1 /*
2 * Copyright (c) 1998, 2014, 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/convertnode.hpp"
34 #include "opto/divnode.hpp"
35 #include "opto/idealGraphPrinter.hpp"
36 #include "opto/loopnode.hpp"
37 #include "opto/mulnode.hpp"
38 #include "opto/rootnode.hpp"
39 #include "opto/superword.hpp"
40
41 //=============================================================================
42 //------------------------------is_loop_iv-------------------------------------
43 // Determine if a node is Counted loop induction variable.
44 // The method is declared in node.hpp.
45 const Node* Node::is_loop_iv() const {
46 if (this->is_Phi() && !this->as_Phi()->is_copy() &&
47 this->as_Phi()->region()->is_CountedLoop() &&
48 this->as_Phi()->region()->as_CountedLoop()->phi() == this) {
49 return this;
50 } else {
51 return NULL;
52 }
53 }
54
55 //=============================================================================
56 //------------------------------dump_spec--------------------------------------
57 // Dump special per-node info
58 #ifndef PRODUCT
59 void LoopNode::dump_spec(outputStream *st) const {
60 if (is_inner_loop()) st->print( "inner " );
61 if (is_partial_peel_loop()) st->print( "partial_peel " );
62 if (partial_peel_has_failed()) st->print( "partial_peel_failed " );
63 }
64 #endif
65
66 //------------------------------is_valid_counted_loop-------------------------
67 bool LoopNode::is_valid_counted_loop() const {
68 if (is_CountedLoop()) {
69 CountedLoopNode* l = as_CountedLoop();
70 CountedLoopEndNode* le = l->loopexit();
71 if (le != NULL &&
72 le->proj_out(1 /* true */) == l->in(LoopNode::LoopBackControl)) {
73 Node* phi = l->phi();
74 Node* exit = le->proj_out(0 /* false */);
75 if (exit != NULL && exit->Opcode() == Op_IfFalse &&
76 phi != NULL && phi->is_Phi() &&
77 phi->in(LoopNode::LoopBackControl) == l->incr() &&
78 le->loopnode() == l && le->stride_is_con()) {
79 return true;
80 }
81 }
82 }
83 return false;
84 }
85
86 //------------------------------get_early_ctrl---------------------------------
87 // Compute earliest legal control
88 Node *PhaseIdealLoop::get_early_ctrl( Node *n ) {
89 assert( !n->is_Phi() && !n->is_CFG(), "this code only handles data nodes" );
90 uint i;
91 Node *early;
92 if (n->in(0) && !n->is_expensive()) {
93 early = n->in(0);
94 if (!early->is_CFG()) // Might be a non-CFG multi-def
95 early = get_ctrl(early); // So treat input as a straight data input
96 i = 1;
97 } else {
98 early = get_ctrl(n->in(1));
99 i = 2;
100 }
101 uint e_d = dom_depth(early);
102 assert( early, "" );
103 for (; i < n->req(); i++) {
104 Node *cin = get_ctrl(n->in(i));
105 assert( cin, "" );
106 // Keep deepest dominator depth
107 uint c_d = dom_depth(cin);
108 if (c_d > e_d) { // Deeper guy?
109 early = cin; // Keep deepest found so far
110 e_d = c_d;
111 } else if (c_d == e_d && // Same depth?
112 early != cin) { // If not equal, must use slower algorithm
113 // If same depth but not equal, one _must_ dominate the other
114 // and we want the deeper (i.e., dominated) guy.
115 Node *n1 = early;
116 Node *n2 = cin;
117 while (1) {
118 n1 = idom(n1); // Walk up until break cycle
119 n2 = idom(n2);
120 if (n1 == cin || // Walked early up to cin
121 dom_depth(n2) < c_d)
122 break; // early is deeper; keep him
123 if (n2 == early || // Walked cin up to early
124 dom_depth(n1) < c_d) {
125 early = cin; // cin is deeper; keep him
126 break;
127 }
128 }
129 e_d = dom_depth(early); // Reset depth register cache
130 }
131 }
132
133 // Return earliest legal location
134 assert(early == find_non_split_ctrl(early), "unexpected early control");
135
136 if (n->is_expensive()) {
137 assert(n->in(0), "should have control input");
138 early = get_early_ctrl_for_expensive(n, early);
139 }
140
141 return early;
142 }
143
144 //------------------------------get_early_ctrl_for_expensive---------------------------------
145 // Move node up the dominator tree as high as legal while still beneficial
146 Node *PhaseIdealLoop::get_early_ctrl_for_expensive(Node *n, Node* earliest) {
147 assert(n->in(0) && n->is_expensive(), "expensive node with control input here");
148 assert(OptimizeExpensiveOps, "optimization off?");
149
150 Node* ctl = n->in(0);
151 assert(ctl->is_CFG(), "expensive input 0 must be cfg");
152 uint min_dom_depth = dom_depth(earliest);
153 #ifdef ASSERT
154 if (!is_dominator(ctl, earliest) && !is_dominator(earliest, ctl)) {
155 dump_bad_graph("Bad graph detected in get_early_ctrl_for_expensive", n, earliest, ctl);
156 assert(false, "Bad graph detected in get_early_ctrl_for_expensive");
157 }
158 #endif
159 if (dom_depth(ctl) < min_dom_depth) {
160 return earliest;
161 }
162
163 while (1) {
164 Node *next = ctl;
165 // Moving the node out of a loop on the projection of a If
166 // confuses loop predication. So once we hit a Loop in a If branch
167 // that doesn't branch to an UNC, we stop. The code that process
168 // expensive nodes will notice the loop and skip over it to try to
169 // move the node further up.
170 if (ctl->is_CountedLoop() && ctl->in(1) != NULL && ctl->in(1)->in(0) != NULL && ctl->in(1)->in(0)->is_If()) {
171 if (!ctl->in(1)->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) {
172 break;
173 }
174 next = idom(ctl->in(1)->in(0));
175 } else if (ctl->is_Proj()) {
176 // We only move it up along a projection if the projection is
177 // the single control projection for its parent: same code path,
178 // if it's a If with UNC or fallthrough of a call.
179 Node* parent_ctl = ctl->in(0);
180 if (parent_ctl == NULL) {
181 break;
182 } else if (parent_ctl->is_CountedLoopEnd() && parent_ctl->as_CountedLoopEnd()->loopnode() != NULL) {
183 next = parent_ctl->as_CountedLoopEnd()->loopnode()->init_control();
184 } else if (parent_ctl->is_If()) {
185 if (!ctl->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) {
186 break;
187 }
188 assert(idom(ctl) == parent_ctl, "strange");
189 next = idom(parent_ctl);
190 } else if (ctl->is_CatchProj()) {
191 if (ctl->as_Proj()->_con != CatchProjNode::fall_through_index) {
192 break;
193 }
194 assert(parent_ctl->in(0)->in(0)->is_Call(), "strange graph");
195 next = parent_ctl->in(0)->in(0)->in(0);
196 } else {
197 // Check if parent control has a single projection (this
198 // control is the only possible successor of the parent
199 // control). If so, we can try to move the node above the
200 // parent control.
201 int nb_ctl_proj = 0;
202 for (DUIterator_Fast imax, i = parent_ctl->fast_outs(imax); i < imax; i++) {
203 Node *p = parent_ctl->fast_out(i);
204 if (p->is_Proj() && p->is_CFG()) {
205 nb_ctl_proj++;
206 if (nb_ctl_proj > 1) {
207 break;
208 }
209 }
210 }
211
212 if (nb_ctl_proj > 1) {
213 break;
214 }
215 assert(parent_ctl->is_Start() || parent_ctl->is_MemBar() || parent_ctl->is_Call(), "unexpected node");
216 assert(idom(ctl) == parent_ctl, "strange");
217 next = idom(parent_ctl);
218 }
219 } else {
220 next = idom(ctl);
221 }
222 if (next->is_Root() || next->is_Start() || dom_depth(next) < min_dom_depth) {
223 break;
224 }
225 ctl = next;
226 }
227
228 if (ctl != n->in(0)) {
229 _igvn.hash_delete(n);
230 n->set_req(0, ctl);
231 _igvn.hash_insert(n);
232 }
233
234 return ctl;
235 }
236
237
238 //------------------------------set_early_ctrl---------------------------------
239 // Set earliest legal control
240 void PhaseIdealLoop::set_early_ctrl( Node *n ) {
241 Node *early = get_early_ctrl(n);
242
243 // Record earliest legal location
244 set_ctrl(n, early);
245 }
246
247 //------------------------------set_subtree_ctrl-------------------------------
248 // set missing _ctrl entries on new nodes
249 void PhaseIdealLoop::set_subtree_ctrl( Node *n ) {
250 // Already set? Get out.
251 if( _nodes[n->_idx] ) return;
252 // Recursively set _nodes array to indicate where the Node goes
253 uint i;
254 for( i = 0; i < n->req(); ++i ) {
255 Node *m = n->in(i);
256 if( m && m != C->root() )
257 set_subtree_ctrl( m );
258 }
259
260 // Fixup self
261 set_early_ctrl( n );
262 }
263
264 //------------------------------is_counted_loop--------------------------------
265 bool PhaseIdealLoop::is_counted_loop( Node *x, IdealLoopTree *loop ) {
266 PhaseGVN *gvn = &_igvn;
267
268 // Counted loop head must be a good RegionNode with only 3 not NULL
269 // control input edges: Self, Entry, LoopBack.
270 if (x->in(LoopNode::Self) == NULL || x->req() != 3 || loop->_irreducible) {
271 return false;
272 }
273 Node *init_control = x->in(LoopNode::EntryControl);
274 Node *back_control = x->in(LoopNode::LoopBackControl);
275 if (init_control == NULL || back_control == NULL) // Partially dead
276 return false;
277 // Must also check for TOP when looking for a dead loop
278 if (init_control->is_top() || back_control->is_top())
279 return false;
280
281 // Allow funny placement of Safepoint
282 if (back_control->Opcode() == Op_SafePoint)
283 back_control = back_control->in(TypeFunc::Control);
284
285 // Controlling test for loop
286 Node *iftrue = back_control;
287 uint iftrue_op = iftrue->Opcode();
288 if (iftrue_op != Op_IfTrue &&
289 iftrue_op != Op_IfFalse)
290 // I have a weird back-control. Probably the loop-exit test is in
291 // the middle of the loop and I am looking at some trailing control-flow
292 // merge point. To fix this I would have to partially peel the loop.
293 return false; // Obscure back-control
294
295 // Get boolean guarding loop-back test
296 Node *iff = iftrue->in(0);
297 if (get_loop(iff) != loop || !iff->in(1)->is_Bool())
298 return false;
299 BoolNode *test = iff->in(1)->as_Bool();
300 BoolTest::mask bt = test->_test._test;
301 float cl_prob = iff->as_If()->_prob;
302 if (iftrue_op == Op_IfFalse) {
303 bt = BoolTest(bt).negate();
304 cl_prob = 1.0 - cl_prob;
305 }
306 // Get backedge compare
307 Node *cmp = test->in(1);
308 int cmp_op = cmp->Opcode();
309 if (cmp_op != Op_CmpI)
310 return false; // Avoid pointer & float compares
311
312 // Find the trip-counter increment & limit. Limit must be loop invariant.
313 Node *incr = cmp->in(1);
314 Node *limit = cmp->in(2);
315
316 // ---------
317 // need 'loop()' test to tell if limit is loop invariant
318 // ---------
319
320 if (!is_member(loop, get_ctrl(incr))) { // Swapped trip counter and limit?
321 Node *tmp = incr; // Then reverse order into the CmpI
322 incr = limit;
323 limit = tmp;
324 bt = BoolTest(bt).commute(); // And commute the exit test
325 }
326 if (is_member(loop, get_ctrl(limit))) // Limit must be loop-invariant
327 return false;
328 if (!is_member(loop, get_ctrl(incr))) // Trip counter must be loop-variant
329 return false;
330
331 Node* phi_incr = NULL;
332 // Trip-counter increment must be commutative & associative.
333 if (incr->is_Phi()) {
334 if (incr->as_Phi()->region() != x || incr->req() != 3)
335 return false; // Not simple trip counter expression
336 phi_incr = incr;
337 incr = phi_incr->in(LoopNode::LoopBackControl); // Assume incr is on backedge of Phi
338 if (!is_member(loop, get_ctrl(incr))) // Trip counter must be loop-variant
339 return false;
340 }
341
342 Node* trunc1 = NULL;
343 Node* trunc2 = NULL;
344 const TypeInt* iv_trunc_t = NULL;
345 if (!(incr = CountedLoopNode::match_incr_with_optional_truncation(incr, &trunc1, &trunc2, &iv_trunc_t))) {
346 return false; // Funny increment opcode
347 }
348 assert(incr->Opcode() == Op_AddI, "wrong increment code");
349
350 // Get merge point
351 Node *xphi = incr->in(1);
352 Node *stride = incr->in(2);
353 if (!stride->is_Con()) { // Oops, swap these
354 if (!xphi->is_Con()) // Is the other guy a constant?
355 return false; // Nope, unknown stride, bail out
356 Node *tmp = xphi; // 'incr' is commutative, so ok to swap
357 xphi = stride;
358 stride = tmp;
359 }
360 // Stride must be constant
361 int stride_con = stride->get_int();
362 if (stride_con == 0)
363 return false; // missed some peephole opt
364
365 if (!xphi->is_Phi())
366 return false; // Too much math on the trip counter
367 if (phi_incr != NULL && phi_incr != xphi)
368 return false;
369 PhiNode *phi = xphi->as_Phi();
370
371 // Phi must be of loop header; backedge must wrap to increment
372 if (phi->region() != x)
373 return false;
374 if (trunc1 == NULL && phi->in(LoopNode::LoopBackControl) != incr ||
375 trunc1 != NULL && phi->in(LoopNode::LoopBackControl) != trunc1) {
376 return false;
377 }
378 Node *init_trip = phi->in(LoopNode::EntryControl);
379
380 // If iv trunc type is smaller than int, check for possible wrap.
381 if (!TypeInt::INT->higher_equal(iv_trunc_t)) {
382 assert(trunc1 != NULL, "must have found some truncation");
383
384 // Get a better type for the phi (filtered thru if's)
385 const TypeInt* phi_ft = filtered_type(phi);
386
387 // Can iv take on a value that will wrap?
388 //
389 // Ensure iv's limit is not within "stride" of the wrap value.
390 //
391 // Example for "short" type
392 // Truncation ensures value is in the range -32768..32767 (iv_trunc_t)
393 // If the stride is +10, then the last value of the induction
394 // variable before the increment (phi_ft->_hi) must be
395 // <= 32767 - 10 and (phi_ft->_lo) must be >= -32768 to
396 // ensure no truncation occurs after the increment.
397
398 if (stride_con > 0) {
399 if (iv_trunc_t->_hi - phi_ft->_hi < stride_con ||
400 iv_trunc_t->_lo > phi_ft->_lo) {
401 return false; // truncation may occur
402 }
403 } else if (stride_con < 0) {
404 if (iv_trunc_t->_lo - phi_ft->_lo > stride_con ||
405 iv_trunc_t->_hi < phi_ft->_hi) {
406 return false; // truncation may occur
407 }
408 }
409 // No possibility of wrap so truncation can be discarded
410 // Promote iv type to Int
411 } else {
412 assert(trunc1 == NULL && trunc2 == NULL, "no truncation for int");
413 }
414
415 // If the condition is inverted and we will be rolling
416 // through MININT to MAXINT, then bail out.
417 if (bt == BoolTest::eq || // Bail out, but this loop trips at most twice!
418 // Odd stride
419 bt == BoolTest::ne && stride_con != 1 && stride_con != -1 ||
420 // Count down loop rolls through MAXINT
421 (bt == BoolTest::le || bt == BoolTest::lt) && stride_con < 0 ||
422 // Count up loop rolls through MININT
423 (bt == BoolTest::ge || bt == BoolTest::gt) && stride_con > 0) {
424 return false; // Bail out
425 }
426
427 const TypeInt* init_t = gvn->type(init_trip)->is_int();
428 const TypeInt* limit_t = gvn->type(limit)->is_int();
429
430 if (stride_con > 0) {
431 jlong init_p = (jlong)init_t->_lo + stride_con;
432 if (init_p > (jlong)max_jint || init_p > (jlong)limit_t->_hi)
433 return false; // cyclic loop or this loop trips only once
434 } else {
435 jlong init_p = (jlong)init_t->_hi + stride_con;
436 if (init_p < (jlong)min_jint || init_p < (jlong)limit_t->_lo)
437 return false; // cyclic loop or this loop trips only once
438 }
439
440 // =================================================
441 // ---- SUCCESS! Found A Trip-Counted Loop! -----
442 //
443 assert(x->Opcode() == Op_Loop, "regular loops only");
444 C->print_method(PHASE_BEFORE_CLOOPS, 3);
445
446 Node *hook = new (C) Node(6);
447
448 if (LoopLimitCheck) {
449
450 // ===================================================
451 // Generate loop limit check to avoid integer overflow
452 // in cases like next (cyclic loops):
453 //
454 // for (i=0; i <= max_jint; i++) {}
455 // for (i=0; i < max_jint; i+=2) {}
456 //
457 //
458 // Limit check predicate depends on the loop test:
459 //
460 // for(;i != limit; i++) --> limit <= (max_jint)
461 // for(;i < limit; i+=stride) --> limit <= (max_jint - stride + 1)
462 // for(;i <= limit; i+=stride) --> limit <= (max_jint - stride )
463 //
464
465 // Check if limit is excluded to do more precise int overflow check.
466 bool incl_limit = (bt == BoolTest::le || bt == BoolTest::ge);
467 int stride_m = stride_con - (incl_limit ? 0 : (stride_con > 0 ? 1 : -1));
468
469 // If compare points directly to the phi we need to adjust
470 // the compare so that it points to the incr. Limit have
471 // to be adjusted to keep trip count the same and the
472 // adjusted limit should be checked for int overflow.
473 if (phi_incr != NULL) {
474 stride_m += stride_con;
475 }
476
477 if (limit->is_Con()) {
478 int limit_con = limit->get_int();
479 if ((stride_con > 0 && limit_con > (max_jint - stride_m)) ||
480 (stride_con < 0 && limit_con < (min_jint - stride_m))) {
481 // Bailout: it could be integer overflow.
482 return false;
483 }
484 } else if ((stride_con > 0 && limit_t->_hi <= (max_jint - stride_m)) ||
485 (stride_con < 0 && limit_t->_lo >= (min_jint - stride_m))) {
486 // Limit's type may satisfy the condition, for example,
487 // when it is an array length.
488 } else {
489 // Generate loop's limit check.
490 // Loop limit check predicate should be near the loop.
491 ProjNode *limit_check_proj = find_predicate_insertion_point(init_control, Deoptimization::Reason_loop_limit_check);
492 if (!limit_check_proj) {
493 // The limit check predicate is not generated if this method trapped here before.
494 #ifdef ASSERT
495 if (TraceLoopLimitCheck) {
496 tty->print("missing loop limit check:");
497 loop->dump_head();
498 x->dump(1);
499 }
500 #endif
501 return false;
502 }
503
504 IfNode* check_iff = limit_check_proj->in(0)->as_If();
505 Node* cmp_limit;
506 Node* bol;
507
508 if (stride_con > 0) {
509 cmp_limit = new (C) CmpINode(limit, _igvn.intcon(max_jint - stride_m));
510 bol = new (C) BoolNode(cmp_limit, BoolTest::le);
511 } else {
512 cmp_limit = new (C) CmpINode(limit, _igvn.intcon(min_jint - stride_m));
513 bol = new (C) BoolNode(cmp_limit, BoolTest::ge);
514 }
515 cmp_limit = _igvn.register_new_node_with_optimizer(cmp_limit);
516 bol = _igvn.register_new_node_with_optimizer(bol);
517 set_subtree_ctrl(bol);
518
519 // Replace condition in original predicate but preserve Opaque node
520 // so that previous predicates could be found.
