1 /*
2 * Copyright (c) 2011, 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 "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-------------------------
register_control(Node * n,IdealLoopTree * loop,Node * pred)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 projection (if_cont) of the new_iff is returned.
95 // This code is also used to clone predicates to cloned loops.
create_new_if_for_predicate(ProjNode * cont_proj,Node * new_entry,Deoptimization::DeoptReason reason,int opcode)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_internal(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)
create_new_if_for_predicate(ProjNode * cont_proj,Node * new_entry,Deoptimization::DeoptReason reason,int opcode)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-----------------------
clone_predicate(ProjNode * predicate_proj,Node * new_entry,Deoptimization::DeoptReason reason,PhaseIdealLoop * loop_phase,PhaseIterGVN * igvn)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
clone_loop_predicates(Node * old_entry,Node * new_entry,bool clone_limit_check)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
clone_loop_predicates(Node * old_entry,Node * new_entry,bool clone_limit_check)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
clone_loop_predicates_fix_mem(ProjNode * dom_proj,ProjNode * proj,PhaseIdealLoop * loop_phase,PhaseIterGVN * igvn)304 void PhaseIdealLoop::clone_loop_predicates_fix_mem(ProjNode* dom_proj , ProjNode* proj,
305 PhaseIdealLoop* loop_phase,
306 PhaseIterGVN* igvn) {
307 Compile* C = NULL;
308 if (loop_phase != NULL) {
309 igvn = &loop_phase->igvn();
310 }
311 C = igvn->C;
312 ProjNode* other_dom_proj = dom_proj->in(0)->as_Multi()->proj_out(1-dom_proj->_con);
313 Node* dom_r = other_dom_proj->unique_ctrl_out();
314 if (dom_r->is_Region()) {
315 assert(dom_r->unique_ctrl_out()->is_Call(), "unc expected");
316 ProjNode* other_proj = proj->in(0)->as_Multi()->proj_out(1-proj->_con);
317 Node* r = other_proj->unique_ctrl_out();
318 assert(r->is_Region() && r->unique_ctrl_out()->is_Call(), "cloned predicate should have caused region to be added");
319 for (DUIterator_Fast imax, i = dom_r->fast_outs(imax); i < imax; i++) {
320 Node* dom_use = dom_r->fast_out(i);
321 if (dom_use->is_Phi() && dom_use->bottom_type() == Type::MEMORY) {
322 assert(dom_use->in(0) == dom_r, "");
323 Node* phi = NULL;
324 for (DUIterator_Fast jmax, j = r->fast_outs(jmax); j < jmax; j++) {
325 Node* use = r->fast_out(j);
326 if (use->is_Phi() && use->bottom_type() == Type::MEMORY &&
327 use->adr_type() == dom_use->adr_type()) {
328 assert(use->in(0) == r, "");
329 assert(phi == NULL, "only one phi");
330 phi = use;
331 }
332 }
333 if (phi == NULL) {
334 const TypePtr* adr_type = dom_use->adr_type();
335 int alias = C->get_alias_index(adr_type);
336 Node* call = r->unique_ctrl_out();
337 Node* mem = call->in(TypeFunc::Memory);
338 MergeMemNode* mm = NULL;
339 if (mem->is_MergeMem()) {
340 mm = mem->clone()->as_MergeMem();
341 if (adr_type == TypePtr::BOTTOM) {
342 mem = mem->as_MergeMem()->base_memory();
343 } else {
344 mem = mem->as_MergeMem()->memory_at(alias);
345 }
346 } else {
347 mm = MergeMemNode::make(mem);
348 }
349 phi = PhiNode::make(r, mem, Type::MEMORY, adr_type);
350 if (adr_type == TypePtr::BOTTOM) {
351 mm->set_base_memory(phi);
352 } else {
353 mm->set_memory_at(alias, phi);
354 }
355 if (loop_phase != NULL) {
356 loop_phase->register_new_node(mm, r);
357 loop_phase->register_new_node(phi, r);
358 } else {
359 igvn->register_new_node_with_optimizer(mm);
360 igvn->register_new_node_with_optimizer(phi);
361 }
362 igvn->replace_input_of(call, TypeFunc::Memory, mm);
363 }
364 igvn->replace_input_of(phi, r->find_edge(other_proj), dom_use->in(dom_r->find_edge(other_dom_proj)));
365 }
366 }
367 }
368 }
369
370
371 // Clone loop predicates to cloned loops (peeled, unswitched, split_if).
clone_loop_predicates(Node * old_entry,Node * new_entry,bool clone_limit_check,PhaseIdealLoop * loop_phase,PhaseIterGVN * igvn)372 Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry,
373 bool clone_limit_check,
374 PhaseIdealLoop* loop_phase,
375 PhaseIterGVN* igvn) {
376 #ifdef ASSERT
377 if (new_entry == NULL || !(new_entry->is_Proj() || new_entry->is_Region() || new_entry->is_SafePoint())) {
378 if (new_entry != NULL)
379 new_entry->dump();
380 assert(false, "not IfTrue, IfFalse, Region or SafePoint");
381 }
382 #endif
383 // Search original predicates
384 Node* entry = old_entry;
385 ProjNode* limit_check_proj = NULL;
386 limit_check_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
387 if (limit_check_proj != NULL) {
388 entry = skip_loop_predicates(entry);
389 }
390 ProjNode* profile_predicate_proj = NULL;
391 ProjNode* predicate_proj = NULL;
392 if (UseProfiledLoopPredicate) {
393 profile_predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_profile_predicate);
394 if (profile_predicate_proj != NULL) {
395 entry = skip_loop_predicates(entry);
396 }
397 }
398 if (UseLoopPredicate) {
399 predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
400 }
401 if (predicate_proj != NULL) { // right pattern that can be used by loop predication
402 // clone predicate
403 ProjNode* proj = clone_predicate(predicate_proj, new_entry,
404 Deoptimization::Reason_predicate,
405 loop_phase, igvn);
406 assert(proj != NULL, "IfTrue or IfFalse after clone predicate");
407 new_entry = proj;
408 if (TraceLoopPredicate) {
409 tty->print("Loop Predicate cloned: ");
410 debug_only( new_entry->in(0)->dump(); );
411 }
412 if (profile_predicate_proj != NULL) {
413 // A node that produces memory may be out of loop and depend on
414 // a profiled predicates. In that case the memory state at the
415 // end of profiled predicates and at the end of predicates are
416 // not the same. The cloned predicates are dominated by the
417 // profiled predicates but may have the wrong memory
418 // state. Update it.
419 clone_loop_predicates_fix_mem(profile_predicate_proj, proj, loop_phase, igvn);
420 }
421 }
422 if (profile_predicate_proj != NULL) { // right pattern that can be used by loop predication
423 // clone predicate
424 new_entry = clone_predicate(profile_predicate_proj, new_entry,
425 Deoptimization::Reason_profile_predicate,
426 loop_phase, igvn);
427 assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone predicate");
428 if (TraceLoopPredicate) {
429 tty->print("Loop Predicate cloned: ");
430 debug_only( new_entry->in(0)->dump(); );
431 }
432 }
433 if (limit_check_proj != NULL && clone_limit_check) {
434 // Clone loop limit check last to insert it before loop.
