1 /*
2 * Copyright (c) 1998, 2016, 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 "memory/resourceArea.hpp"
31 #include "opto/addnode.hpp"
32 #include "opto/callnode.hpp"
33 #include "opto/connode.hpp"
34 #include "opto/convertnode.hpp"
35 #include "opto/divnode.hpp"
36 #include "opto/idealGraphPrinter.hpp"
37 #include "opto/loopnode.hpp"
38 #include "opto/mulnode.hpp"
39 #include "opto/rootnode.hpp"
40 #include "opto/superword.hpp"
41
42 //=============================================================================
43 //------------------------------is_loop_iv-------------------------------------
44 // Determine if a node is Counted loop induction variable.
45 // The method is declared in node.hpp.
46 const Node* Node::is_loop_iv() const {
47 if (this->is_Phi() && !this->as_Phi()->is_copy() &&
48 this->as_Phi()->region()->is_CountedLoop() &&
49 this->as_Phi()->region()->as_CountedLoop()->phi() == this) {
50 return this;
51 } else {
52 return NULL;
53 }
54 }
55
56 //=============================================================================
57 //------------------------------dump_spec--------------------------------------
58 // Dump special per-node info
59 #ifndef PRODUCT
60 void LoopNode::dump_spec(outputStream *st) const {
61 if (is_inner_loop()) st->print( "inner " );
62 if (is_partial_peel_loop()) st->print( "partial_peel " );
63 if (partial_peel_has_failed()) st->print( "partial_peel_failed " );
64 }
65 #endif
66
67 //------------------------------is_valid_counted_loop-------------------------
68 bool LoopNode::is_valid_counted_loop() const {
69 if (is_CountedLoop()) {
70 CountedLoopNode* l = as_CountedLoop();
71 CountedLoopEndNode* le = l->loopexit();
72 if (le != NULL &&
73 le->proj_out(1 /* true */) == l->in(LoopNode::LoopBackControl)) {
74 Node* phi = l->phi();
75 Node* exit = le->proj_out(0 /* false */);
76 if (exit != NULL && exit->Opcode() == Op_IfFalse &&
77 phi != NULL && phi->is_Phi() &&
78 phi->in(LoopNode::LoopBackControl) == l->incr() &&
79 le->loopnode() == l && le->stride_is_con()) {
80 return true;
81 }
82 }
83 }
84 return false;
85 }
86
87 //------------------------------get_early_ctrl---------------------------------
88 // Compute earliest legal control
89 Node *PhaseIdealLoop::get_early_ctrl( Node *n ) {
90 assert( !n->is_Phi() && !n->is_CFG(), "this code only handles data nodes" );
91 uint i;
92 Node *early;
93 if (n->in(0) && !n->is_expensive()) {
94 early = n->in(0);
95 if (!early->is_CFG()) // Might be a non-CFG multi-def
96 early = get_ctrl(early); // So treat input as a straight data input
97 i = 1;
98 } else {
99 early = get_ctrl(n->in(1));
100 i = 2;
101 }
102 uint e_d = dom_depth(early);
103 assert( early, "" );
104 for (; i < n->req(); i++) {
105 Node *cin = get_ctrl(n->in(i));
106 assert( cin, "" );
107 // Keep deepest dominator depth
108 uint c_d = dom_depth(cin);
109 if (c_d > e_d) { // Deeper guy?
110 early = cin; // Keep deepest found so far
111 e_d = c_d;
112 } else if (c_d == e_d && // Same depth?
113 early != cin) { // If not equal, must use slower algorithm
114 // If same depth but not equal, one _must_ dominate the other
115 // and we want the deeper (i.e., dominated) guy.
116 Node *n1 = early;
117 Node *n2 = cin;
118 while (1) {
119 n1 = idom(n1); // Walk up until break cycle
120 n2 = idom(n2);
121 if (n1 == cin || // Walked early up to cin
122 dom_depth(n2) < c_d)
123 break; // early is deeper; keep him
124 if (n2 == early || // Walked cin up to early
125 dom_depth(n1) < c_d) {
126 early = cin; // cin is deeper; keep him
127 break;
128 }
129 }
130 e_d = dom_depth(early); // Reset depth register cache
131 }
132 }
133
134 // Return earliest legal location
135 assert(early == find_non_split_ctrl(early), "unexpected early control");
136
137 if (n->is_expensive() && !_verify_only && !_verify_me) {
138 assert(n->in(0), "should have control input");
139 early = get_early_ctrl_for_expensive(n, early);
140 }
141
142 return early;
143 }
144
145 //------------------------------get_early_ctrl_for_expensive---------------------------------
146 // Move node up the dominator tree as high as legal while still beneficial
147 Node *PhaseIdealLoop::get_early_ctrl_for_expensive(Node *n, Node* earliest) {
148 assert(n->in(0) && n->is_expensive(), "expensive node with control input here");
149 assert(OptimizeExpensiveOps, "optimization off?");
150
151 Node* ctl = n->in(0);
152 assert(ctl->is_CFG(), "expensive input 0 must be cfg");
153 uint min_dom_depth = dom_depth(earliest);
154 #ifdef ASSERT
155 if (!is_dominator(ctl, earliest) && !is_dominator(earliest, ctl)) {
156 dump_bad_graph("Bad graph detected in get_early_ctrl_for_expensive", n, earliest, ctl);
157 assert(false, "Bad graph detected in get_early_ctrl_for_expensive");
158 }
159 #endif
160 if (dom_depth(ctl) < min_dom_depth) {
161 return earliest;
162 }
163
164 while (1) {
165 Node *next = ctl;
166 // Moving the node out of a loop on the projection of a If
167 // confuses loop predication. So once we hit a Loop in a If branch
168 // that doesn't branch to an UNC, we stop. The code that process
169 // expensive nodes will notice the loop and skip over it to try to
170 // move the node further up.
171 if (ctl->is_CountedLoop() && ctl->in(1) != NULL && ctl->in(1)->in(0) != NULL && ctl->in(1)->in(0)->is_If()) {
172 if (!ctl->in(1)->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) {
173 break;
174 }
175 next = idom(ctl->in(1)->in(0));
176 } else if (ctl->is_Proj()) {
177 // We only move it up along a projection if the projection is
178 // the single control projection for its parent: same code path,
179 // if it's a If with UNC or fallthrough of a call.
180 Node* parent_ctl = ctl->in(0);
181 if (parent_ctl == NULL) {
182 break;
183 } else if (parent_ctl->is_CountedLoopEnd() && parent_ctl->as_CountedLoopEnd()->loopnode() != NULL) {
184 next = parent_ctl->as_CountedLoopEnd()->loopnode()->init_control();
185 } else if (parent_ctl->is_If()) {
186 if (!ctl->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) {
187 break;
188 }
189 assert(idom(ctl) == parent_ctl, "strange");
190 next = idom(parent_ctl);
191 } else if (ctl->is_CatchProj()) {
192 if (ctl->as_Proj()->_con != CatchProjNode::fall_through_index) {
193 break;
194 }
195 assert(parent_ctl->in(0)->in(0)->is_Call(), "strange graph");
196 next = parent_ctl->in(0)->in(0)->in(0);
197 } else {
198 // Check if parent control has a single projection (this
199 // control is the only possible successor of the parent
200 // control). If so, we can try to move the node above the
201 // parent control.
202 int nb_ctl_proj = 0;
203 for (DUIterator_Fast imax, i = parent_ctl->fast_outs(imax); i < imax; i++) {
204 Node *p = parent_ctl->fast_out(i);
205 if (p->is_Proj() && p->is_CFG()) {
206 nb_ctl_proj++;
207 if (nb_ctl_proj > 1) {
208 break;
209 }
210 }
211 }
212
213 if (nb_ctl_proj > 1) {
214 break;
215 }
216 assert(parent_ctl->is_Start() || parent_ctl->is_MemBar() || parent_ctl->is_Call(), "unexpected node");
217 assert(idom(ctl) == parent_ctl, "strange");
218 next = idom(parent_ctl);
219 }
220 } else {
221 next = idom(ctl);
222 }
223 if (next->is_Root() || next->is_Start() || dom_depth(next) < min_dom_depth) {
224 break;
225 }
226 ctl = next;
227 }
228
229 if (ctl != n->in(0)) {
230 _igvn.replace_input_of(n, 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->Opcode() == Op_CastII) {
334 incr = incr->in(1);
335 }
336 if (incr->is_Phi()) {
337 if (incr->as_Phi()->region() != x || incr->req() != 3)
338 return false; // Not simple trip counter expression
339 phi_incr = incr;
340 incr = phi_incr->in(LoopNode::LoopBackControl); // Assume incr is on backedge of Phi
341 if (!is_member(loop, get_ctrl(incr))) // Trip counter must be loop-variant
342 return false;
343 }
344
345 Node* trunc1 = NULL;
346 Node* trunc2 = NULL;
347 const TypeInt* iv_trunc_t = NULL;
348 if (!(incr = CountedLoopNode::match_incr_with_optional_truncation(incr, &trunc1, &trunc2, &iv_trunc_t))) {
349 return false; // Funny increment opcode
350 }
351 assert(incr->Opcode() == Op_AddI, "wrong increment code");
352
353 // Get merge point
354 Node *xphi = incr->in(1);
355 Node *stride = incr->in(2);
356 if (!stride->is_Con()) { // Oops, swap these
357 if (!xphi->is_Con()) // Is the other guy a constant?
358 return false; // Nope, unknown stride, bail out
359 Node *tmp = xphi; // 'incr' is commutative, so ok to swap
360 xphi = stride;
361 stride = tmp;
362 }
363 if (xphi->Opcode() == Op_CastII) {
364 xphi = xphi->in(1);
365 }
366 // Stride must be constant
367 int stride_con = stride->get_int();
368 if (stride_con == 0)
369 return false; // missed some peephole opt
370
371 if (!xphi->is_Phi())
372 return false; // Too much math on the trip counter
373 if (phi_incr != NULL && phi_incr != xphi)
374 return false;
375 PhiNode *phi = xphi->as_Phi();
376
377 // Phi must be of loop header; backedge must wrap to increment
378 if (phi->region() != x)
379 return false;
380 if (trunc1 == NULL && phi->in(LoopNode::LoopBackControl) != incr ||
381 trunc1 != NULL && phi->in(LoopNode::LoopBackControl) != trunc1) {
382 return false;
383 }
384 Node *init_trip = phi->in(LoopNode::EntryControl);
385
386 // If iv trunc type is smaller than int, check for possible wrap.
387 if (!TypeInt::INT->higher_equal(iv_trunc_t)) {
388 assert(trunc1 != NULL, "must have found some truncation");
389
390 // Get a better type for the phi (filtered thru if's)
391 const TypeInt* phi_ft = filtered_type(phi);
392
393 // Can iv take on a value that will wrap?
394 //
395 // Ensure iv's limit is not within "stride" of the wrap value.
396 //
397 // Example for "short" type
398 // Truncation ensures value is in the range -32768..32767 (iv_trunc_t)
399 // If the stride is +10, then the last value of the induction
400 // variable before the increment (phi_ft->_hi) must be
401 // <= 32767 - 10 and (phi_ft->_lo) must be >= -32768 to
402 // ensure no truncation occurs after the increment.
403
404 if (stride_con > 0) {
405 if (iv_trunc_t->_hi - phi_ft->_hi < stride_con ||
406 iv_trunc_t->_lo > phi_ft->_lo) {
407 return false; // truncation may occur
408 }
409 } else if (stride_con < 0) {
410 if (iv_trunc_t->_lo - phi_ft->_lo > stride_con ||
411 iv_trunc_t->_hi < phi_ft->_hi) {
412 return false; // truncation may occur
413 }
414 }
415 // No possibility of wrap so truncation can be discarded
416 // Promote iv type to Int
417 } else {
418 assert(trunc1 == NULL && trunc2 == NULL, "no truncation for int");
419 }
420
421 // If the condition is inverted and we will be rolling
422 // through MININT to MAXINT, then bail out.
423 if (bt == BoolTest::eq || // Bail out, but this loop trips at most twice!
424 // Odd stride
425 bt == BoolTest::ne && stride_con != 1 && stride_con != -1 ||
426 // Count down loop rolls through MAXINT
427 (bt == BoolTest::le || bt == BoolTest::lt) && stride_con < 0 ||
428 // Count up loop rolls through MININT
429 (bt == BoolTest::ge || bt == BoolTest::gt) && stride_con > 0) {
430 return false; // Bail out
431 }
432
433 const TypeInt* init_t = gvn->type(init_trip)->is_int();
434 const TypeInt* limit_t = gvn->type(limit)->is_int();
435
436 if (stride_con > 0) {
437 jlong init_p = (jlong)init_t->_lo + stride_con;
438 if (init_p > (jlong)max_jint || init_p > (jlong)limit_t->_hi)
439 return false; // cyclic loop or this loop trips only once
440 } else {
441 jlong init_p = (jlong)init_t->_hi + stride_con;
442 if (init_p < (jlong)min_jint || init_p < (jlong)limit_t->_lo)
443 return false; // cyclic loop or this loop trips only once
444 }
445
446 if (phi_incr != NULL) {
447 // check if there is a possiblity of IV overflowing after the first increment
448 if (stride_con > 0) {
449 if (init_t->_hi > max_jint - stride_con) {
450 return false;
451 }
452 } else {
453 if (init_t->_lo < min_jint - stride_con) {
454 return false;
455 }
456 }
457 }
458
459 // =================================================
460 // ---- SUCCESS! Found A Trip-Counted Loop! -----
461 //
462 assert(x->Opcode() == Op_Loop, "regular loops only");
463 C->print_method(PHASE_BEFORE_CLOOPS, 3);
464
465 Node *hook = new Node(6);
466
467 if (LoopLimitCheck) {
468
469 // ===================================================
470 // Generate loop limit check to avoid integer overflow
471 // in cases like next (cyclic loops):
472 //
473 // for (i=0; i <= max_jint; i++) {}
474 // for (i=0; i < max_jint; i+=2) {}
475 //
476 //
477 // Limit check predicate depends on the loop test:
478 //
479 // for(;i != limit; i++) --> limit <= (max_jint)
480 // for(;i < limit; i+=stride) --> limit <= (max_jint - stride + 1)
481 // for(;i <= limit; i+=stride) --> limit <= (max_jint - stride )
482 //
483
484 // Check if limit is excluded to do more precise int overflow check.
485 bool incl_limit = (bt == BoolTest::le || bt == BoolTest::ge);
486 int stride_m = stride_con - (incl_limit ? 0 : (stride_con > 0 ? 1 : -1));
487
488 // If compare points directly to the phi we need to adjust
489 // the compare so that it points to the incr. Limit have
490 // to be adjusted to keep trip count the same and the
491 // adjusted limit should be checked for int overflow.
492 if (phi_incr != NULL) {
493 stride_m += stride_con;
494 }
495
496 if (limit->is_Con()) {
497 int limit_con = limit->get_int();
498 if ((stride_con > 0 && limit_con > (max_jint - stride_m)) ||
499 (stride_con < 0 && limit_con < (min_jint - stride_m))) {
500 // Bailout: it could be integer overflow.
501 return false;
502 }
503 } else if ((stride_con > 0 && limit_t->_hi <= (max_jint - stride_m)) ||
504 (stride_con < 0 && limit_t->_lo >= (min_jint - stride_m))) {
505 // Limit's type may satisfy the condition, for example,
506 // when it is an array length.
507 } else {
508 // Generate loop's limit check.
509 // Loop limit check predicate should be near the loop.
510 ProjNode *limit_check_proj = find_predicate_insertion_point(init_control, Deoptimization::Reason_loop_limit_check);
511 if (!limit_check_proj) {
512 // The limit check predicate is not generated if this method trapped here before.
513 #ifdef ASSERT
514 if (TraceLoopLimitCheck) {
515 tty->print("missing loop limit check:");
516 loop->dump_head();
517 x->dump(1);
518 }
519 #endif
520 return false;
521 }
522
523 IfNode* check_iff = limit_check_proj->in(0)->as_If();
524 Node* cmp_limit;
525 Node* bol;
526
527 if (stride_con > 0) {
528 cmp_limit = new CmpINode(limit, _igvn.intcon(max_jint - stride_m));
529 bol = new BoolNode(cmp_limit, BoolTest::le);
530 } else {
531 cmp_limit = new CmpINode(limit, _igvn.intcon(min_jint - stride_m));
532 bol = new BoolNode(cmp_limit, BoolTest::ge);
533 }
534 cmp_limit = _igvn.register_new_node_with_optimizer(cmp_limit);
535 bol = _igvn.register_new_node_with_optimizer(bol);
536 set_subtree_ctrl(bol);
537
538 // Replace condition in original predicate but preserve Opaque node
539 // so that previous predicates could be found.
540 assert(check_iff->in(1)->Opcode() == Op_Conv2B &&
541 check_iff->in(1)->in(1)->Opcode() == Op_Opaque1, "");
542 Node* opq = check_iff->in(1)->in(1);
543 _igvn.replace_input_of(opq, 1, bol);
544 // Update ctrl.
545 set_ctrl(opq, check_iff->in(0));
546 set_ctrl(check_iff->in(1), check_iff->in(0));
547
548 #ifndef PRODUCT
549 // report that the loop predication has been actually performed
550 // for this loop
551 if (TraceLoopLimitCheck) {
552 tty->print_cr("Counted Loop Limit Check generated:");
553 debug_only( bol->dump(2); )
554 }
555 #endif
556 }
557
558 if (phi_incr != NULL) {
559 // If compare points directly to the phi we need to adjust
560 // the compare so that it points to the incr. Limit have
561 // to be adjusted to keep trip count the same and we
562 // should avoid int overflow.
563 //
564 // i = init; do {} while(i++ < limit);
565 // is converted to
566 // i = init; do {} while(++i < limit+1);
567 //
568 limit = gvn->transform(new AddINode(limit, stride));
569 }
570
571 // Now we need to canonicalize loop condition.
572 if (bt == BoolTest::ne) {
573 assert(stride_con == 1 || stride_con == -1, "simple increment only");
574 // 'ne' can be replaced with 'lt' only when init < limit.
575 if (stride_con > 0 && init_t->_hi < limit_t->_lo)
576 bt = BoolTest::lt;
577 // 'ne' can be replaced with 'gt' only when init > limit.
578 if (stride_con < 0 && init_t->_lo > limit_t->_hi)
579 bt = BoolTest::gt;
580 }
581
582 if (incl_limit) {
583 // The limit check guaranties that 'limit <= (max_jint - stride)' so
584 // we can convert 'i <= limit' to 'i < limit+1' since stride != 0.
585 //
586 Node* one = (stride_con > 0) ? gvn->intcon( 1) : gvn->intcon(-1);
587 limit = gvn->transform(new AddINode(limit, one));
588 if (bt == BoolTest::le)
589 bt = BoolTest::lt;
590 else if (bt == BoolTest::ge)
591 bt = BoolTest::gt;
592 else
593 ShouldNotReachHere();
594 }
595 set_subtree_ctrl( limit );
596
597 } else { // LoopLimitCheck
598
599 // If compare points to incr, we are ok. Otherwise the compare
600 // can directly point to the phi; in this case adjust the compare so that
601 // it points to the incr by adjusting the limit.
602 if (cmp->in(1) == phi || cmp->in(2) == phi)
603 limit = gvn->transform(new AddINode(limit,stride));
604
605 // trip-count for +-tive stride should be: (limit - init_trip + stride - 1)/stride.
606 // Final value for iterator should be: trip_count * stride + init_trip.
