1 /*
2 * Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "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 }
71
72 //------------------------------compute_exact_trip_count-----------------------
73 // Compute loop exact trip count if possible. Do not recalculate trip count for
74 // split loops (pre-main-post) which have their limits and inits behind Opaque node.
75 void IdealLoopTree::compute_exact_trip_count( PhaseIdealLoop *phase ) {
76 if (!_head->as_Loop()->is_valid_counted_loop()) {
77 return;
78 }
79 CountedLoopNode* cl = _head->as_CountedLoop();
80 // Trip count may become nonexact for iteration split loops since
81 // RCE modifies limits. Note, _trip_count value is not reset since
82 // it is used to limit unrolling of main loop.
83 cl->set_nonexact_trip_count();
84
85 // Loop's test should be part of loop.
86 if (!phase->is_member(this, phase->get_ctrl(cl->loopexit()->in(CountedLoopEndNode::TestValue))))
87 return; // Infinite loop
88
89 #ifdef ASSERT
90 BoolTest::mask bt = cl->loopexit()->test_trip();
91 assert(bt == BoolTest::lt || bt == BoolTest::gt ||
92 bt == BoolTest::ne, "canonical test is expected");
93 #endif
94
95 Node* init_n = cl->init_trip();
96 Node* limit_n = cl->limit();
97 if (init_n != NULL && init_n->is_Con() &&
98 limit_n != NULL && limit_n->is_Con()) {
99 // Use longs to avoid integer overflow.
100 int stride_con = cl->stride_con();
101 jlong init_con = cl->init_trip()->get_int();
102 jlong limit_con = cl->limit()->get_int();
103 int stride_m = stride_con - (stride_con > 0 ? 1 : -1);
104 jlong trip_count = (limit_con - init_con + stride_m)/stride_con;
105 if (trip_count > 0 && (julong)trip_count < (julong)max_juint) {
106 // Set exact trip count.
107 cl->set_exact_trip_count((uint)trip_count);
108 }
109 }
110 }
111
112 //------------------------------compute_profile_trip_cnt----------------------------
113 // Compute loop trip count from profile data as
114 // (backedge_count + loop_exit_count) / loop_exit_count
115 void IdealLoopTree::compute_profile_trip_cnt( PhaseIdealLoop *phase ) {
116 if (!_head->is_CountedLoop()) {
117 return;
118 }
119 CountedLoopNode* head = _head->as_CountedLoop();
120 if (head->profile_trip_cnt() != COUNT_UNKNOWN) {
121 return; // Already computed
122 }
123 float trip_cnt = (float)max_jint; // default is big
124
125 Node* back = head->in(LoopNode::LoopBackControl);
126 while (back != head) {
127 if ((back->Opcode() == Op_IfTrue || back->Opcode() == Op_IfFalse) &&
128 back->in(0) &&
129 back->in(0)->is_If() &&
130 back->in(0)->as_If()->_fcnt != COUNT_UNKNOWN &&
131 back->in(0)->as_If()->_prob != PROB_UNKNOWN) {
132 break;
133 }
134 back = phase->idom(back);
135 }
136 if (back != head) {
137 assert((back->Opcode() == Op_IfTrue || back->Opcode() == Op_IfFalse) &&
138 back->in(0), "if-projection exists");
139 IfNode* back_if = back->in(0)->as_If();
140 float loop_back_cnt = back_if->_fcnt * back_if->_prob;
141
142 // Now compute a loop exit count
143 float loop_exit_cnt = 0.0f;
144 for( uint i = 0; i < _body.size(); i++ ) {
145 Node *n = _body[i];
146 if( n->is_If() ) {
147 IfNode *iff = n->as_If();
148 if( iff->_fcnt != COUNT_UNKNOWN && iff->_prob != PROB_UNKNOWN ) {
149 Node *exit = is_loop_exit(iff);
150 if( exit ) {
151 float exit_prob = iff->_prob;
152 if (exit->Opcode() == Op_IfFalse) exit_prob = 1.0 - exit_prob;
153 if (exit_prob > PROB_MIN) {
154 float exit_cnt = iff->_fcnt * exit_prob;
155 loop_exit_cnt += exit_cnt;
156 }
157 }
158 }
159 }
160 }
161 if (loop_exit_cnt > 0.0f) {
162 trip_cnt = (loop_back_cnt + loop_exit_cnt) / loop_exit_cnt;
163 } else {
164 // No exit count so use
165 trip_cnt = loop_back_cnt;
166 }
167 }
168 #ifndef PRODUCT
169 if (TraceProfileTripCount) {
170 tty->print_cr("compute_profile_trip_cnt lp: %d cnt: %f\n", head->_idx, trip_cnt);
171 }
172 #endif
173 head->set_profile_trip_cnt(trip_cnt);
174 }
175
176 //---------------------is_invariant_addition-----------------------------
177 // Return nonzero index of invariant operand for an Add or Sub
178 // of (nonconstant) invariant and variant values. Helper for reassociate_invariants.
179 int IdealLoopTree::is_invariant_addition(Node* n, PhaseIdealLoop *phase) {
180 int op = n->Opcode();
181 if (op == Op_AddI || op == Op_SubI) {
182 bool in1_invar = this->is_invariant(n->in(1));
183 bool in2_invar = this->is_invariant(n->in(2));
184 if (in1_invar && !in2_invar) return 1;
185 if (!in1_invar && in2_invar) return 2;
186 }
187 return 0;
188 }
189
190 //---------------------reassociate_add_sub-----------------------------
191 // Reassociate invariant add and subtract expressions:
192 //
193 // inv1 + (x + inv2) => ( inv1 + inv2) + x
194 // (x + inv2) + inv1 => ( inv1 + inv2) + x
195 // inv1 + (x - inv2) => ( inv1 - inv2) + x
196 // inv1 - (inv2 - x) => ( inv1 - inv2) + x
197 // (x + inv2) - inv1 => (-inv1 + inv2) + x
198 // (x - inv2) + inv1 => ( inv1 - inv2) + x
199 // (x - inv2) - inv1 => (-inv1 - inv2) + x
200 // inv1 + (inv2 - x) => ( inv1 + inv2) - x
201 // inv1 - (x - inv2) => ( inv1 + inv2) - x
202 // (inv2 - x) + inv1 => ( inv1 + inv2) - x
203 // (inv2 - x) - inv1 => (-inv1 + inv2) - x
204 // inv1 - (x + inv2) => ( inv1 - inv2) - x
205 //
206 Node* IdealLoopTree::reassociate_add_sub(Node* n1, PhaseIdealLoop *phase) {
207 if (!n1->is_Add() && !n1->is_Sub() || n1->outcnt() == 0) return NULL;
208 if (is_invariant(n1)) return NULL;
209 int inv1_idx = is_invariant_addition(n1, phase);
210 if (!inv1_idx) return NULL;
211 // Don't mess with add of constant (igvn moves them to expression tree root.)
212 if (n1->is_Add() && n1->in(2)->is_Con()) return NULL;
213 Node* inv1 = n1->in(inv1_idx);
214 Node* n2 = n1->in(3 - inv1_idx);
215 int inv2_idx = is_invariant_addition(n2, phase);
216 if (!inv2_idx) return NULL;
217 Node* x = n2->in(3 - inv2_idx);
218 Node* inv2 = n2->in(inv2_idx);
219
220 bool neg_x = n2->is_Sub() && inv2_idx == 1;
221 bool neg_inv2 = n2->is_Sub() && inv2_idx == 2;
222 bool neg_inv1 = n1->is_Sub() && inv1_idx == 2;
223 if (n1->is_Sub() && inv1_idx == 1) {
224 neg_x = !neg_x;
225 neg_inv2 = !neg_inv2;
226 }
227 Node* inv1_c = phase->get_ctrl(inv1);
228 Node* inv2_c = phase->get_ctrl(inv2);
229 Node* n_inv1;
230 if (neg_inv1) {
231 Node *zero = phase->_igvn.intcon(0);
232 phase->set_ctrl(zero, phase->C->root());
233 n_inv1 = new SubINode(zero, inv1);
234 phase->register_new_node(n_inv1, inv1_c);
235 } else {
236 n_inv1 = inv1;
237 }
238 Node* inv;
239 if (neg_inv2) {
240 inv = new SubINode(n_inv1, inv2);
241 } else {
242 inv = new AddINode(n_inv1, inv2);
243 }
244 phase->register_new_node(inv, phase->get_early_ctrl(inv));
245
246 Node* addx;
247 if (neg_x) {
248 addx = new SubINode(inv, x);
249 } else {
250 addx = new AddINode(x, inv);
251 }
252 phase->register_new_node(addx, phase->get_ctrl(x));
253 phase->_igvn.replace_node(n1, addx);
254 assert(phase->get_loop(phase->get_ctrl(n1)) == this, "");
255 _body.yank(n1);
256 return addx;
257 }
258
259 //---------------------reassociate_invariants-----------------------------
260 // Reassociate invariant expressions:
261 void IdealLoopTree::reassociate_invariants(PhaseIdealLoop *phase) {
262 for (int i = _body.size() - 1; i >= 0; i--) {
263 Node *n = _body.at(i);
264 for (int j = 0; j < 5; j++) {
265 Node* nn = reassociate_add_sub(n, phase);
266 if (nn == NULL) break;
267 n = nn; // again
268 };
269 }
270 }
271
272 //------------------------------policy_peeling---------------------------------
273 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can
274 // make some loop-invariant test (usually a null-check) happen before the loop.
275 bool IdealLoopTree::policy_peeling( PhaseIdealLoop *phase ) const {
276 Node *test = ((IdealLoopTree*)this)->tail();
277 int body_size = ((IdealLoopTree*)this)->_body.size();
278 // Peeling does loop cloning which can result in O(N^2) node construction
279 if( body_size > 255 /* Prevent overflow for large body_size */
280 || (body_size * body_size + phase->C->live_nodes()) > phase->C->max_node_limit() ) {
281 return false; // too large to safely clone
282 }
283
284 // check for vectorized loops, any peeling done was already applied
285 if (_head->is_CountedLoop() && _head->as_CountedLoop()->do_unroll_only()) return false;
286
287 while( test != _head ) { // Scan till run off top of loop
288 if( test->is_If() ) { // Test?
289 Node *ctrl = phase->get_ctrl(test->in(1));
290 if (ctrl->is_top())
291 return false; // Found dead test on live IF? No peeling!
292 // Standard IF only has one input value to check for loop invariance
293 assert(test->Opcode() == Op_If || test->Opcode() == Op_CountedLoopEnd || test->Opcode() == Op_RangeCheck, "Check this code when new subtype is added");
294 // Condition is not a member of this loop?
295 if( !is_member(phase->get_loop(ctrl)) &&
296 is_loop_exit(test) )
297 return true; // Found reason to peel!
298 }
299 // Walk up dominators to loop _head looking for test which is
300 // executed on every path thru loop.
301 test = phase->idom(test);
302 }
303 return false;
304 }
305
306 //------------------------------peeled_dom_test_elim---------------------------
307 // If we got the effect of peeling, either by actually peeling or by making
308 // a pre-loop which must execute at least once, we can remove all
309 // loop-invariant dominated tests in the main body.
310 void PhaseIdealLoop::peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new ) {
311 bool progress = true;
312 while( progress ) {
313 progress = false; // Reset for next iteration
314 Node *prev = loop->_head->in(LoopNode::LoopBackControl);//loop->tail();
315 Node *test = prev->in(0);
316 while( test != loop->_head ) { // Scan till run off top of loop
317
318 int p_op = prev->Opcode();
319 if( (p_op == Op_IfFalse || p_op == Op_IfTrue) &&
320 test->is_If() && // Test?
321 !test->in(1)->is_Con() && // And not already obvious?
322 // Condition is not a member of this loop?
323 !loop->is_member(get_loop(get_ctrl(test->in(1))))){
324 // Walk loop body looking for instances of this test
325 for( uint i = 0; i < loop->_body.size(); i++ ) {
326 Node *n = loop->_body.at(i);
327 if( n->is_If() && n->in(1) == test->in(1) /*&& n != loop->tail()->in(0)*/ ) {
328 // IfNode was dominated by version in peeled loop body
329 progress = true;
330 dominated_by( old_new[prev->_idx], n );
331 }
332 }
333 }
334 prev = test;
335 test = idom(test);
336 } // End of scan tests in loop
337
338 } // End of while( progress )
339 }
340
341 //------------------------------do_peeling-------------------------------------
342 // Peel the first iteration of the given loop.
343 // Step 1: Clone the loop body. The clone becomes the peeled iteration.
344 // The pre-loop illegally has 2 control users (old & new loops).
345 // Step 2: Make the old-loop fall-in edges point to the peeled iteration.
346 // Do this by making the old-loop fall-in edges act as if they came
347 // around the loopback from the prior iteration (follow the old-loop
348 // backedges) and then map to the new peeled iteration. This leaves
349 // the pre-loop with only 1 user (the new peeled iteration), but the
350 // peeled-loop backedge has 2 users.
351 // Step 3: Cut the backedge on the clone (so its not a loop) and remove the
352 // extra backedge user.
353 //
354 // orig
355 //
356 // stmt1
357 // |
358 // v
359 // loop predicate
360 // |
361 // v
362 // loop<----+
363 // | |
364 // stmt2 |
365 // | |
366 // v |
367 // if ^
368 // / \ |
369 // / \ |
370 // v v |
371 // false true |
372 // / \ |
373 // / ----+
374 // |
375 // v
376 // exit
377 //
378 //
379 // after clone loop
380 //
381 // stmt1
382 // |
383 // v
384 // loop predicate
385 // / \
386 // clone / \ orig
387 // / \
388 // / \
389 // v v
390 // +---->loop clone loop<----+
391 // | | | |
392 // | stmt2 clone stmt2 |
393 // | | | |
394 // | v v |
395 // ^ if clone If ^
396 // | / \ / \ |
397 // | / \ / \ |
398 // | v v v v |
399 // | true false false true |
400 // | / \ / \ |
401 // +---- \ / ----+
402 // \ /
403 // 1v v2
404 // region
405 // |
406 // v
407 // exit
408 //
409 //
410 // after peel and predicate move
411 //
412 // stmt1
413 // /
414 // /
415 // clone / orig
416 // /
417 // / +----------+
418 // / | |
419 // / loop predicate |
420 // / | |
421 // v v |
422 // TOP-->loop clone loop<----+ |
423 // | | | |
424 // stmt2 clone stmt2 | |
425 // | | | ^
426 // v v | |
427 // if clone If ^ |
428 // / \ / \ | |
429 // / \ / \ | |
430 // v v v v | |
431 // true false false true | |
432 // | \ / \ | |
433 // | \ / ----+ ^
434 // | \ / |
435 // | 1v v2 |
436 // v region |
437 // | | |
438 // | v |
439 // | exit |
440 // | |
441 // +--------------->-----------------+
442 //
443 //
444 // final graph
445 //
446 // stmt1
447 // |
448 // v
449 // stmt2 clone
450 // |
451 // v
452 // if clone
453 // / |
454 // / |
455 // v v
456 // false true
457 // | |
458 // | v
459 // | loop predicate
460 // | |
461 // | v
462 // | loop<----+
463 // | | |
464 // | stmt2 |
465 // | | |
466 // | v |
467 // v if ^
468 // | / \ |
469 // | / \ |
470 // | v v |
471 // | false true |
472 // | | \ |
473 // v v --+
474 // region
475 // |
476 // v
477 // exit
478 //
479 void PhaseIdealLoop::do_peeling( IdealLoopTree *loop, Node_List &old_new ) {
480
481 C->set_major_progress();
482 // Peeling a 'main' loop in a pre/main/post situation obfuscates the
483 // 'pre' loop from the main and the 'pre' can no longer have its
484 // iterations adjusted. Therefore, we need to declare this loop as
485 // no longer a 'main' loop; it will need new pre and post loops before
486 // we can do further RCE.
487 #ifndef PRODUCT
488 if (TraceLoopOpts) {
489 tty->print("Peel ");
490 loop->dump_head();
491 }
492 #endif
493 Node* head = loop->_head;
494 bool counted_loop = head->is_CountedLoop();
495 if (counted_loop) {
496 CountedLoopNode *cl = head->as_CountedLoop();
497 assert(cl->trip_count() > 0, "peeling a fully unrolled loop");
498 cl->set_trip_count(cl->trip_count() - 1);
499 if (cl->is_main_loop()) {
500 cl->set_normal_loop();
501 #ifndef PRODUCT
502 if (PrintOpto && VerifyLoopOptimizations) {
503 tty->print("Peeling a 'main' loop; resetting to 'normal' ");
504 loop->dump_head();
505 }
506 #endif
507 }
508 }
509 Node* entry = head->in(LoopNode::EntryControl);
510
511 // Step 1: Clone the loop body. The clone becomes the peeled iteration.
512 // The pre-loop illegally has 2 control users (old & new loops).
513 clone_loop( loop, old_new, dom_depth(head) );
514
515 // Step 2: Make the old-loop fall-in edges point to the peeled iteration.
516 // Do this by making the old-loop fall-in edges act as if they came
517 // around the loopback from the prior iteration (follow the old-loop
518 // backedges) and then map to the new peeled iteration. This leaves
519 // the pre-loop with only 1 user (the new peeled iteration), but the
520 // peeled-loop backedge has 2 users.