435 // Don't clone a limit check which was already finalized
436 // for this counted loop (only one limit check is needed).
437 new_entry = clone_predicate(limit_check_proj, new_entry,
438 Deoptimization::Reason_loop_limit_check,
439 loop_phase, igvn);
440 assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone limit check");
441 if (TraceLoopLimitCheck) {
442 tty->print("Loop Limit Check cloned: ");
443 debug_only( new_entry->in(0)->dump(); )
444 }
445 }
446 return new_entry;
447 }
448
449 //--------------------------skip_loop_predicates------------------------------
450 // Skip related predicates.
skip_loop_predicates(Node * entry)451 Node* PhaseIdealLoop::skip_loop_predicates(Node* entry) {
452 IfNode* iff = entry->in(0)->as_If();
453 ProjNode* uncommon_proj = iff->proj_out(1 - entry->as_Proj()->_con);
454 Node* rgn = uncommon_proj->unique_ctrl_out();
455 assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct");
456 entry = entry->in(0)->in(0);
457 while (entry != NULL && entry->is_Proj() && entry->in(0)->is_If()) {
458 uncommon_proj = entry->in(0)->as_If()->proj_out(1 - entry->as_Proj()->_con);
459 if (uncommon_proj->unique_ctrl_out() != rgn)
460 break;
461 entry = entry->in(0)->in(0);
462 }
463 return entry;
464 }
465
skip_all_loop_predicates(Node * entry)466 Node* PhaseIdealLoop::skip_all_loop_predicates(Node* entry) {
467 Node* predicate = NULL;
468 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
469 if (predicate != NULL) {
470 entry = skip_loop_predicates(entry);
471 }
472 if (UseProfiledLoopPredicate) {
473 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_profile_predicate);
474 if (predicate != NULL) { // right pattern that can be used by loop predication
475 entry = skip_loop_predicates(entry);
476 }
477 }
478 if (UseLoopPredicate) {
479 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
480 if (predicate != NULL) { // right pattern that can be used by loop predication
481 entry = skip_loop_predicates(entry);
482 }
483 }
484 return entry;
485 }
486
487 //--------------------------find_predicate_insertion_point-------------------
488 // Find a good location to insert a predicate
find_predicate_insertion_point(Node * start_c,Deoptimization::DeoptReason reason)489 ProjNode* PhaseIdealLoop::find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason) {
490 if (start_c == NULL || !start_c->is_Proj())
491 return NULL;
492 if (start_c->as_Proj()->is_uncommon_trap_if_pattern(reason)) {
493 return start_c->as_Proj();
494 }
495 return NULL;
496 }
497
498 //--------------------------find_predicate------------------------------------
499 // Find a predicate
find_predicate(Node * entry)500 Node* PhaseIdealLoop::find_predicate(Node* entry) {
501 Node* predicate = NULL;
502 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
503 if (predicate != NULL) { // right pattern that can be used by loop predication
504 return entry;
505 }
506 if (UseLoopPredicate) {
507 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
508 if (predicate != NULL) { // right pattern that can be used by loop predication
509 return entry;
510 }
511 }
512 if (UseProfiledLoopPredicate) {
513 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_profile_predicate);
514 if (predicate != NULL) { // right pattern that can be used by loop predication
515 return entry;
516 }
517 }
518 return NULL;
519 }
520
521 //------------------------------Invariance-----------------------------------
522 // Helper class for loop_predication_impl to compute invariance on the fly and
523 // clone invariants.
524 class Invariance : public StackObj {
525 VectorSet _visited, _invariant;
526 Node_Stack _stack;
527 VectorSet _clone_visited;
528 Node_List _old_new; // map of old to new (clone)
529 IdealLoopTree* _lpt;
530 PhaseIdealLoop* _phase;
531
532 // Helper function to set up the invariance for invariance computation
533 // If n is a known invariant, set up directly. Otherwise, look up the
534 // the possibility to push n onto the stack for further processing.
visit(Node * use,Node * n)535 void visit(Node* use, Node* n) {
536 if (_lpt->is_invariant(n)) { // known invariant
537 _invariant.set(n->_idx);
538 } else if (!n->is_CFG()) {
539 Node *n_ctrl = _phase->ctrl_or_self(n);
540 Node *u_ctrl = _phase->ctrl_or_self(use); // self if use is a CFG
541 if (_phase->is_dominator(n_ctrl, u_ctrl)) {
542 _stack.push(n, n->in(0) == NULL ? 1 : 0);
543 }
544 }
545 }
546
547 // Compute invariance for "the_node" and (possibly) all its inputs recursively
548 // on the fly
compute_invariance(Node * n)549 void compute_invariance(Node* n) {
550 assert(_visited.test(n->_idx), "must be");
551 visit(n, n);
552 while (_stack.is_nonempty()) {
553 Node* n = _stack.node();
554 uint idx = _stack.index();
555 if (idx == n->req()) { // all inputs are processed
556 _stack.pop();
557 // n is invariant if it's inputs are all invariant
558 bool all_inputs_invariant = true;
559 for (uint i = 0; i < n->req(); i++) {
560 Node* in = n->in(i);
561 if (in == NULL) continue;
562 assert(_visited.test(in->_idx), "must have visited input");
563 if (!_invariant.test(in->_idx)) { // bad guy
564 all_inputs_invariant = false;
565 break;
566 }
567 }
568 if (all_inputs_invariant) {
569 // If n's control is a predicate that was moved out of the
570 // loop, it was marked invariant but n is only invariant if
571 // it depends only on that test. Otherwise, unless that test
572 // is out of the loop, it's not invariant.
573 if (n->is_CFG() || n->depends_only_on_test() || n->in(0) == NULL || !_phase->is_member(_lpt, n->in(0))) {
574 _invariant.set(n->_idx); // I am a invariant too
575 }
576 }
577 } else { // process next input
578 _stack.set_index(idx + 1);
579 Node* m = n->in(idx);
580 if (m != NULL && !_visited.test_set(m->_idx)) {
581 visit(n, m);
582 }
583 }
584 }
585 }
586
587 // Helper function to set up _old_new map for clone_nodes.
588 // If n is a known invariant, set up directly ("clone" of n == n).
