1 /*
2 * Copyright (c) 1998, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "ci/ciMethodData.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "libadt/vectset.hpp"
29 #include "memory/allocation.inline.hpp"
30 #include "memory/resourceArea.hpp"
31 #include "opto/addnode.hpp"
32 #include "opto/callnode.hpp"
33 #include "opto/connode.hpp"
34 #include "opto/convertnode.hpp"
35 #include "opto/divnode.hpp"
36 #include "opto/idealGraphPrinter.hpp"
37 #include "opto/loopnode.hpp"
38 #include "opto/mulnode.hpp"
39 #include "opto/opaquenode.hpp"
40 #include "opto/rootnode.hpp"
41 #include "opto/superword.hpp"
42
43 //=============================================================================
44 //------------------------------is_loop_iv-------------------------------------
45 // Determine if a node is Counted loop induction variable.
46 // The method is declared in node.hpp.
47 const Node* Node::is_loop_iv() const {
48 if (this->is_Phi() && !this->as_Phi()->is_copy() &&
49 this->as_Phi()->region()->is_CountedLoop() &&
50 this->as_Phi()->region()->as_CountedLoop()->phi() == this) {
51 return this;
52 } else {
53 return NULL;
54 }
55 }
56
57 //=============================================================================
58 //------------------------------dump_spec--------------------------------------
59 // Dump special per-node info
60 #ifndef PRODUCT
61 void LoopNode::dump_spec(outputStream *st) const {
62 if (is_inner_loop()) st->print( "inner " );
63 if (is_partial_peel_loop()) st->print( "partial_peel " );
64 if (partial_peel_has_failed()) st->print( "partial_peel_failed " );
65 }
66 #endif
67
68 //------------------------------is_valid_counted_loop-------------------------
69 bool LoopNode::is_valid_counted_loop() const {
70 if (is_CountedLoop()) {
71 CountedLoopNode* l = as_CountedLoop();
72 CountedLoopEndNode* le = l->loopexit();
73 if (le != NULL &&
74 le->proj_out(1 /* true */) == l->in(LoopNode::LoopBackControl)) {
75 Node* phi = l->phi();
76 Node* exit = le->proj_out(0 /* false */);
77 if (exit != NULL && exit->Opcode() == Op_IfFalse &&
78 phi != NULL && phi->is_Phi() &&
79 phi->in(LoopNode::LoopBackControl) == l->incr() &&
80 le->loopnode() == l && le->stride_is_con()) {
81 return true;
82 }
83 }
84 }
85 return false;
86 }
87
88 //------------------------------get_early_ctrl---------------------------------
89 // Compute earliest legal control
90 Node *PhaseIdealLoop::get_early_ctrl( Node *n ) {
91 assert( !n->is_Phi() && !n->is_CFG(), "this code only handles data nodes" );
92 uint i;
93 Node *early;
94 if (n->in(0) && !n->is_expensive()) {
95 early = n->in(0);
96 if (!early->is_CFG()) // Might be a non-CFG multi-def
97 early = get_ctrl(early); // So treat input as a straight data input
98 i = 1;
99 } else {
100 early = get_ctrl(n->in(1));
101 i = 2;
102 }
103 uint e_d = dom_depth(early);
104 assert( early, "" );
105 for (; i < n->req(); i++) {
106 Node *cin = get_ctrl(n->in(i));
107 assert( cin, "" );
108 // Keep deepest dominator depth
109 uint c_d = dom_depth(cin);
110 if (c_d > e_d) { // Deeper guy?
111 early = cin; // Keep deepest found so far
112 e_d = c_d;
113 } else if (c_d == e_d && // Same depth?
114 early != cin) { // If not equal, must use slower algorithm
115 // If same depth but not equal, one _must_ dominate the other
116 // and we want the deeper (i.e., dominated) guy.
117 Node *n1 = early;
118 Node *n2 = cin;
119 while (1) {
120 n1 = idom(n1); // Walk up until break cycle
121 n2 = idom(n2);
122 if (n1 == cin || // Walked early up to cin
123 dom_depth(n2) < c_d)
124 break; // early is deeper; keep him
125 if (n2 == early || // Walked cin up to early
126 dom_depth(n1) < c_d) {
127 early = cin; // cin is deeper; keep him
128 break;
129 }
130 }
131 e_d = dom_depth(early); // Reset depth register cache
132 }
133 }
134
135 // Return earliest legal location
136 assert(early == find_non_split_ctrl(early), "unexpected early control");
137
138 if (n->is_expensive() && !_verify_only && !_verify_me) {
139 assert(n->in(0), "should have control input");
140 early = get_early_ctrl_for_expensive(n, early);
141 }
142
143 return early;
144 }
145
146 //------------------------------get_early_ctrl_for_expensive---------------------------------
147 // Move node up the dominator tree as high as legal while still beneficial
148 Node *PhaseIdealLoop::get_early_ctrl_for_expensive(Node *n, Node* earliest) {
149 assert(n->in(0) && n->is_expensive(), "expensive node with control input here");
150 assert(OptimizeExpensiveOps, "optimization off?");
151
152 Node* ctl = n->in(0);
153 assert(ctl->is_CFG(), "expensive input 0 must be cfg");
154 uint min_dom_depth = dom_depth(earliest);
155 #ifdef ASSERT
156 if (!is_dominator(ctl, earliest) && !is_dominator(earliest, ctl)) {
157 dump_bad_graph("Bad graph detected in get_early_ctrl_for_expensive", n, earliest, ctl);
158 assert(false, "Bad graph detected in get_early_ctrl_for_expensive");
159 }
160 #endif
161 if (dom_depth(ctl) < min_dom_depth) {
162 return earliest;
163 }
164
165 while (1) {
166 Node *next = ctl;
167 // Moving the node out of a loop on the projection of a If
168 // confuses loop predication. So once we hit a Loop in a If branch
169 // that doesn't branch to an UNC, we stop. The code that process
170 // expensive nodes will notice the loop and skip over it to try to
171 // move the node further up.
172 if (ctl->is_CountedLoop() && ctl->in(1) != NULL && ctl->in(1)->in(0) != NULL && ctl->in(1)->in(0)->is_If()) {
173 if (!ctl->in(1)->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) {
174 break;
175 }
176 next = idom(ctl->in(1)->in(0));
177 } else if (ctl->is_Proj()) {
178 // We only move it up along a projection if the projection is
179 // the single control projection for its parent: same code path,
180 // if it's a If with UNC or fallthrough of a call.
181 Node* parent_ctl = ctl->in(0);
182 if (parent_ctl == NULL) {
183 break;
184 } else if (parent_ctl->is_CountedLoopEnd() && parent_ctl->as_CountedLoopEnd()->loopnode() != NULL) {
185 next = parent_ctl->as_CountedLoopEnd()->loopnode()->init_control();
186 } else if (parent_ctl->is_If()) {
187 if (!ctl->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) {
188 break;
189 }
190 assert(idom(ctl) == parent_ctl, "strange");
191 next = idom(parent_ctl);
192 } else if (ctl->is_CatchProj()) {
193 if (ctl->as_Proj()->_con != CatchProjNode::fall_through_index) {
194 break;
195 }
196 assert(parent_ctl->in(0)->in(0)->is_Call(), "strange graph");
197 next = parent_ctl->in(0)->in(0)->in(0);
198 } else {
199 // Check if parent control has a single projection (this
200 // control is the only possible successor of the parent
201 // control). If so, we can try to move the node above the
202 // parent control.
203 int nb_ctl_proj = 0;
204 for (DUIterator_Fast imax, i = parent_ctl->fast_outs(imax); i < imax; i++) {
205 Node *p = parent_ctl->fast_out(i);
206 if (p->is_Proj() && p->is_CFG()) {
207 nb_ctl_proj++;
208 if (nb_ctl_proj > 1) {
209 break;
210 }
211 }
212 }
213
214 if (nb_ctl_proj > 1) {
215 break;
216 }
217 assert(parent_ctl->is_Start() || parent_ctl->is_MemBar() || parent_ctl->is_Call(), "unexpected node");
218 assert(idom(ctl) == parent_ctl, "strange");
219 next = idom(parent_ctl);
220 }
221 } else {
222 next = idom(ctl);
223 }
224 if (next->is_Root() || next->is_Start() || dom_depth(next) < min_dom_depth) {
225 break;
226 }
227 ctl = next;
228 }
229
230 if (ctl != n->in(0)) {
231 _igvn.replace_input_of(n, 0, ctl);
232 _igvn.hash_insert(n);
233 }
234
235 return ctl;
236 }
237
238
239 //------------------------------set_early_ctrl---------------------------------
240 // Set earliest legal control
241 void PhaseIdealLoop::set_early_ctrl( Node *n ) {
242 Node *early = get_early_ctrl(n);
243
244 // Record earliest legal location
245 set_ctrl(n, early);
246 }
247
248 //------------------------------set_subtree_ctrl-------------------------------
249 // set missing _ctrl entries on new nodes
250 void PhaseIdealLoop::set_subtree_ctrl( Node *n ) {
251 // Already set? Get out.
252 if( _nodes[n->_idx] ) return;
253 // Recursively set _nodes array to indicate where the Node goes
254 uint i;
255 for( i = 0; i < n->req(); ++i ) {
256 Node *m = n->in(i);
257 if( m && m != C->root() )
258 set_subtree_ctrl( m );
259 }
260
261 // Fixup self
262 set_early_ctrl( n );
263 }
264
265 // Create a skeleton strip mined outer loop: a Loop head before the
266 // inner strip mined loop, a safepoint and an exit condition guarded
267 // by an opaque node after the inner strip mined loop with a backedge
268 // to the loop head. The inner strip mined loop is left as it is. Only
269 // once loop optimizations are over, do we adjust the inner loop exit
270 // condition to limit its number of iterations, set the outer loop
271 // exit condition and add Phis to the outer loop head. Some loop
272 // optimizations that operate on the inner strip mined loop need to be
273 // aware of the outer strip mined loop: loop unswitching needs to
274 // clone the outer loop as well as the inner, unrolling needs to only
275 // clone the inner loop etc. No optimizations need to change the outer
276 // strip mined loop as it is only a skeleton.
277 IdealLoopTree* PhaseIdealLoop::create_outer_strip_mined_loop(BoolNode *test, Node *cmp, Node *init_control,
278 IdealLoopTree* loop, float cl_prob, float le_fcnt,
279 Node*& entry_control, Node*& iffalse) {
280 Node* outer_test = test->clone();
281 Node* outer_cmp = cmp->clone();
282 Node* outer_limit = new Opaque5Node(C, outer_cmp->in(2));
283 outer_cmp->set_req(2, outer_limit);
284 outer_test->set_req(1, outer_cmp);
285 Node *orig = iffalse;
286 iffalse = iffalse->clone();
287 _igvn.register_new_node_with_optimizer(iffalse);
288 set_idom(iffalse, idom(orig), dom_depth(orig));
289
290 IfNode *outer_le = new IfNode(iffalse, outer_test, cl_prob, le_fcnt);
291 Node *outer_ift = new IfTrueNode (outer_le);
292 Node* outer_iff = orig;
293 _igvn.replace_input_of(outer_iff, 0, outer_le);
294
295 LoopNode *outer_l = new LoopNode(init_control, outer_ift);
296 entry_control = outer_l;
297
298 IdealLoopTree* outer_ilt = new IdealLoopTree(this, outer_l, outer_ift);
299 IdealLoopTree* parent = loop->_parent;
300 IdealLoopTree* sibling = parent->_child;
301 if (sibling == loop) {
302 parent->_child = outer_ilt;
303 } else {
304 while (sibling->_next != loop) {
305 sibling = sibling->_next;
306 }
307 sibling->_next = outer_ilt;
308 }
309 outer_ilt->_next = loop->_next;
310 outer_ilt->_parent = parent;
311 outer_ilt->_child = loop;
312 outer_ilt->_nest = loop->_nest;
313 loop->_parent = outer_ilt;
314 loop->_next = NULL;
315 loop->_nest++;
316
317 set_loop(iffalse, outer_ilt);
318 register_new_node(outer_test, iffalse);
319 register_new_node(outer_cmp, iffalse);
320 register_new_node(outer_limit, iffalse);
321 register_control(outer_le, outer_ilt, iffalse);
322 register_control(outer_ift, outer_ilt, outer_le);
323 set_idom(outer_iff, outer_le, dom_depth(outer_le));
324 _igvn.register_new_node_with_optimizer(outer_l);
325 set_loop(outer_l, outer_ilt);
326 set_idom(outer_l, init_control, dom_depth(init_control)+1);
327 outer_l->mark_strip_mined();
328
329 return outer_ilt;
330 }
331
332 //------------------------------is_counted_loop--------------------------------
333 bool PhaseIdealLoop::is_counted_loop(Node* x, IdealLoopTree*& loop) {
334 PhaseGVN *gvn = &_igvn;
335
336 // Counted loop head must be a good RegionNode with only 3 not NULL
337 // control input edges: Self, Entry, LoopBack.
338 if (x->in(LoopNode::Self) == NULL || x->req() != 3 || loop->_irreducible) {
339 return false;
340 }
341 Node *init_control = x->in(LoopNode::EntryControl);
342 Node *back_control = x->in(LoopNode::LoopBackControl);
343 if (init_control == NULL || back_control == NULL) // Partially dead
344 return false;
345 // Must also check for TOP when looking for a dead loop
346 if (init_control->is_top() || back_control->is_top())
347 return false;
348
349 // Allow funny placement of Safepoint
350 if (back_control->Opcode() == Op_SafePoint) {
351 if (LoopStripMiningIter != 0) {
352 // Leaving the safepoint on the backedge and creating a
353 // CountedLoop will confuse optimizations. We can't move the
354 // safepoint around because its jvm state wouldn't match a new
355 // location. Give up on that loop.
356 return false;
357 }
358 back_control = back_control->in(TypeFunc::Control);
359 }
360
361 // Controlling test for loop
362 Node *iftrue = back_control;
363 uint iftrue_op = iftrue->Opcode();
364 if (iftrue_op != Op_IfTrue &&
365 iftrue_op != Op_IfFalse)
366 // I have a weird back-control. Probably the loop-exit test is in
367 // the middle of the loop and I am looking at some trailing control-flow
368 // merge point. To fix this I would have to partially peel the loop.
369 return false; // Obscure back-control
370
371 // Get boolean guarding loop-back test
372 Node *iff = iftrue->in(0);
373 if (get_loop(iff) != loop || !iff->in(1)->is_Bool())
374 return false;
375 BoolNode *test = iff->in(1)->as_Bool();
376 BoolTest::mask bt = test->_test._test;
377 float cl_prob = iff->as_If()->_prob;
378 if (iftrue_op == Op_IfFalse) {
379 bt = BoolTest(bt).negate();
380 cl_prob = 1.0 - cl_prob;
381 }
382 // Get backedge compare
383 Node *cmp = test->in(1);
384 int cmp_op = cmp->Opcode();
385 if (cmp_op != Op_CmpI)
386 return false; // Avoid pointer & float compares
387
388 // Find the trip-counter increment & limit. Limit must be loop invariant.
389 Node *incr = cmp->in(1);
390 Node *limit = cmp->in(2);
391
392 // ---------
393 // need 'loop()' test to tell if limit is loop invariant
394 // ---------
395
396 if (!is_member(loop, get_ctrl(incr))) { // Swapped trip counter and limit?
397 Node *tmp = incr; // Then reverse order into the CmpI
398 incr = limit;
399 limit = tmp;
400 bt = BoolTest(bt).commute(); // And commute the exit test
401 }
402 if (is_member(loop, get_ctrl(limit))) // Limit must be loop-invariant
403 return false;
404 if (!is_member(loop, get_ctrl(incr))) // Trip counter must be loop-variant
405 return false;
406
407 Node* phi_incr = NULL;
408 // Trip-counter increment must be commutative & associative.
409 if (incr->Opcode() == Op_CastII) {
410 incr = incr->in(1);
411 }
412 if (incr->is_Phi()) {
413 if (incr->as_Phi()->region() != x || incr->req() != 3)
414 return false; // Not simple trip counter expression
415 phi_incr = incr;
416 incr = phi_incr->in(LoopNode::LoopBackControl); // Assume incr is on backedge of Phi
417 if (!is_member(loop, get_ctrl(incr))) // Trip counter must be loop-variant
418 return false;
419 }
420
421 Node* trunc1 = NULL;
422 Node* trunc2 = NULL;
423 const TypeInt* iv_trunc_t = NULL;
424 if (!(incr = CountedLoopNode::match_incr_with_optional_truncation(incr, &trunc1, &trunc2, &iv_trunc_t))) {
425 return false; // Funny increment opcode
426 }
427 assert(incr->Opcode() == Op_AddI, "wrong increment code");
428
429 // Get merge point
430 Node *xphi = incr->in(1);
431 Node *stride = incr->in(2);
432 if (!stride->is_Con()) { // Oops, swap these
433 if (!xphi->is_Con()) // Is the other guy a constant?
434 return false; // Nope, unknown stride, bail out
435 Node *tmp = xphi; // 'incr' is commutative, so ok to swap
436 xphi = stride;
437 stride = tmp;
438 }
439 if (xphi->Opcode() == Op_CastII) {
440 xphi = xphi->in(1);
441 }
442 // Stride must be constant
443 int stride_con = stride->get_int();
444 if (stride_con == 0)
445 return false; // missed some peephole opt
446
447 if (!xphi->is_Phi())
448 return false; // Too much math on the trip counter
449 if (phi_incr != NULL && phi_incr != xphi)
450 return false;
451 PhiNode *phi = xphi->as_Phi();
452
453 // Phi must be of loop header; backedge must wrap to increment
454 if (phi->region() != x)
455 return false;
456 if ((trunc1 == NULL && phi->in(LoopNode::LoopBackControl) != incr) ||
457 (trunc1 != NULL && phi->in(LoopNode::LoopBackControl) != trunc1)) {
458 return false;
459 }
460 Node *init_trip = phi->in(LoopNode::EntryControl);
461
462 // If iv trunc type is smaller than int, check for possible wrap.
463 if (!TypeInt::INT->higher_equal(iv_trunc_t)) {
464 assert(trunc1 != NULL, "must have found some truncation");
465
466 // Get a better type for the phi (filtered thru if's)
467 const TypeInt* phi_ft = filtered_type(phi);
468
469 // Can iv take on a value that will wrap?
470 //
471 // Ensure iv's limit is not within "stride" of the wrap value.
472 //
473 // Example for "short" type
474 // Truncation ensures value is in the range -32768..32767 (iv_trunc_t)
475 // If the stride is +10, then the last value of the induction
476 // variable before the increment (phi_ft->_hi) must be
477 // <= 32767 - 10 and (phi_ft->_lo) must be >= -32768 to
478 // ensure no truncation occurs after the increment.
479
480 if (stride_con > 0) {
481 if (iv_trunc_t->_hi - phi_ft->_hi < stride_con ||
482 iv_trunc_t->_lo > phi_ft->_lo) {
483 return false; // truncation may occur
484 }
485 } else if (stride_con < 0) {
486 if (iv_trunc_t->_lo - phi_ft->_lo > stride_con ||
487 iv_trunc_t->_hi < phi_ft->_hi) {
488 return false; // truncation may occur
489 }
490 }
491 // No possibility of wrap so truncation can be discarded
492 // Promote iv type to Int
493 } else {
494 assert(trunc1 == NULL && trunc2 == NULL, "no truncation for int");
495 }
496
497 // If the condition is inverted and we will be rolling
498 // through MININT to MAXINT, then bail out.
499 if (bt == BoolTest::eq || // Bail out, but this loop trips at most twice!
500 // Odd stride
501 (bt == BoolTest::ne && stride_con != 1 && stride_con != -1) ||
502 // Count down loop rolls through MAXINT
503 ((bt == BoolTest::le || bt == BoolTest::lt) && stride_con < 0) ||
504 // Count up loop rolls through MININT
505 ((bt == BoolTest::ge || bt == BoolTest::gt) && stride_con > 0)) {
506 return false; // Bail out
507 }
508
509 const TypeInt* init_t = gvn->type(init_trip)->is_int();
510 const TypeInt* limit_t = gvn->type(limit)->is_int();
511
512 if (stride_con > 0) {
513 jlong init_p = (jlong)init_t->_lo + stride_con;
514 if (init_p > (jlong)max_jint || init_p > (jlong)limit_t->_hi)
515 return false; // cyclic loop or this loop trips only once
516 } else {
517 jlong init_p = (jlong)init_t->_hi + stride_con;
518 if (init_p < (jlong)min_jint || init_p < (jlong)limit_t->_lo)
519 return false; // cyclic loop or this loop trips only once
520 }
521
522 if (phi_incr != NULL) {
523 // check if there is a possiblity of IV overflowing after the first increment
524 if (stride_con > 0) {
525 if (init_t->_hi > max_jint - stride_con) {
526 return false;
527 }
528 } else {
529 if (init_t->_lo < min_jint - stride_con) {
530 return false;
531 }
532 }
533 }
534
535 // =================================================
536 // ---- SUCCESS! Found A Trip-Counted Loop! -----
537 //
538 assert(x->Opcode() == Op_Loop, "regular loops only");
539 C->print_method(PHASE_BEFORE_CLOOPS, 3);
540
541 Node *hook = new Node(6);
542
543 // ===================================================
544 // Generate loop limit check to avoid integer overflow
545 // in cases like next (cyclic loops):
546 //
547 // for (i=0; i <= max_jint; i++) {}
548 // for (i=0; i < max_jint; i+=2) {}
549 //
550 //
551 // Limit check predicate depends on the loop test:
552 //
553 // for(;i != limit; i++) --> limit <= (max_jint)
554 // for(;i < limit; i+=stride) --> limit <= (max_jint - stride + 1)
555 // for(;i <= limit; i+=stride) --> limit <= (max_jint - stride )
556 //
557
558 // Check if limit is excluded to do more precise int overflow check.