521 assert(check_iff->in(1)->Opcode() == Op_Conv2B &&
522 check_iff->in(1)->in(1)->Opcode() == Op_Opaque1, "");
523 Node* opq = check_iff->in(1)->in(1);
524 _igvn.hash_delete(opq);
525 opq->set_req(1, bol);
526 // Update ctrl.
527 set_ctrl(opq, check_iff->in(0));
528 set_ctrl(check_iff->in(1), check_iff->in(0));
529
530 #ifndef PRODUCT
531 // report that the loop predication has been actually performed
532 // for this loop
533 if (TraceLoopLimitCheck) {
534 tty->print_cr("Counted Loop Limit Check generated:");
535 debug_only( bol->dump(2); )
536 }
537 #endif
538 }
539
540 if (phi_incr != NULL) {
541 // If compare points directly to the phi we need to adjust
542 // the compare so that it points to the incr. Limit have
543 // to be adjusted to keep trip count the same and we
544 // should avoid int overflow.
545 //
546 // i = init; do {} while(i++ < limit);
547 // is converted to
548 // i = init; do {} while(++i < limit+1);
549 //
550 limit = gvn->transform(new (C) AddINode(limit, stride));
551 }
552
553 // Now we need to canonicalize loop condition.
554 if (bt == BoolTest::ne) {
555 assert(stride_con == 1 || stride_con == -1, "simple increment only");
556 // 'ne' can be replaced with 'lt' only when init < limit.
557 if (stride_con > 0 && init_t->_hi < limit_t->_lo)
558 bt = BoolTest::lt;
559 // 'ne' can be replaced with 'gt' only when init > limit.
560 if (stride_con < 0 && init_t->_lo > limit_t->_hi)
561 bt = BoolTest::gt;
562 }
563
564 if (incl_limit) {
565 // The limit check guaranties that 'limit <= (max_jint - stride)' so
566 // we can convert 'i <= limit' to 'i < limit+1' since stride != 0.
567 //
568 Node* one = (stride_con > 0) ? gvn->intcon( 1) : gvn->intcon(-1);
569 limit = gvn->transform(new (C) AddINode(limit, one));
570 if (bt == BoolTest::le)
571 bt = BoolTest::lt;
572 else if (bt == BoolTest::ge)
573 bt = BoolTest::gt;
574 else
575 ShouldNotReachHere();
576 }
577 set_subtree_ctrl( limit );
578
579 } else { // LoopLimitCheck
580
581 // If compare points to incr, we are ok. Otherwise the compare
582 // can directly point to the phi; in this case adjust the compare so that
583 // it points to the incr by adjusting the limit.
584 if (cmp->in(1) == phi || cmp->in(2) == phi)
585 limit = gvn->transform(new (C) AddINode(limit,stride));
586
587 // trip-count for +-tive stride should be: (limit - init_trip + stride - 1)/stride.
588 // Final value for iterator should be: trip_count * stride + init_trip.
589 Node *one_p = gvn->intcon( 1);
590 Node *one_m = gvn->intcon(-1);
591
592 Node *trip_count = NULL;
593 switch( bt ) {
594 case BoolTest::eq:
595 ShouldNotReachHere();
596 case BoolTest::ne: // Ahh, the case we desire
597 if (stride_con == 1)
598 trip_count = gvn->transform(new (C) SubINode(limit,init_trip));
599 else if (stride_con == -1)
600 trip_count = gvn->transform(new (C) SubINode(init_trip,limit));
601 else
602 ShouldNotReachHere();
603 set_subtree_ctrl(trip_count);
604 //_loop.map(trip_count->_idx,loop(limit));
605 break;
606 case BoolTest::le: // Maybe convert to '<' case
607 limit = gvn->transform(new (C) AddINode(limit,one_p));
608 set_subtree_ctrl( limit );
609 hook->init_req(4, limit);
610
611 bt = BoolTest::lt;
612 // Make the new limit be in the same loop nest as the old limit
613 //_loop.map(limit->_idx,limit_loop);
614 // Fall into next case
615 case BoolTest::lt: { // Maybe convert to '!=' case
616 if (stride_con < 0) // Count down loop rolls through MAXINT
617 ShouldNotReachHere();
618 Node *range = gvn->transform(new (C) SubINode(limit,init_trip));
619 set_subtree_ctrl( range );
620 hook->init_req(0, range);
621
622 Node *bias = gvn->transform(new (C) AddINode(range,stride));
623 set_subtree_ctrl( bias );
624 hook->init_req(1, bias);
625
626 Node *bias1 = gvn->transform(new (C) AddINode(bias,one_m));
627 set_subtree_ctrl( bias1 );
628 hook->init_req(2, bias1);
629
630 trip_count = gvn->transform(new (C) DivINode(0,bias1,stride));
631 set_subtree_ctrl( trip_count );
632 hook->init_req(3, trip_count);
633 break;
634 }
635
636 case BoolTest::ge: // Maybe convert to '>' case
637 limit = gvn->transform(new (C) AddINode(limit,one_m));
638 set_subtree_ctrl( limit );
639 hook->init_req(4 ,limit);
640
641 bt = BoolTest::gt;
642 // Make the new limit be in the same loop nest as the old limit
643 //_loop.map(limit->_idx,limit_loop);
644 // Fall into next case
645 case BoolTest::gt: { // Maybe convert to '!=' case
646 if (stride_con > 0) // count up loop rolls through MININT
647 ShouldNotReachHere();
648 Node *range = gvn->transform(new (C) SubINode(limit,init_trip));
649 set_subtree_ctrl( range );
650 hook->init_req(0, range);
651
652 Node *bias = gvn->transform(new (C) AddINode(range,stride));
653 set_subtree_ctrl( bias );
654 hook->init_req(1, bias);
655
656 Node *bias1 = gvn->transform(new (C) AddINode(bias,one_p));
657 set_subtree_ctrl( bias1 );
658 hook->init_req(2, bias1);
659
660 trip_count = gvn->transform(new (C) DivINode(0,bias1,stride));
661 set_subtree_ctrl( trip_count );
662 hook->init_req(3, trip_count);
663 break;
664 }
665 } // switch( bt )
666
667 Node *span = gvn->transform(new (C) MulINode(trip_count,stride));
668 set_subtree_ctrl( span );
669 hook->init_req(5, span);
670
671 limit = gvn->transform(new (C) AddINode(span,init_trip));
672 set_subtree_ctrl( limit );
673
674 } // LoopLimitCheck
675
676 // Check for SafePoint on backedge and remove
677 Node *sfpt = x->in(LoopNode::LoopBackControl);
678 if (sfpt->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt)) {
679 lazy_replace( sfpt, iftrue );
680 if (loop->_safepts != NULL) {
681 loop->_safepts->yank(sfpt);
682 }
683 loop->_tail = iftrue;
684 }
685
686 // Build a canonical trip test.
687 // Clone code, as old values may be in use.
688 incr = incr->clone();
689 incr->set_req(1,phi);
690 incr->set_req(2,stride);
691 incr = _igvn.register_new_node_with_optimizer(incr);
692 set_early_ctrl( incr );
693 _igvn.hash_delete(phi);
694 phi->set_req_X( LoopNode::LoopBackControl, incr, &_igvn );
695
696 // If phi type is more restrictive than Int, raise to
697 // Int to prevent (almost) infinite recursion in igvn
698 // which can only handle integer types for constants or minint..maxint.
699 if (!TypeInt::INT->higher_equal(phi->bottom_type())) {
700 Node* nphi = PhiNode::make(phi->in(0), phi->in(LoopNode::EntryControl), TypeInt::INT);
701 nphi->set_req(LoopNode::LoopBackControl, phi->in(LoopNode::LoopBackControl));
702 nphi = _igvn.register_new_node_with_optimizer(nphi);
703 set_ctrl(nphi, get_ctrl(phi));
704 _igvn.replace_node(phi, nphi);
705 phi = nphi->as_Phi();
706 }
707 cmp = cmp->clone();
708 cmp->set_req(1,incr);
709 cmp->set_req(2,limit);
710 cmp = _igvn.register_new_node_with_optimizer(cmp);
711 set_ctrl(cmp, iff->in(0));
712
713 test = test->clone()->as_Bool();
714 (*(BoolTest*)&test->_test)._test = bt;
715 test->set_req(1,cmp);
716 _igvn.register_new_node_with_optimizer(test);
717 set_ctrl(test, iff->in(0));
718
719 // Replace the old IfNode with a new LoopEndNode
720 Node *lex = _igvn.register_new_node_with_optimizer(new (C) CountedLoopEndNode( iff->in(0), test, cl_prob, iff->as_If()->_fcnt ));
721 IfNode *le = lex->as_If();
722 uint dd = dom_depth(iff);
723 set_idom(le, le->in(0), dd); // Update dominance for loop exit
724 set_loop(le, loop);
725
726 // Get the loop-exit control
727 Node *iffalse = iff->as_If()->proj_out(!(iftrue_op == Op_IfTrue));
728
729 // Need to swap loop-exit and loop-back control?
730 if (iftrue_op == Op_IfFalse) {
731 Node *ift2=_igvn.register_new_node_with_optimizer(new (C) IfTrueNode (le));
732 Node *iff2=_igvn.register_new_node_with_optimizer(new (C) IfFalseNode(le));
733
734 loop->_tail = back_control = ift2;
735 set_loop(ift2, loop);
736 set_loop(iff2, get_loop(iffalse));
737
738 // Lazy update of 'get_ctrl' mechanism.
739 lazy_replace_proj( iffalse, iff2 );
740 lazy_replace_proj( iftrue, ift2 );
741
742 // Swap names
743 iffalse = iff2;
744 iftrue = ift2;
745 } else {
746 _igvn.hash_delete(iffalse);
747 _igvn.hash_delete(iftrue);
748 iffalse->set_req_X( 0, le, &_igvn );
749 iftrue ->set_req_X( 0, le, &_igvn );
750 }
751
752 set_idom(iftrue, le, dd+1);
753 set_idom(iffalse, le, dd+1);
754 assert(iff->outcnt() == 0, "should be dead now");
755 lazy_replace( iff, le ); // fix 'get_ctrl'
756
757 // Now setup a new CountedLoopNode to replace the existing LoopNode
758 CountedLoopNode *l = new (C) CountedLoopNode(init_control, back_control);
759 l->set_unswitch_count(x->as_Loop()->unswitch_count()); // Preserve
760 // The following assert is approximately true, and defines the intention
761 // of can_be_counted_loop. It fails, however, because phase->type
762 // is not yet initialized for this loop and its parts.
763 //assert(l->can_be_counted_loop(this), "sanity");
764 _igvn.register_new_node_with_optimizer(l);
765 set_loop(l, loop);
766 loop->_head = l;
767 // Fix all data nodes placed at the old loop head.
768 // Uses the lazy-update mechanism of 'get_ctrl'.
769 lazy_replace( x, l );
770 set_idom(l, init_control, dom_depth(x));
771
772 // Check for immediately preceding SafePoint and remove
773 Node *sfpt2 = le->in(0);
774 if (sfpt2->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt2)) {
775 lazy_replace( sfpt2, sfpt2->in(TypeFunc::Control));
776 if (loop->_safepts != NULL) {
777 loop->_safepts->yank(sfpt2);
778 }
779 }
780
781 // Free up intermediate goo
782 _igvn.remove_dead_node(hook);
783
784 #ifdef ASSERT
785 assert(l->is_valid_counted_loop(), "counted loop shape is messed up");
786 assert(l == loop->_head && l->phi() == phi && l->loopexit() == lex, "" );
787 #endif
788 #ifndef PRODUCT
789 if (TraceLoopOpts) {
790 tty->print("Counted ");
791 loop->dump_head();
792 }
793 #endif
794
795 C->print_method(PHASE_AFTER_CLOOPS, 3);
796
797 return true;
798 }
799
800 //----------------------exact_limit-------------------------------------------
801 Node* PhaseIdealLoop::exact_limit( IdealLoopTree *loop ) {
802 assert(loop->_head->is_CountedLoop(), "");
803 CountedLoopNode *cl = loop->_head->as_CountedLoop();
804 assert(cl->is_valid_counted_loop(), "");
805
806 if (!LoopLimitCheck || ABS(cl->stride_con()) == 1 ||
807 cl->limit()->Opcode() == Op_LoopLimit) {
808 // Old code has exact limit (it could be incorrect in case of int overflow).
809 // Loop limit is exact with stride == 1. And loop may already have exact limit.
810 return cl->limit();
811 }
812 Node *limit = NULL;
813 #ifdef ASSERT
814 BoolTest::mask bt = cl->loopexit()->test_trip();
815 assert(bt == BoolTest::lt || bt == BoolTest::gt, "canonical test is expected");
816 #endif
817 if (cl->has_exact_trip_count()) {
818 // Simple case: loop has constant boundaries.
819 // Use jlongs to avoid integer overflow.
820 int stride_con = cl->stride_con();
821 jlong init_con = cl->init_trip()->get_int();
822 jlong limit_con = cl->limit()->get_int();
823 julong trip_cnt = cl->trip_count();
824 jlong final_con = init_con + trip_cnt*stride_con;
825 int final_int = (int)final_con;
826 // The final value should be in integer range since the loop
827 // is counted and the limit was checked for overflow.
828 assert(final_con == (jlong)final_int, "final value should be integer");
829 limit = _igvn.intcon(final_int);
830 } else {
831 // Create new LoopLimit node to get exact limit (final iv value).
832 limit = new (C) LoopLimitNode(C, cl->init_trip(), cl->limit(), cl->stride());
833 register_new_node(limit, cl->in(LoopNode::EntryControl));
834 }
835 assert(limit != NULL, "sanity");
836 return limit;
837 }
838
839 //------------------------------Ideal------------------------------------------
840 // Return a node which is more "ideal" than the current node.
841 // Attempt to convert into a counted-loop.
842 Node *LoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
843 if (!can_be_counted_loop(phase)) {
844 phase->C->set_major_progress();
845 }
846 return RegionNode::Ideal(phase, can_reshape);
847 }
848
849
850 //=============================================================================
851 //------------------------------Ideal------------------------------------------
852 // Return a node which is more "ideal" than the current node.
853 // Attempt to convert into a counted-loop.
854 Node *CountedLoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
855 return RegionNode::Ideal(phase, can_reshape);
856 }
857
858 //------------------------------dump_spec--------------------------------------
859 // Dump special per-node info
860 #ifndef PRODUCT
861 void CountedLoopNode::dump_spec(outputStream *st) const {
862 LoopNode::dump_spec(st);
863 if (stride_is_con()) {
864 st->print("stride: %d ",stride_con());
865 }
866 if (is_pre_loop ()) st->print("pre of N%d" , _main_idx);
867 if (is_main_loop()) st->print("main of N%d", _idx);
868 if (is_post_loop()) st->print("post of N%d", _main_idx);
869 }
870 #endif
871
872 //=============================================================================
873 int CountedLoopEndNode::stride_con() const {
874 return stride()->bottom_type()->is_int()->get_con();
875 }
876
877 //=============================================================================
878 //------------------------------Value-----------------------------------------
879 const Type *LoopLimitNode::Value( PhaseTransform *phase ) const {
880 const Type* init_t = phase->type(in(Init));
881 const Type* limit_t = phase->type(in(Limit));
882 const Type* stride_t = phase->type(in(Stride));
883 // Either input is TOP ==> the result is TOP
884 if (init_t == Type::TOP) return Type::TOP;
885 if (limit_t == Type::TOP) return Type::TOP;
886 if (stride_t == Type::TOP) return Type::TOP;
887
888 int stride_con = stride_t->is_int()->get_con();
889 if (stride_con == 1)
890 return NULL; // Identity
891
892 if (init_t->is_int()->is_con() && limit_t->is_int()->is_con()) {
893 // Use jlongs to avoid integer overflow.
894 jlong init_con = init_t->is_int()->get_con();
895 jlong limit_con = limit_t->is_int()->get_con();
896 int stride_m = stride_con - (stride_con > 0 ? 1 : -1);
897 jlong trip_count = (limit_con - init_con + stride_m)/stride_con;
898 jlong final_con = init_con + stride_con*trip_count;
899 int final_int = (int)final_con;
900 // The final value should be in integer range since the loop
901 // is counted and the limit was checked for overflow.
902 assert(final_con == (jlong)final_int, "final value should be integer");
903 return TypeInt::make(final_int);
904 }
905
906 return bottom_type(); // TypeInt::INT
907 }
908
909 //------------------------------Ideal------------------------------------------
910 // Return a node which is more "ideal" than the current node.
911 Node *LoopLimitNode::Ideal(PhaseGVN *phase, bool can_reshape) {
912 if (phase->type(in(Init)) == Type::TOP ||
913 phase->type(in(Limit)) == Type::TOP ||
914 phase->type(in(Stride)) == Type::TOP)
915 return NULL; // Dead
916
917 int stride_con = phase->type(in(Stride))->is_int()->get_con();
918 if (stride_con == 1)
919 return NULL; // Identity
920
921 if (in(Init)->is_Con() && in(Limit)->is_Con())
922 return NULL; // Value
923
924 // Delay following optimizations until all loop optimizations
925 // done to keep Ideal graph simple.
926 if (!can_reshape || phase->C->major_progress())
927 return NULL;
928
929 const TypeInt* init_t = phase->type(in(Init) )->is_int();
930 const TypeInt* limit_t = phase->type(in(Limit))->is_int();
931 int stride_p;
932 jlong lim, ini;
933 julong max;
934 if (stride_con > 0) {
935 stride_p = stride_con;
936 lim = limit_t->_hi;
937 ini = init_t->_lo;
938 max = (julong)max_jint;
939 } else {
940 stride_p = -stride_con;
941 lim = init_t->_hi;
942 ini = limit_t->_lo;
943 max = (julong)min_jint;
944 }
945 julong range = lim - ini + stride_p;
946 if (range <= max) {
947 // Convert to integer expression if it is not overflow.
948 Node* stride_m = phase->intcon(stride_con - (stride_con > 0 ? 1 : -1));
949 Node *range = phase->transform(new (phase->C) SubINode(in(Limit), in(Init)));
950 Node *bias = phase->transform(new (phase->C) AddINode(range, stride_m));
951 Node *trip = phase->transform(new (phase->C) DivINode(0, bias, in(Stride)));
952 Node *span = phase->transform(new (phase->C) MulINode(trip, in(Stride)));
953 return new (phase->C) AddINode(span, in(Init)); // exact limit
954 }
955
956 if (is_power_of_2(stride_p) || // divisor is 2^n
957 !Matcher::has_match_rule(Op_LoopLimit)) { // or no specialized Mach node?
958 // Convert to long expression to avoid integer overflow
959 // and let igvn optimizer convert this division.
960 //
961 Node* init = phase->transform( new (phase->C) ConvI2LNode(in(Init)));
962 Node* limit = phase->transform( new (phase->C) ConvI2LNode(in(Limit)));
963 Node* stride = phase->longcon(stride_con);
964 Node* stride_m = phase->longcon(stride_con - (stride_con > 0 ? 1 : -1));
965
966 Node *range = phase->transform(new (phase->C) SubLNode(limit, init));
967 Node *bias = phase->transform(new (phase->C) AddLNode(range, stride_m));
968 Node *span;
969 if (stride_con > 0 && is_power_of_2(stride_p)) {
970 // bias >= 0 if stride >0, so if stride is 2^n we can use &(-stride)
971 // and avoid generating rounding for division. Zero trip guard should
972 // guarantee that init < limit but sometimes the guard is missing and
973 // we can get situation when init > limit. Note, for the empty loop
974 // optimization zero trip guard is generated explicitly which leaves
975 // only RCE predicate where exact limit is used and the predicate
976 // will simply fail forcing recompilation.