589 // Otherwise, push n onto the stack for real cloning.
clone_visit(Node * n)590 void clone_visit(Node* n) {
591 assert(_invariant.test(n->_idx), "must be invariant");
592 if (_lpt->is_invariant(n)) { // known invariant
593 _old_new.map(n->_idx, n);
594 } else { // to be cloned
595 assert(!n->is_CFG(), "should not see CFG here");
596 _stack.push(n, n->in(0) == NULL ? 1 : 0);
597 }
598 }
599
600 // Clone "n" and (possibly) all its inputs recursively
clone_nodes(Node * n,Node * ctrl)601 void clone_nodes(Node* n, Node* ctrl) {
602 clone_visit(n);
603 while (_stack.is_nonempty()) {
604 Node* n = _stack.node();
605 uint idx = _stack.index();
606 if (idx == n->req()) { // all inputs processed, clone n!
607 _stack.pop();
608 // clone invariant node
609 Node* n_cl = n->clone();
610 _old_new.map(n->_idx, n_cl);
611 _phase->register_new_node(n_cl, ctrl);
612 for (uint i = 0; i < n->req(); i++) {
613 Node* in = n_cl->in(i);
614 if (in == NULL) continue;
615 n_cl->set_req(i, _old_new[in->_idx]);
616 }
617 } else { // process next input
618 _stack.set_index(idx + 1);
619 Node* m = n->in(idx);
620 if (m != NULL && !_clone_visited.test_set(m->_idx)) {
621 clone_visit(m); // visit the input
622 }
623 }
624 }
625 }
626
627 public:
Invariance(Arena * area,IdealLoopTree * lpt)628 Invariance(Arena* area, IdealLoopTree* lpt) :
629 _visited(area), _invariant(area),
630 _stack(area, 10 /* guess */),
631 _clone_visited(area), _old_new(area),
632 _lpt(lpt), _phase(lpt->_phase)
633 {
634 LoopNode* head = _lpt->_head->as_Loop();
635 Node* entry = head->skip_strip_mined()->in(LoopNode::EntryControl);
636 if (entry->outcnt() != 1) {
637 // If a node is pinned between the predicates and the loop
638 // entry, we won't be able to move any node in the loop that
639 // depends on it above it in a predicate. Mark all those nodes
640 // as non loop invariatnt.
641 Unique_Node_List wq;
642 wq.push(entry);
643 for (uint next = 0; next < wq.size(); ++next) {
644 Node *n = wq.at(next);
645 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
646 Node* u = n->fast_out(i);
647 if (!u->is_CFG()) {
648 Node* c = _phase->get_ctrl(u);
649 if (_lpt->is_member(_phase->get_loop(c)) || _phase->is_dominator(c, head)) {
650 _visited.set(u->_idx);
651 wq.push(u);
652 }
653 }
654 }
655 }
656 }
657 }
658
659 // Map old to n for invariance computation and clone
map_ctrl(Node * old,Node * n)660 void map_ctrl(Node* old, Node* n) {
661 assert(old->is_CFG() && n->is_CFG(), "must be");
662 _old_new.map(old->_idx, n); // "clone" of old is n
663 _invariant.set(old->_idx); // old is invariant
664 _clone_visited.set(old->_idx);
665 }
666
667 // Driver function to compute invariance
is_invariant(Node * n)668 bool is_invariant(Node* n) {
669 if (!_visited.test_set(n->_idx))
670 compute_invariance(n);
671 return (_invariant.test(n->_idx) != 0);
672 }
673
674 // Driver function to clone invariant
clone(Node * n,Node * ctrl)675 Node* clone(Node* n, Node* ctrl) {
676 assert(ctrl->is_CFG(), "must be");
677 assert(_invariant.test(n->_idx), "must be an invariant");
678 if (!_clone_visited.test(n->_idx))
679 clone_nodes(n, ctrl);
680 return _old_new[n->_idx];
681 }
682 };
683
684 //------------------------------is_range_check_if -----------------------------------
685 // Returns true if the predicate of iff is in "scale*iv + offset u< load_range(ptr)" format
686 // Note: this function is particularly designed for loop predication. We require load_range
687 // and offset to be loop invariant computed on the fly by "invar"
is_range_check_if(IfNode * iff,PhaseIdealLoop * phase,Invariance & invar) const688 bool IdealLoopTree::is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const {
689 if (!is_loop_exit(iff)) {
690 return false;
691 }
692 if (!iff->in(1)->is_Bool()) {
693 return false;
694 }
695 const BoolNode *bol = iff->in(1)->as_Bool();
696 if (bol->_test._test != BoolTest::lt) {
697 return false;
698 }
699 if (!bol->in(1)->is_Cmp()) {
700 return false;
701 }
702 const CmpNode *cmp = bol->in(1)->as_Cmp();
703 if (cmp->Opcode() != Op_CmpU) {
704 return false;
705 }
706 Node* range = cmp->in(2);
707 if (range->Opcode() != Op_LoadRange && !iff->is_RangeCheck()) {
708 const TypeInt* tint = phase->_igvn.type(range)->isa_int();
709 if (tint == NULL || tint->empty() || tint->_lo < 0) {
710 // Allow predication on positive values that aren't LoadRanges.
711 // This allows optimization of loops where the length of the
712 // array is a known value and doesn't need to be loaded back
713 // from the array.
714 return false;
715 }
716 }
717 if (!invar.is_invariant(range)) {
718 return false;
719 }
720 Node *iv = _head->as_CountedLoop()->phi();
721 int scale = 0;
722 Node *offset = NULL;
723 if (!phase->is_scaled_iv_plus_offset(cmp->in(1), iv, &scale, &offset)) {
724 return false;
725 }
726 if (offset && !invar.is_invariant(offset)) { // offset must be invariant
727 return false;
728 }
729 return true;
730 }
731
732 //------------------------------rc_predicate-----------------------------------
733 // Create a range check predicate
734 //
735 // for (i = init; i < limit; i += stride) {
736 // a[scale*i+offset]
737 // }
738 //
739 // Compute max(scale*i + offset) for init <= i < limit and build the predicate
740 // as "max(scale*i + offset) u< a.length".
