1 /*
2 * Copyright (c) 2011, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "opto/loopnode.hpp"
27 #include "opto/addnode.hpp"
28 #include "opto/callnode.hpp"
29 #include "opto/connode.hpp"
30 #include "opto/convertnode.hpp"
31 #include "opto/loopnode.hpp"
32 #include "opto/matcher.hpp"
33 #include "opto/mulnode.hpp"
34 #include "opto/opaquenode.hpp"
35 #include "opto/rootnode.hpp"
36 #include "opto/subnode.hpp"
37 #include <fenv.h>
38 #include <math.h>
39
40 /*
41 * The general idea of Loop Predication is to insert a predicate on the entry
42 * path to a loop, and raise a uncommon trap if the check of the condition fails.
43 * The condition checks are promoted from inside the loop body, and thus
44 * the checks inside the loop could be eliminated. Currently, loop predication
45 * optimization has been applied to remove array range check and loop invariant
46 * checks (such as null checks).
47 */
48
49 //-------------------------------register_control-------------------------
50 void PhaseIdealLoop::register_control(Node* n, IdealLoopTree *loop, Node* pred) {
51 assert(n->is_CFG(), "must be control node");
52 _igvn.register_new_node_with_optimizer(n);
53 loop->_body.push(n);
54 set_loop(n, loop);
55 // When called from beautify_loops() idom is not constructed yet.
56 if (_idom != NULL) {
57 set_idom(n, pred, dom_depth(pred));
58 }
59 }
60
61 //------------------------------create_new_if_for_predicate------------------------
62 // create a new if above the uct_if_pattern for the predicate to be promoted.
63 //
64 // before after
65 // ---------- ----------
66 // ctrl ctrl
67 // | |
68 // | |
69 // v v
70 // iff new_iff
71 // / \ / \
72 // / \ / \
73 // v v v v
74 // uncommon_proj cont_proj if_uct if_cont
75 // \ | | | |
76 // \ | | | |
77 // v v v | v
78 // rgn loop | iff
79 // | | / \
80 // | | / \
81 // v | v v
82 // uncommon_trap | uncommon_proj cont_proj
83 // \ \ | |
84 // \ \ | |
85 // v v v v
86 // rgn loop
87 // |
88 // |
89 // v
90 // uncommon_trap
91 //
92 //
93 // We will create a region to guard the uct call if there is no one there.
94 // The true projecttion (if_cont) of the new_iff is returned.
95 // This code is also used to clone predicates to cloned loops.
96 ProjNode* PhaseIdealLoop::create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry,
97 Deoptimization::DeoptReason reason,
98 int opcode) {
99 assert(cont_proj->is_uncommon_trap_if_pattern(reason), "must be a uct if pattern!");
100 IfNode* iff = cont_proj->in(0)->as_If();
101
102 ProjNode *uncommon_proj = iff->proj_out(1 - cont_proj->_con);
103 Node *rgn = uncommon_proj->unique_ctrl_out();
104 assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct");
105
106 uint proj_index = 1; // region's edge corresponding to uncommon_proj
107 if (!rgn->is_Region()) { // create a region to guard the call
108 assert(rgn->is_Call(), "must be call uct");
109 CallNode* call = rgn->as_Call();
110 IdealLoopTree* loop = get_loop(call);
111 rgn = new RegionNode(1);
112 rgn->add_req(uncommon_proj);
113 register_control(rgn, loop, uncommon_proj);
114 _igvn.replace_input_of(call, 0, rgn);
115 // When called from beautify_loops() idom is not constructed yet.
116 if (_idom != NULL) {
117 set_idom(call, rgn, dom_depth(rgn));
118 }
119 for (DUIterator_Fast imax, i = uncommon_proj->fast_outs(imax); i < imax; i++) {
120 Node* n = uncommon_proj->fast_out(i);
121 if (n->is_Load() || n->is_Store()) {
122 _igvn.replace_input_of(n, 0, rgn);
123 --i; --imax;
124 }
125 }
126 } else {
127 // Find region's edge corresponding to uncommon_proj
128 for (; proj_index < rgn->req(); proj_index++)
129 if (rgn->in(proj_index) == uncommon_proj) break;
130 assert(proj_index < rgn->req(), "sanity");
131 }
132
133 Node* entry = iff->in(0);
134 if (new_entry != NULL) {
135 // Clonning the predicate to new location.
136 entry = new_entry;
137 }
138 // Create new_iff
139 IdealLoopTree* lp = get_loop(entry);
140 IfNode* new_iff = NULL;
141 if (opcode == Op_If) {
142 new_iff = new IfNode(entry, iff->in(1), iff->_prob, iff->_fcnt);
143 } else {
144 assert(opcode == Op_RangeCheck, "no other if variant here");
145 new_iff = new RangeCheckNode(entry, iff->in(1), iff->_prob, iff->_fcnt);
146 }
147 register_control(new_iff, lp, entry);
148 Node *if_cont = new IfTrueNode(new_iff);
149 Node *if_uct = new IfFalseNode(new_iff);
150 if (cont_proj->is_IfFalse()) {
151 // Swap
152 Node* tmp = if_uct; if_uct = if_cont; if_cont = tmp;
153 }
154 register_control(if_cont, lp, new_iff);
155 register_control(if_uct, get_loop(rgn), new_iff);
156
157 // if_uct to rgn
158 _igvn.hash_delete(rgn);
159 rgn->add_req(if_uct);
160 // When called from beautify_loops() idom is not constructed yet.
161 if (_idom != NULL) {
162 Node* ridom = idom(rgn);
163 Node* nrdom = dom_lca(ridom, new_iff);
164 set_idom(rgn, nrdom, dom_depth(rgn));
165 }
166
167 // If rgn has phis add new edges which has the same
168 // value as on original uncommon_proj pass.
169 assert(rgn->in(rgn->req() -1) == if_uct, "new edge should be last");
170 bool has_phi = false;
171 for (DUIterator_Fast imax, i = rgn->fast_outs(imax); i < imax; i++) {
172 Node* use = rgn->fast_out(i);
173 if (use->is_Phi() && use->outcnt() > 0) {
174 assert(use->in(0) == rgn, "");
175 _igvn.rehash_node_delayed(use);
176 use->add_req(use->in(proj_index));
177 has_phi = true;
178 }
179 }
180 assert(!has_phi || rgn->req() > 3, "no phis when region is created");
181
182 if (new_entry == NULL) {
183 // Attach if_cont to iff
184 _igvn.replace_input_of(iff, 0, if_cont);
185 if (_idom != NULL) {
186 set_idom(iff, if_cont, dom_depth(iff));
187 }
188 }
189 return if_cont->as_Proj();
190 }
191
192 //------------------------------create_new_if_for_predicate------------------------
193 // Create a new if below new_entry for the predicate to be cloned (IGVN optimization)
194 ProjNode* PhaseIterGVN::create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry,
195 Deoptimization::DeoptReason reason,
196 int opcode) {
197 assert(new_entry != 0, "only used for clone predicate");
198 assert(cont_proj->is_uncommon_trap_if_pattern(reason), "must be a uct if pattern!");
199 IfNode* iff = cont_proj->in(0)->as_If();
200
201 ProjNode *uncommon_proj = iff->proj_out(1 - cont_proj->_con);
202 Node *rgn = uncommon_proj->unique_ctrl_out();
203 assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct");
204
205 uint proj_index = 1; // region's edge corresponding to uncommon_proj
206 if (!rgn->is_Region()) { // create a region to guard the call
207 assert(rgn->is_Call(), "must be call uct");
208 CallNode* call = rgn->as_Call();
209 rgn = new RegionNode(1);
210 register_new_node_with_optimizer(rgn);
211 rgn->add_req(uncommon_proj);
212 replace_input_of(call, 0, rgn);
213 } else {
214 // Find region's edge corresponding to uncommon_proj
215 for (; proj_index < rgn->req(); proj_index++)
216 if (rgn->in(proj_index) == uncommon_proj) break;
217 assert(proj_index < rgn->req(), "sanity");
218 }
219
220 // Create new_iff in new location.