977 Node* neg_stride = phase->longcon(-stride_con);
978 span = phase->transform(new (phase->C) AndLNode(bias, neg_stride));
979 } else {
980 Node *trip = phase->transform(new (phase->C) DivLNode(0, bias, stride));
981 span = phase->transform(new (phase->C) MulLNode(trip, stride));
982 }
983 // Convert back to int
984 Node *span_int = phase->transform(new (phase->C) ConvL2INode(span));
985 return new (phase->C) AddINode(span_int, in(Init)); // exact limit
986 }
987
988 return NULL; // No progress
989 }
990
991 //------------------------------Identity---------------------------------------
992 // If stride == 1 return limit node.
993 Node *LoopLimitNode::Identity( PhaseTransform *phase ) {
994 int stride_con = phase->type(in(Stride))->is_int()->get_con();
995 if (stride_con == 1 || stride_con == -1)
996 return in(Limit);
997 return this;
998 }
999
1000 //=============================================================================
1001 //----------------------match_incr_with_optional_truncation--------------------
1002 // Match increment with optional truncation:
1003 // CHAR: (i+1)&0x7fff, BYTE: ((i+1)<<8)>>8, or SHORT: ((i+1)<<16)>>16
1004 // Return NULL for failure. Success returns the increment node.
1005 Node* CountedLoopNode::match_incr_with_optional_truncation(
1006 Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type) {
1007 // Quick cutouts:
1008 if (expr == NULL || expr->req() != 3) return NULL;
1009
1010 Node *t1 = NULL;
1011 Node *t2 = NULL;
1012 const TypeInt* trunc_t = TypeInt::INT;
1013 Node* n1 = expr;
1014 int n1op = n1->Opcode();
1015
1016 // Try to strip (n1 & M) or (n1 << N >> N) from n1.
1017 if (n1op == Op_AndI &&
1018 n1->in(2)->is_Con() &&
1019 n1->in(2)->bottom_type()->is_int()->get_con() == 0x7fff) {
1020 // %%% This check should match any mask of 2**K-1.
1021 t1 = n1;
1022 n1 = t1->in(1);
1023 n1op = n1->Opcode();
1024 trunc_t = TypeInt::CHAR;
1025 } else if (n1op == Op_RShiftI &&
1026 n1->in(1) != NULL &&
1027 n1->in(1)->Opcode() == Op_LShiftI &&
1028 n1->in(2) == n1->in(1)->in(2) &&
1029 n1->in(2)->is_Con()) {
1030 jint shift = n1->in(2)->bottom_type()->is_int()->get_con();
1031 // %%% This check should match any shift in [1..31].
1032 if (shift == 16 || shift == 8) {
1033 t1 = n1;
1034 t2 = t1->in(1);
1035 n1 = t2->in(1);
1036 n1op = n1->Opcode();
1037 if (shift == 16) {
1038 trunc_t = TypeInt::SHORT;
1039 } else if (shift == 8) {
1040 trunc_t = TypeInt::BYTE;
1041 }
1042 }
1043 }
1044
1045 // If (maybe after stripping) it is an AddI, we won:
1046 if (n1op == Op_AddI) {
1047 *trunc1 = t1;
1048 *trunc2 = t2;
1049 *trunc_type = trunc_t;
1050 return n1;
1051 }
1052
1053 // failed
1054 return NULL;
1055 }
1056
1057
1058 //------------------------------filtered_type--------------------------------
1059 // Return a type based on condition control flow
1060 // A successful return will be a type that is restricted due
1061 // to a series of dominating if-tests, such as:
1062 // if (i < 10) {
1063 // if (i > 0) {
1064 // here: "i" type is [1..10)
1065 // }
1066 // }
1067 // or a control flow merge
1068 // if (i < 10) {
1069 // do {
1070 // phi( , ) -- at top of loop type is [min_int..10)
1071 // i = ?
1072 // } while ( i < 10)
1073 //
1074 const TypeInt* PhaseIdealLoop::filtered_type( Node *n, Node* n_ctrl) {
1075 assert(n && n->bottom_type()->is_int(), "must be int");
1076 const TypeInt* filtered_t = NULL;
1077 if (!n->is_Phi()) {
1078 assert(n_ctrl != NULL || n_ctrl == C->top(), "valid control");
1079 filtered_t = filtered_type_from_dominators(n, n_ctrl);
1080
1081 } else {
1082 Node* phi = n->as_Phi();
1083 Node* region = phi->in(0);
1084 assert(n_ctrl == NULL || n_ctrl == region, "ctrl parameter must be region");
1085 if (region && region != C->top()) {
1086 for (uint i = 1; i < phi->req(); i++) {
1087 Node* val = phi->in(i);
1088 Node* use_c = region->in(i);
1089 const TypeInt* val_t = filtered_type_from_dominators(val, use_c);
1090 if (val_t != NULL) {
1091 if (filtered_t == NULL) {
1092 filtered_t = val_t;
1093 } else {
1094 filtered_t = filtered_t->meet(val_t)->is_int();
1095 }
1096 }
1097 }
1098 }
1099 }
1100 const TypeInt* n_t = _igvn.type(n)->is_int();
1101 if (filtered_t != NULL) {
1102 n_t = n_t->join(filtered_t)->is_int();
1103 }
1104 return n_t;
1105 }
1106
1107
1108 //------------------------------filtered_type_from_dominators--------------------------------
1109 // Return a possibly more restrictive type for val based on condition control flow of dominators
1110 const TypeInt* PhaseIdealLoop::filtered_type_from_dominators( Node* val, Node *use_ctrl) {
1111 if (val->is_Con()) {
1112 return val->bottom_type()->is_int();
1113 }
1114 uint if_limit = 10; // Max number of dominating if's visited
1115 const TypeInt* rtn_t = NULL;
1116
1117 if (use_ctrl && use_ctrl != C->top()) {
1118 Node* val_ctrl = get_ctrl(val);
1119 uint val_dom_depth = dom_depth(val_ctrl);
1120 Node* pred = use_ctrl;
1121 uint if_cnt = 0;
1122 while (if_cnt < if_limit) {
1123 if ((pred->Opcode() == Op_IfTrue || pred->Opcode() == Op_IfFalse)) {
1124 if_cnt++;
1125 const TypeInt* if_t = IfNode::filtered_int_type(&_igvn, val, pred);
1126 if (if_t != NULL) {
1127 if (rtn_t == NULL) {
1128 rtn_t = if_t;
1129 } else {
1130 rtn_t = rtn_t->join(if_t)->is_int();
1131 }
1132 }
1133 }
1134 pred = idom(pred);
1135 if (pred == NULL || pred == C->top()) {
1136 break;
1137 }
1138 // Stop if going beyond definition block of val
1139 if (dom_depth(pred) < val_dom_depth) {
1140 break;
1141 }
1142 }
1143 }
1144 return rtn_t;
1145 }
1146
1147
1148 //------------------------------dump_spec--------------------------------------
1149 // Dump special per-node info
1150 #ifndef PRODUCT
1151 void CountedLoopEndNode::dump_spec(outputStream *st) const {
1152 if( in(TestValue)->is_Bool() ) {
1153 BoolTest bt( test_trip()); // Added this for g++.
1154
1155 st->print("[");
1156 bt.dump_on(st);
1157 st->print("]");
1158 }
1159 st->print(" ");
1160 IfNode::dump_spec(st);
1161 }
1162 #endif
1163
1164 //=============================================================================
1165 //------------------------------is_member--------------------------------------
1166 // Is 'l' a member of 'this'?
1167 int IdealLoopTree::is_member( const IdealLoopTree *l ) const {
1168 while( l->_nest > _nest ) l = l->_parent;
1169 return l == this;
1170 }
1171
1172 //------------------------------set_nest---------------------------------------
1173 // Set loop tree nesting depth. Accumulate _has_call bits.
1174 int IdealLoopTree::set_nest( uint depth ) {
1175 _nest = depth;
1176 int bits = _has_call;
1177 if( _child ) bits |= _child->set_nest(depth+1);
1178 if( bits ) _has_call = 1;
1179 if( _next ) bits |= _next ->set_nest(depth );
1180 return bits;
1181 }
1182
1183 //------------------------------split_fall_in----------------------------------
1184 // Split out multiple fall-in edges from the loop header. Move them to a
1185 // private RegionNode before the loop. This becomes the loop landing pad.
1186 void IdealLoopTree::split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ) {
1187 PhaseIterGVN &igvn = phase->_igvn;
1188 uint i;
1189
1190 // Make a new RegionNode to be the landing pad.
1191 Node *landing_pad = new (phase->C) RegionNode( fall_in_cnt+1 );
1192 phase->set_loop(landing_pad,_parent);
1193 // Gather all the fall-in control paths into the landing pad
1194 uint icnt = fall_in_cnt;
1195 uint oreq = _head->req();
1196 for( i = oreq-1; i>0; i-- )
1197 if( !phase->is_member( this, _head->in(i) ) )
1198 landing_pad->set_req(icnt--,_head->in(i));
1199
1200 // Peel off PhiNode edges as well
1201 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1202 Node *oj = _head->fast_out(j);
1203 if( oj->is_Phi() ) {
1204 PhiNode* old_phi = oj->as_Phi();
1205 assert( old_phi->region() == _head, "" );
1206 igvn.hash_delete(old_phi); // Yank from hash before hacking edges
1207 Node *p = PhiNode::make_blank(landing_pad, old_phi);
1208 uint icnt = fall_in_cnt;
1209 for( i = oreq-1; i>0; i-- ) {
1210 if( !phase->is_member( this, _head->in(i) ) ) {
1211 p->init_req(icnt--, old_phi->in(i));
1212 // Go ahead and clean out old edges from old phi
1213 old_phi->del_req(i);
1214 }
1215 }
1216 // Search for CSE's here, because ZKM.jar does a lot of
1217 // loop hackery and we need to be a little incremental
1218 // with the CSE to avoid O(N^2) node blow-up.
1219 Node *p2 = igvn.hash_find_insert(p); // Look for a CSE
1220 if( p2 ) { // Found CSE
1221 p->destruct(); // Recover useless new node
1222 p = p2; // Use old node
1223 } else {
1224 igvn.register_new_node_with_optimizer(p, old_phi);
1225 }
1226 // Make old Phi refer to new Phi.
1227 old_phi->add_req(p);
1228 // Check for the special case of making the old phi useless and
1229 // disappear it. In JavaGrande I have a case where this useless
1230 // Phi is the loop limit and prevents recognizing a CountedLoop
1231 // which in turn prevents removing an empty loop.
1232 Node *id_old_phi = old_phi->Identity( &igvn );
1233 if( id_old_phi != old_phi ) { // Found a simple identity?
1234 // Note that I cannot call 'replace_node' here, because
1235 // that will yank the edge from old_phi to the Region and
1236 // I'm mid-iteration over the Region's uses.
1237 for (DUIterator_Last imin, i = old_phi->last_outs(imin); i >= imin; ) {
1238 Node* use = old_phi->last_out(i);
1239 igvn.rehash_node_delayed(use);
1240 uint uses_found = 0;
1241 for (uint j = 0; j < use->len(); j++) {
1242 if (use->in(j) == old_phi) {
1243 if (j < use->req()) use->set_req (j, id_old_phi);
1244 else use->set_prec(j, id_old_phi);
1245 uses_found++;
1246 }
1247 }
1248 i -= uses_found; // we deleted 1 or more copies of this edge
1249 }
1250 }
1251 igvn._worklist.push(old_phi);
1252 }
1253 }
1254 // Finally clean out the fall-in edges from the RegionNode
1255 for( i = oreq-1; i>0; i-- ) {
1256 if( !phase->is_member( this, _head->in(i) ) ) {
1257 _head->del_req(i);
1258 }
1259 }
1260 // Transform landing pad
1261 igvn.register_new_node_with_optimizer(landing_pad, _head);
1262 // Insert landing pad into the header
1263 _head->add_req(landing_pad);
1264 }
1265
1266 //------------------------------split_outer_loop-------------------------------
1267 // Split out the outermost loop from this shared header.
1268 void IdealLoopTree::split_outer_loop( PhaseIdealLoop *phase ) {
1269 PhaseIterGVN &igvn = phase->_igvn;
1270
1271 // Find index of outermost loop; it should also be my tail.
1272 uint outer_idx = 1;
1273 while( _head->in(outer_idx) != _tail ) outer_idx++;
1274
1275 // Make a LoopNode for the outermost loop.
1276 Node *ctl = _head->in(LoopNode::EntryControl);
1277 Node *outer = new (phase->C) LoopNode( ctl, _head->in(outer_idx) );
1278 outer = igvn.register_new_node_with_optimizer(outer, _head);
1279 phase->set_created_loop_node();
1280
1281 // Outermost loop falls into '_head' loop
1282 _head->set_req(LoopNode::EntryControl, outer);
1283 _head->del_req(outer_idx);
1284 // Split all the Phis up between '_head' loop and 'outer' loop.
1285 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1286 Node *out = _head->fast_out(j);
1287 if( out->is_Phi() ) {
1288 PhiNode *old_phi = out->as_Phi();
1289 assert( old_phi->region() == _head, "" );
1290 Node *phi = PhiNode::make_blank(outer, old_phi);
1291 phi->init_req(LoopNode::EntryControl, old_phi->in(LoopNode::EntryControl));
1292 phi->init_req(LoopNode::LoopBackControl, old_phi->in(outer_idx));
1293 phi = igvn.register_new_node_with_optimizer(phi, old_phi);
1294 // Make old Phi point to new Phi on the fall-in path
1295 igvn.replace_input_of(old_phi, LoopNode::EntryControl, phi);
1296 old_phi->del_req(outer_idx);
1297 }
1298 }
1299
1300 // Use the new loop head instead of the old shared one
1301 _head = outer;
1302 phase->set_loop(_head, this);
1303 }
1304
1305 //------------------------------fix_parent-------------------------------------
1306 static void fix_parent( IdealLoopTree *loop, IdealLoopTree *parent ) {
1307 loop->_parent = parent;
1308 if( loop->_child ) fix_parent( loop->_child, loop );
1309 if( loop->_next ) fix_parent( loop->_next , parent );
1310 }
1311
1312 //------------------------------estimate_path_freq-----------------------------
1313 static float estimate_path_freq( Node *n ) {
1314 // Try to extract some path frequency info
1315 IfNode *iff;
1316 for( int i = 0; i < 50; i++ ) { // Skip through a bunch of uncommon tests
1317 uint nop = n->Opcode();
1318 if( nop == Op_SafePoint ) { // Skip any safepoint
1319 n = n->in(0);
1320 continue;
1321 }
1322 if( nop == Op_CatchProj ) { // Get count from a prior call
1323 // Assume call does not always throw exceptions: means the call-site
1324 // count is also the frequency of the fall-through path.
1325 assert( n->is_CatchProj(), "" );
1326 if( ((CatchProjNode*)n)->_con != CatchProjNode::fall_through_index )
1327 return 0.0f; // Assume call exception path is rare
1328 Node *call = n->in(0)->in(0)->in(0);
1329 assert( call->is_Call(), "expect a call here" );
1330 const JVMState *jvms = ((CallNode*)call)->jvms();
1331 ciMethodData* methodData = jvms->method()->method_data();
1332 if (!methodData->is_mature()) return 0.0f; // No call-site data
1333 ciProfileData* data = methodData->bci_to_data(jvms->bci());
1334 if ((data == NULL) || !data->is_CounterData()) {
1335 // no call profile available, try call's control input
1336 n = n->in(0);
1337 continue;
1338 }
1339 return data->as_CounterData()->count()/FreqCountInvocations;
1340 }
1341 // See if there's a gating IF test
1342 Node *n_c = n->in(0);
1343 if( !n_c->is_If() ) break; // No estimate available
1344 iff = n_c->as_If();
1345 if( iff->_fcnt != COUNT_UNKNOWN ) // Have a valid count?
1346 // Compute how much count comes on this path
1347 return ((nop == Op_IfTrue) ? iff->_prob : 1.0f - iff->_prob) * iff->_fcnt;
1348 // Have no count info. Skip dull uncommon-trap like branches.
1349 if( (nop == Op_IfTrue && iff->_prob < PROB_LIKELY_MAG(5)) ||
1350 (nop == Op_IfFalse && iff->_prob > PROB_UNLIKELY_MAG(5)) )
1351 break;
1352 // Skip through never-taken branch; look for a real loop exit.
1353 n = iff->in(0);
1354 }
1355 return 0.0f; // No estimate available
1356 }
1357
1358 //------------------------------merge_many_backedges---------------------------
1359 // Merge all the backedges from the shared header into a private Region.
1360 // Feed that region as the one backedge to this loop.
1361 void IdealLoopTree::merge_many_backedges( PhaseIdealLoop *phase ) {
1362 uint i;
1363
1364 // Scan for the top 2 hottest backedges
1365 float hotcnt = 0.0f;
1366 float warmcnt = 0.0f;
1367 uint hot_idx = 0;
1368 // Loop starts at 2 because slot 1 is the fall-in path
1369 for( i = 2; i < _head->req(); i++ ) {
1370 float cnt = estimate_path_freq(_head->in(i));
1371 if( cnt > hotcnt ) { // Grab hottest path
1372 warmcnt = hotcnt;
1373 hotcnt = cnt;
1374 hot_idx = i;
1375 } else if( cnt > warmcnt ) { // And 2nd hottest path
1376 warmcnt = cnt;
1377 }
1378 }
1379
1380 // See if the hottest backedge is worthy of being an inner loop
1381 // by being much hotter than the next hottest backedge.
1382 if( hotcnt <= 0.0001 ||
1383 hotcnt < 2.0*warmcnt ) hot_idx = 0;// No hot backedge
1384
1385 // Peel out the backedges into a private merge point; peel
1386 // them all except optionally hot_idx.
1387 PhaseIterGVN &igvn = phase->_igvn;
1388
1389 Node *hot_tail = NULL;
1390 // Make a Region for the merge point
1391 Node *r = new (phase->C) RegionNode(1);
1392 for( i = 2; i < _head->req(); i++ ) {
1393 if( i != hot_idx )
1394 r->add_req( _head->in(i) );
1395 else hot_tail = _head->in(i);
1396 }
1397 igvn.register_new_node_with_optimizer(r, _head);
1398 // Plug region into end of loop _head, followed by hot_tail
1399 while( _head->req() > 3 ) _head->del_req( _head->req()-1 );
1400 _head->set_req(2, r);
1401 if( hot_idx ) _head->add_req(hot_tail);
1402
1403 // Split all the Phis up between '_head' loop and the Region 'r'
1404 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1405 Node *out = _head->fast_out(j);
1406 if( out->is_Phi() ) {
1407 PhiNode* n = out->as_Phi();
1408 igvn.hash_delete(n); // Delete from hash before hacking edges
1409 Node *hot_phi = NULL;
1410 Node *phi = new (phase->C) PhiNode(r, n->type(), n->adr_type());
1411 // Check all inputs for the ones to peel out
1412 uint j = 1;
1413 for( uint i = 2; i < n->req(); i++ ) {
1414 if( i != hot_idx )
1415 phi->set_req( j++, n->in(i) );
1416 else hot_phi = n->in(i);
1417 }
1418 // Register the phi but do not transform until whole place transforms
1419 igvn.register_new_node_with_optimizer(phi, n);
1420 // Add the merge phi to the old Phi
1421 while( n->req() > 3 ) n->del_req( n->req()-1 );
1422 n->set_req(2, phi);
1423 if( hot_idx ) n->add_req(hot_phi);
1424 }
1425 }
1426
1427
1428 // Insert a new IdealLoopTree inserted below me. Turn it into a clone
1429 // of self loop tree. Turn self into a loop headed by _head and with
1430 // tail being the new merge point.
