1 /*
2 * Copyright (c) 2000, 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.
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23 */
24
25 #include "precompiled.hpp"
26 #include "compiler/compileLog.hpp"
27 #include "memory/allocation.inline.hpp"
28 #include "opto/addnode.hpp"
29 #include "opto/callnode.hpp"
30 #include "opto/castnode.hpp"
31 #include "opto/connode.hpp"
32 #include "opto/convertnode.hpp"
33 #include "opto/divnode.hpp"
34 #include "opto/loopnode.hpp"
35 #include "opto/mulnode.hpp"
36 #include "opto/movenode.hpp"
37 #include "opto/opaquenode.hpp"
38 #include "opto/rootnode.hpp"
39 #include "opto/runtime.hpp"
40 #include "opto/subnode.hpp"
41 #include "opto/superword.hpp"
42 #include "opto/vectornode.hpp"
43
44 //------------------------------is_loop_exit-----------------------------------
45 // Given an IfNode, return the loop-exiting projection or NULL if both
46 // arms remain in the loop.
47 Node *IdealLoopTree::is_loop_exit(Node *iff) const {
48 if( iff->outcnt() != 2 ) return NULL; // Ignore partially dead tests
49 PhaseIdealLoop *phase = _phase;
50 // Test is an IfNode, has 2 projections. If BOTH are in the loop
51 // we need loop unswitching instead of peeling.
52 if( !is_member(phase->get_loop( iff->raw_out(0) )) )
53 return iff->raw_out(0);
54 if( !is_member(phase->get_loop( iff->raw_out(1) )) )
55 return iff->raw_out(1);
56 return NULL;
57 }
58
59
60 //=============================================================================
61
62
63 //------------------------------record_for_igvn----------------------------
64 // Put loop body on igvn work list
65 void IdealLoopTree::record_for_igvn() {
66 for( uint i = 0; i < _body.size(); i++ ) {
67 Node *n = _body.at(i);
68 _phase->_igvn._worklist.push(n);
69 }
70 // put body of outer strip mined loop on igvn work list as well
71 if (_head->is_CountedLoop() && _head->as_Loop()->is_strip_mined()) {
72 CountedLoopNode* l = _head->as_CountedLoop();
73 Node* outer_loop = l->outer_loop();
74 assert(outer_loop != NULL, "missing piece of strip mined loop");
75 _phase->_igvn._worklist.push(outer_loop);
76 Node* outer_loop_tail = l->outer_loop_tail();
77 assert(outer_loop_tail != NULL, "missing piece of strip mined loop");
78 _phase->_igvn._worklist.push(outer_loop_tail);
79 Node* outer_loop_end = l->outer_loop_end();
80 assert(outer_loop_end != NULL, "missing piece of strip mined loop");
81 _phase->_igvn._worklist.push(outer_loop_end);
82 Node* outer_safepoint = l->outer_safepoint();
83 assert(outer_safepoint != NULL, "missing piece of strip mined loop");
84 _phase->_igvn._worklist.push(outer_safepoint);
85 Node* cle_out = _head->as_CountedLoop()->loopexit()->proj_out(false);
86 assert(cle_out != NULL, "missing piece of strip mined loop");
87 _phase->_igvn._worklist.push(cle_out);
88 }
89 }
90
91 //------------------------------compute_exact_trip_count-----------------------
92 // Compute loop trip count if possible. Do not recalculate trip count for
93 // split loops (pre-main-post) which have their limits and inits behind Opaque node.
94 void IdealLoopTree::compute_trip_count(PhaseIdealLoop* phase) {
95 if (!_head->as_Loop()->is_valid_counted_loop()) {
96 return;
97 }
98 CountedLoopNode* cl = _head->as_CountedLoop();
99 // Trip count may become nonexact for iteration split loops since
100 // RCE modifies limits. Note, _trip_count value is not reset since
101 // it is used to limit unrolling of main loop.
102 cl->set_nonexact_trip_count();
103
104 // Loop's test should be part of loop.
105 if (!phase->is_member(this, phase->get_ctrl(cl->loopexit()->in(CountedLoopEndNode::TestValue))))
106 return; // Infinite loop
107
108 #ifdef ASSERT
109 BoolTest::mask bt = cl->loopexit()->test_trip();
110 assert(bt == BoolTest::lt || bt == BoolTest::gt ||
111 bt == BoolTest::ne, "canonical test is expected");
112 #endif
113
114 Node* init_n = cl->init_trip();
115 Node* limit_n = cl->limit();
116 if (init_n != NULL && limit_n != NULL) {
117 // Use longs to avoid integer overflow.
118 int stride_con = cl->stride_con();
119 const TypeInt* init_type = phase->_igvn.type(init_n)->is_int();
120 const TypeInt* limit_type = phase->_igvn.type(limit_n)->is_int();
121 jlong init_con = (stride_con > 0) ? init_type->_lo : init_type->_hi;
122 jlong limit_con = (stride_con > 0) ? limit_type->_hi : limit_type->_lo;
123 int stride_m = stride_con - (stride_con > 0 ? 1 : -1);
124 jlong trip_count = (limit_con - init_con + stride_m)/stride_con;
125 if (trip_count > 0 && (julong)trip_count < (julong)max_juint) {
126 if (init_n->is_Con() && limit_n->is_Con()) {
127 // Set exact trip count.
128 cl->set_exact_trip_count((uint)trip_count);
129 } else if (cl->unrolled_count() == 1) {
130 // Set maximum trip count before unrolling.
131 cl->set_trip_count((uint)trip_count);
132 }
133 }
134 }
135 }
136
137 //------------------------------compute_profile_trip_cnt----------------------------
138 // Compute loop trip count from profile data as
139 // (backedge_count + loop_exit_count) / loop_exit_count
140
141 float IdealLoopTree::compute_profile_trip_cnt_helper(Node* n) {
142 if (n->is_If()) {
143 IfNode *iff = n->as_If();
144 if (iff->_fcnt != COUNT_UNKNOWN && iff->_prob != PROB_UNKNOWN) {
145 Node *exit = is_loop_exit(iff);
146 if (exit) {
147 float exit_prob = iff->_prob;
148 if (exit->Opcode() == Op_IfFalse) exit_prob = 1.0 - exit_prob;
149 if (exit_prob > PROB_MIN) {
150 float exit_cnt = iff->_fcnt * exit_prob;
151 return exit_cnt;
152 }
153 }
154 }
155 }
156 if (n->is_Jump()) {
157 JumpNode *jmp = n->as_Jump();
158 if (jmp->_fcnt != COUNT_UNKNOWN) {
159 float* probs = jmp->_probs;
160 float exit_prob = 0;
161 PhaseIdealLoop *phase = _phase;
162 for (DUIterator_Fast imax, i = jmp->fast_outs(imax); i < imax; i++) {
163 JumpProjNode* u = jmp->fast_out(i)->as_JumpProj();
164 if (!is_member(_phase->get_loop(u))) {
165 exit_prob += probs[u->_con];
166 }
167 }
168 return exit_prob * jmp->_fcnt;
169 }
170 }
171 return 0;
172 }
173
174 void IdealLoopTree::compute_profile_trip_cnt(PhaseIdealLoop *phase) {
175 if (!_head->is_Loop()) {
176 return;
177 }
178 LoopNode* head = _head->as_Loop();
179 if (head->profile_trip_cnt() != COUNT_UNKNOWN) {
180 return; // Already computed
181 }
182 float trip_cnt = (float)max_jint; // default is big
183
184 Node* back = head->in(LoopNode::LoopBackControl);
185 while (back != head) {
186 if ((back->Opcode() == Op_IfTrue || back->Opcode() == Op_IfFalse) &&
187 back->in(0) &&
188 back->in(0)->is_If() &&
189 back->in(0)->as_If()->_fcnt != COUNT_UNKNOWN &&
190 back->in(0)->as_If()->_prob != PROB_UNKNOWN &&
191 (back->Opcode() == Op_IfTrue ? 1-back->in(0)->as_If()->_prob : back->in(0)->as_If()->_prob) > PROB_MIN) {
192 break;
193 }
194 back = phase->idom(back);
195 }
196 if (back != head) {
197 assert((back->Opcode() == Op_IfTrue || back->Opcode() == Op_IfFalse) &&
198 back->in(0), "if-projection exists");
199 IfNode* back_if = back->in(0)->as_If();
200 float loop_back_cnt = back_if->_fcnt * (back->Opcode() == Op_IfTrue ? back_if->_prob : (1 - back_if->_prob));
201
202 // Now compute a loop exit count
203 float loop_exit_cnt = 0.0f;
204 if (_child == NULL) {
205 for( uint i = 0; i < _body.size(); i++ ) {
206 Node *n = _body[i];
207 loop_exit_cnt += compute_profile_trip_cnt_helper(n);
208 }
209 } else {
210 ResourceMark rm;
211 Unique_Node_List wq;
212 wq.push(back);
213 for (uint i = 0; i < wq.size(); i++) {
214 Node *n = wq.at(i);
215 assert(n->is_CFG(), "only control nodes");
216 if (n != head) {
217 if (n->is_Region()) {
218 for (uint j = 1; j < n->req(); j++) {
219 wq.push(n->in(j));
220 }
221 } else {
222 loop_exit_cnt += compute_profile_trip_cnt_helper(n);
223 wq.push(n->in(0));
224 }
225 }
226 }
227
228 }
229 if (loop_exit_cnt > 0.0f) {
230 trip_cnt = (loop_back_cnt + loop_exit_cnt) / loop_exit_cnt;
231 } else {
232 // No exit count so use
233 trip_cnt = loop_back_cnt;
234 }
235 } else {
236 head->mark_profile_trip_failed();
237 }
238 #ifndef PRODUCT
239 if (TraceProfileTripCount) {
240 tty->print_cr("compute_profile_trip_cnt lp: %d cnt: %f\n", head->_idx, trip_cnt);
241 }
242 #endif
243 head->set_profile_trip_cnt(trip_cnt);
244 }
245
246 //---------------------is_invariant_addition-----------------------------
247 // Return nonzero index of invariant operand for an Add or Sub
248 // of (nonconstant) invariant and variant values. Helper for reassociate_invariants.
249 int IdealLoopTree::is_invariant_addition(Node* n, PhaseIdealLoop *phase) {
250 int op = n->Opcode();
251 if (op == Op_AddI || op == Op_SubI) {
252 bool in1_invar = this->is_invariant(n->in(1));
253 bool in2_invar = this->is_invariant(n->in(2));
254 if (in1_invar && !in2_invar) return 1;
255 if (!in1_invar && in2_invar) return 2;
256 }
257 return 0;
258 }
259
260 //---------------------reassociate_add_sub-----------------------------
261 // Reassociate invariant add and subtract expressions:
262 //
263 // inv1 + (x + inv2) => ( inv1 + inv2) + x
264 // (x + inv2) + inv1 => ( inv1 + inv2) + x
265 // inv1 + (x - inv2) => ( inv1 - inv2) + x
266 // inv1 - (inv2 - x) => ( inv1 - inv2) + x
267 // (x + inv2) - inv1 => (-inv1 + inv2) + x
268 // (x - inv2) + inv1 => ( inv1 - inv2) + x
269 // (x - inv2) - inv1 => (-inv1 - inv2) + x
270 // inv1 + (inv2 - x) => ( inv1 + inv2) - x
271 // inv1 - (x - inv2) => ( inv1 + inv2) - x
272 // (inv2 - x) + inv1 => ( inv1 + inv2) - x
273 // (inv2 - x) - inv1 => (-inv1 + inv2) - x
274 // inv1 - (x + inv2) => ( inv1 - inv2) - x
275 //
276 Node* IdealLoopTree::reassociate_add_sub(Node* n1, PhaseIdealLoop *phase) {
277 if ((!n1->is_Add() && !n1->is_Sub()) || n1->outcnt() == 0) return NULL;
278 if (is_invariant(n1)) return NULL;
279 int inv1_idx = is_invariant_addition(n1, phase);
280 if (!inv1_idx) return NULL;
281 // Don't mess with add of constant (igvn moves them to expression tree root.)
282 if (n1->is_Add() && n1->in(2)->is_Con()) return NULL;
283 Node* inv1 = n1->in(inv1_idx);
284 Node* n2 = n1->in(3 - inv1_idx);
285 int inv2_idx = is_invariant_addition(n2, phase);
286 if (!inv2_idx) return NULL;
287 Node* x = n2->in(3 - inv2_idx);
288 Node* inv2 = n2->in(inv2_idx);
289
290 bool neg_x = n2->is_Sub() && inv2_idx == 1;
291 bool neg_inv2 = n2->is_Sub() && inv2_idx == 2;
292 bool neg_inv1 = n1->is_Sub() && inv1_idx == 2;
293 if (n1->is_Sub() && inv1_idx == 1) {
294 neg_x = !neg_x;
295 neg_inv2 = !neg_inv2;
296 }
297 Node* inv1_c = phase->get_ctrl(inv1);
298 Node* inv2_c = phase->get_ctrl(inv2);
299 Node* n_inv1;
300 if (neg_inv1) {
301 Node *zero = phase->_igvn.intcon(0);
302 phase->set_ctrl(zero, phase->C->root());
303 n_inv1 = new SubINode(zero, inv1);
304 phase->register_new_node(n_inv1, inv1_c);
305 } else {
306 n_inv1 = inv1;
307 }
308 Node* inv;
309 if (neg_inv2) {
310 inv = new SubINode(n_inv1, inv2);
311 } else {
312 inv = new AddINode(n_inv1, inv2);
313 }
314 phase->register_new_node(inv, phase->get_early_ctrl(inv));
315
316 Node* addx;
317 if (neg_x) {
318 addx = new SubINode(inv, x);
319 } else {
320 addx = new AddINode(x, inv);
321 }
322 phase->register_new_node(addx, phase->get_ctrl(x));
323 phase->_igvn.replace_node(n1, addx);
324 assert(phase->get_loop(phase->get_ctrl(n1)) == this, "");
325 _body.yank(n1);
326 return addx;
327 }
328
329 //---------------------reassociate_invariants-----------------------------
330 // Reassociate invariant expressions:
331 void IdealLoopTree::reassociate_invariants(PhaseIdealLoop *phase) {
332 for (int i = _body.size() - 1; i >= 0; i--) {
333 Node *n = _body.at(i);
334 for (int j = 0; j < 5; j++) {
335 Node* nn = reassociate_add_sub(n, phase);
336 if (nn == NULL) break;
337 n = nn; // again
338 };
339 }
340 }
341
342 //------------------------------policy_peeling---------------------------------
343 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can
344 // make some loop-invariant test (usually a null-check) happen before the loop.
345 bool IdealLoopTree::policy_peeling( PhaseIdealLoop *phase ) const {
346 Node *test = ((IdealLoopTree*)this)->tail();
347 int body_size = ((IdealLoopTree*)this)->_body.size();
348 // Peeling does loop cloning which can result in O(N^2) node construction
349 if( body_size > 255 /* Prevent overflow for large body_size */
350 || (body_size * body_size + phase->C->live_nodes()) > phase->C->max_node_limit() ) {
351 return false; // too large to safely clone
352 }
353
354 // check for vectorized loops, any peeling done was already applied
355 if (_head->is_CountedLoop() && _head->as_CountedLoop()->do_unroll_only()) return false;
356
357 if (_head->is_CountedLoop() && _head->as_CountedLoop()->trip_count() == 1) {
358 return false;
359 }
360
361 while( test != _head ) { // Scan till run off top of loop
362 if( test->is_If() ) { // Test?
363 Node *ctrl = phase->get_ctrl(test->in(1));
364 if (ctrl->is_top())
365 return false; // Found dead test on live IF? No peeling!
366 // Standard IF only has one input value to check for loop invariance
367 assert(test->Opcode() == Op_If || test->Opcode() == Op_CountedLoopEnd || test->Opcode() == Op_RangeCheck, "Check this code when new subtype is added");
368 // Condition is not a member of this loop?
369 if( !is_member(phase->get_loop(ctrl)) &&
370 is_loop_exit(test) )
371 return true; // Found reason to peel!
372 }
373 // Walk up dominators to loop _head looking for test which is
374 // executed on every path thru loop.
375 test = phase->idom(test);
376 }
377 return false;
378 }
379
380 //------------------------------peeled_dom_test_elim---------------------------
381 // If we got the effect of peeling, either by actually peeling or by making
382 // a pre-loop which must execute at least once, we can remove all
383 // loop-invariant dominated tests in the main body.
384 void PhaseIdealLoop::peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new ) {
385 bool progress = true;
386 while( progress ) {
387 progress = false; // Reset for next iteration
388 Node *prev = loop->_head->in(LoopNode::LoopBackControl);//loop->tail();
389 Node *test = prev->in(0);
390 while( test != loop->_head ) { // Scan till run off top of loop
391
392 int p_op = prev->Opcode();
393 if( (p_op == Op_IfFalse || p_op == Op_IfTrue) &&
394 test->is_If() && // Test?
395 !test->in(1)->is_Con() && // And not already obvious?
396 // Condition is not a member of this loop?
397 !loop->is_member(get_loop(get_ctrl(test->in(1))))){
398 // Walk loop body looking for instances of this test
399 for( uint i = 0; i < loop->_body.size(); i++ ) {
400 Node *n = loop->_body.at(i);
401 if( n->is_If() && n->in(1) == test->in(1) /*&& n != loop->tail()->in(0)*/ ) {
402 // IfNode was dominated by version in peeled loop body
403 progress = true;
404 dominated_by( old_new[prev->_idx], n );
405 }
406 }
407 }
408 prev = test;
409 test = idom(test);
410 } // End of scan tests in loop
411
412 } // End of while( progress )
413 }
414
415 //------------------------------do_peeling-------------------------------------
416 // Peel the first iteration of the given loop.
417 // Step 1: Clone the loop body. The clone becomes the peeled iteration.
418 // The pre-loop illegally has 2 control users (old & new loops).
419 // Step 2: Make the old-loop fall-in edges point to the peeled iteration.
420 // Do this by making the old-loop fall-in edges act as if they came
421 // around the loopback from the prior iteration (follow the old-loop
422 // backedges) and then map to the new peeled iteration. This leaves
423 // the pre-loop with only 1 user (the new peeled iteration), but the
424 // peeled-loop backedge has 2 users.
425 // Step 3: Cut the backedge on the clone (so its not a loop) and remove the
426 // extra backedge user.
427 //
428 // orig
429 //
430 // stmt1
431 // |
432 // v
433 // loop predicate
434 // |
435 // v
436 // loop<----+
437 // | |
438 // stmt2 |
439 // | |
440 // v |
441 // if ^
442 // / \ |
443 // / \ |
444 // v v |
445 // false true |
446 // / \ |
447 // / ----+
448 // |
449 // v
450 // exit
451 //
452 //
453 // after clone loop
454 //
455 // stmt1
456 // |
457 // v
458 // loop predicate
459 // / \
460 // clone / \ orig
461 // / \
462 // / \
463 // v v
464 // +---->loop clone loop<----+
465 // | | | |
466 // | stmt2 clone stmt2 |
467 // | | | |
468 // | v v |
469 // ^ if clone If ^
470 // | / \ / \ |
471 // | / \ / \ |
472 // | v v v v |
473 // | true false false true |
474 // | / \ / \ |
475 // +---- \ / ----+
476 // \ /
477 // 1v v2
478 // region
479 // |
480 // v
481 // exit
482 //
483 //
484 // after peel and predicate move
485 //
486 // stmt1
487 // /
488 // /
489 // clone / orig
490 // /
491 // / +----------+
492 // / | |
493 // / loop predicate |
494 // / | |
495 // v v |
496 // TOP-->loop clone loop<----+ |
497 // | | | |
498 // stmt2 clone stmt2 | |
499 // | | | ^
500 // v v | |
501 // if clone If ^ |
502 // / \ / \ | |
503 // / \ / \ | |
504 // v v v v | |
505 // true false false true | |
506 // | \ / \ | |
507 // | \ / ----+ ^
508 // | \ / |
509 // | 1v v2 |
510 // v region |
511 // | | |
512 // | v |
513 // | exit |
514 // | |
515 // +--------------->-----------------+
516 //
517 //
518 // final graph
519 //
520 // stmt1
521 // |
522 // v
523 // stmt2 clone
524 // |
525 // v
526 // if clone
527 // / |
528 // / |
529 // v v
530 // false true
531 // | |
532 // | v
533 // | loop predicate
534 // | |
535 // | v
536 // | loop<----+
537 // | | |
538 // | stmt2 |
539 // | | |
540 // | v |
541 // v if ^
542 // | / \ |
543 // | / \ |
544 // | v v |
545 // | false true |
546 // | | \ |
547 // v v --+
548 // region
549 // |
550 // v
551 // exit
552 //
553 void PhaseIdealLoop::do_peeling( IdealLoopTree *loop, Node_List &old_new ) {
554
555 C->set_major_progress();
556 // Peeling a 'main' loop in a pre/main/post situation obfuscates the
557 // 'pre' loop from the main and the 'pre' can no longer have its
558 // iterations adjusted. Therefore, we need to declare this loop as
559 // no longer a 'main' loop; it will need new pre and post loops before
560 // we can do further RCE.
