert(phase->get_loop(n) == this, "");
1838 if (n != sfpt && phase->is_deleteable_safept(n)) {
1839 phase->lazy_replace(n, n->in(TypeFunc::Control));
1840 }
1841 }
1842 }
1843 }
1844
1845 // Recursively
1846 if (_child) _child->counted_loop( phase );
1847 if (_next) _next ->counted_loop( phase );
1848 }
1849
1850 #ifndef PRODUCT
1851 //------------------------------dump_head--------------------------------------
1852 // Dump 1 liner for loop header info
1853 void IdealLoopTree::dump_head( ) const {
1854 for (uint i=0; i<_nest; i++)
1855 tty->print(" ");
1856 tty->print("Loop: N%d/N%d ",_head->_idx,_tail->_idx);
1857 if (_irreducible) tty->print(" IRREDUCIBLE");
1858 Node* entry = _head->in(LoopNode::EntryControl);
1859 if (LoopLimitCheck) {
1860 Node* predicate = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
1861 if (predicate != NULL ) {
1862 tty->print(" limit_check");
1863 entry = entry->in(0)->in(0);
1864 }
1865 }
1866 if (UseLoopPredicate) {
1867 entry = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
1868 if (entry != NULL) {
1869 tty->print(" predicated");
1870 }
1871 }
1872 if (_head->is_CountedLoop()) {
1873 CountedLoopNode *cl = _head->as_CountedLoop();
1874 tty->print(" counted");
1875
1876 Node* init_n = cl->init_trip();
1877 if (init_n != NULL && init_n->is_Con())
1878 tty->print(" [%d,", cl->init_trip()->get_int());
1879 else
1880 tty->print(" [int,");
1881 Node* limit_n = cl->limit();
1882 if (limit_n != NULL && limit_n->is_Con())
1883 tty->print("%d),", cl->limit()->get_int());
1884 else
1885 tty->print("int),");
1886 int stride_con = cl->stride_con();
1887 if (stride_con > 0) tty->print("+");
1888 tty->print("%d", stride_con);
1889
1890 tty->print(" (%d iters) ", (int)cl->profile_trip_cnt());
1891
1892 if (cl->is_pre_loop ()) tty->print(" pre" );
1893 if (cl->is_main_loop()) tty->print(" main");
1894 if (cl->is_post_loop()) tty->print(" post");
1895 }
1896 tty->cr();
1897 }
1898
1899 //------------------------------dump-------------------------------------------
1900 // Dump loops by loop tree
1901 void IdealLoopTree::dump( ) const {
1902 dump_head();
1903 if (_child) _child->dump();
1904 if (_next) _next ->dump();
1905 }
1906
1907 #endif
1908
1909 static void log_loop_tree(IdealLoopTree* root, IdealLoopTree* loop, CompileLog* log) {
1910 if (loop == root) {
1911 if (loop->_child != NULL) {
1912 log->begin_head("loop_tree");
1913 log->end_head();
1914 if( loop->_child ) log_loop_tree(root, loop->_child, log);
1915 log->tail("loop_tree");
1916 assert(loop->_next == NULL, "what?");
1917 }
1918 } else {
1919 Node* head = loop->_head;
1920 log->begin_head("loop");
1921 log->print(" idx='%d' ", head->_idx);
1922 if (loop->_irreducible) log->print("irreducible='1' ");
1923 if (head->is_Loop()) {
1924 if (head->as_Loop()->is_inner_loop()) log->print("inner_loop='1' ");
1925 if (head->as_Loop()->is_partial_peel_loop()) log->print("partial_peel_loop='1' ");
1926 }
1927 if (head->is_CountedLoop()) {
1928 CountedLoopNode* cl = head->as_CountedLoop();
1929 if (cl->is_pre_loop()) log->print("pre_loop='%d' ", cl->main_idx());
1930 if (cl->is_main_loop()) log->print("main_loop='%d' ", cl->_idx);
1931 if (cl->is_post_loop()) log->print("post_loop='%d' ", cl->main_idx());
1932 }
1933 log->end_head();
1934 if( loop->_child ) log_loop_tree(root, loop->_child, log);
1935 log->tail("loop");
1936 if( loop->_next ) log_loop_tree(root, loop->_next, log);
1937 }
1938 }
1939
1940 //---------------------collect_potentially_useful_predicates-----------------------
1941 // Helper function to collect potentially useful predicates to prevent them from
1942 // being eliminated by PhaseIdealLoop::eliminate_useless_predicates
1943 void PhaseIdealLoop::collect_potentially_useful_predicates(
1944 IdealLoopTree * loop, Unique_Node_List &useful_predicates) {
1945 if (loop->_child) { // child
1946 collect_potentially_useful_predicates(loop->_child, useful_predicates);
1947 }
1948
1949 // self (only loops that we can apply loop predication may use their predicates)
1950 if (loop->_head->is_Loop() &&
1951 !loop->_irreducible &&
1952 !loop->tail()->is_top()) {
1953 LoopNode* lpn = loop->_head->as_Loop();
1954 Node* entry = lpn->in(LoopNode::EntryControl);
1955 Node* predicate_proj = find_predicate(entry); // loop_limit_check first
1956 if (predicate_proj != NULL ) { // right pattern that can be used by loop predication
1957 assert(entry->in(0)->in(1)->in(1)->Opcode() == Op_Opaque1, "must be");
1958 useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one
1959 entry = entry->in(0)->in(0);
1960 }
1961 predicate_proj = find_predicate(entry); // Predicate
1962 if (predicate_proj != NULL ) {
1963 useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one
1964 }
1965 }
1966
1967 if (loop->_next) { // sibling
1968 collect_potentially_useful_predicates(loop->_next, useful_predicates);
1969 }
1970 }
1971
1972 //------------------------eliminate_useless_predicates-----------------------------
1973 // Eliminate all inserted predicates if they could not be used by loop predication.
1974 // Note: it will also eliminates loop limits check predicate since it also uses
1975 // Opaque1 node (see Parse::add_predicate()).
1976 void PhaseIdealLoop::eliminate_useless_predicates() {
1977 if (C->predicate_count() == 0)
1978 return; // no predicate left
1979
1980 Unique_Node_List useful_predicates; // to store useful predicates
1981 if (C->has_loops()) {
1982 collect_potentially_useful_predicates(_ltree_root->_child, useful_predicates);
1983 }
1984
1985 for (int i = C->predicate_count(); i > 0; i--) {
1986 Node * n = C->predicate_opaque1_node(i-1);
1987 assert(n->Opcode() == Op_Opaque1, "must be");
1988 if (!useful_predicates.member(n)) { // not in the useful list
1989 _igvn.replace_node(n, n->in(1));
1990 }
1991 }
1992 }
1993
1994 //------------------------process_expensive_nodes-----------------------------
1995 // Expensive nodes have their control input set to prevent the GVN
1996 // from commoning them and as a result forcing the resulting node to
1997 // be in a more frequent path. Use CFG information here, to change the
1998 // control inputs so that some expensive nodes can be commoned while
1999 // not executed more frequently.
2000 bool PhaseIdealLoop::process_expensive_nodes() {
2001 assert(OptimizeExpensiveOps, "optimization off?");
2002
2003 // Sort nodes to bring similar nodes together
2004 C->sort_expensive_nodes();
2005
2006 bool progress = false;
2007
2008 for (int i = 0; i < C->expensive_count(); ) {
2009 Node* n = C->expensive_node(i);
2010 int start = i;
2011 // Find nodes similar to n
2012 i++;
2013 for (; i < C->expensive_count() && Compile::cmp_expensive_nodes(n, C->expensive_node(i)) == 0; i++);
2014 int end = i;
2015 // And compare them two by two
2016 for (int j = start; j < end; j++) {
2017 Node* n1 = C->expensive_node(j);
2018 if (is_node_unreachable(n1)) {
2019 continue;
2020 }
2021 for (int k = j+1; k < end; k++) {
2022 Node* n2 = C->expensive_node(k);
2023 if (is_node_unreachable(n2)) {
2024 continue;
2025 }
2026
2027 assert(n1 != n2, "should be pair of nodes");
2028
2029 Node* c1 = n1->in(0);
2030 Node* c2 = n2->in(0);
2031
2032 Node* parent_c1 = c1;
2033 Node* parent_c2 = c2;
2034
2035 // The call to get_early_ctrl_for_expensive() moves the
2036 // expensive nodes up but stops at loops that are in a if
2037 // branch. See whether we can exit the loop and move above the
2038 // If.
2039 if (c1->is_Loop()) {
2040 parent_c1 = c1->in(1);
2041 }
2042 if (c2->is_Loop()) {
2043 parent_c2 = c2->in(1);
2044 }
2045
2046 if (parent_c1 == parent_c2) {
2047 _igvn._worklist.push(n1);
2048 _igvn._worklist.push(n2);
2049 continue;
2050 }
2051
2052 // Look for identical expensive node up the dominator chain.
2053 if (is_dominator(c1, c2)) {
2054 c2 = c1;
2055 } else if (is_dominator(c2, c1)) {
2056 c1 = c2;
2057 } else if (parent_c1->is_Proj() && parent_c1->in(0)->is_If() &&
2058 parent_c2->is_Proj() && parent_c1->in(0) == parent_c2->in(0)) {
2059 // Both branches have the same expensive node so move it up
2060 // before the if.
2061 c1 = c2 = idom(parent_c1->in(0));
2062 }
2063 // Do the actual moves
2064 if (n1->in(0) != c1) {
2065 _igvn.hash_delete(n1);
2066 n1->set_req(0, c1);
2067 _igvn.hash_insert(n1);
2068 _igvn._worklist.push(n1);
2069 progress = true;
2070 }
2071 if (n2->in(0) != c2) {
2072 _igvn.hash_delete(n2);
2073 n2->set_req(0, c2);
2074 _igvn.hash_insert(n2);
2075 _igvn._worklist.push(n2);
2076 progress = true;
2077 }
2078 }
2079 }
2080 }
2081
2082 return progress;
2083 }
2084
2085
2086 //=============================================================================
2087 //----------------------------build_and_optimize-------------------------------
2088 // Create a PhaseLoop. Build the ideal Loop tree. Map each Ideal Node to
2089 // its corresponding LoopNode. If 'optimize' is true, do some loop cleanups.
