1 /*
2 * Copyright (c) 1998, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "ci/ciMethodData.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "gc/shared/barrierSet.hpp"
29 #include "gc/shared/c2/barrierSetC2.hpp"
30 #include "libadt/vectset.hpp"
31 #include "memory/allocation.inline.hpp"
32 #include "memory/resourceArea.hpp"
33 #include "opto/addnode.hpp"
34 #include "opto/callnode.hpp"
35 #include "opto/connode.hpp"
36 #include "opto/convertnode.hpp"
37 #include "opto/divnode.hpp"
38 #include "opto/idealGraphPrinter.hpp"
39 #include "opto/loopnode.hpp"
40 #include "opto/mulnode.hpp"
41 #include "opto/rootnode.hpp"
42 #include "opto/superword.hpp"
43
44 //=============================================================================
45 //------------------------------is_loop_iv-------------------------------------
46 // Determine if a node is Counted loop induction variable.
47 // The method is declared in node.hpp.
48 const Node* Node::is_loop_iv() const {
49 if (this->is_Phi() && !this->as_Phi()->is_copy() &&
50 this->as_Phi()->region()->is_CountedLoop() &&
51 this->as_Phi()->region()->as_CountedLoop()->phi() == this) {
52 return this;
53 } else {
54 return NULL;
55 }
56 }
57
58 //=============================================================================
59 //------------------------------dump_spec--------------------------------------
60 // Dump special per-node info
61 #ifndef PRODUCT
62 void LoopNode::dump_spec(outputStream *st) const {
63 if (is_inner_loop()) st->print( "inner " );
64 if (is_partial_peel_loop()) st->print( "partial_peel " );
65 if (partial_peel_has_failed()) st->print( "partial_peel_failed " );
66 }
67 #endif
68
69 //------------------------------is_valid_counted_loop-------------------------
70 bool LoopNode::is_valid_counted_loop() const {
71 if (is_CountedLoop()) {
72 CountedLoopNode* l = as_CountedLoop();
73 CountedLoopEndNode* le = l->loopexit_or_null();
74 if (le != NULL &&
75 le->proj_out_or_null(1 /* true */) == l->in(LoopNode::LoopBackControl)) {
76 Node* phi = l->phi();
77 Node* exit = le->proj_out_or_null(0 /* false */);
78 if (exit != NULL && exit->Opcode() == Op_IfFalse &&
79 phi != NULL && phi->is_Phi() &&
80 phi->in(LoopNode::LoopBackControl) == l->incr() &&
81 le->loopnode() == l && le->stride_is_con()) {
82 return true;
83 }
84 }
85 }
86 return false;
87 }
88
89 //------------------------------get_early_ctrl---------------------------------
90 // Compute earliest legal control
91 Node *PhaseIdealLoop::get_early_ctrl( Node *n ) {
92 assert( !n->is_Phi() && !n->is_CFG(), "this code only handles data nodes" );
93 uint i;
94 Node *early;
95 if (n->in(0) && !n->is_expensive()) {
96 early = n->in(0);
97 if (!early->is_CFG()) // Might be a non-CFG multi-def
98 early = get_ctrl(early); // So treat input as a straight data input
99 i = 1;
100 } else {
101 early = get_ctrl(n->in(1));
102 i = 2;
103 }
104 uint e_d = dom_depth(early);
105 assert( early, "" );
106 for (; i < n->req(); i++) {
107 Node *cin = get_ctrl(n->in(i));
108 assert( cin, "" );
109 // Keep deepest dominator depth
110 uint c_d = dom_depth(cin);
111 if (c_d > e_d) { // Deeper guy?
112 early = cin; // Keep deepest found so far
113 e_d = c_d;
114 } else if (c_d == e_d && // Same depth?
115 early != cin) { // If not equal, must use slower algorithm
116 // If same depth but not equal, one _must_ dominate the other
117 // and we want the deeper (i.e., dominated) guy.
118 Node *n1 = early;
119 Node *n2 = cin;
120 while (1) {
121 n1 = idom(n1); // Walk up until break cycle
122 n2 = idom(n2);
123 if (n1 == cin || // Walked early up to cin
124 dom_depth(n2) < c_d)
125 break; // early is deeper; keep him
126 if (n2 == early || // Walked cin up to early
127 dom_depth(n1) < c_d) {
128 early = cin; // cin is deeper; keep him
129 break;
130 }
131 }
132 e_d = dom_depth(early); // Reset depth register cache
133 }
134 }
135
136 // Return earliest legal location
137 assert(early == find_non_split_ctrl(early), "unexpected early control");
138
139 if (n->is_expensive() && !_verify_only && !_verify_me) {
140 assert(n->in(0), "should have control input");
141 early = get_early_ctrl_for_expensive(n, early);
142 }
143
144 return early;
145 }
146
147 //------------------------------get_early_ctrl_for_expensive---------------------------------
148 // Move node up the dominator tree as high as legal while still beneficial
149 Node *PhaseIdealLoop::get_early_ctrl_for_expensive(Node *n, Node* earliest) {
150 assert(n->in(0) && n->is_expensive(), "expensive node with control input here");
151 assert(OptimizeExpensiveOps, "optimization off?");
152
153 Node* ctl = n->in(0);
154 assert(ctl->is_CFG(), "expensive input 0 must be cfg");
155 uint min_dom_depth = dom_depth(earliest);
156 #ifdef ASSERT
157 if (!is_dominator(ctl, earliest) && !is_dominator(earliest, ctl)) {
158 dump_bad_graph("Bad graph detected in get_early_ctrl_for_expensive", n, earliest, ctl);
159 assert(false, "Bad graph detected in get_early_ctrl_for_expensive");
160 }
161 #endif
162 if (dom_depth(ctl) < min_dom_depth) {
163 return earliest;
164 }
165
166 while (1) {
167 Node *next = ctl;
168 // Moving the node out of a loop on the projection of a If
169 // confuses loop predication. So once we hit a Loop in a If branch
170 // that doesn't branch to an UNC, we stop. The code that process
171 // expensive nodes will notice the loop and skip over it to try to
172 // move the node further up.
173 if (ctl->is_CountedLoop() && ctl->in(1) != NULL && ctl->in(1)->in(0) != NULL && ctl->in(1)->in(0)->is_If()) {
174 if (!ctl->in(1)->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) {
175 break;
176 }
177 next = idom(ctl->in(1)->in(0));
178 } else if (ctl->is_Proj()) {
179 // We only move it up along a projection if the projection is
180 // the single control projection for its parent: same code path,
181 // if it's a If with UNC or fallthrough of a call.
182 Node* parent_ctl = ctl->in(0);
183 if (parent_ctl == NULL) {
184 break;
185 } else if (parent_ctl->is_CountedLoopEnd() && parent_ctl->as_CountedLoopEnd()->loopnode() != NULL) {
186 next = parent_ctl->as_CountedLoopEnd()->loopnode()->init_control();
187 } else if (parent_ctl->is_If()) {
188 if (!ctl->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) {
189 break;
190 }
191 assert(idom(ctl) == parent_ctl, "strange");
192 next = idom(parent_ctl);
193 } else if (ctl->is_CatchProj()) {
194 if (ctl->as_Proj()->_con != CatchProjNode::fall_through_index) {
195 break;
196 }
197 assert(parent_ctl->in(0)->in(0)->is_Call(), "strange graph");
198 next = parent_ctl->in(0)->in(0)->in(0);
199 } else {
200 // Check if parent control has a single projection (this
201 // control is the only possible successor of the parent
202 // control). If so, we can try to move the node above the
203 // parent control.
204 int nb_ctl_proj = 0;
205 for (DUIterator_Fast imax, i = parent_ctl->fast_outs(imax); i < imax; i++) {
206 Node *p = parent_ctl->fast_out(i);
207 if (p->is_Proj() && p->is_CFG()) {
208 nb_ctl_proj++;
209 if (nb_ctl_proj > 1) {
210 break;
211 }
212 }
213 }
214
215 if (nb_ctl_proj > 1) {
216 break;
217 }
218 assert(parent_ctl->is_Start() || parent_ctl->is_MemBar() || parent_ctl->is_Call() ||
219 BarrierSet::barrier_set()->barrier_set_c2()->is_gc_barrier_node(parent_ctl), "unexpected node");
220 assert(idom(ctl) == parent_ctl, "strange");
221 next = idom(parent_ctl);
222 }
223 } else {
224 next = idom(ctl);
225 }
226 if (next->is_Root() || next->is_Start() || dom_depth(next) < min_dom_depth) {
227 break;
228 }
229 ctl = next;
230 }
231
232 if (ctl != n->in(0)) {
233 _igvn.replace_input_of(n, 0, ctl);
234 _igvn.hash_insert(n);
235 }
236
237 return ctl;
238 }
239
240
241 //------------------------------set_early_ctrl---------------------------------
242 // Set earliest legal control
243 void PhaseIdealLoop::set_early_ctrl( Node *n ) {
244 Node *early = get_early_ctrl(n);
245
246 // Record earliest legal location
247 set_ctrl(n, early);
248 }
249
250 //------------------------------set_subtree_ctrl-------------------------------
251 // set missing _ctrl entries on new nodes
252 void PhaseIdealLoop::set_subtree_ctrl( Node *n ) {
253 // Already set? Get out.
254 if( _nodes[n->_idx] ) return;
255 // Recursively set _nodes array to indicate where the Node goes
256 uint i;
257 for( i = 0; i < n->req(); ++i ) {
258 Node *m = n->in(i);
259 if( m && m != C->root() )
260 set_subtree_ctrl( m );
261 }
262
263 // Fixup self
264 set_early_ctrl( n );
265 }
266
267 // Create a skeleton strip mined outer loop: a Loop head before the
268 // inner strip mined loop, a safepoint and an exit condition guarded
269 // by an opaque node after the inner strip mined loop with a backedge
270 // to the loop head. The inner strip mined loop is left as it is. Only
271 // once loop optimizations are over, do we adjust the inner loop exit
272 // condition to limit its number of iterations, set the outer loop
273 // exit condition and add Phis to the outer loop head. Some loop
274 // optimizations that operate on the inner strip mined loop need to be
275 // aware of the outer strip mined loop: loop unswitching needs to
276 // clone the outer loop as well as the inner, unrolling needs to only
277 // clone the inner loop etc. No optimizations need to change the outer
278 // strip mined loop as it is only a skeleton.
279 IdealLoopTree* PhaseIdealLoop::create_outer_strip_mined_loop(BoolNode *test, Node *cmp, Node *init_control,
280 IdealLoopTree* loop, float cl_prob, float le_fcnt,
281 Node*& entry_control, Node*& iffalse) {
282 Node* outer_test = _igvn.intcon(0);
283 set_ctrl(outer_test, C->root());
284 Node *orig = iffalse;
285 iffalse = iffalse->clone();
286 _igvn.register_new_node_with_optimizer(iffalse);
287 set_idom(iffalse, idom(orig), dom_depth(orig));
288
289 IfNode *outer_le = new OuterStripMinedLoopEndNode(iffalse, outer_test, cl_prob, le_fcnt);
290 Node *outer_ift = new IfTrueNode (outer_le);
291 Node* outer_iff = orig;
292 _igvn.replace_input_of(outer_iff, 0, outer_le);
293
294 LoopNode *outer_l = new OuterStripMinedLoopNode(C, init_control, outer_ift);
295 entry_control = outer_l;
296
297 IdealLoopTree* outer_ilt = new IdealLoopTree(this, outer_l, outer_ift);
298 IdealLoopTree* parent = loop->_parent;
299 IdealLoopTree* sibling = parent->_child;
300 if (sibling == loop) {
301 parent->_child = outer_ilt;
302 } else {
303 while (sibling->_next != loop) {
304 sibling = sibling->_next;
305 }
306 sibling->_next = outer_ilt;
307 }
308 outer_ilt->_next = loop->_next;
309 outer_ilt->_parent = parent;
310 outer_ilt->_child = loop;
311 outer_ilt->_nest = loop->_nest;
312 loop->_parent = outer_ilt;
313 loop->_next = NULL;
314 loop->_nest++;
315
316 set_loop(iffalse, outer_ilt);
317 register_control(outer_le, outer_ilt, iffalse);
318 register_control(outer_ift, outer_ilt, outer_le);
319 set_idom(outer_iff, outer_le, dom_depth(outer_le));
320 _igvn.register_new_node_with_optimizer(outer_l);
321 set_loop(outer_l, outer_ilt);
322 set_idom(outer_l, init_control, dom_depth(init_control)+1);
323
324 return outer_ilt;
325 }
326
327 //------------------------------is_counted_loop--------------------------------
328 bool PhaseIdealLoop::is_counted_loop(Node* x, IdealLoopTree*& loop) {
329 PhaseGVN *gvn = &_igvn;
330
331 // Counted loop head must be a good RegionNode with only 3 not NULL
332 // control input edges: Self, Entry, LoopBack.
333 if (x->in(LoopNode::Self) == NULL || x->req() != 3 || loop->_irreducible) {
334 return false;
335 }
336 Node *init_control = x->in(LoopNode::EntryControl);
337 Node *back_control = x->in(LoopNode::LoopBackControl);
338 if (init_control == NULL || back_control == NULL) // Partially dead
339 return false;
340 // Must also check for TOP when looking for a dead loop
341 if (init_control->is_top() || back_control->is_top())
342 return false;
343
344 // Allow funny placement of Safepoint
345 if (back_control->Opcode() == Op_SafePoint) {
346 if (LoopStripMiningIter != 0) {
347 // Leaving the safepoint on the backedge and creating a
348 // CountedLoop will confuse optimizations. We can't move the
349 // safepoint around because its jvm state wouldn't match a new
350 // location. Give up on that loop.
351 return false;
352 }
353 back_control = back_control->in(TypeFunc::Control);
354 }
355
356 // Controlling test for loop
357 Node *iftrue = back_control;
358 uint iftrue_op = iftrue->Opcode();
359 if (iftrue_op != Op_IfTrue &&
360 iftrue_op != Op_IfFalse)
361 // I have a weird back-control. Probably the loop-exit test is in
362 // the middle of the loop and I am looking at some trailing control-flow
363 // merge point. To fix this I would have to partially peel the loop.
364 return false; // Obscure back-control
365
366 // Get boolean guarding loop-back test
367 Node *iff = iftrue->in(0);
368 if (get_loop(iff) != loop || !iff->in(1)->is_Bool())
369 return false;
370 BoolNode *test = iff->in(1)->as_Bool();
371 BoolTest::mask bt = test->_test._test;
372 float cl_prob = iff->as_If()->_prob;
373 if (iftrue_op == Op_IfFalse) {
374 bt = BoolTest(bt).negate();
375 cl_prob = 1.0 - cl_prob;
376 }
377 // Get backedge compare
378 Node *cmp = test->in(1);
379 int cmp_op = cmp->Opcode();
380 if (cmp_op != Op_CmpI)
381 return false; // Avoid pointer & float compares
382
383 // Find the trip-counter increment & limit. Limit must be loop invariant.
384 Node *incr = cmp->in(1);
385 Node *limit = cmp->in(2);
386
387 // ---------
388 // need 'loop()' test to tell if limit is loop invariant
389 // ---------
390
391 if (!is_member(loop, get_ctrl(incr))) { // Swapped trip counter and limit?
392 Node *tmp = incr; // Then reverse order into the CmpI
393 incr = limit;
394 limit = tmp;
395 bt = BoolTest(bt).commute(); // And commute the exit test
396 }
397 if (is_member(loop, get_ctrl(limit))) // Limit must be loop-invariant
398 return false;
399 if (!is_member(loop, get_ctrl(incr))) // Trip counter must be loop-variant
400 return false;
401
402 Node* phi_incr = NULL;
403 // Trip-counter increment must be commutative & associative.
404 if (incr->Opcode() == Op_CastII) {
405 incr = incr->in(1);
406 }
407 if (incr->is_Phi()) {
408 if (incr->as_Phi()->region() != x || incr->req() != 3)
409 return false; // Not simple trip counter expression
410 phi_incr = incr;
411 incr = phi_incr->in(LoopNode::LoopBackControl); // Assume incr is on backedge of Phi
412 if (!is_member(loop, get_ctrl(incr))) // Trip counter must be loop-variant
413 return false;
414 }
415
416 Node* trunc1 = NULL;
417 Node* trunc2 = NULL;
418 const TypeInt* iv_trunc_t = NULL;
419 Node* orig_incr = incr;
420 if (!(incr = CountedLoopNode::match_incr_with_optional_truncation(incr, &trunc1, &trunc2, &iv_trunc_t))) {
421 return false; // Funny increment opcode
422 }
423 assert(incr->Opcode() == Op_AddI, "wrong increment code");
424
425 const TypeInt* limit_t = gvn->type(limit)->is_int();
426 if (trunc1 != NULL) {
427 // When there is a truncation, we must be sure that after the truncation
428 // the trip counter will end up higher than the limit, otherwise we are looking
429 // at an endless loop. Can happen with range checks.
430
431 // Example:
432 // int i = 0;
433 // while (true)
434 // sum + = array[i];
435 // i++;
436 // i = i && 0x7fff;
437 // }
438 //
439 // If the array is shorter than 0x8000 this exits through a AIOOB
440 // - Counted loop transformation is ok
441 // If the array is longer then this is an endless loop
442 // - No transformation can be done.
443
444 const TypeInt* incr_t = gvn->type(orig_incr)->is_int();
445 if (limit_t->_hi > incr_t->_hi) {
446 // if the limit can have a higher value than the increment (before the phi)
447 return false;
448 }
449 }
450
451 // Get merge point
452 Node *xphi = incr->in(1);
453 Node *stride = incr->in(2);
454 if (!stride->is_Con()) { // Oops, swap these
455 if (!xphi->is_Con()) // Is the other guy a constant?
456 return false; // Nope, unknown stride, bail out
457 Node *tmp = xphi; // 'incr' is commutative, so ok to swap
458 xphi = stride;
459 stride = tmp;
460 }
461 if (xphi->Opcode() == Op_CastII) {
462 xphi = xphi->in(1);
463 }
464 // Stride must be constant
465 int stride_con = stride->get_int();
466 if (stride_con == 0)
467 return false; // missed some peephole opt
468
469 if (!xphi->is_Phi())
470 return false; // Too much math on the trip counter
471 if (phi_incr != NULL && phi_incr != xphi)
472 return false;
473 PhiNode *phi = xphi->as_Phi();
474
475 // Phi must be of loop header; backedge must wrap to increment
476 if (phi->region() != x)
477 return false;
478 if ((trunc1 == NULL && phi->in(LoopNode::LoopBackControl) != incr) ||
479 (trunc1 != NULL && phi->in(LoopNode::LoopBackControl) != trunc1)) {
480 return false;
481 }
482 Node *init_trip = phi->in(LoopNode::EntryControl);
483
484 // If iv trunc type is smaller than int, check for possible wrap.
485 if (!TypeInt::INT->higher_equal(iv_trunc_t)) {
486 assert(trunc1 != NULL, "must have found some truncation");
487
488 // Get a better type for the phi (filtered thru if's)
489 const TypeInt* phi_ft = filtered_type(phi);
490
491 // Can iv take on a value that will wrap?
492 //
493 // Ensure iv's limit is not within "stride" of the wrap value.
494 //
495 // Example for "short" type
496 // Truncation ensures value is in the range -32768..32767 (iv_trunc_t)
497 // If the stride is +10, then the last value of the induction
498 // variable before the increment (phi_ft->_hi) must be
499 // <= 32767 - 10 and (phi_ft->_lo) must be >= -32768 to
500 // ensure no truncation occurs after the increment.
501
502 if (stride_con > 0) {
503 if (iv_trunc_t->_hi - phi_ft->_hi < stride_con ||
504 iv_trunc_t->_lo > phi_ft->_lo) {
505 return false; // truncation may occur
506 }
507 } else if (stride_con < 0) {
508 if (iv_trunc_t->_lo - phi_ft->_lo > stride_con ||
509 iv_trunc_t->_hi < phi_ft->_hi) {
510 return false; // truncation may occur
511 }
512 }
513 // No possibility of wrap so truncation can be discarded
514 // Promote iv type to Int
515 } else {
516 assert(trunc1 == NULL && trunc2 == NULL, "no truncation for int");
517 }
518
519 // If the condition is inverted and we will be rolling
520 // through MININT to MAXINT, then bail out.
521 if (bt == BoolTest::eq || // Bail out, but this loop trips at most twice!
522 // Odd stride
523 (bt == BoolTest::ne && stride_con != 1 && stride_con != -1) ||
524 // Count down loop rolls through MAXINT
525 ((bt == BoolTest::le || bt == BoolTest::lt) && stride_con < 0) ||
526 // Count up loop rolls through MININT
527 ((bt == BoolTest::ge || bt == BoolTest::gt) && stride_con > 0)) {
528 return false; // Bail out
529 }
530
531 const TypeInt* init_t = gvn->type(init_trip)->is_int();
532
533 if (stride_con > 0) {
534 jlong init_p = (jlong)init_t->_lo + stride_con;
535 if (init_p > (jlong)max_jint || init_p > (jlong)limit_t->_hi)
536 return false; // cyclic loop or this loop trips only once
537 } else {
538 jlong init_p = (jlong)init_t->_hi + stride_con;
539 if (init_p < (jlong)min_jint || init_p < (jlong)limit_t->_lo)
540 return false; // cyclic loop or this loop trips only once
541 }
542
543 if (phi_incr != NULL) {
544 // check if there is a possiblity of IV overflowing after the first increment
545 if (stride_con > 0) {
546 if (init_t->_hi > max_jint - stride_con) {
547 return false;
548 }
549 } else {
550 if (init_t->_lo < min_jint - stride_con) {
551 return false;
552 }
553 }
554 }
555
556 // =================================================
557 // ---- SUCCESS! Found A Trip-Counted Loop! -----
558 //
559 assert(x->Opcode() == Op_Loop, "regular loops only");
560 C->print_method(PHASE_BEFORE_CLOOPS, 3);
561
562 Node *hook = new Node(6);
563
564 // ===================================================
565 // Generate loop limit check to avoid integer overflow
566 // in cases like next (cyclic loops):
567 //
568 // for (i=0; i <= max_jint; i++) {}
569 // for (i=0; i < max_jint; i+=2) {}
570 //
571 //
572 // Limit check predicate depends on the loop test:
573 //
574 // for(;i != limit; i++) --> limit <= (max_jint)
575 // for(;i < limit; i+=stride) --> limit <= (max_jint - stride + 1)
576 // for(;i <= limit; i+=stride) --> limit <= (max_jint - stride )
577 //
578
579 // Check if limit is excluded to do more precise int overflow check.
580 bool incl_limit = (bt == BoolTest::le || bt == BoolTest::ge);
581 int stride_m = stride_con - (incl_limit ? 0 : (stride_con > 0 ? 1 : -1));
582
583 // If compare points directly to the phi we need to adjust
584 // the compare so that it points to the incr. Limit have
585 // to be adjusted to keep trip count the same and the
586 // adjusted limit should be checked for int overflow.
587 if (phi_incr != NULL) {
588 stride_m += stride_con;
589 }
590
591 if (limit->is_Con()) {
592 int limit_con = limit->get_int();
593 if ((stride_con > 0 && limit_con > (max_jint - stride_m)) ||
594 (stride_con < 0 && limit_con < (min_jint - stride_m))) {
595 // Bailout: it could be integer overflow.
