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
38 /*
39 * The general idea of Loop Predication is to insert a predicate on the entry
40 * path to a loop, and raise a uncommon trap if the check of the condition fails.
41 * The condition checks are promoted from inside the loop body, and thus
42 * the checks inside the loop could be eliminated. Currently, loop predication
43 * optimization has been applied to remove array range check and loop invariant
44 * checks (such as null checks).
45 */
46
47 //-------------------------------register_control-------------------------
48 void PhaseIdealLoop::register_control(Node* n, IdealLoopTree *loop, Node* pred) {
49 assert(n->is_CFG(), "must be control node");
50 _igvn.register_new_node_with_optimizer(n);
51 loop->_body.push(n);
52 set_loop(n, loop);
53 // When called from beautify_loops() idom is not constructed yet.
54 if (_idom != NULL) {
55 set_idom(n, pred, dom_depth(pred));
56 }
57 }
58
59 //------------------------------create_new_if_for_predicate------------------------
60 // create a new if above the uct_if_pattern for the predicate to be promoted.
61 //
62 // before after
63 // ---------- ----------
64 // ctrl ctrl
65 // | |
66 // | |
67 // v v
68 // iff new_iff
69 // / \ / \
70 // / \ / \
71 // v v v v
72 // uncommon_proj cont_proj if_uct if_cont
73 // \ | | | |
74 // \ | | | |
75 // v v v | v
76 // rgn loop | iff
77 // | | / \
78 // | | / \
79 // v | v v
80 // uncommon_trap | uncommon_proj cont_proj
81 // \ \ | |
82 // \ \ | |
83 // v v v v
84 // rgn loop
85 // |
86 // |
87 // v
88 // uncommon_trap
89 //
90 //
91 // We will create a region to guard the uct call if there is no one there.
92 // The true projecttion (if_cont) of the new_iff is returned.
93 // This code is also used to clone predicates to cloned loops.
94 ProjNode* PhaseIdealLoop::create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry,
95 Deoptimization::DeoptReason reason,
96 int opcode) {
97 assert(cont_proj->is_uncommon_trap_if_pattern(reason), "must be a uct if pattern!");
98 IfNode* iff = cont_proj->in(0)->as_If();
99
100 ProjNode *uncommon_proj = iff->proj_out(1 - cont_proj->_con);
101 Node *rgn = uncommon_proj->unique_ctrl_out();
102 assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct");
103
104 uint proj_index = 1; // region's edge corresponding to uncommon_proj
105 if (!rgn->is_Region()) { // create a region to guard the call
106 assert(rgn->is_Call(), "must be call uct");
107 CallNode* call = rgn->as_Call();
108 IdealLoopTree* loop = get_loop(call);
109 rgn = new RegionNode(1);
110 rgn->add_req(uncommon_proj);
111 register_control(rgn, loop, uncommon_proj);
112 _igvn.replace_input_of(call, 0, rgn);
113 // When called from beautify_loops() idom is not constructed yet.
114 if (_idom != NULL) {
115 set_idom(call, rgn, dom_depth(rgn));
116 }
117 for (DUIterator_Fast imax, i = uncommon_proj->fast_outs(imax); i < imax; i++) {
118 Node* n = uncommon_proj->fast_out(i);
119 if (n->is_Load() || n->is_Store()) {
120 _igvn.replace_input_of(n, 0, rgn);
121 --i; --imax;
122 }
123 }
124 } else {
125 // Find region's edge corresponding to uncommon_proj
126 for (; proj_index < rgn->req(); proj_index++)
127 if (rgn->in(proj_index) == uncommon_proj) break;
128 assert(proj_index < rgn->req(), "sanity");
129 }
130
131 Node* entry = iff->in(0);
132 if (new_entry != NULL) {
133 // Clonning the predicate to new location.
134 entry = new_entry;
135 }
136 // Create new_iff
137 IdealLoopTree* lp = get_loop(entry);
138 IfNode* new_iff = NULL;
139 if (opcode == Op_If) {
140 new_iff = new IfNode(entry, iff->in(1), iff->_prob, iff->_fcnt);
141 } else {
142 assert(opcode == Op_RangeCheck, "no other if variant here");
143 new_iff = new RangeCheckNode(entry, iff->in(1), iff->_prob, iff->_fcnt);
144 }
145 register_control(new_iff, lp, entry);
146 Node *if_cont = new IfTrueNode(new_iff);
147 Node *if_uct = new IfFalseNode(new_iff);
148 if (cont_proj->is_IfFalse()) {
149 // Swap
150 Node* tmp = if_uct; if_uct = if_cont; if_cont = tmp;
151 }
152 register_control(if_cont, lp, new_iff);
153 register_control(if_uct, get_loop(rgn), new_iff);
154
155 // if_uct to rgn
156 _igvn.hash_delete(rgn);
157 rgn->add_req(if_uct);
158 // When called from beautify_loops() idom is not constructed yet.
159 if (_idom != NULL) {
160 Node* ridom = idom(rgn);
161 Node* nrdom = dom_lca(ridom, new_iff);
162 set_idom(rgn, nrdom, dom_depth(rgn));
163 }
164
165 // If rgn has phis add new edges which has the same
166 // value as on original uncommon_proj pass.