2090 void PhaseIdealLoop::build_and_optimize(bool do_split_ifs, bool skip_loop_opts) {
2091 ResourceMark rm;
2092
2093 int old_progress = C->major_progress();
2094 uint orig_worklist_size = _igvn._worklist.size();
2095
2096 // Reset major-progress flag for the driver's heuristics
2097 C->clear_major_progress();
2098
2099 #ifndef PRODUCT
2100 // Capture for later assert
2101 uint unique = C->unique();
2102 _loop_invokes++;
2103 _loop_work += unique;
2104 #endif
2105
2106 // True if the method has at least 1 irreducible loop
2107 _has_irreducible_loops = false;
2108
2109 _created_loop_node = false;
2110
2111 Arena *a = Thread::current()->resource_area();
2112 VectorSet visited(a);
2113 // Pre-grow the mapping from Nodes to IdealLoopTrees.
2114 _nodes.map(C->unique(), NULL);
2115 memset(_nodes.adr(), 0, wordSize * C->unique());
2116
2117 // Pre-build the top-level outermost loop tree entry
2118 _ltree_root = new IdealLoopTree( this, C->root(), C->root() );
2119 // Do not need a safepoint at the top level
2120 _ltree_root->_has_sfpt = 1;
2121
2122 // Initialize Dominators.
2123 // Checked in clone_loop_predicate() during beautify_loops().
2124 _idom_size = 0;
2125 _idom = NULL;
2126 _dom_depth = NULL;
2127 _dom_stk = NULL;
2128
2129 // Empty pre-order array
2130 allocate_preorders();
2131
2132 // Build a loop tree on the fly. Build a mapping from CFG nodes to
2133 // IdealLoopTree entries. Data nodes are NOT walked.
2134 build_loop_tree();
2135 // Check for bailout, and return
2136 if (C->failing()) {
2137 return;
2138 }
2139
2140 // No loops after all
2141 if( !_ltree_root->_child && !_verify_only ) C->set_has_loops(false);
2142
2143 // There should always be an outer loop containing the Root and Return nodes.
2144 // If not, we have a degenerate empty program. Bail out in this case.
2145 if (!has_node(C->root())) {
2146 if (!_verify_only) {
2147 C->clear_major_progress();
2148 C->record_method_not_compilable("empty program detected during loop optimization");
2149 }
2150 return;
2151 }
2152
2153 // Nothing to do, so get out
2154 bool stop_early = !C->has_loops() && !skip_loop_opts && !do_split_ifs && !_verify_me && !_verify_only;
2155 bool do_expensive_nodes = C->should_optimize_expensive_nodes(_igvn);
2156 if (stop_early && !do_expensive_nodes) {
2157 _igvn.optimize(); // Cleanup NeverBranches
2158 return;
2159 }
2160
2161 // Set loop nesting depth
2162 _ltree_root->set_nest( 0 );
2163
2164 // Split shared headers and insert loop landing pads.
2165 // Do not bother doing this on the Root loop of course.
2166 if( !_verify_me && !_verify_only && _ltree_root->_child ) {
2167 C->print_method(PHASE_BEFORE_BEAUTIFY_LOOPS, 3);
2168 if( _ltree_root->_child->beautify_loops( this ) ) {
2169 // Re-build loop tree!
2170 _ltree_root->_child = NULL;
2171 _nodes.clear();
2172 reallocate_preorders();
2173 build_loop_tree();
2174 // Check for bailout, and return
2175 if (C->failing()) {
2176 return;
2177 }
2178 // Reset loop nesting depth
2179 _ltree_root->set_nest( 0 );
2180
2181 C->print_method(PHASE_AFTER_BEAUTIFY_LOOPS, 3);
2182 }
2183 }
2184
2185 // Build Dominators for elision of NULL checks & loop finding.
2186 // Since nodes do not have a slot for immediate dominator, make
2187 // a persistent side array for that info indexed on node->_idx.
2188 _idom_size = C->unique();
2189 _idom = NEW_RESOURCE_ARRAY( Node*, _idom_size );
2190 _dom_depth = NEW_RESOURCE_ARRAY( uint, _idom_size );
2191 _dom_stk = NULL; // Allocated on demand in recompute_dom_depth
2192 memset( _dom_depth, 0, _idom_size * sizeof(uint) );
2193
2194 Dominators();
2195
2196 if (!_verify_only) {
2197 // As a side effect, Dominators removed any unreachable CFG paths
2198 // into RegionNodes. It doesn't do this test against Root, so
2199 // we do it here.
2200 for( uint i = 1; i < C->root()->req(); i++ ) {
2201 if( !_nodes[C->root()->in(i)->_idx] ) { // Dead path into Root?
2202 _igvn.delete_input_of(C->root(), i);
2203 i--; // Rerun same iteration on compressed edges
2204 }
2205 }
2206
2207 // Given dominators, try to find inner loops with calls that must
2208 // always be executed (call dominates loop tail). These loops do
2209 // not need a separate safepoint.
2210 Node_List cisstack(a);
2211 _ltree_root->check_safepts(visited, cisstack);
2212 }
2213
2214 // Walk the DATA nodes and place into loops. Find earliest control
2215 // node. For CFG nodes, the _nodes array starts out and remains
2216 // holding the associated IdealLoopTree pointer. For DATA nodes, the
2217 // _nodes array holds the earliest legal controlling CFG node.
2218
2219 // Allocate stack with enough space to avoid frequent realloc
2220 int stack_size = (C->unique() >> 1) + 16; // (unique>>1)+16 from Java2D stats
2221 Node_Stack nstack( a, stack_size );
2222
2223 visited.Clear();
2224 Node_List worklist(a);
2225 // Don't need C->root() on worklist since
2226 // it will be processed among C->top() inputs
2227 worklist.push( C->top() );
2228 visited.set( C->top()->_idx ); // Set C->top() as visited now
2229 build_loop_early( visited, worklist, nstack );
2230
2231 // Given early legal placement, try finding counted loops. This placement
2232 // is good enough to discover most loop invariants.
2233 if( !_verify_me && !_verify_only )
2234 _ltree_root->counted_loop( this );
2235
2236 // Find latest loop placement. Find ideal loop placement.
2237 visited.Clear();
2238 init_dom_lca_tags();
2239 // Need C->root() on worklist when processing outs
2240 worklist.push( C->root() );
2241 NOT_PRODUCT( C->verify_graph_edges(); )
2242 worklist.push( C->top() );
2243 build_loop_late( visited, worklist, nstack );
2244
2245 if (_verify_only) {
2246 // restore major progress flag
2247 for (int i = 0; i < old_progress; i++)
2248 C->set_major_progress();
2249 assert(C->unique() == unique, "verification mode made Nodes? ? ?");
2250 assert(_igvn._worklist.size() == orig_worklist_size, "shouldn't push anything");
2251 return;
2252 }
2253
2254 // clear out the dead code after build_loop_late
2255 while (_deadlist.size()) {
2256 _igvn.remove_globally_dead_node(_deadlist.pop());
2257 }
2258
2259 if (stop_early) {
2260 assert(do_expensive_nodes, "why are we here?");
2261 if (process_expensive_nodes()) {
2262 // If we made some progress when processing expensive nodes then
2263 // the IGVN may modify the graph in a way that will allow us to
2264 // make some more progress: we need to try processing expensive
2265 // nodes again.
2266 C->set_major_progress();
2267 }
2268 _igvn.optimize();
2269 return;
2270 }
2271
2272 // Some parser-inserted loop predicates could never be used by loop
2273 // predication or they were moved away from loop during some optimizations.
2274 // For example, peeling. Eliminate them before next loop optimizations.
2275 if (UseLoopPredicate || LoopLimitCheck) {
2276 eliminate_useless_predicates();
2277 }
2278
2279 #ifndef PRODUCT
2280 C->verify_graph_edges();
2281 if (_verify_me) { // Nested verify pass?
2282 // Check to see if the verify mode is broken
2283 assert(C->unique() == unique, "non-optimize mode made Nodes? ? ?");
2284 return;
2285 }
2286 if(VerifyLoopOptimizations) verify();
2287 if(TraceLoopOpts && C->has_loops()) {
2288 _ltree_root->dump();
2289 }
2290 #endif
2291
2292 if (skip_loop_opts) {
2293 // Cleanup any modified bits
2294 _igvn.optimize();
2295
2296 if (C->log() != NULL) {
2297 log_loop_tree(_ltree_root, _ltree_root, C->log());
2298 }
2299 return;
2300 }
2301
2302 if (ReassociateInvariants) {
2303 // Reassociate invariants and prep for split_thru_phi
2304 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
2305 IdealLoopTree* lpt = iter.current();
2306 if (!lpt->is_counted() || !lpt->is_inner()) continue;
2307
2308 lpt->reassociate_invariants(this);
2309
2310 // Because RCE opportunities can be masked by split_thru_phi,
2311 // look for RCE candidates and inhibit split_thru_phi
2312 // on just their loop-phi's for this pass of loop opts
2313 if (SplitIfBlocks && do_split_ifs) {
2314 if (lpt->policy_range_check(this)) {
2315 lpt->_rce_candidate = 1; // = true
2316 }
2317 }
2318 }
2319 }
2320
2321 // Check for aggressive application of split-if and other transforms
2322 // that require basic-block info (like cloning through Phi's)
2323 if( SplitIfBlocks && do_split_ifs ) {
2324 visited.Clear();
2325 split_if_with_blocks( visited, nstack );
2326 NOT_PRODUCT( if( VerifyLoopOptimizations ) verify(); );
2327 }
2328
2329 if (!C->major_progress() && do_expensive_nodes && process_expensive_nodes()) {
2330 C->set_major_progress();
2331 }
2332
2333 // Perform loop predication before iteration splitting
2334 if (C->has_loops() && !C->major_progress() && (C->predicate_count() > 0)) {
2335 _ltree_root->_child->loop_predication(this);
2336 }
2337
2338 if (OptimizeFill && UseLoopPredicate && C->has_loops() && !C->major_progress()) {
2339 if (do_intrinsify_fill()) {
2340 C->set_major_progress();
2341 }
2342 }
2343
2344 // Perform iteration-splitting on inner loops. Split iterations to avoid
2345 // range checks or one-shot null checks.