561 #ifndef PRODUCT
562 if (TraceLoopOpts) {
563 tty->print("Peel ");
564 loop->dump_head();
565 }
566 #endif
567 LoopNode* head = loop->_head->as_Loop();
568 bool counted_loop = head->is_CountedLoop();
569 if (counted_loop) {
570 CountedLoopNode *cl = head->as_CountedLoop();
571 assert(cl->trip_count() > 0, "peeling a fully unrolled loop");
572 cl->set_trip_count(cl->trip_count() - 1);
573 if (cl->is_main_loop()) {
574 cl->set_normal_loop();
575 #ifndef PRODUCT
576 if (PrintOpto && VerifyLoopOptimizations) {
577 tty->print("Peeling a 'main' loop; resetting to 'normal' ");
578 loop->dump_head();
579 }
580 #endif
581 }
582 }
583 Node* entry = head->in(LoopNode::EntryControl);
584
585 // Step 1: Clone the loop body. The clone becomes the peeled iteration.
586 // The pre-loop illegally has 2 control users (old & new loops).
587 clone_loop(loop, old_new, dom_depth(head->skip_strip_mined()), ControlAroundStripMined);
588
589 // Step 2: Make the old-loop fall-in edges point to the peeled iteration.
590 // Do this by making the old-loop fall-in edges act as if they came
591 // around the loopback from the prior iteration (follow the old-loop
592 // backedges) and then map to the new peeled iteration. This leaves
593 // the pre-loop with only 1 user (the new peeled iteration), but the
594 // peeled-loop backedge has 2 users.
595 Node* new_entry = old_new[head->in(LoopNode::LoopBackControl)->_idx];
596 _igvn.hash_delete(head->skip_strip_mined());
597 head->skip_strip_mined()->set_req(LoopNode::EntryControl, new_entry);
598 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
599 Node* old = head->fast_out(j);
600 if (old->in(0) == loop->_head && old->req() == 3 && old->is_Phi()) {
601 Node* new_exit_value = old_new[old->in(LoopNode::LoopBackControl)->_idx];
602 if (!new_exit_value ) // Backedge value is ALSO loop invariant?
603 // Then loop body backedge value remains the same.
604 new_exit_value = old->in(LoopNode::LoopBackControl);
605 _igvn.hash_delete(old);
606 old->set_req(LoopNode::EntryControl, new_exit_value);
607 }
608 }
609
610
611 // Step 3: Cut the backedge on the clone (so its not a loop) and remove the
612 // extra backedge user.
613 Node* new_head = old_new[head->_idx];
614 _igvn.hash_delete(new_head);
615 new_head->set_req(LoopNode::LoopBackControl, C->top());
616 for (DUIterator_Fast j2max, j2 = new_head->fast_outs(j2max); j2 < j2max; j2++) {
617 Node* use = new_head->fast_out(j2);
618 if (use->in(0) == new_head && use->req() == 3 && use->is_Phi()) {
619 _igvn.hash_delete(use);
620 use->set_req(LoopNode::LoopBackControl, C->top());
621 }
622 }
623
624
625 // Step 4: Correct dom-depth info. Set to loop-head depth.
626 int dd = dom_depth(head->skip_strip_mined());
627 set_idom(head->skip_strip_mined(), head->skip_strip_mined()->in(LoopNode::EntryControl), dd);
628 for (uint j3 = 0; j3 < loop->_body.size(); j3++) {
629 Node *old = loop->_body.at(j3);
630 Node *nnn = old_new[old->_idx];
631 if (!has_ctrl(nnn))
632 set_idom(nnn, idom(nnn), dd-1);
633 }
634
635 // Now force out all loop-invariant dominating tests. The optimizer
636 // finds some, but we _know_ they are all useless.
637 peeled_dom_test_elim(loop,old_new);
638
639 loop->record_for_igvn();
640 }
641
642 #define EMPTY_LOOP_SIZE 7 // number of nodes in an empty loop
643
644 //------------------------------policy_maximally_unroll------------------------
645 // Calculate exact loop trip count and return true if loop can be maximally
646 // unrolled.
647 bool IdealLoopTree::policy_maximally_unroll( PhaseIdealLoop *phase ) const {
648 CountedLoopNode *cl = _head->as_CountedLoop();
649 assert(cl->is_normal_loop(), "");
650 if (!cl->is_valid_counted_loop())
651 return false; // Malformed counted loop
652
653 if (!cl->has_exact_trip_count()) {
654 // Trip count is not exact.
655 return false;
656 }
657
658 uint trip_count = cl->trip_count();
659 // Note, max_juint is used to indicate unknown trip count.
660 assert(trip_count > 1, "one iteration loop should be optimized out already");
661 assert(trip_count < max_juint, "exact trip_count should be less than max_uint.");
662
663 // Real policy: if we maximally unroll, does it get too big?
664 // Allow the unrolled mess to get larger than standard loop
665 // size. After all, it will no longer be a loop.
666 uint body_size = _body.size();
667 uint unroll_limit = (uint)LoopUnrollLimit * 4;
668 assert( (intx)unroll_limit == LoopUnrollLimit * 4, "LoopUnrollLimit must fit in 32bits");
669 if (trip_count > unroll_limit || body_size > unroll_limit) {
670 return false;
671 }
672
673 // Fully unroll a loop with few iterations regardless next
674 // conditions since following loop optimizations will split
675 // such loop anyway (pre-main-post).
676 if (trip_count <= 3)
677 return true;
678
679 // Take into account that after unroll conjoined heads and tails will fold,
680 // otherwise policy_unroll() may allow more unrolling than max unrolling.
681 uint new_body_size = EMPTY_LOOP_SIZE + (body_size - EMPTY_LOOP_SIZE) * trip_count;
682 uint tst_body_size = (new_body_size - EMPTY_LOOP_SIZE) / trip_count + EMPTY_LOOP_SIZE;
683 if (body_size != tst_body_size) // Check for int overflow
684 return false;
685 if (new_body_size > unroll_limit ||
686 // Unrolling can result in a large amount of node construction
687 new_body_size >= phase->C->max_node_limit() - phase->C->live_nodes()) {
688 return false;
689 }
690
691 // Do not unroll a loop with String intrinsics code.
692 // String intrinsics are large and have loops.
693 for (uint k = 0; k < _body.size(); k++) {
694 Node* n = _body.at(k);
695 switch (n->Opcode()) {
696 case Op_StrComp:
697 case Op_StrEquals:
698 case Op_StrIndexOf:
699 case Op_StrIndexOfChar:
700 case Op_EncodeISOArray:
701 case Op_AryEq:
702 case Op_HasNegatives: {
703 return false;
704 }
705 #if INCLUDE_RTM_OPT
706 case Op_FastLock:
707 case Op_FastUnlock: {
708 // Don't unroll RTM locking code because it is large.
709 if (UseRTMLocking) {
710 return false;
711 }
712 }
713 #endif
714 } // switch
715 }
716
717 return true; // Do maximally unroll
718 }
719
720
721 //------------------------------policy_unroll----------------------------------
722 // Return TRUE or FALSE if the loop should be unrolled or not. Unroll if
723 // the loop is a CountedLoop and the body is small enough.
724 bool IdealLoopTree::policy_unroll(PhaseIdealLoop *phase) {
725
726 CountedLoopNode *cl = _head->as_CountedLoop();
727 assert(cl->is_normal_loop() || cl->is_main_loop(), "");
728
729 if (!cl->is_valid_counted_loop())
730 return false; // Malformed counted loop
731
732 // Protect against over-unrolling.
733 // After split at least one iteration will be executed in pre-loop.
734 if (cl->trip_count() <= (uint)(cl->is_normal_loop() ? 2 : 1)) return false;
735
736 _local_loop_unroll_limit = LoopUnrollLimit;
737 _local_loop_unroll_factor = 4;
738 int future_unroll_ct = cl->unrolled_count() * 2;
739 if (!cl->is_vectorized_loop()) {
740 if (future_unroll_ct > LoopMaxUnroll) return false;
741 } else {
742 // obey user constraints on vector mapped loops with additional unrolling applied
743 int unroll_constraint = (cl->slp_max_unroll()) ? cl->slp_max_unroll() : 1;
744 if ((future_unroll_ct / unroll_constraint) > LoopMaxUnroll) return false;
745 }
746
747 // Check for initial stride being a small enough constant
748 if (abs(cl->stride_con()) > (1<<2)*future_unroll_ct) return false;
749
750 // Don't unroll if the next round of unrolling would push us
751 // over the expected trip count of the loop. One is subtracted
752 // from the expected trip count because the pre-loop normally
753 // executes 1 iteration.
754 if (UnrollLimitForProfileCheck > 0 &&
755 cl->profile_trip_cnt() != COUNT_UNKNOWN &&
756 future_unroll_ct > UnrollLimitForProfileCheck &&
757 (float)future_unroll_ct > cl->profile_trip_cnt() - 1.0) {
758 return false;
759 }
760
761 // When unroll count is greater than LoopUnrollMin, don't unroll if:
762 // the residual iterations are more than 10% of the trip count
763 // and rounds of "unroll,optimize" are not making significant progress
764 // Progress defined as current size less than 20% larger than previous size.
765 if (UseSuperWord && cl->node_count_before_unroll() > 0 &&
766 future_unroll_ct > LoopUnrollMin &&
767 (future_unroll_ct - 1) * (100 / LoopPercentProfileLimit) > cl->profile_trip_cnt() &&
768 1.2 * cl->node_count_before_unroll() < (double)_body.size()) {
769 return false;
770 }
771
772 Node *init_n = cl->init_trip();
773 Node *limit_n = cl->limit();
774 int stride_con = cl->stride_con();
775 if (limit_n == NULL) return false; // We will dereference it below.
776
777 // Non-constant bounds.
778 // Protect against over-unrolling when init or/and limit are not constant
779 // (so that trip_count's init value is maxint) but iv range is known.
780 if (init_n == NULL || !init_n->is_Con() || !limit_n->is_Con()) {
781 Node* phi = cl->phi();
782 if (phi != NULL) {
783 assert(phi->is_Phi() && phi->in(0) == _head, "Counted loop should have iv phi.");
784 const TypeInt* iv_type = phase->_igvn.type(phi)->is_int();
785 int next_stride = stride_con * 2; // stride after this unroll
786 if (next_stride > 0) {
787 if (iv_type->_lo + next_stride <= iv_type->_lo || // overflow
788 iv_type->_lo + next_stride > iv_type->_hi) {
789 return false; // over-unrolling
790 }
791 } else if (next_stride < 0) {
792 if (iv_type->_hi + next_stride >= iv_type->_hi || // overflow
793 iv_type->_hi + next_stride < iv_type->_lo) {
794 return false; // over-unrolling
795 }
796 }
797 }
798 }
799
800 // After unroll limit will be adjusted: new_limit = limit-stride.
801 // Bailout if adjustment overflow.
802 const TypeInt* limit_type = phase->_igvn.type(limit_n)->is_int();
803 if ((stride_con > 0 && ((limit_type->_hi - stride_con) >= limit_type->_hi)) ||
804 (stride_con < 0 && ((limit_type->_lo - stride_con) <= limit_type->_lo)))
805 return false; // overflow
806
807 // Adjust body_size to determine if we unroll or not
808 uint body_size = _body.size();
809 // Key test to unroll loop in CRC32 java code
810 int xors_in_loop = 0;
811 // Also count ModL, DivL and MulL which expand mightly
812 for (uint k = 0; k < _body.size(); k++) {
813 Node* n = _body.at(k);
814 switch (n->Opcode()) {
815 case Op_XorI: xors_in_loop++; break; // CRC32 java code
816 case Op_ModL: body_size += 30; break;
817 case Op_DivL: body_size += 30; break;
818 case Op_MulL: body_size += 10; break;
819 case Op_StrComp:
820 case Op_StrEquals:
821 case Op_StrIndexOf:
822 case Op_StrIndexOfChar:
823 case Op_EncodeISOArray:
824 case Op_AryEq:
825 case Op_HasNegatives: {
826 // Do not unroll a loop with String intrinsics code.
827 // String intrinsics are large and have loops.
828 return false;
829 }
830 #if INCLUDE_RTM_OPT
831 case Op_FastLock:
832 case Op_FastUnlock: {
833 // Don't unroll RTM locking code because it is large.
834 if (UseRTMLocking) {
835 return false;
836 }
837 }
838 #endif
839 } // switch
840 }
841
842 if (UseSuperWord) {
843 if (!cl->is_reduction_loop()) {
844 phase->mark_reductions(this);
845 }
846
847 // Only attempt slp analysis when user controls do not prohibit it
848 if (LoopMaxUnroll > _local_loop_unroll_factor) {
849 // Once policy_slp_analysis succeeds, mark the loop with the
850 // maximal unroll factor so that we minimize analysis passes
851 if (future_unroll_ct >= _local_loop_unroll_factor) {
852 policy_unroll_slp_analysis(cl, phase, future_unroll_ct);
853 }
854 }
855 }
856
857 int slp_max_unroll_factor = cl->slp_max_unroll();
858 if ((LoopMaxUnroll < slp_max_unroll_factor) && FLAG_IS_DEFAULT(LoopMaxUnroll) && UseSubwordForMaxVector) {
859 LoopMaxUnroll = slp_max_unroll_factor;
860 }
861 if (cl->has_passed_slp()) {
862 if (slp_max_unroll_factor >= future_unroll_ct) return true;
863 // Normal case: loop too big
864 return false;
865 }
866
867 // Check for being too big
868 if (body_size > (uint)_local_loop_unroll_limit) {
869 if ((cl->is_subword_loop() || xors_in_loop >= 4) && body_size < (uint)LoopUnrollLimit * 4) {
870 return true;
871 }
872 // Normal case: loop too big
873 return false;
874 }
875
876 if (cl->do_unroll_only()) {
877 if (TraceSuperWordLoopUnrollAnalysis) {
878 tty->print_cr("policy_unroll passed vector loop(vlen=%d,factor = %d)\n", slp_max_unroll_factor, future_unroll_ct);
879 }
880 }
881
882 // Unroll once! (Each trip will soon do double iterations)
883 return true;
884 }
885
886 void IdealLoopTree::policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_ct) {
887 // Enable this functionality target by target as needed
888 if (SuperWordLoopUnrollAnalysis) {
889 if (!cl->was_slp_analyzed()) {
890 SuperWord sw(phase);
891 sw.transform_loop(this, false);
892
893 // If the loop is slp canonical analyze it
894 if (sw.early_return() == false) {
895 sw.unrolling_analysis(_local_loop_unroll_factor);
896 }
897 }
898
899 if (cl->has_passed_slp()) {
900 int slp_max_unroll_factor = cl->slp_max_unroll();
901 if (slp_max_unroll_factor >= future_unroll_ct) {
902 int new_limit = cl->node_count_before_unroll() * slp_max_unroll_factor;
903 if (new_limit > LoopUnrollLimit) {
904 if (TraceSuperWordLoopUnrollAnalysis) {
905 tty->print_cr("slp analysis unroll=%d, default limit=%d\n", new_limit, _local_loop_unroll_limit);
906 }
907 _local_loop_unroll_limit = new_limit;
908 }
909 }
910 }
911 }
912 }
913
914 //------------------------------policy_align-----------------------------------
915 // Return TRUE or FALSE if the loop should be cache-line aligned. Gather the
916 // expression that does the alignment. Note that only one array base can be
917 // aligned in a loop (unless the VM guarantees mutual alignment). Note that
918 // if we vectorize short memory ops into longer memory ops, we may want to
919 // increase alignment.
920 bool IdealLoopTree::policy_align( PhaseIdealLoop *phase ) const {
921 return false;
922 }
923
924 //------------------------------policy_range_check-----------------------------
925 // Return TRUE or FALSE if the loop should be range-check-eliminated.
926 // Actually we do iteration-splitting, a more powerful form of RCE.
927 bool IdealLoopTree::policy_range_check( PhaseIdealLoop *phase ) const {
928 if (!RangeCheckElimination) return false;
929
930 CountedLoopNode *cl = _head->as_CountedLoop();
931 // If we unrolled with no intention of doing RCE and we later
932 // changed our minds, we got no pre-loop. Either we need to
933 // make a new pre-loop, or we gotta disallow RCE.
934 if (cl->is_main_no_pre_loop()) return false; // Disallowed for now.
935 Node *trip_counter = cl->phi();
936
937 // check for vectorized loops, some opts are no longer needed
938 if (cl->do_unroll_only()) return false;
939
940 // Check loop body for tests of trip-counter plus loop-invariant vs
941 // loop-invariant.
942 for (uint i = 0; i < _body.size(); i++) {
943 Node *iff = _body[i];
944 if (iff->Opcode() == Op_If ||
945 iff->Opcode() == Op_RangeCheck) { // Test?
946
947 // Comparing trip+off vs limit
948 Node *bol = iff->in(1);
949 if (bol->req() != 2) continue; // dead constant test
950 if (!bol->is_Bool()) {
951 assert(bol->Opcode() == Op_Conv2B, "predicate check only");
952 continue;
953 }
954 if (bol->as_Bool()->_test._test == BoolTest::ne)
955 continue; // not RC
956
957 Node *cmp = bol->in(1);
958 Node *rc_exp = cmp->in(1);
959 Node *limit = cmp->in(2);
960
961 Node *limit_c = phase->get_ctrl(limit);
962 if( limit_c == phase->C->top() )
963 return false; // Found dead test on live IF? No RCE!
964 if( is_member(phase->get_loop(limit_c) ) ) {
965 // Compare might have operands swapped; commute them
966 rc_exp = cmp->in(2);
967 limit = cmp->in(1);
968 limit_c = phase->get_ctrl(limit);
969 if( is_member(phase->get_loop(limit_c) ) )
970 continue; // Both inputs are loop varying; cannot RCE
971 }
972
973 if (!phase->is_scaled_iv_plus_offset(rc_exp, trip_counter, NULL, NULL)) {
974 continue;
975 }
976 // Yeah! Found a test like 'trip+off vs limit'
977 // Test is an IfNode, has 2 projections. If BOTH are in the loop
978 // we need loop unswitching instead of iteration splitting.
979 if( is_loop_exit(iff) )
980 return true; // Found reason to split iterations
981 } // End of is IF
982 }
983
984 return false;
985 }
986
987 //------------------------------policy_peel_only-------------------------------
988 // Return TRUE or FALSE if the loop should NEVER be RCE'd or aligned. Useful
989 // for unrolling loops with NO array accesses.
990 bool IdealLoopTree::policy_peel_only( PhaseIdealLoop *phase ) const {
991 // check for vectorized loops, any peeling done was already applied
992 if (_head->is_CountedLoop() && _head->as_CountedLoop()->do_unroll_only()) return false;
993
994 for( uint i = 0; i < _body.size(); i++ )
995 if( _body[i]->is_Mem() )
996 return false;
997
998 // No memory accesses at all!
999 return true;
1000 }
1001
1002 //------------------------------clone_up_backedge_goo--------------------------
1003 // If Node n lives in the back_ctrl block and cannot float, we clone a private
1004 // version of n in preheader_ctrl block and return that, otherwise return n.
1005 Node *PhaseIdealLoop::clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones ) {
1006 if( get_ctrl(n) != back_ctrl ) return n;
1007
1008 // Only visit once
1009 if (visited.test_set(n->_idx)) {
1010 Node *x = clones.find(n->_idx);
1011 if (x != NULL)
1012 return x;
1013 return n;
1014 }
1015
1016 Node *x = NULL; // If required, a clone of 'n'
1017 // Check for 'n' being pinned in the backedge.
1018 if( n->in(0) && n->in(0) == back_ctrl ) {
1019 assert(clones.find(n->_idx) == NULL, "dead loop");
1020 x = n->clone(); // Clone a copy of 'n' to preheader
1021 clones.push(x, n->_idx);
1022 x->set_req( 0, preheader_ctrl ); // Fix x's control input to preheader
1023 }
1024
1025 // Recursive fixup any other input edges into x.
1026 // If there are no changes we can just return 'n', otherwise
1027 // we need to clone a private copy and change it.