221 IfNode* new_iff = NULL;
222 if (opcode == Op_If) {
223 new_iff = new IfNode(new_entry, iff->in(1), iff->_prob, iff->_fcnt);
224 } else {
225 assert(opcode == Op_RangeCheck, "no other if variant here");
226 new_iff = new RangeCheckNode(new_entry, iff->in(1), iff->_prob, iff->_fcnt);
227 }
228
229 register_new_node_with_optimizer(new_iff);
230 Node *if_cont = new IfTrueNode(new_iff);
231 Node *if_uct = new IfFalseNode(new_iff);
232 if (cont_proj->is_IfFalse()) {
233 // Swap
234 Node* tmp = if_uct; if_uct = if_cont; if_cont = tmp;
235 }
236 register_new_node_with_optimizer(if_cont);
237 register_new_node_with_optimizer(if_uct);
238
239 // if_uct to rgn
240 hash_delete(rgn);
241 rgn->add_req(if_uct);
242
243 // If rgn has phis add corresponding new edges which has the same
244 // value as on original uncommon_proj pass.
245 assert(rgn->in(rgn->req() -1) == if_uct, "new edge should be last");
246 bool has_phi = false;
247 for (DUIterator_Fast imax, i = rgn->fast_outs(imax); i < imax; i++) {
248 Node* use = rgn->fast_out(i);
249 if (use->is_Phi() && use->outcnt() > 0) {
250 rehash_node_delayed(use);
251 use->add_req(use->in(proj_index));
252 has_phi = true;
253 }
254 }
255 assert(!has_phi || rgn->req() > 3, "no phis when region is created");
256
257 return if_cont->as_Proj();
258 }
259
260 //--------------------------clone_predicate-----------------------
261 ProjNode* PhaseIdealLoop::clone_predicate(ProjNode* predicate_proj, Node* new_entry,
262 Deoptimization::DeoptReason reason,
263 PhaseIdealLoop* loop_phase,
264 PhaseIterGVN* igvn) {
265 ProjNode* new_predicate_proj;
266 if (loop_phase != NULL) {
267 new_predicate_proj = loop_phase->create_new_if_for_predicate(predicate_proj, new_entry, reason, Op_If);
268 } else {
269 new_predicate_proj = igvn->create_new_if_for_predicate(predicate_proj, new_entry, reason, Op_If);
270 }
271 IfNode* iff = new_predicate_proj->in(0)->as_If();
272 Node* ctrl = iff->in(0);
273
274 // Match original condition since predicate's projections could be swapped.
275 assert(predicate_proj->in(0)->in(1)->in(1)->Opcode()==Op_Opaque1, "must be");
276 Node* opq = new Opaque1Node(igvn->C, predicate_proj->in(0)->in(1)->in(1)->in(1));
277 igvn->C->add_predicate_opaq(opq);
278
279 Node* bol = new Conv2BNode(opq);
280 if (loop_phase != NULL) {
281 loop_phase->register_new_node(opq, ctrl);
282 loop_phase->register_new_node(bol, ctrl);
283 } else {
284 igvn->register_new_node_with_optimizer(opq);
285 igvn->register_new_node_with_optimizer(bol);
286 }
287 igvn->hash_delete(iff);
288 iff->set_req(1, bol);
289 return new_predicate_proj;
290 }
291
292
293 //--------------------------clone_loop_predicates-----------------------
294 // Interface from IGVN
295 Node* PhaseIterGVN::clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) {
296 return PhaseIdealLoop::clone_loop_predicates(old_entry, new_entry, clone_limit_check, NULL, this);
297 }
298
299 // Interface from PhaseIdealLoop
300 Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) {
301 return clone_loop_predicates(old_entry, new_entry, clone_limit_check, this, &this->_igvn);
302 }
303
304 // Clone loop predicates to cloned loops (peeled, unswitched, split_if).
305 Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry,
306 bool clone_limit_check,
307 PhaseIdealLoop* loop_phase,
308 PhaseIterGVN* igvn) {
309 #ifdef ASSERT
310 if (new_entry == NULL || !(new_entry->is_Proj() || new_entry->is_Region() || new_entry->is_SafePoint())) {
311 if (new_entry != NULL)
312 new_entry->dump();
313 assert(false, "not IfTrue, IfFalse, Region or SafePoint");
314 }
315 #endif
316 // Search original predicates
317 Node* entry = old_entry;
318 ProjNode* limit_check_proj = NULL;
319 limit_check_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
320 if (limit_check_proj != NULL) {
321 entry = entry->in(0)->in(0);
322 }
323 ProjNode* profile_predicate_proj = NULL;
324 ProjNode* predicate_proj = NULL;
325 if (UseProfiledLoopPredicate) {
326 profile_predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_profile_predicate);
327 if (profile_predicate_proj != NULL) {
328 entry = skip_loop_predicates(entry);
329 }
330 }
331 if (UseLoopPredicate) {
332 predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
333 }
334 if (predicate_proj != NULL) { // right pattern that can be used by loop predication
335 // clone predicate
336 new_entry = clone_predicate(predicate_proj, new_entry,
337 Deoptimization::Reason_predicate,
338 loop_phase, igvn);
339 assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone predicate");
340 if (TraceLoopPredicate) {
341 tty->print("Loop Predicate cloned: ");
342 debug_only( new_entry->in(0)->dump(); );
343 }
344 }
345 if (profile_predicate_proj != NULL) { // right pattern that can be used by loop predication
346 // clone predicate
347 new_entry = clone_predicate(profile_predicate_proj, new_entry,
348 Deoptimization::Reason_profile_predicate,
349 loop_phase, igvn);
350 assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone predicate");
351 if (TraceLoopPredicate) {
352 tty->print("Loop Predicate cloned: ");
353 debug_only( new_entry->in(0)->dump(); );
354 }
355 }
356 if (limit_check_proj != NULL && clone_limit_check) {
357 // Clone loop limit check last to insert it before loop.
358 // Don't clone a limit check which was already finalized
359 // for this counted loop (only one limit check is needed).
360 new_entry = clone_predicate(limit_check_proj, new_entry,
361 Deoptimization::Reason_loop_limit_check,
362 loop_phase, igvn);
363 assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone limit check");
364 if (TraceLoopLimitCheck) {
365 tty->print("Loop Limit Check cloned: ");
366 debug_only( new_entry->in(0)->dump(); )
367 }
368 }
369 return new_entry;
370 }
371
372 //--------------------------skip_loop_predicates------------------------------
373 // Skip related predicates.