167 assert(rgn->in(rgn->req() -1) == if_uct, "new edge should be last");
168 bool has_phi = false;
169 for (DUIterator_Fast imax, i = rgn->fast_outs(imax); i < imax; i++) {
170 Node* use = rgn->fast_out(i);
171 if (use->is_Phi() && use->outcnt() > 0) {
172 assert(use->in(0) == rgn, "");
173 _igvn.rehash_node_delayed(use);
174 use->add_req(use->in(proj_index));
175 has_phi = true;
176 }
177 }
178 assert(!has_phi || rgn->req() > 3, "no phis when region is created");
179
180 if (new_entry == NULL) {
181 // Attach if_cont to iff
182 _igvn.replace_input_of(iff, 0, if_cont);
183 if (_idom != NULL) {
184 set_idom(iff, if_cont, dom_depth(iff));
185 }
186 }
187 return if_cont->as_Proj();
188 }
189
190 //------------------------------create_new_if_for_predicate------------------------
191 // Create a new if below new_entry for the predicate to be cloned (IGVN optimization)
192 ProjNode* PhaseIterGVN::create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry,
193 Deoptimization::DeoptReason reason,
194 int opcode) {
195 assert(new_entry != 0, "only used for clone predicate");
196 assert(cont_proj->is_uncommon_trap_if_pattern(reason), "must be a uct if pattern!");
197 IfNode* iff = cont_proj->in(0)->as_If();
198
199 ProjNode *uncommon_proj = iff->proj_out(1 - cont_proj->_con);
200 Node *rgn = uncommon_proj->unique_ctrl_out();
201 assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct");
202
203 uint proj_index = 1; // region's edge corresponding to uncommon_proj
204 if (!rgn->is_Region()) { // create a region to guard the call
205 assert(rgn->is_Call(), "must be call uct");
206 CallNode* call = rgn->as_Call();
207 rgn = new RegionNode(1);
208 register_new_node_with_optimizer(rgn);
209 rgn->add_req(uncommon_proj);
210 replace_input_of(call, 0, rgn);
211 } else {
212 // Find region's edge corresponding to uncommon_proj
213 for (; proj_index < rgn->req(); proj_index++)
214 if (rgn->in(proj_index) == uncommon_proj) break;
215 assert(proj_index < rgn->req(), "sanity");
216 }
217
218 // Create new_iff in new location.
219 IfNode* new_iff = NULL;
220 if (opcode == Op_If) {
221 new_iff = new IfNode(new_entry, iff->in(1), iff->_prob, iff->_fcnt);
222 } else {
223 assert(opcode == Op_RangeCheck, "no other if variant here");
224 new_iff = new RangeCheckNode(new_entry, iff->in(1), iff->_prob, iff->_fcnt);
225 }
226
227 register_new_node_with_optimizer(new_iff);
228 Node *if_cont = new IfTrueNode(new_iff);
229 Node *if_uct = new IfFalseNode(new_iff);
230 if (cont_proj->is_IfFalse()) {
231 // Swap
232 Node* tmp = if_uct; if_uct = if_cont; if_cont = tmp;
233 }
234 register_new_node_with_optimizer(if_cont);
235 register_new_node_with_optimizer(if_uct);
236
237 // if_uct to rgn
238 hash_delete(rgn);
239 rgn->add_req(if_uct);
240
241 // If rgn has phis add corresponding new edges which has the same
242 // value as on original uncommon_proj pass.
243 assert(rgn->in(rgn->req() -1) == if_uct, "new edge should be last");
244 bool has_phi = false;
245 for (DUIterator_Fast imax, i = rgn->fast_outs(imax); i < imax; i++) {
246 Node* use = rgn->fast_out(i);
247 if (use->is_Phi() && use->outcnt() > 0) {
248 rehash_node_delayed(use);
249 use->add_req(use->in(proj_index));
250 has_phi = true;
251 }
252 }
253 assert(!has_phi || rgn->req() > 3, "no phis when region is created");
254
255 return if_cont->as_Proj();
256 }
257
258 //--------------------------clone_predicate-----------------------
259 ProjNode* PhaseIdealLoop::clone_predicate(ProjNode* predicate_proj, Node* new_entry,
260 Deoptimization::DeoptReason reason,
261 PhaseIdealLoop* loop_phase,
262 PhaseIterGVN* igvn) {
263 ProjNode* new_predicate_proj;
264 if (loop_phase != NULL) {
265 new_predicate_proj = loop_phase->create_new_if_for_predicate(predicate_proj, new_entry, reason, Op_If);
266 } else {
267 new_predicate_proj = igvn->create_new_if_for_predicate(predicate_proj, new_entry, reason, Op_If);
268 }
269 IfNode* iff = new_predicate_proj->in(0)->as_If();
270 Node* ctrl = iff->in(0);
271
272 // Match original condition since predicate's projections could be swapped.