596 return false;
597 }
598 } else if ((stride_con > 0 && limit_t->_hi <= (max_jint - stride_m)) ||
599 (stride_con < 0 && limit_t->_lo >= (min_jint - stride_m))) {
600 // Limit's type may satisfy the condition, for example,
601 // when it is an array length.
602 } else {
603 // Generate loop's limit check.
604 // Loop limit check predicate should be near the loop.
605 ProjNode *limit_check_proj = find_predicate_insertion_point(init_control, Deoptimization::Reason_loop_limit_check);
606 if (!limit_check_proj) {
607 // The limit check predicate is not generated if this method trapped here before.
608 #ifdef ASSERT
609 if (TraceLoopLimitCheck) {
610 tty->print("missing loop limit check:");
611 loop->dump_head();
612 x->dump(1);
613 }
614 #endif
615 return false;
616 }
617
618 IfNode* check_iff = limit_check_proj->in(0)->as_If();
619 Node* cmp_limit;
620 Node* bol;
621
622 if (stride_con > 0) {
623 cmp_limit = new CmpINode(limit, _igvn.intcon(max_jint - stride_m));
624 bol = new BoolNode(cmp_limit, BoolTest::le);
625 } else {
626 cmp_limit = new CmpINode(limit, _igvn.intcon(min_jint - stride_m));
627 bol = new BoolNode(cmp_limit, BoolTest::ge);
628 }
629 cmp_limit = _igvn.register_new_node_with_optimizer(cmp_limit);
630 bol = _igvn.register_new_node_with_optimizer(bol);
631 set_subtree_ctrl(bol);
632
633 // Replace condition in original predicate but preserve Opaque node
634 // so that previous predicates could be found.
635 assert(check_iff->in(1)->Opcode() == Op_Conv2B &&
636 check_iff->in(1)->in(1)->Opcode() == Op_Opaque1, "");
637 Node* opq = check_iff->in(1)->in(1);
638 _igvn.replace_input_of(opq, 1, bol);
639 // Update ctrl.
640 set_ctrl(opq, check_iff->in(0));
641 set_ctrl(check_iff->in(1), check_iff->in(0));
642
643 #ifndef PRODUCT
644 // report that the loop predication has been actually performed
645 // for this loop
646 if (TraceLoopLimitCheck) {
647 tty->print_cr("Counted Loop Limit Check generated:");
648 debug_only( bol->dump(2); )
649 }
650 #endif
651 }
652
653 if (phi_incr != NULL) {
654 // If compare points directly to the phi we need to adjust
655 // the compare so that it points to the incr. Limit have
656 // to be adjusted to keep trip count the same and we
657 // should avoid int overflow.
658 //
659 // i = init; do {} while(i++ < limit);
660 // is converted to
661 // i = init; do {} while(++i < limit+1);
662 //
663 limit = gvn->transform(new AddINode(limit, stride));
664 }
665
666 // Now we need to canonicalize loop condition.
667 if (bt == BoolTest::ne) {
668 assert(stride_con == 1 || stride_con == -1, "simple increment only");
669 // 'ne' can be replaced with 'lt' only when init < limit.
670 if (stride_con > 0 && init_t->_hi < limit_t->_lo)
671 bt = BoolTest::lt;
672 // 'ne' can be replaced with 'gt' only when init > limit.
673 if (stride_con < 0 && init_t->_lo > limit_t->_hi)
674 bt = BoolTest::gt;
675 }
676
677 if (incl_limit) {
678 // The limit check guaranties that 'limit <= (max_jint - stride)' so
679 // we can convert 'i <= limit' to 'i < limit+1' since stride != 0.
680 //
681 Node* one = (stride_con > 0) ? gvn->intcon( 1) : gvn->intcon(-1);
682 limit = gvn->transform(new AddINode(limit, one));
683 if (bt == BoolTest::le)
684 bt = BoolTest::lt;
685 else if (bt == BoolTest::ge)
686 bt = BoolTest::gt;
687 else
688 ShouldNotReachHere();
689 }
690 set_subtree_ctrl( limit );
691
692 if (LoopStripMiningIter == 0) {
693 // Check for SafePoint on backedge and remove
694 Node *sfpt = x->in(LoopNode::LoopBackControl);
695 if (sfpt->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt)) {
696 lazy_replace( sfpt, iftrue );
697 if (loop->_safepts != NULL) {
698 loop->_safepts->yank(sfpt);
699 }
700 loop->_tail = iftrue;
701 }
702 }
703
704 // Build a canonical trip test.
705 // Clone code, as old values may be in use.
706 incr = incr->clone();
707 incr->set_req(1,phi);
708 incr->set_req(2,stride);
709 incr = _igvn.register_new_node_with_optimizer(incr);
710 set_early_ctrl( incr );
711 _igvn.rehash_node_delayed(phi);
712 phi->set_req_X( LoopNode::LoopBackControl, incr, &_igvn );
713
714 // If phi type is more restrictive than Int, raise to
715 // Int to prevent (almost) infinite recursion in igvn
716 // which can only handle integer types for constants or minint..maxint.
717 if (!TypeInt::INT->higher_equal(phi->bottom_type())) {
718 Node* nphi = PhiNode::make(phi->in(0), phi->in(LoopNode::EntryControl), TypeInt::INT);
719 nphi->set_req(LoopNode::LoopBackControl, phi->in(LoopNode::LoopBackControl));
720 nphi = _igvn.register_new_node_with_optimizer(nphi);
721 set_ctrl(nphi, get_ctrl(phi));
722 _igvn.replace_node(phi, nphi);
723 phi = nphi->as_Phi();
724 }
725 cmp = cmp->clone();
726 cmp->set_req(1,incr);
727 cmp->set_req(2,limit);
728 cmp = _igvn.register_new_node_with_optimizer(cmp);
729 set_ctrl(cmp, iff->in(0));
730
731 test = test->clone()->as_Bool();
732 (*(BoolTest*)&test->_test)._test = bt;
733 test->set_req(1,cmp);
734 _igvn.register_new_node_with_optimizer(test);
735 set_ctrl(test, iff->in(0));
736
737 // Replace the old IfNode with a new LoopEndNode
738 Node *lex = _igvn.register_new_node_with_optimizer(new CountedLoopEndNode( iff->in(0), test, cl_prob, iff->as_If()->_fcnt ));
739 IfNode *le = lex->as_If();
740 uint dd = dom_depth(iff);
741 set_idom(le, le->in(0), dd); // Update dominance for loop exit
742 set_loop(le, loop);
743
744 // Get the loop-exit control
745 Node *iffalse = iff->as_If()->proj_out(!(iftrue_op == Op_IfTrue));
746
747 // Need to swap loop-exit and loop-back control?
748 if (iftrue_op == Op_IfFalse) {
749 Node *ift2=_igvn.register_new_node_with_optimizer(new IfTrueNode (le));
750 Node *iff2=_igvn.register_new_node_with_optimizer(new IfFalseNode(le));
751
752 loop->_tail = back_control = ift2;
753 set_loop(ift2, loop);
754 set_loop(iff2, get_loop(iffalse));
755
756 // Lazy update of 'get_ctrl' mechanism.
757 lazy_replace(iffalse, iff2);
758 lazy_replace(iftrue, ift2);
759
760 // Swap names
761 iffalse = iff2;
762 iftrue = ift2;
763 } else {
764 _igvn.rehash_node_delayed(iffalse);
765 _igvn.rehash_node_delayed(iftrue);
766 iffalse->set_req_X( 0, le, &_igvn );
767 iftrue ->set_req_X( 0, le, &_igvn );
768 }
769
770 set_idom(iftrue, le, dd+1);
771 set_idom(iffalse, le, dd+1);
772 assert(iff->outcnt() == 0, "should be dead now");
773 lazy_replace( iff, le ); // fix 'get_ctrl'
774
775 Node *sfpt2 = le->in(0);
776
777 Node* entry_control = init_control;
778 bool strip_mine_loop = LoopStripMiningIter > 1 && loop->_child == NULL &&
779 sfpt2->Opcode() == Op_SafePoint && !loop->_has_call;
780 IdealLoopTree* outer_ilt = NULL;
781 if (strip_mine_loop) {
782 outer_ilt = create_outer_strip_mined_loop(test, cmp, init_control, loop,
783 cl_prob, le->_fcnt, entry_control,
784 iffalse);
785 }
786
787 // Now setup a new CountedLoopNode to replace the existing LoopNode
788 CountedLoopNode *l = new CountedLoopNode(entry_control, back_control);
789 l->set_unswitch_count(x->as_Loop()->unswitch_count()); // Preserve
790 // The following assert is approximately true, and defines the intention
791 // of can_be_counted_loop. It fails, however, because phase->type
792 // is not yet initialized for this loop and its parts.
793 //assert(l->can_be_counted_loop(this), "sanity");
794 _igvn.register_new_node_with_optimizer(l);
795 set_loop(l, loop);
796 loop->_head = l;
797 // Fix all data nodes placed at the old loop head.
798 // Uses the lazy-update mechanism of 'get_ctrl'.
799 lazy_replace( x, l );
800 set_idom(l, entry_control, dom_depth(entry_control) + 1);
801
802 if (LoopStripMiningIter == 0 || strip_mine_loop) {
803 // Check for immediately preceding SafePoint and remove
804 if (sfpt2->Opcode() == Op_SafePoint && (LoopStripMiningIter != 0 || is_deleteable_safept(sfpt2))) {
805 if (strip_mine_loop) {
806 Node* outer_le = outer_ilt->_tail->in(0);
807 Node* sfpt = sfpt2->clone();
808 sfpt->set_req(0, iffalse);
809 outer_le->set_req(0, sfpt);
810 register_control(sfpt, outer_ilt, iffalse);
811 set_idom(outer_le, sfpt, dom_depth(sfpt));
812 }
813 lazy_replace( sfpt2, sfpt2->in(TypeFunc::Control));
814 if (loop->_safepts != NULL) {
815 loop->_safepts->yank(sfpt2);
816 }
817 }
818 }
819
820 // Free up intermediate goo
821 _igvn.remove_dead_node(hook);
822
823 #ifdef ASSERT
824 assert(l->is_valid_counted_loop(), "counted loop shape is messed up");
825 assert(l == loop->_head && l->phi() == phi && l->loopexit_or_null() == lex, "" );
826 #endif
827 #ifndef PRODUCT
828 if (TraceLoopOpts) {
829 tty->print("Counted ");
830 loop->dump_head();
831 }
832 #endif
833
834 C->print_method(PHASE_AFTER_CLOOPS, 3);
835
836 // Capture bounds of the loop in the induction variable Phi before
837 // subsequent transformation (iteration splitting) obscures the
838 // bounds
839 l->phi()->as_Phi()->set_type(l->phi()->Value(&_igvn));
840
841 if (strip_mine_loop) {
842 l->mark_strip_mined();
843 l->verify_strip_mined(1);
844 outer_ilt->_head->as_Loop()->verify_strip_mined(1);
845 loop = outer_ilt;
846 }
847
848 return true;
849 }
850
851 //----------------------exact_limit-------------------------------------------
852 Node* PhaseIdealLoop::exact_limit( IdealLoopTree *loop ) {
853 assert(loop->_head->is_CountedLoop(), "");
854 CountedLoopNode *cl = loop->_head->as_CountedLoop();
855 assert(cl->is_valid_counted_loop(), "");
856
857 if (ABS(cl->stride_con()) == 1 ||
858 cl->limit()->Opcode() == Op_LoopLimit) {
859 // Old code has exact limit (it could be incorrect in case of int overflow).
860 // Loop limit is exact with stride == 1. And loop may already have exact limit.
861 return cl->limit();
862 }
863 Node *limit = NULL;
864 #ifdef ASSERT
865 BoolTest::mask bt = cl->loopexit()->test_trip();
866 assert(bt == BoolTest::lt || bt == BoolTest::gt, "canonical test is expected");
867 #endif
868 if (cl->has_exact_trip_count()) {
869 // Simple case: loop has constant boundaries.
870 // Use jlongs to avoid integer overflow.
871 int stride_con = cl->stride_con();
872 jlong init_con = cl->init_trip()->get_int();
873 jlong limit_con = cl->limit()->get_int();
874 julong trip_cnt = cl->trip_count();
875 jlong final_con = init_con + trip_cnt*stride_con;
876 int final_int = (int)final_con;
877 // The final value should be in integer range since the loop
878 // is counted and the limit was checked for overflow.
879 assert(final_con == (jlong)final_int, "final value should be integer");
880 limit = _igvn.intcon(final_int);
881 } else {
882 // Create new LoopLimit node to get exact limit (final iv value).
883 limit = new LoopLimitNode(C, cl->init_trip(), cl->limit(), cl->stride());
884 register_new_node(limit, cl->in(LoopNode::EntryControl));
885 }
886 assert(limit != NULL, "sanity");
887 return limit;
888 }
889
890 //------------------------------Ideal------------------------------------------
891 // Return a node which is more "ideal" than the current node.
892 // Attempt to convert into a counted-loop.
893 Node *LoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
894 if (!can_be_counted_loop(phase) && !is_OuterStripMinedLoop()) {
895 phase->C->set_major_progress();
896 }
897 return RegionNode::Ideal(phase, can_reshape);
898 }
899
900 void LoopNode::verify_strip_mined(int expect_skeleton) const {
901 #ifdef ASSERT
902 const OuterStripMinedLoopNode* outer = NULL;
903 const CountedLoopNode* inner = NULL;
904 if (is_strip_mined()) {
905 assert(is_CountedLoop(), "no Loop should be marked strip mined");
906 inner = as_CountedLoop();
907 outer = inner->in(LoopNode::EntryControl)->as_OuterStripMinedLoop();
908 } else if (is_OuterStripMinedLoop()) {
909 outer = this->as_OuterStripMinedLoop();
910 inner = outer->unique_ctrl_out()->as_CountedLoop();
911 assert(!is_strip_mined(), "outer loop shouldn't be marked strip mined");
912 }
913 if (inner != NULL || outer != NULL) {
914 assert(inner != NULL && outer != NULL, "missing loop in strip mined nest");
915 Node* outer_tail = outer->in(LoopNode::LoopBackControl);
916 Node* outer_le = outer_tail->in(0);
917 assert(outer_le->Opcode() == Op_OuterStripMinedLoopEnd, "tail of outer loop should be an If");
918 Node* sfpt = outer_le->in(0);
919 assert(sfpt->Opcode() == Op_SafePoint, "where's the safepoint?");
920 Node* inner_out = sfpt->in(0);
921 if (inner_out->outcnt() != 1) {
922 ResourceMark rm;
923 Unique_Node_List wq;
924
925 for (DUIterator_Fast imax, i = inner_out->fast_outs(imax); i < imax; i++) {
926 Node* u = inner_out->fast_out(i);
927 if (u == sfpt) {
928 continue;
929 }
930 wq.clear();
931 wq.push(u);
932 bool found_sfpt = false;
933 for (uint next = 0; next < wq.size() && !found_sfpt; next++) {
934 Node *n = wq.at(next);
935 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax && !found_sfpt; i++) {
936 Node* u = n->fast_out(i);
937 if (u == sfpt) {
938 found_sfpt = true;
939 }
940 if (!u->is_CFG()) {
941 wq.push(u);
942 }
943 }
944 }
945 assert(found_sfpt, "no node in loop that's not input to safepoint");
946 }
947 }
948 CountedLoopEndNode* cle = inner_out->in(0)->as_CountedLoopEnd();
949 assert(cle == inner->loopexit_or_null(), "mismatch");
950 bool has_skeleton = outer_le->in(1)->bottom_type()->singleton() && outer_le->in(1)->bottom_type()->is_int()->get_con() == 0;
951 if (has_skeleton) {
952 assert(expect_skeleton == 1 || expect_skeleton == -1, "unexpected skeleton node");
953 assert(outer->outcnt() == 2, "only phis");
954 } else {
955 assert(expect_skeleton == 0 || expect_skeleton == -1, "no skeleton node?");
956 uint phis = 0;
957 for (DUIterator_Fast imax, i = inner->fast_outs(imax); i < imax; i++) {
958 Node* u = inner->fast_out(i);
959 if (u->is_Phi()) {
960 phis++;
961 }
962 }
963 for (DUIterator_Fast imax, i = outer->fast_outs(imax); i < imax; i++) {
964 Node* u = outer->fast_out(i);
965 assert(u == outer || u == inner || u->is_Phi(), "nothing between inner and outer loop");
966 }
967 uint stores = 0;
968 for (DUIterator_Fast imax, i = inner_out->fast_outs(imax); i < imax; i++) {
969 Node* u = inner_out->fast_out(i);
970 if (u->is_Store()) {
971 stores++;
972 }
973 }
974 assert(outer->outcnt() >= phis + 2 && outer->outcnt() <= phis + 2 + stores + 1, "only phis");
975 }
976 assert(sfpt->outcnt() == 1, "no data node");
977 assert(outer_tail->outcnt() == 1 || !has_skeleton, "no data node");
978 }
979 #endif
980 }
981
982 //=============================================================================
983 //------------------------------Ideal------------------------------------------
984 // Return a node which is more "ideal" than the current node.
985 // Attempt to convert into a counted-loop.
986 Node *CountedLoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
987 return RegionNode::Ideal(phase, can_reshape);
988 }
989
990 //------------------------------dump_spec--------------------------------------
991 // Dump special per-node info
992 #ifndef PRODUCT
993 void CountedLoopNode::dump_spec(outputStream *st) const {
994 LoopNode::dump_spec(st);
995 if (stride_is_con()) {
996 st->print("stride: %d ",stride_con());
997 }
998 if (is_pre_loop ()) st->print("pre of N%d" , _main_idx);
999 if (is_main_loop()) st->print("main of N%d", _idx);
1000 if (is_post_loop()) st->print("post of N%d", _main_idx);
1001 if (is_strip_mined()) st->print(" strip mined");
1002 }
1003 #endif
1004
1005 //=============================================================================
1006 int CountedLoopEndNode::stride_con() const {
1007 return stride()->bottom_type()->is_int()->get_con();
1008 }
1009
1010 //=============================================================================
1011 //------------------------------Value-----------------------------------------
1012 const Type* LoopLimitNode::Value(PhaseGVN* phase) const {
1013 const Type* init_t = phase->type(in(Init));
1014 const Type* limit_t = phase->type(in(Limit));
1015 const Type* stride_t = phase->type(in(Stride));
1016 // Either input is TOP ==> the result is TOP
1017 if (init_t == Type::TOP) return Type::TOP;
1018 if (limit_t == Type::TOP) return Type::TOP;
1019 if (stride_t == Type::TOP) return Type::TOP;
1020
1021 int stride_con = stride_t->is_int()->get_con();
1022 if (stride_con == 1)
1023 return NULL; // Identity
1024
1025 if (init_t->is_int()->is_con() && limit_t->is_int()->is_con()) {
1026 // Use jlongs to avoid integer overflow.
1027 jlong init_con = init_t->is_int()->get_con();
1028 jlong limit_con = limit_t->is_int()->get_con();
1029 int stride_m = stride_con - (stride_con > 0 ? 1 : -1);
1030 jlong trip_count = (limit_con - init_con + stride_m)/stride_con;
1031 jlong final_con = init_con + stride_con*trip_count;
1032 int final_int = (int)final_con;
1033 // The final value should be in integer range since the loop
1034 // is counted and the limit was checked for overflow.
1035 assert(final_con == (jlong)final_int, "final value should be integer");
1036 return TypeInt::make(final_int);
1037 }
1038
1039 return bottom_type(); // TypeInt::INT
1040 }
1041
1042 //------------------------------Ideal------------------------------------------
1043 // Return a node which is more "ideal" than the current node.
1044 Node *LoopLimitNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1045 if (phase->type(in(Init)) == Type::TOP ||
1046 phase->type(in(Limit)) == Type::TOP ||
1047 phase->type(in(Stride)) == Type::TOP)
1048 return NULL; // Dead
1049
1050 int stride_con = phase->type(in(Stride))->is_int()->get_con();
1051 if (stride_con == 1)
1052 return NULL; // Identity
1053
1054 if (in(Init)->is_Con() && in(Limit)->is_Con())
1055 return NULL; // Value
1056
1057 // Delay following optimizations until all loop optimizations
1058 // done to keep Ideal graph simple.
1059 if (!can_reshape || phase->C->major_progress())
1060 return NULL;
1061
1062 const TypeInt* init_t = phase->type(in(Init) )->is_int();
1063 const TypeInt* limit_t = phase->type(in(Limit))->is_int();
1064 int stride_p;
1065 jlong lim, ini;
1066 julong max;
1067 if (stride_con > 0) {
1068 stride_p = stride_con;
1069 lim = limit_t->_hi;
1070 ini = init_t->_lo;
1071 max = (julong)max_jint;
1072 } else {
1073 stride_p = -stride_con;
1074 lim = init_t->_hi;
1075 ini = limit_t->_lo;
1076 max = (julong)min_jint;
1077 }
1078 julong range = lim - ini + stride_p;
1079 if (range <= max) {
1080 // Convert to integer expression if it is not overflow.
1081 Node* stride_m = phase->intcon(stride_con - (stride_con > 0 ? 1 : -1));
1082 Node *range = phase->transform(new SubINode(in(Limit), in(Init)));
1083 Node *bias = phase->transform(new AddINode(range, stride_m));
1084 Node *trip = phase->transform(new DivINode(0, bias, in(Stride)));
1085 Node *span = phase->transform(new MulINode(trip, in(Stride)));
1086 return new AddINode(span, in(Init)); // exact limit
1087 }
1088
1089 if (is_power_of_2(stride_p) || // divisor is 2^n
1090 !Matcher::has_match_rule(Op_LoopLimit)) { // or no specialized Mach node?
1091 // Convert to long expression to avoid integer overflow
1092 // and let igvn optimizer convert this division.
1093 //
1094 Node* init = phase->transform( new ConvI2LNode(in(Init)));
1095 Node* limit = phase->transform( new ConvI2LNode(in(Limit)));
1096 Node* stride = phase->longcon(stride_con);
1097 Node* stride_m = phase->longcon(stride_con - (stride_con > 0 ? 1 : -1));
1098
1099 Node *range = phase->transform(new SubLNode(limit, init));
1100 Node *bias = phase->transform(new AddLNode(range, stride_m));
1101 Node *span;
1102 if (stride_con > 0 && is_power_of_2(stride_p)) {
1103 // bias >= 0 if stride >0, so if stride is 2^n we can use &(-stride)
1104 // and avoid generating rounding for division. Zero trip guard should
1105 // guarantee that init < limit but sometimes the guard is missing and
1106 // we can get situation when init > limit. Note, for the empty loop
1107 // optimization zero trip guard is generated explicitly which leaves
1108 // only RCE predicate where exact limit is used and the predicate
1109 // will simply fail forcing recompilation.
1110 Node* neg_stride = phase->longcon(-stride_con);
1111 span = phase->transform(new AndLNode(bias, neg_stride));
1112 } else {
1113 Node *trip = phase->transform(new DivLNode(0, bias, stride));
1114 span = phase->transform(new MulLNode(trip, stride));
1115 }
1116 // Convert back to int
1117 Node *span_int = phase->transform(new ConvL2INode(span));
1118 return new AddINode(span_int, in(Init)); // exact limit
1119 }
1120
1121 return NULL; // No progress
1122 }
1123
1124 //------------------------------Identity---------------------------------------
1125 // If stride == 1 return limit node.