559 bool incl_limit = (bt == BoolTest::le || bt == BoolTest::ge);
560 int stride_m = stride_con - (incl_limit ? 0 : (stride_con > 0 ? 1 : -1));
561
562 // If compare points directly to the phi we need to adjust
563 // the compare so that it points to the incr. Limit have
564 // to be adjusted to keep trip count the same and the
565 // adjusted limit should be checked for int overflow.
566 if (phi_incr != NULL) {
567 stride_m += stride_con;
568 }
569
570 if (limit->is_Con()) {
571 int limit_con = limit->get_int();
572 if ((stride_con > 0 && limit_con > (max_jint - stride_m)) ||
573 (stride_con < 0 && limit_con < (min_jint - stride_m))) {
574 // Bailout: it could be integer overflow.
575 return false;
576 }
577 } else if ((stride_con > 0 && limit_t->_hi <= (max_jint - stride_m)) ||
578 (stride_con < 0 && limit_t->_lo >= (min_jint - stride_m))) {
579 // Limit's type may satisfy the condition, for example,
580 // when it is an array length.
581 } else {
582 // Generate loop's limit check.
583 // Loop limit check predicate should be near the loop.
584 ProjNode *limit_check_proj = find_predicate_insertion_point(init_control, Deoptimization::Reason_loop_limit_check);
585 if (!limit_check_proj) {
586 // The limit check predicate is not generated if this method trapped here before.
587 #ifdef ASSERT
588 if (TraceLoopLimitCheck) {
589 tty->print("missing loop limit check:");
590 loop->dump_head();
591 x->dump(1);
592 }
593 #endif
594 return false;
595 }
596
597 IfNode* check_iff = limit_check_proj->in(0)->as_If();
598 Node* cmp_limit;
599 Node* bol;
600
601 if (stride_con > 0) {
602 cmp_limit = new CmpINode(limit, _igvn.intcon(max_jint - stride_m));
603 bol = new BoolNode(cmp_limit, BoolTest::le);
604 } else {
605 cmp_limit = new CmpINode(limit, _igvn.intcon(min_jint - stride_m));
606 bol = new BoolNode(cmp_limit, BoolTest::ge);
607 }
608 cmp_limit = _igvn.register_new_node_with_optimizer(cmp_limit);
609 bol = _igvn.register_new_node_with_optimizer(bol);
610 set_subtree_ctrl(bol);
611
612 // Replace condition in original predicate but preserve Opaque node
613 // so that previous predicates could be found.
614 assert(check_iff->in(1)->Opcode() == Op_Conv2B &&
615 check_iff->in(1)->in(1)->Opcode() == Op_Opaque1, "");
616 Node* opq = check_iff->in(1)->in(1);
617 _igvn.replace_input_of(opq, 1, bol);
618 // Update ctrl.
619 set_ctrl(opq, check_iff->in(0));
620 set_ctrl(check_iff->in(1), check_iff->in(0));
621
622 #ifndef PRODUCT
623 // report that the loop predication has been actually performed
624 // for this loop
625 if (TraceLoopLimitCheck) {
626 tty->print_cr("Counted Loop Limit Check generated:");
627 debug_only( bol->dump(2); )
628 }
629 #endif
630 }
631
632 if (phi_incr != NULL) {
633 // If compare points directly to the phi we need to adjust
634 // the compare so that it points to the incr. Limit have
635 // to be adjusted to keep trip count the same and we
636 // should avoid int overflow.
637 //
638 // i = init; do {} while(i++ < limit);
639 // is converted to
640 // i = init; do {} while(++i < limit+1);
641 //
642 limit = gvn->transform(new AddINode(limit, stride));
643 }
644
645 // Now we need to canonicalize loop condition.
646 if (bt == BoolTest::ne) {
647 assert(stride_con == 1 || stride_con == -1, "simple increment only");
648 // 'ne' can be replaced with 'lt' only when init < limit.
649 if (stride_con > 0 && init_t->_hi < limit_t->_lo)
650 bt = BoolTest::lt;
651 // 'ne' can be replaced with 'gt' only when init > limit.
652 if (stride_con < 0 && init_t->_lo > limit_t->_hi)
653 bt = BoolTest::gt;
654 }
655
656 if (incl_limit) {
657 // The limit check guaranties that 'limit <= (max_jint - stride)' so
658 // we can convert 'i <= limit' to 'i < limit+1' since stride != 0.
659 //
660 Node* one = (stride_con > 0) ? gvn->intcon( 1) : gvn->intcon(-1);
661 limit = gvn->transform(new AddINode(limit, one));
662 if (bt == BoolTest::le)
663 bt = BoolTest::lt;
664 else if (bt == BoolTest::ge)
665 bt = BoolTest::gt;
666 else
667 ShouldNotReachHere();
668 }
669 set_subtree_ctrl( limit );
670
671 if (LoopStripMiningIter == 0) {
672 // Check for SafePoint on backedge and remove
673 Node *sfpt = x->in(LoopNode::LoopBackControl);
674 if (sfpt->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt)) {
675 lazy_replace( sfpt, iftrue );
676 if (loop->_safepts != NULL) {
677 loop->_safepts->yank(sfpt);
678 }
679 loop->_tail = iftrue;
680 }
681 }
682
683 // Build a canonical trip test.
684 // Clone code, as old values may be in use.
685 incr = incr->clone();
686 incr->set_req(1,phi);
687 incr->set_req(2,stride);
688 incr = _igvn.register_new_node_with_optimizer(incr);
689 set_early_ctrl( incr );
690 _igvn.rehash_node_delayed(phi);
691 phi->set_req_X( LoopNode::LoopBackControl, incr, &_igvn );
692
693 // If phi type is more restrictive than Int, raise to
694 // Int to prevent (almost) infinite recursion in igvn
695 // which can only handle integer types for constants or minint..maxint.
696 if (!TypeInt::INT->higher_equal(phi->bottom_type())) {
697 Node* nphi = PhiNode::make(phi->in(0), phi->in(LoopNode::EntryControl), TypeInt::INT);
698 nphi->set_req(LoopNode::LoopBackControl, phi->in(LoopNode::LoopBackControl));
699 nphi = _igvn.register_new_node_with_optimizer(nphi);
700 set_ctrl(nphi, get_ctrl(phi));
701 _igvn.replace_node(phi, nphi);
702 phi = nphi->as_Phi();
703 }
704 cmp = cmp->clone();
705 cmp->set_req(1,incr);
706 cmp->set_req(2,limit);
707 cmp = _igvn.register_new_node_with_optimizer(cmp);
708 set_ctrl(cmp, iff->in(0));
709
710 test = test->clone()->as_Bool();
711 (*(BoolTest*)&test->_test)._test = bt;
712 test->set_req(1,cmp);
713 _igvn.register_new_node_with_optimizer(test);
714 set_ctrl(test, iff->in(0));
715
716 // Replace the old IfNode with a new LoopEndNode
717 Node *lex = _igvn.register_new_node_with_optimizer(new CountedLoopEndNode( iff->in(0), test, cl_prob, iff->as_If()->_fcnt ));
718 IfNode *le = lex->as_If();
719 uint dd = dom_depth(iff);
720 set_idom(le, le->in(0), dd); // Update dominance for loop exit
721 set_loop(le, loop);
722
723 // Get the loop-exit control
724 Node *iffalse = iff->as_If()->proj_out(!(iftrue_op == Op_IfTrue));
725
726 // Need to swap loop-exit and loop-back control?
727 if (iftrue_op == Op_IfFalse) {
728 Node *ift2=_igvn.register_new_node_with_optimizer(new IfTrueNode (le));
729 Node *iff2=_igvn.register_new_node_with_optimizer(new IfFalseNode(le));
730
731 loop->_tail = back_control = ift2;
732 set_loop(ift2, loop);
733 set_loop(iff2, get_loop(iffalse));
734
735 // Lazy update of 'get_ctrl' mechanism.
736 lazy_replace(iffalse, iff2);
737 lazy_replace(iftrue, ift2);
738
739 // Swap names
740 iffalse = iff2;
741 iftrue = ift2;
742 } else {
743 _igvn.rehash_node_delayed(iffalse);
744 _igvn.rehash_node_delayed(iftrue);
745 iffalse->set_req_X( 0, le, &_igvn );
746 iftrue ->set_req_X( 0, le, &_igvn );
747 }
748
749 set_idom(iftrue, le, dd+1);
750 set_idom(iffalse, le, dd+1);
751 assert(iff->outcnt() == 0, "should be dead now");
752 lazy_replace( iff, le ); // fix 'get_ctrl'
753
754 Node *sfpt2 = le->in(0);
755
756 Node* entry_control = init_control;
757 bool strip_mine_loop = LoopStripMiningIter > 1 && loop->_child == NULL &&
758 sfpt2->Opcode() == Op_SafePoint && !loop->_has_call;
759 IdealLoopTree* outer_ilt = NULL;
760 if (strip_mine_loop) {
761 outer_ilt = create_outer_strip_mined_loop(test, cmp, init_control, loop,
762 cl_prob, le->_fcnt, entry_control,
763 iffalse);
764 }
765
766 // Now setup a new CountedLoopNode to replace the existing LoopNode
767 CountedLoopNode *l = new CountedLoopNode(entry_control, back_control);
768 l->set_unswitch_count(x->as_Loop()->unswitch_count()); // Preserve
769 // The following assert is approximately true, and defines the intention
770 // of can_be_counted_loop. It fails, however, because phase->type
771 // is not yet initialized for this loop and its parts.
772 //assert(l->can_be_counted_loop(this), "sanity");
773 _igvn.register_new_node_with_optimizer(l);
774 set_loop(l, loop);
775 loop->_head = l;
776 // Fix all data nodes placed at the old loop head.
777 // Uses the lazy-update mechanism of 'get_ctrl'.
778 lazy_replace( x, l );
779 set_idom(l, entry_control, dom_depth(entry_control) + 1);
780
781 if (LoopStripMiningIter == 0 || strip_mine_loop) {
782 // Check for immediately preceding SafePoint and remove
783 if (sfpt2->Opcode() == Op_SafePoint && (LoopStripMiningIter != 0 || is_deleteable_safept(sfpt2))) {
784 if (strip_mine_loop) {
785 Node* outer_le = outer_ilt->_tail->in(0);
786 Node* outer_limit = outer_le->in(1)->in(1)->in(2);
787 assert(outer_limit->Opcode() == Op_Opaque5, "where's the opaque node?");
788 Node* sfpt = sfpt2->clone();
789 sfpt->set_req(0, iffalse);
790 outer_le->set_req(0, sfpt);
791 outer_limit->set_req(0, sfpt);
792 register_control(sfpt, outer_ilt, iffalse);
793 set_idom(outer_le, sfpt, dom_depth(sfpt));
794 }
795 lazy_replace( sfpt2, sfpt2->in(TypeFunc::Control));
796 if (loop->_safepts != NULL) {
797 loop->_safepts->yank(sfpt2);
798 }
799 }
800 }
801
802 // Free up intermediate goo
803 _igvn.remove_dead_node(hook);
804
805 #ifdef ASSERT
806 assert(l->is_valid_counted_loop(), "counted loop shape is messed up");
807 assert(l == loop->_head && l->phi() == phi && l->loopexit() == lex, "" );
808 #endif
809 #ifndef PRODUCT
810 if (TraceLoopOpts) {
811 tty->print("Counted ");
812 loop->dump_head();
813 }
814 #endif
815
816 C->print_method(PHASE_AFTER_CLOOPS, 3);
817
818 // Capture bounds of the loop in the induction variable Phi before
819 // subsequent transformation (iteration splitting) obscures the
820 // bounds
821 l->phi()->as_Phi()->set_type(l->phi()->Value(&_igvn));
822
823 if (strip_mine_loop) {
824 l->mark_strip_mined();
825 l->verify_strip_mined(1);
826 outer_ilt->_head->as_Loop()->verify_strip_mined(1);
827 loop = outer_ilt;
828 }
829
830 return true;
831 }
832
833 //----------------------exact_limit-------------------------------------------
834 Node* PhaseIdealLoop::exact_limit( IdealLoopTree *loop ) {
835 assert(loop->_head->is_CountedLoop(), "");
836 CountedLoopNode *cl = loop->_head->as_CountedLoop();
837 assert(cl->is_valid_counted_loop(), "");
838
839 if (ABS(cl->stride_con()) == 1 ||
840 cl->limit()->Opcode() == Op_LoopLimit) {
841 // Old code has exact limit (it could be incorrect in case of int overflow).
842 // Loop limit is exact with stride == 1. And loop may already have exact limit.
843 return cl->limit();
844 }
845 Node *limit = NULL;
846 #ifdef ASSERT
847 BoolTest::mask bt = cl->loopexit()->test_trip();
848 assert(bt == BoolTest::lt || bt == BoolTest::gt, "canonical test is expected");
849 #endif
850 if (cl->has_exact_trip_count()) {
851 // Simple case: loop has constant boundaries.
852 // Use jlongs to avoid integer overflow.
853 int stride_con = cl->stride_con();
854 jlong init_con = cl->init_trip()->get_int();
855 jlong limit_con = cl->limit()->get_int();
856 julong trip_cnt = cl->trip_count();
857 jlong final_con = init_con + trip_cnt*stride_con;
858 int final_int = (int)final_con;
859 // The final value should be in integer range since the loop
860 // is counted and the limit was checked for overflow.
861 assert(final_con == (jlong)final_int, "final value should be integer");
862 limit = _igvn.intcon(final_int);
863 } else {
864 // Create new LoopLimit node to get exact limit (final iv value).
865 limit = new LoopLimitNode(C, cl->init_trip(), cl->limit(), cl->stride());
866 register_new_node(limit, cl->in(LoopNode::EntryControl));
867 }
868 assert(limit != NULL, "sanity");
869 return limit;
870 }
871
872 //------------------------------Ideal------------------------------------------
873 // Return a node which is more "ideal" than the current node.
874 // Attempt to convert into a counted-loop.
875 Node *LoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
876 if (!can_be_counted_loop(phase) && !is_strip_mined()) {
877 phase->C->set_major_progress();
878 }
879 return RegionNode::Ideal(phase, can_reshape);
880 }
881
882 void LoopNode::verify_strip_mined(int expect_opaq) const {
883 #ifdef ASSERT
884 if (is_strip_mined()) {
885 const LoopNode* outer = NULL;
886 const CountedLoopNode* inner = NULL;
887 if (is_CountedLoop()) {
888 inner = as_CountedLoop();
889 outer = inner->in(LoopNode::EntryControl)->as_Loop();
890 } else {
891 outer = this;
892 inner = outer->unique_ctrl_out()->as_CountedLoop();
893 }
894 assert(outer->Opcode() == Op_Loop, "no counted loop here");
895 assert(outer->is_strip_mined(), "incorrect outer loop");
896 Node* outer_tail = outer->in(LoopNode::LoopBackControl);
897 Node* outer_le = outer_tail->in(0);
898 assert(outer_le->Opcode() == Op_If, "tail of outer loop should be an If");
899 Node* sfpt = outer_le->in(0);
900 assert(sfpt->Opcode() == Op_SafePoint, "where's the safepoint?");
901 Node* inner_out = sfpt->in(0);
902 if (inner_out->outcnt() != 1) {
903 ResourceMark rm;
904 Unique_Node_List wq;
905
906 for (DUIterator_Fast imax, i = inner_out->fast_outs(imax); i < imax; i++) {
907 Node* u = inner_out->fast_out(i);
908 if (u == sfpt) {
909 continue;
910 }
911 wq.clear();
912 wq.push(u);
913 bool found_sfpt = false;
914 for (uint next = 0; next < wq.size() && !found_sfpt; next++) {
915 Node *n = wq.at(next);
916 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax && !found_sfpt; i++) {
917 Node* u = n->fast_out(i);
918 if (u == sfpt) {
919 found_sfpt = true;
920 }
921 if (!u->is_CFG()) {
922 wq.push(u);
923 }
924 }
925 }
926 assert(found_sfpt, "no node in loop that's not input to safepoint");
927 }
928 }
929 CountedLoopEndNode* cle = inner_out->in(0)->as_CountedLoopEnd();
930 assert(cle == inner->loopexit(), "mismatch");
931 Node* cmp = outer_le->in(1)->in(1);
932 bool has_opaque = cmp->in(2)->Opcode() == Op_Opaque5;
933 assert(cmp->in(1) == inner->incr(), "strange exit condition");
934 if (has_opaque) {
935 assert(expect_opaq == 1 || expect_opaq == -1, "unexpected opaque node");
936 assert(outer->outcnt() == 2, "only phis");
937 } else {
938 assert(expect_opaq == 0 || expect_opaq == -1, "no opaque node?");
939 uint phis = 0;
940 for (DUIterator_Fast imax, i = inner->fast_outs(imax); i < imax; i++) {
941 Node* u = inner->fast_out(i);
942 if (u->is_Phi()) {
943 phis++;
944 }
945 }
946 for (DUIterator_Fast imax, i = outer->fast_outs(imax); i < imax; i++) {
947 Node* u = outer->fast_out(i);
948 assert(u == outer || u == inner || u->is_Phi(), "nothing between inner and outer loop");
949 }
950 uint stores = 0;
951 for (DUIterator_Fast imax, i = inner_out->fast_outs(imax); i < imax; i++) {
952 Node* u = inner_out->fast_out(i);
953 if (u->is_Store()) {
954 stores++;
955 }
956 }
957 assert(outer->outcnt() >= phis + 2 && outer->outcnt() <= phis + 2 + stores + 1, "only phis");
958 }
959 assert(sfpt->outcnt() == 1 + (has_opaque ? 1 : 0), "no data node");
960 assert(outer_tail->outcnt() == 1 || !has_opaque, "no data node");
961 }
962 #endif
963 }
964
965 //=============================================================================
966 //------------------------------Ideal------------------------------------------
967 // Return a node which is more "ideal" than the current node.
968 // Attempt to convert into a counted-loop.
969 Node *CountedLoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
970 return RegionNode::Ideal(phase, can_reshape);
971 }
972
973 //------------------------------dump_spec--------------------------------------
974 // Dump special per-node info
975 #ifndef PRODUCT
976 void CountedLoopNode::dump_spec(outputStream *st) const {
977 LoopNode::dump_spec(st);
978 if (stride_is_con()) {
979 st->print("stride: %d ",stride_con());
980 }
981 if (is_pre_loop ()) st->print("pre of N%d" , _main_idx);
982 if (is_main_loop()) st->print("main of N%d", _idx);
983 if (is_post_loop()) st->print("post of N%d", _main_idx);
984 }
985 #endif
986
987 //=============================================================================
988 int CountedLoopEndNode::stride_con() const {
989 return stride()->bottom_type()->is_int()->get_con();
990 }
991
992 //=============================================================================
993 //------------------------------Value-----------------------------------------
994 const Type* LoopLimitNode::Value(PhaseGVN* phase) const {
995 const Type* init_t = phase->type(in(Init));
996 const Type* limit_t = phase->type(in(Limit));
997 const Type* stride_t = phase->type(in(Stride));
998 // Either input is TOP ==> the result is TOP
999 if (init_t == Type::TOP) return Type::TOP;
1000 if (limit_t == Type::TOP) return Type::TOP;
1001 if (stride_t == Type::TOP) return Type::TOP;
1002
1003 int stride_con = stride_t->is_int()->get_con();
1004 if (stride_con == 1)
1005 return NULL; // Identity
1006
1007 if (init_t->is_int()->is_con() && limit_t->is_int()->is_con()) {
1008 // Use jlongs to avoid integer overflow.
1009 jlong init_con = init_t->is_int()->get_con();
1010 jlong limit_con = limit_t->is_int()->get_con();
1011 int stride_m = stride_con - (stride_con > 0 ? 1 : -1);
1012 jlong trip_count = (limit_con - init_con + stride_m)/stride_con;
1013 jlong final_con = init_con + stride_con*trip_count;
1014 int final_int = (int)final_con;
1015 // The final value should be in integer range since the loop
1016 // is counted and the limit was checked for overflow.
1017 assert(final_con == (jlong)final_int, "final value should be integer");
1018 return TypeInt::make(final_int);
1019 }
1020
1021 return bottom_type(); // TypeInt::INT
1022 }
1023
1024 //------------------------------Ideal------------------------------------------
1025 // Return a node which is more "ideal" than the current node.
1026 Node *LoopLimitNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1027 if (phase->type(in(Init)) == Type::TOP ||
1028 phase->type(in(Limit)) == Type::TOP ||
1029 phase->type(in(Stride)) == Type::TOP)
1030 return NULL; // Dead
1031
1032 int stride_con = phase->type(in(Stride))->is_int()->get_con();
1033 if (stride_con == 1)
1034 return NULL; // Identity
1035
1036 if (in(Init)->is_Con() && in(Limit)->is_Con())
1037 return NULL; // Value
1038
1039 // Delay following optimizations until all loop optimizations
1040 // done to keep Ideal graph simple.
1041 if (!can_reshape || phase->C->major_progress())
1042 return NULL;
1043
1044 const TypeInt* init_t = phase->type(in(Init) )->is_int();
1045 const TypeInt* limit_t = phase->type(in(Limit))->is_int();
1046 int stride_p;
1047 jlong lim, ini;
1048 julong max;
1049 if (stride_con > 0) {
1050 stride_p = stride_con;
1051 lim = limit_t->_hi;
1052 ini = init_t->_lo;
1053 max = (julong)max_jint;
1054 } else {
1055 stride_p = -stride_con;
1056 lim = init_t->_hi;
1057 ini = limit_t->_lo;
1058 max = (julong)min_jint;
1059 }
1060 julong range = lim - ini + stride_p;
1061 if (range <= max) {
1062 // Convert to integer expression if it is not overflow.
1063 Node* stride_m = phase->intcon(stride_con - (stride_con > 0 ? 1 : -1));
1064 Node *range = phase->transform(new SubINode(in(Limit), in(Init)));
1065 Node *bias = phase->transform(new AddINode(range, stride_m));
1066 Node *trip = phase->transform(new DivINode(0, bias, in(Stride)));
1067 Node *span = phase->transform(new MulINode(trip, in(Stride)));
1068 return new AddINode(span, in(Init)); // exact limit
1069 }
1070
1071 if (is_power_of_2(stride_p) || // divisor is 2^n
1072 !Matcher::has_match_rule(Op_LoopLimit)) { // or no specialized Mach node?
