1 /*
2 * Copyright (c) 1998, 2019, 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 "gc/shared/barrierSet.hpp"
29 #include "gc/shared/c2/barrierSetC2.hpp"
30 #include "libadt/vectset.hpp"
31 #include "memory/allocation.inline.hpp"
32 #include "memory/resourceArea.hpp"
33 #include "opto/addnode.hpp"
34 #include "opto/callnode.hpp"
35 #include "opto/connode.hpp"
36 #include "opto/convertnode.hpp"
37 #include "opto/divnode.hpp"
38 #include "opto/idealGraphPrinter.hpp"
39 #include "opto/loopnode.hpp"
40 #include "opto/mulnode.hpp"
41 #include "opto/rootnode.hpp"
42 #include "opto/superword.hpp"
43
44 //=============================================================================
45 //--------------------------is_cloop_ind_var-----------------------------------
46 // Determine if a node is a counted loop induction variable.
47 // NOTE: The method is declared in "node.hpp".
48 bool Node::is_cloop_ind_var() const {
49 return (is_Phi() && !as_Phi()->is_copy() &&
50 as_Phi()->region()->is_CountedLoop() &&
51 as_Phi()->region()->as_CountedLoop()->phi() == this);
52 }
53
54 //=============================================================================
55 //------------------------------dump_spec--------------------------------------
56 // Dump special per-node info
57 #ifndef PRODUCT
58 void LoopNode::dump_spec(outputStream *st) const {
59 if (is_inner_loop()) st->print( "inner " );
60 if (is_partial_peel_loop()) st->print( "partial_peel " );
61 if (partial_peel_has_failed()) st->print( "partial_peel_failed " );
62 }
63 #endif
64
65 //------------------------------is_valid_counted_loop-------------------------
66 bool LoopNode::is_valid_counted_loop() const {
67 if (is_CountedLoop()) {
68 CountedLoopNode* l = as_CountedLoop();
69 CountedLoopEndNode* le = l->loopexit_or_null();
70 if (le != NULL &&
71 le->proj_out_or_null(1 /* true */) == l->in(LoopNode::LoopBackControl)) {
72 Node* phi = l->phi();
73 Node* exit = le->proj_out_or_null(0 /* false */);
74 if (exit != NULL && exit->Opcode() == Op_IfFalse &&
75 phi != NULL && phi->is_Phi() &&
76 phi->in(LoopNode::LoopBackControl) == l->incr() &&
77 le->loopnode() == l && le->stride_is_con()) {
78 return true;
79 }
80 }
81 }
82 return false;
83 }
84
85 //------------------------------get_early_ctrl---------------------------------
86 // Compute earliest legal control
87 Node *PhaseIdealLoop::get_early_ctrl( Node *n ) {
88 assert( !n->is_Phi() && !n->is_CFG(), "this code only handles data nodes" );
89 uint i;
90 Node *early;
91 if (n->in(0) && !n->is_expensive()) {
92 early = n->in(0);
93 if (!early->is_CFG()) // Might be a non-CFG multi-def
94 early = get_ctrl(early); // So treat input as a straight data input
95 i = 1;
96 } else {
97 early = get_ctrl(n->in(1));
98 i = 2;
99 }
100 uint e_d = dom_depth(early);
101 assert( early, "" );
102 for (; i < n->req(); i++) {
103 Node *cin = get_ctrl(n->in(i));
104 assert( cin, "" );
105 // Keep deepest dominator depth
106 uint c_d = dom_depth(cin);
107 if (c_d > e_d) { // Deeper guy?
108 early = cin; // Keep deepest found so far
109 e_d = c_d;
110 } else if (c_d == e_d && // Same depth?
111 early != cin) { // If not equal, must use slower algorithm
112 // If same depth but not equal, one _must_ dominate the other
113 // and we want the deeper (i.e., dominated) guy.
114 Node *n1 = early;
115 Node *n2 = cin;
116 while (1) {
117 n1 = idom(n1); // Walk up until break cycle
118 n2 = idom(n2);
119 if (n1 == cin || // Walked early up to cin
120 dom_depth(n2) < c_d)
121 break; // early is deeper; keep him
122 if (n2 == early || // Walked cin up to early
123 dom_depth(n1) < c_d) {
124 early = cin; // cin is deeper; keep him
125 break;
126 }
127 }
128 e_d = dom_depth(early); // Reset depth register cache
129 }
130 }
131
132 // Return earliest legal location
133 assert(early == find_non_split_ctrl(early), "unexpected early control");
134
135 if (n->is_expensive() && !_verify_only && !_verify_me) {
136 assert(n->in(0), "should have control input");
137 early = get_early_ctrl_for_expensive(n, early);
138 }
139
140 return early;
141 }
142
143 //------------------------------get_early_ctrl_for_expensive---------------------------------
144 // Move node up the dominator tree as high as legal while still beneficial
145 Node *PhaseIdealLoop::get_early_ctrl_for_expensive(Node *n, Node* earliest) {
146 assert(n->in(0) && n->is_expensive(), "expensive node with control input here");
147 assert(OptimizeExpensiveOps, "optimization off?");
148
149 Node* ctl = n->in(0);
150 assert(ctl->is_CFG(), "expensive input 0 must be cfg");
151 uint min_dom_depth = dom_depth(earliest);
152 #ifdef ASSERT
153 if (!is_dominator(ctl, earliest) && !is_dominator(earliest, ctl)) {
154 dump_bad_graph("Bad graph detected in get_early_ctrl_for_expensive", n, earliest, ctl);
155 assert(false, "Bad graph detected in get_early_ctrl_for_expensive");
156 }
157 #endif
158 if (dom_depth(ctl) < min_dom_depth) {
159 return earliest;
160 }
161
162 while (1) {
163 Node *next = ctl;
164 // Moving the node out of a loop on the projection of a If
165 // confuses loop predication. So once we hit a Loop in a If branch
166 // that doesn't branch to an UNC, we stop. The code that process
167 // expensive nodes will notice the loop and skip over it to try to
168 // move the node further up.
169 if (ctl->is_CountedLoop() && ctl->in(1) != NULL && ctl->in(1)->in(0) != NULL && ctl->in(1)->in(0)->is_If()) {
170 if (!ctl->in(1)->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) {
171 break;
172 }
173 next = idom(ctl->in(1)->in(0));
174 } else if (ctl->is_Proj()) {
175 // We only move it up along a projection if the projection is
176 // the single control projection for its parent: same code path,
177 // if it's a If with UNC or fallthrough of a call.
178 Node* parent_ctl = ctl->in(0);
179 if (parent_ctl == NULL) {
180 break;
181 } else if (parent_ctl->is_CountedLoopEnd() && parent_ctl->as_CountedLoopEnd()->loopnode() != NULL) {
182 next = parent_ctl->as_CountedLoopEnd()->loopnode()->init_control();
183 } else if (parent_ctl->is_If()) {
184 if (!ctl->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) {
185 break;
186 }
187 assert(idom(ctl) == parent_ctl, "strange");
188 next = idom(parent_ctl);
189 } else if (ctl->is_CatchProj()) {
190 if (ctl->as_Proj()->_con != CatchProjNode::fall_through_index) {
191 break;
192 }
193 assert(parent_ctl->in(0)->in(0)->is_Call(), "strange graph");
194 next = parent_ctl->in(0)->in(0)->in(0);
195 } else {
196 // Check if parent control has a single projection (this
197 // control is the only possible successor of the parent
198 // control). If so, we can try to move the node above the
199 // parent control.
200 int nb_ctl_proj = 0;
201 for (DUIterator_Fast imax, i = parent_ctl->fast_outs(imax); i < imax; i++) {
202 Node *p = parent_ctl->fast_out(i);
203 if (p->is_Proj() && p->is_CFG()) {
204 nb_ctl_proj++;
205 if (nb_ctl_proj > 1) {
206 break;
207 }
208 }
209 }
210
211 if (nb_ctl_proj > 1) {
212 break;
213 }
214 assert(parent_ctl->is_Start() || parent_ctl->is_MemBar() || parent_ctl->is_Call() ||
215 BarrierSet::barrier_set()->barrier_set_c2()->is_gc_barrier_node(parent_ctl), "unexpected node");
216 assert(idom(ctl) == parent_ctl, "strange");
217 next = idom(parent_ctl);
218 }
219 } else {
220 next = idom(ctl);
221 }
222 if (next->is_Root() || next->is_Start() || dom_depth(next) < min_dom_depth) {
223 break;
224 }
225 ctl = next;
226 }
227
228 if (ctl != n->in(0)) {
229 _igvn.replace_input_of(n, 0, ctl);
230 _igvn.hash_insert(n);
231 }
232
233 return ctl;
234 }
235
236
237 //------------------------------set_early_ctrl---------------------------------
238 // Set earliest legal control
239 void PhaseIdealLoop::set_early_ctrl( Node *n ) {
240 Node *early = get_early_ctrl(n);
241
242 // Record earliest legal location
243 set_ctrl(n, early);
244 }
245
246 //------------------------------set_subtree_ctrl-------------------------------
247 // set missing _ctrl entries on new nodes
248 void PhaseIdealLoop::set_subtree_ctrl( Node *n ) {
249 // Already set? Get out.
250 if( _nodes[n->_idx] ) return;
251 // Recursively set _nodes array to indicate where the Node goes
252 uint i;
253 for( i = 0; i < n->req(); ++i ) {
254 Node *m = n->in(i);
255 if( m && m != C->root() )
256 set_subtree_ctrl( m );
257 }
258
259 // Fixup self
260 set_early_ctrl( n );
261 }
262
263 // Create a skeleton strip mined outer loop: a Loop head before the
264 // inner strip mined loop, a safepoint and an exit condition guarded
265 // by an opaque node after the inner strip mined loop with a backedge
266 // to the loop head. The inner strip mined loop is left as it is. Only
267 // once loop optimizations are over, do we adjust the inner loop exit
268 // condition to limit its number of iterations, set the outer loop
269 // exit condition and add Phis to the outer loop head. Some loop
270 // optimizations that operate on the inner strip mined loop need to be
271 // aware of the outer strip mined loop: loop unswitching needs to
272 // clone the outer loop as well as the inner, unrolling needs to only
273 // clone the inner loop etc. No optimizations need to change the outer
274 // strip mined loop as it is only a skeleton.
275 IdealLoopTree* PhaseIdealLoop::create_outer_strip_mined_loop(BoolNode *test, Node *cmp, Node *init_control,
276 IdealLoopTree* loop, float cl_prob, float le_fcnt,
277 Node*& entry_control, Node*& iffalse) {
278 Node* outer_test = _igvn.intcon(0);
279 set_ctrl(outer_test, C->root());
280 Node *orig = iffalse;
281 iffalse = iffalse->clone();
282 _igvn.register_new_node_with_optimizer(iffalse);
283 set_idom(iffalse, idom(orig), dom_depth(orig));
284
285 IfNode *outer_le = new OuterStripMinedLoopEndNode(iffalse, outer_test, cl_prob, le_fcnt);
286 Node *outer_ift = new IfTrueNode (outer_le);
287 Node* outer_iff = orig;
288 _igvn.replace_input_of(outer_iff, 0, outer_le);
289
290 LoopNode *outer_l = new OuterStripMinedLoopNode(C, init_control, outer_ift);
291 entry_control = outer_l;
292
293 IdealLoopTree* outer_ilt = new IdealLoopTree(this, outer_l, outer_ift);
294 IdealLoopTree* parent = loop->_parent;
295 IdealLoopTree* sibling = parent->_child;
296 if (sibling == loop) {
297 parent->_child = outer_ilt;
298 } else {
299 while (sibling->_next != loop) {
300 sibling = sibling->_next;
301 }
302 sibling->_next = outer_ilt;
303 }
304 outer_ilt->_next = loop->_next;
305 outer_ilt->_parent = parent;
306 outer_ilt->_child = loop;
307 outer_ilt->_nest = loop->_nest;
308 loop->_parent = outer_ilt;
309 loop->_next = NULL;
310 loop->_nest++;
311
312 set_loop(iffalse, outer_ilt);
313 register_control(outer_le, outer_ilt, iffalse);
314 register_control(outer_ift, outer_ilt, outer_le);
315 set_idom(outer_iff, outer_le, dom_depth(outer_le));
316 _igvn.register_new_node_with_optimizer(outer_l);
317 set_loop(outer_l, outer_ilt);
318 set_idom(outer_l, init_control, dom_depth(init_control)+1);
319
320 return outer_ilt;
321 }
322
323 void PhaseIdealLoop::insert_loop_limit_check(ProjNode* limit_check_proj, Node* cmp_limit, Node* bol) {
324 Node* new_predicate_proj = create_new_if_for_predicate(limit_check_proj, NULL,
325 Deoptimization::Reason_loop_limit_check,
326 Op_If);
327 Node* iff = new_predicate_proj->in(0);
328 assert(iff->Opcode() == Op_If, "bad graph shape");
329 Node* conv = iff->in(1);
330 assert(conv->Opcode() == Op_Conv2B, "bad graph shape");
331 Node* opaq = conv->in(1);
332 assert(opaq->Opcode() == Op_Opaque1, "bad graph shape");
333 cmp_limit = _igvn.register_new_node_with_optimizer(cmp_limit);
334 bol = _igvn.register_new_node_with_optimizer(bol);
335 set_subtree_ctrl(bol);
336 _igvn.replace_input_of(iff, 1, bol);
337
338 #ifndef PRODUCT
339 // report that the loop predication has been actually performed
340 // for this loop
341 if (TraceLoopLimitCheck) {
342 tty->print_cr("Counted Loop Limit Check generated:");
343 debug_only( bol->dump(2); )
344 }
345 #endif
346 }
347
348 //------------------------------is_counted_loop--------------------------------
349 bool PhaseIdealLoop::is_counted_loop(Node* x, IdealLoopTree*& loop) {
350 PhaseGVN *gvn = &_igvn;
351
352 // Counted loop head must be a good RegionNode with only 3 not NULL
353 // control input edges: Self, Entry, LoopBack.
354 if (x->in(LoopNode::Self) == NULL || x->req() != 3 || loop->_irreducible) {
355 return false;
356 }
357 Node *init_control = x->in(LoopNode::EntryControl);
358 Node *back_control = x->in(LoopNode::LoopBackControl);
359 if (init_control == NULL || back_control == NULL) // Partially dead
360 return false;
361 // Must also check for TOP when looking for a dead loop
362 if (init_control->is_top() || back_control->is_top())
363 return false;
364
365 // Allow funny placement of Safepoint
366 if (back_control->Opcode() == Op_SafePoint) {
367 if (LoopStripMiningIter != 0) {
368 // Leaving the safepoint on the backedge and creating a
369 // CountedLoop will confuse optimizations. We can't move the
370 // safepoint around because its jvm state wouldn't match a new
371 // location. Give up on that loop.
372 return false;
373 }
374 back_control = back_control->in(TypeFunc::Control);
375 }
376
377 // Controlling test for loop
378 Node *iftrue = back_control;
379 uint iftrue_op = iftrue->Opcode();
380 if (iftrue_op != Op_IfTrue &&
381 iftrue_op != Op_IfFalse)
382 // I have a weird back-control. Probably the loop-exit test is in
383 // the middle of the loop and I am looking at some trailing control-flow
384 // merge point. To fix this I would have to partially peel the loop.
385 return false; // Obscure back-control
386
387 // Get boolean guarding loop-back test
388 Node *iff = iftrue->in(0);
389 if (get_loop(iff) != loop || !iff->in(1)->is_Bool())
390 return false;
391 BoolNode *test = iff->in(1)->as_Bool();
392 BoolTest::mask bt = test->_test._test;
393 float cl_prob = iff->as_If()->_prob;
394 if (iftrue_op == Op_IfFalse) {
395 bt = BoolTest(bt).negate();
396 cl_prob = 1.0 - cl_prob;
397 }
398 // Get backedge compare
399 Node *cmp = test->in(1);
400 int cmp_op = cmp->Opcode();
401 if (cmp_op != Op_CmpI)
402 return false; // Avoid pointer & float compares
403
404 // Find the trip-counter increment & limit. Limit must be loop invariant.
405 Node *incr = cmp->in(1);
406 Node *limit = cmp->in(2);
407
408 // ---------
409 // need 'loop()' test to tell if limit is loop invariant
410 // ---------
411
412 if (!is_member(loop, get_ctrl(incr))) { // Swapped trip counter and limit?
413 Node *tmp = incr; // Then reverse order into the CmpI
414 incr = limit;
415 limit = tmp;
416 bt = BoolTest(bt).commute(); // And commute the exit test
417 }
418 if (is_member(loop, get_ctrl(limit))) // Limit must be loop-invariant
419 return false;
420 if (!is_member(loop, get_ctrl(incr))) // Trip counter must be loop-variant
421 return false;
422
423 Node* phi_incr = NULL;
424 // Trip-counter increment must be commutative & associative.
425 if (incr->Opcode() == Op_CastII) {
426 incr = incr->in(1);
427 }
428 if (incr->is_Phi()) {
429 if (incr->as_Phi()->region() != x || incr->req() != 3)
430 return false; // Not simple trip counter expression
431 phi_incr = incr;
432 incr = phi_incr->in(LoopNode::LoopBackControl); // Assume incr is on backedge of Phi
433 if (!is_member(loop, get_ctrl(incr))) // Trip counter must be loop-variant
434 return false;
435 }
436
437 Node* trunc1 = NULL;
438 Node* trunc2 = NULL;
439 const TypeInt* iv_trunc_t = NULL;
440 Node* orig_incr = incr;
441 if (!(incr = CountedLoopNode::match_incr_with_optional_truncation(incr, &trunc1, &trunc2, &iv_trunc_t))) {
442 return false; // Funny increment opcode
443 }
444 assert(incr->Opcode() == Op_AddI, "wrong increment code");
445
446 const TypeInt* limit_t = gvn->type(limit)->is_int();
447 if (trunc1 != NULL) {
448 // When there is a truncation, we must be sure that after the truncation
449 // the trip counter will end up higher than the limit, otherwise we are looking
450 // at an endless loop. Can happen with range checks.
451
452 // Example:
453 // int i = 0;
454 // while (true)
455 // sum + = array[i];
456 // i++;
457 // i = i && 0x7fff;
458 // }
459 //
460 // If the array is shorter than 0x8000 this exits through a AIOOB
461 // - Counted loop transformation is ok
462 // If the array is longer then this is an endless loop
463 // - No transformation can be done.
464
465 const TypeInt* incr_t = gvn->type(orig_incr)->is_int();
466 if (limit_t->_hi > incr_t->_hi) {
467 // if the limit can have a higher value than the increment (before the phi)
468 return false;
469 }
470 }
471
472 // Get merge point
473 Node *xphi = incr->in(1);
474 Node *stride = incr->in(2);
475 if (!stride->is_Con()) { // Oops, swap these
476 if (!xphi->is_Con()) // Is the other guy a constant?
477 return false; // Nope, unknown stride, bail out
478 Node *tmp = xphi; // 'incr' is commutative, so ok to swap
479 xphi = stride;
480 stride = tmp;
481 }
482 if (xphi->Opcode() == Op_CastII) {
483 xphi = xphi->in(1);
484 }
485 // Stride must be constant
486 int stride_con = stride->get_int();
487 if (stride_con == 0)
488 return false; // missed some peephole opt
489
490 if (!xphi->is_Phi())
491 return false; // Too much math on the trip counter
492 if (phi_incr != NULL && phi_incr != xphi)
493 return false;
494 PhiNode *phi = xphi->as_Phi();
495
496 // Phi must be of loop header; backedge must wrap to increment
497 if (phi->region() != x)
498 return false;
499 if ((trunc1 == NULL && phi->in(LoopNode::LoopBackControl) != incr) ||
500 (trunc1 != NULL && phi->in(LoopNode::LoopBackControl) != trunc1)) {
501 return false;
502 }
503 Node *init_trip = phi->in(LoopNode::EntryControl);
504
505 // If iv trunc type is smaller than int, check for possible wrap.
506 if (!TypeInt::INT->higher_equal(iv_trunc_t)) {
507 assert(trunc1 != NULL, "must have found some truncation");
508
509 // Get a better type for the phi (filtered thru if's)
510 const TypeInt* phi_ft = filtered_type(phi);
511
512 // Can iv take on a value that will wrap?
513 //
514 // Ensure iv's limit is not within "stride" of the wrap value.
515 //
516 // Example for "short" type
517 // Truncation ensures value is in the range -32768..32767 (iv_trunc_t)
518 // If the stride is +10, then the last value of the induction
519 // variable before the increment (phi_ft->_hi) must be
520 // <= 32767 - 10 and (phi_ft->_lo) must be >= -32768 to
521 // ensure no truncation occurs after the increment.
522
523 if (stride_con > 0) {
524 if (iv_trunc_t->_hi - phi_ft->_hi < stride_con ||
525 iv_trunc_t->_lo > phi_ft->_lo) {
526 return false; // truncation may occur
527 }
528 } else if (stride_con < 0) {
529 if (iv_trunc_t->_lo - phi_ft->_lo > stride_con ||
530 iv_trunc_t->_hi < phi_ft->_hi) {
531 return false; // truncation may occur
532 }
533 }
534 // No possibility of wrap so truncation can be discarded
535 // Promote iv type to Int
536 } else {
537 assert(trunc1 == NULL && trunc2 == NULL, "no truncation for int");
538 }
539
540 // If the condition is inverted and we will be rolling
541 // through MININT to MAXINT, then bail out.
542 if (bt == BoolTest::eq || // Bail out, but this loop trips at most twice!
543 // Odd stride
544 (bt == BoolTest::ne && stride_con != 1 && stride_con != -1) ||
545 // Count down loop rolls through MAXINT
546 ((bt == BoolTest::le || bt == BoolTest::lt) && stride_con < 0) ||
547 // Count up loop rolls through MININT
548 ((bt == BoolTest::ge || bt == BoolTest::gt) && stride_con > 0)) {
549 return false; // Bail out
550 }
551
552 const TypeInt* init_t = gvn->type(init_trip)->is_int();
553
554 if (stride_con > 0) {
555 jlong init_p = (jlong)init_t->_lo + stride_con;
556 if (init_p > (jlong)max_jint || init_p > (jlong)limit_t->_hi)
557 return false; // cyclic loop or this loop trips only once
558 } else {
559 jlong init_p = (jlong)init_t->_hi + stride_con;
560 if (init_p < (jlong)min_jint || init_p < (jlong)limit_t->_lo)
561 return false; // cyclic loop or this loop trips only once
562 }
563
564 if (phi_incr != NULL && bt != BoolTest::ne) {
565 // check if there is a possiblity of IV overflowing after the first increment
566 if (stride_con > 0) {
567 if (init_t->_hi > max_jint - stride_con) {
568 return false;
569 }
570 } else {
571 if (init_t->_lo < min_jint - stride_con) {
572 return false;
573 }
574 }
575 }
576
577 // =================================================
578 // ---- SUCCESS! Found A Trip-Counted Loop! -----
579 //
580 assert(x->Opcode() == Op_Loop, "regular loops only");
581 C->print_method(PHASE_BEFORE_CLOOPS, 3);
582
583 Node *hook = new Node(6);
584
585 // ===================================================
586 // Generate loop limit check to avoid integer overflow
587 // in cases like next (cyclic loops):
588 //
589 // for (i=0; i <= max_jint; i++) {}
590 // for (i=0; i < max_jint; i+=2) {}
591 //
592 //
593 // Limit check predicate depends on the loop test:
594 //
595 // for(;i != limit; i++) --> limit <= (max_jint)
596 // for(;i < limit; i+=stride) --> limit <= (max_jint - stride + 1)
597 // for(;i <= limit; i+=stride) --> limit <= (max_jint - stride )
598 //
599
600 // Check if limit is excluded to do more precise int overflow check.
601 bool incl_limit = (bt == BoolTest::le || bt == BoolTest::ge);
602 int stride_m = stride_con - (incl_limit ? 0 : (stride_con > 0 ? 1 : -1));
603
604 // If compare points directly to the phi we need to adjust
605 // the compare so that it points to the incr. Limit have
606 // to be adjusted to keep trip count the same and the
607 // adjusted limit should be checked for int overflow.
608 if (phi_incr != NULL) {
609 stride_m += stride_con;
610 }
611
612 if (limit->is_Con()) {
613 int limit_con = limit->get_int();
614 if ((stride_con > 0 && limit_con > (max_jint - stride_m)) ||
615 (stride_con < 0 && limit_con < (min_jint - stride_m))) {
616 // Bailout: it could be integer overflow.