2346
2347 // If split-if's didn't hack the graph too bad (no CFG changes)
2348 // then do loop opts.
2349 if (C->has_loops() && !C->major_progress()) {
2350 memset( worklist.adr(), 0, worklist.Size()*sizeof(Node*) );
2351 _ltree_root->_child->iteration_split( this, worklist );
2352 // No verify after peeling! GCM has hoisted code out of the loop.
2353 // After peeling, the hoisted code could sink inside the peeled area.
2354 // The peeling code does not try to recompute the best location for
2355 // all the code before the peeled area, so the verify pass will always
2356 // complain about it.
2357 }
2358 // Do verify graph edges in any case
2359 NOT_PRODUCT( C->verify_graph_edges(); );
2360
2361 if (!do_split_ifs) {
2362 // We saw major progress in Split-If to get here. We forced a
2363 // pass with unrolling and not split-if, however more split-if's
2364 // might make progress. If the unrolling didn't make progress
2365 // then the major-progress flag got cleared and we won't try
2366 // another round of Split-If. In particular the ever-common
2367 // instance-of/check-cast pattern requires at least 2 rounds of
2368 // Split-If to clear out.
2369 C->set_major_progress();
2370 }
2371
2372 // Repeat loop optimizations if new loops were seen
2373 if (created_loop_node()) {
2374 C->set_major_progress();
2375 }
2376
2377 // Keep loop predicates and perform optimizations with them
2378 // until no more loop optimizations could be done.
2379 // After that switch predicates off and do more loop optimizations.
2380 if (!C->major_progress() && (C->predicate_count() > 0)) {
2381 C->cleanup_loop_predicates(_igvn);
2382 #ifndef PRODUCT
2383 if (TraceLoopOpts) {
2384 tty->print_cr("PredicatesOff");
2385 }
2386 #endif
2387 C->set_major_progress();
2388 }
2389
2390 // Convert scalar to superword operations at the end of all loop opts.
2391 if (UseSuperWord && C->has_loops() && !C->major_progress()) {
2392 // SuperWord transform
2393 SuperWord sw(this);
2394 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
2395 IdealLoopTree* lpt = iter.current();
2396 if (lpt->is_counted()) {
2397 sw.transform_loop(lpt);
2398 }
2399 }
2400 }
2401
2402 // Cleanup any modified bits
2403 _igvn.optimize();
2404
2405 // disable assert until issue with split_flow_path is resolved (6742111)
2406 // assert(!_has_irreducible_loops || C->parsed_irreducible_loop() || C->is_osr_compilation(),
2407 // "shouldn't introduce irreducible loops");
2408
2409 if (C->log() != NULL) {
2410 log_loop_tree(_ltree_root, _ltree_root, C->log());
2411 }
2412 }
2413
2414 #ifndef PRODUCT
2415 //------------------------------print_statistics-------------------------------
2416 int PhaseIdealLoop::_loop_invokes=0;// Count of PhaseIdealLoop invokes
2417 int PhaseIdealLoop::_loop_work=0; // Sum of PhaseIdealLoop x unique
2418 void PhaseIdealLoop::print_statistics() {
2419 tty->print_cr("PhaseIdealLoop=%d, sum _unique=%d", _loop_invokes, _loop_work);
2420 }
2421
2422 //------------------------------verify-----------------------------------------
2423 // Build a verify-only PhaseIdealLoop, and see that it agrees with me.
2424 static int fail; // debug only, so its multi-thread dont care
2425 void PhaseIdealLoop::verify() const {
2426 int old_progress = C->major_progress();
2427 ResourceMark rm;
2428 PhaseIdealLoop loop_verify( _igvn, this );
2429 VectorSet visited(Thread::current()->resource_area());
2430
2431 fail = 0;
2432 verify_compare( C->root(), &loop_verify, visited );
2433 assert( fail == 0, "verify loops failed" );
2434 // Verify loop structure is the same
2435 _ltree_root->verify_tree(loop_verify._ltree_root, NULL);
2436 // Reset major-progress. It was cleared by creating a verify version of
2437 // PhaseIdealLoop.
2438 for( int i=0; i<old_progress; i++ )
2439 C->set_major_progress();
2440 }
2441
2442 //------------------------------verify_compare---------------------------------
2443 // Make sure me and the given PhaseIdealLoop agree on key data structures
2444 void PhaseIdealLoop::verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const {
2445 if( !n ) return;
2446 if( visited.test_set( n->_idx ) ) return;
2447 if( !_nodes[n->_idx] ) { // Unreachable
2448 assert( !loop_verify->_nodes[n->_idx], "both should be unreachable" );
2449 return;
2450 }
2451
2452 uint i;
2453 for( i = 0; i < n->req(); i++ )
2454 verify_compare( n->in(i), loop_verify, visited );
2455
2456 // Check the '_nodes' block/loop structure
2457 i = n->_idx;
2458 if( has_ctrl(n) ) { // We have control; verify has loop or ctrl
2459 if( _nodes[i] != loop_verify->_nodes[i] &&
2460 get_ctrl_no_update(n) != loop_verify->get_ctrl_no_update(n) ) {
2461 tty->print("Mismatched control setting for: ");
2462 n->dump();
2463 if( fail++ > 10 ) return;
2464 Node *c = get_ctrl_no_update(n);
2465 tty->print("We have it as: ");
2466 if( c->in(0) ) c->dump();
2467 else tty->print_cr("N%d",c->_idx);
2468 tty->print("Verify thinks: ");
2469 if( loop_verify->has_ctrl(n) )
2470 loop_verify->get_ctrl_no_update(n)->dump();
2471 else
2472 loop_verify->get_loop_idx(n)->dump();
2473 tty->cr();
2474 }
2475 } else { // We have a loop
2476 IdealLoopTree *us = get_loop_idx(n);
2477 if( loop_verify->has_ctrl(n) ) {
2478 tty->print("Mismatched loop setting for: ");
2479 n->dump();
2480 if( fail++ > 10 ) return;
2481 tty->print("We have it as: ");
2482 us->dump();
2483 tty->print("Verify thinks: ");
2484 loop_verify->get_ctrl_no_update(n)->dump();
2485 tty->cr();
2486 } else if (!C->major_progress()) {
2487 // Loop selection can be messed up if we did a major progress
2488 // operation, like split-if. Do not verify in that case.
2489 IdealLoopTree *them = loop_verify->get_loop_idx(n);
2490 if( us->_head != them->_head || us->_tail != them->_tail ) {
2491 tty->print("Unequals loops for: ");
2492 n->dump();
2493 if( fail++ > 10 ) return;
2494 tty->print("We have it as: ");
2495 us->dump();
2496 tty->print("Verify thinks: ");
2497 them->dump();
2498 tty->cr();
2499 }
2500 }
2501 }
2502
2503 // Check for immediate dominators being equal
2504 if( i >= _idom_size ) {
2505 if( !n->is_CFG() ) return;
2506 tty->print("CFG Node with no idom: ");
2507 n->dump();
2508 return;
2509 }
2510 if( !n->is_CFG() ) return;
2511 if( n == C->root() ) return; // No IDOM here
2512
2513 assert(n->_idx == i, "sanity");
2514 Node *id = idom_no_update(n);
2515 if( id != loop_verify->idom_no_update(n) ) {
2516 tty->print("Unequals idoms for: ");
2517 n->dump();
2518 if( fail++ > 10 ) return;
2519 tty->print("We have it as: ");
2520 id->dump();
2521 tty->print("Verify thinks: ");
2522 loop_verify->idom_no_update(n)->dump();
2523 tty->cr();
2524 }
2525
2526 }
2527
2528 //------------------------------verify_tree------------------------------------
2529 // Verify that tree structures match. Because the CFG can change, siblings
2530 // within the loop tree can be reordered. We attempt to deal with that by
2531 // reordering the verify's loop tree if possible.
2532 void IdealLoopTree::verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const {
2533 assert( _parent == parent, "Badly formed loop tree" );
2534
2535 // Siblings not in same order? Attempt to re-order.
2536 if( _head != loop->_head ) {
2537 // Find _next pointer to update
2538 IdealLoopTree **pp = &loop->_parent->_child;
2539 while( *pp != loop )
2540 pp = &((*pp)->_next);
2541 // Find proper sibling to be next
2542 IdealLoopTree **nn = &loop->_next;
2543 while( (*nn) && (*nn)->_head != _head )
2544 nn = &((*nn)->_next);
2545
2546 // Check for no match.
2547 if( !(*nn) ) {
2548 // Annoyingly, irreducible loops can pick different headers
2549 // after a major_progress operation, so the rest of the loop
2550 // tree cannot be matched.
2551 if (_irreducible && Compile::current()->major_progress()) return;
2552 assert( 0, "failed to match loop tree" );
2553 }
2554
2555 // Move (*nn) to (*pp)
2556 IdealLoopTree *hit = *nn;
2557 *nn = hit->_next;
2558 hit->_next = loop;
2559 *pp = loop;
2560 loop = hit;
2561 // Now try again to verify
2562 }
2563
2564 assert( _head == loop->_head , "mismatched loop head" );
2565 Node *tail = _tail; // Inline a non-updating version of
2566 while( !tail->in(0) ) // the 'tail()' call.