521 Node* new_entry = old_new[head->in(LoopNode::LoopBackControl)->_idx];
522 _igvn.hash_delete(head);
523 head->set_req(LoopNode::EntryControl, new_entry);
524 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
525 Node* old = head->fast_out(j);
526 if (old->in(0) == loop->_head && old->req() == 3 && old->is_Phi()) {
527 Node* new_exit_value = old_new[old->in(LoopNode::LoopBackControl)->_idx];
528 if (!new_exit_value ) // Backedge value is ALSO loop invariant?
529 // Then loop body backedge value remains the same.
530 new_exit_value = old->in(LoopNode::LoopBackControl);
531 _igvn.hash_delete(old);
532 old->set_req(LoopNode::EntryControl, new_exit_value);
533 }
534 }
535
536
537 // Step 3: Cut the backedge on the clone (so its not a loop) and remove the
538 // extra backedge user.
539 Node* new_head = old_new[head->_idx];
540 _igvn.hash_delete(new_head);
541 new_head->set_req(LoopNode::LoopBackControl, C->top());
542 for (DUIterator_Fast j2max, j2 = new_head->fast_outs(j2max); j2 < j2max; j2++) {
543 Node* use = new_head->fast_out(j2);
544 if (use->in(0) == new_head && use->req() == 3 && use->is_Phi()) {
545 _igvn.hash_delete(use);
546 use->set_req(LoopNode::LoopBackControl, C->top());
547 }
548 }
549
550
551 // Step 4: Correct dom-depth info. Set to loop-head depth.
552 int dd = dom_depth(head);
553 set_idom(head, head->in(1), dd);
554 for (uint j3 = 0; j3 < loop->_body.size(); j3++) {
555 Node *old = loop->_body.at(j3);
556 Node *nnn = old_new[old->_idx];
557 if (!has_ctrl(nnn))
558 set_idom(nnn, idom(nnn), dd-1);
559 }
560
561 // Now force out all loop-invariant dominating tests. The optimizer
562 // finds some, but we _know_ they are all useless.
563 peeled_dom_test_elim(loop,old_new);
564
565 loop->record_for_igvn();
566 }
567
568 #define EMPTY_LOOP_SIZE 7 // number of nodes in an empty loop
569
570 //------------------------------policy_maximally_unroll------------------------
571 // Calculate exact loop trip count and return true if loop can be maximally
572 // unrolled.
573 bool IdealLoopTree::policy_maximally_unroll( PhaseIdealLoop *phase ) const {
574 CountedLoopNode *cl = _head->as_CountedLoop();
575 assert(cl->is_normal_loop(), "");
576 if (!cl->is_valid_counted_loop())
577 return false; // Malformed counted loop
578
579 if (!cl->has_exact_trip_count()) {
580 // Trip count is not exact.
581 return false;
582 }
583
584 uint trip_count = cl->trip_count();
585 // Note, max_juint is used to indicate unknown trip count.
586 assert(trip_count > 1, "one iteration loop should be optimized out already");
587 assert(trip_count < max_juint, "exact trip_count should be less than max_uint.");
588
589 // Real policy: if we maximally unroll, does it get too big?
590 // Allow the unrolled mess to get larger than standard loop
591 // size. After all, it will no longer be a loop.
592 uint body_size = _body.size();
593 uint unroll_limit = (uint)LoopUnrollLimit * 4;
594 assert( (intx)unroll_limit == LoopUnrollLimit * 4, "LoopUnrollLimit must fit in 32bits");
595 if (trip_count > unroll_limit || body_size > unroll_limit) {
596 return false;
597 }
598
599 // Fully unroll a loop with few iterations regardless next
600 // conditions since following loop optimizations will split
601 // such loop anyway (pre-main-post).
602 if (trip_count <= 3)
603 return true;
604
605 // Take into account that after unroll conjoined heads and tails will fold,
606 // otherwise policy_unroll() may allow more unrolling than max unrolling.
607 uint new_body_size = EMPTY_LOOP_SIZE + (body_size - EMPTY_LOOP_SIZE) * trip_count;
608 uint tst_body_size = (new_body_size - EMPTY_LOOP_SIZE) / trip_count + EMPTY_LOOP_SIZE;
609 if (body_size != tst_body_size) // Check for int overflow
610 return false;
611 if (new_body_size > unroll_limit ||
612 // Unrolling can result in a large amount of node construction
613 new_body_size >= phase->C->max_node_limit() - phase->C->live_nodes()) {
614 return false;
615 }
616
617 // Do not unroll a loop with String intrinsics code.
618 // String intrinsics are large and have loops.
619 for (uint k = 0; k < _body.size(); k++) {
620 Node* n = _body.at(k);
621 switch (n->Opcode()) {
622 case Op_StrComp:
623 case Op_StrEquals:
624 case Op_StrIndexOf:
625 case Op_StrIndexOfChar:
626 case Op_EncodeISOArray:
627 case Op_AryEq:
628 case Op_HasNegatives: {
629 return false;
630 }
631 #if INCLUDE_RTM_OPT
632 case Op_FastLock:
633 case Op_FastUnlock: {
634 // Don't unroll RTM locking code because it is large.
635 if (UseRTMLocking) {
636 return false;
637 }
638 }
639 #endif
640 } // switch
641 }
642
643 return true; // Do maximally unroll
644 }
645
646
647 //------------------------------policy_unroll----------------------------------
648 // Return TRUE or FALSE if the loop should be unrolled or not. Unroll if
649 // the loop is a CountedLoop and the body is small enough.
650 bool IdealLoopTree::policy_unroll(PhaseIdealLoop *phase) {
651
652 CountedLoopNode *cl = _head->as_CountedLoop();
653 assert(cl->is_normal_loop() || cl->is_main_loop(), "");
654
655 if (!cl->is_valid_counted_loop())
656 return false; // Malformed counted loop
657
658 // Protect against over-unrolling.
659 // After split at least one iteration will be executed in pre-loop.
660 if (cl->trip_count() <= (uint)(cl->is_normal_loop() ? 2 : 1)) return false;
661
662 _local_loop_unroll_limit = LoopUnrollLimit;
663 _local_loop_unroll_factor = 4;
664 int future_unroll_ct = cl->unrolled_count() * 2;
665 if (!cl->do_unroll_only()) {
666 if (future_unroll_ct > LoopMaxUnroll) return false;
667 } else {
668 // obey user constraints on vector mapped loops with additional unrolling applied
669 int unroll_constraint = (cl->slp_max_unroll()) ? cl->slp_max_unroll() : 1;
670 if ((future_unroll_ct / unroll_constraint) > LoopMaxUnroll) return false;
671 }
672
673 // Check for initial stride being a small enough constant
674 if (abs(cl->stride_con()) > (1<<2)*future_unroll_ct) return false;
675
676 // Don't unroll if the next round of unrolling would push us
677 // over the expected trip count of the loop. One is subtracted
678 // from the expected trip count because the pre-loop normally
679 // executes 1 iteration.
680 if (UnrollLimitForProfileCheck > 0 &&
681 cl->profile_trip_cnt() != COUNT_UNKNOWN &&
682 future_unroll_ct > UnrollLimitForProfileCheck &&
683 (float)future_unroll_ct > cl->profile_trip_cnt() - 1.0) {
684 return false;
685 }
686
687 // When unroll count is greater than LoopUnrollMin, don't unroll if:
688 // the residual iterations are more than 10% of the trip count
689 // and rounds of "unroll,optimize" are not making significant progress
690 // Progress defined as current size less than 20% larger than previous size.
691 if (UseSuperWord && cl->node_count_before_unroll() > 0 &&
692 future_unroll_ct > LoopUnrollMin &&
693 (future_unroll_ct - 1) * (100 / LoopPercentProfileLimit) > cl->profile_trip_cnt() &&
694 1.2 * cl->node_count_before_unroll() < (double)_body.size()) {
695 return false;
696 }
697
698 Node *init_n = cl->init_trip();
699 Node *limit_n = cl->limit();
700 int stride_con = cl->stride_con();
701 // Non-constant bounds.
702 // Protect against over-unrolling when init or/and limit are not constant
703 // (so that trip_count's init value is maxint) but iv range is known.
704 if (init_n == NULL || !init_n->is_Con() ||
705 limit_n == NULL || !limit_n->is_Con()) {
706 Node* phi = cl->phi();
707 if (phi != NULL) {
708 assert(phi->is_Phi() && phi->in(0) == _head, "Counted loop should have iv phi.");
709 const TypeInt* iv_type = phase->_igvn.type(phi)->is_int();
710 int next_stride = stride_con * 2; // stride after this unroll
711 if (next_stride > 0) {
712 if (iv_type->_lo + next_stride <= iv_type->_lo || // overflow
713 iv_type->_lo + next_stride > iv_type->_hi) {
714 return false; // over-unrolling
715 }
716 } else if (next_stride < 0) {
717 if (iv_type->_hi + next_stride >= iv_type->_hi || // overflow
718 iv_type->_hi + next_stride < iv_type->_lo) {
719 return false; // over-unrolling
720 }
721 }
722 }
723 }
724
725 // After unroll limit will be adjusted: new_limit = limit-stride.
726 // Bailout if adjustment overflow.
727 const TypeInt* limit_type = phase->_igvn.type(limit_n)->is_int();
728 if (stride_con > 0 && ((limit_type->_hi - stride_con) >= limit_type->_hi) ||
729 stride_con < 0 && ((limit_type->_lo - stride_con) <= limit_type->_lo))
730 return false; // overflow
731
732 // Adjust body_size to determine if we unroll or not
733 uint body_size = _body.size();
734 // Key test to unroll loop in CRC32 java code
735 int xors_in_loop = 0;
736 // Also count ModL, DivL and MulL which expand mightly
737 for (uint k = 0; k < _body.size(); k++) {
738 Node* n = _body.at(k);
739 switch (n->Opcode()) {
740 case Op_XorI: xors_in_loop++; break; // CRC32 java code
741 case Op_ModL: body_size += 30; break;
742 case Op_DivL: body_size += 30; break;
743 case Op_MulL: body_size += 10; break;
744 case Op_StrComp:
745 case Op_StrEquals:
746 case Op_StrIndexOf:
747 case Op_StrIndexOfChar:
748 case Op_EncodeISOArray:
749 case Op_AryEq:
750 case Op_HasNegatives: {
751 // Do not unroll a loop with String intrinsics code.
752 // String intrinsics are large and have loops.
753 return false;
754 }
755 #if INCLUDE_RTM_OPT
756 case Op_FastLock:
757 case Op_FastUnlock: {
758 // Don't unroll RTM locking code because it is large.
759 if (UseRTMLocking) {
760 return false;
761 }
762 }
763 #endif
764 } // switch
765 }
766
767 if (UseSuperWord) {
768 if (!cl->is_reduction_loop()) {
769 phase->mark_reductions(this);
770 }
771
772 // Only attempt slp analysis when user controls do not prohibit it
773 if (LoopMaxUnroll > _local_loop_unroll_factor) {
774 // Once policy_slp_analysis succeeds, mark the loop with the
775 // maximal unroll factor so that we minimize analysis passes
776 if (future_unroll_ct >= _local_loop_unroll_factor) {
777 policy_unroll_slp_analysis(cl, phase, future_unroll_ct);
778 }
779 }
780 }
781
782 int slp_max_unroll_factor = cl->slp_max_unroll();
783 if (cl->has_passed_slp()) {
784 if (slp_max_unroll_factor >= future_unroll_ct) return true;
785 // Normal case: loop too big
786 return false;
787 }
788
789 // Check for being too big
790 if (body_size > (uint)_local_loop_unroll_limit) {
791 if (xors_in_loop >= 4 && body_size < (uint)LoopUnrollLimit*4) return true;
792 // Normal case: loop too big
793 return false;
794 }
795
796 if (cl->do_unroll_only()) {
797 if (TraceSuperWordLoopUnrollAnalysis) {
798 tty->print_cr("policy_unroll passed vector loop(vlen=%d,factor = %d)\n", slp_max_unroll_factor, future_unroll_ct);
799 }
800 }
801
802 // Unroll once! (Each trip will soon do double iterations)
803 return true;
804 }
805
806 void IdealLoopTree::policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_ct) {
807 // Enable this functionality target by target as needed
808 if (SuperWordLoopUnrollAnalysis) {
809 if (!cl->was_slp_analyzed()) {
810 SuperWord sw(phase);
811 sw.transform_loop(this, false);
812
813 // If the loop is slp canonical analyze it
814 if (sw.early_return() == false) {
815 sw.unrolling_analysis(_local_loop_unroll_factor);
816 }
817 }
818
819 if (cl->has_passed_slp()) {
820 int slp_max_unroll_factor = cl->slp_max_unroll();
821 if (slp_max_unroll_factor >= future_unroll_ct) {
822 int new_limit = cl->node_count_before_unroll() * slp_max_unroll_factor;
823 if (new_limit > LoopUnrollLimit) {
824 if (TraceSuperWordLoopUnrollAnalysis) {
825 tty->print_cr("slp analysis unroll=%d, default limit=%d\n", new_limit, _local_loop_unroll_limit);
826 }
827 _local_loop_unroll_limit = new_limit;
828 }
829 }
830 }
831 }
832 }
833
834 //------------------------------policy_align-----------------------------------
835 // Return TRUE or FALSE if the loop should be cache-line aligned. Gather the
836 // expression that does the alignment. Note that only one array base can be
837 // aligned in a loop (unless the VM guarantees mutual alignment). Note that
838 // if we vectorize short memory ops into longer memory ops, we may want to
839 // increase alignment.
840 bool IdealLoopTree::policy_align( PhaseIdealLoop *phase ) const {
841 return false;
842 }
843
844 //------------------------------policy_range_check-----------------------------
845 // Return TRUE or FALSE if the loop should be range-check-eliminated.
846 // Actually we do iteration-splitting, a more powerful form of RCE.
847 bool IdealLoopTree::policy_range_check( PhaseIdealLoop *phase ) const {
848 if (!RangeCheckElimination) return false;
849
850 CountedLoopNode *cl = _head->as_CountedLoop();
851 // If we unrolled with no intention of doing RCE and we later
852 // changed our minds, we got no pre-loop. Either we need to
853 // make a new pre-loop, or we gotta disallow RCE.
854 if (cl->is_main_no_pre_loop()) return false; // Disallowed for now.
855 Node *trip_counter = cl->phi();
856
857 // check for vectorized loops, some opts are no longer needed
858 if (cl->do_unroll_only()) return false;
859
860 // Check loop body for tests of trip-counter plus loop-invariant vs
861 // loop-invariant.
862 for (uint i = 0; i < _body.size(); i++) {
863 Node *iff = _body[i];
864 if (iff->Opcode() == Op_If ||
865 iff->Opcode() == Op_RangeCheck) { // Test?
866
867 // Comparing trip+off vs limit
868 Node *bol = iff->in(1);
869 if (bol->req() != 2) continue; // dead constant test
870 if (!bol->is_Bool()) {
871 assert(UseLoopPredicate && bol->Opcode() == Op_Conv2B, "predicate check only");
872 continue;
873 }
874 if (bol->as_Bool()->_test._test == BoolTest::ne)
875 continue; // not RC
876
877 Node *cmp = bol->in(1);
878 Node *rc_exp = cmp->in(1);
879 Node *limit = cmp->in(2);
880
881 Node *limit_c = phase->get_ctrl(limit);
882 if( limit_c == phase->C->top() )
883 return false; // Found dead test on live IF? No RCE!
884 if( is_member(phase->get_loop(limit_c) ) ) {
885 // Compare might have operands swapped; commute them
886 rc_exp = cmp->in(2);
887 limit = cmp->in(1);
888 limit_c = phase->get_ctrl(limit);
889 if( is_member(phase->get_loop(limit_c) ) )
890 continue; // Both inputs are loop varying; cannot RCE
891 }
892
893 if (!phase->is_scaled_iv_plus_offset(rc_exp, trip_counter, NULL, NULL)) {
894 continue;
895 }
896 // Yeah! Found a test like 'trip+off vs limit'
897 // Test is an IfNode, has 2 projections. If BOTH are in the loop
898 // we need loop unswitching instead of iteration splitting.
899 if( is_loop_exit(iff) )
900 return true; // Found reason to split iterations
901 } // End of is IF
902 }
903
904 return false;
905 }
906
907 //------------------------------policy_peel_only-------------------------------
908 // Return TRUE or FALSE if the loop should NEVER be RCE'd or aligned. Useful
909 // for unrolling loops with NO array accesses.
910 bool IdealLoopTree::policy_peel_only( PhaseIdealLoop *phase ) const {
911 // check for vectorized loops, any peeling done was already applied
912 if (_head->is_CountedLoop() && _head->as_CountedLoop()->do_unroll_only()) return false;
913
914 for( uint i = 0; i < _body.size(); i++ )
915 if( _body[i]->is_Mem() )
916 return false;
917
918 // No memory accesses at all!
919 return true;
920 }
921
922 //------------------------------clone_up_backedge_goo--------------------------
923 // If Node n lives in the back_ctrl block and cannot float, we clone a private
924 // version of n in preheader_ctrl block and return that, otherwise return n.