617 return false;
618 }
619 } else if ((stride_con > 0 && limit_t->_hi <= (max_jint - stride_m)) ||
620 (stride_con < 0 && limit_t->_lo >= (min_jint - stride_m))) {
621 // Limit's type may satisfy the condition, for example,
622 // when it is an array length.
623 } else {
624 // Generate loop's limit check.
625 // Loop limit check predicate should be near the loop.
626 ProjNode *limit_check_proj = find_predicate_insertion_point(init_control, Deoptimization::Reason_loop_limit_check);
627 if (!limit_check_proj) {
628 // The limit check predicate is not generated if this method trapped here before.
629 #ifdef ASSERT
630 if (TraceLoopLimitCheck) {
631 tty->print("missing loop limit check:");
632 loop->dump_head();
633 x->dump(1);
634 }
635 #endif
636 return false;
637 }
638
639 IfNode* check_iff = limit_check_proj->in(0)->as_If();
640
641 if (!is_dominator(get_ctrl(limit), check_iff->in(0))) {
642 return false;
643 }
644
645 Node* cmp_limit;
646 Node* bol;
647
648 if (stride_con > 0) {
649 cmp_limit = new CmpINode(limit, _igvn.intcon(max_jint - stride_m));
650 bol = new BoolNode(cmp_limit, BoolTest::le);
651 } else {
652 cmp_limit = new CmpINode(limit, _igvn.intcon(min_jint - stride_m));
653 bol = new BoolNode(cmp_limit, BoolTest::ge);
654 }
655
656 insert_loop_limit_check(limit_check_proj, cmp_limit, bol);
657 }
658
659 // Now we need to canonicalize loop condition.
660 if (bt == BoolTest::ne) {
661 assert(stride_con == 1 || stride_con == -1, "simple increment only");
662 if (stride_con > 0 && init_t->_hi < limit_t->_lo) {
663 // 'ne' can be replaced with 'lt' only when init < limit.
664 bt = BoolTest::lt;
665 } else if (stride_con < 0 && init_t->_lo > limit_t->_hi) {
666 // 'ne' can be replaced with 'gt' only when init > limit.
667 bt = BoolTest::gt;
668 } else {
669 ProjNode *limit_check_proj = find_predicate_insertion_point(init_control, Deoptimization::Reason_loop_limit_check);
670 if (!limit_check_proj) {
671 // The limit check predicate is not generated if this method trapped here before.
672 #ifdef ASSERT
673 if (TraceLoopLimitCheck) {
674 tty->print("missing loop limit check:");
675 loop->dump_head();
676 x->dump(1);
677 }
678 #endif
679 return false;
680 }
681 IfNode* check_iff = limit_check_proj->in(0)->as_If();
682
683 if (!is_dominator(get_ctrl(limit), check_iff->in(0)) ||
684 !is_dominator(get_ctrl(init_trip), check_iff->in(0))) {
685 return false;
686 }
687
688 Node* cmp_limit;
689 Node* bol;
690
691 if (stride_con > 0) {
692 cmp_limit = new CmpINode(init_trip, limit);
693 bol = new BoolNode(cmp_limit, BoolTest::lt);
694 } else {
695 cmp_limit = new CmpINode(init_trip, limit);
696 bol = new BoolNode(cmp_limit, BoolTest::gt);
697 }
698
699 insert_loop_limit_check(limit_check_proj, cmp_limit, bol);
700
701 if (stride_con > 0) {
702 // 'ne' can be replaced with 'lt' only when init < limit.
703 bt = BoolTest::lt;
704 } else if (stride_con < 0) {
705 // 'ne' can be replaced with 'gt' only when init > limit.
706 bt = BoolTest::gt;
707 }
708 }
709 }
710
711 if (phi_incr != NULL) {
712 // If compare points directly to the phi we need to adjust
713 // the compare so that it points to the incr. Limit have
714 // to be adjusted to keep trip count the same and we
715 // should avoid int overflow.
716 //
717 // i = init; do {} while(i++ < limit);
718 // is converted to
719 // i = init; do {} while(++i < limit+1);
720 //
721 limit = gvn->transform(new AddINode(limit, stride));
722 }
723
724 if (incl_limit) {
725 // The limit check guaranties that 'limit <= (max_jint - stride)' so
726 // we can convert 'i <= limit' to 'i < limit+1' since stride != 0.
727 //
728 Node* one = (stride_con > 0) ? gvn->intcon( 1) : gvn->intcon(-1);
729 limit = gvn->transform(new AddINode(limit, one));
730 if (bt == BoolTest::le)
731 bt = BoolTest::lt;
732 else if (bt == BoolTest::ge)
733 bt = BoolTest::gt;
734 else
735 ShouldNotReachHere();
736 }
737 set_subtree_ctrl( limit );
738
739 if (LoopStripMiningIter == 0) {
740 // Check for SafePoint on backedge and remove
741 Node *sfpt = x->in(LoopNode::LoopBackControl);
742 if (sfpt->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt)) {
743 lazy_replace( sfpt, iftrue );
744 if (loop->_safepts != NULL) {
745 loop->_safepts->yank(sfpt);
746 }
747 loop->_tail = iftrue;
748 }
749 }
750
751 // Build a canonical trip test.
752 // Clone code, as old values may be in use.
753 incr = incr->clone();
754 incr->set_req(1,phi);
755 incr->set_req(2,stride);
756 incr = _igvn.register_new_node_with_optimizer(incr);
757 set_early_ctrl( incr );
758 _igvn.rehash_node_delayed(phi);
759 phi->set_req_X( LoopNode::LoopBackControl, incr, &_igvn );
760
761 // If phi type is more restrictive than Int, raise to
762 // Int to prevent (almost) infinite recursion in igvn
763 // which can only handle integer types for constants or minint..maxint.
764 if (!TypeInt::INT->higher_equal(phi->bottom_type())) {
765 Node* nphi = PhiNode::make(phi->in(0), phi->in(LoopNode::EntryControl), TypeInt::INT);
766 nphi->set_req(LoopNode::LoopBackControl, phi->in(LoopNode::LoopBackControl));
767 nphi = _igvn.register_new_node_with_optimizer(nphi);
768 set_ctrl(nphi, get_ctrl(phi));
769 _igvn.replace_node(phi, nphi);
770 phi = nphi->as_Phi();
771 }
772 cmp = cmp->clone();
773 cmp->set_req(1,incr);
774 cmp->set_req(2,limit);
775 cmp = _igvn.register_new_node_with_optimizer(cmp);
776 set_ctrl(cmp, iff->in(0));
777
778 test = test->clone()->as_Bool();
779 (*(BoolTest*)&test->_test)._test = bt;
780 test->set_req(1,cmp);
781 _igvn.register_new_node_with_optimizer(test);
782 set_ctrl(test, iff->in(0));
783
784 // Replace the old IfNode with a new LoopEndNode
785 Node *lex = _igvn.register_new_node_with_optimizer(new CountedLoopEndNode( iff->in(0), test, cl_prob, iff->as_If()->_fcnt ));
786 IfNode *le = lex->as_If();
787 uint dd = dom_depth(iff);
788 set_idom(le, le->in(0), dd); // Update dominance for loop exit
789 set_loop(le, loop);
790
791 // Get the loop-exit control
792 Node *iffalse = iff->as_If()->proj_out(!(iftrue_op == Op_IfTrue));
793
794 // Need to swap loop-exit and loop-back control?
795 if (iftrue_op == Op_IfFalse) {
796 Node *ift2=_igvn.register_new_node_with_optimizer(new IfTrueNode (le));
797 Node *iff2=_igvn.register_new_node_with_optimizer(new IfFalseNode(le));
798
799 loop->_tail = back_control = ift2;
800 set_loop(ift2, loop);
801 set_loop(iff2, get_loop(iffalse));
802
803 // Lazy update of 'get_ctrl' mechanism.
804 lazy_replace(iffalse, iff2);
805 lazy_replace(iftrue, ift2);
806
807 // Swap names
808 iffalse = iff2;
809 iftrue = ift2;
810 } else {
811 _igvn.rehash_node_delayed(iffalse);
812 _igvn.rehash_node_delayed(iftrue);
813 iffalse->set_req_X( 0, le, &_igvn );
814 iftrue ->set_req_X( 0, le, &_igvn );
815 }
816
817 set_idom(iftrue, le, dd+1);
818 set_idom(iffalse, le, dd+1);
819 assert(iff->outcnt() == 0, "should be dead now");
820 lazy_replace( iff, le ); // fix 'get_ctrl'
821
822 Node *sfpt2 = le->in(0);
823
824 Node* entry_control = init_control;
825 bool strip_mine_loop = LoopStripMiningIter > 1 && loop->_child == NULL &&
826 sfpt2->Opcode() == Op_SafePoint && !loop->_has_call;
827 IdealLoopTree* outer_ilt = NULL;
828 if (strip_mine_loop) {
829 outer_ilt = create_outer_strip_mined_loop(test, cmp, init_control, loop,
830 cl_prob, le->_fcnt, entry_control,
831 iffalse);
832 }
833
834 // Now setup a new CountedLoopNode to replace the existing LoopNode
835 CountedLoopNode *l = new CountedLoopNode(entry_control, back_control);
836 l->set_unswitch_count(x->as_Loop()->unswitch_count()); // Preserve
837 // The following assert is approximately true, and defines the intention
838 // of can_be_counted_loop. It fails, however, because phase->type
839 // is not yet initialized for this loop and its parts.
840 //assert(l->can_be_counted_loop(this), "sanity");
841 _igvn.register_new_node_with_optimizer(l);
842 set_loop(l, loop);
843 loop->_head = l;
844 // Fix all data nodes placed at the old loop head.
845 // Uses the lazy-update mechanism of 'get_ctrl'.
846 lazy_replace( x, l );
847 set_idom(l, entry_control, dom_depth(entry_control) + 1);
848
849 if (LoopStripMiningIter == 0 || strip_mine_loop) {
850 // Check for immediately preceding SafePoint and remove
851 if (sfpt2->Opcode() == Op_SafePoint && (LoopStripMiningIter != 0 || is_deleteable_safept(sfpt2))) {
852 if (strip_mine_loop) {
853 Node* outer_le = outer_ilt->_tail->in(0);
854 Node* sfpt = sfpt2->clone();
855 sfpt->set_req(0, iffalse);
856 outer_le->set_req(0, sfpt);
857 register_control(sfpt, outer_ilt, iffalse);
858 set_idom(outer_le, sfpt, dom_depth(sfpt));
859 }
860 lazy_replace( sfpt2, sfpt2->in(TypeFunc::Control));
861 if (loop->_safepts != NULL) {
862 loop->_safepts->yank(sfpt2);
863 }
864 }
865 }
866
867 // Free up intermediate goo
868 _igvn.remove_dead_node(hook);
869
870 #ifdef ASSERT
871 assert(l->is_valid_counted_loop(), "counted loop shape is messed up");
872 assert(l == loop->_head && l->phi() == phi && l->loopexit_or_null() == lex, "" );
873 #endif
874 #ifndef PRODUCT
875 if (TraceLoopOpts) {
876 tty->print("Counted ");
877 loop->dump_head();
878 }
879 #endif
880
881 C->print_method(PHASE_AFTER_CLOOPS, 3);
882
883 // Capture bounds of the loop in the induction variable Phi before
884 // subsequent transformation (iteration splitting) obscures the
885 // bounds
886 l->phi()->as_Phi()->set_type(l->phi()->Value(&_igvn));
887
888 if (strip_mine_loop) {
889 l->mark_strip_mined();
890 l->verify_strip_mined(1);
891 outer_ilt->_head->as_Loop()->verify_strip_mined(1);
892 loop = outer_ilt;
893 }
894
895 return true;
896 }
897
898 //----------------------exact_limit-------------------------------------------
899 Node* PhaseIdealLoop::exact_limit( IdealLoopTree *loop ) {
900 assert(loop->_head->is_CountedLoop(), "");
901 CountedLoopNode *cl = loop->_head->as_CountedLoop();
902 assert(cl->is_valid_counted_loop(), "");
903
904 if (ABS(cl->stride_con()) == 1 ||
905 cl->limit()->Opcode() == Op_LoopLimit) {
906 // Old code has exact limit (it could be incorrect in case of int overflow).
907 // Loop limit is exact with stride == 1. And loop may already have exact limit.
908 return cl->limit();
909 }
910 Node *limit = NULL;
911 #ifdef ASSERT
912 BoolTest::mask bt = cl->loopexit()->test_trip();
913 assert(bt == BoolTest::lt || bt == BoolTest::gt, "canonical test is expected");
914 #endif
915 if (cl->has_exact_trip_count()) {
916 // Simple case: loop has constant boundaries.
917 // Use jlongs to avoid integer overflow.
918 int stride_con = cl->stride_con();
919 jlong init_con = cl->init_trip()->get_int();
920 jlong limit_con = cl->limit()->get_int();
921 julong trip_cnt = cl->trip_count();
922 jlong final_con = init_con + trip_cnt*stride_con;
923 int final_int = (int)final_con;
924 // The final value should be in integer range since the loop
925 // is counted and the limit was checked for overflow.
926 assert(final_con == (jlong)final_int, "final value should be integer");
927 limit = _igvn.intcon(final_int);
928 } else {
929 // Create new LoopLimit node to get exact limit (final iv value).
930 limit = new LoopLimitNode(C, cl->init_trip(), cl->limit(), cl->stride());
931 register_new_node(limit, cl->in(LoopNode::EntryControl));
932 }
933 assert(limit != NULL, "sanity");
934 return limit;
935 }
936
937 //------------------------------Ideal------------------------------------------
938 // Return a node which is more "ideal" than the current node.
939 // Attempt to convert into a counted-loop.
940 Node *LoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
941 if (!can_be_counted_loop(phase) && !is_OuterStripMinedLoop()) {
942 phase->C->set_major_progress();
943 }
944 return RegionNode::Ideal(phase, can_reshape);
945 }
946
947 void LoopNode::verify_strip_mined(int expect_skeleton) const {
948 #ifdef ASSERT
949 const OuterStripMinedLoopNode* outer = NULL;
950 const CountedLoopNode* inner = NULL;
951 if (is_strip_mined()) {
952 assert(is_CountedLoop(), "no Loop should be marked strip mined");
953 inner = as_CountedLoop();
954 outer = inner->in(LoopNode::EntryControl)->as_OuterStripMinedLoop();
955 } else if (is_OuterStripMinedLoop()) {
956 outer = this->as_OuterStripMinedLoop();
957 inner = outer->unique_ctrl_out()->as_CountedLoop();
958 assert(!is_strip_mined(), "outer loop shouldn't be marked strip mined");
959 }
960 if (inner != NULL || outer != NULL) {
961 assert(inner != NULL && outer != NULL, "missing loop in strip mined nest");
962 Node* outer_tail = outer->in(LoopNode::LoopBackControl);
963 Node* outer_le = outer_tail->in(0);
964 assert(outer_le->Opcode() == Op_OuterStripMinedLoopEnd, "tail of outer loop should be an If");
965 Node* sfpt = outer_le->in(0);
966 assert(sfpt->Opcode() == Op_SafePoint, "where's the safepoint?");
967 Node* inner_out = sfpt->in(0);
968 if (inner_out->outcnt() != 1) {
969 ResourceMark rm;
970 Unique_Node_List wq;
971
972 for (DUIterator_Fast imax, i = inner_out->fast_outs(imax); i < imax; i++) {
973 Node* u = inner_out->fast_out(i);
974 if (u == sfpt) {
975 continue;
976 }
977 wq.clear();
978 wq.push(u);
979 bool found_sfpt = false;
980 for (uint next = 0; next < wq.size() && !found_sfpt; next++) {
981 Node* n = wq.at(next);
982 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax && !found_sfpt; i++) {
983 Node* u = n->fast_out(i);
984 if (u == sfpt) {
985 found_sfpt = true;
986 }
987 if (!u->is_CFG()) {
988 wq.push(u);
989 }
990 }
991 }
992 assert(found_sfpt, "no node in loop that's not input to safepoint");
993 }
994 }
995
996 CountedLoopEndNode* cle = inner_out->in(0)->as_CountedLoopEnd();
997 assert(cle == inner->loopexit_or_null(), "mismatch");
998 bool has_skeleton = outer_le->in(1)->bottom_type()->singleton() && outer_le->in(1)->bottom_type()->is_int()->get_con() == 0;
999 if (has_skeleton) {
1000 assert(expect_skeleton == 1 || expect_skeleton == -1, "unexpected skeleton node");
1001 assert(outer->outcnt() == 2, "only phis");
1002 } else {
1003 assert(expect_skeleton == 0 || expect_skeleton == -1, "no skeleton node?");
1004 uint phis = 0;
1005 for (DUIterator_Fast imax, i = inner->fast_outs(imax); i < imax; i++) {
1006 Node* u = inner->fast_out(i);
1007 if (u->is_Phi()) {
1008 phis++;
1009 }
1010 }
1011 for (DUIterator_Fast imax, i = outer->fast_outs(imax); i < imax; i++) {
1012 Node* u = outer->fast_out(i);
1013 assert(u == outer || u == inner || u->is_Phi(), "nothing between inner and outer loop");
1014 }
1015 uint stores = 0;
1016 for (DUIterator_Fast imax, i = inner_out->fast_outs(imax); i < imax; i++) {
1017 Node* u = inner_out->fast_out(i);
1018 if (u->is_Store()) {
1019 stores++;
1020 }
1021 }
1022 assert(outer->outcnt() >= phis + 2 && outer->outcnt() <= phis + 2 + stores + 1, "only phis");
1023 }
1024 assert(sfpt->outcnt() == 1, "no data node");
1025 assert(outer_tail->outcnt() == 1 || !has_skeleton, "no data node");
1026 }
1027 #endif
1028 }
1029
1030 //=============================================================================
1031 //------------------------------Ideal------------------------------------------
1032 // Return a node which is more "ideal" than the current node.
1033 // Attempt to convert into a counted-loop.
1034 Node *CountedLoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1035 return RegionNode::Ideal(phase, can_reshape);
1036 }
1037
1038 //------------------------------dump_spec--------------------------------------
1039 // Dump special per-node info
1040 #ifndef PRODUCT
1041 void CountedLoopNode::dump_spec(outputStream *st) const {
1042 LoopNode::dump_spec(st);
1043 if (stride_is_con()) {
1044 st->print("stride: %d ",stride_con());
1045 }
1046 if (is_pre_loop ()) st->print("pre of N%d" , _main_idx);
1047 if (is_main_loop()) st->print("main of N%d", _idx);
1048 if (is_post_loop()) st->print("post of N%d", _main_idx);
1049 if (is_strip_mined()) st->print(" strip mined");
1050 }
1051 #endif
1052
1053 //=============================================================================
1054 int CountedLoopEndNode::stride_con() const {
1055 return stride()->bottom_type()->is_int()->get_con();
1056 }
1057
1058 //=============================================================================
1059 //------------------------------Value-----------------------------------------
1060 const Type* LoopLimitNode::Value(PhaseGVN* phase) const {
1061 const Type* init_t = phase->type(in(Init));
1062 const Type* limit_t = phase->type(in(Limit));
1063 const Type* stride_t = phase->type(in(Stride));
1064 // Either input is TOP ==> the result is TOP
1065 if (init_t == Type::TOP) return Type::TOP;
1066 if (limit_t == Type::TOP) return Type::TOP;
1067 if (stride_t == Type::TOP) return Type::TOP;
1068
1069 int stride_con = stride_t->is_int()->get_con();
1070 if (stride_con == 1)
1071 return NULL; // Identity
1072
1073 if (init_t->is_int()->is_con() && limit_t->is_int()->is_con()) {
1074 // Use jlongs to avoid integer overflow.
1075 jlong init_con = init_t->is_int()->get_con();
1076 jlong limit_con = limit_t->is_int()->get_con();
1077 int stride_m = stride_con - (stride_con > 0 ? 1 : -1);
1078 jlong trip_count = (limit_con - init_con + stride_m)/stride_con;
1079 jlong final_con = init_con + stride_con*trip_count;
1080 int final_int = (int)final_con;
1081 // The final value should be in integer range since the loop
1082 // is counted and the limit was checked for overflow.
1083 assert(final_con == (jlong)final_int, "final value should be integer");
1084 return TypeInt::make(final_int);
1085 }
1086
1087 return bottom_type(); // TypeInt::INT
1088 }
1089
1090 //------------------------------Ideal------------------------------------------
1091 // Return a node which is more "ideal" than the current node.
1092 Node *LoopLimitNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1093 if (phase->type(in(Init)) == Type::TOP ||
1094 phase->type(in(Limit)) == Type::TOP ||
1095 phase->type(in(Stride)) == Type::TOP)
1096 return NULL; // Dead
1097
1098 int stride_con = phase->type(in(Stride))->is_int()->get_con();
1099 if (stride_con == 1)
1100 return NULL; // Identity
1101
1102 if (in(Init)->is_Con() && in(Limit)->is_Con())
1103 return NULL; // Value
1104
1105 // Delay following optimizations until all loop optimizations
1106 // done to keep Ideal graph simple.
1107 if (!can_reshape || phase->C->major_progress())
1108 return NULL;
1109
1110 const TypeInt* init_t = phase->type(in(Init) )->is_int();
1111 const TypeInt* limit_t = phase->type(in(Limit))->is_int();
1112 int stride_p;
1113 jlong lim, ini;
1114 julong max;
1115 if (stride_con > 0) {
1116 stride_p = stride_con;
1117 lim = limit_t->_hi;
1118 ini = init_t->_lo;
1119 max = (julong)max_jint;
1120 } else {
1121 stride_p = -stride_con;
1122 lim = init_t->_hi;
1123 ini = limit_t->_lo;
1124 max = (julong)min_jint;
1125 }
1126 julong range = lim - ini + stride_p;
1127 if (range <= max) {
1128 // Convert to integer expression if it is not overflow.
1129 Node* stride_m = phase->intcon(stride_con - (stride_con > 0 ? 1 : -1));
1130 Node *range = phase->transform(new SubINode(in(Limit), in(Init)));
1131 Node *bias = phase->transform(new AddINode(range, stride_m));
1132 Node *trip = phase->transform(new DivINode(0, bias, in(Stride)));
1133 Node *span = phase->transform(new MulINode(trip, in(Stride)));
1134 return new AddINode(span, in(Init)); // exact limit
1135 }
1136
1137 if (is_power_of_2(stride_p) || // divisor is 2^n
1138 !Matcher::has_match_rule(Op_LoopLimit)) { // or no specialized Mach node?
1139 // Convert to long expression to avoid integer overflow
1140 // and let igvn optimizer convert this division.
1141 //
1142 Node* init = phase->transform( new ConvI2LNode(in(Init)));
1143 Node* limit = phase->transform( new ConvI2LNode(in(Limit)));
1144 Node* stride = phase->longcon(stride_con);
1145 Node* stride_m = phase->longcon(stride_con - (stride_con > 0 ? 1 : -1));
1146
1147 Node *range = phase->transform(new SubLNode(limit, init));
1148 Node *bias = phase->transform(new AddLNode(range, stride_m));
1149 Node *span;
1150 if (stride_con > 0 && is_power_of_2(stride_p)) {
1151 // bias >= 0 if stride >0, so if stride is 2^n we can use &(-stride)
1152 // and avoid generating rounding for division. Zero trip guard should
1153 // guarantee that init < limit but sometimes the guard is missing and
1154 // we can get situation when init > limit. Note, for the empty loop
1155 // optimization zero trip guard is generated explicitly which leaves
1156 // only RCE predicate where exact limit is used and the predicate
1157 // will simply fail forcing recompilation.
1158 Node* neg_stride = phase->longcon(-stride_con);
1159 span = phase->transform(new AndLNode(bias, neg_stride));
1160 } else {
1161 Node *trip = phase->transform(new DivLNode(0, bias, stride));
1162 span = phase->transform(new MulLNode(trip, stride));
1163 }
1164 // Convert back to int
1165 Node *span_int = phase->transform(new ConvL2INode(span));
1166 return new AddINode(span_int, in(Init)); // exact limit
1167 }
1168
1169 return NULL; // No progress
1170 }
1171
1172 //------------------------------Identity---------------------------------------
1173 // If stride == 1 return limit node.