374 Node* PhaseIdealLoop::skip_loop_predicates(Node* entry) {
375 IfNode* iff = entry->in(0)->as_If();
376 ProjNode* uncommon_proj = iff->proj_out(1 - entry->as_Proj()->_con);
377 Node* rgn = uncommon_proj->unique_ctrl_out();
378 assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct");
379 entry = entry->in(0)->in(0);
380 while (entry != NULL && entry->is_Proj() && entry->in(0)->is_If()) {
381 uncommon_proj = entry->in(0)->as_If()->proj_out(1 - entry->as_Proj()->_con);
382 if (uncommon_proj->unique_ctrl_out() != rgn)
383 break;
384 entry = entry->in(0)->in(0);
385 }
386 return entry;
387 }
388
389 Node* PhaseIdealLoop::skip_all_loop_predicates(Node* entry) {
390 Node* predicate = NULL;
391 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
392 if (predicate != NULL) {
393 entry = entry->in(0)->in(0);
394 }
395 if (UseProfiledLoopPredicate) {
396 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_profile_predicate);
397 if (predicate != NULL) { // right pattern that can be used by loop predication
398 entry = skip_loop_predicates(entry);
399 }
400 }
401 if (UseLoopPredicate) {
402 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
403 if (predicate != NULL) { // right pattern that can be used by loop predication
404 entry = skip_loop_predicates(entry);
405 }
406 }
407 return entry;
408 }
409
410 //--------------------------find_predicate_insertion_point-------------------
411 // Find a good location to insert a predicate
412 ProjNode* PhaseIdealLoop::find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason) {
413 if (start_c == NULL || !start_c->is_Proj())
414 return NULL;
415 if (start_c->as_Proj()->is_uncommon_trap_if_pattern(reason)) {
416 return start_c->as_Proj();
417 }
418 return NULL;
419 }
420
421 //--------------------------find_predicate------------------------------------
422 // Find a predicate
423 Node* PhaseIdealLoop::find_predicate(Node* entry) {
424 Node* predicate = NULL;
425 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
426 if (predicate != NULL) { // right pattern that can be used by loop predication
427 return entry;
428 }
429 if (UseLoopPredicate) {
430 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
431 if (predicate != NULL) { // right pattern that can be used by loop predication
432 return entry;
433 }
434 }
435 if (UseProfiledLoopPredicate) {
436 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_profile_predicate);
437 if (predicate != NULL) { // right pattern that can be used by loop predication
438 return entry;
439 }
440 }
441 return NULL;
442 }
443
444 //------------------------------Invariance-----------------------------------
445 // Helper class for loop_predication_impl to compute invariance on the fly and
446 // clone invariants.
447 class Invariance : public StackObj {
448 VectorSet _visited, _invariant;
449 Node_Stack _stack;
450 VectorSet _clone_visited;
451 Node_List _old_new; // map of old to new (clone)
452 IdealLoopTree* _lpt;
453 PhaseIdealLoop* _phase;
454
455 // Helper function to set up the invariance for invariance computation
456 // If n is a known invariant, set up directly. Otherwise, look up the
457 // the possibility to push n onto the stack for further processing.
458 void visit(Node* use, Node* n) {
459 if (_lpt->is_invariant(n)) { // known invariant
460 _invariant.set(n->_idx);
461 } else if (!n->is_CFG()) {
462 Node *n_ctrl = _phase->ctrl_or_self(n);
463 Node *u_ctrl = _phase->ctrl_or_self(use); // self if use is a CFG
464 if (_phase->is_dominator(n_ctrl, u_ctrl)) {
465 _stack.push(n, n->in(0) == NULL ? 1 : 0);
466 }
467 }
468 }
469
470 // Compute invariance for "the_node" and (possibly) all its inputs recursively
471 // on the fly
472 void compute_invariance(Node* n) {
473 assert(_visited.test(n->_idx), "must be");
474 visit(n, n);
475 while (_stack.is_nonempty()) {
476 Node* n = _stack.node();
477 uint idx = _stack.index();
478 if (idx == n->req()) { // all inputs are processed
479 _stack.pop();
480 // n is invariant if it's inputs are all invariant
481 bool all_inputs_invariant = true;
482 for (uint i = 0; i < n->req(); i++) {
483 Node* in = n->in(i);
484 if (in == NULL) continue;
485 assert(_visited.test(in->_idx), "must have visited input");
486 if (!_invariant.test(in->_idx)) { // bad guy
487 all_inputs_invariant = false;
488 break;
489 }
490 }
491 if (all_inputs_invariant) {
492 // If n's control is a predicate that was moved out of the
493 // loop, it was marked invariant but n is only invariant if
494 // it depends only on that test. Otherwise, unless that test
495 // is out of the loop, it's not invariant.
496 if (n->is_CFG() || n->depends_only_on_test() || n->in(0) == NULL || !_phase->is_member(_lpt, n->in(0))) {
497 _invariant.set(n->_idx); // I am a invariant too
498 }
499 }
500 } else { // process next input
501 _stack.set_index(idx + 1);
502 Node* m = n->in(idx);
503 if (m != NULL && !_visited.test_set(m->_idx)) {
504 visit(n, m);
505 }
506 }
507 }
508 }
509
510 // Helper function to set up _old_new map for clone_nodes.
511 // If n is a known invariant, set up directly ("clone" of n == n).
512 // Otherwise, push n onto the stack for real cloning.
513 void clone_visit(Node* n) {
514 assert(_invariant.test(n->_idx), "must be invariant");
515 if (_lpt->is_invariant(n)) { // known invariant
516 _old_new.map(n->_idx, n);
517 } else { // to be cloned
518 assert(!n->is_CFG(), "should not see CFG here");
519 _stack.push(n, n->in(0) == NULL ? 1 : 0);
520 }
521 }
522
523 // Clone "n" and (possibly) all its inputs recursively
524 void clone_nodes(Node* n, Node* ctrl) {
525 clone_visit(n);
526 while (_stack.is_nonempty()) {
527 Node* n = _stack.node();
528 uint idx = _stack.index();
529 if (idx == n->req()) { // all inputs processed, clone n!
530 _stack.pop();
531 // clone invariant node
532 Node* n_cl = n->clone();
533 _old_new.map(n->_idx, n_cl);
534 _phase->register_new_node(n_cl, ctrl);
535 for (uint i = 0; i < n->req(); i++) {
536 Node* in = n_cl->in(i);
537 if (in == NULL) continue;
538 n_cl->set_req(i, _old_new[in->_idx]);
539 }
540 } else { // process next input
541 _stack.set_index(idx + 1);
542 Node* m = n->in(idx);
543 if (m != NULL && !_clone_visited.test_set(m->_idx)) {
544 clone_visit(m); // visit the input
545 }
546 }
547 }
548 }
549
550 public:
551 Invariance(Arena* area, IdealLoopTree* lpt) :
552 _lpt(lpt), _phase(lpt->_phase),
553 _visited(area), _invariant(area), _stack(area, 10 /* guess */),
554 _clone_visited(area), _old_new(area)
555 {
556 LoopNode* head = _lpt->_head->as_Loop();
557 Node* entry = head->skip_strip_mined()->in(LoopNode::EntryControl);
558 if (entry->outcnt() != 1) {
559 // If a node is pinned between the predicates and the loop
560 // entry, we won't be able to move any node in the loop that
561 // depends on it above it in a predicate. Mark all those nodes
562 // as non loop invariatnt.