925 Node *PhaseIdealLoop::clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones ) {
926 if( get_ctrl(n) != back_ctrl ) return n;
927
928 // Only visit once
929 if (visited.test_set(n->_idx)) {
930 Node *x = clones.find(n->_idx);
931 if (x != NULL)
932 return x;
933 return n;
934 }
935
936 Node *x = NULL; // If required, a clone of 'n'
937 // Check for 'n' being pinned in the backedge.
938 if( n->in(0) && n->in(0) == back_ctrl ) {
939 assert(clones.find(n->_idx) == NULL, "dead loop");
940 x = n->clone(); // Clone a copy of 'n' to preheader
941 clones.push(x, n->_idx);
942 x->set_req( 0, preheader_ctrl ); // Fix x's control input to preheader
943 }
944
945 // Recursive fixup any other input edges into x.
946 // If there are no changes we can just return 'n', otherwise
947 // we need to clone a private copy and change it.
948 for( uint i = 1; i < n->req(); i++ ) {
949 Node *g = clone_up_backedge_goo( back_ctrl, preheader_ctrl, n->in(i), visited, clones );
950 if( g != n->in(i) ) {
951 if( !x ) {
952 assert(clones.find(n->_idx) == NULL, "dead loop");
953 x = n->clone();
954 clones.push(x, n->_idx);
955 }
956 x->set_req(i, g);
957 }
958 }
959 if( x ) { // x can legally float to pre-header location
960 register_new_node( x, preheader_ctrl );
961 return x;
962 } else { // raise n to cover LCA of uses
963 set_ctrl( n, find_non_split_ctrl(back_ctrl->in(0)) );
964 }
965 return n;
966 }
967
968 bool PhaseIdealLoop::cast_incr_before_loop(Node* incr, Node* ctrl, Node* loop) {
969 Node* castii = new CastIINode(incr, TypeInt::INT, true);
970 castii->set_req(0, ctrl);
971 register_new_node(castii, ctrl);
972 for (DUIterator_Fast imax, i = incr->fast_outs(imax); i < imax; i++) {
973 Node* n = incr->fast_out(i);
974 if (n->is_Phi() && n->in(0) == loop) {
975 int nrep = n->replace_edge(incr, castii);
976 return true;
977 }
978 }
979 return false;
980 }
981
982 //------------------------------insert_pre_post_loops--------------------------
983 // Insert pre and post loops. If peel_only is set, the pre-loop can not have
984 // more iterations added. It acts as a 'peel' only, no lower-bound RCE, no
985 // alignment. Useful to unroll loops that do no array accesses.
986 void PhaseIdealLoop::insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only ) {
987
988 #ifndef PRODUCT
989 if (TraceLoopOpts) {
990 if (peel_only)
991 tty->print("PeelMainPost ");
992 else
993 tty->print("PreMainPost ");
994 loop->dump_head();
995 }
996 #endif
997 C->set_major_progress();
998
999 // Find common pieces of the loop being guarded with pre & post loops
1000 CountedLoopNode *main_head = loop->_head->as_CountedLoop();
1001 assert( main_head->is_normal_loop(), "" );
1002 CountedLoopEndNode *main_end = main_head->loopexit();
1003 guarantee(main_end != NULL, "no loop exit node");
1004 assert( main_end->outcnt() == 2, "1 true, 1 false path only" );
1005 uint dd_main_head = dom_depth(main_head);
1006 uint max = main_head->outcnt();
1007
1008 Node *pre_header= main_head->in(LoopNode::EntryControl);
1009 Node *init = main_head->init_trip();
1010 Node *incr = main_end ->incr();
1011 Node *limit = main_end ->limit();
1012 Node *stride = main_end ->stride();
1013 Node *cmp = main_end ->cmp_node();
1014 BoolTest::mask b_test = main_end->test_trip();
1015
1016 // Need only 1 user of 'bol' because I will be hacking the loop bounds.
1017 Node *bol = main_end->in(CountedLoopEndNode::TestValue);
1018 if( bol->outcnt() != 1 ) {
1019 bol = bol->clone();
1020 register_new_node(bol,main_end->in(CountedLoopEndNode::TestControl));
1021 _igvn.replace_input_of(main_end, CountedLoopEndNode::TestValue, bol);
1022 }
1023 // Need only 1 user of 'cmp' because I will be hacking the loop bounds.
1024 if( cmp->outcnt() != 1 ) {
1025 cmp = cmp->clone();
1026 register_new_node(cmp,main_end->in(CountedLoopEndNode::TestControl));
1027 _igvn.replace_input_of(bol, 1, cmp);
1028 }
1029
1030 //------------------------------
1031 // Step A: Create Post-Loop.
1032 Node* main_exit = main_end->proj_out(false);
1033 assert( main_exit->Opcode() == Op_IfFalse, "" );
1034 int dd_main_exit = dom_depth(main_exit);
1035
1036 // Step A1: Clone the loop body. The clone becomes the post-loop. The main
1037 // loop pre-header illegally has 2 control users (old & new loops).
1038 clone_loop( loop, old_new, dd_main_exit );
1039 assert( old_new[main_end ->_idx]->Opcode() == Op_CountedLoopEnd, "" );
1040 CountedLoopNode *post_head = old_new[main_head->_idx]->as_CountedLoop();
1041 post_head->set_post_loop(main_head);
1042
1043 // Reduce the post-loop trip count.
1044 CountedLoopEndNode* post_end = old_new[main_end ->_idx]->as_CountedLoopEnd();
1045 post_end->_prob = PROB_FAIR;
1046
1047 // Build the main-loop normal exit.
1048 IfFalseNode *new_main_exit = new IfFalseNode(main_end);
1049 _igvn.register_new_node_with_optimizer( new_main_exit );
1050 set_idom(new_main_exit, main_end, dd_main_exit );
1051 set_loop(new_main_exit, loop->_parent);
1052
1053 // Step A2: Build a zero-trip guard for the post-loop. After leaving the
1054 // main-loop, the post-loop may not execute at all. We 'opaque' the incr
1055 // (the main-loop trip-counter exit value) because we will be changing
1056 // the exit value (via unrolling) so we cannot constant-fold away the zero
1057 // trip guard until all unrolling is done.
1058 Node *zer_opaq = new Opaque1Node(C, incr);
1059 Node *zer_cmp = new CmpINode( zer_opaq, limit );
1060 Node *zer_bol = new BoolNode( zer_cmp, b_test );
1061 register_new_node( zer_opaq, new_main_exit );
1062 register_new_node( zer_cmp , new_main_exit );
1063 register_new_node( zer_bol , new_main_exit );
1064
1065 // Build the IfNode
1066 IfNode *zer_iff = new IfNode( new_main_exit, zer_bol, PROB_FAIR, COUNT_UNKNOWN );
1067 _igvn.register_new_node_with_optimizer( zer_iff );
1068 set_idom(zer_iff, new_main_exit, dd_main_exit);
1069 set_loop(zer_iff, loop->_parent);
1070
1071 // Plug in the false-path, taken if we need to skip post-loop
1072 _igvn.replace_input_of(main_exit, 0, zer_iff);
1073 set_idom(main_exit, zer_iff, dd_main_exit);
1074 set_idom(main_exit->unique_out(), zer_iff, dd_main_exit);
1075 // Make the true-path, must enter the post loop
1076 Node *zer_taken = new IfTrueNode( zer_iff );
1077 _igvn.register_new_node_with_optimizer( zer_taken );
1078 set_idom(zer_taken, zer_iff, dd_main_exit);
1079 set_loop(zer_taken, loop->_parent);
1080 // Plug in the true path
1081 _igvn.hash_delete( post_head );
1082 post_head->set_req(LoopNode::EntryControl, zer_taken);
1083 set_idom(post_head, zer_taken, dd_main_exit);
1084
1085 Arena *a = Thread::current()->resource_area();
1086 VectorSet visited(a);
1087 Node_Stack clones(a, main_head->back_control()->outcnt());
1088 // Step A3: Make the fall-in values to the post-loop come from the
1089 // fall-out values of the main-loop.
1090 for (DUIterator_Fast imax, i = main_head->fast_outs(imax); i < imax; i++) {
1091 Node* main_phi = main_head->fast_out(i);
1092 if( main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() >0 ) {
1093 Node *post_phi = old_new[main_phi->_idx];
1094 Node *fallmain = clone_up_backedge_goo(main_head->back_control(),
1095 post_head->init_control(),
1096 main_phi->in(LoopNode::LoopBackControl),
1097 visited, clones);
1098 _igvn.hash_delete(post_phi);
1099 post_phi->set_req( LoopNode::EntryControl, fallmain );
1100 }
1101 }
1102
1103 // Update local caches for next stanza
1104 main_exit = new_main_exit;
1105
1106
1107 //------------------------------
1108 // Step B: Create Pre-Loop.
1109
1110 // Step B1: Clone the loop body. The clone becomes the pre-loop. The main
1111 // loop pre-header illegally has 2 control users (old & new loops).
1112 clone_loop( loop, old_new, dd_main_head );
1113 CountedLoopNode* pre_head = old_new[main_head->_idx]->as_CountedLoop();
1114 CountedLoopEndNode* pre_end = old_new[main_end ->_idx]->as_CountedLoopEnd();
1115 pre_head->set_pre_loop(main_head);
1116 Node *pre_incr = old_new[incr->_idx];
1117
1118 // Reduce the pre-loop trip count.
1119 pre_end->_prob = PROB_FAIR;
1120
1121 // Find the pre-loop normal exit.
1122 Node* pre_exit = pre_end->proj_out(false);
1123 assert( pre_exit->Opcode() == Op_IfFalse, "" );
1124 IfFalseNode *new_pre_exit = new IfFalseNode(pre_end);
1125 _igvn.register_new_node_with_optimizer( new_pre_exit );
1126 set_idom(new_pre_exit, pre_end, dd_main_head);
1127 set_loop(new_pre_exit, loop->_parent);
1128
1129 // Step B2: Build a zero-trip guard for the main-loop. After leaving the
1130 // pre-loop, the main-loop may not execute at all. Later in life this
1131 // zero-trip guard will become the minimum-trip guard when we unroll
1132 // the main-loop.
1133 Node *min_opaq = new Opaque1Node(C, limit);
1134 Node *min_cmp = new CmpINode( pre_incr, min_opaq );
1135 Node *min_bol = new BoolNode( min_cmp, b_test );
1136 register_new_node( min_opaq, new_pre_exit );
1137 register_new_node( min_cmp , new_pre_exit );
1138 register_new_node( min_bol , new_pre_exit );
1139
1140 // Build the IfNode (assume the main-loop is executed always).
1141 IfNode *min_iff = new IfNode( new_pre_exit, min_bol, PROB_ALWAYS, COUNT_UNKNOWN );
1142 _igvn.register_new_node_with_optimizer( min_iff );
1143 set_idom(min_iff, new_pre_exit, dd_main_head);
1144 set_loop(min_iff, loop->_parent);
1145
1146 // Plug in the false-path, taken if we need to skip main-loop
1147 _igvn.hash_delete( pre_exit );
1148 pre_exit->set_req(0, min_iff);
1149 set_idom(pre_exit, min_iff, dd_main_head);
1150 set_idom(pre_exit->unique_out(), min_iff, dd_main_head);
1151 // Make the true-path, must enter the main loop
1152 Node *min_taken = new IfTrueNode( min_iff );
1153 _igvn.register_new_node_with_optimizer( min_taken );
1154 set_idom(min_taken, min_iff, dd_main_head);
1155 set_loop(min_taken, loop->_parent);
1156 // Plug in the true path
1157 _igvn.hash_delete( main_head );
1158 main_head->set_req(LoopNode::EntryControl, min_taken);
1159 set_idom(main_head, min_taken, dd_main_head);
1160
1161 visited.Clear();
1162 clones.clear();
1163 // Step B3: Make the fall-in values to the main-loop come from the
1164 // fall-out values of the pre-loop.
1165 for (DUIterator_Fast i2max, i2 = main_head->fast_outs(i2max); i2 < i2max; i2++) {
1166 Node* main_phi = main_head->fast_out(i2);
1167 if( main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() > 0 ) {
1168 Node *pre_phi = old_new[main_phi->_idx];
1169 Node *fallpre = clone_up_backedge_goo(pre_head->back_control(),
1170 main_head->init_control(),
1171 pre_phi->in(LoopNode::LoopBackControl),
1172 visited, clones);
1173 _igvn.hash_delete(main_phi);
1174 main_phi->set_req( LoopNode::EntryControl, fallpre );
1175 }
1176 }
1177
1178 // Nodes inside the loop may be control dependent on a predicate
1179 // that was moved before the preloop. If the back branch of the main
1180 // or post loops becomes dead, those nodes won't be dependent on the
1181 // test that guards that loop nest anymore which could lead to an
1182 // incorrect array access because it executes independently of the
1183 // test that was guarding the loop nest. We add a special CastII on
1184 // the if branch that enters the loop, between the input induction
1185 // variable value and the induction variable Phi to preserve correct
1186 // dependencies.
1187
1188 // CastII for the post loop:
1189 bool inserted = cast_incr_before_loop(zer_opaq->in(1), zer_taken, post_head);
1190 assert(inserted, "no castII inserted");
1191
1192 // CastII for the main loop:
1193 inserted = cast_incr_before_loop(pre_incr, min_taken, main_head);
1194 assert(inserted, "no castII inserted");
1195
1196 // Step B4: Shorten the pre-loop to run only 1 iteration (for now).
1197 // RCE and alignment may change this later.
1198 Node *cmp_end = pre_end->cmp_node();
1199 assert( cmp_end->in(2) == limit, "" );
1200 Node *pre_limit = new AddINode( init, stride );
1201
1202 // Save the original loop limit in this Opaque1 node for
1203 // use by range check elimination.
1204 Node *pre_opaq = new Opaque1Node(C, pre_limit, limit);
1205
1206 register_new_node( pre_limit, pre_head->in(0) );
1207 register_new_node( pre_opaq , pre_head->in(0) );
1208
1209 // Since no other users of pre-loop compare, I can hack limit directly
1210 assert( cmp_end->outcnt() == 1, "no other users" );
1211 _igvn.hash_delete(cmp_end);
1212 cmp_end->set_req(2, peel_only ? pre_limit : pre_opaq);
1213
1214 // Special case for not-equal loop bounds:
1215 // Change pre loop test, main loop test, and the
1216 // main loop guard test to use lt or gt depending on stride
1217 // direction:
1218 // positive stride use <
1219 // negative stride use >
1220 //
1221 // not-equal test is kept for post loop to handle case
1222 // when init > limit when stride > 0 (and reverse).
1223
1224 if (pre_end->in(CountedLoopEndNode::TestValue)->as_Bool()->_test._test == BoolTest::ne) {
1225
1226 BoolTest::mask new_test = (main_end->stride_con() > 0) ? BoolTest::lt : BoolTest::gt;
1227 // Modify pre loop end condition
1228 Node* pre_bol = pre_end->in(CountedLoopEndNode::TestValue)->as_Bool();
1229 BoolNode* new_bol0 = new BoolNode(pre_bol->in(1), new_test);
1230 register_new_node( new_bol0, pre_head->in(0) );
1231 _igvn.replace_input_of(pre_end, CountedLoopEndNode::TestValue, new_bol0);
1232 // Modify main loop guard condition
1233 assert(min_iff->in(CountedLoopEndNode::TestValue) == min_bol, "guard okay");
1234 BoolNode* new_bol1 = new BoolNode(min_bol->in(1), new_test);
1235 register_new_node( new_bol1, new_pre_exit );
1236 _igvn.hash_delete(min_iff);
1237 min_iff->set_req(CountedLoopEndNode::TestValue, new_bol1);
1238 // Modify main loop end condition
1239 BoolNode* main_bol = main_end->in(CountedLoopEndNode::TestValue)->as_Bool();
1240 BoolNode* new_bol2 = new BoolNode(main_bol->in(1), new_test);
1241 register_new_node( new_bol2, main_end->in(CountedLoopEndNode::TestControl) );
1242 _igvn.replace_input_of(main_end, CountedLoopEndNode::TestValue, new_bol2);
1243 }
1244
1245 // Flag main loop
1246 main_head->set_main_loop();
1247 if( peel_only ) main_head->set_main_no_pre_loop();
1248
1249 // Subtract a trip count for the pre-loop.
1250 main_head->set_trip_count(main_head->trip_count() - 1);
1251
1252 // It's difficult to be precise about the trip-counts
1253 // for the pre/post loops. They are usually very short,
1254 // so guess that 4 trips is a reasonable value.
1255 post_head->set_profile_trip_cnt(4.0);
1256 pre_head->set_profile_trip_cnt(4.0);
1257
1258 // Now force out all loop-invariant dominating tests. The optimizer
1259 // finds some, but we _know_ they are all useless.
1260 peeled_dom_test_elim(loop,old_new);
1261 loop->record_for_igvn();
1262 }
1263
1264 //------------------------------insert_vector_post_loop------------------------
1265 // Insert a copy of the atomic unrolled vectorized main loop as a post loop,
1266 // unroll_policy has already informed us that more unrolling is about to happen to
1267 // the main loop. The resultant post loop will serve as a vectorized drain loop.