2567 tail = tail->in(1);
2568 assert( tail == loop->_tail, "mismatched loop tail" );
2569
2570 // Counted loops that are guarded should be able to find their guards
2571 if( _head->is_CountedLoop() && _head->as_CountedLoop()->is_main_loop() ) {
2572 CountedLoopNode *cl = _head->as_CountedLoop();
2573 Node *init = cl->init_trip();
2574 Node *ctrl = cl->in(LoopNode::EntryControl);
2575 assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" );
2576 Node *iff = ctrl->in(0);
2577 assert( iff->Opcode() == Op_If, "" );
2578 Node *bol = iff->in(1);
2579 assert( bol->Opcode() == Op_Bool, "" );
2580 Node *cmp = bol->in(1);
2581 assert( cmp->Opcode() == Op_CmpI, "" );
2582 Node *add = cmp->in(1);
2583 Node *opaq;
2584 if( add->Opcode() == Op_Opaque1 ) {
2585 opaq = add;
2586 } else {
2587 assert( add->Opcode() == Op_AddI || add->Opcode() == Op_ConI , "" );
2588 assert( add == init, "" );
2589 opaq = cmp->in(2);
2590 }
2591 assert( opaq->Opcode() == Op_Opaque1, "" );
2592
2593 }
2594
2595 if (_child != NULL) _child->verify_tree(loop->_child, this);
2596 if (_next != NULL) _next ->verify_tree(loop->_next, parent);
2597 // Innermost loops need to verify loop bodies,
2598 // but only if no 'major_progress'
2599 int fail = 0;
2600 if (!Compile::current()->major_progress() && _child == NULL) {
2601 for( uint i = 0; i < _body.size(); i++ ) {
2602 Node *n = _body.at(i);
2603 if (n->outcnt() == 0) continue; // Ignore dead
2604 uint j;
2605 for( j = 0; j < loop->_body.size(); j++ )
2606 if( loop->_body.at(j) == n )
2607 break;
2608 if( j == loop->_body.size() ) { // Not found in loop body
2609 // Last ditch effort to avoid assertion: Its possible that we
2610 // have some users (so outcnt not zero) but are still dead.
2611 // Try to find from root.
2612 if (Compile::current()->root()->find(n->_idx)) {
2613 fail++;
2614 tty->print("We have that verify does not: ");
2615 n->dump();
2616 }
2617 }
2618 }
2619 for( uint i2 = 0; i2 < loop->_body.size(); i2++ ) {
2620 Node *n = loop->_body.at(i2);
2621 if (n->outcnt() == 0) continue; // Ignore dead
2622 uint j;
2623 for( j = 0; j < _body.size(); j++ )
2624 if( _body.at(j) == n )
2625 break;
2626 if( j == _body.size() ) { // Not found in loop body
2627 // Last ditch effort to avoid assertion: Its possible that we
2628 // have some users (so outcnt not zero) but are still dead.
2629 // Try to find from root.
2630 if (Compile::current()->root()->find(n->_idx)) {
2631 fail++;
2632 tty->print("Verify has that we do not: ");
2633 n->dump();
2634 }
2635 }
2636 }
2637 assert( !fail, "loop body mismatch" );
2638 }
2639 }
2640
2641 #endif
2642
2643 //------------------------------set_idom---------------------------------------
2644 void PhaseIdealLoop::set_idom(Node* d, Node* n, uint dom_depth) {
2645 uint idx = d->_idx;
2646 if (idx >= _idom_size) {
2647 uint newsize = _idom_size<<1;
2648 while( idx >= newsize ) {
2649 newsize <<= 1;
2650 }
2651 _idom = REALLOC_RESOURCE_ARRAY( Node*, _idom,_idom_size,newsize);
2652 _dom_depth = REALLOC_RESOURCE_ARRAY( uint, _dom_depth,_idom_size,newsize);
2653 memset( _dom_depth + _idom_size, 0, (newsize - _idom_size) * sizeof(uint) );
2654 _idom_size = newsize;
2655 }
2656 _idom[idx] = n;
2657 _dom_depth[idx] = dom_depth;
2658 }
2659
2660 //------------------------------recompute_dom_depth---------------------------------------
2661 // The dominator tree is constructed with only parent pointers.
2662 // This recomputes the depth in the tree by first tagging all
2663 // nodes as "no depth yet" marker. The next pass then runs up
2664 // the dom tree from each node marked "no depth yet", and computes
2665 // the depth on the way back down.
2666 void PhaseIdealLoop::recompute_dom_depth() {
2667 uint no_depth_marker = C->unique();
2668 uint i;
2669 // Initialize depth to "no depth yet"
2670 for (i = 0; i < _idom_size; i++) {
2671 if (_dom_depth[i] > 0 && _idom[i] != NULL) {
2672 _dom_depth[i] = no_depth_marker;
2673 }
2674 }
2675 if (_dom_stk == NULL) {
2676 uint init_size = C->unique() / 100; // Guess that 1/100 is a reasonable initial size.
2677 if (init_size < 10) init_size = 10;
2678 _dom_stk = new GrowableArray<uint>(init_size);
2679 }
2680 // Compute new depth for each node.
2681 for (i = 0; i < _idom_size; i++) {
2682 uint j = i;
2683 // Run up the dom tree to find a node with a depth
2684 while (_dom_depth[j] == no_depth_marker) {
2685 _dom_stk->push(j);
2686 j = _idom[j]->_idx;
2687 }
2688 // Compute the depth on the way back down this tree branch
2689 uint dd = _dom_depth[j] + 1;
2690 while (_dom_stk->length() > 0) {
2691 uint j = _dom_stk->pop();
2692 _dom_depth[j] = dd;
2693 dd++;
2694 }
2695 }
2696 }
2697
2698 //------------------------------sort-------------------------------------------
2699 // Insert 'loop' into the existing loop tree. 'innermost' is a leaf of the
2700 // loop tree, not the root.
2701 IdealLoopTree *PhaseIdealLoop::sort( IdealLoopTree *loop, IdealLoopTree *innermost ) {
2702 if( !innermost ) return loop; // New innermost loop
2703
2704 int loop_preorder = get_preorder(loop->_head); // Cache pre-order number
2705 assert( loop_preorder, "not yet post-walked loop" );
2706 IdealLoopTree **pp = &innermost; // Pointer to previous next-pointer
2707 IdealLoopTree *l = *pp; // Do I go before or after 'l'?
2708
2709 // Insert at start of list
2710 while( l ) { // Insertion sort based on pre-order
2711 if( l == loop ) return innermost; // Already on list!
2712 int l_preorder = get_preorder(l->_head); // Cache pre-order number
2713 assert( l_preorder, "not yet post-walked l" );
2714 // Check header pre-order number to figure proper nesting
2715 if( loop_preorder > l_preorder )
2716 break; // End of insertion
2717 // If headers tie (e.g., shared headers) check tail pre-order numbers.
2718 // Since I split shared headers, you'd think this could not happen.
2719 // BUT: I must first do the preorder numbering before I can discover I
2720 // have shared headers, so the split headers all get the same preorder
2721 // number as the RegionNode they split from.
2722 if( loop_preorder == l_preorder &&
2723 get_preorder(loop->_tail) < get_preorder(l->_tail) )
2724 break; // Also check for shared headers (same pre#)
2725 pp = &l->_parent; // Chain up list
2726 l = *pp;
2727 }
2728 // Link into list
2729 // Point predecessor to me
2730 *pp = loop;
2731 // Point me to successor
2732 IdealLoopTree *p = loop->_parent;
2733 loop->_parent = l; // Point me to successor
2734 if( p ) sort( p, innermost ); // Insert my parents into list as well
2735 return innermost;
2736 }
2737
2738 //------------------------------build_loop_tree--------------------------------
2739 // I use a modified Vick/Tarjan algorithm. I need pre- and a post- visit
2740 // bits. The _nodes[] array is mapped by Node index and holds a NULL for
2741 // not-yet-pre-walked, pre-order # for pre-but-not-post-walked and holds the
2742 // tightest enclosing IdealLoopTree for post-walked.
2743 //
2744 // During my forward walk I do a short 1-layer lookahead to see if I can find
2745 // a loop backedge with that doesn't have any work on the backedge. This
2746 // helps me construct nested loops with shared headers better.
2747 //
2748 // Once I've done the forward recursion, I do the post-work. For each child
2749 // I check to see if there is a backedge. Backedges define a loop! I
2750 // insert an IdealLoopTree at the target of the backedge.
2751 //
2752 // During the post-work I also check to see if I have several children
2753 // belonging to different loops. If so, then this Node is a decision point
2754 // where control flow can choose to change loop nests. It is at this
2755 // decision point where I can figure out how loops are nested. At this
2756 // time I can properly order the different loop nests from my children.
2757 // Note that there may not be any backedges at the decision point!
2758 //
2759 // Since the decision point can be far removed from the backedges, I can't
2760 // order my loops at the time I discover them. Thus at the decision point
2761 // I need to inspect loop header pre-order numbers to properly nest my
2762 // loops. This means I need to sort my childrens' loops by pre-order.
2763 // The sort is of size number-of-control-children, which generally limits
2764 // it to size 2 (i.e., I just choose between my 2 target loops).
2765 void PhaseIdealLoop::build_loop_tree() {
2766 // Allocate stack of size C->unique()/2 to avoid frequent realloc
2767 GrowableArray <Node *> bltstack(C->unique() >> 1);
2768 Node *n = C->root();
2769 bltstack.push(n);
2770 int pre_order = 1;
2771 int stack_size;
2772
2773 while ( ( stack_size = bltstack.length() ) != 0 ) {
2774 n = bltstack.top(); // Leave node on stack
2775 if ( !is_visited(n) ) {
2776 // ---- Pre-pass Work ----
2777 // Pre-walked but not post-walked nodes need a pre_order number.
2778
2779 set_preorder_visited( n, pre_order ); // set as visited
2780
2781 // ---- Scan over children ----
2782 // Scan first over control projections that lead to loop headers.
2783 // This helps us find inner-to-outer loops with shared headers better.
2784
2785 // Scan children's children for loop headers.
2786 for ( int i = n->outcnt() - 1; i >= 0; --i ) {
2787 Node* m = n->raw_out(i); // Child
2788 if( m->is_CFG() && !is_visited(m) ) { // Only for CFG children
2789 // Scan over children's children to find loop
2790 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
2791 Node* l = m->fast_out(j);
2792 if( is_visited(l) && // Been visited?
2793 !is_postvisited(l) && // But not post-visited
2794 get_preorder(l) < pre_order ) { // And smaller pre-order
2795 // Found! Scan the DFS down this path before doing other paths
2796 bltstack.push(m);
2797 break;
2798 }
2799 }
2800 }
2801 }
2802 pre_order++;
2803 }
2804 else if ( !is_postvisited(n) ) {
2805 // Note: build_loop_tree_impl() adds out edges on rare occasions,
2806 // such as com.sun.rsasign.am::a.