563 Unique_Node_List wq;
564 wq.push(entry);
565 for (uint next = 0; next < wq.size(); ++next) {
566 Node *n = wq.at(next);
567 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
568 Node* u = n->fast_out(i);
569 if (!u->is_CFG()) {
570 Node* c = _phase->get_ctrl(u);
571 if (_lpt->is_member(_phase->get_loop(c)) || _phase->is_dominator(c, head)) {
572 _visited.set(u->_idx);
573 wq.push(u);
574 }
575 }
576 }
577 }
578 }
579 }
580
581 // Map old to n for invariance computation and clone
582 void map_ctrl(Node* old, Node* n) {
583 assert(old->is_CFG() && n->is_CFG(), "must be");
584 _old_new.map(old->_idx, n); // "clone" of old is n
585 _invariant.set(old->_idx); // old is invariant
586 _clone_visited.set(old->_idx);
587 }
588
589 // Driver function to compute invariance
590 bool is_invariant(Node* n) {
591 if (!_visited.test_set(n->_idx))
592 compute_invariance(n);
593 return (_invariant.test(n->_idx) != 0);
594 }
595
596 // Driver function to clone invariant
597 Node* clone(Node* n, Node* ctrl) {
598 assert(ctrl->is_CFG(), "must be");
599 assert(_invariant.test(n->_idx), "must be an invariant");
600 if (!_clone_visited.test(n->_idx))
601 clone_nodes(n, ctrl);
602 return _old_new[n->_idx];
603 }
604 };
605
606 //------------------------------is_range_check_if -----------------------------------
607 // Returns true if the predicate of iff is in "scale*iv + offset u< load_range(ptr)" format
608 // Note: this function is particularly designed for loop predication. We require load_range
609 // and offset to be loop invariant computed on the fly by "invar"
610 bool IdealLoopTree::is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const {
611 if (!is_loop_exit(iff)) {
612 return false;
613 }
614 if (!iff->in(1)->is_Bool()) {
615 return false;
616 }
617 const BoolNode *bol = iff->in(1)->as_Bool();
618 if (bol->_test._test != BoolTest::lt) {
619 return false;
620 }
621 if (!bol->in(1)->is_Cmp()) {
622 return false;
623 }
624 const CmpNode *cmp = bol->in(1)->as_Cmp();
625 if (cmp->Opcode() != Op_CmpU) {
626 return false;
627 }
628 Node* range = cmp->in(2);
629 if (range->Opcode() != Op_LoadRange && !iff->is_RangeCheck()) {
630 const TypeInt* tint = phase->_igvn.type(range)->isa_int();
631 if (tint == NULL || tint->empty() || tint->_lo < 0) {
632 // Allow predication on positive values that aren't LoadRanges.
633 // This allows optimization of loops where the length of the
634 // array is a known value and doesn't need to be loaded back
635 // from the array.
636 return false;
637 }
638 }
639 if (!invar.is_invariant(range)) {
640 return false;
641 }
642 Node *iv = _head->as_CountedLoop()->phi();
643 int scale = 0;
644 Node *offset = NULL;
645 if (!phase->is_scaled_iv_plus_offset(cmp->in(1), iv, &scale, &offset)) {
646 return false;
647 }
648 if (offset && !invar.is_invariant(offset)) { // offset must be invariant
649 return false;
650 }
651 return true;
652 }
653
654 //------------------------------rc_predicate-----------------------------------
655 // Create a range check predicate
656 //
657 // for (i = init; i < limit; i += stride) {
658 // a[scale*i+offset]
659 // }
660 //
661 // Compute max(scale*i + offset) for init <= i < limit and build the predicate
662 // as "max(scale*i + offset) u< a.length".
663 //
664 // There are two cases for max(scale*i + offset):
665 // (1) stride*scale > 0
666 // max(scale*i + offset) = scale*(limit-stride) + offset
667 // (2) stride*scale < 0
668 // max(scale*i + offset) = scale*init + offset
669 BoolNode* PhaseIdealLoop::rc_predicate(IdealLoopTree *loop, Node* ctrl,
670 int scale, Node* offset,
671 Node* init, Node* limit, jint stride,
672 Node* range, bool upper, bool &overflow) {
673 jint con_limit = (limit != NULL && limit->is_Con()) ? limit->get_int() : 0;
674 jint con_init = init->is_Con() ? init->get_int() : 0;
675 jint con_offset = offset->is_Con() ? offset->get_int() : 0;
676
677 stringStream* predString = NULL;
678 if (TraceLoopPredicate) {
679 predString = new stringStream();
680 predString->print("rc_predicate ");
681 }
682
683 overflow = false;
684 Node* max_idx_expr = NULL;
685 const TypeInt* idx_type = TypeInt::INT;
686 if ((stride > 0) == (scale > 0) == upper) {
687 if (TraceLoopPredicate) {
688 if (limit->is_Con()) {
689 predString->print("(%d ", con_limit);
690 } else {
691 predString->print("(limit ");
692 }
693 predString->print("- %d) ", stride);
694 }
695 // Check if (limit - stride) may overflow
696 const TypeInt* limit_type = _igvn.type(limit)->isa_int();
697 jint limit_lo = limit_type->_lo;
698 jint limit_hi = limit_type->_hi;
699 if ((stride > 0 && (java_subtract(limit_lo, stride) < limit_lo)) ||
700 (stride < 0 && (java_subtract(limit_hi, stride) > limit_hi))) {
701 // No overflow possible
702 ConINode* con_stride = _igvn.intcon(stride);
703 set_ctrl(con_stride, C->root());
704 max_idx_expr = new SubINode(limit, con_stride);
705 idx_type = TypeInt::make(limit_lo - stride, limit_hi - stride, limit_type->_widen);
706 } else {
707 // May overflow
708 overflow = true;
709 limit = new ConvI2LNode(limit);
710 register_new_node(limit, ctrl);
711 ConLNode* con_stride = _igvn.longcon(stride);
712 set_ctrl(con_stride, C->root());
713 max_idx_expr = new SubLNode(limit, con_stride);
714 }
715 register_new_node(max_idx_expr, ctrl);
716 } else {
717 if (TraceLoopPredicate) {
718 if (init->is_Con()) {
719 predString->print("%d ", con_init);
720 } else {
721 predString->print("init ");
722 }
723 }
724 idx_type = _igvn.type(init)->isa_int();
725 max_idx_expr = init;
726 }
727
728 if (scale != 1) {
729 ConNode* con_scale = _igvn.intcon(scale);
730 set_ctrl(con_scale, C->root());
731 if (TraceLoopPredicate) {
732 predString->print("* %d ", scale);
733 }
734 // Check if (scale * max_idx_expr) may overflow
735 const TypeInt* scale_type = TypeInt::make(scale);
736 MulINode* mul = new MulINode(max_idx_expr, con_scale);
737 idx_type = (TypeInt*)mul->mul_ring(idx_type, scale_type);
738 if (overflow || TypeInt::INT->higher_equal(idx_type)) {
739 // May overflow
740 mul->destruct();
741 if (!overflow) {
742 max_idx_expr = new ConvI2LNode(max_idx_expr);
743 register_new_node(max_idx_expr, ctrl);
744 }
745 overflow = true;
746 con_scale = _igvn.longcon(scale);
747 set_ctrl(con_scale, C->root());
748 max_idx_expr = new MulLNode(max_idx_expr, con_scale);
749 } else {
750 // No overflow possible
751 max_idx_expr = mul;
752 }
753 register_new_node(max_idx_expr, ctrl);
754 }
755
756 if (offset && (!offset->is_Con() || con_offset != 0)){
757 if (TraceLoopPredicate) {
758 if (offset->is_Con()) {
759 predString->print("+ %d ", con_offset);
760 } else {
761 predString->print("+ offset");
762 }
763 }
764 // Check if (max_idx_expr + offset) may overflow
765 const TypeInt* offset_type = _igvn.type(offset)->isa_int();
766 jint lo = java_add(idx_type->_lo, offset_type->_lo);
767 jint hi = java_add(idx_type->_hi, offset_type->_hi);
768 if (overflow || (lo > hi) ||
769 ((idx_type->_lo & offset_type->_lo) < 0 && lo >= 0) ||
770 ((~(idx_type->_hi | offset_type->_hi)) < 0 && hi < 0)) {
771 // May overflow
772 if (!overflow) {
773 max_idx_expr = new ConvI2LNode(max_idx_expr);
774 register_new_node(max_idx_expr, ctrl);
775 }
776 overflow = true;
777 offset = new ConvI2LNode(offset);
778 register_new_node(offset, ctrl);
779 max_idx_expr = new AddLNode(max_idx_expr, offset);
780 } else {
781 // No overflow possible
782 max_idx_expr = new AddINode(max_idx_expr, offset);
783 }
784 register_new_node(max_idx_expr, ctrl);
785 }
786
787 CmpNode* cmp = NULL;
788 if (overflow) {
789 // Integer expressions may overflow, do long comparison
790 range = new ConvI2LNode(range);
791 register_new_node(range, ctrl);
792 cmp = new CmpULNode(max_idx_expr, range);
793 } else {
794 cmp = new CmpUNode(max_idx_expr, range);
795 }
796 register_new_node(cmp, ctrl);
797 BoolNode* bol = new BoolNode(cmp, BoolTest::lt);
798 register_new_node(bol, ctrl);
799
800 if (TraceLoopPredicate) {
801 predString->print_cr("<u range");
802 tty->print("%s", predString->as_string());
803 }
804 return bol;
805 }
806
807 // Should loop predication look not only in the path from tail to head
808 // but also in branches of the loop body?