1073 // Convert to long expression to avoid integer overflow
1074 // and let igvn optimizer convert this division.
1075 //
1076 Node* init = phase->transform( new ConvI2LNode(in(Init)));
1077 Node* limit = phase->transform( new ConvI2LNode(in(Limit)));
1078 Node* stride = phase->longcon(stride_con);
1079 Node* stride_m = phase->longcon(stride_con - (stride_con > 0 ? 1 : -1));
1080
1081 Node *range = phase->transform(new SubLNode(limit, init));
1082 Node *bias = phase->transform(new AddLNode(range, stride_m));
1083 Node *span;
1084 if (stride_con > 0 && is_power_of_2(stride_p)) {
1085 // bias >= 0 if stride >0, so if stride is 2^n we can use &(-stride)
1086 // and avoid generating rounding for division. Zero trip guard should
1087 // guarantee that init < limit but sometimes the guard is missing and
1088 // we can get situation when init > limit. Note, for the empty loop
1089 // optimization zero trip guard is generated explicitly which leaves
1090 // only RCE predicate where exact limit is used and the predicate
1091 // will simply fail forcing recompilation.
1092 Node* neg_stride = phase->longcon(-stride_con);
1093 span = phase->transform(new AndLNode(bias, neg_stride));
1094 } else {
1095 Node *trip = phase->transform(new DivLNode(0, bias, stride));
1096 span = phase->transform(new MulLNode(trip, stride));
1097 }
1098 // Convert back to int
1099 Node *span_int = phase->transform(new ConvL2INode(span));
1100 return new AddINode(span_int, in(Init)); // exact limit
1101 }
1102
1103 return NULL; // No progress
1104 }
1105
1106 //------------------------------Identity---------------------------------------
1107 // If stride == 1 return limit node.
1108 Node* LoopLimitNode::Identity(PhaseGVN* phase) {
1109 int stride_con = phase->type(in(Stride))->is_int()->get_con();
1110 if (stride_con == 1 || stride_con == -1)
1111 return in(Limit);
1112 return this;
1113 }
1114
1115 //=============================================================================
1116 //----------------------match_incr_with_optional_truncation--------------------
1117 // Match increment with optional truncation:
1118 // CHAR: (i+1)&0x7fff, BYTE: ((i+1)<<8)>>8, or SHORT: ((i+1)<<16)>>16
1119 // Return NULL for failure. Success returns the increment node.
1120 Node* CountedLoopNode::match_incr_with_optional_truncation(
1121 Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type) {
1122 // Quick cutouts:
1123 if (expr == NULL || expr->req() != 3) return NULL;
1124
1125 Node *t1 = NULL;
1126 Node *t2 = NULL;
1127 const TypeInt* trunc_t = TypeInt::INT;
1128 Node* n1 = expr;
1129 int n1op = n1->Opcode();
1130
1131 // Try to strip (n1 & M) or (n1 << N >> N) from n1.
1132 if (n1op == Op_AndI &&
1133 n1->in(2)->is_Con() &&
1134 n1->in(2)->bottom_type()->is_int()->get_con() == 0x7fff) {
1135 // %%% This check should match any mask of 2**K-1.
1136 t1 = n1;
1137 n1 = t1->in(1);
1138 n1op = n1->Opcode();
1139 trunc_t = TypeInt::CHAR;
1140 } else if (n1op == Op_RShiftI &&
1141 n1->in(1) != NULL &&
1142 n1->in(1)->Opcode() == Op_LShiftI &&
1143 n1->in(2) == n1->in(1)->in(2) &&
1144 n1->in(2)->is_Con()) {
1145 jint shift = n1->in(2)->bottom_type()->is_int()->get_con();
1146 // %%% This check should match any shift in [1..31].
1147 if (shift == 16 || shift == 8) {
1148 t1 = n1;
1149 t2 = t1->in(1);
1150 n1 = t2->in(1);
1151 n1op = n1->Opcode();
1152 if (shift == 16) {
1153 trunc_t = TypeInt::SHORT;
1154 } else if (shift == 8) {
1155 trunc_t = TypeInt::BYTE;
1156 }
1157 }
1158 }
1159
1160 // If (maybe after stripping) it is an AddI, we won:
1161 if (n1op == Op_AddI) {
1162 *trunc1 = t1;
1163 *trunc2 = t2;
1164 *trunc_type = trunc_t;
1165 return n1;
1166 }
1167
1168 // failed
1169 return NULL;
1170 }
1171
1172 LoopNode* CountedLoopNode::skip_strip_mined(int expect_opaq) {
1173 if (is_strip_mined()) {
1174 verify_strip_mined(expect_opaq);
1175 return in(EntryControl)->as_Loop();
1176 }
1177 return this;
1178 }
1179
1180 LoopNode* CountedLoopNode::outer_loop() const {
1181 assert(is_strip_mined(), "not a strip mined loop");
1182 Node* c = in(EntryControl);
1183 if (c == NULL || c->is_top() || c->Opcode() != Op_Loop) {
1184 return NULL;
1185 }
1186 LoopNode* l = c->as_Loop();
1187 assert(l->is_strip_mined(), "where's the outer loop?");
1188 return l;
1189 }
1190
1191 IfTrueNode* LoopNode::outer_loop_tail() const {
1192 assert(is_strip_mined() && Opcode() == Op_Loop, "not a strip mined loop");
1193 Node* c = in(LoopBackControl);
1194 if (c == NULL || c->is_top()) {
1195 return NULL;
1196 }
1197 return c->as_IfTrue();
1198 }
1199
1200 IfTrueNode* CountedLoopNode::outer_loop_tail() const {
1201 LoopNode* l = outer_loop();
1202 if (l == NULL) {
1203 return NULL;
1204 }
1205 return l->outer_loop_tail();
1206 }
1207
1208 IfNode* LoopNode::outer_loop_end() const {
1209 IfTrueNode* proj = outer_loop_tail();
1210 if (proj == NULL) {
1211 return NULL;
1212 }
1213 Node* c = proj->in(0);
1214 if (c == NULL || c->is_top() || c->outcnt() != 2) {
1215 return NULL;
1216 }
1217 assert(c->Opcode() == Op_If, "broken outer loop");
1218 return c->as_If();
1219 }
1220
1221 IfNode* CountedLoopNode::outer_loop_end() const {
1222 LoopNode* l = outer_loop();
1223 if (l == NULL) {
1224 return NULL;
1225 }
1226 return l->outer_loop_end();
1227 }
1228
1229 IfFalseNode* LoopNode::outer_loop_exit() const {
1230 IfNode* le = outer_loop_end();
1231 if (le == NULL) {
1232 return NULL;
1233 }
1234 Node* c = le->proj_out(false);
1235 if (c == NULL) {
1236 return NULL;
1237 }
1238 return c->as_IfFalse();
1239 }
1240
1241 IfFalseNode* CountedLoopNode::outer_loop_exit() const {
1242 LoopNode* l = outer_loop();
1243 if (l == NULL) {
1244 return NULL;
1245 }
1246 return l->outer_loop_exit();
1247 }
1248
1249 SafePointNode* LoopNode::outer_safepoint() const {
1250 IfNode* le = outer_loop_end();
1251 if (le == NULL) {
1252 return NULL;
1253 }
1254 Node* c = le->in(0);
1255 if (c == NULL || c->is_top()) {
1256 return NULL;
1257 }
1258 assert(c->Opcode() == Op_SafePoint, "broken outer loop");
1259 return c->as_SafePoint();
1260 }
1261
1262 SafePointNode* CountedLoopNode::outer_safepoint() const {
1263 LoopNode* l = outer_loop();
1264 if (l == NULL) {
1265 return NULL;
1266 }
1267 return l->outer_safepoint();
1268 }
1269
1270 BoolNode* LoopNode::outer_bol() const {
1271 IfNode* le = outer_loop_end();
1272 if (le == NULL) {
1273 return NULL;
1274 }
1275 Node* n = le->in(1);
1276 if (n == NULL || n->is_top()) {
1277 return NULL;
1278 }
1279 return n->as_Bool();
1280 }
1281
1282 BoolNode* CountedLoopNode::outer_bol() const {
1283 LoopNode* l = outer_loop();
1284 if (l == NULL) {
1285 return NULL;
1286 }
1287 return l->outer_bol();
1288 }
1289
1290 CmpINode* LoopNode::outer_cmp() const {
1291 Node* bol = outer_bol();
1292 if (bol == NULL) {
1293 return NULL;
1294 }
1295 Node* n = bol->in(1);
1296 if (n == NULL || n->is_top()) {
1297 return NULL;
1298 }
1299 assert(n->Opcode() == Op_CmpI, "broken strip mined loop");
1300 return (CmpINode*)n;
1301 }
1302
1303 CmpINode* CountedLoopNode::outer_cmp() const {
1304 LoopNode* l = outer_loop();
1305 if (l == NULL) {
1306 return NULL;
1307 }
1308 return l->outer_cmp();
1309 }
1310
1311 Opaque5Node* LoopNode::outer_opaq() const {
1312 Node* cmp = outer_cmp();
1313 if (cmp == NULL) {
1314 return NULL;
1315 }
1316 Node* n = cmp->in(2);
1317 if (n == NULL || n->is_top()) {
1318 return NULL;
1319 }
1320 assert(n->Opcode() == Op_Opaque5, "broken strip mined loop");
1321 return (Opaque5Node*)n;
1322 }
1323
1324 Opaque5Node* CountedLoopNode::outer_opaq() const {
1325 LoopNode* l = outer_loop();
1326 if (l == NULL) {
1327 return NULL;
1328 }
1329 return l->outer_opaq();
1330 }
1331
1332 //------------------------------filtered_type--------------------------------
1333 // Return a type based on condition control flow
1334 // A successful return will be a type that is restricted due
1335 // to a series of dominating if-tests, such as:
1336 // if (i < 10) {
1337 // if (i > 0) {
1338 // here: "i" type is [1..10)
1339 // }
1340 // }
1341 // or a control flow merge
1342 // if (i < 10) {
1343 // do {
1344 // phi( , ) -- at top of loop type is [min_int..10)
1345 // i = ?
1346 // } while ( i < 10)
1347 //
1348 const TypeInt* PhaseIdealLoop::filtered_type( Node *n, Node* n_ctrl) {
1349 assert(n && n->bottom_type()->is_int(), "must be int");
1350 const TypeInt* filtered_t = NULL;
1351 if (!n->is_Phi()) {
1352 assert(n_ctrl != NULL || n_ctrl == C->top(), "valid control");
1353 filtered_t = filtered_type_from_dominators(n, n_ctrl);
1354
1355 } else {
1356 Node* phi = n->as_Phi();
1357 Node* region = phi->in(0);
1358 assert(n_ctrl == NULL || n_ctrl == region, "ctrl parameter must be region");
1359 if (region && region != C->top()) {
1360 for (uint i = 1; i < phi->req(); i++) {
1361 Node* val = phi->in(i);
1362 Node* use_c = region->in(i);
1363 const TypeInt* val_t = filtered_type_from_dominators(val, use_c);
1364 if (val_t != NULL) {
1365 if (filtered_t == NULL) {
1366 filtered_t = val_t;
1367 } else {
1368 filtered_t = filtered_t->meet(val_t)->is_int();
1369 }
1370 }
1371 }
1372 }
1373 }
1374 const TypeInt* n_t = _igvn.type(n)->is_int();
1375 if (filtered_t != NULL) {
1376 n_t = n_t->join(filtered_t)->is_int();
1377 }
1378 return n_t;
1379 }
1380
1381
1382 //------------------------------filtered_type_from_dominators--------------------------------
1383 // Return a possibly more restrictive type for val based on condition control flow of dominators
1384 const TypeInt* PhaseIdealLoop::filtered_type_from_dominators( Node* val, Node *use_ctrl) {
1385 if (val->is_Con()) {
1386 return val->bottom_type()->is_int();
1387 }
1388 uint if_limit = 10; // Max number of dominating if's visited
1389 const TypeInt* rtn_t = NULL;
1390
1391 if (use_ctrl && use_ctrl != C->top()) {
1392 Node* val_ctrl = get_ctrl(val);
1393 uint val_dom_depth = dom_depth(val_ctrl);
1394 Node* pred = use_ctrl;
1395 uint if_cnt = 0;
1396 while (if_cnt < if_limit) {
1397 if ((pred->Opcode() == Op_IfTrue || pred->Opcode() == Op_IfFalse)) {
1398 if_cnt++;
1399 const TypeInt* if_t = IfNode::filtered_int_type(&_igvn, val, pred);
1400 if (if_t != NULL) {
1401 if (rtn_t == NULL) {
1402 rtn_t = if_t;
1403 } else {
1404 rtn_t = rtn_t->join(if_t)->is_int();
1405 }
1406 }
1407 }
1408 pred = idom(pred);
1409 if (pred == NULL || pred == C->top()) {
1410 break;
1411 }
1412 // Stop if going beyond definition block of val
1413 if (dom_depth(pred) < val_dom_depth) {
1414 break;
1415 }
1416 }
1417 }
1418 return rtn_t;
1419 }
1420
1421
1422 //------------------------------dump_spec--------------------------------------
1423 // Dump special per-node info
1424 #ifndef PRODUCT
1425 void CountedLoopEndNode::dump_spec(outputStream *st) const {
1426 if( in(TestValue) != NULL && in(TestValue)->is_Bool() ) {
1427 BoolTest bt( test_trip()); // Added this for g++.
1428
1429 st->print("[");
1430 bt.dump_on(st);
1431 st->print("]");
1432 }
1433 st->print(" ");
1434 IfNode::dump_spec(st);
1435 }
1436 #endif
1437
1438 //=============================================================================
1439 //------------------------------is_member--------------------------------------
1440 // Is 'l' a member of 'this'?
1441 bool IdealLoopTree::is_member(const IdealLoopTree *l) const {
1442 while( l->_nest > _nest ) l = l->_parent;
1443 return l == this;
1444 }
1445
1446 //------------------------------set_nest---------------------------------------
1447 // Set loop tree nesting depth. Accumulate _has_call bits.
1448 int IdealLoopTree::set_nest( uint depth ) {
1449 _nest = depth;
1450 int bits = _has_call;
1451 if( _child ) bits |= _child->set_nest(depth+1);
1452 if( bits ) _has_call = 1;
1453 if( _next ) bits |= _next ->set_nest(depth );
1454 return bits;
1455 }
1456
1457 //------------------------------split_fall_in----------------------------------
1458 // Split out multiple fall-in edges from the loop header. Move them to a
1459 // private RegionNode before the loop. This becomes the loop landing pad.
1460 void IdealLoopTree::split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ) {
1461 PhaseIterGVN &igvn = phase->_igvn;
1462 uint i;
1463
1464 // Make a new RegionNode to be the landing pad.
1465 Node *landing_pad = new RegionNode( fall_in_cnt+1 );
1466 phase->set_loop(landing_pad,_parent);
1467 // Gather all the fall-in control paths into the landing pad
1468 uint icnt = fall_in_cnt;
1469 uint oreq = _head->req();
1470 for( i = oreq-1; i>0; i-- )
1471 if( !phase->is_member( this, _head->in(i) ) )
1472 landing_pad->set_req(icnt--,_head->in(i));
1473
1474 // Peel off PhiNode edges as well
1475 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1476 Node *oj = _head->fast_out(j);
1477 if( oj->is_Phi() ) {
1478 PhiNode* old_phi = oj->as_Phi();
1479 assert( old_phi->region() == _head, "" );
1480 igvn.hash_delete(old_phi); // Yank from hash before hacking edges
1481 Node *p = PhiNode::make_blank(landing_pad, old_phi);
1482 uint icnt = fall_in_cnt;
1483 for( i = oreq-1; i>0; i-- ) {
1484 if( !phase->is_member( this, _head->in(i) ) ) {
1485 p->init_req(icnt--, old_phi->in(i));
1486 // Go ahead and clean out old edges from old phi
1487 old_phi->del_req(i);
1488 }
1489 }
1490 // Search for CSE's here, because ZKM.jar does a lot of
1491 // loop hackery and we need to be a little incremental
1492 // with the CSE to avoid O(N^2) node blow-up.
1493 Node *p2 = igvn.hash_find_insert(p); // Look for a CSE
1494 if( p2 ) { // Found CSE
1495 p->destruct(); // Recover useless new node
1496 p = p2; // Use old node
1497 } else {
1498 igvn.register_new_node_with_optimizer(p, old_phi);
1499 }
1500 // Make old Phi refer to new Phi.
1501 old_phi->add_req(p);
1502 // Check for the special case of making the old phi useless and
1503 // disappear it. In JavaGrande I have a case where this useless
1504 // Phi is the loop limit and prevents recognizing a CountedLoop
1505 // which in turn prevents removing an empty loop.
1506 Node *id_old_phi = old_phi->Identity( &igvn );
1507 if( id_old_phi != old_phi ) { // Found a simple identity?
1508 // Note that I cannot call 'replace_node' here, because
1509 // that will yank the edge from old_phi to the Region and
1510 // I'm mid-iteration over the Region's uses.
1511 for (DUIterator_Last imin, i = old_phi->last_outs(imin); i >= imin; ) {
1512 Node* use = old_phi->last_out(i);
1513 igvn.rehash_node_delayed(use);
1514 uint uses_found = 0;
1515 for (uint j = 0; j < use->len(); j++) {
1516 if (use->in(j) == old_phi) {
1517 if (j < use->req()) use->set_req (j, id_old_phi);
1518 else use->set_prec(j, id_old_phi);
1519 uses_found++;
1520 }
1521 }
1522 i -= uses_found; // we deleted 1 or more copies of this edge
1523 }
1524 }
1525 igvn._worklist.push(old_phi);
1526 }
1527 }
1528 // Finally clean out the fall-in edges from the RegionNode
1529 for( i = oreq-1; i>0; i-- ) {
1530 if( !phase->is_member( this, _head->in(i) ) ) {
1531 _head->del_req(i);
1532 }
1533 }
1534 igvn.rehash_node_delayed(_head);
1535 // Transform landing pad
1536 igvn.register_new_node_with_optimizer(landing_pad, _head);
1537 // Insert landing pad into the header
1538 _head->add_req(landing_pad);
1539 }
1540
1541 //------------------------------split_outer_loop-------------------------------
1542 // Split out the outermost loop from this shared header.
1543 void IdealLoopTree::split_outer_loop( PhaseIdealLoop *phase ) {
1544 PhaseIterGVN &igvn = phase->_igvn;
1545
1546 // Find index of outermost loop; it should also be my tail.
1547 uint outer_idx = 1;
1548 while( _head->in(outer_idx) != _tail ) outer_idx++;
1549
1550 // Make a LoopNode for the outermost loop.
1551 Node *ctl = _head->in(LoopNode::EntryControl);
1552 Node *outer = new LoopNode( ctl, _head->in(outer_idx) );
1553 outer = igvn.register_new_node_with_optimizer(outer, _head);
1554 phase->set_created_loop_node();
1555
1556 // Outermost loop falls into '_head' loop
1557 _head->set_req(LoopNode::EntryControl, outer);
1558 _head->del_req(outer_idx);
1559 // Split all the Phis up between '_head' loop and 'outer' loop.
1560 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1561 Node *out = _head->fast_out(j);
1562 if( out->is_Phi() ) {
1563 PhiNode *old_phi = out->as_Phi();
1564 assert( old_phi->region() == _head, "" );
1565 Node *phi = PhiNode::make_blank(outer, old_phi);
1566 phi->init_req(LoopNode::EntryControl, old_phi->in(LoopNode::EntryControl));
1567 phi->init_req(LoopNode::LoopBackControl, old_phi->in(outer_idx));
1568 phi = igvn.register_new_node_with_optimizer(phi, old_phi);
1569 // Make old Phi point to new Phi on the fall-in path
1570 igvn.replace_input_of(old_phi, LoopNode::EntryControl, phi);
1571 old_phi->del_req(outer_idx);
1572 }
1573 }
1574
1575 // Use the new loop head instead of the old shared one
1576 _head = outer;
1577 phase->set_loop(_head, this);
1578 }
1579
1580 //------------------------------fix_parent-------------------------------------
1581 static void fix_parent( IdealLoopTree *loop, IdealLoopTree *parent ) {
1582 loop->_parent = parent;
1583 if( loop->_child ) fix_parent( loop->_child, loop );
1584 if( loop->_next ) fix_parent( loop->_next , parent );
1585 }
1586
1587 //------------------------------estimate_path_freq-----------------------------
1588 static float estimate_path_freq( Node *n ) {
1589 // Try to extract some path frequency info
1590 IfNode *iff;
1591 for( int i = 0; i < 50; i++ ) { // Skip through a bunch of uncommon tests
1592 uint nop = n->Opcode();
1593 if( nop == Op_SafePoint ) { // Skip any safepoint
1594 n = n->in(0);
1595 continue;
1596 }
1597 if( nop == Op_CatchProj ) { // Get count from a prior call
1598 // Assume call does not always throw exceptions: means the call-site
1599 // count is also the frequency of the fall-through path.
1600 assert( n->is_CatchProj(), "" );
1601 if( ((CatchProjNode*)n)->_con != CatchProjNode::fall_through_index )
1602 return 0.0f; // Assume call exception path is rare
1603 Node *call = n->in(0)->in(0)->in(0);
1604 assert( call->is_Call(), "expect a call here" );
1605 const JVMState *jvms = ((CallNode*)call)->jvms();
1606 ciMethodData* methodData = jvms->method()->method_data();
1607 if (!methodData->is_mature()) return 0.0f; // No call-site data
1608 ciProfileData* data = methodData->bci_to_data(jvms->bci());
1609 if ((data == NULL) || !data->is_CounterData()) {
1610 // no call profile available, try call's control input
1611 n = n->in(0);
1612 continue;
1613 }
1614 return data->as_CounterData()->count()/FreqCountInvocations;
1615 }
1616 // See if there's a gating IF test
1617 Node *n_c = n->in(0);
1618 if( !n_c->is_If() ) break; // No estimate available
1619 iff = n_c->as_If();
1620 if( iff->_fcnt != COUNT_UNKNOWN ) // Have a valid count?