607 Node *one_p = gvn->intcon( 1);
608 Node *one_m = gvn->intcon(-1);
609
610 Node *trip_count = NULL;
611 switch( bt ) {
612 case BoolTest::eq:
613 ShouldNotReachHere();
614 case BoolTest::ne: // Ahh, the case we desire
615 if (stride_con == 1)
616 trip_count = gvn->transform(new SubINode(limit,init_trip));
617 else if (stride_con == -1)
618 trip_count = gvn->transform(new SubINode(init_trip,limit));
619 else
620 ShouldNotReachHere();
621 set_subtree_ctrl(trip_count);
622 //_loop.map(trip_count->_idx,loop(limit));
623 break;
624 case BoolTest::le: // Maybe convert to '<' case
625 limit = gvn->transform(new AddINode(limit,one_p));
626 set_subtree_ctrl( limit );
627 hook->init_req(4, limit);
628
629 bt = BoolTest::lt;
630 // Make the new limit be in the same loop nest as the old limit
631 //_loop.map(limit->_idx,limit_loop);
632 // Fall into next case
633 case BoolTest::lt: { // Maybe convert to '!=' case
634 if (stride_con < 0) // Count down loop rolls through MAXINT
635 ShouldNotReachHere();
636 Node *range = gvn->transform(new SubINode(limit,init_trip));
637 set_subtree_ctrl( range );
638 hook->init_req(0, range);
639
640 Node *bias = gvn->transform(new AddINode(range,stride));
641 set_subtree_ctrl( bias );
642 hook->init_req(1, bias);
643
644 Node *bias1 = gvn->transform(new AddINode(bias,one_m));
645 set_subtree_ctrl( bias1 );
646 hook->init_req(2, bias1);
647
648 trip_count = gvn->transform(new DivINode(0,bias1,stride));
649 set_subtree_ctrl( trip_count );
650 hook->init_req(3, trip_count);
651 break;
652 }
653
654 case BoolTest::ge: // Maybe convert to '>' case
655 limit = gvn->transform(new AddINode(limit,one_m));
656 set_subtree_ctrl( limit );
657 hook->init_req(4 ,limit);
658
659 bt = BoolTest::gt;
660 // Make the new limit be in the same loop nest as the old limit
661 //_loop.map(limit->_idx,limit_loop);
662 // Fall into next case
663 case BoolTest::gt: { // Maybe convert to '!=' case
664 if (stride_con > 0) // count up loop rolls through MININT
665 ShouldNotReachHere();
666 Node *range = gvn->transform(new SubINode(limit,init_trip));
667 set_subtree_ctrl( range );
668 hook->init_req(0, range);
669
670 Node *bias = gvn->transform(new AddINode(range,stride));
671 set_subtree_ctrl( bias );
672 hook->init_req(1, bias);
673
674 Node *bias1 = gvn->transform(new AddINode(bias,one_p));
675 set_subtree_ctrl( bias1 );
676 hook->init_req(2, bias1);
677
678 trip_count = gvn->transform(new DivINode(0,bias1,stride));
679 set_subtree_ctrl( trip_count );
680 hook->init_req(3, trip_count);
681 break;
682 }
683 } // switch( bt )
684
685 Node *span = gvn->transform(new MulINode(trip_count,stride));
686 set_subtree_ctrl( span );
687 hook->init_req(5, span);
688
689 limit = gvn->transform(new AddINode(span,init_trip));
690 set_subtree_ctrl( limit );
691
692 } // LoopLimitCheck
693
694 if (!UseCountedLoopSafepoints) {
695 // Check for SafePoint on backedge and remove
696 Node *sfpt = x->in(LoopNode::LoopBackControl);
697 if (sfpt->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt)) {
698 lazy_replace( sfpt, iftrue );
699 if (loop->_safepts != NULL) {
700 loop->_safepts->yank(sfpt);
701 }
702 loop->_tail = iftrue;
703 }
704 }
705
706 // Build a canonical trip test.
707 // Clone code, as old values may be in use.
708 incr = incr->clone();
709 incr->set_req(1,phi);
710 incr->set_req(2,stride);
711 incr = _igvn.register_new_node_with_optimizer(incr);
712 set_early_ctrl( incr );
713 _igvn.rehash_node_delayed(phi);
714 phi->set_req_X( LoopNode::LoopBackControl, incr, &_igvn );
715
716 // If phi type is more restrictive than Int, raise to
717 // Int to prevent (almost) infinite recursion in igvn
718 // which can only handle integer types for constants or minint..maxint.
719 if (!TypeInt::INT->higher_equal(phi->bottom_type())) {
720 Node* nphi = PhiNode::make(phi->in(0), phi->in(LoopNode::EntryControl), TypeInt::INT);
721 nphi->set_req(LoopNode::LoopBackControl, phi->in(LoopNode::LoopBackControl));
722 nphi = _igvn.register_new_node_with_optimizer(nphi);
723 set_ctrl(nphi, get_ctrl(phi));
724 _igvn.replace_node(phi, nphi);
725 phi = nphi->as_Phi();
726 }
727 cmp = cmp->clone();
728 cmp->set_req(1,incr);
729 cmp->set_req(2,limit);
730 cmp = _igvn.register_new_node_with_optimizer(cmp);
731 set_ctrl(cmp, iff->in(0));
732
733 test = test->clone()->as_Bool();
734 (*(BoolTest*)&test->_test)._test = bt;
735 test->set_req(1,cmp);
736 _igvn.register_new_node_with_optimizer(test);
737 set_ctrl(test, iff->in(0));
738
739 // Replace the old IfNode with a new LoopEndNode
740 Node *lex = _igvn.register_new_node_with_optimizer(new CountedLoopEndNode( iff->in(0), test, cl_prob, iff->as_If()->_fcnt ));
741 IfNode *le = lex->as_If();
742 uint dd = dom_depth(iff);
743 set_idom(le, le->in(0), dd); // Update dominance for loop exit
744 set_loop(le, loop);
745
746 // Get the loop-exit control
747 Node *iffalse = iff->as_If()->proj_out(!(iftrue_op == Op_IfTrue));
748
749 // Need to swap loop-exit and loop-back control?
750 if (iftrue_op == Op_IfFalse) {
751 Node *ift2=_igvn.register_new_node_with_optimizer(new IfTrueNode (le));
752 Node *iff2=_igvn.register_new_node_with_optimizer(new IfFalseNode(le));
753
754 loop->_tail = back_control = ift2;
755 set_loop(ift2, loop);
756 set_loop(iff2, get_loop(iffalse));
757
758 // Lazy update of 'get_ctrl' mechanism.
759 lazy_replace(iffalse, iff2);
760 lazy_replace(iftrue, ift2);
761
762 // Swap names
763 iffalse = iff2;
764 iftrue = ift2;
765 } else {
766 _igvn.rehash_node_delayed(iffalse);
767 _igvn.rehash_node_delayed(iftrue);
768 iffalse->set_req_X( 0, le, &_igvn );
769 iftrue ->set_req_X( 0, le, &_igvn );
770 }
771
772 set_idom(iftrue, le, dd+1);
773 set_idom(iffalse, le, dd+1);
774 assert(iff->outcnt() == 0, "should be dead now");
775 lazy_replace( iff, le ); // fix 'get_ctrl'
776
777 // Now setup a new CountedLoopNode to replace the existing LoopNode
778 CountedLoopNode *l = new CountedLoopNode(init_control, back_control);
779 l->set_unswitch_count(x->as_Loop()->unswitch_count()); // Preserve
780 // The following assert is approximately true, and defines the intention
781 // of can_be_counted_loop. It fails, however, because phase->type
782 // is not yet initialized for this loop and its parts.
783 //assert(l->can_be_counted_loop(this), "sanity");
784 _igvn.register_new_node_with_optimizer(l);
785 set_loop(l, loop);
786 loop->_head = l;
787 // Fix all data nodes placed at the old loop head.
788 // Uses the lazy-update mechanism of 'get_ctrl'.
789 lazy_replace( x, l );
790 set_idom(l, init_control, dom_depth(x));
791
792 if (!UseCountedLoopSafepoints) {
793 // Check for immediately preceding SafePoint and remove
794 Node *sfpt2 = le->in(0);
795 if (sfpt2->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt2)) {
796 lazy_replace( sfpt2, sfpt2->in(TypeFunc::Control));
797 if (loop->_safepts != NULL) {
798 loop->_safepts->yank(sfpt2);
799 }
800 }
801 }
802
803 // Free up intermediate goo
804 _igvn.remove_dead_node(hook);
805
806 #ifdef ASSERT
807 assert(l->is_valid_counted_loop(), "counted loop shape is messed up");
808 assert(l == loop->_head && l->phi() == phi && l->loopexit() == lex, "" );
809 #endif
810 #ifndef PRODUCT
811 if (TraceLoopOpts) {
812 tty->print("Counted ");
813 loop->dump_head();
814 }
815 #endif
816
817 C->print_method(PHASE_AFTER_CLOOPS, 3);
818
819 // Capture bounds of the loop in the induction variable Phi before
820 // subsequent transformation (iteration splitting) obscures the
821 // bounds
822 l->phi()->as_Phi()->set_type(l->phi()->Value(&_igvn));
823
824 return true;
825 }
826
827 //----------------------exact_limit-------------------------------------------
828 Node* PhaseIdealLoop::exact_limit( IdealLoopTree *loop ) {
829 assert(loop->_head->is_CountedLoop(), "");
830 CountedLoopNode *cl = loop->_head->as_CountedLoop();
831 assert(cl->is_valid_counted_loop(), "");
832
833 if (!LoopLimitCheck || ABS(cl->stride_con()) == 1 ||
834 cl->limit()->Opcode() == Op_LoopLimit) {
835 // Old code has exact limit (it could be incorrect in case of int overflow).
836 // Loop limit is exact with stride == 1. And loop may already have exact limit.
837 return cl->limit();
838 }
839 Node *limit = NULL;
840 #ifdef ASSERT
841 BoolTest::mask bt = cl->loopexit()->test_trip();
842 assert(bt == BoolTest::lt || bt == BoolTest::gt, "canonical test is expected");
843 #endif
844 if (cl->has_exact_trip_count()) {
845 // Simple case: loop has constant boundaries.
846 // Use jlongs to avoid integer overflow.
847 int stride_con = cl->stride_con();
848 jlong init_con = cl->init_trip()->get_int();
849 jlong limit_con = cl->limit()->get_int();
850 julong trip_cnt = cl->trip_count();
851 jlong final_con = init_con + trip_cnt*stride_con;
852 int final_int = (int)final_con;
853 // The final value should be in integer range since the loop
854 // is counted and the limit was checked for overflow.
855 assert(final_con == (jlong)final_int, "final value should be integer");
856 limit = _igvn.intcon(final_int);
857 } else {
858 // Create new LoopLimit node to get exact limit (final iv value).
859 limit = new LoopLimitNode(C, cl->init_trip(), cl->limit(), cl->stride());
860 register_new_node(limit, cl->in(LoopNode::EntryControl));
861 }
862 assert(limit != NULL, "sanity");
863 return limit;
864 }
865
866 //------------------------------Ideal------------------------------------------
867 // Return a node which is more "ideal" than the current node.
868 // Attempt to convert into a counted-loop.
869 Node *LoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
870 if (!can_be_counted_loop(phase)) {
871 phase->C->set_major_progress();
872 }
873 return RegionNode::Ideal(phase, can_reshape);
874 }
875
876
877 //=============================================================================
878 //------------------------------Ideal------------------------------------------
879 // Return a node which is more "ideal" than the current node.
880 // Attempt to convert into a counted-loop.
881 Node *CountedLoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
882 return RegionNode::Ideal(phase, can_reshape);
883 }
884
885 //------------------------------dump_spec--------------------------------------
886 // Dump special per-node info
887 #ifndef PRODUCT
888 void CountedLoopNode::dump_spec(outputStream *st) const {
889 LoopNode::dump_spec(st);
890 if (stride_is_con()) {
891 st->print("stride: %d ",stride_con());
892 }
893 if (is_pre_loop ()) st->print("pre of N%d" , _main_idx);
894 if (is_main_loop()) st->print("main of N%d", _idx);
895 if (is_post_loop()) st->print("post of N%d", _main_idx);
896 }
897 #endif
898
899 //=============================================================================
900 int CountedLoopEndNode::stride_con() const {
901 return stride()->bottom_type()->is_int()->get_con();
902 }
903
904 //=============================================================================
905 //------------------------------Value-----------------------------------------
906 const Type* LoopLimitNode::Value(PhaseGVN* phase) const {
907 const Type* init_t = phase->type(in(Init));
908 const Type* limit_t = phase->type(in(Limit));
909 const Type* stride_t = phase->type(in(Stride));
910 // Either input is TOP ==> the result is TOP
911 if (init_t == Type::TOP) return Type::TOP;
912 if (limit_t == Type::TOP) return Type::TOP;
913 if (stride_t == Type::TOP) return Type::TOP;
914
915 int stride_con = stride_t->is_int()->get_con();
916 if (stride_con == 1)
917 return NULL; // Identity
918
919 if (init_t->is_int()->is_con() && limit_t->is_int()->is_con()) {
920 // Use jlongs to avoid integer overflow.
921 jlong init_con = init_t->is_int()->get_con();
922 jlong limit_con = limit_t->is_int()->get_con();
923 int stride_m = stride_con - (stride_con > 0 ? 1 : -1);
924 jlong trip_count = (limit_con - init_con + stride_m)/stride_con;
925 jlong final_con = init_con + stride_con*trip_count;
926 int final_int = (int)final_con;
927 // The final value should be in integer range since the loop
928 // is counted and the limit was checked for overflow.
929 assert(final_con == (jlong)final_int, "final value should be integer");
930 return TypeInt::make(final_int);
931 }
932
933 return bottom_type(); // TypeInt::INT
934 }
935
936 //------------------------------Ideal------------------------------------------
937 // Return a node which is more "ideal" than the current node.
938 Node *LoopLimitNode::Ideal(PhaseGVN *phase, bool can_reshape) {
939 if (phase->type(in(Init)) == Type::TOP ||
940 phase->type(in(Limit)) == Type::TOP ||
941 phase->type(in(Stride)) == Type::TOP)
942 return NULL; // Dead
943
944 int stride_con = phase->type(in(Stride))->is_int()->get_con();
945 if (stride_con == 1)
946 return NULL; // Identity
947
948 if (in(Init)->is_Con() && in(Limit)->is_Con())
949 return NULL; // Value
950
951 // Delay following optimizations until all loop optimizations
952 // done to keep Ideal graph simple.
953 if (!can_reshape || phase->C->major_progress())
954 return NULL;
955
956 const TypeInt* init_t = phase->type(in(Init) )->is_int();
957 const TypeInt* limit_t = phase->type(in(Limit))->is_int();
958 int stride_p;
959 jlong lim, ini;
960 julong max;
961 if (stride_con > 0) {
962 stride_p = stride_con;
963 lim = limit_t->_hi;
964 ini = init_t->_lo;
965 max = (julong)max_jint;
966 } else {
967 stride_p = -stride_con;
968 lim = init_t->_hi;
969 ini = limit_t->_lo;
970 max = (julong)min_jint;
971 }
972 julong range = lim - ini + stride_p;
973 if (range <= max) {
974 // Convert to integer expression if it is not overflow.
975 Node* stride_m = phase->intcon(stride_con - (stride_con > 0 ? 1 : -1));
976 Node *range = phase->transform(new SubINode(in(Limit), in(Init)));
977 Node *bias = phase->transform(new AddINode(range, stride_m));
978 Node *trip = phase->transform(new DivINode(0, bias, in(Stride)));
979 Node *span = phase->transform(new MulINode(trip, in(Stride)));
980 return new AddINode(span, in(Init)); // exact limit
981 }
982
983 if (is_power_of_2(stride_p) || // divisor is 2^n
984 !Matcher::has_match_rule(Op_LoopLimit)) { // or no specialized Mach node?
985 // Convert to long expression to avoid integer overflow
986 // and let igvn optimizer convert this division.
987 //
988 Node* init = phase->transform( new ConvI2LNode(in(Init)));
989 Node* limit = phase->transform( new ConvI2LNode(in(Limit)));
990 Node* stride = phase->longcon(stride_con);
991 Node* stride_m = phase->longcon(stride_con - (stride_con > 0 ? 1 : -1));
992
993 Node *range = phase->transform(new SubLNode(limit, init));
994 Node *bias = phase->transform(new AddLNode(range, stride_m));
995 Node *span;
996 if (stride_con > 0 && is_power_of_2(stride_p)) {
997 // bias >= 0 if stride >0, so if stride is 2^n we can use &(-stride)
998 // and avoid generating rounding for division. Zero trip guard should
999 // guarantee that init < limit but sometimes the guard is missing and
1000 // we can get situation when init > limit. Note, for the empty loop
1001 // optimization zero trip guard is generated explicitly which leaves
1002 // only RCE predicate where exact limit is used and the predicate
1003 // will simply fail forcing recompilation.
1004 Node* neg_stride = phase->longcon(-stride_con);
1005 span = phase->transform(new AndLNode(bias, neg_stride));
1006 } else {
1007 Node *trip = phase->transform(new DivLNode(0, bias, stride));
1008 span = phase->transform(new MulLNode(trip, stride));
1009 }
1010 // Convert back to int
1011 Node *span_int = phase->transform(new ConvL2INode(span));
1012 return new AddINode(span_int, in(Init)); // exact limit
1013 }
1014
1015 return NULL; // No progress
1016 }
1017
1018 //------------------------------Identity---------------------------------------
1019 // If stride == 1 return limit node.
1020 Node* LoopLimitNode::Identity(PhaseGVN* phase) {
1021 int stride_con = phase->type(in(Stride))->is_int()->get_con();
1022 if (stride_con == 1 || stride_con == -1)
1023 return in(Limit);
1024 return this;
1025 }
1026
1027 //=============================================================================
1028 //----------------------match_incr_with_optional_truncation--------------------
1029 // Match increment with optional truncation:
1030 // CHAR: (i+1)&0x7fff, BYTE: ((i+1)<<8)>>8, or SHORT: ((i+1)<<16)>>16
1031 // Return NULL for failure. Success returns the increment node.
1032 Node* CountedLoopNode::match_incr_with_optional_truncation(
1033 Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type) {
1034 // Quick cutouts:
1035 if (expr == NULL || expr->req() != 3) return NULL;
1036
1037 Node *t1 = NULL;
1038 Node *t2 = NULL;
1039 const TypeInt* trunc_t = TypeInt::INT;
1040 Node* n1 = expr;
1041 int n1op = n1->Opcode();
1042
1043 // Try to strip (n1 & M) or (n1 << N >> N) from n1.
1044 if (n1op == Op_AndI &&
1045 n1->in(2)->is_Con() &&
1046 n1->in(2)->bottom_type()->is_int()->get_con() == 0x7fff) {
1047 // %%% This check should match any mask of 2**K-1.
1048 t1 = n1;
1049 n1 = t1->in(1);
1050 n1op = n1->Opcode();
1051 trunc_t = TypeInt::CHAR;
1052 } else if (n1op == Op_RShiftI &&
1053 n1->in(1) != NULL &&
1054 n1->in(1)->Opcode() == Op_LShiftI &&
1055 n1->in(2) == n1->in(1)->in(2) &&
1056 n1->in(2)->is_Con()) {
1057 jint shift = n1->in(2)->bottom_type()->is_int()->get_con();
1058 // %%% This check should match any shift in [1..31].