1431 IdealLoopTree *ilt = new IdealLoopTree( phase, _head, _tail );
1432 phase->set_loop(_tail,ilt); // Adjust tail
1433 _tail = r; // Self's tail is new merge point
1434 phase->set_loop(r,this);
1435 ilt->_child = _child; // New guy has my children
1436 _child = ilt; // Self has new guy as only child
1437 ilt->_parent = this; // new guy has self for parent
1438 ilt->_nest = _nest; // Same nesting depth (for now)
1439
1440 // Starting with 'ilt', look for child loop trees using the same shared
1441 // header. Flatten these out; they will no longer be loops in the end.
1442 IdealLoopTree **pilt = &_child;
1443 while( ilt ) {
1444 if( ilt->_head == _head ) {
1445 uint i;
1446 for( i = 2; i < _head->req(); i++ )
1447 if( _head->in(i) == ilt->_tail )
1448 break; // Still a loop
1449 if( i == _head->req() ) { // No longer a loop
1450 // Flatten ilt. Hang ilt's "_next" list from the end of
1451 // ilt's '_child' list. Move the ilt's _child up to replace ilt.
1452 IdealLoopTree **cp = &ilt->_child;
1453 while( *cp ) cp = &(*cp)->_next; // Find end of child list
1454 *cp = ilt->_next; // Hang next list at end of child list
1455 *pilt = ilt->_child; // Move child up to replace ilt
1456 ilt->_head = NULL; // Flag as a loop UNIONED into parent
1457 ilt = ilt->_child; // Repeat using new ilt
1458 continue; // do not advance over ilt->_child
1459 }
1460 assert( ilt->_tail == hot_tail, "expected to only find the hot inner loop here" );
1461 phase->set_loop(_head,ilt);
1462 }
1463 pilt = &ilt->_child; // Advance to next
1464 ilt = *pilt;
1465 }
1466
1467 if( _child ) fix_parent( _child, this );
1468 }
1469
1470 //------------------------------beautify_loops---------------------------------
1471 // Split shared headers and insert loop landing pads.
1472 // Insert a LoopNode to replace the RegionNode.
1473 // Return TRUE if loop tree is structurally changed.
1474 bool IdealLoopTree::beautify_loops( PhaseIdealLoop *phase ) {
1475 bool result = false;
1476 // Cache parts in locals for easy
1477 PhaseIterGVN &igvn = phase->_igvn;
1478
1479 igvn.hash_delete(_head); // Yank from hash before hacking edges
1480
1481 // Check for multiple fall-in paths. Peel off a landing pad if need be.
1482 int fall_in_cnt = 0;
1483 for( uint i = 1; i < _head->req(); i++ )
1484 if( !phase->is_member( this, _head->in(i) ) )
1485 fall_in_cnt++;
1486 assert( fall_in_cnt, "at least 1 fall-in path" );
1487 if( fall_in_cnt > 1 ) // Need a loop landing pad to merge fall-ins
1488 split_fall_in( phase, fall_in_cnt );
1489
1490 // Swap inputs to the _head and all Phis to move the fall-in edge to
1491 // the left.
1492 fall_in_cnt = 1;
1493 while( phase->is_member( this, _head->in(fall_in_cnt) ) )
1494 fall_in_cnt++;
1495 if( fall_in_cnt > 1 ) {
1496 // Since I am just swapping inputs I do not need to update def-use info
1497 Node *tmp = _head->in(1);
1498 _head->set_req( 1, _head->in(fall_in_cnt) );
1499 _head->set_req( fall_in_cnt, tmp );
1500 // Swap also all Phis
1501 for (DUIterator_Fast imax, i = _head->fast_outs(imax); i < imax; i++) {
1502 Node* phi = _head->fast_out(i);
1503 if( phi->is_Phi() ) {
1504 igvn.hash_delete(phi); // Yank from hash before hacking edges
1505 tmp = phi->in(1);
1506 phi->set_req( 1, phi->in(fall_in_cnt) );
1507 phi->set_req( fall_in_cnt, tmp );
1508 }
1509 }
1510 }
1511 assert( !phase->is_member( this, _head->in(1) ), "left edge is fall-in" );
1512 assert( phase->is_member( this, _head->in(2) ), "right edge is loop" );
1513
1514 // If I am a shared header (multiple backedges), peel off the many
1515 // backedges into a private merge point and use the merge point as
1516 // the one true backedge.
1517 if( _head->req() > 3 ) {
1518 // Merge the many backedges into a single backedge but leave
1519 // the hottest backedge as separate edge for the following peel.
1520 merge_many_backedges( phase );
1521 result = true;
1522 }
1523
1524 // If I have one hot backedge, peel off myself loop.
1525 // I better be the outermost loop.
1526 if (_head->req() > 3 && !_irreducible) {
1527 split_outer_loop( phase );
1528 result = true;
1529
1530 } else if (!_head->is_Loop() && !_irreducible) {
1531 // Make a new LoopNode to replace the old loop head
1532 Node *l = new (phase->C) LoopNode( _head->in(1), _head->in(2) );
1533 l = igvn.register_new_node_with_optimizer(l, _head);
1534 phase->set_created_loop_node();
1535 // Go ahead and replace _head
1536 phase->_igvn.replace_node( _head, l );
1537 _head = l;
1538 phase->set_loop(_head, this);
1539 }
1540
1541 // Now recursively beautify nested loops
1542 if( _child ) result |= _child->beautify_loops( phase );
1543 if( _next ) result |= _next ->beautify_loops( phase );
1544 return result;
1545 }
1546
1547 //------------------------------allpaths_check_safepts----------------------------
1548 // Allpaths backwards scan from loop tail, terminating each path at first safepoint
1549 // encountered. Helper for check_safepts.
1550 void IdealLoopTree::allpaths_check_safepts(VectorSet &visited, Node_List &stack) {
1551 assert(stack.size() == 0, "empty stack");
1552 stack.push(_tail);
1553 visited.Clear();
1554 visited.set(_tail->_idx);
1555 while (stack.size() > 0) {
1556 Node* n = stack.pop();
1557 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
1558 // Terminate this path
1559 } else if (n->Opcode() == Op_SafePoint) {
1560 if (_phase->get_loop(n) != this) {
1561 if (_required_safept == NULL) _required_safept = new Node_List();
1562 _required_safept->push(n); // save the one closest to the tail
1563 }
1564 // Terminate this path
1565 } else {
1566 uint start = n->is_Region() ? 1 : 0;
1567 uint end = n->is_Region() && !n->is_Loop() ? n->req() : start + 1;
1568 for (uint i = start; i < end; i++) {
1569 Node* in = n->in(i);
1570 assert(in->is_CFG(), "must be");
1571 if (!visited.test_set(in->_idx) && is_member(_phase->get_loop(in))) {
1572 stack.push(in);
1573 }
1574 }
1575 }
1576 }
1577 }
1578
1579 //------------------------------check_safepts----------------------------
1580 // Given dominators, try to find loops with calls that must always be
1581 // executed (call dominates loop tail). These loops do not need non-call
1582 // safepoints (ncsfpt).
1583 //
1584 // A complication is that a safepoint in a inner loop may be needed
1585 // by an outer loop. In the following, the inner loop sees it has a
1586 // call (block 3) on every path from the head (block 2) to the
1587 // backedge (arc 3->2). So it deletes the ncsfpt (non-call safepoint)
1588 // in block 2, _but_ this leaves the outer loop without a safepoint.
1589 //
1590 // entry 0
1591 // |
1592 // v
1593 // outer 1,2 +->1
1594 // | |
1595 // | v
1596 // | 2<---+ ncsfpt in 2
1597 // |_/|\ |
1598 // | v |
1599 // inner 2,3 / 3 | call in 3
1600 // / | |
1601 // v +--+
1602 // exit 4
1603 //
1604 //
1605 // This method creates a list (_required_safept) of ncsfpt nodes that must
1606 // be protected is created for each loop. When a ncsfpt maybe deleted, it
1607 // is first looked for in the lists for the outer loops of the current loop.
1608 //
1609 // The insights into the problem:
1610 // A) counted loops are okay
1611 // B) innermost loops are okay (only an inner loop can delete
1612 // a ncsfpt needed by an outer loop)
1613 // C) a loop is immune from an inner loop deleting a safepoint
1614 // if the loop has a call on the idom-path
1615 // D) a loop is also immune if it has a ncsfpt (non-call safepoint) on the
1616 // idom-path that is not in a nested loop
1617 // E) otherwise, an ncsfpt on the idom-path that is nested in an inner
1618 // loop needs to be prevented from deletion by an inner loop
1619 //
1620 // There are two analyses:
1621 // 1) The first, and cheaper one, scans the loop body from
1622 // tail to head following the idom (immediate dominator)
1623 // chain, looking for the cases (C,D,E) above.
1624 // Since inner loops are scanned before outer loops, there is summary
1625 // information about inner loops. Inner loops can be skipped over
1626 // when the tail of an inner loop is encountered.
1627 //
1628 // 2) The second, invoked if the first fails to find a call or ncsfpt on
1629 // the idom path (which is rare), scans all predecessor control paths
1630 // from the tail to the head, terminating a path when a call or sfpt
1631 // is encountered, to find the ncsfpt's that are closest to the tail.
1632 //
1633 void IdealLoopTree::check_safepts(VectorSet &visited, Node_List &stack) {
1634 // Bottom up traversal
1635 IdealLoopTree* ch = _child;
1636 if (_child) _child->check_safepts(visited, stack);
1637 if (_next) _next ->check_safepts(visited, stack);
1638
1639 if (!_head->is_CountedLoop() && !_has_sfpt && _parent != NULL && !_irreducible) {
1640 bool has_call = false; // call on dom-path
1641 bool has_local_ncsfpt = false; // ncsfpt on dom-path at this loop depth
1642 Node* nonlocal_ncsfpt = NULL; // ncsfpt on dom-path at a deeper depth
1643 // Scan the dom-path nodes from tail to head
1644 for (Node* n = tail(); n != _head; n = _phase->idom(n)) {
1645 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
1646 has_call = true;
1647 _has_sfpt = 1; // Then no need for a safept!
1648 break;
1649 } else if (n->Opcode() == Op_SafePoint) {
1650 if (_phase->get_loop(n) == this) {
1651 has_local_ncsfpt = true;
1652 break;
1653 }
1654 if (nonlocal_ncsfpt == NULL) {
1655 nonlocal_ncsfpt = n; // save the one closest to the tail
1656 }
1657 } else {
1658 IdealLoopTree* nlpt = _phase->get_loop(n);
1659 if (this != nlpt) {
1660 // If at an inner loop tail, see if the inner loop has already
1661 // recorded seeing a call on the dom-path (and stop.) If not,
1662 // jump to the head of the inner loop.
1663 assert(is_member(nlpt), "nested loop");
1664 Node* tail = nlpt->_tail;
1665 if (tail->in(0)->is_If()) tail = tail->in(0);
1666 if (n == tail) {
1667 // If inner loop has call on dom-path, so does outer loop
1668 if (nlpt->_has_sfpt) {
1669 has_call = true;
1670 _has_sfpt = 1;
1671 break;
1672 }
1673 // Skip to head of inner loop
1674 assert(_phase->is_dominator(_head, nlpt->_head), "inner head dominated by outer head");
1675 n = nlpt->_head;
1676 }
1677 }
1678 }
1679 }
1680 // Record safept's that this loop needs preserved when an
1681 // inner loop attempts to delete it's safepoints.
1682 if (_child != NULL && !has_call && !has_local_ncsfpt) {
1683 if (nonlocal_ncsfpt != NULL) {
1684 if (_required_safept == NULL) _required_safept = new Node_List();
1685 _required_safept->push(nonlocal_ncsfpt);
1686 } else {
1687 // Failed to find a suitable safept on the dom-path. Now use
1688 // an all paths walk from tail to head, looking for safepoints to preserve.
1689 allpaths_check_safepts(visited, stack);
1690 }
1691 }
1692 }
1693 }
1694
1695 //---------------------------is_deleteable_safept----------------------------
1696 // Is safept not required by an outer loop?
1697 bool PhaseIdealLoop::is_deleteable_safept(Node* sfpt) {
1698 assert(sfpt->Opcode() == Op_SafePoint, "");
1699 IdealLoopTree* lp = get_loop(sfpt)->_parent;
1700 while (lp != NULL) {
1701 Node_List* sfpts = lp->_required_safept;
1702 if (sfpts != NULL) {
1703 for (uint i = 0; i < sfpts->size(); i++) {
1704 if (sfpt == sfpts->at(i))
1705 return false;
1706 }
1707 }
1708 lp = lp->_parent;
1709 }
1710 return true;
1711 }
1712
1713 //---------------------------replace_parallel_iv-------------------------------
1714 // Replace parallel induction variable (parallel to trip counter)
1715 void PhaseIdealLoop::replace_parallel_iv(IdealLoopTree *loop) {
1716 assert(loop->_head->is_CountedLoop(), "");
1717 CountedLoopNode *cl = loop->_head->as_CountedLoop();
1718 if (!cl->is_valid_counted_loop())
1719 return; // skip malformed counted loop
1720 Node *incr = cl->incr();
1721 if (incr == NULL)
1722 return; // Dead loop?
1723 Node *init = cl->init_trip();
1724 Node *phi = cl->phi();
1725 int stride_con = cl->stride_con();
1726
1727 // Visit all children, looking for Phis
1728 for (DUIterator i = cl->outs(); cl->has_out(i); i++) {
1729 Node *out = cl->out(i);
1730 // Look for other phis (secondary IVs). Skip dead ones
1731 if (!out->is_Phi() || out == phi || !has_node(out))
1732 continue;
1733 PhiNode* phi2 = out->as_Phi();
1734 Node *incr2 = phi2->in( LoopNode::LoopBackControl );
1735 // Look for induction variables of the form: X += constant
1736 if (phi2->region() != loop->_head ||
1737 incr2->req() != 3 ||
1738 incr2->in(1) != phi2 ||
1739 incr2 == incr ||
1740 incr2->Opcode() != Op_AddI ||
1741 !incr2->in(2)->is_Con())
1742 continue;
1743
1744 // Check for parallel induction variable (parallel to trip counter)
1745 // via an affine function. In particular, count-down loops with
1746 // count-up array indices are common. We only RCE references off
1747 // the trip-counter, so we need to convert all these to trip-counter
1748 // expressions.
1749 Node *init2 = phi2->in( LoopNode::EntryControl );
1750 int stride_con2 = incr2->in(2)->get_int();
1751
1752 // The general case here gets a little tricky. We want to find the
1753 // GCD of all possible parallel IV's and make a new IV using this
1754 // GCD for the loop. Then all possible IVs are simple multiples of
1755 // the GCD. In practice, this will cover very few extra loops.
1756 // Instead we require 'stride_con2' to be a multiple of 'stride_con',
1757 // where +/-1 is the common case, but other integer multiples are
1758 // also easy to handle.
1759 int ratio_con = stride_con2/stride_con;
1760
1761 if ((ratio_con * stride_con) == stride_con2) { // Check for exact
1762 #ifndef PRODUCT
1763 if (TraceLoopOpts) {
1764 tty->print("Parallel IV: %d ", phi2->_idx);
1765 loop->dump_head();
1766 }
1767 #endif
1768 // Convert to using the trip counter. The parallel induction
1769 // variable differs from the trip counter by a loop-invariant
1770 // amount, the difference between their respective initial values.
1771 // It is scaled by the 'ratio_con'.
1772 Node* ratio = _igvn.intcon(ratio_con);
1773 set_ctrl(ratio, C->root());
1774 Node* ratio_init = new (C) MulINode(init, ratio);
1775 _igvn.register_new_node_with_optimizer(ratio_init, init);
1776 set_early_ctrl(ratio_init);
1777 Node* diff = new (C) SubINode(init2, ratio_init);
1778 _igvn.register_new_node_with_optimizer(diff, init2);
1779 set_early_ctrl(diff);
1780 Node* ratio_idx = new (C) MulINode(phi, ratio);
1781 _igvn.register_new_node_with_optimizer(ratio_idx, phi);
1782 set_ctrl(ratio_idx, cl);
1783 Node* add = new (C) AddINode(ratio_idx, diff);
1784 _igvn.register_new_node_with_optimizer(add);
1785 set_ctrl(add, cl);
1786 _igvn.replace_node( phi2, add );
1787 // Sometimes an induction variable is unused
1788 if (add->outcnt() == 0) {
1789 _igvn.remove_dead_node(add);
1790 }
1791 --i; // deleted this phi; rescan starting with next position
1792 continue;
1793 }
1794 }
1795 }
1796
1797 //------------------------------counted_loop-----------------------------------
1798 // Convert to counted loops where possible
1799 void IdealLoopTree::counted_loop( PhaseIdealLoop *phase ) {
1800
1801 // For grins, set the inner-loop flag here
1802 if (!_child) {
1803 if (_head->is_Loop()) _head->as_Loop()->set_inner_loop();
1804 }
1805
1806 if (_head->is_CountedLoop() ||
1807 phase->is_counted_loop(_head, this)) {
1808 _has_sfpt = 1; // Indicate we do not need a safepoint here
1809
1810 // Look for safepoints to remove.
1811 Node_List* sfpts = _safepts;
1812 if (sfpts != NULL) {
1813 for (uint i = 0; i < sfpts->size(); i++) {
1814 Node* n = sfpts->at(i);
1815 assert(phase->get_loop(n) == this, "");
1816 if (phase->is_deleteable_safept(n)) {
1817 phase->lazy_replace(n, n->in(TypeFunc::Control));
1818 }
1819 }
1820 }
1821
1822 // Look for induction variables
1823 phase->replace_parallel_iv(this);
1824
1825 } else if (_parent != NULL && !_irreducible) {
1826 // Not a counted loop.
1827 // Look for a safepoint on the idom-path.
1828 Node* sfpt = tail();
1829 for (; sfpt != _head; sfpt = phase->idom(sfpt)) {
1830 if (sfpt->Opcode() == Op_SafePoint && phase->get_loop(sfpt) == this)
1831 break; // Found one
1832 }
1833 // Delete other safepoints in this loop.
