1 /*
2 * Copyright (c) 2000, 2013, 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 while( test != _head ) { // Scan till run off top of loop
284 if( test->is_If() ) { // Test?
285 Node *ctrl = phase->get_ctrl(test->in(1));
286 if (ctrl->is_top())
287 return false; // Found dead test on live IF? No peeling!
288 // Standard IF only has one input value to check for loop invariance
289 assert( test->Opcode() == Op_If || test->Opcode() == Op_CountedLoopEnd, "Check this code when new subtype is added");
290 // Condition is not a member of this loop?
291 if( !is_member(phase->get_loop(ctrl)) &&
292 is_loop_exit(test) )
293 return true; // Found reason to peel!
294 }
295 // Walk up dominators to loop _head looking for test which is
296 // executed on every path thru loop.
297 test = phase->idom(test);
298 }
299 return false;
300 }
301
302 //------------------------------peeled_dom_test_elim---------------------------
303 // If we got the effect of peeling, either by actually peeling or by making
304 // a pre-loop which must execute at least once, we can remove all
305 // loop-invariant dominated tests in the main body.
306 void PhaseIdealLoop::peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new ) {
307 bool progress = true;
308 while( progress ) {
309 progress = false; // Reset for next iteration
310 Node *prev = loop->_head->in(LoopNode::LoopBackControl);//loop->tail();
311 Node *test = prev->in(0);
312 while( test != loop->_head ) { // Scan till run off top of loop
313
314 int p_op = prev->Opcode();
315 if( (p_op == Op_IfFalse || p_op == Op_IfTrue) &&
316 test->is_If() && // Test?
317 !test->in(1)->is_Con() && // And not already obvious?
318 // Condition is not a member of this loop?
319 !loop->is_member(get_loop(get_ctrl(test->in(1))))){
320 // Walk loop body looking for instances of this test
321 for( uint i = 0; i < loop->_body.size(); i++ ) {
322 Node *n = loop->_body.at(i);
323 if( n->is_If() && n->in(1) == test->in(1) /*&& n != loop->tail()->in(0)*/ ) {
324 // IfNode was dominated by version in peeled loop body
325 progress = true;
326 dominated_by( old_new[prev->_idx], n );
327 }
328 }
329 }
330 prev = test;
331 test = idom(test);
332 } // End of scan tests in loop
333
334 } // End of while( progress )
335 }
336
337 //------------------------------do_peeling-------------------------------------
338 // Peel the first iteration of the given loop.
339 // Step 1: Clone the loop body. The clone becomes the peeled iteration.
340 // The pre-loop illegally has 2 control users (old & new loops).
341 // Step 2: Make the old-loop fall-in edges point to the peeled iteration.
342 // Do this by making the old-loop fall-in edges act as if they came
343 // around the loopback from the prior iteration (follow the old-loop
344 // backedges) and then map to the new peeled iteration. This leaves
345 // the pre-loop with only 1 user (the new peeled iteration), but the
346 // peeled-loop backedge has 2 users.
347 // Step 3: Cut the backedge on the clone (so its not a loop) and remove the
348 // extra backedge user.