809 bool PhaseIdealLoop::loop_predication_should_follow_branches(IdealLoopTree *loop, ProjNode *predicate_proj, float& loop_trip_cnt) {
810 if (!UseProfiledLoopPredicate) {
811 return false;
812 }
813
814 if (predicate_proj == NULL) {
815 return false;
816 }
817
818 LoopNode* head = loop->_head->as_Loop();
819 bool follow_branches = true;
820 IdealLoopTree* l = loop->_child;
821 // For leaf loops and loops with a single inner loop
822 while (l != NULL && follow_branches) {
823 IdealLoopTree* child = l;
824 if (child->_child != NULL &&
825 child->_head->is_OuterStripMinedLoop()) {
826 assert(child->_child->_next == NULL, "only one inner loop for strip mined loop");
827 assert(child->_child->_head->is_CountedLoop() && child->_child->_head->as_CountedLoop()->is_strip_mined(), "inner loop should be strip mined");
828 child = child->_child;
829 }
830 if (child->_child != NULL || child->_irreducible) {
831 follow_branches = false;
832 }
833 l = l->_next;
834 }
835 if (follow_branches) {
836 loop->compute_profile_trip_cnt(this);
837 if (head->is_profile_trip_failed()) {
838 follow_branches = false;
839 } else {
840 loop_trip_cnt = head->profile_trip_cnt();
841 if (head->is_CountedLoop()) {
842 CountedLoopNode* cl = head->as_CountedLoop();
843 if (cl->phi() != NULL) {
844 const TypeInt* t = _igvn.type(cl->phi())->is_int();
845 float worst_case_trip_cnt = ((float)t->_hi - t->_lo) / ABS(cl->stride_con());
846 if (worst_case_trip_cnt < loop_trip_cnt) {
847 loop_trip_cnt = worst_case_trip_cnt;
848 }
849 }
850 }
851 }
852 }
853 return follow_branches;
854 }
855
856 // Compute probability of reaching some CFG node from a fixed
857 // dominating CFG node
858 class PathFrequency {
859 private:
860 Node* _dom; // frequencies are computed relative to this node
861 Node_Stack _stack;
862 GrowableArray<float> _freqs_stack; // keep track of intermediate result at regions
863 GrowableArray<float> _freqs; // cache frequencies
864 PhaseIdealLoop* _phase;
865
866 public:
867 PathFrequency(Node* dom, PhaseIdealLoop* phase)
868 : _dom(dom), _stack(0), _phase(phase) {
869 }
870
871 float to(Node* n) {
872 // post order walk on the CFG graph from n to _dom
873 fesetround(FE_TOWARDZERO); // make sure rounding doesn't push frequency above 1
874 IdealLoopTree* loop = _phase->get_loop(_dom);
875 Node* c = n;
876 for (;;) {
877 assert(_phase->get_loop(c) == loop, "have to be in the same loop");
878 if (c == _dom || _freqs.at_grow(c->_idx, -1) >= 0) {
879 float f = c == _dom ? 1 : _freqs.at(c->_idx);
880 Node* prev = c;
881 while (_stack.size() > 0 && prev == c) {
882 Node* n = _stack.node();
883 if (!n->is_Region()) {
884 if (_phase->get_loop(n) != _phase->get_loop(n->in(0))) {
885 // Found an inner loop: compute frequency of reaching this
886 // exit from the loop head by looking at the number of
887 // times each loop exit was taken
888 IdealLoopTree* inner_loop = _phase->get_loop(n->in(0));
889 LoopNode* inner_head = inner_loop->_head->as_Loop();
890 assert(_phase->get_loop(n) == loop, "only 1 inner loop");
891 if (inner_head->is_OuterStripMinedLoop()) {
892 inner_head->verify_strip_mined(1);
893 if (n->in(0) == inner_head->in(LoopNode::LoopBackControl)->in(0)) {
894 n = n->in(0)->in(0)->in(0);
895 }
896 inner_loop = inner_loop->_child;
897 inner_head = inner_loop->_head->as_Loop();
898 inner_head->verify_strip_mined(1);
899 }
900 fesetround(FE_UPWARD); // make sure rounding doesn't push frequency above 1
901 float loop_exit_cnt = 0.0f;
902 for (uint i = 0; i < inner_loop->_body.size(); i++) {
903 Node *n = inner_loop->_body[i];
904 float c = inner_loop->compute_profile_trip_cnt_helper(n);
905 loop_exit_cnt += c;
906 }
907 fesetround(FE_TOWARDZERO);
908 float cnt = -1;
909 if (n->in(0)->is_If()) {
910 IfNode* iff = n->in(0)->as_If();
911 float p = n->in(0)->as_If()->_prob;
912 if (n->Opcode() == Op_IfFalse) {
913 p = 1 - p;
914 }
915 if (p > PROB_MIN) {
916 cnt = p * iff->_fcnt;
917 } else {
918 cnt = 0;
919 }
920 } else {
921 assert(n->in(0)->is_Jump(), "unsupported node kind");
922 JumpNode* jmp = n->in(0)->as_Jump();
923 float p = n->in(0)->as_Jump()->_probs[n->as_JumpProj()->_con];
924 cnt = p * jmp->_fcnt;
925 }
926 float this_exit_f = cnt > 0 ? cnt / loop_exit_cnt : 0;
927 assert(this_exit_f <= 1 && this_exit_f >= 0, "Incorrect frequency");
928 f = f * this_exit_f;
929 assert(f <= 1 && f >= 0, "Incorrect frequency");
930 } else {
931 float p = -1;
932 if (n->in(0)->is_If()) {
933 p = n->in(0)->as_If()->_prob;
934 if (n->Opcode() == Op_IfFalse) {
935 p = 1 - p;
936 }
937 } else {
938 assert(n->in(0)->is_Jump(), "unsupported node kind");
939 p = n->in(0)->as_Jump()->_probs[n->as_JumpProj()->_con];
940 }
941 f = f * p;
942 assert(f <= 1 && f >= 0, "Incorrect frequency");
943 }
944 _freqs.at_put_grow(n->_idx, (float)f, -1);
945 _stack.pop();
946 } else {
947 float prev_f = _freqs_stack.pop();
948 float new_f = f;
949 f = new_f + prev_f;
950 assert(f <= 1 && f >= 0, "Incorrect frequency");
951 uint i = _stack.index();
952 if (i < n->req()) {
953 c = n->in(i);
954 _stack.set_index(i+1);
955 _freqs_stack.push(f);
956 } else {
957 _freqs.at_put_grow(n->_idx, f, -1);
958 _stack.pop();
959 }
960 }
961 }
962 if (_stack.size() == 0) {
963 fesetround(FE_TONEAREST);
964 assert(f >= 0 && f <= 1, "should have been computed");
965 return f;
966 }
967 } else if (c->is_Loop()) {
968 ShouldNotReachHere();
969 c = c->in(LoopNode::EntryControl);