1268 void PhaseIdealLoop::insert_vector_post_loop(IdealLoopTree *loop, Node_List &old_new) {
1269 if (!loop->_head->is_CountedLoop()) return;
1270
1271 CountedLoopNode *cl = loop->_head->as_CountedLoop();
1272
1273 // only process vectorized main loops
1274 if (!cl->is_vectorized_loop() || !cl->is_main_loop()) return;
1275
1276 int slp_max_unroll_factor = cl->slp_max_unroll();
1277 int cur_unroll = cl->unrolled_count();
1278
1279 if (slp_max_unroll_factor == 0) return;
1280
1281 // only process atomic unroll vector loops (not super unrolled after vectorization)
1282 if (cur_unroll != slp_max_unroll_factor) return;
1283
1284 // we only ever process this one time
1285 if (cl->has_atomic_post_loop()) return;
1286
1287 #ifndef PRODUCT
1288 if (TraceLoopOpts) {
1289 tty->print("PostVector ");
1290 loop->dump_head();
1291 }
1292 #endif
1293 C->set_major_progress();
1294
1295 // Find common pieces of the loop being guarded with pre & post loops
1296 CountedLoopNode *main_head = loop->_head->as_CountedLoop();
1297 CountedLoopEndNode *main_end = main_head->loopexit();
1298 guarantee(main_end != NULL, "no loop exit node");
1299 // diagnostic to show loop end is not properly formed
1300 assert(main_end->outcnt() == 2, "1 true, 1 false path only");
1301 uint dd_main_head = dom_depth(main_head);
1302 uint max = main_head->outcnt();
1303
1304 // mark this loop as processed
1305 main_head->mark_has_atomic_post_loop();
1306
1307 Node *pre_header = main_head->in(LoopNode::EntryControl);
1308 Node *init = main_head->init_trip();
1309 Node *incr = main_end->incr();
1310 Node *limit = main_end->limit();
1311 Node *stride = main_end->stride();
1312 Node *cmp = main_end->cmp_node();
1313 BoolTest::mask b_test = main_end->test_trip();
1314
1315 //------------------------------
1316 // Step A: Create a new post-Loop.
1317 Node* main_exit = main_end->proj_out(false);
1318 assert(main_exit->Opcode() == Op_IfFalse, "");
1319 int dd_main_exit = dom_depth(main_exit);
1320
1321 // Step A1: Clone the loop body of main. The clone becomes the vector post-loop.
1322 // The main loop pre-header illegally has 2 control users (old & new loops).
1323 clone_loop(loop, old_new, dd_main_exit);
1324 assert(old_new[main_end->_idx]->Opcode() == Op_CountedLoopEnd, "");
1325 CountedLoopNode *post_head = old_new[main_head->_idx]->as_CountedLoop();
1326 post_head->set_normal_loop();
1327 post_head->set_post_loop(main_head);
1328
1329 // Reduce the post-loop trip count.
1330 CountedLoopEndNode* post_end = old_new[main_end->_idx]->as_CountedLoopEnd();
1331 post_end->_prob = PROB_FAIR;
1332
1333 // Build the main-loop normal exit.
1334 IfFalseNode *new_main_exit = new IfFalseNode(main_end);
1335 _igvn.register_new_node_with_optimizer(new_main_exit);
1336 set_idom(new_main_exit, main_end, dd_main_exit);
1337 set_loop(new_main_exit, loop->_parent);
1338
1339 // Step A2: Build a zero-trip guard for the vector post-loop. After leaving the
1340 // main-loop, the vector post-loop may not execute at all. We 'opaque' the incr
1341 // (the vectorized main-loop trip-counter exit value) because we will be changing
1342 // the exit value (via additional unrolling) so we cannot constant-fold away the zero
1343 // trip guard until all unrolling is done.
1344 Node *zer_opaq = new Opaque1Node(C, incr);
1345 Node *zer_cmp = new CmpINode(zer_opaq, limit);
1346 Node *zer_bol = new BoolNode(zer_cmp, b_test);
1347 register_new_node(zer_opaq, new_main_exit);
1348 register_new_node(zer_cmp, new_main_exit);
1349 register_new_node(zer_bol, new_main_exit);
1350
1351 // Build the IfNode
1352 IfNode *zer_iff = new IfNode(new_main_exit, zer_bol, PROB_FAIR, COUNT_UNKNOWN);
1353 _igvn.register_new_node_with_optimizer(zer_iff);
1354 set_idom(zer_iff, new_main_exit, dd_main_exit);
1355 set_loop(zer_iff, loop->_parent);
1356
1357 // Plug in the false-path, taken if we need to skip vector post-loop
1358 _igvn.replace_input_of(main_exit, 0, zer_iff);
1359 set_idom(main_exit, zer_iff, dd_main_exit);
1360 set_idom(main_exit->unique_out(), zer_iff, dd_main_exit);
1361 // Make the true-path, must enter the vector post loop
1362 Node *zer_taken = new IfTrueNode(zer_iff);
1363 _igvn.register_new_node_with_optimizer(zer_taken);
1364 set_idom(zer_taken, zer_iff, dd_main_exit);
1365 set_loop(zer_taken, loop->_parent);
1366 // Plug in the true path
1367 _igvn.hash_delete(post_head);
1368 post_head->set_req(LoopNode::EntryControl, zer_taken);
1369 set_idom(post_head, zer_taken, dd_main_exit);
1370
1371 Arena *a = Thread::current()->resource_area();
1372 VectorSet visited(a);
1373 Node_Stack clones(a, main_head->back_control()->outcnt());
1374 // Step A3: Make the fall-in values to the vector post-loop come from the
1375 // fall-out values of the main-loop.
1376 for (DUIterator_Fast imax, i = main_head->fast_outs(imax); i < imax; i++) {
1377 Node* main_phi = main_head->fast_out(i);
1378 if (main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() >0) {
1379 Node *cur_phi = old_new[main_phi->_idx];
1380 Node *fallnew = clone_up_backedge_goo(main_head->back_control(),
1381 post_head->init_control(),
1382 main_phi->in(LoopNode::LoopBackControl),
1383 visited, clones);
1384 _igvn.hash_delete(cur_phi);
1385 cur_phi->set_req(LoopNode::EntryControl, fallnew);
1386 }
1387 }
1388
1389 // CastII for the new post loop:
1390 bool inserted = cast_incr_before_loop(zer_opaq->in(1), zer_taken, post_head);
1391 assert(inserted, "no castII inserted");
1392
1393 // It's difficult to be precise about the trip-counts
1394 // for post loops. They are usually very short,
1395 // so guess that unit vector trips is a reasonable value.
1396 post_head->set_profile_trip_cnt((float)slp_max_unroll_factor);
1397
1398 // Now force out all loop-invariant dominating tests. The optimizer
1399 // finds some, but we _know_ they are all useless.
1400 peeled_dom_test_elim(loop, old_new);
1401 loop->record_for_igvn();
1402 }
1403
1404 //------------------------------is_invariant-----------------------------
1405 // Return true if n is invariant
1406 bool IdealLoopTree::is_invariant(Node* n) const {
1407 Node *n_c = _phase->has_ctrl(n) ? _phase->get_ctrl(n) : n;
1408 if (n_c->is_top()) return false;
1409 return !is_member(_phase->get_loop(n_c));
1410 }
1411
1412
1413 //------------------------------do_unroll--------------------------------------
1414 // Unroll the loop body one step - make each trip do 2 iterations.
1415 void PhaseIdealLoop::do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip ) {
1416 assert(LoopUnrollLimit, "");
1417 CountedLoopNode *loop_head = loop->_head->as_CountedLoop();
1418 CountedLoopEndNode *loop_end = loop_head->loopexit();
1419 assert(loop_end, "");
1420 #ifndef PRODUCT
1421 if (PrintOpto && VerifyLoopOptimizations) {
1422 tty->print("Unrolling ");
1423 loop->dump_head();
1424 } else if (TraceLoopOpts) {
1425 if (loop_head->trip_count() < (uint)LoopUnrollLimit) {
1426 tty->print("Unroll %d(%2d) ", loop_head->unrolled_count()*2, loop_head->trip_count());
1427 } else {
1428 tty->print("Unroll %d ", loop_head->unrolled_count()*2);
1429 }
1430 loop->dump_head();
1431 }
1432
1433 if (C->do_vector_loop() && (PrintOpto && VerifyLoopOptimizations || TraceLoopOpts)) {
1434 Arena* arena = Thread::current()->resource_area();
1435 Node_Stack stack(arena, C->live_nodes() >> 2);
1436 Node_List rpo_list;
1437 VectorSet visited(arena);
1438 visited.set(loop_head->_idx);
1439 rpo( loop_head, stack, visited, rpo_list );
1440 dump(loop, rpo_list.size(), rpo_list );
1441 }
1442 #endif
1443
1444 // Remember loop node count before unrolling to detect
1445 // if rounds of unroll,optimize are making progress
1446 loop_head->set_node_count_before_unroll(loop->_body.size());
1447
1448 Node *ctrl = loop_head->in(LoopNode::EntryControl);
1449 Node *limit = loop_head->limit();
1450 Node *init = loop_head->init_trip();
1451 Node *stride = loop_head->stride();
1452
1453 Node *opaq = NULL;
1454 if (adjust_min_trip) { // If not maximally unrolling, need adjustment
1455 // Search for zero-trip guard.
1456 assert( loop_head->is_main_loop(), "" );
1457 assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" );
1458 Node *iff = ctrl->in(0);
1459 assert( iff->Opcode() == Op_If, "" );
1460 Node *bol = iff->in(1);
1461 assert( bol->Opcode() == Op_Bool, "" );
1462 Node *cmp = bol->in(1);
1463 assert( cmp->Opcode() == Op_CmpI, "" );
1464 opaq = cmp->in(2);
1465 // Occasionally it's possible for a zero-trip guard Opaque1 node to be
1466 // optimized away and then another round of loop opts attempted.
1467 // We can not optimize this particular loop in that case.
1468 if (opaq->Opcode() != Op_Opaque1)
1469 return; // Cannot find zero-trip guard! Bail out!
1470 // Zero-trip test uses an 'opaque' node which is not shared.
1471 assert(opaq->outcnt() == 1 && opaq->in(1) == limit, "");
1472 }
1473
1474 C->set_major_progress();
1475
1476 Node* new_limit = NULL;
1477 if (UnrollLimitCheck) {
1478 int stride_con = stride->get_int();
1479 int stride_p = (stride_con > 0) ? stride_con : -stride_con;
1480 uint old_trip_count = loop_head->trip_count();
1481 // Verify that unroll policy result is still valid.
1482 assert(old_trip_count > 1 &&
1483 (!adjust_min_trip || stride_p <= (1<<3)*loop_head->unrolled_count()), "sanity");
1484
1485 // Adjust loop limit to keep valid iterations number after unroll.
1486 // Use (limit - stride) instead of (((limit - init)/stride) & (-2))*stride
1487 // which may overflow.
1488 if (!adjust_min_trip) {
1489 assert(old_trip_count > 1 && (old_trip_count & 1) == 0,
1490 "odd trip count for maximally unroll");
1491 // Don't need to adjust limit for maximally unroll since trip count is even.
1492 } else if (loop_head->has_exact_trip_count() && init->is_Con()) {
1493 // Loop's limit is constant. Loop's init could be constant when pre-loop
1494 // become peeled iteration.
1495 jlong init_con = init->get_int();
1496 // We can keep old loop limit if iterations count stays the same:
1497 // old_trip_count == new_trip_count * 2
1498 // Note: since old_trip_count >= 2 then new_trip_count >= 1
1499 // so we also don't need to adjust zero trip test.
1500 jlong limit_con = limit->get_int();
1501 // (stride_con*2) not overflow since stride_con <= 8.
1502 int new_stride_con = stride_con * 2;
1503 int stride_m = new_stride_con - (stride_con > 0 ? 1 : -1);
1504 jlong trip_count = (limit_con - init_con + stride_m)/new_stride_con;
1505 // New trip count should satisfy next conditions.
1506 assert(trip_count > 0 && (julong)trip_count < (julong)max_juint/2, "sanity");
1507 uint new_trip_count = (uint)trip_count;
1508 adjust_min_trip = (old_trip_count != new_trip_count*2);
1509 }
1510
1511 if (adjust_min_trip) {
1512 // Step 2: Adjust the trip limit if it is called for.
1513 // The adjustment amount is -stride. Need to make sure if the
1514 // adjustment underflows or overflows, then the main loop is skipped.
1515 Node* cmp = loop_end->cmp_node();
1516 assert(cmp->in(2) == limit, "sanity");
1517 assert(opaq != NULL && opaq->in(1) == limit, "sanity");
1518
1519 // Verify that policy_unroll result is still valid.
1520 const TypeInt* limit_type = _igvn.type(limit)->is_int();
1521 assert(stride_con > 0 && ((limit_type->_hi - stride_con) < limit_type->_hi) ||
1522 stride_con < 0 && ((limit_type->_lo - stride_con) > limit_type->_lo), "sanity");
1523
1524 if (limit->is_Con()) {
1525 // The check in policy_unroll and the assert above guarantee
1526 // no underflow if limit is constant.
1527 new_limit = _igvn.intcon(limit->get_int() - stride_con);
1528 set_ctrl(new_limit, C->root());
1529 } else {
1530 // Limit is not constant.
1531 if (loop_head->unrolled_count() == 1) { // only for first unroll
1532 // Separate limit by Opaque node in case it is an incremented
1533 // variable from previous loop to avoid using pre-incremented
1534 // value which could increase register pressure.
1535 // Otherwise reorg_offsets() optimization will create a separate
1536 // Opaque node for each use of trip-counter and as result
1537 // zero trip guard limit will be different from loop limit.
1538 assert(has_ctrl(opaq), "should have it");
1539 Node* opaq_ctrl = get_ctrl(opaq);
1540 limit = new Opaque2Node( C, limit );
1541 register_new_node( limit, opaq_ctrl );
1542 }
1543 if (stride_con > 0 && (java_subtract(limit_type->_lo, stride_con) < limit_type->_lo) ||
1544 stride_con < 0 && (java_subtract(limit_type->_hi, stride_con) > limit_type->_hi)) {
1545 // No underflow.
1546 new_limit = new SubINode(limit, stride);
1547 } else {
1548 // (limit - stride) may underflow.
1549 // Clamp the adjustment value with MININT or MAXINT:
1550 //
1551 // new_limit = limit-stride
1552 // if (stride > 0)
1553 // new_limit = (limit < new_limit) ? MININT : new_limit;
1554 // else
1555 // new_limit = (limit > new_limit) ? MAXINT : new_limit;
1556 //
1557 BoolTest::mask bt = loop_end->test_trip();
1558 assert(bt == BoolTest::lt || bt == BoolTest::gt, "canonical test is expected");
1559 Node* adj_max = _igvn.intcon((stride_con > 0) ? min_jint : max_jint);
1560 set_ctrl(adj_max, C->root());
1561 Node* old_limit = NULL;
1562 Node* adj_limit = NULL;
1563 Node* bol = limit->is_CMove() ? limit->in(CMoveNode::Condition) : NULL;
1564 if (loop_head->unrolled_count() > 1 &&
1565 limit->is_CMove() && limit->Opcode() == Op_CMoveI &&
1566 limit->in(CMoveNode::IfTrue) == adj_max &&
1567 bol->as_Bool()->_test._test == bt &&
1568 bol->in(1)->Opcode() == Op_CmpI &&
1569 bol->in(1)->in(2) == limit->in(CMoveNode::IfFalse)) {
1570 // Loop was unrolled before.
1571 // Optimize the limit to avoid nested CMove:
1572 // use original limit as old limit.
1573 old_limit = bol->in(1)->in(1);
1574 // Adjust previous adjusted limit.
1575 adj_limit = limit->in(CMoveNode::IfFalse);
1576 adj_limit = new SubINode(adj_limit, stride);
1577 } else {
1578 old_limit = limit;
1579 adj_limit = new SubINode(limit, stride);
1580 }
1581 assert(old_limit != NULL && adj_limit != NULL, "");
1582 register_new_node( adj_limit, ctrl ); // adjust amount
1583 Node* adj_cmp = new CmpINode(old_limit, adj_limit);
1584 register_new_node( adj_cmp, ctrl );
1585 Node* adj_bool = new BoolNode(adj_cmp, bt);
1586 register_new_node( adj_bool, ctrl );
1587 new_limit = new CMoveINode(adj_bool, adj_limit, adj_max, TypeInt::INT);
1588 }
1589 register_new_node(new_limit, ctrl);
1590 }
1591 assert(new_limit != NULL, "");
1592 // Replace in loop test.
1593 assert(loop_end->in(1)->in(1) == cmp, "sanity");
1594 if (cmp->outcnt() == 1 && loop_end->in(1)->outcnt() == 1) {
1595 // Don't need to create new test since only one user.
1596 _igvn.hash_delete(cmp);
1597 cmp->set_req(2, new_limit);
1598 } else {
1599 // Create new test since it is shared.
1600 Node* ctrl2 = loop_end->in(0);
1601 Node* cmp2 = cmp->clone();
1602 cmp2->set_req(2, new_limit);
1603 register_new_node(cmp2, ctrl2);
1604 Node* bol2 = loop_end->in(1)->clone();
1605 bol2->set_req(1, cmp2);
1606 register_new_node(bol2, ctrl2);
1607 _igvn.replace_input_of(loop_end, 1, bol2);
1608 }
1609 // Step 3: Find the min-trip test guaranteed before a 'main' loop.