1028 for( uint i = 1; i < n->req(); i++ ) {
1029 Node *g = clone_up_backedge_goo( back_ctrl, preheader_ctrl, n->in(i), visited, clones );
1030 if( g != n->in(i) ) {
1031 if( !x ) {
1032 assert(clones.find(n->_idx) == NULL, "dead loop");
1033 x = n->clone();
1034 clones.push(x, n->_idx);
1035 }
1036 x->set_req(i, g);
1037 }
1038 }
1039 if( x ) { // x can legally float to pre-header location
1040 register_new_node( x, preheader_ctrl );
1041 return x;
1042 } else { // raise n to cover LCA of uses
1043 set_ctrl( n, find_non_split_ctrl(back_ctrl->in(0)) );
1044 }
1045 return n;
1046 }
1047
1048 Node* PhaseIdealLoop::cast_incr_before_loop(Node* incr, Node* ctrl, Node* loop) {
1049 Node* castii = new CastIINode(incr, TypeInt::INT, true);
1050 castii->set_req(0, ctrl);
1051 register_new_node(castii, ctrl);
1052 for (DUIterator_Fast imax, i = incr->fast_outs(imax); i < imax; i++) {
1053 Node* n = incr->fast_out(i);
1054 if (n->is_Phi() && n->in(0) == loop) {
1055 int nrep = n->replace_edge(incr, castii);
1056 return castii;
1057 }
1058 }
1059 return NULL;
1060 }
1061
1062 #ifdef ASSERT
1063 void PhaseIdealLoop::ensure_zero_trip_guard_proj(Node* node, bool is_main_loop) {
1064 assert(node->is_IfProj(), "must be the zero trip guard If node");
1065 Node* zer_bol = node->in(0)->in(1);
1066 assert(zer_bol != NULL && zer_bol->is_Bool(), "must be Bool");
1067 Node* zer_cmp = zer_bol->in(1);
1068 assert(zer_cmp != NULL && zer_cmp->Opcode() == Op_CmpI, "must be CmpI");
1069 // For the main loop, the opaque node is the second input to zer_cmp, for the post loop it's the first input node
1070 Node* zer_opaq = zer_cmp->in(is_main_loop ? 2 : 1);
1071 assert(zer_opaq != NULL && zer_opaq->Opcode() == Op_Opaque1, "must be Opaque1");
1072 }
1073 #endif
1074
1075 // Make a copy of the skeleton range check predicates before the main
1076 // loop and set the initial value of loop as input. After unrolling,
1077 // the range of values for the induction variable in the main loop can
1078 // fall outside the allowed range of values by the array access (main
1079 // loop is never executed). When that happens, range check
1080 // CastII/ConvI2L nodes cause some data paths to die. For consistency,
1081 // the control paths must die too but the range checks were removed by
1082 // predication. The range checks that we add here guarantee that they do.
1083 void PhaseIdealLoop::copy_skeleton_predicates_to_main_loop_helper(Node* predicate, Node* start, Node* end,
1084 IdealLoopTree* outer_loop, LoopNode* outer_main_head,
1085 uint dd_main_head, const uint idx_before_pre_post,
1086 const uint idx_after_post_before_pre, Node* zero_trip_guard_proj_main,
1087 Node* zero_trip_guard_proj_post, const Node_List &old_new) {
1088 if (predicate != NULL) {
1089 #ifdef ASSERT
1090 ensure_zero_trip_guard_proj(zero_trip_guard_proj_main, true);
1091 ensure_zero_trip_guard_proj(zero_trip_guard_proj_post, false);
1092 #endif
1093 IfNode* iff = predicate->in(0)->as_If();
1094 ProjNode* uncommon_proj = iff->proj_out(1 - predicate->as_Proj()->_con);
1095 Node* rgn = uncommon_proj->unique_ctrl_out();
1096 assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct");
1097 assert(iff->in(1)->in(1)->Opcode() == Op_Opaque1, "unexpected predicate shape");
1098 predicate = iff->in(0);
1099 Node* current_proj = outer_main_head->in(LoopNode::EntryControl);
1100 Node* prev_proj = current_proj;
1101 while (predicate != NULL && predicate->is_Proj() && predicate->in(0)->is_If()) {
1102 iff = predicate->in(0)->as_If();
1103 uncommon_proj = iff->proj_out(1 - predicate->as_Proj()->_con);
1104 if (uncommon_proj->unique_ctrl_out() != rgn)
1105 break;
1106 if (iff->in(1)->Opcode() == Op_Opaque4) {
1107 assert(skeleton_predicate_has_opaque(iff), "unexpected");
1108 // Clone the skeleton predicate twice and initialize one with the initial
1109 // value of the loop induction variable. Leave the other predicate
1110 // to be initialized when increasing the stride during loop unrolling.
1111 prev_proj = clone_skeleton_predicate(iff, start, predicate, uncommon_proj, current_proj, outer_loop, prev_proj);
1112 assert(skeleton_predicate_has_opaque(prev_proj->in(0)->as_If()) == (start->Opcode() == Op_Opaque1), "");
1113 prev_proj = clone_skeleton_predicate(iff, end, predicate, uncommon_proj, current_proj, outer_loop, prev_proj);
1114 assert(skeleton_predicate_has_opaque(prev_proj->in(0)->as_If()) == (end->Opcode() == Op_Opaque1), "");
1115
1116 // Rewire any control inputs from the cloned skeleton predicates down to the main and post loop for data nodes that are part of the
1117 // main loop (and were cloned to the pre and post loop).
1118 for (DUIterator i = predicate->outs(); predicate->has_out(i); i++) {
1119 Node* loop_node = predicate->out(i);
1120 Node* pre_loop_node = old_new[loop_node->_idx];
1121 // Change the control if 'loop_node' is part of the main loop. If there is an old->new mapping and the index of
1122 // 'pre_loop_node' is greater than idx_before_pre_post, then we know that 'loop_node' was cloned and is part of
1123 // the main loop (and 'pre_loop_node' is part of the pre loop).
1124 if (!loop_node->is_CFG() && (pre_loop_node != NULL && pre_loop_node->_idx > idx_after_post_before_pre)) {
1125 // 'loop_node' is a data node and part of the main loop. Rewire the control to the projection of the zero-trip guard if node
1126 // of the main loop that is immediately preceding the cloned predicates.
1127 _igvn.replace_input_of(loop_node, 0, zero_trip_guard_proj_main);
1128 --i;
1129 } else if (loop_node->_idx > idx_before_pre_post && loop_node->_idx < idx_after_post_before_pre) {
1130 // 'loop_node' is a data node and part of the post loop. Rewire the control to the projection of the zero-trip guard if node
1131 // of the post loop that is immediately preceding the post loop header node (there are no cloned predicates for the post loop).
1132 assert(pre_loop_node == NULL, "a node belonging to the post loop should not have an old_new mapping at this stage");
1133 _igvn.replace_input_of(loop_node, 0, zero_trip_guard_proj_post);
1134 --i;
1135 }
1136 }
1137
1138 // Remove the skeleton predicate from the pre-loop
1139 _igvn.replace_input_of(iff, 1, _igvn.intcon(1));
1140 }
1141 predicate = predicate->in(0)->in(0);
1142 }
1143 _igvn.replace_input_of(outer_main_head, LoopNode::EntryControl, prev_proj);
1144 set_idom(outer_main_head, prev_proj, dd_main_head);
1145 }
1146 }
1147
1148 static bool skeleton_follow_inputs(Node* n, int op) {
1149 return (n->is_Bool() ||
1150 n->is_Cmp() ||
1151 op == Op_AndL ||
1152 op == Op_OrL ||
1153 op == Op_RShiftL ||
1154 op == Op_LShiftL ||
1155 op == Op_AddL ||
1156 op == Op_AddI ||
1157 op == Op_MulL ||
1158 op == Op_MulI ||
1159 op == Op_SubL ||
1160 op == Op_SubI ||
1161 op == Op_ConvI2L);
1162 }
1163
1164 bool PhaseIdealLoop::skeleton_predicate_has_opaque(IfNode* iff) {
1165 ResourceMark rm;
1166 Unique_Node_List wq;
1167 wq.push(iff->in(1)->in(1));
1168 for (uint i = 0; i < wq.size(); i++) {
1169 Node* n = wq.at(i);
1170 int op = n->Opcode();
1171 if (skeleton_follow_inputs(n, op)) {
1172 for (uint j = 1; j < n->req(); j++) {
1173 Node* m = n->in(j);
1174 if (m != NULL) {
1175 wq.push(m);
1176 }
1177 }
1178 continue;
1179 }
1180 if (op == Op_Opaque1) {
1181 return true;
1182 }
1183 }
1184 return false;
1185 }
1186
1187 Node* PhaseIdealLoop::clone_skeleton_predicate(Node* iff, Node* value, Node* predicate, Node* uncommon_proj,
1188 Node* current_proj, IdealLoopTree* outer_loop, Node* prev_proj) {
1189 Node_Stack to_clone(2);
1190 to_clone.push(iff->in(1), 1);
1191 uint current = C->unique();
1192 Node* result = NULL;
1193 // Look for the opaque node to replace with the new value
1194 // and clone everything in between. We keep the Opaque4 node
1195 // so the duplicated predicates are eliminated once loop
1196 // opts are over: they are here only to keep the IR graph
1197 // consistent.
1198 do {
1199 Node* n = to_clone.node();
1200 uint i = to_clone.index();
1201 Node* m = n->in(i);
1202 int op = m->Opcode();
1203 if (skeleton_follow_inputs(m, op)) {
1204 to_clone.push(m, 1);
1205 continue;
1206 }
1207 if (op == Op_Opaque1) {
1208 if (n->_idx < current) {
1209 n = n->clone();
1210 }
1211 n->set_req(i, value);
1212 register_new_node(n, current_proj);
1213 to_clone.set_node(n);
1214 }
1215 for (;;) {
1216 Node* cur = to_clone.node();
1217 uint j = to_clone.index();
1218 if (j+1 < cur->req()) {
1219 to_clone.set_index(j+1);
1220 break;
1221 }
1222 to_clone.pop();
1223 if (to_clone.size() == 0) {
1224 result = cur;
1225 break;
1226 }
1227 Node* next = to_clone.node();
1228 j = to_clone.index();
1229 if (next->in(j) != cur) {
1230 assert(cur->_idx >= current || next->in(j)->Opcode() == Op_Opaque1, "new node or Opaque1 being replaced");
1231 if (next->_idx < current) {
1232 next = next->clone();
1233 register_new_node(next, current_proj);
1234 to_clone.set_node(next);
1235 }
1236 next->set_req(j, cur);
1237 }
1238 }
1239 } while (result == NULL);
1240 assert(result->_idx >= current, "new node expected");
1241
1242 Node* proj = predicate->clone();
1243 Node* other_proj = uncommon_proj->clone();
1244 Node* new_iff = iff->clone();
1245 new_iff->set_req(1, result);
1246 proj->set_req(0, new_iff);
1247 other_proj->set_req(0, new_iff);
1248 Node *frame = new ParmNode(C->start(), TypeFunc::FramePtr);
1249 register_new_node(frame, C->start());
1250 // It's impossible for the predicate to fail at runtime. Use an Halt node.
1251 Node* halt = new HaltNode(other_proj, frame, "duplicated predicate failed which is impossible");
1252 C->root()->add_req(halt);
1253 new_iff->set_req(0, prev_proj);
1254
1255 register_control(new_iff, outer_loop->_parent, prev_proj);
1256 register_control(proj, outer_loop->_parent, new_iff);
1257 register_control(other_proj, _ltree_root, new_iff);
1258 register_control(halt, _ltree_root, other_proj);
1259 return proj;
1260 }
1261
1262 void PhaseIdealLoop::copy_skeleton_predicates_to_main_loop(CountedLoopNode* pre_head, Node* start, Node* end,
1263 IdealLoopTree* outer_loop, LoopNode* outer_main_head,
1264 uint dd_main_head, const uint idx_before_pre_post,
1265 const uint idx_after_post_before_pre, Node* zero_trip_guard_proj_main,
1266 Node* zero_trip_guard_proj_post, const Node_List &old_new) {
1267 if (UseLoopPredicate) {
1268 Node* entry = pre_head->in(LoopNode::EntryControl);
1269 Node* predicate = NULL;
1270 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
1271 if (predicate != NULL) {
1272 entry = skip_loop_predicates(entry);
1273 }
1274 Node* profile_predicate = NULL;
1275 if (UseProfiledLoopPredicate) {
1276 profile_predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_profile_predicate);
1277 if (profile_predicate != NULL) {
1278 entry = skip_loop_predicates(entry);
1279 }
1280 }
1281 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
1282 copy_skeleton_predicates_to_main_loop_helper(predicate, start, end, outer_loop, outer_main_head, dd_main_head,
1283 idx_before_pre_post, idx_after_post_before_pre, zero_trip_guard_proj_main,
1284 zero_trip_guard_proj_post, old_new);
1285 copy_skeleton_predicates_to_main_loop_helper(profile_predicate, start, end, outer_loop, outer_main_head, dd_main_head,
1286 idx_before_pre_post, idx_after_post_before_pre, zero_trip_guard_proj_main,
1287 zero_trip_guard_proj_post, old_new);
1288 }
1289 }
1290
1291 //------------------------------insert_pre_post_loops--------------------------
1292 // Insert pre and post loops. If peel_only is set, the pre-loop can not have
1293 // more iterations added. It acts as a 'peel' only, no lower-bound RCE, no
1294 // alignment. Useful to unroll loops that do no array accesses.
1295 void PhaseIdealLoop::insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only ) {
1296
1297 #ifndef PRODUCT
1298 if (TraceLoopOpts) {
1299 if (peel_only)
1300 tty->print("PeelMainPost ");
1301 else
1302 tty->print("PreMainPost ");
1303 loop->dump_head();
1304 }
1305 #endif
1306 C->set_major_progress();
1307
1308 // Find common pieces of the loop being guarded with pre & post loops
1309 CountedLoopNode *main_head = loop->_head->as_CountedLoop();
1310 assert( main_head->is_normal_loop(), "" );
1311 CountedLoopEndNode *main_end = main_head->loopexit();
1312 assert( main_end->outcnt() == 2, "1 true, 1 false path only" );
1313
1314 Node *pre_header= main_head->in(LoopNode::EntryControl);
1315 Node *init = main_head->init_trip();
1316 Node *incr = main_end ->incr();
1317 Node *limit = main_end ->limit();
1318 Node *stride = main_end ->stride();
1319 Node *cmp = main_end ->cmp_node();
1320 BoolTest::mask b_test = main_end->test_trip();
1321
1322 // Need only 1 user of 'bol' because I will be hacking the loop bounds.
1323 Node *bol = main_end->in(CountedLoopEndNode::TestValue);
1324 if( bol->outcnt() != 1 ) {
1325 bol = bol->clone();
1326 register_new_node(bol,main_end->in(CountedLoopEndNode::TestControl));
1327 _igvn.replace_input_of(main_end, CountedLoopEndNode::TestValue, bol);
1328 }
1329 // Need only 1 user of 'cmp' because I will be hacking the loop bounds.
1330 if( cmp->outcnt() != 1 ) {
1331 cmp = cmp->clone();
1332 register_new_node(cmp,main_end->in(CountedLoopEndNode::TestControl));
1333 _igvn.replace_input_of(bol, 1, cmp);
1334 }
1335
1336 // Add the post loop
1337 const uint idx_before_pre_post = Compile::current()->unique();
1338 CountedLoopNode *post_head = NULL;
1339 Node *main_exit = insert_post_loop(loop, old_new, main_head, main_end, incr, limit, post_head);
1340 const uint idx_after_post_before_pre = Compile::current()->unique();
1341
1342 //------------------------------
1343 // Step B: Create Pre-Loop.
1344
1345 // Step B1: Clone the loop body. The clone becomes the pre-loop. The main
1346 // loop pre-header illegally has 2 control users (old & new loops).
1347 LoopNode* outer_main_head = main_head;
1348 IdealLoopTree* outer_loop = loop;
1349 if (main_head->is_strip_mined()) {
1350 main_head->verify_strip_mined(1);
1351 outer_main_head = main_head->outer_loop();
1352 outer_loop = loop->_parent;
1353 assert(outer_loop->_head == outer_main_head, "broken loop tree");
1354 }
1355 uint dd_main_head = dom_depth(outer_main_head);
1356 clone_loop(loop, old_new, dd_main_head, ControlAroundStripMined);
1357 CountedLoopNode* pre_head = old_new[main_head->_idx]->as_CountedLoop();
1358 CountedLoopEndNode* pre_end = old_new[main_end ->_idx]->as_CountedLoopEnd();
1359 pre_head->set_pre_loop(main_head);
1360 Node *pre_incr = old_new[incr->_idx];
1361
1362 // Reduce the pre-loop trip count.
1363 pre_end->_prob = PROB_FAIR;
1364
1365 // Find the pre-loop normal exit.
1366 Node* pre_exit = pre_end->proj_out(false);
1367 assert( pre_exit->Opcode() == Op_IfFalse, "" );
1368 IfFalseNode *new_pre_exit = new IfFalseNode(pre_end);
1369 _igvn.register_new_node_with_optimizer( new_pre_exit );
1370 set_idom(new_pre_exit, pre_end, dd_main_head);
1371 set_loop(new_pre_exit, outer_loop->_parent);
1372
1373 // Step B2: Build a zero-trip guard for the main-loop. After leaving the
1374 // pre-loop, the main-loop may not execute at all. Later in life this
1375 // zero-trip guard will become the minimum-trip guard when we unroll
1376 // the main-loop.
1377 Node *min_opaq = new Opaque1Node(C, limit);
1378 Node *min_cmp = new CmpINode( pre_incr, min_opaq );
1379 Node *min_bol = new BoolNode( min_cmp, b_test );
1380 register_new_node( min_opaq, new_pre_exit );
1381 register_new_node( min_cmp , new_pre_exit );
1382 register_new_node( min_bol , new_pre_exit );
1383
1384 // Build the IfNode (assume the main-loop is executed always).
1385 IfNode *min_iff = new IfNode( new_pre_exit, min_bol, PROB_ALWAYS, COUNT_UNKNOWN );
1386 _igvn.register_new_node_with_optimizer( min_iff );
1387 set_idom(min_iff, new_pre_exit, dd_main_head);
1388 set_loop(min_iff, outer_loop->_parent);
1389
1390 // Plug in the false-path, taken if we need to skip main-loop
1391 _igvn.hash_delete( pre_exit );
1392 pre_exit->set_req(0, min_iff);
1393 set_idom(pre_exit, min_iff, dd_main_head);
1394 set_idom(pre_exit->unique_ctrl_out(), min_iff, dd_main_head);
1395 // Make the true-path, must enter the main loop
1396 Node *min_taken = new IfTrueNode( min_iff );
1397 _igvn.register_new_node_with_optimizer( min_taken );
1398 set_idom(min_taken, min_iff, dd_main_head);
1399 set_loop(min_taken, outer_loop->_parent);
1400 // Plug in the true path
1401 _igvn.hash_delete(outer_main_head);
1402 outer_main_head->set_req(LoopNode::EntryControl, min_taken);
1403 set_idom(outer_main_head, min_taken, dd_main_head);
1404
1405 Arena *a = Thread::current()->resource_area();
1406 VectorSet visited(a);
1407 Node_Stack clones(a, main_head->back_control()->outcnt());
1408 // Step B3: Make the fall-in values to the main-loop come from the
1409 // fall-out values of the pre-loop.
1410 for (DUIterator_Fast i2max, i2 = main_head->fast_outs(i2max); i2 < i2max; i2++) {
1411 Node* main_phi = main_head->fast_out(i2);
1412 if( main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() > 0 ) {
1413 Node *pre_phi = old_new[main_phi->_idx];
1414 Node *fallpre = clone_up_backedge_goo(pre_head->back_control(),
1415 main_head->skip_strip_mined()->in(LoopNode::EntryControl),
1416 pre_phi->in(LoopNode::LoopBackControl),
1417 visited, clones);
1418 _igvn.hash_delete(main_phi);
1419 main_phi->set_req( LoopNode::EntryControl, fallpre );
1420 }
1421 }
1422
1423 // Nodes inside the loop may be control dependent on a predicate
1424 // that was moved before the preloop. If the back branch of the main
1425 // or post loops becomes dead, those nodes won't be dependent on the
1426 // test that guards that loop nest anymore which could lead to an
1427 // incorrect array access because it executes independently of the
1428 // test that was guarding the loop nest. We add a special CastII on
1429 // the if branch that enters the loop, between the input induction
1430 // variable value and the induction variable Phi to preserve correct
1431 // dependencies.
1432
1433 // CastII for the main loop:
1434 Node* castii = cast_incr_before_loop( pre_incr, min_taken, main_head );
1435 assert(castii != NULL, "no castII inserted");
1436 Node* opaque_castii = new Opaque1Node(C, castii);
1437 register_new_node(opaque_castii, outer_main_head->in(LoopNode::EntryControl));
1438 assert(post_head->in(1)->is_IfProj(), "must be zero-trip guard If node projection of the post loop");
1439 copy_skeleton_predicates_to_main_loop(pre_head, castii, opaque_castii, outer_loop, outer_main_head, dd_main_head,
1440 idx_before_pre_post, idx_after_post_before_pre, min_taken, post_head->in(1), old_new);
1441
1442 // Step B4: Shorten the pre-loop to run only 1 iteration (for now).
1443 // RCE and alignment may change this later.
1444 Node *cmp_end = pre_end->cmp_node();
1445 assert( cmp_end->in(2) == limit, "" );
1446 Node *pre_limit = new AddINode( init, stride );
1447
1448 // Save the original loop limit in this Opaque1 node for
1449 // use by range check elimination.