1174 Node* LoopLimitNode::Identity(PhaseGVN* phase) {
1175 int stride_con = phase->type(in(Stride))->is_int()->get_con();
1176 if (stride_con == 1 || stride_con == -1)
1177 return in(Limit);
1178 return this;
1179 }
1180
1181 //=============================================================================
1182 //----------------------match_incr_with_optional_truncation--------------------
1183 // Match increment with optional truncation:
1184 // CHAR: (i+1)&0x7fff, BYTE: ((i+1)<<8)>>8, or SHORT: ((i+1)<<16)>>16
1185 // Return NULL for failure. Success returns the increment node.
1186 Node* CountedLoopNode::match_incr_with_optional_truncation(
1187 Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type) {
1188 // Quick cutouts:
1189 if (expr == NULL || expr->req() != 3) return NULL;
1190
1191 Node *t1 = NULL;
1192 Node *t2 = NULL;
1193 const TypeInt* trunc_t = TypeInt::INT;
1194 Node* n1 = expr;
1195 int n1op = n1->Opcode();
1196
1197 // Try to strip (n1 & M) or (n1 << N >> N) from n1.
1198 if (n1op == Op_AndI &&
1199 n1->in(2)->is_Con() &&
1200 n1->in(2)->bottom_type()->is_int()->get_con() == 0x7fff) {
1201 // %%% This check should match any mask of 2**K-1.
1202 t1 = n1;
1203 n1 = t1->in(1);
1204 n1op = n1->Opcode();
1205 trunc_t = TypeInt::CHAR;
1206 } else if (n1op == Op_RShiftI &&
1207 n1->in(1) != NULL &&
1208 n1->in(1)->Opcode() == Op_LShiftI &&
1209 n1->in(2) == n1->in(1)->in(2) &&
1210 n1->in(2)->is_Con()) {
1211 jint shift = n1->in(2)->bottom_type()->is_int()->get_con();
1212 // %%% This check should match any shift in [1..31].
1213 if (shift == 16 || shift == 8) {
1214 t1 = n1;
1215 t2 = t1->in(1);
1216 n1 = t2->in(1);
1217 n1op = n1->Opcode();
1218 if (shift == 16) {
1219 trunc_t = TypeInt::SHORT;
1220 } else if (shift == 8) {
1221 trunc_t = TypeInt::BYTE;
1222 }
1223 }
1224 }
1225
1226 // If (maybe after stripping) it is an AddI, we won:
1227 if (n1op == Op_AddI) {
1228 *trunc1 = t1;
1229 *trunc2 = t2;
1230 *trunc_type = trunc_t;
1231 return n1;
1232 }
1233
1234 // failed
1235 return NULL;
1236 }
1237
1238 LoopNode* CountedLoopNode::skip_strip_mined(int expect_skeleton) {
1239 if (is_strip_mined()) {
1240 verify_strip_mined(expect_skeleton);
1241 return in(EntryControl)->as_Loop();
1242 }
1243 return this;
1244 }
1245
1246 OuterStripMinedLoopNode* CountedLoopNode::outer_loop() const {
1247 assert(is_strip_mined(), "not a strip mined loop");
1248 Node* c = in(EntryControl);
1249 if (c == NULL || c->is_top() || !c->is_OuterStripMinedLoop()) {
1250 return NULL;
1251 }
1252 return c->as_OuterStripMinedLoop();
1253 }
1254
1255 IfTrueNode* OuterStripMinedLoopNode::outer_loop_tail() const {
1256 Node* c = in(LoopBackControl);
1257 if (c == NULL || c->is_top()) {
1258 return NULL;
1259 }
1260 return c->as_IfTrue();
1261 }
1262
1263 IfTrueNode* CountedLoopNode::outer_loop_tail() const {
1264 LoopNode* l = outer_loop();
1265 if (l == NULL) {
1266 return NULL;
1267 }
1268 return l->outer_loop_tail();
1269 }
1270
1271 OuterStripMinedLoopEndNode* OuterStripMinedLoopNode::outer_loop_end() const {
1272 IfTrueNode* proj = outer_loop_tail();
1273 if (proj == NULL) {
1274 return NULL;
1275 }
1276 Node* c = proj->in(0);
1277 if (c == NULL || c->is_top() || c->outcnt() != 2) {
1278 return NULL;
1279 }
1280 return c->as_OuterStripMinedLoopEnd();
1281 }
1282
1283 OuterStripMinedLoopEndNode* CountedLoopNode::outer_loop_end() const {
1284 LoopNode* l = outer_loop();
1285 if (l == NULL) {
1286 return NULL;
1287 }
1288 return l->outer_loop_end();
1289 }
1290
1291 IfFalseNode* OuterStripMinedLoopNode::outer_loop_exit() const {
1292 IfNode* le = outer_loop_end();
1293 if (le == NULL) {
1294 return NULL;
1295 }
1296 Node* c = le->proj_out_or_null(false);
1297 if (c == NULL) {
1298 return NULL;
1299 }
1300 return c->as_IfFalse();
1301 }
1302
1303 IfFalseNode* CountedLoopNode::outer_loop_exit() const {
1304 LoopNode* l = outer_loop();
1305 if (l == NULL) {
1306 return NULL;
1307 }
1308 return l->outer_loop_exit();
1309 }
1310
1311 SafePointNode* OuterStripMinedLoopNode::outer_safepoint() const {
1312 IfNode* le = outer_loop_end();
1313 if (le == NULL) {
1314 return NULL;
1315 }
1316 Node* c = le->in(0);
1317 if (c == NULL || c->is_top()) {
1318 return NULL;
1319 }
1320 assert(c->Opcode() == Op_SafePoint, "broken outer loop");
1321 return c->as_SafePoint();
1322 }
1323
1324 SafePointNode* CountedLoopNode::outer_safepoint() const {
1325 LoopNode* l = outer_loop();
1326 if (l == NULL) {
1327 return NULL;
1328 }
1329 return l->outer_safepoint();
1330 }
1331
1332 Node* CountedLoopNode::skip_predicates_from_entry(Node* ctrl) {
1333 while (ctrl != NULL && ctrl->is_Proj() && ctrl->in(0)->is_If() &&
1334 ctrl->in(0)->as_If()->proj_out(1-ctrl->as_Proj()->_con)->outcnt() == 1 &&
1335 ctrl->in(0)->as_If()->proj_out(1-ctrl->as_Proj()->_con)->unique_out()->Opcode() == Op_Halt) {
1336 ctrl = ctrl->in(0)->in(0);
1337 }
1338
1339 return ctrl;
1340 }
1341
1342 Node* CountedLoopNode::skip_predicates() {
1343 if (is_main_loop()) {
1344 Node* ctrl = skip_strip_mined()->in(LoopNode::EntryControl);
1345
1346 return skip_predicates_from_entry(ctrl);
1347 }
1348 return in(LoopNode::EntryControl);
1349 }
1350
1351 void OuterStripMinedLoopNode::adjust_strip_mined_loop(PhaseIterGVN* igvn) {
1352 // Look for the outer & inner strip mined loop, reduce number of
1353 // iterations of the inner loop, set exit condition of outer loop,
1354 // construct required phi nodes for outer loop.
1355 CountedLoopNode* inner_cl = unique_ctrl_out()->as_CountedLoop();
1356 assert(inner_cl->is_strip_mined(), "inner loop should be strip mined");
1357 Node* inner_iv_phi = inner_cl->phi();
1358 if (inner_iv_phi == NULL) {
1359 IfNode* outer_le = outer_loop_end();
1360 Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt));
1361 igvn->replace_node(outer_le, iff);
1362 inner_cl->clear_strip_mined();
1363 return;
1364 }
1365 CountedLoopEndNode* inner_cle = inner_cl->loopexit();
1366
1367 int stride = inner_cl->stride_con();
1368 jlong scaled_iters_long = ((jlong)LoopStripMiningIter) * ABS(stride);
1369 int scaled_iters = (int)scaled_iters_long;
1370 int short_scaled_iters = LoopStripMiningIterShortLoop* ABS(stride);
1371 const TypeInt* inner_iv_t = igvn->type(inner_iv_phi)->is_int();
1372 jlong iter_estimate = (jlong)inner_iv_t->_hi - (jlong)inner_iv_t->_lo;
1373 assert(iter_estimate > 0, "broken");
1374 if ((jlong)scaled_iters != scaled_iters_long || iter_estimate <= short_scaled_iters) {
1375 // Remove outer loop and safepoint (too few iterations)
1376 Node* outer_sfpt = outer_safepoint();
1377 Node* outer_out = outer_loop_exit();
1378 igvn->replace_node(outer_out, outer_sfpt->in(0));
1379 igvn->replace_input_of(outer_sfpt, 0, igvn->C->top());
1380 inner_cl->clear_strip_mined();
1381 return;
1382 }
1383 if (iter_estimate <= scaled_iters_long) {
1384 // We would only go through one iteration of
1385 // the outer loop: drop the outer loop but
1386 // keep the safepoint so we don't run for
1387 // too long without a safepoint
1388 IfNode* outer_le = outer_loop_end();
1389 Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt));
1390 igvn->replace_node(outer_le, iff);
1391 inner_cl->clear_strip_mined();
1392 return;
1393 }
1394
1395 Node* cle_tail = inner_cle->proj_out(true);
1396 ResourceMark rm;
1397 Node_List old_new;
1398 if (cle_tail->outcnt() > 1) {
1399 // Look for nodes on backedge of inner loop and clone them
1400 Unique_Node_List backedge_nodes;
1401 for (DUIterator_Fast imax, i = cle_tail->fast_outs(imax); i < imax; i++) {
1402 Node* u = cle_tail->fast_out(i);
1403 if (u != inner_cl) {
1404 assert(!u->is_CFG(), "control flow on the backedge?");
1405 backedge_nodes.push(u);
1406 }
1407 }
1408 uint last = igvn->C->unique();
1409 for (uint next = 0; next < backedge_nodes.size(); next++) {
1410 Node* n = backedge_nodes.at(next);
1411 old_new.map(n->_idx, n->clone());
1412 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1413 Node* u = n->fast_out(i);
1414 assert(!u->is_CFG(), "broken");
1415 if (u->_idx >= last) {
1416 continue;
1417 }
1418 if (!u->is_Phi()) {
1419 backedge_nodes.push(u);
1420 } else {
1421 assert(u->in(0) == inner_cl, "strange phi on the backedge");
1422 }
1423 }
1424 }
1425 // Put the clones on the outer loop backedge
1426 Node* le_tail = outer_loop_tail();
1427 for (uint next = 0; next < backedge_nodes.size(); next++) {
1428 Node *n = old_new[backedge_nodes.at(next)->_idx];
1429 for (uint i = 1; i < n->req(); i++) {
1430 if (n->in(i) != NULL && old_new[n->in(i)->_idx] != NULL) {
1431 n->set_req(i, old_new[n->in(i)->_idx]);
1432 }
1433 }
1434 if (n->in(0) != NULL && n->in(0) == cle_tail) {
1435 n->set_req(0, le_tail);
1436 }
1437 igvn->register_new_node_with_optimizer(n);
1438 }
1439 }
1440
1441 Node* iv_phi = NULL;
1442 // Make a clone of each phi in the inner loop
1443 // for the outer loop
1444 for (uint i = 0; i < inner_cl->outcnt(); i++) {
1445 Node* u = inner_cl->raw_out(i);
1446 if (u->is_Phi()) {
1447 assert(u->in(0) == inner_cl, "inconsistent");
1448 Node* phi = u->clone();
1449 phi->set_req(0, this);
1450 Node* be = old_new[phi->in(LoopNode::LoopBackControl)->_idx];
1451 if (be != NULL) {
1452 phi->set_req(LoopNode::LoopBackControl, be);
1453 }
1454 phi = igvn->transform(phi);
1455 igvn->replace_input_of(u, LoopNode::EntryControl, phi);
1456 if (u == inner_iv_phi) {
1457 iv_phi = phi;
1458 }
1459 }
1460 }
1461 Node* cle_out = inner_cle->proj_out(false);
1462 if (cle_out->outcnt() > 1) {
1463 // Look for chains of stores that were sunk
1464 // out of the inner loop and are in the outer loop
1465 for (DUIterator_Fast imax, i = cle_out->fast_outs(imax); i < imax; i++) {
1466 Node* u = cle_out->fast_out(i);
1467 if (u->is_Store()) {
1468 Node* first = u;
1469 for(;;) {
1470 Node* next = first->in(MemNode::Memory);
1471 if (!next->is_Store() || next->in(0) != cle_out) {
1472 break;
1473 }
1474 first = next;
1475 }
1476 Node* last = u;
1477 for(;;) {
1478 Node* next = NULL;
1479 for (DUIterator_Fast jmax, j = last->fast_outs(jmax); j < jmax; j++) {
1480 Node* uu = last->fast_out(j);
1481 if (uu->is_Store() && uu->in(0) == cle_out) {
1482 assert(next == NULL, "only one in the outer loop");
1483 next = uu;
1484 }
1485 }
1486 if (next == NULL) {
1487 break;
1488 }
1489 last = next;
1490 }
1491 Node* phi = NULL;
1492 for (DUIterator_Fast jmax, j = fast_outs(jmax); j < jmax; j++) {
1493 Node* uu = fast_out(j);
1494 if (uu->is_Phi()) {
1495 Node* be = uu->in(LoopNode::LoopBackControl);
1496 if (be->is_Store() && old_new[be->_idx] != NULL) {
1497 assert(false, "store on the backedge + sunk stores: unsupported");
1498 // drop outer loop
1499 IfNode* outer_le = outer_loop_end();
1500 Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt));
1501 igvn->replace_node(outer_le, iff);
1502 inner_cl->clear_strip_mined();
1503 return;
1504 }
1505 if (be == last || be == first->in(MemNode::Memory)) {
1506 assert(phi == NULL, "only one phi");
1507 phi = uu;
1508 }
1509 }
1510 }
1511 #ifdef ASSERT
1512 for (DUIterator_Fast jmax, j = fast_outs(jmax); j < jmax; j++) {
1513 Node* uu = fast_out(j);
1514 if (uu->is_Phi() && uu->bottom_type() == Type::MEMORY) {
1515 if (uu->adr_type() == igvn->C->get_adr_type(igvn->C->get_alias_index(u->adr_type()))) {
1516 assert(phi == uu, "what's that phi?");
1517 } else if (uu->adr_type() == TypePtr::BOTTOM) {
1518 Node* n = uu->in(LoopNode::LoopBackControl);
1519 uint limit = igvn->C->live_nodes();
1520 uint i = 0;
1521 while (n != uu) {
1522 i++;
1523 assert(i < limit, "infinite loop");
1524 if (n->is_Proj()) {
1525 n = n->in(0);
1526 } else if (n->is_SafePoint() || n->is_MemBar()) {
1527 n = n->in(TypeFunc::Memory);
1528 } else if (n->is_Phi()) {
1529 n = n->in(1);
1530 } else if (n->is_MergeMem()) {
1531 n = n->as_MergeMem()->memory_at(igvn->C->get_alias_index(u->adr_type()));
1532 } else if (n->is_Store() || n->is_LoadStore() || n->is_ClearArray()) {
1533 n = n->in(MemNode::Memory);
1534 } else {
1535 n->dump();
1536 ShouldNotReachHere();
1537 }
1538 }
1539 }
1540 }
1541 }
1542 #endif
1543 if (phi == NULL) {
1544 // If the an entire chains was sunk, the
1545 // inner loop has no phi for that memory
1546 // slice, create one for the outer loop
1547 phi = PhiNode::make(this, first->in(MemNode::Memory), Type::MEMORY,
1548 igvn->C->get_adr_type(igvn->C->get_alias_index(u->adr_type())));
1549 phi->set_req(LoopNode::LoopBackControl, last);
1550 phi = igvn->transform(phi);
1551 igvn->replace_input_of(first, MemNode::Memory, phi);
1552 } else {
1553 // Or fix the outer loop fix to include
1554 // that chain of stores.
1555 Node* be = phi->in(LoopNode::LoopBackControl);
1556 assert(!(be->is_Store() && old_new[be->_idx] != NULL), "store on the backedge + sunk stores: unsupported");
1557 if (be == first->in(MemNode::Memory)) {
1558 if (be == phi->in(LoopNode::LoopBackControl)) {
1559 igvn->replace_input_of(phi, LoopNode::LoopBackControl, last);
1560 } else {
1561 igvn->replace_input_of(be, MemNode::Memory, last);
1562 }
1563 } else {
1564 #ifdef ASSERT
1565 if (be == phi->in(LoopNode::LoopBackControl)) {
1566 assert(phi->in(LoopNode::LoopBackControl) == last, "");
1567 } else {
1568 assert(be->in(MemNode::Memory) == last, "");
1569 }
1570 #endif
1571 }
1572 }
1573 }
1574 }
1575 }
1576
1577 if (iv_phi != NULL) {
1578 // Now adjust the inner loop's exit condition
1579 Node* limit = inner_cl->limit();
1580 Node* sub = NULL;
1581 if (stride > 0) {
1582 sub = igvn->transform(new SubINode(limit, iv_phi));
1583 } else {
1584 sub = igvn->transform(new SubINode(iv_phi, limit));
1585 }
1586 Node* min = igvn->transform(new MinINode(sub, igvn->intcon(scaled_iters)));
1587 Node* new_limit = NULL;
1588 if (stride > 0) {
1589 new_limit = igvn->transform(new AddINode(min, iv_phi));
1590 } else {
1591 new_limit = igvn->transform(new SubINode(iv_phi, min));
1592 }
1593 Node* inner_cmp = inner_cle->cmp_node();
1594 Node* inner_bol = inner_cle->in(CountedLoopEndNode::TestValue);
1595 Node* outer_bol = inner_bol;
1596 // cmp node for inner loop may be shared
1597 inner_cmp = inner_cmp->clone();
1598 inner_cmp->set_req(2, new_limit);
1599 inner_bol = inner_bol->clone();
1600 inner_bol->set_req(1, igvn->transform(inner_cmp));
1601 igvn->replace_input_of(inner_cle, CountedLoopEndNode::TestValue, igvn->transform(inner_bol));
1602 // Set the outer loop's exit condition too
1603 igvn->replace_input_of(outer_loop_end(), 1, outer_bol);
1604 } else {
1605 assert(false, "should be able to adjust outer loop");
1606 IfNode* outer_le = outer_loop_end();
1607 Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt));
1608 igvn->replace_node(outer_le, iff);
1609 inner_cl->clear_strip_mined();
1610 }
1611 }
1612
1613 const Type* OuterStripMinedLoopEndNode::Value(PhaseGVN* phase) const {
1614 if (!in(0)) return Type::TOP;
1615 if (phase->type(in(0)) == Type::TOP)
1616 return Type::TOP;
1617
1618 return TypeTuple::IFBOTH;
1619 }
1620
1621 Node *OuterStripMinedLoopEndNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1622 if (remove_dead_region(phase, can_reshape)) return this;
1623
1624 return NULL;
1625 }
1626
1627 //------------------------------filtered_type--------------------------------
1628 // Return a type based on condition control flow
1629 // A successful return will be a type that is restricted due
1630 // to a series of dominating if-tests, such as:
1631 // if (i < 10) {
1632 // if (i > 0) {
1633 // here: "i" type is [1..10)
1634 // }
1635 // }
1636 // or a control flow merge
1637 // if (i < 10) {
1638 // do {
1639 // phi( , ) -- at top of loop type is [min_int..10)
1640 // i = ?
1641 // } while ( i < 10)
1642 //
1643 const TypeInt* PhaseIdealLoop::filtered_type( Node *n, Node* n_ctrl) {
1644 assert(n && n->bottom_type()->is_int(), "must be int");
1645 const TypeInt* filtered_t = NULL;
1646 if (!n->is_Phi()) {
1647 assert(n_ctrl != NULL || n_ctrl == C->top(), "valid control");
1648 filtered_t = filtered_type_from_dominators(n, n_ctrl);
1649
1650 } else {
1651 Node* phi = n->as_Phi();
1652 Node* region = phi->in(0);
1653 assert(n_ctrl == NULL || n_ctrl == region, "ctrl parameter must be region");
1654 if (region && region != C->top()) {
1655 for (uint i = 1; i < phi->req(); i++) {
1656 Node* val = phi->in(i);
1657 Node* use_c = region->in(i);
1658 const TypeInt* val_t = filtered_type_from_dominators(val, use_c);
1659 if (val_t != NULL) {
1660 if (filtered_t == NULL) {
1661 filtered_t = val_t;
1662 } else {
1663 filtered_t = filtered_t->meet(val_t)->is_int();
1664 }
1665 }
1666 }
1667 }
1668 }
1669 const TypeInt* n_t = _igvn.type(n)->is_int();
1670 if (filtered_t != NULL) {
1671 n_t = n_t->join(filtered_t)->is_int();
1672 }
1673 return n_t;
1674 }
1675
1676
1677 //------------------------------filtered_type_from_dominators--------------------------------
1678 // Return a possibly more restrictive type for val based on condition control flow of dominators
1679 const TypeInt* PhaseIdealLoop::filtered_type_from_dominators( Node* val, Node *use_ctrl) {
1680 if (val->is_Con()) {
1681 return val->bottom_type()->is_int();
1682 }
1683 uint if_limit = 10; // Max number of dominating if's visited
1684 const TypeInt* rtn_t = NULL;
1685
1686 if (use_ctrl && use_ctrl != C->top()) {
1687 Node* val_ctrl = get_ctrl(val);
1688 uint val_dom_depth = dom_depth(val_ctrl);
1689 Node* pred = use_ctrl;
1690 uint if_cnt = 0;
1691 while (if_cnt < if_limit) {
1692 if ((pred->Opcode() == Op_IfTrue || pred->Opcode() == Op_IfFalse)) {
1693 if_cnt++;
1694 const TypeInt* if_t = IfNode::filtered_int_type(&_igvn, val, pred);
1695 if (if_t != NULL) {
1696 if (rtn_t == NULL) {
1697 rtn_t = if_t;
1698 } else {
1699 rtn_t = rtn_t->join(if_t)->is_int();
1700 }
1701 }
1702 }
1703 pred = idom(pred);
1704 if (pred == NULL || pred == C->top()) {
1705 break;
1706 }
1707 // Stop if going beyond definition block of val
1708 if (dom_depth(pred) < val_dom_depth) {
1709 break;
1710 }
1711 }
1712 }
1713 return rtn_t;
1714 }
1715
1716
1717 //------------------------------dump_spec--------------------------------------
1718 // Dump special per-node info
1719 #ifndef PRODUCT
1720 void CountedLoopEndNode::dump_spec(outputStream *st) const {
1721 if( in(TestValue) != NULL && in(TestValue)->is_Bool() ) {
1722 BoolTest bt( test_trip()); // Added this for g++.
1723
1724 st->print("[");
1725 bt.dump_on(st);
1726 st->print("]");
1727 }
1728 st->print(" ");
1729 IfNode::dump_spec(st);
1730 }
1731 #endif
1732
1733 //=============================================================================
1734 //------------------------------is_member--------------------------------------
1735 // Is 'l' a member of 'this'?
1736 bool IdealLoopTree::is_member(const IdealLoopTree *l) const {
1737 while( l->_nest > _nest ) l = l->_parent;
1738 return l == this;
1739 }
1740
1741 //------------------------------set_nest---------------------------------------
1742 // Set loop tree nesting depth. Accumulate _has_call bits.
1743 int IdealLoopTree::set_nest( uint depth ) {
1744 _nest = depth;
1745 int bits = _has_call;
1746 if( _child ) bits |= _child->set_nest(depth+1);
1747 if( bits ) _has_call = 1;
1748 if( _next ) bits |= _next ->set_nest(depth );
1749 return bits;
1750 }
1751
1752 //------------------------------split_fall_in----------------------------------
1753 // Split out multiple fall-in edges from the loop header. Move them to a
1754 // private RegionNode before the loop. This becomes the loop landing pad.
1755 void IdealLoopTree::split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ) {
1756 PhaseIterGVN &igvn = phase->_igvn;
1757 uint i;
1758
1759 // Make a new RegionNode to be the landing pad.