1126 Node* LoopLimitNode::Identity(PhaseGVN* phase) {
1127 int stride_con = phase->type(in(Stride))->is_int()->get_con();
1128 if (stride_con == 1 || stride_con == -1)
1129 return in(Limit);
1130 return this;
1131 }
1132
1133 //=============================================================================
1134 //----------------------match_incr_with_optional_truncation--------------------
1135 // Match increment with optional truncation:
1136 // CHAR: (i+1)&0x7fff, BYTE: ((i+1)<<8)>>8, or SHORT: ((i+1)<<16)>>16
1137 // Return NULL for failure. Success returns the increment node.
1138 Node* CountedLoopNode::match_incr_with_optional_truncation(
1139 Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type) {
1140 // Quick cutouts:
1141 if (expr == NULL || expr->req() != 3) return NULL;
1142
1143 Node *t1 = NULL;
1144 Node *t2 = NULL;
1145 const TypeInt* trunc_t = TypeInt::INT;
1146 Node* n1 = expr;
1147 int n1op = n1->Opcode();
1148
1149 // Try to strip (n1 & M) or (n1 << N >> N) from n1.
1150 if (n1op == Op_AndI &&
1151 n1->in(2)->is_Con() &&
1152 n1->in(2)->bottom_type()->is_int()->get_con() == 0x7fff) {
1153 // %%% This check should match any mask of 2**K-1.
1154 t1 = n1;
1155 n1 = t1->in(1);
1156 n1op = n1->Opcode();
1157 trunc_t = TypeInt::CHAR;
1158 } else if (n1op == Op_RShiftI &&
1159 n1->in(1) != NULL &&
1160 n1->in(1)->Opcode() == Op_LShiftI &&
1161 n1->in(2) == n1->in(1)->in(2) &&
1162 n1->in(2)->is_Con()) {
1163 jint shift = n1->in(2)->bottom_type()->is_int()->get_con();
1164 // %%% This check should match any shift in [1..31].
1165 if (shift == 16 || shift == 8) {
1166 t1 = n1;
1167 t2 = t1->in(1);
1168 n1 = t2->in(1);
1169 n1op = n1->Opcode();
1170 if (shift == 16) {
1171 trunc_t = TypeInt::SHORT;
1172 } else if (shift == 8) {
1173 trunc_t = TypeInt::BYTE;
1174 }
1175 }
1176 }
1177
1178 // If (maybe after stripping) it is an AddI, we won:
1179 if (n1op == Op_AddI) {
1180 *trunc1 = t1;
1181 *trunc2 = t2;
1182 *trunc_type = trunc_t;
1183 return n1;
1184 }
1185
1186 // failed
1187 return NULL;
1188 }
1189
1190 LoopNode* CountedLoopNode::skip_strip_mined(int expect_skeleton) {
1191 if (is_strip_mined()) {
1192 verify_strip_mined(expect_skeleton);
1193 return in(EntryControl)->as_Loop();
1194 }
1195 return this;
1196 }
1197
1198 OuterStripMinedLoopNode* CountedLoopNode::outer_loop() const {
1199 assert(is_strip_mined(), "not a strip mined loop");
1200 Node* c = in(EntryControl);
1201 if (c == NULL || c->is_top() || !c->is_OuterStripMinedLoop()) {
1202 return NULL;
1203 }
1204 return c->as_OuterStripMinedLoop();
1205 }
1206
1207 IfTrueNode* OuterStripMinedLoopNode::outer_loop_tail() const {
1208 Node* c = in(LoopBackControl);
1209 if (c == NULL || c->is_top()) {
1210 return NULL;
1211 }
1212 return c->as_IfTrue();
1213 }
1214
1215 IfTrueNode* CountedLoopNode::outer_loop_tail() const {
1216 LoopNode* l = outer_loop();
1217 if (l == NULL) {
1218 return NULL;
1219 }
1220 return l->outer_loop_tail();
1221 }
1222
1223 OuterStripMinedLoopEndNode* OuterStripMinedLoopNode::outer_loop_end() const {
1224 IfTrueNode* proj = outer_loop_tail();
1225 if (proj == NULL) {
1226 return NULL;
1227 }
1228 Node* c = proj->in(0);
1229 if (c == NULL || c->is_top() || c->outcnt() != 2) {
1230 return NULL;
1231 }
1232 return c->as_OuterStripMinedLoopEnd();
1233 }
1234
1235 OuterStripMinedLoopEndNode* CountedLoopNode::outer_loop_end() const {
1236 LoopNode* l = outer_loop();
1237 if (l == NULL) {
1238 return NULL;
1239 }
1240 return l->outer_loop_end();
1241 }
1242
1243 IfFalseNode* OuterStripMinedLoopNode::outer_loop_exit() const {
1244 IfNode* le = outer_loop_end();
1245 if (le == NULL) {
1246 return NULL;
1247 }
1248 Node* c = le->proj_out_or_null(false);
1249 if (c == NULL) {
1250 return NULL;
1251 }
1252 return c->as_IfFalse();
1253 }
1254
1255 IfFalseNode* CountedLoopNode::outer_loop_exit() const {
1256 LoopNode* l = outer_loop();
1257 if (l == NULL) {
1258 return NULL;
1259 }
1260 return l->outer_loop_exit();
1261 }
1262
1263 SafePointNode* OuterStripMinedLoopNode::outer_safepoint() const {
1264 IfNode* le = outer_loop_end();
1265 if (le == NULL) {
1266 return NULL;
1267 }
1268 Node* c = le->in(0);
1269 if (c == NULL || c->is_top()) {
1270 return NULL;
1271 }
1272 assert(c->Opcode() == Op_SafePoint, "broken outer loop");
1273 return c->as_SafePoint();
1274 }
1275
1276 SafePointNode* CountedLoopNode::outer_safepoint() const {
1277 LoopNode* l = outer_loop();
1278 if (l == NULL) {
1279 return NULL;
1280 }
1281 return l->outer_safepoint();
1282 }
1283
1284 Node* CountedLoopNode::skip_predicates() {
1285 if (is_main_loop()) {
1286 Node* ctrl = skip_strip_mined()->in(LoopNode::EntryControl);
1287 while (ctrl != NULL && ctrl->is_Proj() && ctrl->in(0)->is_If() &&
1288 ctrl->in(0)->as_If()->proj_out(1-ctrl->as_Proj()->_con)->outcnt() == 1 &&
1289 ctrl->in(0)->as_If()->proj_out(1-ctrl->as_Proj()->_con)->unique_out()->Opcode() == Op_Halt) {
1290 ctrl = ctrl->in(0)->in(0);
1291 }
1292
1293 return ctrl;
1294 }
1295 return in(LoopNode::EntryControl);
1296 }
1297
1298 void OuterStripMinedLoopNode::adjust_strip_mined_loop(PhaseIterGVN* igvn) {
1299 // Look for the outer & inner strip mined loop, reduce number of
1300 // iterations of the inner loop, set exit condition of outer loop,
1301 // construct required phi nodes for outer loop.
1302 CountedLoopNode* inner_cl = unique_ctrl_out()->as_CountedLoop();
1303 assert(inner_cl->is_strip_mined(), "inner loop should be strip mined");
1304 Node* inner_iv_phi = inner_cl->phi();
1305 if (inner_iv_phi == NULL) {
1306 IfNode* outer_le = outer_loop_end();
1307 Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt));
1308 igvn->replace_node(outer_le, iff);
1309 inner_cl->clear_strip_mined();
1310 return;
1311 }
1312 CountedLoopEndNode* inner_cle = inner_cl->loopexit();
1313
1314 int stride = inner_cl->stride_con();
1315 jlong scaled_iters_long = ((jlong)LoopStripMiningIter) * ABS(stride);
1316 int scaled_iters = (int)scaled_iters_long;
1317 int short_scaled_iters = LoopStripMiningIterShortLoop* ABS(stride);
1318 const TypeInt* inner_iv_t = igvn->type(inner_iv_phi)->is_int();
1319 jlong iter_estimate = (jlong)inner_iv_t->_hi - (jlong)inner_iv_t->_lo;
1320 assert(iter_estimate > 0, "broken");
1321 if ((jlong)scaled_iters != scaled_iters_long || iter_estimate <= short_scaled_iters) {
1322 // Remove outer loop and safepoint (too few iterations)
1323 Node* outer_sfpt = outer_safepoint();
1324 Node* outer_out = outer_loop_exit();
1325 igvn->replace_node(outer_out, outer_sfpt->in(0));
1326 igvn->replace_input_of(outer_sfpt, 0, igvn->C->top());
1327 inner_cl->clear_strip_mined();
1328 return;
1329 }
1330 if (iter_estimate <= scaled_iters_long) {
1331 // We would only go through one iteration of
1332 // the outer loop: drop the outer loop but
1333 // keep the safepoint so we don't run for
1334 // too long without a safepoint
1335 IfNode* outer_le = outer_loop_end();
1336 Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt));
1337 igvn->replace_node(outer_le, iff);
1338 inner_cl->clear_strip_mined();
1339 return;
1340 }
1341
1342 Node* cle_tail = inner_cle->proj_out(true);
1343 ResourceMark rm;
1344 Node_List old_new;
1345 if (cle_tail->outcnt() > 1) {
1346 // Look for nodes on backedge of inner loop and clone them
1347 Unique_Node_List backedge_nodes;
1348 for (DUIterator_Fast imax, i = cle_tail->fast_outs(imax); i < imax; i++) {
1349 Node* u = cle_tail->fast_out(i);
1350 if (u != inner_cl) {
1351 assert(!u->is_CFG(), "control flow on the backedge?");
1352 backedge_nodes.push(u);
1353 }
1354 }
1355 uint last = igvn->C->unique();
1356 for (uint next = 0; next < backedge_nodes.size(); next++) {
1357 Node* n = backedge_nodes.at(next);
1358 old_new.map(n->_idx, n->clone());
1359 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1360 Node* u = n->fast_out(i);
1361 assert(!u->is_CFG(), "broken");
1362 if (u->_idx >= last) {
1363 continue;
1364 }
1365 if (!u->is_Phi()) {
1366 backedge_nodes.push(u);
1367 } else {
1368 assert(u->in(0) == inner_cl, "strange phi on the backedge");
1369 }
1370 }
1371 }
1372 // Put the clones on the outer loop backedge
1373 Node* le_tail = outer_loop_tail();
1374 for (uint next = 0; next < backedge_nodes.size(); next++) {
1375 Node *n = old_new[backedge_nodes.at(next)->_idx];
1376 for (uint i = 1; i < n->req(); i++) {
1377 if (n->in(i) != NULL && old_new[n->in(i)->_idx] != NULL) {
1378 n->set_req(i, old_new[n->in(i)->_idx]);
1379 }
1380 }
1381 if (n->in(0) != NULL && n->in(0) == cle_tail) {
1382 n->set_req(0, le_tail);
1383 }
1384 igvn->register_new_node_with_optimizer(n);
1385 }
1386 }
1387
1388 Node* iv_phi = NULL;
1389 // Make a clone of each phi in the inner loop
1390 // for the outer loop
1391 for (uint i = 0; i < inner_cl->outcnt(); i++) {
1392 Node* u = inner_cl->raw_out(i);
1393 if (u->is_Phi()) {
1394 assert(u->in(0) == inner_cl, "inconsistent");
1395 Node* phi = u->clone();
1396 phi->set_req(0, this);
1397 Node* be = old_new[phi->in(LoopNode::LoopBackControl)->_idx];
1398 if (be != NULL) {
1399 phi->set_req(LoopNode::LoopBackControl, be);
1400 }
1401 phi = igvn->transform(phi);
1402 igvn->replace_input_of(u, LoopNode::EntryControl, phi);
1403 if (u == inner_iv_phi) {
1404 iv_phi = phi;
1405 }
1406 }
1407 }
1408 Node* cle_out = inner_cle->proj_out(false);
1409 if (cle_out->outcnt() > 1) {
1410 // Look for chains of stores that were sunk
1411 // out of the inner loop and are in the outer loop
1412 for (DUIterator_Fast imax, i = cle_out->fast_outs(imax); i < imax; i++) {
1413 Node* u = cle_out->fast_out(i);
1414 if (u->is_Store()) {
1415 Node* first = u;
1416 for(;;) {
1417 Node* next = first->in(MemNode::Memory);
1418 if (!next->is_Store() || next->in(0) != cle_out) {
1419 break;
1420 }
1421 first = next;
1422 }
1423 Node* last = u;
1424 for(;;) {
1425 Node* next = NULL;
1426 for (DUIterator_Fast jmax, j = last->fast_outs(jmax); j < jmax; j++) {
1427 Node* uu = last->fast_out(j);
1428 if (uu->is_Store() && uu->in(0) == cle_out) {
1429 assert(next == NULL, "only one in the outer loop");
1430 next = uu;
1431 }
1432 }
1433 if (next == NULL) {
1434 break;
1435 }
1436 last = next;
1437 }
1438 Node* phi = NULL;
1439 for (DUIterator_Fast jmax, j = fast_outs(jmax); j < jmax; j++) {
1440 Node* uu = fast_out(j);
1441 if (uu->is_Phi()) {
1442 Node* be = uu->in(LoopNode::LoopBackControl);
1443 if (be->is_Store() && old_new[be->_idx] != NULL) {
1444 assert(false, "store on the backedge + sunk stores: unsupported");
1445 // drop outer loop
1446 IfNode* outer_le = outer_loop_end();
1447 Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt));
1448 igvn->replace_node(outer_le, iff);
1449 inner_cl->clear_strip_mined();
1450 return;
1451 }
1452 if (be == last || be == first->in(MemNode::Memory)) {
1453 assert(phi == NULL, "only one phi");
1454 phi = uu;
1455 }
1456 }
1457 }
1458 #ifdef ASSERT
1459 for (DUIterator_Fast jmax, j = fast_outs(jmax); j < jmax; j++) {
1460 Node* uu = fast_out(j);
1461 if (uu->is_Phi() && uu->bottom_type() == Type::MEMORY) {
1462 if (uu->adr_type() == igvn->C->get_adr_type(igvn->C->get_alias_index(u->adr_type()))) {
1463 assert(phi == uu, "what's that phi?");
1464 } else if (uu->adr_type() == TypePtr::BOTTOM) {
1465 Node* n = uu->in(LoopNode::LoopBackControl);
1466 uint limit = igvn->C->live_nodes();
1467 uint i = 0;
1468 while (n != uu) {
1469 i++;
1470 assert(i < limit, "infinite loop");
1471 if (n->is_Proj()) {
1472 n = n->in(0);
1473 } else if (n->is_SafePoint() || n->is_MemBar()) {
1474 n = n->in(TypeFunc::Memory);
1475 } else if (n->is_Phi()) {
1476 n = n->in(1);
1477 } else if (n->is_MergeMem()) {
1478 n = n->as_MergeMem()->memory_at(igvn->C->get_alias_index(u->adr_type()));
1479 } else if (n->is_Store() || n->is_LoadStore() || n->is_ClearArray()) {
1480 n = n->in(MemNode::Memory);
1481 } else {
1482 n->dump();
1483 ShouldNotReachHere();
1484 }
1485 }
1486 }
1487 }
1488 }
1489 #endif
1490 if (phi == NULL) {
1491 // If the an entire chains was sunk, the
1492 // inner loop has no phi for that memory
1493 // slice, create one for the outer loop
1494 phi = PhiNode::make(this, first->in(MemNode::Memory), Type::MEMORY,
1495 igvn->C->get_adr_type(igvn->C->get_alias_index(u->adr_type())));
1496 phi->set_req(LoopNode::LoopBackControl, last);
1497 phi = igvn->transform(phi);
1498 igvn->replace_input_of(first, MemNode::Memory, phi);
1499 } else {
1500 // Or fix the outer loop fix to include
1501 // that chain of stores.
1502 Node* be = phi->in(LoopNode::LoopBackControl);
1503 assert(!(be->is_Store() && old_new[be->_idx] != NULL), "store on the backedge + sunk stores: unsupported");
1504 if (be == first->in(MemNode::Memory)) {
1505 if (be == phi->in(LoopNode::LoopBackControl)) {
1506 igvn->replace_input_of(phi, LoopNode::LoopBackControl, last);
1507 } else {
1508 igvn->replace_input_of(be, MemNode::Memory, last);
1509 }
1510 } else {
1511 #ifdef ASSERT
1512 if (be == phi->in(LoopNode::LoopBackControl)) {
1513 assert(phi->in(LoopNode::LoopBackControl) == last, "");
1514 } else {
1515 assert(be->in(MemNode::Memory) == last, "");
1516 }
1517 #endif
1518 }
1519 }
1520 }
1521 }
1522 }
1523
1524 if (iv_phi != NULL) {
1525 // Now adjust the inner loop's exit condition
1526 Node* limit = inner_cl->limit();
1527 Node* sub = NULL;
1528 if (stride > 0) {
1529 sub = igvn->transform(new SubINode(limit, iv_phi));
1530 } else {
1531 sub = igvn->transform(new SubINode(iv_phi, limit));
1532 }
1533 Node* min = igvn->transform(new MinINode(sub, igvn->intcon(scaled_iters)));
1534 Node* new_limit = NULL;
1535 if (stride > 0) {
1536 new_limit = igvn->transform(new AddINode(min, iv_phi));
1537 } else {
1538 new_limit = igvn->transform(new SubINode(iv_phi, min));
1539 }
1540 Node* cmp = inner_cle->cmp_node()->clone();
1541 igvn->replace_input_of(cmp, 2, new_limit);
1542 Node* bol = inner_cle->in(CountedLoopEndNode::TestValue)->clone();
1543 cmp->set_req(2, limit);
1544 bol->set_req(1, igvn->transform(cmp));
1545 igvn->replace_input_of(outer_loop_end(), 1, igvn->transform(bol));
1546 } else {
1547 assert(false, "should be able to adjust outer loop");
1548 IfNode* outer_le = outer_loop_end();
1549 Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt));
1550 igvn->replace_node(outer_le, iff);
1551 inner_cl->clear_strip_mined();
1552 }
1553 }
1554
1555 const Type* OuterStripMinedLoopEndNode::Value(PhaseGVN* phase) const {
1556 if (!in(0)) return Type::TOP;
1557 if (phase->type(in(0)) == Type::TOP)
1558 return Type::TOP;
1559
1560 return TypeTuple::IFBOTH;
1561 }
1562
1563 Node *OuterStripMinedLoopEndNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1564 if (remove_dead_region(phase, can_reshape)) return this;
1565
1566 return NULL;
1567 }
1568
1569 //------------------------------filtered_type--------------------------------
1570 // Return a type based on condition control flow
1571 // A successful return will be a type that is restricted due
1572 // to a series of dominating if-tests, such as:
1573 // if (i < 10) {
1574 // if (i > 0) {
1575 // here: "i" type is [1..10)
1576 // }
1577 // }
1578 // or a control flow merge
1579 // if (i < 10) {
1580 // do {
1581 // phi( , ) -- at top of loop type is [min_int..10)
1582 // i = ?
1583 // } while ( i < 10)
1584 //
1585 const TypeInt* PhaseIdealLoop::filtered_type( Node *n, Node* n_ctrl) {
1586 assert(n && n->bottom_type()->is_int(), "must be int");
1587 const TypeInt* filtered_t = NULL;
1588 if (!n->is_Phi()) {
1589 assert(n_ctrl != NULL || n_ctrl == C->top(), "valid control");
1590 filtered_t = filtered_type_from_dominators(n, n_ctrl);
1591
1592 } else {
1593 Node* phi = n->as_Phi();
1594 Node* region = phi->in(0);
1595 assert(n_ctrl == NULL || n_ctrl == region, "ctrl parameter must be region");
1596 if (region && region != C->top()) {
1597 for (uint i = 1; i < phi->req(); i++) {
1598 Node* val = phi->in(i);
1599 Node* use_c = region->in(i);
1600 const TypeInt* val_t = filtered_type_from_dominators(val, use_c);
1601 if (val_t != NULL) {
1602 if (filtered_t == NULL) {
1603 filtered_t = val_t;
1604 } else {
1605 filtered_t = filtered_t->meet(val_t)->is_int();
1606 }
1607 }
1608 }
1609 }
1610 }
1611 const TypeInt* n_t = _igvn.type(n)->is_int();
1612 if (filtered_t != NULL) {
1613 n_t = n_t->join(filtered_t)->is_int();
1614 }
1615 return n_t;
1616 }
1617
1618
1619 //------------------------------filtered_type_from_dominators--------------------------------
1620 // Return a possibly more restrictive type for val based on condition control flow of dominators
1621 const TypeInt* PhaseIdealLoop::filtered_type_from_dominators( Node* val, Node *use_ctrl) {
1622 if (val->is_Con()) {
1623 return val->bottom_type()->is_int();
1624 }
1625 uint if_limit = 10; // Max number of dominating if's visited
1626 const TypeInt* rtn_t = NULL;
1627
1628 if (use_ctrl && use_ctrl != C->top()) {
1629 Node* val_ctrl = get_ctrl(val);
1630 uint val_dom_depth = dom_depth(val_ctrl);
1631 Node* pred = use_ctrl;
1632 uint if_cnt = 0;
1633 while (if_cnt < if_limit) {
1634 if ((pred->Opcode() == Op_IfTrue || pred->Opcode() == Op_IfFalse)) {
1635 if_cnt++;
1636 const TypeInt* if_t = IfNode::filtered_int_type(&_igvn, val, pred);
1637 if (if_t != NULL) {
1638 if (rtn_t == NULL) {
1639 rtn_t = if_t;
1640 } else {
1641 rtn_t = rtn_t->join(if_t)->is_int();
1642 }
1643 }
1644 }
1645 pred = idom(pred);
1646 if (pred == NULL || pred == C->top()) {
1647 break;
1648 }
1649 // Stop if going beyond definition block of val
1650 if (dom_depth(pred) < val_dom_depth) {
1651 break;
1652 }
1653 }
1654 }
1655 return rtn_t;
1656 }
1657
1658
1659 //------------------------------dump_spec--------------------------------------
1660 // Dump special per-node info
1661 #ifndef PRODUCT
1662 void CountedLoopEndNode::dump_spec(outputStream *st) const {
1663 if( in(TestValue) != NULL && in(TestValue)->is_Bool() ) {
1664 BoolTest bt( test_trip()); // Added this for g++.
1665
1666 st->print("[");
1667 bt.dump_on(st);
1668 st->print("]");
1669 }
1670 st->print(" ");
1671 IfNode::dump_spec(st);
1672 }
1673 #endif
1674
1675 //=============================================================================
1676 //------------------------------is_member--------------------------------------
1677 // Is 'l' a member of 'this'?
1678 bool IdealLoopTree::is_member(const IdealLoopTree *l) const {
1679 while( l->_nest > _nest ) l = l->_parent;
1680 return l == this;
1681 }
1682
1683 //------------------------------set_nest---------------------------------------
1684 // Set loop tree nesting depth. Accumulate _has_call bits.
1685 int IdealLoopTree::set_nest( uint depth ) {
1686 _nest = depth;
1687 int bits = _has_call;
1688 if( _child ) bits |= _child->set_nest(depth+1);
1689 if( bits ) _has_call = 1;
1690 if( _next ) bits |= _next ->set_nest(depth );
1691 return bits;
1692 }
1693
1694 //------------------------------split_fall_in----------------------------------
1695 // Split out multiple fall-in edges from the loop header. Move them to a
1696 // private RegionNode before the loop. This becomes the loop landing pad.
1697 void IdealLoopTree::split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ) {
1698 PhaseIterGVN &igvn = phase->_igvn;
1699 uint i;
1700
1701 // Make a new RegionNode to be the landing pad.