1450 Node *pre_opaq = new Opaque1Node(C, pre_limit, limit);
1451
1452 register_new_node( pre_limit, pre_head->in(0) );
1453 register_new_node( pre_opaq , pre_head->in(0) );
1454
1455 // Since no other users of pre-loop compare, I can hack limit directly
1456 assert( cmp_end->outcnt() == 1, "no other users" );
1457 _igvn.hash_delete(cmp_end);
1458 cmp_end->set_req(2, peel_only ? pre_limit : pre_opaq);
1459
1460 // Special case for not-equal loop bounds:
1461 // Change pre loop test, main loop test, and the
1462 // main loop guard test to use lt or gt depending on stride
1463 // direction:
1464 // positive stride use <
1465 // negative stride use >
1466 //
1467 // not-equal test is kept for post loop to handle case
1468 // when init > limit when stride > 0 (and reverse).
1469
1470 if (pre_end->in(CountedLoopEndNode::TestValue)->as_Bool()->_test._test == BoolTest::ne) {
1471
1472 BoolTest::mask new_test = (main_end->stride_con() > 0) ? BoolTest::lt : BoolTest::gt;
1473 // Modify pre loop end condition
1474 Node* pre_bol = pre_end->in(CountedLoopEndNode::TestValue)->as_Bool();
1475 BoolNode* new_bol0 = new BoolNode(pre_bol->in(1), new_test);
1476 register_new_node( new_bol0, pre_head->in(0) );
1477 _igvn.replace_input_of(pre_end, CountedLoopEndNode::TestValue, new_bol0);
1478 // Modify main loop guard condition
1479 assert(min_iff->in(CountedLoopEndNode::TestValue) == min_bol, "guard okay");
1480 BoolNode* new_bol1 = new BoolNode(min_bol->in(1), new_test);
1481 register_new_node( new_bol1, new_pre_exit );
1482 _igvn.hash_delete(min_iff);
1483 min_iff->set_req(CountedLoopEndNode::TestValue, new_bol1);
1484 // Modify main loop end condition
1485 BoolNode* main_bol = main_end->in(CountedLoopEndNode::TestValue)->as_Bool();
1486 BoolNode* new_bol2 = new BoolNode(main_bol->in(1), new_test);
1487 register_new_node( new_bol2, main_end->in(CountedLoopEndNode::TestControl) );
1488 _igvn.replace_input_of(main_end, CountedLoopEndNode::TestValue, new_bol2);
1489 }
1490
1491 // Flag main loop
1492 main_head->set_main_loop();
1493 if( peel_only ) main_head->set_main_no_pre_loop();
1494
1495 // Subtract a trip count for the pre-loop.
1496 main_head->set_trip_count(main_head->trip_count() - 1);
1497
1498 // It's difficult to be precise about the trip-counts
1499 // for the pre/post loops. They are usually very short,
1500 // so guess that 4 trips is a reasonable value.
1501 post_head->set_profile_trip_cnt(4.0);
1502 pre_head->set_profile_trip_cnt(4.0);
1503
1504 // Now force out all loop-invariant dominating tests. The optimizer
1505 // finds some, but we _know_ they are all useless.
1506 peeled_dom_test_elim(loop,old_new);
1507 loop->record_for_igvn();
1508 }
1509
1510 //------------------------------insert_vector_post_loop------------------------
1511 // Insert a copy of the atomic unrolled vectorized main loop as a post loop,
1512 // unroll_policy has already informed us that more unrolling is about to happen to
1513 // the main loop. The resultant post loop will serve as a vectorized drain loop.
1514 void PhaseIdealLoop::insert_vector_post_loop(IdealLoopTree *loop, Node_List &old_new) {
1515 if (!loop->_head->is_CountedLoop()) return;
1516
1517 CountedLoopNode *cl = loop->_head->as_CountedLoop();
1518
1519 // only process vectorized main loops
1520 if (!cl->is_vectorized_loop() || !cl->is_main_loop()) return;
1521
1522 int slp_max_unroll_factor = cl->slp_max_unroll();
1523 int cur_unroll = cl->unrolled_count();
1524
1525 if (slp_max_unroll_factor == 0) return;
1526
1527 // only process atomic unroll vector loops (not super unrolled after vectorization)
1528 if (cur_unroll != slp_max_unroll_factor) return;
1529
1530 // we only ever process this one time
1531 if (cl->has_atomic_post_loop()) return;
1532
1533 #ifndef PRODUCT
1534 if (TraceLoopOpts) {
1535 tty->print("PostVector ");
1536 loop->dump_head();
1537 }
1538 #endif
1539 C->set_major_progress();
1540
1541 // Find common pieces of the loop being guarded with pre & post loops
1542 CountedLoopNode *main_head = loop->_head->as_CountedLoop();
1543 CountedLoopEndNode *main_end = main_head->loopexit();
1544 // diagnostic to show loop end is not properly formed
1545 assert(main_end->outcnt() == 2, "1 true, 1 false path only");
1546
1547 // mark this loop as processed
1548 main_head->mark_has_atomic_post_loop();
1549
1550 Node *incr = main_end->incr();
1551 Node *limit = main_end->limit();
1552
1553 // In this case we throw away the result as we are not using it to connect anything else.
1554 CountedLoopNode *post_head = NULL;
1555 insert_post_loop(loop, old_new, main_head, main_end, incr, limit, post_head);
1556
1557 // It's difficult to be precise about the trip-counts
1558 // for post loops. They are usually very short,
1559 // so guess that unit vector trips is a reasonable value.
1560 post_head->set_profile_trip_cnt(cur_unroll);
1561
1562 // Now force out all loop-invariant dominating tests. The optimizer
1563 // finds some, but we _know_ they are all useless.
1564 peeled_dom_test_elim(loop, old_new);
1565 loop->record_for_igvn();
1566 }
1567
1568
1569 //-------------------------insert_scalar_rced_post_loop------------------------
1570 // Insert a copy of the rce'd main loop as a post loop,
1571 // We have not unrolled the main loop, so this is the right time to inject this.
1572 // Later we will examine the partner of this post loop pair which still has range checks
1573 // to see inject code which tests at runtime if the range checks are applicable.
1574 void PhaseIdealLoop::insert_scalar_rced_post_loop(IdealLoopTree *loop, Node_List &old_new) {
1575 if (!loop->_head->is_CountedLoop()) return;
1576
1577 CountedLoopNode *cl = loop->_head->as_CountedLoop();
1578
1579 // only process RCE'd main loops
1580 if (!cl->is_main_loop() || cl->range_checks_present()) return;
1581
1582 #ifndef PRODUCT
1583 if (TraceLoopOpts) {
1584 tty->print("PostScalarRce ");
1585 loop->dump_head();
1586 }
1587 #endif
1588 C->set_major_progress();
1589
1590 // Find common pieces of the loop being guarded with pre & post loops
1591 CountedLoopNode *main_head = loop->_head->as_CountedLoop();
1592 CountedLoopEndNode *main_end = main_head->loopexit();
1593 // diagnostic to show loop end is not properly formed
1594 assert(main_end->outcnt() == 2, "1 true, 1 false path only");
1595
1596 Node *incr = main_end->incr();
1597 Node *limit = main_end->limit();
1598
1599 // In this case we throw away the result as we are not using it to connect anything else.
1600 CountedLoopNode *post_head = NULL;
1601 insert_post_loop(loop, old_new, main_head, main_end, incr, limit, post_head);
1602
1603 // It's difficult to be precise about the trip-counts
1604 // for post loops. They are usually very short,
1605 // so guess that unit vector trips is a reasonable value.
1606 post_head->set_profile_trip_cnt(4.0);
1607 post_head->set_is_rce_post_loop();
1608
1609 // Now force out all loop-invariant dominating tests. The optimizer
1610 // finds some, but we _know_ they are all useless.
1611 peeled_dom_test_elim(loop, old_new);
1612 loop->record_for_igvn();
1613 }
1614
1615
1616 //------------------------------insert_post_loop-------------------------------
1617 // Insert post loops. Add a post loop to the given loop passed.
1618 Node *PhaseIdealLoop::insert_post_loop(IdealLoopTree *loop, Node_List &old_new,
1619 CountedLoopNode *main_head, CountedLoopEndNode *main_end,
1620 Node *incr, Node *limit, CountedLoopNode *&post_head) {
1621 IfNode* outer_main_end = main_end;
1622 IdealLoopTree* outer_loop = loop;
1623 if (main_head->is_strip_mined()) {
1624 main_head->verify_strip_mined(1);
1625 outer_main_end = main_head->outer_loop_end();
1626 outer_loop = loop->_parent;
1627 assert(outer_loop->_head == main_head->in(LoopNode::EntryControl), "broken loop tree");
1628 }
1629
1630 //------------------------------
1631 // Step A: Create a new post-Loop.
1632 Node* main_exit = outer_main_end->proj_out(false);
1633 assert(main_exit->Opcode() == Op_IfFalse, "");
1634 int dd_main_exit = dom_depth(main_exit);
1635
1636 // Step A1: Clone the loop body of main. The clone becomes the post-loop.
1637 // The main loop pre-header illegally has 2 control users (old & new loops).
1638 clone_loop(loop, old_new, dd_main_exit, ControlAroundStripMined);
1639 assert(old_new[main_end->_idx]->Opcode() == Op_CountedLoopEnd, "");
1640 post_head = old_new[main_head->_idx]->as_CountedLoop();
1641 post_head->set_normal_loop();
1642 post_head->set_post_loop(main_head);
1643
1644 // Reduce the post-loop trip count.
1645 CountedLoopEndNode* post_end = old_new[main_end->_idx]->as_CountedLoopEnd();
1646 post_end->_prob = PROB_FAIR;
1647
1648 // Build the main-loop normal exit.
1649 IfFalseNode *new_main_exit = new IfFalseNode(outer_main_end);
1650 _igvn.register_new_node_with_optimizer(new_main_exit);
1651 set_idom(new_main_exit, outer_main_end, dd_main_exit);
1652 set_loop(new_main_exit, outer_loop->_parent);
1653
1654 // Step A2: Build a zero-trip guard for the post-loop. After leaving the
1655 // main-loop, the post-loop may not execute at all. We 'opaque' the incr
1656 // (the previous loop trip-counter exit value) because we will be changing
1657 // the exit value (via additional unrolling) so we cannot constant-fold away the zero
1658 // trip guard until all unrolling is done.
1659 Node *zer_opaq = new Opaque1Node(C, incr);
1660 Node *zer_cmp = new CmpINode(zer_opaq, limit);
1661 Node *zer_bol = new BoolNode(zer_cmp, main_end->test_trip());
1662 register_new_node(zer_opaq, new_main_exit);
1663 register_new_node(zer_cmp, new_main_exit);
1664 register_new_node(zer_bol, new_main_exit);
1665
1666 // Build the IfNode
1667 IfNode *zer_iff = new IfNode(new_main_exit, zer_bol, PROB_FAIR, COUNT_UNKNOWN);
1668 _igvn.register_new_node_with_optimizer(zer_iff);
1669 set_idom(zer_iff, new_main_exit, dd_main_exit);
1670 set_loop(zer_iff, outer_loop->_parent);
1671
1672 // Plug in the false-path, taken if we need to skip this post-loop
1673 _igvn.replace_input_of(main_exit, 0, zer_iff);
1674 set_idom(main_exit, zer_iff, dd_main_exit);
1675 set_idom(main_exit->unique_out(), zer_iff, dd_main_exit);
1676 // Make the true-path, must enter this post loop
1677 Node *zer_taken = new IfTrueNode(zer_iff);
1678 _igvn.register_new_node_with_optimizer(zer_taken);
1679 set_idom(zer_taken, zer_iff, dd_main_exit);
1680 set_loop(zer_taken, outer_loop->_parent);
1681 // Plug in the true path
1682 _igvn.hash_delete(post_head);
1683 post_head->set_req(LoopNode::EntryControl, zer_taken);
1684 set_idom(post_head, zer_taken, dd_main_exit);
1685
1686 Arena *a = Thread::current()->resource_area();
1687 VectorSet visited(a);
1688 Node_Stack clones(a, main_head->back_control()->outcnt());
1689 // Step A3: Make the fall-in values to the post-loop come from the
1690 // fall-out values of the main-loop.
1691 for (DUIterator_Fast imax, i = main_head->fast_outs(imax); i < imax; i++) {
1692 Node* main_phi = main_head->fast_out(i);
1693 if (main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() >0) {
1694 Node *cur_phi = old_new[main_phi->_idx];
1695 Node *fallnew = clone_up_backedge_goo(main_head->back_control(),
1696 post_head->init_control(),
1697 main_phi->in(LoopNode::LoopBackControl),
1698 visited, clones);
1699 _igvn.hash_delete(cur_phi);
1700 cur_phi->set_req(LoopNode::EntryControl, fallnew);
1701 }
1702 }
1703
1704 // CastII for the new post loop:
1705 Node* castii = cast_incr_before_loop(zer_opaq->in(1), zer_taken, post_head);
1706 assert(castii != NULL, "no castII inserted");
1707
1708 return new_main_exit;
1709 }
1710
1711 //------------------------------is_invariant-----------------------------
1712 // Return true if n is invariant
1713 bool IdealLoopTree::is_invariant(Node* n) const {
1714 Node *n_c = _phase->has_ctrl(n) ? _phase->get_ctrl(n) : n;
1715 if (n_c->is_top()) return false;
1716 return !is_member(_phase->get_loop(n_c));
1717 }
1718
1719 void PhaseIdealLoop::update_main_loop_skeleton_predicates(Node* ctrl, CountedLoopNode* loop_head, Node* init, int stride_con) {
1720 // Search for skeleton predicates and update them according to the new stride
1721 Node* entry = ctrl;
1722 Node* prev_proj = ctrl;
1723 LoopNode* outer_loop_head = loop_head->skip_strip_mined();
1724 IdealLoopTree* outer_loop = get_loop(outer_loop_head);
1725 while (entry != NULL && entry->is_Proj() && entry->in(0)->is_If()) {
1726 IfNode* iff = entry->in(0)->as_If();
1727 ProjNode* proj = iff->proj_out(1 - entry->as_Proj()->_con);
1728 if (proj->unique_ctrl_out()->Opcode() != Op_Halt) {
1729 break;
1730 }
1731 if (iff->in(1)->Opcode() == Op_Opaque4) {
1732 // Look for predicate with an Opaque1 node that can be used as a template
1733 if (!skeleton_predicate_has_opaque(iff)) {
1734 // No Opaque1 node? It's either the check for the first value
1735 // of the first iteration or the check for the last value of
1736 // the first iteration of an unrolled loop. We can't
1737 // tell. Kill it in any case.
1738 _igvn.replace_input_of(iff, 1, iff->in(1)->in(2));
1739 } else {
1740 // Add back the predicate for the value at the beginning of the first entry
1741 prev_proj = clone_skeleton_predicate(iff, init, entry, proj, ctrl, outer_loop, prev_proj);
1742 assert(!skeleton_predicate_has_opaque(prev_proj->in(0)->as_If()), "unexpected");
1743 // Compute the value of the loop induction variable at the end of the
1744 // first iteration of the unrolled loop: init + new_stride_con - init_inc
1745 int init_inc = stride_con/loop_head->unrolled_count();
1746 assert(init_inc != 0, "invalid loop increment");
1747 int new_stride_con = stride_con * 2;
1748 Node* max_value = _igvn.intcon(new_stride_con - init_inc);
1749 max_value = new AddINode(init, max_value);
1750 register_new_node(max_value, get_ctrl(iff->in(1)));
1751 prev_proj = clone_skeleton_predicate(iff, max_value, entry, proj, ctrl, outer_loop, prev_proj);
1752 assert(!skeleton_predicate_has_opaque(prev_proj->in(0)->as_If()), "unexpected");
1753 }
1754 }
1755 entry = entry->in(0)->in(0);
1756 }
1757 if (prev_proj != ctrl) {
1758 _igvn.replace_input_of(outer_loop_head, LoopNode::EntryControl, prev_proj);
1759 set_idom(outer_loop_head, prev_proj, dom_depth(outer_loop_head));
1760 }
1761 }
1762
1763 //------------------------------do_unroll--------------------------------------
1764 // Unroll the loop body one step - make each trip do 2 iterations.
1765 void PhaseIdealLoop::do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip ) {
1766 assert(LoopUnrollLimit, "");
1767 CountedLoopNode *loop_head = loop->_head->as_CountedLoop();
1768 CountedLoopEndNode *loop_end = loop_head->loopexit();
1769 #ifndef PRODUCT
1770 if (PrintOpto && VerifyLoopOptimizations) {
1771 tty->print("Unrolling ");
1772 loop->dump_head();
1773 } else if (TraceLoopOpts) {
1774 if (loop_head->trip_count() < (uint)LoopUnrollLimit) {
1775 tty->print("Unroll %d(%2d) ", loop_head->unrolled_count()*2, loop_head->trip_count());
1776 } else {
1777 tty->print("Unroll %d ", loop_head->unrolled_count()*2);
1778 }
1779 loop->dump_head();
1780 }
1781
1782 if (C->do_vector_loop() && (PrintOpto && (VerifyLoopOptimizations || TraceLoopOpts))) {
1783 Arena* arena = Thread::current()->resource_area();
1784 Node_Stack stack(arena, C->live_nodes() >> 2);
1785 Node_List rpo_list;
1786 VectorSet visited(arena);
1787 visited.set(loop_head->_idx);
1788 rpo( loop_head, stack, visited, rpo_list );
1789 dump(loop, rpo_list.size(), rpo_list );
1790 }
1791 #endif
1792
1793 // Remember loop node count before unrolling to detect
1794 // if rounds of unroll,optimize are making progress
1795 loop_head->set_node_count_before_unroll(loop->_body.size());
1796
1797 Node *ctrl = loop_head->skip_strip_mined()->in(LoopNode::EntryControl);
1798 Node *limit = loop_head->limit();
1799 Node *init = loop_head->init_trip();
1800 Node *stride = loop_head->stride();
1801
1802 Node *opaq = NULL;
1803 if (adjust_min_trip) { // If not maximally unrolling, need adjustment
1804 // Search for zero-trip guard.
1805
1806 // Check the shape of the graph at the loop entry. If an inappropriate
1807 // graph shape is encountered, the compiler bails out loop unrolling;
1808 // compilation of the method will still succeed.
1809 if (!is_canonical_loop_entry(loop_head)) {
1810 return;
1811 }
1812 opaq = loop_head->skip_predicates()->in(0)->in(1)->in(1)->in(2);
1813 // Zero-trip test uses an 'opaque' node which is not shared.
1814 assert(opaq->outcnt() == 1 && opaq->in(1) == limit, "");
1815 }
1816
1817 C->set_major_progress();
1818
1819 Node* new_limit = NULL;
1820 int stride_con = stride->get_int();
1821 int stride_p = (stride_con > 0) ? stride_con : -stride_con;
1822 uint old_trip_count = loop_head->trip_count();
1823 // Verify that unroll policy result is still valid.
1824 assert(old_trip_count > 1 &&
1825 (!adjust_min_trip || stride_p <= (1<<3)*loop_head->unrolled_count()), "sanity");
1826
1827 update_main_loop_skeleton_predicates(ctrl, loop_head, init, stride_con);
1828
1829 // Adjust loop limit to keep valid iterations number after unroll.
1830 // Use (limit - stride) instead of (((limit - init)/stride) & (-2))*stride
1831 // which may overflow.
1832 if (!adjust_min_trip) {
1833 assert(old_trip_count > 1 && (old_trip_count & 1) == 0,
1834 "odd trip count for maximally unroll");
1835 // Don't need to adjust limit for maximally unroll since trip count is even.
1836 } else if (loop_head->has_exact_trip_count() && init->is_Con()) {
1837 // Loop's limit is constant. Loop's init could be constant when pre-loop
1838 // become peeled iteration.
1839 jlong init_con = init->get_int();
1840 // We can keep old loop limit if iterations count stays the same:
1841 // old_trip_count == new_trip_count * 2
1842 // Note: since old_trip_count >= 2 then new_trip_count >= 1
1843 // so we also don't need to adjust zero trip test.
1844 jlong limit_con = limit->get_int();
1845 // (stride_con*2) not overflow since stride_con <= 8.
1846 int new_stride_con = stride_con * 2;
1847 int stride_m = new_stride_con - (stride_con > 0 ? 1 : -1);
1848 jlong trip_count = (limit_con - init_con + stride_m)/new_stride_con;
1849 // New trip count should satisfy next conditions.
1850 assert(trip_count > 0 && (julong)trip_count < (julong)max_juint/2, "sanity");
1851 uint new_trip_count = (uint)trip_count;
1852 adjust_min_trip = (old_trip_count != new_trip_count*2);
1853 }
1854
1855 if (adjust_min_trip) {
1856 // Step 2: Adjust the trip limit if it is called for.
1857 // The adjustment amount is -stride. Need to make sure if the
1858 // adjustment underflows or overflows, then the main loop is skipped.
1859 Node* cmp = loop_end->cmp_node();
1860 assert(cmp->in(2) == limit, "sanity");
1861 assert(opaq != NULL && opaq->in(1) == limit, "sanity");
1862
1863 // Verify that policy_unroll result is still valid.