1059 if (shift == 16 || shift == 8) {
1060 t1 = n1;
1061 t2 = t1->in(1);
1062 n1 = t2->in(1);
1063 n1op = n1->Opcode();
1064 if (shift == 16) {
1065 trunc_t = TypeInt::SHORT;
1066 } else if (shift == 8) {
1067 trunc_t = TypeInt::BYTE;
1068 }
1069 }
1070 }
1071
1072 // If (maybe after stripping) it is an AddI, we won:
1073 if (n1op == Op_AddI) {
1074 *trunc1 = t1;
1075 *trunc2 = t2;
1076 *trunc_type = trunc_t;
1077 return n1;
1078 }
1079
1080 // failed
1081 return NULL;
1082 }
1083
1084
1085 //------------------------------filtered_type--------------------------------
1086 // Return a type based on condition control flow
1087 // A successful return will be a type that is restricted due
1088 // to a series of dominating if-tests, such as:
1089 // if (i < 10) {
1090 // if (i > 0) {
1091 // here: "i" type is [1..10)
1092 // }
1093 // }
1094 // or a control flow merge
1095 // if (i < 10) {
1096 // do {
1097 // phi( , ) -- at top of loop type is [min_int..10)
1098 // i = ?
1099 // } while ( i < 10)
1100 //
1101 const TypeInt* PhaseIdealLoop::filtered_type( Node *n, Node* n_ctrl) {
1102 assert(n && n->bottom_type()->is_int(), "must be int");
1103 const TypeInt* filtered_t = NULL;
1104 if (!n->is_Phi()) {
1105 assert(n_ctrl != NULL || n_ctrl == C->top(), "valid control");
1106 filtered_t = filtered_type_from_dominators(n, n_ctrl);
1107
1108 } else {
1109 Node* phi = n->as_Phi();
1110 Node* region = phi->in(0);
1111 assert(n_ctrl == NULL || n_ctrl == region, "ctrl parameter must be region");
1112 if (region && region != C->top()) {
1113 for (uint i = 1; i < phi->req(); i++) {
1114 Node* val = phi->in(i);
1115 Node* use_c = region->in(i);
1116 const TypeInt* val_t = filtered_type_from_dominators(val, use_c);
1117 if (val_t != NULL) {
1118 if (filtered_t == NULL) {
1119 filtered_t = val_t;
1120 } else {
1121 filtered_t = filtered_t->meet(val_t)->is_int();
1122 }
1123 }
1124 }
1125 }
1126 }
1127 const TypeInt* n_t = _igvn.type(n)->is_int();
1128 if (filtered_t != NULL) {
1129 n_t = n_t->join(filtered_t)->is_int();
1130 }
1131 return n_t;
1132 }
1133
1134
1135 //------------------------------filtered_type_from_dominators--------------------------------
1136 // Return a possibly more restrictive type for val based on condition control flow of dominators
1137 const TypeInt* PhaseIdealLoop::filtered_type_from_dominators( Node* val, Node *use_ctrl) {
1138 if (val->is_Con()) {
1139 return val->bottom_type()->is_int();
1140 }
1141 uint if_limit = 10; // Max number of dominating if's visited
1142 const TypeInt* rtn_t = NULL;
1143
1144 if (use_ctrl && use_ctrl != C->top()) {
1145 Node* val_ctrl = get_ctrl(val);
1146 uint val_dom_depth = dom_depth(val_ctrl);
1147 Node* pred = use_ctrl;
1148 uint if_cnt = 0;
1149 while (if_cnt < if_limit) {
1150 if ((pred->Opcode() == Op_IfTrue || pred->Opcode() == Op_IfFalse)) {
1151 if_cnt++;
1152 const TypeInt* if_t = IfNode::filtered_int_type(&_igvn, val, pred);
1153 if (if_t != NULL) {
1154 if (rtn_t == NULL) {
1155 rtn_t = if_t;
1156 } else {
1157 rtn_t = rtn_t->join(if_t)->is_int();
1158 }
1159 }
1160 }
1161 pred = idom(pred);
1162 if (pred == NULL || pred == C->top()) {
1163 break;
1164 }
1165 // Stop if going beyond definition block of val
1166 if (dom_depth(pred) < val_dom_depth) {
1167 break;
1168 }
1169 }
1170 }
1171 return rtn_t;
1172 }
1173
1174
1175 //------------------------------dump_spec--------------------------------------
1176 // Dump special per-node info
1177 #ifndef PRODUCT
1178 void CountedLoopEndNode::dump_spec(outputStream *st) const {
1179 if( in(TestValue) != NULL && in(TestValue)->is_Bool() ) {
1180 BoolTest bt( test_trip()); // Added this for g++.
1181
1182 st->print("[");
1183 bt.dump_on(st);
1184 st->print("]");
1185 }
1186 st->print(" ");
1187 IfNode::dump_spec(st);
1188 }
1189 #endif
1190
1191 //=============================================================================
1192 //------------------------------is_member--------------------------------------
1193 // Is 'l' a member of 'this'?
1194 bool IdealLoopTree::is_member(const IdealLoopTree *l) const {
1195 while( l->_nest > _nest ) l = l->_parent;
1196 return l == this;
1197 }
1198
1199 //------------------------------set_nest---------------------------------------
1200 // Set loop tree nesting depth. Accumulate _has_call bits.
1201 int IdealLoopTree::set_nest( uint depth ) {
1202 _nest = depth;
1203 int bits = _has_call;
1204 if( _child ) bits |= _child->set_nest(depth+1);
1205 if( bits ) _has_call = 1;
1206 if( _next ) bits |= _next ->set_nest(depth );
1207 return bits;
1208 }
1209
1210 //------------------------------split_fall_in----------------------------------
1211 // Split out multiple fall-in edges from the loop header. Move them to a
1212 // private RegionNode before the loop. This becomes the loop landing pad.
1213 void IdealLoopTree::split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ) {
1214 PhaseIterGVN &igvn = phase->_igvn;
1215 uint i;
1216
1217 // Make a new RegionNode to be the landing pad.
1218 Node *landing_pad = new RegionNode( fall_in_cnt+1 );
1219 phase->set_loop(landing_pad,_parent);
1220 // Gather all the fall-in control paths into the landing pad
1221 uint icnt = fall_in_cnt;
1222 uint oreq = _head->req();
1223 for( i = oreq-1; i>0; i-- )
1224 if( !phase->is_member( this, _head->in(i) ) )
1225 landing_pad->set_req(icnt--,_head->in(i));
1226
1227 // Peel off PhiNode edges as well
1228 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1229 Node *oj = _head->fast_out(j);
1230 if( oj->is_Phi() ) {
1231 PhiNode* old_phi = oj->as_Phi();
1232 assert( old_phi->region() == _head, "" );
1233 igvn.hash_delete(old_phi); // Yank from hash before hacking edges
1234 Node *p = PhiNode::make_blank(landing_pad, old_phi);
1235 uint icnt = fall_in_cnt;
1236 for( i = oreq-1; i>0; i-- ) {
1237 if( !phase->is_member( this, _head->in(i) ) ) {
1238 p->init_req(icnt--, old_phi->in(i));
1239 // Go ahead and clean out old edges from old phi
1240 old_phi->del_req(i);
1241 }
1242 }
1243 // Search for CSE's here, because ZKM.jar does a lot of
1244 // loop hackery and we need to be a little incremental
1245 // with the CSE to avoid O(N^2) node blow-up.
1246 Node *p2 = igvn.hash_find_insert(p); // Look for a CSE
1247 if( p2 ) { // Found CSE
1248 p->destruct(); // Recover useless new node
1249 p = p2; // Use old node
1250 } else {
1251 igvn.register_new_node_with_optimizer(p, old_phi);
1252 }
1253 // Make old Phi refer to new Phi.
1254 old_phi->add_req(p);
1255 // Check for the special case of making the old phi useless and
1256 // disappear it. In JavaGrande I have a case where this useless
1257 // Phi is the loop limit and prevents recognizing a CountedLoop
1258 // which in turn prevents removing an empty loop.
1259 Node *id_old_phi = old_phi->Identity( &igvn );
1260 if( id_old_phi != old_phi ) { // Found a simple identity?
1261 // Note that I cannot call 'replace_node' here, because
1262 // that will yank the edge from old_phi to the Region and
1263 // I'm mid-iteration over the Region's uses.
1264 for (DUIterator_Last imin, i = old_phi->last_outs(imin); i >= imin; ) {
1265 Node* use = old_phi->last_out(i);
1266 igvn.rehash_node_delayed(use);
1267 uint uses_found = 0;
1268 for (uint j = 0; j < use->len(); j++) {
1269 if (use->in(j) == old_phi) {
1270 if (j < use->req()) use->set_req (j, id_old_phi);
1271 else use->set_prec(j, id_old_phi);
1272 uses_found++;
1273 }
1274 }
1275 i -= uses_found; // we deleted 1 or more copies of this edge
1276 }
1277 }
1278 igvn._worklist.push(old_phi);
1279 }
1280 }
1281 // Finally clean out the fall-in edges from the RegionNode
1282 for( i = oreq-1; i>0; i-- ) {
1283 if( !phase->is_member( this, _head->in(i) ) ) {
1284 _head->del_req(i);
1285 }
1286 }
1287 igvn.rehash_node_delayed(_head);
1288 // Transform landing pad
1289 igvn.register_new_node_with_optimizer(landing_pad, _head);
1290 // Insert landing pad into the header
1291 _head->add_req(landing_pad);
1292 }
1293
1294 //------------------------------split_outer_loop-------------------------------
1295 // Split out the outermost loop from this shared header.
1296 void IdealLoopTree::split_outer_loop( PhaseIdealLoop *phase ) {
1297 PhaseIterGVN &igvn = phase->_igvn;
1298
1299 // Find index of outermost loop; it should also be my tail.
1300 uint outer_idx = 1;
1301 while( _head->in(outer_idx) != _tail ) outer_idx++;
1302
1303 // Make a LoopNode for the outermost loop.
1304 Node *ctl = _head->in(LoopNode::EntryControl);
1305 Node *outer = new LoopNode( ctl, _head->in(outer_idx) );
1306 outer = igvn.register_new_node_with_optimizer(outer, _head);
1307 phase->set_created_loop_node();
1308
1309 // Outermost loop falls into '_head' loop
1310 _head->set_req(LoopNode::EntryControl, outer);
1311 _head->del_req(outer_idx);
1312 // Split all the Phis up between '_head' loop and 'outer' loop.
1313 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1314 Node *out = _head->fast_out(j);
1315 if( out->is_Phi() ) {
1316 PhiNode *old_phi = out->as_Phi();
1317 assert( old_phi->region() == _head, "" );
1318 Node *phi = PhiNode::make_blank(outer, old_phi);
1319 phi->init_req(LoopNode::EntryControl, old_phi->in(LoopNode::EntryControl));
1320 phi->init_req(LoopNode::LoopBackControl, old_phi->in(outer_idx));
1321 phi = igvn.register_new_node_with_optimizer(phi, old_phi);
1322 // Make old Phi point to new Phi on the fall-in path
1323 igvn.replace_input_of(old_phi, LoopNode::EntryControl, phi);
1324 old_phi->del_req(outer_idx);
1325 }
1326 }
1327
1328 // Use the new loop head instead of the old shared one
1329 _head = outer;
1330 phase->set_loop(_head, this);
1331 }
1332
1333 //------------------------------fix_parent-------------------------------------
1334 static void fix_parent( IdealLoopTree *loop, IdealLoopTree *parent ) {
1335 loop->_parent = parent;
1336 if( loop->_child ) fix_parent( loop->_child, loop );
1337 if( loop->_next ) fix_parent( loop->_next , parent );
1338 }
1339
1340 //------------------------------estimate_path_freq-----------------------------
1341 static float estimate_path_freq( Node *n ) {
1342 // Try to extract some path frequency info
1343 IfNode *iff;
1344 for( int i = 0; i < 50; i++ ) { // Skip through a bunch of uncommon tests
1345 uint nop = n->Opcode();
1346 if( nop == Op_SafePoint ) { // Skip any safepoint
1347 n = n->in(0);
1348 continue;
1349 }
1350 if( nop == Op_CatchProj ) { // Get count from a prior call
1351 // Assume call does not always throw exceptions: means the call-site
1352 // count is also the frequency of the fall-through path.
1353 assert( n->is_CatchProj(), "" );
1354 if( ((CatchProjNode*)n)->_con != CatchProjNode::fall_through_index )
1355 return 0.0f; // Assume call exception path is rare
1356 Node *call = n->in(0)->in(0)->in(0);
1357 assert( call->is_Call(), "expect a call here" );
1358 const JVMState *jvms = ((CallNode*)call)->jvms();
1359 ciMethodData* methodData = jvms->method()->method_data();
1360 if (!methodData->is_mature()) return 0.0f; // No call-site data
1361 ciProfileData* data = methodData->bci_to_data(jvms->bci());
1362 if ((data == NULL) || !data->is_CounterData()) {
1363 // no call profile available, try call's control input
1364 n = n->in(0);
1365 continue;
1366 }
1367 return data->as_CounterData()->count()/FreqCountInvocations;
1368 }
1369 // See if there's a gating IF test
1370 Node *n_c = n->in(0);
1371 if( !n_c->is_If() ) break; // No estimate available
1372 iff = n_c->as_If();
1373 if( iff->_fcnt != COUNT_UNKNOWN ) // Have a valid count?
1374 // Compute how much count comes on this path
1375 return ((nop == Op_IfTrue) ? iff->_prob : 1.0f - iff->_prob) * iff->_fcnt;
1376 // Have no count info. Skip dull uncommon-trap like branches.
1377 if( (nop == Op_IfTrue && iff->_prob < PROB_LIKELY_MAG(5)) ||
1378 (nop == Op_IfFalse && iff->_prob > PROB_UNLIKELY_MAG(5)) )
1379 break;
1380 // Skip through never-taken branch; look for a real loop exit.
1381 n = iff->in(0);
1382 }
1383 return 0.0f; // No estimate available
1384 }
1385
1386 //------------------------------merge_many_backedges---------------------------
1387 // Merge all the backedges from the shared header into a private Region.
1388 // Feed that region as the one backedge to this loop.
1389 void IdealLoopTree::merge_many_backedges( PhaseIdealLoop *phase ) {
1390 uint i;
1391
1392 // Scan for the top 2 hottest backedges
1393 float hotcnt = 0.0f;
1394 float warmcnt = 0.0f;
1395 uint hot_idx = 0;
1396 // Loop starts at 2 because slot 1 is the fall-in path
1397 for( i = 2; i < _head->req(); i++ ) {
1398 float cnt = estimate_path_freq(_head->in(i));
1399 if( cnt > hotcnt ) { // Grab hottest path
1400 warmcnt = hotcnt;
1401 hotcnt = cnt;
1402 hot_idx = i;
1403 } else if( cnt > warmcnt ) { // And 2nd hottest path
1404 warmcnt = cnt;
1405 }
1406 }
1407
1408 // See if the hottest backedge is worthy of being an inner loop
1409 // by being much hotter than the next hottest backedge.
1410 if( hotcnt <= 0.0001 ||
1411 hotcnt < 2.0*warmcnt ) hot_idx = 0;// No hot backedge
1412
1413 // Peel out the backedges into a private merge point; peel
1414 // them all except optionally hot_idx.
1415 PhaseIterGVN &igvn = phase->_igvn;
1416
1417 Node *hot_tail = NULL;
1418 // Make a Region for the merge point
1419 Node *r = new RegionNode(1);
1420 for( i = 2; i < _head->req(); i++ ) {
1421 if( i != hot_idx )
1422 r->add_req( _head->in(i) );
1423 else hot_tail = _head->in(i);
1424 }
1425 igvn.register_new_node_with_optimizer(r, _head);
1426 // Plug region into end of loop _head, followed by hot_tail
1427 while( _head->req() > 3 ) _head->del_req( _head->req()-1 );
1428 igvn.replace_input_of(_head, 2, r);
1429 if( hot_idx ) _head->add_req(hot_tail);
1430
1431 // Split all the Phis up between '_head' loop and the Region 'r'
1432 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1433 Node *out = _head->fast_out(j);
1434 if( out->is_Phi() ) {
1435 PhiNode* n = out->as_Phi();
1436 igvn.hash_delete(n); // Delete from hash before hacking edges
1437 Node *hot_phi = NULL;
1438 Node *phi = new PhiNode(r, n->type(), n->adr_type());
1439 // Check all inputs for the ones to peel out
1440 uint j = 1;
1441 for( uint i = 2; i < n->req(); i++ ) {
1442 if( i != hot_idx )
1443 phi->set_req( j++, n->in(i) );
1444 else hot_phi = n->in(i);
1445 }
1446 // Register the phi but do not transform until whole place transforms
1447 igvn.register_new_node_with_optimizer(phi, n);
1448 // Add the merge phi to the old Phi
1449 while( n->req() > 3 ) n->del_req( n->req()-1 );
1450 igvn.replace_input_of(n, 2, phi);
1451 if( hot_idx ) n->add_req(hot_phi);
1452 }
1453 }
1454
1455
1456 // Insert a new IdealLoopTree inserted below me. Turn it into a clone
1457 // of self loop tree. Turn self into a loop headed by _head and with
1458 // tail being the new merge point.
1459 IdealLoopTree *ilt = new IdealLoopTree( phase, _head, _tail );
1460 phase->set_loop(_tail,ilt); // Adjust tail
1461 _tail = r; // Self's tail is new merge point
1462 phase->set_loop(r,this);
1463 ilt->_child = _child; // New guy has my children
1464 _child = ilt; // Self has new guy as only child
1465 ilt->_parent = this; // new guy has self for parent
1466 ilt->_nest = _nest; // Same nesting depth (for now)
1467
1468 // Starting with 'ilt', look for child loop trees using the same shared
1469 // header. Flatten these out; they will no longer be loops in the end.
1470 IdealLoopTree **pilt = &_child;
1471 while( ilt ) {
1472 if( ilt->_head == _head ) {
1473 uint i;
1474 for( i = 2; i < _head->req(); i++ )
1475 if( _head->in(i) == ilt->_tail )
1476 break; // Still a loop
1477 if( i == _head->req() ) { // No longer a loop
1478 // Flatten ilt. Hang ilt's "_next" list from the end of
1479 // ilt's '_child' list. Move the ilt's _child up to replace ilt.
1480 IdealLoopTree **cp = &ilt->_child;
1481 while( *cp ) cp = &(*cp)->_next; // Find end of child list
1482 *cp = ilt->_next; // Hang next list at end of child list
1483 *pilt = ilt->_child; // Move child up to replace ilt
1484 ilt->_head = NULL; // Flag as a loop UNIONED into parent
1485 ilt = ilt->_child; // Repeat using new ilt
1486 continue; // do not advance over ilt->_child
1487 }
1488 assert( ilt->_tail == hot_tail, "expected to only find the hot inner loop here" );
1489 phase->set_loop(_head,ilt);
1490 }
1491 pilt = &ilt->_child; // Advance to next
1492 ilt = *pilt;
1493 }
1494
1495 if( _child ) fix_parent( _child, this );
1496 }
1497
1498 //------------------------------beautify_loops---------------------------------
1499 // Split shared headers and insert loop landing pads.
1500 // Insert a LoopNode to replace the RegionNode.
1501 // Return TRUE if loop tree is structurally changed.
1502 bool IdealLoopTree::beautify_loops( PhaseIdealLoop *phase ) {
1503 bool result = false;
1504 // Cache parts in locals for easy
1505 PhaseIterGVN &igvn = phase->_igvn;
1506
1507 igvn.hash_delete(_head); // Yank from hash before hacking edges
1508
1509 // Check for multiple fall-in paths. Peel off a landing pad if need be.