1610 // Make it a 1-trip test (means at least 2 trips).
1611
1612 // Guard test uses an 'opaque' node which is not shared. Hence I
1613 // can edit it's inputs directly. Hammer in the new limit for the
1614 // minimum-trip guard.
1615 assert(opaq->outcnt() == 1, "");
1616 _igvn.replace_input_of(opaq, 1, new_limit);
1617 }
1618
1619 // Adjust max trip count. The trip count is intentionally rounded
1620 // down here (e.g. 15-> 7-> 3-> 1) because if we unwittingly over-unroll,
1621 // the main, unrolled, part of the loop will never execute as it is protected
1622 // by the min-trip test. See bug 4834191 for a case where we over-unrolled
1623 // and later determined that part of the unrolled loop was dead.
1624 loop_head->set_trip_count(old_trip_count / 2);
1625
1626 // Double the count of original iterations in the unrolled loop body.
1627 loop_head->double_unrolled_count();
1628
1629 } else { // LoopLimitCheck
1630
1631 // Adjust max trip count. The trip count is intentionally rounded
1632 // down here (e.g. 15-> 7-> 3-> 1) because if we unwittingly over-unroll,
1633 // the main, unrolled, part of the loop will never execute as it is protected
1634 // by the min-trip test. See bug 4834191 for a case where we over-unrolled
1635 // and later determined that part of the unrolled loop was dead.
1636 loop_head->set_trip_count(loop_head->trip_count() / 2);
1637
1638 // Double the count of original iterations in the unrolled loop body.
1639 loop_head->double_unrolled_count();
1640
1641 // -----------
1642 // Step 2: Cut back the trip counter for an unroll amount of 2.
1643 // Loop will normally trip (limit - init)/stride_con. Since it's a
1644 // CountedLoop this is exact (stride divides limit-init exactly).
1645 // We are going to double the loop body, so we want to knock off any
1646 // odd iteration: (trip_cnt & ~1). Then back compute a new limit.
1647 Node *span = new SubINode( limit, init );
1648 register_new_node( span, ctrl );
1649 Node *trip = new DivINode( 0, span, stride );
1650 register_new_node( trip, ctrl );
1651 Node *mtwo = _igvn.intcon(-2);
1652 set_ctrl(mtwo, C->root());
1653 Node *rond = new AndINode( trip, mtwo );
1654 register_new_node( rond, ctrl );
1655 Node *spn2 = new MulINode( rond, stride );
1656 register_new_node( spn2, ctrl );
1657 new_limit = new AddINode( spn2, init );
1658 register_new_node( new_limit, ctrl );
1659
1660 // Hammer in the new limit
1661 Node *ctrl2 = loop_end->in(0);
1662 Node *cmp2 = new CmpINode( loop_head->incr(), new_limit );
1663 register_new_node( cmp2, ctrl2 );
1664 Node *bol2 = new BoolNode( cmp2, loop_end->test_trip() );
1665 register_new_node( bol2, ctrl2 );
1666 _igvn.replace_input_of(loop_end, CountedLoopEndNode::TestValue, bol2);
1667
1668 // Step 3: Find the min-trip test guaranteed before a 'main' loop.
1669 // Make it a 1-trip test (means at least 2 trips).
1670 if( adjust_min_trip ) {
1671 assert( new_limit != NULL, "" );
1672 // Guard test uses an 'opaque' node which is not shared. Hence I
1673 // can edit it's inputs directly. Hammer in the new limit for the
1674 // minimum-trip guard.
1675 assert( opaq->outcnt() == 1, "" );
1676 _igvn.hash_delete(opaq);
1677 opaq->set_req(1, new_limit);
1678 }
1679 } // LoopLimitCheck
1680
1681 // ---------
1682 // Step 4: Clone the loop body. Move it inside the loop. This loop body
1683 // represents the odd iterations; since the loop trips an even number of
1684 // times its backedge is never taken. Kill the backedge.
1685 uint dd = dom_depth(loop_head);
1686 clone_loop( loop, old_new, dd );
1687
1688 // Make backedges of the clone equal to backedges of the original.
1689 // Make the fall-in from the original come from the fall-out of the clone.
1690 for (DUIterator_Fast jmax, j = loop_head->fast_outs(jmax); j < jmax; j++) {
1691 Node* phi = loop_head->fast_out(j);
1692 if( phi->is_Phi() && phi->in(0) == loop_head && phi->outcnt() > 0 ) {
1693 Node *newphi = old_new[phi->_idx];
1694 _igvn.hash_delete( phi );
1695 _igvn.hash_delete( newphi );
1696
1697 phi ->set_req(LoopNode:: EntryControl, newphi->in(LoopNode::LoopBackControl));
1698 newphi->set_req(LoopNode::LoopBackControl, phi ->in(LoopNode::LoopBackControl));
1699 phi ->set_req(LoopNode::LoopBackControl, C->top());
1700 }
1701 }
1702 Node *clone_head = old_new[loop_head->_idx];
1703 _igvn.hash_delete( clone_head );
1704 loop_head ->set_req(LoopNode:: EntryControl, clone_head->in(LoopNode::LoopBackControl));
1705 clone_head->set_req(LoopNode::LoopBackControl, loop_head ->in(LoopNode::LoopBackControl));
1706 loop_head ->set_req(LoopNode::LoopBackControl, C->top());
1707 loop->_head = clone_head; // New loop header
1708
1709 set_idom(loop_head, loop_head ->in(LoopNode::EntryControl), dd);
1710 set_idom(clone_head, clone_head->in(LoopNode::EntryControl), dd);
1711
1712 // Kill the clone's backedge
1713 Node *newcle = old_new[loop_end->_idx];
1714 _igvn.hash_delete( newcle );
1715 Node *one = _igvn.intcon(1);
1716 set_ctrl(one, C->root());
1717 newcle->set_req(1, one);
1718 // Force clone into same loop body
1719 uint max = loop->_body.size();
1720 for( uint k = 0; k < max; k++ ) {
1721 Node *old = loop->_body.at(k);
1722 Node *nnn = old_new[old->_idx];
1723 loop->_body.push(nnn);
1724 if (!has_ctrl(old))
1725 set_loop(nnn, loop);
1726 }
1727
1728 loop->record_for_igvn();
1729
1730 #ifndef PRODUCT
1731 if (C->do_vector_loop() && (PrintOpto && VerifyLoopOptimizations || TraceLoopOpts)) {
1732 tty->print("\nnew loop after unroll\n"); loop->dump_head();
1733 for (uint i = 0; i < loop->_body.size(); i++) {
1734 loop->_body.at(i)->dump();
1735 }
1736 if(C->clone_map().is_debug()) {
1737 tty->print("\nCloneMap\n");
1738 Dict* dict = C->clone_map().dict();
1739 DictI i(dict);
1740 tty->print_cr("Dict@%p[%d] = ", dict, dict->Size());
1741 for (int ii = 0; i.test(); ++i, ++ii) {
1742 NodeCloneInfo cl((uint64_t)dict->operator[]((void*)i._key));
1743 tty->print("%d->%d:%d,", (int)(intptr_t)i._key, cl.idx(), cl.gen());
1744 if (ii % 10 == 9) {
1745 tty->print_cr(" ");
1746 }
1747 }
1748 tty->print_cr(" ");
1749 }
1750 }
1751 #endif
1752
1753 }
1754
1755 //------------------------------do_maximally_unroll----------------------------
1756
1757 void PhaseIdealLoop::do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new ) {
1758 CountedLoopNode *cl = loop->_head->as_CountedLoop();
1759 assert(cl->has_exact_trip_count(), "trip count is not exact");
1760 assert(cl->trip_count() > 0, "");
1761 #ifndef PRODUCT
1762 if (TraceLoopOpts) {
1763 tty->print("MaxUnroll %d ", cl->trip_count());
1764 loop->dump_head();
1765 }
1766 #endif
1767
1768 // If loop is tripping an odd number of times, peel odd iteration
1769 if ((cl->trip_count() & 1) == 1) {
1770 do_peeling(loop, old_new);
1771 }
1772
1773 // Now its tripping an even number of times remaining. Double loop body.
1774 // Do not adjust pre-guards; they are not needed and do not exist.
1775 if (cl->trip_count() > 0) {
1776 assert((cl->trip_count() & 1) == 0, "missed peeling");
1777 do_unroll(loop, old_new, false);
1778 }
1779 }
1780
1781 void PhaseIdealLoop::mark_reductions(IdealLoopTree *loop) {
1782 if (SuperWordReductions == false) return;
1783
1784 CountedLoopNode* loop_head = loop->_head->as_CountedLoop();
1785 if (loop_head->unrolled_count() > 1) {
1786 return;
1787 }
1788
1789 Node* trip_phi = loop_head->phi();
1790 for (DUIterator_Fast imax, i = loop_head->fast_outs(imax); i < imax; i++) {
1791 Node* phi = loop_head->fast_out(i);
1792 if (phi->is_Phi() && phi->outcnt() > 0 && phi != trip_phi) {
1793 // For definitions which are loop inclusive and not tripcounts.
1794 Node* def_node = phi->in(LoopNode::LoopBackControl);
1795
1796 if (def_node != NULL) {
1797 Node* n_ctrl = get_ctrl(def_node);
1798 if (n_ctrl != NULL && loop->is_member(get_loop(n_ctrl))) {
1799 // Now test it to see if it fits the standard pattern for a reduction operator.
1800 int opc = def_node->Opcode();
1801 if (opc != ReductionNode::opcode(opc, def_node->bottom_type()->basic_type())) {
1802 if (!def_node->is_reduction()) { // Not marked yet
1803 // To be a reduction, the arithmetic node must have the phi as input and provide a def to it
1804 bool ok = false;
1805 for (unsigned j = 1; j < def_node->req(); j++) {
1806 Node* in = def_node->in(j);
1807 if (in == phi) {
1808 ok = true;
1809 break;
1810 }
1811 }
1812
1813 // do nothing if we did not match the initial criteria
1814 if (ok == false) {
1815 continue;
1816 }
1817
1818 // The result of the reduction must not be used in the loop
1819 for (DUIterator_Fast imax, i = def_node->fast_outs(imax); i < imax && ok; i++) {
1820 Node* u = def_node->fast_out(i);
1821 if (has_ctrl(u) && !loop->is_member(get_loop(get_ctrl(u)))) {
1822 continue;
1823 }
1824 if (u == phi) {
1825 continue;
1826 }
1827 ok = false;
1828 }
1829
1830 // iff the uses conform
1831 if (ok) {
1832 def_node->add_flag(Node::Flag_is_reduction);
1833 loop_head->mark_has_reductions();
1834 }
1835 }
1836 }
1837 }
1838 }
1839 }
1840 }
1841 }
1842
1843 //------------------------------dominates_backedge---------------------------------
1844 // Returns true if ctrl is executed on every complete iteration
1845 bool IdealLoopTree::dominates_backedge(Node* ctrl) {
1846 assert(ctrl->is_CFG(), "must be control");
1847 Node* backedge = _head->as_Loop()->in(LoopNode::LoopBackControl);
1848 return _phase->dom_lca_internal(ctrl, backedge) == ctrl;
1849 }
1850
1851 //------------------------------adjust_limit-----------------------------------
1852 // Helper function for add_constraint().
1853 Node* PhaseIdealLoop::adjust_limit(int stride_con, Node * scale, Node *offset, Node *rc_limit, Node *loop_limit, Node *pre_ctrl) {
1854 // Compute "I :: (limit-offset)/scale"
1855 Node *con = new SubINode(rc_limit, offset);
1856 register_new_node(con, pre_ctrl);
1857 Node *X = new DivINode(0, con, scale);
1858 register_new_node(X, pre_ctrl);
1859
1860 // Adjust loop limit
1861 loop_limit = (stride_con > 0)
1862 ? (Node*)(new MinINode(loop_limit, X))
1863 : (Node*)(new MaxINode(loop_limit, X));
1864 register_new_node(loop_limit, pre_ctrl);
1865 return loop_limit;
1866 }
1867
1868 //------------------------------add_constraint---------------------------------
1869 // Constrain the main loop iterations so the conditions:
1870 // low_limit <= scale_con * I + offset < upper_limit
1871 // always holds true. That is, either increase the number of iterations in
1872 // the pre-loop or the post-loop until the condition holds true in the main
1873 // loop. Stride, scale, offset and limit are all loop invariant. Further,
1874 // stride and scale are constants (offset and limit often are).
1875 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 ) {
1876 // For positive stride, the pre-loop limit always uses a MAX function
1877 // and the main loop a MIN function. For negative stride these are
1878 // reversed.
1879
1880 // Also for positive stride*scale the affine function is increasing, so the
1881 // pre-loop must check for underflow and the post-loop for overflow.
1882 // Negative stride*scale reverses this; pre-loop checks for overflow and
1883 // post-loop for underflow.
1884
1885 Node *scale = _igvn.intcon(scale_con);
1886 set_ctrl(scale, C->root());
1887
1888 if ((stride_con^scale_con) >= 0) { // Use XOR to avoid overflow
1889 // The overflow limit: scale*I+offset < upper_limit
1890 // For main-loop compute
1891 // ( if (scale > 0) /* and stride > 0 */
1892 // I < (upper_limit-offset)/scale
1893 // else /* scale < 0 and stride < 0 */
1894 // I > (upper_limit-offset)/scale
1895 // )
1896 //
1897 // (upper_limit-offset) may overflow or underflow.
1898 // But it is fine since main loop will either have
1899 // less iterations or will be skipped in such case.
1900 *main_limit = adjust_limit(stride_con, scale, offset, upper_limit, *main_limit, pre_ctrl);
1901
1902 // The underflow limit: low_limit <= scale*I+offset.
1903 // For pre-loop compute
1904 // NOT(scale*I+offset >= low_limit)
1905 // scale*I+offset < low_limit
1906 // ( if (scale > 0) /* and stride > 0 */
1907 // I < (low_limit-offset)/scale
1908 // else /* scale < 0 and stride < 0 */
1909 // I > (low_limit-offset)/scale
1910 // )
1911
1912 if (low_limit->get_int() == -max_jint) {
1913 if (!RangeLimitCheck) return;
1914 // We need this guard when scale*pre_limit+offset >= limit
1915 // due to underflow. So we need execute pre-loop until
1916 // scale*I+offset >= min_int. But (min_int-offset) will
1917 // underflow when offset > 0 and X will be > original_limit
1918 // when stride > 0. To avoid it we replace positive offset with 0.
1919 //
1920 // Also (min_int+1 == -max_int) is used instead of min_int here
1921 // to avoid problem with scale == -1 (min_int/(-1) == min_int).
1922 Node* shift = _igvn.intcon(31);
1923 set_ctrl(shift, C->root());
1924 Node* sign = new RShiftINode(offset, shift);
1925 register_new_node(sign, pre_ctrl);
1926 offset = new AndINode(offset, sign);
1927 register_new_node(offset, pre_ctrl);
1928 } else {
1929 assert(low_limit->get_int() == 0, "wrong low limit for range check");
1930 // The only problem we have here when offset == min_int
1931 // since (0-min_int) == min_int. It may be fine for stride > 0
1932 // but for stride < 0 X will be < original_limit. To avoid it
1933 // max(pre_limit, original_limit) is used in do_range_check().
1934 }
1935 // Pass (-stride) to indicate pre_loop_cond = NOT(main_loop_cond);
1936 *pre_limit = adjust_limit((-stride_con), scale, offset, low_limit, *pre_limit, pre_ctrl);
1937
1938 } else { // stride_con*scale_con < 0
1939 // For negative stride*scale pre-loop checks for overflow and
1940 // post-loop for underflow.
1941 //
1942 // The overflow limit: scale*I+offset < upper_limit
1943 // For pre-loop compute
1944 // NOT(scale*I+offset < upper_limit)
1945 // scale*I+offset >= upper_limit
1946 // scale*I+offset+1 > upper_limit
1947 // ( if (scale < 0) /* and stride > 0 */
1948 // I < (upper_limit-(offset+1))/scale
1949 // else /* scale > 0 and stride < 0 */
1950 // I > (upper_limit-(offset+1))/scale
1951 // )
1952 //
1953 // (upper_limit-offset-1) may underflow or overflow.
1954 // To avoid it min(pre_limit, original_limit) is used
1955 // in do_range_check() for stride > 0 and max() for < 0.
1956 Node *one = _igvn.intcon(1);
1957 set_ctrl(one, C->root());
1958
1959 Node *plus_one = new AddINode(offset, one);
1960 register_new_node( plus_one, pre_ctrl );
1961 // Pass (-stride) to indicate pre_loop_cond = NOT(main_loop_cond);
1962 *pre_limit = adjust_limit((-stride_con), scale, plus_one, upper_limit, *pre_limit, pre_ctrl);
1963
1964 if (low_limit->get_int() == -max_jint) {
1965 if (!RangeLimitCheck) return;
1966 // We need this guard when scale*main_limit+offset >= limit
1967 // due to underflow. So we need execute main-loop while
1968 // scale*I+offset+1 > min_int. But (min_int-offset-1) will
1969 // underflow when (offset+1) > 0 and X will be < main_limit
1970 // when scale < 0 (and stride > 0). To avoid it we replace
1971 // positive (offset+1) with 0.