741 //
742 // There are two cases for max(scale*i + offset):
743 // (1) stride*scale > 0
744 // max(scale*i + offset) = scale*(limit-stride) + offset
745 // (2) stride*scale < 0
746 // max(scale*i + offset) = scale*init + offset
rc_predicate(IdealLoopTree * loop,Node * ctrl,int scale,Node * offset,Node * init,Node * limit,jint stride,Node * range,bool upper,bool & overflow)747 BoolNode* PhaseIdealLoop::rc_predicate(IdealLoopTree *loop, Node* ctrl,
748 int scale, Node* offset,
749 Node* init, Node* limit, jint stride,
750 Node* range, bool upper, bool &overflow) {
751 jint con_limit = (limit != NULL && limit->is_Con()) ? limit->get_int() : 0;
752 jint con_init = init->is_Con() ? init->get_int() : 0;
753 jint con_offset = offset->is_Con() ? offset->get_int() : 0;
754
755 stringStream* predString = NULL;
756 if (TraceLoopPredicate) {
757 predString = new stringStream();
758 predString->print("rc_predicate ");
759 }
760
761 overflow = false;
762 Node* max_idx_expr = NULL;
763 const TypeInt* idx_type = TypeInt::INT;
764 if ((stride > 0) == (scale > 0) == upper) {
765 guarantee(limit != NULL, "sanity");
766 if (TraceLoopPredicate) {
767 if (limit->is_Con()) {
768 predString->print("(%d ", con_limit);
769 } else {
770 predString->print("(limit ");
771 }
772 predString->print("- %d) ", stride);
773 }
774 // Check if (limit - stride) may overflow
775 const TypeInt* limit_type = _igvn.type(limit)->isa_int();
776 jint limit_lo = limit_type->_lo;
777 jint limit_hi = limit_type->_hi;
778 if ((stride > 0 && (java_subtract(limit_lo, stride) < limit_lo)) ||
779 (stride < 0 && (java_subtract(limit_hi, stride) > limit_hi))) {
780 // No overflow possible
781 ConINode* con_stride = _igvn.intcon(stride);
782 set_ctrl(con_stride, C->root());
783 max_idx_expr = new SubINode(limit, con_stride);
784 idx_type = TypeInt::make(limit_lo - stride, limit_hi - stride, limit_type->_widen);
785 } else {
786 // May overflow
787 overflow = true;
788 limit = new ConvI2LNode(limit);
789 register_new_node(limit, ctrl);
790 ConLNode* con_stride = _igvn.longcon(stride);
791 set_ctrl(con_stride, C->root());
792 max_idx_expr = new SubLNode(limit, con_stride);
793 }
794 register_new_node(max_idx_expr, ctrl);
795 } else {
796 if (TraceLoopPredicate) {
797 if (init->is_Con()) {
798 predString->print("%d ", con_init);
799 } else {
800 predString->print("init ");
801 }
802 }
803 idx_type = _igvn.type(init)->isa_int();
804 max_idx_expr = init;
805 }
806
807 if (scale != 1) {
808 ConNode* con_scale = _igvn.intcon(scale);
809 set_ctrl(con_scale, C->root());
810 if (TraceLoopPredicate) {
811 predString->print("* %d ", scale);
812 }
813 // Check if (scale * max_idx_expr) may overflow
814 const TypeInt* scale_type = TypeInt::make(scale);
815 MulINode* mul = new MulINode(max_idx_expr, con_scale);
816 idx_type = (TypeInt*)mul->mul_ring(idx_type, scale_type);
817 if (overflow || TypeInt::INT->higher_equal(idx_type)) {
818 // May overflow
819 mul->destruct();
820 if (!overflow) {
821 max_idx_expr = new ConvI2LNode(max_idx_expr);
822 register_new_node(max_idx_expr, ctrl);
823 }
824 overflow = true;
825 con_scale = _igvn.longcon(scale);
826 set_ctrl(con_scale, C->root());
827 max_idx_expr = new MulLNode(max_idx_expr, con_scale);
828 } else {
829 // No overflow possible
830 max_idx_expr = mul;
831 }
832 register_new_node(max_idx_expr, ctrl);
833 }
834
835 if (offset && (!offset->is_Con() || con_offset != 0)){
836 if (TraceLoopPredicate) {
837 if (offset->is_Con()) {
838 predString->print("+ %d ", con_offset);
839 } else {
840 predString->print("+ offset");
841 }
842 }
843 // Check if (max_idx_expr + offset) may overflow
844 const TypeInt* offset_type = _igvn.type(offset)->isa_int();
845 jint lo = java_add(idx_type->_lo, offset_type->_lo);
846 jint hi = java_add(idx_type->_hi, offset_type->_hi);
847 if (overflow || (lo > hi) ||
848 ((idx_type->_lo & offset_type->_lo) < 0 && lo >= 0) ||
849 ((~(idx_type->_hi | offset_type->_hi)) < 0 && hi < 0)) {
850 // May overflow
851 if (!overflow) {
852 max_idx_expr = new ConvI2LNode(max_idx_expr);
853 register_new_node(max_idx_expr, ctrl);
854 }
855 overflow = true;
856 offset = new ConvI2LNode(offset);
857 register_new_node(offset, ctrl);
858 max_idx_expr = new AddLNode(max_idx_expr, offset);
859 } else {
860 // No overflow possible
861 max_idx_expr = new AddINode(max_idx_expr, offset);
862 }
863 register_new_node(max_idx_expr, ctrl);
864 }
865
866 CmpNode* cmp = NULL;
867 if (overflow) {
868 // Integer expressions may overflow, do long comparison
869 range = new ConvI2LNode(range);
870 register_new_node(range, ctrl);
871 cmp = new CmpULNode(max_idx_expr, range);
872 } else {
873 cmp = new CmpUNode(max_idx_expr, range);
874 }
875 register_new_node(cmp, ctrl);
876 BoolNode* bol = new BoolNode(cmp, BoolTest::lt);
877 register_new_node(bol, ctrl);
878
879 if (TraceLoopPredicate) {
880 predString->print_cr("<u range");
881 tty->print("%s", predString->base());
882 predString->~stringStream();
883 }
884 return bol;
885 }
886
887 // Should loop predication look not only in the path from tail to head
888 // but also in branches of the loop body?