1702 Node *landing_pad = new RegionNode( fall_in_cnt+1 );
1703 phase->set_loop(landing_pad,_parent);
1704 // Gather all the fall-in control paths into the landing pad
1705 uint icnt = fall_in_cnt;
1706 uint oreq = _head->req();
1707 for( i = oreq-1; i>0; i-- )
1708 if( !phase->is_member( this, _head->in(i) ) )
1709 landing_pad->set_req(icnt--,_head->in(i));
1710
1711 // Peel off PhiNode edges as well
1712 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1713 Node *oj = _head->fast_out(j);
1714 if( oj->is_Phi() ) {
1715 PhiNode* old_phi = oj->as_Phi();
1716 assert( old_phi->region() == _head, "" );
1717 igvn.hash_delete(old_phi); // Yank from hash before hacking edges
1718 Node *p = PhiNode::make_blank(landing_pad, old_phi);
1719 uint icnt = fall_in_cnt;
1720 for( i = oreq-1; i>0; i-- ) {
1721 if( !phase->is_member( this, _head->in(i) ) ) {
1722 p->init_req(icnt--, old_phi->in(i));
1723 // Go ahead and clean out old edges from old phi
1724 old_phi->del_req(i);
1725 }
1726 }
1727 // Search for CSE's here, because ZKM.jar does a lot of
1728 // loop hackery and we need to be a little incremental
1729 // with the CSE to avoid O(N^2) node blow-up.
1730 Node *p2 = igvn.hash_find_insert(p); // Look for a CSE
1731 if( p2 ) { // Found CSE
1732 p->destruct(); // Recover useless new node
1733 p = p2; // Use old node
1734 } else {
1735 igvn.register_new_node_with_optimizer(p, old_phi);
1736 }
1737 // Make old Phi refer to new Phi.
1738 old_phi->add_req(p);
1739 // Check for the special case of making the old phi useless and
1740 // disappear it. In JavaGrande I have a case where this useless
1741 // Phi is the loop limit and prevents recognizing a CountedLoop
1742 // which in turn prevents removing an empty loop.
1743 Node *id_old_phi = old_phi->Identity( &igvn );
1744 if( id_old_phi != old_phi ) { // Found a simple identity?
1745 // Note that I cannot call 'replace_node' here, because
1746 // that will yank the edge from old_phi to the Region and
1747 // I'm mid-iteration over the Region's uses.
1748 for (DUIterator_Last imin, i = old_phi->last_outs(imin); i >= imin; ) {
1749 Node* use = old_phi->last_out(i);
1750 igvn.rehash_node_delayed(use);
1751 uint uses_found = 0;
1752 for (uint j = 0; j < use->len(); j++) {
1753 if (use->in(j) == old_phi) {
1754 if (j < use->req()) use->set_req (j, id_old_phi);
1755 else use->set_prec(j, id_old_phi);
1756 uses_found++;
1757 }
1758 }
1759 i -= uses_found; // we deleted 1 or more copies of this edge
1760 }
1761 }
1762 igvn._worklist.push(old_phi);
1763 }
1764 }
1765 // Finally clean out the fall-in edges from the RegionNode
1766 for( i = oreq-1; i>0; i-- ) {
1767 if( !phase->is_member( this, _head->in(i) ) ) {
1768 _head->del_req(i);
1769 }
1770 }
1771 igvn.rehash_node_delayed(_head);
1772 // Transform landing pad
1773 igvn.register_new_node_with_optimizer(landing_pad, _head);
1774 // Insert landing pad into the header
1775 _head->add_req(landing_pad);
1776 }
1777
1778 //------------------------------split_outer_loop-------------------------------
1779 // Split out the outermost loop from this shared header.
1780 void IdealLoopTree::split_outer_loop( PhaseIdealLoop *phase ) {
1781 PhaseIterGVN &igvn = phase->_igvn;
1782
1783 // Find index of outermost loop; it should also be my tail.
1784 uint outer_idx = 1;
1785 while( _head->in(outer_idx) != _tail ) outer_idx++;
1786
1787 // Make a LoopNode for the outermost loop.
1788 Node *ctl = _head->in(LoopNode::EntryControl);
1789 Node *outer = new LoopNode( ctl, _head->in(outer_idx) );
1790 outer = igvn.register_new_node_with_optimizer(outer, _head);
1791 phase->set_created_loop_node();
1792
1793 // Outermost loop falls into '_head' loop
1794 _head->set_req(LoopNode::EntryControl, outer);
1795 _head->del_req(outer_idx);
1796 // Split all the Phis up between '_head' loop and 'outer' loop.
1797 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1798 Node *out = _head->fast_out(j);
1799 if( out->is_Phi() ) {
1800 PhiNode *old_phi = out->as_Phi();
1801 assert( old_phi->region() == _head, "" );
1802 Node *phi = PhiNode::make_blank(outer, old_phi);
1803 phi->init_req(LoopNode::EntryControl, old_phi->in(LoopNode::EntryControl));
1804 phi->init_req(LoopNode::LoopBackControl, old_phi->in(outer_idx));
1805 phi = igvn.register_new_node_with_optimizer(phi, old_phi);
1806 // Make old Phi point to new Phi on the fall-in path
1807 igvn.replace_input_of(old_phi, LoopNode::EntryControl, phi);
1808 old_phi->del_req(outer_idx);
1809 }
1810 }
1811
1812 // Use the new loop head instead of the old shared one
1813 _head = outer;
1814 phase->set_loop(_head, this);
1815 }
1816
1817 //------------------------------fix_parent-------------------------------------
1818 static void fix_parent( IdealLoopTree *loop, IdealLoopTree *parent ) {
1819 loop->_parent = parent;
1820 if( loop->_child ) fix_parent( loop->_child, loop );
1821 if( loop->_next ) fix_parent( loop->_next , parent );
1822 }
1823
1824 //------------------------------estimate_path_freq-----------------------------
1825 static float estimate_path_freq( Node *n ) {
1826 // Try to extract some path frequency info
1827 IfNode *iff;
1828 for( int i = 0; i < 50; i++ ) { // Skip through a bunch of uncommon tests
1829 uint nop = n->Opcode();
1830 if( nop == Op_SafePoint ) { // Skip any safepoint
1831 n = n->in(0);
1832 continue;
1833 }
1834 if( nop == Op_CatchProj ) { // Get count from a prior call
1835 // Assume call does not always throw exceptions: means the call-site
1836 // count is also the frequency of the fall-through path.
1837 assert( n->is_CatchProj(), "" );
1838 if( ((CatchProjNode*)n)->_con != CatchProjNode::fall_through_index )
1839 return 0.0f; // Assume call exception path is rare
1840 Node *call = n->in(0)->in(0)->in(0);
1841 assert( call->is_Call(), "expect a call here" );
1842 const JVMState *jvms = ((CallNode*)call)->jvms();
1843 ciMethodData* methodData = jvms->method()->method_data();
1844 if (!methodData->is_mature()) return 0.0f; // No call-site data
1845 ciProfileData* data = methodData->bci_to_data(jvms->bci());
1846 if ((data == NULL) || !data->is_CounterData()) {
1847 // no call profile available, try call's control input
1848 n = n->in(0);
1849 continue;
1850 }
1851 return data->as_CounterData()->count()/FreqCountInvocations;
1852 }
1853 // See if there's a gating IF test
1854 Node *n_c = n->in(0);
1855 if( !n_c->is_If() ) break; // No estimate available
1856 iff = n_c->as_If();
1857 if( iff->_fcnt != COUNT_UNKNOWN ) // Have a valid count?
1858 // Compute how much count comes on this path
1859 return ((nop == Op_IfTrue) ? iff->_prob : 1.0f - iff->_prob) * iff->_fcnt;
1860 // Have no count info. Skip dull uncommon-trap like branches.
1861 if( (nop == Op_IfTrue && iff->_prob < PROB_LIKELY_MAG(5)) ||
1862 (nop == Op_IfFalse && iff->_prob > PROB_UNLIKELY_MAG(5)) )
1863 break;
1864 // Skip through never-taken branch; look for a real loop exit.
1865 n = iff->in(0);
1866 }
1867 return 0.0f; // No estimate available
1868 }
1869
1870 //------------------------------merge_many_backedges---------------------------
1871 // Merge all the backedges from the shared header into a private Region.
1872 // Feed that region as the one backedge to this loop.
1873 void IdealLoopTree::merge_many_backedges( PhaseIdealLoop *phase ) {
1874 uint i;
1875
1876 // Scan for the top 2 hottest backedges
1877 float hotcnt = 0.0f;
1878 float warmcnt = 0.0f;
1879 uint hot_idx = 0;
1880 // Loop starts at 2 because slot 1 is the fall-in path
1881 for( i = 2; i < _head->req(); i++ ) {
1882 float cnt = estimate_path_freq(_head->in(i));
1883 if( cnt > hotcnt ) { // Grab hottest path
1884 warmcnt = hotcnt;
1885 hotcnt = cnt;
1886 hot_idx = i;
1887 } else if( cnt > warmcnt ) { // And 2nd hottest path
1888 warmcnt = cnt;
1889 }
1890 }
1891
1892 // See if the hottest backedge is worthy of being an inner loop
1893 // by being much hotter than the next hottest backedge.
1894 if( hotcnt <= 0.0001 ||
1895 hotcnt < 2.0*warmcnt ) hot_idx = 0;// No hot backedge
1896
1897 // Peel out the backedges into a private merge point; peel
1898 // them all except optionally hot_idx.
1899 PhaseIterGVN &igvn = phase->_igvn;
1900
1901 Node *hot_tail = NULL;
1902 // Make a Region for the merge point
1903 Node *r = new RegionNode(1);
1904 for( i = 2; i < _head->req(); i++ ) {
1905 if( i != hot_idx )
1906 r->add_req( _head->in(i) );
1907 else hot_tail = _head->in(i);
1908 }
1909 igvn.register_new_node_with_optimizer(r, _head);
1910 // Plug region into end of loop _head, followed by hot_tail
1911 while( _head->req() > 3 ) _head->del_req( _head->req()-1 );
1912 igvn.replace_input_of(_head, 2, r);
1913 if( hot_idx ) _head->add_req(hot_tail);
1914
1915 // Split all the Phis up between '_head' loop and the Region 'r'
1916 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1917 Node *out = _head->fast_out(j);
1918 if( out->is_Phi() ) {
1919 PhiNode* n = out->as_Phi();
1920 igvn.hash_delete(n); // Delete from hash before hacking edges
1921 Node *hot_phi = NULL;
1922 Node *phi = new PhiNode(r, n->type(), n->adr_type());
1923 // Check all inputs for the ones to peel out
1924 uint j = 1;
1925 for( uint i = 2; i < n->req(); i++ ) {
1926 if( i != hot_idx )
1927 phi->set_req( j++, n->in(i) );
1928 else hot_phi = n->in(i);
1929 }
1930 // Register the phi but do not transform until whole place transforms
1931 igvn.register_new_node_with_optimizer(phi, n);
1932 // Add the merge phi to the old Phi
1933 while( n->req() > 3 ) n->del_req( n->req()-1 );
1934 igvn.replace_input_of(n, 2, phi);
1935 if( hot_idx ) n->add_req(hot_phi);
1936 }
1937 }
1938
1939
1940 // Insert a new IdealLoopTree inserted below me. Turn it into a clone
1941 // of self loop tree. Turn self into a loop headed by _head and with
1942 // tail being the new merge point.
1943 IdealLoopTree *ilt = new IdealLoopTree( phase, _head, _tail );
1944 phase->set_loop(_tail,ilt); // Adjust tail
1945 _tail = r; // Self's tail is new merge point
1946 phase->set_loop(r,this);
1947 ilt->_child = _child; // New guy has my children
1948 _child = ilt; // Self has new guy as only child
1949 ilt->_parent = this; // new guy has self for parent
1950 ilt->_nest = _nest; // Same nesting depth (for now)
1951
1952 // Starting with 'ilt', look for child loop trees using the same shared
1953 // header. Flatten these out; they will no longer be loops in the end.
1954 IdealLoopTree **pilt = &_child;
1955 while( ilt ) {
1956 if( ilt->_head == _head ) {
1957 uint i;
1958 for( i = 2; i < _head->req(); i++ )
1959 if( _head->in(i) == ilt->_tail )
1960 break; // Still a loop
1961 if( i == _head->req() ) { // No longer a loop
1962 // Flatten ilt. Hang ilt's "_next" list from the end of
1963 // ilt's '_child' list. Move the ilt's _child up to replace ilt.
1964 IdealLoopTree **cp = &ilt->_child;
1965 while( *cp ) cp = &(*cp)->_next; // Find end of child list
1966 *cp = ilt->_next; // Hang next list at end of child list
1967 *pilt = ilt->_child; // Move child up to replace ilt
1968 ilt->_head = NULL; // Flag as a loop UNIONED into parent
1969 ilt = ilt->_child; // Repeat using new ilt
1970 continue; // do not advance over ilt->_child
1971 }
1972 assert( ilt->_tail == hot_tail, "expected to only find the hot inner loop here" );
1973 phase->set_loop(_head,ilt);
1974 }
1975 pilt = &ilt->_child; // Advance to next
1976 ilt = *pilt;
1977 }
1978
1979 if( _child ) fix_parent( _child, this );
1980 }
1981
1982 //------------------------------beautify_loops---------------------------------
1983 // Split shared headers and insert loop landing pads.
1984 // Insert a LoopNode to replace the RegionNode.
1985 // Return TRUE if loop tree is structurally changed.
1986 bool IdealLoopTree::beautify_loops( PhaseIdealLoop *phase ) {
1987 bool result = false;
1988 // Cache parts in locals for easy
1989 PhaseIterGVN &igvn = phase->_igvn;
1990
1991 igvn.hash_delete(_head); // Yank from hash before hacking edges
1992
1993 // Check for multiple fall-in paths. Peel off a landing pad if need be.
1994 int fall_in_cnt = 0;
1995 for( uint i = 1; i < _head->req(); i++ )
1996 if( !phase->is_member( this, _head->in(i) ) )
1997 fall_in_cnt++;
1998 assert( fall_in_cnt, "at least 1 fall-in path" );
1999 if( fall_in_cnt > 1 ) // Need a loop landing pad to merge fall-ins
2000 split_fall_in( phase, fall_in_cnt );
2001
2002 // Swap inputs to the _head and all Phis to move the fall-in edge to
2003 // the left.
2004 fall_in_cnt = 1;
2005 while( phase->is_member( this, _head->in(fall_in_cnt) ) )
2006 fall_in_cnt++;
2007 if( fall_in_cnt > 1 ) {
2008 // Since I am just swapping inputs I do not need to update def-use info
2009 Node *tmp = _head->in(1);
2010 igvn.rehash_node_delayed(_head);
2011 _head->set_req( 1, _head->in(fall_in_cnt) );
2012 _head->set_req( fall_in_cnt, tmp );
2013 // Swap also all Phis
2014 for (DUIterator_Fast imax, i = _head->fast_outs(imax); i < imax; i++) {
2015 Node* phi = _head->fast_out(i);
2016 if( phi->is_Phi() ) {
2017 igvn.rehash_node_delayed(phi); // Yank from hash before hacking edges
2018 tmp = phi->in(1);
2019 phi->set_req( 1, phi->in(fall_in_cnt) );
2020 phi->set_req( fall_in_cnt, tmp );
2021 }
2022 }
2023 }
2024 assert( !phase->is_member( this, _head->in(1) ), "left edge is fall-in" );
2025 assert( phase->is_member( this, _head->in(2) ), "right edge is loop" );
2026
2027 // If I am a shared header (multiple backedges), peel off the many
2028 // backedges into a private merge point and use the merge point as
2029 // the one true backedge.
2030 if( _head->req() > 3 ) {
2031 // Merge the many backedges into a single backedge but leave
2032 // the hottest backedge as separate edge for the following peel.
2033 merge_many_backedges( phase );
2034 result = true;
2035 }
2036
2037 // If I have one hot backedge, peel off myself loop.
2038 // I better be the outermost loop.
2039 if (_head->req() > 3 && !_irreducible) {
2040 split_outer_loop( phase );
2041 result = true;
2042
2043 } else if (!_head->is_Loop() && !_irreducible) {
2044 // Make a new LoopNode to replace the old loop head
2045 Node *l = new LoopNode( _head->in(1), _head->in(2) );
2046 l = igvn.register_new_node_with_optimizer(l, _head);
2047 phase->set_created_loop_node();
2048 // Go ahead and replace _head
2049 phase->_igvn.replace_node( _head, l );
2050 _head = l;
2051 phase->set_loop(_head, this);
2052 }
2053
2054 // Now recursively beautify nested loops
2055 if( _child ) result |= _child->beautify_loops( phase );
2056 if( _next ) result |= _next ->beautify_loops( phase );
2057 return result;
2058 }
2059
2060 //------------------------------allpaths_check_safepts----------------------------
2061 // Allpaths backwards scan from loop tail, terminating each path at first safepoint
2062 // encountered. Helper for check_safepts.
2063 void IdealLoopTree::allpaths_check_safepts(VectorSet &visited, Node_List &stack) {
2064 assert(stack.size() == 0, "empty stack");
2065 stack.push(_tail);
2066 visited.Clear();
2067 visited.set(_tail->_idx);
2068 while (stack.size() > 0) {
2069 Node* n = stack.pop();
2070 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
2071 // Terminate this path
2072 } else if (n->Opcode() == Op_SafePoint) {
2073 if (_phase->get_loop(n) != this) {
2074 if (_required_safept == NULL) _required_safept = new Node_List();
2075 _required_safept->push(n); // save the one closest to the tail
2076 }
2077 // Terminate this path
2078 } else {
2079 uint start = n->is_Region() ? 1 : 0;
2080 uint end = n->is_Region() && !n->is_Loop() ? n->req() : start + 1;
2081 for (uint i = start; i < end; i++) {
2082 Node* in = n->in(i);
2083 assert(in->is_CFG(), "must be");
2084 if (!visited.test_set(in->_idx) && is_member(_phase->get_loop(in))) {
2085 stack.push(in);
2086 }
2087 }
2088 }
2089 }
2090 }
2091
2092 //------------------------------check_safepts----------------------------
2093 // Given dominators, try to find loops with calls that must always be
2094 // executed (call dominates loop tail). These loops do not need non-call
2095 // safepoints (ncsfpt).
2096 //
2097 // A complication is that a safepoint in a inner loop may be needed
2098 // by an outer loop. In the following, the inner loop sees it has a
2099 // call (block 3) on every path from the head (block 2) to the
2100 // backedge (arc 3->2). So it deletes the ncsfpt (non-call safepoint)
2101 // in block 2, _but_ this leaves the outer loop without a safepoint.
2102 //
2103 // entry 0
2104 // |
2105 // v
2106 // outer 1,2 +->1
2107 // | |
2108 // | v
2109 // | 2<---+ ncsfpt in 2
2110 // |_/|\ |
2111 // | v |
2112 // inner 2,3 / 3 | call in 3
2113 // / | |
2114 // v +--+
2115 // exit 4
2116 //
2117 //
2118 // This method creates a list (_required_safept) of ncsfpt nodes that must
2119 // be protected is created for each loop. When a ncsfpt maybe deleted, it
2120 // is first looked for in the lists for the outer loops of the current loop.
2121 //
2122 // The insights into the problem:
2123 // A) counted loops are okay
2124 // B) innermost loops are okay (only an inner loop can delete
2125 // a ncsfpt needed by an outer loop)
2126 // C) a loop is immune from an inner loop deleting a safepoint
2127 // if the loop has a call on the idom-path
2128 // D) a loop is also immune if it has a ncsfpt (non-call safepoint) on the
2129 // idom-path that is not in a nested loop
2130 // E) otherwise, an ncsfpt on the idom-path that is nested in an inner
2131 // loop needs to be prevented from deletion by an inner loop
2132 //
2133 // There are two analyses:
2134 // 1) The first, and cheaper one, scans the loop body from
2135 // tail to head following the idom (immediate dominator)
2136 // chain, looking for the cases (C,D,E) above.
2137 // Since inner loops are scanned before outer loops, there is summary
2138 // information about inner loops. Inner loops can be skipped over
2139 // when the tail of an inner loop is encountered.
2140 //
2141 // 2) The second, invoked if the first fails to find a call or ncsfpt on
2142 // the idom path (which is rare), scans all predecessor control paths
2143 // from the tail to the head, terminating a path when a call or sfpt
2144 // is encountered, to find the ncsfpt's that are closest to the tail.
2145 //
2146 void IdealLoopTree::check_safepts(VectorSet &visited, Node_List &stack) {
2147 // Bottom up traversal
2148 IdealLoopTree* ch = _child;
2149 if (_child) _child->check_safepts(visited, stack);
2150 if (_next) _next ->check_safepts(visited, stack);
2151
2152 if (!_head->is_CountedLoop() && !_has_sfpt && _parent != NULL && !_irreducible) {
2153 bool has_call = false; // call on dom-path
2154 bool has_local_ncsfpt = false; // ncsfpt on dom-path at this loop depth
2155 Node* nonlocal_ncsfpt = NULL; // ncsfpt on dom-path at a deeper depth
2156 // Scan the dom-path nodes from tail to head
2157 for (Node* n = tail(); n != _head; n = _phase->idom(n)) {
2158 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
2159 has_call = true;
2160 _has_sfpt = 1; // Then no need for a safept!
2161 break;
2162 } else if (n->Opcode() == Op_SafePoint) {
2163 if (_phase->get_loop(n) == this) {
2164 has_local_ncsfpt = true;
2165 break;
2166 }
2167 if (nonlocal_ncsfpt == NULL) {
2168 nonlocal_ncsfpt = n; // save the one closest to the tail
2169 }
2170 } else {
2171 IdealLoopTree* nlpt = _phase->get_loop(n);
2172 if (this != nlpt) {
2173 // If at an inner loop tail, see if the inner loop has already
2174 // recorded seeing a call on the dom-path (and stop.) If not,
2175 // jump to the head of the inner loop.
2176 assert(is_member(nlpt), "nested loop");
2177 Node* tail = nlpt->_tail;
2178 if (tail->in(0)->is_If()) tail = tail->in(0);
2179 if (n == tail) {
2180 // If inner loop has call on dom-path, so does outer loop
2181 if (nlpt->_has_sfpt) {
2182 has_call = true;
2183 _has_sfpt = 1;
2184 break;
2185 }
2186 // Skip to head of inner loop
2187 assert(_phase->is_dominator(_head, nlpt->_head), "inner head dominated by outer head");
2188 n = nlpt->_head;
2189 }
2190 }
2191 }
2192 }
2193 // Record safept's that this loop needs preserved when an
2194 // inner loop attempts to delete it's safepoints.
2195 if (_child != NULL && !has_call && !has_local_ncsfpt) {
2196 if (nonlocal_ncsfpt != NULL) {
2197 if (_required_safept == NULL) _required_safept = new Node_List();
2198 _required_safept->push(nonlocal_ncsfpt);
2199 } else {
2200 // Failed to find a suitable safept on the dom-path. Now use
2201 // an all paths walk from tail to head, looking for safepoints to preserve.
2202 allpaths_check_safepts(visited, stack);
2203 }
2204 }
2205 }
2206 }
2207
2208 //---------------------------is_deleteable_safept----------------------------
2209 // Is safept not required by an outer loop?