1972 //
1973 // Also (min_int+1 == -max_int) is used instead of min_int here
1974 // to avoid problem with scale == -1 (min_int/(-1) == min_int).
1975 Node* shift = _igvn.intcon(31);
1976 set_ctrl(shift, C->root());
1977 Node* sign = new RShiftINode(plus_one, shift);
1978 register_new_node(sign, pre_ctrl);
1979 plus_one = new AndINode(plus_one, sign);
1980 register_new_node(plus_one, pre_ctrl);
1981 } else {
1982 assert(low_limit->get_int() == 0, "wrong low limit for range check");
1983 // The only problem we have here when offset == max_int
1984 // since (max_int+1) == min_int and (0-min_int) == min_int.
1985 // But it is fine since main loop will either have
1986 // less iterations or will be skipped in such case.
1987 }
1988 // The underflow limit: low_limit <= scale*I+offset.
1989 // For main-loop compute
1990 // scale*I+offset+1 > low_limit
1991 // ( if (scale < 0) /* and stride > 0 */
1992 // I < (low_limit-(offset+1))/scale
1993 // else /* scale > 0 and stride < 0 */
1994 // I > (low_limit-(offset+1))/scale
1995 // )
1996
1997 *main_limit = adjust_limit(stride_con, scale, plus_one, low_limit, *main_limit, pre_ctrl);
1998 }
1999 }
2000
2001
2002 //------------------------------is_scaled_iv---------------------------------
2003 // Return true if exp is a constant times an induction var
2004 bool PhaseIdealLoop::is_scaled_iv(Node* exp, Node* iv, int* p_scale) {
2005 if (exp == iv) {
2006 if (p_scale != NULL) {
2007 *p_scale = 1;
2008 }
2009 return true;
2010 }
2011 int opc = exp->Opcode();
2012 if (opc == Op_MulI) {
2013 if (exp->in(1) == iv && exp->in(2)->is_Con()) {
2014 if (p_scale != NULL) {
2015 *p_scale = exp->in(2)->get_int();
2016 }
2017 return true;
2018 }
2019 if (exp->in(2) == iv && exp->in(1)->is_Con()) {
2020 if (p_scale != NULL) {
2021 *p_scale = exp->in(1)->get_int();
2022 }
2023 return true;
2024 }
2025 } else if (opc == Op_LShiftI) {
2026 if (exp->in(1) == iv && exp->in(2)->is_Con()) {
2027 if (p_scale != NULL) {
2028 *p_scale = 1 << exp->in(2)->get_int();
2029 }
2030 return true;
2031 }
2032 }
2033 return false;
2034 }
2035
2036 //-----------------------------is_scaled_iv_plus_offset------------------------------
2037 // Return true if exp is a simple induction variable expression: k1*iv + (invar + k2)
2038 bool PhaseIdealLoop::is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth) {
2039 if (is_scaled_iv(exp, iv, p_scale)) {
2040 if (p_offset != NULL) {
2041 Node *zero = _igvn.intcon(0);
2042 set_ctrl(zero, C->root());
2043 *p_offset = zero;
2044 }
2045 return true;
2046 }
2047 int opc = exp->Opcode();
2048 if (opc == Op_AddI) {
2049 if (is_scaled_iv(exp->in(1), iv, p_scale)) {
2050 if (p_offset != NULL) {
2051 *p_offset = exp->in(2);
2052 }
2053 return true;
2054 }
2055 if (is_scaled_iv(exp->in(2), iv, p_scale)) {
2056 if (p_offset != NULL) {
2057 *p_offset = exp->in(1);
2058 }
2059 return true;
2060 }
2061 if (exp->in(2)->is_Con()) {
2062 Node* offset2 = NULL;
2063 if (depth < 2 &&
2064 is_scaled_iv_plus_offset(exp->in(1), iv, p_scale,
2065 p_offset != NULL ? &offset2 : NULL, depth+1)) {
2066 if (p_offset != NULL) {
2067 Node *ctrl_off2 = get_ctrl(offset2);
2068 Node* offset = new AddINode(offset2, exp->in(2));
2069 register_new_node(offset, ctrl_off2);
2070 *p_offset = offset;
2071 }
2072 return true;
2073 }
2074 }
2075 } else if (opc == Op_SubI) {
2076 if (is_scaled_iv(exp->in(1), iv, p_scale)) {
2077 if (p_offset != NULL) {
2078 Node *zero = _igvn.intcon(0);
2079 set_ctrl(zero, C->root());
2080 Node *ctrl_off = get_ctrl(exp->in(2));
2081 Node* offset = new SubINode(zero, exp->in(2));
2082 register_new_node(offset, ctrl_off);
2083 *p_offset = offset;
2084 }
2085 return true;
2086 }
2087 if (is_scaled_iv(exp->in(2), iv, p_scale)) {
2088 if (p_offset != NULL) {
2089 *p_scale *= -1;
2090 *p_offset = exp->in(1);
2091 }
2092 return true;
2093 }
2094 }
2095 return false;
2096 }
2097
2098 //------------------------------do_range_check---------------------------------
2099 // Eliminate range-checks and other trip-counter vs loop-invariant tests.
2100 void PhaseIdealLoop::do_range_check( IdealLoopTree *loop, Node_List &old_new ) {
2101 #ifndef PRODUCT
2102 if (PrintOpto && VerifyLoopOptimizations) {
2103 tty->print("Range Check Elimination ");
2104 loop->dump_head();
2105 } else if (TraceLoopOpts) {
2106 tty->print("RangeCheck ");
2107 loop->dump_head();
2108 }
2109 #endif
2110 assert(RangeCheckElimination, "");
2111 CountedLoopNode *cl = loop->_head->as_CountedLoop();
2112 assert(cl->is_main_loop(), "");
2113
2114 // protect against stride not being a constant
2115 if (!cl->stride_is_con())
2116 return;
2117
2118 // Find the trip counter; we are iteration splitting based on it
2119 Node *trip_counter = cl->phi();
2120 // Find the main loop limit; we will trim it's iterations
2121 // to not ever trip end tests
2122 Node *main_limit = cl->limit();
2123
2124 // Need to find the main-loop zero-trip guard
2125 Node *ctrl = cl->in(LoopNode::EntryControl);
2126 assert(ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "");
2127 Node *iffm = ctrl->in(0);
2128 assert(iffm->Opcode() == Op_If, "");
2129 Node *bolzm = iffm->in(1);
2130 assert(bolzm->Opcode() == Op_Bool, "");
2131 Node *cmpzm = bolzm->in(1);
2132 assert(cmpzm->is_Cmp(), "");
2133 Node *opqzm = cmpzm->in(2);
2134 // Can not optimize a loop if zero-trip Opaque1 node is optimized
2135 // away and then another round of loop opts attempted.
2136 if (opqzm->Opcode() != Op_Opaque1)
2137 return;
2138 assert(opqzm->in(1) == main_limit, "do not understand situation");
2139
2140 // Find the pre-loop limit; we will expand its iterations to
2141 // not ever trip low tests.
2142 Node *p_f = iffm->in(0);
2143 // pre loop may have been optimized out
2144 if (p_f->Opcode() != Op_IfFalse) {
2145 return;
2146 }
2147 CountedLoopEndNode *pre_end = p_f->in(0)->as_CountedLoopEnd();
2148 assert(pre_end->loopnode()->is_pre_loop(), "");
2149 Node *pre_opaq1 = pre_end->limit();
2150 // Occasionally it's possible for a pre-loop Opaque1 node to be
2151 // optimized away and then another round of loop opts attempted.
2152 // We can not optimize this particular loop in that case.
2153 if (pre_opaq1->Opcode() != Op_Opaque1)
2154 return;
2155 Opaque1Node *pre_opaq = (Opaque1Node*)pre_opaq1;
2156 Node *pre_limit = pre_opaq->in(1);
2157
2158 // Where do we put new limit calculations
2159 Node *pre_ctrl = pre_end->loopnode()->in(LoopNode::EntryControl);
2160
2161 // Ensure the original loop limit is available from the
2162 // pre-loop Opaque1 node.
2163 Node *orig_limit = pre_opaq->original_loop_limit();
2164 if (orig_limit == NULL || _igvn.type(orig_limit) == Type::TOP)
2165 return;
2166
2167 // Must know if its a count-up or count-down loop
2168
2169 int stride_con = cl->stride_con();
2170 Node *zero = _igvn.intcon(0);
2171 Node *one = _igvn.intcon(1);
2172 // Use symmetrical int range [-max_jint,max_jint]
2173 Node *mini = _igvn.intcon(-max_jint);
2174 set_ctrl(zero, C->root());
2175 set_ctrl(one, C->root());
2176 set_ctrl(mini, C->root());
2177
2178 // Range checks that do not dominate the loop backedge (ie.
2179 // conditionally executed) can lengthen the pre loop limit beyond
2180 // the original loop limit. To prevent this, the pre limit is
2181 // (for stride > 0) MINed with the original loop limit (MAXed
2182 // stride < 0) when some range_check (rc) is conditionally
2183 // executed.
2184 bool conditional_rc = false;
2185
2186 // Check loop body for tests of trip-counter plus loop-invariant vs
2187 // loop-invariant.
2188 for( uint i = 0; i < loop->_body.size(); i++ ) {
2189 Node *iff = loop->_body[i];
2190 if (iff->Opcode() == Op_If ||
2191 iff->Opcode() == Op_RangeCheck) { // Test?
2192 // Test is an IfNode, has 2 projections. If BOTH are in the loop
2193 // we need loop unswitching instead of iteration splitting.
2194 Node *exit = loop->is_loop_exit(iff);
2195 if( !exit ) continue;
2196 int flip = (exit->Opcode() == Op_IfTrue) ? 1 : 0;
2197
2198 // Get boolean condition to test
2199 Node *i1 = iff->in(1);
2200 if( !i1->is_Bool() ) continue;
2201 BoolNode *bol = i1->as_Bool();
2202 BoolTest b_test = bol->_test;
2203 // Flip sense of test if exit condition is flipped
2204 if( flip )
2205 b_test = b_test.negate();
2206
2207 // Get compare
2208 Node *cmp = bol->in(1);
2209
2210 // Look for trip_counter + offset vs limit
2211 Node *rc_exp = cmp->in(1);
2212 Node *limit = cmp->in(2);
2213 jint scale_con= 1; // Assume trip counter not scaled
2214
2215 Node *limit_c = get_ctrl(limit);
2216 if( loop->is_member(get_loop(limit_c) ) ) {
2217 // Compare might have operands swapped; commute them
2218 b_test = b_test.commute();
2219 rc_exp = cmp->in(2);
2220 limit = cmp->in(1);
2221 limit_c = get_ctrl(limit);
2222 if( loop->is_member(get_loop(limit_c) ) )
2223 continue; // Both inputs are loop varying; cannot RCE
2224 }
2225 // Here we know 'limit' is loop invariant
2226
2227 // 'limit' maybe pinned below the zero trip test (probably from a
2228 // previous round of rce), in which case, it can't be used in the
2229 // zero trip test expression which must occur before the zero test's if.
2230 if( limit_c == ctrl ) {
2231 continue; // Don't rce this check but continue looking for other candidates.
2232 }
2233
2234 // Check for scaled induction variable plus an offset
2235 Node *offset = NULL;
2236
2237 if (!is_scaled_iv_plus_offset(rc_exp, trip_counter, &scale_con, &offset)) {
2238 continue;
2239 }
2240
2241 Node *offset_c = get_ctrl(offset);
2242 if( loop->is_member( get_loop(offset_c) ) )
2243 continue; // Offset is not really loop invariant
2244 // Here we know 'offset' is loop invariant.
2245
2246 // As above for the 'limit', the 'offset' maybe pinned below the
2247 // zero trip test.
2248 if( offset_c == ctrl ) {
2249 continue; // Don't rce this check but continue looking for other candidates.
2250 }
2251 #ifdef ASSERT
2252 if (TraceRangeLimitCheck) {
2253 tty->print_cr("RC bool node%s", flip ? " flipped:" : ":");
2254 bol->dump(2);
2255 }
2256 #endif
2257 // At this point we have the expression as:
2258 // scale_con * trip_counter + offset :: limit
2259 // where scale_con, offset and limit are loop invariant. Trip_counter
2260 // monotonically increases by stride_con, a constant. Both (or either)
2261 // stride_con and scale_con can be negative which will flip about the
2262 // sense of the test.
2263
2264 // Adjust pre and main loop limits to guard the correct iteration set
2265 if( cmp->Opcode() == Op_CmpU ) {// Unsigned compare is really 2 tests
2266 if( b_test._test == BoolTest::lt ) { // Range checks always use lt
2267 // The underflow and overflow limits: 0 <= scale*I+offset < limit
2268 add_constraint( stride_con, scale_con, offset, zero, limit, pre_ctrl, &pre_limit, &main_limit );
2269 if (!conditional_rc) {
2270 // (0-offset)/scale could be outside of loop iterations range.
2271 conditional_rc = !loop->dominates_backedge(iff) || RangeLimitCheck;
2272 }
2273 } else {
2274 if (PrintOpto) {
2275 tty->print_cr("missed RCE opportunity");
2276 }
2277 continue; // In release mode, ignore it
2278 }
2279 } else { // Otherwise work on normal compares
2280 switch( b_test._test ) {
2281 case BoolTest::gt:
2282 // Fall into GE case
2283 case BoolTest::ge:
2284 // Convert (I*scale+offset) >= Limit to (I*(-scale)+(-offset)) <= -Limit
2285 scale_con = -scale_con;
2286 offset = new SubINode( zero, offset );
2287 register_new_node( offset, pre_ctrl );
2288 limit = new SubINode( zero, limit );
2289 register_new_node( limit, pre_ctrl );
2290 // Fall into LE case
2291 case BoolTest::le:
2292 if (b_test._test != BoolTest::gt) {
2293 // Convert X <= Y to X < Y+1
2294 limit = new AddINode( limit, one );
2295 register_new_node( limit, pre_ctrl );
2296 }
2297 // Fall into LT case
2298 case BoolTest::lt:
2299 // The underflow and overflow limits: MIN_INT <= scale*I+offset < limit
2300 // Note: (MIN_INT+1 == -MAX_INT) is used instead of MIN_INT here
2301 // to avoid problem with scale == -1: MIN_INT/(-1) == MIN_INT.
2302 add_constraint( stride_con, scale_con, offset, mini, limit, pre_ctrl, &pre_limit, &main_limit );
2303 if (!conditional_rc) {
2304 // ((MIN_INT+1)-offset)/scale could be outside of loop iterations range.
2305 // Note: negative offset is replaced with 0 but (MIN_INT+1)/scale could
2306 // still be outside of loop range.
2307 conditional_rc = !loop->dominates_backedge(iff) || RangeLimitCheck;
2308 }
2309 break;
2310 default:
2311 if (PrintOpto) {
2312 tty->print_cr("missed RCE opportunity");
2313 }
2314 continue; // Unhandled case
2315 }
2316 }
2317
2318 // Kill the eliminated test
2319 C->set_major_progress();
2320 Node *kill_con = _igvn.intcon( 1-flip );
2321 set_ctrl(kill_con, C->root());
2322 _igvn.replace_input_of(iff, 1, kill_con);
2323 // Find surviving projection
2324 assert(iff->is_If(), "");
2325 ProjNode* dp = ((IfNode*)iff)->proj_out(1-flip);
2326 // Find loads off the surviving projection; remove their control edge
2327 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
2328 Node* cd = dp->fast_out(i); // Control-dependent node
2329 if (cd->is_Load() && cd->depends_only_on_test()) { // Loads can now float around in the loop
2330 // Allow the load to float around in the loop, or before it
2331 // but NOT before the pre-loop.
2332 _igvn.replace_input_of(cd, 0, ctrl); // ctrl, not NULL
2333 --i;
2334 --imax;
2335 }
2336 }
2337
2338 } // End of is IF
2339
2340 }
2341
2342 // Update loop limits
2343 if (conditional_rc) {
2344 pre_limit = (stride_con > 0) ? (Node*)new MinINode(pre_limit, orig_limit)
2345 : (Node*)new MaxINode(pre_limit, orig_limit);
2346 register_new_node(pre_limit, pre_ctrl);
2347 }
2348 _igvn.replace_input_of(pre_opaq, 1, pre_limit);
2349
2350 // Note:: we are making the main loop limit no longer precise;
2351 // need to round up based on stride.
2352 cl->set_nonexact_trip_count();
2353 if (!LoopLimitCheck && stride_con != 1 && stride_con != -1) { // Cutout for common case
2354 // "Standard" round-up logic: ([main_limit-init+(y-1)]/y)*y+init
2355 // Hopefully, compiler will optimize for powers of 2.
2356 Node *ctrl = get_ctrl(main_limit);
2357 Node *stride = cl->stride();
2358 Node *init = cl->init_trip()->uncast();
2359 Node *span = new SubINode(main_limit,init);
2360 register_new_node(span,ctrl);
2361 Node *rndup = _igvn.intcon(stride_con + ((stride_con>0)?-1:1));
2362 Node *add = new AddINode(span,rndup);
2363 register_new_node(add,ctrl);
2364 Node *div = new DivINode(0,add,stride);
2365 register_new_node(div,ctrl);
2366 Node *mul = new MulINode(div,stride);
2367 register_new_node(mul,ctrl);
2368 Node *newlim = new AddINode(mul,init);
2369 register_new_node(newlim,ctrl);
2370 main_limit = newlim;
2371 }
2372
2373 Node *main_cle = cl->loopexit();
2374 Node *main_bol = main_cle->in(1);
2375 // Hacking loop bounds; need private copies of exit test
2376 if( main_bol->outcnt() > 1 ) {// BoolNode shared?