349 //
350 // orig
351 //
352 // stmt1
353 // |
354 // v
355 // loop predicate
356 // |
357 // v
358 // loop<----+
359 // | |
360 // stmt2 |
361 // | |
362 // v |
363 // if ^
364 // / \ |
365 // / \ |
366 // v v |
367 // false true |
368 // / \ |
369 // / ----+
370 // |
371 // v
372 // exit
373 //
374 //
375 // after clone loop
376 //
377 // stmt1
378 // |
379 // v
380 // loop predicate
381 // / \
382 // clone / \ orig
383 // / \
384 // / \
385 // v v
386 // +---->loop clone loop<----+
387 // | | | |
388 // | stmt2 clone stmt2 |
389 // | | | |
390 // | v v |
391 // ^ if clone If ^
392 // | / \ / \ |
393 // | / \ / \ |
394 // | v v v v |
395 // | true false false true |
396 // | / \ / \ |
397 // +---- \ / ----+
398 // \ /
399 // 1v v2
400 // region
401 // |
402 // v
403 // exit
404 //
405 //
406 // after peel and predicate move
407 //
408 // stmt1
409 // /
410 // /
411 // clone / orig
412 // /
413 // / +----------+
414 // / | |
415 // / loop predicate |
416 // / | |
417 // v v |
418 // TOP-->loop clone loop<----+ |
419 // | | | |
420 // stmt2 clone stmt2 | |
421 // | | | ^
422 // v v | |
423 // if clone If ^ |
424 // / \ / \ | |
425 // / \ / \ | |
426 // v v v v | |
427 // true false false true | |
428 // | \ / \ | |
429 // | \ / ----+ ^
430 // | \ / |
431 // | 1v v2 |
432 // v region |
433 // | | |
434 // | v |
435 // | exit |
436 // | |
437 // +--------------->-----------------+
438 //
439 //
440 // final graph
441 //
442 // stmt1
443 // |
444 // v
445 // stmt2 clone
446 // |
447 // v
448 // if clone
449 // / |
450 // / |
451 // v v
452 // false true
453 // | |
454 // | v
455 // | loop predicate
456 // | |
457 // | v
458 // | loop<----+
459 // | | |
460 // | stmt2 |
461 // | | |
462 // | v |
463 // v if ^
464 // | / \ |
465 // | / \ |
466 // | v v |
467 // | false true |
468 // | | \ |
469 // v v --+
470 // region
471 // |
472 // v
473 // exit
474 //
475 void PhaseIdealLoop::do_peeling( IdealLoopTree *loop, Node_List &old_new ) {
476
477 C->set_major_progress();
478 // Peeling a 'main' loop in a pre/main/post situation obfuscates the
479 // 'pre' loop from the main and the 'pre' can no longer have it's
480 // iterations adjusted. Therefore, we need to declare this loop as
481 // no longer a 'main' loop; it will need new pre and post loops before
482 // we can do further RCE.
483 #ifndef PRODUCT
484 if (TraceLoopOpts) {
485 tty->print("Peel ");
486 loop->dump_head();
487 }
488 #endif
489 Node* head = loop->_head;
490 bool counted_loop = head->is_CountedLoop();
491 if (counted_loop) {
492 CountedLoopNode *cl = head->as_CountedLoop();
493 assert(cl->trip_count() > 0, "peeling a fully unrolled loop");
494 cl->set_trip_count(cl->trip_count() - 1);
495 if (cl->is_main_loop()) {
496 cl->set_normal_loop();
497 #ifndef PRODUCT
498 if (PrintOpto && VerifyLoopOptimizations) {
499 tty->print("Peeling a 'main' loop; resetting to 'normal' ");
500 loop->dump_head();
501 }
502 #endif
503 }
504 }
505 Node* entry = head->in(LoopNode::EntryControl);
506
507 // Step 1: Clone the loop body. The clone becomes the peeled iteration.
508 // The pre-loop illegally has 2 control users (old & new loops).
509 clone_loop( loop, old_new, dom_depth(head) );
510
511 // Step 2: Make the old-loop fall-in edges point to the peeled iteration.
512 // Do this by making the old-loop fall-in edges act as if they came
513 // around the loopback from the prior iteration (follow the old-loop
514 // backedges) and then map to the new peeled iteration. This leaves
515 // the pre-loop with only 1 user (the new peeled iteration), but the
516 // peeled-loop backedge has 2 users.
517 Node* new_entry = old_new[head->in(LoopNode::LoopBackControl)->_idx];
518 _igvn.hash_delete(head);
519 head->set_req(LoopNode::EntryControl, new_entry);
520 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
521 Node* old = head->fast_out(j);
522 if (old->in(0) == loop->_head && old->req() == 3 && old->is_Phi()) {
523 Node* new_exit_value = old_new[old->in(LoopNode::LoopBackControl)->_idx];
524 if (!new_exit_value ) // Backedge value is ALSO loop invariant?
525 // Then loop body backedge value remains the same.