loop_predication_should_follow_branches(IdealLoopTree * loop,ProjNode * predicate_proj,float & loop_trip_cnt)889 bool PhaseIdealLoop::loop_predication_should_follow_branches(IdealLoopTree *loop, ProjNode *predicate_proj, float& loop_trip_cnt) {
890 if (!UseProfiledLoopPredicate) {
891 return false;
892 }
893
894 if (predicate_proj == NULL) {
895 return false;
896 }
897
898 LoopNode* head = loop->_head->as_Loop();
899 bool follow_branches = true;
900 IdealLoopTree* l = loop->_child;
901 // For leaf loops and loops with a single inner loop
902 while (l != NULL && follow_branches) {
903 IdealLoopTree* child = l;
904 if (child->_child != NULL &&
905 child->_head->is_OuterStripMinedLoop()) {
906 assert(child->_child->_next == NULL, "only one inner loop for strip mined loop");
907 assert(child->_child->_head->is_CountedLoop() && child->_child->_head->as_CountedLoop()->is_strip_mined(), "inner loop should be strip mined");
908 child = child->_child;
909 }
910 if (child->_child != NULL || child->_irreducible) {
911 follow_branches = false;
912 }
913 l = l->_next;
914 }
915 if (follow_branches) {
916 loop->compute_profile_trip_cnt(this);
917 if (head->is_profile_trip_failed()) {
918 follow_branches = false;
919 } else {
920 loop_trip_cnt = head->profile_trip_cnt();
921 if (head->is_CountedLoop()) {
922 CountedLoopNode* cl = head->as_CountedLoop();
923 if (cl->phi() != NULL) {
924 const TypeInt* t = _igvn.type(cl->phi())->is_int();
925 float worst_case_trip_cnt = ((float)t->_hi - t->_lo) / ABS(cl->stride_con());
926 if (worst_case_trip_cnt < loop_trip_cnt) {
927 loop_trip_cnt = worst_case_trip_cnt;
928 }
929 }
930 }
931 }
932 }
933 return follow_branches;
934 }
935
936 // Compute probability of reaching some CFG node from a fixed
937 // dominating CFG node
938 class PathFrequency {
939 private:
940 Node* _dom; // frequencies are computed relative to this node
941 Node_Stack _stack;
942 GrowableArray<float> _freqs_stack; // keep track of intermediate result at regions
943 GrowableArray<float> _freqs; // cache frequencies
944 PhaseIdealLoop* _phase;
945
set_rounding(int mode)946 void set_rounding(int mode) {
947 // fesetround is broken on windows
948 NOT_WINDOWS(fesetround(mode);)
949 }
950
check_frequency(float f)951 void check_frequency(float f) {
952 NOT_WINDOWS(assert(f <= 1 && f >= 0, "Incorrect frequency");)
953 }
954
955 public:
PathFrequency(Node * dom,PhaseIdealLoop * phase)956 PathFrequency(Node* dom, PhaseIdealLoop* phase)
957 : _dom(dom), _stack(0), _phase(phase) {
958 }
959
to(Node * n)960 float to(Node* n) {
961 // post order walk on the CFG graph from n to _dom
962 set_rounding(FE_TOWARDZERO); // make sure rounding doesn't push frequency above 1
963 IdealLoopTree* loop = _phase->get_loop(_dom);
964 Node* c = n;
965 for (;;) {
966 assert(_phase->get_loop(c) == loop, "have to be in the same loop");
967 if (c == _dom || _freqs.at_grow(c->_idx, -1) >= 0) {
968 float f = c == _dom ? 1 : _freqs.at(c->_idx);
969 Node* prev = c;
970 while (_stack.size() > 0 && prev == c) {
971 Node* n = _stack.node();
972 if (!n->is_Region()) {
973 if (_phase->get_loop(n) != _phase->get_loop(n->in(0))) {
974 // Found an inner loop: compute frequency of reaching this
975 // exit from the loop head by looking at the number of
976 // times each loop exit was taken
977 IdealLoopTree* inner_loop = _phase->get_loop(n->in(0));
978 LoopNode* inner_head = inner_loop->_head->as_Loop();
979 assert(_phase->get_loop(n) == loop, "only 1 inner loop");
980 if (inner_head->is_OuterStripMinedLoop()) {
981 inner_head->verify_strip_mined(1);
982 if (n->in(0) == inner_head->in(LoopNode::LoopBackControl)->in(0)) {
983 n = n->in(0)->in(0)->in(0);
984 }
985 inner_loop = inner_loop->_child;
986 inner_head = inner_loop->_head->as_Loop();
987 inner_head->verify_strip_mined(1);
988 }
989 set_rounding(FE_UPWARD); // make sure rounding doesn't push frequency above 1
990 float loop_exit_cnt = 0.0f;
991 for (uint i = 0; i < inner_loop->_body.size(); i++) {
992 Node *n = inner_loop->_body[i];
993 float c = inner_loop->compute_profile_trip_cnt_helper(n);
994 loop_exit_cnt += c;
995 }
996 set_rounding(FE_TOWARDZERO);
997 float cnt = -1;
998 if (n->in(0)->is_If()) {
999 IfNode* iff = n->in(0)->as_If();
1000 float p = n->in(0)->as_If()->_prob;
1001 if (n->Opcode() == Op_IfFalse) {
1002 p = 1 - p;
1003 }
1004 if (p > PROB_MIN) {
1005 cnt = p * iff->_fcnt;
1006 } else {
1007 cnt = 0;
1008 }
1009 } else {
1010 assert(n->in(0)->is_Jump(), "unsupported node kind");
1011 JumpNode* jmp = n->in(0)->as_Jump();
1012 float p = n->in(0)->as_Jump()->_probs[n->as_JumpProj()->_con];
1013 cnt = p * jmp->_fcnt;
1014 }
1015 float this_exit_f = cnt > 0 ? cnt / loop_exit_cnt : 0;
1016 check_frequency(this_exit_f);
1017 f = f * this_exit_f;
1018 check_frequency(f);
1019 } else {
1020 float p = -1;
1021 if (n->in(0)->is_If()) {
1022 p = n->in(0)->as_If()->_prob;
1023 if (n->Opcode() == Op_IfFalse) {
1024 p = 1 - p;
1025 }
1026 } else {
1027 assert(n->in(0)->is_Jump(), "unsupported node kind");
1028 p = n->in(0)->as_Jump()->_probs[n->as_JumpProj()->_con];
1029 }
1030 f = f * p;
1031 check_frequency(f);
1032 }
1033 _freqs.at_put_grow(n->_idx, (float)f, -1);
1034 _stack.pop();
1035 } else {
1036 float prev_f = _freqs_stack.pop();
1037 float new_f = f;
1038 f = new_f + prev_f;
1039 check_frequency(f);
1040 uint i = _stack.index();
1041 if (i < n->req()) {
1042 c = n->in(i);
1043 _stack.set_index(i+1);
1044 _freqs_stack.push(f);
1045 } else {
1046 _freqs.at_put_grow(n->_idx, f, -1);
1047 _stack.pop();
1048 }
1049 }
1050 }
1051 if (_stack.size() == 0) {
1052 set_rounding(FE_TONEAREST);
1053 check_frequency(f);
1054 return f;
1055 }
1056 } else if (c->is_Loop()) {
1057 ShouldNotReachHere();
1058 c = c->in(LoopNode::EntryControl);
1059 } else if (c->is_Region()) {
1060 _freqs_stack.push(0);
1061 _stack.push(c, 2);
1062 c = c->in(1);
1063 } else {
1064 if (c->is_IfProj()) {
1065 IfNode* iff = c->in(0)->as_If();
1066 if (iff->_prob == PROB_UNKNOWN) {
1067 // assume never taken
1068 _freqs.at_put_grow(c->_idx, 0, -1);
