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