1510 int fall_in_cnt = 0;
1511 for( uint i = 1; i < _head->req(); i++ )
1512 if( !phase->is_member( this, _head->in(i) ) )
1513 fall_in_cnt++;
1514 assert( fall_in_cnt, "at least 1 fall-in path" );
1515 if( fall_in_cnt > 1 ) // Need a loop landing pad to merge fall-ins
1516 split_fall_in( phase, fall_in_cnt );
1517
1518 // Swap inputs to the _head and all Phis to move the fall-in edge to
1519 // the left.
1520 fall_in_cnt = 1;
1521 while( phase->is_member( this, _head->in(fall_in_cnt) ) )
1522 fall_in_cnt++;
1523 if( fall_in_cnt > 1 ) {
1524 // Since I am just swapping inputs I do not need to update def-use info
1525 Node *tmp = _head->in(1);
1526 igvn.rehash_node_delayed(_head);
1527 _head->set_req( 1, _head->in(fall_in_cnt) );
1528 _head->set_req( fall_in_cnt, tmp );
1529 // Swap also all Phis
1530 for (DUIterator_Fast imax, i = _head->fast_outs(imax); i < imax; i++) {
1531 Node* phi = _head->fast_out(i);
1532 if( phi->is_Phi() ) {
1533 igvn.rehash_node_delayed(phi); // Yank from hash before hacking edges
1534 tmp = phi->in(1);
1535 phi->set_req( 1, phi->in(fall_in_cnt) );
1536 phi->set_req( fall_in_cnt, tmp );
1537 }
1538 }
1539 }
1540 assert( !phase->is_member( this, _head->in(1) ), "left edge is fall-in" );
1541 assert( phase->is_member( this, _head->in(2) ), "right edge is loop" );
1542
1543 // If I am a shared header (multiple backedges), peel off the many
1544 // backedges into a private merge point and use the merge point as
1545 // the one true backedge.
1546 if( _head->req() > 3 ) {
1547 // Merge the many backedges into a single backedge but leave
1548 // the hottest backedge as separate edge for the following peel.
1549 merge_many_backedges( phase );
1550 result = true;
1551 }
1552
1553 // If I have one hot backedge, peel off myself loop.
1554 // I better be the outermost loop.
1555 if (_head->req() > 3 && !_irreducible) {
1556 split_outer_loop( phase );
1557 result = true;
1558
1559 } else if (!_head->is_Loop() && !_irreducible) {
1560 // Make a new LoopNode to replace the old loop head
1561 Node *l = new LoopNode( _head->in(1), _head->in(2) );
1562 l = igvn.register_new_node_with_optimizer(l, _head);
1563 phase->set_created_loop_node();
1564 // Go ahead and replace _head
1565 phase->_igvn.replace_node( _head, l );
1566 _head = l;
1567 phase->set_loop(_head, this);
1568 }
1569
1570 // Now recursively beautify nested loops
1571 if( _child ) result |= _child->beautify_loops( phase );
1572 if( _next ) result |= _next ->beautify_loops( phase );
1573 return result;
1574 }
1575
1576 //------------------------------allpaths_check_safepts----------------------------
1577 // Allpaths backwards scan from loop tail, terminating each path at first safepoint
1578 // encountered. Helper for check_safepts.
1579 void IdealLoopTree::allpaths_check_safepts(VectorSet &visited, Node_List &stack) {
1580 assert(stack.size() == 0, "empty stack");
1581 stack.push(_tail);
1582 visited.Clear();
1583 visited.set(_tail->_idx);
1584 while (stack.size() > 0) {
1585 Node* n = stack.pop();
1586 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
1587 // Terminate this path
1588 } else if (n->Opcode() == Op_SafePoint) {
1589 if (_phase->get_loop(n) != this) {
1590 if (_required_safept == NULL) _required_safept = new Node_List();
1591 _required_safept->push(n); // save the one closest to the tail
1592 }
1593 // Terminate this path
1594 } else {
1595 uint start = n->is_Region() ? 1 : 0;
1596 uint end = n->is_Region() && !n->is_Loop() ? n->req() : start + 1;
1597 for (uint i = start; i < end; i++) {
1598 Node* in = n->in(i);
1599 assert(in->is_CFG(), "must be");
1600 if (!visited.test_set(in->_idx) && is_member(_phase->get_loop(in))) {
1601 stack.push(in);
1602 }
1603 }
1604 }
1605 }
1606 }
1607
1608 //------------------------------check_safepts----------------------------
1609 // Given dominators, try to find loops with calls that must always be
1610 // executed (call dominates loop tail). These loops do not need non-call
1611 // safepoints (ncsfpt).
1612 //
1613 // A complication is that a safepoint in a inner loop may be needed
1614 // by an outer loop. In the following, the inner loop sees it has a
1615 // call (block 3) on every path from the head (block 2) to the
1616 // backedge (arc 3->2). So it deletes the ncsfpt (non-call safepoint)
1617 // in block 2, _but_ this leaves the outer loop without a safepoint.
1618 //
1619 // entry 0
1620 // |
1621 // v
1622 // outer 1,2 +->1
1623 // | |
1624 // | v
1625 // | 2<---+ ncsfpt in 2
1626 // |_/|\ |
1627 // | v |
1628 // inner 2,3 / 3 | call in 3
1629 // / | |
1630 // v +--+
1631 // exit 4
1632 //
1633 //
1634 // This method creates a list (_required_safept) of ncsfpt nodes that must
1635 // be protected is created for each loop. When a ncsfpt maybe deleted, it
1636 // is first looked for in the lists for the outer loops of the current loop.
1637 //
1638 // The insights into the problem:
1639 // A) counted loops are okay
1640 // B) innermost loops are okay (only an inner loop can delete
1641 // a ncsfpt needed by an outer loop)
1642 // C) a loop is immune from an inner loop deleting a safepoint
1643 // if the loop has a call on the idom-path
1644 // D) a loop is also immune if it has a ncsfpt (non-call safepoint) on the
1645 // idom-path that is not in a nested loop
1646 // E) otherwise, an ncsfpt on the idom-path that is nested in an inner
1647 // loop needs to be prevented from deletion by an inner loop
1648 //
1649 // There are two analyses:
1650 // 1) The first, and cheaper one, scans the loop body from
1651 // tail to head following the idom (immediate dominator)
1652 // chain, looking for the cases (C,D,E) above.
1653 // Since inner loops are scanned before outer loops, there is summary
1654 // information about inner loops. Inner loops can be skipped over
1655 // when the tail of an inner loop is encountered.
1656 //
1657 // 2) The second, invoked if the first fails to find a call or ncsfpt on
1658 // the idom path (which is rare), scans all predecessor control paths
1659 // from the tail to the head, terminating a path when a call or sfpt
1660 // is encountered, to find the ncsfpt's that are closest to the tail.
1661 //
1662 void IdealLoopTree::check_safepts(VectorSet &visited, Node_List &stack) {
1663 // Bottom up traversal
1664 IdealLoopTree* ch = _child;
1665 if (_child) _child->check_safepts(visited, stack);
1666 if (_next) _next ->check_safepts(visited, stack);
1667
1668 if (!_head->is_CountedLoop() && !_has_sfpt && _parent != NULL && !_irreducible) {
1669 bool has_call = false; // call on dom-path
1670 bool has_local_ncsfpt = false; // ncsfpt on dom-path at this loop depth
1671 Node* nonlocal_ncsfpt = NULL; // ncsfpt on dom-path at a deeper depth
1672 // Scan the dom-path nodes from tail to head
1673 for (Node* n = tail(); n != _head; n = _phase->idom(n)) {
1674 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
1675 has_call = true;
1676 _has_sfpt = 1; // Then no need for a safept!
1677 break;
1678 } else if (n->Opcode() == Op_SafePoint) {
1679 if (_phase->get_loop(n) == this) {
1680 has_local_ncsfpt = true;
1681 break;
1682 }
1683 if (nonlocal_ncsfpt == NULL) {
1684 nonlocal_ncsfpt = n; // save the one closest to the tail
1685 }
1686 } else {
1687 IdealLoopTree* nlpt = _phase->get_loop(n);
1688 if (this != nlpt) {
1689 // If at an inner loop tail, see if the inner loop has already
1690 // recorded seeing a call on the dom-path (and stop.) If not,
1691 // jump to the head of the inner loop.
1692 assert(is_member(nlpt), "nested loop");
1693 Node* tail = nlpt->_tail;
1694 if (tail->in(0)->is_If()) tail = tail->in(0);
1695 if (n == tail) {
1696 // If inner loop has call on dom-path, so does outer loop
1697 if (nlpt->_has_sfpt) {
1698 has_call = true;
1699 _has_sfpt = 1;
1700 break;
1701 }
1702 // Skip to head of inner loop
1703 assert(_phase->is_dominator(_head, nlpt->_head), "inner head dominated by outer head");
1704 n = nlpt->_head;
1705 }
1706 }
1707 }
1708 }
1709 // Record safept's that this loop needs preserved when an
1710 // inner loop attempts to delete it's safepoints.
1711 if (_child != NULL && !has_call && !has_local_ncsfpt) {
1712 if (nonlocal_ncsfpt != NULL) {
1713 if (_required_safept == NULL) _required_safept = new Node_List();
1714 _required_safept->push(nonlocal_ncsfpt);
1715 } else {
1716 // Failed to find a suitable safept on the dom-path. Now use
1717 // an all paths walk from tail to head, looking for safepoints to preserve.
1718 allpaths_check_safepts(visited, stack);
1719 }
1720 }
1721 }
1722 }
1723
1724 //---------------------------is_deleteable_safept----------------------------
1725 // Is safept not required by an outer loop?
1726 bool PhaseIdealLoop::is_deleteable_safept(Node* sfpt) {
1727 assert(sfpt->Opcode() == Op_SafePoint, "");
1728 IdealLoopTree* lp = get_loop(sfpt)->_parent;
1729 while (lp != NULL) {
1730 Node_List* sfpts = lp->_required_safept;
1731 if (sfpts != NULL) {
1732 for (uint i = 0; i < sfpts->size(); i++) {
1733 if (sfpt == sfpts->at(i))
1734 return false;
1735 }
1736 }
1737 lp = lp->_parent;
1738 }
1739 return true;
1740 }
1741
1742 //---------------------------replace_parallel_iv-------------------------------
1743 // Replace parallel induction variable (parallel to trip counter)
1744 void PhaseIdealLoop::replace_parallel_iv(IdealLoopTree *loop) {
1745 assert(loop->_head->is_CountedLoop(), "");
1746 CountedLoopNode *cl = loop->_head->as_CountedLoop();
1747 if (!cl->is_valid_counted_loop())
1748 return; // skip malformed counted loop
1749 Node *incr = cl->incr();
1750 if (incr == NULL)
1751 return; // Dead loop?
1752 Node *init = cl->init_trip();
1753 Node *phi = cl->phi();
1754 int stride_con = cl->stride_con();
1755
1756 // Visit all children, looking for Phis
1757 for (DUIterator i = cl->outs(); cl->has_out(i); i++) {
1758 Node *out = cl->out(i);
1759 // Look for other phis (secondary IVs). Skip dead ones
1760 if (!out->is_Phi() || out == phi || !has_node(out))
1761 continue;
1762 PhiNode* phi2 = out->as_Phi();
1763 Node *incr2 = phi2->in( LoopNode::LoopBackControl );
1764 // Look for induction variables of the form: X += constant
1765 if (phi2->region() != loop->_head ||
1766 incr2->req() != 3 ||
1767 incr2->in(1) != phi2 ||
1768 incr2 == incr ||
1769 incr2->Opcode() != Op_AddI ||
1770 !incr2->in(2)->is_Con())
1771 continue;
1772
1773 // Check for parallel induction variable (parallel to trip counter)
1774 // via an affine function. In particular, count-down loops with
1775 // count-up array indices are common. We only RCE references off
1776 // the trip-counter, so we need to convert all these to trip-counter
1777 // expressions.
1778 Node *init2 = phi2->in( LoopNode::EntryControl );
1779 int stride_con2 = incr2->in(2)->get_int();
1780
1781 // The general case here gets a little tricky. We want to find the
1782 // GCD of all possible parallel IV's and make a new IV using this
1783 // GCD for the loop. Then all possible IVs are simple multiples of
1784 // the GCD. In practice, this will cover very few extra loops.
1785 // Instead we require 'stride_con2' to be a multiple of 'stride_con',
1786 // where +/-1 is the common case, but other integer multiples are
1787 // also easy to handle.
1788 int ratio_con = stride_con2/stride_con;
1789
1790 if ((ratio_con * stride_con) == stride_con2) { // Check for exact
1791 #ifndef PRODUCT
1792 if (TraceLoopOpts) {
1793 tty->print("Parallel IV: %d ", phi2->_idx);
1794 loop->dump_head();
1795 }
1796 #endif
1797 // Convert to using the trip counter. The parallel induction
1798 // variable differs from the trip counter by a loop-invariant
1799 // amount, the difference between their respective initial values.
1800 // It is scaled by the 'ratio_con'.
1801 Node* ratio = _igvn.intcon(ratio_con);
1802 set_ctrl(ratio, C->root());
1803 Node* ratio_init = new MulINode(init, ratio);
1804 _igvn.register_new_node_with_optimizer(ratio_init, init);
1805 set_early_ctrl(ratio_init);
1806 Node* diff = new SubINode(init2, ratio_init);
1807 _igvn.register_new_node_with_optimizer(diff, init2);
1808 set_early_ctrl(diff);
1809 Node* ratio_idx = new MulINode(phi, ratio);
1810 _igvn.register_new_node_with_optimizer(ratio_idx, phi);
1811 set_ctrl(ratio_idx, cl);
1812 Node* add = new AddINode(ratio_idx, diff);
1813 _igvn.register_new_node_with_optimizer(add);
1814 set_ctrl(add, cl);
1815 _igvn.replace_node( phi2, add );
1816 // Sometimes an induction variable is unused
1817 if (add->outcnt() == 0) {
1818 _igvn.remove_dead_node(add);
1819 }
1820 --i; // deleted this phi; rescan starting with next position
1821 continue;
1822 }
1823 }
1824 }
1825
1826 void IdealLoopTree::remove_safepoints(PhaseIdealLoop* phase, bool keep_one) {
1827 Node* keep = NULL;
1828 if (keep_one) {
1829 // Look for a safepoint on the idom-path.
1830 for (Node* i = tail(); i != _head; i = phase->idom(i)) {
1831 if (i->Opcode() == Op_SafePoint && phase->get_loop(i) == this) {
1832 keep = i;
1833 break; // Found one
1834 }
1835 }
1836 }
1837
1838 // Don't remove any safepoints if it is requested to keep a single safepoint and
1839 // no safepoint was found on idom-path. It is not safe to remove any safepoint
1840 // in this case since there's no safepoint dominating all paths in the loop body.
1841 bool prune = !keep_one || keep != NULL;
1842
1843 // Delete other safepoints in this loop.
1844 Node_List* sfpts = _safepts;
1845 if (prune && sfpts != NULL) {
1846 assert(keep == NULL || keep->Opcode() == Op_SafePoint, "not safepoint");
1847 for (uint i = 0; i < sfpts->size(); i++) {
1848 Node* n = sfpts->at(i);
1849 assert(phase->get_loop(n) == this, "");
1850 if (n != keep && phase->is_deleteable_safept(n)) {
1851 phase->lazy_replace(n, n->in(TypeFunc::Control));
1852 }
1853 }
1854 }
1855 }
1856
1857 //------------------------------counted_loop-----------------------------------
1858 // Convert to counted loops where possible
1859 void IdealLoopTree::counted_loop( PhaseIdealLoop *phase ) {
1860
1861 // For grins, set the inner-loop flag here
1862 if (!_child) {
1863 if (_head->is_Loop()) _head->as_Loop()->set_inner_loop();
1864 }
1865
1866 if (_head->is_CountedLoop() ||
1867 phase->is_counted_loop(_head, this)) {
1868
1869 if (!UseCountedLoopSafepoints) {
1870 // Indicate we do not need a safepoint here
1871 _has_sfpt = 1;
1872 }
1873
1874 // Remove safepoints
1875 bool keep_one_sfpt = !(_has_call || _has_sfpt);
1876 remove_safepoints(phase, keep_one_sfpt);
1877
1878 // Look for induction variables
1879 phase->replace_parallel_iv(this);
1880
1881 } else if (_parent != NULL && !_irreducible) {
1882 // Not a counted loop. Keep one safepoint.
1883 bool keep_one_sfpt = true;
1884 remove_safepoints(phase, keep_one_sfpt);
1885 }
1886
1887 // Recursively
1888 if (_child) _child->counted_loop( phase );
1889 if (_next) _next ->counted_loop( phase );
1890 }
1891
1892 #ifndef PRODUCT
1893 //------------------------------dump_head--------------------------------------
1894 // Dump 1 liner for loop header info
1895 void IdealLoopTree::dump_head( ) const {
1896 for (uint i=0; i<_nest; i++)
1897 tty->print(" ");
1898 tty->print("Loop: N%d/N%d ",_head->_idx,_tail->_idx);
1899 if (_irreducible) tty->print(" IRREDUCIBLE");
1900 Node* entry = _head->in(LoopNode::EntryControl);
1901 if (LoopLimitCheck) {
1902 Node* predicate = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
1903 if (predicate != NULL ) {
1904 tty->print(" limit_check");
1905 entry = entry->in(0)->in(0);
1906 }
1907 }
1908 if (UseLoopPredicate) {
1909 entry = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
1910 if (entry != NULL) {
1911 tty->print(" predicated");
1912 }
1913 }
1914 if (_head->is_CountedLoop()) {
1915 CountedLoopNode *cl = _head->as_CountedLoop();
1916 tty->print(" counted");
1917
1918 Node* init_n = cl->init_trip();
1919 if (init_n != NULL && init_n->is_Con())
1920 tty->print(" [%d,", cl->init_trip()->get_int());
1921 else
1922 tty->print(" [int,");
1923 Node* limit_n = cl->limit();
1924 if (limit_n != NULL && limit_n->is_Con())
1925 tty->print("%d),", cl->limit()->get_int());
1926 else
1927 tty->print("int),");
1928 int stride_con = cl->stride_con();
1929 if (stride_con > 0) tty->print("+");
1930 tty->print("%d", stride_con);
1931
1932 tty->print(" (%0.f iters) ", cl->profile_trip_cnt());
1933
1934 if (cl->is_pre_loop ()) tty->print(" pre" );
1935 if (cl->is_main_loop()) tty->print(" main");
1936 if (cl->is_post_loop()) tty->print(" post");
1937 }
1938 if (_has_call) tty->print(" has_call");
1939 if (_has_sfpt) tty->print(" has_sfpt");
1940 if (_rce_candidate) tty->print(" rce");
1941 if (_safepts != NULL && _safepts->size() > 0) {
1942 tty->print(" sfpts={"); _safepts->dump_simple(); tty->print(" }");
1943 }
1944 if (_required_safept != NULL && _required_safept->size() > 0) {
1945 tty->print(" req={"); _required_safept->dump_simple(); tty->print(" }");
1946 }
1947 tty->cr();
1948 }
1949
1950 //------------------------------dump-------------------------------------------
1951 // Dump loops by loop tree
1952 void IdealLoopTree::dump( ) const {
1953 dump_head();
1954 if (_child) _child->dump();
1955 if (_next) _next ->dump();
1956 }
1957
1958 #endif
1959
1960 static void log_loop_tree(IdealLoopTree* root, IdealLoopTree* loop, CompileLog* log) {
1961 if (loop == root) {
1962 if (loop->_child != NULL) {
1963 log->begin_head("loop_tree");
1964 log->end_head();
1965 if( loop->_child ) log_loop_tree(root, loop->_child, log);
1966 log->tail("loop_tree");
1967 assert(loop->_next == NULL, "what?");
1968 }
1969 } else {
1970 Node* head = loop->_head;
1971 log->begin_head("loop");
1972 log->print(" idx='%d' ", head->_idx);
1973 if (loop->_irreducible) log->print("irreducible='1' ");
1974 if (head->is_Loop()) {
1975 if (head->as_Loop()->is_inner_loop()) log->print("inner_loop='1' ");
1976 if (head->as_Loop()->is_partial_peel_loop()) log->print("partial_peel_loop='1' ");
1977 }
1978 if (head->is_CountedLoop()) {
1979 CountedLoopNode* cl = head->as_CountedLoop();
1980 if (cl->is_pre_loop()) log->print("pre_loop='%d' ", cl->main_idx());
1981 if (cl->is_main_loop()) log->print("main_loop='%d' ", cl->_idx);
1982 if (cl->is_post_loop()) log->print("post_loop='%d' ", cl->main_idx());
1983 }
1984 log->end_head();
1985 if( loop->_child ) log_loop_tree(root, loop->_child, log);
1986 log->tail("loop");
1987 if( loop->_next ) log_loop_tree(root, loop->_next, log);
1988 }
1989 }
1990
1991 //---------------------collect_potentially_useful_predicates-----------------------
1992 // Helper function to collect potentially useful predicates to prevent them from
1993 // being eliminated by PhaseIdealLoop::eliminate_useless_predicates
1994 void PhaseIdealLoop::collect_potentially_useful_predicates(
1995 IdealLoopTree * loop, Unique_Node_List &useful_predicates) {
1996 if (loop->_child) { // child
1997 collect_potentially_useful_predicates(loop->_child, useful_predicates);
1998 }
1999
2000 // self (only loops that we can apply loop predication may use their predicates)
2001 if (loop->_head->is_Loop() &&
2002 !loop->_irreducible &&
2003 !loop->tail()->is_top()) {
2004 LoopNode* lpn = loop->_head->as_Loop();
2005 Node* entry = lpn->in(LoopNode::EntryControl);
2006 Node* predicate_proj = find_predicate(entry); // loop_limit_check first
2007 if (predicate_proj != NULL ) { // right pattern that can be used by loop predication
2008 assert(entry->in(0)->in(1)->in(1)->Opcode() == Op_Opaque1, "must be");
2009 useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one
2010 entry = entry->in(0)->in(0);
2011 }
2012 predicate_proj = find_predicate(entry); // Predicate
2013 if (predicate_proj != NULL ) {
2014 useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one
2015 }
2016 }
2017
2018 if (loop->_next) { // sibling
2019 collect_potentially_useful_predicates(loop->_next, useful_predicates);
2020 }
2021 }
2022
2023 //------------------------eliminate_useless_predicates-----------------------------
2024 // Eliminate all inserted predicates if they could not be used by loop predication.