2210 bool PhaseIdealLoop::is_deleteable_safept(Node* sfpt) {
2211 assert(sfpt->Opcode() == Op_SafePoint, "");
2212 IdealLoopTree* lp = get_loop(sfpt)->_parent;
2213 while (lp != NULL) {
2214 Node_List* sfpts = lp->_required_safept;
2215 if (sfpts != NULL) {
2216 for (uint i = 0; i < sfpts->size(); i++) {
2217 if (sfpt == sfpts->at(i))
2218 return false;
2219 }
2220 }
2221 lp = lp->_parent;
2222 }
2223 return true;
2224 }
2225
2226 //---------------------------replace_parallel_iv-------------------------------
2227 // Replace parallel induction variable (parallel to trip counter)
2228 void PhaseIdealLoop::replace_parallel_iv(IdealLoopTree *loop) {
2229 assert(loop->_head->is_CountedLoop(), "");
2230 CountedLoopNode *cl = loop->_head->as_CountedLoop();
2231 if (!cl->is_valid_counted_loop())
2232 return; // skip malformed counted loop
2233 Node *incr = cl->incr();
2234 if (incr == NULL)
2235 return; // Dead loop?
2236 Node *init = cl->init_trip();
2237 Node *phi = cl->phi();
2238 int stride_con = cl->stride_con();
2239
2240 // Visit all children, looking for Phis
2241 for (DUIterator i = cl->outs(); cl->has_out(i); i++) {
2242 Node *out = cl->out(i);
2243 // Look for other phis (secondary IVs). Skip dead ones
2244 if (!out->is_Phi() || out == phi || !has_node(out))
2245 continue;
2246 PhiNode* phi2 = out->as_Phi();
2247 Node *incr2 = phi2->in( LoopNode::LoopBackControl );
2248 // Look for induction variables of the form: X += constant
2249 if (phi2->region() != loop->_head ||
2250 incr2->req() != 3 ||
2251 incr2->in(1) != phi2 ||
2252 incr2 == incr ||
2253 incr2->Opcode() != Op_AddI ||
2254 !incr2->in(2)->is_Con())
2255 continue;
2256
2257 // Check for parallel induction variable (parallel to trip counter)
2258 // via an affine function. In particular, count-down loops with
2259 // count-up array indices are common. We only RCE references off
2260 // the trip-counter, so we need to convert all these to trip-counter
2261 // expressions.
2262 Node *init2 = phi2->in( LoopNode::EntryControl );
2263 int stride_con2 = incr2->in(2)->get_int();
2264
2265 // The ratio of the two strides cannot be represented as an int
2266 // if stride_con2 is min_int and stride_con is -1.
2267 if (stride_con2 == min_jint && stride_con == -1) {
2268 continue;
2269 }
2270
2271 // The general case here gets a little tricky. We want to find the
2272 // GCD of all possible parallel IV's and make a new IV using this
2273 // GCD for the loop. Then all possible IVs are simple multiples of
2274 // the GCD. In practice, this will cover very few extra loops.
2275 // Instead we require 'stride_con2' to be a multiple of 'stride_con',
2276 // where +/-1 is the common case, but other integer multiples are
2277 // also easy to handle.
2278 int ratio_con = stride_con2/stride_con;
2279
2280 if ((ratio_con * stride_con) == stride_con2) { // Check for exact
2281 #ifndef PRODUCT
2282 if (TraceLoopOpts) {
2283 tty->print("Parallel IV: %d ", phi2->_idx);
2284 loop->dump_head();
2285 }
2286 #endif
2287 // Convert to using the trip counter. The parallel induction
2288 // variable differs from the trip counter by a loop-invariant
2289 // amount, the difference between their respective initial values.
2290 // It is scaled by the 'ratio_con'.
2291 Node* ratio = _igvn.intcon(ratio_con);
2292 set_ctrl(ratio, C->root());
2293 Node* ratio_init = new MulINode(init, ratio);
2294 _igvn.register_new_node_with_optimizer(ratio_init, init);
2295 set_early_ctrl(ratio_init);
2296 Node* diff = new SubINode(init2, ratio_init);
2297 _igvn.register_new_node_with_optimizer(diff, init2);
2298 set_early_ctrl(diff);
2299 Node* ratio_idx = new MulINode(phi, ratio);
2300 _igvn.register_new_node_with_optimizer(ratio_idx, phi);
2301 set_ctrl(ratio_idx, cl);
2302 Node* add = new AddINode(ratio_idx, diff);
2303 _igvn.register_new_node_with_optimizer(add);
2304 set_ctrl(add, cl);
2305 _igvn.replace_node( phi2, add );
2306 // Sometimes an induction variable is unused
2307 if (add->outcnt() == 0) {
2308 _igvn.remove_dead_node(add);
2309 }
2310 --i; // deleted this phi; rescan starting with next position
2311 continue;
2312 }
2313 }
2314 }
2315
2316 void IdealLoopTree::remove_safepoints(PhaseIdealLoop* phase, bool keep_one) {
2317 Node* keep = NULL;
2318 if (keep_one) {
2319 // Look for a safepoint on the idom-path.
2320 for (Node* i = tail(); i != _head; i = phase->idom(i)) {
2321 if (i->Opcode() == Op_SafePoint && phase->get_loop(i) == this) {
2322 keep = i;
2323 break; // Found one
2324 }
2325 }
2326 }
2327
2328 // Don't remove any safepoints if it is requested to keep a single safepoint and
2329 // no safepoint was found on idom-path. It is not safe to remove any safepoint
2330 // in this case since there's no safepoint dominating all paths in the loop body.
2331 bool prune = !keep_one || keep != NULL;
2332
2333 // Delete other safepoints in this loop.
2334 Node_List* sfpts = _safepts;
2335 if (prune && sfpts != NULL) {
2336 assert(keep == NULL || keep->Opcode() == Op_SafePoint, "not safepoint");
2337 for (uint i = 0; i < sfpts->size(); i++) {
2338 Node* n = sfpts->at(i);
2339 assert(phase->get_loop(n) == this, "");
2340 if (n != keep && phase->is_deleteable_safept(n)) {
2341 phase->lazy_replace(n, n->in(TypeFunc::Control));
2342 }
2343 }
2344 }
2345 }
2346
2347 //------------------------------counted_loop-----------------------------------
2348 // Convert to counted loops where possible
2349 void IdealLoopTree::counted_loop( PhaseIdealLoop *phase ) {
2350
2351 // For grins, set the inner-loop flag here
2352 if (!_child) {
2353 if (_head->is_Loop()) _head->as_Loop()->set_inner_loop();
2354 }
2355
2356 IdealLoopTree* loop = this;
2357 if (_head->is_CountedLoop() ||
2358 phase->is_counted_loop(_head, loop)) {
2359
2360 if (LoopStripMiningIter == 0 || (LoopStripMiningIter > 1 && _child == NULL)) {
2361 // Indicate we do not need a safepoint here
2362 _has_sfpt = 1;
2363 }
2364
2365 // Remove safepoints
2366 bool keep_one_sfpt = !(_has_call || _has_sfpt);
2367 remove_safepoints(phase, keep_one_sfpt);
2368
2369 // Look for induction variables
2370 phase->replace_parallel_iv(this);
2371
2372 } else if (_parent != NULL && !_irreducible) {
2373 // Not a counted loop. Keep one safepoint.
2374 bool keep_one_sfpt = true;
2375 remove_safepoints(phase, keep_one_sfpt);
2376 }
2377
2378 // Recursively
2379 assert(loop->_child != this || (loop->_head->as_Loop()->is_OuterStripMinedLoop() && _head->as_CountedLoop()->is_strip_mined()), "what kind of loop was added?");
2380 assert(loop->_child != this || (loop->_child->_child == NULL && loop->_child->_next == NULL), "would miss some loops");
2381 if (loop->_child && loop->_child != this) loop->_child->counted_loop(phase);
2382 if (loop->_next) loop->_next ->counted_loop(phase);
2383 }
2384
2385 #ifndef PRODUCT
2386 //------------------------------dump_head--------------------------------------
2387 // Dump 1 liner for loop header info
2388 void IdealLoopTree::dump_head( ) const {
2389 for (uint i=0; i<_nest; i++)
2390 tty->print(" ");
2391 tty->print("Loop: N%d/N%d ",_head->_idx,_tail->_idx);
2392 if (_irreducible) tty->print(" IRREDUCIBLE");
2393 Node* entry = _head->is_Loop() ? _head->as_Loop()->skip_strip_mined(-1)->in(LoopNode::EntryControl) : _head->in(LoopNode::EntryControl);
2394 Node* predicate = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
2395 if (predicate != NULL ) {
2396 tty->print(" limit_check");
2397 entry = entry->in(0)->in(0);
2398 }
2399 if (UseLoopPredicate) {
2400 entry = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
2401 if (entry != NULL) {
2402 tty->print(" predicated");
2403 }
2404 }
2405 if (_head->is_CountedLoop()) {
2406 CountedLoopNode *cl = _head->as_CountedLoop();
2407 tty->print(" counted");
2408
2409 Node* init_n = cl->init_trip();
2410 if (init_n != NULL && init_n->is_Con())
2411 tty->print(" [%d,", cl->init_trip()->get_int());
2412 else
2413 tty->print(" [int,");
2414 Node* limit_n = cl->limit();
2415 if (limit_n != NULL && limit_n->is_Con())
2416 tty->print("%d),", cl->limit()->get_int());
2417 else
2418 tty->print("int),");
2419 int stride_con = cl->stride_con();
2420 if (stride_con > 0) tty->print("+");
2421 tty->print("%d", stride_con);
2422
2423 tty->print(" (%0.f iters) ", cl->profile_trip_cnt());
2424
2425 if (cl->is_pre_loop ()) tty->print(" pre" );
2426 if (cl->is_main_loop()) tty->print(" main");
2427 if (cl->is_post_loop()) tty->print(" post");
2428 if (cl->is_vectorized_loop()) tty->print(" vector");
2429 if (cl->range_checks_present()) tty->print(" rc ");
2430 if (cl->is_multiversioned()) tty->print(" multi ");
2431 }
2432 if (_has_call) tty->print(" has_call");
2433 if (_has_sfpt) tty->print(" has_sfpt");
2434 if (_rce_candidate) tty->print(" rce");
2435 if (_safepts != NULL && _safepts->size() > 0) {
2436 tty->print(" sfpts={"); _safepts->dump_simple(); tty->print(" }");
2437 }
2438 if (_required_safept != NULL && _required_safept->size() > 0) {
2439 tty->print(" req={"); _required_safept->dump_simple(); tty->print(" }");
2440 }
2441 if (Verbose) {
2442 tty->print(" body={"); _body.dump_simple(); tty->print(" }");
2443 }
2444 if (_head->is_Loop() && _head->as_Loop()->is_strip_mined()) {
2445 tty->print(" strip_mined");
2446 }
2447 tty->cr();
2448 }
2449
2450 //------------------------------dump-------------------------------------------
2451 // Dump loops by loop tree
2452 void IdealLoopTree::dump( ) const {
2453 dump_head();
2454 if (_child) _child->dump();
2455 if (_next) _next ->dump();
2456 }
2457
2458 #endif
2459
2460 static void log_loop_tree(IdealLoopTree* root, IdealLoopTree* loop, CompileLog* log) {
2461 if (loop == root) {
2462 if (loop->_child != NULL) {
2463 log->begin_head("loop_tree");
2464 log->end_head();
2465 if( loop->_child ) log_loop_tree(root, loop->_child, log);
2466 log->tail("loop_tree");
2467 assert(loop->_next == NULL, "what?");
2468 }
2469 } else {
2470 Node* head = loop->_head;
2471 log->begin_head("loop");
2472 log->print(" idx='%d' ", head->_idx);
2473 if (loop->_irreducible) log->print("irreducible='1' ");
2474 if (head->is_Loop()) {
2475 if (head->as_Loop()->is_inner_loop()) log->print("inner_loop='1' ");
2476 if (head->as_Loop()->is_partial_peel_loop()) log->print("partial_peel_loop='1' ");
2477 }
2478 if (head->is_CountedLoop()) {
2479 CountedLoopNode* cl = head->as_CountedLoop();
2480 if (cl->is_pre_loop()) log->print("pre_loop='%d' ", cl->main_idx());
2481 if (cl->is_main_loop()) log->print("main_loop='%d' ", cl->_idx);
2482 if (cl->is_post_loop()) log->print("post_loop='%d' ", cl->main_idx());
2483 }
2484 log->end_head();
2485 if( loop->_child ) log_loop_tree(root, loop->_child, log);
2486 log->tail("loop");
2487 if( loop->_next ) log_loop_tree(root, loop->_next, log);
2488 }
2489 }
2490
2491 //---------------------collect_potentially_useful_predicates-----------------------
2492 // Helper function to collect potentially useful predicates to prevent them from
2493 // being eliminated by PhaseIdealLoop::eliminate_useless_predicates
2494 void PhaseIdealLoop::collect_potentially_useful_predicates(
2495 IdealLoopTree * loop, Unique_Node_List &useful_predicates) {
2496 if (loop->_child) { // child
2497 collect_potentially_useful_predicates(loop->_child, useful_predicates);
2498 }
2499
2500 // self (only loops that we can apply loop predication may use their predicates)
2501 if (loop->_head->is_Loop() &&
2502 !loop->_irreducible &&
2503 !loop->tail()->is_top()) {
2504 LoopNode* lpn = loop->_head->as_Loop();
2505 Node* entry = lpn->in(LoopNode::EntryControl);
2506 Node* predicate_proj = find_predicate(entry); // loop_limit_check first
2507 if (predicate_proj != NULL ) { // right pattern that can be used by loop predication
2508 assert(entry->in(0)->in(1)->in(1)->Opcode() == Op_Opaque1, "must be");
2509 useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one
2510 entry = entry->in(0)->in(0);
2511 }
2512 predicate_proj = find_predicate(entry); // Predicate
2513 if (predicate_proj != NULL ) {
2514 useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one
2515 }
2516 }
2517
2518 if (loop->_next) { // sibling
2519 collect_potentially_useful_predicates(loop->_next, useful_predicates);
2520 }
2521 }
2522
2523 //------------------------eliminate_useless_predicates-----------------------------
2524 // Eliminate all inserted predicates if they could not be used by loop predication.
2525 // Note: it will also eliminates loop limits check predicate since it also uses
2526 // Opaque1 node (see Parse::add_predicate()).
2527 void PhaseIdealLoop::eliminate_useless_predicates() {
2528 if (C->predicate_count() == 0)
2529 return; // no predicate left
2530
2531 Unique_Node_List useful_predicates; // to store useful predicates
2532 if (C->has_loops()) {
2533 collect_potentially_useful_predicates(_ltree_root->_child, useful_predicates);
2534 }
2535
2536 for (int i = C->predicate_count(); i > 0; i--) {
2537 Node * n = C->predicate_opaque1_node(i-1);
2538 assert(n->Opcode() == Op_Opaque1, "must be");
2539 if (!useful_predicates.member(n)) { // not in the useful list
2540 _igvn.replace_node(n, n->in(1));
2541 }
2542 }
2543 }
2544
2545 //------------------------process_expensive_nodes-----------------------------
2546 // Expensive nodes have their control input set to prevent the GVN
2547 // from commoning them and as a result forcing the resulting node to
2548 // be in a more frequent path. Use CFG information here, to change the
2549 // control inputs so that some expensive nodes can be commoned while
2550 // not executed more frequently.
2551 bool PhaseIdealLoop::process_expensive_nodes() {
2552 assert(OptimizeExpensiveOps, "optimization off?");
2553
2554 // Sort nodes to bring similar nodes together
2555 C->sort_expensive_nodes();
2556
2557 bool progress = false;
2558
2559 for (int i = 0; i < C->expensive_count(); ) {
2560 Node* n = C->expensive_node(i);
2561 int start = i;
2562 // Find nodes similar to n
2563 i++;
2564 for (; i < C->expensive_count() && Compile::cmp_expensive_nodes(n, C->expensive_node(i)) == 0; i++);
2565 int end = i;
2566 // And compare them two by two
2567 for (int j = start; j < end; j++) {
2568 Node* n1 = C->expensive_node(j);
2569 if (is_node_unreachable(n1)) {
2570 continue;
2571 }
2572 for (int k = j+1; k < end; k++) {
2573 Node* n2 = C->expensive_node(k);
2574 if (is_node_unreachable(n2)) {
2575 continue;
2576 }
2577
2578 assert(n1 != n2, "should be pair of nodes");
2579
2580 Node* c1 = n1->in(0);
2581 Node* c2 = n2->in(0);
2582
2583 Node* parent_c1 = c1;
2584 Node* parent_c2 = c2;
2585
2586 // The call to get_early_ctrl_for_expensive() moves the
2587 // expensive nodes up but stops at loops that are in a if
2588 // branch. See whether we can exit the loop and move above the
2589 // If.
2590 if (c1->is_Loop()) {
2591 parent_c1 = c1->in(1);
2592 }
2593 if (c2->is_Loop()) {
2594 parent_c2 = c2->in(1);
2595 }
2596
2597 if (parent_c1 == parent_c2) {
2598 _igvn._worklist.push(n1);
2599 _igvn._worklist.push(n2);
2600 continue;
2601 }
2602
2603 // Look for identical expensive node up the dominator chain.
2604 if (is_dominator(c1, c2)) {
2605 c2 = c1;
2606 } else if (is_dominator(c2, c1)) {
2607 c1 = c2;
2608 } else if (parent_c1->is_Proj() && parent_c1->in(0)->is_If() &&
2609 parent_c2->is_Proj() && parent_c1->in(0) == parent_c2->in(0)) {
2610 // Both branches have the same expensive node so move it up
2611 // before the if.
2612 c1 = c2 = idom(parent_c1->in(0));
2613 }
2614 // Do the actual moves
2615 if (n1->in(0) != c1) {
2616 _igvn.hash_delete(n1);
2617 n1->set_req(0, c1);
2618 _igvn.hash_insert(n1);
2619 _igvn._worklist.push(n1);
2620 progress = true;
2621 }
2622 if (n2->in(0) != c2) {
2623 _igvn.hash_delete(n2);
2624 n2->set_req(0, c2);
2625 _igvn.hash_insert(n2);
2626 _igvn._worklist.push(n2);
2627 progress = true;
2628 }
2629 }
2630 }
2631 }
2632
2633 return progress;
2634 }
2635
2636
2637 //=============================================================================
2638 //----------------------------build_and_optimize-------------------------------
2639 // Create a PhaseLoop. Build the ideal Loop tree. Map each Ideal Node to
2640 // its corresponding LoopNode. If 'optimize' is true, do some loop cleanups.
2641 void PhaseIdealLoop::build_and_optimize(bool do_split_ifs, bool skip_loop_opts, bool last_round) {
2642 ResourceMark rm;
2643
2644 int old_progress = C->major_progress();
2645 uint orig_worklist_size = _igvn._worklist.size();
2646
2647 #ifndef PRODUCT
2648 // Capture for later assert
2649 uint unique = C->unique();
2650 _loop_invokes++;
2651 _loop_work += unique;
2652 #endif
2653
2654 // True if the method has at least 1 irreducible loop
2655 _has_irreducible_loops = false;
2656
2657 _created_loop_node = false;
2658
2659 Arena *a = Thread::current()->resource_area();
2660 VectorSet visited(a);
2661 // Pre-grow the mapping from Nodes to IdealLoopTrees.
2662 _nodes.map(C->unique(), NULL);
2663 memset(_nodes.adr(), 0, wordSize * C->unique());
2664
2665 // Pre-build the top-level outermost loop tree entry
2666 _ltree_root = new IdealLoopTree( this, C->root(), C->root() );
2667 // Do not need a safepoint at the top level
2668 _ltree_root->_has_sfpt = 1;
2669
2670 // Initialize Dominators.
2671 // Checked in clone_loop_predicate() during beautify_loops().
2672 _idom_size = 0;
2673 _idom = NULL;
2674 _dom_depth = NULL;
2675 _dom_stk = NULL;
2676
2677 // Empty pre-order array
2678 allocate_preorders();
2679
2680 // Build a loop tree on the fly. Build a mapping from CFG nodes to
2681 // IdealLoopTree entries. Data nodes are NOT walked.
2682 build_loop_tree();
2683 // Check for bailout, and return
2684 if (C->failing()) {
2685 return;
2686 }
2687
2688 // No loops after all
2689 if( !_ltree_root->_child && !_verify_only ) C->set_has_loops(false);
2690
2691 // There should always be an outer loop containing the Root and Return nodes.
2692 // If not, we have a degenerate empty program. Bail out in this case.
2693 if (!has_node(C->root())) {
2694 if (!_verify_only) {
2695 C->clear_major_progress();
2696 C->record_method_not_compilable("empty program detected during loop optimization");
2697 }
2698 return;
2699 }
2700
2701 // Nothing to do, so get out
2702 bool stop_early = !C->has_loops() && !skip_loop_opts && !do_split_ifs && !_verify_me && !_verify_only;
2703 bool do_expensive_nodes = C->should_optimize_expensive_nodes(_igvn);
2704 if (stop_early && !do_expensive_nodes) {
2705 _igvn.optimize(); // Cleanup NeverBranches
2706 return;
2707 }
2708
2709 // Set loop nesting depth
2710 _ltree_root->set_nest( 0 );
2711
2712 // Split shared headers and insert loop landing pads.
2713 // Do not bother doing this on the Root loop of course.
2714 if( !_verify_me && !_verify_only && _ltree_root->_child ) {
2715 C->print_method(PHASE_BEFORE_BEAUTIFY_LOOPS, 3);
2716 if( _ltree_root->_child->beautify_loops( this ) ) {
2717 // IdealLoopTree::split_outer_loop may produce phi-nodes with a single in edge.
2718 // Transform them away.
2719 _igvn.optimize();
2720
2721 // Re-build loop tree!
2722 _ltree_root->_child = NULL;
2723 _nodes.clear();
2724 reallocate_preorders();
2725 build_loop_tree();
2726
2727 // Check for bailout, and return
2728 if (C->failing()) {
2729 return;
2730 }
2731 // Reset loop nesting depth
2732 _ltree_root->set_nest( 0 );
2733
2734 C->print_method(PHASE_AFTER_BEAUTIFY_LOOPS, 3);
2735 }
2736 }
2737
2738 // Reset major-progress flag for the driver's heuristics
2739 C->clear_major_progress();
2740
2741 // Build Dominators for elision of NULL checks & loop finding.
2742 // Since nodes do not have a slot for immediate dominator, make
2743 // a persistent side array for that info indexed on node->_idx.
2744 _idom_size = C->unique();
2745 _idom = NEW_RESOURCE_ARRAY( Node*, _idom_size );
2746 _dom_depth = NEW_RESOURCE_ARRAY( uint, _idom_size );
2747 _dom_stk = NULL; // Allocated on demand in recompute_dom_depth
2748 memset( _dom_depth, 0, _idom_size * sizeof(uint) );
2749
2750 Dominators();
2751
2752 if (!_verify_only) {
2753 // As a side effect, Dominators removed any unreachable CFG paths
2754 // into RegionNodes. It doesn't do this test against Root, so
2755 // we do it here.
2756 for( uint i = 1; i < C->root()->req(); i++ ) {
2757 if( !_nodes[C->root()->in(i)->_idx] ) { // Dead path into Root?
2758 _igvn.delete_input_of(C->root(), i);
2759 i--; // Rerun same iteration on compressed edges
2760 }
2761 }
2762
2763 // Given dominators, try to find inner loops with calls that must
2764 // always be executed (call dominates loop tail). These loops do
2765 // not need a separate safepoint.
2766 Node_List cisstack(a);
2767 _ltree_root->check_safepts(visited, cisstack);
2768 }
2769
2770 // Walk the DATA nodes and place into loops. Find earliest control
2771 // node. For CFG nodes, the _nodes array starts out and remains
2772 // holding the associated IdealLoopTree pointer. For DATA nodes, the
2773 // _nodes array holds the earliest legal controlling CFG node.