1834 Node_List* sfpts = _safepts;
1835 if (sfpts != NULL && sfpt != _head && sfpt->Opcode() == Op_SafePoint) {
1836 for (uint i = 0; i < sfpts->size(); i++) {
1837 Node* n = sfpts->at(i);
1838 assert(phase->get_loop(n) == this, "");
1839 if (n != sfpt && phase->is_deleteable_safept(n)) {
1840 phase->lazy_replace(n, n->in(TypeFunc::Control));
1841 }
1842 }
1843 }
1844 }
1845
1846 // Recursively
1847 if (_child) _child->counted_loop( phase );
1848 if (_next) _next ->counted_loop( phase );
1849 }
1850
1851 #ifndef PRODUCT
1852 //------------------------------dump_head--------------------------------------
1853 // Dump 1 liner for loop header info
1854 void IdealLoopTree::dump_head( ) const {
1855 for (uint i=0; i<_nest; i++)
1856 tty->print(" ");
1857 tty->print("Loop: N%d/N%d ",_head->_idx,_tail->_idx);
1858 if (_irreducible) tty->print(" IRREDUCIBLE");
1859 Node* entry = _head->in(LoopNode::EntryControl);
1860 if (LoopLimitCheck) {
1861 Node* predicate = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
1862 if (predicate != NULL ) {
1863 tty->print(" limit_check");
1864 entry = entry->in(0)->in(0);
1865 }
1866 }
1867 if (UseLoopPredicate) {
1868 entry = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
1869 if (entry != NULL) {
1870 tty->print(" predicated");
1871 }
1872 }
1873 if (_head->is_CountedLoop()) {
1874 CountedLoopNode *cl = _head->as_CountedLoop();
1875 tty->print(" counted");
1876
1877 Node* init_n = cl->init_trip();
1878 if (init_n != NULL && init_n->is_Con())
1879 tty->print(" [%d,", cl->init_trip()->get_int());
1880 else
1881 tty->print(" [int,");
1882 Node* limit_n = cl->limit();
1883 if (limit_n != NULL && limit_n->is_Con())
1884 tty->print("%d),", cl->limit()->get_int());
1885 else
1886 tty->print("int),");
1887 int stride_con = cl->stride_con();
1888 if (stride_con > 0) tty->print("+");
1889 tty->print("%d", stride_con);
1890
1891 tty->print(" (%d iters) ", (int)cl->profile_trip_cnt());
1892
1893 if (cl->is_pre_loop ()) tty->print(" pre" );
1894 if (cl->is_main_loop()) tty->print(" main");
1895 if (cl->is_post_loop()) tty->print(" post");
1896 }
1897 tty->cr();
1898 }
1899
1900 //------------------------------dump-------------------------------------------
1901 // Dump loops by loop tree
1902 void IdealLoopTree::dump( ) const {
1903 dump_head();
1904 if (_child) _child->dump();
1905 if (_next) _next ->dump();
1906 }
1907
1908 #endif
1909
1910 static void log_loop_tree(IdealLoopTree* root, IdealLoopTree* loop, CompileLog* log) {
1911 if (loop == root) {
1912 if (loop->_child != NULL) {
1913 log->begin_head("loop_tree");
1914 log->end_head();
1915 if( loop->_child ) log_loop_tree(root, loop->_child, log);
1916 log->tail("loop_tree");
1917 assert(loop->_next == NULL, "what?");
1918 }
1919 } else {
1920 Node* head = loop->_head;
1921 log->begin_head("loop");
1922 log->print(" idx='%d' ", head->_idx);
1923 if (loop->_irreducible) log->print("irreducible='1' ");
1924 if (head->is_Loop()) {
1925 if (head->as_Loop()->is_inner_loop()) log->print("inner_loop='1' ");
1926 if (head->as_Loop()->is_partial_peel_loop()) log->print("partial_peel_loop='1' ");
1927 }
1928 if (head->is_CountedLoop()) {
1929 CountedLoopNode* cl = head->as_CountedLoop();
1930 if (cl->is_pre_loop()) log->print("pre_loop='%d' ", cl->main_idx());
1931 if (cl->is_main_loop()) log->print("main_loop='%d' ", cl->_idx);
1932 if (cl->is_post_loop()) log->print("post_loop='%d' ", cl->main_idx());
1933 }
1934 log->end_head();
1935 if( loop->_child ) log_loop_tree(root, loop->_child, log);
1936 log->tail("loop");
1937 if( loop->_next ) log_loop_tree(root, loop->_next, log);
1938 }
1939 }
1940
1941 //---------------------collect_potentially_useful_predicates-----------------------
1942 // Helper function to collect potentially useful predicates to prevent them from
1943 // being eliminated by PhaseIdealLoop::eliminate_useless_predicates
1944 void PhaseIdealLoop::collect_potentially_useful_predicates(
1945 IdealLoopTree * loop, Unique_Node_List &useful_predicates) {
1946 if (loop->_child) { // child
1947 collect_potentially_useful_predicates(loop->_child, useful_predicates);
1948 }
1949
1950 // self (only loops that we can apply loop predication may use their predicates)
1951 if (loop->_head->is_Loop() &&
1952 !loop->_irreducible &&
1953 !loop->tail()->is_top()) {
1954 LoopNode* lpn = loop->_head->as_Loop();
1955 Node* entry = lpn->in(LoopNode::EntryControl);
1956 Node* predicate_proj = find_predicate(entry); // loop_limit_check first
1957 if (predicate_proj != NULL ) { // right pattern that can be used by loop predication
1958 assert(entry->in(0)->in(1)->in(1)->Opcode() == Op_Opaque1, "must be");
1959 useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one
1960 entry = entry->in(0)->in(0);
1961 }
1962 predicate_proj = find_predicate(entry); // Predicate
1963 if (predicate_proj != NULL ) {
1964 useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one
1965 }
1966 }
1967
1968 if (loop->_next) { // sibling
1969 collect_potentially_useful_predicates(loop->_next, useful_predicates);
1970 }
1971 }
1972
1973 //------------------------eliminate_useless_predicates-----------------------------
1974 // Eliminate all inserted predicates if they could not be used by loop predication.
1975 // Note: it will also eliminates loop limits check predicate since it also uses
1976 // Opaque1 node (see Parse::add_predicate()).
1977 void PhaseIdealLoop::eliminate_useless_predicates() {
1978 if (C->predicate_count() == 0)
1979 return; // no predicate left
1980
1981 Unique_Node_List useful_predicates; // to store useful predicates
1982 if (C->has_loops()) {
1983 collect_potentially_useful_predicates(_ltree_root->_child, useful_predicates);
1984 }
1985
1986 for (int i = C->predicate_count(); i > 0; i--) {
1987 Node * n = C->predicate_opaque1_node(i-1);
1988 assert(n->Opcode() == Op_Opaque1, "must be");
1989 if (!useful_predicates.member(n)) { // not in the useful list
1990 _igvn.replace_node(n, n->in(1));
1991 }
1992 }
1993 }
1994
1995 //------------------------process_expensive_nodes-----------------------------
1996 // Expensive nodes have their control input set to prevent the GVN
1997 // from commoning them and as a result forcing the resulting node to
1998 // be in a more frequent path. Use CFG information here, to change the
1999 // control inputs so that some expensive nodes can be commoned while
2000 // not executed more frequently.
2001 bool PhaseIdealLoop::process_expensive_nodes() {
2002 assert(OptimizeExpensiveOps, "optimization off?");
2003
2004 // Sort nodes to bring similar nodes together
2005 C->sort_expensive_nodes();
2006
2007 bool progress = false;
2008
2009 for (int i = 0; i < C->expensive_count(); ) {
2010 Node* n = C->expensive_node(i);
2011 int start = i;
2012 // Find nodes similar to n
2013 i++;
2014 for (; i < C->expensive_count() && Compile::cmp_expensive_nodes(n, C->expensive_node(i)) == 0; i++);
2015 int end = i;
2016 // And compare them two by two
2017 for (int j = start; j < end; j++) {
2018 Node* n1 = C->expensive_node(j);
2019 if (is_node_unreachable(n1)) {
2020 continue;
2021 }
2022 for (int k = j+1; k < end; k++) {
2023 Node* n2 = C->expensive_node(k);
2024 if (is_node_unreachable(n2)) {
2025 continue;
2026 }
2027
2028 assert(n1 != n2, "should be pair of nodes");
2029
2030 Node* c1 = n1->in(0);
2031 Node* c2 = n2->in(0);
2032
2033 Node* parent_c1 = c1;
2034 Node* parent_c2 = c2;
2035
2036 // The call to get_early_ctrl_for_expensive() moves the
2037 // expensive nodes up but stops at loops that are in a if
2038 // branch. See whether we can exit the loop and move above the
2039 // If.
2040 if (c1->is_Loop()) {
2041 parent_c1 = c1->in(1);
2042 }
2043 if (c2->is_Loop()) {
2044 parent_c2 = c2->in(1);
2045 }
2046
2047 if (parent_c1 == parent_c2) {
2048 _igvn._worklist.push(n1);
2049 _igvn._worklist.push(n2);
2050 continue;
2051 }
2052
2053 // Look for identical expensive node up the dominator chain.
2054 if (is_dominator(c1, c2)) {
2055 c2 = c1;
2056 } else if (is_dominator(c2, c1)) {
2057 c1 = c2;
2058 } else if (parent_c1->is_Proj() && parent_c1->in(0)->is_If() &&
2059 parent_c2->is_Proj() && parent_c1->in(0) == parent_c2->in(0)) {
2060 // Both branches have the same expensive node so move it up
2061 // before the if.
2062 c1 = c2 = idom(parent_c1->in(0));
2063 }
2064 // Do the actual moves
2065 if (n1->in(0) != c1) {
2066 _igvn.hash_delete(n1);
2067 n1->set_req(0, c1);
2068 _igvn.hash_insert(n1);
2069 _igvn._worklist.push(n1);
2070 progress = true;
2071 }
2072 if (n2->in(0) != c2) {
2073 _igvn.hash_delete(n2);
2074 n2->set_req(0, c2);
2075 _igvn.hash_insert(n2);
2076 _igvn._worklist.push(n2);
2077 progress = true;
2078 }
2079 }
2080 }
2081 }
2082
2083 return progress;
2084 }
2085
2086
2087 //=============================================================================
2088 //----------------------------build_and_optimize-------------------------------
2089 // Create a PhaseLoop. Build the ideal Loop tree. Map each Ideal Node to
2090 // its corresponding LoopNode. If 'optimize' is true, do some loop cleanups.
2091 void PhaseIdealLoop::build_and_optimize(bool do_split_ifs, bool skip_loop_opts) {
2092 ResourceMark rm;
2093
2094 int old_progress = C->major_progress();
2095 uint orig_worklist_size = _igvn._worklist.size();
2096
2097 // Reset major-progress flag for the driver's heuristics
2098 C->clear_major_progress();
2099
2100 #ifndef PRODUCT
2101 // Capture for later assert
2102 uint unique = C->unique();
2103 _loop_invokes++;
2104 _loop_work += unique;
2105 #endif
2106
2107 // True if the method has at least 1 irreducible loop
2108 _has_irreducible_loops = false;
2109
2110 _created_loop_node = false;
2111
2112 Arena *a = Thread::current()->resource_area();
2113 VectorSet visited(a);
2114 // Pre-grow the mapping from Nodes to IdealLoopTrees.
2115 _nodes.map(C->unique(), NULL);
2116 memset(_nodes.adr(), 0, wordSize * C->unique());
2117
2118 // Pre-build the top-level outermost loop tree entry
2119 _ltree_root = new IdealLoopTree( this, C->root(), C->root() );
2120 // Do not need a safepoint at the top level
2121 _ltree_root->_has_sfpt = 1;
2122
2123 // Initialize Dominators.
2124 // Checked in clone_loop_predicate() during beautify_loops().
2125 _idom_size = 0;
2126 _idom = NULL;
2127 _dom_depth = NULL;
2128 _dom_stk = NULL;
2129
2130 // Empty pre-order array
2131 allocate_preorders();
2132
2133 // Build a loop tree on the fly. Build a mapping from CFG nodes to
2134 // IdealLoopTree entries. Data nodes are NOT walked.
2135 build_loop_tree();
2136 // Check for bailout, and return
2137 if (C->failing()) {
2138 return;
2139 }
2140
2141 // No loops after all
2142 if( !_ltree_root->_child && !_verify_only ) C->set_has_loops(false);
2143
2144 // There should always be an outer loop containing the Root and Return nodes.
2145 // If not, we have a degenerate empty program. Bail out in this case.
2146 if (!has_node(C->root())) {
2147 if (!_verify_only) {
2148 C->clear_major_progress();
2149 C->record_method_not_compilable("empty program detected during loop optimization");
2150 }
2151 return;
2152 }
2153
2154 // Nothing to do, so get out
2155 bool stop_early = !C->has_loops() && !skip_loop_opts && !do_split_ifs && !_verify_me && !_verify_only;
2156 bool do_expensive_nodes = C->should_optimize_expensive_nodes(_igvn);
2157 if (stop_early && !do_expensive_nodes) {
2158 _igvn.optimize(); // Cleanup NeverBranches
2159 return;
2160 }
2161
2162 // Set loop nesting depth
2163 _ltree_root->set_nest( 0 );
2164
2165 // Split shared headers and insert loop landing pads.
2166 // Do not bother doing this on the Root loop of course.
2167 if( !_verify_me && !_verify_only && _ltree_root->_child ) {
2168 C->print_method(PHASE_BEFORE_BEAUTIFY_LOOPS, 3);
2169 if( _ltree_root->_child->beautify_loops( this ) ) {
2170 // Re-build loop tree!
2171 _ltree_root->_child = NULL;
2172 _nodes.clear();
2173 reallocate_preorders();
2174 build_loop_tree();
2175 // Check for bailout, and return
2176 if (C->failing()) {
2177 return;
2178 }
2179 // Reset loop nesting depth
2180 _ltree_root->set_nest( 0 );
2181
2182 C->print_method(PHASE_AFTER_BEAUTIFY_LOOPS, 3);
2183 }
2184 }
2185
2186 // Build Dominators for elision of NULL checks & loop finding.
2187 // Since nodes do not have a slot for immediate dominator, make
2188 // a persistent side array for that info indexed on node->_idx.
2189 _idom_size = C->unique();
2190 _idom = NEW_RESOURCE_ARRAY( Node*, _idom_size );
2191 _dom_depth = NEW_RESOURCE_ARRAY( uint, _idom_size );
2192 _dom_stk = NULL; // Allocated on demand in recompute_dom_depth
2193 memset( _dom_depth, 0, _idom_size * sizeof(uint) );
2194
2195 Dominators();
2196
2197 if (!_verify_only) {
2198 // As a side effect, Dominators removed any unreachable CFG paths
2199 // into RegionNodes. It doesn't do this test against Root, so
2200 // we do it here.
2201 for( uint i = 1; i < C->root()->req(); i++ ) {
2202 if( !_nodes[C->root()->in(i)->_idx] ) { // Dead path into Root?
2203 _igvn.delete_input_of(C->root(), i);
2204 i--; // Rerun same iteration on compressed edges
2205 }
2206 }
2207
2208 // Given dominators, try to find inner loops with calls that must
2209 // always be executed (call dominates loop tail). These loops do
2210 // not need a separate safepoint.
2211 Node_List cisstack(a);
2212 _ltree_root->check_safepts(visited, cisstack);
2213 }
2214
2215 // Walk the DATA nodes and place into loops. Find earliest control
2216 // node. For CFG nodes, the _nodes array starts out and remains
2217 // holding the associated IdealLoopTree pointer. For DATA nodes, the
2218 // _nodes array holds the earliest legal controlling CFG node.
2219
2220 // Allocate stack with enough space to avoid frequent realloc
2221 int stack_size = (C->unique() >> 1) + 16; // (unique>>1)+16 from Java2D stats
2222 Node_Stack nstack( a, stack_size );
2223
2224 visited.Clear();
2225 Node_List worklist(a);
2226 // Don't need C->root() on worklist since
2227 // it will be processed among C->top() inputs
2228 worklist.push( C->top() );
2229 visited.set( C->top()->_idx ); // Set C->top() as visited now
2230 build_loop_early( visited, worklist, nstack );
2231
2232 // Given early legal placement, try finding counted loops. This placement
2233 // is good enough to discover most loop invariants.
2234 if( !_verify_me && !_verify_only )
2235 _ltree_root->counted_loop( this );
2236
2237 // Find latest loop placement. Find ideal loop placement.
2238 visited.Clear();
2239 init_dom_lca_tags();
2240 // Need C->root() on worklist when processing outs
2241 worklist.push( C->root() );
2242 NOT_PRODUCT( C->verify_graph_edges(); )
2243 worklist.push( C->top() );
2244 build_loop_late( visited, worklist, nstack );
2245
2246 if (_verify_only) {
2247 // restore major progress flag
2248 for (int i = 0; i < old_progress; i++)
2249 C->set_major_progress();
2250 assert(C->unique() == unique, "verification mode made Nodes? ? ?");
2251 assert(_igvn._worklist.size() == orig_worklist_size, "shouldn't push anything");
2252 return;
2253 }
2254
2255 // clear out the dead code after build_loop_late
2256 while (_deadlist.size()) {
2257 _igvn.remove_globally_dead_node(_deadlist.pop());
2258 }
2259
2260 if (stop_early) {
2261 assert(do_expensive_nodes, "why are we here?");
2262 if (process_expensive_nodes()) {
2263 // If we made some progress when processing expensive nodes then
2264 // the IGVN may modify the graph in a way that will allow us to
2265 // make some more progress: we need to try processing expensive
2266 // nodes again.
2267 C->set_major_progress();
2268 }
2269 _igvn.optimize();
2270 return;
2271 }
2272
2273 // Some parser-inserted loop predicates could never be used by loop
2274 // predication or they were moved away from loop during some optimizations.
2275 // For example, peeling. Eliminate them before next loop optimizations.
2276 if (UseLoopPredicate || LoopLimitCheck) {
2277 eliminate_useless_predicates();
2278 }
2279
2280 #ifndef PRODUCT
2281 C->verify_graph_edges();
2282 if (_verify_me) { // Nested verify pass?
2283 // Check to see if the verify mode is broken
2284 assert(C->unique() == unique, "non-optimize mode made Nodes? ? ?");
2285 return;
2286 }
2287 if(VerifyLoopOptimizations) verify();
2288 if(TraceLoopOpts && C->has_loops()) {
2289 _ltree_root->dump();
2290 }
2291 #endif
2292
2293 if (skip_loop_opts) {
2294 // Cleanup any modified bits
2295 _igvn.optimize();
2296
2297 if (C->log() != NULL) {
2298 log_loop_tree(_ltree_root, _ltree_root, C->log());
2299 }
2300 return;
2301 }
2302
2303 if (ReassociateInvariants) {
2304 // Reassociate invariants and prep for split_thru_phi
2305 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
2306 IdealLoopTree* lpt = iter.current();
2307 if (!lpt->is_counted() || !lpt->is_inner()) continue;
2308
2309 lpt->reassociate_invariants(this);
2310
2311 // Because RCE opportunities can be masked by split_thru_phi,
2312 // look for RCE candidates and inhibit split_thru_phi
2313 // on just their loop-phi's for this pass of loop opts
2314 if (SplitIfBlocks && do_split_ifs) {
2315 if (lpt->policy_range_check(this)) {
2316 lpt->_rce_candidate = 1; // = true
2317 }
2318 }
2319 }
2320 }
2321
2322 // Check for aggressive application of split-if and other transforms
2323 // that require basic-block info (like cloning through Phi's)
2324 if( SplitIfBlocks && do_split_ifs ) {
2325 visited.Clear();
2326 split_if_with_blocks( visited, nstack );
2327 NOT_PRODUCT( if( VerifyLoopOptimizations ) verify(); );
2328 }
2329
2330 if (!C->major_progress() && do_expensive_nodes && process_expensive_nodes()) {
2331 C->set_major_progress();
2332 }
2333
2334 // Perform loop predication before iteration splitting
2335 if (C->has_loops() && !C->major_progress() && (C->predicate_count() > 0)) {
2336 _ltree_root->_child->loop_predication(this);
2337 }
2338
2339 if (OptimizeFill && UseLoopPredicate && C->has_loops() && !C->major_progress()) {
2340 if (do_intrinsify_fill()) {
2341 C->set_major_progress();
2342 }
2343 }
2344
2345 // Perform iteration-splitting on inner loops. Split iterations to avoid
2346 // range checks or one-shot null checks.
2347
2348 // If split-if's didn't hack the graph too bad (no CFG changes)
2349 // then do loop opts.
2350 if (C->has_loops() && !C->major_progress()) {
2351 memset( worklist.adr(), 0, worklist.Size()*sizeof(Node*) );
2352 _ltree_root->_child->iteration_split( this, worklist );
2353 // No verify after peeling! GCM has hoisted code out of the loop.
2354 // After peeling, the hoisted code could sink inside the peeled area.
2355 // The peeling code does not try to recompute the best location for
2356 // all the code before the peeled area, so the verify pass will always
2357 // complain about it.
2358 }
2359 // Do verify graph edges in any case
2360 NOT_PRODUCT( C->verify_graph_edges(); );
2361
2362 if (!do_split_ifs) {
2363 // We saw major progress in Split-If to get here. We forced a
2364 // pass with unrolling and not split-if, however more split-if's
2365 // might make progress. If the unrolling didn't make progress
2366 // then the major-progress flag got cleared and we won't try
2367 // another round of Split-If. In particular the ever-common
2368 // instance-of/check-cast pattern requires at least 2 rounds of
2369 // Split-If to clear out.