2807 // For non-recursive version, first, process current children.
2808 // On next iteration, check if additional children were added.
2809 for ( int k = n->outcnt() - 1; k >= 0; --k ) {
2810 Node* u = n->raw_out(k);
2811 if ( u->is_CFG() && !is_visited(u) ) {
2812 bltstack.push(u);
2813 }
2814 }
2815 if ( bltstack.length() == stack_size ) {
2816 // There were no additional children, post visit node now
2817 (void)bltstack.pop(); // Remove node from stack
2818 pre_order = build_loop_tree_impl( n, pre_order );
2819 // Check for bailout
2820 if (C->failing()) {
2821 return;
2822 }
2823 // Check to grow _preorders[] array for the case when
2824 // build_loop_tree_impl() adds new nodes.
2825 check_grow_preorders();
2826 }
2827 }
2828 else {
2829 (void)bltstack.pop(); // Remove post-visited node from stack
2830 }
2831 }
2832 }
2833
2834 //------------------------------build_loop_tree_impl---------------------------
2835 int PhaseIdealLoop::build_loop_tree_impl( Node *n, int pre_order ) {
2836 // ---- Post-pass Work ----
2837 // Pre-walked but not post-walked nodes need a pre_order number.
2838
2839 // Tightest enclosing loop for this Node
2840 IdealLoopTree *innermost = NULL;
2841
2842 // For all children, see if any edge is a backedge. If so, make a loop
2843 // for it. Then find the tightest enclosing loop for the self Node.
2844 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2845 Node* m = n->fast_out(i); // Child
2846 if( n == m ) continue; // Ignore control self-cycles
2847 if( !m->is_CFG() ) continue;// Ignore non-CFG edges
2848
2849 IdealLoopTree *l; // Child's loop
2850 if( !is_postvisited(m) ) { // Child visited but not post-visited?
2851 // Found a backedge
2852 assert( get_preorder(m) < pre_order, "should be backedge" );
2853 // Check for the RootNode, which is already a LoopNode and is allowed
2854 // to have multiple "backedges".
2855 if( m == C->root()) { // Found the root?
2856 l = _ltree_root; // Root is the outermost LoopNode
2857 } else { // Else found a nested loop
2858 // Insert a LoopNode to mark this loop.
2859 l = new IdealLoopTree(this, m, n);
2860 } // End of Else found a nested loop
2861 if( !has_loop(m) ) // If 'm' does not already have a loop set
2862 set_loop(m, l); // Set loop header to loop now
2863
2864 } else { // Else not a nested loop
2865 if( !_nodes[m->_idx] ) continue; // Dead code has no loop
2866 l = get_loop(m); // Get previously determined loop
2867 // If successor is header of a loop (nest), move up-loop till it
2868 // is a member of some outer enclosing loop. Since there are no
2869 // shared headers (I've split them already) I only need to go up
2870 // at most 1 level.
2871 while( l && l->_head == m ) // Successor heads loop?
2872 l = l->_parent; // Move up 1 for me
2873 // If this loop is not properly parented, then this loop
2874 // has no exit path out, i.e. its an infinite loop.
2875 if( !l ) {
2876 // Make loop "reachable" from root so the CFG is reachable. Basically
2877 // insert a bogus loop exit that is never taken. 'm', the loop head,
2878 // points to 'n', one (of possibly many) fall-in paths. There may be
2879 // many backedges as well.
2880
2881 // Here I set the loop to be the root loop. I could have, after
2882 // inserting a bogus loop exit, restarted the recursion and found my
2883 // new loop exit. This would make the infinite loop a first-class
2884 // loop and it would then get properly optimized. What's the use of
2885 // optimizing an infinite loop?
2886 l = _ltree_root; // Oops, found infinite loop
2887
2888 if (!_verify_only) {
2889 // Insert the NeverBranch between 'm' and it's control user.
2890 NeverBranchNode *iff = new (C) NeverBranchNode( m );
2891 _igvn.register_new_node_with_optimizer(iff);
2892 set_loop(iff, l);
2893 Node *if_t = new (C) CProjNode( iff, 0 );
2894 _igvn.register_new_node_with_optimizer(if_t);
2895 set_loop(if_t, l);
2896
2897 Node* cfg = NULL; // Find the One True Control User of m
2898 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
2899 Node* x = m->fast_out(j);
2900 if (x->is_CFG() && x != m && x != iff)
2901 { cfg = x; break; }
2902 }
2903 assert(cfg != NULL, "must find the control user of m");
2904 uint k = 0; // Probably cfg->in(0)
2905 while( cfg->in(k) != m ) k++; // But check incase cfg is a Region
2906 cfg->set_req( k, if_t ); // Now point to NeverBranch
2907
2908 // Now create the never-taken loop exit
2909 Node *if_f = new (C) CProjNode( iff, 1 );
2910 _igvn.register_new_node_with_optimizer(if_f);
2911 set_loop(if_f, l);
2912 // Find frame ptr for Halt. Relies on the optimizer
2913 // V-N'ing. Easier and quicker than searching through
2914 // the program structure.
2915 Node *frame = new (C) ParmNode( C->start(), TypeFunc::FramePtr );
2916 _igvn.register_new_node_with_optimizer(frame);
2917 // Halt & Catch Fire
2918 Node *halt = new (C) HaltNode( if_f, frame );
2919 _igvn.register_new_node_with_optimizer(halt);
2920 set_loop(halt, l);
2921 C->root()->add_req(halt);
2922 }
2923 set_loop(C->root(), _ltree_root);
2924 }
2925 }
2926 // Weeny check for irreducible. This child was already visited (this
2927 // IS the post-work phase). Is this child's loop header post-visited
2928 // as well? If so, then I found another entry into the loop.
2929 if (!_verify_only) {
2930 while( is_postvisited(l->_head) ) {
2931 // found irreducible
2932 l->_irreducible = 1; // = true
2933 l = l->_parent;
2934 _has_irreducible_loops = true;
2935 // Check for bad CFG here to prevent crash, and bailout of compile
2936 if (l == NULL) {
2937 C->record_method_not_compilable("unhandled CFG detected during loop optimization");
2938 return pre_order;
2939 }
2940 }
2941 }
2942
2943 // This Node might be a decision point for loops. It is only if
2944 // it's children belong to several different loops. The sort call
2945 // does a trivial amount of work if there is only 1 child or all
2946 // children belong to the same loop. If however, the children
2947 // belong to different loops, the sort call will properly set the
2948 // _parent pointers to show how the loops nest.
2949 //
2950 // In any case, it returns the tightest enclosing loop.
2951 innermost = sort( l, innermost );
2952 }
2953
2954 // Def-use info will have some dead stuff; dead stuff will have no
2955 // loop decided on.
2956
2957 // Am I a loop header? If so fix up my parent's child and next ptrs.
2958 if( innermost && innermost->_head == n ) {
2959 assert( get_loop(n) == innermost, "" );
2960 IdealLoopTree *p = innermost->_parent;
2961 IdealLoopTree *l = innermost;
2962 while( p && l->_head == n ) {
2963 l->_next = p->_child; // Put self on parents 'next child'
2964 p->_child = l; // Make self as first child of parent
2965 l = p; // Now walk up the parent chain
2966 p = l->_parent;
2967 }
2968 } else {
2969 // Note that it is possible for a LoopNode to reach here, if the
2970 // backedge has been made unreachable (hence the LoopNode no longer
2971 // denotes a Loop, and will eventually be removed).
2972
2973 // Record tightest enclosing loop for self. Mark as post-visited.
2974 set_loop(n, innermost);
2975 // Also record has_call flag early on
2976 if( innermost ) {
2977 if( n->is_Call() && !n->is_CallLeaf() && !n->is_macro() ) {
2978 // Do not count uncommon calls
2979 if( !n->is_CallStaticJava() || !n->as_CallStaticJava()->_name ) {
2980 Node *iff = n->in(0)->in(0);
2981 // No any calls for vectorized loops.
2982 if( UseSuperWord || !iff->is_If() ||
2983 (n->in(0)->Opcode() == Op_IfFalse &&
2984 (1.0 - iff->as_If()->_prob) >= 0.01) ||
2985 (iff->as_If()->_prob >= 0.01) )
2986 innermost->_has_call = 1;
2987 }
2988 } else if( n->is_Allocate() && n->as_Allocate()->_is_scalar_replaceable ) {
2989 // Disable loop optimizations if the loop has a scalar replaceable
2990 // allocation. This disabling may cause a potential performance lost
2991 // if the allocation is not eliminated for some reason.
2992 innermost->_allow_optimizations = false;
2993 innermost->_has_call = 1; // = true
2994 } else if (n->Opcode() == Op_SafePoint) {
2995 // Record all safepoints in this loop.
2996 if (innermost->_safepts == NULL) innermost->_safepts = new Node_List();
2997 innermost->_safepts->push(n);
2998 }
2999 }
3000 }
3001
3002 // Flag as post-visited now
3003 set_postvisited(n);
3004 return pre_order;
3005 }
3006
3007
3008 //------------------------------build_loop_early-------------------------------
3009 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
3010 // First pass computes the earliest controlling node possible. This is the
3011 // controlling input with the deepest dominating depth.
3012 void PhaseIdealLoop::build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) {
3013 while (worklist.size() != 0) {
3014 // Use local variables nstack_top_n & nstack_top_i to cache values
3015 // on nstack's top.
3016 Node *nstack_top_n = worklist.pop();
3017 uint nstack_top_i = 0;
3018 //while_nstack_nonempty:
3019 while (true) {
3020 // Get parent node and next input's index from stack's top.
3021 Node *n = nstack_top_n;
3022 uint i = nstack_top_i;
3023 uint cnt = n->req(); // Count of inputs
3024 if (i == 0) { // Pre-process the node.
3025 if( has_node(n) && // Have either loop or control already?
3026 !has_ctrl(n) ) { // Have loop picked out already?
3027 // During "merge_many_backedges" we fold up several nested loops
3028 // into a single loop. This makes the members of the original
3029 // loop bodies pointing to dead loops; they need to move up
3030 // to the new UNION'd larger loop. I set the _head field of these
3031 // dead loops to NULL and the _parent field points to the owning
3032 // loop. Shades of UNION-FIND algorithm.