2774
2775 // Allocate stack with enough space to avoid frequent realloc
2776 int stack_size = (C->live_nodes() >> 1) + 16; // (live_nodes>>1)+16 from Java2D stats
2777 Node_Stack nstack( a, stack_size );
2778
2779 visited.Clear();
2780 Node_List worklist(a);
2781 // Don't need C->root() on worklist since
2782 // it will be processed among C->top() inputs
2783 worklist.push( C->top() );
2784 visited.set( C->top()->_idx ); // Set C->top() as visited now
2785 build_loop_early( visited, worklist, nstack );
2786
2787 // Given early legal placement, try finding counted loops. This placement
2788 // is good enough to discover most loop invariants.
2789 if( !_verify_me && !_verify_only )
2790 _ltree_root->counted_loop( this );
2791
2792 // Find latest loop placement. Find ideal loop placement.
2793 visited.Clear();
2794 init_dom_lca_tags();
2795 // Need C->root() on worklist when processing outs
2796 worklist.push( C->root() );
2797 NOT_PRODUCT( C->verify_graph_edges(); )
2798 worklist.push( C->top() );
2799 build_loop_late( visited, worklist, nstack );
2800
2801 if (_verify_only) {
2802 // restore major progress flag
2803 for (int i = 0; i < old_progress; i++)
2804 C->set_major_progress();
2805 assert(C->unique() == unique, "verification mode made Nodes? ? ?");
2806 assert(_igvn._worklist.size() == orig_worklist_size, "shouldn't push anything");
2807 return;
2808 }
2809
2810 // clear out the dead code after build_loop_late
2811 while (_deadlist.size()) {
2812 _igvn.remove_globally_dead_node(_deadlist.pop());
2813 }
2814
2815 if (stop_early) {
2816 assert(do_expensive_nodes, "why are we here?");
2817 if (process_expensive_nodes()) {
2818 // If we made some progress when processing expensive nodes then
2819 // the IGVN may modify the graph in a way that will allow us to
2820 // make some more progress: we need to try processing expensive
2821 // nodes again.
2822 C->set_major_progress();
2823 }
2824 _igvn.optimize();
2825 return;
2826 }
2827
2828 // Some parser-inserted loop predicates could never be used by loop
2829 // predication or they were moved away from loop during some optimizations.
2830 // For example, peeling. Eliminate them before next loop optimizations.
2831 eliminate_useless_predicates();
2832
2833 #ifndef PRODUCT
2834 C->verify_graph_edges();
2835 if (_verify_me) { // Nested verify pass?
2836 // Check to see if the verify mode is broken
2837 assert(C->unique() == unique, "non-optimize mode made Nodes? ? ?");
2838 return;
2839 }
2840 if(VerifyLoopOptimizations) verify();
2841 if(TraceLoopOpts && C->has_loops()) {
2842 _ltree_root->dump();
2843 }
2844 #endif
2845
2846 if (skip_loop_opts) {
2847 // restore major progress flag
2848 for (int i = 0; i < old_progress; i++) {
2849 C->set_major_progress();
2850 }
2851
2852 // Cleanup any modified bits
2853 _igvn.optimize();
2854
2855 if (C->log() != NULL) {
2856 log_loop_tree(_ltree_root, _ltree_root, C->log());
2857 }
2858 return;
2859 }
2860
2861 if (ReassociateInvariants) {
2862 // Reassociate invariants and prep for split_thru_phi
2863 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
2864 IdealLoopTree* lpt = iter.current();
2865 bool is_counted = lpt->is_counted();
2866 if (!is_counted || !lpt->is_inner()) continue;
2867
2868 // check for vectorized loops, any reassociation of invariants was already done
2869 if (is_counted && lpt->_head->as_CountedLoop()->do_unroll_only()) continue;
2870
2871 lpt->reassociate_invariants(this);
2872
2873 // Because RCE opportunities can be masked by split_thru_phi,
2874 // look for RCE candidates and inhibit split_thru_phi
2875 // on just their loop-phi's for this pass of loop opts
2876 if (SplitIfBlocks && do_split_ifs) {
2877 if (lpt->policy_range_check(this)) {
2878 lpt->_rce_candidate = 1; // = true
2879 }
2880 }
2881 }
2882 }
2883
2884 // Check for aggressive application of split-if and other transforms
2885 // that require basic-block info (like cloning through Phi's)
2886 if( SplitIfBlocks && do_split_ifs ) {
2887 visited.Clear();
2888 split_if_with_blocks( visited, nstack, last_round );
2889 NOT_PRODUCT( if( VerifyLoopOptimizations ) verify(); );
2890 if (last_round) {
2891 C->set_major_progress();
2892 }
2893 }
2894
2895 if (!C->major_progress() && do_expensive_nodes && process_expensive_nodes()) {
2896 C->set_major_progress();
2897 }
2898
2899 // Perform loop predication before iteration splitting
2900 if (C->has_loops() && !C->major_progress() && (C->predicate_count() > 0)) {
2901 _ltree_root->_child->loop_predication(this);
2902 }
2903
2904 if (OptimizeFill && UseLoopPredicate && C->has_loops() && !C->major_progress()) {
2905 if (do_intrinsify_fill()) {
2906 C->set_major_progress();
2907 }
2908 }
2909
2910 // Perform iteration-splitting on inner loops. Split iterations to avoid
2911 // range checks or one-shot null checks.
2912
2913 // If split-if's didn't hack the graph too bad (no CFG changes)
2914 // then do loop opts.
2915 if (C->has_loops() && !C->major_progress()) {
2916 memset( worklist.adr(), 0, worklist.Size()*sizeof(Node*) );
2917 _ltree_root->_child->iteration_split( this, worklist );
2918 // No verify after peeling! GCM has hoisted code out of the loop.
2919 // After peeling, the hoisted code could sink inside the peeled area.
2920 // The peeling code does not try to recompute the best location for
2921 // all the code before the peeled area, so the verify pass will always
2922 // complain about it.
2923 }
2924 // Do verify graph edges in any case
2925 NOT_PRODUCT( C->verify_graph_edges(); );
2926
2927 if (!do_split_ifs) {
2928 // We saw major progress in Split-If to get here. We forced a
2929 // pass with unrolling and not split-if, however more split-if's
2930 // might make progress. If the unrolling didn't make progress
2931 // then the major-progress flag got cleared and we won't try
2932 // another round of Split-If. In particular the ever-common
2933 // instance-of/check-cast pattern requires at least 2 rounds of
2934 // Split-If to clear out.
2935 C->set_major_progress();
2936 }
2937
2938 // Repeat loop optimizations if new loops were seen
2939 if (created_loop_node()) {
2940 C->set_major_progress();
2941 }
2942
2943 // Keep loop predicates and perform optimizations with them
2944 // until no more loop optimizations could be done.
2945 // After that switch predicates off and do more loop optimizations.
2946 if (!C->major_progress() && (C->predicate_count() > 0)) {
2947 C->cleanup_loop_predicates(_igvn);
2948 if (TraceLoopOpts) {
2949 tty->print_cr("PredicatesOff");
2950 }
2951 C->set_major_progress();
2952 }
2953
2954 // Convert scalar to superword operations at the end of all loop opts.
2955 if (UseSuperWord && C->has_loops() && !C->major_progress()) {
2956 // SuperWord transform
2957 SuperWord sw(this);
2958 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
2959 IdealLoopTree* lpt = iter.current();
2960 if (lpt->is_counted()) {
2961 CountedLoopNode *cl = lpt->_head->as_CountedLoop();
2962
2963 if (PostLoopMultiversioning && cl->is_rce_post_loop() && !cl->is_vectorized_loop()) {
2964 // Check that the rce'd post loop is encountered first, multiversion after all
2965 // major main loop optimization are concluded
2966 if (!C->major_progress()) {
2967 IdealLoopTree *lpt_next = lpt->_next;
2968 if (lpt_next && lpt_next->is_counted()) {
2969 CountedLoopNode *cl = lpt_next->_head->as_CountedLoop();
2970 has_range_checks(lpt_next);
2971 if (cl->is_post_loop() && cl->range_checks_present()) {
2972 if (!cl->is_multiversioned()) {
2973 if (multi_version_post_loops(lpt, lpt_next) == false) {
2974 // Cause the rce loop to be optimized away if we fail
2975 cl->mark_is_multiversioned();
2976 cl->set_slp_max_unroll(0);
2977 poison_rce_post_loop(lpt);
2978 }
2979 }
2980 }
2981 }
2982 sw.transform_loop(lpt, true);
2983 }
2984 } else if (cl->is_main_loop()) {
2985 sw.transform_loop(lpt, true);
2986 }
2987 }
2988 }
2989 }
2990
2991 // Cleanup any modified bits
2992 _igvn.optimize();
2993
2994 // disable assert until issue with split_flow_path is resolved (6742111)
2995 // assert(!_has_irreducible_loops || C->parsed_irreducible_loop() || C->is_osr_compilation(),
2996 // "shouldn't introduce irreducible loops");
2997
2998 if (C->log() != NULL) {
2999 log_loop_tree(_ltree_root, _ltree_root, C->log());
3000 }
3001 }
3002
3003 #ifndef PRODUCT
3004 //------------------------------print_statistics-------------------------------
3005 int PhaseIdealLoop::_loop_invokes=0;// Count of PhaseIdealLoop invokes
3006 int PhaseIdealLoop::_loop_work=0; // Sum of PhaseIdealLoop x unique
3007 void PhaseIdealLoop::print_statistics() {
3008 tty->print_cr("PhaseIdealLoop=%d, sum _unique=%d", _loop_invokes, _loop_work);
3009 }
3010
3011 //------------------------------verify-----------------------------------------
3012 // Build a verify-only PhaseIdealLoop, and see that it agrees with me.
3013 static int fail; // debug only, so its multi-thread dont care
3014 void PhaseIdealLoop::verify() const {
3015 int old_progress = C->major_progress();
3016 ResourceMark rm;
3017 PhaseIdealLoop loop_verify( _igvn, this );
3018 VectorSet visited(Thread::current()->resource_area());
3019
3020 fail = 0;
3021 verify_compare( C->root(), &loop_verify, visited );
3022 assert( fail == 0, "verify loops failed" );
3023 // Verify loop structure is the same
3024 _ltree_root->verify_tree(loop_verify._ltree_root, NULL);
3025 // Reset major-progress. It was cleared by creating a verify version of
3026 // PhaseIdealLoop.
3027 for( int i=0; i<old_progress; i++ )
3028 C->set_major_progress();
3029 }
3030
3031 //------------------------------verify_compare---------------------------------
3032 // Make sure me and the given PhaseIdealLoop agree on key data structures
3033 void PhaseIdealLoop::verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const {
3034 if( !n ) return;
3035 if( visited.test_set( n->_idx ) ) return;
3036 if( !_nodes[n->_idx] ) { // Unreachable
3037 assert( !loop_verify->_nodes[n->_idx], "both should be unreachable" );
3038 return;
3039 }
3040
3041 uint i;
3042 for( i = 0; i < n->req(); i++ )
3043 verify_compare( n->in(i), loop_verify, visited );
3044
3045 // Check the '_nodes' block/loop structure
3046 i = n->_idx;
3047 if( has_ctrl(n) ) { // We have control; verify has loop or ctrl
3048 if( _nodes[i] != loop_verify->_nodes[i] &&
3049 get_ctrl_no_update(n) != loop_verify->get_ctrl_no_update(n) ) {
3050 tty->print("Mismatched control setting for: ");
3051 n->dump();
3052 if( fail++ > 10 ) return;
3053 Node *c = get_ctrl_no_update(n);
3054 tty->print("We have it as: ");
3055 if( c->in(0) ) c->dump();
3056 else tty->print_cr("N%d",c->_idx);
3057 tty->print("Verify thinks: ");
3058 if( loop_verify->has_ctrl(n) )
3059 loop_verify->get_ctrl_no_update(n)->dump();
3060 else
3061 loop_verify->get_loop_idx(n)->dump();
3062 tty->cr();
3063 }
3064 } else { // We have a loop
3065 IdealLoopTree *us = get_loop_idx(n);
3066 if( loop_verify->has_ctrl(n) ) {
3067 tty->print("Mismatched loop setting for: ");
3068 n->dump();
3069 if( fail++ > 10 ) return;
3070 tty->print("We have it as: ");
3071 us->dump();
3072 tty->print("Verify thinks: ");
3073 loop_verify->get_ctrl_no_update(n)->dump();
3074 tty->cr();
3075 } else if (!C->major_progress()) {
3076 // Loop selection can be messed up if we did a major progress
3077 // operation, like split-if. Do not verify in that case.
3078 IdealLoopTree *them = loop_verify->get_loop_idx(n);
3079 if( us->_head != them->_head || us->_tail != them->_tail ) {
3080 tty->print("Unequals loops for: ");
3081 n->dump();
3082 if( fail++ > 10 ) return;
3083 tty->print("We have it as: ");
3084 us->dump();
3085 tty->print("Verify thinks: ");
3086 them->dump();
3087 tty->cr();
3088 }
3089 }
3090 }
3091
3092 // Check for immediate dominators being equal
3093 if( i >= _idom_size ) {
3094 if( !n->is_CFG() ) return;
3095 tty->print("CFG Node with no idom: ");
3096 n->dump();
3097 return;
3098 }
3099 if( !n->is_CFG() ) return;
3100 if( n == C->root() ) return; // No IDOM here
3101
3102 assert(n->_idx == i, "sanity");
3103 Node *id = idom_no_update(n);
3104 if( id != loop_verify->idom_no_update(n) ) {
3105 tty->print("Unequals idoms for: ");
3106 n->dump();
3107 if( fail++ > 10 ) return;
3108 tty->print("We have it as: ");
3109 id->dump();
3110 tty->print("Verify thinks: ");
3111 loop_verify->idom_no_update(n)->dump();
3112 tty->cr();
3113 }
3114
3115 }
3116
3117 //------------------------------verify_tree------------------------------------
3118 // Verify that tree structures match. Because the CFG can change, siblings
3119 // within the loop tree can be reordered. We attempt to deal with that by
3120 // reordering the verify's loop tree if possible.
3121 void IdealLoopTree::verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const {
3122 assert( _parent == parent, "Badly formed loop tree" );
3123
3124 // Siblings not in same order? Attempt to re-order.
3125 if( _head != loop->_head ) {
3126 // Find _next pointer to update
3127 IdealLoopTree **pp = &loop->_parent->_child;
3128 while( *pp != loop )
3129 pp = &((*pp)->_next);
3130 // Find proper sibling to be next
3131 IdealLoopTree **nn = &loop->_next;
3132 while( (*nn) && (*nn)->_head != _head )
3133 nn = &((*nn)->_next);
3134
3135 // Check for no match.
3136 if( !(*nn) ) {
3137 // Annoyingly, irreducible loops can pick different headers
3138 // after a major_progress operation, so the rest of the loop
3139 // tree cannot be matched.
3140 if (_irreducible && Compile::current()->major_progress()) return;
3141 assert( 0, "failed to match loop tree" );
3142 }
3143
3144 // Move (*nn) to (*pp)
3145 IdealLoopTree *hit = *nn;
3146 *nn = hit->_next;
3147 hit->_next = loop;
3148 *pp = loop;
3149 loop = hit;
3150 // Now try again to verify
3151 }
3152
3153 assert( _head == loop->_head , "mismatched loop head" );
3154 Node *tail = _tail; // Inline a non-updating version of
3155 while( !tail->in(0) ) // the 'tail()' call.
3156 tail = tail->in(1);
3157 assert( tail == loop->_tail, "mismatched loop tail" );
3158
3159 // Counted loops that are guarded should be able to find their guards
3160 if( _head->is_CountedLoop() && _head->as_CountedLoop()->is_main_loop() ) {
3161 CountedLoopNode *cl = _head->as_CountedLoop();
3162 Node *init = cl->init_trip();
3163 Node *ctrl = cl->in(LoopNode::EntryControl);
3164 assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" );
3165 Node *iff = ctrl->in(0);
3166 assert( iff->Opcode() == Op_If, "" );
3167 Node *bol = iff->in(1);
3168 assert( bol->Opcode() == Op_Bool, "" );
3169 Node *cmp = bol->in(1);
3170 assert( cmp->Opcode() == Op_CmpI, "" );
3171 Node *add = cmp->in(1);
3172 Node *opaq;
3173 if( add->Opcode() == Op_Opaque1 ) {
3174 opaq = add;
3175 } else {
3176 assert( add->Opcode() == Op_AddI || add->Opcode() == Op_ConI , "" );
3177 assert( add == init, "" );
3178 opaq = cmp->in(2);
3179 }
3180 assert( opaq->Opcode() == Op_Opaque1, "" );
3181
3182 }
3183
3184 if (_child != NULL) _child->verify_tree(loop->_child, this);
3185 if (_next != NULL) _next ->verify_tree(loop->_next, parent);
3186 // Innermost loops need to verify loop bodies,
3187 // but only if no 'major_progress'
3188 int fail = 0;
3189 if (!Compile::current()->major_progress() && _child == NULL) {
3190 for( uint i = 0; i < _body.size(); i++ ) {
3191 Node *n = _body.at(i);
3192 if (n->outcnt() == 0) continue; // Ignore dead
3193 uint j;
3194 for( j = 0; j < loop->_body.size(); j++ )
3195 if( loop->_body.at(j) == n )
3196 break;
3197 if( j == loop->_body.size() ) { // Not found in loop body
3198 // Last ditch effort to avoid assertion: Its possible that we
3199 // have some users (so outcnt not zero) but are still dead.
3200 // Try to find from root.
3201 if (Compile::current()->root()->find(n->_idx)) {
3202 fail++;
3203 tty->print("We have that verify does not: ");
3204 n->dump();
3205 }
3206 }
3207 }
3208 for( uint i2 = 0; i2 < loop->_body.size(); i2++ ) {
3209 Node *n = loop->_body.at(i2);
3210 if (n->outcnt() == 0) continue; // Ignore dead
3211 uint j;
3212 for( j = 0; j < _body.size(); j++ )
3213 if( _body.at(j) == n )
3214 break;
3215 if( j == _body.size() ) { // Not found in loop body
3216 // Last ditch effort to avoid assertion: Its possible that we
3217 // have some users (so outcnt not zero) but are still dead.
3218 // Try to find from root.
3219 if (Compile::current()->root()->find(n->_idx)) {
3220 fail++;
3221 tty->print("Verify has that we do not: ");
3222 n->dump();
3223 }
3224 }
3225 }
3226 assert( !fail, "loop body mismatch" );
3227 }
3228 }
3229
3230 #endif
3231
3232 //------------------------------set_idom---------------------------------------
3233 void PhaseIdealLoop::set_idom(Node* d, Node* n, uint dom_depth) {
3234 uint idx = d->_idx;
3235 if (idx >= _idom_size) {
3236 uint newsize = _idom_size<<1;
3237 while( idx >= newsize ) {
3238 newsize <<= 1;
3239 }
3240 _idom = REALLOC_RESOURCE_ARRAY( Node*, _idom,_idom_size,newsize);
3241 _dom_depth = REALLOC_RESOURCE_ARRAY( uint, _dom_depth,_idom_size,newsize);
3242 memset( _dom_depth + _idom_size, 0, (newsize - _idom_size) * sizeof(uint) );
3243 _idom_size = newsize;
3244 }
3245 _idom[idx] = n;
3246 _dom_depth[idx] = dom_depth;
3247 }
3248
3249 //------------------------------recompute_dom_depth---------------------------------------
3250 // The dominator tree is constructed with only parent pointers.
3251 // This recomputes the depth in the tree by first tagging all
3252 // nodes as "no depth yet" marker. The next pass then runs up
3253 // the dom tree from each node marked "no depth yet", and computes
3254 // the depth on the way back down.
3255 void PhaseIdealLoop::recompute_dom_depth() {
3256 uint no_depth_marker = C->unique();
3257 uint i;
3258 // Initialize depth to "no depth yet" and realize all lazy updates
3259 for (i = 0; i < _idom_size; i++) {
3260 // Only indices with a _dom_depth has a Node* or NULL (otherwise uninitalized).
3261 if (_dom_depth[i] > 0 && _idom[i] != NULL) {
3262 _dom_depth[i] = no_depth_marker;
3263
3264 // heal _idom if it has a fwd mapping in _nodes
3265 if (_idom[i]->in(0) == NULL) {
3266 idom(i);
3267 }
3268 }
3269 }
3270 if (_dom_stk == NULL) {
3271 uint init_size = C->live_nodes() / 100; // Guess that 1/100 is a reasonable initial size.
3272 if (init_size < 10) init_size = 10;
3273 _dom_stk = new GrowableArray<uint>(init_size);
3274 }
3275 // Compute new depth for each node.
3276 for (i = 0; i < _idom_size; i++) {
3277 uint j = i;
3278 // Run up the dom tree to find a node with a depth
3279 while (_dom_depth[j] == no_depth_marker) {
3280 _dom_stk->push(j);
3281 j = _idom[j]->_idx;
3282 }
3283 // Compute the depth on the way back down this tree branch
3284 uint dd = _dom_depth[j] + 1;
3285 while (_dom_stk->length() > 0) {
3286 uint j = _dom_stk->pop();
3287 _dom_depth[j] = dd;
3288 dd++;
3289 }
3290 }
3291 }
3292
3293 //------------------------------sort-------------------------------------------
3294 // Insert 'loop' into the existing loop tree. 'innermost' is a leaf of the
3295 // loop tree, not the root.
3296 IdealLoopTree *PhaseIdealLoop::sort( IdealLoopTree *loop, IdealLoopTree *innermost ) {
3297 if( !innermost ) return loop; // New innermost loop
3298
3299 int loop_preorder = get_preorder(loop->_head); // Cache pre-order number
3300 assert( loop_preorder, "not yet post-walked loop" );
3301 IdealLoopTree **pp = &innermost; // Pointer to previous next-pointer
3302 IdealLoopTree *l = *pp; // Do I go before or after 'l'?
3303
3304 // Insert at start of list
3305 while( l ) { // Insertion sort based on pre-order
3306 if( l == loop ) return innermost; // Already on list!
3307 int l_preorder = get_preorder(l->_head); // Cache pre-order number
3308 assert( l_preorder, "not yet post-walked l" );
3309 // Check header pre-order number to figure proper nesting
3310 if( loop_preorder > l_preorder )
3311 break; // End of insertion
3312 // If headers tie (e.g., shared headers) check tail pre-order numbers.
3313 // Since I split shared headers, you'd think this could not happen.
3314 // BUT: I must first do the preorder numbering before I can discover I
3315 // have shared headers, so the split headers all get the same preorder
3316 // number as the RegionNode they split from.
3317 if( loop_preorder == l_preorder &&
3318 get_preorder(loop->_tail) < get_preorder(l->_tail) )
3319 break; // Also check for shared headers (same pre#)
3320 pp = &l->_parent; // Chain up list
3321 l = *pp;
3322 }
3323 // Link into list
3324 // Point predecessor to me
3325 *pp = loop;
3326 // Point me to successor
3327 IdealLoopTree *p = loop->_parent;
3328 loop->_parent = l; // Point me to successor
3329 if( p ) sort( p, innermost ); // Insert my parents into list as well
3330 return innermost;
3331 }
3332
3333 //------------------------------build_loop_tree--------------------------------
3334 // I use a modified Vick/Tarjan algorithm. I need pre- and a post- visit
3335 // bits. The _nodes[] array is mapped by Node index and holds a NULL for
3336 // not-yet-pre-walked, pre-order # for pre-but-not-post-walked and holds the
3337 // tightest enclosing IdealLoopTree for post-walked.