1760 Node *landing_pad = new RegionNode( fall_in_cnt+1 );
1761 phase->set_loop(landing_pad,_parent);
1762 // Gather all the fall-in control paths into the landing pad
1763 uint icnt = fall_in_cnt;
1764 uint oreq = _head->req();
1765 for( i = oreq-1; i>0; i-- )
1766 if( !phase->is_member( this, _head->in(i) ) )
1767 landing_pad->set_req(icnt--,_head->in(i));
1768
1769 // Peel off PhiNode edges as well
1770 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1771 Node *oj = _head->fast_out(j);
1772 if( oj->is_Phi() ) {
1773 PhiNode* old_phi = oj->as_Phi();
1774 assert( old_phi->region() == _head, "" );
1775 igvn.hash_delete(old_phi); // Yank from hash before hacking edges
1776 Node *p = PhiNode::make_blank(landing_pad, old_phi);
1777 uint icnt = fall_in_cnt;
1778 for( i = oreq-1; i>0; i-- ) {
1779 if( !phase->is_member( this, _head->in(i) ) ) {
1780 p->init_req(icnt--, old_phi->in(i));
1781 // Go ahead and clean out old edges from old phi
1782 old_phi->del_req(i);
1783 }
1784 }
1785 // Search for CSE's here, because ZKM.jar does a lot of
1786 // loop hackery and we need to be a little incremental
1787 // with the CSE to avoid O(N^2) node blow-up.
1788 Node *p2 = igvn.hash_find_insert(p); // Look for a CSE
1789 if( p2 ) { // Found CSE
1790 p->destruct(); // Recover useless new node
1791 p = p2; // Use old node
1792 } else {
1793 igvn.register_new_node_with_optimizer(p, old_phi);
1794 }
1795 // Make old Phi refer to new Phi.
1796 old_phi->add_req(p);
1797 // Check for the special case of making the old phi useless and
1798 // disappear it. In JavaGrande I have a case where this useless
1799 // Phi is the loop limit and prevents recognizing a CountedLoop
1800 // which in turn prevents removing an empty loop.
1801 Node *id_old_phi = igvn.apply_identity(old_phi);
1802 if( id_old_phi != old_phi ) { // Found a simple identity?
1803 // Note that I cannot call 'replace_node' here, because
1804 // that will yank the edge from old_phi to the Region and
1805 // I'm mid-iteration over the Region's uses.
1806 for (DUIterator_Last imin, i = old_phi->last_outs(imin); i >= imin; ) {
1807 Node* use = old_phi->last_out(i);
1808 igvn.rehash_node_delayed(use);
1809 uint uses_found = 0;
1810 for (uint j = 0; j < use->len(); j++) {
1811 if (use->in(j) == old_phi) {
1812 if (j < use->req()) use->set_req (j, id_old_phi);
1813 else use->set_prec(j, id_old_phi);
1814 uses_found++;
1815 }
1816 }
1817 i -= uses_found; // we deleted 1 or more copies of this edge
1818 }
1819 }
1820 igvn._worklist.push(old_phi);
1821 }
1822 }
1823 // Finally clean out the fall-in edges from the RegionNode
1824 for( i = oreq-1; i>0; i-- ) {
1825 if( !phase->is_member( this, _head->in(i) ) ) {
1826 _head->del_req(i);
1827 }
1828 }
1829 igvn.rehash_node_delayed(_head);
1830 // Transform landing pad
1831 igvn.register_new_node_with_optimizer(landing_pad, _head);
1832 // Insert landing pad into the header
1833 _head->add_req(landing_pad);
1834 }
1835
1836 //------------------------------split_outer_loop-------------------------------
1837 // Split out the outermost loop from this shared header.
1838 void IdealLoopTree::split_outer_loop( PhaseIdealLoop *phase ) {
1839 PhaseIterGVN &igvn = phase->_igvn;
1840
1841 // Find index of outermost loop; it should also be my tail.
1842 uint outer_idx = 1;
1843 while( _head->in(outer_idx) != _tail ) outer_idx++;
1844
1845 // Make a LoopNode for the outermost loop.
1846 Node *ctl = _head->in(LoopNode::EntryControl);
1847 Node *outer = new LoopNode( ctl, _head->in(outer_idx) );
1848 outer = igvn.register_new_node_with_optimizer(outer, _head);
1849 phase->set_created_loop_node();
1850
1851 // Outermost loop falls into '_head' loop
1852 _head->set_req(LoopNode::EntryControl, outer);
1853 _head->del_req(outer_idx);
1854 // Split all the Phis up between '_head' loop and 'outer' loop.
1855 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1856 Node *out = _head->fast_out(j);
1857 if( out->is_Phi() ) {
1858 PhiNode *old_phi = out->as_Phi();
1859 assert( old_phi->region() == _head, "" );
1860 Node *phi = PhiNode::make_blank(outer, old_phi);
1861 phi->init_req(LoopNode::EntryControl, old_phi->in(LoopNode::EntryControl));
1862 phi->init_req(LoopNode::LoopBackControl, old_phi->in(outer_idx));
1863 phi = igvn.register_new_node_with_optimizer(phi, old_phi);
1864 // Make old Phi point to new Phi on the fall-in path
1865 igvn.replace_input_of(old_phi, LoopNode::EntryControl, phi);
1866 old_phi->del_req(outer_idx);
1867 }
1868 }
1869
1870 // Use the new loop head instead of the old shared one
1871 _head = outer;
1872 phase->set_loop(_head, this);
1873 }
1874
1875 //------------------------------fix_parent-------------------------------------
1876 static void fix_parent( IdealLoopTree *loop, IdealLoopTree *parent ) {
1877 loop->_parent = parent;
1878 if( loop->_child ) fix_parent( loop->_child, loop );
1879 if( loop->_next ) fix_parent( loop->_next , parent );
1880 }
1881
1882 //------------------------------estimate_path_freq-----------------------------
1883 static float estimate_path_freq( Node *n ) {
1884 // Try to extract some path frequency info
1885 IfNode *iff;
1886 for( int i = 0; i < 50; i++ ) { // Skip through a bunch of uncommon tests
1887 uint nop = n->Opcode();
1888 if( nop == Op_SafePoint ) { // Skip any safepoint
1889 n = n->in(0);
1890 continue;
1891 }
1892 if( nop == Op_CatchProj ) { // Get count from a prior call
1893 // Assume call does not always throw exceptions: means the call-site
1894 // count is also the frequency of the fall-through path.
1895 assert( n->is_CatchProj(), "" );
1896 if( ((CatchProjNode*)n)->_con != CatchProjNode::fall_through_index )
1897 return 0.0f; // Assume call exception path is rare
1898 Node *call = n->in(0)->in(0)->in(0);
1899 assert( call->is_Call(), "expect a call here" );
1900 const JVMState *jvms = ((CallNode*)call)->jvms();
1901 ciMethodData* methodData = jvms->method()->method_data();
1902 if (!methodData->is_mature()) return 0.0f; // No call-site data
1903 ciProfileData* data = methodData->bci_to_data(jvms->bci());
1904 if ((data == NULL) || !data->is_CounterData()) {
1905 // no call profile available, try call's control input
1906 n = n->in(0);
1907 continue;
1908 }
1909 return data->as_CounterData()->count()/FreqCountInvocations;
1910 }
1911 // See if there's a gating IF test
1912 Node *n_c = n->in(0);
1913 if( !n_c->is_If() ) break; // No estimate available
1914 iff = n_c->as_If();
1915 if( iff->_fcnt != COUNT_UNKNOWN ) // Have a valid count?
1916 // Compute how much count comes on this path
1917 return ((nop == Op_IfTrue) ? iff->_prob : 1.0f - iff->_prob) * iff->_fcnt;
1918 // Have no count info. Skip dull uncommon-trap like branches.
1919 if( (nop == Op_IfTrue && iff->_prob < PROB_LIKELY_MAG(5)) ||
1920 (nop == Op_IfFalse && iff->_prob > PROB_UNLIKELY_MAG(5)) )
1921 break;
1922 // Skip through never-taken branch; look for a real loop exit.
1923 n = iff->in(0);
1924 }
1925 return 0.0f; // No estimate available
1926 }
1927
1928 //------------------------------merge_many_backedges---------------------------
1929 // Merge all the backedges from the shared header into a private Region.
1930 // Feed that region as the one backedge to this loop.
1931 void IdealLoopTree::merge_many_backedges( PhaseIdealLoop *phase ) {
1932 uint i;
1933
1934 // Scan for the top 2 hottest backedges
1935 float hotcnt = 0.0f;
1936 float warmcnt = 0.0f;
1937 uint hot_idx = 0;
1938 // Loop starts at 2 because slot 1 is the fall-in path
1939 for( i = 2; i < _head->req(); i++ ) {
1940 float cnt = estimate_path_freq(_head->in(i));
1941 if( cnt > hotcnt ) { // Grab hottest path
1942 warmcnt = hotcnt;
1943 hotcnt = cnt;
1944 hot_idx = i;
1945 } else if( cnt > warmcnt ) { // And 2nd hottest path
1946 warmcnt = cnt;
1947 }
1948 }
1949
1950 // See if the hottest backedge is worthy of being an inner loop
1951 // by being much hotter than the next hottest backedge.
1952 if( hotcnt <= 0.0001 ||
1953 hotcnt < 2.0*warmcnt ) hot_idx = 0;// No hot backedge
1954
1955 // Peel out the backedges into a private merge point; peel
1956 // them all except optionally hot_idx.
1957 PhaseIterGVN &igvn = phase->_igvn;
1958
1959 Node *hot_tail = NULL;
1960 // Make a Region for the merge point
1961 Node *r = new RegionNode(1);
1962 for( i = 2; i < _head->req(); i++ ) {
1963 if( i != hot_idx )
1964 r->add_req( _head->in(i) );
1965 else hot_tail = _head->in(i);
1966 }
1967 igvn.register_new_node_with_optimizer(r, _head);
1968 // Plug region into end of loop _head, followed by hot_tail
1969 while( _head->req() > 3 ) _head->del_req( _head->req()-1 );
1970 igvn.replace_input_of(_head, 2, r);
1971 if( hot_idx ) _head->add_req(hot_tail);
1972
1973 // Split all the Phis up between '_head' loop and the Region 'r'
1974 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1975 Node *out = _head->fast_out(j);
1976 if( out->is_Phi() ) {
1977 PhiNode* n = out->as_Phi();
1978 igvn.hash_delete(n); // Delete from hash before hacking edges
1979 Node *hot_phi = NULL;
1980 Node *phi = new PhiNode(r, n->type(), n->adr_type());
1981 // Check all inputs for the ones to peel out
1982 uint j = 1;
1983 for( uint i = 2; i < n->req(); i++ ) {
1984 if( i != hot_idx )
1985 phi->set_req( j++, n->in(i) );
1986 else hot_phi = n->in(i);
1987 }
1988 // Register the phi but do not transform until whole place transforms
1989 igvn.register_new_node_with_optimizer(phi, n);
1990 // Add the merge phi to the old Phi
1991 while( n->req() > 3 ) n->del_req( n->req()-1 );
1992 igvn.replace_input_of(n, 2, phi);
1993 if( hot_idx ) n->add_req(hot_phi);
1994 }
1995 }
1996
1997
1998 // Insert a new IdealLoopTree inserted below me. Turn it into a clone
1999 // of self loop tree. Turn self into a loop headed by _head and with
2000 // tail being the new merge point.
2001 IdealLoopTree *ilt = new IdealLoopTree( phase, _head, _tail );
2002 phase->set_loop(_tail,ilt); // Adjust tail
2003 _tail = r; // Self's tail is new merge point
2004 phase->set_loop(r,this);
2005 ilt->_child = _child; // New guy has my children
2006 _child = ilt; // Self has new guy as only child
2007 ilt->_parent = this; // new guy has self for parent
2008 ilt->_nest = _nest; // Same nesting depth (for now)
2009
2010 // Starting with 'ilt', look for child loop trees using the same shared
2011 // header. Flatten these out; they will no longer be loops in the end.
2012 IdealLoopTree **pilt = &_child;
2013 while( ilt ) {
2014 if( ilt->_head == _head ) {
2015 uint i;
2016 for( i = 2; i < _head->req(); i++ )
2017 if( _head->in(i) == ilt->_tail )
2018 break; // Still a loop
2019 if( i == _head->req() ) { // No longer a loop
2020 // Flatten ilt. Hang ilt's "_next" list from the end of
2021 // ilt's '_child' list. Move the ilt's _child up to replace ilt.
2022 IdealLoopTree **cp = &ilt->_child;
2023 while( *cp ) cp = &(*cp)->_next; // Find end of child list
2024 *cp = ilt->_next; // Hang next list at end of child list
2025 *pilt = ilt->_child; // Move child up to replace ilt
2026 ilt->_head = NULL; // Flag as a loop UNIONED into parent
2027 ilt = ilt->_child; // Repeat using new ilt
2028 continue; // do not advance over ilt->_child
2029 }
2030 assert( ilt->_tail == hot_tail, "expected to only find the hot inner loop here" );
2031 phase->set_loop(_head,ilt);
2032 }
2033 pilt = &ilt->_child; // Advance to next
2034 ilt = *pilt;
2035 }
2036
2037 if( _child ) fix_parent( _child, this );
2038 }
2039
2040 //------------------------------beautify_loops---------------------------------
2041 // Split shared headers and insert loop landing pads.
2042 // Insert a LoopNode to replace the RegionNode.
2043 // Return TRUE if loop tree is structurally changed.
2044 bool IdealLoopTree::beautify_loops( PhaseIdealLoop *phase ) {
2045 bool result = false;
2046 // Cache parts in locals for easy
2047 PhaseIterGVN &igvn = phase->_igvn;
2048
2049 igvn.hash_delete(_head); // Yank from hash before hacking edges
2050
2051 // Check for multiple fall-in paths. Peel off a landing pad if need be.
2052 int fall_in_cnt = 0;
2053 for( uint i = 1; i < _head->req(); i++ )
2054 if( !phase->is_member( this, _head->in(i) ) )
2055 fall_in_cnt++;
2056 assert( fall_in_cnt, "at least 1 fall-in path" );
2057 if( fall_in_cnt > 1 ) // Need a loop landing pad to merge fall-ins
2058 split_fall_in( phase, fall_in_cnt );
2059
2060 // Swap inputs to the _head and all Phis to move the fall-in edge to
2061 // the left.
2062 fall_in_cnt = 1;
2063 while( phase->is_member( this, _head->in(fall_in_cnt) ) )
2064 fall_in_cnt++;
2065 if( fall_in_cnt > 1 ) {
2066 // Since I am just swapping inputs I do not need to update def-use info
2067 Node *tmp = _head->in(1);
2068 igvn.rehash_node_delayed(_head);
2069 _head->set_req( 1, _head->in(fall_in_cnt) );
2070 _head->set_req( fall_in_cnt, tmp );
2071 // Swap also all Phis
2072 for (DUIterator_Fast imax, i = _head->fast_outs(imax); i < imax; i++) {
2073 Node* phi = _head->fast_out(i);
2074 if( phi->is_Phi() ) {
2075 igvn.rehash_node_delayed(phi); // Yank from hash before hacking edges
2076 tmp = phi->in(1);
2077 phi->set_req( 1, phi->in(fall_in_cnt) );
2078 phi->set_req( fall_in_cnt, tmp );
2079 }
2080 }
2081 }
2082 assert( !phase->is_member( this, _head->in(1) ), "left edge is fall-in" );
2083 assert( phase->is_member( this, _head->in(2) ), "right edge is loop" );
2084
2085 // If I am a shared header (multiple backedges), peel off the many
2086 // backedges into a private merge point and use the merge point as
2087 // the one true backedge.
2088 if( _head->req() > 3 ) {
2089 // Merge the many backedges into a single backedge but leave
2090 // the hottest backedge as separate edge for the following peel.
2091 merge_many_backedges( phase );
2092 result = true;
2093 }
2094
2095 // If I have one hot backedge, peel off myself loop.
2096 // I better be the outermost loop.
2097 if (_head->req() > 3 && !_irreducible) {
2098 split_outer_loop( phase );
2099 result = true;
2100
2101 } else if (!_head->is_Loop() && !_irreducible) {
2102 // Make a new LoopNode to replace the old loop head
2103 Node *l = new LoopNode( _head->in(1), _head->in(2) );
2104 l = igvn.register_new_node_with_optimizer(l, _head);
2105 phase->set_created_loop_node();
2106 // Go ahead and replace _head
2107 phase->_igvn.replace_node( _head, l );
2108 _head = l;
2109 phase->set_loop(_head, this);
2110 }
2111
2112 // Now recursively beautify nested loops
2113 if( _child ) result |= _child->beautify_loops( phase );
2114 if( _next ) result |= _next ->beautify_loops( phase );
2115 return result;
2116 }
2117
2118 //------------------------------allpaths_check_safepts----------------------------
2119 // Allpaths backwards scan from loop tail, terminating each path at first safepoint
2120 // encountered. Helper for check_safepts.
2121 void IdealLoopTree::allpaths_check_safepts(VectorSet &visited, Node_List &stack) {
2122 assert(stack.size() == 0, "empty stack");
2123 stack.push(_tail);
2124 visited.Clear();
2125 visited.set(_tail->_idx);
2126 while (stack.size() > 0) {
2127 Node* n = stack.pop();
2128 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
2129 // Terminate this path
2130 } else if (n->Opcode() == Op_SafePoint) {
2131 if (_phase->get_loop(n) != this) {
2132 if (_required_safept == NULL) _required_safept = new Node_List();
2133 _required_safept->push(n); // save the one closest to the tail
2134 }
2135 // Terminate this path
2136 } else {
2137 uint start = n->is_Region() ? 1 : 0;
2138 uint end = n->is_Region() && !n->is_Loop() ? n->req() : start + 1;
2139 for (uint i = start; i < end; i++) {
2140 Node* in = n->in(i);
2141 assert(in->is_CFG(), "must be");
2142 if (!visited.test_set(in->_idx) && is_member(_phase->get_loop(in))) {
2143 stack.push(in);
2144 }
2145 }
2146 }
2147 }
2148 }
2149
2150 //------------------------------check_safepts----------------------------
2151 // Given dominators, try to find loops with calls that must always be
2152 // executed (call dominates loop tail). These loops do not need non-call
2153 // safepoints (ncsfpt).
2154 //
2155 // A complication is that a safepoint in a inner loop may be needed
2156 // by an outer loop. In the following, the inner loop sees it has a
2157 // call (block 3) on every path from the head (block 2) to the
2158 // backedge (arc 3->2). So it deletes the ncsfpt (non-call safepoint)
2159 // in block 2, _but_ this leaves the outer loop without a safepoint.
2160 //
2161 // entry 0
2162 // |
2163 // v
2164 // outer 1,2 +->1
2165 // | |
2166 // | v
2167 // | 2<---+ ncsfpt in 2
2168 // |_/|\ |
2169 // | v |
2170 // inner 2,3 / 3 | call in 3
2171 // / | |
2172 // v +--+
2173 // exit 4
2174 //
2175 //
2176 // This method creates a list (_required_safept) of ncsfpt nodes that must
2177 // be protected is created for each loop. When a ncsfpt maybe deleted, it
2178 // is first looked for in the lists for the outer loops of the current loop.
2179 //
2180 // The insights into the problem:
2181 // A) counted loops are okay
2182 // B) innermost loops are okay (only an inner loop can delete
2183 // a ncsfpt needed by an outer loop)
2184 // C) a loop is immune from an inner loop deleting a safepoint
2185 // if the loop has a call on the idom-path
2186 // D) a loop is also immune if it has a ncsfpt (non-call safepoint) on the
2187 // idom-path that is not in a nested loop
2188 // E) otherwise, an ncsfpt on the idom-path that is nested in an inner
2189 // loop needs to be prevented from deletion by an inner loop
2190 //
2191 // There are two analyses:
2192 // 1) The first, and cheaper one, scans the loop body from
2193 // tail to head following the idom (immediate dominator)
2194 // chain, looking for the cases (C,D,E) above.
2195 // Since inner loops are scanned before outer loops, there is summary
2196 // information about inner loops. Inner loops can be skipped over
2197 // when the tail of an inner loop is encountered.
2198 //
2199 // 2) The second, invoked if the first fails to find a call or ncsfpt on
2200 // the idom path (which is rare), scans all predecessor control paths
2201 // from the tail to the head, terminating a path when a call or sfpt
2202 // is encountered, to find the ncsfpt's that are closest to the tail.
2203 //
2204 void IdealLoopTree::check_safepts(VectorSet &visited, Node_List &stack) {
2205 // Bottom up traversal
2206 IdealLoopTree* ch = _child;
2207 if (_child) _child->check_safepts(visited, stack);
2208 if (_next) _next ->check_safepts(visited, stack);
2209
2210 if (!_head->is_CountedLoop() && !_has_sfpt && _parent != NULL && !_irreducible) {
2211 bool has_call = false; // call on dom-path
2212 bool has_local_ncsfpt = false; // ncsfpt on dom-path at this loop depth
2213 Node* nonlocal_ncsfpt = NULL; // ncsfpt on dom-path at a deeper depth
2214 // Scan the dom-path nodes from tail to head
2215 for (Node* n = tail(); n != _head; n = _phase->idom(n)) {
2216 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
2217 has_call = true;
2218 _has_sfpt = 1; // Then no need for a safept!
2219 break;
2220 } else if (n->Opcode() == Op_SafePoint) {
2221 if (_phase->get_loop(n) == this) {
2222 has_local_ncsfpt = true;
2223 break;
2224 }
2225 if (nonlocal_ncsfpt == NULL) {
2226 nonlocal_ncsfpt = n; // save the one closest to the tail
2227 }
2228 } else {
2229 IdealLoopTree* nlpt = _phase->get_loop(n);
2230 if (this != nlpt) {
2231 // If at an inner loop tail, see if the inner loop has already
2232 // recorded seeing a call on the dom-path (and stop.) If not,
2233 // jump to the head of the inner loop.
2234 assert(is_member(nlpt), "nested loop");
2235 Node* tail = nlpt->_tail;
2236 if (tail->in(0)->is_If()) tail = tail->in(0);
2237 if (n == tail) {
2238 // If inner loop has call on dom-path, so does outer loop
2239 if (nlpt->_has_sfpt) {
2240 has_call = true;
2241 _has_sfpt = 1;
2242 break;
2243 }
2244 // Skip to head of inner loop
2245 assert(_phase->is_dominator(_head, nlpt->_head), "inner head dominated by outer head");
2246 n = nlpt->_head;
2247 }
2248 }
2249 }
2250 }
2251 // Record safept's that this loop needs preserved when an
2252 // inner loop attempts to delete it's safepoints.
2253 if (_child != NULL && !has_call && !has_local_ncsfpt) {
2254 if (nonlocal_ncsfpt != NULL) {
2255 if (_required_safept == NULL) _required_safept = new Node_List();
2256 _required_safept->push(nonlocal_ncsfpt);
2257 } else {
2258 // Failed to find a suitable safept on the dom-path. Now use
2259 // an all paths walk from tail to head, looking for safepoints to preserve.
2260 allpaths_check_safepts(visited, stack);
2261 }
2262 }
2263 }
2264 }
2265
2266 //---------------------------is_deleteable_safept----------------------------
2267 // Is safept not required by an outer loop?
2268 bool PhaseIdealLoop::is_deleteable_safept(Node* sfpt) {
2269 assert(sfpt->Opcode() == Op_SafePoint, "");
2270 IdealLoopTree* lp = get_loop(sfpt)->_parent;
2271 while (lp != NULL) {
2272 Node_List* sfpts = lp->_required_safept;
2273 if (sfpts != NULL) {
2274 for (uint i = 0; i < sfpts->size(); i++) {
2275 if (sfpt == sfpts->at(i))
2276 return false;
2277 }
2278 }
2279 lp = lp->_parent;
2280 }
2281 return true;
2282 }
2283
2284 //---------------------------replace_parallel_iv-------------------------------
2285 // Replace parallel induction variable (parallel to trip counter)
2286 void PhaseIdealLoop::replace_parallel_iv(IdealLoopTree *loop) {
2287 assert(loop->_head->is_CountedLoop(), "");
2288 CountedLoopNode *cl = loop->_head->as_CountedLoop();
2289 if (!cl->is_valid_counted_loop())
2290 return; // skip malformed counted loop
2291 Node *incr = cl->incr();
2292 if (incr == NULL)
2293 return; // Dead loop?
2294 Node *init = cl->init_trip();
2295 Node *phi = cl->phi();
2296 int stride_con = cl->stride_con();
2297
2298 // Visit all children, looking for Phis
2299 for (DUIterator i = cl->outs(); cl->has_out(i); i++) {
2300 Node *out = cl->out(i);
2301 // Look for other phis (secondary IVs). Skip dead ones
2302 if (!out->is_Phi() || out == phi || !has_node(out))
2303 continue;
2304 PhiNode* phi2 = out->as_Phi();
2305 Node *incr2 = phi2->in( LoopNode::LoopBackControl );
2306 // Look for induction variables of the form: X += constant
2307 if (phi2->region() != loop->_head ||
2308 incr2->req() != 3 ||
2309 incr2->in(1) != phi2 ||
2310 incr2 == incr ||
2311 incr2->Opcode() != Op_AddI ||
2312 !incr2->in(2)->is_Con())
2313 continue;
2314
2315 // Check for parallel induction variable (parallel to trip counter)
2316 // via an affine function. In particular, count-down loops with
2317 // count-up array indices are common. We only RCE references off
2318 // the trip-counter, so we need to convert all these to trip-counter
2319 // expressions.