273 assert(predicate_proj->in(0)->in(1)->in(1)->Opcode()==Op_Opaque1, "must be");
274 Node* opq = new Opaque1Node(igvn->C, predicate_proj->in(0)->in(1)->in(1)->in(1));
275 igvn->C->add_predicate_opaq(opq);
276
277 Node* bol = new Conv2BNode(opq);
278 if (loop_phase != NULL) {
279 loop_phase->register_new_node(opq, ctrl);
280 loop_phase->register_new_node(bol, ctrl);
281 } else {
282 igvn->register_new_node_with_optimizer(opq);
283 igvn->register_new_node_with_optimizer(bol);
284 }
285 igvn->hash_delete(iff);
286 iff->set_req(1, bol);
287 return new_predicate_proj;
288 }
289
290
291 //--------------------------clone_loop_predicates-----------------------
292 // Interface from IGVN
293 Node* PhaseIterGVN::clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) {
294 return PhaseIdealLoop::clone_loop_predicates(old_entry, new_entry, clone_limit_check, NULL, this);
295 }
296
297 // Interface from PhaseIdealLoop
298 Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) {
299 return clone_loop_predicates(old_entry, new_entry, clone_limit_check, this, &this->_igvn);
300 }
301
302 // Clone loop predicates to cloned loops (peeled, unswitched, split_if).
303 Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry,
304 bool clone_limit_check,
305 PhaseIdealLoop* loop_phase,
306 PhaseIterGVN* igvn) {
307 #ifdef ASSERT
308 if (new_entry == NULL || !(new_entry->is_Proj() || new_entry->is_Region() || new_entry->is_SafePoint())) {
309 if (new_entry != NULL)
310 new_entry->dump();
311 assert(false, "not IfTrue, IfFalse, Region or SafePoint");
312 }
313 #endif
314 // Search original predicates
315 Node* entry = old_entry;
316 ProjNode* limit_check_proj = NULL;
317 limit_check_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
318 if (limit_check_proj != NULL) {
319 entry = entry->in(0)->in(0);
320 }
321 if (UseLoopPredicate) {
322 ProjNode* predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
323 if (predicate_proj != NULL) { // right pattern that can be used by loop predication
324 // clone predicate
325 new_entry = clone_predicate(predicate_proj, new_entry,
326 Deoptimization::Reason_predicate,
327 loop_phase, igvn);
328 assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone predicate");
329 if (TraceLoopPredicate) {
330 tty->print("Loop Predicate cloned: ");
331 debug_only( new_entry->in(0)->dump(); )
332 }
333 }
334 }
335 if (limit_check_proj != NULL && clone_limit_check) {
336 // Clone loop limit check last to insert it before loop.
337 // Don't clone a limit check which was already finalized
338 // for this counted loop (only one limit check is needed).
339 new_entry = clone_predicate(limit_check_proj, new_entry,
340 Deoptimization::Reason_loop_limit_check,
341 loop_phase, igvn);
342 assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone limit check");
343 if (TraceLoopLimitCheck) {
344 tty->print("Loop Limit Check cloned: ");
345 debug_only( new_entry->in(0)->dump(); )
346 }
347 }
348 return new_entry;
349 }
350
351 //--------------------------skip_loop_predicates------------------------------
352 // Skip related predicates.
353 Node* PhaseIdealLoop::skip_loop_predicates(Node* entry) {
354 Node* predicate = NULL;
355 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
356 if (predicate != NULL) {
357 entry = entry->in(0)->in(0);
358 }
359 if (UseLoopPredicate) {
360 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
361 if (predicate != NULL) { // right pattern that can be used by loop predication
362 IfNode* iff = entry->in(0)->as_If();
363 ProjNode* uncommon_proj = iff->proj_out(1 - entry->as_Proj()->_con);
364 Node* rgn = uncommon_proj->unique_ctrl_out();
365 assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct");
366 entry = entry->in(0)->in(0);
367 while (entry != NULL && entry->is_Proj() && entry->in(0)->is_If()) {
368 uncommon_proj = entry->in(0)->as_If()->proj_out(1 - entry->as_Proj()->_con);
369 if (uncommon_proj->unique_ctrl_out() != rgn)
370 break;
371 entry = entry->in(0)->in(0);
372 }
373 }
374 }
375 return entry;
376 }
377
378 //--------------------------find_predicate_insertion_point-------------------
379 // Find a good location to insert a predicate
380 ProjNode* PhaseIdealLoop::find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason) {
381 if (start_c == NULL || !start_c->is_Proj())
382 return NULL;
383 if (start_c->as_Proj()->is_uncommon_trap_if_pattern(reason)) {
384 return start_c->as_Proj();
385 }
386 return NULL;
387 }
388
389 //--------------------------find_predicate------------------------------------
390 // Find a predicate
391 Node* PhaseIdealLoop::find_predicate(Node* entry) {
392 Node* predicate = NULL;
393 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
394 if (predicate != NULL) { // right pattern that can be used by loop predication
395 return entry;
396 }
397 if (UseLoopPredicate) {
398 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
399 if (predicate != NULL) { // right pattern that can be used by loop predication
400 return entry;
401 }
402 }
403 return NULL;
404 }
405
406 //------------------------------Invariance-----------------------------------
407 // Helper class for loop_predication_impl to compute invariance on the fly and
408 // clone invariants.
409 class Invariance : public StackObj {
410 VectorSet _visited, _invariant;
411 Node_Stack _stack;
412 VectorSet _clone_visited;
413 Node_List _old_new; // map of old to new (clone)
414 IdealLoopTree* _lpt;
415 PhaseIdealLoop* _phase;
416
417 // Helper function to set up the invariance for invariance computation
418 // If n is a known invariant, set up directly. Otherwise, look up the
419 // the possibility to push n onto the stack for further processing.