1864 const TypeInt* limit_type = _igvn.type(limit)->is_int();
1865 assert(stride_con > 0 && ((limit_type->_hi - stride_con) < limit_type->_hi) ||
1866 stride_con < 0 && ((limit_type->_lo - stride_con) > limit_type->_lo), "sanity");
1867
1868 if (limit->is_Con()) {
1869 // The check in policy_unroll and the assert above guarantee
1870 // no underflow if limit is constant.
1871 new_limit = _igvn.intcon(limit->get_int() - stride_con);
1872 set_ctrl(new_limit, C->root());
1873 } else {
1874 // Limit is not constant.
1875 if (loop_head->unrolled_count() == 1) { // only for first unroll
1876 // Separate limit by Opaque node in case it is an incremented
1877 // variable from previous loop to avoid using pre-incremented
1878 // value which could increase register pressure.
1879 // Otherwise reorg_offsets() optimization will create a separate
1880 // Opaque node for each use of trip-counter and as result
1881 // zero trip guard limit will be different from loop limit.
1882 assert(has_ctrl(opaq), "should have it");
1883 Node* opaq_ctrl = get_ctrl(opaq);
1884 limit = new Opaque2Node( C, limit );
1885 register_new_node( limit, opaq_ctrl );
1886 }
1887 if ((stride_con > 0 && (java_subtract(limit_type->_lo, stride_con) < limit_type->_lo)) ||
1888 (stride_con < 0 && (java_subtract(limit_type->_hi, stride_con) > limit_type->_hi))) {
1889 // No underflow.
1890 new_limit = new SubINode(limit, stride);
1891 } else {
1892 // (limit - stride) may underflow.
1893 // Clamp the adjustment value with MININT or MAXINT:
1894 //
1895 // new_limit = limit-stride
1896 // if (stride > 0)
1897 // new_limit = (limit < new_limit) ? MININT : new_limit;
1898 // else
1899 // new_limit = (limit > new_limit) ? MAXINT : new_limit;
1900 //
1901 BoolTest::mask bt = loop_end->test_trip();
1902 assert(bt == BoolTest::lt || bt == BoolTest::gt, "canonical test is expected");
1903 Node* adj_max = _igvn.intcon((stride_con > 0) ? min_jint : max_jint);
1904 set_ctrl(adj_max, C->root());
1905 Node* old_limit = NULL;
1906 Node* adj_limit = NULL;
1907 Node* bol = limit->is_CMove() ? limit->in(CMoveNode::Condition) : NULL;
1908 if (loop_head->unrolled_count() > 1 &&
1909 limit->is_CMove() && limit->Opcode() == Op_CMoveI &&
1910 limit->in(CMoveNode::IfTrue) == adj_max &&
1911 bol->as_Bool()->_test._test == bt &&
1912 bol->in(1)->Opcode() == Op_CmpI &&
1913 bol->in(1)->in(2) == limit->in(CMoveNode::IfFalse)) {
1914 // Loop was unrolled before.
1915 // Optimize the limit to avoid nested CMove:
1916 // use original limit as old limit.
1917 old_limit = bol->in(1)->in(1);
1918 // Adjust previous adjusted limit.
1919 adj_limit = limit->in(CMoveNode::IfFalse);
1920 adj_limit = new SubINode(adj_limit, stride);
1921 } else {
1922 old_limit = limit;
1923 adj_limit = new SubINode(limit, stride);
1924 }
1925 assert(old_limit != NULL && adj_limit != NULL, "");
1926 register_new_node( adj_limit, ctrl ); // adjust amount
1927 Node* adj_cmp = new CmpINode(old_limit, adj_limit);
1928 register_new_node( adj_cmp, ctrl );
1929 Node* adj_bool = new BoolNode(adj_cmp, bt);
1930 register_new_node( adj_bool, ctrl );
1931 new_limit = new CMoveINode(adj_bool, adj_limit, adj_max, TypeInt::INT);
1932 }
1933 register_new_node(new_limit, ctrl);
1934 }
1935 assert(new_limit != NULL, "");
1936 // Replace in loop test.
1937 assert(loop_end->in(1)->in(1) == cmp, "sanity");
1938 if (cmp->outcnt() == 1 && loop_end->in(1)->outcnt() == 1) {
1939 // Don't need to create new test since only one user.
1940 _igvn.hash_delete(cmp);
1941 cmp->set_req(2, new_limit);
1942 } else {
1943 // Create new test since it is shared.
1944 Node* ctrl2 = loop_end->in(0);
1945 Node* cmp2 = cmp->clone();
1946 cmp2->set_req(2, new_limit);
1947 register_new_node(cmp2, ctrl2);
1948 Node* bol2 = loop_end->in(1)->clone();
1949 bol2->set_req(1, cmp2);
1950 register_new_node(bol2, ctrl2);
1951 _igvn.replace_input_of(loop_end, 1, bol2);
1952 }
1953 // Step 3: Find the min-trip test guaranteed before a 'main' loop.
1954 // Make it a 1-trip test (means at least 2 trips).
1955
1956 // Guard test uses an 'opaque' node which is not shared. Hence I
1957 // can edit it's inputs directly. Hammer in the new limit for the
1958 // minimum-trip guard.
1959 assert(opaq->outcnt() == 1, "");
1960 _igvn.replace_input_of(opaq, 1, new_limit);
1961 }
1962
1963 // Adjust max trip count. The trip count is intentionally rounded
1964 // down here (e.g. 15-> 7-> 3-> 1) because if we unwittingly over-unroll,
1965 // the main, unrolled, part of the loop will never execute as it is protected
1966 // by the min-trip test. See bug 4834191 for a case where we over-unrolled
1967 // and later determined that part of the unrolled loop was dead.
1968 loop_head->set_trip_count(old_trip_count / 2);
1969
1970 // Double the count of original iterations in the unrolled loop body.
1971 loop_head->double_unrolled_count();
1972
1973 // ---------
1974 // Step 4: Clone the loop body. Move it inside the loop. This loop body
1975 // represents the odd iterations; since the loop trips an even number of
1976 // times its backedge is never taken. Kill the backedge.
1977 uint dd = dom_depth(loop_head);
1978 clone_loop(loop, old_new, dd, IgnoreStripMined);
1979
1980 // Make backedges of the clone equal to backedges of the original.
1981 // Make the fall-in from the original come from the fall-out of the clone.
1982 for (DUIterator_Fast jmax, j = loop_head->fast_outs(jmax); j < jmax; j++) {
1983 Node* phi = loop_head->fast_out(j);
1984 if( phi->is_Phi() && phi->in(0) == loop_head && phi->outcnt() > 0 ) {
1985 Node *newphi = old_new[phi->_idx];
1986 _igvn.hash_delete( phi );
1987 _igvn.hash_delete( newphi );
1988
1989 phi ->set_req(LoopNode:: EntryControl, newphi->in(LoopNode::LoopBackControl));
1990 newphi->set_req(LoopNode::LoopBackControl, phi ->in(LoopNode::LoopBackControl));
1991 phi ->set_req(LoopNode::LoopBackControl, C->top());
1992 }
1993 }
1994 Node *clone_head = old_new[loop_head->_idx];
1995 _igvn.hash_delete( clone_head );
1996 loop_head ->set_req(LoopNode:: EntryControl, clone_head->in(LoopNode::LoopBackControl));
1997 clone_head->set_req(LoopNode::LoopBackControl, loop_head ->in(LoopNode::LoopBackControl));
1998 loop_head ->set_req(LoopNode::LoopBackControl, C->top());
1999 loop->_head = clone_head; // New loop header
2000
2001 set_idom(loop_head, loop_head ->in(LoopNode::EntryControl), dd);
2002 set_idom(clone_head, clone_head->in(LoopNode::EntryControl), dd);
2003
2004 // Kill the clone's backedge
2005 Node *newcle = old_new[loop_end->_idx];
2006 _igvn.hash_delete( newcle );
2007 Node *one = _igvn.intcon(1);
2008 set_ctrl(one, C->root());
2009 newcle->set_req(1, one);
2010 // Force clone into same loop body
2011 uint max = loop->_body.size();
2012 for( uint k = 0; k < max; k++ ) {
2013 Node *old = loop->_body.at(k);
2014 Node *nnn = old_new[old->_idx];
2015 loop->_body.push(nnn);
2016 if (!has_ctrl(old))
2017 set_loop(nnn, loop);
2018 }
2019
2020 loop->record_for_igvn();
2021 loop_head->clear_strip_mined();
2022
2023 #ifndef PRODUCT
2024 if (C->do_vector_loop() && (PrintOpto && (VerifyLoopOptimizations || TraceLoopOpts))) {
2025 tty->print("\nnew loop after unroll\n"); loop->dump_head();
2026 for (uint i = 0; i < loop->_body.size(); i++) {
2027 loop->_body.at(i)->dump();
2028 }
2029 if(C->clone_map().is_debug()) {
2030 tty->print("\nCloneMap\n");
2031 Dict* dict = C->clone_map().dict();
2032 DictI i(dict);
2033 tty->print_cr("Dict@%p[%d] = ", dict, dict->Size());
2034 for (int ii = 0; i.test(); ++i, ++ii) {
2035 NodeCloneInfo cl((uint64_t)dict->operator[]((void*)i._key));
2036 tty->print("%d->%d:%d,", (int)(intptr_t)i._key, cl.idx(), cl.gen());
2037 if (ii % 10 == 9) {
2038 tty->print_cr(" ");
2039 }
2040 }
2041 tty->print_cr(" ");
2042 }
2043 }
2044 #endif
2045
2046 }
2047
2048 //------------------------------do_maximally_unroll----------------------------
2049
2050 void PhaseIdealLoop::do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new ) {
2051 CountedLoopNode *cl = loop->_head->as_CountedLoop();
2052 assert(cl->has_exact_trip_count(), "trip count is not exact");
2053 assert(cl->trip_count() > 0, "");
2054 #ifndef PRODUCT
2055 if (TraceLoopOpts) {
2056 tty->print("MaxUnroll %d ", cl->trip_count());
2057 loop->dump_head();
2058 }
2059 #endif
2060
2061 // If loop is tripping an odd number of times, peel odd iteration
2062 if ((cl->trip_count() & 1) == 1) {
2063 do_peeling(loop, old_new);
2064 }
2065
2066 // Now its tripping an even number of times remaining. Double loop body.
2067 // Do not adjust pre-guards; they are not needed and do not exist.
2068 if (cl->trip_count() > 0) {
2069 assert((cl->trip_count() & 1) == 0, "missed peeling");
2070 do_unroll(loop, old_new, false);
2071 }
2072 }
2073
2074 void PhaseIdealLoop::mark_reductions(IdealLoopTree *loop) {
2075 if (SuperWordReductions == false) return;
2076
2077 CountedLoopNode* loop_head = loop->_head->as_CountedLoop();
2078 if (loop_head->unrolled_count() > 1) {
2079 return;
2080 }
2081
2082 Node* trip_phi = loop_head->phi();
2083 for (DUIterator_Fast imax, i = loop_head->fast_outs(imax); i < imax; i++) {
2084 Node* phi = loop_head->fast_out(i);
2085 if (phi->is_Phi() && phi->outcnt() > 0 && phi != trip_phi) {
2086 // For definitions which are loop inclusive and not tripcounts.
2087 Node* def_node = phi->in(LoopNode::LoopBackControl);
2088
2089 if (def_node != NULL) {
2090 Node* n_ctrl = get_ctrl(def_node);
2091 if (n_ctrl != NULL && loop->is_member(get_loop(n_ctrl))) {
2092 // Now test it to see if it fits the standard pattern for a reduction operator.
2093 int opc = def_node->Opcode();
2094 if (opc != ReductionNode::opcode(opc, def_node->bottom_type()->basic_type())) {
2095 if (!def_node->is_reduction()) { // Not marked yet
2096 // To be a reduction, the arithmetic node must have the phi as input and provide a def to it
2097 bool ok = false;
2098 for (unsigned j = 1; j < def_node->req(); j++) {
2099 Node* in = def_node->in(j);
2100 if (in == phi) {
2101 ok = true;
2102 break;
2103 }
2104 }
2105
2106 // do nothing if we did not match the initial criteria
2107 if (ok == false) {
2108 continue;
2109 }
2110
2111 // The result of the reduction must not be used in the loop
2112 for (DUIterator_Fast imax, i = def_node->fast_outs(imax); i < imax && ok; i++) {
2113 Node* u = def_node->fast_out(i);
2114 if (!loop->is_member(get_loop(ctrl_or_self(u)))) {
2115 continue;
2116 }
2117 if (u == phi) {
2118 continue;
2119 }
2120 ok = false;
2121 }
2122
2123 // iff the uses conform
2124 if (ok) {
2125 def_node->add_flag(Node::Flag_is_reduction);
2126 loop_head->mark_has_reductions();
2127 }
2128 }
2129 }
2130 }
2131 }
2132 }
2133 }
2134 }
2135
2136 //------------------------------adjust_limit-----------------------------------
2137 // Helper function for add_constraint().
2138 Node* PhaseIdealLoop::adjust_limit(int stride_con, Node * scale, Node *offset, Node *rc_limit, Node *loop_limit, Node *pre_ctrl, bool round_up) {
2139 // Compute "I :: (limit-offset)/scale"
2140 Node *con = new SubINode(rc_limit, offset);
2141 register_new_node(con, pre_ctrl);
2142 Node *X = new DivINode(0, con, scale);
2143 register_new_node(X, pre_ctrl);
2144
2145 // When the absolute value of scale is greater than one, the integer
2146 // division may round limit down so add one to the limit.
2147 if (round_up) {
2148 X = new AddINode(X, _igvn.intcon(1));
2149 register_new_node(X, pre_ctrl);
2150 }
2151
2152 // Adjust loop limit
2153 loop_limit = (stride_con > 0)
2154 ? (Node*)(new MinINode(loop_limit, X))
2155 : (Node*)(new MaxINode(loop_limit, X));
2156 register_new_node(loop_limit, pre_ctrl);
2157 return loop_limit;
2158 }
2159
2160 //------------------------------add_constraint---------------------------------
2161 // Constrain the main loop iterations so the conditions:
2162 // low_limit <= scale_con * I + offset < upper_limit
2163 // always holds true. That is, either increase the number of iterations in
2164 // the pre-loop or the post-loop until the condition holds true in the main
2165 // loop. Stride, scale, offset and limit are all loop invariant. Further,
2166 // stride and scale are constants (offset and limit often are).
2167 void PhaseIdealLoop::add_constraint( int stride_con, int scale_con, Node *offset, Node *low_limit, Node *upper_limit, Node *pre_ctrl, Node **pre_limit, Node **main_limit ) {
2168 // For positive stride, the pre-loop limit always uses a MAX function
2169 // and the main loop a MIN function. For negative stride these are
2170 // reversed.
2171
2172 // Also for positive stride*scale the affine function is increasing, so the
2173 // pre-loop must check for underflow and the post-loop for overflow.
2174 // Negative stride*scale reverses this; pre-loop checks for overflow and
2175 // post-loop for underflow.
2176
2177 Node *scale = _igvn.intcon(scale_con);
2178 set_ctrl(scale, C->root());
2179
2180 if ((stride_con^scale_con) >= 0) { // Use XOR to avoid overflow
2181 // The overflow limit: scale*I+offset < upper_limit
2182 // For main-loop compute
2183 // ( if (scale > 0) /* and stride > 0 */
2184 // I < (upper_limit-offset)/scale
2185 // else /* scale < 0 and stride < 0 */
2186 // I > (upper_limit-offset)/scale
2187 // )
2188 //
2189 // (upper_limit-offset) may overflow or underflow.
2190 // But it is fine since main loop will either have
2191 // less iterations or will be skipped in such case.
2192 *main_limit = adjust_limit(stride_con, scale, offset, upper_limit, *main_limit, pre_ctrl, false);
2193
2194 // The underflow limit: low_limit <= scale*I+offset.
2195 // For pre-loop compute
2196 // NOT(scale*I+offset >= low_limit)
2197 // scale*I+offset < low_limit
2198 // ( if (scale > 0) /* and stride > 0 */
2199 // I < (low_limit-offset)/scale
2200 // else /* scale < 0 and stride < 0 */
2201 // I > (low_limit-offset)/scale
2202 // )
2203
2204 if (low_limit->get_int() == -max_jint) {
2205 // We need this guard when scale*pre_limit+offset >= limit
2206 // due to underflow. So we need execute pre-loop until
2207 // scale*I+offset >= min_int. But (min_int-offset) will
2208 // underflow when offset > 0 and X will be > original_limit
2209 // when stride > 0. To avoid it we replace positive offset with 0.
2210 //
2211 // Also (min_int+1 == -max_int) is used instead of min_int here
2212 // to avoid problem with scale == -1 (min_int/(-1) == min_int).
2213 Node* shift = _igvn.intcon(31);
2214 set_ctrl(shift, C->root());
2215 Node* sign = new RShiftINode(offset, shift);
2216 register_new_node(sign, pre_ctrl);
2217 offset = new AndINode(offset, sign);
2218 register_new_node(offset, pre_ctrl);
2219 } else {
2220 assert(low_limit->get_int() == 0, "wrong low limit for range check");
2221 // The only problem we have here when offset == min_int
2222 // since (0-min_int) == min_int. It may be fine for stride > 0
2223 // but for stride < 0 X will be < original_limit. To avoid it
2224 // max(pre_limit, original_limit) is used in do_range_check().
2225 }
2226 // Pass (-stride) to indicate pre_loop_cond = NOT(main_loop_cond);
2227 *pre_limit = adjust_limit((-stride_con), scale, offset, low_limit, *pre_limit, pre_ctrl,
2228 scale_con > 1 && stride_con > 0);
2229
2230 } else { // stride_con*scale_con < 0
2231 // For negative stride*scale pre-loop checks for overflow and
2232 // post-loop for underflow.
2233 //
2234 // The overflow limit: scale*I+offset < upper_limit
2235 // For pre-loop compute
2236 // NOT(scale*I+offset < upper_limit)
2237 // scale*I+offset >= upper_limit
2238 // scale*I+offset+1 > upper_limit
2239 // ( if (scale < 0) /* and stride > 0 */
2240 // I < (upper_limit-(offset+1))/scale
2241 // else /* scale > 0 and stride < 0 */
2242 // I > (upper_limit-(offset+1))/scale
2243 // )
2244 //
2245 // (upper_limit-offset-1) may underflow or overflow.
2246 // To avoid it min(pre_limit, original_limit) is used
2247 // in do_range_check() for stride > 0 and max() for < 0.
2248 Node *one = _igvn.intcon(1);
2249 set_ctrl(one, C->root());
2250
2251 Node *plus_one = new AddINode(offset, one);
2252 register_new_node( plus_one, pre_ctrl );
2253 // Pass (-stride) to indicate pre_loop_cond = NOT(main_loop_cond);
2254 *pre_limit = adjust_limit((-stride_con), scale, plus_one, upper_limit, *pre_limit, pre_ctrl,
2255 scale_con < -1 && stride_con > 0);
2256
2257 if (low_limit->get_int() == -max_jint) {
2258 // We need this guard when scale*main_limit+offset >= limit
2259 // due to underflow. So we need execute main-loop while
2260 // scale*I+offset+1 > min_int. But (min_int-offset-1) will
2261 // underflow when (offset+1) > 0 and X will be < main_limit
2262 // when scale < 0 (and stride > 0). To avoid it we replace
2263 // positive (offset+1) with 0.
2264 //
2265 // Also (min_int+1 == -max_int) is used instead of min_int here
2266 // to avoid problem with scale == -1 (min_int/(-1) == min_int).
2267 Node* shift = _igvn.intcon(31);
2268 set_ctrl(shift, C->root());
2269 Node* sign = new RShiftINode(plus_one, shift);
2270 register_new_node(sign, pre_ctrl);
2271 plus_one = new AndINode(plus_one, sign);
2272 register_new_node(plus_one, pre_ctrl);
2273 } else {
2274 assert(low_limit->get_int() == 0, "wrong low limit for range check");
2275 // The only problem we have here when offset == max_int
2276 // since (max_int+1) == min_int and (0-min_int) == min_int.
2277 // But it is fine since main loop will either have
2278 // less iterations or will be skipped in such case.
2279 }
2280 // The underflow limit: low_limit <= scale*I+offset.