970 } else if (c->is_Region()) {
971 _freqs_stack.push(0);
972 _stack.push(c, 2);
973 c = c->in(1);
974 } else {
975 if (c->is_IfProj()) {
976 IfNode* iff = c->in(0)->as_If();
977 if (iff->_prob == PROB_UNKNOWN) {
978 // assume never taken
979 _freqs.at_put_grow(c->_idx, 0, -1);
980 } else if (_phase->get_loop(c) != _phase->get_loop(iff)) {
981 if (iff->_fcnt == COUNT_UNKNOWN) {
982 // assume never taken
983 _freqs.at_put_grow(c->_idx, 0, -1);
984 } else {
985 // skip over loop
986 _stack.push(c, 1);
987 c = _phase->get_loop(c->in(0))->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl);
988 }
989 } else {
990 _stack.push(c, 1);
991 c = iff;
992 }
993 } else if (c->is_JumpProj()) {
994 JumpNode* jmp = c->in(0)->as_Jump();
995 if (_phase->get_loop(c) != _phase->get_loop(jmp)) {
996 if (jmp->_fcnt == COUNT_UNKNOWN) {
997 // assume never taken
998 _freqs.at_put_grow(c->_idx, 0, -1);
999 } else {
1000 // skip over loop
1001 _stack.push(c, 1);
1002 c = _phase->get_loop(c->in(0))->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl);
1003 }
1004 } else {
1005 _stack.push(c, 1);
1006 c = jmp;
1007 }
1008 } else if (c->Opcode() == Op_CatchProj &&
1009 c->in(0)->Opcode() == Op_Catch &&
1010 c->in(0)->in(0)->is_Proj() &&
1011 c->in(0)->in(0)->in(0)->is_Call()) {
1012 // assume exceptions are never thrown
1013 uint con = c->as_Proj()->_con;
1014 if (con == CatchProjNode::fall_through_index) {
1015 Node* call = c->in(0)->in(0)->in(0)->in(0);
1016 if (_phase->get_loop(call) != _phase->get_loop(c)) {
1017 _freqs.at_put_grow(c->_idx, 0, -1);
1018 } else {
1019 c = call;
1020 }
1021 } else {
1022 assert(con >= CatchProjNode::catch_all_index, "what else?");
1023 _freqs.at_put_grow(c->_idx, 0, -1);
1024 }
1025 } else if (c->unique_ctrl_out() == NULL && !c->is_If() && !c->is_Jump()) {
1026 ShouldNotReachHere();
1027 } else {
1028 c = c->in(0);
1029 }
1030 }
1031 }
1032 ShouldNotReachHere();
1033 return -1;
1034 }
1035 };
1036
1037 void PhaseIdealLoop::loop_predication_follow_branches(Node *n, IdealLoopTree *loop, float loop_trip_cnt,
1038 PathFrequency& pf, Node_Stack& stack, VectorSet& seen,
1039 Node_List& if_proj_list) {
1040 assert(n->is_Region(), "start from a region");
1041 Node* tail = loop->tail();
1042 stack.push(n, 1);
1043 do {
1044 Node* c = stack.node();
1045 assert(c->is_Region() || c->is_IfProj(), "only region here");
1046 uint i = stack.index();
1047
1048 if (i < c->req()) {
1049 stack.set_index(i+1);
1050 Node* in = c->in(i);
1051 while (!is_dominator(in, tail) && !seen.test_set(in->_idx)) {
1052 IdealLoopTree* in_loop = get_loop(in);
1053 if (in_loop != loop) {
1054 in = in_loop->_head->in(LoopNode::EntryControl);
1055 } else if (in->is_Region()) {
1056 stack.push(in, 1);
1057 break;
1058 } else if (in->is_IfProj() &&
1059 in->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) {
1060 if (pf.to(in) * loop_trip_cnt >= 1) {
1061 stack.push(in, 1);
1062 }
1063 in = in->in(0);
1064 } else {
1065 in = in->in(0);
1066 }
1067 }
1068 } else {
1069 if (c->is_IfProj()) {
1070 if_proj_list.push(c);
1071 }
1072 stack.pop();
1073 }
1074
1075 } while (stack.size() > 0);
1076 }
1077
1078
1079 bool PhaseIdealLoop::loop_predication_impl_helper(IdealLoopTree *loop, ProjNode* proj, ProjNode *predicate_proj,
1080 CountedLoopNode *cl, ConNode* zero, Invariance& invar,
1081 Deoptimization::DeoptReason reason) {
1082 // Following are changed to nonnull when a predicate can be hoisted
1083 ProjNode* new_predicate_proj = NULL;
1084 IfNode* iff = proj->in(0)->as_If();
1085 Node* test = iff->in(1);
1086 if (!test->is_Bool()){ //Conv2B, ...
1087 return false;
1088 }
1089 BoolNode* bol = test->as_Bool();
1090 if (invar.is_invariant(bol)) {
1091 // Invariant test
1092 new_predicate_proj = create_new_if_for_predicate(predicate_proj, NULL,
1093 reason,
1094 iff->Opcode());
1095 Node* ctrl = new_predicate_proj->in(0)->as_If()->in(0);
1096 BoolNode* new_predicate_bol = invar.clone(bol, ctrl)->as_Bool();
1097
1098 // Negate test if necessary
1099 bool negated = false;
1100 if (proj->_con != predicate_proj->_con) {
1101 new_predicate_bol = new BoolNode(new_predicate_bol->in(1), new_predicate_bol->_test.negate());
1102 register_new_node(new_predicate_bol, ctrl);
1103 negated = true;
1104 }
1105 IfNode* new_predicate_iff = new_predicate_proj->in(0)->as_If();
1106 _igvn.hash_delete(new_predicate_iff);
1107 new_predicate_iff->set_req(1, new_predicate_bol);
1108 #ifndef PRODUCT
1109 if (TraceLoopPredicate) {
1110 tty->print("Predicate invariant if%s: %d ", negated ? " negated" : "", new_predicate_iff->_idx);
1111 loop->dump_head();
1112 } else if (TraceLoopOpts) {
1113 tty->print("Predicate IC ");
1114 loop->dump_head();
1115 }
1116 #endif
1117 } else if (cl != NULL && loop->is_range_check_if(iff, this, invar)) {
1118 // Range check for counted loops
1119 const Node* cmp = bol->in(1)->as_Cmp();
1120 Node* idx = cmp->in(1);
1121 assert(!invar.is_invariant(idx), "index is variant");
1122 Node* rng = cmp->in(2);
1123 assert(rng->Opcode() == Op_LoadRange || iff->is_RangeCheck() || _igvn.type(rng)->is_int()->_lo >= 0, "must be");
1124 assert(invar.is_invariant(rng), "range must be invariant");
1125 int scale = 1;
1126 Node* offset = zero;
1127 bool ok = is_scaled_iv_plus_offset(idx, cl->phi(), &scale, &offset);
1128 assert(ok, "must be index expression");
1129
1130 Node* init = cl->init_trip();
1131 // Limit is not exact.