1069 } else if (_phase->get_loop(c) != _phase->get_loop(iff)) {
1070 if (iff->_fcnt == COUNT_UNKNOWN) {
1071 // assume never taken
1072 _freqs.at_put_grow(c->_idx, 0, -1);
1073 } else {
1074 // skip over loop
1075 _stack.push(c, 1);
1076 c = _phase->get_loop(c->in(0))->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl);
1077 }
1078 } else {
1079 _stack.push(c, 1);
1080 c = iff;
1081 }
1082 } else if (c->is_JumpProj()) {
1083 JumpNode* jmp = c->in(0)->as_Jump();
1084 if (_phase->get_loop(c) != _phase->get_loop(jmp)) {
1085 if (jmp->_fcnt == COUNT_UNKNOWN) {
1086 // assume never taken
1087 _freqs.at_put_grow(c->_idx, 0, -1);
1088 } else {
1089 // skip over loop
1090 _stack.push(c, 1);
1091 c = _phase->get_loop(c->in(0))->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl);
1092 }
1093 } else {
1094 _stack.push(c, 1);
1095 c = jmp;
1096 }
1097 } else if (c->Opcode() == Op_CatchProj &&
1098 c->in(0)->Opcode() == Op_Catch &&
1099 c->in(0)->in(0)->is_Proj() &&
1100 c->in(0)->in(0)->in(0)->is_Call()) {
1101 // assume exceptions are never thrown
1102 uint con = c->as_Proj()->_con;
1103 if (con == CatchProjNode::fall_through_index) {
1104 Node* call = c->in(0)->in(0)->in(0)->in(0);
1105 if (_phase->get_loop(call) != _phase->get_loop(c)) {
1106 _freqs.at_put_grow(c->_idx, 0, -1);
1107 } else {
1108 c = call;
1109 }
1110 } else {
1111 assert(con >= CatchProjNode::catch_all_index, "what else?");
1112 _freqs.at_put_grow(c->_idx, 0, -1);
1113 }
1114 } else if (c->unique_ctrl_out() == NULL && !c->is_If() && !c->is_Jump()) {
1115 ShouldNotReachHere();
1116 } else {
1117 c = c->in(0);
1118 }
1119 }
1120 }
1121 ShouldNotReachHere();
1122 return -1;
1123 }
1124 };
1125
loop_predication_follow_branches(Node * n,IdealLoopTree * loop,float loop_trip_cnt,PathFrequency & pf,Node_Stack & stack,VectorSet & seen,Node_List & if_proj_list)1126 void PhaseIdealLoop::loop_predication_follow_branches(Node *n, IdealLoopTree *loop, float loop_trip_cnt,
1127 PathFrequency& pf, Node_Stack& stack, VectorSet& seen,
1128 Node_List& if_proj_list) {
1129 assert(n->is_Region(), "start from a region");
1130 Node* tail = loop->tail();
1131 stack.push(n, 1);
1132 do {
1133 Node* c = stack.node();
1134 assert(c->is_Region() || c->is_IfProj(), "only region here");
1135 uint i = stack.index();
1136
1137 if (i < c->req()) {
1138 stack.set_index(i+1);
1139 Node* in = c->in(i);
1140 while (!is_dominator(in, tail) && !seen.test_set(in->_idx)) {
1141 IdealLoopTree* in_loop = get_loop(in);
1142 if (in_loop != loop) {
1143 in = in_loop->_head->in(LoopNode::EntryControl);
1144 } else if (in->is_Region()) {
1145 stack.push(in, 1);
1146 break;
1147 } else if (in->is_IfProj() &&
1148 in->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none) &&
1149 (in->in(0)->Opcode() == Op_If ||
1150 in->in(0)->Opcode() == Op_RangeCheck)) {
1151 if (pf.to(in) * loop_trip_cnt >= 1) {
1152 stack.push(in, 1);
1153 }
1154 in = in->in(0);
1155 } else {
1156 in = in->in(0);
1157 }
1158 }
1159 } else {
1160 if (c->is_IfProj()) {
1161 if_proj_list.push(c);
1162 }
1163 stack.pop();
1164 }
1165
1166 } while (stack.size() > 0);
1167 }
1168
1169
loop_predication_impl_helper(IdealLoopTree * loop,ProjNode * proj,ProjNode * predicate_proj,CountedLoopNode * cl,ConNode * zero,Invariance & invar,Deoptimization::DeoptReason reason)1170 bool PhaseIdealLoop::loop_predication_impl_helper(IdealLoopTree *loop, ProjNode* proj, ProjNode *predicate_proj,
1171 CountedLoopNode *cl, ConNode* zero, Invariance& invar,
1172 Deoptimization::DeoptReason reason) {
1173 // Following are changed to nonnull when a predicate can be hoisted
1174 ProjNode* new_predicate_proj = NULL;
1175 IfNode* iff = proj->in(0)->as_If();
1176 Node* test = iff->in(1);
1177 if (!test->is_Bool()){ //Conv2B, ...
1178 return false;
1179 }
1180 BoolNode* bol = test->as_Bool();
1181 if (invar.is_invariant(bol)) {
1182 // Invariant test
1183 new_predicate_proj = create_new_if_for_predicate(predicate_proj, NULL,
1184 reason,
1185 iff->Opcode());
1186 Node* ctrl = new_predicate_proj->in(0)->as_If()->in(0);
1187 BoolNode* new_predicate_bol = invar.clone(bol, ctrl)->as_Bool();
1188
1189 // Negate test if necessary
1190 bool negated = false;
1191 if (proj->_con != predicate_proj->_con) {
1192 new_predicate_bol = new BoolNode(new_predicate_bol->in(1), new_predicate_bol->_test.negate());
1193 register_new_node(new_predicate_bol, ctrl);
1194 negated = true;
1195 }
1196 IfNode* new_predicate_iff = new_predicate_proj->in(0)->as_If();
1197 _igvn.hash_delete(new_predicate_iff);
1198 new_predicate_iff->set_req(1, new_predicate_bol);
1199 #ifndef PRODUCT
1200 if (TraceLoopPredicate) {
1201 tty->print("Predicate invariant if%s: %d ", negated ? " negated" : "", new_predicate_iff->_idx);
1202 loop->dump_head();
1203 } else if (TraceLoopOpts) {
1204 tty->print("Predicate IC ");
1205 loop->dump_head();
1206 }
1207 #endif
1208 } else if (cl != NULL && loop->is_range_check_if(iff, this, invar)) {
1209 // Range check for counted loops
1210 const Node* cmp = bol->in(1)->as_Cmp();
1211 Node* idx = cmp->in(1);
1212 assert(!invar.is_invariant(idx), "index is variant");
1213 Node* rng = cmp->in(2);
1214 assert(rng->Opcode() == Op_LoadRange || iff->is_RangeCheck() || _igvn.type(rng)->is_int()->_lo >= 0, "must be");
1215 assert(invar.is_invariant(rng), "range must be invariant");
1216 int scale = 1;
1217 Node* offset = zero;
1218 bool ok = is_scaled_iv_plus_offset(idx, cl->phi(), &scale, &offset);
1219 assert(ok, "must be index expression");
1220
1221 Node* init = cl->init_trip();
1222 // Limit is not exact.
1223 // Calculate exact limit here.
1224 // Note, counted loop's test is '<' or '>'.
1225 Node* limit = exact_limit(loop);
1226 int stride = cl->stride()->get_int();
1227
1228 // Build if's for the upper and lower bound tests. The
1229 // lower_bound test will dominate the upper bound test and all
1230 // cloned or created nodes will use the lower bound test as
1231 // their declared control.
1232
1233 // Perform cloning to keep Invariance state correct since the
1234 // late schedule will place invariant things in the loop.