2370 C->set_major_progress();
2371 }
2372
2373 // Repeat loop optimizations if new loops were seen
2374 if (created_loop_node()) {
2375 C->set_major_progress();
2376 }
2377
2378 // Keep loop predicates and perform optimizations with them
2379 // until no more loop optimizations could be done.
2380 // After that switch predicates off and do more loop optimizations.
2381 if (!C->major_progress() && (C->predicate_count() > 0)) {
2382 C->cleanup_loop_predicates(_igvn);
2383 #ifndef PRODUCT
2384 if (TraceLoopOpts) {
2385 tty->print_cr("PredicatesOff");
2386 }
2387 #endif
2388 C->set_major_progress();
2389 }
2390
2391 // Convert scalar to superword operations at the end of all loop opts.
2392 if (UseSuperWord && C->has_loops() && !C->major_progress()) {
2393 // SuperWord transform
2394 SuperWord sw(this);
2395 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
2396 IdealLoopTree* lpt = iter.current();
2397 if (lpt->is_counted()) {
2398 sw.transform_loop(lpt);
2399 }
2400 }
2401 }
2402
2403 // Cleanup any modified bits
2404 _igvn.optimize();
2405
2406 // disable assert until issue with split_flow_path is resolved (6742111)
2407 // assert(!_has_irreducible_loops || C->parsed_irreducible_loop() || C->is_osr_compilation(),
2408 // "shouldn't introduce irreducible loops");
2409
2410 if (C->log() != NULL) {
2411 log_loop_tree(_ltree_root, _ltree_root, C->log());
2412 }
2413 }
2414
2415 #ifndef PRODUCT
2416 //------------------------------print_statistics-------------------------------
2417 int PhaseIdealLoop::_loop_invokes=0;// Count of PhaseIdealLoop invokes
2418 int PhaseIdealLoop::_loop_work=0; // Sum of PhaseIdealLoop x unique
2419 void PhaseIdealLoop::print_statistics() {
2420 tty->print_cr("PhaseIdealLoop=%d, sum _unique=%d", _loop_invokes, _loop_work);
2421 }
2422
2423 //------------------------------verify-----------------------------------------
2424 // Build a verify-only PhaseIdealLoop, and see that it agrees with me.
2425 static int fail; // debug only, so its multi-thread dont care
2426 void PhaseIdealLoop::verify() const {
2427 int old_progress = C->major_progress();
2428 ResourceMark rm;
2429 PhaseIdealLoop loop_verify( _igvn, this );
2430 VectorSet visited(Thread::current()->resource_area());
2431
2432 fail = 0;
2433 verify_compare( C->root(), &loop_verify, visited );
2434 assert( fail == 0, "verify loops failed" );
2435 // Verify loop structure is the same
2436 _ltree_root->verify_tree(loop_verify._ltree_root, NULL);
2437 // Reset major-progress. It was cleared by creating a verify version of
2438 // PhaseIdealLoop.
2439 for( int i=0; i<old_progress; i++ )
2440 C->set_major_progress();
2441 }
2442
2443 //------------------------------verify_compare---------------------------------
2444 // Make sure me and the given PhaseIdealLoop agree on key data structures
2445 void PhaseIdealLoop::verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const {
2446 if( !n ) return;
2447 if( visited.test_set( n->_idx ) ) return;
2448 if( !_nodes[n->_idx] ) { // Unreachable
2449 assert( !loop_verify->_nodes[n->_idx], "both should be unreachable" );
2450 return;
2451 }
2452
2453 uint i;
2454 for( i = 0; i < n->req(); i++ )
2455 verify_compare( n->in(i), loop_verify, visited );
2456
2457 // Check the '_nodes' block/loop structure
2458 i = n->_idx;
2459 if( has_ctrl(n) ) { // We have control; verify has loop or ctrl
2460 if( _nodes[i] != loop_verify->_nodes[i] &&
2461 get_ctrl_no_update(n) != loop_verify->get_ctrl_no_update(n) ) {
2462 tty->print("Mismatched control setting for: ");
2463 n->dump();
2464 if( fail++ > 10 ) return;
2465 Node *c = get_ctrl_no_update(n);
2466 tty->print("We have it as: ");
2467 if( c->in(0) ) c->dump();
2468 else tty->print_cr("N%d",c->_idx);
2469 tty->print("Verify thinks: ");
2470 if( loop_verify->has_ctrl(n) )
2471 loop_verify->get_ctrl_no_update(n)->dump();
2472 else
2473 loop_verify->get_loop_idx(n)->dump();
2474 tty->cr();
2475 }
2476 } else { // We have a loop
2477 IdealLoopTree *us = get_loop_idx(n);
2478 if( loop_verify->has_ctrl(n) ) {
2479 tty->print("Mismatched loop setting for: ");
2480 n->dump();
2481 if( fail++ > 10 ) return;
2482 tty->print("We have it as: ");
2483 us->dump();
2484 tty->print("Verify thinks: ");
2485 loop_verify->get_ctrl_no_update(n)->dump();
2486 tty->cr();
2487 } else if (!C->major_progress()) {
2488 // Loop selection can be messed up if we did a major progress
2489 // operation, like split-if. Do not verify in that case.
2490 IdealLoopTree *them = loop_verify->get_loop_idx(n);
2491 if( us->_head != them->_head || us->_tail != them->_tail ) {
2492 tty->print("Unequals loops for: ");
2493 n->dump();
2494 if( fail++ > 10 ) return;
2495 tty->print("We have it as: ");
2496 us->dump();
2497 tty->print("Verify thinks: ");
2498 them->dump();
2499 tty->cr();
2500 }
2501 }
2502 }
2503
2504 // Check for immediate dominators being equal
2505 if( i >= _idom_size ) {
2506 if( !n->is_CFG() ) return;
2507 tty->print("CFG Node with no idom: ");
2508 n->dump();
2509 return;
2510 }
2511 if( !n->is_CFG() ) return;
2512 if( n == C->root() ) return; // No IDOM here
2513
2514 assert(n->_idx == i, "sanity");
2515 Node *id = idom_no_update(n);
2516 if( id != loop_verify->idom_no_update(n) ) {
2517 tty->print("Unequals idoms for: ");
2518 n->dump();
2519 if( fail++ > 10 ) return;
2520 tty->print("We have it as: ");
2521 id->dump();
2522 tty->print("Verify thinks: ");
2523 loop_verify->idom_no_update(n)->dump();
2524 tty->cr();
2525 }
2526
2527 }
2528
2529 //------------------------------verify_tree------------------------------------
2530 // Verify that tree structures match. Because the CFG can change, siblings
2531 // within the loop tree can be reordered. We attempt to deal with that by
2532 // reordering the verify's loop tree if possible.
2533 void IdealLoopTree::verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const {
2534 assert( _parent == parent, "Badly formed loop tree" );
2535
2536 // Siblings not in same order? Attempt to re-order.
2537 if( _head != loop->_head ) {
2538 // Find _next pointer to update
2539 IdealLoopTree **pp = &loop->_parent->_child;
2540 while( *pp != loop )
2541 pp = &((*pp)->_next);
2542 // Find proper sibling to be next
2543 IdealLoopTree **nn = &loop->_next;
2544 while( (*nn) && (*nn)->_head != _head )
2545 nn = &((*nn)->_next);
2546
2547 // Check for no match.
2548 if( !(*nn) ) {
2549 // Annoyingly, irreducible loops can pick different headers
2550 // after a major_progress operation, so the rest of the loop
2551 // tree cannot be matched.
2552 if (_irreducible && Compile::current()->major_progress()) return;
2553 assert( 0, "failed to match loop tree" );
2554 }
2555
2556 // Move (*nn) to (*pp)
2557 IdealLoopTree *hit = *nn;
2558 *nn = hit->_next;
2559 hit->_next = loop;
2560 *pp = loop;
2561 loop = hit;
2562 // Now try again to verify
2563 }
2564
2565 assert( _head == loop->_head , "mismatched loop head" );
2566 Node *tail = _tail; // Inline a non-updating version of
2567 while( !tail->in(0) ) // the 'tail()' call.
2568 tail = tail->in(1);
2569 assert( tail == loop->_tail, "mismatched loop tail" );
2570
2571 // Counted loops that are guarded should be able to find their guards
2572 if( _head->is_CountedLoop() && _head->as_CountedLoop()->is_main_loop() ) {
2573 CountedLoopNode *cl = _head->as_CountedLoop();
2574 Node *init = cl->init_trip();
2575 Node *ctrl = cl->in(LoopNode::EntryControl);
2576 assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" );
2577 Node *iff = ctrl->in(0);
2578 assert( iff->Opcode() == Op_If, "" );
2579 Node *bol = iff->in(1);
2580 assert( bol->Opcode() == Op_Bool, "" );
2581 Node *cmp = bol->in(1);
2582 assert( cmp->Opcode() == Op_CmpI, "" );
2583 Node *add = cmp->in(1);
2584 Node *opaq;
2585 if( add->Opcode() == Op_Opaque1 ) {
2586 opaq = add;
2587 } else {
2588 assert( add->Opcode() == Op_AddI || add->Opcode() == Op_ConI , "" );
2589 assert( add == init, "" );
2590 opaq = cmp->in(2);
2591 }
2592 assert( opaq->Opcode() == Op_Opaque1, "" );
2593
2594 }
2595
2596 if (_child != NULL) _child->verify_tree(loop->_child, this);
2597 if (_next != NULL) _next ->verify_tree(loop->_next, parent);
2598 // Innermost loops need to verify loop bodies,
2599 // but only if no 'major_progress'
2600 int fail = 0;
2601 if (!Compile::current()->major_progress() && _child == NULL) {
2602 for( uint i = 0; i < _body.size(); i++ ) {
2603 Node *n = _body.at(i);
2604 if (n->outcnt() == 0) continue; // Ignore dead
2605 uint j;
2606 for( j = 0; j < loop->_body.size(); j++ )
2607 if( loop->_body.at(j) == n )
2608 break;
2609 if( j == loop->_body.size() ) { // Not found in loop body
2610 // Last ditch effort to avoid assertion: Its possible that we
2611 // have some users (so outcnt not zero) but are still dead.
2612 // Try to find from root.
2613 if (Compile::current()->root()->find(n->_idx)) {
2614 fail++;
2615 tty->print("We have that verify does not: ");
2616 n->dump();
2617 }
2618 }
2619 }
2620 for( uint i2 = 0; i2 < loop->_body.size(); i2++ ) {
2621 Node *n = loop->_body.at(i2);
2622 if (n->outcnt() == 0) continue; // Ignore dead
2623 uint j;
2624 for( j = 0; j < _body.size(); j++ )
2625 if( _body.at(j) == n )
2626 break;
2627 if( j == _body.size() ) { // Not found in loop body
2628 // Last ditch effort to avoid assertion: Its possible that we
2629 // have some users (so outcnt not zero) but are still dead.
2630 // Try to find from root.
2631 if (Compile::current()->root()->find(n->_idx)) {
2632 fail++;
2633 tty->print("Verify has that we do not: ");
2634 n->dump();
2635 }
2636 }
2637 }
2638 assert( !fail, "loop body mismatch" );
2639 }
2640 }
2641
2642 #endif
2643
2644 //------------------------------set_idom---------------------------------------
2645 void PhaseIdealLoop::set_idom(Node* d, Node* n, uint dom_depth) {
2646 uint idx = d->_idx;
2647 if (idx >= _idom_size) {
2648 uint newsize = _idom_size<<1;
2649 while( idx >= newsize ) {
2650 newsize <<= 1;
2651 }
2652 _idom = REALLOC_RESOURCE_ARRAY( Node*, _idom,_idom_size,newsize);
2653 _dom_depth = REALLOC_RESOURCE_ARRAY( uint, _dom_depth,_idom_size,newsize);
2654 memset( _dom_depth + _idom_size, 0, (newsize - _idom_size) * sizeof(uint) );
2655 _idom_size = newsize;
2656 }
2657 _idom[idx] = n;
2658 _dom_depth[idx] = dom_depth;
2659 }
2660
2661 //------------------------------recompute_dom_depth---------------------------------------
2662 // The dominator tree is constructed with only parent pointers.
2663 // This recomputes the depth in the tree by first tagging all
2664 // nodes as "no depth yet" marker. The next pass then runs up
2665 // the dom tree from each node marked "no depth yet", and computes
2666 // the depth on the way back down.
2667 void PhaseIdealLoop::recompute_dom_depth() {
2668 uint no_depth_marker = C->unique();
2669 uint i;
2670 // Initialize depth to "no depth yet"
2671 for (i = 0; i < _idom_size; i++) {
2672 if (_dom_depth[i] > 0 && _idom[i] != NULL) {
2673 _dom_depth[i] = no_depth_marker;
2674 }
2675 }
2676 if (_dom_stk == NULL) {
2677 uint init_size = C->unique() / 100; // Guess that 1/100 is a reasonable initial size.
2678 if (init_size < 10) init_size = 10;
2679 _dom_stk = new GrowableArray<uint>(init_size);
2680 }
2681 // Compute new depth for each node.
2682 for (i = 0; i < _idom_size; i++) {
2683 uint j = i;
2684 // Run up the dom tree to find a node with a depth
2685 while (_dom_depth[j] == no_depth_marker) {
2686 _dom_stk->push(j);
2687 j = _idom[j]->_idx;
2688 }
2689 // Compute the depth on the way back down this tree branch
2690 uint dd = _dom_depth[j] + 1;
2691 while (_dom_stk->length() > 0) {
2692 uint j = _dom_stk->pop();
2693 _dom_depth[j] = dd;
2694 dd++;
2695 }
2696 }
2697 }
2698
2699 //------------------------------sort-------------------------------------------
2700 // Insert 'loop' into the existing loop tree. 'innermost' is a leaf of the
2701 // loop tree, not the root.
2702 IdealLoopTree *PhaseIdealLoop::sort( IdealLoopTree *loop, IdealLoopTree *innermost ) {
2703 if( !innermost ) return loop; // New innermost loop
2704
2705 int loop_preorder = get_preorder(loop->_head); // Cache pre-order number
2706 assert( loop_preorder, "not yet post-walked loop" );
2707 IdealLoopTree **pp = &innermost; // Pointer to previous next-pointer
2708 IdealLoopTree *l = *pp; // Do I go before or after 'l'?
2709
2710 // Insert at start of list
2711 while( l ) { // Insertion sort based on pre-order
2712 if( l == loop ) return innermost; // Already on list!
2713 int l_preorder = get_preorder(l->_head); // Cache pre-order number
2714 assert( l_preorder, "not yet post-walked l" );
2715 // Check header pre-order number to figure proper nesting
2716 if( loop_preorder > l_preorder )
2717 break; // End of insertion
2718 // If headers tie (e.g., shared headers) check tail pre-order numbers.
2719 // Since I split shared headers, you'd think this could not happen.
2720 // BUT: I must first do the preorder numbering before I can discover I
2721 // have shared headers, so the split headers all get the same preorder
2722 // number as the RegionNode they split from.
2723 if( loop_preorder == l_preorder &&
2724 get_preorder(loop->_tail) < get_preorder(l->_tail) )
2725 break; // Also check for shared headers (same pre#)
2726 pp = &l->_parent; // Chain up list
2727 l = *pp;
2728 }
2729 // Link into list
2730 // Point predecessor to me
2731 *pp = loop;
2732 // Point me to successor
2733 IdealLoopTree *p = loop->_parent;
2734 loop->_parent = l; // Point me to successor
2735 if( p ) sort( p, innermost ); // Insert my parents into list as well
2736 return innermost;
2737 }
2738
2739 //------------------------------build_loop_tree--------------------------------
2740 // I use a modified Vick/Tarjan algorithm. I need pre- and a post- visit
2741 // bits. The _nodes[] array is mapped by Node index and holds a NULL for
2742 // not-yet-pre-walked, pre-order # for pre-but-not-post-walked and holds the
2743 // tightest enclosing IdealLoopTree for post-walked.
2744 //
2745 // During my forward walk I do a short 1-layer lookahead to see if I can find
2746 // a loop backedge with that doesn't have any work on the backedge. This
2747 // helps me construct nested loops with shared headers better.
2748 //
2749 // Once I've done the forward recursion, I do the post-work. For each child
2750 // I check to see if there is a backedge. Backedges define a loop! I
2751 // insert an IdealLoopTree at the target of the backedge.
2752 //
2753 // During the post-work I also check to see if I have several children
2754 // belonging to different loops. If so, then this Node is a decision point
2755 // where control flow can choose to change loop nests. It is at this
2756 // decision point where I can figure out how loops are nested. At this
2757 // time I can properly order the different loop nests from my children.
2758 // Note that there may not be any backedges at the decision point!
2759 //
2760 // Since the decision point can be far removed from the backedges, I can't
2761 // order my loops at the time I discover them. Thus at the decision point
2762 // I need to inspect loop header pre-order numbers to properly nest my
2763 // loops. This means I need to sort my childrens' loops by pre-order.
2764 // The sort is of size number-of-control-children, which generally limits
2765 // it to size 2 (i.e., I just choose between my 2 target loops).
2766 void PhaseIdealLoop::build_loop_tree() {
2767 // Allocate stack of size C->unique()/2 to avoid frequent realloc
2768 GrowableArray <Node *> bltstack(C->unique() >> 1);
2769 Node *n = C->root();
2770 bltstack.push(n);
2771 int pre_order = 1;
2772 int stack_size;
2773
2774 while ( ( stack_size = bltstack.length() ) != 0 ) {
2775 n = bltstack.top(); // Leave node on stack
2776 if ( !is_visited(n) ) {
2777 // ---- Pre-pass Work ----
2778 // Pre-walked but not post-walked nodes need a pre_order number.
2779
2780 set_preorder_visited( n, pre_order ); // set as visited
2781
2782 // ---- Scan over children ----
2783 // Scan first over control projections that lead to loop headers.
2784 // This helps us find inner-to-outer loops with shared headers better.
2785
2786 // Scan children's children for loop headers.
2787 for ( int i = n->outcnt() - 1; i >= 0; --i ) {
2788 Node* m = n->raw_out(i); // Child
2789 if( m->is_CFG() && !is_visited(m) ) { // Only for CFG children
2790 // Scan over children's children to find loop
2791 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
2792 Node* l = m->fast_out(j);
2793 if( is_visited(l) && // Been visited?
2794 !is_postvisited(l) && // But not post-visited
2795 get_preorder(l) < pre_order ) { // And smaller pre-order
2796 // Found! Scan the DFS down this path before doing other paths
2797 bltstack.push(m);
2798 break;
2799 }
2800 }
2801 }
2802 }
2803 pre_order++;
2804 }
2805 else if ( !is_postvisited(n) ) {
2806 // Note: build_loop_tree_impl() adds out edges on rare occasions,
2807 // such as com.sun.rsasign.am::a.
2808 // For non-recursive version, first, process current children.
2809 // On next iteration, check if additional children were added.
2810 for ( int k = n->outcnt() - 1; k >= 0; --k ) {
2811 Node* u = n->raw_out(k);
2812 if ( u->is_CFG() && !is_visited(u) ) {
2813 bltstack.push(u);
2814 }
2815 }
2816 if ( bltstack.length() == stack_size ) {
2817 // There were no additional children, post visit node now
2818 (void)bltstack.pop(); // Remove node from stack
2819 pre_order = build_loop_tree_impl( n, pre_order );
2820 // Check for bailout
2821 if (C->failing()) {
2822 return;
2823 }
2824 // Check to grow _preorders[] array for the case when
2825 // build_loop_tree_impl() adds new nodes.