1621 // Compute how much count comes on this path
1622 return ((nop == Op_IfTrue) ? iff->_prob : 1.0f - iff->_prob) * iff->_fcnt;
1623 // Have no count info. Skip dull uncommon-trap like branches.
1624 if( (nop == Op_IfTrue && iff->_prob < PROB_LIKELY_MAG(5)) ||
1625 (nop == Op_IfFalse && iff->_prob > PROB_UNLIKELY_MAG(5)) )
1626 break;
1627 // Skip through never-taken branch; look for a real loop exit.
1628 n = iff->in(0);
1629 }
1630 return 0.0f; // No estimate available
1631 }
1632
1633 //------------------------------merge_many_backedges---------------------------
1634 // Merge all the backedges from the shared header into a private Region.
1635 // Feed that region as the one backedge to this loop.
1636 void IdealLoopTree::merge_many_backedges( PhaseIdealLoop *phase ) {
1637 uint i;
1638
1639 // Scan for the top 2 hottest backedges
1640 float hotcnt = 0.0f;
1641 float warmcnt = 0.0f;
1642 uint hot_idx = 0;
1643 // Loop starts at 2 because slot 1 is the fall-in path
1644 for( i = 2; i < _head->req(); i++ ) {
1645 float cnt = estimate_path_freq(_head->in(i));
1646 if( cnt > hotcnt ) { // Grab hottest path
1647 warmcnt = hotcnt;
1648 hotcnt = cnt;
1649 hot_idx = i;
1650 } else if( cnt > warmcnt ) { // And 2nd hottest path
1651 warmcnt = cnt;
1652 }
1653 }
1654
1655 // See if the hottest backedge is worthy of being an inner loop
1656 // by being much hotter than the next hottest backedge.
1657 if( hotcnt <= 0.0001 ||
1658 hotcnt < 2.0*warmcnt ) hot_idx = 0;// No hot backedge
1659
1660 // Peel out the backedges into a private merge point; peel
1661 // them all except optionally hot_idx.
1662 PhaseIterGVN &igvn = phase->_igvn;
1663
1664 Node *hot_tail = NULL;
1665 // Make a Region for the merge point
1666 Node *r = new RegionNode(1);
1667 for( i = 2; i < _head->req(); i++ ) {
1668 if( i != hot_idx )
1669 r->add_req( _head->in(i) );
1670 else hot_tail = _head->in(i);
1671 }
1672 igvn.register_new_node_with_optimizer(r, _head);
1673 // Plug region into end of loop _head, followed by hot_tail
1674 while( _head->req() > 3 ) _head->del_req( _head->req()-1 );
1675 igvn.replace_input_of(_head, 2, r);
1676 if( hot_idx ) _head->add_req(hot_tail);
1677
1678 // Split all the Phis up between '_head' loop and the Region 'r'
1679 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1680 Node *out = _head->fast_out(j);
1681 if( out->is_Phi() ) {
1682 PhiNode* n = out->as_Phi();
1683 igvn.hash_delete(n); // Delete from hash before hacking edges
1684 Node *hot_phi = NULL;
1685 Node *phi = new PhiNode(r, n->type(), n->adr_type());
1686 // Check all inputs for the ones to peel out
1687 uint j = 1;
1688 for( uint i = 2; i < n->req(); i++ ) {
1689 if( i != hot_idx )
1690 phi->set_req( j++, n->in(i) );
1691 else hot_phi = n->in(i);
1692 }
1693 // Register the phi but do not transform until whole place transforms
1694 igvn.register_new_node_with_optimizer(phi, n);
1695 // Add the merge phi to the old Phi
1696 while( n->req() > 3 ) n->del_req( n->req()-1 );
1697 igvn.replace_input_of(n, 2, phi);
1698 if( hot_idx ) n->add_req(hot_phi);
1699 }
1700 }
1701
1702
1703 // Insert a new IdealLoopTree inserted below me. Turn it into a clone
1704 // of self loop tree. Turn self into a loop headed by _head and with
1705 // tail being the new merge point.
1706 IdealLoopTree *ilt = new IdealLoopTree( phase, _head, _tail );
1707 phase->set_loop(_tail,ilt); // Adjust tail
1708 _tail = r; // Self's tail is new merge point
1709 phase->set_loop(r,this);
1710 ilt->_child = _child; // New guy has my children
1711 _child = ilt; // Self has new guy as only child
1712 ilt->_parent = this; // new guy has self for parent
1713 ilt->_nest = _nest; // Same nesting depth (for now)
1714
1715 // Starting with 'ilt', look for child loop trees using the same shared
1716 // header. Flatten these out; they will no longer be loops in the end.
1717 IdealLoopTree **pilt = &_child;
1718 while( ilt ) {
1719 if( ilt->_head == _head ) {
1720 uint i;
1721 for( i = 2; i < _head->req(); i++ )
1722 if( _head->in(i) == ilt->_tail )
1723 break; // Still a loop
1724 if( i == _head->req() ) { // No longer a loop
1725 // Flatten ilt. Hang ilt's "_next" list from the end of
1726 // ilt's '_child' list. Move the ilt's _child up to replace ilt.
1727 IdealLoopTree **cp = &ilt->_child;
1728 while( *cp ) cp = &(*cp)->_next; // Find end of child list
1729 *cp = ilt->_next; // Hang next list at end of child list
1730 *pilt = ilt->_child; // Move child up to replace ilt
1731 ilt->_head = NULL; // Flag as a loop UNIONED into parent
1732 ilt = ilt->_child; // Repeat using new ilt
1733 continue; // do not advance over ilt->_child
1734 }
1735 assert( ilt->_tail == hot_tail, "expected to only find the hot inner loop here" );
1736 phase->set_loop(_head,ilt);
1737 }
1738 pilt = &ilt->_child; // Advance to next
1739 ilt = *pilt;
1740 }
1741
1742 if( _child ) fix_parent( _child, this );
1743 }
1744
1745 //------------------------------beautify_loops---------------------------------
1746 // Split shared headers and insert loop landing pads.
1747 // Insert a LoopNode to replace the RegionNode.
1748 // Return TRUE if loop tree is structurally changed.
1749 bool IdealLoopTree::beautify_loops( PhaseIdealLoop *phase ) {
1750 bool result = false;
1751 // Cache parts in locals for easy
1752 PhaseIterGVN &igvn = phase->_igvn;
1753
1754 igvn.hash_delete(_head); // Yank from hash before hacking edges
1755
1756 // Check for multiple fall-in paths. Peel off a landing pad if need be.
1757 int fall_in_cnt = 0;
1758 for( uint i = 1; i < _head->req(); i++ )
1759 if( !phase->is_member( this, _head->in(i) ) )
1760 fall_in_cnt++;
1761 assert( fall_in_cnt, "at least 1 fall-in path" );
1762 if( fall_in_cnt > 1 ) // Need a loop landing pad to merge fall-ins
1763 split_fall_in( phase, fall_in_cnt );
1764
1765 // Swap inputs to the _head and all Phis to move the fall-in edge to
1766 // the left.
1767 fall_in_cnt = 1;
1768 while( phase->is_member( this, _head->in(fall_in_cnt) ) )
1769 fall_in_cnt++;
1770 if( fall_in_cnt > 1 ) {
1771 // Since I am just swapping inputs I do not need to update def-use info
1772 Node *tmp = _head->in(1);
1773 igvn.rehash_node_delayed(_head);
1774 _head->set_req( 1, _head->in(fall_in_cnt) );
1775 _head->set_req( fall_in_cnt, tmp );
1776 // Swap also all Phis
1777 for (DUIterator_Fast imax, i = _head->fast_outs(imax); i < imax; i++) {
1778 Node* phi = _head->fast_out(i);
1779 if( phi->is_Phi() ) {
1780 igvn.rehash_node_delayed(phi); // Yank from hash before hacking edges
1781 tmp = phi->in(1);
1782 phi->set_req( 1, phi->in(fall_in_cnt) );
1783 phi->set_req( fall_in_cnt, tmp );
1784 }
1785 }
1786 }
1787 assert( !phase->is_member( this, _head->in(1) ), "left edge is fall-in" );
1788 assert( phase->is_member( this, _head->in(2) ), "right edge is loop" );
1789
1790 // If I am a shared header (multiple backedges), peel off the many
1791 // backedges into a private merge point and use the merge point as
1792 // the one true backedge.
1793 if( _head->req() > 3 ) {
1794 // Merge the many backedges into a single backedge but leave
1795 // the hottest backedge as separate edge for the following peel.
1796 merge_many_backedges( phase );
1797 result = true;
1798 }
1799
1800 // If I have one hot backedge, peel off myself loop.
1801 // I better be the outermost loop.
1802 if (_head->req() > 3 && !_irreducible) {
1803 split_outer_loop( phase );
1804 result = true;
1805
1806 } else if (!_head->is_Loop() && !_irreducible) {
1807 // Make a new LoopNode to replace the old loop head
1808 Node *l = new LoopNode( _head->in(1), _head->in(2) );
1809 l = igvn.register_new_node_with_optimizer(l, _head);
1810 phase->set_created_loop_node();
1811 // Go ahead and replace _head
1812 phase->_igvn.replace_node( _head, l );
1813 _head = l;
1814 phase->set_loop(_head, this);
1815 }
1816
1817 // Now recursively beautify nested loops
1818 if( _child ) result |= _child->beautify_loops( phase );
1819 if( _next ) result |= _next ->beautify_loops( phase );
1820 return result;
1821 }
1822
1823 //------------------------------allpaths_check_safepts----------------------------
1824 // Allpaths backwards scan from loop tail, terminating each path at first safepoint
1825 // encountered. Helper for check_safepts.
1826 void IdealLoopTree::allpaths_check_safepts(VectorSet &visited, Node_List &stack) {
1827 assert(stack.size() == 0, "empty stack");
1828 stack.push(_tail);
1829 visited.Clear();
1830 visited.set(_tail->_idx);
1831 while (stack.size() > 0) {
1832 Node* n = stack.pop();
1833 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
1834 // Terminate this path
1835 } else if (n->Opcode() == Op_SafePoint) {
1836 if (_phase->get_loop(n) != this) {
1837 if (_required_safept == NULL) _required_safept = new Node_List();
1838 _required_safept->push(n); // save the one closest to the tail
1839 }
1840 // Terminate this path
1841 } else {
1842 uint start = n->is_Region() ? 1 : 0;
1843 uint end = n->is_Region() && !n->is_Loop() ? n->req() : start + 1;
1844 for (uint i = start; i < end; i++) {
1845 Node* in = n->in(i);
1846 assert(in->is_CFG(), "must be");
1847 if (!visited.test_set(in->_idx) && is_member(_phase->get_loop(in))) {
1848 stack.push(in);
1849 }
1850 }
1851 }
1852 }
1853 }
1854
1855 //------------------------------check_safepts----------------------------
1856 // Given dominators, try to find loops with calls that must always be
1857 // executed (call dominates loop tail). These loops do not need non-call
1858 // safepoints (ncsfpt).
1859 //
1860 // A complication is that a safepoint in a inner loop may be needed
1861 // by an outer loop. In the following, the inner loop sees it has a
1862 // call (block 3) on every path from the head (block 2) to the
1863 // backedge (arc 3->2). So it deletes the ncsfpt (non-call safepoint)
1864 // in block 2, _but_ this leaves the outer loop without a safepoint.
1865 //
1866 // entry 0
1867 // |
1868 // v
1869 // outer 1,2 +->1
1870 // | |
1871 // | v
1872 // | 2<---+ ncsfpt in 2
1873 // |_/|\ |
1874 // | v |
1875 // inner 2,3 / 3 | call in 3
1876 // / | |
1877 // v +--+
1878 // exit 4
1879 //
1880 //
1881 // This method creates a list (_required_safept) of ncsfpt nodes that must
1882 // be protected is created for each loop. When a ncsfpt maybe deleted, it
1883 // is first looked for in the lists for the outer loops of the current loop.
1884 //
1885 // The insights into the problem:
1886 // A) counted loops are okay
1887 // B) innermost loops are okay (only an inner loop can delete
1888 // a ncsfpt needed by an outer loop)
1889 // C) a loop is immune from an inner loop deleting a safepoint
1890 // if the loop has a call on the idom-path
1891 // D) a loop is also immune if it has a ncsfpt (non-call safepoint) on the
1892 // idom-path that is not in a nested loop
1893 // E) otherwise, an ncsfpt on the idom-path that is nested in an inner
1894 // loop needs to be prevented from deletion by an inner loop
1895 //
1896 // There are two analyses:
1897 // 1) The first, and cheaper one, scans the loop body from
1898 // tail to head following the idom (immediate dominator)
1899 // chain, looking for the cases (C,D,E) above.
1900 // Since inner loops are scanned before outer loops, there is summary
1901 // information about inner loops. Inner loops can be skipped over
1902 // when the tail of an inner loop is encountered.
1903 //
1904 // 2) The second, invoked if the first fails to find a call or ncsfpt on
1905 // the idom path (which is rare), scans all predecessor control paths
1906 // from the tail to the head, terminating a path when a call or sfpt
1907 // is encountered, to find the ncsfpt's that are closest to the tail.
1908 //
1909 void IdealLoopTree::check_safepts(VectorSet &visited, Node_List &stack) {
1910 // Bottom up traversal
1911 IdealLoopTree* ch = _child;
1912 if (_child) _child->check_safepts(visited, stack);
1913 if (_next) _next ->check_safepts(visited, stack);
1914
1915 if (!_head->is_CountedLoop() && !_has_sfpt && _parent != NULL && !_irreducible) {
1916 bool has_call = false; // call on dom-path
1917 bool has_local_ncsfpt = false; // ncsfpt on dom-path at this loop depth
1918 Node* nonlocal_ncsfpt = NULL; // ncsfpt on dom-path at a deeper depth
1919 // Scan the dom-path nodes from tail to head
1920 for (Node* n = tail(); n != _head; n = _phase->idom(n)) {
1921 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
1922 has_call = true;
1923 _has_sfpt = 1; // Then no need for a safept!
1924 break;
1925 } else if (n->Opcode() == Op_SafePoint) {
1926 if (_phase->get_loop(n) == this) {
1927 has_local_ncsfpt = true;
1928 break;
1929 }
1930 if (nonlocal_ncsfpt == NULL) {
1931 nonlocal_ncsfpt = n; // save the one closest to the tail
1932 }
1933 } else {
1934 IdealLoopTree* nlpt = _phase->get_loop(n);
1935 if (this != nlpt) {
1936 // If at an inner loop tail, see if the inner loop has already
1937 // recorded seeing a call on the dom-path (and stop.) If not,
1938 // jump to the head of the inner loop.
1939 assert(is_member(nlpt), "nested loop");
1940 Node* tail = nlpt->_tail;
1941 if (tail->in(0)->is_If()) tail = tail->in(0);
1942 if (n == tail) {
1943 // If inner loop has call on dom-path, so does outer loop
1944 if (nlpt->_has_sfpt) {
1945 has_call = true;
1946 _has_sfpt = 1;
1947 break;
1948 }
1949 // Skip to head of inner loop
1950 assert(_phase->is_dominator(_head, nlpt->_head), "inner head dominated by outer head");
1951 n = nlpt->_head;
1952 }
1953 }
1954 }
1955 }
1956 // Record safept's that this loop needs preserved when an
1957 // inner loop attempts to delete it's safepoints.
1958 if (_child != NULL && !has_call && !has_local_ncsfpt) {
1959 if (nonlocal_ncsfpt != NULL) {
1960 if (_required_safept == NULL) _required_safept = new Node_List();
1961 _required_safept->push(nonlocal_ncsfpt);
1962 } else {
1963 // Failed to find a suitable safept on the dom-path. Now use
1964 // an all paths walk from tail to head, looking for safepoints to preserve.
1965 allpaths_check_safepts(visited, stack);
1966 }
1967 }
1968 }
1969 }
1970
1971 //---------------------------is_deleteable_safept----------------------------
1972 // Is safept not required by an outer loop?
1973 bool PhaseIdealLoop::is_deleteable_safept(Node* sfpt) {
1974 assert(sfpt->Opcode() == Op_SafePoint, "");
1975 IdealLoopTree* lp = get_loop(sfpt)->_parent;
1976 while (lp != NULL) {
1977 Node_List* sfpts = lp->_required_safept;
1978 if (sfpts != NULL) {
1979 for (uint i = 0; i < sfpts->size(); i++) {
1980 if (sfpt == sfpts->at(i))
1981 return false;
1982 }
1983 }
1984 lp = lp->_parent;
1985 }
1986 return true;
1987 }
1988
1989 //---------------------------replace_parallel_iv-------------------------------
1990 // Replace parallel induction variable (parallel to trip counter)
1991 void PhaseIdealLoop::replace_parallel_iv(IdealLoopTree *loop) {
1992 assert(loop->_head->is_CountedLoop(), "");
1993 CountedLoopNode *cl = loop->_head->as_CountedLoop();
1994 if (!cl->is_valid_counted_loop())
1995 return; // skip malformed counted loop
1996 Node *incr = cl->incr();
1997 if (incr == NULL)
1998 return; // Dead loop?
1999 Node *init = cl->init_trip();
2000 Node *phi = cl->phi();
2001 int stride_con = cl->stride_con();
2002
2003 // Visit all children, looking for Phis
2004 for (DUIterator i = cl->outs(); cl->has_out(i); i++) {
2005 Node *out = cl->out(i);
2006 // Look for other phis (secondary IVs). Skip dead ones
2007 if (!out->is_Phi() || out == phi || !has_node(out))
2008 continue;
2009 PhiNode* phi2 = out->as_Phi();
2010 Node *incr2 = phi2->in( LoopNode::LoopBackControl );
2011 // Look for induction variables of the form: X += constant
2012 if (phi2->region() != loop->_head ||
2013 incr2->req() != 3 ||
2014 incr2->in(1) != phi2 ||
2015 incr2 == incr ||
2016 incr2->Opcode() != Op_AddI ||
2017 !incr2->in(2)->is_Con())
2018 continue;
2019
2020 // Check for parallel induction variable (parallel to trip counter)
2021 // via an affine function. In particular, count-down loops with
2022 // count-up array indices are common. We only RCE references off
2023 // the trip-counter, so we need to convert all these to trip-counter
2024 // expressions.
2025 Node *init2 = phi2->in( LoopNode::EntryControl );
2026 int stride_con2 = incr2->in(2)->get_int();
2027
2028 // The ratio of the two strides cannot be represented as an int
2029 // if stride_con2 is min_int and stride_con is -1.
2030 if (stride_con2 == min_jint && stride_con == -1) {
2031 continue;
2032 }
2033
2034 // The general case here gets a little tricky. We want to find the
2035 // GCD of all possible parallel IV's and make a new IV using this
2036 // GCD for the loop. Then all possible IVs are simple multiples of
2037 // the GCD. In practice, this will cover very few extra loops.
2038 // Instead we require 'stride_con2' to be a multiple of 'stride_con',
2039 // where +/-1 is the common case, but other integer multiples are
2040 // also easy to handle.
2041 int ratio_con = stride_con2/stride_con;
2042
2043 if ((ratio_con * stride_con) == stride_con2) { // Check for exact
2044 #ifndef PRODUCT
2045 if (TraceLoopOpts) {
2046 tty->print("Parallel IV: %d ", phi2->_idx);
2047 loop->dump_head();
2048 }
2049 #endif
2050 // Convert to using the trip counter. The parallel induction
2051 // variable differs from the trip counter by a loop-invariant
2052 // amount, the difference between their respective initial values.
2053 // It is scaled by the 'ratio_con'.
2054 Node* ratio = _igvn.intcon(ratio_con);
2055 set_ctrl(ratio, C->root());
2056 Node* ratio_init = new MulINode(init, ratio);
2057 _igvn.register_new_node_with_optimizer(ratio_init, init);
2058 set_early_ctrl(ratio_init);
2059 Node* diff = new SubINode(init2, ratio_init);
2060 _igvn.register_new_node_with_optimizer(diff, init2);
2061 set_early_ctrl(diff);
2062 Node* ratio_idx = new MulINode(phi, ratio);
2063 _igvn.register_new_node_with_optimizer(ratio_idx, phi);
2064 set_ctrl(ratio_idx, cl);
2065 Node* add = new AddINode(ratio_idx, diff);
2066 _igvn.register_new_node_with_optimizer(add);
2067 set_ctrl(add, cl);
2068 _igvn.replace_node( phi2, add );
2069 // Sometimes an induction variable is unused
2070 if (add->outcnt() == 0) {
2071 _igvn.remove_dead_node(add);
2072 }
2073 --i; // deleted this phi; rescan starting with next position
2074 continue;
2075 }
2076 }
2077 }
2078
2079 void IdealLoopTree::remove_safepoints(PhaseIdealLoop* phase, bool keep_one) {
2080 Node* keep = NULL;
2081 if (keep_one) {
2082 // Look for a safepoint on the idom-path.
2083 for (Node* i = tail(); i != _head; i = phase->idom(i)) {
2084 if (i->Opcode() == Op_SafePoint && phase->get_loop(i) == this) {
2085 keep = i;
2086 break; // Found one
2087 }
2088 }
2089 }
2090
2091 // Don't remove any safepoints if it is requested to keep a single safepoint and
2092 // no safepoint was found on idom-path. It is not safe to remove any safepoint
2093 // in this case since there's no safepoint dominating all paths in the loop body.
2094 bool prune = !keep_one || keep != NULL;
2095
2096 // Delete other safepoints in this loop.