2320 Node *init2 = phi2->in( LoopNode::EntryControl );
2321 int stride_con2 = incr2->in(2)->get_int();
2322
2323 // The ratio of the two strides cannot be represented as an int
2324 // if stride_con2 is min_int and stride_con is -1.
2325 if (stride_con2 == min_jint && stride_con == -1) {
2326 continue;
2327 }
2328
2329 // The general case here gets a little tricky. We want to find the
2330 // GCD of all possible parallel IV's and make a new IV using this
2331 // GCD for the loop. Then all possible IVs are simple multiples of
2332 // the GCD. In practice, this will cover very few extra loops.
2333 // Instead we require 'stride_con2' to be a multiple of 'stride_con',
2334 // where +/-1 is the common case, but other integer multiples are
2335 // also easy to handle.
2336 int ratio_con = stride_con2/stride_con;
2337
2338 if ((ratio_con * stride_con) == stride_con2) { // Check for exact
2339 #ifndef PRODUCT
2340 if (TraceLoopOpts) {
2341 tty->print("Parallel IV: %d ", phi2->_idx);
2342 loop->dump_head();
2343 }
2344 #endif
2345 // Convert to using the trip counter. The parallel induction
2346 // variable differs from the trip counter by a loop-invariant
2347 // amount, the difference between their respective initial values.
2348 // It is scaled by the 'ratio_con'.
2349 Node* ratio = _igvn.intcon(ratio_con);
2350 set_ctrl(ratio, C->root());
2351 Node* ratio_init = new MulINode(init, ratio);
2352 _igvn.register_new_node_with_optimizer(ratio_init, init);
2353 set_early_ctrl(ratio_init);
2354 Node* diff = new SubINode(init2, ratio_init);
2355 _igvn.register_new_node_with_optimizer(diff, init2);
2356 set_early_ctrl(diff);
2357 Node* ratio_idx = new MulINode(phi, ratio);
2358 _igvn.register_new_node_with_optimizer(ratio_idx, phi);
2359 set_ctrl(ratio_idx, cl);
2360 Node* add = new AddINode(ratio_idx, diff);
2361 _igvn.register_new_node_with_optimizer(add);
2362 set_ctrl(add, cl);
2363 _igvn.replace_node( phi2, add );
2364 // Sometimes an induction variable is unused
2365 if (add->outcnt() == 0) {
2366 _igvn.remove_dead_node(add);
2367 }
2368 --i; // deleted this phi; rescan starting with next position
2369 continue;
2370 }
2371 }
2372 }
2373
2374 void IdealLoopTree::remove_safepoints(PhaseIdealLoop* phase, bool keep_one) {
2375 Node* keep = NULL;
2376 if (keep_one) {
2377 // Look for a safepoint on the idom-path.
2378 for (Node* i = tail(); i != _head; i = phase->idom(i)) {
2379 if (i->Opcode() == Op_SafePoint && phase->get_loop(i) == this) {
2380 keep = i;
2381 break; // Found one
2382 }
2383 }
2384 }
2385
2386 // Don't remove any safepoints if it is requested to keep a single safepoint and
2387 // no safepoint was found on idom-path. It is not safe to remove any safepoint
2388 // in this case since there's no safepoint dominating all paths in the loop body.
2389 bool prune = !keep_one || keep != NULL;
2390
2391 // Delete other safepoints in this loop.
2392 Node_List* sfpts = _safepts;
2393 if (prune && sfpts != NULL) {
2394 assert(keep == NULL || keep->Opcode() == Op_SafePoint, "not safepoint");
2395 for (uint i = 0; i < sfpts->size(); i++) {
2396 Node* n = sfpts->at(i);
2397 assert(phase->get_loop(n) == this, "");
2398 if (n != keep && phase->is_deleteable_safept(n)) {
2399 phase->lazy_replace(n, n->in(TypeFunc::Control));
2400 }
2401 }
2402 }
2403 }
2404
2405 //------------------------------counted_loop-----------------------------------
2406 // Convert to counted loops where possible
2407 void IdealLoopTree::counted_loop( PhaseIdealLoop *phase ) {
2408
2409 // For grins, set the inner-loop flag here
2410 if (!_child) {
2411 if (_head->is_Loop()) _head->as_Loop()->set_inner_loop();
2412 }
2413
2414 IdealLoopTree* loop = this;
2415 if (_head->is_CountedLoop() ||
2416 phase->is_counted_loop(_head, loop)) {
2417
2418 if (LoopStripMiningIter == 0 || (LoopStripMiningIter > 1 && _child == NULL)) {
2419 // Indicate we do not need a safepoint here
2420 _has_sfpt = 1;
2421 }
2422
2423 // Remove safepoints
2424 bool keep_one_sfpt = !(_has_call || _has_sfpt);
2425 remove_safepoints(phase, keep_one_sfpt);
2426
2427 // Look for induction variables
2428 phase->replace_parallel_iv(this);
2429
2430 } else if (_parent != NULL && !_irreducible) {
2431 // Not a counted loop. Keep one safepoint.
2432 bool keep_one_sfpt = true;
2433 remove_safepoints(phase, keep_one_sfpt);
2434 }
2435
2436 // Recursively
2437 assert(loop->_child != this || (loop->_head->as_Loop()->is_OuterStripMinedLoop() && _head->as_CountedLoop()->is_strip_mined()), "what kind of loop was added?");
2438 assert(loop->_child != this || (loop->_child->_child == NULL && loop->_child->_next == NULL), "would miss some loops");
2439 if (loop->_child && loop->_child != this) loop->_child->counted_loop(phase);
2440 if (loop->_next) loop->_next ->counted_loop(phase);
2441 }
2442
2443
2444 // The Estimated Loop Clone Size:
2445 // CloneFactor * (~112% * BodySize + BC) + CC + FanOutTerm,
2446 // where BC and CC are totally ad-hoc/magic "body" and "clone" constants,
2447 // respectively, used to ensure that the node usage estimates made are on the
2448 // safe side, for the most part. The FanOutTerm is an attempt to estimate the
2449 // possible additional/excessive nodes generated due to data and control flow
2450 // merging, for edges reaching outside the loop.
2451 uint IdealLoopTree::est_loop_clone_sz(uint factor) const {
2452
2453 precond(0 < factor && factor < 16);
2454
2455 uint const bc = 13;
2456 uint const cc = 17;
2457 uint const sz = _body.size() + (_body.size() + 7) / 8;
2458 uint estimate = factor * (sz + bc) + cc;
2459
2460 assert((estimate - cc) / factor == sz + bc, "overflow");
2461
2462 return estimate + est_loop_flow_merge_sz();
2463 }
2464
2465 // The Estimated Loop (full-) Unroll Size:
2466 // UnrollFactor * (~106% * BodySize) + CC + FanOutTerm,
2467 // where CC is a (totally) ad-hoc/magic "clone" constant, used to ensure that
2468 // node usage estimates made are on the safe side, for the most part. This is
2469 // a "light" version of the loop clone size calculation (above), based on the
2470 // assumption that most of the loop-construct overhead will be unraveled when
2471 // (fully) unrolled. Defined for unroll factors larger or equal to one (>=1),
2472 // including an overflow check and returning UINT_MAX in case of an overflow.
2473 uint IdealLoopTree::est_loop_unroll_sz(uint factor) const {
2474
2475 precond(factor > 0);
2476
2477 // Take into account that after unroll conjoined heads and tails will fold.
2478 uint const b0 = _body.size() - EMPTY_LOOP_SIZE;
2479 uint const cc = 7;
2480 uint const sz = b0 + (b0 + 15) / 16;
2481 uint estimate = factor * sz + cc;
2482
2483 if ((estimate - cc) / factor != sz) {
2484 return UINT_MAX;
2485 }
2486
2487 return estimate + est_loop_flow_merge_sz();
2488 }
2489
2490 // Estimate the growth effect (in nodes) of merging control and data flow when
2491 // cloning a loop body, based on the amount of control and data flow reaching
2492 // outside of the (current) loop body.
2493 uint IdealLoopTree::est_loop_flow_merge_sz() const {
2494
2495 uint ctrl_edge_out_cnt = 0;
2496 uint data_edge_out_cnt = 0;
2497
2498 for (uint i = 0; i < _body.size(); i++) {
2499 Node* node = _body.at(i);
2500 uint outcnt = node->outcnt();
2501
2502 for (uint k = 0; k < outcnt; k++) {
2503 Node* out = node->raw_out(k);
2504
2505 if (out->is_CFG()) {
2506 if (!is_member(_phase->get_loop(out))) {
2507 ctrl_edge_out_cnt++;
2508 }
2509 } else {
2510 Node* ctrl = _phase->get_ctrl(out);
2511 assert(ctrl->is_CFG(), "must be");
2512 if (!is_member(_phase->get_loop(ctrl))) {
2513 data_edge_out_cnt++;
2514 }
2515 }
2516 }
2517 }
2518 // Use data and control count (x2.0) in estimate iff both are > 0. This is
2519 // a rather pessimistic estimate for the most part, in particular for some
2520 // complex loops, but still not enough to capture all loops.
2521 if (ctrl_edge_out_cnt > 0 && data_edge_out_cnt > 0) {
2522 return 2 * (ctrl_edge_out_cnt + data_edge_out_cnt);
2523 }
2524 return 0;
2525 }
2526
2527 #ifndef PRODUCT
2528 //------------------------------dump_head--------------------------------------
2529 // Dump 1 liner for loop header info
2530 void IdealLoopTree::dump_head() const {
2531 tty->sp(2 * _nest);
2532 tty->print("Loop: N%d/N%d ", _head->_idx, _tail->_idx);
2533 if (_irreducible) tty->print(" IRREDUCIBLE");
2534 Node* entry = _head->is_Loop() ? _head->as_Loop()->skip_strip_mined(-1)->in(LoopNode::EntryControl) : _head->in(LoopNode::EntryControl);
2535 Node* predicate = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
2536 if (predicate != NULL ) {
2537 tty->print(" limit_check");
2538 entry = PhaseIdealLoop::skip_loop_predicates(entry);
2539 }
2540 if (UseLoopPredicate) {
2541 entry = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
2542 if (entry != NULL) {
2543 tty->print(" predicated");
2544 entry = PhaseIdealLoop::skip_loop_predicates(entry);
2545 }
2546 }
2547 if (UseProfiledLoopPredicate) {
2548 entry = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_profile_predicate);
2549 if (entry != NULL) {
2550 tty->print(" profile_predicated");
2551 }
2552 }
2553 if (_head->is_CountedLoop()) {
2554 CountedLoopNode *cl = _head->as_CountedLoop();
2555 tty->print(" counted");
2556
2557 Node* init_n = cl->init_trip();
2558 if (init_n != NULL && init_n->is_Con())
2559 tty->print(" [%d,", cl->init_trip()->get_int());
2560 else
2561 tty->print(" [int,");
2562 Node* limit_n = cl->limit();
2563 if (limit_n != NULL && limit_n->is_Con())
2564 tty->print("%d),", cl->limit()->get_int());
2565 else
2566 tty->print("int),");
2567 int stride_con = cl->stride_con();
2568 if (stride_con > 0) tty->print("+");
2569 tty->print("%d", stride_con);
2570
2571 tty->print(" (%0.f iters) ", cl->profile_trip_cnt());
2572
2573 if (cl->is_pre_loop ()) tty->print(" pre" );
2574 if (cl->is_main_loop()) tty->print(" main");
2575 if (cl->is_post_loop()) tty->print(" post");
2576 if (cl->is_vectorized_loop()) tty->print(" vector");
2577 if (cl->range_checks_present()) tty->print(" rc ");
2578 if (cl->is_multiversioned()) tty->print(" multi ");
2579 }
2580 if (_has_call) tty->print(" has_call");
2581 if (_has_sfpt) tty->print(" has_sfpt");
2582 if (_rce_candidate) tty->print(" rce");
2583 if (_safepts != NULL && _safepts->size() > 0) {
2584 tty->print(" sfpts={"); _safepts->dump_simple(); tty->print(" }");
2585 }
2586 if (_required_safept != NULL && _required_safept->size() > 0) {
2587 tty->print(" req={"); _required_safept->dump_simple(); tty->print(" }");
2588 }
2589 if (Verbose) {
2590 tty->print(" body={"); _body.dump_simple(); tty->print(" }");
2591 }
2592 if (_head->is_Loop() && _head->as_Loop()->is_strip_mined()) {
2593 tty->print(" strip_mined");
2594 }
2595 tty->cr();
2596 }
2597
2598 //------------------------------dump-------------------------------------------
2599 // Dump loops by loop tree
2600 void IdealLoopTree::dump() const {
2601 dump_head();
2602 if (_child) _child->dump();
2603 if (_next) _next ->dump();
2604 }
2605
2606 #endif
2607
2608 static void log_loop_tree(IdealLoopTree* root, IdealLoopTree* loop, CompileLog* log) {
2609 if (loop == root) {
2610 if (loop->_child != NULL) {
2611 log->begin_head("loop_tree");
2612 log->end_head();
2613 if( loop->_child ) log_loop_tree(root, loop->_child, log);
2614 log->tail("loop_tree");
2615 assert(loop->_next == NULL, "what?");
2616 }
2617 } else {
2618 Node* head = loop->_head;
2619 log->begin_head("loop");
2620 log->print(" idx='%d' ", head->_idx);
2621 if (loop->_irreducible) log->print("irreducible='1' ");
2622 if (head->is_Loop()) {
2623 if (head->as_Loop()->is_inner_loop()) log->print("inner_loop='1' ");
2624 if (head->as_Loop()->is_partial_peel_loop()) log->print("partial_peel_loop='1' ");
2625 }
2626 if (head->is_CountedLoop()) {
2627 CountedLoopNode* cl = head->as_CountedLoop();
2628 if (cl->is_pre_loop()) log->print("pre_loop='%d' ", cl->main_idx());
2629 if (cl->is_main_loop()) log->print("main_loop='%d' ", cl->_idx);
2630 if (cl->is_post_loop()) log->print("post_loop='%d' ", cl->main_idx());
2631 }
2632 log->end_head();
2633 if( loop->_child ) log_loop_tree(root, loop->_child, log);
2634 log->tail("loop");
2635 if( loop->_next ) log_loop_tree(root, loop->_next, log);
2636 }
2637 }
2638
2639 //---------------------collect_potentially_useful_predicates-----------------------
2640 // Helper function to collect potentially useful predicates to prevent them from
2641 // being eliminated by PhaseIdealLoop::eliminate_useless_predicates
2642 void PhaseIdealLoop::collect_potentially_useful_predicates(
2643 IdealLoopTree * loop, Unique_Node_List &useful_predicates) {
2644 if (loop->_child) { // child
2645 collect_potentially_useful_predicates(loop->_child, useful_predicates);
2646 }
2647
2648 // self (only loops that we can apply loop predication may use their predicates)
2649 if (loop->_head->is_Loop() &&
2650 !loop->_irreducible &&
2651 !loop->tail()->is_top()) {
2652 LoopNode* lpn = loop->_head->as_Loop();
2653 Node* entry = lpn->in(LoopNode::EntryControl);
2654 Node* predicate_proj = find_predicate(entry); // loop_limit_check first
2655 if (predicate_proj != NULL ) { // right pattern that can be used by loop predication
2656 assert(entry->in(0)->in(1)->in(1)->Opcode() == Op_Opaque1, "must be");
2657 useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one
2658 entry = skip_loop_predicates(entry);
2659 }
2660 predicate_proj = find_predicate(entry); // Predicate
2661 if (predicate_proj != NULL ) {
2662 useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one
2663 entry = skip_loop_predicates(entry);
2664 }
2665 if (UseProfiledLoopPredicate) {
2666 predicate_proj = find_predicate(entry); // Predicate
2667 if (predicate_proj != NULL ) {
2668 useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one
2669 }
2670 }
2671 }
2672
2673 if (loop->_next) { // sibling
2674 collect_potentially_useful_predicates(loop->_next, useful_predicates);
2675 }
2676 }
2677
2678 //------------------------eliminate_useless_predicates-----------------------------
2679 // Eliminate all inserted predicates if they could not be used by loop predication.
2680 // Note: it will also eliminates loop limits check predicate since it also uses
2681 // Opaque1 node (see Parse::add_predicate()).
2682 void PhaseIdealLoop::eliminate_useless_predicates() {
2683 if (C->predicate_count() == 0)
2684 return; // no predicate left
2685
2686 Unique_Node_List useful_predicates; // to store useful predicates
2687 if (C->has_loops()) {
2688 collect_potentially_useful_predicates(_ltree_root->_child, useful_predicates);
2689 }
2690
2691 for (int i = C->predicate_count(); i > 0; i--) {
2692 Node * n = C->predicate_opaque1_node(i-1);
2693 assert(n->Opcode() == Op_Opaque1, "must be");
2694 if (!useful_predicates.member(n)) { // not in the useful list
2695 _igvn.replace_node(n, n->in(1));
2696 }
2697 }
2698 }
2699
2700 //------------------------process_expensive_nodes-----------------------------
2701 // Expensive nodes have their control input set to prevent the GVN
2702 // from commoning them and as a result forcing the resulting node to
2703 // be in a more frequent path. Use CFG information here, to change the
2704 // control inputs so that some expensive nodes can be commoned while
2705 // not executed more frequently.
2706 bool PhaseIdealLoop::process_expensive_nodes() {
2707 assert(OptimizeExpensiveOps, "optimization off?");
2708
2709 // Sort nodes to bring similar nodes together
2710 C->sort_expensive_nodes();
2711
2712 bool progress = false;
2713
2714 for (int i = 0; i < C->expensive_count(); ) {
2715 Node* n = C->expensive_node(i);
2716 int start = i;
2717 // Find nodes similar to n
2718 i++;
2719 for (; i < C->expensive_count() && Compile::cmp_expensive_nodes(n, C->expensive_node(i)) == 0; i++);
2720 int end = i;
2721 // And compare them two by two
2722 for (int j = start; j < end; j++) {
2723 Node* n1 = C->expensive_node(j);
2724 if (is_node_unreachable(n1)) {
2725 continue;
2726 }
2727 for (int k = j+1; k < end; k++) {
2728 Node* n2 = C->expensive_node(k);
2729 if (is_node_unreachable(n2)) {
2730 continue;
2731 }
2732
2733 assert(n1 != n2, "should be pair of nodes");
2734
2735 Node* c1 = n1->in(0);
2736 Node* c2 = n2->in(0);
2737
2738 Node* parent_c1 = c1;
2739 Node* parent_c2 = c2;
2740
2741 // The call to get_early_ctrl_for_expensive() moves the
2742 // expensive nodes up but stops at loops that are in a if
2743 // branch. See whether we can exit the loop and move above the
2744 // If.
2745 if (c1->is_Loop()) {
2746 parent_c1 = c1->in(1);
2747 }
2748 if (c2->is_Loop()) {
2749 parent_c2 = c2->in(1);
2750 }
2751
2752 if (parent_c1 == parent_c2) {
2753 _igvn._worklist.push(n1);
2754 _igvn._worklist.push(n2);
2755 continue;
2756 }
2757
2758 // Look for identical expensive node up the dominator chain.
2759 if (is_dominator(c1, c2)) {
2760 c2 = c1;
2761 } else if (is_dominator(c2, c1)) {
2762 c1 = c2;
2763 } else if (parent_c1->is_Proj() && parent_c1->in(0)->is_If() &&
2764 parent_c2->is_Proj() && parent_c1->in(0) == parent_c2->in(0)) {
2765 // Both branches have the same expensive node so move it up
2766 // before the if.
2767 c1 = c2 = idom(parent_c1->in(0));
2768 }
2769 // Do the actual moves
2770 if (n1->in(0) != c1) {
2771 _igvn.hash_delete(n1);
2772 n1->set_req(0, c1);
2773 _igvn.hash_insert(n1);
2774 _igvn._worklist.push(n1);
2775 progress = true;
2776 }
2777 if (n2->in(0) != c2) {
2778 _igvn.hash_delete(n2);
2779 n2->set_req(0, c2);
2780 _igvn.hash_insert(n2);
2781 _igvn._worklist.push(n2);
2782 progress = true;
2783 }
2784 }
2785 }
2786 }
2787
2788 return progress;
2789 }
2790
2791
2792 //=============================================================================
2793 //----------------------------build_and_optimize-------------------------------
2794 // Create a PhaseLoop. Build the ideal Loop tree. Map each Ideal Node to
2795 // its corresponding LoopNode. If 'optimize' is true, do some loop cleanups.
2796 void PhaseIdealLoop::build_and_optimize(LoopOptsMode mode) {
2797 bool do_split_ifs = (mode == LoopOptsDefault);
2798 bool skip_loop_opts = (mode == LoopOptsNone);
2799
2800 int old_progress = C->major_progress();
2801 uint orig_worklist_size = _igvn._worklist.size();
2802
2803 // Reset major-progress flag for the driver's heuristics
2804 C->clear_major_progress();
2805
2806 #ifndef PRODUCT
2807 // Capture for later assert
2808 uint unique = C->unique();
2809 _loop_invokes++;
2810 _loop_work += unique;
2811 #endif
2812
2813 // True if the method has at least 1 irreducible loop
2814 _has_irreducible_loops = false;
2815
2816 _created_loop_node = false;
2817
2818 Arena *a = Thread::current()->resource_area();
2819 VectorSet visited(a);
2820 // Pre-grow the mapping from Nodes to IdealLoopTrees.
2821 _nodes.map(C->unique(), NULL);
2822 memset(_nodes.adr(), 0, wordSize * C->unique());
2823
2824 // Pre-build the top-level outermost loop tree entry
2825 _ltree_root = new IdealLoopTree( this, C->root(), C->root() );
2826 // Do not need a safepoint at the top level
2827 _ltree_root->_has_sfpt = 1;
2828
2829 // Initialize Dominators.
2830 // Checked in clone_loop_predicate() during beautify_loops().
2831 _idom_size = 0;
2832 _idom = NULL;
2833 _dom_depth = NULL;
2834 _dom_stk = NULL;
2835
2836 // Empty pre-order array
2837 allocate_preorders();
2838
2839 // Build a loop tree on the fly. Build a mapping from CFG nodes to
2840 // IdealLoopTree entries. Data nodes are NOT walked.
2841 build_loop_tree();
2842 // Check for bailout, and return
2843 if (C->failing()) {
2844 return;
2845 }
2846
2847 // No loops after all
2848 if( !_ltree_root->_child && !_verify_only ) C->set_has_loops(false);
2849
2850 // There should always be an outer loop containing the Root and Return nodes.
2851 // If not, we have a degenerate empty program. Bail out in this case.
2852 if (!has_node(C->root())) {
2853 if (!_verify_only) {
2854 C->clear_major_progress();
2855 C->record_method_not_compilable("empty program detected during loop optimization");
2856 }
2857 return;
2858 }
2859
2860 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2861 // Nothing to do, so get out
2862 bool stop_early = !C->has_loops() && !skip_loop_opts && !do_split_ifs && !_verify_me && !_verify_only &&
2863 !bs->is_gc_specific_loop_opts_pass(mode);
2864 bool do_expensive_nodes = C->should_optimize_expensive_nodes(_igvn);
2865 bool strip_mined_loops_expanded = bs->strip_mined_loops_expanded(mode);
2866 if (stop_early && !do_expensive_nodes) {
2867 _igvn.optimize(); // Cleanup NeverBranches
2868 return;
2869 }
2870
2871 // Set loop nesting depth
2872 _ltree_root->set_nest( 0 );
2873
2874 // Split shared headers and insert loop landing pads.
2875 // Do not bother doing this on the Root loop of course.
2876 if( !_verify_me && !_verify_only && _ltree_root->_child ) {
2877 C->print_method(PHASE_BEFORE_BEAUTIFY_LOOPS, 3);
2878 if( _ltree_root->_child->beautify_loops( this ) ) {
2879 // Re-build loop tree!