3033 IdealLoopTree *ilt;
3034 while( !(ilt = get_loop(n))->_head ) {
3035 // Normally I would use a set_loop here. But in this one special
3036 // case, it is legal (and expected) to change what loop a Node
3037 // belongs to.
3038 _nodes.map(n->_idx, (Node*)(ilt->_parent) );
3039 }
3040 // Remove safepoints ONLY if I've already seen I don't need one.
3041 // (the old code here would yank a 2nd safepoint after seeing a
3042 // first one, even though the 1st did not dominate in the loop body
3043 // and thus could be avoided indefinitely)
3044 if( !_verify_only && !_verify_me && ilt->_has_sfpt && n->Opcode() == Op_SafePoint &&
3045 is_deleteable_safept(n)) {
3046 Node *in = n->in(TypeFunc::Control);
3047 lazy_replace(n,in); // Pull safepoint now
3048 if (ilt->_safepts != NULL) {
3049 ilt->_safepts->yank(n);
3050 }
3051 // Carry on with the recursion "as if" we are walking
3052 // only the control input
3053 if( !visited.test_set( in->_idx ) ) {
3054 worklist.push(in); // Visit this guy later, using worklist
3055 }
3056 // Get next node from nstack:
3057 // - skip n's inputs processing by setting i > cnt;
3058 // - we also will not call set_early_ctrl(n) since
3059 // has_node(n) == true (see the condition above).
3060 i = cnt + 1;
3061 }
3062 }
3063 } // if (i == 0)
3064
3065 // Visit all inputs
3066 bool done = true; // Assume all n's inputs will be processed
3067 while (i < cnt) {
3068 Node *in = n->in(i);
3069 ++i;
3070 if (in == NULL) continue;
3071 if (in->pinned() && !in->is_CFG())
3072 set_ctrl(in, in->in(0));
3073 int is_visited = visited.test_set( in->_idx );
3074 if (!has_node(in)) { // No controlling input yet?
3075 assert( !in->is_CFG(), "CFG Node with no controlling input?" );
3076 assert( !is_visited, "visit only once" );
3077 nstack.push(n, i); // Save parent node and next input's index.
3078 nstack_top_n = in; // Process current input now.
3079 nstack_top_i = 0;
3080 done = false; // Not all n's inputs processed.
3081 break; // continue while_nstack_nonempty;
3082 } else if (!is_visited) {
3083 // This guy has a location picked out for him, but has not yet
3084 // been visited. Happens to all CFG nodes, for instance.
3085 // Visit him using the worklist instead of recursion, to break
3086 // cycles. Since he has a location already we do not need to
3087 // find his location before proceeding with the current Node.
3088 worklist.push(in); // Visit this guy later, using worklist
3089 }
3090 }
3091 if (done) {
3092 // All of n's inputs have been processed, complete post-processing.
3093
3094 // Compute earliest point this Node can go.
3095 // CFG, Phi, pinned nodes already know their controlling input.
3096 if (!has_node(n)) {
3097 // Record earliest legal location
3098 set_early_ctrl( n );
3099 }
3100 if (nstack.is_empty()) {
3101 // Finished all nodes on stack.
3102 // Process next node on the worklist.
3103 break;
3104 }
3105 // Get saved parent node and next input's index.
3106 nstack_top_n = nstack.node();
3107 nstack_top_i = nstack.index();
3108 nstack.pop();
3109 }
3110 } // while (true)
3111 }
3112 }
3113
3114 //------------------------------dom_lca_internal--------------------------------
3115 // Pair-wise LCA
3116 Node *PhaseIdealLoop::dom_lca_internal( Node *n1, Node *n2 ) const {
3117 if( !n1 ) return n2; // Handle NULL original LCA
3118 assert( n1->is_CFG(), "" );
3119 assert( n2->is_CFG(), "" );
3120 // find LCA of all uses
3121 uint d1 = dom_depth(n1);
3122 uint d2 = dom_depth(n2);
3123 while (n1 != n2) {
3124 if (d1 > d2) {
3125 n1 = idom(n1);
3126 d1 = dom_depth(n1);
3127 } else if (d1 < d2) {
3128 n2 = idom(n2);
3129 d2 = dom_depth(n2);
3130 } else {
3131 // Here d1 == d2. Due to edits of the dominator-tree, sections
3132 // of the tree might have the same depth. These sections have
3133 // to be searched more carefully.
3134
3135 // Scan up all the n1's with equal depth, looking for n2.
3136 Node *t1 = idom(n1);
3137 while (dom_depth(t1) == d1) {
3138 if (t1 == n2) return n2;
3139 t1 = idom(t1);
3140 }
3141 // Scan up all the n2's with equal depth, looking for n1.
3142 Node *t2 = idom(n2);
3143 while (dom_depth(t2) == d2) {
3144 if (t2 == n1) return n1;
3145 t2 = idom(t2);
3146 }
3147 // Move up to a new dominator-depth value as well as up the dom-tree.
3148 n1 = t1;
3149 n2 = t2;
3150 d1 = dom_depth(n1);
3151 d2 = dom_depth(n2);
3152 }
3153 }
3154 return n1;
3155 }
3156
3157 //------------------------------compute_idom-----------------------------------
3158 // Locally compute IDOM using dom_lca call. Correct only if the incoming
3159 // IDOMs are correct.
3160 Node *PhaseIdealLoop::compute_idom( Node *region ) const {
3161 assert( region->is_Region(), "" );
3162 Node *LCA = NULL;
3163 for( uint i = 1; i < region->req(); i++ ) {
3164 if( region->in(i) != C->top() )
3165 LCA = dom_lca( LCA, region->in(i) );
3166 }
3167 return LCA;
3168 }
3169
3170 bool PhaseIdealLoop::verify_dominance(Node* n, Node* use, Node* LCA, Node* early) {
3171 bool had_error = false;
3172 #ifdef ASSERT
3173 if (early != C->root()) {
3174 // Make sure that there's a dominance path from use to LCA
3175 Node* d = use;
3176 while (d != LCA) {
3177 d = idom(d);
3178 if (d == C->root()) {
3179 tty->print_cr("*** Use %d isn't dominated by def %s", use->_idx, n->_idx);
3180 n->dump();
3181 use->dump();
3182 had_error = true;
3183 break;
3184 }
3185 }
3186 }
3187 #endif
3188 return had_error;
3189 }
3190
3191
3192 Node* PhaseIdealLoop::compute_lca_of_uses(Node* n, Node* early, bool verify) {
3193 // Compute LCA over list of uses
3194 bool had_error = false;
3195 Node *LCA = NULL;
3196 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax && LCA != early; i++) {
3197 Node* c = n->fast_out(i);
3198 if (_nodes[c->_idx] == NULL)
3199 continue; // Skip the occasional dead node
3200 if( c->is_Phi() ) { // For Phis, we must land above on the path
3201 for( uint j=1; j<c->req(); j++ ) {// For all inputs
3202 if( c->in(j) == n ) { // Found matching input?
3203 Node *use = c->in(0)->in(j);
3204 if (_verify_only && use->is_top()) continue;
3205 LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
3206 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error;
3207 }
3208 }
3209 } else {
3210 // For CFG data-users, use is in the block just prior
3211 Node *use = has_ctrl(c) ? get_ctrl(c) : c->in(0);
3212 LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
3213 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error;
3214 }
3215 }
3216 assert(!had_error, "bad dominance");
3217 return LCA;
3218 }
3219
3220 //------------------------------get_late_ctrl----------------------------------
3221 // Compute latest legal control.
3222 Node *PhaseIdealLoop::get_late_ctrl( Node *n, Node *early ) {
3223 assert(early != NULL, "early control should not be NULL");
3224
3225 Node* LCA = compute_lca_of_uses(n, early);
3226 #ifdef ASSERT
3227 if (LCA == C->root() && LCA != early) {
3228 // def doesn't dominate uses so print some useful debugging output
3229 compute_lca_of_uses(n, early, true);
3230 }
3231 #endif
3232
3233 // if this is a load, check for anti-dependent stores
3234 // We use a conservative algorithm to identify potential interfering
3235 // instructions and for rescheduling the load. The users of the memory
3236 // input of this load are examined. Any use which is not a load and is
3237 // dominated by early is considered a potentially interfering store.
3238 // This can produce false positives.
3239 if (n->is_Load() && LCA != early) {
3240 Node_List worklist;
3241
3242 Node *mem = n->in(MemNode::Memory);
3243 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
3244 Node* s = mem->fast_out(i);
3245 worklist.push(s);
3246 }
3247 while(worklist.size() != 0 && LCA != early) {
3248 Node* s = worklist.pop();
3249 if (s->is_Load()) {
3250 continue;
3251 } else if (s->is_MergeMem()) {
3252 for (DUIterator_Fast imax, i = s->fast_outs(imax); i < imax; i++) {
3253 Node* s1 = s->fast_out(i);
3254 worklist.push(s1);
3255 }
3256 } else {
3257 Node *sctrl = has_ctrl(s) ? get_ctrl(s) : s->in(0);
3258 assert(sctrl != NULL || s->outcnt() == 0, "must have control");
3259 if (sctrl != NULL && !sctrl->is_top() && is_dominator(early, sctrl)) {
3260 LCA = dom_lca_for_get_late_ctrl(LCA, sctrl, n);
3261 }
3262 }
3263 }
3264 }
3265
3266 assert(LCA == find_non_split_ctrl(LCA), "unexpected late control");
3267 return LCA;
3268 }
3269
3270 // true if CFG node d dominates CFG node n
3271 bool PhaseIdealLoop::is_dominator(Node *d, Node *n) {
3272 if (d == n)
3273 return true;
3274 assert(d->is_CFG() && n->is_CFG(), "must have CFG nodes");
3275 uint dd = dom_depth(d);
3276 while (dom_depth(n) >= dd) {
3277 if (n == d)
3278 return true;
3279 n = idom(n);
3280 }
3281 return false;
3282 }
3283
3284 //------------------------------dom_lca_for_get_late_ctrl_internal-------------
3285 // Pair-wise LCA with tags.