2097 Node_List* sfpts = _safepts;
2098 if (prune && sfpts != NULL) {
2099 assert(keep == NULL || keep->Opcode() == Op_SafePoint, "not safepoint");
2100 for (uint i = 0; i < sfpts->size(); i++) {
2101 Node* n = sfpts->at(i);
2102 assert(phase->get_loop(n) == this, "");
2103 if (n != keep && phase->is_deleteable_safept(n)) {
2104 phase->lazy_replace(n, n->in(TypeFunc::Control));
2105 }
2106 }
2107 }
2108 }
2109
2110 //------------------------------counted_loop-----------------------------------
2111 // Convert to counted loops where possible
2112 void IdealLoopTree::counted_loop( PhaseIdealLoop *phase ) {
2113
2114 // For grins, set the inner-loop flag here
2115 if (!_child) {
2116 if (_head->is_Loop()) _head->as_Loop()->set_inner_loop();
2117 }
2118
2119 IdealLoopTree* loop = this;
2120 if (_head->is_CountedLoop() ||
2121 phase->is_counted_loop(_head, loop)) {
2122
2123 if (LoopStripMiningIter == 0 || (LoopStripMiningIter > 1 && _child == NULL)) {
2124 // Indicate we do not need a safepoint here
2125 _has_sfpt = 1;
2126 }
2127
2128 // Remove safepoints
2129 bool keep_one_sfpt = !(_has_call || _has_sfpt);
2130 remove_safepoints(phase, keep_one_sfpt);
2131
2132 // Look for induction variables
2133 phase->replace_parallel_iv(this);
2134
2135 } else if (_parent != NULL && !_irreducible) {
2136 // Not a counted loop. Keep one safepoint.
2137 bool keep_one_sfpt = true;
2138 remove_safepoints(phase, keep_one_sfpt);
2139 }
2140
2141 // Recursively
2142 assert(loop->_child != this || (loop->_head->as_Loop()->is_strip_mined() && _head->as_CountedLoop()->is_strip_mined()), "what kind of loop was added?");
2143 assert(loop->_child != this || (loop->_child->_child == NULL && loop->_child->_next == NULL), "would miss some loops");
2144 if (loop->_child && loop->_child != this) loop->_child->counted_loop(phase);
2145 if (loop->_next) loop->_next ->counted_loop(phase);
2146 }
2147
2148 #ifndef PRODUCT
2149 //------------------------------dump_head--------------------------------------
2150 // Dump 1 liner for loop header info
2151 void IdealLoopTree::dump_head( ) const {
2152 for (uint i=0; i<_nest; i++)
2153 tty->print(" ");
2154 tty->print("Loop: N%d/N%d ",_head->_idx,_tail->_idx);
2155 if (_irreducible) tty->print(" IRREDUCIBLE");
2156 Node* entry = _head->as_Loop()->skip_strip_mined(-1)->in(LoopNode::EntryControl);
2157 Node* predicate = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
2158 if (predicate != NULL ) {
2159 tty->print(" limit_check");
2160 entry = entry->in(0)->in(0);
2161 }
2162 if (UseLoopPredicate) {
2163 entry = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
2164 if (entry != NULL) {
2165 tty->print(" predicated");
2166 }
2167 }
2168 if (_head->is_CountedLoop()) {
2169 CountedLoopNode *cl = _head->as_CountedLoop();
2170 tty->print(" counted");
2171
2172 Node* init_n = cl->init_trip();
2173 if (init_n != NULL && init_n->is_Con())
2174 tty->print(" [%d,", cl->init_trip()->get_int());
2175 else
2176 tty->print(" [int,");
2177 Node* limit_n = cl->limit();
2178 if (limit_n != NULL && limit_n->is_Con())
2179 tty->print("%d),", cl->limit()->get_int());
2180 else
2181 tty->print("int),");
2182 int stride_con = cl->stride_con();
2183 if (stride_con > 0) tty->print("+");
2184 tty->print("%d", stride_con);
2185
2186 tty->print(" (%0.f iters) ", cl->profile_trip_cnt());
2187
2188 if (cl->is_pre_loop ()) tty->print(" pre" );
2189 if (cl->is_main_loop()) tty->print(" main");
2190 if (cl->is_post_loop()) tty->print(" post");
2191 if (cl->is_vectorized_loop()) tty->print(" vector");
2192 if (cl->range_checks_present()) tty->print(" rc ");
2193 if (cl->is_multiversioned()) tty->print(" multi ");
2194 }
2195 if (_has_call) tty->print(" has_call");
2196 if (_has_sfpt) tty->print(" has_sfpt");
2197 if (_rce_candidate) tty->print(" rce");
2198 if (_safepts != NULL && _safepts->size() > 0) {
2199 tty->print(" sfpts={"); _safepts->dump_simple(); tty->print(" }");
2200 }
2201 if (_required_safept != NULL && _required_safept->size() > 0) {
2202 tty->print(" req={"); _required_safept->dump_simple(); tty->print(" }");
2203 }
2204 if (Verbose) {
2205 tty->print(" body={"); _body.dump_simple(); tty->print(" }");
2206 }
2207 if (_head->as_Loop()->is_strip_mined()) {
2208 tty->print(" strip mined");
2209 }
2210 tty->cr();
2211 }
2212
2213 //------------------------------dump-------------------------------------------
2214 // Dump loops by loop tree
2215 void IdealLoopTree::dump( ) const {
2216 dump_head();
2217 if (_child) _child->dump();
2218 if (_next) _next ->dump();
2219 }
2220
2221 #endif
2222
2223 static void log_loop_tree(IdealLoopTree* root, IdealLoopTree* loop, CompileLog* log) {
2224 if (loop == root) {
2225 if (loop->_child != NULL) {
2226 log->begin_head("loop_tree");
2227 log->end_head();
2228 if( loop->_child ) log_loop_tree(root, loop->_child, log);
2229 log->tail("loop_tree");
2230 assert(loop->_next == NULL, "what?");
2231 }
2232 } else {
2233 Node* head = loop->_head;
2234 log->begin_head("loop");
2235 log->print(" idx='%d' ", head->_idx);
2236 if (loop->_irreducible) log->print("irreducible='1' ");
2237 if (head->is_Loop()) {
2238 if (head->as_Loop()->is_inner_loop()) log->print("inner_loop='1' ");
2239 if (head->as_Loop()->is_partial_peel_loop()) log->print("partial_peel_loop='1' ");
2240 }
2241 if (head->is_CountedLoop()) {
2242 CountedLoopNode* cl = head->as_CountedLoop();
2243 if (cl->is_pre_loop()) log->print("pre_loop='%d' ", cl->main_idx());
2244 if (cl->is_main_loop()) log->print("main_loop='%d' ", cl->_idx);
2245 if (cl->is_post_loop()) log->print("post_loop='%d' ", cl->main_idx());
2246 }
2247 log->end_head();
2248 if( loop->_child ) log_loop_tree(root, loop->_child, log);
2249 log->tail("loop");
2250 if( loop->_next ) log_loop_tree(root, loop->_next, log);
2251 }
2252 }
2253
2254 //---------------------collect_potentially_useful_predicates-----------------------
2255 // Helper function to collect potentially useful predicates to prevent them from
2256 // being eliminated by PhaseIdealLoop::eliminate_useless_predicates
2257 void PhaseIdealLoop::collect_potentially_useful_predicates(
2258 IdealLoopTree * loop, Unique_Node_List &useful_predicates) {
2259 if (loop->_child) { // child
2260 collect_potentially_useful_predicates(loop->_child, useful_predicates);
2261 }
2262
2263 // self (only loops that we can apply loop predication may use their predicates)
2264 if (loop->_head->is_Loop() &&
2265 !loop->_irreducible &&
2266 !loop->tail()->is_top()) {
2267 LoopNode* lpn = loop->_head->as_Loop();
2268 Node* entry = lpn->in(LoopNode::EntryControl);
2269 Node* predicate_proj = find_predicate(entry); // loop_limit_check first
2270 if (predicate_proj != NULL ) { // right pattern that can be used by loop predication
2271 assert(entry->in(0)->in(1)->in(1)->Opcode() == Op_Opaque1, "must be");
2272 useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one
2273 entry = entry->in(0)->in(0);
2274 }
2275 predicate_proj = find_predicate(entry); // Predicate
2276 if (predicate_proj != NULL ) {
2277 useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one
2278 }
2279 }
2280
2281 if (loop->_next) { // sibling
2282 collect_potentially_useful_predicates(loop->_next, useful_predicates);
2283 }
2284 }
2285
2286 //------------------------eliminate_useless_predicates-----------------------------
2287 // Eliminate all inserted predicates if they could not be used by loop predication.
2288 // Note: it will also eliminates loop limits check predicate since it also uses
2289 // Opaque1 node (see Parse::add_predicate()).
2290 void PhaseIdealLoop::eliminate_useless_predicates() {
2291 if (C->predicate_count() == 0)
2292 return; // no predicate left
2293
2294 Unique_Node_List useful_predicates; // to store useful predicates
2295 if (C->has_loops()) {
2296 collect_potentially_useful_predicates(_ltree_root->_child, useful_predicates);
2297 }
2298
2299 for (int i = C->predicate_count(); i > 0; i--) {
2300 Node * n = C->predicate_opaque1_node(i-1);
2301 assert(n->Opcode() == Op_Opaque1, "must be");
2302 if (!useful_predicates.member(n)) { // not in the useful list
2303 _igvn.replace_node(n, n->in(1));
2304 }
2305 }
2306 }
2307
2308 //------------------------process_expensive_nodes-----------------------------
2309 // Expensive nodes have their control input set to prevent the GVN
2310 // from commoning them and as a result forcing the resulting node to
2311 // be in a more frequent path. Use CFG information here, to change the
2312 // control inputs so that some expensive nodes can be commoned while
2313 // not executed more frequently.
2314 bool PhaseIdealLoop::process_expensive_nodes() {
2315 assert(OptimizeExpensiveOps, "optimization off?");
2316
2317 // Sort nodes to bring similar nodes together
2318 C->sort_expensive_nodes();
2319
2320 bool progress = false;
2321
2322 for (int i = 0; i < C->expensive_count(); ) {
2323 Node* n = C->expensive_node(i);
2324 int start = i;
2325 // Find nodes similar to n
2326 i++;
2327 for (; i < C->expensive_count() && Compile::cmp_expensive_nodes(n, C->expensive_node(i)) == 0; i++);
2328 int end = i;
2329 // And compare them two by two
2330 for (int j = start; j < end; j++) {
2331 Node* n1 = C->expensive_node(j);
2332 if (is_node_unreachable(n1)) {
2333 continue;
2334 }
2335 for (int k = j+1; k < end; k++) {
2336 Node* n2 = C->expensive_node(k);
2337 if (is_node_unreachable(n2)) {
2338 continue;
2339 }
2340
2341 assert(n1 != n2, "should be pair of nodes");
2342
2343 Node* c1 = n1->in(0);
2344 Node* c2 = n2->in(0);
2345
2346 Node* parent_c1 = c1;
2347 Node* parent_c2 = c2;
2348
2349 // The call to get_early_ctrl_for_expensive() moves the
2350 // expensive nodes up but stops at loops that are in a if
2351 // branch. See whether we can exit the loop and move above the
2352 // If.
2353 if (c1->is_Loop()) {
2354 parent_c1 = c1->in(1);
2355 }
2356 if (c2->is_Loop()) {
2357 parent_c2 = c2->in(1);
2358 }
2359
2360 if (parent_c1 == parent_c2) {
2361 _igvn._worklist.push(n1);
2362 _igvn._worklist.push(n2);
2363 continue;
2364 }
2365
2366 // Look for identical expensive node up the dominator chain.
2367 if (is_dominator(c1, c2)) {
2368 c2 = c1;
2369 } else if (is_dominator(c2, c1)) {
2370 c1 = c2;
2371 } else if (parent_c1->is_Proj() && parent_c1->in(0)->is_If() &&
2372 parent_c2->is_Proj() && parent_c1->in(0) == parent_c2->in(0)) {
2373 // Both branches have the same expensive node so move it up
2374 // before the if.
2375 c1 = c2 = idom(parent_c1->in(0));
2376 }
2377 // Do the actual moves
2378 if (n1->in(0) != c1) {
2379 _igvn.hash_delete(n1);
2380 n1->set_req(0, c1);
2381 _igvn.hash_insert(n1);
2382 _igvn._worklist.push(n1);
2383 progress = true;
2384 }
2385 if (n2->in(0) != c2) {
2386 _igvn.hash_delete(n2);
2387 n2->set_req(0, c2);
2388 _igvn.hash_insert(n2);
2389 _igvn._worklist.push(n2);
2390 progress = true;
2391 }
2392 }
2393 }
2394 }
2395
2396 return progress;
2397 }
2398
2399
2400 //=============================================================================
2401 //----------------------------build_and_optimize-------------------------------
2402 // Create a PhaseLoop. Build the ideal Loop tree. Map each Ideal Node to
2403 // its corresponding LoopNode. If 'optimize' is true, do some loop cleanups.
2404 void PhaseIdealLoop::build_and_optimize(bool do_split_ifs, bool skip_loop_opts) {
2405 ResourceMark rm;
2406
2407 int old_progress = C->major_progress();
2408 uint orig_worklist_size = _igvn._worklist.size();
2409
2410 // Reset major-progress flag for the driver's heuristics
2411 C->clear_major_progress();
2412
2413 #ifndef PRODUCT
2414 // Capture for later assert
2415 uint unique = C->unique();
2416 _loop_invokes++;
2417 _loop_work += unique;
2418 #endif
2419
2420 // True if the method has at least 1 irreducible loop
2421 _has_irreducible_loops = false;
2422
2423 _created_loop_node = false;
2424
2425 Arena *a = Thread::current()->resource_area();
2426 VectorSet visited(a);
2427 // Pre-grow the mapping from Nodes to IdealLoopTrees.
2428 _nodes.map(C->unique(), NULL);
2429 memset(_nodes.adr(), 0, wordSize * C->unique());
2430
2431 // Pre-build the top-level outermost loop tree entry
2432 _ltree_root = new IdealLoopTree( this, C->root(), C->root() );
2433 // Do not need a safepoint at the top level
2434 _ltree_root->_has_sfpt = 1;
2435
2436 // Initialize Dominators.
2437 // Checked in clone_loop_predicate() during beautify_loops().
2438 _idom_size = 0;
2439 _idom = NULL;
2440 _dom_depth = NULL;
2441 _dom_stk = NULL;
2442
2443 // Empty pre-order array
2444 allocate_preorders();
2445
2446 // Build a loop tree on the fly. Build a mapping from CFG nodes to
2447 // IdealLoopTree entries. Data nodes are NOT walked.
2448 build_loop_tree();
2449 // Check for bailout, and return
2450 if (C->failing()) {
2451 return;
2452 }
2453
2454 // No loops after all
2455 if( !_ltree_root->_child && !_verify_only ) C->set_has_loops(false);
2456
2457 // There should always be an outer loop containing the Root and Return nodes.
2458 // If not, we have a degenerate empty program. Bail out in this case.
2459 if (!has_node(C->root())) {
2460 if (!_verify_only) {
2461 C->clear_major_progress();
2462 C->record_method_not_compilable("empty program detected during loop optimization");
2463 }
2464 return;
2465 }
2466
2467 // Nothing to do, so get out
2468 bool stop_early = !C->has_loops() && !skip_loop_opts && !do_split_ifs && !_verify_me && !_verify_only;
2469 bool do_expensive_nodes = C->should_optimize_expensive_nodes(_igvn);
2470 if (stop_early && !do_expensive_nodes) {
2471 _igvn.optimize(); // Cleanup NeverBranches
2472 return;
2473 }
2474
2475 // Set loop nesting depth
2476 _ltree_root->set_nest( 0 );
2477
2478 // Split shared headers and insert loop landing pads.
2479 // Do not bother doing this on the Root loop of course.
2480 if( !_verify_me && !_verify_only && _ltree_root->_child ) {
2481 C->print_method(PHASE_BEFORE_BEAUTIFY_LOOPS, 3);
2482 if( _ltree_root->_child->beautify_loops( this ) ) {
2483 // Re-build loop tree!
2484 _ltree_root->_child = NULL;
2485 _nodes.clear();
2486 reallocate_preorders();
2487 build_loop_tree();
2488 // Check for bailout, and return
2489 if (C->failing()) {
2490 return;
2491 }
2492 // Reset loop nesting depth
2493 _ltree_root->set_nest( 0 );
2494
2495 C->print_method(PHASE_AFTER_BEAUTIFY_LOOPS, 3);
2496 }
2497 }
2498
2499 // Build Dominators for elision of NULL checks & loop finding.
2500 // Since nodes do not have a slot for immediate dominator, make
2501 // a persistent side array for that info indexed on node->_idx.
2502 _idom_size = C->unique();
2503 _idom = NEW_RESOURCE_ARRAY( Node*, _idom_size );
2504 _dom_depth = NEW_RESOURCE_ARRAY( uint, _idom_size );
2505 _dom_stk = NULL; // Allocated on demand in recompute_dom_depth
2506 memset( _dom_depth, 0, _idom_size * sizeof(uint) );
2507
2508 Dominators();
2509
2510 if (!_verify_only) {
2511 // As a side effect, Dominators removed any unreachable CFG paths
2512 // into RegionNodes. It doesn't do this test against Root, so
2513 // we do it here.
2514 for( uint i = 1; i < C->root()->req(); i++ ) {
2515 if( !_nodes[C->root()->in(i)->_idx] ) { // Dead path into Root?
2516 _igvn.delete_input_of(C->root(), i);
2517 i--; // Rerun same iteration on compressed edges
2518 }
2519 }
2520
2521 // Given dominators, try to find inner loops with calls that must
2522 // always be executed (call dominates loop tail). These loops do
2523 // not need a separate safepoint.
2524 Node_List cisstack(a);
2525 _ltree_root->check_safepts(visited, cisstack);
2526 }
2527
2528 // Walk the DATA nodes and place into loops. Find earliest control
2529 // node. For CFG nodes, the _nodes array starts out and remains
2530 // holding the associated IdealLoopTree pointer. For DATA nodes, the
2531 // _nodes array holds the earliest legal controlling CFG node.
2532
2533 // Allocate stack with enough space to avoid frequent realloc
2534 int stack_size = (C->live_nodes() >> 1) + 16; // (live_nodes>>1)+16 from Java2D stats
2535 Node_Stack nstack( a, stack_size );
2536
2537 visited.Clear();
2538 Node_List worklist(a);
2539 // Don't need C->root() on worklist since
2540 // it will be processed among C->top() inputs
2541 worklist.push( C->top() );
2542 visited.set( C->top()->_idx ); // Set C->top() as visited now
2543 build_loop_early( visited, worklist, nstack );
2544
2545 // Given early legal placement, try finding counted loops. This placement
2546 // is good enough to discover most loop invariants.
2547 if( !_verify_me && !_verify_only )
2548 _ltree_root->counted_loop( this );
2549
2550 // Find latest loop placement. Find ideal loop placement.
2551 visited.Clear();
2552 init_dom_lca_tags();
2553 // Need C->root() on worklist when processing outs
2554 worklist.push( C->root() );
2555 NOT_PRODUCT( C->verify_graph_edges(); )
2556 worklist.push( C->top() );
2557 build_loop_late( visited, worklist, nstack );
2558
2559 if (_verify_only) {
2560 // restore major progress flag
2561 for (int i = 0; i < old_progress; i++)
2562 C->set_major_progress();
2563 assert(C->unique() == unique, "verification mode made Nodes? ? ?");
2564 assert(_igvn._worklist.size() == orig_worklist_size, "shouldn't push anything");
2565 return;
2566 }
2567
2568 // clear out the dead code after build_loop_late
2569 while (_deadlist.size()) {
2570 _igvn.remove_globally_dead_node(_deadlist.pop());
2571 }
2572
2573 if (stop_early) {
2574 assert(do_expensive_nodes, "why are we here?");
2575 if (process_expensive_nodes()) {
2576 // If we made some progress when processing expensive nodes then
2577 // the IGVN may modify the graph in a way that will allow us to
2578 // make some more progress: we need to try processing expensive
2579 // nodes again.
2580 C->set_major_progress();
2581 }
2582 _igvn.optimize();
2583 return;
2584 }
2585
2586 // Some parser-inserted loop predicates could never be used by loop
2587 // predication or they were moved away from loop during some optimizations.
2588 // For example, peeling. Eliminate them before next loop optimizations.
2589 eliminate_useless_predicates();
2590
2591 #ifndef PRODUCT
2592 C->verify_graph_edges();
2593 if (_verify_me) { // Nested verify pass?
2594 // Check to see if the verify mode is broken
2595 assert(C->unique() == unique, "non-optimize mode made Nodes? ? ?");
2596 return;
2597 }
2598 if(VerifyLoopOptimizations) verify();
2599 if(TraceLoopOpts && C->has_loops()) {
2600 _ltree_root->dump();
2601 }
2602 #endif
2603
2604 if (skip_loop_opts) {
2605 // restore major progress flag
2606 for (int i = 0; i < old_progress; i++) {
2607 C->set_major_progress();
2608 }
2609
2610 // Cleanup any modified bits
2611 _igvn.optimize();
2612
2613 if (C->log() != NULL) {
2614 log_loop_tree(_ltree_root, _ltree_root, C->log());
2615 }
2616 return;
2617 }
2618
2619 if (ReassociateInvariants) {
2620 // Reassociate invariants and prep for split_thru_phi
2621 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
2622 IdealLoopTree* lpt = iter.current();
2623 bool is_counted = lpt->is_counted();
2624 if (!is_counted || !lpt->is_inner()) continue;
2625
2626 // check for vectorized loops, any reassociation of invariants was already done
2627 if (is_counted && lpt->_head->as_CountedLoop()->do_unroll_only()) continue;
2628
2629 lpt->reassociate_invariants(this);
2630
2631 // Because RCE opportunities can be masked by split_thru_phi,
2632 // look for RCE candidates and inhibit split_thru_phi
2633 // on just their loop-phi's for this pass of loop opts
2634 if (SplitIfBlocks && do_split_ifs) {
2635 if (lpt->policy_range_check(this)) {
2636 lpt->_rce_candidate = 1; // = true
2637 }
2638 }
2639 }
2640 }
2641
2642 // Check for aggressive application of split-if and other transforms
2643 // that require basic-block info (like cloning through Phi's)
2644 if( SplitIfBlocks && do_split_ifs ) {
2645 visited.Clear();
2646 split_if_with_blocks( visited, nstack );
2647 NOT_PRODUCT( if( VerifyLoopOptimizations ) verify(); );
2648 }
2649
2650 if (!C->major_progress() && do_expensive_nodes && process_expensive_nodes()) {
2651 C->set_major_progress();
2652 }
2653
2654 // Perform loop predication before iteration splitting
2655 if (C->has_loops() && !C->major_progress() && (C->predicate_count() > 0)) {
2656 _ltree_root->_child->loop_predication(this);
2657 }
2658
2659 if (OptimizeFill && UseLoopPredicate && C->has_loops() && !C->major_progress()) {
2660 if (do_intrinsify_fill()) {
2661 C->set_major_progress();
2662 }
2663 }
2664
2665 // Perform iteration-splitting on inner loops. Split iterations to avoid
2666 // range checks or one-shot null checks.