2025 // Note: it will also eliminates loop limits check predicate since it also uses
2026 // Opaque1 node (see Parse::add_predicate()).
2027 void PhaseIdealLoop::eliminate_useless_predicates() {
2028 if (C->predicate_count() == 0)
2029 return; // no predicate left
2030
2031 Unique_Node_List useful_predicates; // to store useful predicates
2032 if (C->has_loops()) {
2033 collect_potentially_useful_predicates(_ltree_root->_child, useful_predicates);
2034 }
2035
2036 for (int i = C->predicate_count(); i > 0; i--) {
2037 Node * n = C->predicate_opaque1_node(i-1);
2038 assert(n->Opcode() == Op_Opaque1, "must be");
2039 if (!useful_predicates.member(n)) { // not in the useful list
2040 _igvn.replace_node(n, n->in(1));
2041 }
2042 }
2043 }
2044
2045 //------------------------process_expensive_nodes-----------------------------
2046 // Expensive nodes have their control input set to prevent the GVN
2047 // from commoning them and as a result forcing the resulting node to
2048 // be in a more frequent path. Use CFG information here, to change the
2049 // control inputs so that some expensive nodes can be commoned while
2050 // not executed more frequently.
2051 bool PhaseIdealLoop::process_expensive_nodes() {
2052 assert(OptimizeExpensiveOps, "optimization off?");
2053
2054 // Sort nodes to bring similar nodes together
2055 C->sort_expensive_nodes();
2056
2057 bool progress = false;
2058
2059 for (int i = 0; i < C->expensive_count(); ) {
2060 Node* n = C->expensive_node(i);
2061 int start = i;
2062 // Find nodes similar to n
2063 i++;
2064 for (; i < C->expensive_count() && Compile::cmp_expensive_nodes(n, C->expensive_node(i)) == 0; i++);
2065 int end = i;
2066 // And compare them two by two
2067 for (int j = start; j < end; j++) {
2068 Node* n1 = C->expensive_node(j);
2069 if (is_node_unreachable(n1)) {
2070 continue;
2071 }
2072 for (int k = j+1; k < end; k++) {
2073 Node* n2 = C->expensive_node(k);
2074 if (is_node_unreachable(n2)) {
2075 continue;
2076 }
2077
2078 assert(n1 != n2, "should be pair of nodes");
2079
2080 Node* c1 = n1->in(0);
2081 Node* c2 = n2->in(0);
2082
2083 Node* parent_c1 = c1;
2084 Node* parent_c2 = c2;
2085
2086 // The call to get_early_ctrl_for_expensive() moves the
2087 // expensive nodes up but stops at loops that are in a if
2088 // branch. See whether we can exit the loop and move above the
2089 // If.
2090 if (c1->is_Loop()) {
2091 parent_c1 = c1->in(1);
2092 }
2093 if (c2->is_Loop()) {
2094 parent_c2 = c2->in(1);
2095 }
2096
2097 if (parent_c1 == parent_c2) {
2098 _igvn._worklist.push(n1);
2099 _igvn._worklist.push(n2);
2100 continue;
2101 }
2102
2103 // Look for identical expensive node up the dominator chain.
2104 if (is_dominator(c1, c2)) {
2105 c2 = c1;
2106 } else if (is_dominator(c2, c1)) {
2107 c1 = c2;
2108 } else if (parent_c1->is_Proj() && parent_c1->in(0)->is_If() &&
2109 parent_c2->is_Proj() && parent_c1->in(0) == parent_c2->in(0)) {
2110 // Both branches have the same expensive node so move it up
2111 // before the if.
2112 c1 = c2 = idom(parent_c1->in(0));
2113 }
2114 // Do the actual moves
2115 if (n1->in(0) != c1) {
2116 _igvn.hash_delete(n1);
2117 n1->set_req(0, c1);
2118 _igvn.hash_insert(n1);
2119 _igvn._worklist.push(n1);
2120 progress = true;
2121 }
2122 if (n2->in(0) != c2) {
2123 _igvn.hash_delete(n2);
2124 n2->set_req(0, c2);
2125 _igvn.hash_insert(n2);
2126 _igvn._worklist.push(n2);
2127 progress = true;
2128 }
2129 }
2130 }
2131 }
2132
2133 return progress;
2134 }
2135
2136
2137 //=============================================================================
2138 //----------------------------build_and_optimize-------------------------------
2139 // Create a PhaseLoop. Build the ideal Loop tree. Map each Ideal Node to
2140 // its corresponding LoopNode. If 'optimize' is true, do some loop cleanups.
2141 void PhaseIdealLoop::build_and_optimize(bool do_split_ifs, bool skip_loop_opts) {
2142 ResourceMark rm;
2143
2144 int old_progress = C->major_progress();
2145 uint orig_worklist_size = _igvn._worklist.size();
2146
2147 // Reset major-progress flag for the driver's heuristics
2148 C->clear_major_progress();
2149
2150 #ifndef PRODUCT
2151 // Capture for later assert
2152 uint unique = C->unique();
2153 _loop_invokes++;
2154 _loop_work += unique;
2155 #endif
2156
2157 // True if the method has at least 1 irreducible loop
2158 _has_irreducible_loops = false;
2159
2160 _created_loop_node = false;
2161
2162 Arena *a = Thread::current()->resource_area();
2163 VectorSet visited(a);
2164 // Pre-grow the mapping from Nodes to IdealLoopTrees.
2165 _nodes.map(C->unique(), NULL);
2166 memset(_nodes.adr(), 0, wordSize * C->unique());
2167
2168 // Pre-build the top-level outermost loop tree entry
2169 _ltree_root = new IdealLoopTree( this, C->root(), C->root() );
2170 // Do not need a safepoint at the top level
2171 _ltree_root->_has_sfpt = 1;
2172
2173 // Initialize Dominators.
2174 // Checked in clone_loop_predicate() during beautify_loops().
2175 _idom_size = 0;
2176 _idom = NULL;
2177 _dom_depth = NULL;
2178 _dom_stk = NULL;
2179
2180 // Empty pre-order array
2181 allocate_preorders();
2182
2183 // Build a loop tree on the fly. Build a mapping from CFG nodes to
2184 // IdealLoopTree entries. Data nodes are NOT walked.
2185 build_loop_tree();
2186 // Check for bailout, and return
2187 if (C->failing()) {
2188 return;
2189 }
2190
2191 // No loops after all
2192 if( !_ltree_root->_child && !_verify_only ) C->set_has_loops(false);
2193
2194 // There should always be an outer loop containing the Root and Return nodes.
2195 // If not, we have a degenerate empty program. Bail out in this case.
2196 if (!has_node(C->root())) {
2197 if (!_verify_only) {
2198 C->clear_major_progress();
2199 C->record_method_not_compilable("empty program detected during loop optimization");
2200 }
2201 return;
2202 }
2203
2204 // Nothing to do, so get out
2205 bool stop_early = !C->has_loops() && !skip_loop_opts && !do_split_ifs && !_verify_me && !_verify_only;
2206 bool do_expensive_nodes = C->should_optimize_expensive_nodes(_igvn);
2207 if (stop_early && !do_expensive_nodes) {
2208 _igvn.optimize(); // Cleanup NeverBranches
2209 return;
2210 }
2211
2212 // Set loop nesting depth
2213 _ltree_root->set_nest( 0 );
2214
2215 // Split shared headers and insert loop landing pads.
2216 // Do not bother doing this on the Root loop of course.
2217 if( !_verify_me && !_verify_only && _ltree_root->_child ) {
2218 C->print_method(PHASE_BEFORE_BEAUTIFY_LOOPS, 3);
2219 if( _ltree_root->_child->beautify_loops( this ) ) {
2220 // Re-build loop tree!
2221 _ltree_root->_child = NULL;
2222 _nodes.clear();
2223 reallocate_preorders();
2224 build_loop_tree();
2225 // Check for bailout, and return
2226 if (C->failing()) {
2227 return;
2228 }
2229 // Reset loop nesting depth
2230 _ltree_root->set_nest( 0 );
2231
2232 C->print_method(PHASE_AFTER_BEAUTIFY_LOOPS, 3);
2233 }
2234 }
2235
2236 // Build Dominators for elision of NULL checks & loop finding.
2237 // Since nodes do not have a slot for immediate dominator, make
2238 // a persistent side array for that info indexed on node->_idx.
2239 _idom_size = C->unique();
2240 _idom = NEW_RESOURCE_ARRAY( Node*, _idom_size );
2241 _dom_depth = NEW_RESOURCE_ARRAY( uint, _idom_size );
2242 _dom_stk = NULL; // Allocated on demand in recompute_dom_depth
2243 memset( _dom_depth, 0, _idom_size * sizeof(uint) );
2244
2245 Dominators();
2246
2247 if (!_verify_only) {
2248 // As a side effect, Dominators removed any unreachable CFG paths
2249 // into RegionNodes. It doesn't do this test against Root, so
2250 // we do it here.
2251 for( uint i = 1; i < C->root()->req(); i++ ) {
2252 if( !_nodes[C->root()->in(i)->_idx] ) { // Dead path into Root?
2253 _igvn.delete_input_of(C->root(), i);
2254 i--; // Rerun same iteration on compressed edges
2255 }
2256 }
2257
2258 // Given dominators, try to find inner loops with calls that must
2259 // always be executed (call dominates loop tail). These loops do
2260 // not need a separate safepoint.
2261 Node_List cisstack(a);
2262 _ltree_root->check_safepts(visited, cisstack);
2263 }
2264
2265 // Walk the DATA nodes and place into loops. Find earliest control
2266 // node. For CFG nodes, the _nodes array starts out and remains
2267 // holding the associated IdealLoopTree pointer. For DATA nodes, the
2268 // _nodes array holds the earliest legal controlling CFG node.
2269
2270 // Allocate stack with enough space to avoid frequent realloc
2271 int stack_size = (C->live_nodes() >> 1) + 16; // (live_nodes>>1)+16 from Java2D stats
2272 Node_Stack nstack( a, stack_size );
2273
2274 visited.Clear();
2275 Node_List worklist(a);
2276 // Don't need C->root() on worklist since
2277 // it will be processed among C->top() inputs
2278 worklist.push( C->top() );
2279 visited.set( C->top()->_idx ); // Set C->top() as visited now
2280 build_loop_early( visited, worklist, nstack );
2281
2282 // Given early legal placement, try finding counted loops. This placement
2283 // is good enough to discover most loop invariants.
2284 if( !_verify_me && !_verify_only )
2285 _ltree_root->counted_loop( this );
2286
2287 // Find latest loop placement. Find ideal loop placement.
2288 visited.Clear();
2289 init_dom_lca_tags();
2290 // Need C->root() on worklist when processing outs
2291 worklist.push( C->root() );
2292 NOT_PRODUCT( C->verify_graph_edges(); )
2293 worklist.push( C->top() );
2294 build_loop_late( visited, worklist, nstack );
2295
2296 if (_verify_only) {
2297 // restore major progress flag
2298 for (int i = 0; i < old_progress; i++)
2299 C->set_major_progress();
2300 assert(C->unique() == unique, "verification mode made Nodes? ? ?");
2301 assert(_igvn._worklist.size() == orig_worklist_size, "shouldn't push anything");
2302 return;
2303 }
2304
2305 // clear out the dead code after build_loop_late
2306 while (_deadlist.size()) {
2307 _igvn.remove_globally_dead_node(_deadlist.pop());
2308 }
2309
2310 if (stop_early) {
2311 assert(do_expensive_nodes, "why are we here?");
2312 if (process_expensive_nodes()) {
2313 // If we made some progress when processing expensive nodes then
2314 // the IGVN may modify the graph in a way that will allow us to
2315 // make some more progress: we need to try processing expensive
2316 // nodes again.
2317 C->set_major_progress();
2318 }
2319 _igvn.optimize();
2320 return;
2321 }
2322
2323 // Some parser-inserted loop predicates could never be used by loop
2324 // predication or they were moved away from loop during some optimizations.
2325 // For example, peeling. Eliminate them before next loop optimizations.
2326 if (UseLoopPredicate || LoopLimitCheck) {
2327 eliminate_useless_predicates();
2328 }
2329
2330 #ifndef PRODUCT
2331 C->verify_graph_edges();
2332 if (_verify_me) { // Nested verify pass?
2333 // Check to see if the verify mode is broken
2334 assert(C->unique() == unique, "non-optimize mode made Nodes? ? ?");
2335 return;
2336 }
2337 if(VerifyLoopOptimizations) verify();
2338 if(TraceLoopOpts && C->has_loops()) {
2339 _ltree_root->dump();
2340 }
2341 #endif
2342
2343 if (skip_loop_opts) {
2344 // restore major progress flag
2345 for (int i = 0; i < old_progress; i++) {
2346 C->set_major_progress();
2347 }
2348
2349 // Cleanup any modified bits
2350 _igvn.optimize();
2351
2352 if (C->log() != NULL) {
2353 log_loop_tree(_ltree_root, _ltree_root, C->log());
2354 }
2355 return;
2356 }
2357
2358 if (ReassociateInvariants) {
2359 // Reassociate invariants and prep for split_thru_phi
2360 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
2361 IdealLoopTree* lpt = iter.current();
2362 bool is_counted = lpt->is_counted();
2363 if (!is_counted || !lpt->is_inner()) continue;
2364
2365 // check for vectorized loops, any reassociation of invariants was already done
2366 if (is_counted && lpt->_head->as_CountedLoop()->do_unroll_only()) continue;
2367
2368 lpt->reassociate_invariants(this);
2369
2370 // Because RCE opportunities can be masked by split_thru_phi,
2371 // look for RCE candidates and inhibit split_thru_phi
2372 // on just their loop-phi's for this pass of loop opts
2373 if (SplitIfBlocks && do_split_ifs) {
2374 if (lpt->policy_range_check(this)) {
2375 lpt->_rce_candidate = 1; // = true
2376 }
2377 }
2378 }
2379 }
2380
2381 // Check for aggressive application of split-if and other transforms
2382 // that require basic-block info (like cloning through Phi's)
2383 if( SplitIfBlocks && do_split_ifs ) {
2384 visited.Clear();
2385 split_if_with_blocks( visited, nstack );
2386 NOT_PRODUCT( if( VerifyLoopOptimizations ) verify(); );
2387 }
2388
2389 if (!C->major_progress() && do_expensive_nodes && process_expensive_nodes()) {
2390 C->set_major_progress();
2391 }
2392
2393 // Perform loop predication before iteration splitting
2394 if (C->has_loops() && !C->major_progress() && (C->predicate_count() > 0)) {
2395 _ltree_root->_child->loop_predication(this);
2396 }
2397
2398 if (OptimizeFill && UseLoopPredicate && C->has_loops() && !C->major_progress()) {
2399 if (do_intrinsify_fill()) {
2400 C->set_major_progress();
2401 }
2402 }
2403
2404 // Perform iteration-splitting on inner loops. Split iterations to avoid
2405 // range checks or one-shot null checks.
2406
2407 // If split-if's didn't hack the graph too bad (no CFG changes)
2408 // then do loop opts.
2409 if (C->has_loops() && !C->major_progress()) {
2410 memset( worklist.adr(), 0, worklist.Size()*sizeof(Node*) );
2411 _ltree_root->_child->iteration_split( this, worklist );
2412 // No verify after peeling! GCM has hoisted code out of the loop.
2413 // After peeling, the hoisted code could sink inside the peeled area.
2414 // The peeling code does not try to recompute the best location for
2415 // all the code before the peeled area, so the verify pass will always
2416 // complain about it.
2417 }
2418 // Do verify graph edges in any case
2419 NOT_PRODUCT( C->verify_graph_edges(); );
2420
2421 if (!do_split_ifs) {
2422 // We saw major progress in Split-If to get here. We forced a
2423 // pass with unrolling and not split-if, however more split-if's
2424 // might make progress. If the unrolling didn't make progress
2425 // then the major-progress flag got cleared and we won't try
2426 // another round of Split-If. In particular the ever-common
2427 // instance-of/check-cast pattern requires at least 2 rounds of
2428 // Split-If to clear out.
2429 C->set_major_progress();
2430 }
2431
2432 // Repeat loop optimizations if new loops were seen
2433 if (created_loop_node()) {
2434 C->set_major_progress();
2435 }
2436
2437 // Keep loop predicates and perform optimizations with them
2438 // until no more loop optimizations could be done.
2439 // After that switch predicates off and do more loop optimizations.
2440 if (!C->major_progress() && (C->predicate_count() > 0)) {
2441 C->cleanup_loop_predicates(_igvn);
2442 if (TraceLoopOpts) {
2443 tty->print_cr("PredicatesOff");
2444 }
2445 C->set_major_progress();
2446 }
2447
2448 // Convert scalar to superword operations at the end of all loop opts.