2377 main_bol = main_bol->clone();// Clone a private BoolNode
2378 register_new_node( main_bol, main_cle->in(0) );
2379 _igvn.replace_input_of(main_cle, 1, main_bol);
2380 }
2381 Node *main_cmp = main_bol->in(1);
2382 if( main_cmp->outcnt() > 1 ) { // CmpNode shared?
2383 main_cmp = main_cmp->clone();// Clone a private CmpNode
2384 register_new_node( main_cmp, main_cle->in(0) );
2385 _igvn.replace_input_of(main_bol, 1, main_cmp);
2386 }
2387 // Hack the now-private loop bounds
2388 _igvn.replace_input_of(main_cmp, 2, main_limit);
2389 // The OpaqueNode is unshared by design
2390 assert( opqzm->outcnt() == 1, "cannot hack shared node" );
2391 _igvn.replace_input_of(opqzm, 1, main_limit);
2392 }
2393
2394 //------------------------------DCE_loop_body----------------------------------
2395 // Remove simplistic dead code from loop body
2396 void IdealLoopTree::DCE_loop_body() {
2397 for( uint i = 0; i < _body.size(); i++ )
2398 if( _body.at(i)->outcnt() == 0 )
2399 _body.map( i--, _body.pop() );
2400 }
2401
2402
2403 //------------------------------adjust_loop_exit_prob--------------------------
2404 // Look for loop-exit tests with the 50/50 (or worse) guesses from the parsing stage.
2405 // Replace with a 1-in-10 exit guess.
2406 void IdealLoopTree::adjust_loop_exit_prob( PhaseIdealLoop *phase ) {
2407 Node *test = tail();
2408 while( test != _head ) {
2409 uint top = test->Opcode();
2410 if( top == Op_IfTrue || top == Op_IfFalse ) {
2411 int test_con = ((ProjNode*)test)->_con;
2412 assert(top == (uint)(test_con? Op_IfTrue: Op_IfFalse), "sanity");
2413 IfNode *iff = test->in(0)->as_If();
2414 if( iff->outcnt() == 2 ) { // Ignore dead tests
2415 Node *bol = iff->in(1);
2416 if( bol && bol->req() > 1 && bol->in(1) &&
2417 ((bol->in(1)->Opcode() == Op_StorePConditional ) ||
2418 (bol->in(1)->Opcode() == Op_StoreIConditional ) ||
2419 (bol->in(1)->Opcode() == Op_StoreLConditional ) ||
2420 (bol->in(1)->Opcode() == Op_CompareAndSwapI ) ||
2421 (bol->in(1)->Opcode() == Op_CompareAndSwapL ) ||
2422 (bol->in(1)->Opcode() == Op_CompareAndSwapP ) ||
2423 (bol->in(1)->Opcode() == Op_CompareAndSwapN )))
2424 return; // Allocation loops RARELY take backedge
2425 // Find the OTHER exit path from the IF
2426 Node* ex = iff->proj_out(1-test_con);
2427 float p = iff->_prob;
2428 if( !phase->is_member( this, ex ) && iff->_fcnt == COUNT_UNKNOWN ) {
2429 if( top == Op_IfTrue ) {
2430 if( p < (PROB_FAIR + PROB_UNLIKELY_MAG(3))) {
2431 iff->_prob = PROB_STATIC_FREQUENT;
2432 }
2433 } else {
2434 if( p > (PROB_FAIR - PROB_UNLIKELY_MAG(3))) {
2435 iff->_prob = PROB_STATIC_INFREQUENT;
2436 }
2437 }
2438 }
2439 }
2440 }
2441 test = phase->idom(test);
2442 }
2443 }
2444
2445 #ifdef ASSERT
2446 static CountedLoopNode* locate_pre_from_main(CountedLoopNode *cl) {
2447 Node *ctrl = cl->in(LoopNode::EntryControl);
2448 assert(ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "");
2449 Node *iffm = ctrl->in(0);
2450 assert(iffm->Opcode() == Op_If, "");
2451 Node *p_f = iffm->in(0);
2452 assert(p_f->Opcode() == Op_IfFalse, "");
2453 CountedLoopEndNode *pre_end = p_f->in(0)->as_CountedLoopEnd();
2454 assert(pre_end->loopnode()->is_pre_loop(), "");
2455 return pre_end->loopnode();
2456 }
2457 #endif
2458
2459 // Remove the main and post loops and make the pre loop execute all
2460 // iterations. Useful when the pre loop is found empty.
2461 void IdealLoopTree::remove_main_post_loops(CountedLoopNode *cl, PhaseIdealLoop *phase) {
2462 CountedLoopEndNode* pre_end = cl->loopexit();
2463 Node* pre_cmp = pre_end->cmp_node();
2464 if (pre_cmp->in(2)->Opcode() != Op_Opaque1) {
2465 // Only safe to remove the main loop if the compiler optimized it
2466 // out based on an unknown number of iterations
2467 return;
2468 }
2469
2470 // Can we find the main loop?
2471 if (_next == NULL) {
2472 return;
2473 }
2474
2475 Node* next_head = _next->_head;
2476 if (!next_head->is_CountedLoop()) {
2477 return;
2478 }
2479
2480 CountedLoopNode* main_head = next_head->as_CountedLoop();
2481 if (!main_head->is_main_loop()) {
2482 return;
2483 }
2484
2485 assert(locate_pre_from_main(main_head) == cl, "bad main loop");
2486 Node* main_iff = main_head->in(LoopNode::EntryControl)->in(0);
2487
2488 // Remove the Opaque1Node of the pre loop and make it execute all iterations
2489 phase->_igvn.replace_input_of(pre_cmp, 2, pre_cmp->in(2)->in(2));
2490 // Remove the Opaque1Node of the main loop so it can be optimized out
2491 Node* main_cmp = main_iff->in(1)->in(1);
2492 assert(main_cmp->in(2)->Opcode() == Op_Opaque1, "main loop has no opaque node?");
2493 phase->_igvn.replace_input_of(main_cmp, 2, main_cmp->in(2)->in(1));
2494 }
2495
2496 //------------------------------policy_do_remove_empty_loop--------------------
2497 // Micro-benchmark spamming. Policy is to always remove empty loops.
2498 // The 'DO' part is to replace the trip counter with the value it will
2499 // have on the last iteration. This will break the loop.
2500 bool IdealLoopTree::policy_do_remove_empty_loop( PhaseIdealLoop *phase ) {
2501 // Minimum size must be empty loop
2502 if (_body.size() > EMPTY_LOOP_SIZE)
2503 return false;
2504
2505 if (!_head->is_CountedLoop())
2506 return false; // Dead loop
2507 CountedLoopNode *cl = _head->as_CountedLoop();
2508 if (!cl->is_valid_counted_loop())
2509 return false; // Malformed loop
2510 if (!phase->is_member(this, phase->get_ctrl(cl->loopexit()->in(CountedLoopEndNode::TestValue))))
2511 return false; // Infinite loop
2512
2513 if (cl->is_pre_loop()) {
2514 // If the loop we are removing is a pre-loop then the main and
2515 // post loop can be removed as well
2516 remove_main_post_loops(cl, phase);
2517 }
2518
2519 #ifdef ASSERT
2520 // Ensure only one phi which is the iv.
2521 Node* iv = NULL;
2522 for (DUIterator_Fast imax, i = cl->fast_outs(imax); i < imax; i++) {
2523 Node* n = cl->fast_out(i);
2524 if (n->Opcode() == Op_Phi) {
2525 assert(iv == NULL, "Too many phis" );
2526 iv = n;
2527 }
2528 }
2529 assert(iv == cl->phi(), "Wrong phi" );
2530 #endif
2531
2532 // main and post loops have explicitly created zero trip guard
2533 bool needs_guard = !cl->is_main_loop() && !cl->is_post_loop();
2534 if (needs_guard) {
2535 // Skip guard if values not overlap.
2536 const TypeInt* init_t = phase->_igvn.type(cl->init_trip())->is_int();
2537 const TypeInt* limit_t = phase->_igvn.type(cl->limit())->is_int();
2538 int stride_con = cl->stride_con();
2539 if (stride_con > 0) {
2540 needs_guard = (init_t->_hi >= limit_t->_lo);
2541 } else {
2542 needs_guard = (init_t->_lo <= limit_t->_hi);
2543 }
2544 }
2545 if (needs_guard) {
2546 // Check for an obvious zero trip guard.
2547 Node* inctrl = PhaseIdealLoop::skip_loop_predicates(cl->in(LoopNode::EntryControl));
2548 if (inctrl->Opcode() == Op_IfTrue) {
2549 // The test should look like just the backedge of a CountedLoop
2550 Node* iff = inctrl->in(0);
2551 if (iff->is_If()) {
2552 Node* bol = iff->in(1);
2553 if (bol->is_Bool() && bol->as_Bool()->_test._test == cl->loopexit()->test_trip()) {
2554 Node* cmp = bol->in(1);
2555 if (cmp->is_Cmp() && cmp->in(1) == cl->init_trip() && cmp->in(2) == cl->limit()) {
2556 needs_guard = false;
2557 }
2558 }
2559 }
2560 }
2561 }
2562
2563 #ifndef PRODUCT
2564 if (PrintOpto) {
2565 tty->print("Removing empty loop with%s zero trip guard", needs_guard ? "out" : "");
2566 this->dump_head();
2567 } else if (TraceLoopOpts) {
2568 tty->print("Empty with%s zero trip guard ", needs_guard ? "out" : "");
2569 this->dump_head();
2570 }
2571 #endif
2572
2573 if (needs_guard) {
2574 // Peel the loop to ensure there's a zero trip guard
2575 Node_List old_new;
2576 phase->do_peeling(this, old_new);
2577 }
2578
2579 // Replace the phi at loop head with the final value of the last
2580 // iteration. Then the CountedLoopEnd will collapse (backedge never
2581 // taken) and all loop-invariant uses of the exit values will be correct.
2582 Node *phi = cl->phi();
2583 Node *exact_limit = phase->exact_limit(this);
2584 if (exact_limit != cl->limit()) {
2585 // We also need to replace the original limit to collapse loop exit.
2586 Node* cmp = cl->loopexit()->cmp_node();
2587 assert(cl->limit() == cmp->in(2), "sanity");
2588 phase->_igvn._worklist.push(cmp->in(2)); // put limit on worklist
2589 phase->_igvn.replace_input_of(cmp, 2, exact_limit); // put cmp on worklist
2590 }
2591 // Note: the final value after increment should not overflow since
2592 // counted loop has limit check predicate.
2593 Node *final = new SubINode( exact_limit, cl->stride() );
2594 phase->register_new_node(final,cl->in(LoopNode::EntryControl));
2595 phase->_igvn.replace_node(phi,final);
2596 phase->C->set_major_progress();
2597 return true;
2598 }
2599
2600 //------------------------------policy_do_one_iteration_loop-------------------
2601 // Convert one iteration loop into normal code.
2602 bool IdealLoopTree::policy_do_one_iteration_loop( PhaseIdealLoop *phase ) {
2603 if (!_head->as_Loop()->is_valid_counted_loop())
2604 return false; // Only for counted loop
2605
2606 CountedLoopNode *cl = _head->as_CountedLoop();
2607 if (!cl->has_exact_trip_count() || cl->trip_count() != 1) {
2608 return false;
2609 }
2610
2611 #ifndef PRODUCT
2612 if(TraceLoopOpts) {
2613 tty->print("OneIteration ");
2614 this->dump_head();
2615 }
2616 #endif
2617
2618 Node *init_n = cl->init_trip();
2619 #ifdef ASSERT
2620 // Loop boundaries should be constant since trip count is exact.
2621 assert(init_n->get_int() + cl->stride_con() >= cl->limit()->get_int(), "should be one iteration");
2622 #endif
2623 // Replace the phi at loop head with the value of the init_trip.
2624 // Then the CountedLoopEnd will collapse (backedge will not be taken)
2625 // and all loop-invariant uses of the exit values will be correct.
2626 phase->_igvn.replace_node(cl->phi(), cl->init_trip());
2627 phase->C->set_major_progress();
2628 return true;
2629 }
2630
2631 //=============================================================================
2632 //------------------------------iteration_split_impl---------------------------
2633 bool IdealLoopTree::iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new ) {
2634 // Compute exact loop trip count if possible.
2635 compute_exact_trip_count(phase);
2636
2637 // Convert one iteration loop into normal code.
2638 if (policy_do_one_iteration_loop(phase))
2639 return true;
2640
2641 // Check and remove empty loops (spam micro-benchmarks)
2642 if (policy_do_remove_empty_loop(phase))
2643 return true; // Here we removed an empty loop
2644
2645 bool should_peel = policy_peeling(phase); // Should we peel?
2646
2647 bool should_unswitch = policy_unswitching(phase);
2648
2649 // Non-counted loops may be peeled; exactly 1 iteration is peeled.
2650 // This removes loop-invariant tests (usually null checks).
2651 if (!_head->is_CountedLoop()) { // Non-counted loop
2652 if (PartialPeelLoop && phase->partial_peel(this, old_new)) {
2653 // Partial peel succeeded so terminate this round of loop opts
2654 return false;
2655 }
2656 if (should_peel) { // Should we peel?
2657 if (PrintOpto) { tty->print_cr("should_peel"); }
2658 phase->do_peeling(this,old_new);
2659 } else if (should_unswitch) {
2660 phase->do_unswitching(this, old_new);
2661 }
2662 return true;
2663 }
2664 CountedLoopNode *cl = _head->as_CountedLoop();
2665
2666 if (!cl->is_valid_counted_loop()) return true; // Ignore various kinds of broken loops
2667
2668 // Do nothing special to pre- and post- loops
2669 if (cl->is_pre_loop() || cl->is_post_loop()) return true;
2670
2671 // Compute loop trip count from profile data
2672 compute_profile_trip_cnt(phase);
2673
2674 // Before attempting fancy unrolling, RCE or alignment, see if we want
2675 // to completely unroll this loop or do loop unswitching.
2676 if (cl->is_normal_loop()) {
2677 if (should_unswitch) {
2678 phase->do_unswitching(this, old_new);
2679 return true;
2680 }
2681 bool should_maximally_unroll = policy_maximally_unroll(phase);
2682 if (should_maximally_unroll) {
2683 // Here we did some unrolling and peeling. Eventually we will
2684 // completely unroll this loop and it will no longer be a loop.
2685 phase->do_maximally_unroll(this,old_new);
2686 return true;
2687 }
2688 }
2689
2690 // Skip next optimizations if running low on nodes. Note that
2691 // policy_unswitching and policy_maximally_unroll have this check.
2692 int nodes_left = phase->C->max_node_limit() - phase->C->live_nodes();
2693 if ((int)(2 * _body.size()) > nodes_left) {
2694 return true;
2695 }
2696
2697 // Counted loops may be peeled, may need some iterations run up
2698 // front for RCE, and may want to align loop refs to a cache
2699 // line. Thus we clone a full loop up front whose trip count is
2700 // at least 1 (if peeling), but may be several more.
2701
2702 // The main loop will start cache-line aligned with at least 1
2703 // iteration of the unrolled body (zero-trip test required) and
2704 // will have some range checks removed.
2705
2706 // A post-loop will finish any odd iterations (leftover after
2707 // unrolling), plus any needed for RCE purposes.
2708
2709 bool should_unroll = policy_unroll(phase);
2710
2711 bool should_rce = policy_range_check(phase);
2712
2713 bool should_align = policy_align(phase);
2714
2715 // If not RCE'ing (iteration splitting) or Aligning, then we do not
2716 // need a pre-loop. We may still need to peel an initial iteration but
2717 // we will not be needing an unknown number of pre-iterations.
2718 //
2719 // Basically, if may_rce_align reports FALSE first time through,
2720 // we will not be able to later do RCE or Aligning on this loop.
2721 bool may_rce_align = !policy_peel_only(phase) || should_rce || should_align;
2722
2723 // If we have any of these conditions (RCE, alignment, unrolling) met, then
2724 // we switch to the pre-/main-/post-loop model. This model also covers
2725 // peeling.
2726 if (should_rce || should_align || should_unroll) {
2727 if (cl->is_normal_loop()) // Convert to 'pre/main/post' loops
2728 phase->insert_pre_post_loops(this,old_new, !may_rce_align);
2729
2730 // Adjust the pre- and main-loop limits to let the pre and post loops run
2731 // with full checks, but the main-loop with no checks. Remove said
2732 // checks from the main body.
2733 if (should_rce)
2734 phase->do_range_check(this,old_new);
2735
2736 // Double loop body for unrolling. Adjust the minimum-trip test (will do
2737 // twice as many iterations as before) and the main body limit (only do
2738 // an even number of trips). If we are peeling, we might enable some RCE
2739 // and we'd rather unroll the post-RCE'd loop SO... do not unroll if
2740 // peeling.