2667
2668 // If split-if's didn't hack the graph too bad (no CFG changes)
2669 // then do loop opts.
2670 if (C->has_loops() && !C->major_progress()) {
2671 memset( worklist.adr(), 0, worklist.Size()*sizeof(Node*) );
2672 _ltree_root->_child->iteration_split( this, worklist );
2673 // No verify after peeling! GCM has hoisted code out of the loop.
2674 // After peeling, the hoisted code could sink inside the peeled area.
2675 // The peeling code does not try to recompute the best location for
2676 // all the code before the peeled area, so the verify pass will always
2677 // complain about it.
2678 }
2679 // Do verify graph edges in any case
2680 NOT_PRODUCT( C->verify_graph_edges(); );
2681
2682 if (!do_split_ifs) {
2683 // We saw major progress in Split-If to get here. We forced a
2684 // pass with unrolling and not split-if, however more split-if's
2685 // might make progress. If the unrolling didn't make progress
2686 // then the major-progress flag got cleared and we won't try
2687 // another round of Split-If. In particular the ever-common
2688 // instance-of/check-cast pattern requires at least 2 rounds of
2689 // Split-If to clear out.
2690 C->set_major_progress();
2691 }
2692
2693 // Repeat loop optimizations if new loops were seen
2694 if (created_loop_node()) {
2695 C->set_major_progress();
2696 }
2697
2698 // Keep loop predicates and perform optimizations with them
2699 // until no more loop optimizations could be done.
2700 // After that switch predicates off and do more loop optimizations.
2701 if (!C->major_progress() && (C->predicate_count() > 0)) {
2702 C->cleanup_loop_predicates(_igvn);
2703 if (TraceLoopOpts) {
2704 tty->print_cr("PredicatesOff");
2705 }
2706 C->set_major_progress();
2707 }
2708
2709 // Convert scalar to superword operations at the end of all loop opts.
2710 if (UseSuperWord && C->has_loops() && !C->major_progress()) {
2711 // SuperWord transform
2712 SuperWord sw(this);
2713 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
2714 IdealLoopTree* lpt = iter.current();
2715 if (lpt->is_counted()) {
2716 CountedLoopNode *cl = lpt->_head->as_CountedLoop();
2717
2718 if (PostLoopMultiversioning && cl->is_rce_post_loop() && !cl->is_vectorized_loop()) {
2719 // Check that the rce'd post loop is encountered first, multiversion after all
2720 // major main loop optimization are concluded
2721 if (!C->major_progress()) {
2722 IdealLoopTree *lpt_next = lpt->_next;
2723 if (lpt_next && lpt_next->is_counted()) {
2724 CountedLoopNode *cl = lpt_next->_head->as_CountedLoop();
2725 has_range_checks(lpt_next);
2726 if (cl->is_post_loop() && cl->range_checks_present()) {
2727 if (!cl->is_multiversioned()) {
2728 if (multi_version_post_loops(lpt, lpt_next) == false) {
2729 // Cause the rce loop to be optimized away if we fail
2730 cl->mark_is_multiversioned();
2731 cl->set_slp_max_unroll(0);
2732 poison_rce_post_loop(lpt);
2733 }
2734 }
2735 }
2736 }
2737 sw.transform_loop(lpt, true);
2738 }
2739 } else if (cl->is_main_loop()) {
2740 sw.transform_loop(lpt, true);
2741 }
2742 }
2743 }
2744 }
2745
2746 // Cleanup any modified bits
2747 _igvn.optimize();
2748
2749 // disable assert until issue with split_flow_path is resolved (6742111)
2750 // assert(!_has_irreducible_loops || C->parsed_irreducible_loop() || C->is_osr_compilation(),
2751 // "shouldn't introduce irreducible loops");
2752
2753 if (C->log() != NULL) {
2754 log_loop_tree(_ltree_root, _ltree_root, C->log());
2755 }
2756 }
2757
2758 #ifndef PRODUCT
2759 //------------------------------print_statistics-------------------------------
2760 int PhaseIdealLoop::_loop_invokes=0;// Count of PhaseIdealLoop invokes
2761 int PhaseIdealLoop::_loop_work=0; // Sum of PhaseIdealLoop x unique
2762 void PhaseIdealLoop::print_statistics() {
2763 tty->print_cr("PhaseIdealLoop=%d, sum _unique=%d", _loop_invokes, _loop_work);
2764 }
2765
2766 //------------------------------verify-----------------------------------------
2767 // Build a verify-only PhaseIdealLoop, and see that it agrees with me.
2768 static int fail; // debug only, so its multi-thread dont care
2769 void PhaseIdealLoop::verify() const {
2770 int old_progress = C->major_progress();
2771 ResourceMark rm;
2772 PhaseIdealLoop loop_verify( _igvn, this );
2773 VectorSet visited(Thread::current()->resource_area());
2774
2775 fail = 0;
2776 verify_compare( C->root(), &loop_verify, visited );
2777 assert( fail == 0, "verify loops failed" );
2778 // Verify loop structure is the same
2779 _ltree_root->verify_tree(loop_verify._ltree_root, NULL);
2780 // Reset major-progress. It was cleared by creating a verify version of
2781 // PhaseIdealLoop.
2782 for( int i=0; i<old_progress; i++ )
2783 C->set_major_progress();
2784 }
2785
2786 //------------------------------verify_compare---------------------------------
2787 // Make sure me and the given PhaseIdealLoop agree on key data structures
2788 void PhaseIdealLoop::verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const {
2789 if( !n ) return;
2790 if( visited.test_set( n->_idx ) ) return;
2791 if( !_nodes[n->_idx] ) { // Unreachable
2792 assert( !loop_verify->_nodes[n->_idx], "both should be unreachable" );
2793 return;
2794 }
2795
2796 uint i;
2797 for( i = 0; i < n->req(); i++ )
2798 verify_compare( n->in(i), loop_verify, visited );
2799
2800 // Check the '_nodes' block/loop structure
2801 i = n->_idx;
2802 if( has_ctrl(n) ) { // We have control; verify has loop or ctrl
2803 if( _nodes[i] != loop_verify->_nodes[i] &&
2804 get_ctrl_no_update(n) != loop_verify->get_ctrl_no_update(n) ) {
2805 tty->print("Mismatched control setting for: ");
2806 n->dump();
2807 if( fail++ > 10 ) return;
2808 Node *c = get_ctrl_no_update(n);
2809 tty->print("We have it as: ");
2810 if( c->in(0) ) c->dump();
2811 else tty->print_cr("N%d",c->_idx);
2812 tty->print("Verify thinks: ");
2813 if( loop_verify->has_ctrl(n) )
2814 loop_verify->get_ctrl_no_update(n)->dump();
2815 else
2816 loop_verify->get_loop_idx(n)->dump();
2817 tty->cr();
2818 }
2819 } else { // We have a loop
2820 IdealLoopTree *us = get_loop_idx(n);
2821 if( loop_verify->has_ctrl(n) ) {
2822 tty->print("Mismatched loop setting for: ");
2823 n->dump();
2824 if( fail++ > 10 ) return;
2825 tty->print("We have it as: ");
2826 us->dump();
2827 tty->print("Verify thinks: ");
2828 loop_verify->get_ctrl_no_update(n)->dump();
2829 tty->cr();
2830 } else if (!C->major_progress()) {
2831 // Loop selection can be messed up if we did a major progress
2832 // operation, like split-if. Do not verify in that case.
2833 IdealLoopTree *them = loop_verify->get_loop_idx(n);
2834 if( us->_head != them->_head || us->_tail != them->_tail ) {
2835 tty->print("Unequals loops for: ");
2836 n->dump();
2837 if( fail++ > 10 ) return;
2838 tty->print("We have it as: ");
2839 us->dump();
2840 tty->print("Verify thinks: ");
2841 them->dump();
2842 tty->cr();
2843 }
2844 }
2845 }
2846
2847 // Check for immediate dominators being equal
2848 if( i >= _idom_size ) {
2849 if( !n->is_CFG() ) return;
2850 tty->print("CFG Node with no idom: ");
2851 n->dump();
2852 return;
2853 }
2854 if( !n->is_CFG() ) return;
2855 if( n == C->root() ) return; // No IDOM here
2856
2857 assert(n->_idx == i, "sanity");
2858 Node *id = idom_no_update(n);
2859 if( id != loop_verify->idom_no_update(n) ) {
2860 tty->print("Unequals idoms for: ");
2861 n->dump();
2862 if( fail++ > 10 ) return;
2863 tty->print("We have it as: ");
2864 id->dump();
2865 tty->print("Verify thinks: ");
2866 loop_verify->idom_no_update(n)->dump();
2867 tty->cr();
2868 }
2869
2870 }
2871
2872 //------------------------------verify_tree------------------------------------
2873 // Verify that tree structures match. Because the CFG can change, siblings
2874 // within the loop tree can be reordered. We attempt to deal with that by
2875 // reordering the verify's loop tree if possible.
2876 void IdealLoopTree::verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const {
2877 assert( _parent == parent, "Badly formed loop tree" );
2878
2879 // Siblings not in same order? Attempt to re-order.
2880 if( _head != loop->_head ) {
2881 // Find _next pointer to update
2882 IdealLoopTree **pp = &loop->_parent->_child;
2883 while( *pp != loop )
2884 pp = &((*pp)->_next);
2885 // Find proper sibling to be next
2886 IdealLoopTree **nn = &loop->_next;
2887 while( (*nn) && (*nn)->_head != _head )
2888 nn = &((*nn)->_next);
2889
2890 // Check for no match.
2891 if( !(*nn) ) {
2892 // Annoyingly, irreducible loops can pick different headers
2893 // after a major_progress operation, so the rest of the loop
2894 // tree cannot be matched.
2895 if (_irreducible && Compile::current()->major_progress()) return;
2896 assert( 0, "failed to match loop tree" );
2897 }
2898
2899 // Move (*nn) to (*pp)
2900 IdealLoopTree *hit = *nn;
2901 *nn = hit->_next;
2902 hit->_next = loop;
2903 *pp = loop;
2904 loop = hit;
2905 // Now try again to verify
2906 }
2907
2908 assert( _head == loop->_head , "mismatched loop head" );
2909 Node *tail = _tail; // Inline a non-updating version of
2910 while( !tail->in(0) ) // the 'tail()' call.
2911 tail = tail->in(1);
2912 assert( tail == loop->_tail, "mismatched loop tail" );
2913
2914 // Counted loops that are guarded should be able to find their guards
2915 if( _head->is_CountedLoop() && _head->as_CountedLoop()->is_main_loop() ) {
2916 CountedLoopNode *cl = _head->as_CountedLoop();
2917 Node *init = cl->init_trip();
2918 Node *ctrl = cl->in(LoopNode::EntryControl);
2919 assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" );
2920 Node *iff = ctrl->in(0);
2921 assert( iff->Opcode() == Op_If, "" );
2922 Node *bol = iff->in(1);
2923 assert( bol->Opcode() == Op_Bool, "" );
2924 Node *cmp = bol->in(1);
2925 assert( cmp->Opcode() == Op_CmpI, "" );
2926 Node *add = cmp->in(1);
2927 Node *opaq;
2928 if( add->Opcode() == Op_Opaque1 ) {
2929 opaq = add;
2930 } else {
2931 assert( add->Opcode() == Op_AddI || add->Opcode() == Op_ConI , "" );
2932 assert( add == init, "" );
2933 opaq = cmp->in(2);
2934 }
2935 assert( opaq->Opcode() == Op_Opaque1, "" );
2936
2937 }
2938
2939 if (_child != NULL) _child->verify_tree(loop->_child, this);
2940 if (_next != NULL) _next ->verify_tree(loop->_next, parent);
2941 // Innermost loops need to verify loop bodies,
2942 // but only if no 'major_progress'
2943 int fail = 0;
2944 if (!Compile::current()->major_progress() && _child == NULL) {
2945 for( uint i = 0; i < _body.size(); i++ ) {
2946 Node *n = _body.at(i);
2947 if (n->outcnt() == 0) continue; // Ignore dead
2948 uint j;
2949 for( j = 0; j < loop->_body.size(); j++ )
2950 if( loop->_body.at(j) == n )
2951 break;
2952 if( j == loop->_body.size() ) { // Not found in loop body
2953 // Last ditch effort to avoid assertion: Its possible that we
2954 // have some users (so outcnt not zero) but are still dead.
2955 // Try to find from root.
2956 if (Compile::current()->root()->find(n->_idx)) {
2957 fail++;
2958 tty->print("We have that verify does not: ");
2959 n->dump();
2960 }
2961 }
2962 }
2963 for( uint i2 = 0; i2 < loop->_body.size(); i2++ ) {
2964 Node *n = loop->_body.at(i2);
2965 if (n->outcnt() == 0) continue; // Ignore dead
2966 uint j;
2967 for( j = 0; j < _body.size(); j++ )
2968 if( _body.at(j) == n )
2969 break;
2970 if( j == _body.size() ) { // Not found in loop body
2971 // Last ditch effort to avoid assertion: Its possible that we
2972 // have some users (so outcnt not zero) but are still dead.
2973 // Try to find from root.
2974 if (Compile::current()->root()->find(n->_idx)) {
2975 fail++;
2976 tty->print("Verify has that we do not: ");
2977 n->dump();
2978 }
2979 }
2980 }
2981 assert( !fail, "loop body mismatch" );
2982 }
2983 }
2984
2985 #endif
2986
2987 //------------------------------set_idom---------------------------------------
2988 void PhaseIdealLoop::set_idom(Node* d, Node* n, uint dom_depth) {
2989 uint idx = d->_idx;
2990 if (idx >= _idom_size) {
2991 uint newsize = _idom_size<<1;
2992 while( idx >= newsize ) {
2993 newsize <<= 1;
2994 }
2995 _idom = REALLOC_RESOURCE_ARRAY( Node*, _idom,_idom_size,newsize);
2996 _dom_depth = REALLOC_RESOURCE_ARRAY( uint, _dom_depth,_idom_size,newsize);
2997 memset( _dom_depth + _idom_size, 0, (newsize - _idom_size) * sizeof(uint) );
2998 _idom_size = newsize;
2999 }
3000 _idom[idx] = n;
3001 _dom_depth[idx] = dom_depth;
3002 }
3003
3004 //------------------------------recompute_dom_depth---------------------------------------
3005 // The dominator tree is constructed with only parent pointers.
3006 // This recomputes the depth in the tree by first tagging all
3007 // nodes as "no depth yet" marker. The next pass then runs up
3008 // the dom tree from each node marked "no depth yet", and computes
3009 // the depth on the way back down.
3010 void PhaseIdealLoop::recompute_dom_depth() {
3011 uint no_depth_marker = C->unique();
3012 uint i;
3013 // Initialize depth to "no depth yet"
3014 for (i = 0; i < _idom_size; i++) {
3015 if (_dom_depth[i] > 0 && _idom[i] != NULL) {
3016 _dom_depth[i] = no_depth_marker;
3017 }
3018 }
3019 if (_dom_stk == NULL) {
3020 uint init_size = C->live_nodes() / 100; // Guess that 1/100 is a reasonable initial size.
3021 if (init_size < 10) init_size = 10;
3022 _dom_stk = new GrowableArray<uint>(init_size);
3023 }
3024 // Compute new depth for each node.
3025 for (i = 0; i < _idom_size; i++) {
3026 uint j = i;
3027 // Run up the dom tree to find a node with a depth
3028 while (_dom_depth[j] == no_depth_marker) {
3029 _dom_stk->push(j);
3030 j = _idom[j]->_idx;
3031 }
3032 // Compute the depth on the way back down this tree branch
3033 uint dd = _dom_depth[j] + 1;
3034 while (_dom_stk->length() > 0) {
3035 uint j = _dom_stk->pop();
3036 _dom_depth[j] = dd;
3037 dd++;
3038 }
3039 }
3040 }
3041
3042 //------------------------------sort-------------------------------------------
3043 // Insert 'loop' into the existing loop tree. 'innermost' is a leaf of the
3044 // loop tree, not the root.
3045 IdealLoopTree *PhaseIdealLoop::sort( IdealLoopTree *loop, IdealLoopTree *innermost ) {
3046 if( !innermost ) return loop; // New innermost loop
3047
3048 int loop_preorder = get_preorder(loop->_head); // Cache pre-order number
3049 assert( loop_preorder, "not yet post-walked loop" );
3050 IdealLoopTree **pp = &innermost; // Pointer to previous next-pointer
3051 IdealLoopTree *l = *pp; // Do I go before or after 'l'?
3052
3053 // Insert at start of list
3054 while( l ) { // Insertion sort based on pre-order
3055 if( l == loop ) return innermost; // Already on list!
3056 int l_preorder = get_preorder(l->_head); // Cache pre-order number
3057 assert( l_preorder, "not yet post-walked l" );
3058 // Check header pre-order number to figure proper nesting
3059 if( loop_preorder > l_preorder )
3060 break; // End of insertion
3061 // If headers tie (e.g., shared headers) check tail pre-order numbers.
3062 // Since I split shared headers, you'd think this could not happen.
3063 // BUT: I must first do the preorder numbering before I can discover I
3064 // have shared headers, so the split headers all get the same preorder
3065 // number as the RegionNode they split from.
3066 if( loop_preorder == l_preorder &&
3067 get_preorder(loop->_tail) < get_preorder(l->_tail) )
3068 break; // Also check for shared headers (same pre#)
3069 pp = &l->_parent; // Chain up list
3070 l = *pp;
3071 }
3072 // Link into list
3073 // Point predecessor to me
3074 *pp = loop;
3075 // Point me to successor
3076 IdealLoopTree *p = loop->_parent;
3077 loop->_parent = l; // Point me to successor
3078 if( p ) sort( p, innermost ); // Insert my parents into list as well
3079 return innermost;
3080 }
3081
3082 //------------------------------build_loop_tree--------------------------------
3083 // I use a modified Vick/Tarjan algorithm. I need pre- and a post- visit
3084 // bits. The _nodes[] array is mapped by Node index and holds a NULL for
3085 // not-yet-pre-walked, pre-order # for pre-but-not-post-walked and holds the
3086 // tightest enclosing IdealLoopTree for post-walked.
3087 //
3088 // During my forward walk I do a short 1-layer lookahead to see if I can find
3089 // a loop backedge with that doesn't have any work on the backedge. This
3090 // helps me construct nested loops with shared headers better.
3091 //
3092 // Once I've done the forward recursion, I do the post-work. For each child
3093 // I check to see if there is a backedge. Backedges define a loop! I
3094 // insert an IdealLoopTree at the target of the backedge.
3095 //
3096 // During the post-work I also check to see if I have several children
3097 // belonging to different loops. If so, then this Node is a decision point
3098 // where control flow can choose to change loop nests. It is at this
3099 // decision point where I can figure out how loops are nested. At this
3100 // time I can properly order the different loop nests from my children.
3101 // Note that there may not be any backedges at the decision point!
3102 //
3103 // Since the decision point can be far removed from the backedges, I can't
3104 // order my loops at the time I discover them. Thus at the decision point
3105 // I need to inspect loop header pre-order numbers to properly nest my
3106 // loops. This means I need to sort my childrens' loops by pre-order.
3107 // The sort is of size number-of-control-children, which generally limits
3108 // it to size 2 (i.e., I just choose between my 2 target loops).
3109 void PhaseIdealLoop::build_loop_tree() {
3110 // Allocate stack of size C->live_nodes()/2 to avoid frequent realloc
3111 GrowableArray <Node *> bltstack(C->live_nodes() >> 1);
3112 Node *n = C->root();
3113 bltstack.push(n);
3114 int pre_order = 1;
3115 int stack_size;
3116
3117 while ( ( stack_size = bltstack.length() ) != 0 ) {
3118 n = bltstack.top(); // Leave node on stack
3119 if ( !is_visited(n) ) {
3120 // ---- Pre-pass Work ----
3121 // Pre-walked but not post-walked nodes need a pre_order number.
3122
3123 set_preorder_visited( n, pre_order ); // set as visited
3124
3125 // ---- Scan over children ----
3126 // Scan first over control projections that lead to loop headers.
3127 // This helps us find inner-to-outer loops with shared headers better.
3128
3129 // Scan children's children for loop headers.
3130 for ( int i = n->outcnt() - 1; i >= 0; --i ) {
3131 Node* m = n->raw_out(i); // Child
3132 if( m->is_CFG() && !is_visited(m) ) { // Only for CFG children
3133 // Scan over children's children to find loop
3134 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3135 Node* l = m->fast_out(j);
3136 if( is_visited(l) && // Been visited?
3137 !is_postvisited(l) && // But not post-visited
3138 get_preorder(l) < pre_order ) { // And smaller pre-order
3139 // Found! Scan the DFS down this path before doing other paths
3140 bltstack.push(m);
3141 break;
3142 }
3143 }
3144 }
3145 }
3146 pre_order++;
3147 }
3148 else if ( !is_postvisited(n) ) {
3149 // Note: build_loop_tree_impl() adds out edges on rare occasions,
3150 // such as com.sun.rsasign.am::a.
3151 // For non-recursive version, first, process current children.