2281 // For main-loop compute
2282 // scale*I+offset+1 > low_limit
2283 // ( if (scale < 0) /* and stride > 0 */
2284 // I < (low_limit-(offset+1))/scale
2285 // else /* scale > 0 and stride < 0 */
2286 // I > (low_limit-(offset+1))/scale
2287 // )
2288
2289 *main_limit = adjust_limit(stride_con, scale, plus_one, low_limit, *main_limit, pre_ctrl,
2290 false);
2291 }
2292 }
2293
2294
2295 //------------------------------is_scaled_iv---------------------------------
2296 // Return true if exp is a constant times an induction var
2297 bool PhaseIdealLoop::is_scaled_iv(Node* exp, Node* iv, int* p_scale) {
2298 if (exp == iv) {
2299 if (p_scale != NULL) {
2300 *p_scale = 1;
2301 }
2302 return true;
2303 }
2304 int opc = exp->Opcode();
2305 if (opc == Op_MulI) {
2306 if (exp->in(1) == iv && exp->in(2)->is_Con()) {
2307 if (p_scale != NULL) {
2308 *p_scale = exp->in(2)->get_int();
2309 }
2310 return true;
2311 }
2312 if (exp->in(2) == iv && exp->in(1)->is_Con()) {
2313 if (p_scale != NULL) {
2314 *p_scale = exp->in(1)->get_int();
2315 }
2316 return true;
2317 }
2318 } else if (opc == Op_LShiftI) {
2319 if (exp->in(1) == iv && exp->in(2)->is_Con()) {
2320 if (p_scale != NULL) {
2321 *p_scale = 1 << exp->in(2)->get_int();
2322 }
2323 return true;
2324 }
2325 }
2326 return false;
2327 }
2328
2329 //-----------------------------is_scaled_iv_plus_offset------------------------------
2330 // Return true if exp is a simple induction variable expression: k1*iv + (invar + k2)
2331 bool PhaseIdealLoop::is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth) {
2332 if (is_scaled_iv(exp, iv, p_scale)) {
2333 if (p_offset != NULL) {
2334 Node *zero = _igvn.intcon(0);
2335 set_ctrl(zero, C->root());
2336 *p_offset = zero;
2337 }
2338 return true;
2339 }
2340 int opc = exp->Opcode();
2341 if (opc == Op_AddI) {
2342 if (is_scaled_iv(exp->in(1), iv, p_scale)) {
2343 if (p_offset != NULL) {
2344 *p_offset = exp->in(2);
2345 }
2346 return true;
2347 }
2348 if (is_scaled_iv(exp->in(2), iv, p_scale)) {
2349 if (p_offset != NULL) {
2350 *p_offset = exp->in(1);
2351 }
2352 return true;
2353 }
2354 if (exp->in(2)->is_Con()) {
2355 Node* offset2 = NULL;
2356 if (depth < 2 &&
2357 is_scaled_iv_plus_offset(exp->in(1), iv, p_scale,
2358 p_offset != NULL ? &offset2 : NULL, depth+1)) {
2359 if (p_offset != NULL) {
2360 Node *ctrl_off2 = get_ctrl(offset2);
2361 Node* offset = new AddINode(offset2, exp->in(2));
2362 register_new_node(offset, ctrl_off2);
2363 *p_offset = offset;
2364 }
2365 return true;
2366 }
2367 }
2368 } else if (opc == Op_SubI) {
2369 if (is_scaled_iv(exp->in(1), iv, p_scale)) {
2370 if (p_offset != NULL) {
2371 Node *zero = _igvn.intcon(0);
2372 set_ctrl(zero, C->root());
2373 Node *ctrl_off = get_ctrl(exp->in(2));
2374 Node* offset = new SubINode(zero, exp->in(2));
2375 register_new_node(offset, ctrl_off);
2376 *p_offset = offset;
2377 }
2378 return true;
2379 }
2380 if (is_scaled_iv(exp->in(2), iv, p_scale)) {
2381 if (p_offset != NULL) {
2382 *p_scale *= -1;
2383 *p_offset = exp->in(1);
2384 }
2385 return true;
2386 }
2387 }
2388 return false;
2389 }
2390
2391 // Same as PhaseIdealLoop::duplicate_predicates() but for range checks
2392 // eliminated by iteration splitting.
2393 Node* PhaseIdealLoop::add_range_check_predicate(IdealLoopTree* loop, CountedLoopNode* cl,
2394 Node* predicate_proj, int scale_con, Node* offset,
2395 Node* limit, jint stride_con, Node* value) {
2396 bool overflow = false;
2397 BoolNode* bol = rc_predicate(loop, predicate_proj, scale_con, offset, value, NULL, stride_con, limit, (stride_con > 0) != (scale_con > 0), overflow);
2398 Node* opaque_bol = new Opaque4Node(C, bol, _igvn.intcon(1));
2399 register_new_node(opaque_bol, predicate_proj);
2400 IfNode* new_iff = NULL;
2401 if (overflow) {
2402 new_iff = new IfNode(predicate_proj, opaque_bol, PROB_MAX, COUNT_UNKNOWN);
2403 } else {
2404 new_iff = new RangeCheckNode(predicate_proj, opaque_bol, PROB_MAX, COUNT_UNKNOWN);
2405 }
2406 register_control(new_iff, loop->_parent, predicate_proj);
2407 Node* iffalse = new IfFalseNode(new_iff);
2408 register_control(iffalse, _ltree_root, new_iff);
2409 ProjNode* iftrue = new IfTrueNode(new_iff);
2410 register_control(iftrue, loop->_parent, new_iff);
2411 Node *frame = new ParmNode(C->start(), TypeFunc::FramePtr);
2412 register_new_node(frame, C->start());
2413 Node* halt = new HaltNode(iffalse, frame, "range check predicate failed which is impossible");
2414 register_control(halt, _ltree_root, iffalse);
2415 C->root()->add_req(halt);
2416 return iftrue;
2417 }
2418
2419 //------------------------------do_range_check---------------------------------
2420 // Eliminate range-checks and other trip-counter vs loop-invariant tests.
2421 int PhaseIdealLoop::do_range_check( IdealLoopTree *loop, Node_List &old_new ) {
2422 #ifndef PRODUCT
2423 if (PrintOpto && VerifyLoopOptimizations) {
2424 tty->print("Range Check Elimination ");
2425 loop->dump_head();
2426 } else if (TraceLoopOpts) {
2427 tty->print("RangeCheck ");
2428 loop->dump_head();
2429 }
2430 #endif
2431 assert(RangeCheckElimination, "");
2432 CountedLoopNode *cl = loop->_head->as_CountedLoop();
2433 // If we fail before trying to eliminate range checks, set multiversion state
2434 int closed_range_checks = 1;
2435
2436 // protect against stride not being a constant
2437 if (!cl->stride_is_con())
2438 return closed_range_checks;
2439
2440 // Find the trip counter; we are iteration splitting based on it
2441 Node *trip_counter = cl->phi();
2442 // Find the main loop limit; we will trim it's iterations
2443 // to not ever trip end tests
2444 Node *main_limit = cl->limit();
2445
2446 // Check graph shape. Cannot optimize a loop if zero-trip
2447 // Opaque1 node is optimized away and then another round
2448 // of loop opts attempted.
2449 if (!is_canonical_loop_entry(cl)) {
2450 return closed_range_checks;
2451 }
2452
2453 // Need to find the main-loop zero-trip guard
2454 Node *ctrl = cl->skip_predicates();
2455 Node *iffm = ctrl->in(0);
2456 Node *opqzm = iffm->in(1)->in(1)->in(2);
2457 assert(opqzm->in(1) == main_limit, "do not understand situation");
2458
2459 // Find the pre-loop limit; we will expand its iterations to
2460 // not ever trip low tests.
2461 Node *p_f = iffm->in(0);
2462 // pre loop may have been optimized out
2463 if (p_f->Opcode() != Op_IfFalse) {
2464 return closed_range_checks;
2465 }
2466 CountedLoopEndNode *pre_end = p_f->in(0)->as_CountedLoopEnd();
2467 assert(pre_end->loopnode()->is_pre_loop(), "");
2468 Node *pre_opaq1 = pre_end->limit();
2469 // Occasionally it's possible for a pre-loop Opaque1 node to be
2470 // optimized away and then another round of loop opts attempted.
2471 // We can not optimize this particular loop in that case.
2472 if (pre_opaq1->Opcode() != Op_Opaque1)
2473 return closed_range_checks;
2474 Opaque1Node *pre_opaq = (Opaque1Node*)pre_opaq1;
2475 Node *pre_limit = pre_opaq->in(1);
2476
2477 // Where do we put new limit calculations
2478 Node *pre_ctrl = pre_end->loopnode()->in(LoopNode::EntryControl);
2479
2480 // Ensure the original loop limit is available from the
2481 // pre-loop Opaque1 node.
2482 Node *orig_limit = pre_opaq->original_loop_limit();
2483 if (orig_limit == NULL || _igvn.type(orig_limit) == Type::TOP)
2484 return closed_range_checks;
2485
2486 // Must know if its a count-up or count-down loop
2487
2488 int stride_con = cl->stride_con();
2489 Node *zero = _igvn.intcon(0);
2490 Node *one = _igvn.intcon(1);
2491 // Use symmetrical int range [-max_jint,max_jint]
2492 Node *mini = _igvn.intcon(-max_jint);
2493 set_ctrl(zero, C->root());
2494 set_ctrl(one, C->root());
2495 set_ctrl(mini, C->root());
2496
2497 // Range checks that do not dominate the loop backedge (ie.
2498 // conditionally executed) can lengthen the pre loop limit beyond
2499 // the original loop limit. To prevent this, the pre limit is
2500 // (for stride > 0) MINed with the original loop limit (MAXed
2501 // stride < 0) when some range_check (rc) is conditionally
2502 // executed.
2503 bool conditional_rc = false;
2504
2505 // Count number of range checks and reduce by load range limits, if zero,
2506 // the loop is in canonical form to multiversion.
2507 closed_range_checks = 0;
2508
2509 Node* predicate_proj = cl->skip_strip_mined()->in(LoopNode::EntryControl);
2510 assert(predicate_proj->is_Proj() && predicate_proj->in(0)->is_If(), "if projection only");
2511 // Check loop body for tests of trip-counter plus loop-invariant vs loop-variant.
2512 for( uint i = 0; i < loop->_body.size(); i++ ) {
2513 Node *iff = loop->_body[i];
2514 if (iff->Opcode() == Op_If ||
2515 iff->Opcode() == Op_RangeCheck) { // Test?
2516 // Test is an IfNode, has 2 projections. If BOTH are in the loop
2517 // we need loop unswitching instead of iteration splitting.
2518 closed_range_checks++;
2519 Node *exit = loop->is_loop_exit(iff);
2520 if( !exit ) continue;
2521 int flip = (exit->Opcode() == Op_IfTrue) ? 1 : 0;
2522
2523 // Get boolean condition to test
2524 Node *i1 = iff->in(1);
2525 if( !i1->is_Bool() ) continue;
2526 BoolNode *bol = i1->as_Bool();
2527 BoolTest b_test = bol->_test;
2528 // Flip sense of test if exit condition is flipped
2529 if( flip )
2530 b_test = b_test.negate();
2531
2532 // Get compare
2533 Node *cmp = bol->in(1);
2534
2535 // Look for trip_counter + offset vs limit
2536 Node *rc_exp = cmp->in(1);
2537 Node *limit = cmp->in(2);
2538 int scale_con= 1; // Assume trip counter not scaled
2539
2540 Node *limit_c = get_ctrl(limit);
2541 if( loop->is_member(get_loop(limit_c) ) ) {
2542 // Compare might have operands swapped; commute them
2543 b_test = b_test.commute();
2544 rc_exp = cmp->in(2);
2545 limit = cmp->in(1);
2546 limit_c = get_ctrl(limit);
2547 if( loop->is_member(get_loop(limit_c) ) )
2548 continue; // Both inputs are loop varying; cannot RCE
2549 }
2550 // Here we know 'limit' is loop invariant
2551
2552 // 'limit' maybe pinned below the zero trip test (probably from a
2553 // previous round of rce), in which case, it can't be used in the
2554 // zero trip test expression which must occur before the zero test's if.
2555 if (is_dominator(ctrl, limit_c)) {
2556 continue; // Don't rce this check but continue looking for other candidates.
2557 }
2558
2559 // Check for scaled induction variable plus an offset
2560 Node *offset = NULL;
2561
2562 if (!is_scaled_iv_plus_offset(rc_exp, trip_counter, &scale_con, &offset)) {
2563 continue;
2564 }
2565
2566 Node *offset_c = get_ctrl(offset);
2567 if( loop->is_member( get_loop(offset_c) ) )
2568 continue; // Offset is not really loop invariant
2569 // Here we know 'offset' is loop invariant.
2570
2571 // As above for the 'limit', the 'offset' maybe pinned below the
2572 // zero trip test.
2573 if (is_dominator(ctrl, offset_c)) {
2574 continue; // Don't rce this check but continue looking for other candidates.
2575 }
2576 #ifdef ASSERT
2577 if (TraceRangeLimitCheck) {
2578 tty->print_cr("RC bool node%s", flip ? " flipped:" : ":");
2579 bol->dump(2);
2580 }
2581 #endif
2582 // At this point we have the expression as:
2583 // scale_con * trip_counter + offset :: limit
2584 // where scale_con, offset and limit are loop invariant. Trip_counter
2585 // monotonically increases by stride_con, a constant. Both (or either)
2586 // stride_con and scale_con can be negative which will flip about the
2587 // sense of the test.
2588
2589 // Adjust pre and main loop limits to guard the correct iteration set
2590 if( cmp->Opcode() == Op_CmpU ) {// Unsigned compare is really 2 tests
2591 if( b_test._test == BoolTest::lt ) { // Range checks always use lt
2592 // The underflow and overflow limits: 0 <= scale*I+offset < limit
2593 add_constraint( stride_con, scale_con, offset, zero, limit, pre_ctrl, &pre_limit, &main_limit );
2594 // (0-offset)/scale could be outside of loop iterations range.
2595 conditional_rc = true;
2596 Node* init = cl->init_trip();
2597 Node* opaque_init = new Opaque1Node(C, init);
2598 register_new_node(opaque_init, predicate_proj);
2599 // template predicate so it can be updated on next unrolling
2600 predicate_proj = add_range_check_predicate(loop, cl, predicate_proj, scale_con, offset, limit, stride_con, opaque_init);
2601 assert(skeleton_predicate_has_opaque(predicate_proj->in(0)->as_If()), "unexpected");
2602 // predicate on first value of first iteration
2603 predicate_proj = add_range_check_predicate(loop, cl, predicate_proj, scale_con, offset, limit, stride_con, init);
2604 assert(!skeleton_predicate_has_opaque(predicate_proj->in(0)->as_If()), "unexpected");
2605 int init_inc = stride_con/cl->unrolled_count();
2606 assert(init_inc != 0, "invalid loop increment");
2607 Node* max_value = _igvn.intcon(stride_con - init_inc);
2608 max_value = new AddINode(init, max_value);
2609 register_new_node(max_value, predicate_proj);
2610 // predicate on last value of first iteration (in case unrolling has already happened)
2611 predicate_proj = add_range_check_predicate(loop, cl, predicate_proj, scale_con, offset, limit, stride_con, max_value);
2612 assert(!skeleton_predicate_has_opaque(predicate_proj->in(0)->as_If()), "unexpected");
2613 } else {
2614 if (PrintOpto) {
2615 tty->print_cr("missed RCE opportunity");
2616 }
2617 continue; // In release mode, ignore it
2618 }
2619 } else { // Otherwise work on normal compares
2620 switch( b_test._test ) {
2621 case BoolTest::gt:
2622 // Fall into GE case
2623 case BoolTest::ge:
2624 // Convert (I*scale+offset) >= Limit to (I*(-scale)+(-offset)) <= -Limit
2625 scale_con = -scale_con;
2626 offset = new SubINode( zero, offset );
2627 register_new_node( offset, pre_ctrl );
2628 limit = new SubINode( zero, limit );
2629 register_new_node( limit, pre_ctrl );
2630 // Fall into LE case
2631 case BoolTest::le:
2632 if (b_test._test != BoolTest::gt) {
2633 // Convert X <= Y to X < Y+1
2634 limit = new AddINode( limit, one );
2635 register_new_node( limit, pre_ctrl );
2636 }
2637 // Fall into LT case
2638 case BoolTest::lt:
2639 // The underflow and overflow limits: MIN_INT <= scale*I+offset < limit
2640 // Note: (MIN_INT+1 == -MAX_INT) is used instead of MIN_INT here
2641 // to avoid problem with scale == -1: MIN_INT/(-1) == MIN_INT.
2642 add_constraint( stride_con, scale_con, offset, mini, limit, pre_ctrl, &pre_limit, &main_limit );
2643 // ((MIN_INT+1)-offset)/scale could be outside of loop iterations range.
2644 // Note: negative offset is replaced with 0 but (MIN_INT+1)/scale could
2645 // still be outside of loop range.
2646 conditional_rc = true;
2647 break;
2648 default:
2649 if (PrintOpto) {
2650 tty->print_cr("missed RCE opportunity");
2651 }
2652 continue; // Unhandled case
2653 }
2654 }
2655
2656 // Kill the eliminated test
2657 C->set_major_progress();
2658 Node *kill_con = _igvn.intcon( 1-flip );
2659 set_ctrl(kill_con, C->root());
2660 _igvn.replace_input_of(iff, 1, kill_con);
2661 // Find surviving projection
2662 assert(iff->is_If(), "");
2663 ProjNode* dp = ((IfNode*)iff)->proj_out(1-flip);
2664 // Find loads off the surviving projection; remove their control edge
2665 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
2666 Node* cd = dp->fast_out(i); // Control-dependent node
2667 if (cd->is_Load() && cd->depends_only_on_test()) { // Loads can now float around in the loop
2668 // Allow the load to float around in the loop, or before it
2669 // but NOT before the pre-loop.
2670 _igvn.replace_input_of(cd, 0, ctrl); // ctrl, not NULL
2671 --i;
2672 --imax;
2673 }
2674 }
2675 if (limit->Opcode() == Op_LoadRange) {
2676 closed_range_checks--;
2677 }
2678
2679 } // End of is IF
2680
2681 }
2682 if (predicate_proj != cl->skip_strip_mined()->in(LoopNode::EntryControl)) {
2683 _igvn.replace_input_of(cl->skip_strip_mined(), LoopNode::EntryControl, predicate_proj);
2684 set_idom(cl->skip_strip_mined(), predicate_proj, dom_depth(cl->skip_strip_mined()));
2685 }
2686
2687 // Update loop limits
2688 if (conditional_rc) {
2689 pre_limit = (stride_con > 0) ? (Node*)new MinINode(pre_limit, orig_limit)
2690 : (Node*)new MaxINode(pre_limit, orig_limit);
2691 register_new_node(pre_limit, pre_ctrl);
2692 }
2693 _igvn.replace_input_of(pre_opaq, 1, pre_limit);
2694
2695 // Note:: we are making the main loop limit no longer precise;
2696 // need to round up based on stride.
2697 cl->set_nonexact_trip_count();
2698 Node *main_cle = cl->loopexit();
2699 Node *main_bol = main_cle->in(1);
2700 // Hacking loop bounds; need private copies of exit test
2701 if( main_bol->outcnt() > 1 ) {// BoolNode shared?
2702 main_bol = main_bol->clone();// Clone a private BoolNode
2703 register_new_node( main_bol, main_cle->in(0) );
2704 _igvn.replace_input_of(main_cle, 1, main_bol);
2705 }
2706 Node *main_cmp = main_bol->in(1);
2707 if( main_cmp->outcnt() > 1 ) { // CmpNode shared?
2708 main_cmp = main_cmp->clone();// Clone a private CmpNode
2709 register_new_node( main_cmp, main_cle->in(0) );
2710 _igvn.replace_input_of(main_bol, 1, main_cmp);
2711 }
2712 // Hack the now-private loop bounds
2713 _igvn.replace_input_of(main_cmp, 2, main_limit);
2714 // The OpaqueNode is unshared by design
2715 assert( opqzm->outcnt() == 1, "cannot hack shared node" );
2716 _igvn.replace_input_of(opqzm, 1, main_limit);
2717
2718 return closed_range_checks;
2719 }
2720
2721 //------------------------------has_range_checks-------------------------------
2722 // Check to see if RCE cleaned the current loop of range-checks.
2723 void PhaseIdealLoop::has_range_checks(IdealLoopTree *loop) {
2724 assert(RangeCheckElimination, "");
2725
2726 // skip if not a counted loop
2727 if (!loop->is_counted()) return;
2728
2729 CountedLoopNode *cl = loop->_head->as_CountedLoop();
2730
2731 // skip this loop if it is already checked
2732 if (cl->has_been_range_checked()) return;
2733
2734 // Now check for existence of range checks
2735 for (uint i = 0; i < loop->_body.size(); i++) {
2736 Node *iff = loop->_body[i];
2737 int iff_opc = iff->Opcode();
2738 if (iff_opc == Op_If || iff_opc == Op_RangeCheck) {
2739 cl->mark_has_range_checks();
2740 break;
2741 }
2742 }
2743 cl->set_has_been_range_checked();
2744 }
2745
2746 //-------------------------multi_version_post_loops----------------------------
2747 // Check the range checks that remain, if simple, use the bounds to guard
2748 // which version to a post loop we execute, one with range checks or one without
2749 bool PhaseIdealLoop::multi_version_post_loops(IdealLoopTree *rce_loop, IdealLoopTree *legacy_loop) {
2750 bool multi_version_succeeded = false;
2751 assert(RangeCheckElimination, "");
2752 CountedLoopNode *legacy_cl = legacy_loop->_head->as_CountedLoop();
2753 assert(legacy_cl->is_post_loop(), "");
2754
2755 // Check for existence of range checks using the unique instance to make a guard with
2756 Unique_Node_List worklist;
2757 for (uint i = 0; i < legacy_loop->_body.size(); i++) {
2758 Node *iff = legacy_loop->_body[i];
2759 int iff_opc = iff->Opcode();
2760 if (iff_opc == Op_If || iff_opc == Op_RangeCheck) {
2761 worklist.push(iff);
2762 }
2763 }
2764
2765 // Find RCE'd post loop so that we can stage its guard.