2880 _ltree_root->_child = NULL;
2881 _nodes.clear();
2882 reallocate_preorders();
2883 build_loop_tree();
2884 // Check for bailout, and return
2885 if (C->failing()) {
2886 return;
2887 }
2888 // Reset loop nesting depth
2889 _ltree_root->set_nest( 0 );
2890
2891 C->print_method(PHASE_AFTER_BEAUTIFY_LOOPS, 3);
2892 }
2893 }
2894
2895 // Build Dominators for elision of NULL checks & loop finding.
2896 // Since nodes do not have a slot for immediate dominator, make
2897 // a persistent side array for that info indexed on node->_idx.
2898 _idom_size = C->unique();
2899 _idom = NEW_RESOURCE_ARRAY( Node*, _idom_size );
2900 _dom_depth = NEW_RESOURCE_ARRAY( uint, _idom_size );
2901 _dom_stk = NULL; // Allocated on demand in recompute_dom_depth
2902 memset( _dom_depth, 0, _idom_size * sizeof(uint) );
2903
2904 Dominators();
2905
2906 if (!_verify_only) {
2907 // As a side effect, Dominators removed any unreachable CFG paths
2908 // into RegionNodes. It doesn't do this test against Root, so
2909 // we do it here.
2910 for( uint i = 1; i < C->root()->req(); i++ ) {
2911 if( !_nodes[C->root()->in(i)->_idx] ) { // Dead path into Root?
2912 _igvn.delete_input_of(C->root(), i);
2913 i--; // Rerun same iteration on compressed edges
2914 }
2915 }
2916
2917 // Given dominators, try to find inner loops with calls that must
2918 // always be executed (call dominates loop tail). These loops do
2919 // not need a separate safepoint.
2920 Node_List cisstack(a);
2921 _ltree_root->check_safepts(visited, cisstack);
2922 }
2923
2924 // Walk the DATA nodes and place into loops. Find earliest control
2925 // node. For CFG nodes, the _nodes array starts out and remains
2926 // holding the associated IdealLoopTree pointer. For DATA nodes, the
2927 // _nodes array holds the earliest legal controlling CFG node.
2928
2929 // Allocate stack with enough space to avoid frequent realloc
2930 int stack_size = (C->live_nodes() >> 1) + 16; // (live_nodes>>1)+16 from Java2D stats
2931 Node_Stack nstack( a, stack_size );
2932
2933 visited.Clear();
2934 Node_List worklist(a);
2935 // Don't need C->root() on worklist since
2936 // it will be processed among C->top() inputs
2937 worklist.push( C->top() );
2938 visited.set( C->top()->_idx ); // Set C->top() as visited now
2939 build_loop_early( visited, worklist, nstack );
2940
2941 // Given early legal placement, try finding counted loops. This placement
2942 // is good enough to discover most loop invariants.
2943 if (!_verify_me && !_verify_only && !strip_mined_loops_expanded) {
2944 _ltree_root->counted_loop( this );
2945 }
2946
2947 // Find latest loop placement. Find ideal loop placement.
2948 visited.Clear();
2949 init_dom_lca_tags();
2950 // Need C->root() on worklist when processing outs
2951 worklist.push( C->root() );
2952 NOT_PRODUCT( C->verify_graph_edges(); )
2953 worklist.push( C->top() );
2954 build_loop_late( visited, worklist, nstack );
2955
2956 if (_verify_only) {
2957 C->restore_major_progress(old_progress);
2958 assert(C->unique() == unique, "verification mode made Nodes? ? ?");
2959 assert(_igvn._worklist.size() == orig_worklist_size, "shouldn't push anything");
2960 return;
2961 }
2962
2963 // clear out the dead code after build_loop_late
2964 while (_deadlist.size()) {
2965 _igvn.remove_globally_dead_node(_deadlist.pop());
2966 }
2967
2968 if (stop_early) {
2969 assert(do_expensive_nodes, "why are we here?");
2970 if (process_expensive_nodes()) {
2971 // If we made some progress when processing expensive nodes then
2972 // the IGVN may modify the graph in a way that will allow us to
2973 // make some more progress: we need to try processing expensive
2974 // nodes again.
2975 C->set_major_progress();
2976 }
2977 _igvn.optimize();
2978 return;
2979 }
2980
2981 // Some parser-inserted loop predicates could never be used by loop
2982 // predication or they were moved away from loop during some optimizations.
2983 // For example, peeling. Eliminate them before next loop optimizations.
2984 eliminate_useless_predicates();
2985
2986 #ifndef PRODUCT
2987 C->verify_graph_edges();
2988 if (_verify_me) { // Nested verify pass?
2989 // Check to see if the verify mode is broken
2990 assert(C->unique() == unique, "non-optimize mode made Nodes? ? ?");
2991 return;
2992 }
2993 if (VerifyLoopOptimizations) verify();
2994 if (TraceLoopOpts && C->has_loops()) {
2995 _ltree_root->dump();
2996 }
2997 #endif
2998
2999 if (skip_loop_opts) {
3000 // restore major progress flag
3001 C->restore_major_progress(old_progress);
3002
3003 // Cleanup any modified bits
3004 _igvn.optimize();
3005
3006 if (C->log() != NULL) {
3007 log_loop_tree(_ltree_root, _ltree_root, C->log());
3008 }
3009 return;
3010 }
3011
3012 if (bs->optimize_loops(this, mode, visited, nstack, worklist)) {
3013 _igvn.optimize();
3014 if (C->log() != NULL) {
3015 log_loop_tree(_ltree_root, _ltree_root, C->log());
3016 }
3017 return;
3018 }
3019
3020 if (ReassociateInvariants) {
3021 // Reassociate invariants and prep for split_thru_phi
3022 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
3023 IdealLoopTree* lpt = iter.current();
3024 bool is_counted = lpt->is_counted();
3025 if (!is_counted || !lpt->is_innermost()) continue;
3026
3027 // check for vectorized loops, any reassociation of invariants was already done
3028 if (is_counted && lpt->_head->as_CountedLoop()->is_unroll_only()) {
3029 continue;
3030 } else {
3031 AutoNodeBudget node_budget(this);
3032 lpt->reassociate_invariants(this);
3033 }
3034 // Because RCE opportunities can be masked by split_thru_phi,
3035 // look for RCE candidates and inhibit split_thru_phi
3036 // on just their loop-phi's for this pass of loop opts
3037 if (SplitIfBlocks && do_split_ifs) {
3038 AutoNodeBudget node_budget(this, AutoNodeBudget::NO_BUDGET_CHECK);
3039 if (lpt->policy_range_check(this)) {
3040 lpt->_rce_candidate = 1; // = true
3041 }
3042 }
3043 }
3044 }
3045
3046 // Check for aggressive application of split-if and other transforms
3047 // that require basic-block info (like cloning through Phi's)
3048 if( SplitIfBlocks && do_split_ifs ) {
3049 visited.Clear();
3050 split_if_with_blocks( visited, nstack);
3051 NOT_PRODUCT( if( VerifyLoopOptimizations ) verify(); );
3052 }
3053
3054 if (!C->major_progress() && do_expensive_nodes && process_expensive_nodes()) {
3055 C->set_major_progress();
3056 }
3057
3058 // Perform loop predication before iteration splitting
3059 if (C->has_loops() && !C->major_progress() && (C->predicate_count() > 0)) {
3060 _ltree_root->_child->loop_predication(this);
3061 }
3062
3063 if (OptimizeFill && UseLoopPredicate && C->has_loops() && !C->major_progress()) {
3064 if (do_intrinsify_fill()) {
3065 C->set_major_progress();
3066 }
3067 }
3068
3069 // Perform iteration-splitting on inner loops. Split iterations to avoid
3070 // range checks or one-shot null checks.
3071
3072 // If split-if's didn't hack the graph too bad (no CFG changes)
3073 // then do loop opts.
3074 if (C->has_loops() && !C->major_progress()) {
3075 memset( worklist.adr(), 0, worklist.Size()*sizeof(Node*) );
3076 _ltree_root->_child->iteration_split( this, worklist );
3077 // No verify after peeling! GCM has hoisted code out of the loop.
3078 // After peeling, the hoisted code could sink inside the peeled area.
3079 // The peeling code does not try to recompute the best location for
3080 // all the code before the peeled area, so the verify pass will always
3081 // complain about it.
3082 }
3083 // Do verify graph edges in any case
3084 NOT_PRODUCT( C->verify_graph_edges(); );
3085
3086 if (!do_split_ifs) {
3087 // We saw major progress in Split-If to get here. We forced a
3088 // pass with unrolling and not split-if, however more split-if's
3089 // might make progress. If the unrolling didn't make progress
3090 // then the major-progress flag got cleared and we won't try
3091 // another round of Split-If. In particular the ever-common
3092 // instance-of/check-cast pattern requires at least 2 rounds of
3093 // Split-If to clear out.
3094 C->set_major_progress();
3095 }
3096
3097 // Repeat loop optimizations if new loops were seen
3098 if (created_loop_node()) {
3099 C->set_major_progress();
3100 }
3101
3102 // Keep loop predicates and perform optimizations with them
3103 // until no more loop optimizations could be done.
3104 // After that switch predicates off and do more loop optimizations.
3105 if (!C->major_progress() && (C->predicate_count() > 0)) {
3106 C->cleanup_loop_predicates(_igvn);
3107 if (TraceLoopOpts) {
3108 tty->print_cr("PredicatesOff");
3109 }
3110 C->set_major_progress();
3111 }
3112
3113 // Convert scalar to superword operations at the end of all loop opts.
3114 if (UseSuperWord && C->has_loops() && !C->major_progress()) {
3115 // SuperWord transform
3116 SuperWord sw(this);
3117 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
3118 IdealLoopTree* lpt = iter.current();
3119 if (lpt->is_counted()) {
3120 CountedLoopNode *cl = lpt->_head->as_CountedLoop();
3121
3122 if (PostLoopMultiversioning && cl->is_rce_post_loop() && !cl->is_vectorized_loop()) {
3123 // Check that the rce'd post loop is encountered first, multiversion after all
3124 // major main loop optimization are concluded
3125 if (!C->major_progress()) {
3126 IdealLoopTree *lpt_next = lpt->_next;
3127 if (lpt_next && lpt_next->is_counted()) {
3128 CountedLoopNode *cl = lpt_next->_head->as_CountedLoop();
3129 has_range_checks(lpt_next);
3130 if (cl->is_post_loop() && cl->range_checks_present()) {
3131 if (!cl->is_multiversioned()) {
3132 if (multi_version_post_loops(lpt, lpt_next) == false) {
3133 // Cause the rce loop to be optimized away if we fail
3134 cl->mark_is_multiversioned();
3135 cl->set_slp_max_unroll(0);
3136 poison_rce_post_loop(lpt);
3137 }
3138 }
3139 }
3140 }
3141 sw.transform_loop(lpt, true);
3142 }
3143 } else if (cl->is_main_loop()) {
3144 sw.transform_loop(lpt, true);
3145 }
3146 }
3147 }
3148 }
3149
3150 // Cleanup any modified bits
3151 _igvn.optimize();
3152
3153 // disable assert until issue with split_flow_path is resolved (6742111)
3154 // assert(!_has_irreducible_loops || C->parsed_irreducible_loop() || C->is_osr_compilation(),
3155 // "shouldn't introduce irreducible loops");
3156
3157 if (C->log() != NULL) {
3158 log_loop_tree(_ltree_root, _ltree_root, C->log());
3159 }
3160 }
3161
3162 #ifndef PRODUCT
3163 //------------------------------print_statistics-------------------------------
3164 int PhaseIdealLoop::_loop_invokes=0;// Count of PhaseIdealLoop invokes
3165 int PhaseIdealLoop::_loop_work=0; // Sum of PhaseIdealLoop x unique
3166 void PhaseIdealLoop::print_statistics() {
3167 tty->print_cr("PhaseIdealLoop=%d, sum _unique=%d", _loop_invokes, _loop_work);
3168 }
3169
3170 //------------------------------verify-----------------------------------------
3171 // Build a verify-only PhaseIdealLoop, and see that it agrees with me.
3172 static int fail; // debug only, so its multi-thread dont care
3173 void PhaseIdealLoop::verify() const {
3174 int old_progress = C->major_progress();
3175 ResourceMark rm;
3176 PhaseIdealLoop loop_verify( _igvn, this );
3177 VectorSet visited(Thread::current()->resource_area());
3178
3179 fail = 0;
3180 verify_compare( C->root(), &loop_verify, visited );
3181 assert( fail == 0, "verify loops failed" );
3182 // Verify loop structure is the same
3183 _ltree_root->verify_tree(loop_verify._ltree_root, NULL);
3184 // Reset major-progress. It was cleared by creating a verify version of
3185 // PhaseIdealLoop.
3186 C->restore_major_progress(old_progress);
3187 }
3188
3189 //------------------------------verify_compare---------------------------------
3190 // Make sure me and the given PhaseIdealLoop agree on key data structures
3191 void PhaseIdealLoop::verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const {
3192 if( !n ) return;
3193 if( visited.test_set( n->_idx ) ) return;
3194 if( !_nodes[n->_idx] ) { // Unreachable
3195 assert( !loop_verify->_nodes[n->_idx], "both should be unreachable" );
3196 return;
3197 }
3198
3199 uint i;
3200 for( i = 0; i < n->req(); i++ )
3201 verify_compare( n->in(i), loop_verify, visited );
3202
3203 // Check the '_nodes' block/loop structure
3204 i = n->_idx;
3205 if( has_ctrl(n) ) { // We have control; verify has loop or ctrl
3206 if( _nodes[i] != loop_verify->_nodes[i] &&
3207 get_ctrl_no_update(n) != loop_verify->get_ctrl_no_update(n) ) {
3208 tty->print("Mismatched control setting for: ");
3209 n->dump();
3210 if( fail++ > 10 ) return;
3211 Node *c = get_ctrl_no_update(n);
3212 tty->print("We have it as: ");
3213 if( c->in(0) ) c->dump();
3214 else tty->print_cr("N%d",c->_idx);
3215 tty->print("Verify thinks: ");
3216 if( loop_verify->has_ctrl(n) )
3217 loop_verify->get_ctrl_no_update(n)->dump();
3218 else
3219 loop_verify->get_loop_idx(n)->dump();
3220 tty->cr();
3221 }
3222 } else { // We have a loop
3223 IdealLoopTree *us = get_loop_idx(n);
3224 if( loop_verify->has_ctrl(n) ) {
3225 tty->print("Mismatched loop setting for: ");
3226 n->dump();
3227 if( fail++ > 10 ) return;
3228 tty->print("We have it as: ");
3229 us->dump();
3230 tty->print("Verify thinks: ");
3231 loop_verify->get_ctrl_no_update(n)->dump();
3232 tty->cr();
3233 } else if (!C->major_progress()) {
3234 // Loop selection can be messed up if we did a major progress
3235 // operation, like split-if. Do not verify in that case.
3236 IdealLoopTree *them = loop_verify->get_loop_idx(n);
3237 if( us->_head != them->_head || us->_tail != them->_tail ) {
3238 tty->print("Unequals loops for: ");
3239 n->dump();
3240 if( fail++ > 10 ) return;
3241 tty->print("We have it as: ");
3242 us->dump();
3243 tty->print("Verify thinks: ");
3244 them->dump();
3245 tty->cr();
3246 }
3247 }
3248 }
3249
3250 // Check for immediate dominators being equal
3251 if( i >= _idom_size ) {
3252 if( !n->is_CFG() ) return;
3253 tty->print("CFG Node with no idom: ");
3254 n->dump();
3255 return;
3256 }
3257 if( !n->is_CFG() ) return;
3258 if( n == C->root() ) return; // No IDOM here
3259
3260 assert(n->_idx == i, "sanity");
3261 Node *id = idom_no_update(n);
3262 if( id != loop_verify->idom_no_update(n) ) {
3263 tty->print("Unequals idoms for: ");
3264 n->dump();
3265 if( fail++ > 10 ) return;
3266 tty->print("We have it as: ");
3267 id->dump();
3268 tty->print("Verify thinks: ");
3269 loop_verify->idom_no_update(n)->dump();
3270 tty->cr();
3271 }
3272
3273 }
3274
3275 //------------------------------verify_tree------------------------------------
3276 // Verify that tree structures match. Because the CFG can change, siblings
3277 // within the loop tree can be reordered. We attempt to deal with that by
3278 // reordering the verify's loop tree if possible.
3279 void IdealLoopTree::verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const {
3280 assert( _parent == parent, "Badly formed loop tree" );
3281
3282 // Siblings not in same order? Attempt to re-order.
3283 if( _head != loop->_head ) {
3284 // Find _next pointer to update
3285 IdealLoopTree **pp = &loop->_parent->_child;
3286 while( *pp != loop )
3287 pp = &((*pp)->_next);
3288 // Find proper sibling to be next
3289 IdealLoopTree **nn = &loop->_next;
3290 while( (*nn) && (*nn)->_head != _head )
3291 nn = &((*nn)->_next);
3292
3293 // Check for no match.
3294 if( !(*nn) ) {
3295 // Annoyingly, irreducible loops can pick different headers
3296 // after a major_progress operation, so the rest of the loop
3297 // tree cannot be matched.
3298 if (_irreducible && Compile::current()->major_progress()) return;
3299 assert( 0, "failed to match loop tree" );
3300 }
3301
3302 // Move (*nn) to (*pp)
3303 IdealLoopTree *hit = *nn;
3304 *nn = hit->_next;
3305 hit->_next = loop;
3306 *pp = loop;
3307 loop = hit;
3308 // Now try again to verify
3309 }
3310
3311 assert( _head == loop->_head , "mismatched loop head" );
3312 Node *tail = _tail; // Inline a non-updating version of
3313 while( !tail->in(0) ) // the 'tail()' call.
3314 tail = tail->in(1);
3315 assert( tail == loop->_tail, "mismatched loop tail" );
3316
3317 // Counted loops that are guarded should be able to find their guards
3318 if( _head->is_CountedLoop() && _head->as_CountedLoop()->is_main_loop() ) {
3319 CountedLoopNode *cl = _head->as_CountedLoop();
3320 Node *init = cl->init_trip();
3321 Node *ctrl = cl->in(LoopNode::EntryControl);
3322 assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" );
3323 Node *iff = ctrl->in(0);
3324 assert( iff->Opcode() == Op_If, "" );
3325 Node *bol = iff->in(1);
3326 assert( bol->Opcode() == Op_Bool, "" );
3327 Node *cmp = bol->in(1);
3328 assert( cmp->Opcode() == Op_CmpI, "" );
3329 Node *add = cmp->in(1);
3330 Node *opaq;
3331 if( add->Opcode() == Op_Opaque1 ) {
3332 opaq = add;
3333 } else {
3334 assert( add->Opcode() == Op_AddI || add->Opcode() == Op_ConI , "" );
3335 assert( add == init, "" );
3336 opaq = cmp->in(2);
3337 }
3338 assert( opaq->Opcode() == Op_Opaque1, "" );
3339
3340 }
3341
3342 if (_child != NULL) _child->verify_tree(loop->_child, this);
3343 if (_next != NULL) _next ->verify_tree(loop->_next, parent);
3344 // Innermost loops need to verify loop bodies,
3345 // but only if no 'major_progress'
3346 int fail = 0;
3347 if (!Compile::current()->major_progress() && _child == NULL) {
3348 for( uint i = 0; i < _body.size(); i++ ) {
3349 Node *n = _body.at(i);
3350 if (n->outcnt() == 0) continue; // Ignore dead
3351 uint j;
3352 for( j = 0; j < loop->_body.size(); j++ )
3353 if( loop->_body.at(j) == n )
3354 break;
3355 if( j == loop->_body.size() ) { // Not found in loop body
3356 // Last ditch effort to avoid assertion: Its possible that we
3357 // have some users (so outcnt not zero) but are still dead.
3358 // Try to find from root.
3359 if (Compile::current()->root()->find(n->_idx)) {
3360 fail++;
3361 tty->print("We have that verify does not: ");
3362 n->dump();
3363 }
3364 }
3365 }
3366 for( uint i2 = 0; i2 < loop->_body.size(); i2++ ) {
3367 Node *n = loop->_body.at(i2);
3368 if (n->outcnt() == 0) continue; // Ignore dead
3369 uint j;
3370 for( j = 0; j < _body.size(); j++ )
3371 if( _body.at(j) == n )
3372 break;
3373 if( j == _body.size() ) { // Not found in loop body
3374 // Last ditch effort to avoid assertion: Its possible that we
3375 // have some users (so outcnt not zero) but are still dead.
3376 // Try to find from root.
3377 if (Compile::current()->root()->find(n->_idx)) {
3378 fail++;
3379 tty->print("Verify has that we do not: ");
3380 n->dump();
3381 }
3382 }
3383 }
3384 assert( !fail, "loop body mismatch" );
3385 }
3386 }
3387
3388 #endif
3389
3390 //------------------------------set_idom---------------------------------------
3391 void PhaseIdealLoop::set_idom(Node* d, Node* n, uint dom_depth) {
3392 uint idx = d->_idx;
3393 if (idx >= _idom_size) {
3394 uint newsize = _idom_size<<1;
3395 while( idx >= newsize ) {
3396 newsize <<= 1;
3397 }
3398 _idom = REALLOC_RESOURCE_ARRAY( Node*, _idom,_idom_size,newsize);
3399 _dom_depth = REALLOC_RESOURCE_ARRAY( uint, _dom_depth,_idom_size,newsize);
3400 memset( _dom_depth + _idom_size, 0, (newsize - _idom_size) * sizeof(uint) );
3401 _idom_size = newsize;
3402 }
3403 _idom[idx] = n;
3404 _dom_depth[idx] = dom_depth;
3405 }
3406
3407 //------------------------------recompute_dom_depth---------------------------------------
3408 // The dominator tree is constructed with only parent pointers.
3409 // This recomputes the depth in the tree by first tagging all
3410 // nodes as "no depth yet" marker. The next pass then runs up
3411 // the dom tree from each node marked "no depth yet", and computes
3412 // the depth on the way back down.
3413 void PhaseIdealLoop::recompute_dom_depth() {
3414 uint no_depth_marker = C->unique();
3415 uint i;
3416 // Initialize depth to "no depth yet" and realize all lazy updates
3417 for (i = 0; i < _idom_size; i++) {
3418 // Only indices with a _dom_depth has a Node* or NULL (otherwise uninitalized).
3419 if (_dom_depth[i] > 0 && _idom[i] != NULL) {
3420 _dom_depth[i] = no_depth_marker;
3421
3422 // heal _idom if it has a fwd mapping in _nodes
3423 if (_idom[i]->in(0) == NULL) {
3424 idom(i);
3425 }
3426 }
3427 }
3428 if (_dom_stk == NULL) {
3429 uint init_size = C->live_nodes() / 100; // Guess that 1/100 is a reasonable initial size.
3430 if (init_size < 10) init_size = 10;
3431 _dom_stk = new GrowableArray<uint>(init_size);
3432 }
3433 // Compute new depth for each node.
3434 for (i = 0; i < _idom_size; i++) {
3435 uint j = i;
3436 // Run up the dom tree to find a node with a depth
3437 while (_dom_depth[j] == no_depth_marker) {
3438 _dom_stk->push(j);
3439 j = _idom[j]->_idx;
3440 }
3441 // Compute the depth on the way back down this tree branch
3442 uint dd = _dom_depth[j] + 1;
3443 while (_dom_stk->length() > 0) {
3444 uint j = _dom_stk->pop();
3445 _dom_depth[j] = dd;
3446 dd++;
3447 }
3448 }
3449 }
3450
3451 //------------------------------sort-------------------------------------------
3452 // Insert 'loop' into the existing loop tree. 'innermost' is a leaf of the
3453 // loop tree, not the root.
3454 IdealLoopTree *PhaseIdealLoop::sort( IdealLoopTree *loop, IdealLoopTree *innermost ) {
3455 if( !innermost ) return loop; // New innermost loop
3456
3457 int loop_preorder = get_preorder(loop->_head); // Cache pre-order number
3458 assert( loop_preorder, "not yet post-walked loop" );
3459 IdealLoopTree **pp = &innermost; // Pointer to previous next-pointer
3460 IdealLoopTree *l = *pp; // Do I go before or after 'l'?
3461
3462 // Insert at start of list
3463 while( l ) { // Insertion sort based on pre-order
3464 if( l == loop ) return innermost; // Already on list!
3465 int l_preorder = get_preorder(l->_head); // Cache pre-order number
3466 assert( l_preorder, "not yet post-walked l" );
3467 // Check header pre-order number to figure proper nesting
3468 if( loop_preorder > l_preorder )
3469 break; // End of insertion
3470 // If headers tie (e.g., shared headers) check tail pre-order numbers.