3286 // Tag each index with the node 'tag' currently being processed
3287 // before advancing up the dominator chain using idom().
3288 // Later calls that find a match to 'tag' know that this path has already
3289 // been considered in the current LCA (which is input 'n1' by convention).
3290 // Since get_late_ctrl() is only called once for each node, the tag array
3291 // does not need to be cleared between calls to get_late_ctrl().
3292 // Algorithm trades a larger constant factor for better asymptotic behavior
3293 //
3294 Node *PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal( Node *n1, Node *n2, Node *tag ) {
3295 uint d1 = dom_depth(n1);
3296 uint d2 = dom_depth(n2);
3297
3298 do {
3299 if (d1 > d2) {
3300 // current lca is deeper than n2
3301 _dom_lca_tags.map(n1->_idx, tag);
3302 n1 = idom(n1);
3303 d1 = dom_depth(n1);
3304 } else if (d1 < d2) {
3305 // n2 is deeper than current lca
3306 Node *memo = _dom_lca_tags[n2->_idx];
3307 if( memo == tag ) {
3308 return n1; // Return the current LCA
3309 }
3310 _dom_lca_tags.map(n2->_idx, tag);
3311 n2 = idom(n2);
3312 d2 = dom_depth(n2);
3313 } else {
3314 // Here d1 == d2. Due to edits of the dominator-tree, sections
3315 // of the tree might have the same depth. These sections have
3316 // to be searched more carefully.
3317
3318 // Scan up all the n1's with equal depth, looking for n2.
3319 _dom_lca_tags.map(n1->_idx, tag);
3320 Node *t1 = idom(n1);
3321 while (dom_depth(t1) == d1) {
3322 if (t1 == n2) return n2;
3323 _dom_lca_tags.map(t1->_idx, tag);
3324 t1 = idom(t1);
3325 }
3326 // Scan up all the n2's with equal depth, looking for n1.
3327 _dom_lca_tags.map(n2->_idx, tag);
3328 Node *t2 = idom(n2);
3329 while (dom_depth(t2) == d2) {
3330 if (t2 == n1) return n1;
3331 _dom_lca_tags.map(t2->_idx, tag);
3332 t2 = idom(t2);
3333 }
3334 // Move up to a new dominator-depth value as well as up the dom-tree.
3335 n1 = t1;
3336 n2 = t2;
3337 d1 = dom_depth(n1);
3338 d2 = dom_depth(n2);
3339 }
3340 } while (n1 != n2);
3341 return n1;
3342 }
3343
3344 //------------------------------init_dom_lca_tags------------------------------
3345 // Tag could be a node's integer index, 32bits instead of 64bits in some cases
3346 // Intended use does not involve any growth for the array, so it could
3347 // be of fixed size.
3348 void PhaseIdealLoop::init_dom_lca_tags() {
3349 uint limit = C->unique() + 1;
3350 _dom_lca_tags.map( limit, NULL );
3351 #ifdef ASSERT
3352 for( uint i = 0; i < limit; ++i ) {
3353 assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer");
3354 }
3355 #endif // ASSERT
3356 }
3357
3358 //------------------------------clear_dom_lca_tags------------------------------
3359 // Tag could be a node's integer index, 32bits instead of 64bits in some cases
3360 // Intended use does not involve any growth for the array, so it could
3361 // be of fixed size.
3362 void PhaseIdealLoop::clear_dom_lca_tags() {
3363 uint limit = C->unique() + 1;
3364 _dom_lca_tags.map( limit, NULL );
3365 _dom_lca_tags.clear();
3366 #ifdef ASSERT
3367 for( uint i = 0; i < limit; ++i ) {
3368 assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer");
3369 }
3370 #endif // ASSERT
3371 }
3372
3373 //------------------------------build_loop_late--------------------------------
3374 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
3375 // Second pass finds latest legal placement, and ideal loop placement.
3376 void PhaseIdealLoop::build_loop_late( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) {
3377 while (worklist.size() != 0) {
3378 Node *n = worklist.pop();
3379 // Only visit once
3380 if (visited.test_set(n->_idx)) continue;
3381 uint cnt = n->outcnt();
3382 uint i = 0;
3383 while (true) {
3384 assert( _nodes[n->_idx], "no dead nodes" );
3385 // Visit all children
3386 if (i < cnt) {
3387 Node* use = n->raw_out(i);
3388 ++i;
3389 // Check for dead uses. Aggressively prune such junk. It might be
3390 // dead in the global sense, but still have local uses so I cannot
3391 // easily call 'remove_dead_node'.
3392 if( _nodes[use->_idx] != NULL || use->is_top() ) { // Not dead?
3393 // Due to cycles, we might not hit the same fixed point in the verify
3394 // pass as we do in the regular pass. Instead, visit such phis as
3395 // simple uses of the loop head.
3396 if( use->in(0) && (use->is_CFG() || use->is_Phi()) ) {
3397 if( !visited.test(use->_idx) )
3398 worklist.push(use);
3399 } else if( !visited.test_set(use->_idx) ) {
3400 nstack.push(n, i); // Save parent and next use's index.
3401 n = use; // Process all children of current use.
3402 cnt = use->outcnt();
3403 i = 0;
3404 }
3405 } else {
3406 // Do not visit around the backedge of loops via data edges.
3407 // push dead code onto a worklist
3408 _deadlist.push(use);
3409 }
3410 } else {
3411 // All of n's children have been processed, complete post-processing.
3412 build_loop_late_post(n);
3413 if (nstack.is_empty()) {
3414 // Finished all nodes on stack.
3415 // Process next node on the worklist.
3416 break;
3417 }
3418 // Get saved parent node and next use's index. Visit the rest of uses.
3419 n = nstack.node();
3420 cnt = n->outcnt();
3421 i = nstack.index();
3422 nstack.pop();
3423 }
3424 }
3425 }
3426 }
3427
3428 //------------------------------build_loop_late_post---------------------------
3429 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
3430 // Second pass finds latest legal placement, and ideal loop placement.
3431 void PhaseIdealLoop::build_loop_late_post( Node *n ) {
3432
3433 if (n->req() == 2 && n->Opcode() == Op_ConvI2L && !C->major_progress() && !_verify_only) {
3434 _igvn._worklist.push(n); // Maybe we'll normalize it, if no more loops.
3435 }
3436
3437 // CFG and pinned nodes already handled
3438 if( n->in(0) ) {
3439 if( n->in(0)->is_top() ) return; // Dead?
3440
3441 // We'd like +VerifyLoopOptimizations to not believe that Mod's/Loads
3442 // _must_ be pinned (they have to observe their control edge of course).
3443 // Unlike Stores (which modify an unallocable resource, the memory
3444 // state), Mods/Loads can float around. So free them up.
3445 bool pinned = true;
3446 switch( n->Opcode() ) {
3447 case Op_DivI:
3448 case Op_DivF:
3449 case Op_DivD:
3450 case Op_ModI:
3451 case Op_ModF:
3452 case Op_ModD:
3453 case Op_LoadB: // Same with Loads; they can sink
3454 case Op_LoadUB: // during loop optimizations.
3455 case Op_LoadUS:
3456 case Op_LoadD:
3457 case Op_LoadF:
3458 case Op_LoadI:
3459 case Op_LoadKlass:
3460 case Op_LoadNKlass:
3461 case Op_LoadL:
3462 case Op_LoadS:
3463 case Op_LoadP:
3464 case Op_LoadN:
3465 case Op_LoadRange:
3466 case Op_LoadD_unaligned:
3467 case Op_LoadL_unaligned:
3468 case Op_StrComp: // Does a bunch of load-like effects
3469 case Op_StrEquals:
3470 case Op_StrIndexOf:
3471 case Op_AryEq:
3472 pinned = false;
3473 }
3474 if( pinned ) {
3475 IdealLoopTree *chosen_loop = get_loop(n->is_CFG() ? n : get_ctrl(n));
3476 if( !chosen_loop->_child ) // Inner loop?
3477 chosen_loop->_body.push(n); // Collect inner loops
3478 return;
3479 }
3480 } else { // No slot zero
3481 if( n->is_CFG() ) { // CFG with no slot 0 is dead
3482 _nodes.map(n->_idx,0); // No block setting, it's globally dead
3483 return;
3484 }
3485 assert(!n->is_CFG() || n->outcnt() == 0, "");
3486 }
3487
3488 // Do I have a "safe range" I can select over?
3489 Node *early = get_ctrl(n);// Early location already computed
3490
3491 // Compute latest point this Node can go
3492 Node *LCA = get_late_ctrl( n, early );
3493 // LCA is NULL due to uses being dead
3494 if( LCA == NULL ) {
3495 #ifdef ASSERT
3496 for (DUIterator i1 = n->outs(); n->has_out(i1); i1++) {
3497 assert( _nodes[n->out(i1)->_idx] == NULL, "all uses must also be dead");
3498 }
3499 #endif
3500 _nodes.map(n->_idx, 0); // This node is useless
3501 _deadlist.push(n);
3502 return;
3503 }
3504 assert(LCA != NULL && !LCA->is_top(), "no dead nodes");
3505
3506 Node *legal = LCA; // Walk 'legal' up the IDOM chain
3507 Node *least = legal; // Best legal position so far
3508 while( early != legal ) { // While not at earliest legal
3509 #ifdef ASSERT
3510 if (legal->is_Start() && !early->is_Root()) {
3511 // Bad graph. Print idom path and fail.
3512 dump_bad_graph("Bad graph detected in build_loop_late", n, early, LCA);
3513 assert(false, "Bad graph detected in build_loop_late");
3514 }
3515 #endif
3516 // Find least loop nesting depth
3517 legal = idom(legal); // Bump up the IDOM tree
3518 // Check for lower nesting depth
3519 if( get_loop(legal)->_nest < get_loop(least)->_nest )
3520 least = legal;
3521 }
3522 assert(early == legal || legal != C->root(), "bad dominance of inputs");
3523
3524 // Try not to place code on a loop entry projection
3525 // which can inhibit range check elimination.