2826 check_grow_preorders();
2827 }
2828 }
2829 else {
2830 (void)bltstack.pop(); // Remove post-visited node from stack
2831 }
2832 }
2833 }
2834
2835 //------------------------------build_loop_tree_impl---------------------------
2836 int PhaseIdealLoop::build_loop_tree_impl( Node *n, int pre_order ) {
2837 // ---- Post-pass Work ----
2838 // Pre-walked but not post-walked nodes need a pre_order number.
2839
2840 // Tightest enclosing loop for this Node
2841 IdealLoopTree *innermost = NULL;
2842
2843 // For all children, see if any edge is a backedge. If so, make a loop
2844 // for it. Then find the tightest enclosing loop for the self Node.
2845 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2846 Node* m = n->fast_out(i); // Child
2847 if( n == m ) continue; // Ignore control self-cycles
2848 if( !m->is_CFG() ) continue;// Ignore non-CFG edges
2849
2850 IdealLoopTree *l; // Child's loop
2851 if( !is_postvisited(m) ) { // Child visited but not post-visited?
2852 // Found a backedge
2853 assert( get_preorder(m) < pre_order, "should be backedge" );
2854 // Check for the RootNode, which is already a LoopNode and is allowed
2855 // to have multiple "backedges".
2856 if( m == C->root()) { // Found the root?
2857 l = _ltree_root; // Root is the outermost LoopNode
2858 } else { // Else found a nested loop
2859 // Insert a LoopNode to mark this loop.
2860 l = new IdealLoopTree(this, m, n);
2861 } // End of Else found a nested loop
2862 if( !has_loop(m) ) // If 'm' does not already have a loop set
2863 set_loop(m, l); // Set loop header to loop now
2864
2865 } else { // Else not a nested loop
2866 if( !_nodes[m->_idx] ) continue; // Dead code has no loop
2867 l = get_loop(m); // Get previously determined loop
2868 // If successor is header of a loop (nest), move up-loop till it
2869 // is a member of some outer enclosing loop. Since there are no
2870 // shared headers (I've split them already) I only need to go up
2871 // at most 1 level.
2872 while( l && l->_head == m ) // Successor heads loop?
2873 l = l->_parent; // Move up 1 for me
2874 // If this loop is not properly parented, then this loop
2875 // has no exit path out, i.e. its an infinite loop.
2876 if( !l ) {
2877 // Make loop "reachable" from root so the CFG is reachable. Basically
2878 // insert a bogus loop exit that is never taken. 'm', the loop head,
2879 // points to 'n', one (of possibly many) fall-in paths. There may be
2880 // many backedges as well.
2881
2882 // Here I set the loop to be the root loop. I could have, after
2883 // inserting a bogus loop exit, restarted the recursion and found my
2884 // new loop exit. This would make the infinite loop a first-class
2885 // loop and it would then get properly optimized. What's the use of
2886 // optimizing an infinite loop?
2887 l = _ltree_root; // Oops, found infinite loop
2888
2889 if (!_verify_only) {
2890 // Insert the NeverBranch between 'm' and it's control user.
2891 NeverBranchNode *iff = new (C) NeverBranchNode( m );
2892 _igvn.register_new_node_with_optimizer(iff);
2893 set_loop(iff, l);
2894 Node *if_t = new (C) CProjNode( iff, 0 );
2895 _igvn.register_new_node_with_optimizer(if_t);
2896 set_loop(if_t, l);
2897
2898 Node* cfg = NULL; // Find the One True Control User of m
2899 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
2900 Node* x = m->fast_out(j);
2901 if (x->is_CFG() && x != m && x != iff)
2902 { cfg = x; break; }
2903 }
2904 assert(cfg != NULL, "must find the control user of m");
2905 uint k = 0; // Probably cfg->in(0)
2906 while( cfg->in(k) != m ) k++; // But check incase cfg is a Region
2907 cfg->set_req( k, if_t ); // Now point to NeverBranch
2908
2909 // Now create the never-taken loop exit
2910 Node *if_f = new (C) CProjNode( iff, 1 );
2911 _igvn.register_new_node_with_optimizer(if_f);
2912 set_loop(if_f, l);
2913 // Find frame ptr for Halt. Relies on the optimizer
2914 // V-N'ing. Easier and quicker than searching through
2915 // the program structure.
2916 Node *frame = new (C) ParmNode( C->start(), TypeFunc::FramePtr );
2917 _igvn.register_new_node_with_optimizer(frame);
2918 // Halt & Catch Fire
2919 Node *halt = new (C) HaltNode( if_f, frame );
2920 _igvn.register_new_node_with_optimizer(halt);
2921 set_loop(halt, l);
2922 C->root()->add_req(halt);
2923 }
2924 set_loop(C->root(), _ltree_root);
2925 }
2926 }
2927 // Weeny check for irreducible. This child was already visited (this
2928 // IS the post-work phase). Is this child's loop header post-visited
2929 // as well? If so, then I found another entry into the loop.
2930 if (!_verify_only) {
2931 while( is_postvisited(l->_head) ) {
2932 // found irreducible
2933 l->_irreducible = 1; // = true
2934 l = l->_parent;
2935 _has_irreducible_loops = true;
2936 // Check for bad CFG here to prevent crash, and bailout of compile
2937 if (l == NULL) {
2938 C->record_method_not_compilable("unhandled CFG detected during loop optimization");
2939 return pre_order;
2940 }
2941 }
2942 C->set_has_irreducible_loop(_has_irreducible_loops);
2943 }
2944
2945 // This Node might be a decision point for loops. It is only if
2946 // it's children belong to several different loops. The sort call
2947 // does a trivial amount of work if there is only 1 child or all
2948 // children belong to the same loop. If however, the children
2949 // belong to different loops, the sort call will properly set the
2950 // _parent pointers to show how the loops nest.
2951 //
2952 // In any case, it returns the tightest enclosing loop.
2953 innermost = sort( l, innermost );
2954 }
2955
2956 // Def-use info will have some dead stuff; dead stuff will have no
2957 // loop decided on.
2958
2959 // Am I a loop header? If so fix up my parent's child and next ptrs.
2960 if( innermost && innermost->_head == n ) {
2961 assert( get_loop(n) == innermost, "" );
2962 IdealLoopTree *p = innermost->_parent;
2963 IdealLoopTree *l = innermost;
2964 while( p && l->_head == n ) {
2965 l->_next = p->_child; // Put self on parents 'next child'
2966 p->_child = l; // Make self as first child of parent
2967 l = p; // Now walk up the parent chain
2968 p = l->_parent;
2969 }
2970 } else {
2971 // Note that it is possible for a LoopNode to reach here, if the
2972 // backedge has been made unreachable (hence the LoopNode no longer
2973 // denotes a Loop, and will eventually be removed).
2974
2975 // Record tightest enclosing loop for self. Mark as post-visited.
2976 set_loop(n, innermost);
2977 // Also record has_call flag early on
2978 if( innermost ) {
2979 if( n->is_Call() && !n->is_CallLeaf() && !n->is_macro() ) {
2980 // Do not count uncommon calls
2981 if( !n->is_CallStaticJava() || !n->as_CallStaticJava()->_name ) {
2982 Node *iff = n->in(0)->in(0);
2983 // No any calls for vectorized loops.
2984 if( UseSuperWord || !iff->is_If() ||
2985 (n->in(0)->Opcode() == Op_IfFalse &&
2986 (1.0 - iff->as_If()->_prob) >= 0.01) ||
2987 (iff->as_If()->_prob >= 0.01) )
2988 innermost->_has_call = 1;
2989 }
2990 } else if( n->is_Allocate() && n->as_Allocate()->_is_scalar_replaceable ) {
2991 // Disable loop optimizations if the loop has a scalar replaceable
2992 // allocation. This disabling may cause a potential performance lost
2993 // if the allocation is not eliminated for some reason.
2994 innermost->_allow_optimizations = false;
2995 innermost->_has_call = 1; // = true
2996 } else if (n->Opcode() == Op_SafePoint) {
2997 // Record all safepoints in this loop.
2998 if (innermost->_safepts == NULL) innermost->_safepts = new Node_List();
2999 innermost->_safepts->push(n);
3000 }
3001 }
3002 }
3003
3004 // Flag as post-visited now
3005 set_postvisited(n);
3006 return pre_order;
3007 }
3008
3009
3010 //------------------------------build_loop_early-------------------------------
3011 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
3012 // First pass computes the earliest controlling node possible. This is the
3013 // controlling input with the deepest dominating depth.
3014 void PhaseIdealLoop::build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) {
3015 while (worklist.size() != 0) {
3016 // Use local variables nstack_top_n & nstack_top_i to cache values
3017 // on nstack's top.
3018 Node *nstack_top_n = worklist.pop();
3019 uint nstack_top_i = 0;
3020 //while_nstack_nonempty:
3021 while (true) {
3022 // Get parent node and next input's index from stack's top.
3023 Node *n = nstack_top_n;
3024 uint i = nstack_top_i;
3025 uint cnt = n->req(); // Count of inputs
3026 if (i == 0) { // Pre-process the node.
3027 if( has_node(n) && // Have either loop or control already?
3028 !has_ctrl(n) ) { // Have loop picked out already?
3029 // During "merge_many_backedges" we fold up several nested loops
3030 // into a single loop. This makes the members of the original
3031 // loop bodies pointing to dead loops; they need to move up
3032 // to the new UNION'd larger loop. I set the _head field of these
3033 // dead loops to NULL and the _parent field points to the owning
3034 // loop. Shades of UNION-FIND algorithm.
3035 IdealLoopTree *ilt;
3036 while( !(ilt = get_loop(n))->_head ) {
3037 // Normally I would use a set_loop here. But in this one special
3038 // case, it is legal (and expected) to change what loop a Node
3039 // belongs to.
3040 _nodes.map(n->_idx, (Node*)(ilt->_parent) );
3041 }
3042 // Remove safepoints ONLY if I've already seen I don't need one.
3043 // (the old code here would yank a 2nd safepoint after seeing a
3044 // first one, even though the 1st did not dominate in the loop body
3045 // and thus could be avoided indefinitely)
3046 if( !_verify_only && !_verify_me && ilt->_has_sfpt && n->Opcode() == Op_SafePoint &&
3047 is_deleteable_safept(n)) {
3048 Node *in = n->in(TypeFunc::Control);
3049 lazy_replace(n,in); // Pull safepoint now
3050 if (ilt->_safepts != NULL) {
3051 ilt->_safepts->yank(n);
3052 }
3053 // Carry on with the recursion "as if" we are walking
3054 // only the control input
3055 if( !visited.test_set( in->_idx ) ) {
3056 worklist.push(in); // Visit this guy later, using worklist
3057 }
3058 // Get next node from nstack:
3059 // - skip n's inputs processing by setting i > cnt;
3060 // - we also will not call set_early_ctrl(n) since
3061 // has_node(n) == true (see the condition above).
3062 i = cnt + 1;
3063 }
3064 }
3065 } // if (i == 0)
3066
3067 // Visit all inputs
3068 bool done = true; // Assume all n's inputs will be processed
3069 while (i < cnt) {
3070 Node *in = n->in(i);
3071 ++i;
3072 if (in == NULL) continue;
3073 if (in->pinned() && !in->is_CFG())
3074 set_ctrl(in, in->in(0));
3075 int is_visited = visited.test_set( in->_idx );
3076 if (!has_node(in)) { // No controlling input yet?
3077 assert( !in->is_CFG(), "CFG Node with no controlling input?" );
3078 assert( !is_visited, "visit only once" );
3079 nstack.push(n, i); // Save parent node and next input's index.
3080 nstack_top_n = in; // Process current input now.
3081 nstack_top_i = 0;
3082 done = false; // Not all n's inputs processed.
3083 break; // continue while_nstack_nonempty;
3084 } else if (!is_visited) {
3085 // This guy has a location picked out for him, but has not yet
3086 // been visited. Happens to all CFG nodes, for instance.
3087 // Visit him using the worklist instead of recursion, to break
3088 // cycles. Since he has a location already we do not need to
3089 // find his location before proceeding with the current Node.
3090 worklist.push(in); // Visit this guy later, using worklist
3091 }
3092 }
3093 if (done) {
3094 // All of n's inputs have been processed, complete post-processing.
3095
3096 // Compute earliest point this Node can go.
3097 // CFG, Phi, pinned nodes already know their controlling input.
3098 if (!has_node(n)) {
3099 // Record earliest legal location
3100 set_early_ctrl( n );
3101 }
3102 if (nstack.is_empty()) {
3103 // Finished all nodes on stack.
3104 // Process next node on the worklist.
3105 break;
3106 }
3107 // Get saved parent node and next input's index.
3108 nstack_top_n = nstack.node();
3109 nstack_top_i = nstack.index();
3110 nstack.pop();
3111 }
3112 } // while (true)
3113 }
3114 }
3115
3116 //------------------------------dom_lca_internal--------------------------------
3117 // Pair-wise LCA
3118 Node *PhaseIdealLoop::dom_lca_internal( Node *n1, Node *n2 ) const {
3119 if( !n1 ) return n2; // Handle NULL original LCA
3120 assert( n1->is_CFG(), "" );
3121 assert( n2->is_CFG(), "" );
3122 // find LCA of all uses
3123 uint d1 = dom_depth(n1);
3124 uint d2 = dom_depth(n2);
3125 while (n1 != n2) {
3126 if (d1 > d2) {
3127 n1 = idom(n1);
3128 d1 = dom_depth(n1);
3129 } else if (d1 < d2) {
3130 n2 = idom(n2);
3131 d2 = dom_depth(n2);
3132 } else {
3133 // Here d1 == d2. Due to edits of the dominator-tree, sections
3134 // of the tree might have the same depth. These sections have
3135 // to be searched more carefully.
3136
3137 // Scan up all the n1's with equal depth, looking for n2.
3138 Node *t1 = idom(n1);
3139 while (dom_depth(t1) == d1) {
3140 if (t1 == n2) return n2;
3141 t1 = idom(t1);
3142 }
3143 // Scan up all the n2's with equal depth, looking for n1.
3144 Node *t2 = idom(n2);
3145 while (dom_depth(t2) == d2) {
3146 if (t2 == n1) return n1;
3147 t2 = idom(t2);
3148 }
3149 // Move up to a new dominator-depth value as well as up the dom-tree.
3150 n1 = t1;
3151 n2 = t2;
3152 d1 = dom_depth(n1);
3153 d2 = dom_depth(n2);
3154 }
3155 }
3156 return n1;
3157 }
3158
3159 //------------------------------compute_idom-----------------------------------
3160 // Locally compute IDOM using dom_lca call. Correct only if the incoming
3161 // IDOMs are correct.
3162 Node *PhaseIdealLoop::compute_idom( Node *region ) const {
3163 assert( region->is_Region(), "" );
3164 Node *LCA = NULL;
3165 for( uint i = 1; i < region->req(); i++ ) {
3166 if( region->in(i) != C->top() )
3167 LCA = dom_lca( LCA, region->in(i) );
3168 }
3169 return LCA;
3170 }
3171
3172 bool PhaseIdealLoop::verify_dominance(Node* n, Node* use, Node* LCA, Node* early) {
3173 bool had_error = false;
3174 #ifdef ASSERT
3175 if (early != C->root()) {
3176 // Make sure that there's a dominance path from LCA to early
3177 Node* d = LCA;
3178 while (d != early) {
3179 if (d == C->root()) {
3180 dump_bad_graph("Bad graph detected in compute_lca_of_uses", n, early, LCA);
3181 tty->print_cr("*** Use %d isn't dominated by def %d ***", use->_idx, n->_idx);
3182 had_error = true;
3183 break;
3184 }
3185 d = idom(d);
3186 }
3187 }
3188 #endif
3189 return had_error;
3190 }
3191
3192
3193 Node* PhaseIdealLoop::compute_lca_of_uses(Node* n, Node* early, bool verify) {
3194 // Compute LCA over list of uses
3195 bool had_error = false;
3196 Node *LCA = NULL;
3197 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax && LCA != early; i++) {
3198 Node* c = n->fast_out(i);
3199 if (_nodes[c->_idx] == NULL)
3200 continue; // Skip the occasional dead node
3201 if( c->is_Phi() ) { // For Phis, we must land above on the path
3202 for( uint j=1; j<c->req(); j++ ) {// For all inputs
3203 if( c->in(j) == n ) { // Found matching input?
3204 Node *use = c->in(0)->in(j);
3205 if (_verify_only && use->is_top()) continue;
3206 LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
3207 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error;
3208 }
3209 }
3210 } else {
3211 // For CFG data-users, use is in the block just prior
3212 Node *use = has_ctrl(c) ? get_ctrl(c) : c->in(0);
3213 LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
3214 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error;
3215 }
3216 }
3217 assert(!had_error, "bad dominance");
3218 return LCA;
3219 }
3220
3221 //------------------------------get_late_ctrl----------------------------------
3222 // Compute latest legal control.
3223 Node *PhaseIdealLoop::get_late_ctrl( Node *n, Node *early ) {
3224 assert(early != NULL, "early control should not be NULL");
3225
3226 Node* LCA = compute_lca_of_uses(n, early);
3227 #ifdef ASSERT
3228 if (LCA == C->root() && LCA != early) {
3229 // def doesn't dominate uses so print some useful debugging output
3230 compute_lca_of_uses(n, early, true);
3231 }
3232 #endif
3233
3234 // if this is a load, check for anti-dependent stores
3235 // We use a conservative algorithm to identify potential interfering
3236 // instructions and for rescheduling the load. The users of the memory
3237 // input of this load are examined. Any use which is not a load and is
3238 // dominated by early is considered a potentially interfering store.
3239 // This can produce false positives.
3240 if (n->is_Load() && LCA != early) {
3241 Node_List worklist;
3242
3243 Node *mem = n->in(MemNode::Memory);
3244 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
3245 Node* s = mem->fast_out(i);
3246 worklist.push(s);
3247 }
3248 while(worklist.size() != 0 && LCA != early) {
3249 Node* s = worklist.pop();
3250 if (s->is_Load()) {
3251 continue;
3252 } else if (s->is_MergeMem()) {
3253 for (DUIterator_Fast imax, i = s->fast_outs(imax); i < imax; i++) {
3254 Node* s1 = s->fast_out(i);
3255 worklist.push(s1);
3256 }
3257 } else {
3258 Node *sctrl = has_ctrl(s) ? get_ctrl(s) : s->in(0);
3259 assert(sctrl != NULL || s->outcnt() == 0, "must have control");
3260 if (sctrl != NULL && !sctrl->is_top() && is_dominator(early, sctrl)) {
3261 LCA = dom_lca_for_get_late_ctrl(LCA, sctrl, n);
3262 }
3263 }
3264 }
3265 }
3266
3267 assert(LCA == find_non_split_ctrl(LCA), "unexpected late control");
3268 return LCA;
3269 }
3270
3271 // true if CFG node d dominates CFG node n
3272 bool PhaseIdealLoop::is_dominator(Node *d, Node *n) {
3273 if (d == n)
3274 return true;
3275 assert(d->is_CFG() && n->is_CFG(), "must have CFG nodes");
3276 uint dd = dom_depth(d);
3277 while (dom_depth(n) >= dd) {
3278 if (n == d)
3279 return true;
3280 n = idom(n);
3281 }
3282 return false;
3283 }
3284
3285 //------------------------------dom_lca_for_get_late_ctrl_internal-------------
3286 // Pair-wise LCA with tags.
3287 // Tag each index with the node 'tag' currently being processed
3288 // before advancing up the dominator chain using idom().
3289 // Later calls that find a match to 'tag' know that this path has already
3290 // been considered in the current LCA (which is input 'n1' by convention).
3291 // Since get_late_ctrl() is only called once for each node, the tag array
3292 // does not need to be cleared between calls to get_late_ctrl().