526 new_exit_value = old->in(LoopNode::LoopBackControl);
527 _igvn.hash_delete(old);
528 old->set_req(LoopNode::EntryControl, new_exit_value);
529 }
530 }
531
532
533 // Step 3: Cut the backedge on the clone (so its not a loop) and remove the
534 // extra backedge user.
535 Node* new_head = old_new[head->_idx];
536 _igvn.hash_delete(new_head);
537 new_head->set_req(LoopNode::LoopBackControl, C->top());
538 for (DUIterator_Fast j2max, j2 = new_head->fast_outs(j2max); j2 < j2max; j2++) {
539 Node* use = new_head->fast_out(j2);
540 if (use->in(0) == new_head && use->req() == 3 && use->is_Phi()) {
541 _igvn.hash_delete(use);
542 use->set_req(LoopNode::LoopBackControl, C->top());
543 }
544 }
545
546
547 // Step 4: Correct dom-depth info. Set to loop-head depth.
548 int dd = dom_depth(head);
549 set_idom(head, head->in(1), dd);
550 for (uint j3 = 0; j3 < loop->_body.size(); j3++) {
551 Node *old = loop->_body.at(j3);
552 Node *nnn = old_new[old->_idx];
553 if (!has_ctrl(nnn))
554 set_idom(nnn, idom(nnn), dd-1);
555 }
556
557 // Now force out all loop-invariant dominating tests. The optimizer
558 // finds some, but we _know_ they are all useless.
559 peeled_dom_test_elim(loop,old_new);
560
561 loop->record_for_igvn();
562 }
563
564 #define EMPTY_LOOP_SIZE 7 // number of nodes in an empty loop
565
566 //------------------------------policy_maximally_unroll------------------------
567 // Calculate exact loop trip count and return true if loop can be maximally
568 // unrolled.
569 bool IdealLoopTree::policy_maximally_unroll( PhaseIdealLoop *phase ) const {
570 CountedLoopNode *cl = _head->as_CountedLoop();
571 assert(cl->is_normal_loop(), "");
572 if (!cl->is_valid_counted_loop())
573 return false; // Malformed counted loop
574
575 if (!cl->has_exact_trip_count()) {
576 // Trip count is not exact.
577 return false;
578 }
579
580 uint trip_count = cl->trip_count();
581 // Note, max_juint is used to indicate unknown trip count.
582 assert(trip_count > 1, "one iteration loop should be optimized out already");
583 assert(trip_count < max_juint, "exact trip_count should be less than max_uint.");
584
585 // Real policy: if we maximally unroll, does it get too big?
586 // Allow the unrolled mess to get larger than standard loop
587 // size. After all, it will no longer be a loop.
588 uint body_size = _body.size();
589 uint unroll_limit = (uint)LoopUnrollLimit * 4;
590 assert( (intx)unroll_limit == LoopUnrollLimit * 4, "LoopUnrollLimit must fit in 32bits");
591 if (trip_count > unroll_limit || body_size > unroll_limit) {
592 return false;
593 }
594
595 // Fully unroll a loop with few iterations regardless next
596 // conditions since following loop optimizations will split
597 // such loop anyway (pre-main-post).
598 if (trip_count <= 3)
599 return true;
600
601 // Take into account that after unroll conjoined heads and tails will fold,
602 // otherwise policy_unroll() may allow more unrolling than max unrolling.
603 uint new_body_size = EMPTY_LOOP_SIZE + (body_size - EMPTY_LOOP_SIZE) * trip_count;
604 uint tst_body_size = (new_body_size - EMPTY_LOOP_SIZE) / trip_count + EMPTY_LOOP_SIZE;
605 if (body_size != tst_body_size) // Check for int overflow
606 return false;
607 if (new_body_size > unroll_limit ||
608 // Unrolling can result in a large amount of node construction
609 new_body_size >= phase->C->max_node_limit() - phase->C->live_nodes()) {
610 return false;
611 }
612
613 // Do not unroll a loop with String intrinsics code.
614 // String intrinsics are large and have loops.