2449 if (UseSuperWord && C->has_loops() && !C->major_progress()) {
2450 // SuperWord transform
2451 SuperWord sw(this);
2452 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
2453 IdealLoopTree* lpt = iter.current();
2454 if (lpt->is_counted()) {
2455 sw.transform_loop(lpt, true);
2456 }
2457 }
2458 }
2459
2460 // Cleanup any modified bits
2461 _igvn.optimize();
2462
2463 // disable assert until issue with split_flow_path is resolved (6742111)
2464 // assert(!_has_irreducible_loops || C->parsed_irreducible_loop() || C->is_osr_compilation(),
2465 // "shouldn't introduce irreducible loops");
2466
2467 if (C->log() != NULL) {
2468 log_loop_tree(_ltree_root, _ltree_root, C->log());
2469 }
2470 }
2471
2472 #ifndef PRODUCT
2473 //------------------------------print_statistics-------------------------------
2474 int PhaseIdealLoop::_loop_invokes=0;// Count of PhaseIdealLoop invokes
2475 int PhaseIdealLoop::_loop_work=0; // Sum of PhaseIdealLoop x unique
2476 void PhaseIdealLoop::print_statistics() {
2477 tty->print_cr("PhaseIdealLoop=%d, sum _unique=%d", _loop_invokes, _loop_work);
2478 }
2479
2480 //------------------------------verify-----------------------------------------
2481 // Build a verify-only PhaseIdealLoop, and see that it agrees with me.
2482 static int fail; // debug only, so its multi-thread dont care
2483 void PhaseIdealLoop::verify() const {
2484 int old_progress = C->major_progress();
2485 ResourceMark rm;
2486 PhaseIdealLoop loop_verify( _igvn, this );
2487 VectorSet visited(Thread::current()->resource_area());
2488
2489 fail = 0;
2490 verify_compare( C->root(), &loop_verify, visited );
2491 assert( fail == 0, "verify loops failed" );
2492 // Verify loop structure is the same
2493 _ltree_root->verify_tree(loop_verify._ltree_root, NULL);
2494 // Reset major-progress. It was cleared by creating a verify version of
2495 // PhaseIdealLoop.
2496 for( int i=0; i<old_progress; i++ )
2497 C->set_major_progress();
2498 }
2499
2500 //------------------------------verify_compare---------------------------------
2501 // Make sure me and the given PhaseIdealLoop agree on key data structures
2502 void PhaseIdealLoop::verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const {
2503 if( !n ) return;
2504 if( visited.test_set( n->_idx ) ) return;
2505 if( !_nodes[n->_idx] ) { // Unreachable
2506 assert( !loop_verify->_nodes[n->_idx], "both should be unreachable" );
2507 return;
2508 }
2509
2510 uint i;
2511 for( i = 0; i < n->req(); i++ )
2512 verify_compare( n->in(i), loop_verify, visited );
2513
2514 // Check the '_nodes' block/loop structure
2515 i = n->_idx;
2516 if( has_ctrl(n) ) { // We have control; verify has loop or ctrl
2517 if( _nodes[i] != loop_verify->_nodes[i] &&
2518 get_ctrl_no_update(n) != loop_verify->get_ctrl_no_update(n) ) {
2519 tty->print("Mismatched control setting for: ");
2520 n->dump();
2521 if( fail++ > 10 ) return;
2522 Node *c = get_ctrl_no_update(n);
2523 tty->print("We have it as: ");
2524 if( c->in(0) ) c->dump();
2525 else tty->print_cr("N%d",c->_idx);
2526 tty->print("Verify thinks: ");
2527 if( loop_verify->has_ctrl(n) )
2528 loop_verify->get_ctrl_no_update(n)->dump();
2529 else
2530 loop_verify->get_loop_idx(n)->dump();
2531 tty->cr();
2532 }
2533 } else { // We have a loop
2534 IdealLoopTree *us = get_loop_idx(n);
2535 if( loop_verify->has_ctrl(n) ) {
2536 tty->print("Mismatched loop setting for: ");
2537 n->dump();
2538 if( fail++ > 10 ) return;
2539 tty->print("We have it as: ");
2540 us->dump();
2541 tty->print("Verify thinks: ");
2542 loop_verify->get_ctrl_no_update(n)->dump();
2543 tty->cr();
2544 } else if (!C->major_progress()) {
2545 // Loop selection can be messed up if we did a major progress
2546 // operation, like split-if. Do not verify in that case.
2547 IdealLoopTree *them = loop_verify->get_loop_idx(n);
2548 if( us->_head != them->_head || us->_tail != them->_tail ) {
2549 tty->print("Unequals loops for: ");
2550 n->dump();
2551 if( fail++ > 10 ) return;
2552 tty->print("We have it as: ");
2553 us->dump();
2554 tty->print("Verify thinks: ");
2555 them->dump();
2556 tty->cr();
2557 }
2558 }
2559 }
2560
2561 // Check for immediate dominators being equal
2562 if( i >= _idom_size ) {
2563 if( !n->is_CFG() ) return;
2564 tty->print("CFG Node with no idom: ");
2565 n->dump();
2566 return;
2567 }
2568 if( !n->is_CFG() ) return;
2569 if( n == C->root() ) return; // No IDOM here
2570
2571 assert(n->_idx == i, "sanity");
2572 Node *id = idom_no_update(n);
2573 if( id != loop_verify->idom_no_update(n) ) {
2574 tty->print("Unequals idoms for: ");
2575 n->dump();
2576 if( fail++ > 10 ) return;
2577 tty->print("We have it as: ");
2578 id->dump();
2579 tty->print("Verify thinks: ");
2580 loop_verify->idom_no_update(n)->dump();
2581 tty->cr();
2582 }
2583
2584 }
2585
2586 //------------------------------verify_tree------------------------------------
2587 // Verify that tree structures match. Because the CFG can change, siblings
2588 // within the loop tree can be reordered. We attempt to deal with that by
2589 // reordering the verify's loop tree if possible.
2590 void IdealLoopTree::verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const {
2591 assert( _parent == parent, "Badly formed loop tree" );
2592
2593 // Siblings not in same order? Attempt to re-order.
2594 if( _head != loop->_head ) {
2595 // Find _next pointer to update
2596 IdealLoopTree **pp = &loop->_parent->_child;
2597 while( *pp != loop )
2598 pp = &((*pp)->_next);
2599 // Find proper sibling to be next
2600 IdealLoopTree **nn = &loop->_next;
2601 while( (*nn) && (*nn)->_head != _head )
2602 nn = &((*nn)->_next);
2603
2604 // Check for no match.
2605 if( !(*nn) ) {
2606 // Annoyingly, irreducible loops can pick different headers
2607 // after a major_progress operation, so the rest of the loop
2608 // tree cannot be matched.
2609 if (_irreducible && Compile::current()->major_progress()) return;
2610 assert( 0, "failed to match loop tree" );
2611 }
2612
2613 // Move (*nn) to (*pp)
2614 IdealLoopTree *hit = *nn;
2615 *nn = hit->_next;
2616 hit->_next = loop;
2617 *pp = loop;
2618 loop = hit;
2619 // Now try again to verify
2620 }
2621
2622 assert( _head == loop->_head , "mismatched loop head" );
2623 Node *tail = _tail; // Inline a non-updating version of
2624 while( !tail->in(0) ) // the 'tail()' call.
2625 tail = tail->in(1);
2626 assert( tail == loop->_tail, "mismatched loop tail" );
2627
2628 // Counted loops that are guarded should be able to find their guards
2629 if( _head->is_CountedLoop() && _head->as_CountedLoop()->is_main_loop() ) {
2630 CountedLoopNode *cl = _head->as_CountedLoop();
2631 Node *init = cl->init_trip();
2632 Node *ctrl = cl->in(LoopNode::EntryControl);
2633 assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" );
2634 Node *iff = ctrl->in(0);
2635 assert( iff->Opcode() == Op_If, "" );
2636 Node *bol = iff->in(1);
2637 assert( bol->Opcode() == Op_Bool, "" );
2638 Node *cmp = bol->in(1);
2639 assert( cmp->Opcode() == Op_CmpI, "" );
2640 Node *add = cmp->in(1);
2641 Node *opaq;
2642 if( add->Opcode() == Op_Opaque1 ) {
2643 opaq = add;
2644 } else {
2645 assert( add->Opcode() == Op_AddI || add->Opcode() == Op_ConI , "" );
2646 assert( add == init, "" );
2647 opaq = cmp->in(2);
2648 }
2649 assert( opaq->Opcode() == Op_Opaque1, "" );
2650
2651 }
2652
2653 if (_child != NULL) _child->verify_tree(loop->_child, this);
2654 if (_next != NULL) _next ->verify_tree(loop->_next, parent);
2655 // Innermost loops need to verify loop bodies,
2656 // but only if no 'major_progress'
2657 int fail = 0;
2658 if (!Compile::current()->major_progress() && _child == NULL) {
2659 for( uint i = 0; i < _body.size(); i++ ) {
2660 Node *n = _body.at(i);
2661 if (n->outcnt() == 0) continue; // Ignore dead
2662 uint j;
2663 for( j = 0; j < loop->_body.size(); j++ )
2664 if( loop->_body.at(j) == n )
2665 break;
2666 if( j == loop->_body.size() ) { // Not found in loop body
2667 // Last ditch effort to avoid assertion: Its possible that we
2668 // have some users (so outcnt not zero) but are still dead.
2669 // Try to find from root.
2670 if (Compile::current()->root()->find(n->_idx)) {
2671 fail++;
2672 tty->print("We have that verify does not: ");
2673 n->dump();
2674 }
2675 }
2676 }
2677 for( uint i2 = 0; i2 < loop->_body.size(); i2++ ) {
2678 Node *n = loop->_body.at(i2);
2679 if (n->outcnt() == 0) continue; // Ignore dead
2680 uint j;
2681 for( j = 0; j < _body.size(); j++ )
2682 if( _body.at(j) == n )
2683 break;
2684 if( j == _body.size() ) { // Not found in loop body
2685 // Last ditch effort to avoid assertion: Its possible that we
2686 // have some users (so outcnt not zero) but are still dead.
2687 // Try to find from root.
2688 if (Compile::current()->root()->find(n->_idx)) {
2689 fail++;
2690 tty->print("Verify has that we do not: ");
2691 n->dump();
2692 }
2693 }
2694 }
2695 assert( !fail, "loop body mismatch" );
2696 }
2697 }
2698
2699 #endif
2700
2701 //------------------------------set_idom---------------------------------------
2702 void PhaseIdealLoop::set_idom(Node* d, Node* n, uint dom_depth) {
2703 uint idx = d->_idx;
2704 if (idx >= _idom_size) {
2705 uint newsize = _idom_size<<1;
2706 while( idx >= newsize ) {
2707 newsize <<= 1;
2708 }
2709 _idom = REALLOC_RESOURCE_ARRAY( Node*, _idom,_idom_size,newsize);
2710 _dom_depth = REALLOC_RESOURCE_ARRAY( uint, _dom_depth,_idom_size,newsize);
2711 memset( _dom_depth + _idom_size, 0, (newsize - _idom_size) * sizeof(uint) );
2712 _idom_size = newsize;
2713 }
2714 _idom[idx] = n;
2715 _dom_depth[idx] = dom_depth;
2716 }
2717
2718 //------------------------------recompute_dom_depth---------------------------------------
2719 // The dominator tree is constructed with only parent pointers.
2720 // This recomputes the depth in the tree by first tagging all
2721 // nodes as "no depth yet" marker. The next pass then runs up
2722 // the dom tree from each node marked "no depth yet", and computes
2723 // the depth on the way back down.
2724 void PhaseIdealLoop::recompute_dom_depth() {
2725 uint no_depth_marker = C->unique();
2726 uint i;
2727 // Initialize depth to "no depth yet"
2728 for (i = 0; i < _idom_size; i++) {
2729 if (_dom_depth[i] > 0 && _idom[i] != NULL) {
2730 _dom_depth[i] = no_depth_marker;
2731 }
2732 }
2733 if (_dom_stk == NULL) {
2734 uint init_size = C->live_nodes() / 100; // Guess that 1/100 is a reasonable initial size.
2735 if (init_size < 10) init_size = 10;
2736 _dom_stk = new GrowableArray<uint>(init_size);
2737 }
2738 // Compute new depth for each node.
2739 for (i = 0; i < _idom_size; i++) {
2740 uint j = i;
2741 // Run up the dom tree to find a node with a depth
2742 while (_dom_depth[j] == no_depth_marker) {
2743 _dom_stk->push(j);
2744 j = _idom[j]->_idx;
2745 }
2746 // Compute the depth on the way back down this tree branch
2747 uint dd = _dom_depth[j] + 1;
2748 while (_dom_stk->length() > 0) {
2749 uint j = _dom_stk->pop();
2750 _dom_depth[j] = dd;
2751 dd++;
2752 }
2753 }
2754 }
2755
2756 //------------------------------sort-------------------------------------------
2757 // Insert 'loop' into the existing loop tree. 'innermost' is a leaf of the
2758 // loop tree, not the root.
2759 IdealLoopTree *PhaseIdealLoop::sort( IdealLoopTree *loop, IdealLoopTree *innermost ) {
2760 if( !innermost ) return loop; // New innermost loop
2761
2762 int loop_preorder = get_preorder(loop->_head); // Cache pre-order number
2763 assert( loop_preorder, "not yet post-walked loop" );
2764 IdealLoopTree **pp = &innermost; // Pointer to previous next-pointer
2765 IdealLoopTree *l = *pp; // Do I go before or after 'l'?
2766
2767 // Insert at start of list
2768 while( l ) { // Insertion sort based on pre-order
2769 if( l == loop ) return innermost; // Already on list!
2770 int l_preorder = get_preorder(l->_head); // Cache pre-order number
2771 assert( l_preorder, "not yet post-walked l" );
2772 // Check header pre-order number to figure proper nesting
2773 if( loop_preorder > l_preorder )
2774 break; // End of insertion
2775 // If headers tie (e.g., shared headers) check tail pre-order numbers.
2776 // Since I split shared headers, you'd think this could not happen.
2777 // BUT: I must first do the preorder numbering before I can discover I
2778 // have shared headers, so the split headers all get the same preorder
2779 // number as the RegionNode they split from.
2780 if( loop_preorder == l_preorder &&
2781 get_preorder(loop->_tail) < get_preorder(l->_tail) )
2782 break; // Also check for shared headers (same pre#)
2783 pp = &l->_parent; // Chain up list
2784 l = *pp;
2785 }
2786 // Link into list
2787 // Point predecessor to me
2788 *pp = loop;
2789 // Point me to successor
2790 IdealLoopTree *p = loop->_parent;
2791 loop->_parent = l; // Point me to successor
2792 if( p ) sort( p, innermost ); // Insert my parents into list as well
2793 return innermost;
2794 }
2795
2796 //------------------------------build_loop_tree--------------------------------
2797 // I use a modified Vick/Tarjan algorithm. I need pre- and a post- visit
2798 // bits. The _nodes[] array is mapped by Node index and holds a NULL for
2799 // not-yet-pre-walked, pre-order # for pre-but-not-post-walked and holds the
2800 // tightest enclosing IdealLoopTree for post-walked.
2801 //
2802 // During my forward walk I do a short 1-layer lookahead to see if I can find
2803 // a loop backedge with that doesn't have any work on the backedge. This
2804 // helps me construct nested loops with shared headers better.
2805 //
2806 // Once I've done the forward recursion, I do the post-work. For each child
2807 // I check to see if there is a backedge. Backedges define a loop! I
2808 // insert an IdealLoopTree at the target of the backedge.
2809 //
2810 // During the post-work I also check to see if I have several children
2811 // belonging to different loops. If so, then this Node is a decision point
2812 // where control flow can choose to change loop nests. It is at this
2813 // decision point where I can figure out how loops are nested. At this
2814 // time I can properly order the different loop nests from my children.
2815 // Note that there may not be any backedges at the decision point!
2816 //
2817 // Since the decision point can be far removed from the backedges, I can't
2818 // order my loops at the time I discover them. Thus at the decision point
2819 // I need to inspect loop header pre-order numbers to properly nest my
2820 // loops. This means I need to sort my childrens' loops by pre-order.
2821 // The sort is of size number-of-control-children, which generally limits
2822 // it to size 2 (i.e., I just choose between my 2 target loops).
2823 void PhaseIdealLoop::build_loop_tree() {
2824 // Allocate stack of size C->live_nodes()/2 to avoid frequent realloc
2825 GrowableArray <Node *> bltstack(C->live_nodes() >> 1);
2826 Node *n = C->root();
2827 bltstack.push(n);
2828 int pre_order = 1;
2829 int stack_size;
2830
2831 while ( ( stack_size = bltstack.length() ) != 0 ) {
2832 n = bltstack.top(); // Leave node on stack
2833 if ( !is_visited(n) ) {
2834 // ---- Pre-pass Work ----
2835 // Pre-walked but not post-walked nodes need a pre_order number.
2836
2837 set_preorder_visited( n, pre_order ); // set as visited
2838
2839 // ---- Scan over children ----
2840 // Scan first over control projections that lead to loop headers.
2841 // This helps us find inner-to-outer loops with shared headers better.
2842
2843 // Scan children's children for loop headers.
2844 for ( int i = n->outcnt() - 1; i >= 0; --i ) {
2845 Node* m = n->raw_out(i); // Child
2846 if( m->is_CFG() && !is_visited(m) ) { // Only for CFG children
2847 // Scan over children's children to find loop
2848 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
2849 Node* l = m->fast_out(j);
2850 if( is_visited(l) && // Been visited?
2851 !is_postvisited(l) && // But not post-visited
2852 get_preorder(l) < pre_order ) { // And smaller pre-order
2853 // Found! Scan the DFS down this path before doing other paths
2854 bltstack.push(m);
2855 break;
2856 }
2857 }
2858 }
2859 }
2860 pre_order++;
2861 }
2862 else if ( !is_postvisited(n) ) {
2863 // Note: build_loop_tree_impl() adds out edges on rare occasions,
2864 // such as com.sun.rsasign.am::a.
2865 // For non-recursive version, first, process current children.
2866 // On next iteration, check if additional children were added.
2867 for ( int k = n->outcnt() - 1; k >= 0; --k ) {
2868 Node* u = n->raw_out(k);
2869 if ( u->is_CFG() && !is_visited(u) ) {
2870 bltstack.push(u);
2871 }
2872 }
2873 if ( bltstack.length() == stack_size ) {
2874 // There were no additional children, post visit node now
2875 (void)bltstack.pop(); // Remove node from stack
2876 pre_order = build_loop_tree_impl( n, pre_order );
2877 // Check for bailout
2878 if (C->failing()) {
2879 return;
2880 }
2881 // Check to grow _preorders[] array for the case when
2882 // build_loop_tree_impl() adds new nodes.
2883 check_grow_preorders();
2884 }
2885 }
2886 else {
2887 (void)bltstack.pop(); // Remove post-visited node from stack
2888 }
2889 }
2890 }
2891
2892 //------------------------------build_loop_tree_impl---------------------------
2893 int PhaseIdealLoop::build_loop_tree_impl( Node *n, int pre_order ) {
2894 // ---- Post-pass Work ----
2895 // Pre-walked but not post-walked nodes need a pre_order number.
2896
2897 // Tightest enclosing loop for this Node
2898 IdealLoopTree *innermost = NULL;
2899
2900 // For all children, see if any edge is a backedge. If so, make a loop
2901 // for it. Then find the tightest enclosing loop for the self Node.