3471 // Since I split shared headers, you'd think this could not happen.
3472 // BUT: I must first do the preorder numbering before I can discover I
3473 // have shared headers, so the split headers all get the same preorder
3474 // number as the RegionNode they split from.
3475 if( loop_preorder == l_preorder &&
3476 get_preorder(loop->_tail) < get_preorder(l->_tail) )
3477 break; // Also check for shared headers (same pre#)
3478 pp = &l->_parent; // Chain up list
3479 l = *pp;
3480 }
3481 // Link into list
3482 // Point predecessor to me
3483 *pp = loop;
3484 // Point me to successor
3485 IdealLoopTree *p = loop->_parent;
3486 loop->_parent = l; // Point me to successor
3487 if( p ) sort( p, innermost ); // Insert my parents into list as well
3488 return innermost;
3489 }
3490
3491 //------------------------------build_loop_tree--------------------------------
3492 // I use a modified Vick/Tarjan algorithm. I need pre- and a post- visit
3493 // bits. The _nodes[] array is mapped by Node index and holds a NULL for
3494 // not-yet-pre-walked, pre-order # for pre-but-not-post-walked and holds the
3495 // tightest enclosing IdealLoopTree for post-walked.
3496 //
3497 // During my forward walk I do a short 1-layer lookahead to see if I can find
3498 // a loop backedge with that doesn't have any work on the backedge. This
3499 // helps me construct nested loops with shared headers better.
3500 //
3501 // Once I've done the forward recursion, I do the post-work. For each child
3502 // I check to see if there is a backedge. Backedges define a loop! I
3503 // insert an IdealLoopTree at the target of the backedge.
3504 //
3505 // During the post-work I also check to see if I have several children
3506 // belonging to different loops. If so, then this Node is a decision point
3507 // where control flow can choose to change loop nests. It is at this
3508 // decision point where I can figure out how loops are nested. At this
3509 // time I can properly order the different loop nests from my children.
3510 // Note that there may not be any backedges at the decision point!
3511 //
3512 // Since the decision point can be far removed from the backedges, I can't
3513 // order my loops at the time I discover them. Thus at the decision point
3514 // I need to inspect loop header pre-order numbers to properly nest my
3515 // loops. This means I need to sort my childrens' loops by pre-order.
3516 // The sort is of size number-of-control-children, which generally limits
3517 // it to size 2 (i.e., I just choose between my 2 target loops).
3518 void PhaseIdealLoop::build_loop_tree() {
3519 // Allocate stack of size C->live_nodes()/2 to avoid frequent realloc
3520 GrowableArray <Node *> bltstack(C->live_nodes() >> 1);
3521 Node *n = C->root();
3522 bltstack.push(n);
3523 int pre_order = 1;
3524 int stack_size;
3525
3526 while ( ( stack_size = bltstack.length() ) != 0 ) {
3527 n = bltstack.top(); // Leave node on stack
3528 if ( !is_visited(n) ) {
3529 // ---- Pre-pass Work ----
3530 // Pre-walked but not post-walked nodes need a pre_order number.
3531
3532 set_preorder_visited( n, pre_order ); // set as visited
3533
3534 // ---- Scan over children ----
3535 // Scan first over control projections that lead to loop headers.
3536 // This helps us find inner-to-outer loops with shared headers better.
3537
3538 // Scan children's children for loop headers.
3539 for ( int i = n->outcnt() - 1; i >= 0; --i ) {
3540 Node* m = n->raw_out(i); // Child
3541 if( m->is_CFG() && !is_visited(m) ) { // Only for CFG children
3542 // Scan over children's children to find loop
3543 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3544 Node* l = m->fast_out(j);
3545 if( is_visited(l) && // Been visited?
3546 !is_postvisited(l) && // But not post-visited
3547 get_preorder(l) < pre_order ) { // And smaller pre-order
3548 // Found! Scan the DFS down this path before doing other paths
3549 bltstack.push(m);
3550 break;
3551 }
3552 }
3553 }
3554 }
3555 pre_order++;
3556 }
3557 else if ( !is_postvisited(n) ) {
3558 // Note: build_loop_tree_impl() adds out edges on rare occasions,
3559 // such as com.sun.rsasign.am::a.
3560 // For non-recursive version, first, process current children.
3561 // On next iteration, check if additional children were added.
3562 for ( int k = n->outcnt() - 1; k >= 0; --k ) {
3563 Node* u = n->raw_out(k);
3564 if ( u->is_CFG() && !is_visited(u) ) {
3565 bltstack.push(u);
3566 }
3567 }
3568 if ( bltstack.length() == stack_size ) {
3569 // There were no additional children, post visit node now
3570 (void)bltstack.pop(); // Remove node from stack
3571 pre_order = build_loop_tree_impl( n, pre_order );
3572 // Check for bailout
3573 if (C->failing()) {
3574 return;
3575 }
3576 // Check to grow _preorders[] array for the case when
3577 // build_loop_tree_impl() adds new nodes.
3578 check_grow_preorders();
3579 }
3580 }
3581 else {
3582 (void)bltstack.pop(); // Remove post-visited node from stack
3583 }
3584 }
3585 }
3586
3587 //------------------------------build_loop_tree_impl---------------------------
3588 int PhaseIdealLoop::build_loop_tree_impl( Node *n, int pre_order ) {
3589 // ---- Post-pass Work ----
3590 // Pre-walked but not post-walked nodes need a pre_order number.
3591
3592 // Tightest enclosing loop for this Node
3593 IdealLoopTree *innermost = NULL;
3594
3595 // For all children, see if any edge is a backedge. If so, make a loop
3596 // for it. Then find the tightest enclosing loop for the self Node.
3597 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
3598 Node* m = n->fast_out(i); // Child
3599 if( n == m ) continue; // Ignore control self-cycles
3600 if( !m->is_CFG() ) continue;// Ignore non-CFG edges
3601
3602 IdealLoopTree *l; // Child's loop
3603 if( !is_postvisited(m) ) { // Child visited but not post-visited?
3604 // Found a backedge
3605 assert( get_preorder(m) < pre_order, "should be backedge" );
3606 // Check for the RootNode, which is already a LoopNode and is allowed
3607 // to have multiple "backedges".
3608 if( m == C->root()) { // Found the root?
3609 l = _ltree_root; // Root is the outermost LoopNode
3610 } else { // Else found a nested loop
3611 // Insert a LoopNode to mark this loop.
3612 l = new IdealLoopTree(this, m, n);
3613 } // End of Else found a nested loop
3614 if( !has_loop(m) ) // If 'm' does not already have a loop set
3615 set_loop(m, l); // Set loop header to loop now
3616
3617 } else { // Else not a nested loop
3618 if( !_nodes[m->_idx] ) continue; // Dead code has no loop
3619 l = get_loop(m); // Get previously determined loop
3620 // If successor is header of a loop (nest), move up-loop till it
3621 // is a member of some outer enclosing loop. Since there are no
3622 // shared headers (I've split them already) I only need to go up
3623 // at most 1 level.
3624 while( l && l->_head == m ) // Successor heads loop?
3625 l = l->_parent; // Move up 1 for me
3626 // If this loop is not properly parented, then this loop
3627 // has no exit path out, i.e. its an infinite loop.
3628 if( !l ) {
3629 // Make loop "reachable" from root so the CFG is reachable. Basically
3630 // insert a bogus loop exit that is never taken. 'm', the loop head,
3631 // points to 'n', one (of possibly many) fall-in paths. There may be
3632 // many backedges as well.
3633
3634 // Here I set the loop to be the root loop. I could have, after
3635 // inserting a bogus loop exit, restarted the recursion and found my
3636 // new loop exit. This would make the infinite loop a first-class
3637 // loop and it would then get properly optimized. What's the use of
3638 // optimizing an infinite loop?
3639 l = _ltree_root; // Oops, found infinite loop
3640
3641 if (!_verify_only) {
3642 // Insert the NeverBranch between 'm' and it's control user.
3643 NeverBranchNode *iff = new NeverBranchNode( m );
3644 _igvn.register_new_node_with_optimizer(iff);
3645 set_loop(iff, l);
3646 Node *if_t = new CProjNode( iff, 0 );
3647 _igvn.register_new_node_with_optimizer(if_t);
3648 set_loop(if_t, l);
3649
3650 Node* cfg = NULL; // Find the One True Control User of m
3651 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3652 Node* x = m->fast_out(j);
3653 if (x->is_CFG() && x != m && x != iff)
3654 { cfg = x; break; }
3655 }
3656 assert(cfg != NULL, "must find the control user of m");
3657 uint k = 0; // Probably cfg->in(0)
3658 while( cfg->in(k) != m ) k++; // But check incase cfg is a Region
3659 cfg->set_req( k, if_t ); // Now point to NeverBranch
3660 _igvn._worklist.push(cfg);
3661
3662 // Now create the never-taken loop exit
3663 Node *if_f = new CProjNode( iff, 1 );
3664 _igvn.register_new_node_with_optimizer(if_f);
3665 set_loop(if_f, l);
3666 // Find frame ptr for Halt. Relies on the optimizer
3667 // V-N'ing. Easier and quicker than searching through
3668 // the program structure.
3669 Node *frame = new ParmNode( C->start(), TypeFunc::FramePtr );
3670 _igvn.register_new_node_with_optimizer(frame);
3671 // Halt & Catch Fire
3672 Node* halt = new HaltNode(if_f, frame, "never-taken loop exit reached");
3673 _igvn.register_new_node_with_optimizer(halt);
3674 set_loop(halt, l);
3675 C->root()->add_req(halt);
3676 }
3677 set_loop(C->root(), _ltree_root);
3678 }
3679 }
3680 // Weeny check for irreducible. This child was already visited (this
3681 // IS the post-work phase). Is this child's loop header post-visited
3682 // as well? If so, then I found another entry into the loop.
3683 if (!_verify_only) {
3684 while( is_postvisited(l->_head) ) {
3685 // found irreducible
3686 l->_irreducible = 1; // = true
3687 l = l->_parent;
3688 _has_irreducible_loops = true;
3689 // Check for bad CFG here to prevent crash, and bailout of compile
3690 if (l == NULL) {
3691 C->record_method_not_compilable("unhandled CFG detected during loop optimization");
3692 return pre_order;
3693 }
3694 }
3695 C->set_has_irreducible_loop(_has_irreducible_loops);
3696 }
3697
3698 // This Node might be a decision point for loops. It is only if
3699 // it's children belong to several different loops. The sort call
3700 // does a trivial amount of work if there is only 1 child or all
3701 // children belong to the same loop. If however, the children
3702 // belong to different loops, the sort call will properly set the
3703 // _parent pointers to show how the loops nest.
3704 //
3705 // In any case, it returns the tightest enclosing loop.
3706 innermost = sort( l, innermost );
3707 }
3708
3709 // Def-use info will have some dead stuff; dead stuff will have no
3710 // loop decided on.
3711
3712 // Am I a loop header? If so fix up my parent's child and next ptrs.
3713 if( innermost && innermost->_head == n ) {
3714 assert( get_loop(n) == innermost, "" );
3715 IdealLoopTree *p = innermost->_parent;
3716 IdealLoopTree *l = innermost;
3717 while( p && l->_head == n ) {
3718 l->_next = p->_child; // Put self on parents 'next child'
3719 p->_child = l; // Make self as first child of parent
3720 l = p; // Now walk up the parent chain
3721 p = l->_parent;
3722 }
3723 } else {
3724 // Note that it is possible for a LoopNode to reach here, if the
3725 // backedge has been made unreachable (hence the LoopNode no longer
3726 // denotes a Loop, and will eventually be removed).
3727
3728 // Record tightest enclosing loop for self. Mark as post-visited.
3729 set_loop(n, innermost);
3730 // Also record has_call flag early on
3731 if( innermost ) {
3732 if( n->is_Call() && !n->is_CallLeaf() && !n->is_macro() ) {
3733 // Do not count uncommon calls
3734 if( !n->is_CallStaticJava() || !n->as_CallStaticJava()->_name ) {
3735 Node *iff = n->in(0)->in(0);
3736 // No any calls for vectorized loops.
3737 if( UseSuperWord || !iff->is_If() ||
3738 (n->in(0)->Opcode() == Op_IfFalse &&
3739 (1.0 - iff->as_If()->_prob) >= 0.01) ||
3740 (iff->as_If()->_prob >= 0.01) )
3741 innermost->_has_call = 1;
3742 }
3743 } else if( n->is_Allocate() && n->as_Allocate()->_is_scalar_replaceable ) {
3744 // Disable loop optimizations if the loop has a scalar replaceable
3745 // allocation. This disabling may cause a potential performance lost
3746 // if the allocation is not eliminated for some reason.
3747 innermost->_allow_optimizations = false;
3748 innermost->_has_call = 1; // = true
3749 } else if (n->Opcode() == Op_SafePoint) {
3750 // Record all safepoints in this loop.
3751 if (innermost->_safepts == NULL) innermost->_safepts = new Node_List();
3752 innermost->_safepts->push(n);
3753 }
3754 }
3755 }
3756
3757 // Flag as post-visited now
3758 set_postvisited(n);
3759 return pre_order;
3760 }
3761
3762
3763 //------------------------------build_loop_early-------------------------------
3764 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
3765 // First pass computes the earliest controlling node possible. This is the
3766 // controlling input with the deepest dominating depth.
3767 void PhaseIdealLoop::build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) {
3768 while (worklist.size() != 0) {
3769 // Use local variables nstack_top_n & nstack_top_i to cache values
3770 // on nstack's top.
3771 Node *nstack_top_n = worklist.pop();
3772 uint nstack_top_i = 0;
3773 //while_nstack_nonempty:
3774 while (true) {
3775 // Get parent node and next input's index from stack's top.
3776 Node *n = nstack_top_n;
3777 uint i = nstack_top_i;
3778 uint cnt = n->req(); // Count of inputs
3779 if (i == 0) { // Pre-process the node.
3780 if( has_node(n) && // Have either loop or control already?
3781 !has_ctrl(n) ) { // Have loop picked out already?
3782 // During "merge_many_backedges" we fold up several nested loops
3783 // into a single loop. This makes the members of the original
3784 // loop bodies pointing to dead loops; they need to move up
3785 // to the new UNION'd larger loop. I set the _head field of these
3786 // dead loops to NULL and the _parent field points to the owning
3787 // loop. Shades of UNION-FIND algorithm.
3788 IdealLoopTree *ilt;
3789 while( !(ilt = get_loop(n))->_head ) {
3790 // Normally I would use a set_loop here. But in this one special
3791 // case, it is legal (and expected) to change what loop a Node
3792 // belongs to.
3793 _nodes.map(n->_idx, (Node*)(ilt->_parent) );
3794 }
3795 // Remove safepoints ONLY if I've already seen I don't need one.
3796 // (the old code here would yank a 2nd safepoint after seeing a
3797 // first one, even though the 1st did not dominate in the loop body
3798 // and thus could be avoided indefinitely)
3799 if( !_verify_only && !_verify_me && ilt->_has_sfpt && n->Opcode() == Op_SafePoint &&
3800 is_deleteable_safept(n)) {
3801 Node *in = n->in(TypeFunc::Control);
3802 lazy_replace(n,in); // Pull safepoint now
3803 if (ilt->_safepts != NULL) {
3804 ilt->_safepts->yank(n);
3805 }
3806 // Carry on with the recursion "as if" we are walking
3807 // only the control input
3808 if( !visited.test_set( in->_idx ) ) {
3809 worklist.push(in); // Visit this guy later, using worklist
3810 }
3811 // Get next node from nstack:
3812 // - skip n's inputs processing by setting i > cnt;
3813 // - we also will not call set_early_ctrl(n) since
3814 // has_node(n) == true (see the condition above).
3815 i = cnt + 1;
3816 }
3817 }
3818 } // if (i == 0)
3819
3820 // Visit all inputs
3821 bool done = true; // Assume all n's inputs will be processed
3822 while (i < cnt) {
3823 Node *in = n->in(i);
3824 ++i;
3825 if (in == NULL) continue;
3826 if (in->pinned() && !in->is_CFG())
3827 set_ctrl(in, in->in(0));
3828 int is_visited = visited.test_set( in->_idx );
3829 if (!has_node(in)) { // No controlling input yet?
3830 assert( !in->is_CFG(), "CFG Node with no controlling input?" );
3831 assert( !is_visited, "visit only once" );
3832 nstack.push(n, i); // Save parent node and next input's index.
3833 nstack_top_n = in; // Process current input now.
3834 nstack_top_i = 0;
3835 done = false; // Not all n's inputs processed.
3836 break; // continue while_nstack_nonempty;
3837 } else if (!is_visited) {
3838 // This guy has a location picked out for him, but has not yet
3839 // been visited. Happens to all CFG nodes, for instance.
3840 // Visit him using the worklist instead of recursion, to break
3841 // cycles. Since he has a location already we do not need to
3842 // find his location before proceeding with the current Node.
3843 worklist.push(in); // Visit this guy later, using worklist
3844 }
3845 }
3846 if (done) {
3847 // All of n's inputs have been processed, complete post-processing.
3848
3849 // Compute earliest point this Node can go.
3850 // CFG, Phi, pinned nodes already know their controlling input.
3851 if (!has_node(n)) {
3852 // Record earliest legal location
3853 set_early_ctrl( n );
3854 }
3855 if (nstack.is_empty()) {
3856 // Finished all nodes on stack.
3857 // Process next node on the worklist.
3858 break;
3859 }
3860 // Get saved parent node and next input's index.
3861 nstack_top_n = nstack.node();
3862 nstack_top_i = nstack.index();
3863 nstack.pop();
3864 }
3865 } // while (true)
3866 }
3867 }
3868
3869 //------------------------------dom_lca_internal--------------------------------
3870 // Pair-wise LCA
3871 Node *PhaseIdealLoop::dom_lca_internal( Node *n1, Node *n2 ) const {
3872 if( !n1 ) return n2; // Handle NULL original LCA
3873 assert( n1->is_CFG(), "" );
3874 assert( n2->is_CFG(), "" );
3875 // find LCA of all uses
3876 uint d1 = dom_depth(n1);
3877 uint d2 = dom_depth(n2);
3878 while (n1 != n2) {
3879 if (d1 > d2) {
3880 n1 = idom(n1);
3881 d1 = dom_depth(n1);
3882 } else if (d1 < d2) {
3883 n2 = idom(n2);
3884 d2 = dom_depth(n2);
3885 } else {
3886 // Here d1 == d2. Due to edits of the dominator-tree, sections
3887 // of the tree might have the same depth. These sections have
3888 // to be searched more carefully.
3889
3890 // Scan up all the n1's with equal depth, looking for n2.
3891 Node *t1 = idom(n1);
3892 while (dom_depth(t1) == d1) {
3893 if (t1 == n2) return n2;
3894 t1 = idom(t1);
3895 }
3896 // Scan up all the n2's with equal depth, looking for n1.
3897 Node *t2 = idom(n2);
3898 while (dom_depth(t2) == d2) {
3899 if (t2 == n1) return n1;
3900 t2 = idom(t2);
3901 }
3902 // Move up to a new dominator-depth value as well as up the dom-tree.
3903 n1 = t1;
3904 n2 = t2;
3905 d1 = dom_depth(n1);
3906 d2 = dom_depth(n2);
3907 }
3908 }
3909 return n1;
3910 }
3911
3912 //------------------------------compute_idom-----------------------------------
3913 // Locally compute IDOM using dom_lca call. Correct only if the incoming
3914 // IDOMs are correct.
3915 Node *PhaseIdealLoop::compute_idom( Node *region ) const {
3916 assert( region->is_Region(), "" );
3917 Node *LCA = NULL;
3918 for( uint i = 1; i < region->req(); i++ ) {
3919 if( region->in(i) != C->top() )
3920 LCA = dom_lca( LCA, region->in(i) );
3921 }
3922 return LCA;
3923 }
3924
3925 bool PhaseIdealLoop::verify_dominance(Node* n, Node* use, Node* LCA, Node* early) {
3926 bool had_error = false;
3927 #ifdef ASSERT
3928 if (early != C->root()) {
3929 // Make sure that there's a dominance path from LCA to early
3930 Node* d = LCA;
3931 while (d != early) {
3932 if (d == C->root()) {
3933 dump_bad_graph("Bad graph detected in compute_lca_of_uses", n, early, LCA);
3934 tty->print_cr("*** Use %d isn't dominated by def %d ***", use->_idx, n->_idx);
3935 had_error = true;
3936 break;
3937 }
3938 d = idom(d);
3939 }
3940 }
3941 #endif
3942 return had_error;
3943 }
3944
3945
3946 Node* PhaseIdealLoop::compute_lca_of_uses(Node* n, Node* early, bool verify) {
3947 // Compute LCA over list of uses
3948 bool had_error = false;
3949 Node *LCA = NULL;
3950 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax && LCA != early; i++) {
3951 Node* c = n->fast_out(i);
3952 if (_nodes[c->_idx] == NULL)
3953 continue; // Skip the occasional dead node
3954 if( c->is_Phi() ) { // For Phis, we must land above on the path
3955 for( uint j=1; j<c->req(); j++ ) {// For all inputs
3956 if( c->in(j) == n ) { // Found matching input?
3957 Node *use = c->in(0)->in(j);
3958 if (_verify_only && use->is_top()) continue;
3959 LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
3960 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error;
3961 }
3962 }
3963 } else {
3964 // For CFG data-users, use is in the block just prior
3965 Node *use = has_ctrl(c) ? get_ctrl(c) : c->in(0);
3966 LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
3967 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error;
3968 }
3969 }
3970 assert(!had_error, "bad dominance");
3971 return LCA;
3972 }
3973
3974 // Check the shape of the graph at the loop entry. In some cases,
3975 // the shape of the graph does not match the shape outlined below.
3976 // That is caused by the Opaque1 node "protecting" the shape of
3977 // the graph being removed by, for example, the IGVN performed
3978 // in PhaseIdealLoop::build_and_optimize().
3979 //
3980 // After the Opaque1 node has been removed, optimizations (e.g., split-if,
3981 // loop unswitching, and IGVN, or a combination of them) can freely change
3982 // the graph's shape. As a result, the graph shape outlined below cannot
3983 // be guaranteed anymore.
3984 bool PhaseIdealLoop::is_canonical_loop_entry(CountedLoopNode* cl) {
3985 if (!cl->is_main_loop() && !cl->is_post_loop()) {
3986 return false;
3987 }
3988 Node* ctrl = cl->skip_predicates();
3989
3990 if (ctrl == NULL || (!ctrl->is_IfTrue() && !ctrl->is_IfFalse())) {
3991 return false;
3992 }
3993 Node* iffm = ctrl->in(0);
3994 if (iffm == NULL || !iffm->is_If()) {
3995 return false;
3996 }
3997 Node* bolzm = iffm->in(1);
3998 if (bolzm == NULL || !bolzm->is_Bool()) {
3999 return false;
4000 }
4001 Node* cmpzm = bolzm->in(1);
4002 if (cmpzm == NULL || !cmpzm->is_Cmp()) {
4003 return false;
4004 }
4005 // compares can get conditionally flipped
4006 bool found_opaque = false;
4007 for (uint i = 1; i < cmpzm->req(); i++) {
4008 Node* opnd = cmpzm->in(i);
4009 if (opnd && opnd->Opcode() == Op_Opaque1) {
4010 found_opaque = true;
4011 break;
4012 }
4013 }
4014 if (!found_opaque) {
4015 return false;
4016 }
4017 return true;
4018 }
4019
4020 //------------------------------get_late_ctrl----------------------------------
4021 // Compute latest legal control.
4022 Node *PhaseIdealLoop::get_late_ctrl( Node *n, Node *early ) {
4023 assert(early != NULL, "early control should not be NULL");
4024
4025 Node* LCA = compute_lca_of_uses(n, early);
4026 #ifdef ASSERT
4027 if (LCA == C->root() && LCA != early) {
4028 // def doesn't dominate uses so print some useful debugging output
4029 compute_lca_of_uses(n, early, true);
4030 }
4031 #endif
4032
4033 // if this is a load, check for anti-dependent stores
4034 // We use a conservative algorithm to identify potential interfering
4035 // instructions and for rescheduling the load. The users of the memory
4036 // input of this load are examined. Any use which is not a load and is
4037 // dominated by early is considered a potentially interfering store.
4038 // This can produce false positives.