1132 // Calculate exact limit here.
1133 // Note, counted loop's test is '<' or '>'.
1134 Node* limit = exact_limit(loop);
1135 int stride = cl->stride()->get_int();
1136
1137 // Build if's for the upper and lower bound tests. The
1138 // lower_bound test will dominate the upper bound test and all
1139 // cloned or created nodes will use the lower bound test as
1140 // their declared control.
1141
1142 // Perform cloning to keep Invariance state correct since the
1143 // late schedule will place invariant things in the loop.
1144 Node *ctrl = predicate_proj->in(0)->as_If()->in(0);
1145 rng = invar.clone(rng, ctrl);
1146 if (offset && offset != zero) {
1147 assert(invar.is_invariant(offset), "offset must be loop invariant");
1148 offset = invar.clone(offset, ctrl);
1149 }
1150 // If predicate expressions may overflow in the integer range, longs are used.
1151 bool overflow = false;
1152
1153 // Test the lower bound
1154 BoolNode* lower_bound_bol = rc_predicate(loop, ctrl, scale, offset, init, limit, stride, rng, false, overflow);
1155 // Negate test if necessary
1156 bool negated = false;
1157 if (proj->_con != predicate_proj->_con) {
1158 lower_bound_bol = new BoolNode(lower_bound_bol->in(1), lower_bound_bol->_test.negate());
1159 register_new_node(lower_bound_bol, ctrl);
1160 negated = true;
1161 }
1162 ProjNode* lower_bound_proj = create_new_if_for_predicate(predicate_proj, NULL, reason, overflow ? Op_If : iff->Opcode());
1163 IfNode* lower_bound_iff = lower_bound_proj->in(0)->as_If();
1164 _igvn.hash_delete(lower_bound_iff);
1165 lower_bound_iff->set_req(1, lower_bound_bol);
1166 if (TraceLoopPredicate) tty->print_cr("lower bound check if: %s %d ", negated ? " negated" : "", lower_bound_iff->_idx);
1167
1168 // Test the upper bound
1169 BoolNode* upper_bound_bol = rc_predicate(loop, lower_bound_proj, scale, offset, init, limit, stride, rng, true, overflow);
1170 negated = false;
1171 if (proj->_con != predicate_proj->_con) {
1172 upper_bound_bol = new BoolNode(upper_bound_bol->in(1), upper_bound_bol->_test.negate());
1173 register_new_node(upper_bound_bol, ctrl);
1174 negated = true;
1175 }
1176 ProjNode* upper_bound_proj = create_new_if_for_predicate(predicate_proj, NULL, reason, overflow ? Op_If : iff->Opcode());
1177 assert(upper_bound_proj->in(0)->as_If()->in(0) == lower_bound_proj, "should dominate");
1178 IfNode* upper_bound_iff = upper_bound_proj->in(0)->as_If();
1179 _igvn.hash_delete(upper_bound_iff);
1180 upper_bound_iff->set_req(1, upper_bound_bol);
1181 if (TraceLoopPredicate) tty->print_cr("upper bound check if: %s %d ", negated ? " negated" : "", lower_bound_iff->_idx);
1182
1183 // Fall through into rest of the clean up code which will move
1184 // any dependent nodes onto the upper bound test.
1185 new_predicate_proj = upper_bound_proj;
1186
1187 if (iff->is_RangeCheck()) {
1188 new_predicate_proj = insert_skeleton_predicate(iff, loop, proj, predicate_proj, upper_bound_proj, scale, offset, init, limit, stride, rng, overflow, reason);
1189 }
1190
1191 #ifndef PRODUCT
1192 if (TraceLoopOpts && !TraceLoopPredicate) {
1193 tty->print("Predicate RC ");
1194 loop->dump_head();
1195 }
1196 #endif
1197 } else {
1198 // Loop variant check (for example, range check in non-counted loop)
1199 // with uncommon trap.
1200 return false;
1201 }
1202 assert(new_predicate_proj != NULL, "sanity");
1203 // Success - attach condition (new_predicate_bol) to predicate if
1204 invar.map_ctrl(proj, new_predicate_proj); // so that invariance test can be appropriate
1205
1206 // Eliminate the old If in the loop body
1207 dominated_by( new_predicate_proj, iff, proj->_con != new_predicate_proj->_con );
1208
1209 C->set_major_progress();
1210 return true;
1211 }
1212
1213
1214 // After pre/main/post loops are created, we'll put a copy of some
1215 // range checks between the pre and main loop to validate the initial
1216 // value of the induction variable for the main loop. Make a copy of
1217 // the predicates here with an opaque node as a place holder for the
1218 // initial value.
1219 ProjNode* PhaseIdealLoop::insert_skeleton_predicate(IfNode* iff, IdealLoopTree *loop,
1220 ProjNode* proj, ProjNode *predicate_proj,
1221 ProjNode* upper_bound_proj,
1222 int scale, Node* offset,
1223 Node* init, Node* limit, jint stride,
1224 Node* rng, bool &overflow,
1225 Deoptimization::DeoptReason reason) {
1226 assert(proj->_con && predicate_proj->_con, "not a range check?");
1227 Node* opaque_init = new Opaque1Node(C, init);
1228 register_new_node(opaque_init, upper_bound_proj);
1229 BoolNode* bol = rc_predicate(loop, upper_bound_proj, scale, offset, opaque_init, limit, stride, rng, (stride > 0) != (scale > 0), overflow);
1230 Node* opaque_bol = new Opaque4Node(C, bol, _igvn.intcon(1)); // This will go away once loop opts are over
1231 register_new_node(opaque_bol, upper_bound_proj);
1232 ProjNode* new_proj = create_new_if_for_predicate(predicate_proj, NULL, reason, overflow ? Op_If : iff->Opcode());
1233 _igvn.replace_input_of(new_proj->in(0), 1, opaque_bol);
1234 assert(opaque_init->outcnt() > 0, "should be used");
1235 return new_proj;
1236 }
1237
1238 //------------------------------ loop_predication_impl--------------------------
1239 // Insert loop predicates for null checks and range checks
1240 bool PhaseIdealLoop::loop_predication_impl(IdealLoopTree *loop) {
1241 if (!UseLoopPredicate) return false;
1242
1243 if (!loop->_head->is_Loop()) {
1244 // Could be a simple region when irreducible loops are present.