2902 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2903 Node* m = n->fast_out(i); // Child
2904 if( n == m ) continue; // Ignore control self-cycles
2905 if( !m->is_CFG() ) continue;// Ignore non-CFG edges
2906
2907 IdealLoopTree *l; // Child's loop
2908 if( !is_postvisited(m) ) { // Child visited but not post-visited?
2909 // Found a backedge
2910 assert( get_preorder(m) < pre_order, "should be backedge" );
2911 // Check for the RootNode, which is already a LoopNode and is allowed
2912 // to have multiple "backedges".
2913 if( m == C->root()) { // Found the root?
2914 l = _ltree_root; // Root is the outermost LoopNode
2915 } else { // Else found a nested loop
2916 // Insert a LoopNode to mark this loop.
2917 l = new IdealLoopTree(this, m, n);
2918 } // End of Else found a nested loop
2919 if( !has_loop(m) ) // If 'm' does not already have a loop set
2920 set_loop(m, l); // Set loop header to loop now
2921
2922 } else { // Else not a nested loop
2923 if( !_nodes[m->_idx] ) continue; // Dead code has no loop
2924 l = get_loop(m); // Get previously determined loop
2925 // If successor is header of a loop (nest), move up-loop till it
2926 // is a member of some outer enclosing loop. Since there are no
2927 // shared headers (I've split them already) I only need to go up
2928 // at most 1 level.
2929 while( l && l->_head == m ) // Successor heads loop?
2930 l = l->_parent; // Move up 1 for me
2931 // If this loop is not properly parented, then this loop
2932 // has no exit path out, i.e. its an infinite loop.
2933 if( !l ) {
2934 // Make loop "reachable" from root so the CFG is reachable. Basically
2935 // insert a bogus loop exit that is never taken. 'm', the loop head,
2936 // points to 'n', one (of possibly many) fall-in paths. There may be
2937 // many backedges as well.
2938
2939 // Here I set the loop to be the root loop. I could have, after
2940 // inserting a bogus loop exit, restarted the recursion and found my
2941 // new loop exit. This would make the infinite loop a first-class
2942 // loop and it would then get properly optimized. What's the use of
2943 // optimizing an infinite loop?
2944 l = _ltree_root; // Oops, found infinite loop
2945
2946 if (!_verify_only) {
2947 // Insert the NeverBranch between 'm' and it's control user.
2948 NeverBranchNode *iff = new NeverBranchNode( m );
2949 _igvn.register_new_node_with_optimizer(iff);
2950 set_loop(iff, l);
2951 Node *if_t = new CProjNode( iff, 0 );
2952 _igvn.register_new_node_with_optimizer(if_t);
2953 set_loop(if_t, l);
2954
2955 Node* cfg = NULL; // Find the One True Control User of m
2956 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
2957 Node* x = m->fast_out(j);
2958 if (x->is_CFG() && x != m && x != iff)
2959 { cfg = x; break; }
2960 }
2961 assert(cfg != NULL, "must find the control user of m");
2962 uint k = 0; // Probably cfg->in(0)
2963 while( cfg->in(k) != m ) k++; // But check incase cfg is a Region
2964 cfg->set_req( k, if_t ); // Now point to NeverBranch
2965 _igvn._worklist.push(cfg);
2966
2967 // Now create the never-taken loop exit
2968 Node *if_f = new CProjNode( iff, 1 );
2969 _igvn.register_new_node_with_optimizer(if_f);
2970 set_loop(if_f, l);
2971 // Find frame ptr for Halt. Relies on the optimizer
2972 // V-N'ing. Easier and quicker than searching through
2973 // the program structure.
2974 Node *frame = new ParmNode( C->start(), TypeFunc::FramePtr );
2975 _igvn.register_new_node_with_optimizer(frame);
2976 // Halt & Catch Fire
2977 Node *halt = new HaltNode( if_f, frame );
2978 _igvn.register_new_node_with_optimizer(halt);
2979 set_loop(halt, l);
2980 C->root()->add_req(halt);
2981 }
2982 set_loop(C->root(), _ltree_root);
2983 }
2984 }
2985 // Weeny check for irreducible. This child was already visited (this
2986 // IS the post-work phase). Is this child's loop header post-visited
2987 // as well? If so, then I found another entry into the loop.
2988 if (!_verify_only) {
2989 while( is_postvisited(l->_head) ) {
2990 // found irreducible
2991 l->_irreducible = 1; // = true
2992 l = l->_parent;
2993 _has_irreducible_loops = true;
2994 // Check for bad CFG here to prevent crash, and bailout of compile
2995 if (l == NULL) {
2996 C->record_method_not_compilable("unhandled CFG detected during loop optimization");
2997 return pre_order;
2998 }
2999 }
3000 C->set_has_irreducible_loop(_has_irreducible_loops);
3001 }
3002
3003 // This Node might be a decision point for loops. It is only if
3004 // it's children belong to several different loops. The sort call
3005 // does a trivial amount of work if there is only 1 child or all
3006 // children belong to the same loop. If however, the children
3007 // belong to different loops, the sort call will properly set the
3008 // _parent pointers to show how the loops nest.
3009 //
3010 // In any case, it returns the tightest enclosing loop.
3011 innermost = sort( l, innermost );
3012 }
3013
3014 // Def-use info will have some dead stuff; dead stuff will have no
3015 // loop decided on.
3016
3017 // Am I a loop header? If so fix up my parent's child and next ptrs.
3018 if( innermost && innermost->_head == n ) {
3019 assert( get_loop(n) == innermost, "" );
3020 IdealLoopTree *p = innermost->_parent;
3021 IdealLoopTree *l = innermost;
3022 while( p && l->_head == n ) {
3023 l->_next = p->_child; // Put self on parents 'next child'
3024 p->_child = l; // Make self as first child of parent
3025 l = p; // Now walk up the parent chain
3026 p = l->_parent;
3027 }
3028 } else {
3029 // Note that it is possible for a LoopNode to reach here, if the
3030 // backedge has been made unreachable (hence the LoopNode no longer
3031 // denotes a Loop, and will eventually be removed).
3032
3033 // Record tightest enclosing loop for self. Mark as post-visited.
3034 set_loop(n, innermost);
3035 // Also record has_call flag early on
3036 if( innermost ) {
3037 if( n->is_Call() && !n->is_CallLeaf() && !n->is_macro() ) {
3038 // Do not count uncommon calls
3039 if( !n->is_CallStaticJava() || !n->as_CallStaticJava()->_name ) {
3040 Node *iff = n->in(0)->in(0);
3041 // No any calls for vectorized loops.
3042 if( UseSuperWord || !iff->is_If() ||
3043 (n->in(0)->Opcode() == Op_IfFalse &&
3044 (1.0 - iff->as_If()->_prob) >= 0.01) ||
3045 (iff->as_If()->_prob >= 0.01) )
3046 innermost->_has_call = 1;
3047 }
3048 } else if( n->is_Allocate() && n->as_Allocate()->_is_scalar_replaceable ) {
3049 // Disable loop optimizations if the loop has a scalar replaceable
3050 // allocation. This disabling may cause a potential performance lost
3051 // if the allocation is not eliminated for some reason.
3052 innermost->_allow_optimizations = false;
3053 innermost->_has_call = 1; // = true
3054 } else if (n->Opcode() == Op_SafePoint) {
3055 // Record all safepoints in this loop.
3056 if (innermost->_safepts == NULL) innermost->_safepts = new Node_List();
3057 innermost->_safepts->push(n);
3058 }
3059 }
3060 }
3061
3062 // Flag as post-visited now
3063 set_postvisited(n);
3064 return pre_order;
3065 }
3066
3067
3068 //------------------------------build_loop_early-------------------------------
3069 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
3070 // First pass computes the earliest controlling node possible. This is the
3071 // controlling input with the deepest dominating depth.
3072 void PhaseIdealLoop::build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) {
3073 while (worklist.size() != 0) {
3074 // Use local variables nstack_top_n & nstack_top_i to cache values
3075 // on nstack's top.
3076 Node *nstack_top_n = worklist.pop();
3077 uint nstack_top_i = 0;
3078 //while_nstack_nonempty:
3079 while (true) {
3080 // Get parent node and next input's index from stack's top.
3081 Node *n = nstack_top_n;
3082 uint i = nstack_top_i;
3083 uint cnt = n->req(); // Count of inputs
3084 if (i == 0) { // Pre-process the node.
3085 if( has_node(n) && // Have either loop or control already?
3086 !has_ctrl(n) ) { // Have loop picked out already?
3087 // During "merge_many_backedges" we fold up several nested loops
3088 // into a single loop. This makes the members of the original
3089 // loop bodies pointing to dead loops; they need to move up
3090 // to the new UNION'd larger loop. I set the _head field of these
3091 // dead loops to NULL and the _parent field points to the owning
3092 // loop. Shades of UNION-FIND algorithm.
3093 IdealLoopTree *ilt;
3094 while( !(ilt = get_loop(n))->_head ) {
3095 // Normally I would use a set_loop here. But in this one special
3096 // case, it is legal (and expected) to change what loop a Node
3097 // belongs to.
3098 _nodes.map(n->_idx, (Node*)(ilt->_parent) );
3099 }
3100 // Remove safepoints ONLY if I've already seen I don't need one.
3101 // (the old code here would yank a 2nd safepoint after seeing a
3102 // first one, even though the 1st did not dominate in the loop body
3103 // and thus could be avoided indefinitely)
3104 if( !_verify_only && !_verify_me && ilt->_has_sfpt && n->Opcode() == Op_SafePoint &&
3105 is_deleteable_safept(n)) {
3106 Node *in = n->in(TypeFunc::Control);
3107 lazy_replace(n,in); // Pull safepoint now
3108 if (ilt->_safepts != NULL) {
3109 ilt->_safepts->yank(n);
3110 }
3111 // Carry on with the recursion "as if" we are walking
3112 // only the control input
3113 if( !visited.test_set( in->_idx ) ) {
3114 worklist.push(in); // Visit this guy later, using worklist
3115 }
3116 // Get next node from nstack:
3117 // - skip n's inputs processing by setting i > cnt;
3118 // - we also will not call set_early_ctrl(n) since
3119 // has_node(n) == true (see the condition above).
3120 i = cnt + 1;
3121 }
3122 }
3123 } // if (i == 0)
3124
3125 // Visit all inputs
3126 bool done = true; // Assume all n's inputs will be processed
3127 while (i < cnt) {
3128 Node *in = n->in(i);
3129 ++i;
3130 if (in == NULL) continue;
3131 if (in->pinned() && !in->is_CFG())
3132 set_ctrl(in, in->in(0));
3133 int is_visited = visited.test_set( in->_idx );
3134 if (!has_node(in)) { // No controlling input yet?
3135 assert( !in->is_CFG(), "CFG Node with no controlling input?" );
3136 assert( !is_visited, "visit only once" );
3137 nstack.push(n, i); // Save parent node and next input's index.
3138 nstack_top_n = in; // Process current input now.
3139 nstack_top_i = 0;
3140 done = false; // Not all n's inputs processed.
3141 break; // continue while_nstack_nonempty;
3142 } else if (!is_visited) {
3143 // This guy has a location picked out for him, but has not yet
3144 // been visited. Happens to all CFG nodes, for instance.
3145 // Visit him using the worklist instead of recursion, to break
3146 // cycles. Since he has a location already we do not need to
3147 // find his location before proceeding with the current Node.
3148 worklist.push(in); // Visit this guy later, using worklist
3149 }
3150 }
3151 if (done) {
3152 // All of n's inputs have been processed, complete post-processing.
3153
3154 // Compute earliest point this Node can go.
3155 // CFG, Phi, pinned nodes already know their controlling input.
3156 if (!has_node(n)) {
3157 // Record earliest legal location
3158 set_early_ctrl( n );
3159 }
3160 if (nstack.is_empty()) {
3161 // Finished all nodes on stack.
3162 // Process next node on the worklist.
3163 break;
3164 }
3165 // Get saved parent node and next input's index.
3166 nstack_top_n = nstack.node();
3167 nstack_top_i = nstack.index();
3168 nstack.pop();
3169 }
3170 } // while (true)
3171 }
3172 }
3173
3174 //------------------------------dom_lca_internal--------------------------------
3175 // Pair-wise LCA
3176 Node *PhaseIdealLoop::dom_lca_internal( Node *n1, Node *n2 ) const {
3177 if( !n1 ) return n2; // Handle NULL original LCA
3178 assert( n1->is_CFG(), "" );
3179 assert( n2->is_CFG(), "" );
3180 // find LCA of all uses
3181 uint d1 = dom_depth(n1);
3182 uint d2 = dom_depth(n2);
3183 while (n1 != n2) {
3184 if (d1 > d2) {
3185 n1 = idom(n1);
3186 d1 = dom_depth(n1);
3187 } else if (d1 < d2) {
3188 n2 = idom(n2);
3189 d2 = dom_depth(n2);
3190 } else {
3191 // Here d1 == d2. Due to edits of the dominator-tree, sections
3192 // of the tree might have the same depth. These sections have
3193 // to be searched more carefully.
3194
3195 // Scan up all the n1's with equal depth, looking for n2.
3196 Node *t1 = idom(n1);
3197 while (dom_depth(t1) == d1) {
3198 if (t1 == n2) return n2;
3199 t1 = idom(t1);
3200 }
3201 // Scan up all the n2's with equal depth, looking for n1.
3202 Node *t2 = idom(n2);
3203 while (dom_depth(t2) == d2) {
3204 if (t2 == n1) return n1;
3205 t2 = idom(t2);
3206 }
3207 // Move up to a new dominator-depth value as well as up the dom-tree.
3208 n1 = t1;
3209 n2 = t2;
3210 d1 = dom_depth(n1);
3211 d2 = dom_depth(n2);
3212 }
3213 }
3214 return n1;
3215 }
3216
3217 //------------------------------compute_idom-----------------------------------
3218 // Locally compute IDOM using dom_lca call. Correct only if the incoming
3219 // IDOMs are correct.
3220 Node *PhaseIdealLoop::compute_idom( Node *region ) const {
3221 assert( region->is_Region(), "" );
3222 Node *LCA = NULL;
3223 for( uint i = 1; i < region->req(); i++ ) {
3224 if( region->in(i) != C->top() )
3225 LCA = dom_lca( LCA, region->in(i) );
3226 }
3227 return LCA;
3228 }
3229
3230 bool PhaseIdealLoop::verify_dominance(Node* n, Node* use, Node* LCA, Node* early) {
3231 bool had_error = false;
3232 #ifdef ASSERT
3233 if (early != C->root()) {
3234 // Make sure that there's a dominance path from LCA to early
3235 Node* d = LCA;
3236 while (d != early) {
3237 if (d == C->root()) {
3238 dump_bad_graph("Bad graph detected in compute_lca_of_uses", n, early, LCA);
3239 tty->print_cr("*** Use %d isn't dominated by def %d ***", use->_idx, n->_idx);
3240 had_error = true;
3241 break;
3242 }
3243 d = idom(d);
3244 }
3245 }
3246 #endif
3247 return had_error;
3248 }
3249
3250
3251 Node* PhaseIdealLoop::compute_lca_of_uses(Node* n, Node* early, bool verify) {
3252 // Compute LCA over list of uses
3253 bool had_error = false;
3254 Node *LCA = NULL;
3255 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax && LCA != early; i++) {
3256 Node* c = n->fast_out(i);
3257 if (_nodes[c->_idx] == NULL)
3258 continue; // Skip the occasional dead node
3259 if( c->is_Phi() ) { // For Phis, we must land above on the path
3260 for( uint j=1; j<c->req(); j++ ) {// For all inputs
3261 if( c->in(j) == n ) { // Found matching input?
3262 Node *use = c->in(0)->in(j);
3263 if (_verify_only && use->is_top()) continue;
3264 LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
3265 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error;
3266 }
3267 }
3268 } else {
3269 // For CFG data-users, use is in the block just prior
3270 Node *use = has_ctrl(c) ? get_ctrl(c) : c->in(0);
3271 LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
3272 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error;
3273 }
3274 }
3275 assert(!had_error, "bad dominance");
3276 return LCA;
3277 }
3278
3279 //------------------------------get_late_ctrl----------------------------------
3280 // Compute latest legal control.
3281 Node *PhaseIdealLoop::get_late_ctrl( Node *n, Node *early ) {
3282 assert(early != NULL, "early control should not be NULL");
3283
3284 Node* LCA = compute_lca_of_uses(n, early);
3285 #ifdef ASSERT
3286 if (LCA == C->root() && LCA != early) {
3287 // def doesn't dominate uses so print some useful debugging output
3288 compute_lca_of_uses(n, early, true);
3289 }
3290 #endif
3291
3292 // if this is a load, check for anti-dependent stores
3293 // We use a conservative algorithm to identify potential interfering
3294 // instructions and for rescheduling the load. The users of the memory
3295 // input of this load are examined. Any use which is not a load and is
3296 // dominated by early is considered a potentially interfering store.
3297 // This can produce false positives.
3298 if (n->is_Load() && LCA != early) {
3299 Node_List worklist;
3300
3301 Node *mem = n->in(MemNode::Memory);
3302 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
3303 Node* s = mem->fast_out(i);
3304 worklist.push(s);
3305 }
3306 while(worklist.size() != 0 && LCA != early) {
3307 Node* s = worklist.pop();
3308 if (s->is_Load()) {
3309 continue;
3310 } else if (s->is_MergeMem()) {
3311 for (DUIterator_Fast imax, i = s->fast_outs(imax); i < imax; i++) {
3312 Node* s1 = s->fast_out(i);
3313 worklist.push(s1);
3314 }
3315 } else {
3316 Node *sctrl = has_ctrl(s) ? get_ctrl(s) : s->in(0);
3317 assert(sctrl != NULL || s->outcnt() == 0, "must have control");
3318 if (sctrl != NULL && !sctrl->is_top() && is_dominator(early, sctrl)) {
3319 LCA = dom_lca_for_get_late_ctrl(LCA, sctrl, n);
3320 }
3321 }
3322 }
3323 }
3324
3325 assert(LCA == find_non_split_ctrl(LCA), "unexpected late control");
3326 return LCA;
3327 }
3328
3329 // true if CFG node d dominates CFG node n
3330 bool PhaseIdealLoop::is_dominator(Node *d, Node *n) {
3331 if (d == n)
3332 return true;
3333 assert(d->is_CFG() && n->is_CFG(), "must have CFG nodes");
3334 uint dd = dom_depth(d);
3335 while (dom_depth(n) >= dd) {
3336 if (n == d)
3337 return true;
3338 n = idom(n);
3339 }
3340 return false;
3341 }
3342
3343 //------------------------------dom_lca_for_get_late_ctrl_internal-------------
3344 // Pair-wise LCA with tags.
3345 // Tag each index with the node 'tag' currently being processed
3346 // before advancing up the dominator chain using idom().
3347 // Later calls that find a match to 'tag' know that this path has already
3348 // been considered in the current LCA (which is input 'n1' by convention).
3349 // Since get_late_ctrl() is only called once for each node, the tag array
3350 // does not need to be cleared between calls to get_late_ctrl().
3351 // Algorithm trades a larger constant factor for better asymptotic behavior
3352 //
3353 Node *PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal( Node *n1, Node *n2, Node *tag ) {
3354 uint d1 = dom_depth(n1);
3355 uint d2 = dom_depth(n2);
3356
3357 do {
3358 if (d1 > d2) {
3359 // current lca is deeper than n2
3360 _dom_lca_tags.map(n1->_idx, tag);
3361 n1 = idom(n1);
3362 d1 = dom_depth(n1);
3363 } else if (d1 < d2) {
3364 // n2 is deeper than current lca
3365 Node *memo = _dom_lca_tags[n2->_idx];
3366 if( memo == tag ) {
3367 return n1; // Return the current LCA
3368 }
3369 _dom_lca_tags.map(n2->_idx, tag);
3370 n2 = idom(n2);
3371 d2 = dom_depth(n2);
3372 } else {
3373 // Here d1 == d2. Due to edits of the dominator-tree, sections
3374 // of the tree might have the same depth. These sections have
3375 // to be searched more carefully.