3152 // On next iteration, check if additional children were added.
3153 for ( int k = n->outcnt() - 1; k >= 0; --k ) {
3154 Node* u = n->raw_out(k);
3155 if ( u->is_CFG() && !is_visited(u) ) {
3156 bltstack.push(u);
3157 }
3158 }
3159 if ( bltstack.length() == stack_size ) {
3160 // There were no additional children, post visit node now
3161 (void)bltstack.pop(); // Remove node from stack
3162 pre_order = build_loop_tree_impl( n, pre_order );
3163 // Check for bailout
3164 if (C->failing()) {
3165 return;
3166 }
3167 // Check to grow _preorders[] array for the case when
3168 // build_loop_tree_impl() adds new nodes.
3169 check_grow_preorders();
3170 }
3171 }
3172 else {
3173 (void)bltstack.pop(); // Remove post-visited node from stack
3174 }
3175 }
3176 }
3177
3178 //------------------------------build_loop_tree_impl---------------------------
3179 int PhaseIdealLoop::build_loop_tree_impl( Node *n, int pre_order ) {
3180 // ---- Post-pass Work ----
3181 // Pre-walked but not post-walked nodes need a pre_order number.
3182
3183 // Tightest enclosing loop for this Node
3184 IdealLoopTree *innermost = NULL;
3185
3186 // For all children, see if any edge is a backedge. If so, make a loop
3187 // for it. Then find the tightest enclosing loop for the self Node.
3188 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
3189 Node* m = n->fast_out(i); // Child
3190 if( n == m ) continue; // Ignore control self-cycles
3191 if( !m->is_CFG() ) continue;// Ignore non-CFG edges
3192
3193 IdealLoopTree *l; // Child's loop
3194 if( !is_postvisited(m) ) { // Child visited but not post-visited?
3195 // Found a backedge
3196 assert( get_preorder(m) < pre_order, "should be backedge" );
3197 // Check for the RootNode, which is already a LoopNode and is allowed
3198 // to have multiple "backedges".
3199 if( m == C->root()) { // Found the root?
3200 l = _ltree_root; // Root is the outermost LoopNode
3201 } else { // Else found a nested loop
3202 // Insert a LoopNode to mark this loop.
3203 l = new IdealLoopTree(this, m, n);
3204 } // End of Else found a nested loop
3205 if( !has_loop(m) ) // If 'm' does not already have a loop set
3206 set_loop(m, l); // Set loop header to loop now
3207
3208 } else { // Else not a nested loop
3209 if( !_nodes[m->_idx] ) continue; // Dead code has no loop
3210 l = get_loop(m); // Get previously determined loop
3211 // If successor is header of a loop (nest), move up-loop till it
3212 // is a member of some outer enclosing loop. Since there are no
3213 // shared headers (I've split them already) I only need to go up
3214 // at most 1 level.
3215 while( l && l->_head == m ) // Successor heads loop?
3216 l = l->_parent; // Move up 1 for me
3217 // If this loop is not properly parented, then this loop
3218 // has no exit path out, i.e. its an infinite loop.
3219 if( !l ) {
3220 // Make loop "reachable" from root so the CFG is reachable. Basically
3221 // insert a bogus loop exit that is never taken. 'm', the loop head,
3222 // points to 'n', one (of possibly many) fall-in paths. There may be
3223 // many backedges as well.
3224
3225 // Here I set the loop to be the root loop. I could have, after
3226 // inserting a bogus loop exit, restarted the recursion and found my
3227 // new loop exit. This would make the infinite loop a first-class
3228 // loop and it would then get properly optimized. What's the use of
3229 // optimizing an infinite loop?
3230 l = _ltree_root; // Oops, found infinite loop
3231
3232 if (!_verify_only) {
3233 // Insert the NeverBranch between 'm' and it's control user.
3234 NeverBranchNode *iff = new NeverBranchNode( m );
3235 _igvn.register_new_node_with_optimizer(iff);
3236 set_loop(iff, l);
3237 Node *if_t = new CProjNode( iff, 0 );
3238 _igvn.register_new_node_with_optimizer(if_t);
3239 set_loop(if_t, l);
3240
3241 Node* cfg = NULL; // Find the One True Control User of m
3242 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3243 Node* x = m->fast_out(j);
3244 if (x->is_CFG() && x != m && x != iff)
3245 { cfg = x; break; }
3246 }
3247 assert(cfg != NULL, "must find the control user of m");
3248 uint k = 0; // Probably cfg->in(0)
3249 while( cfg->in(k) != m ) k++; // But check incase cfg is a Region
3250 cfg->set_req( k, if_t ); // Now point to NeverBranch
3251 _igvn._worklist.push(cfg);
3252
3253 // Now create the never-taken loop exit
3254 Node *if_f = new CProjNode( iff, 1 );
3255 _igvn.register_new_node_with_optimizer(if_f);
3256 set_loop(if_f, l);
3257 // Find frame ptr for Halt. Relies on the optimizer
3258 // V-N'ing. Easier and quicker than searching through
3259 // the program structure.
3260 Node *frame = new ParmNode( C->start(), TypeFunc::FramePtr );
3261 _igvn.register_new_node_with_optimizer(frame);
3262 // Halt & Catch Fire
3263 Node *halt = new HaltNode( if_f, frame );
3264 _igvn.register_new_node_with_optimizer(halt);
3265 set_loop(halt, l);
3266 C->root()->add_req(halt);
3267 }
3268 set_loop(C->root(), _ltree_root);
3269 }
3270 }
3271 // Weeny check for irreducible. This child was already visited (this
3272 // IS the post-work phase). Is this child's loop header post-visited
3273 // as well? If so, then I found another entry into the loop.
3274 if (!_verify_only) {
3275 while( is_postvisited(l->_head) ) {
3276 // found irreducible
3277 l->_irreducible = 1; // = true
3278 l = l->_parent;
3279 _has_irreducible_loops = true;
3280 // Check for bad CFG here to prevent crash, and bailout of compile
3281 if (l == NULL) {
3282 C->record_method_not_compilable("unhandled CFG detected during loop optimization");
3283 return pre_order;
3284 }
3285 }
3286 C->set_has_irreducible_loop(_has_irreducible_loops);
3287 }
3288
3289 // This Node might be a decision point for loops. It is only if
3290 // it's children belong to several different loops. The sort call
3291 // does a trivial amount of work if there is only 1 child or all
3292 // children belong to the same loop. If however, the children
3293 // belong to different loops, the sort call will properly set the
3294 // _parent pointers to show how the loops nest.
3295 //
3296 // In any case, it returns the tightest enclosing loop.
3297 innermost = sort( l, innermost );
3298 }
3299
3300 // Def-use info will have some dead stuff; dead stuff will have no
3301 // loop decided on.
3302
3303 // Am I a loop header? If so fix up my parent's child and next ptrs.
3304 if( innermost && innermost->_head == n ) {
3305 assert( get_loop(n) == innermost, "" );
3306 IdealLoopTree *p = innermost->_parent;
3307 IdealLoopTree *l = innermost;
3308 while( p && l->_head == n ) {
3309 l->_next = p->_child; // Put self on parents 'next child'
3310 p->_child = l; // Make self as first child of parent
3311 l = p; // Now walk up the parent chain
3312 p = l->_parent;
3313 }
3314 } else {
3315 // Note that it is possible for a LoopNode to reach here, if the
3316 // backedge has been made unreachable (hence the LoopNode no longer
3317 // denotes a Loop, and will eventually be removed).
3318
3319 // Record tightest enclosing loop for self. Mark as post-visited.
3320 set_loop(n, innermost);
3321 // Also record has_call flag early on
3322 if( innermost ) {
3323 if( n->is_Call() && !n->is_CallLeaf() && !n->is_macro() ) {
3324 // Do not count uncommon calls
3325 if( !n->is_CallStaticJava() || !n->as_CallStaticJava()->_name ) {
3326 Node *iff = n->in(0)->in(0);
3327 // No any calls for vectorized loops.
3328 if( UseSuperWord || !iff->is_If() ||
3329 (n->in(0)->Opcode() == Op_IfFalse &&
3330 (1.0 - iff->as_If()->_prob) >= 0.01) ||
3331 (iff->as_If()->_prob >= 0.01) )
3332 innermost->_has_call = 1;
3333 }
3334 } else if( n->is_Allocate() && n->as_Allocate()->_is_scalar_replaceable ) {
3335 // Disable loop optimizations if the loop has a scalar replaceable
3336 // allocation. This disabling may cause a potential performance lost
3337 // if the allocation is not eliminated for some reason.
3338 innermost->_allow_optimizations = false;
3339 innermost->_has_call = 1; // = true
3340 } else if (n->Opcode() == Op_SafePoint) {
3341 // Record all safepoints in this loop.
3342 if (innermost->_safepts == NULL) innermost->_safepts = new Node_List();
3343 innermost->_safepts->push(n);
3344 }
3345 }
3346 }
3347
3348 // Flag as post-visited now
3349 set_postvisited(n);
3350 return pre_order;
3351 }
3352
3353
3354 //------------------------------build_loop_early-------------------------------
3355 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
3356 // First pass computes the earliest controlling node possible. This is the
3357 // controlling input with the deepest dominating depth.
3358 void PhaseIdealLoop::build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) {
3359 while (worklist.size() != 0) {
3360 // Use local variables nstack_top_n & nstack_top_i to cache values
3361 // on nstack's top.
3362 Node *nstack_top_n = worklist.pop();
3363 uint nstack_top_i = 0;
3364 //while_nstack_nonempty:
3365 while (true) {
3366 // Get parent node and next input's index from stack's top.
3367 Node *n = nstack_top_n;
3368 uint i = nstack_top_i;
3369 uint cnt = n->req(); // Count of inputs
3370 if (i == 0) { // Pre-process the node.
3371 if( has_node(n) && // Have either loop or control already?
3372 !has_ctrl(n) ) { // Have loop picked out already?
3373 // During "merge_many_backedges" we fold up several nested loops
3374 // into a single loop. This makes the members of the original
3375 // loop bodies pointing to dead loops; they need to move up
3376 // to the new UNION'd larger loop. I set the _head field of these
3377 // dead loops to NULL and the _parent field points to the owning
3378 // loop. Shades of UNION-FIND algorithm.
3379 IdealLoopTree *ilt;
3380 while( !(ilt = get_loop(n))->_head ) {
3381 // Normally I would use a set_loop here. But in this one special
3382 // case, it is legal (and expected) to change what loop a Node
3383 // belongs to.
3384 _nodes.map(n->_idx, (Node*)(ilt->_parent) );
3385 }
3386 // Remove safepoints ONLY if I've already seen I don't need one.
3387 // (the old code here would yank a 2nd safepoint after seeing a
3388 // first one, even though the 1st did not dominate in the loop body
3389 // and thus could be avoided indefinitely)
3390 if( !_verify_only && !_verify_me && ilt->_has_sfpt && n->Opcode() == Op_SafePoint &&
3391 is_deleteable_safept(n)) {
3392 Node *in = n->in(TypeFunc::Control);
3393 lazy_replace(n,in); // Pull safepoint now
3394 if (ilt->_safepts != NULL) {
3395 ilt->_safepts->yank(n);
3396 }
3397 // Carry on with the recursion "as if" we are walking
3398 // only the control input
3399 if( !visited.test_set( in->_idx ) ) {
3400 worklist.push(in); // Visit this guy later, using worklist
3401 }
3402 // Get next node from nstack:
3403 // - skip n's inputs processing by setting i > cnt;
3404 // - we also will not call set_early_ctrl(n) since
3405 // has_node(n) == true (see the condition above).
3406 i = cnt + 1;
3407 }
3408 }
3409 } // if (i == 0)
3410
3411 // Visit all inputs
3412 bool done = true; // Assume all n's inputs will be processed
3413 while (i < cnt) {
3414 Node *in = n->in(i);
3415 ++i;
3416 if (in == NULL) continue;
3417 if (in->pinned() && !in->is_CFG())
3418 set_ctrl(in, in->in(0));
3419 int is_visited = visited.test_set( in->_idx );
3420 if (!has_node(in)) { // No controlling input yet?
3421 assert( !in->is_CFG(), "CFG Node with no controlling input?" );
3422 assert( !is_visited, "visit only once" );
3423 nstack.push(n, i); // Save parent node and next input's index.
3424 nstack_top_n = in; // Process current input now.
3425 nstack_top_i = 0;
3426 done = false; // Not all n's inputs processed.
3427 break; // continue while_nstack_nonempty;
3428 } else if (!is_visited) {
3429 // This guy has a location picked out for him, but has not yet
3430 // been visited. Happens to all CFG nodes, for instance.
3431 // Visit him using the worklist instead of recursion, to break
3432 // cycles. Since he has a location already we do not need to
3433 // find his location before proceeding with the current Node.
3434 worklist.push(in); // Visit this guy later, using worklist
3435 }
3436 }
3437 if (done) {
3438 // All of n's inputs have been processed, complete post-processing.
3439
3440 // Compute earliest point this Node can go.
3441 // CFG, Phi, pinned nodes already know their controlling input.
3442 if (!has_node(n)) {
3443 // Record earliest legal location
3444 set_early_ctrl( n );
3445 }
3446 if (nstack.is_empty()) {
3447 // Finished all nodes on stack.
3448 // Process next node on the worklist.
3449 break;
3450 }
3451 // Get saved parent node and next input's index.
3452 nstack_top_n = nstack.node();
3453 nstack_top_i = nstack.index();
3454 nstack.pop();
3455 }
3456 } // while (true)
3457 }
3458 }
3459
3460 //------------------------------dom_lca_internal--------------------------------
3461 // Pair-wise LCA
3462 Node *PhaseIdealLoop::dom_lca_internal( Node *n1, Node *n2 ) const {
3463 if( !n1 ) return n2; // Handle NULL original LCA
3464 assert( n1->is_CFG(), "" );
3465 assert( n2->is_CFG(), "" );
3466 // find LCA of all uses
3467 uint d1 = dom_depth(n1);
3468 uint d2 = dom_depth(n2);
3469 while (n1 != n2) {
3470 if (d1 > d2) {
3471 n1 = idom(n1);
3472 d1 = dom_depth(n1);
3473 } else if (d1 < d2) {
3474 n2 = idom(n2);
3475 d2 = dom_depth(n2);
3476 } else {
3477 // Here d1 == d2. Due to edits of the dominator-tree, sections
3478 // of the tree might have the same depth. These sections have
3479 // to be searched more carefully.
3480
3481 // Scan up all the n1's with equal depth, looking for n2.
3482 Node *t1 = idom(n1);
3483 while (dom_depth(t1) == d1) {
3484 if (t1 == n2) return n2;
3485 t1 = idom(t1);
3486 }
3487 // Scan up all the n2's with equal depth, looking for n1.
3488 Node *t2 = idom(n2);
3489 while (dom_depth(t2) == d2) {
3490 if (t2 == n1) return n1;
3491 t2 = idom(t2);
3492 }
3493 // Move up to a new dominator-depth value as well as up the dom-tree.
3494 n1 = t1;
3495 n2 = t2;
3496 d1 = dom_depth(n1);
3497 d2 = dom_depth(n2);
3498 }
3499 }
3500 return n1;
3501 }
3502
3503 //------------------------------compute_idom-----------------------------------
3504 // Locally compute IDOM using dom_lca call. Correct only if the incoming
3505 // IDOMs are correct.
3506 Node *PhaseIdealLoop::compute_idom( Node *region ) const {
3507 assert( region->is_Region(), "" );
3508 Node *LCA = NULL;
3509 for( uint i = 1; i < region->req(); i++ ) {
3510 if( region->in(i) != C->top() )
3511 LCA = dom_lca( LCA, region->in(i) );
3512 }
3513 return LCA;
3514 }
3515
3516 bool PhaseIdealLoop::verify_dominance(Node* n, Node* use, Node* LCA, Node* early) {
3517 bool had_error = false;
3518 #ifdef ASSERT
3519 if (early != C->root()) {
3520 // Make sure that there's a dominance path from LCA to early
3521 Node* d = LCA;
3522 while (d != early) {
3523 if (d == C->root()) {
3524 dump_bad_graph("Bad graph detected in compute_lca_of_uses", n, early, LCA);
3525 tty->print_cr("*** Use %d isn't dominated by def %d ***", use->_idx, n->_idx);
3526 had_error = true;
3527 break;
3528 }
3529 d = idom(d);
3530 }
3531 }
3532 #endif
3533 return had_error;
3534 }
3535
3536
3537 Node* PhaseIdealLoop::compute_lca_of_uses(Node* n, Node* early, bool verify) {
3538 // Compute LCA over list of uses
3539 bool had_error = false;
3540 Node *LCA = NULL;
3541 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax && LCA != early; i++) {
3542 Node* c = n->fast_out(i);
3543 if (_nodes[c->_idx] == NULL)
3544 continue; // Skip the occasional dead node
3545 if( c->is_Phi() ) { // For Phis, we must land above on the path
3546 for( uint j=1; j<c->req(); j++ ) {// For all inputs
3547 if( c->in(j) == n ) { // Found matching input?
3548 Node *use = c->in(0)->in(j);
3549 if (_verify_only && use->is_top()) continue;
3550 LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
3551 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error;
3552 }
3553 }
3554 } else {
3555 // For CFG data-users, use is in the block just prior
3556 Node *use = has_ctrl(c) ? get_ctrl(c) : c->in(0);
3557 LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
3558 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error;
3559 }
3560 }
3561 assert(!had_error, "bad dominance");
3562 return LCA;
3563 }
3564
3565 // Check the shape of the graph at the loop entry. In some cases,
3566 // the shape of the graph does not match the shape outlined below.
3567 // That is caused by the Opaque1 node "protecting" the shape of
3568 // the graph being removed by, for example, the IGVN performed
3569 // in PhaseIdealLoop::build_and_optimize().
3570 //
3571 // After the Opaque1 node has been removed, optimizations (e.g., split-if,
3572 // loop unswitching, and IGVN, or a combination of them) can freely change
3573 // the graph's shape. As a result, the graph shape outlined below cannot
3574 // be guaranteed anymore.
3575 bool PhaseIdealLoop::is_canonical_loop_entry(CountedLoopNode* cl) {
3576 if (!cl->is_main_loop() && !cl->is_post_loop()) {
3577 return false;
3578 }
3579 Node* ctrl = cl->skip_strip_mined()->in(LoopNode::EntryControl);
3580 if (ctrl == NULL || (!ctrl->is_IfTrue() && !ctrl->is_IfFalse())) {
3581 return false;
3582 }
3583 Node* iffm = ctrl->in(0);
3584 if (iffm == NULL || !iffm->is_If()) {
3585 return false;
3586 }
3587 Node* bolzm = iffm->in(1);
3588 if (bolzm == NULL || !bolzm->is_Bool()) {
3589 return false;
3590 }
3591 Node* cmpzm = bolzm->in(1);
3592 if (cmpzm == NULL || !cmpzm->is_Cmp()) {
3593 return false;
3594 }
3595 // compares can get conditionally flipped
3596 bool found_opaque = false;
3597 for (uint i = 1; i < cmpzm->req(); i++) {
3598 Node* opnd = cmpzm->in(i);
3599 if (opnd && opnd->Opcode() == Op_Opaque1) {
3600 found_opaque = true;
3601 break;
3602 }
3603 }
3604 if (!found_opaque) {
3605 return false;
3606 }
3607 return true;
3608 }
3609
3610 //------------------------------get_late_ctrl----------------------------------
3611 // Compute latest legal control.
3612 Node *PhaseIdealLoop::get_late_ctrl( Node *n, Node *early ) {
3613 assert(early != NULL, "early control should not be NULL");
3614
3615 Node* LCA = compute_lca_of_uses(n, early);
3616 #ifdef ASSERT
3617 if (LCA == C->root() && LCA != early) {
3618 // def doesn't dominate uses so print some useful debugging output
3619 compute_lca_of_uses(n, early, true);
3620 }
3621 #endif
3622
3623 // if this is a load, check for anti-dependent stores
3624 // We use a conservative algorithm to identify potential interfering
3625 // instructions and for rescheduling the load. The users of the memory
3626 // input of this load are examined. Any use which is not a load and is
3627 // dominated by early is considered a potentially interfering store.
3628 // This can produce false positives.
3629 if (n->is_Load() && LCA != early) {
3630 Node_List worklist;
3631
3632 Node *mem = n->in(MemNode::Memory);
3633 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
3634 Node* s = mem->fast_out(i);
3635 worklist.push(s);
3636 }
3637 while(worklist.size() != 0 && LCA != early) {
3638 Node* s = worklist.pop();
3639 if (s->is_Load() || s->Opcode() == Op_SafePoint) {
3640 continue;
3641 } else if (s->is_MergeMem()) {
3642 for (DUIterator_Fast imax, i = s->fast_outs(imax); i < imax; i++) {
3643 Node* s1 = s->fast_out(i);
3644 worklist.push(s1);
3645 }
3646 } else {
3647 Node *sctrl = has_ctrl(s) ? get_ctrl(s) : s->in(0);
3648 assert(sctrl != NULL || s->outcnt() == 0, "must have control");
3649 if (sctrl != NULL && !sctrl->is_top() && is_dominator(early, sctrl)) {
3650 LCA = dom_lca_for_get_late_ctrl(LCA, sctrl, n);
3651 }
3652 }
3653 }
3654 }
3655
3656 assert(LCA == find_non_split_ctrl(LCA), "unexpected late control");
3657 return LCA;
3658 }
3659
3660 // true if CFG node d dominates CFG node n
3661 bool PhaseIdealLoop::is_dominator(Node *d, Node *n) {
3662 if (d == n)
3663 return true;
3664 assert(d->is_CFG() && n->is_CFG(), "must have CFG nodes");
3665 uint dd = dom_depth(d);
3666 while (dom_depth(n) >= dd) {
3667 if (n == d)
3668 return true;
3669 n = idom(n);
3670 }
3671 return false;
3672 }
3673
3674 //------------------------------dom_lca_for_get_late_ctrl_internal-------------
3675 // Pair-wise LCA with tags.