1235 Node *ctrl = predicate_proj->in(0)->as_If()->in(0);
1236 rng = invar.clone(rng, ctrl);
1237 if (offset && offset != zero) {
1238 assert(invar.is_invariant(offset), "offset must be loop invariant");
1239 offset = invar.clone(offset, ctrl);
1240 }
1241 // If predicate expressions may overflow in the integer range, longs are used.
1242 bool overflow = false;
1243
1244 // Test the lower bound
1245 BoolNode* lower_bound_bol = rc_predicate(loop, ctrl, scale, offset, init, limit, stride, rng, false, overflow);
1246 // Negate test if necessary
1247 bool negated = false;
1248 if (proj->_con != predicate_proj->_con) {
1249 lower_bound_bol = new BoolNode(lower_bound_bol->in(1), lower_bound_bol->_test.negate());
1250 register_new_node(lower_bound_bol, ctrl);
1251 negated = true;
1252 }
1253 ProjNode* lower_bound_proj = create_new_if_for_predicate(predicate_proj, NULL, reason, overflow ? Op_If : iff->Opcode());
1254 IfNode* lower_bound_iff = lower_bound_proj->in(0)->as_If();
1255 _igvn.hash_delete(lower_bound_iff);
1256 lower_bound_iff->set_req(1, lower_bound_bol);
1257 if (TraceLoopPredicate) tty->print_cr("lower bound check if: %s %d ", negated ? " negated" : "", lower_bound_iff->_idx);
1258
1259 // Test the upper bound
1260 BoolNode* upper_bound_bol = rc_predicate(loop, lower_bound_proj, scale, offset, init, limit, stride, rng, true, overflow);
1261 negated = false;
1262 if (proj->_con != predicate_proj->_con) {
1263 upper_bound_bol = new BoolNode(upper_bound_bol->in(1), upper_bound_bol->_test.negate());
1264 register_new_node(upper_bound_bol, ctrl);
1265 negated = true;
1266 }
1267 ProjNode* upper_bound_proj = create_new_if_for_predicate(predicate_proj, NULL, reason, overflow ? Op_If : iff->Opcode());
1268 assert(upper_bound_proj->in(0)->as_If()->in(0) == lower_bound_proj, "should dominate");
1269 IfNode* upper_bound_iff = upper_bound_proj->in(0)->as_If();
1270 _igvn.hash_delete(upper_bound_iff);
1271 upper_bound_iff->set_req(1, upper_bound_bol);
1272 if (TraceLoopPredicate) tty->print_cr("upper bound check if: %s %d ", negated ? " negated" : "", lower_bound_iff->_idx);
1273
1274 // Fall through into rest of the clean up code which will move
1275 // any dependent nodes onto the upper bound test.
1276 new_predicate_proj = upper_bound_proj;
1277
1278 if (iff->is_RangeCheck()) {
1279 new_predicate_proj = insert_skeleton_predicate(iff, loop, proj, predicate_proj, upper_bound_proj, scale, offset, init, limit, stride, rng, overflow, reason);
1280 }
1281
1282 #ifndef PRODUCT
1283 if (TraceLoopOpts && !TraceLoopPredicate) {
1284 tty->print("Predicate RC ");
1285 loop->dump_head();
1286 }
1287 #endif
1288 } else {
1289 // Loop variant check (for example, range check in non-counted loop)
1290 // with uncommon trap.
1291 return false;
1292 }
1293 assert(new_predicate_proj != NULL, "sanity");
1294 // Success - attach condition (new_predicate_bol) to predicate if
1295 invar.map_ctrl(proj, new_predicate_proj); // so that invariance test can be appropriate
1296
1297 // Eliminate the old If in the loop body
1298 dominated_by( new_predicate_proj, iff, proj->_con != new_predicate_proj->_con );
1299
1300 C->set_major_progress();
1301 return true;
1302 }
1303
1304
1305 // After pre/main/post loops are created, we'll put a copy of some
1306 // range checks between the pre and main loop to validate the value
1307 // of the main loop induction variable. Make a copy of the predicates
1308 // here with an opaque node as a place holder for the value (will be
1309 // updated by PhaseIdealLoop::clone_skeleton_predicate()).
insert_skeleton_predicate(IfNode * iff,IdealLoopTree * loop,ProjNode * proj,ProjNode * predicate_proj,ProjNode * upper_bound_proj,int scale,Node * offset,Node * init,Node * limit,jint stride,Node * rng,bool & overflow,Deoptimization::DeoptReason reason)1310 ProjNode* PhaseIdealLoop::insert_skeleton_predicate(IfNode* iff, IdealLoopTree *loop,
1311 ProjNode* proj, ProjNode *predicate_proj,
1312 ProjNode* upper_bound_proj,
1313 int scale, Node* offset,
1314 Node* init, Node* limit, jint stride,
1315 Node* rng, bool &overflow,
1316 Deoptimization::DeoptReason reason) {
1317 assert(proj->_con && predicate_proj->_con, "not a range check?");
1318 Node* opaque_init = new Opaque1Node(C, init);
1319 register_new_node(opaque_init, upper_bound_proj);
1320 BoolNode* bol = rc_predicate(loop, upper_bound_proj, scale, offset, opaque_init, limit, stride, rng, (stride > 0) != (scale > 0), overflow);
1321 Node* opaque_bol = new Opaque4Node(C, bol, _igvn.intcon(1)); // This will go away once loop opts are over
1322 register_new_node(opaque_bol, upper_bound_proj);
1323 ProjNode* new_proj = create_new_if_for_predicate(predicate_proj, NULL, reason, overflow ? Op_If : iff->Opcode());
1324 _igvn.replace_input_of(new_proj->in(0), 1, opaque_bol);
1325 assert(opaque_init->outcnt() > 0, "should be used");
1326 return new_proj;
1327 }
1328
1329 //------------------------------ loop_predication_impl--------------------------
1330 // Insert loop predicates for null checks and range checks
loop_predication_impl(IdealLoopTree * loop)1331 bool PhaseIdealLoop::loop_predication_impl(IdealLoopTree *loop) {
1332 if (!UseLoopPredicate) return false;
1333
1334 if (!loop->_head->is_Loop()) {
1335 // Could be a simple region when irreducible loops are present.
1336 return false;
1337 }
1338 LoopNode* head = loop->_head->as_Loop();
1339
1340 if (head->unique_ctrl_out()->Opcode() == Op_NeverBranch) {
1341 // do nothing for infinite loops
1342 return false;
1343 }
1344
1345 if (head->is_OuterStripMinedLoop()) {
1346 return false;
1347 }
1348
1349 CountedLoopNode *cl = NULL;
1350 if (head->is_valid_counted_loop()) {
1351 cl = head->as_CountedLoop();
1352 // do nothing for iteration-splitted loops
1353 if (!cl->is_normal_loop()) return false;
1354 // Avoid RCE if Counted loop's test is '!='.