3338 //
3339 // During my forward walk I do a short 1-layer lookahead to see if I can find
3340 // a loop backedge with that doesn't have any work on the backedge. This
3341 // helps me construct nested loops with shared headers better.
3342 //
3343 // Once I've done the forward recursion, I do the post-work. For each child
3344 // I check to see if there is a backedge. Backedges define a loop! I
3345 // insert an IdealLoopTree at the target of the backedge.
3346 //
3347 // During the post-work I also check to see if I have several children
3348 // belonging to different loops. If so, then this Node is a decision point
3349 // where control flow can choose to change loop nests. It is at this
3350 // decision point where I can figure out how loops are nested. At this
3351 // time I can properly order the different loop nests from my children.
3352 // Note that there may not be any backedges at the decision point!
3353 //
3354 // Since the decision point can be far removed from the backedges, I can't
3355 // order my loops at the time I discover them. Thus at the decision point
3356 // I need to inspect loop header pre-order numbers to properly nest my
3357 // loops. This means I need to sort my childrens' loops by pre-order.
3358 // The sort is of size number-of-control-children, which generally limits
3359 // it to size 2 (i.e., I just choose between my 2 target loops).
3360 void PhaseIdealLoop::build_loop_tree() {
3361 // Allocate stack of size C->live_nodes()/2 to avoid frequent realloc
3362 GrowableArray <Node *> bltstack(C->live_nodes() >> 1);
3363 Node *n = C->root();
3364 bltstack.push(n);
3365 int pre_order = 1;
3366 int stack_size;
3367
3368 while ( ( stack_size = bltstack.length() ) != 0 ) {
3369 n = bltstack.top(); // Leave node on stack
3370 if ( !is_visited(n) ) {
3371 // ---- Pre-pass Work ----
3372 // Pre-walked but not post-walked nodes need a pre_order number.
3373
3374 set_preorder_visited( n, pre_order ); // set as visited
3375
3376 // ---- Scan over children ----
3377 // Scan first over control projections that lead to loop headers.
3378 // This helps us find inner-to-outer loops with shared headers better.
3379
3380 // Scan children's children for loop headers.
3381 for ( int i = n->outcnt() - 1; i >= 0; --i ) {
3382 Node* m = n->raw_out(i); // Child
3383 if( m->is_CFG() && !is_visited(m) ) { // Only for CFG children
3384 // Scan over children's children to find loop
3385 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3386 Node* l = m->fast_out(j);
3387 if( is_visited(l) && // Been visited?
3388 !is_postvisited(l) && // But not post-visited
3389 get_preorder(l) < pre_order ) { // And smaller pre-order
3390 // Found! Scan the DFS down this path before doing other paths
3391 bltstack.push(m);
3392 break;
3393 }
3394 }
3395 }
3396 }
3397 pre_order++;
3398 }
3399 else if ( !is_postvisited(n) ) {
3400 // Note: build_loop_tree_impl() adds out edges on rare occasions,
3401 // such as com.sun.rsasign.am::a.
3402 // For non-recursive version, first, process current children.
3403 // On next iteration, check if additional children were added.
3404 for ( int k = n->outcnt() - 1; k >= 0; --k ) {
3405 Node* u = n->raw_out(k);
3406 if ( u->is_CFG() && !is_visited(u) ) {
3407 bltstack.push(u);
3408 }
3409 }
3410 if ( bltstack.length() == stack_size ) {
3411 // There were no additional children, post visit node now
3412 (void)bltstack.pop(); // Remove node from stack
3413 pre_order = build_loop_tree_impl( n, pre_order );
3414 // Check for bailout
3415 if (C->failing()) {
3416 return;
3417 }
3418 // Check to grow _preorders[] array for the case when
3419 // build_loop_tree_impl() adds new nodes.
3420 check_grow_preorders();
3421 }
3422 }
3423 else {
3424 (void)bltstack.pop(); // Remove post-visited node from stack
3425 }
3426 }
3427 }
3428
3429 //------------------------------build_loop_tree_impl---------------------------
3430 int PhaseIdealLoop::build_loop_tree_impl( Node *n, int pre_order ) {
3431 // ---- Post-pass Work ----
3432 // Pre-walked but not post-walked nodes need a pre_order number.
3433
3434 // Tightest enclosing loop for this Node
3435 IdealLoopTree *innermost = NULL;
3436
3437 // For all children, see if any edge is a backedge. If so, make a loop
3438 // for it. Then find the tightest enclosing loop for the self Node.
3439 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
3440 Node* m = n->fast_out(i); // Child
3441 if( n == m ) continue; // Ignore control self-cycles
3442 if( !m->is_CFG() ) continue;// Ignore non-CFG edges
3443
3444 IdealLoopTree *l; // Child's loop
3445 if( !is_postvisited(m) ) { // Child visited but not post-visited?
3446 // Found a backedge
3447 assert( get_preorder(m) < pre_order, "should be backedge" );
3448 // Check for the RootNode, which is already a LoopNode and is allowed
3449 // to have multiple "backedges".
3450 if( m == C->root()) { // Found the root?
3451 l = _ltree_root; // Root is the outermost LoopNode
3452 } else { // Else found a nested loop
3453 // Insert a LoopNode to mark this loop.
3454 l = new IdealLoopTree(this, m, n);
3455 } // End of Else found a nested loop
3456 if( !has_loop(m) ) // If 'm' does not already have a loop set
3457 set_loop(m, l); // Set loop header to loop now
3458
3459 } else { // Else not a nested loop
3460 if( !_nodes[m->_idx] ) continue; // Dead code has no loop
3461 l = get_loop(m); // Get previously determined loop
3462 // If successor is header of a loop (nest), move up-loop till it
3463 // is a member of some outer enclosing loop. Since there are no
3464 // shared headers (I've split them already) I only need to go up
3465 // at most 1 level.
3466 while( l && l->_head == m ) // Successor heads loop?
3467 l = l->_parent; // Move up 1 for me
3468 // If this loop is not properly parented, then this loop
3469 // has no exit path out, i.e. its an infinite loop.
3470 if( !l ) {
3471 // Make loop "reachable" from root so the CFG is reachable. Basically
3472 // insert a bogus loop exit that is never taken. 'm', the loop head,
3473 // points to 'n', one (of possibly many) fall-in paths. There may be
3474 // many backedges as well.
3475
3476 // Here I set the loop to be the root loop. I could have, after
3477 // inserting a bogus loop exit, restarted the recursion and found my
3478 // new loop exit. This would make the infinite loop a first-class
3479 // loop and it would then get properly optimized. What's the use of
3480 // optimizing an infinite loop?
3481 l = _ltree_root; // Oops, found infinite loop
3482
3483 if (!_verify_only) {
3484 // Insert the NeverBranch between 'm' and it's control user.
3485 NeverBranchNode *iff = new NeverBranchNode( m );
3486 _igvn.register_new_node_with_optimizer(iff);
3487 set_loop(iff, l);
3488 Node *if_t = new CProjNode( iff, 0 );
3489 _igvn.register_new_node_with_optimizer(if_t);
3490 set_loop(if_t, l);
3491
3492 Node* cfg = NULL; // Find the One True Control User of m
3493 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3494 Node* x = m->fast_out(j);
3495 if (x->is_CFG() && x != m && x != iff)
3496 { cfg = x; break; }
3497 }
3498 assert(cfg != NULL, "must find the control user of m");
3499 uint k = 0; // Probably cfg->in(0)
3500 while( cfg->in(k) != m ) k++; // But check incase cfg is a Region
3501 cfg->set_req( k, if_t ); // Now point to NeverBranch
3502 _igvn._worklist.push(cfg);
3503
3504 // Now create the never-taken loop exit
3505 Node *if_f = new CProjNode( iff, 1 );
3506 _igvn.register_new_node_with_optimizer(if_f);
3507 set_loop(if_f, l);
3508 // Find frame ptr for Halt. Relies on the optimizer
3509 // V-N'ing. Easier and quicker than searching through
3510 // the program structure.
3511 Node *frame = new ParmNode( C->start(), TypeFunc::FramePtr );
3512 _igvn.register_new_node_with_optimizer(frame);
3513 // Halt & Catch Fire
3514 Node *halt = new HaltNode( if_f, frame );
3515 _igvn.register_new_node_with_optimizer(halt);
3516 set_loop(halt, l);
3517 C->root()->add_req(halt);
3518 }
3519 set_loop(C->root(), _ltree_root);
3520 }
3521 }
3522 // Weeny check for irreducible. This child was already visited (this
3523 // IS the post-work phase). Is this child's loop header post-visited
3524 // as well? If so, then I found another entry into the loop.
3525 if (!_verify_only) {
3526 while( is_postvisited(l->_head) ) {
3527 // found irreducible
3528 l->_irreducible = 1; // = true
3529 l = l->_parent;
3530 _has_irreducible_loops = true;
3531 // Check for bad CFG here to prevent crash, and bailout of compile
3532 if (l == NULL) {
3533 C->record_method_not_compilable("unhandled CFG detected during loop optimization");
3534 return pre_order;
3535 }
3536 }
3537 C->set_has_irreducible_loop(_has_irreducible_loops);
3538 }
3539
3540 // This Node might be a decision point for loops. It is only if
3541 // it's children belong to several different loops. The sort call
3542 // does a trivial amount of work if there is only 1 child or all
3543 // children belong to the same loop. If however, the children
3544 // belong to different loops, the sort call will properly set the
3545 // _parent pointers to show how the loops nest.
3546 //
3547 // In any case, it returns the tightest enclosing loop.
3548 innermost = sort( l, innermost );
3549 }
3550
3551 // Def-use info will have some dead stuff; dead stuff will have no
3552 // loop decided on.
3553
3554 // Am I a loop header? If so fix up my parent's child and next ptrs.
3555 if( innermost && innermost->_head == n ) {
3556 assert( get_loop(n) == innermost, "" );
3557 IdealLoopTree *p = innermost->_parent;
3558 IdealLoopTree *l = innermost;
3559 while( p && l->_head == n ) {
3560 l->_next = p->_child; // Put self on parents 'next child'
3561 p->_child = l; // Make self as first child of parent
3562 l = p; // Now walk up the parent chain
3563 p = l->_parent;
3564 }
3565 } else {
3566 // Note that it is possible for a LoopNode to reach here, if the
3567 // backedge has been made unreachable (hence the LoopNode no longer
3568 // denotes a Loop, and will eventually be removed).
3569
3570 // Record tightest enclosing loop for self. Mark as post-visited.
3571 set_loop(n, innermost);
3572 // Also record has_call flag early on
3573 if( innermost ) {
3574 if( n->is_Call() && !n->is_CallLeaf() && !n->is_macro() ) {
3575 // Do not count uncommon calls
3576 if( !n->is_CallStaticJava() || !n->as_CallStaticJava()->_name ) {
3577 Node *iff = n->in(0)->in(0);
3578 // No any calls for vectorized loops.
3579 if( UseSuperWord || !iff->is_If() ||
3580 (n->in(0)->Opcode() == Op_IfFalse &&
3581 (1.0 - iff->as_If()->_prob) >= 0.01) ||
3582 (iff->as_If()->_prob >= 0.01) )
3583 innermost->_has_call = 1;
3584 }
3585 } else if( n->is_Allocate() && n->as_Allocate()->_is_scalar_replaceable ) {
3586 // Disable loop optimizations if the loop has a scalar replaceable
3587 // allocation. This disabling may cause a potential performance lost
3588 // if the allocation is not eliminated for some reason.
3589 innermost->_allow_optimizations = false;
3590 innermost->_has_call = 1; // = true
3591 } else if (n->Opcode() == Op_SafePoint) {
3592 // Record all safepoints in this loop.
3593 if (innermost->_safepts == NULL) innermost->_safepts = new Node_List();
3594 innermost->_safepts->push(n);
3595 }
3596 }
3597 }
3598
3599 // Flag as post-visited now
3600 set_postvisited(n);
3601 return pre_order;
3602 }
3603
3604
3605 //------------------------------build_loop_early-------------------------------
3606 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
3607 // First pass computes the earliest controlling node possible. This is the
3608 // controlling input with the deepest dominating depth.
3609 void PhaseIdealLoop::build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) {
3610 while (worklist.size() != 0) {
3611 // Use local variables nstack_top_n & nstack_top_i to cache values
3612 // on nstack's top.
3613 Node *nstack_top_n = worklist.pop();
3614 uint nstack_top_i = 0;
3615 //while_nstack_nonempty:
3616 while (true) {
3617 // Get parent node and next input's index from stack's top.
3618 Node *n = nstack_top_n;
3619 uint i = nstack_top_i;
3620 uint cnt = n->req(); // Count of inputs
3621 if (i == 0) { // Pre-process the node.
3622 if( has_node(n) && // Have either loop or control already?
3623 !has_ctrl(n) ) { // Have loop picked out already?
3624 // During "merge_many_backedges" we fold up several nested loops
3625 // into a single loop. This makes the members of the original
3626 // loop bodies pointing to dead loops; they need to move up
3627 // to the new UNION'd larger loop. I set the _head field of these
3628 // dead loops to NULL and the _parent field points to the owning
3629 // loop. Shades of UNION-FIND algorithm.
3630 IdealLoopTree *ilt;
3631 while( !(ilt = get_loop(n))->_head ) {
3632 // Normally I would use a set_loop here. But in this one special
3633 // case, it is legal (and expected) to change what loop a Node
3634 // belongs to.
3635 _nodes.map(n->_idx, (Node*)(ilt->_parent) );
3636 }
3637 // Remove safepoints ONLY if I've already seen I don't need one.
3638 // (the old code here would yank a 2nd safepoint after seeing a
3639 // first one, even though the 1st did not dominate in the loop body
3640 // and thus could be avoided indefinitely)
3641 if( !_verify_only && !_verify_me && ilt->_has_sfpt && n->Opcode() == Op_SafePoint &&
3642 is_deleteable_safept(n)) {
3643 Node *in = n->in(TypeFunc::Control);
3644 lazy_replace(n,in); // Pull safepoint now
3645 if (ilt->_safepts != NULL) {
3646 ilt->_safepts->yank(n);
3647 }
3648 // Carry on with the recursion "as if" we are walking
3649 // only the control input
3650 if( !visited.test_set( in->_idx ) ) {
3651 worklist.push(in); // Visit this guy later, using worklist
3652 }
3653 // Get next node from nstack:
3654 // - skip n's inputs processing by setting i > cnt;
3655 // - we also will not call set_early_ctrl(n) since
3656 // has_node(n) == true (see the condition above).
3657 i = cnt + 1;
3658 }
3659 }
3660 } // if (i == 0)
3661
3662 // Visit all inputs
3663 bool done = true; // Assume all n's inputs will be processed
3664 while (i < cnt) {
3665 Node *in = n->in(i);
3666 ++i;
3667 if (in == NULL) continue;
3668 if (in->pinned() && !in->is_CFG())
3669 set_ctrl(in, in->in(0));
3670 int is_visited = visited.test_set( in->_idx );
3671 if (!has_node(in)) { // No controlling input yet?
3672 assert( !in->is_CFG(), "CFG Node with no controlling input?" );
3673 assert( !is_visited, "visit only once" );
3674 nstack.push(n, i); // Save parent node and next input's index.
3675 nstack_top_n = in; // Process current input now.
3676 nstack_top_i = 0;
3677 done = false; // Not all n's inputs processed.
3678 break; // continue while_nstack_nonempty;
3679 } else if (!is_visited) {
3680 // This guy has a location picked out for him, but has not yet
3681 // been visited. Happens to all CFG nodes, for instance.
3682 // Visit him using the worklist instead of recursion, to break
3683 // cycles. Since he has a location already we do not need to
3684 // find his location before proceeding with the current Node.
3685 worklist.push(in); // Visit this guy later, using worklist
3686 }
3687 }
3688 if (done) {
3689 // All of n's inputs have been processed, complete post-processing.
3690
3691 // Compute earliest point this Node can go.
3692 // CFG, Phi, pinned nodes already know their controlling input.
3693 if (!has_node(n)) {
3694 // Record earliest legal location
3695 set_early_ctrl( n );
3696 }
3697 if (nstack.is_empty()) {
3698 // Finished all nodes on stack.
3699 // Process next node on the worklist.
3700 break;
3701 }
3702 // Get saved parent node and next input's index.
3703 nstack_top_n = nstack.node();
3704 nstack_top_i = nstack.index();
3705 nstack.pop();
3706 }
3707 } // while (true)
3708 }
3709 }
3710
3711 //------------------------------dom_lca_internal--------------------------------
3712 // Pair-wise LCA
3713 Node *PhaseIdealLoop::dom_lca_internal( Node *n1, Node *n2 ) const {
3714 if( !n1 ) return n2; // Handle NULL original LCA
3715 assert( n1->is_CFG(), "" );
3716 assert( n2->is_CFG(), "" );
3717 // find LCA of all uses
3718 uint d1 = dom_depth(n1);
3719 uint d2 = dom_depth(n2);
3720 while (n1 != n2) {
3721 if (d1 > d2) {
3722 n1 = idom(n1);
3723 d1 = dom_depth(n1);
3724 } else if (d1 < d2) {
3725 n2 = idom(n2);
3726 d2 = dom_depth(n2);
3727 } else {
3728 // Here d1 == d2. Due to edits of the dominator-tree, sections
3729 // of the tree might have the same depth. These sections have
3730 // to be searched more carefully.
3731
3732 // Scan up all the n1's with equal depth, looking for n2.
3733 Node *t1 = idom(n1);
3734 while (dom_depth(t1) == d1) {
3735 if (t1 == n2) return n2;
3736 t1 = idom(t1);
3737 }
3738 // Scan up all the n2's with equal depth, looking for n1.
3739 Node *t2 = idom(n2);
3740 while (dom_depth(t2) == d2) {
3741 if (t2 == n1) return n1;
3742 t2 = idom(t2);
3743 }
3744 // Move up to a new dominator-depth value as well as up the dom-tree.
3745 n1 = t1;
3746 n2 = t2;
3747 d1 = dom_depth(n1);
3748 d2 = dom_depth(n2);
3749 }
3750 }
3751 return n1;
3752 }
3753
3754 //------------------------------compute_idom-----------------------------------
3755 // Locally compute IDOM using dom_lca call. Correct only if the incoming
3756 // IDOMs are correct.
3757 Node *PhaseIdealLoop::compute_idom( Node *region ) const {
3758 assert( region->is_Region(), "" );
3759 Node *LCA = NULL;
3760 for( uint i = 1; i < region->req(); i++ ) {
3761 if( region->in(i) != C->top() )
3762 LCA = dom_lca( LCA, region->in(i) );
3763 }
3764 return LCA;
3765 }
3766
3767 bool PhaseIdealLoop::verify_dominance(Node* n, Node* use, Node* LCA, Node* early) {
3768 bool had_error = false;
3769 #ifdef ASSERT
3770 if (early != C->root()) {
3771 // Make sure that there's a dominance path from LCA to early
3772 Node* d = LCA;
3773 while (d != early) {
3774 if (d == C->root()) {
3775 dump_bad_graph("Bad graph detected in compute_lca_of_uses", n, early, LCA);
3776 tty->print_cr("*** Use %d isn't dominated by def %d ***", use->_idx, n->_idx);
3777 had_error = true;
3778 break;
3779 }
3780 d = idom(d);
3781 }
3782 }
3783 #endif
3784 return had_error;
3785 }
3786
3787
3788 Node* PhaseIdealLoop::compute_lca_of_uses(Node* n, Node* early, bool verify) {
3789 // Compute LCA over list of uses
3790 bool had_error = false;
3791 Node *LCA = NULL;
3792 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax && LCA != early; i++) {
3793 Node* c = n->fast_out(i);
3794 if (_nodes[c->_idx] == NULL)
3795 continue; // Skip the occasional dead node
3796 if( c->is_Phi() ) { // For Phis, we must land above on the path
3797 for( uint j=1; j<c->req(); j++ ) {// For all inputs
3798 if( c->in(j) == n ) { // Found matching input?
3799 Node *use = c->in(0)->in(j);
3800 if (_verify_only && use->is_top()) continue;
3801 LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
3802 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error;
3803 }
3804 }
3805 } else {
3806 // For CFG data-users, use is in the block just prior
3807 Node *use = has_ctrl(c) ? get_ctrl(c) : c->in(0);
3808 LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
3809 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error;
3810 }
3811 }
3812 assert(!had_error, "bad dominance");
3813 return LCA;
3814 }
3815
3816 // Check the shape of the graph at the loop entry. In some cases,
3817 // the shape of the graph does not match the shape outlined below.
3818 // That is caused by the Opaque1 node "protecting" the shape of
3819 // the graph being removed by, for example, the IGVN performed
3820 // in PhaseIdealLoop::build_and_optimize().
3821 //
3822 // After the Opaque1 node has been removed, optimizations (e.g., split-if,
3823 // loop unswitching, and IGVN, or a combination of them) can freely change
3824 // the graph's shape. As a result, the graph shape outlined below cannot
3825 // be guaranteed anymore.
3826 bool PhaseIdealLoop::is_canonical_loop_entry(CountedLoopNode* cl) {
3827 if (!cl->is_main_loop() && !cl->is_post_loop()) {
3828 return false;
3829 }
3830 Node* ctrl = cl->skip_predicates();
3831
3832 if (ctrl == NULL || (!ctrl->is_IfTrue() && !ctrl->is_IfFalse())) {
3833 return false;
3834 }
3835 Node* iffm = ctrl->in(0);
3836 if (iffm == NULL || !iffm->is_If()) {
3837 return false;
3838 }
3839 Node* bolzm = iffm->in(1);
3840 if (bolzm == NULL || !bolzm->is_Bool()) {
3841 return false;
3842 }
3843 Node* cmpzm = bolzm->in(1);
3844 if (cmpzm == NULL || !cmpzm->is_Cmp()) {
3845 return false;
3846 }
3847 // compares can get conditionally flipped
3848 bool found_opaque = false;
3849 for (uint i = 1; i < cmpzm->req(); i++) {
3850 Node* opnd = cmpzm->in(i);
3851 if (opnd && opnd->Opcode() == Op_Opaque1) {
3852 found_opaque = true;
3853 break;
3854 }
3855 }
3856 if (!found_opaque) {
3857 return false;
3858 }
3859 return true;
3860 }
3861
3862 //------------------------------get_late_ctrl----------------------------------
3863 // Compute latest legal control.
3864 Node *PhaseIdealLoop::get_late_ctrl( Node *n, Node *early ) {
3865 assert(early != NULL, "early control should not be NULL");
3866
3867 Node* LCA = compute_lca_of_uses(n, early);
3868 #ifdef ASSERT
3869 if (LCA == C->root() && LCA != early) {
3870 // def doesn't dominate uses so print some useful debugging output
3871 compute_lca_of_uses(n, early, true);
3872 }
3873 #endif
3874
3875 // if this is a load, check for anti-dependent stores
3876 // We use a conservative algorithm to identify potential interfering
3877 // instructions and for rescheduling the load. The users of the memory
3878 // input of this load are examined. Any use which is not a load and is
3879 // dominated by early is considered a potentially interfering store.
3880 // This can produce false positives.