3676 // Tag each index with the node 'tag' currently being processed
3677 // before advancing up the dominator chain using idom().
3678 // Later calls that find a match to 'tag' know that this path has already
3679 // been considered in the current LCA (which is input 'n1' by convention).
3680 // Since get_late_ctrl() is only called once for each node, the tag array
3681 // does not need to be cleared between calls to get_late_ctrl().
3682 // Algorithm trades a larger constant factor for better asymptotic behavior
3683 //
3684 Node *PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal( Node *n1, Node *n2, Node *tag ) {
3685 uint d1 = dom_depth(n1);
3686 uint d2 = dom_depth(n2);
3687
3688 do {
3689 if (d1 > d2) {
3690 // current lca is deeper than n2
3691 _dom_lca_tags.map(n1->_idx, tag);
3692 n1 = idom(n1);
3693 d1 = dom_depth(n1);
3694 } else if (d1 < d2) {
3695 // n2 is deeper than current lca
3696 Node *memo = _dom_lca_tags[n2->_idx];
3697 if( memo == tag ) {
3698 return n1; // Return the current LCA
3699 }
3700 _dom_lca_tags.map(n2->_idx, tag);
3701 n2 = idom(n2);
3702 d2 = dom_depth(n2);
3703 } else {
3704 // Here d1 == d2. Due to edits of the dominator-tree, sections
3705 // of the tree might have the same depth. These sections have
3706 // to be searched more carefully.
3707
3708 // Scan up all the n1's with equal depth, looking for n2.
3709 _dom_lca_tags.map(n1->_idx, tag);
3710 Node *t1 = idom(n1);
3711 while (dom_depth(t1) == d1) {
3712 if (t1 == n2) return n2;
3713 _dom_lca_tags.map(t1->_idx, tag);
3714 t1 = idom(t1);
3715 }
3716 // Scan up all the n2's with equal depth, looking for n1.
3717 _dom_lca_tags.map(n2->_idx, tag);
3718 Node *t2 = idom(n2);
3719 while (dom_depth(t2) == d2) {
3720 if (t2 == n1) return n1;
3721 _dom_lca_tags.map(t2->_idx, tag);
3722 t2 = idom(t2);
3723 }
3724 // Move up to a new dominator-depth value as well as up the dom-tree.
3725 n1 = t1;
3726 n2 = t2;
3727 d1 = dom_depth(n1);
3728 d2 = dom_depth(n2);
3729 }
3730 } while (n1 != n2);
3731 return n1;
3732 }
3733
3734 //------------------------------init_dom_lca_tags------------------------------
3735 // Tag could be a node's integer index, 32bits instead of 64bits in some cases
3736 // Intended use does not involve any growth for the array, so it could
3737 // be of fixed size.
3738 void PhaseIdealLoop::init_dom_lca_tags() {
3739 uint limit = C->unique() + 1;
3740 _dom_lca_tags.map( limit, NULL );
3741 #ifdef ASSERT
3742 for( uint i = 0; i < limit; ++i ) {
3743 assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer");
3744 }
3745 #endif // ASSERT
3746 }
3747
3748 //------------------------------clear_dom_lca_tags------------------------------
3749 // Tag could be a node's integer index, 32bits instead of 64bits in some cases
3750 // Intended use does not involve any growth for the array, so it could
3751 // be of fixed size.
3752 void PhaseIdealLoop::clear_dom_lca_tags() {
3753 uint limit = C->unique() + 1;
3754 _dom_lca_tags.map( limit, NULL );
3755 _dom_lca_tags.clear();
3756 #ifdef ASSERT
3757 for( uint i = 0; i < limit; ++i ) {
3758 assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer");
3759 }
3760 #endif // ASSERT
3761 }
3762
3763 //------------------------------build_loop_late--------------------------------
3764 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
3765 // Second pass finds latest legal placement, and ideal loop placement.
3766 void PhaseIdealLoop::build_loop_late( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) {
3767 while (worklist.size() != 0) {
3768 Node *n = worklist.pop();
3769 // Only visit once
3770 if (visited.test_set(n->_idx)) continue;
3771 uint cnt = n->outcnt();
3772 uint i = 0;
3773 while (true) {
3774 assert( _nodes[n->_idx], "no dead nodes" );
3775 // Visit all children
3776 if (i < cnt) {
3777 Node* use = n->raw_out(i);
3778 ++i;
3779 // Check for dead uses. Aggressively prune such junk. It might be
3780 // dead in the global sense, but still have local uses so I cannot
3781 // easily call 'remove_dead_node'.
3782 if( _nodes[use->_idx] != NULL || use->is_top() ) { // Not dead?
3783 // Due to cycles, we might not hit the same fixed point in the verify
3784 // pass as we do in the regular pass. Instead, visit such phis as
3785 // simple uses of the loop head.
3786 if( use->in(0) && (use->is_CFG() || use->is_Phi()) ) {
3787 if( !visited.test(use->_idx) )
3788 worklist.push(use);
3789 } else if( !visited.test_set(use->_idx) ) {
3790 nstack.push(n, i); // Save parent and next use's index.
3791 n = use; // Process all children of current use.
3792 cnt = use->outcnt();
3793 i = 0;
3794 }
3795 } else {
3796 // Do not visit around the backedge of loops via data edges.
3797 // push dead code onto a worklist
3798 _deadlist.push(use);
3799 }
3800 } else {
3801 // All of n's children have been processed, complete post-processing.
3802 build_loop_late_post(n);
3803 if (nstack.is_empty()) {
3804 // Finished all nodes on stack.
3805 // Process next node on the worklist.
3806 break;
3807 }
3808 // Get saved parent node and next use's index. Visit the rest of uses.
3809 n = nstack.node();
3810 cnt = n->outcnt();
3811 i = nstack.index();
3812 nstack.pop();
3813 }
3814 }
3815 }
3816 }
3817
3818 // Verify that no data node is schedules in the outer loop of a strip
3819 // mined loop.
3820 void PhaseIdealLoop::verify_strip_mined_scheduling(Node *n, Node* least) {
3821 #ifdef ASSERT
3822 if (get_loop(least)->_nest == 0) {
3823 return;
3824 }
3825 IdealLoopTree* loop = get_loop(least);
3826 Node* head = loop->_head;
3827 if (head->Opcode() == Op_Loop && head->as_Loop()->is_strip_mined()) {
3828 if (n != head->as_Loop()->outer_bol() &&
3829 n != head->as_Loop()->outer_cmp() &&
3830 n != head->as_Loop()->outer_opaq()) {
3831 Node* sfpt = head->as_Loop()->outer_safepoint();
3832 ResourceMark rm;
3833 Unique_Node_List wq;
3834 wq.push(sfpt);
3835 for (uint i = 0; i < wq.size(); i++) {
3836 Node *m = wq.at(i);
3837 for (uint i = 1; i < m->req(); i++) {
3838 Node* nn = m->in(i);
3839 if (nn == n) {
3840 return;
3841 }
3842 if (nn != NULL && has_ctrl(nn) && get_loop(get_ctrl(nn)) == loop) {
3843 wq.push(nn);
3844 }
3845 }
3846 }
3847 ShouldNotReachHere();
3848 }
3849 }
3850 #endif
3851 }
3852
3853
3854 //------------------------------build_loop_late_post---------------------------
3855 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
3856 // Second pass finds latest legal placement, and ideal loop placement.
3857 void PhaseIdealLoop::build_loop_late_post( Node *n ) {
3858
3859 if (n->req() == 2 && (n->Opcode() == Op_ConvI2L || n->Opcode() == Op_CastII) && !C->major_progress() && !_verify_only) {
3860 _igvn._worklist.push(n); // Maybe we'll normalize it, if no more loops.
3861 }
3862
3863 #ifdef ASSERT
3864 if (_verify_only && !n->is_CFG()) {
3865 // Check def-use domination.
3866 compute_lca_of_uses(n, get_ctrl(n), true /* verify */);
3867 }
3868 #endif
3869
3870 // CFG and pinned nodes already handled
3871 if( n->in(0) ) {
3872 if( n->in(0)->is_top() ) return; // Dead?
3873
3874 // We'd like +VerifyLoopOptimizations to not believe that Mod's/Loads
3875 // _must_ be pinned (they have to observe their control edge of course).
3876 // Unlike Stores (which modify an unallocable resource, the memory
3877 // state), Mods/Loads can float around. So free them up.
3878 bool pinned = true;
3879 switch( n->Opcode() ) {
3880 case Op_DivI:
3881 case Op_DivF:
3882 case Op_DivD:
3883 case Op_ModI:
3884 case Op_ModF:
3885 case Op_ModD:
3886 case Op_LoadB: // Same with Loads; they can sink
3887 case Op_LoadUB: // during loop optimizations.
3888 case Op_LoadUS:
3889 case Op_LoadD:
3890 case Op_LoadF:
3891 case Op_LoadI:
3892 case Op_LoadKlass:
3893 case Op_LoadNKlass:
3894 case Op_LoadL:
3895 case Op_LoadS:
3896 case Op_LoadP:
3897 case Op_LoadN:
3898 case Op_LoadRange:
3899 case Op_LoadD_unaligned:
3900 case Op_LoadL_unaligned:
3901 case Op_StrComp: // Does a bunch of load-like effects
3902 case Op_StrEquals:
3903 case Op_StrIndexOf:
3904 case Op_StrIndexOfChar:
3905 case Op_AryEq:
3906 case Op_HasNegatives:
3907 pinned = false;
3908 }
3909 if( pinned ) {
3910 IdealLoopTree *chosen_loop = get_loop(n->is_CFG() ? n : get_ctrl(n));
3911 if( !chosen_loop->_child ) // Inner loop?
3912 chosen_loop->_body.push(n); // Collect inner loops
3913 return;
3914 }
3915 } else { // No slot zero
3916 if( n->is_CFG() ) { // CFG with no slot 0 is dead
3917 _nodes.map(n->_idx,0); // No block setting, it's globally dead
3918 return;
3919 }
3920 assert(!n->is_CFG() || n->outcnt() == 0, "");
3921 }
3922
3923 // Do I have a "safe range" I can select over?
3924 Node *early = get_ctrl(n);// Early location already computed
3925
3926 // Compute latest point this Node can go
3927 Node *LCA = get_late_ctrl( n, early );
3928 // LCA is NULL due to uses being dead
3929 if( LCA == NULL ) {
3930 #ifdef ASSERT
3931 for (DUIterator i1 = n->outs(); n->has_out(i1); i1++) {
3932 assert( _nodes[n->out(i1)->_idx] == NULL, "all uses must also be dead");
3933 }
3934 #endif
3935 _nodes.map(n->_idx, 0); // This node is useless
3936 _deadlist.push(n);
3937 return;
3938 }
3939 assert(LCA != NULL && !LCA->is_top(), "no dead nodes");
3940
3941 Node *legal = LCA; // Walk 'legal' up the IDOM chain
3942 Node *least = legal; // Best legal position so far
3943 while( early != legal ) { // While not at earliest legal
3944 #ifdef ASSERT
3945 if (legal->is_Start() && !early->is_Root()) {
3946 // Bad graph. Print idom path and fail.
3947 dump_bad_graph("Bad graph detected in build_loop_late", n, early, LCA);
3948 assert(false, "Bad graph detected in build_loop_late");
3949 }
3950 #endif
3951 // Find least loop nesting depth
3952 legal = idom(legal); // Bump up the IDOM tree
3953 // Check for lower nesting depth
3954 if( get_loop(legal)->_nest < get_loop(least)->_nest )
3955 least = legal;
3956 }
3957 assert(early == legal || legal != C->root(), "bad dominance of inputs");
3958
3959 // Try not to place code on a loop entry projection
3960 // which can inhibit range check elimination.
3961 if (least != early) {
3962 Node* ctrl_out = least->unique_ctrl_out();
3963 if (ctrl_out && ctrl_out->is_Loop() &&
3964 least == ctrl_out->in(LoopNode::EntryControl) &&
3965 (ctrl_out->is_CountedLoop() || ctrl_out->as_Loop()->is_strip_mined())) {
3966 Node* least_dom = idom(least);
3967 if (get_loop(least_dom)->is_member(get_loop(least))) {
3968 least = least_dom;
3969 }
3970 }
3971 }
3972
3973 #ifdef ASSERT
3974 // If verifying, verify that 'verify_me' has a legal location
3975 // and choose it as our location.
3976 if( _verify_me ) {
3977 Node *v_ctrl = _verify_me->get_ctrl_no_update(n);
3978 Node *legal = LCA;
3979 while( early != legal ) { // While not at earliest legal
3980 if( legal == v_ctrl ) break; // Check for prior good location
3981 legal = idom(legal) ;// Bump up the IDOM tree
3982 }
3983 // Check for prior good location
3984 if( legal == v_ctrl ) least = legal; // Keep prior if found
3985 }
3986 #endif
3987
3988 // Assign discovered "here or above" point
3989 least = find_non_split_ctrl(least);
3990 verify_strip_mined_scheduling(n, least);
3991 set_ctrl(n, least);
3992
3993 // Collect inner loop bodies
3994 IdealLoopTree *chosen_loop = get_loop(least);
3995 if( !chosen_loop->_child ) // Inner loop?
3996 chosen_loop->_body.push(n);// Collect inner loops
3997 }
3998
3999 #ifdef ASSERT
4000 void PhaseIdealLoop::dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA) {
4001 tty->print_cr("%s", msg);
4002 tty->print("n: "); n->dump();
4003 tty->print("early(n): "); early->dump();
4004 if (n->in(0) != NULL && !n->in(0)->is_top() &&
4005 n->in(0) != early && !n->in(0)->is_Root()) {
4006 tty->print("n->in(0): "); n->in(0)->dump();
4007 }
4008 for (uint i = 1; i < n->req(); i++) {
4009 Node* in1 = n->in(i);
4010 if (in1 != NULL && in1 != n && !in1->is_top()) {
4011 tty->print("n->in(%d): ", i); in1->dump();
4012 Node* in1_early = get_ctrl(in1);
4013 tty->print("early(n->in(%d)): ", i); in1_early->dump();
4014 if (in1->in(0) != NULL && !in1->in(0)->is_top() &&
4015 in1->in(0) != in1_early && !in1->in(0)->is_Root()) {
4016 tty->print("n->in(%d)->in(0): ", i); in1->in(0)->dump();
4017 }
4018 for (uint j = 1; j < in1->req(); j++) {
4019 Node* in2 = in1->in(j);
4020 if (in2 != NULL && in2 != n && in2 != in1 && !in2->is_top()) {
4021 tty->print("n->in(%d)->in(%d): ", i, j); in2->dump();
4022 Node* in2_early = get_ctrl(in2);
4023 tty->print("early(n->in(%d)->in(%d)): ", i, j); in2_early->dump();
4024 if (in2->in(0) != NULL && !in2->in(0)->is_top() &&
4025 in2->in(0) != in2_early && !in2->in(0)->is_Root()) {
4026 tty->print("n->in(%d)->in(%d)->in(0): ", i, j); in2->in(0)->dump();
4027 }
4028 }
4029 }
4030 }
4031 }
4032 tty->cr();
4033 tty->print("LCA(n): "); LCA->dump();
4034 for (uint i = 0; i < n->outcnt(); i++) {
4035 Node* u1 = n->raw_out(i);
4036 if (u1 == n)
4037 continue;
4038 tty->print("n->out(%d): ", i); u1->dump();
4039 if (u1->is_CFG()) {
4040 for (uint j = 0; j < u1->outcnt(); j++) {
4041 Node* u2 = u1->raw_out(j);
4042 if (u2 != u1 && u2 != n && u2->is_CFG()) {
4043 tty->print("n->out(%d)->out(%d): ", i, j); u2->dump();
4044 }
4045 }
4046 } else {
4047 Node* u1_later = get_ctrl(u1);
4048 tty->print("later(n->out(%d)): ", i); u1_later->dump();
4049 if (u1->in(0) != NULL && !u1->in(0)->is_top() &&
4050 u1->in(0) != u1_later && !u1->in(0)->is_Root()) {
4051 tty->print("n->out(%d)->in(0): ", i); u1->in(0)->dump();
4052 }
4053 for (uint j = 0; j < u1->outcnt(); j++) {
4054 Node* u2 = u1->raw_out(j);
4055 if (u2 == n || u2 == u1)
4056 continue;
4057 tty->print("n->out(%d)->out(%d): ", i, j); u2->dump();
4058 if (!u2->is_CFG()) {
4059 Node* u2_later = get_ctrl(u2);
4060 tty->print("later(n->out(%d)->out(%d)): ", i, j); u2_later->dump();
4061 if (u2->in(0) != NULL && !u2->in(0)->is_top() &&
4062 u2->in(0) != u2_later && !u2->in(0)->is_Root()) {
4063 tty->print("n->out(%d)->in(0): ", i); u2->in(0)->dump();
4064 }
4065 }
4066 }
4067 }
4068 }
4069 tty->cr();
4070 int ct = 0;
4071 Node *dbg_legal = LCA;
4072 while(!dbg_legal->is_Start() && ct < 100) {
4073 tty->print("idom[%d] ",ct); dbg_legal->dump();
4074 ct++;
4075 dbg_legal = idom(dbg_legal);
4076 }
4077 tty->cr();
4078 }
4079 #endif
4080
4081 #ifndef PRODUCT
4082 //------------------------------dump-------------------------------------------
4083 void PhaseIdealLoop::dump( ) const {
4084 ResourceMark rm;
4085 Arena* arena = Thread::current()->resource_area();
4086 Node_Stack stack(arena, C->live_nodes() >> 2);
4087 Node_List rpo_list;
4088 VectorSet visited(arena);
4089 visited.set(C->top()->_idx);
4090 rpo( C->root(), stack, visited, rpo_list );
4091 // Dump root loop indexed by last element in PO order
4092 dump( _ltree_root, rpo_list.size(), rpo_list );
4093 }
4094
4095 void PhaseIdealLoop::dump( IdealLoopTree *loop, uint idx, Node_List &rpo_list ) const {
4096 loop->dump_head();
4097
4098 // Now scan for CFG nodes in the same loop
4099 for( uint j=idx; j > 0; j-- ) {
4100 Node *n = rpo_list[j-1];
4101 if( !_nodes[n->_idx] ) // Skip dead nodes
4102 continue;
4103 if( get_loop(n) != loop ) { // Wrong loop nest
4104 if( get_loop(n)->_head == n && // Found nested loop?
4105 get_loop(n)->_parent == loop )
4106 dump(get_loop(n),rpo_list.size(),rpo_list); // Print it nested-ly
4107 continue;
4108 }
4109
4110 // Dump controlling node
4111 for( uint x = 0; x < loop->_nest; x++ )
4112 tty->print(" ");
4113 tty->print("C");
4114 if( n == C->root() ) {
4115 n->dump();
4116 } else {
4117 Node* cached_idom = idom_no_update(n);
4118 Node *computed_idom = n->in(0);
4119 if( n->is_Region() ) {
4120 computed_idom = compute_idom(n);
4121 // computed_idom() will return n->in(0) when idom(n) is an IfNode (or
4122 // any MultiBranch ctrl node), so apply a similar transform to
4123 // the cached idom returned from idom_no_update.
4124 cached_idom = find_non_split_ctrl(cached_idom);
4125 }
4126 tty->print(" ID:%d",computed_idom->_idx);
4127 n->dump();
4128 if( cached_idom != computed_idom ) {
4129 tty->print_cr("*** BROKEN IDOM! Computed as: %d, cached as: %d",
4130 computed_idom->_idx, cached_idom->_idx);
4131 }
4132 }
4133 // Dump nodes it controls
4134 for( uint k = 0; k < _nodes.Size(); k++ ) {
4135 // (k < C->unique() && get_ctrl(find(k)) == n)
4136 if (k < C->unique() && _nodes[k] == (Node*)((intptr_t)n + 1)) {
4137 Node *m = C->root()->find(k);
4138 if( m && m->outcnt() > 0 ) {
4139 if (!(has_ctrl(m) && get_ctrl_no_update(m) == n)) {
4140 tty->print_cr("*** BROKEN CTRL ACCESSOR! _nodes[k] is %p, ctrl is %p",
4141 _nodes[k], has_ctrl(m) ? get_ctrl_no_update(m) : NULL);
4142 }
4143 for( uint j = 0; j < loop->_nest; j++ )
4144 tty->print(" ");
4145 tty->print(" ");
4146 m->dump();
4147 }
4148 }
4149 }
4150 }
4151 }
4152
4153 // Collect a R-P-O for the whole CFG.
4154 // Result list is in post-order (scan backwards for RPO)
4155 void PhaseIdealLoop::rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const {
4156 stk.push(start, 0);
4157 visited.set(start->_idx);
4158
4159 while (stk.is_nonempty()) {
4160 Node* m = stk.node();
4161 uint idx = stk.index();
4162 if (idx < m->outcnt()) {
4163 stk.set_index(idx + 1);
4164 Node* n = m->raw_out(idx);
4165 if (n->is_CFG() && !visited.test_set(n->_idx)) {
4166 stk.push(n, 0);
4167 }
4168 } else {
4169 rpo_list.push(m);
4170 stk.pop();
4171 }
4172 }
4173 }
4174 #endif
4175
4176
4177 //=============================================================================
4178 //------------------------------LoopTreeIterator-----------------------------------
4179
4180 // Advance to next loop tree using a preorder, left-to-right traversal.
4181 void LoopTreeIterator::next() {
4182 assert(!done(), "must not be done.");
4183 if (_curnt->_child != NULL) {
4184 _curnt = _curnt->_child;
4185 } else if (_curnt->_next != NULL) {
4186 _curnt = _curnt->_next;
4187 } else {
4188 while (_curnt != _root && _curnt->_next == NULL) {
4189 _curnt = _curnt->_parent;
4190 }
4191 if (_curnt == _root) {
4192 _curnt = NULL;
4193 assert(done(), "must be done.");
4194 } else {
4195 assert(_curnt->_next != NULL, "must be more to do");
4196 _curnt = _curnt->_next;
4197 }
4198 }
4199 }