2741 if (should_unroll && !should_peel) {
2742 if (SuperWordLoopUnrollAnalysis) {
2743 phase->insert_vector_post_loop(this, old_new);
2744 }
2745 phase->do_unroll(this, old_new, true);
2746 }
2747
2748 // Adjust the pre-loop limits to align the main body
2749 // iterations.
2750 if (should_align)
2751 Unimplemented();
2752
2753 } else { // Else we have an unchanged counted loop
2754 if (should_peel) // Might want to peel but do nothing else
2755 phase->do_peeling(this,old_new);
2756 }
2757 return true;
2758 }
2759
2760
2761 //=============================================================================
2762 //------------------------------iteration_split--------------------------------
2763 bool IdealLoopTree::iteration_split( PhaseIdealLoop *phase, Node_List &old_new ) {
2764 // Recursively iteration split nested loops
2765 if (_child && !_child->iteration_split(phase, old_new))
2766 return false;
2767
2768 // Clean out prior deadwood
2769 DCE_loop_body();
2770
2771
2772 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage.
2773 // Replace with a 1-in-10 exit guess.
2774 if (_parent /*not the root loop*/ &&
2775 !_irreducible &&
2776 // Also ignore the occasional dead backedge
2777 !tail()->is_top()) {
2778 adjust_loop_exit_prob(phase);
2779 }
2780
2781 // Gate unrolling, RCE and peeling efforts.
2782 if (!_child && // If not an inner loop, do not split
2783 !_irreducible &&
2784 _allow_optimizations &&
2785 !tail()->is_top()) { // Also ignore the occasional dead backedge
2786 if (!_has_call) {
2787 if (!iteration_split_impl(phase, old_new)) {
2788 return false;
2789 }
2790 } else if (policy_unswitching(phase)) {
2791 phase->do_unswitching(this, old_new);
2792 }
2793 }
2794
2795 // Minor offset re-organization to remove loop-fallout uses of
2796 // trip counter when there was no major reshaping.
2797 phase->reorg_offsets(this);
2798
2799 if (_next && !_next->iteration_split(phase, old_new))
2800 return false;
2801 return true;
2802 }
2803
2804
2805 //=============================================================================
2806 // Process all the loops in the loop tree and replace any fill
2807 // patterns with an intrinsic version.
2808 bool PhaseIdealLoop::do_intrinsify_fill() {
2809 bool changed = false;
2810 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
2811 IdealLoopTree* lpt = iter.current();
2812 changed |= intrinsify_fill(lpt);
2813 }
2814 return changed;
2815 }
2816
2817
2818 // Examine an inner loop looking for a a single store of an invariant
2819 // value in a unit stride loop,
2820 bool PhaseIdealLoop::match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value,
2821 Node*& shift, Node*& con) {
2822 const char* msg = NULL;
2823 Node* msg_node = NULL;
2824
2825 store_value = NULL;
2826 con = NULL;
2827 shift = NULL;
2828
2829 // Process the loop looking for stores. If there are multiple
2830 // stores or extra control flow give at this point.
2831 CountedLoopNode* head = lpt->_head->as_CountedLoop();
2832 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) {
2833 Node* n = lpt->_body.at(i);
2834 if (n->outcnt() == 0) continue; // Ignore dead
2835 if (n->is_Store()) {
2836 if (store != NULL) {
2837 msg = "multiple stores";
2838 break;
2839 }
2840 int opc = n->Opcode();
2841 if (opc == Op_StoreP || opc == Op_StoreN || opc == Op_StoreNKlass || opc == Op_StoreCM) {
2842 msg = "oop fills not handled";
2843 break;
2844 }
2845 Node* value = n->in(MemNode::ValueIn);
2846 if (!lpt->is_invariant(value)) {
2847 msg = "variant store value";
2848 } else if (!_igvn.type(n->in(MemNode::Address))->isa_aryptr()) {
2849 msg = "not array address";
2850 }
2851 store = n;
2852 store_value = value;
2853 } else if (n->is_If() && n != head->loopexit()) {
2854 msg = "extra control flow";
2855 msg_node = n;
2856 }
2857 }
2858
2859 if (store == NULL) {
2860 // No store in loop
2861 return false;
2862 }
2863
2864 if (msg == NULL && head->stride_con() != 1) {
2865 // could handle negative strides too
2866 if (head->stride_con() < 0) {
2867 msg = "negative stride";
2868 } else {
2869 msg = "non-unit stride";
2870 }
2871 }
2872
2873 if (msg == NULL && !store->in(MemNode::Address)->is_AddP()) {
2874 msg = "can't handle store address";
2875 msg_node = store->in(MemNode::Address);
2876 }
2877
2878 if (msg == NULL &&
2879 (!store->in(MemNode::Memory)->is_Phi() ||
2880 store->in(MemNode::Memory)->in(LoopNode::LoopBackControl) != store)) {
2881 msg = "store memory isn't proper phi";
2882 msg_node = store->in(MemNode::Memory);
2883 }
2884
2885 // Make sure there is an appropriate fill routine
2886 BasicType t = store->as_Mem()->memory_type();
2887 const char* fill_name;
2888 if (msg == NULL &&
2889 StubRoutines::select_fill_function(t, false, fill_name) == NULL) {
2890 msg = "unsupported store";
2891 msg_node = store;
2892 }
2893
2894 if (msg != NULL) {
2895 #ifndef PRODUCT
2896 if (TraceOptimizeFill) {
2897 tty->print_cr("not fill intrinsic candidate: %s", msg);
2898 if (msg_node != NULL) msg_node->dump();
2899 }
2900 #endif
2901 return false;
2902 }
2903
2904 // Make sure the address expression can be handled. It should be
2905 // head->phi * elsize + con. head->phi might have a ConvI2L(CastII()).
2906 Node* elements[4];
2907 Node* cast = NULL;
2908 Node* conv = NULL;
2909 bool found_index = false;
2910 int count = store->in(MemNode::Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
2911 for (int e = 0; e < count; e++) {
2912 Node* n = elements[e];
2913 if (n->is_Con() && con == NULL) {
2914 con = n;
2915 } else if (n->Opcode() == Op_LShiftX && shift == NULL) {
2916 Node* value = n->in(1);
2917 #ifdef _LP64
2918 if (value->Opcode() == Op_ConvI2L) {
2919 conv = value;
2920 value = value->in(1);
2921 }
2922 if (value->Opcode() == Op_CastII &&
2923 value->as_CastII()->has_range_check()) {
2924 // Skip range check dependent CastII nodes
2925 cast = value;
2926 value = value->in(1);
2927 }
2928 #endif
2929 if (value != head->phi()) {
2930 msg = "unhandled shift in address";
2931 } else {
2932 if (type2aelembytes(store->as_Mem()->memory_type(), true) != (1 << n->in(2)->get_int())) {
2933 msg = "scale doesn't match";
2934 } else {
2935 found_index = true;
2936 shift = n;
2937 }
2938 }
2939 } else if (n->Opcode() == Op_ConvI2L && conv == NULL) {
2940 conv = n;
2941 n = n->in(1);
2942 if (n->Opcode() == Op_CastII &&
2943 n->as_CastII()->has_range_check()) {
2944 // Skip range check dependent CastII nodes
2945 cast = n;
2946 n = n->in(1);
2947 }
2948 if (n == head->phi()) {
2949 found_index = true;
2950 } else {
2951 msg = "unhandled input to ConvI2L";
2952 }
2953 } else if (n == head->phi()) {
2954 // no shift, check below for allowed cases
2955 found_index = true;
2956 } else {
2957 msg = "unhandled node in address";
2958 msg_node = n;
2959 }
2960 }
2961
2962 if (count == -1) {
2963 msg = "malformed address expression";
2964 msg_node = store;
2965 }
2966
2967 if (!found_index) {
2968 msg = "missing use of index";
2969 }
2970
2971 // byte sized items won't have a shift
2972 if (msg == NULL && shift == NULL && t != T_BYTE && t != T_BOOLEAN) {
2973 msg = "can't find shift";
2974 msg_node = store;
2975 }
2976
2977 if (msg != NULL) {
2978 #ifndef PRODUCT
2979 if (TraceOptimizeFill) {
2980 tty->print_cr("not fill intrinsic: %s", msg);
2981 if (msg_node != NULL) msg_node->dump();
2982 }
2983 #endif
2984 return false;
2985 }
2986
2987 // No make sure all the other nodes in the loop can be handled
2988 VectorSet ok(Thread::current()->resource_area());
2989
2990 // store related values are ok
2991 ok.set(store->_idx);
2992 ok.set(store->in(MemNode::Memory)->_idx);
2993
2994 CountedLoopEndNode* loop_exit = head->loopexit();
2995 guarantee(loop_exit != NULL, "no loop exit node");
2996
2997 // Loop structure is ok
2998 ok.set(head->_idx);
2999 ok.set(loop_exit->_idx);
3000 ok.set(head->phi()->_idx);
3001 ok.set(head->incr()->_idx);
3002 ok.set(loop_exit->cmp_node()->_idx);
3003 ok.set(loop_exit->in(1)->_idx);
3004
3005 // Address elements are ok
3006 if (con) ok.set(con->_idx);
3007 if (shift) ok.set(shift->_idx);
3008 if (cast) ok.set(cast->_idx);
3009 if (conv) ok.set(conv->_idx);
3010
3011 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) {
3012 Node* n = lpt->_body.at(i);
3013 if (n->outcnt() == 0) continue; // Ignore dead
3014 if (ok.test(n->_idx)) continue;
3015 // Backedge projection is ok
3016 if (n->is_IfTrue() && n->in(0) == loop_exit) continue;
3017 if (!n->is_AddP()) {
3018 msg = "unhandled node";
3019 msg_node = n;
3020 break;
3021 }
3022 }
3023
3024 // Make sure no unexpected values are used outside the loop
3025 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) {
3026 Node* n = lpt->_body.at(i);
3027 // These values can be replaced with other nodes if they are used
3028 // outside the loop.
3029 if (n == store || n == loop_exit || n == head->incr() || n == store->in(MemNode::Memory)) continue;
3030 for (SimpleDUIterator iter(n); iter.has_next(); iter.next()) {
3031 Node* use = iter.get();
3032 if (!lpt->_body.contains(use)) {
3033 msg = "node is used outside loop";
3034 // lpt->_body.dump();
3035 msg_node = n;
3036 break;
3037 }
3038 }
3039 }
3040
3041 #ifdef ASSERT
3042 if (TraceOptimizeFill) {
3043 if (msg != NULL) {
3044 tty->print_cr("no fill intrinsic: %s", msg);
3045 if (msg_node != NULL) msg_node->dump();
3046 } else {
3047 tty->print_cr("fill intrinsic for:");
3048 }
3049 store->dump();
3050 if (Verbose) {
3051 lpt->_body.dump();
3052 }
3053 }
3054 #endif
3055
3056 return msg == NULL;
3057 }
3058
3059
3060
3061 bool PhaseIdealLoop::intrinsify_fill(IdealLoopTree* lpt) {
3062 // Only for counted inner loops
3063 if (!lpt->is_counted() || !lpt->is_inner()) {
3064 return false;
3065 }
3066
3067 // Must have constant stride
3068 CountedLoopNode* head = lpt->_head->as_CountedLoop();
3069 if (!head->is_valid_counted_loop() || !head->is_normal_loop()) {
3070 return false;
3071 }
3072
3073 // Check that the body only contains a store of a loop invariant
3074 // value that is indexed by the loop phi.
3075 Node* store = NULL;
3076 Node* store_value = NULL;
3077 Node* shift = NULL;
3078 Node* offset = NULL;
3079 if (!match_fill_loop(lpt, store, store_value, shift, offset)) {
3080 return false;
3081 }
3082
3083 #ifndef PRODUCT
3084 if (TraceLoopOpts) {
3085 tty->print("ArrayFill ");
3086 lpt->dump_head();
3087 }
3088 #endif
3089
3090 // Now replace the whole loop body by a call to a fill routine that
3091 // covers the same region as the loop.
3092 Node* base = store->in(MemNode::Address)->as_AddP()->in(AddPNode::Base);
3093
3094 // Build an expression for the beginning of the copy region
3095 Node* index = head->init_trip();
3096 #ifdef _LP64
3097 index = new ConvI2LNode(index);
3098 _igvn.register_new_node_with_optimizer(index);
3099 #endif
3100 if (shift != NULL) {
3101 // byte arrays don't require a shift but others do.
3102 index = new LShiftXNode(index, shift->in(2));
3103 _igvn.register_new_node_with_optimizer(index);
3104 }
3105 index = new AddPNode(base, base, index);
3106 _igvn.register_new_node_with_optimizer(index);
3107 Node* from = new AddPNode(base, index, offset);
3108 _igvn.register_new_node_with_optimizer(from);
3109 // Compute the number of elements to copy
3110 Node* len = new SubINode(head->limit(), head->init_trip());
3111 _igvn.register_new_node_with_optimizer(len);
3112
3113 BasicType t = store->as_Mem()->memory_type();
3114 bool aligned = false;
3115 if (offset != NULL && head->init_trip()->is_Con()) {
3116 int element_size = type2aelembytes(t);
3117 aligned = (offset->find_intptr_t_type()->get_con() + head->init_trip()->get_int() * element_size) % HeapWordSize == 0;
3118 }
3119
3120 // Build a call to the fill routine
3121 const char* fill_name;
3122 address fill = StubRoutines::select_fill_function(t, aligned, fill_name);
3123 assert(fill != NULL, "what?");
3124
3125 // Convert float/double to int/long for fill routines
3126 if (t == T_FLOAT) {
3127 store_value = new MoveF2INode(store_value);
3128 _igvn.register_new_node_with_optimizer(store_value);
3129 } else if (t == T_DOUBLE) {
3130 store_value = new MoveD2LNode(store_value);
3131 _igvn.register_new_node_with_optimizer(store_value);
3132 }
3133
3134 Node* mem_phi = store->in(MemNode::Memory);
3135 Node* result_ctrl;
3136 Node* result_mem;
3137 const TypeFunc* call_type = OptoRuntime::array_fill_Type();
3138 CallLeafNode *call = new CallLeafNoFPNode(call_type, fill,
3139 fill_name, TypeAryPtr::get_array_body_type(t));
3140 uint cnt = 0;
3141 call->init_req(TypeFunc::Parms + cnt++, from);
3142 call->init_req(TypeFunc::Parms + cnt++, store_value);
3143 #ifdef _LP64
3144 len = new ConvI2LNode(len);
3145 _igvn.register_new_node_with_optimizer(len);
3146 #endif
3147 call->init_req(TypeFunc::Parms + cnt++, len);
3148 #ifdef _LP64
3149 call->init_req(TypeFunc::Parms + cnt++, C->top());
3150 #endif
3151 call->init_req(TypeFunc::Control, head->init_control());
3152 call->init_req(TypeFunc::I_O, C->top()); // Does no I/O.
3153 call->init_req(TypeFunc::Memory, mem_phi->in(LoopNode::EntryControl));
3154 call->init_req(TypeFunc::ReturnAdr, C->start()->proj_out(TypeFunc::ReturnAdr));
3155 call->init_req(TypeFunc::FramePtr, C->start()->proj_out(TypeFunc::FramePtr));
3156 _igvn.register_new_node_with_optimizer(call);
3157 result_ctrl = new ProjNode(call,TypeFunc::Control);
3158 _igvn.register_new_node_with_optimizer(result_ctrl);
3159 result_mem = new ProjNode(call,TypeFunc::Memory);
3160 _igvn.register_new_node_with_optimizer(result_mem);
3161
3162 /* Disable following optimization until proper fix (add missing checks).
3163
3164 // If this fill is tightly coupled to an allocation and overwrites
3165 // the whole body, allow it to take over the zeroing.
3166 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, this);
3167 if (alloc != NULL && alloc->is_AllocateArray()) {
3168 Node* length = alloc->as_AllocateArray()->Ideal_length();
3169 if (head->limit() == length &&
3170 head->init_trip() == _igvn.intcon(0)) {
3171 if (TraceOptimizeFill) {
3172 tty->print_cr("Eliminated zeroing in allocation");
3173 }
3174 alloc->maybe_set_complete(&_igvn);
3175 } else {
3176 #ifdef ASSERT
3177 if (TraceOptimizeFill) {
3178 tty->print_cr("filling array but bounds don't match");
3179 alloc->dump();
3180 head->init_trip()->dump();
3181 head->limit()->dump();
3182 length->dump();
3183 }
3184 #endif
3185 }
3186 }
3187 */
3188
3189 // Redirect the old control and memory edges that are outside the loop.
3190 Node* exit = head->loopexit()->proj_out(0);
3191 // Sometimes the memory phi of the head is used as the outgoing
3192 // state of the loop. It's safe in this case to replace it with the
3193 // result_mem.
3194 _igvn.replace_node(store->in(MemNode::Memory), result_mem);
3195 lazy_replace(exit, result_ctrl);
3196 _igvn.replace_node(store, result_mem);
3197 // Any uses the increment outside of the loop become the loop limit.
3198 _igvn.replace_node(head->incr(), head->limit());
3199
3200 // Disconnect the head from the loop.
3201 for (uint i = 0; i < lpt->_body.size(); i++) {
3202 Node* n = lpt->_body.at(i);
3203 _igvn.replace_node(n, C->top());
3204 }
3205
3206 return true;
3207 }