615 for (uint k = 0; k < _body.size(); k++) {
616 Node* n = _body.at(k);
617 switch (n->Opcode()) {
618 case Op_StrComp:
619 case Op_StrEquals:
620 case Op_StrIndexOf:
621 case Op_EncodeISOArray:
622 case Op_AryEq: {
623 return false;
624 }
625 #if INCLUDE_RTM_OPT
626 case Op_FastLock:
627 case Op_FastUnlock: {
628 // Don't unroll RTM locking code because it is large.
629 if (UseRTMLocking) {
630 return false;
631 }
632 }
633 #endif
634 } // switch
635 }
636
637 return true; // Do maximally unroll
638 }
639
640
641 //------------------------------policy_unroll----------------------------------
642 // Return TRUE or FALSE if the loop should be unrolled or not. Unroll if
643 // the loop is a CountedLoop and the body is small enough.
644 bool IdealLoopTree::policy_unroll( PhaseIdealLoop *phase ) {
645
646 CountedLoopNode *cl = _head->as_CountedLoop();
647 assert(cl->is_normal_loop() || cl->is_main_loop(), "");
648
649 if (!cl->is_valid_counted_loop())
650 return false; // Malformed counted loop
651
652 // Protect against over-unrolling.
653 // After split at least one iteration will be executed in pre-loop.
654 if (cl->trip_count() <= (uint)(cl->is_normal_loop() ? 2 : 1)) return false;
655
656 _local_loop_unroll_limit = LoopUnrollLimit;
657 _local_loop_unroll_factor = 4;
658 int future_unroll_ct = cl->unrolled_count() * 2;
659 if (future_unroll_ct > LoopMaxUnroll) return false;
660
661 if (UseSuperWord) {
662 if (cl->is_reduction_loop() == false) phase->mark_reductions(this);
663
664 // Only attempt slp analysis when user controls do not prohibit it
665 if (LoopMaxUnroll > _local_loop_unroll_factor) {
666 // Once policy_slp_analysis succeeds, mark the loop with the
667 // maximal unroll factor so that we minimize analysis passes
668 if (cl->has_passed_slp() == false) {
669 if (policy_slp_analysis(cl, phase)) {
670 if (_local_loop_unroll_factor > 4) {
671 cl->mark_passed_slp();
672 cl->set_slp_max_unroll(_local_loop_unroll_factor);
673 }
674 }
675 }
676
677 if (cl->has_passed_slp()) {
678 int slp_max_unroll_factor = cl->slp_max_unroll();
679 if ((slp_max_unroll_factor > 4) &&
680 (slp_max_unroll_factor >= future_unroll_ct)) {
681 int new_limit = cl->node_count_before_unroll() * slp_max_unroll_factor;
682 if (new_limit > LoopUnrollLimit) {
683 #ifndef PRODUCT
684 if (TraceSuperWordLoopUnrollAnalysis) {
685 tty->print_cr("slp analysis is applying unroll limit %d, the original limit was %d\n",
686 new_limit, _local_loop_unroll_limit);
687 }
688 #endif
689 _local_loop_unroll_limit = new_limit;
690 }
691 }
692 }
693 }
694 }
695
696 // Check for initial stride being a small enough constant
697 if (abs(cl->stride_con()) > (1<<2)*future_unroll_ct) return false;
698
699 // Don't unroll if the next round of unrolling would push us
700 // over the expected trip count of the loop. One is subtracted
701 // from the expected trip count because the pre-loop normally
702 // executes 1 iteration.
703 if (UnrollLimitForProfileCheck > 0 &&
704 cl->profile_trip_cnt() != COUNT_UNKNOWN &&
705 future_unroll_ct > UnrollLimitForProfileCheck &&
706 (float)future_unroll_ct > cl->profile_trip_cnt() - 1.0) {
707 return false;
708 }
709
710 // When unroll count is greater than LoopUnrollMin, don't unroll if:
711 // the residual iterations are more than 10% of the trip count
712 // and rounds of "unroll,optimize" are not making significant progress
713 // Progress defined as current size less than 20% larger than previous size.