2766 if (!is_canonical_loop_entry(legacy_cl)) return multi_version_succeeded;
2767 Node* ctrl = legacy_cl->in(LoopNode::EntryControl);
2768 Node* iffm = ctrl->in(0);
2769
2770 // Now we test that both the post loops are connected
2771 Node* post_loop_region = iffm->in(0);
2772 if (post_loop_region == NULL) return multi_version_succeeded;
2773 if (!post_loop_region->is_Region()) return multi_version_succeeded;
2774 Node* covering_region = post_loop_region->in(RegionNode::Control+1);
2775 if (covering_region == NULL) return multi_version_succeeded;
2776 if (!covering_region->is_Region()) return multi_version_succeeded;
2777 Node* p_f = covering_region->in(RegionNode::Control);
2778 if (p_f == NULL) return multi_version_succeeded;
2779 if (!p_f->is_IfFalse()) return multi_version_succeeded;
2780 if (!p_f->in(0)->is_CountedLoopEnd()) return multi_version_succeeded;
2781 CountedLoopEndNode* rce_loop_end = p_f->in(0)->as_CountedLoopEnd();
2782 if (rce_loop_end == NULL) return multi_version_succeeded;
2783 CountedLoopNode* rce_cl = rce_loop_end->loopnode();
2784 if (rce_cl == NULL || !rce_cl->is_post_loop()) return multi_version_succeeded;
2785 CountedLoopNode *known_rce_cl = rce_loop->_head->as_CountedLoop();
2786 if (rce_cl != known_rce_cl) return multi_version_succeeded;
2787
2788 // Then we fetch the cover entry test
2789 ctrl = rce_cl->in(LoopNode::EntryControl);
2790 if (!ctrl->is_IfTrue() && !ctrl->is_IfFalse()) return multi_version_succeeded;
2791
2792 #ifndef PRODUCT
2793 if (TraceLoopOpts) {
2794 tty->print("PostMultiVersion\n");
2795 rce_loop->dump_head();
2796 legacy_loop->dump_head();
2797 }
2798 #endif
2799
2800 // Now fetch the limit we want to compare against
2801 Node *limit = rce_cl->limit();
2802 bool first_time = true;
2803
2804 // If we got this far, we identified the post loop which has been RCE'd and
2805 // we have a work list. Now we will try to transform the if guard to cause
2806 // the loop pair to be multi version executed with the determination left to runtime
2807 // or the optimizer if full information is known about the given arrays at compile time.
2808 Node *last_min = NULL;
2809 multi_version_succeeded = true;
2810 while (worklist.size()) {
2811 Node* rc_iffm = worklist.pop();
2812 if (rc_iffm->is_If()) {
2813 Node *rc_bolzm = rc_iffm->in(1);
2814 if (rc_bolzm->is_Bool()) {
2815 Node *rc_cmpzm = rc_bolzm->in(1);
2816 if (rc_cmpzm->is_Cmp()) {
2817 Node *rc_left = rc_cmpzm->in(2);
2818 if (rc_left->Opcode() != Op_LoadRange) {
2819 multi_version_succeeded = false;
2820 break;
2821 }
2822 if (first_time) {
2823 last_min = rc_left;
2824 first_time = false;
2825 } else {
2826 Node *cur_min = new MinINode(last_min, rc_left);
2827 last_min = cur_min;
2828 _igvn.register_new_node_with_optimizer(last_min);
2829 }
2830 }
2831 }
2832 }
2833 }
2834
2835 // All we have to do is update the limit of the rce loop
2836 // with the min of our expression and the current limit.
2837 // We will use this expression to replace the current limit.
2838 if (last_min && multi_version_succeeded) {
2839 Node *cur_min = new MinINode(last_min, limit);
2840 _igvn.register_new_node_with_optimizer(cur_min);
2841 Node *cmp_node = rce_loop_end->cmp_node();
2842 _igvn.replace_input_of(cmp_node, 2, cur_min);
2843 set_ctrl(cur_min, ctrl);
2844 set_loop(cur_min, rce_loop->_parent);
2845
2846 legacy_cl->mark_is_multiversioned();
2847 rce_cl->mark_is_multiversioned();
2848 multi_version_succeeded = true;
2849
2850 C->set_major_progress();
2851 }
2852
2853 return multi_version_succeeded;
2854 }
2855
2856 //-------------------------poison_rce_post_loop--------------------------------
2857 // Causes the rce'd post loop to be optimized away if multiversioning fails
2858 void PhaseIdealLoop::poison_rce_post_loop(IdealLoopTree *rce_loop) {
2859 CountedLoopNode *rce_cl = rce_loop->_head->as_CountedLoop();
2860 Node* ctrl = rce_cl->in(LoopNode::EntryControl);
2861 if (ctrl->is_IfTrue() || ctrl->is_IfFalse()) {
2862 Node* iffm = ctrl->in(0);
2863 if (iffm->is_If()) {
2864 Node* cur_bool = iffm->in(1);
2865 if (cur_bool->is_Bool()) {
2866 Node* cur_cmp = cur_bool->in(1);
2867 if (cur_cmp->is_Cmp()) {
2868 BoolTest::mask new_test = BoolTest::gt;
2869 BoolNode *new_bool = new BoolNode(cur_cmp, new_test);
2870 _igvn.replace_node(cur_bool, new_bool);
2871 _igvn._worklist.push(new_bool);
2872 Node* left_op = cur_cmp->in(1);
2873 _igvn.replace_input_of(cur_cmp, 2, left_op);
2874 C->set_major_progress();
2875 }
2876 }
2877 }
2878 }
2879 }
2880
2881 //------------------------------DCE_loop_body----------------------------------
2882 // Remove simplistic dead code from loop body
2883 void IdealLoopTree::DCE_loop_body() {
2884 for( uint i = 0; i < _body.size(); i++ )
2885 if( _body.at(i)->outcnt() == 0 )
2886 _body.map( i--, _body.pop() );
2887 }
2888
2889
2890 //------------------------------adjust_loop_exit_prob--------------------------
2891 // Look for loop-exit tests with the 50/50 (or worse) guesses from the parsing stage.
2892 // Replace with a 1-in-10 exit guess.
2893 void IdealLoopTree::adjust_loop_exit_prob( PhaseIdealLoop *phase ) {
2894 Node *test = tail();
2895 while( test != _head ) {
2896 uint top = test->Opcode();
2897 if( top == Op_IfTrue || top == Op_IfFalse ) {
2898 int test_con = ((ProjNode*)test)->_con;
2899 assert(top == (uint)(test_con? Op_IfTrue: Op_IfFalse), "sanity");
2900 IfNode *iff = test->in(0)->as_If();
2901 if( iff->outcnt() == 2 ) { // Ignore dead tests
2902 Node *bol = iff->in(1);
2903 if( bol && bol->req() > 1 && bol->in(1) &&
2904 ((bol->in(1)->Opcode() == Op_StorePConditional ) ||
2905 (bol->in(1)->Opcode() == Op_StoreIConditional ) ||
2906 (bol->in(1)->Opcode() == Op_StoreLConditional ) ||
2907 (bol->in(1)->Opcode() == Op_CompareAndExchangeB ) ||
2908 (bol->in(1)->Opcode() == Op_CompareAndExchangeS ) ||
2909 (bol->in(1)->Opcode() == Op_CompareAndExchangeI ) ||
2910 (bol->in(1)->Opcode() == Op_CompareAndExchangeL ) ||
2911 (bol->in(1)->Opcode() == Op_CompareAndExchangeP ) ||
2912 (bol->in(1)->Opcode() == Op_CompareAndExchangeN ) ||
2913 (bol->in(1)->Opcode() == Op_WeakCompareAndSwapB ) ||
2914 (bol->in(1)->Opcode() == Op_WeakCompareAndSwapS ) ||
2915 (bol->in(1)->Opcode() == Op_WeakCompareAndSwapI ) ||
2916 (bol->in(1)->Opcode() == Op_WeakCompareAndSwapL ) ||
2917 (bol->in(1)->Opcode() == Op_WeakCompareAndSwapP ) ||
2918 (bol->in(1)->Opcode() == Op_WeakCompareAndSwapN ) ||
2919 (bol->in(1)->Opcode() == Op_CompareAndSwapB ) ||
2920 (bol->in(1)->Opcode() == Op_CompareAndSwapS ) ||
2921 (bol->in(1)->Opcode() == Op_CompareAndSwapI ) ||
2922 (bol->in(1)->Opcode() == Op_CompareAndSwapL ) ||
2923 (bol->in(1)->Opcode() == Op_CompareAndSwapP ) ||
2924 (bol->in(1)->Opcode() == Op_CompareAndSwapN )))
2925 return; // Allocation loops RARELY take backedge
2926 // Find the OTHER exit path from the IF
2927 Node* ex = iff->proj_out(1-test_con);
2928 float p = iff->_prob;
2929 if( !phase->is_member( this, ex ) && iff->_fcnt == COUNT_UNKNOWN ) {
2930 if( top == Op_IfTrue ) {
2931 if( p < (PROB_FAIR + PROB_UNLIKELY_MAG(3))) {
2932 iff->_prob = PROB_STATIC_FREQUENT;
2933 }
2934 } else {
2935 if( p > (PROB_FAIR - PROB_UNLIKELY_MAG(3))) {
2936 iff->_prob = PROB_STATIC_INFREQUENT;
2937 }
2938 }
2939 }
2940 }
2941 }
2942 test = phase->idom(test);
2943 }
2944 }
2945
2946 #ifdef ASSERT
2947 static CountedLoopNode* locate_pre_from_main(CountedLoopNode* main_loop) {
2948 assert(!main_loop->is_main_no_pre_loop(), "Does not have a pre loop");
2949 Node* ctrl = main_loop->skip_predicates();
2950 assert(ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "");
2951 Node* iffm = ctrl->in(0);
2952 assert(iffm->Opcode() == Op_If, "");
2953 Node* p_f = iffm->in(0);
2954 assert(p_f->Opcode() == Op_IfFalse, "");
2955 CountedLoopNode* pre_loop = p_f->in(0)->as_CountedLoopEnd()->loopnode();
2956 assert(pre_loop->is_pre_loop(), "No pre loop found");
2957 return pre_loop;
2958 }
2959 #endif
2960
2961 // Remove the main and post loops and make the pre loop execute all
2962 // iterations. Useful when the pre loop is found empty.
2963 void IdealLoopTree::remove_main_post_loops(CountedLoopNode *cl, PhaseIdealLoop *phase) {
2964 CountedLoopEndNode* pre_end = cl->loopexit();
2965 Node* pre_cmp = pre_end->cmp_node();
2966 if (pre_cmp->in(2)->Opcode() != Op_Opaque1) {
2967 // Only safe to remove the main loop if the compiler optimized it
2968 // out based on an unknown number of iterations
2969 return;
2970 }
2971
2972 // Can we find the main loop?
2973 if (_next == NULL) {
2974 return;
2975 }
2976
2977 Node* next_head = _next->_head;
2978 if (!next_head->is_CountedLoop()) {
2979 return;
2980 }
2981
2982 CountedLoopNode* main_head = next_head->as_CountedLoop();
2983 if (!main_head->is_main_loop() || main_head->is_main_no_pre_loop()) {
2984 return;
2985 }
2986
2987 assert(locate_pre_from_main(main_head) == cl, "bad main loop");
2988 Node* main_iff = main_head->skip_predicates()->in(0);
2989
2990 // Remove the Opaque1Node of the pre loop and make it execute all iterations
2991 phase->_igvn.replace_input_of(pre_cmp, 2, pre_cmp->in(2)->in(2));
2992 // Remove the Opaque1Node of the main loop so it can be optimized out
2993 Node* main_cmp = main_iff->in(1)->in(1);
2994 assert(main_cmp->in(2)->Opcode() == Op_Opaque1, "main loop has no opaque node?");
2995 phase->_igvn.replace_input_of(main_cmp, 2, main_cmp->in(2)->in(1));
2996 }
2997
2998 //------------------------------policy_do_remove_empty_loop--------------------
2999 // Micro-benchmark spamming. Policy is to always remove empty loops.
3000 // The 'DO' part is to replace the trip counter with the value it will
3001 // have on the last iteration. This will break the loop.
3002 bool IdealLoopTree::policy_do_remove_empty_loop( PhaseIdealLoop *phase ) {
3003 // Minimum size must be empty loop
3004 if (_body.size() > EMPTY_LOOP_SIZE)
3005 return false;
3006
3007 if (!_head->is_CountedLoop())
3008 return false; // Dead loop
3009 CountedLoopNode *cl = _head->as_CountedLoop();
3010 if (!cl->is_valid_counted_loop())
3011 return false; // Malformed loop
3012 if (!phase->is_member(this, phase->get_ctrl(cl->loopexit()->in(CountedLoopEndNode::TestValue))))
3013 return false; // Infinite loop
3014
3015 if (cl->is_pre_loop()) {
3016 // If the loop we are removing is a pre-loop then the main and
3017 // post loop can be removed as well
3018 remove_main_post_loops(cl, phase);
3019 }
3020
3021 #ifdef ASSERT
3022 // Ensure only one phi which is the iv.
3023 Node* iv = NULL;
3024 for (DUIterator_Fast imax, i = cl->fast_outs(imax); i < imax; i++) {
3025 Node* n = cl->fast_out(i);
3026 if (n->Opcode() == Op_Phi) {
3027 assert(iv == NULL, "Too many phis" );
3028 iv = n;
3029 }
3030 }
3031 assert(iv == cl->phi(), "Wrong phi" );
3032 #endif
3033
3034 // main and post loops have explicitly created zero trip guard
3035 bool needs_guard = !cl->is_main_loop() && !cl->is_post_loop();
3036 if (needs_guard) {
3037 // Skip guard if values not overlap.
3038 const TypeInt* init_t = phase->_igvn.type(cl->init_trip())->is_int();
3039 const TypeInt* limit_t = phase->_igvn.type(cl->limit())->is_int();
3040 int stride_con = cl->stride_con();
3041 if (stride_con > 0) {
3042 needs_guard = (init_t->_hi >= limit_t->_lo);
3043 } else {
3044 needs_guard = (init_t->_lo <= limit_t->_hi);
3045 }
3046 }
3047 if (needs_guard) {
3048 // Check for an obvious zero trip guard.
3049 Node* inctrl = PhaseIdealLoop::skip_all_loop_predicates(cl->skip_predicates());
3050 if (inctrl->Opcode() == Op_IfTrue || inctrl->Opcode() == Op_IfFalse) {
3051 bool maybe_swapped = (inctrl->Opcode() == Op_IfFalse);
3052 // The test should look like just the backedge of a CountedLoop
3053 Node* iff = inctrl->in(0);
3054 if (iff->is_If()) {
3055 Node* bol = iff->in(1);
3056 if (bol->is_Bool()) {
3057 BoolTest test = bol->as_Bool()->_test;
3058 if (maybe_swapped) {
3059 test._test = test.commute();
3060 test._test = test.negate();
3061 }
3062 if (test._test == cl->loopexit()->test_trip()) {
3063 Node* cmp = bol->in(1);
3064 int init_idx = maybe_swapped ? 2 : 1;
3065 int limit_idx = maybe_swapped ? 1 : 2;
3066 if (cmp->is_Cmp() && cmp->in(init_idx) == cl->init_trip() && cmp->in(limit_idx) == cl->limit()) {
3067 needs_guard = false;
3068 }
3069 }
3070 }
3071 }
3072 }
3073 }
3074
3075 #ifndef PRODUCT
3076 if (PrintOpto) {
3077 tty->print("Removing empty loop with%s zero trip guard", needs_guard ? "out" : "");
3078 this->dump_head();
3079 } else if (TraceLoopOpts) {
3080 tty->print("Empty with%s zero trip guard ", needs_guard ? "out" : "");
3081 this->dump_head();
3082 }
3083 #endif
3084
3085 if (needs_guard) {
3086 // Peel the loop to ensure there's a zero trip guard
3087 Node_List old_new;
3088 phase->do_peeling(this, old_new);
3089 }
3090
3091 // Replace the phi at loop head with the final value of the last
3092 // iteration. Then the CountedLoopEnd will collapse (backedge never
3093 // taken) and all loop-invariant uses of the exit values will be correct.
3094 Node *phi = cl->phi();
3095 Node *exact_limit = phase->exact_limit(this);
3096 if (exact_limit != cl->limit()) {
3097 // We also need to replace the original limit to collapse loop exit.
3098 Node* cmp = cl->loopexit()->cmp_node();
3099 assert(cl->limit() == cmp->in(2), "sanity");
3100 // Duplicate cmp node if it has other users
3101 if (cmp->outcnt() > 1) {
3102 cmp = cmp->clone();
3103 cmp = phase->_igvn.register_new_node_with_optimizer(cmp);
3104 BoolNode *bol = cl->loopexit()->in(CountedLoopEndNode::TestValue)->as_Bool();
3105 phase->_igvn.replace_input_of(bol, 1, cmp); // put bol on worklist
3106 }
3107 phase->_igvn._worklist.push(cmp->in(2)); // put limit on worklist
3108 phase->_igvn.replace_input_of(cmp, 2, exact_limit); // put cmp on worklist
3109 }
3110 // Note: the final value after increment should not overflow since
3111 // counted loop has limit check predicate.
3112 Node *final = new SubINode( exact_limit, cl->stride() );
3113 phase->register_new_node(final,cl->in(LoopNode::EntryControl));
3114 phase->_igvn.replace_node(phi,final);
3115 phase->C->set_major_progress();
3116 return true;
3117 }
3118
3119 //------------------------------policy_do_one_iteration_loop-------------------
3120 // Convert one iteration loop into normal code.
3121 bool IdealLoopTree::policy_do_one_iteration_loop( PhaseIdealLoop *phase ) {
3122 if (!_head->as_Loop()->is_valid_counted_loop())
3123 return false; // Only for counted loop
3124
3125 CountedLoopNode *cl = _head->as_CountedLoop();
3126 if (!cl->has_exact_trip_count() || cl->trip_count() != 1) {
3127 return false;
3128 }
3129
3130 #ifndef PRODUCT
3131 if(TraceLoopOpts) {
3132 tty->print("OneIteration ");
3133 this->dump_head();
3134 }
3135 #endif
3136
3137 Node *init_n = cl->init_trip();
3138 #ifdef ASSERT
3139 // Loop boundaries should be constant since trip count is exact.
3140 assert(init_n->get_int() + cl->stride_con() >= cl->limit()->get_int(), "should be one iteration");
3141 #endif
3142 // Replace the phi at loop head with the value of the init_trip.
3143 // Then the CountedLoopEnd will collapse (backedge will not be taken)
3144 // and all loop-invariant uses of the exit values will be correct.
3145 phase->_igvn.replace_node(cl->phi(), cl->init_trip());
3146 phase->C->set_major_progress();
3147 return true;
3148 }
3149
3150 //=============================================================================
3151 //------------------------------iteration_split_impl---------------------------
3152 bool IdealLoopTree::iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new ) {
3153 // Compute loop trip count if possible.
3154 compute_trip_count(phase);
3155
3156 // Convert one iteration loop into normal code.
3157 if (policy_do_one_iteration_loop(phase))
3158 return true;
3159
3160 // Check and remove empty loops (spam micro-benchmarks)
3161 if (policy_do_remove_empty_loop(phase))
3162 return true; // Here we removed an empty loop
3163
3164 bool should_peel = policy_peeling(phase); // Should we peel?
3165
3166 bool should_unswitch = policy_unswitching(phase);
3167
3168 // Non-counted loops may be peeled; exactly 1 iteration is peeled.
3169 // This removes loop-invariant tests (usually null checks).
3170 if (!_head->is_CountedLoop()) { // Non-counted loop
3171 if (PartialPeelLoop && phase->partial_peel(this, old_new)) {
3172 // Partial peel succeeded so terminate this round of loop opts
3173 return false;
3174 }
3175 if (should_peel) { // Should we peel?
3176 if (PrintOpto) { tty->print_cr("should_peel"); }
3177 phase->do_peeling(this,old_new);
3178 } else if (should_unswitch) {
3179 phase->do_unswitching(this, old_new);
3180 }
3181 return true;
3182 }
3183 CountedLoopNode *cl = _head->as_CountedLoop();
3184
3185 if (!cl->is_valid_counted_loop()) return true; // Ignore various kinds of broken loops
3186
3187 // Do nothing special to pre- and post- loops
3188 if (cl->is_pre_loop() || cl->is_post_loop()) return true;
3189
3190 // Compute loop trip count from profile data
3191 compute_profile_trip_cnt(phase);
3192
3193 // Before attempting fancy unrolling, RCE or alignment, see if we want
3194 // to completely unroll this loop or do loop unswitching.