1355 BoolTest::mask bt = cl->loopexit()->test_trip();
1356 if (bt != BoolTest::lt && bt != BoolTest::gt)
1357 cl = NULL;
1358 }
1359
1360 Node* entry = head->skip_strip_mined()->in(LoopNode::EntryControl);
1361 ProjNode *loop_limit_proj = NULL;
1362 ProjNode *predicate_proj = NULL;
1363 ProjNode *profile_predicate_proj = NULL;
1364 // Loop limit check predicate should be near the loop.
1365 loop_limit_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
1366 if (loop_limit_proj != NULL) {
1367 entry = skip_loop_predicates(loop_limit_proj);
1368 }
1369 bool has_profile_predicates = false;
1370 profile_predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_profile_predicate);
1371 if (profile_predicate_proj != NULL) {
1372 Node* n = skip_loop_predicates(entry);
1373 // Check if predicates were already added to the profile predicate
1374 // block
1375 if (n != entry->in(0)->in(0) || n->outcnt() != 1) {
1376 has_profile_predicates = true;
1377 }
1378 entry = n;
1379 }
1380 predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
1381
1382 float loop_trip_cnt = -1;
1383 bool follow_branches = loop_predication_should_follow_branches(loop, profile_predicate_proj, loop_trip_cnt);
1384 assert(!follow_branches || loop_trip_cnt >= 0, "negative trip count?");
1385
1386 if (predicate_proj == NULL && !follow_branches) {
1387 #ifndef PRODUCT
1388 if (TraceLoopPredicate) {
1389 tty->print("missing predicate:");
1390 loop->dump_head();
1391 head->dump(1);
1392 }
1393 #endif
1394 return false;
1395 }
1396 ConNode* zero = _igvn.intcon(0);
1397 set_ctrl(zero, C->root());
1398
1399 ResourceArea *area = Thread::current()->resource_area();
1400 Invariance invar(area, loop);
1401
1402 // Create list of if-projs such that a newer proj dominates all older
1403 // projs in the list, and they all dominate loop->tail()
1404 Node_List if_proj_list(area);
1405 Node_List regions(area);
1406 Node *current_proj = loop->tail(); //start from tail
1407
1408
1409 Node_List controls(area);
1410 while (current_proj != head) {
1411 if (loop == get_loop(current_proj) && // still in the loop ?
1412 current_proj->is_Proj() && // is a projection ?
1413 (current_proj->in(0)->Opcode() == Op_If ||
1414 current_proj->in(0)->Opcode() == Op_RangeCheck)) { // is a if projection ?
1415 if_proj_list.push(current_proj);
1416 }
1417 if (follow_branches &&
1418 current_proj->Opcode() == Op_Region &&
1419 loop == get_loop(current_proj)) {
1420 regions.push(current_proj);
1421 }
1422 current_proj = idom(current_proj);
1423 }
1424
1425 bool hoisted = false; // true if at least one proj is promoted
1426
1427 if (!has_profile_predicates) {
1428 while (if_proj_list.size() > 0) {
1429 Node* n = if_proj_list.pop();
1430
1431 ProjNode* proj = n->as_Proj();
1432 IfNode* iff = proj->in(0)->as_If();
1433
1434 CallStaticJavaNode* call = proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
1435 if (call == NULL) {
1436 if (loop->is_loop_exit(iff)) {
1437 // stop processing the remaining projs in the list because the execution of them
1438 // depends on the condition of "iff" (iff->in(1)).
1439 break;
1440 } else {
1441 // Both arms are inside the loop. There are two cases:
1442 // (1) there is one backward branch. In this case, any remaining proj
1443 // in the if_proj list post-dominates "iff". So, the condition of "iff"
1444 // does not determine the execution the remining projs directly, and we
1445 // can safely continue.
1446 // (2) both arms are forwarded, i.e. a diamond shape. In this case, "proj"
1447 // does not dominate loop->tail(), so it can not be in the if_proj list.
1448 continue;
1449 }
1450 }
1451 Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(call->uncommon_trap_request());
1452 if (reason == Deoptimization::Reason_predicate) {
1453 break;
1454 }
1455
1456 if (predicate_proj != NULL) {
1457 hoisted = loop_predication_impl_helper(loop, proj, predicate_proj, cl, zero, invar, Deoptimization::Reason_predicate) | hoisted;
1458 }
1459 } // end while
1460 }
1461
1462 if (follow_branches) {
1463 PathFrequency pf(loop->_head, this);
1464
1465 // Some projections were skipped by regular predicates because of
1466 // an early loop exit. Try them with profile data.
1467 while (if_proj_list.size() > 0) {
1468 Node* proj = if_proj_list.pop();
1469 float f = pf.to(proj);
1470 if (proj->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none) &&
1471 f * loop_trip_cnt >= 1) {
1472 hoisted = loop_predication_impl_helper(loop, proj->as_Proj(), profile_predicate_proj, cl, zero, invar, Deoptimization::Reason_profile_predicate) | hoisted;
1473 }
1474 }
1475
1476 // And look into all branches
1477 Node_Stack stack(0);
1478 VectorSet seen(Thread::current()->resource_area());
1479 Node_List if_proj_list_freq(area);
1480 while (regions.size() > 0) {
1481 Node* c = regions.pop();
1482 loop_predication_follow_branches(c, loop, loop_trip_cnt, pf, stack, seen, if_proj_list_freq);
1483 }
1484
1485 for (uint i = 0; i < if_proj_list_freq.size(); i++) {
1486 ProjNode* proj = if_proj_list_freq.at(i)->as_Proj();
1487 hoisted = loop_predication_impl_helper(loop, proj, profile_predicate_proj, cl, zero, invar, Deoptimization::Reason_profile_predicate) | hoisted;
1488 }
1489 }
1490
1491 #ifndef PRODUCT
1492 // report that the loop predication has been actually performed
1493 // for this loop
1494 if (TraceLoopPredicate && hoisted) {
1495 tty->print("Loop Predication Performed:");
1496 loop->dump_head();
1497 }
1498 #endif
1499
1500 head->verify_strip_mined(1);
1501
1502 return hoisted;
1503 }
1504
1505 //------------------------------loop_predication--------------------------------
1506 // driver routine for loop predication optimization
loop_predication(PhaseIdealLoop * phase)1507 bool IdealLoopTree::loop_predication( PhaseIdealLoop *phase) {
1508 bool hoisted = false;
1509 // Recursively promote predicates
1510 if (_child) {
1511 hoisted = _child->loop_predication( phase);
1512 }
1513
1514 // self
1515 if (!_irreducible && !tail()->is_top()) {
1516 hoisted |= phase->loop_predication_impl(this);
1517 }
1518
1519 if (_next) { //sibling
1520 hoisted |= _next->loop_predication( phase);
1521 }
1522
1523 return hoisted;
1524 }
1525