420 void visit(Node* use, Node* n) {
421 if (_lpt->is_invariant(n)) { // known invariant
422 _invariant.set(n->_idx);
423 } else if (!n->is_CFG()) {
424 Node *n_ctrl = _phase->ctrl_or_self(n);
425 Node *u_ctrl = _phase->ctrl_or_self(use); // self if use is a CFG
426 if (_phase->is_dominator(n_ctrl, u_ctrl)) {
427 _stack.push(n, n->in(0) == NULL ? 1 : 0);
428 }
429 }
430 }
431
432 // Compute invariance for "the_node" and (possibly) all its inputs recursively
433 // on the fly
434 void compute_invariance(Node* n) {
435 assert(_visited.test(n->_idx), "must be");
436 visit(n, n);
437 while (_stack.is_nonempty()) {
438 Node* n = _stack.node();
439 uint idx = _stack.index();
440 if (idx == n->req()) { // all inputs are processed
441 _stack.pop();
442 // n is invariant if it's inputs are all invariant
443 bool all_inputs_invariant = true;
444 for (uint i = 0; i < n->req(); i++) {
445 Node* in = n->in(i);
446 if (in == NULL) continue;
447 assert(_visited.test(in->_idx), "must have visited input");
448 if (!_invariant.test(in->_idx)) { // bad guy
449 all_inputs_invariant = false;
450 break;
451 }
452 }
453 if (all_inputs_invariant) {
454 // If n's control is a predicate that was moved out of the
455 // loop, it was marked invariant but n is only invariant if
456 // it depends only on that test. Otherwise, unless that test
457 // is out of the loop, it's not invariant.
458 if (n->is_CFG() || n->depends_only_on_test() || n->in(0) == NULL || !_phase->is_member(_lpt, n->in(0))) {
459 _invariant.set(n->_idx); // I am a invariant too
460 }
461 }
462 } else { // process next input
463 _stack.set_index(idx + 1);
464 Node* m = n->in(idx);
465 if (m != NULL && !_visited.test_set(m->_idx)) {
466 visit(n, m);
467 }
468 }
469 }
470 }
471
472 // Helper function to set up _old_new map for clone_nodes.
473 // If n is a known invariant, set up directly ("clone" of n == n).
474 // Otherwise, push n onto the stack for real cloning.
475 void clone_visit(Node* n) {
476 assert(_invariant.test(n->_idx), "must be invariant");
477 if (_lpt->is_invariant(n)) { // known invariant
478 _old_new.map(n->_idx, n);
479 } else { // to be cloned
480 assert(!n->is_CFG(), "should not see CFG here");
481 _stack.push(n, n->in(0) == NULL ? 1 : 0);
482 }
483 }
484
485 // Clone "n" and (possibly) all its inputs recursively
486 void clone_nodes(Node* n, Node* ctrl) {
487 clone_visit(n);
488 while (_stack.is_nonempty()) {
489 Node* n = _stack.node();
490 uint idx = _stack.index();
491 if (idx == n->req()) { // all inputs processed, clone n!
492 _stack.pop();
493 // clone invariant node
494 Node* n_cl = n->clone();
495 _old_new.map(n->_idx, n_cl);
496 _phase->register_new_node(n_cl, ctrl);
497 for (uint i = 0; i < n->req(); i++) {
498 Node* in = n_cl->in(i);
499 if (in == NULL) continue;
500 n_cl->set_req(i, _old_new[in->_idx]);
501 }
502 } else { // process next input
503 _stack.set_index(idx + 1);
504 Node* m = n->in(idx);
505 if (m != NULL && !_clone_visited.test_set(m->_idx)) {
506 clone_visit(m); // visit the input
507 }
508 }
509 }
510 }
511
512 public:
513 Invariance(Arena* area, IdealLoopTree* lpt) :
514 _lpt(lpt), _phase(lpt->_phase),
515 _visited(area), _invariant(area), _stack(area, 10 /* guess */),
516 _clone_visited(area), _old_new(area)
517 {
518 LoopNode* head = _lpt->_head->as_Loop();
519 Node* entry = head->skip_strip_mined()->in(LoopNode::EntryControl);
520 if (entry->outcnt() != 1) {
521 // If a node is pinned between the predicates and the loop
522 // entry, we won't be able to move any node in the loop that
523 // depends on it above it in a predicate. Mark all those nodes
524 // as non loop invariatnt.