3195 if (cl->is_normal_loop()) {
3196 if (should_unswitch) {
3197 phase->do_unswitching(this, old_new);
3198 return true;
3199 }
3200 bool should_maximally_unroll = policy_maximally_unroll(phase);
3201 if (should_maximally_unroll) {
3202 // Here we did some unrolling and peeling. Eventually we will
3203 // completely unroll this loop and it will no longer be a loop.
3204 phase->do_maximally_unroll(this,old_new);
3205 return true;
3206 }
3207 }
3208
3209 // Skip next optimizations if running low on nodes. Note that
3210 // policy_unswitching and policy_maximally_unroll have this check.
3211 int nodes_left = phase->C->max_node_limit() - phase->C->live_nodes();
3212 if ((int)(2 * _body.size()) > nodes_left) {
3213 return true;
3214 }
3215
3216 // Counted loops may be peeled, may need some iterations run up
3217 // front for RCE, and may want to align loop refs to a cache
3218 // line. Thus we clone a full loop up front whose trip count is
3219 // at least 1 (if peeling), but may be several more.
3220
3221 // The main loop will start cache-line aligned with at least 1
3222 // iteration of the unrolled body (zero-trip test required) and
3223 // will have some range checks removed.
3224
3225 // A post-loop will finish any odd iterations (leftover after
3226 // unrolling), plus any needed for RCE purposes.
3227
3228 bool should_unroll = policy_unroll(phase);
3229
3230 bool should_rce = policy_range_check(phase);
3231
3232 bool should_align = policy_align(phase);
3233
3234 // If not RCE'ing (iteration splitting) or Aligning, then we do not
3235 // need a pre-loop. We may still need to peel an initial iteration but
3236 // we will not be needing an unknown number of pre-iterations.
3237 //
3238 // Basically, if may_rce_align reports FALSE first time through,
3239 // we will not be able to later do RCE or Aligning on this loop.
3240 bool may_rce_align = !policy_peel_only(phase) || should_rce || should_align;
3241
3242 // If we have any of these conditions (RCE, alignment, unrolling) met, then
3243 // we switch to the pre-/main-/post-loop model. This model also covers
3244 // peeling.
3245 if (should_rce || should_align || should_unroll) {
3246 if (cl->is_normal_loop()) // Convert to 'pre/main/post' loops
3247 phase->insert_pre_post_loops(this,old_new, !may_rce_align);
3248
3249 // Adjust the pre- and main-loop limits to let the pre and post loops run
3250 // with full checks, but the main-loop with no checks. Remove said
3251 // checks from the main body.
3252 if (should_rce) {
3253 if (phase->do_range_check(this, old_new) != 0) {
3254 cl->mark_has_range_checks();
3255 }
3256 } else if (PostLoopMultiversioning) {
3257 phase->has_range_checks(this);
3258 }
3259
3260 if (should_unroll && !should_peel && PostLoopMultiversioning) {
3261 // Try to setup multiversioning on main loops before they are unrolled
3262 if (cl->is_main_loop() && (cl->unrolled_count() == 1)) {
3263 phase->insert_scalar_rced_post_loop(this, old_new);
3264 }
3265 }
3266
3267 // Double loop body for unrolling. Adjust the minimum-trip test (will do
3268 // twice as many iterations as before) and the main body limit (only do
3269 // an even number of trips). If we are peeling, we might enable some RCE
3270 // and we'd rather unroll the post-RCE'd loop SO... do not unroll if
3271 // peeling.
3272 if (should_unroll && !should_peel) {
3273 if (SuperWordLoopUnrollAnalysis) {
3274 phase->insert_vector_post_loop(this, old_new);
3275 }
3276 phase->do_unroll(this, old_new, true);
3277 }
3278
3279 // Adjust the pre-loop limits to align the main body
3280 // iterations.
3281 if (should_align)
3282 Unimplemented();
3283
3284 } else { // Else we have an unchanged counted loop
3285 if (should_peel) // Might want to peel but do nothing else
3286 phase->do_peeling(this,old_new);
3287 }
3288 return true;
3289 }
3290
3291
3292 //=============================================================================
3293 //------------------------------iteration_split--------------------------------
3294 bool IdealLoopTree::iteration_split( PhaseIdealLoop *phase, Node_List &old_new ) {
3295 // Recursively iteration split nested loops
3296 if (_child && !_child->iteration_split(phase, old_new))
3297 return false;
3298
3299 // Clean out prior deadwood
3300 DCE_loop_body();
3301
3302
3303 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage.
3304 // Replace with a 1-in-10 exit guess.
3305 if (_parent /*not the root loop*/ &&
3306 !_irreducible &&
3307 // Also ignore the occasional dead backedge
3308 !tail()->is_top()) {
3309 adjust_loop_exit_prob(phase);
3310 }
3311
3312 // Gate unrolling, RCE and peeling efforts.
3313 if (!_child && // If not an inner loop, do not split
3314 !_irreducible &&
3315 _allow_optimizations &&
3316 !tail()->is_top()) { // Also ignore the occasional dead backedge
3317 if (!_has_call) {
3318 if (!iteration_split_impl(phase, old_new)) {
3319 return false;
3320 }
3321 } else if (policy_unswitching(phase)) {
3322 phase->do_unswitching(this, old_new);
3323 }
3324 }
3325
3326 // Minor offset re-organization to remove loop-fallout uses of
3327 // trip counter when there was no major reshaping.
3328 phase->reorg_offsets(this);
3329
3330 if (_next && !_next->iteration_split(phase, old_new))
3331 return false;
3332 return true;
3333 }
3334
3335
3336 //=============================================================================
3337 // Process all the loops in the loop tree and replace any fill
3338 // patterns with an intrinsic version.
3339 bool PhaseIdealLoop::do_intrinsify_fill() {
3340 bool changed = false;
3341 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
3342 IdealLoopTree* lpt = iter.current();
3343 changed |= intrinsify_fill(lpt);
3344 }
3345 return changed;
3346 }
3347
3348
3349 // Examine an inner loop looking for a a single store of an invariant
3350 // value in a unit stride loop,
3351 bool PhaseIdealLoop::match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value,
3352 Node*& shift, Node*& con) {
3353 const char* msg = NULL;
3354 Node* msg_node = NULL;
3355
3356 store_value = NULL;
3357 con = NULL;
3358 shift = NULL;
3359
3360 // Process the loop looking for stores. If there are multiple
3361 // stores or extra control flow give at this point.
3362 CountedLoopNode* head = lpt->_head->as_CountedLoop();
3363 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) {
3364 Node* n = lpt->_body.at(i);
3365 if (n->outcnt() == 0) continue; // Ignore dead
3366 if (n->is_Store()) {
3367 if (store != NULL) {
3368 msg = "multiple stores";
3369 break;
3370 }
3371 int opc = n->Opcode();
3372 if (opc == Op_StoreP || opc == Op_StoreN || opc == Op_StoreNKlass || opc == Op_StoreCM) {
3373 msg = "oop fills not handled";
3374 break;
3375 }
3376 Node* value = n->in(MemNode::ValueIn);
3377 if (!lpt->is_invariant(value)) {
3378 msg = "variant store value";
3379 } else if (!_igvn.type(n->in(MemNode::Address))->isa_aryptr()) {
3380 msg = "not array address";
3381 }
3382 store = n;
3383 store_value = value;
3384 } else if (n->is_If() && n != head->loopexit_or_null()) {
3385 msg = "extra control flow";
3386 msg_node = n;
3387 }
3388 }
3389
3390 if (store == NULL) {
3391 // No store in loop
3392 return false;
3393 }
3394
3395 if (msg == NULL && head->stride_con() != 1) {
3396 // could handle negative strides too
3397 if (head->stride_con() < 0) {
3398 msg = "negative stride";
3399 } else {
3400 msg = "non-unit stride";
3401 }
3402 }
3403
3404 if (msg == NULL && !store->in(MemNode::Address)->is_AddP()) {
3405 msg = "can't handle store address";
3406 msg_node = store->in(MemNode::Address);
3407 }
3408
3409 if (msg == NULL &&
3410 (!store->in(MemNode::Memory)->is_Phi() ||
3411 store->in(MemNode::Memory)->in(LoopNode::LoopBackControl) != store)) {
3412 msg = "store memory isn't proper phi";
3413 msg_node = store->in(MemNode::Memory);
3414 }
3415
3416 // Make sure there is an appropriate fill routine
3417 BasicType t = store->as_Mem()->memory_type();
3418 const char* fill_name;
3419 if (msg == NULL &&
3420 StubRoutines::select_fill_function(t, false, fill_name) == NULL) {
3421 msg = "unsupported store";
3422 msg_node = store;
3423 }
3424
3425 if (msg != NULL) {
3426 #ifndef PRODUCT
3427 if (TraceOptimizeFill) {
3428 tty->print_cr("not fill intrinsic candidate: %s", msg);
3429 if (msg_node != NULL) msg_node->dump();
3430 }
3431 #endif
3432 return false;
3433 }
3434
3435 // Make sure the address expression can be handled. It should be
3436 // head->phi * elsize + con. head->phi might have a ConvI2L(CastII()).
3437 Node* elements[4];
3438 Node* cast = NULL;
3439 Node* conv = NULL;
3440 bool found_index = false;
3441 int count = store->in(MemNode::Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
3442 for (int e = 0; e < count; e++) {
3443 Node* n = elements[e];
3444 if (n->is_Con() && con == NULL) {
3445 con = n;
3446 } else if (n->Opcode() == Op_LShiftX && shift == NULL) {
3447 Node* value = n->in(1);
3448 #ifdef _LP64
3449 if (value->Opcode() == Op_ConvI2L) {
3450 conv = value;
3451 value = value->in(1);
3452 }
3453 if (value->Opcode() == Op_CastII &&
3454 value->as_CastII()->has_range_check()) {
3455 // Skip range check dependent CastII nodes
3456 cast = value;
3457 value = value->in(1);
3458 }
3459 #endif
3460 if (value != head->phi()) {
3461 msg = "unhandled shift in address";
3462 } else {
3463 if (type2aelembytes(store->as_Mem()->memory_type(), true) != (1 << n->in(2)->get_int())) {
3464 msg = "scale doesn't match";
3465 } else {
3466 found_index = true;
3467 shift = n;
3468 }
3469 }
3470 } else if (n->Opcode() == Op_ConvI2L && conv == NULL) {
3471 conv = n;
3472 n = n->in(1);
3473 if (n->Opcode() == Op_CastII &&
3474 n->as_CastII()->has_range_check()) {
3475 // Skip range check dependent CastII nodes
3476 cast = n;
3477 n = n->in(1);
3478 }
3479 if (n == head->phi()) {
3480 found_index = true;
3481 } else {
3482 msg = "unhandled input to ConvI2L";
3483 }
3484 } else if (n == head->phi()) {
3485 // no shift, check below for allowed cases
3486 found_index = true;
3487 } else {
3488 msg = "unhandled node in address";
3489 msg_node = n;
3490 }
3491 }
3492
3493 if (count == -1) {
3494 msg = "malformed address expression";
3495 msg_node = store;
3496 }
3497
3498 if (!found_index) {
3499 msg = "missing use of index";
3500 }
3501
3502 // byte sized items won't have a shift
3503 if (msg == NULL && shift == NULL && t != T_BYTE && t != T_BOOLEAN) {
3504 msg = "can't find shift";
3505 msg_node = store;
3506 }
3507
3508 if (msg != NULL) {
3509 #ifndef PRODUCT
3510 if (TraceOptimizeFill) {
3511 tty->print_cr("not fill intrinsic: %s", msg);
3512 if (msg_node != NULL) msg_node->dump();
3513 }
3514 #endif
3515 return false;
3516 }
3517
3518 // No make sure all the other nodes in the loop can be handled
3519 VectorSet ok(Thread::current()->resource_area());
3520
3521 // store related values are ok
3522 ok.set(store->_idx);
3523 ok.set(store->in(MemNode::Memory)->_idx);
3524
3525 CountedLoopEndNode* loop_exit = head->loopexit();
3526
3527 // Loop structure is ok
3528 ok.set(head->_idx);
3529 ok.set(loop_exit->_idx);
3530 ok.set(head->phi()->_idx);
3531 ok.set(head->incr()->_idx);
3532 ok.set(loop_exit->cmp_node()->_idx);
3533 ok.set(loop_exit->in(1)->_idx);
3534
3535 // Address elements are ok
3536 if (con) ok.set(con->_idx);
3537 if (shift) ok.set(shift->_idx);
3538 if (cast) ok.set(cast->_idx);
3539 if (conv) ok.set(conv->_idx);
3540
3541 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) {
3542 Node* n = lpt->_body.at(i);
3543 if (n->outcnt() == 0) continue; // Ignore dead
3544 if (ok.test(n->_idx)) continue;
3545 // Backedge projection is ok
3546 if (n->is_IfTrue() && n->in(0) == loop_exit) continue;
3547 if (!n->is_AddP()) {
3548 msg = "unhandled node";
3549 msg_node = n;
3550 break;
3551 }
3552 }
3553
3554 // Make sure no unexpected values are used outside the loop
3555 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) {
3556 Node* n = lpt->_body.at(i);
3557 // These values can be replaced with other nodes if they are used
3558 // outside the loop.
3559 if (n == store || n == loop_exit || n == head->incr() || n == store->in(MemNode::Memory)) continue;
3560 for (SimpleDUIterator iter(n); iter.has_next(); iter.next()) {
3561 Node* use = iter.get();
3562 if (!lpt->_body.contains(use)) {
3563 msg = "node is used outside loop";
3564 // lpt->_body.dump();
3565 msg_node = n;
3566 break;
3567 }
3568 }
3569 }
3570
3571 #ifdef ASSERT
3572 if (TraceOptimizeFill) {
3573 if (msg != NULL) {
3574 tty->print_cr("no fill intrinsic: %s", msg);
3575 if (msg_node != NULL) msg_node->dump();
3576 } else {
3577 tty->print_cr("fill intrinsic for:");
3578 }
3579 store->dump();
3580 if (Verbose) {
3581 lpt->_body.dump();
3582 }
3583 }
3584 #endif
3585
3586 return msg == NULL;
3587 }
3588
3589
3590
3591 bool PhaseIdealLoop::intrinsify_fill(IdealLoopTree* lpt) {
3592 // Only for counted inner loops
3593 if (!lpt->is_counted() || !lpt->is_inner()) {
3594 return false;
3595 }
3596
3597 // Must have constant stride
3598 CountedLoopNode* head = lpt->_head->as_CountedLoop();
3599 if (!head->is_valid_counted_loop() || !head->is_normal_loop()) {
3600 return false;
3601 }
3602
3603 head->verify_strip_mined(1);
3604
3605 // Check that the body only contains a store of a loop invariant
3606 // value that is indexed by the loop phi.
3607 Node* store = NULL;
3608 Node* store_value = NULL;
3609 Node* shift = NULL;
3610 Node* offset = NULL;
3611 if (!match_fill_loop(lpt, store, store_value, shift, offset)) {
3612 return false;
3613 }
3614
3615 Node* exit = head->loopexit()->proj_out_or_null(0);
3616 if (exit == NULL) {
3617 return false;
3618 }
3619
3620 #ifndef PRODUCT
3621 if (TraceLoopOpts) {
3622 tty->print("ArrayFill ");
3623 lpt->dump_head();
3624 }
3625 #endif
3626
3627 // Now replace the whole loop body by a call to a fill routine that
3628 // covers the same region as the loop.
3629 Node* base = store->in(MemNode::Address)->as_AddP()->in(AddPNode::Base);
3630
3631 // Build an expression for the beginning of the copy region
3632 Node* index = head->init_trip();
3633 #ifdef _LP64
3634 index = new ConvI2LNode(index);
3635 _igvn.register_new_node_with_optimizer(index);
3636 #endif
3637 if (shift != NULL) {
3638 // byte arrays don't require a shift but others do.
3639 index = new LShiftXNode(index, shift->in(2));
3640 _igvn.register_new_node_with_optimizer(index);
3641 }
3642 index = new AddPNode(base, base, index);
3643 _igvn.register_new_node_with_optimizer(index);
3644 Node* from = new AddPNode(base, index, offset);
3645 _igvn.register_new_node_with_optimizer(from);
3646 // Compute the number of elements to copy
3647 Node* len = new SubINode(head->limit(), head->init_trip());
3648 _igvn.register_new_node_with_optimizer(len);
3649
3650 BasicType t = store->as_Mem()->memory_type();
3651 bool aligned = false;
3652 if (offset != NULL && head->init_trip()->is_Con()) {
3653 int element_size = type2aelembytes(t);
3654 aligned = (offset->find_intptr_t_type()->get_con() + head->init_trip()->get_int() * element_size) % HeapWordSize == 0;
3655 }
3656
3657 // Build a call to the fill routine
3658 const char* fill_name;
3659 address fill = StubRoutines::select_fill_function(t, aligned, fill_name);
3660 assert(fill != NULL, "what?");
3661
3662 // Convert float/double to int/long for fill routines
3663 if (t == T_FLOAT) {
3664 store_value = new MoveF2INode(store_value);
3665 _igvn.register_new_node_with_optimizer(store_value);
3666 } else if (t == T_DOUBLE) {
3667 store_value = new MoveD2LNode(store_value);
3668 _igvn.register_new_node_with_optimizer(store_value);
3669 }
3670
3671 Node* mem_phi = store->in(MemNode::Memory);
3672 Node* result_ctrl;
3673 Node* result_mem;
3674 const TypeFunc* call_type = OptoRuntime::array_fill_Type();
3675 CallLeafNode *call = new CallLeafNoFPNode(call_type, fill,
3676 fill_name, TypeAryPtr::get_array_body_type(t));
3677 uint cnt = 0;
3678 call->init_req(TypeFunc::Parms + cnt++, from);
3679 call->init_req(TypeFunc::Parms + cnt++, store_value);
3680 #ifdef _LP64
3681 len = new ConvI2LNode(len);
3682 _igvn.register_new_node_with_optimizer(len);
3683 #endif
3684 call->init_req(TypeFunc::Parms + cnt++, len);
3685 #ifdef _LP64
3686 call->init_req(TypeFunc::Parms + cnt++, C->top());
3687 #endif
3688 call->init_req(TypeFunc::Control, head->init_control());
3689 call->init_req(TypeFunc::I_O, C->top()); // Does no I/O.
3690 call->init_req(TypeFunc::Memory, mem_phi->in(LoopNode::EntryControl));
3691 call->init_req(TypeFunc::ReturnAdr, C->start()->proj_out_or_null(TypeFunc::ReturnAdr));
3692 call->init_req(TypeFunc::FramePtr, C->start()->proj_out_or_null(TypeFunc::FramePtr));
3693 _igvn.register_new_node_with_optimizer(call);
3694 result_ctrl = new ProjNode(call,TypeFunc::Control);
3695 _igvn.register_new_node_with_optimizer(result_ctrl);
3696 result_mem = new ProjNode(call,TypeFunc::Memory);
3697 _igvn.register_new_node_with_optimizer(result_mem);
3698
3699 /* Disable following optimization until proper fix (add missing checks).
3700
3701 // If this fill is tightly coupled to an allocation and overwrites
3702 // the whole body, allow it to take over the zeroing.
3703 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, this);
3704 if (alloc != NULL && alloc->is_AllocateArray()) {
3705 Node* length = alloc->as_AllocateArray()->Ideal_length();
3706 if (head->limit() == length &&
3707 head->init_trip() == _igvn.intcon(0)) {
3708 if (TraceOptimizeFill) {
3709 tty->print_cr("Eliminated zeroing in allocation");
3710 }
3711 alloc->maybe_set_complete(&_igvn);
3712 } else {
3713 #ifdef ASSERT
3714 if (TraceOptimizeFill) {
3715 tty->print_cr("filling array but bounds don't match");
3716 alloc->dump();
3717 head->init_trip()->dump();
3718 head->limit()->dump();
3719 length->dump();
3720 }
3721 #endif
3722 }
3723 }
3724 */
3725
3726 if (head->is_strip_mined()) {
3727 // Inner strip mined loop goes away so get rid of outer strip
3728 // mined loop
3729 Node* outer_sfpt = head->outer_safepoint();
3730 Node* in = outer_sfpt->in(0);
3731 Node* outer_out = head->outer_loop_exit();
3732 lazy_replace(outer_out, in);
3733 _igvn.replace_input_of(outer_sfpt, 0, C->top());
3734 }
3735
3736 // Redirect the old control and memory edges that are outside the loop.
3737 // Sometimes the memory phi of the head is used as the outgoing
3738 // state of the loop. It's safe in this case to replace it with the
3739 // result_mem.
3740 _igvn.replace_node(store->in(MemNode::Memory), result_mem);
3741 lazy_replace(exit, result_ctrl);
3742 _igvn.replace_node(store, result_mem);
3743 // Any uses the increment outside of the loop become the loop limit.
3744 _igvn.replace_node(head->incr(), head->limit());
3745
3746 // Disconnect the head from the loop.
3747 for (uint i = 0; i < lpt->_body.size(); i++) {
3748 Node* n = lpt->_body.at(i);
3749 _igvn.replace_node(n, C->top());
3750 }
3751
3752 return true;
3753 }