3376
3377 // Scan up all the n1's with equal depth, looking for n2.
3378 _dom_lca_tags.map(n1->_idx, tag);
3379 Node *t1 = idom(n1);
3380 while (dom_depth(t1) == d1) {
3381 if (t1 == n2) return n2;
3382 _dom_lca_tags.map(t1->_idx, tag);
3383 t1 = idom(t1);
3384 }
3385 // Scan up all the n2's with equal depth, looking for n1.
3386 _dom_lca_tags.map(n2->_idx, tag);
3387 Node *t2 = idom(n2);
3388 while (dom_depth(t2) == d2) {
3389 if (t2 == n1) return n1;
3390 _dom_lca_tags.map(t2->_idx, tag);
3391 t2 = idom(t2);
3392 }
3393 // Move up to a new dominator-depth value as well as up the dom-tree.
3394 n1 = t1;
3395 n2 = t2;
3396 d1 = dom_depth(n1);
3397 d2 = dom_depth(n2);
3398 }
3399 } while (n1 != n2);
3400 return n1;
3401 }
3402
3403 //------------------------------init_dom_lca_tags------------------------------
3404 // Tag could be a node's integer index, 32bits instead of 64bits in some cases
3405 // Intended use does not involve any growth for the array, so it could
3406 // be of fixed size.
3407 void PhaseIdealLoop::init_dom_lca_tags() {
3408 uint limit = C->unique() + 1;
3409 _dom_lca_tags.map( limit, NULL );
3410 #ifdef ASSERT
3411 for( uint i = 0; i < limit; ++i ) {
3412 assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer");
3413 }
3414 #endif // ASSERT
3415 }
3416
3417 //------------------------------clear_dom_lca_tags------------------------------
3418 // Tag could be a node's integer index, 32bits instead of 64bits in some cases
3419 // Intended use does not involve any growth for the array, so it could
3420 // be of fixed size.
3421 void PhaseIdealLoop::clear_dom_lca_tags() {
3422 uint limit = C->unique() + 1;
3423 _dom_lca_tags.map( limit, NULL );
3424 _dom_lca_tags.clear();
3425 #ifdef ASSERT
3426 for( uint i = 0; i < limit; ++i ) {
3427 assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer");
3428 }
3429 #endif // ASSERT
3430 }
3431
3432 //------------------------------build_loop_late--------------------------------
3433 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
3434 // Second pass finds latest legal placement, and ideal loop placement.
3435 void PhaseIdealLoop::build_loop_late( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) {
3436 while (worklist.size() != 0) {
3437 Node *n = worklist.pop();
3438 // Only visit once
3439 if (visited.test_set(n->_idx)) continue;
3440 uint cnt = n->outcnt();
3441 uint i = 0;
3442 while (true) {
3443 assert( _nodes[n->_idx], "no dead nodes" );
3444 // Visit all children
3445 if (i < cnt) {
3446 Node* use = n->raw_out(i);
3447 ++i;
3448 // Check for dead uses. Aggressively prune such junk. It might be
3449 // dead in the global sense, but still have local uses so I cannot
3450 // easily call 'remove_dead_node'.
3451 if( _nodes[use->_idx] != NULL || use->is_top() ) { // Not dead?
3452 // Due to cycles, we might not hit the same fixed point in the verify
3453 // pass as we do in the regular pass. Instead, visit such phis as
3454 // simple uses of the loop head.
3455 if( use->in(0) && (use->is_CFG() || use->is_Phi()) ) {
3456 if( !visited.test(use->_idx) )
3457 worklist.push(use);
3458 } else if( !visited.test_set(use->_idx) ) {
3459 nstack.push(n, i); // Save parent and next use's index.
3460 n = use; // Process all children of current use.
3461 cnt = use->outcnt();
3462 i = 0;
3463 }
3464 } else {
3465 // Do not visit around the backedge of loops via data edges.
3466 // push dead code onto a worklist
3467 _deadlist.push(use);
3468 }
3469 } else {
3470 // All of n's children have been processed, complete post-processing.
3471 build_loop_late_post(n);
3472 if (nstack.is_empty()) {
3473 // Finished all nodes on stack.
3474 // Process next node on the worklist.
3475 break;
3476 }
3477 // Get saved parent node and next use's index. Visit the rest of uses.
3478 n = nstack.node();
3479 cnt = n->outcnt();
3480 i = nstack.index();
3481 nstack.pop();
3482 }
3483 }
3484 }
3485 }
3486
3487 //------------------------------build_loop_late_post---------------------------
3488 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
3489 // Second pass finds latest legal placement, and ideal loop placement.
3490 void PhaseIdealLoop::build_loop_late_post( Node *n ) {
3491
3492 if (n->req() == 2 && (n->Opcode() == Op_ConvI2L || n->Opcode() == Op_CastII) && !C->major_progress() && !_verify_only) {
3493 _igvn._worklist.push(n); // Maybe we'll normalize it, if no more loops.
3494 }
3495
3496 #ifdef ASSERT
3497 if (_verify_only && !n->is_CFG()) {
3498 // Check def-use domination.
3499 compute_lca_of_uses(n, get_ctrl(n), true /* verify */);
3500 }
3501 #endif
3502
3503 // CFG and pinned nodes already handled
3504 if( n->in(0) ) {
3505 if( n->in(0)->is_top() ) return; // Dead?
3506
3507 // We'd like +VerifyLoopOptimizations to not believe that Mod's/Loads
3508 // _must_ be pinned (they have to observe their control edge of course).
3509 // Unlike Stores (which modify an unallocable resource, the memory
3510 // state), Mods/Loads can float around. So free them up.
3511 bool pinned = true;
3512 switch( n->Opcode() ) {
3513 case Op_DivI:
3514 case Op_DivF:
3515 case Op_DivD:
3516 case Op_ModI:
3517 case Op_ModF:
3518 case Op_ModD:
3519 case Op_LoadB: // Same with Loads; they can sink
3520 case Op_LoadUB: // during loop optimizations.
3521 case Op_LoadUS:
3522 case Op_LoadD:
3523 case Op_LoadF:
3524 case Op_LoadI:
3525 case Op_LoadKlass:
3526 case Op_LoadNKlass:
3527 case Op_LoadL:
3528 case Op_LoadS:
3529 case Op_LoadP:
3530 case Op_LoadN:
3531 case Op_LoadRange:
3532 case Op_LoadD_unaligned:
3533 case Op_LoadL_unaligned:
3534 case Op_StrComp: // Does a bunch of load-like effects
3535 case Op_StrEquals:
3536 case Op_StrIndexOf:
3537 case Op_StrIndexOfChar:
3538 case Op_AryEq:
3539 case Op_HasNegatives:
3540 pinned = false;
3541 }
3542 if( pinned ) {
3543 IdealLoopTree *chosen_loop = get_loop(n->is_CFG() ? n : get_ctrl(n));
3544 if( !chosen_loop->_child ) // Inner loop?
3545 chosen_loop->_body.push(n); // Collect inner loops
3546 return;
3547 }
3548 } else { // No slot zero
3549 if( n->is_CFG() ) { // CFG with no slot 0 is dead
3550 _nodes.map(n->_idx,0); // No block setting, it's globally dead
3551 return;
3552 }
3553 assert(!n->is_CFG() || n->outcnt() == 0, "");
3554 }
3555
3556 // Do I have a "safe range" I can select over?
3557 Node *early = get_ctrl(n);// Early location already computed
3558
3559 // Compute latest point this Node can go
3560 Node *LCA = get_late_ctrl( n, early );
3561 // LCA is NULL due to uses being dead
3562 if( LCA == NULL ) {
3563 #ifdef ASSERT
3564 for (DUIterator i1 = n->outs(); n->has_out(i1); i1++) {
3565 assert( _nodes[n->out(i1)->_idx] == NULL, "all uses must also be dead");
3566 }
3567 #endif
3568 _nodes.map(n->_idx, 0); // This node is useless
3569 _deadlist.push(n);
3570 return;
3571 }
3572 assert(LCA != NULL && !LCA->is_top(), "no dead nodes");
3573
3574 Node *legal = LCA; // Walk 'legal' up the IDOM chain
3575 Node *least = legal; // Best legal position so far
3576 while( early != legal ) { // While not at earliest legal
3577 #ifdef ASSERT
3578 if (legal->is_Start() && !early->is_Root()) {
3579 // Bad graph. Print idom path and fail.
3580 dump_bad_graph("Bad graph detected in build_loop_late", n, early, LCA);
3581 assert(false, "Bad graph detected in build_loop_late");
3582 }
3583 #endif
3584 // Find least loop nesting depth
3585 legal = idom(legal); // Bump up the IDOM tree
3586 // Check for lower nesting depth
3587 if( get_loop(legal)->_nest < get_loop(least)->_nest )
3588 least = legal;
3589 }
3590 assert(early == legal || legal != C->root(), "bad dominance of inputs");
3591
3592 // Try not to place code on a loop entry projection
3593 // which can inhibit range check elimination.
3594 if (least != early) {
3595 Node* ctrl_out = least->unique_ctrl_out();
3596 if (ctrl_out && ctrl_out->is_CountedLoop() &&
3597 least == ctrl_out->in(LoopNode::EntryControl)) {
3598 Node* least_dom = idom(least);
3599 if (get_loop(least_dom)->is_member(get_loop(least))) {
3600 least = least_dom;
3601 }
3602 }
3603 }
3604
3605 #ifdef ASSERT
3606 // If verifying, verify that 'verify_me' has a legal location
3607 // and choose it as our location.
3608 if( _verify_me ) {
3609 Node *v_ctrl = _verify_me->get_ctrl_no_update(n);
3610 Node *legal = LCA;
3611 while( early != legal ) { // While not at earliest legal
3612 if( legal == v_ctrl ) break; // Check for prior good location
3613 legal = idom(legal) ;// Bump up the IDOM tree
3614 }
3615 // Check for prior good location
3616 if( legal == v_ctrl ) least = legal; // Keep prior if found
3617 }
3618 #endif
3619
3620 // Assign discovered "here or above" point
3621 least = find_non_split_ctrl(least);
3622 set_ctrl(n, least);
3623
3624 // Collect inner loop bodies
3625 IdealLoopTree *chosen_loop = get_loop(least);
3626 if( !chosen_loop->_child ) // Inner loop?
3627 chosen_loop->_body.push(n);// Collect inner loops
3628 }
3629
3630 #ifdef ASSERT
3631 void PhaseIdealLoop::dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA) {
3632 tty->print_cr("%s", msg);
3633 tty->print("n: "); n->dump();
3634 tty->print("early(n): "); early->dump();
3635 if (n->in(0) != NULL && !n->in(0)->is_top() &&
3636 n->in(0) != early && !n->in(0)->is_Root()) {
3637 tty->print("n->in(0): "); n->in(0)->dump();
3638 }
3639 for (uint i = 1; i < n->req(); i++) {
3640 Node* in1 = n->in(i);
3641 if (in1 != NULL && in1 != n && !in1->is_top()) {
3642 tty->print("n->in(%d): ", i); in1->dump();
3643 Node* in1_early = get_ctrl(in1);
3644 tty->print("early(n->in(%d)): ", i); in1_early->dump();
3645 if (in1->in(0) != NULL && !in1->in(0)->is_top() &&
3646 in1->in(0) != in1_early && !in1->in(0)->is_Root()) {
3647 tty->print("n->in(%d)->in(0): ", i); in1->in(0)->dump();
3648 }
3649 for (uint j = 1; j < in1->req(); j++) {
3650 Node* in2 = in1->in(j);
3651 if (in2 != NULL && in2 != n && in2 != in1 && !in2->is_top()) {
3652 tty->print("n->in(%d)->in(%d): ", i, j); in2->dump();
3653 Node* in2_early = get_ctrl(in2);
3654 tty->print("early(n->in(%d)->in(%d)): ", i, j); in2_early->dump();
3655 if (in2->in(0) != NULL && !in2->in(0)->is_top() &&
3656 in2->in(0) != in2_early && !in2->in(0)->is_Root()) {
3657 tty->print("n->in(%d)->in(%d)->in(0): ", i, j); in2->in(0)->dump();
3658 }
3659 }
3660 }
3661 }
3662 }
3663 tty->cr();
3664 tty->print("LCA(n): "); LCA->dump();
3665 for (uint i = 0; i < n->outcnt(); i++) {
3666 Node* u1 = n->raw_out(i);
3667 if (u1 == n)
3668 continue;
3669 tty->print("n->out(%d): ", i); u1->dump();
3670 if (u1->is_CFG()) {
3671 for (uint j = 0; j < u1->outcnt(); j++) {
3672 Node* u2 = u1->raw_out(j);
3673 if (u2 != u1 && u2 != n && u2->is_CFG()) {
3674 tty->print("n->out(%d)->out(%d): ", i, j); u2->dump();
3675 }
3676 }
3677 } else {
3678 Node* u1_later = get_ctrl(u1);
3679 tty->print("later(n->out(%d)): ", i); u1_later->dump();
3680 if (u1->in(0) != NULL && !u1->in(0)->is_top() &&
3681 u1->in(0) != u1_later && !u1->in(0)->is_Root()) {
3682 tty->print("n->out(%d)->in(0): ", i); u1->in(0)->dump();
3683 }
3684 for (uint j = 0; j < u1->outcnt(); j++) {
3685 Node* u2 = u1->raw_out(j);
3686 if (u2 == n || u2 == u1)
3687 continue;
3688 tty->print("n->out(%d)->out(%d): ", i, j); u2->dump();
3689 if (!u2->is_CFG()) {
3690 Node* u2_later = get_ctrl(u2);
3691 tty->print("later(n->out(%d)->out(%d)): ", i, j); u2_later->dump();
3692 if (u2->in(0) != NULL && !u2->in(0)->is_top() &&
3693 u2->in(0) != u2_later && !u2->in(0)->is_Root()) {
3694 tty->print("n->out(%d)->in(0): ", i); u2->in(0)->dump();
3695 }
3696 }
3697 }
3698 }
3699 }
3700 tty->cr();
3701 int ct = 0;
3702 Node *dbg_legal = LCA;
3703 while(!dbg_legal->is_Start() && ct < 100) {
3704 tty->print("idom[%d] ",ct); dbg_legal->dump();
3705 ct++;
3706 dbg_legal = idom(dbg_legal);
3707 }
3708 tty->cr();
3709 }
3710 #endif
3711
3712 #ifndef PRODUCT
3713 //------------------------------dump-------------------------------------------
3714 void PhaseIdealLoop::dump( ) const {
3715 ResourceMark rm;
3716 Arena* arena = Thread::current()->resource_area();
3717 Node_Stack stack(arena, C->live_nodes() >> 2);
3718 Node_List rpo_list;
3719 VectorSet visited(arena);
3720 visited.set(C->top()->_idx);
3721 rpo( C->root(), stack, visited, rpo_list );
3722 // Dump root loop indexed by last element in PO order
3723 dump( _ltree_root, rpo_list.size(), rpo_list );
3724 }
3725
3726 void PhaseIdealLoop::dump( IdealLoopTree *loop, uint idx, Node_List &rpo_list ) const {
3727 loop->dump_head();
3728
3729 // Now scan for CFG nodes in the same loop
3730 for( uint j=idx; j > 0; j-- ) {
3731 Node *n = rpo_list[j-1];
3732 if( !_nodes[n->_idx] ) // Skip dead nodes
3733 continue;
3734 if( get_loop(n) != loop ) { // Wrong loop nest
3735 if( get_loop(n)->_head == n && // Found nested loop?
3736 get_loop(n)->_parent == loop )
3737 dump(get_loop(n),rpo_list.size(),rpo_list); // Print it nested-ly
3738 continue;
3739 }
3740
3741 // Dump controlling node
3742 for( uint x = 0; x < loop->_nest; x++ )
3743 tty->print(" ");
3744 tty->print("C");
3745 if( n == C->root() ) {
3746 n->dump();
3747 } else {
3748 Node* cached_idom = idom_no_update(n);
3749 Node *computed_idom = n->in(0);
3750 if( n->is_Region() ) {
3751 computed_idom = compute_idom(n);
3752 // computed_idom() will return n->in(0) when idom(n) is an IfNode (or
3753 // any MultiBranch ctrl node), so apply a similar transform to
3754 // the cached idom returned from idom_no_update.
3755 cached_idom = find_non_split_ctrl(cached_idom);
3756 }
3757 tty->print(" ID:%d",computed_idom->_idx);
3758 n->dump();
3759 if( cached_idom != computed_idom ) {
3760 tty->print_cr("*** BROKEN IDOM! Computed as: %d, cached as: %d",
3761 computed_idom->_idx, cached_idom->_idx);
3762 }
3763 }
3764 // Dump nodes it controls
3765 for( uint k = 0; k < _nodes.Size(); k++ ) {
3766 // (k < C->unique() && get_ctrl(find(k)) == n)
3767 if (k < C->unique() && _nodes[k] == (Node*)((intptr_t)n + 1)) {
3768 Node *m = C->root()->find(k);
3769 if( m && m->outcnt() > 0 ) {
3770 if (!(has_ctrl(m) && get_ctrl_no_update(m) == n)) {
3771 tty->print_cr("*** BROKEN CTRL ACCESSOR! _nodes[k] is %p, ctrl is %p",
3772 _nodes[k], has_ctrl(m) ? get_ctrl_no_update(m) : NULL);
3773 }
3774 for( uint j = 0; j < loop->_nest; j++ )
3775 tty->print(" ");
3776 tty->print(" ");
3777 m->dump();
3778 }
3779 }
3780 }
3781 }
3782 }
3783
3784 // Collect a R-P-O for the whole CFG.
3785 // Result list is in post-order (scan backwards for RPO)
3786 void PhaseIdealLoop::rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const {
3787 stk.push(start, 0);
3788 visited.set(start->_idx);
3789
3790 while (stk.is_nonempty()) {
3791 Node* m = stk.node();
3792 uint idx = stk.index();
3793 if (idx < m->outcnt()) {
3794 stk.set_index(idx + 1);
3795 Node* n = m->raw_out(idx);
3796 if (n->is_CFG() && !visited.test_set(n->_idx)) {
3797 stk.push(n, 0);
3798 }
3799 } else {
3800 rpo_list.push(m);
3801 stk.pop();
3802 }
3803 }
3804 }
3805 #endif
3806
3807
3808 //=============================================================================
3809 //------------------------------LoopTreeIterator-----------------------------------
3810
3811 // Advance to next loop tree using a preorder, left-to-right traversal.
3812 void LoopTreeIterator::next() {
3813 assert(!done(), "must not be done.");
3814 if (_curnt->_child != NULL) {
3815 _curnt = _curnt->_child;
3816 } else if (_curnt->_next != NULL) {
3817 _curnt = _curnt->_next;
3818 } else {
3819 while (_curnt != _root && _curnt->_next == NULL) {
3820 _curnt = _curnt->_parent;
3821 }
3822 if (_curnt == _root) {
3823 _curnt = NULL;
3824 assert(done(), "must be done.");
3825 } else {
3826 assert(_curnt->_next != NULL, "must be more to do");
3827 _curnt = _curnt->_next;
3828 }
3829 }
3830 }