525 Unique_Node_List wq;
526 wq.push(entry);
527 for (uint next = 0; next < wq.size(); ++next) {
528 Node *n = wq.at(next);
529 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
530 Node* u = n->fast_out(i);
531 if (!u->is_CFG()) {
532 Node* c = _phase->get_ctrl(u);
533 if (_lpt->is_member(_phase->get_loop(c)) || _phase->is_dominator(c, head)) {
534 _visited.set(u->_idx);
535 wq.push(u);
536 }
537 }
538 }
539 }
540 }
541 }
542
543 // Map old to n for invariance computation and clone
544 void map_ctrl(Node* old, Node* n) {
545 assert(old->is_CFG() && n->is_CFG(), "must be");
546 _old_new.map(old->_idx, n); // "clone" of old is n
547 _invariant.set(old->_idx); // old is invariant
548 _clone_visited.set(old->_idx);
549 }
550
551 // Driver function to compute invariance
552 bool is_invariant(Node* n) {
553 if (!_visited.test_set(n->_idx))
554 compute_invariance(n);
555 return (_invariant.test(n->_idx) != 0);
556 }
557
558 // Driver function to clone invariant
559 Node* clone(Node* n, Node* ctrl) {
560 assert(ctrl->is_CFG(), "must be");
561 assert(_invariant.test(n->_idx), "must be an invariant");
562 if (!_clone_visited.test(n->_idx))
563 clone_nodes(n, ctrl);
564 return _old_new[n->_idx];
565 }
566 };
567
568 //------------------------------is_range_check_if -----------------------------------
569 // Returns true if the predicate of iff is in "scale*iv + offset u< load_range(ptr)" format
570 // Note: this function is particularly designed for loop predication. We require load_range
571 // and offset to be loop invariant computed on the fly by "invar"
572 bool IdealLoopTree::is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const {
573 if (!is_loop_exit(iff)) {
574 return false;
575 }
576 if (!iff->in(1)->is_Bool()) {
577 return false;
578 }
579 const BoolNode *bol = iff->in(1)->as_Bool();
580 if (bol->_test._test != BoolTest::lt) {
581 return false;
582 }
583 if (!bol->in(1)->is_Cmp()) {
584 return false;
585 }
586 const CmpNode *cmp = bol->in(1)->as_Cmp();
587 if (cmp->Opcode() != Op_CmpU) {
588 return false;
589 }
590 Node* range = cmp->in(2);
591 if (range->Opcode() != Op_LoadRange && !iff->is_RangeCheck()) {
592 const TypeInt* tint = phase->_igvn.type(range)->isa_int();
593 if (tint == NULL || tint->empty() || tint->_lo < 0) {
594 // Allow predication on positive values that aren't LoadRanges.
595 // This allows optimization of loops where the length of the
596 // array is a known value and doesn't need to be loaded back
597 // from the array.
598 return false;
599 }
600 }
601 if (!invar.is_invariant(range)) {
602 return false;
603 }
604 Node *iv = _head->as_CountedLoop()->phi();
605 int scale = 0;
606 Node *offset = NULL;
607 if (!phase->is_scaled_iv_plus_offset(cmp->in(1), iv, &scale, &offset)) {
608 return false;
609 }
610 if (offset && !invar.is_invariant(offset)) { // offset must be invariant
611 return false;
612 }
613 return true;
614 }
615
616 //------------------------------rc_predicate-----------------------------------
617 // Create a range check predicate
618 //
619 // for (i = init; i < limit; i += stride) {
620 // a[scale*i+offset]
621 // }
622 //
623 // Compute max(scale*i + offset) for init <= i < limit and build the predicate
624 // as "max(scale*i + offset) u< a.length".
625 //
626 // There are two cases for max(scale*i + offset):
627 // (1) stride*scale > 0
628 // max(scale*i + offset) = scale*(limit-stride) + offset
629 // (2) stride*scale < 0
630 // max(scale*i + offset) = scale*init + offset
631 BoolNode* PhaseIdealLoop::rc_predicate(IdealLoopTree *loop, Node* ctrl,
632 int scale, Node* offset,
633 Node* init, Node* limit, jint stride,
634 Node* range, bool upper, bool &overflow) {
635 jint con_limit = (limit != NULL && limit->is_Con()) ? limit->get_int() : 0;
636 jint con_init = init->is_Con() ? init->get_int() : 0;
637 jint con_offset = offset->is_Con() ? offset->get_int() : 0;
638
639 stringStream* predString = NULL;
640 if (TraceLoopPredicate) {
641 predString = new stringStream();
642 predString->print("rc_predicate ");
643 }
644
645 overflow = false;
646 Node* max_idx_expr = NULL;
647 const TypeInt* idx_type = TypeInt::INT;
648 if ((stride > 0) == (scale > 0) == upper) {
649 if (TraceLoopPredicate) {
650 if (limit->is_Con()) {
651 predString->print("(%d ", con_limit);
652 } else {
653 predString->print("(limit ");
654 }
655 predString->print("- %d) ", stride);
656 }
657 // Check if (limit - stride) may overflow
658 const TypeInt* limit_type = _igvn.type(limit)->isa_int();
659 jint limit_lo = limit_type->_lo;
660 jint limit_hi = limit_type->_hi;
661 if ((stride > 0 && (java_subtract(limit_lo, stride) < limit_lo)) ||
662 (stride < 0 && (java_subtract(limit_hi, stride) > limit_hi))) {
663 // No overflow possible
664 ConINode* con_stride = _igvn.intcon(stride);
665 set_ctrl(con_stride, C->root());
666 max_idx_expr = new SubINode(limit, con_stride);