3881 if (n->is_Load() && LCA != early) {
3882 Node_List worklist;
3883
3884 Node *mem = n->in(MemNode::Memory);
3885 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
3886 Node* s = mem->fast_out(i);
3887 worklist.push(s);
3888 }
3889 while(worklist.size() != 0 && LCA != early) {
3890 Node* s = worklist.pop();
3891 if (s->is_Load() || s->Opcode() == Op_SafePoint) {
3892 continue;
3893 } else if (s->is_MergeMem()) {
3894 for (DUIterator_Fast imax, i = s->fast_outs(imax); i < imax; i++) {
3895 Node* s1 = s->fast_out(i);
3896 worklist.push(s1);
3897 }
3898 } else {
3899 Node *sctrl = has_ctrl(s) ? get_ctrl(s) : s->in(0);
3900 assert(sctrl != NULL || s->outcnt() == 0, "must have control");
3901 if (sctrl != NULL && !sctrl->is_top() && is_dominator(early, sctrl)) {
3902 LCA = dom_lca_for_get_late_ctrl(LCA, sctrl, n);
3903 }
3904 }
3905 }
3906 }
3907
3908 assert(LCA == find_non_split_ctrl(LCA), "unexpected late control");
3909 return LCA;
3910 }
3911
3912 // true if CFG node d dominates CFG node n
3913 bool PhaseIdealLoop::is_dominator(Node *d, Node *n) {
3914 if (d == n)
3915 return true;
3916 assert(d->is_CFG() && n->is_CFG(), "must have CFG nodes");
3917 uint dd = dom_depth(d);
3918 while (dom_depth(n) >= dd) {
3919 if (n == d)
3920 return true;
3921 n = idom(n);
3922 }
3923 return false;
3924 }
3925
3926 //------------------------------dom_lca_for_get_late_ctrl_internal-------------
3927 // Pair-wise LCA with tags.
3928 // Tag each index with the node 'tag' currently being processed
3929 // before advancing up the dominator chain using idom().
3930 // Later calls that find a match to 'tag' know that this path has already
3931 // been considered in the current LCA (which is input 'n1' by convention).
3932 // Since get_late_ctrl() is only called once for each node, the tag array
3933 // does not need to be cleared between calls to get_late_ctrl().
3934 // Algorithm trades a larger constant factor for better asymptotic behavior
3935 //
3936 Node *PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal( Node *n1, Node *n2, Node *tag ) {
3937 uint d1 = dom_depth(n1);
3938 uint d2 = dom_depth(n2);
3939
3940 do {
3941 if (d1 > d2) {
3942 // current lca is deeper than n2
3943 _dom_lca_tags.map(n1->_idx, tag);
3944 n1 = idom(n1);
3945 d1 = dom_depth(n1);
3946 } else if (d1 < d2) {
3947 // n2 is deeper than current lca
3948 Node *memo = _dom_lca_tags[n2->_idx];
3949 if( memo == tag ) {
3950 return n1; // Return the current LCA
3951 }
3952 _dom_lca_tags.map(n2->_idx, tag);
3953 n2 = idom(n2);
3954 d2 = dom_depth(n2);
3955 } else {
3956 // Here d1 == d2. Due to edits of the dominator-tree, sections
3957 // of the tree might have the same depth. These sections have
3958 // to be searched more carefully.
3959
3960 // Scan up all the n1's with equal depth, looking for n2.
3961 _dom_lca_tags.map(n1->_idx, tag);
3962 Node *t1 = idom(n1);
3963 while (dom_depth(t1) == d1) {
3964 if (t1 == n2) return n2;
3965 _dom_lca_tags.map(t1->_idx, tag);
3966 t1 = idom(t1);
3967 }
3968 // Scan up all the n2's with equal depth, looking for n1.
3969 _dom_lca_tags.map(n2->_idx, tag);
3970 Node *t2 = idom(n2);
3971 while (dom_depth(t2) == d2) {
3972 if (t2 == n1) return n1;
3973 _dom_lca_tags.map(t2->_idx, tag);
3974 t2 = idom(t2);
3975 }
3976 // Move up to a new dominator-depth value as well as up the dom-tree.
3977 n1 = t1;
3978 n2 = t2;
3979 d1 = dom_depth(n1);
3980 d2 = dom_depth(n2);
3981 }
3982 } while (n1 != n2);
3983 return n1;
3984 }
3985
3986 //------------------------------init_dom_lca_tags------------------------------
3987 // Tag could be a node's integer index, 32bits instead of 64bits in some cases
3988 // Intended use does not involve any growth for the array, so it could
3989 // be of fixed size.
3990 void PhaseIdealLoop::init_dom_lca_tags() {
3991 uint limit = C->unique() + 1;
3992 _dom_lca_tags.map( limit, NULL );
3993 #ifdef ASSERT
3994 for( uint i = 0; i < limit; ++i ) {
3995 assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer");
3996 }
3997 #endif // ASSERT
3998 }
3999
4000 //------------------------------clear_dom_lca_tags------------------------------
4001 // Tag could be a node's integer index, 32bits instead of 64bits in some cases
4002 // Intended use does not involve any growth for the array, so it could
4003 // be of fixed size.
4004 void PhaseIdealLoop::clear_dom_lca_tags() {
4005 uint limit = C->unique() + 1;
4006 _dom_lca_tags.map( limit, NULL );
4007 _dom_lca_tags.clear();
4008 #ifdef ASSERT
4009 for( uint i = 0; i < limit; ++i ) {
4010 assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer");
4011 }
4012 #endif // ASSERT
4013 }
4014
4015 //------------------------------build_loop_late--------------------------------
4016 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
4017 // Second pass finds latest legal placement, and ideal loop placement.
4018 void PhaseIdealLoop::build_loop_late( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) {
4019 while (worklist.size() != 0) {
4020 Node *n = worklist.pop();
4021 // Only visit once
4022 if (visited.test_set(n->_idx)) continue;
4023 uint cnt = n->outcnt();
4024 uint i = 0;
4025 while (true) {
4026 assert( _nodes[n->_idx], "no dead nodes" );
4027 // Visit all children
4028 if (i < cnt) {
4029 Node* use = n->raw_out(i);
4030 ++i;
4031 // Check for dead uses. Aggressively prune such junk. It might be
4032 // dead in the global sense, but still have local uses so I cannot
4033 // easily call 'remove_dead_node'.
4034 if( _nodes[use->_idx] != NULL || use->is_top() ) { // Not dead?
4035 // Due to cycles, we might not hit the same fixed point in the verify
4036 // pass as we do in the regular pass. Instead, visit such phis as
4037 // simple uses of the loop head.
4038 if( use->in(0) && (use->is_CFG() || use->is_Phi()) ) {
4039 if( !visited.test(use->_idx) )
4040 worklist.push(use);
4041 } else if( !visited.test_set(use->_idx) ) {
4042 nstack.push(n, i); // Save parent and next use's index.
4043 n = use; // Process all children of current use.
4044 cnt = use->outcnt();
4045 i = 0;
4046 }
4047 } else {
4048 // Do not visit around the backedge of loops via data edges.
4049 // push dead code onto a worklist
4050 _deadlist.push(use);
4051 }
4052 } else {
4053 // All of n's children have been processed, complete post-processing.
4054 build_loop_late_post(n);
4055 if (nstack.is_empty()) {
4056 // Finished all nodes on stack.
4057 // Process next node on the worklist.
4058 break;
4059 }
4060 // Get saved parent node and next use's index. Visit the rest of uses.
4061 n = nstack.node();
4062 cnt = n->outcnt();
4063 i = nstack.index();
4064 nstack.pop();
4065 }
4066 }
4067 }
4068 }
4069
4070 // Verify that no data node is schedules in the outer loop of a strip
4071 // mined loop.
4072 void PhaseIdealLoop::verify_strip_mined_scheduling(Node *n, Node* least) {
4073 #ifdef ASSERT
4074 if (get_loop(least)->_nest == 0) {
4075 return;
4076 }
4077 IdealLoopTree* loop = get_loop(least);
4078 Node* head = loop->_head;
4079 if (head->is_OuterStripMinedLoop()) {
4080 Node* sfpt = head->as_Loop()->outer_safepoint();
4081 ResourceMark rm;
4082 Unique_Node_List wq;
4083 wq.push(sfpt);
4084 for (uint i = 0; i < wq.size(); i++) {
4085 Node *m = wq.at(i);
4086 for (uint i = 1; i < m->req(); i++) {
4087 Node* nn = m->in(i);
4088 if (nn == n) {
4089 return;
4090 }
4091 if (nn != NULL && has_ctrl(nn) && get_loop(get_ctrl(nn)) == loop) {
4092 wq.push(nn);
4093 }
4094 }
4095 }
4096 ShouldNotReachHere();
4097 }
4098 #endif
4099 }
4100
4101
4102 //------------------------------build_loop_late_post---------------------------
4103 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
4104 // Second pass finds latest legal placement, and ideal loop placement.
4105 void PhaseIdealLoop::build_loop_late_post( Node *n ) {
4106
4107 if (n->req() == 2 && (n->Opcode() == Op_ConvI2L || n->Opcode() == Op_CastII) && !C->major_progress() && !_verify_only) {
4108 _igvn._worklist.push(n); // Maybe we'll normalize it, if no more loops.
4109 }
4110
4111 #ifdef ASSERT
4112 if (_verify_only && !n->is_CFG()) {
4113 // Check def-use domination.
4114 compute_lca_of_uses(n, get_ctrl(n), true /* verify */);
4115 }
4116 #endif
4117
4118 // CFG and pinned nodes already handled
4119 if( n->in(0) ) {
4120 if( n->in(0)->is_top() ) return; // Dead?
4121
4122 // We'd like +VerifyLoopOptimizations to not believe that Mod's/Loads
4123 // _must_ be pinned (they have to observe their control edge of course).
4124 // Unlike Stores (which modify an unallocable resource, the memory
4125 // state), Mods/Loads can float around. So free them up.
4126 bool pinned = true;
4127 switch( n->Opcode() ) {
4128 case Op_DivI:
4129 case Op_DivF:
4130 case Op_DivD:
4131 case Op_ModI:
4132 case Op_ModF:
4133 case Op_ModD:
4134 case Op_LoadB: // Same with Loads; they can sink
4135 case Op_LoadUB: // during loop optimizations.
4136 case Op_LoadUS:
4137 case Op_LoadD:
4138 case Op_LoadF:
4139 case Op_LoadI:
4140 case Op_LoadKlass:
4141 case Op_LoadNKlass:
4142 case Op_LoadL:
4143 case Op_LoadS:
4144 case Op_LoadP:
4145 case Op_LoadBarrierSlowReg:
4146 case Op_LoadBarrierWeakSlowReg:
4147 case Op_LoadN:
4148 case Op_LoadRange:
4149 case Op_LoadD_unaligned:
4150 case Op_LoadL_unaligned:
4151 case Op_StrComp: // Does a bunch of load-like effects
4152 case Op_StrEquals:
4153 case Op_StrIndexOf:
4154 case Op_StrIndexOfChar:
4155 case Op_AryEq:
4156 case Op_HasNegatives:
4157 pinned = false;
4158 }
4159 if( pinned ) {
4160 IdealLoopTree *chosen_loop = get_loop(n->is_CFG() ? n : get_ctrl(n));
4161 if( !chosen_loop->_child ) // Inner loop?
4162 chosen_loop->_body.push(n); // Collect inner loops
4163 return;
4164 }
4165 } else { // No slot zero
4166 if( n->is_CFG() ) { // CFG with no slot 0 is dead
4167 _nodes.map(n->_idx,0); // No block setting, it's globally dead
4168 return;
4169 }
4170 assert(!n->is_CFG() || n->outcnt() == 0, "");
4171 }
4172
4173 // Do I have a "safe range" I can select over?
4174 Node *early = get_ctrl(n);// Early location already computed
4175
4176 // Compute latest point this Node can go
4177 Node *LCA = get_late_ctrl( n, early );
4178 // LCA is NULL due to uses being dead
4179 if( LCA == NULL ) {
4180 #ifdef ASSERT
4181 for (DUIterator i1 = n->outs(); n->has_out(i1); i1++) {
4182 assert( _nodes[n->out(i1)->_idx] == NULL, "all uses must also be dead");
4183 }
4184 #endif
4185 _nodes.map(n->_idx, 0); // This node is useless
4186 _deadlist.push(n);
4187 return;
4188 }
4189 assert(LCA != NULL && !LCA->is_top(), "no dead nodes");
4190
4191 Node *legal = LCA; // Walk 'legal' up the IDOM chain
4192 Node *least = legal; // Best legal position so far
4193 while( early != legal ) { // While not at earliest legal
4194 #ifdef ASSERT
4195 if (legal->is_Start() && !early->is_Root()) {
4196 // Bad graph. Print idom path and fail.
4197 dump_bad_graph("Bad graph detected in build_loop_late", n, early, LCA);
4198 assert(false, "Bad graph detected in build_loop_late");
4199 }
4200 #endif
4201 // Find least loop nesting depth
4202 legal = idom(legal); // Bump up the IDOM tree
4203 // Check for lower nesting depth
4204 if( get_loop(legal)->_nest < get_loop(least)->_nest )
4205 least = legal;
4206 }
4207 assert(early == legal || legal != C->root(), "bad dominance of inputs");
4208
4209 // Try not to place code on a loop entry projection
4210 // which can inhibit range check elimination.
4211 if (least != early) {
4212 Node* ctrl_out = least->unique_ctrl_out();
4213 if (ctrl_out && ctrl_out->is_Loop() &&
4214 least == ctrl_out->in(LoopNode::EntryControl) &&
4215 (ctrl_out->is_CountedLoop() || ctrl_out->is_OuterStripMinedLoop())) {
4216 Node* least_dom = idom(least);
4217 if (get_loop(least_dom)->is_member(get_loop(least))) {
4218 least = least_dom;
4219 }
4220 }
4221 }
4222
4223 #ifdef ASSERT
4224 // If verifying, verify that 'verify_me' has a legal location
4225 // and choose it as our location.
4226 if( _verify_me ) {
4227 Node *v_ctrl = _verify_me->get_ctrl_no_update(n);
4228 Node *legal = LCA;
4229 while( early != legal ) { // While not at earliest legal
4230 if( legal == v_ctrl ) break; // Check for prior good location
4231 legal = idom(legal) ;// Bump up the IDOM tree
4232 }
4233 // Check for prior good location
4234 if( legal == v_ctrl ) least = legal; // Keep prior if found
4235 }
4236 #endif
4237
4238 // Assign discovered "here or above" point
4239 least = find_non_split_ctrl(least);
4240 verify_strip_mined_scheduling(n, least);
4241 set_ctrl(n, least);
4242
4243 // Collect inner loop bodies
4244 IdealLoopTree *chosen_loop = get_loop(least);
4245 if( !chosen_loop->_child ) // Inner loop?
4246 chosen_loop->_body.push(n);// Collect inner loops
4247 }
4248
4249 #ifdef ASSERT
4250 void PhaseIdealLoop::dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA) {
4251 tty->print_cr("%s", msg);
4252 tty->print("n: "); n->dump();
4253 tty->print("early(n): "); early->dump();
4254 if (n->in(0) != NULL && !n->in(0)->is_top() &&
4255 n->in(0) != early && !n->in(0)->is_Root()) {
4256 tty->print("n->in(0): "); n->in(0)->dump();
4257 }
4258 for (uint i = 1; i < n->req(); i++) {
4259 Node* in1 = n->in(i);
4260 if (in1 != NULL && in1 != n && !in1->is_top()) {
4261 tty->print("n->in(%d): ", i); in1->dump();
4262 Node* in1_early = get_ctrl(in1);
4263 tty->print("early(n->in(%d)): ", i); in1_early->dump();
4264 if (in1->in(0) != NULL && !in1->in(0)->is_top() &&
4265 in1->in(0) != in1_early && !in1->in(0)->is_Root()) {
4266 tty->print("n->in(%d)->in(0): ", i); in1->in(0)->dump();
4267 }
4268 for (uint j = 1; j < in1->req(); j++) {
4269 Node* in2 = in1->in(j);
4270 if (in2 != NULL && in2 != n && in2 != in1 && !in2->is_top()) {
4271 tty->print("n->in(%d)->in(%d): ", i, j); in2->dump();
4272 Node* in2_early = get_ctrl(in2);
4273 tty->print("early(n->in(%d)->in(%d)): ", i, j); in2_early->dump();
4274 if (in2->in(0) != NULL && !in2->in(0)->is_top() &&
4275 in2->in(0) != in2_early && !in2->in(0)->is_Root()) {
4276 tty->print("n->in(%d)->in(%d)->in(0): ", i, j); in2->in(0)->dump();
4277 }
4278 }
4279 }
4280 }
4281 }
4282 tty->cr();
4283 tty->print("LCA(n): "); LCA->dump();
4284 for (uint i = 0; i < n->outcnt(); i++) {
4285 Node* u1 = n->raw_out(i);
4286 if (u1 == n)
4287 continue;
4288 tty->print("n->out(%d): ", i); u1->dump();
4289 if (u1->is_CFG()) {
4290 for (uint j = 0; j < u1->outcnt(); j++) {
4291 Node* u2 = u1->raw_out(j);
4292 if (u2 != u1 && u2 != n && u2->is_CFG()) {
4293 tty->print("n->out(%d)->out(%d): ", i, j); u2->dump();
4294 }
4295 }
4296 } else {
4297 Node* u1_later = get_ctrl(u1);
4298 tty->print("later(n->out(%d)): ", i); u1_later->dump();
4299 if (u1->in(0) != NULL && !u1->in(0)->is_top() &&
4300 u1->in(0) != u1_later && !u1->in(0)->is_Root()) {
4301 tty->print("n->out(%d)->in(0): ", i); u1->in(0)->dump();
4302 }
4303 for (uint j = 0; j < u1->outcnt(); j++) {
4304 Node* u2 = u1->raw_out(j);
4305 if (u2 == n || u2 == u1)
4306 continue;
4307 tty->print("n->out(%d)->out(%d): ", i, j); u2->dump();
4308 if (!u2->is_CFG()) {
4309 Node* u2_later = get_ctrl(u2);
4310 tty->print("later(n->out(%d)->out(%d)): ", i, j); u2_later->dump();
4311 if (u2->in(0) != NULL && !u2->in(0)->is_top() &&
4312 u2->in(0) != u2_later && !u2->in(0)->is_Root()) {
4313 tty->print("n->out(%d)->in(0): ", i); u2->in(0)->dump();
4314 }
4315 }
4316 }
4317 }
4318 }
4319 tty->cr();
4320 int ct = 0;
4321 Node *dbg_legal = LCA;
4322 while(!dbg_legal->is_Start() && ct < 100) {
4323 tty->print("idom[%d] ",ct); dbg_legal->dump();
4324 ct++;
4325 dbg_legal = idom(dbg_legal);
4326 }
4327 tty->cr();
4328 }
4329 #endif
4330
4331 #ifndef PRODUCT
4332 //------------------------------dump-------------------------------------------
4333 void PhaseIdealLoop::dump( ) const {
4334 ResourceMark rm;
4335 Arena* arena = Thread::current()->resource_area();
4336 Node_Stack stack(arena, C->live_nodes() >> 2);
4337 Node_List rpo_list;
4338 VectorSet visited(arena);
4339 visited.set(C->top()->_idx);
4340 rpo( C->root(), stack, visited, rpo_list );
4341 // Dump root loop indexed by last element in PO order
4342 dump( _ltree_root, rpo_list.size(), rpo_list );
4343 }
4344
4345 void PhaseIdealLoop::dump( IdealLoopTree *loop, uint idx, Node_List &rpo_list ) const {
4346 loop->dump_head();
4347
4348 // Now scan for CFG nodes in the same loop
4349 for( uint j=idx; j > 0; j-- ) {
4350 Node *n = rpo_list[j-1];
4351 if( !_nodes[n->_idx] ) // Skip dead nodes
4352 continue;
4353 if( get_loop(n) != loop ) { // Wrong loop nest
4354 if( get_loop(n)->_head == n && // Found nested loop?
4355 get_loop(n)->_parent == loop )
4356 dump(get_loop(n),rpo_list.size(),rpo_list); // Print it nested-ly
4357 continue;
4358 }
4359
4360 // Dump controlling node
4361 for( uint x = 0; x < loop->_nest; x++ )
4362 tty->print(" ");
4363 tty->print("C");
4364 if( n == C->root() ) {
4365 n->dump();
4366 } else {
4367 Node* cached_idom = idom_no_update(n);
4368 Node *computed_idom = n->in(0);
4369 if( n->is_Region() ) {
4370 computed_idom = compute_idom(n);
4371 // computed_idom() will return n->in(0) when idom(n) is an IfNode (or
4372 // any MultiBranch ctrl node), so apply a similar transform to
4373 // the cached idom returned from idom_no_update.
4374 cached_idom = find_non_split_ctrl(cached_idom);
4375 }
4376 tty->print(" ID:%d",computed_idom->_idx);
4377 n->dump();
4378 if( cached_idom != computed_idom ) {
4379 tty->print_cr("*** BROKEN IDOM! Computed as: %d, cached as: %d",
4380 computed_idom->_idx, cached_idom->_idx);
4381 }
4382 }
4383 // Dump nodes it controls
4384 for( uint k = 0; k < _nodes.Size(); k++ ) {
4385 // (k < C->unique() && get_ctrl(find(k)) == n)
4386 if (k < C->unique() && _nodes[k] == (Node*)((intptr_t)n + 1)) {
4387 Node *m = C->root()->find(k);
4388 if( m && m->outcnt() > 0 ) {
4389 if (!(has_ctrl(m) && get_ctrl_no_update(m) == n)) {
4390 tty->print_cr("*** BROKEN CTRL ACCESSOR! _nodes[k] is %p, ctrl is %p",
4391 _nodes[k], has_ctrl(m) ? get_ctrl_no_update(m) : NULL);
4392 }
4393 for( uint j = 0; j < loop->_nest; j++ )
4394 tty->print(" ");
4395 tty->print(" ");
4396 m->dump();
4397 }
4398 }
4399 }
4400 }
4401 }
4402
4403 // Collect a R-P-O for the whole CFG.
4404 // Result list is in post-order (scan backwards for RPO)
4405 void PhaseIdealLoop::rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const {
4406 stk.push(start, 0);
4407 visited.set(start->_idx);
4408
4409 while (stk.is_nonempty()) {
4410 Node* m = stk.node();
4411 uint idx = stk.index();
4412 if (idx < m->outcnt()) {
4413 stk.set_index(idx + 1);
4414 Node* n = m->raw_out(idx);
4415 if (n->is_CFG() && !visited.test_set(n->_idx)) {
4416 stk.push(n, 0);
4417 }
4418 } else {
4419 rpo_list.push(m);
4420 stk.pop();
4421 }
4422 }
4423 }
4424 #endif
4425
4426
4427 //=============================================================================
4428 //------------------------------LoopTreeIterator-----------------------------------
4429
4430 // Advance to next loop tree using a preorder, left-to-right traversal.
4431 void LoopTreeIterator::next() {
4432 assert(!done(), "must not be done.");
4433 if (_curnt->_child != NULL) {
4434 _curnt = _curnt->_child;
4435 } else if (_curnt->_next != NULL) {
4436 _curnt = _curnt->_next;
4437 } else {
4438 while (_curnt != _root && _curnt->_next == NULL) {
4439 _curnt = _curnt->_parent;
4440 }
4441 if (_curnt == _root) {
4442 _curnt = NULL;
4443 assert(done(), "must be done.");
4444 } else {
4445 assert(_curnt->_next != NULL, "must be more to do");
4446 _curnt = _curnt->_next;
4447 }
4448 }
4449 }