1245 return false;
1246 }
1247 LoopNode* head = loop->_head->as_Loop();
1248
1249 if (head->unique_ctrl_out()->Opcode() == Op_NeverBranch) {
1250 // do nothing for infinite loops
1251 return false;
1252 }
1253
1254 if (head->is_OuterStripMinedLoop()) {
1255 return false;
1256 }
1257
1258 CountedLoopNode *cl = NULL;
1259 if (head->is_valid_counted_loop()) {
1260 cl = head->as_CountedLoop();
1261 // do nothing for iteration-splitted loops
1262 if (!cl->is_normal_loop()) return false;
1263 // Avoid RCE if Counted loop's test is '!='.
1264 BoolTest::mask bt = cl->loopexit()->test_trip();
1265 if (bt != BoolTest::lt && bt != BoolTest::gt)
1266 cl = NULL;
1267 }
1268
1269 Node* entry = head->skip_strip_mined()->in(LoopNode::EntryControl);
1270 ProjNode *loop_limit_proj = NULL;
1271 ProjNode *predicate_proj = NULL;
1272 ProjNode *profile_predicate_proj = NULL;
1273 // Loop limit check predicate should be near the loop.
1274 loop_limit_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
1275 if (loop_limit_proj != NULL) {
1276 entry = loop_limit_proj->in(0)->in(0);
1277 }
1278 bool has_profile_predicates = false;
1279 profile_predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_profile_predicate);
1280 if (profile_predicate_proj != NULL) {
1281 Node* n = skip_loop_predicates(entry);
1282 // Check if predicates were already added to the profile predicate
1283 // block
1284 if (n != entry->in(0)->in(0)) {
1285 has_profile_predicates = true;
1286 }
1287 entry = n;
1288 }
1289 predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
1290
1291 float loop_trip_cnt = -1;
1292 bool follow_branches = loop_predication_should_follow_branches(loop, profile_predicate_proj, loop_trip_cnt);
1293 assert(!follow_branches || loop_trip_cnt >= 0, "negative trip count?");
1294
1295 if (predicate_proj == NULL && !follow_branches) {
1296 #ifndef PRODUCT
1297 if (TraceLoopPredicate) {
1298 tty->print("missing predicate:");
1299 loop->dump_head();
1300 head->dump(1);
1301 }
1302 #endif
1303 return false;
1304 }
1305 ConNode* zero = _igvn.intcon(0);
1306 set_ctrl(zero, C->root());
1307
1308 ResourceArea *area = Thread::current()->resource_area();
1309 Invariance invar(area, loop);
1310
1311 // Create list of if-projs such that a newer proj dominates all older
1312 // projs in the list, and they all dominate loop->tail()
1313 Node_List if_proj_list(area);
1314 Node_List regions(area);
1315 Node *current_proj = loop->tail(); //start from tail
1316
1317
1318 Node_List controls(area);
1319 while (current_proj != head) {
1320 if (loop == get_loop(current_proj) && // still in the loop ?
1321 current_proj->is_Proj() && // is a projection ?
1322 (current_proj->in(0)->Opcode() == Op_If ||
1323 current_proj->in(0)->Opcode() == Op_RangeCheck)) { // is a if projection ?
1324 if_proj_list.push(current_proj);
1325 }
1326 if (follow_branches &&
1327 current_proj->Opcode() == Op_Region &&
1328 loop == get_loop(current_proj)) {
1329 regions.push(current_proj);
1330 }
1331 current_proj = idom(current_proj);
1332 }
1333
1334 bool hoisted = false; // true if at least one proj is promoted
1335
1336 if (!has_profile_predicates) {
1337 while (if_proj_list.size() > 0) {
1338 Node* n = if_proj_list.pop();
1339
1340 ProjNode* proj = n->as_Proj();
1341 IfNode* iff = proj->in(0)->as_If();
1342
1343 CallStaticJavaNode* call = proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
1344 if (call == NULL) {
1345 if (loop->is_loop_exit(iff)) {
1346 // stop processing the remaining projs in the list because the execution of them
1347 // depends on the condition of "iff" (iff->in(1)).
1348 break;
1349 } else {
1350 // Both arms are inside the loop. There are two cases:
1351 // (1) there is one backward branch. In this case, any remaining proj
1352 // in the if_proj list post-dominates "iff". So, the condition of "iff"
1353 // does not determine the execution the remining projs directly, and we
1354 // can safely continue.
1355 // (2) both arms are forwarded, i.e. a diamond shape. In this case, "proj"
1356 // does not dominate loop->tail(), so it can not be in the if_proj list.
1357 continue;
1358 }
1359 }
1360 Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(call->uncommon_trap_request());
1361 if (reason == Deoptimization::Reason_predicate) {
1362 break;
1363 }
1364
1365 if (predicate_proj != NULL) {
1366 hoisted = loop_predication_impl_helper(loop, proj, predicate_proj, cl, zero, invar, Deoptimization::Reason_predicate) | hoisted;
1367 }
1368 } // end while
1369 }
1370
1371 Node_List if_proj_list_freq(area);
1372 if (follow_branches) {
1373 PathFrequency pf(loop->_head, this);
1374
1375 // Some projections were skipped by regular predicates because of
1376 // an early loop exit. Try them with profile data.
1377 while (if_proj_list.size() > 0) {
1378 Node* proj = if_proj_list.pop();
1379 float f = pf.to(proj);
1380 if (proj->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none) &&
1381 f * loop_trip_cnt >= 1) {
1382 hoisted = loop_predication_impl_helper(loop, proj->as_Proj(), profile_predicate_proj, cl, zero, invar, Deoptimization::Reason_profile_predicate) | hoisted;
1383 }
1384 }
1385
1386 // And look into all branches
1387 Node_Stack stack(0);
1388 VectorSet seen(Thread::current()->resource_area());
1389 while (regions.size() > 0) {
1390 Node* c = regions.pop();
1391 loop_predication_follow_branches(c, loop, loop_trip_cnt, pf, stack, seen, if_proj_list_freq);
1392 }
1393
1394 for (uint i = 0; i < if_proj_list_freq.size(); i++) {
1395 ProjNode* proj = if_proj_list_freq.at(i)->as_Proj();
1396 hoisted = loop_predication_impl_helper(loop, proj, profile_predicate_proj, cl, zero, invar, Deoptimization::Reason_profile_predicate) | hoisted;
1397 }
1398 }
1399
1400 #ifndef PRODUCT
1401 // report that the loop predication has been actually performed
1402 // for this loop
1403 if (TraceLoopPredicate && hoisted) {
1404 tty->print("Loop Predication Performed:");
1405 loop->dump_head();
1406 }
1407 #endif
1408
1409 head->verify_strip_mined(1);
1410
1411 return hoisted;
1412 }
1413
1414 //------------------------------loop_predication--------------------------------
1415 // driver routine for loop predication optimization
1416 bool IdealLoopTree::loop_predication( PhaseIdealLoop *phase) {
1417 bool hoisted = false;
1418 // Recursively promote predicates
1419 if (_child) {
1420 hoisted = _child->loop_predication( phase);
1421 }
1422
1423 // self
1424 if (!_irreducible && !tail()->is_top()) {
1425 hoisted |= phase->loop_predication_impl(this);
1426 }
1427
1428 if (_next) { //sibling
1429 hoisted |= _next->loop_predication( phase);
1430 }
1431
1432 return hoisted;
1433 }