667 idx_type = TypeInt::make(limit_lo - stride, limit_hi - stride, limit_type->_widen);
668 } else {
669 // May overflow
670 overflow = true;
671 limit = new ConvI2LNode(limit);
672 register_new_node(limit, ctrl);
673 ConLNode* con_stride = _igvn.longcon(stride);
674 set_ctrl(con_stride, C->root());
675 max_idx_expr = new SubLNode(limit, con_stride);
676 }
677 register_new_node(max_idx_expr, ctrl);
678 } else {
679 if (TraceLoopPredicate) {
680 if (init->is_Con()) {
681 predString->print("%d ", con_init);
682 } else {
683 predString->print("init ");
684 }
685 }
686 idx_type = _igvn.type(init)->isa_int();
687 max_idx_expr = init;
688 }
689
690 if (scale != 1) {
691 ConNode* con_scale = _igvn.intcon(scale);
692 set_ctrl(con_scale, C->root());
693 if (TraceLoopPredicate) {
694 predString->print("* %d ", scale);
695 }
696 // Check if (scale * max_idx_expr) may overflow
697 const TypeInt* scale_type = TypeInt::make(scale);
698 MulINode* mul = new MulINode(max_idx_expr, con_scale);
699 idx_type = (TypeInt*)mul->mul_ring(idx_type, scale_type);
700 if (overflow || TypeInt::INT->higher_equal(idx_type)) {
701 // May overflow
702 mul->destruct();
703 if (!overflow) {
704 max_idx_expr = new ConvI2LNode(max_idx_expr);
705 register_new_node(max_idx_expr, ctrl);
706 }
707 overflow = true;
708 con_scale = _igvn.longcon(scale);
709 set_ctrl(con_scale, C->root());
710 max_idx_expr = new MulLNode(max_idx_expr, con_scale);
711 } else {
712 // No overflow possible
713 max_idx_expr = mul;
714 }
715 register_new_node(max_idx_expr, ctrl);
716 }
717
718 if (offset && (!offset->is_Con() || con_offset != 0)){
719 if (TraceLoopPredicate) {
720 if (offset->is_Con()) {
721 predString->print("+ %d ", con_offset);
722 } else {
723 predString->print("+ offset");
724 }
725 }
726 // Check if (max_idx_expr + offset) may overflow
727 const TypeInt* offset_type = _igvn.type(offset)->isa_int();
728 jint lo = java_add(idx_type->_lo, offset_type->_lo);
729 jint hi = java_add(idx_type->_hi, offset_type->_hi);
730 if (overflow || (lo > hi) ||
731 ((idx_type->_lo & offset_type->_lo) < 0 && lo >= 0) ||
732 ((~(idx_type->_hi | offset_type->_hi)) < 0 && hi < 0)) {
733 // May overflow
734 if (!overflow) {
735 max_idx_expr = new ConvI2LNode(max_idx_expr);
736 register_new_node(max_idx_expr, ctrl);
737 }
738 overflow = true;
739 offset = new ConvI2LNode(offset);
740 register_new_node(offset, ctrl);
741 max_idx_expr = new AddLNode(max_idx_expr, offset);
742 } else {
743 // No overflow possible
744 max_idx_expr = new AddINode(max_idx_expr, offset);
745 }
746 register_new_node(max_idx_expr, ctrl);
747 }
748
749 CmpNode* cmp = NULL;
750 if (overflow) {
751 // Integer expressions may overflow, do long comparison
752 range = new ConvI2LNode(range);
753 register_new_node(range, ctrl);
754 cmp = new CmpULNode(max_idx_expr, range);
755 } else {
756 cmp = new CmpUNode(max_idx_expr, range);
757 }
758 register_new_node(cmp, ctrl);
759 BoolNode* bol = new BoolNode(cmp, BoolTest::lt);
760 register_new_node(bol, ctrl);
761
762 if (TraceLoopPredicate) {
763 predString->print_cr("<u range");
764 tty->print("%s", predString->as_string());
765 }
766 return bol;
767 }
768
769 // After pre/main/post loops are created, we'll put a copy of some
770 // range checks between the pre and main loop to validate the initial
771 // value of the induction variable for the main loop. Make a copy of
772 // the predicates here with an opaque node as a place holder for the
773 // initial value.
774 ProjNode* PhaseIdealLoop::insert_skeleton_predicate(IfNode* iff, IdealLoopTree *loop,
775 ProjNode* proj, ProjNode *predicate_proj,
776 ProjNode* upper_bound_proj,
777 int scale, Node* offset,
778 Node* init, Node* limit, jint stride,
779 Node* rng, bool &overflow) {
780 assert(proj->_con && predicate_proj->_con, "not a range check?");
781 Node* opaque_init = new Opaque1Node(C, init);
782 register_new_node(opaque_init, upper_bound_proj);
783 BoolNode* bol = rc_predicate(loop, upper_bound_proj, scale, offset, opaque_init, limit, stride, rng, (stride > 0) != (scale > 0), overflow);
784 Node* opaque_bol = new Opaque4Node(C, bol, _igvn.intcon(1)); // This will go away once loop opts are over
785 register_new_node(opaque_bol, upper_bound_proj);
786 ProjNode* new_proj = create_new_if_for_predicate(predicate_proj, NULL, Deoptimization::Reason_predicate, overflow ? Op_If : iff->Opcode());
787 _igvn.replace_input_of(new_proj->in(0), 1, opaque_bol);
788 assert(opaque_init->outcnt() > 0, "should be used");
789 return new_proj;
790 }
791
792 //------------------------------ loop_predication_impl--------------------------
793 // Insert loop predicates for null checks and range checks
794 bool PhaseIdealLoop::loop_predication_impl(IdealLoopTree *loop) {
795 if (!UseLoopPredicate) return false;
796
797 if (!loop->_head->is_Loop()) {
798 // Could be a simple region when irreducible loops are present.