3526 if (least != early) {
3527 Node* ctrl_out = least->unique_ctrl_out();
3528 if (ctrl_out && ctrl_out->is_CountedLoop() &&
3529 least == ctrl_out->in(LoopNode::EntryControl)) {
3530 Node* least_dom = idom(least);
3531 if (get_loop(least_dom)->is_member(get_loop(least))) {
3532 least = least_dom;
3533 }
3534 }
3535 }
3536
3537 #ifdef ASSERT
3538 // If verifying, verify that 'verify_me' has a legal location
3539 // and choose it as our location.
3540 if( _verify_me ) {
3541 Node *v_ctrl = _verify_me->get_ctrl_no_update(n);
3542 Node *legal = LCA;
3543 while( early != legal ) { // While not at earliest legal
3544 if( legal == v_ctrl ) break; // Check for prior good location
3545 legal = idom(legal) ;// Bump up the IDOM tree
3546 }
3547 // Check for prior good location
3548 if( legal == v_ctrl ) least = legal; // Keep prior if found
3549 }
3550 #endif
3551
3552 // Assign discovered "here or above" point
3553 least = find_non_split_ctrl(least);
3554 set_ctrl(n, least);
3555
3556 // Collect inner loop bodies
3557 IdealLoopTree *chosen_loop = get_loop(least);
3558 if( !chosen_loop->_child ) // Inner loop?
3559 chosen_loop->_body.push(n);// Collect inner loops
3560 }
3561
3562 #ifdef ASSERT
3563 void PhaseIdealLoop::dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA) {
3564 tty->print_cr(msg);
3565 tty->print("n: "); n->dump();
3566 tty->print("early(n): "); early->dump();
3567 if (n->in(0) != NULL && !n->in(0)->is_top() &&
3568 n->in(0) != early && !n->in(0)->is_Root()) {
3569 tty->print("n->in(0): "); n->in(0)->dump();
3570 }
3571 for (uint i = 1; i < n->req(); i++) {
3572 Node* in1 = n->in(i);
3573 if (in1 != NULL && in1 != n && !in1->is_top()) {
3574 tty->print("n->in(%d): ", i); in1->dump();
3575 Node* in1_early = get_ctrl(in1);
3576 tty->print("early(n->in(%d)): ", i); in1_early->dump();
3577 if (in1->in(0) != NULL && !in1->in(0)->is_top() &&
3578 in1->in(0) != in1_early && !in1->in(0)->is_Root()) {
3579 tty->print("n->in(%d)->in(0): ", i); in1->in(0)->dump();
3580 }
3581 for (uint j = 1; j < in1->req(); j++) {
3582 Node* in2 = in1->in(j);
3583 if (in2 != NULL && in2 != n && in2 != in1 && !in2->is_top()) {
3584 tty->print("n->in(%d)->in(%d): ", i, j); in2->dump();
3585 Node* in2_early = get_ctrl(in2);
3586 tty->print("early(n->in(%d)->in(%d)): ", i, j); in2_early->dump();
3587 if (in2->in(0) != NULL && !in2->in(0)->is_top() &&
3588 in2->in(0) != in2_early && !in2->in(0)->is_Root()) {
3589 tty->print("n->in(%d)->in(%d)->in(0): ", i, j); in2->in(0)->dump();
3590 }
3591 }
3592 }
3593 }
3594 }
3595 tty->cr();
3596 tty->print("LCA(n): "); LCA->dump();
3597 for (uint i = 0; i < n->outcnt(); i++) {
3598 Node* u1 = n->raw_out(i);
3599 if (u1 == n)
3600 continue;
3601 tty->print("n->out(%d): ", i); u1->dump();
3602 if (u1->is_CFG()) {
3603 for (uint j = 0; j < u1->outcnt(); j++) {
3604 Node* u2 = u1->raw_out(j);
3605 if (u2 != u1 && u2 != n && u2->is_CFG()) {
3606 tty->print("n->out(%d)->out(%d): ", i, j); u2->dump();
3607 }
3608 }
3609 } else {
3610 Node* u1_later = get_ctrl(u1);
3611 tty->print("later(n->out(%d)): ", i); u1_later->dump();
3612 if (u1->in(0) != NULL && !u1->in(0)->is_top() &&
3613 u1->in(0) != u1_later && !u1->in(0)->is_Root()) {
3614 tty->print("n->out(%d)->in(0): ", i); u1->in(0)->dump();
3615 }
3616 for (uint j = 0; j < u1->outcnt(); j++) {
3617 Node* u2 = u1->raw_out(j);
3618 if (u2 == n || u2 == u1)
3619 continue;
3620 tty->print("n->out(%d)->out(%d): ", i, j); u2->dump();
3621 if (!u2->is_CFG()) {
3622 Node* u2_later = get_ctrl(u2);
3623 tty->print("later(n->out(%d)->out(%d)): ", i, j); u2_later->dump();
3624 if (u2->in(0) != NULL && !u2->in(0)->is_top() &&
3625 u2->in(0) != u2_later && !u2->in(0)->is_Root()) {
3626 tty->print("n->out(%d)->in(0): ", i); u2->in(0)->dump();
3627 }
3628 }
3629 }
3630 }
3631 }
3632 tty->cr();
3633 int ct = 0;
3634 Node *dbg_legal = LCA;
3635 while(!dbg_legal->is_Start() && ct < 100) {
3636 tty->print("idom[%d] ",ct); dbg_legal->dump();
3637 ct++;
3638 dbg_legal = idom(dbg_legal);
3639 }
3640 tty->cr();
3641 }
3642 #endif
3643
3644 #ifndef PRODUCT
3645 //------------------------------dump-------------------------------------------
3646 void PhaseIdealLoop::dump( ) const {
3647 ResourceMark rm;
3648 Arena* arena = Thread::current()->resource_area();
3649 Node_Stack stack(arena, C->unique() >> 2);
3650 Node_List rpo_list;
3651 VectorSet visited(arena);
3652 visited.set(C->top()->_idx);
3653 rpo( C->root(), stack, visited, rpo_list );
3654 // Dump root loop indexed by last element in PO order
3655 dump( _ltree_root, rpo_list.size(), rpo_list );
3656 }
3657
3658 void PhaseIdealLoop::dump( IdealLoopTree *loop, uint idx, Node_List &rpo_list ) const {
3659 loop->dump_head();
3660
3661 // Now scan for CFG nodes in the same loop
3662 for( uint j=idx; j > 0; j-- ) {
3663 Node *n = rpo_list[j-1];
3664 if( !_nodes[n->_idx] ) // Skip dead nodes
3665 continue;
3666 if( get_loop(n) != loop ) { // Wrong loop nest
3667 if( get_loop(n)->_head == n && // Found nested loop?
3668 get_loop(n)->_parent == loop )
3669 dump(get_loop(n),rpo_list.size(),rpo_list); // Print it nested-ly
3670 continue;
3671 }
3672
3673 // Dump controlling node
3674 for( uint x = 0; x < loop->_nest; x++ )
3675 tty->print(" ");
3676 tty->print("C");
3677 if( n == C->root() ) {
3678 n->dump();
3679 } else {
3680 Node* cached_idom = idom_no_update(n);
3681 Node *computed_idom = n->in(0);
3682 if( n->is_Region() ) {
3683 computed_idom = compute_idom(n);
3684 // computed_idom() will return n->in(0) when idom(n) is an IfNode (or
3685 // any MultiBranch ctrl node), so apply a similar transform to
3686 // the cached idom returned from idom_no_update.
3687 cached_idom = find_non_split_ctrl(cached_idom);
3688 }
3689 tty->print(" ID:%d",computed_idom->_idx);
3690 n->dump();
3691 if( cached_idom != computed_idom ) {
3692 tty->print_cr("*** BROKEN IDOM! Computed as: %d, cached as: %d",
3693 computed_idom->_idx, cached_idom->_idx);
3694 }
3695 }
3696 // Dump nodes it controls
3697 for( uint k = 0; k < _nodes.Size(); k++ ) {
3698 // (k < C->unique() && get_ctrl(find(k)) == n)
3699 if (k < C->unique() && _nodes[k] == (Node*)((intptr_t)n + 1)) {
3700 Node *m = C->root()->find(k);
3701 if( m && m->outcnt() > 0 ) {
3702 if (!(has_ctrl(m) && get_ctrl_no_update(m) == n)) {
3703 tty->print_cr("*** BROKEN CTRL ACCESSOR! _nodes[k] is %p, ctrl is %p",
3704 _nodes[k], has_ctrl(m) ? get_ctrl_no_update(m) : NULL);
3705 }
3706 for( uint j = 0; j < loop->_nest; j++ )
3707 tty->print(" ");
3708 tty->print(" ");
3709 m->dump();
3710 }
3711 }
3712 }
3713 }
3714 }
3715
3716 // Collect a R-P-O for the whole CFG.
3717 // Result list is in post-order (scan backwards for RPO)
3718 void PhaseIdealLoop::rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const {
3719 stk.push(start, 0);
3720 visited.set(start->_idx);
3721
3722 while (stk.is_nonempty()) {
3723 Node* m = stk.node();
3724 uint idx = stk.index();
3725 if (idx < m->outcnt()) {
3726 stk.set_index(idx + 1);
3727 Node* n = m->raw_out(idx);
3728 if (n->is_CFG() && !visited.test_set(n->_idx)) {
3729 stk.push(n, 0);
3730 }
3731 } else {
3732 rpo_list.push(m);
3733 stk.pop();
3734 }
3735 }
3736 }
3737 #endif
3738
3739
3740 //=============================================================================
3741 //------------------------------LoopTreeIterator-----------------------------------
3742
3743 // Advance to next loop tree using a preorder, left-to-right traversal.
3744 void LoopTreeIterator::next() {
3745 assert(!done(), "must not be done.");
3746 if (_curnt->_child != NULL) {
3747 _curnt = _curnt->_child;
3748 } else if (_curnt->_next != NULL) {
3749 _curnt = _curnt->_next;
3750 } else {
3751 while (_curnt != _root && _curnt->_next == NULL) {
3752 _curnt = _curnt->_parent;
3753 }
3754 if (_curnt == _root) {
3755 _curnt = NULL;
3756 assert(done(), "must be done.");
3757 } else {
3758 assert(_curnt->_next != NULL, "must be more to do");
3759 _curnt = _curnt->_next;
3760 }
3761 }
3762 }