3293 // Algorithm trades a larger constant factor for better asymptotic behavior
3294 //
3295 Node *PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal( Node *n1, Node *n2, Node *tag ) {
3296 uint d1 = dom_depth(n1);
3297 uint d2 = dom_depth(n2);
3298
3299 do {
3300 if (d1 > d2) {
3301 // current lca is deeper than n2
3302 _dom_lca_tags.map(n1->_idx, tag);
3303 n1 = idom(n1);
3304 d1 = dom_depth(n1);
3305 } else if (d1 < d2) {
3306 // n2 is deeper than current lca
3307 Node *memo = _dom_lca_tags[n2->_idx];
3308 if( memo == tag ) {
3309 return n1; // Return the current LCA
3310 }
3311 _dom_lca_tags.map(n2->_idx, tag);
3312 n2 = idom(n2);
3313 d2 = dom_depth(n2);
3314 } else {
3315 // Here d1 == d2. Due to edits of the dominator-tree, sections
3316 // of the tree might have the same depth. These sections have
3317 // to be searched more carefully.
3318
3319 // Scan up all the n1's with equal depth, looking for n2.
3320 _dom_lca_tags.map(n1->_idx, tag);
3321 Node *t1 = idom(n1);
3322 while (dom_depth(t1) == d1) {
3323 if (t1 == n2) return n2;
3324 _dom_lca_tags.map(t1->_idx, tag);
3325 t1 = idom(t1);
3326 }
3327 // Scan up all the n2's with equal depth, looking for n1.
3328 _dom_lca_tags.map(n2->_idx, tag);
3329 Node *t2 = idom(n2);
3330 while (dom_depth(t2) == d2) {
3331 if (t2 == n1) return n1;
3332 _dom_lca_tags.map(t2->_idx, tag);
3333 t2 = idom(t2);
3334 }
3335 // Move up to a new dominator-depth value as well as up the dom-tree.
3336 n1 = t1;
3337 n2 = t2;
3338 d1 = dom_depth(n1);
3339 d2 = dom_depth(n2);
3340 }
3341 } while (n1 != n2);
3342 return n1;
3343 }
3344
3345 //------------------------------init_dom_lca_tags------------------------------
3346 // Tag could be a node's integer index, 32bits instead of 64bits in some cases
3347 // Intended use does not involve any growth for the array, so it could
3348 // be of fixed size.
3349 void PhaseIdealLoop::init_dom_lca_tags() {
3350 uint limit = C->unique() + 1;
3351 _dom_lca_tags.map( limit, NULL );
3352 #ifdef ASSERT
3353 for( uint i = 0; i < limit; ++i ) {
3354 assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer");
3355 }
3356 #endif // ASSERT
3357 }
3358
3359 //------------------------------clear_dom_lca_tags------------------------------
3360 // Tag could be a node's integer index, 32bits instead of 64bits in some cases
3361 // Intended use does not involve any growth for the array, so it could
3362 // be of fixed size.
3363 void PhaseIdealLoop::clear_dom_lca_tags() {
3364 uint limit = C->unique() + 1;
3365 _dom_lca_tags.map( limit, NULL );
3366 _dom_lca_tags.clear();
3367 #ifdef ASSERT
3368 for( uint i = 0; i < limit; ++i ) {
3369 assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer");
3370 }
3371 #endif // ASSERT
3372 }
3373
3374 //------------------------------build_loop_late--------------------------------
3375 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
3376 // Second pass finds latest legal placement, and ideal loop placement.
3377 void PhaseIdealLoop::build_loop_late( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) {
3378 while (worklist.size() != 0) {
3379 Node *n = worklist.pop();
3380 // Only visit once
3381 if (visited.test_set(n->_idx)) continue;
3382 uint cnt = n->outcnt();
3383 uint i = 0;
3384 while (true) {
3385 assert( _nodes[n->_idx], "no dead nodes" );
3386 // Visit all children
3387 if (i < cnt) {
3388 Node* use = n->raw_out(i);
3389 ++i;
3390 // Check for dead uses. Aggressively prune such junk. It might be
3391 // dead in the global sense, but still have local uses so I cannot
3392 // easily call 'remove_dead_node'.
3393 if( _nodes[use->_idx] != NULL || use->is_top() ) { // Not dead?
3394 // Due to cycles, we might not hit the same fixed point in the verify
3395 // pass as we do in the regular pass. Instead, visit such phis as
3396 // simple uses of the loop head.
3397 if( use->in(0) && (use->is_CFG() || use->is_Phi()) ) {
3398 if( !visited.test(use->_idx) )
3399 worklist.push(use);
3400 } else if( !visited.test_set(use->_idx) ) {
3401 nstack.push(n, i); // Save parent and next use's index.
3402 n = use; // Process all children of current use.
3403 cnt = use->outcnt();
3404 i = 0;
3405 }
3406 } else {
3407 // Do not visit around the backedge of loops via data edges.
3408 // push dead code onto a worklist
3409 _deadlist.push(use);
3410 }
3411 } else {
3412 // All of n's children have been processed, complete post-processing.
3413 build_loop_late_post(n);
3414 if (nstack.is_empty()) {
3415 // Finished all nodes on stack.
3416 // Process next node on the worklist.
3417 break;
3418 }
3419 // Get saved parent node and next use's index. Visit the rest of uses.
3420 n = nstack.node();
3421 cnt = n->outcnt();
3422 i = nstack.index();
3423 nstack.pop();
3424 }
3425 }
3426 }
3427 }
3428
3429 //------------------------------build_loop_late_post---------------------------
3430 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
3431 // Second pass finds latest legal placement, and ideal loop placement.
3432 void PhaseIdealLoop::build_loop_late_post( Node *n ) {
3433
3434 if (n->req() == 2 && n->Opcode() == Op_ConvI2L && !C->major_progress() && !_verify_only) {
3435 _igvn._worklist.push(n); // Maybe we'll normalize it, if no more loops.
3436 }
3437
3438 #ifdef ASSERT
3439 if (_verify_only && !n->is_CFG()) {
3440 // Check def-use domination.
3441 compute_lca_of_uses(n, get_ctrl(n), true /* verify */);
3442 }
3443 #endif
3444
3445 // CFG and pinned nodes already handled
3446 if( n->in(0) ) {
3447 if( n->in(0)->is_top() ) return; // Dead?
3448
3449 // We'd like +VerifyLoopOptimizations to not believe that Mod's/Loads
3450 // _must_ be pinned (they have to observe their control edge of course).
3451 // Unlike Stores (which modify an unallocable resource, the memory
3452 // state), Mods/Loads can float around. So free them up.
3453 bool pinned = true;
3454 switch( n->Opcode() ) {
3455 case Op_DivI:
3456 case Op_DivF:
3457 case Op_DivD:
3458 case Op_ModI:
3459 case Op_ModF:
3460 case Op_ModD:
3461 case Op_LoadB: // Same with Loads; they can sink
3462 case Op_LoadUB: // during loop optimizations.
3463 case Op_LoadUS:
3464 case Op_LoadD:
3465 case Op_LoadF:
3466 case Op_LoadI:
3467 case Op_LoadKlass:
3468 case Op_LoadNKlass:
3469 case Op_LoadL:
3470 case Op_LoadS:
3471 case Op_LoadP:
3472 case Op_LoadN:
3473 case Op_LoadRange:
3474 case Op_LoadD_unaligned:
3475 case Op_LoadL_unaligned:
3476 case Op_StrComp: // Does a bunch of load-like effects
3477 case Op_StrEquals:
3478 case Op_StrIndexOf:
3479 case Op_AryEq:
3480 pinned = false;
3481 }
3482 if( pinned ) {
3483 IdealLoopTree *chosen_loop = get_loop(n->is_CFG() ? n : get_ctrl(n));
3484 if( !chosen_loop->_child ) // Inner loop?
3485 chosen_loop->_body.push(n); // Collect inner loops
3486 return;
3487 }
3488 } else { // No slot zero
3489 if( n->is_CFG() ) { // CFG with no slot 0 is dead
3490 _nodes.map(n->_idx,0); // No block setting, it's globally dead
3491 return;
3492 }
3493 assert(!n->is_CFG() || n->outcnt() == 0, "");
3494 }
3495
3496 // Do I have a "safe range" I can select over?
3497 Node *early = get_ctrl(n);// Early location already computed
3498
3499 // Compute latest point this Node can go
3500 Node *LCA = get_late_ctrl( n, early );
3501 // LCA is NULL due to uses being dead
3502 if( LCA == NULL ) {
3503 #ifdef ASSERT
3504 for (DUIterator i1 = n->outs(); n->has_out(i1); i1++) {
3505 assert( _nodes[n->out(i1)->_idx] == NULL, "all uses must also be dead");
3506 }
3507 #endif
3508 _nodes.map(n->_idx, 0); // This node is useless
3509 _deadlist.push(n);
3510 return;
3511 }
3512 assert(LCA != NULL && !LCA->is_top(), "no dead nodes");
3513
3514 Node *legal = LCA; // Walk 'legal' up the IDOM chain
3515 Node *least = legal; // Best legal position so far
3516 while( early != legal ) { // While not at earliest legal
3517 #ifdef ASSERT
3518 if (legal->is_Start() && !early->is_Root()) {
3519 // Bad graph. Print idom path and fail.
3520 dump_bad_graph("Bad graph detected in build_loop_late", n, early, LCA);
3521 assert(false, "Bad graph detected in build_loop_late");
3522 }
3523 #endif
3524 // Find least loop nesting depth
3525 legal = idom(legal); // Bump up the IDOM tree
3526 // Check for lower nesting depth
3527 if( get_loop(legal)->_nest < get_loop(least)->_nest )
3528 least = legal;
3529 }
3530 assert(early == legal || legal != C->root(), "bad dominance of inputs");
3531
3532 // Try not to place code on a loop entry projection
3533 // which can inhibit range check elimination.
3534 if (least != early) {
3535 Node* ctrl_out = least->unique_ctrl_out();
3536 if (ctrl_out && ctrl_out->is_CountedLoop() &&
3537 least == ctrl_out->in(LoopNode::EntryControl)) {
3538 Node* least_dom = idom(least);
3539 if (get_loop(least_dom)->is_member(get_loop(least))) {
3540 least = least_dom;
3541 }
3542 }
3543 }
3544
3545 #ifdef ASSERT
3546 // If verifying, verify that 'verify_me' has a legal location
3547 // and choose it as our location.
3548 if( _verify_me ) {
3549 Node *v_ctrl = _verify_me->get_ctrl_no_update(n);
3550 Node *legal = LCA;
3551 while( early != legal ) { // While not at earliest legal
3552 if( legal == v_ctrl ) break; // Check for prior good location
3553 legal = idom(legal) ;// Bump up the IDOM tree
3554 }
3555 // Check for prior good location
3556 if( legal == v_ctrl ) least = legal; // Keep prior if found
3557 }
3558 #endif
3559
3560 // Assign discovered "here or above" point
3561 least = find_non_split_ctrl(least);
3562 set_ctrl(n, least);
3563
3564 // Collect inner loop bodies
3565 IdealLoopTree *chosen_loop = get_loop(least);
3566 if( !chosen_loop->_child ) // Inner loop?
3567 chosen_loop->_body.push(n);// Collect inner loops
3568 }
3569
3570 #ifdef ASSERT
3571 void PhaseIdealLoop::dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA) {
3572 tty->print_cr("%s", msg);
3573 tty->print("n: "); n->dump();
3574 tty->print("early(n): "); early->dump();
3575 if (n->in(0) != NULL && !n->in(0)->is_top() &&
3576 n->in(0) != early && !n->in(0)->is_Root()) {
3577 tty->print("n->in(0): "); n->in(0)->dump();
3578 }
3579 for (uint i = 1; i < n->req(); i++) {
3580 Node* in1 = n->in(i);
3581 if (in1 != NULL && in1 != n && !in1->is_top()) {
3582 tty->print("n->in(%d): ", i); in1->dump();
3583 Node* in1_early = get_ctrl(in1);
3584 tty->print("early(n->in(%d)): ", i); in1_early->dump();
3585 if (in1->in(0) != NULL && !in1->in(0)->is_top() &&
3586 in1->in(0) != in1_early && !in1->in(0)->is_Root()) {
3587 tty->print("n->in(%d)->in(0): ", i); in1->in(0)->dump();
3588 }
3589 for (uint j = 1; j < in1->req(); j++) {
3590 Node* in2 = in1->in(j);
3591 if (in2 != NULL && in2 != n && in2 != in1 && !in2->is_top()) {
3592 tty->print("n->in(%d)->in(%d): ", i, j); in2->dump();
3593 Node* in2_early = get_ctrl(in2);
3594 tty->print("early(n->in(%d)->in(%d)): ", i, j); in2_early->dump();
3595 if (in2->in(0) != NULL && !in2->in(0)->is_top() &&
3596 in2->in(0) != in2_early && !in2->in(0)->is_Root()) {
3597 tty->print("n->in(%d)->in(%d)->in(0): ", i, j); in2->in(0)->dump();
3598 }
3599 }
3600 }
3601 }
3602 }
3603 tty->cr();
3604 tty->print("LCA(n): "); LCA->dump();
3605 for (uint i = 0; i < n->outcnt(); i++) {
3606 Node* u1 = n->raw_out(i);
3607 if (u1 == n)
3608 continue;
3609 tty->print("n->out(%d): ", i); u1->dump();
3610 if (u1->is_CFG()) {
3611 for (uint j = 0; j < u1->outcnt(); j++) {
3612 Node* u2 = u1->raw_out(j);
3613 if (u2 != u1 && u2 != n && u2->is_CFG()) {
3614 tty->print("n->out(%d)->out(%d): ", i, j); u2->dump();
3615 }
3616 }
3617 } else {
3618 Node* u1_later = get_ctrl(u1);
3619 tty->print("later(n->out(%d)): ", i); u1_later->dump();
3620 if (u1->in(0) != NULL && !u1->in(0)->is_top() &&
3621 u1->in(0) != u1_later && !u1->in(0)->is_Root()) {
3622 tty->print("n->out(%d)->in(0): ", i); u1->in(0)->dump();
3623 }
3624 for (uint j = 0; j < u1->outcnt(); j++) {
3625 Node* u2 = u1->raw_out(j);
3626 if (u2 == n || u2 == u1)
3627 continue;
3628 tty->print("n->out(%d)->out(%d): ", i, j); u2->dump();
3629 if (!u2->is_CFG()) {
3630 Node* u2_later = get_ctrl(u2);
3631 tty->print("later(n->out(%d)->out(%d)): ", i, j); u2_later->dump();
3632 if (u2->in(0) != NULL && !u2->in(0)->is_top() &&
3633 u2->in(0) != u2_later && !u2->in(0)->is_Root()) {
3634 tty->print("n->out(%d)->in(0): ", i); u2->in(0)->dump();
3635 }
3636 }
3637 }
3638 }
3639 }
3640 tty->cr();
3641 int ct = 0;
3642 Node *dbg_legal = LCA;
3643 while(!dbg_legal->is_Start() && ct < 100) {
3644 tty->print("idom[%d] ",ct); dbg_legal->dump();
3645 ct++;
3646 dbg_legal = idom(dbg_legal);
3647 }
3648 tty->cr();
3649 }
3650 #endif
3651
3652 #ifndef PRODUCT
3653 //------------------------------dump-------------------------------------------
3654 void PhaseIdealLoop::dump( ) const {
3655 ResourceMark rm;
3656 Arena* arena = Thread::current()->resource_area();
3657 Node_Stack stack(arena, C->unique() >> 2);
3658 Node_List rpo_list;
3659 VectorSet visited(arena);
3660 visited.set(C->top()->_idx);
3661 rpo( C->root(), stack, visited, rpo_list );
3662 // Dump root loop indexed by last element in PO order
3663 dump( _ltree_root, rpo_list.size(), rpo_list );
3664 }
3665
3666 void PhaseIdealLoop::dump( IdealLoopTree *loop, uint idx, Node_List &rpo_list ) const {
3667 loop->dump_head();
3668
3669 // Now scan for CFG nodes in the same loop
3670 for( uint j=idx; j > 0; j-- ) {
3671 Node *n = rpo_list[j-1];
3672 if( !_nodes[n->_idx] ) // Skip dead nodes
3673 continue;
3674 if( get_loop(n) != loop ) { // Wrong loop nest
3675 if( get_loop(n)->_head == n && // Found nested loop?
3676 get_loop(n)->_parent == loop )
3677 dump(get_loop(n),rpo_list.size(),rpo_list); // Print it nested-ly
3678 continue;
3679 }
3680
3681 // Dump controlling node
3682 for( uint x = 0; x < loop->_nest; x++ )
3683 tty->print(" ");
3684 tty->print("C");
3685 if( n == C->root() ) {
3686 n->dump();
3687 } else {
3688 Node* cached_idom = idom_no_update(n);
3689 Node *computed_idom = n->in(0);
3690 if( n->is_Region() ) {
3691 computed_idom = compute_idom(n);
3692 // computed_idom() will return n->in(0) when idom(n) is an IfNode (or
3693 // any MultiBranch ctrl node), so apply a similar transform to
3694 // the cached idom returned from idom_no_update.
3695 cached_idom = find_non_split_ctrl(cached_idom);
3696 }
3697 tty->print(" ID:%d",computed_idom->_idx);
3698 n->dump();
3699 if( cached_idom != computed_idom ) {
3700 tty->print_cr("*** BROKEN IDOM! Computed as: %d, cached as: %d",
3701 computed_idom->_idx, cached_idom->_idx);
3702 }
3703 }
3704 // Dump nodes it controls
3705 for( uint k = 0; k < _nodes.Size(); k++ ) {
3706 // (k < C->unique() && get_ctrl(find(k)) == n)
3707 if (k < C->unique() && _nodes[k] == (Node*)((intptr_t)n + 1)) {
3708 Node *m = C->root()->find(k);
3709 if( m && m->outcnt() > 0 ) {
3710 if (!(has_ctrl(m) && get_ctrl_no_update(m) == n)) {
3711 tty->print_cr("*** BROKEN CTRL ACCESSOR! _nodes[k] is %p, ctrl is %p",
3712 _nodes[k], has_ctrl(m) ? get_ctrl_no_update(m) : NULL);
3713 }
3714 for( uint j = 0; j < loop->_nest; j++ )
3715 tty->print(" ");
3716 tty->print(" ");
3717 m->dump();
3718 }
3719 }
3720 }
3721 }
3722 }
3723
3724 // Collect a R-P-O for the whole CFG.
3725 // Result list is in post-order (scan backwards for RPO)
3726 void PhaseIdealLoop::rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const {
3727 stk.push(start, 0);
3728 visited.set(start->_idx);
3729
3730 while (stk.is_nonempty()) {
3731 Node* m = stk.node();
3732 uint idx = stk.index();
3733 if (idx < m->outcnt()) {
3734 stk.set_index(idx + 1);
3735 Node* n = m->raw_out(idx);
3736 if (n->is_CFG() && !visited.test_set(n->_idx)) {
3737 stk.push(n, 0);
3738 }
3739 } else {
3740 rpo_list.push(m);
3741 stk.pop();
3742 }
3743 }
3744 }
3745 #endif
3746
3747
3748 //=============================================================================
3749 //------------------------------LoopTreeIterator-----------------------------------
3750
3751 // Advance to next loop tree using a preorder, left-to-right traversal.
3752 void LoopTreeIterator::next() {
3753 assert(!done(), "must not be done.");
3754 if (_curnt->_child != NULL) {
3755 _curnt = _curnt->_child;
3756 } else if (_curnt->_next != NULL) {
3757 _curnt = _curnt->_next;
3758 } else {
3759 while (_curnt != _root && _curnt->_next == NULL) {
3760 _curnt = _curnt->_parent;
3761 }
3762 if (_curnt == _root) {
3763 _curnt = NULL;
3764 assert(done(), "must be done.");
3765 } else {
3766 assert(_curnt->_next != NULL, "must be more to do");
3767 _curnt = _curnt->_next;
3768 }
3769 }
3770 }