799 return false;
800 }
801 LoopNode* head = loop->_head->as_Loop();
802
803 if (head->unique_ctrl_out()->Opcode() == Op_NeverBranch) {
804 // do nothing for infinite loops
805 return false;
806 }
807
808 if (head->is_OuterStripMinedLoop()) {
809 return false;
810 }
811
812 CountedLoopNode *cl = NULL;
813 if (head->is_valid_counted_loop()) {
814 cl = head->as_CountedLoop();
815 // do nothing for iteration-splitted loops
816 if (!cl->is_normal_loop()) return false;
817 // Avoid RCE if Counted loop's test is '!='.
818 BoolTest::mask bt = cl->loopexit()->test_trip();
819 if (bt != BoolTest::lt && bt != BoolTest::gt)
820 cl = NULL;
821 }
822
823 Node* entry = head->skip_strip_mined()->in(LoopNode::EntryControl);
824 ProjNode *predicate_proj = NULL;
825 // Loop limit check predicate should be near the loop.
826 predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
827 if (predicate_proj != NULL)
828 entry = predicate_proj->in(0)->in(0);
829 predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
830 if (!predicate_proj) {
831 #ifndef PRODUCT
832 if (TraceLoopPredicate) {
833 tty->print("missing predicate:");
834 loop->dump_head();
835 head->dump(1);
836 }
837 #endif
838 return false;
839 }
840 ConNode* zero = _igvn.intcon(0);
841 set_ctrl(zero, C->root());
842
843 ResourceArea *area = Thread::current()->resource_area();
844 Invariance invar(area, loop);
845
846 // Create list of if-projs such that a newer proj dominates all older
847 // projs in the list, and they all dominate loop->tail()
848 Node_List if_proj_list(area);
849 Node *current_proj = loop->tail(); //start from tail
850 while (current_proj != head) {
851 if (loop == get_loop(current_proj) && // still in the loop ?
852 current_proj->is_Proj() && // is a projection ?
853 (current_proj->in(0)->Opcode() == Op_If ||
854 current_proj->in(0)->Opcode() == Op_RangeCheck)) { // is a if projection ?
855 if_proj_list.push(current_proj);
856 }
857 current_proj = idom(current_proj);
858 }
859
860 bool hoisted = false; // true if at least one proj is promoted
861 while (if_proj_list.size() > 0) {
862 // Following are changed to nonnull when a predicate can be hoisted
863 ProjNode* new_predicate_proj = NULL;
864
865 ProjNode* proj = if_proj_list.pop()->as_Proj();
866 IfNode* iff = proj->in(0)->as_If();
867
868 if (!proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) {
869 if (loop->is_loop_exit(iff)) {
870 // stop processing the remaining projs in the list because the execution of them
871 // depends on the condition of "iff" (iff->in(1)).
872 break;
873 } else {
874 // Both arms are inside the loop. There are two cases:
875 // (1) there is one backward branch. In this case, any remaining proj
876 // in the if_proj list post-dominates "iff". So, the condition of "iff"
877 // does not determine the execution the remining projs directly, and we
878 // can safely continue.
879 // (2) both arms are forwarded, i.e. a diamond shape. In this case, "proj"
880 // does not dominate loop->tail(), so it can not be in the if_proj list.
881 continue;
882 }
883 }
884
885 Node* test = iff->in(1);
886 if (!test->is_Bool()){ //Conv2B, ...
887 continue;
888 }
889 BoolNode* bol = test->as_Bool();
890 if (invar.is_invariant(bol)) {
891 // Invariant test
892 new_predicate_proj = create_new_if_for_predicate(predicate_proj, NULL,
893 Deoptimization::Reason_predicate,
894 iff->Opcode());
895 Node* ctrl = new_predicate_proj->in(0)->as_If()->in(0);
896 BoolNode* new_predicate_bol = invar.clone(bol, ctrl)->as_Bool();
897
898 // Negate test if necessary
899 bool negated = false;
900 if (proj->_con != predicate_proj->_con) {
901 new_predicate_bol = new BoolNode(new_predicate_bol->in(1), new_predicate_bol->_test.negate());
902 register_new_node(new_predicate_bol, ctrl);
903 negated = true;
904 }
905 IfNode* new_predicate_iff = new_predicate_proj->in(0)->as_If();
906 _igvn.hash_delete(new_predicate_iff);
907 new_predicate_iff->set_req(1, new_predicate_bol);
908 #ifndef PRODUCT
909 if (TraceLoopPredicate) {
910 tty->print("Predicate invariant if%s: %d ", negated ? " negated" : "", new_predicate_iff->_idx);
911 loop->dump_head();
912 } else if (TraceLoopOpts) {
913 tty->print("Predicate IC ");
914 loop->dump_head();
915 }
916 #endif
917 } else if (cl != NULL && loop->is_range_check_if(iff, this, invar)) {
918 // Range check for counted loops
919 const Node* cmp = bol->in(1)->as_Cmp();
920 Node* idx = cmp->in(1);
921 assert(!invar.is_invariant(idx), "index is variant");
922 Node* rng = cmp->in(2);
923 assert(rng->Opcode() == Op_LoadRange || iff->is_RangeCheck() || _igvn.type(rng)->is_int()->_lo >= 0, "must be");
924 assert(invar.is_invariant(rng), "range must be invariant");
925 int scale = 1;
926 Node* offset = zero;
927 bool ok = is_scaled_iv_plus_offset(idx, cl->phi(), &scale, &offset);
928 assert(ok, "must be index expression");
929
930 Node* init = cl->init_trip();
931 // Limit is not exact.