4039 if (n->is_Load() && LCA != early) {
4040 Node_List worklist;
4041
4042 Node *mem = n->in(MemNode::Memory);
4043 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
4044 Node* s = mem->fast_out(i);
4045 worklist.push(s);
4046 }
4047 while(worklist.size() != 0 && LCA != early) {
4048 Node* s = worklist.pop();
4049 if (s->is_Load() || s->Opcode() == Op_SafePoint ||
4050 (s->is_CallStaticJava() && s->as_CallStaticJava()->uncommon_trap_request() != 0)) {
4051 continue;
4052 } else if (s->is_MergeMem()) {
4053 for (DUIterator_Fast imax, i = s->fast_outs(imax); i < imax; i++) {
4054 Node* s1 = s->fast_out(i);
4055 worklist.push(s1);
4056 }
4057 } else {
4058 Node *sctrl = has_ctrl(s) ? get_ctrl(s) : s->in(0);
4059 assert(sctrl != NULL || s->outcnt() == 0, "must have control");
4060 if (sctrl != NULL && !sctrl->is_top() && is_dominator(early, sctrl)) {
4061 LCA = dom_lca_for_get_late_ctrl(LCA, sctrl, n);
4062 }
4063 }
4064 }
4065 }
4066
4067 assert(LCA == find_non_split_ctrl(LCA), "unexpected late control");
4068 return LCA;
4069 }
4070
4071 // true if CFG node d dominates CFG node n
4072 bool PhaseIdealLoop::is_dominator(Node *d, Node *n) {
4073 if (d == n)
4074 return true;
4075 assert(d->is_CFG() && n->is_CFG(), "must have CFG nodes");
4076 uint dd = dom_depth(d);
4077 while (dom_depth(n) >= dd) {
4078 if (n == d)
4079 return true;
4080 n = idom(n);
4081 }
4082 return false;
4083 }
4084
4085 //------------------------------dom_lca_for_get_late_ctrl_internal-------------
4086 // Pair-wise LCA with tags.
4087 // Tag each index with the node 'tag' currently being processed
4088 // before advancing up the dominator chain using idom().
4089 // Later calls that find a match to 'tag' know that this path has already
4090 // been considered in the current LCA (which is input 'n1' by convention).
4091 // Since get_late_ctrl() is only called once for each node, the tag array
4092 // does not need to be cleared between calls to get_late_ctrl().
4093 // Algorithm trades a larger constant factor for better asymptotic behavior
4094 //
4095 Node *PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal( Node *n1, Node *n2, Node *tag ) {
4096 uint d1 = dom_depth(n1);
4097 uint d2 = dom_depth(n2);
4098
4099 do {
4100 if (d1 > d2) {
4101 // current lca is deeper than n2
4102 _dom_lca_tags.map(n1->_idx, tag);
4103 n1 = idom(n1);
4104 d1 = dom_depth(n1);
4105 } else if (d1 < d2) {
4106 // n2 is deeper than current lca
4107 Node *memo = _dom_lca_tags[n2->_idx];
4108 if( memo == tag ) {
4109 return n1; // Return the current LCA
4110 }
4111 _dom_lca_tags.map(n2->_idx, tag);
4112 n2 = idom(n2);
4113 d2 = dom_depth(n2);
4114 } else {
4115 // Here d1 == d2. Due to edits of the dominator-tree, sections
4116 // of the tree might have the same depth. These sections have
4117 // to be searched more carefully.
4118
4119 // Scan up all the n1's with equal depth, looking for n2.
4120 _dom_lca_tags.map(n1->_idx, tag);
4121 Node *t1 = idom(n1);
4122 while (dom_depth(t1) == d1) {
4123 if (t1 == n2) return n2;
4124 _dom_lca_tags.map(t1->_idx, tag);
4125 t1 = idom(t1);
4126 }
4127 // Scan up all the n2's with equal depth, looking for n1.
4128 _dom_lca_tags.map(n2->_idx, tag);
4129 Node *t2 = idom(n2);
4130 while (dom_depth(t2) == d2) {
4131 if (t2 == n1) return n1;
4132 _dom_lca_tags.map(t2->_idx, tag);
4133 t2 = idom(t2);
4134 }
4135 // Move up to a new dominator-depth value as well as up the dom-tree.
4136 n1 = t1;
4137 n2 = t2;
4138 d1 = dom_depth(n1);
4139 d2 = dom_depth(n2);
4140 }
4141 } while (n1 != n2);
4142 return n1;
4143 }
4144
4145 //------------------------------init_dom_lca_tags------------------------------
4146 // Tag could be a node's integer index, 32bits instead of 64bits in some cases
4147 // Intended use does not involve any growth for the array, so it could
4148 // be of fixed size.
4149 void PhaseIdealLoop::init_dom_lca_tags() {
4150 uint limit = C->unique() + 1;
4151 _dom_lca_tags.map( limit, NULL );
4152 #ifdef ASSERT
4153 for( uint i = 0; i < limit; ++i ) {
4154 assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer");
4155 }
4156 #endif // ASSERT
4157 }
4158
4159 //------------------------------clear_dom_lca_tags------------------------------
4160 // Tag could be a node's integer index, 32bits instead of 64bits in some cases
4161 // Intended use does not involve any growth for the array, so it could
4162 // be of fixed size.
4163 void PhaseIdealLoop::clear_dom_lca_tags() {
4164 uint limit = C->unique() + 1;
4165 _dom_lca_tags.map( limit, NULL );
4166 _dom_lca_tags.clear();
4167 #ifdef ASSERT
4168 for( uint i = 0; i < limit; ++i ) {
4169 assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer");
4170 }
4171 #endif // ASSERT
4172 }
4173
4174 //------------------------------build_loop_late--------------------------------
4175 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
4176 // Second pass finds latest legal placement, and ideal loop placement.
4177 void PhaseIdealLoop::build_loop_late( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) {
4178 while (worklist.size() != 0) {
4179 Node *n = worklist.pop();
4180 // Only visit once
4181 if (visited.test_set(n->_idx)) continue;
4182 uint cnt = n->outcnt();
4183 uint i = 0;
4184 while (true) {
4185 assert( _nodes[n->_idx], "no dead nodes" );
4186 // Visit all children
4187 if (i < cnt) {
4188 Node* use = n->raw_out(i);
4189 ++i;
4190 // Check for dead uses. Aggressively prune such junk. It might be
4191 // dead in the global sense, but still have local uses so I cannot
4192 // easily call 'remove_dead_node'.
4193 if( _nodes[use->_idx] != NULL || use->is_top() ) { // Not dead?
4194 // Due to cycles, we might not hit the same fixed point in the verify
4195 // pass as we do in the regular pass. Instead, visit such phis as
4196 // simple uses of the loop head.
4197 if( use->in(0) && (use->is_CFG() || use->is_Phi()) ) {
4198 if( !visited.test(use->_idx) )
4199 worklist.push(use);
4200 } else if( !visited.test_set(use->_idx) ) {
4201 nstack.push(n, i); // Save parent and next use's index.
4202 n = use; // Process all children of current use.
4203 cnt = use->outcnt();
4204 i = 0;
4205 }
4206 } else {
4207 // Do not visit around the backedge of loops via data edges.
4208 // push dead code onto a worklist
4209 _deadlist.push(use);
4210 }
4211 } else {
4212 // All of n's children have been processed, complete post-processing.
4213 build_loop_late_post(n);
4214 if (nstack.is_empty()) {
4215 // Finished all nodes on stack.
4216 // Process next node on the worklist.
4217 break;
4218 }
4219 // Get saved parent node and next use's index. Visit the rest of uses.
4220 n = nstack.node();
4221 cnt = n->outcnt();
4222 i = nstack.index();
4223 nstack.pop();
4224 }
4225 }
4226 }
4227 }
4228
4229 // Verify that no data node is scheduled in the outer loop of a strip
4230 // mined loop.
4231 void PhaseIdealLoop::verify_strip_mined_scheduling(Node *n, Node* least) {
4232 #ifdef ASSERT
4233 if (get_loop(least)->_nest == 0) {
4234 return;
4235 }
4236 IdealLoopTree* loop = get_loop(least);
4237 Node* head = loop->_head;
4238 if (head->is_OuterStripMinedLoop() &&
4239 // Verification can't be applied to fully built strip mined loops
4240 head->as_Loop()->outer_loop_end()->in(1)->find_int_con(-1) == 0) {
4241 Node* sfpt = head->as_Loop()->outer_safepoint();
4242 ResourceMark rm;
4243 Unique_Node_List wq;
4244 wq.push(sfpt);
4245 for (uint i = 0; i < wq.size(); i++) {
4246 Node *m = wq.at(i);
4247 for (uint i = 1; i < m->req(); i++) {
4248 Node* nn = m->in(i);
4249 if (nn == n) {
4250 return;
4251 }
4252 if (nn != NULL && has_ctrl(nn) && get_loop(get_ctrl(nn)) == loop) {
4253 wq.push(nn);
4254 }
4255 }
4256 }
4257 ShouldNotReachHere();
4258 }
4259 #endif
4260 }
4261
4262
4263 //------------------------------build_loop_late_post---------------------------
4264 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
4265 // Second pass finds latest legal placement, and ideal loop placement.
4266 void PhaseIdealLoop::build_loop_late_post(Node *n) {
4267 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
4268
4269 if (bs->build_loop_late_post(this, n)) {
4270 return;
4271 }
4272
4273 build_loop_late_post_work(n, true);
4274 }
4275
4276 void PhaseIdealLoop::build_loop_late_post_work(Node *n, bool pinned) {
4277
4278 if (n->req() == 2 && (n->Opcode() == Op_ConvI2L || n->Opcode() == Op_CastII) && !C->major_progress() && !_verify_only) {
4279 _igvn._worklist.push(n); // Maybe we'll normalize it, if no more loops.
4280 }
4281
4282 #ifdef ASSERT
4283 if (_verify_only && !n->is_CFG()) {
4284 // Check def-use domination.
4285 compute_lca_of_uses(n, get_ctrl(n), true /* verify */);
4286 }
4287 #endif
4288
4289 // CFG and pinned nodes already handled
4290 if( n->in(0) ) {
4291 if( n->in(0)->is_top() ) return; // Dead?
4292
4293 // We'd like +VerifyLoopOptimizations to not believe that Mod's/Loads
4294 // _must_ be pinned (they have to observe their control edge of course).
4295 // Unlike Stores (which modify an unallocable resource, the memory
4296 // state), Mods/Loads can float around. So free them up.
4297 switch( n->Opcode() ) {
4298 case Op_DivI:
4299 case Op_DivF:
4300 case Op_DivD:
4301 case Op_ModI:
4302 case Op_ModF:
4303 case Op_ModD:
4304 case Op_LoadB: // Same with Loads; they can sink
4305 case Op_LoadUB: // during loop optimizations.
4306 case Op_LoadUS:
4307 case Op_LoadD:
4308 case Op_LoadF:
4309 case Op_LoadI:
4310 case Op_LoadKlass:
4311 case Op_LoadNKlass:
4312 case Op_LoadL:
4313 case Op_LoadS:
4314 case Op_LoadP:
4315 case Op_LoadN:
4316 case Op_LoadRange:
4317 case Op_LoadD_unaligned:
4318 case Op_LoadL_unaligned:
4319 case Op_StrComp: // Does a bunch of load-like effects
4320 case Op_StrEquals:
4321 case Op_StrIndexOf:
4322 case Op_StrIndexOfChar:
4323 case Op_AryEq:
4324 case Op_HasNegatives:
4325 pinned = false;
4326 }
4327 if( pinned ) {
4328 IdealLoopTree *chosen_loop = get_loop(n->is_CFG() ? n : get_ctrl(n));
4329 if( !chosen_loop->_child ) // Inner loop?
4330 chosen_loop->_body.push(n); // Collect inner loops
4331 return;
4332 }
4333 } else { // No slot zero
4334 if( n->is_CFG() ) { // CFG with no slot 0 is dead
4335 _nodes.map(n->_idx,0); // No block setting, it's globally dead
4336 return;
4337 }
4338 assert(!n->is_CFG() || n->outcnt() == 0, "");
4339 }
4340
4341 // Do I have a "safe range" I can select over?
4342 Node *early = get_ctrl(n);// Early location already computed
4343
4344 // Compute latest point this Node can go
4345 Node *LCA = get_late_ctrl( n, early );
4346 // LCA is NULL due to uses being dead
4347 if( LCA == NULL ) {
4348 #ifdef ASSERT
4349 for (DUIterator i1 = n->outs(); n->has_out(i1); i1++) {
4350 assert( _nodes[n->out(i1)->_idx] == NULL, "all uses must also be dead");
4351 }
4352 #endif
4353 _nodes.map(n->_idx, 0); // This node is useless
4354 _deadlist.push(n);
4355 return;
4356 }
4357 assert(LCA != NULL && !LCA->is_top(), "no dead nodes");
4358
4359 Node *legal = LCA; // Walk 'legal' up the IDOM chain
4360 Node *least = legal; // Best legal position so far
4361 while( early != legal ) { // While not at earliest legal
4362 #ifdef ASSERT
4363 if (legal->is_Start() && !early->is_Root()) {
4364 // Bad graph. Print idom path and fail.
4365 dump_bad_graph("Bad graph detected in build_loop_late", n, early, LCA);
4366 assert(false, "Bad graph detected in build_loop_late");
4367 }
4368 #endif
4369 // Find least loop nesting depth
4370 legal = idom(legal); // Bump up the IDOM tree
4371 // Check for lower nesting depth
4372 if( get_loop(legal)->_nest < get_loop(least)->_nest )
4373 least = legal;
4374 }
4375 assert(early == legal || legal != C->root(), "bad dominance of inputs");
4376
4377 // Try not to place code on a loop entry projection
4378 // which can inhibit range check elimination.
4379 if (least != early) {
4380 Node* ctrl_out = least->unique_ctrl_out();
4381 if (ctrl_out && ctrl_out->is_Loop() &&
4382 least == ctrl_out->in(LoopNode::EntryControl)) {
4383 // Move the node above predicates as far up as possible so a
4384 // following pass of loop predication doesn't hoist a predicate
4385 // that depends on it above that node.
4386 Node* new_ctrl = least;
4387 for (;;) {
4388 if (!new_ctrl->is_Proj()) {
4389 break;
4390 }
4391 CallStaticJavaNode* call = new_ctrl->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
4392 if (call == NULL) {
4393 break;
4394 }
4395 int req = call->uncommon_trap_request();
4396 Deoptimization::DeoptReason trap_reason = Deoptimization::trap_request_reason(req);
4397 if (trap_reason != Deoptimization::Reason_loop_limit_check &&
4398 trap_reason != Deoptimization::Reason_predicate &&
4399 trap_reason != Deoptimization::Reason_profile_predicate) {
4400 break;
4401 }
4402 Node* c = new_ctrl->in(0)->in(0);
4403 if (is_dominator(c, early) && c != early) {
4404 break;
4405 }
4406 new_ctrl = c;
4407 }
4408 least = new_ctrl;
4409 }
4410 }
4411
4412 #ifdef ASSERT
4413 // If verifying, verify that 'verify_me' has a legal location
4414 // and choose it as our location.
4415 if( _verify_me ) {
4416 Node *v_ctrl = _verify_me->get_ctrl_no_update(n);
4417 Node *legal = LCA;
4418 while( early != legal ) { // While not at earliest legal
4419 if( legal == v_ctrl ) break; // Check for prior good location
4420 legal = idom(legal) ;// Bump up the IDOM tree
4421 }
4422 // Check for prior good location
4423 if( legal == v_ctrl ) least = legal; // Keep prior if found
4424 }
4425 #endif
4426
4427 // Assign discovered "here or above" point
4428 least = find_non_split_ctrl(least);
4429 verify_strip_mined_scheduling(n, least);
4430 set_ctrl(n, least);
4431
4432 // Collect inner loop bodies
4433 IdealLoopTree *chosen_loop = get_loop(least);
4434 if( !chosen_loop->_child ) // Inner loop?
4435 chosen_loop->_body.push(n);// Collect inner loops
4436 }
4437
4438 #ifdef ASSERT
4439 void PhaseIdealLoop::dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA) {
4440 tty->print_cr("%s", msg);
4441 tty->print("n: "); n->dump();
4442 tty->print("early(n): "); early->dump();
4443 if (n->in(0) != NULL && !n->in(0)->is_top() &&
4444 n->in(0) != early && !n->in(0)->is_Root()) {
4445 tty->print("n->in(0): "); n->in(0)->dump();
4446 }
4447 for (uint i = 1; i < n->req(); i++) {
4448 Node* in1 = n->in(i);
4449 if (in1 != NULL && in1 != n && !in1->is_top()) {
4450 tty->print("n->in(%d): ", i); in1->dump();
4451 Node* in1_early = get_ctrl(in1);
4452 tty->print("early(n->in(%d)): ", i); in1_early->dump();
4453 if (in1->in(0) != NULL && !in1->in(0)->is_top() &&
4454 in1->in(0) != in1_early && !in1->in(0)->is_Root()) {
4455 tty->print("n->in(%d)->in(0): ", i); in1->in(0)->dump();
4456 }
4457 for (uint j = 1; j < in1->req(); j++) {
4458 Node* in2 = in1->in(j);
4459 if (in2 != NULL && in2 != n && in2 != in1 && !in2->is_top()) {
4460 tty->print("n->in(%d)->in(%d): ", i, j); in2->dump();
4461 Node* in2_early = get_ctrl(in2);
4462 tty->print("early(n->in(%d)->in(%d)): ", i, j); in2_early->dump();
4463 if (in2->in(0) != NULL && !in2->in(0)->is_top() &&
4464 in2->in(0) != in2_early && !in2->in(0)->is_Root()) {
4465 tty->print("n->in(%d)->in(%d)->in(0): ", i, j); in2->in(0)->dump();
4466 }
4467 }
4468 }
4469 }
4470 }
4471 tty->cr();
4472 tty->print("LCA(n): "); LCA->dump();
4473 for (uint i = 0; i < n->outcnt(); i++) {
4474 Node* u1 = n->raw_out(i);
4475 if (u1 == n)
4476 continue;
4477 tty->print("n->out(%d): ", i); u1->dump();
4478 if (u1->is_CFG()) {
4479 for (uint j = 0; j < u1->outcnt(); j++) {
4480 Node* u2 = u1->raw_out(j);
4481 if (u2 != u1 && u2 != n && u2->is_CFG()) {
4482 tty->print("n->out(%d)->out(%d): ", i, j); u2->dump();
4483 }
4484 }
4485 } else {
4486 Node* u1_later = get_ctrl(u1);
4487 tty->print("later(n->out(%d)): ", i); u1_later->dump();
4488 if (u1->in(0) != NULL && !u1->in(0)->is_top() &&
4489 u1->in(0) != u1_later && !u1->in(0)->is_Root()) {
4490 tty->print("n->out(%d)->in(0): ", i); u1->in(0)->dump();
4491 }
4492 for (uint j = 0; j < u1->outcnt(); j++) {
4493 Node* u2 = u1->raw_out(j);
4494 if (u2 == n || u2 == u1)
4495 continue;
4496 tty->print("n->out(%d)->out(%d): ", i, j); u2->dump();
4497 if (!u2->is_CFG()) {
4498 Node* u2_later = get_ctrl(u2);
4499 tty->print("later(n->out(%d)->out(%d)): ", i, j); u2_later->dump();
4500 if (u2->in(0) != NULL && !u2->in(0)->is_top() &&
4501 u2->in(0) != u2_later && !u2->in(0)->is_Root()) {
4502 tty->print("n->out(%d)->in(0): ", i); u2->in(0)->dump();
4503 }
4504 }
4505 }
4506 }
4507 }
4508 tty->cr();
4509 int ct = 0;
4510 Node *dbg_legal = LCA;
4511 while(!dbg_legal->is_Start() && ct < 100) {
4512 tty->print("idom[%d] ",ct); dbg_legal->dump();
4513 ct++;
4514 dbg_legal = idom(dbg_legal);
4515 }
4516 tty->cr();
4517 }
4518 #endif
4519
4520 #ifndef PRODUCT
4521 //------------------------------dump-------------------------------------------
4522 void PhaseIdealLoop::dump() const {
4523 ResourceMark rm;
4524 Arena* arena = Thread::current()->resource_area();
4525 Node_Stack stack(arena, C->live_nodes() >> 2);
4526 Node_List rpo_list;
4527 VectorSet visited(arena);
4528 visited.set(C->top()->_idx);
4529 rpo(C->root(), stack, visited, rpo_list);
4530 // Dump root loop indexed by last element in PO order
4531 dump(_ltree_root, rpo_list.size(), rpo_list);
4532 }
4533
4534 void PhaseIdealLoop::dump(IdealLoopTree* loop, uint idx, Node_List &rpo_list) const {
4535 loop->dump_head();
4536
4537 // Now scan for CFG nodes in the same loop
4538 for (uint j = idx; j > 0; j--) {
4539 Node* n = rpo_list[j-1];
4540 if (!_nodes[n->_idx]) // Skip dead nodes
4541 continue;
4542
4543 if (get_loop(n) != loop) { // Wrong loop nest
4544 if (get_loop(n)->_head == n && // Found nested loop?
4545 get_loop(n)->_parent == loop)
4546 dump(get_loop(n), rpo_list.size(), rpo_list); // Print it nested-ly
4547 continue;
4548 }
4549
4550 // Dump controlling node
4551 tty->sp(2 * loop->_nest);
4552 tty->print("C");
4553 if (n == C->root()) {
4554 n->dump();
4555 } else {
4556 Node* cached_idom = idom_no_update(n);
4557 Node* computed_idom = n->in(0);
4558 if (n->is_Region()) {
4559 computed_idom = compute_idom(n);
4560 // computed_idom() will return n->in(0) when idom(n) is an IfNode (or
4561 // any MultiBranch ctrl node), so apply a similar transform to
4562 // the cached idom returned from idom_no_update.
4563 cached_idom = find_non_split_ctrl(cached_idom);
4564 }
4565 tty->print(" ID:%d", computed_idom->_idx);
4566 n->dump();
4567 if (cached_idom != computed_idom) {
4568 tty->print_cr("*** BROKEN IDOM! Computed as: %d, cached as: %d",
4569 computed_idom->_idx, cached_idom->_idx);
4570 }
4571 }
4572 // Dump nodes it controls
4573 for (uint k = 0; k < _nodes.Size(); k++) {
4574 // (k < C->unique() && get_ctrl(find(k)) == n)
4575 if (k < C->unique() && _nodes[k] == (Node*)((intptr_t)n + 1)) {
4576 Node* m = C->root()->find(k);
4577 if (m && m->outcnt() > 0) {
4578 if (!(has_ctrl(m) && get_ctrl_no_update(m) == n)) {
4579 tty->print_cr("*** BROKEN CTRL ACCESSOR! _nodes[k] is %p, ctrl is %p",
4580 _nodes[k], has_ctrl(m) ? get_ctrl_no_update(m) : NULL);
4581 }
4582 tty->sp(2 * loop->_nest + 1);
4583 m->dump();
4584 }
4585 }
4586 }
4587 }
4588 }
4589 #endif
4590
4591 // Collect a R-P-O for the whole CFG.
4592 // Result list is in post-order (scan backwards for RPO)
4593 void PhaseIdealLoop::rpo(Node* start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list) const {
4594 stk.push(start, 0);
4595 visited.set(start->_idx);
4596
4597 while (stk.is_nonempty()) {
4598 Node* m = stk.node();
4599 uint idx = stk.index();
4600 if (idx < m->outcnt()) {
4601 stk.set_index(idx + 1);
4602 Node* n = m->raw_out(idx);
4603 if (n->is_CFG() && !visited.test_set(n->_idx)) {
4604 stk.push(n, 0);
4605 }
4606 } else {
4607 rpo_list.push(m);
4608 stk.pop();
4609 }
4610 }
4611 }
4612
4613
4614 //=============================================================================
4615 //------------------------------LoopTreeIterator-------------------------------
4616
4617 // Advance to next loop tree using a preorder, left-to-right traversal.
4618 void LoopTreeIterator::next() {
4619 assert(!done(), "must not be done.");
4620 if (_curnt->_child != NULL) {
4621 _curnt = _curnt->_child;
4622 } else if (_curnt->_next != NULL) {
4623 _curnt = _curnt->_next;
4624 } else {
4625 while (_curnt != _root && _curnt->_next == NULL) {
4626 _curnt = _curnt->_parent;
4627 }
4628 if (_curnt == _root) {
4629 _curnt = NULL;
4630 assert(done(), "must be done.");
4631 } else {
4632 assert(_curnt->_next != NULL, "must be more to do");
4633 _curnt = _curnt->_next;
4634 }
4635 }
4636 }