932 // Calculate exact limit here.
933 // Note, counted loop's test is '<' or '>'.
934 Node* limit = exact_limit(loop);
935 int stride = cl->stride()->get_int();
936
937 // Build if's for the upper and lower bound tests. The
938 // lower_bound test will dominate the upper bound test and all
939 // cloned or created nodes will use the lower bound test as
940 // their declared control.
941
942 // Perform cloning to keep Invariance state correct since the
943 // late schedule will place invariant things in the loop.
944 Node *ctrl = predicate_proj->in(0)->as_If()->in(0);
945 rng = invar.clone(rng, ctrl);
946 if (offset && offset != zero) {
947 assert(invar.is_invariant(offset), "offset must be loop invariant");
948 offset = invar.clone(offset, ctrl);
949 }
950 // If predicate expressions may overflow in the integer range, longs are used.
951 bool overflow = false;
952
953 // Test the lower bound
954 BoolNode* lower_bound_bol = rc_predicate(loop, ctrl, scale, offset, init, limit, stride, rng, false, overflow);
955 // Negate test if necessary
956 bool negated = false;
957 if (proj->_con != predicate_proj->_con) {
958 lower_bound_bol = new BoolNode(lower_bound_bol->in(1), lower_bound_bol->_test.negate());
959 register_new_node(lower_bound_bol, ctrl);
960 negated = true;
961 }
962 ProjNode* lower_bound_proj = create_new_if_for_predicate(predicate_proj, NULL, Deoptimization::Reason_predicate, overflow ? Op_If : iff->Opcode());
963 IfNode* lower_bound_iff = lower_bound_proj->in(0)->as_If();
964 _igvn.hash_delete(lower_bound_iff);
965 lower_bound_iff->set_req(1, lower_bound_bol);
966 if (TraceLoopPredicate) tty->print_cr("lower bound check if: %s %d ", negated ? " negated" : "", lower_bound_iff->_idx);
967
968 // Test the upper bound
969 BoolNode* upper_bound_bol = rc_predicate(loop, lower_bound_proj, scale, offset, init, limit, stride, rng, true, overflow);
970 negated = false;
971 if (proj->_con != predicate_proj->_con) {
972 upper_bound_bol = new BoolNode(upper_bound_bol->in(1), upper_bound_bol->_test.negate());
973 register_new_node(upper_bound_bol, ctrl);
974 negated = true;
975 }
976 ProjNode* upper_bound_proj = create_new_if_for_predicate(predicate_proj, NULL, Deoptimization::Reason_predicate, overflow ? Op_If : iff->Opcode());
977 assert(upper_bound_proj->in(0)->as_If()->in(0) == lower_bound_proj, "should dominate");
978 IfNode* upper_bound_iff = upper_bound_proj->in(0)->as_If();
979 _igvn.hash_delete(upper_bound_iff);
980 upper_bound_iff->set_req(1, upper_bound_bol);
981 if (TraceLoopPredicate) tty->print_cr("upper bound check if: %s %d ", negated ? " negated" : "", lower_bound_iff->_idx);
982
983 // Fall through into rest of the clean up code which will move
984 // any dependent nodes onto the upper bound test.
985 new_predicate_proj = upper_bound_proj;
986
987 if (iff->is_RangeCheck()) {
988 new_predicate_proj = insert_skeleton_predicate(iff, loop, proj, predicate_proj, upper_bound_proj, scale, offset, init, limit, stride, rng, overflow);
989 }
990
991 #ifndef PRODUCT
992 if (TraceLoopOpts && !TraceLoopPredicate) {
993 tty->print("Predicate RC ");
994 loop->dump_head();
995 }
996 #endif
997 } else {
998 // Loop variant check (for example, range check in non-counted loop)
999 // with uncommon trap.
1000 continue;
1001 }
1002 assert(new_predicate_proj != NULL, "sanity");
1003 // Success - attach condition (new_predicate_bol) to predicate if
1004 invar.map_ctrl(proj, new_predicate_proj); // so that invariance test can be appropriate
1005
1006 // Eliminate the old If in the loop body
1007 dominated_by( new_predicate_proj, iff, proj->_con != new_predicate_proj->_con );
1008
1009 hoisted = true;
1010 C->set_major_progress();
1011 } // end while
1012
1013 #ifndef PRODUCT
1014 // report that the loop predication has been actually performed
1015 // for this loop
1016 if (TraceLoopPredicate && hoisted) {
1017 tty->print("Loop Predication Performed:");
1018 loop->dump_head();
1019 }
1020 #endif
1021
1022 head->verify_strip_mined(1);
1023
1024 return hoisted;
1025 }
1026
1027 //------------------------------loop_predication--------------------------------
1028 // driver routine for loop predication optimization
1029 bool IdealLoopTree::loop_predication( PhaseIdealLoop *phase) {
1030 bool hoisted = false;
1031 // Recursively promote predicates
1032 if (_child) {
1033 hoisted = _child->loop_predication( phase);
1034 }
1035
1036 // self
1037 if (!_irreducible && !tail()->is_top()) {
1038 hoisted |= phase->loop_predication_impl(this);
1039 }
1040
1041 if (_next) { //sibling
1042 hoisted |= _next->loop_predication( phase);
1043 }
1044
1045 return hoisted;
1046 }