714 if (UseSuperWord && cl->node_count_before_unroll() > 0 &&
715 future_unroll_ct > LoopUnrollMin &&
716 (future_unroll_ct - 1) * 10.0 > cl->profile_trip_cnt() &&
717 1.2 * cl->node_count_before_unroll() < (double)_body.size()) {
718 return false;
719 }
720
721 Node *init_n = cl->init_trip();
722 Node *limit_n = cl->limit();
723 int stride_con = cl->stride_con();
724 // Non-constant bounds.
725 // Protect against over-unrolling when init or/and limit are not constant
726 // (so that trip_count's init value is maxint) but iv range is known.
727 if (init_n == NULL || !init_n->is_Con() ||
728 limit_n == NULL || !limit_n->is_Con()) {
729 Node* phi = cl->phi();
730 if (phi != NULL) {
731 assert(phi->is_Phi() && phi->in(0) == _head, "Counted loop should have iv phi.");
732 const TypeInt* iv_type = phase->_igvn.type(phi)->is_int();
733 int next_stride = stride_con * 2; // stride after this unroll
734 if (next_stride > 0) {
735 if (iv_type->_lo + next_stride <= iv_type->_lo || // overflow
736 iv_type->_lo + next_stride > iv_type->_hi) {
737 return false; // over-unrolling
738 }
739 } else if (next_stride < 0) {
740 if (iv_type->_hi + next_stride >= iv_type->_hi || // overflow
741 iv_type->_hi + next_stride < iv_type->_lo) {
742 return false; // over-unrolling
743 }
744 }
745 }
746 }
747
748 // After unroll limit will be adjusted: new_limit = limit-stride.
749 // Bailout if adjustment overflow.
750 const TypeInt* limit_type = phase->_igvn.type(limit_n)->is_int();
751 if (stride_con > 0 && ((limit_type->_hi - stride_con) >= limit_type->_hi) ||
752 stride_con < 0 && ((limit_type->_lo - stride_con) <= limit_type->_lo))
753 return false; // overflow
754
755 // Adjust body_size to determine if we unroll or not
756 uint body_size = _body.size();
757 // Key test to unroll loop in CRC32 java code
758 int xors_in_loop = 0;
759 // Also count ModL, DivL and MulL which expand mightly
760 for (uint k = 0; k < _body.size(); k++) {
761 Node* n = _body.at(k);
762 switch (n->Opcode()) {
763 case Op_XorI: xors_in_loop++; break; // CRC32 java code
764 case Op_ModL: body_size += 30; break;
765 case Op_DivL: body_size += 30; break;
766 case Op_MulL: body_size += 10; break;
767 case Op_StrComp:
768 case Op_StrEquals:
769 case Op_StrIndexOf:
770 case Op_EncodeISOArray:
771 case Op_AryEq: {
772 // Do not unroll a loop with String intrinsics code.
773 // String intrinsics are large and have loops.
774 return false;
775 }
776 #if INCLUDE_RTM_OPT
777 case Op_FastLock:
778 case Op_FastUnlock: {
779 // Don't unroll RTM locking code because it is large.
780 if (UseRTMLocking) {
781 return false;
782 }
783 }
784 #endif
785 } // switch
786 }
787
788 // Check for being too big
789 if (body_size > (uint)_local_loop_unroll_limit) {
790 if (xors_in_loop >= 4 && body_size < (uint)LoopUnrollLimit*4) return true;
791 // Normal case: loop too big
792 return false;
793 }
794
795 // Unroll once! (Each trip will soon do double iterations)
796 return true;
797 }
798
799 bool IdealLoopTree::policy_slp_analysis( CountedLoopNode *cl, PhaseIdealLoop *phase ) {
800 // SLP analysis
801 bool not_slp = false;
802
803 // Enable this functionality target by target as needed
804 if (SuperWordLoopUnrollAnalysis) {
805 SuperWord sw(phase);
806 sw.transform_loop(this, false);
807
808 // If the loop is slp canonical analyze it
809 if (sw.early_return() == false) {
810 Arena *a = Thread::current()->resource_area();
811 int max_vector = Matcher::max_vector_size(T_INT);
812 size_t ignored_size = _body.size()*sizeof(int*);
813 int *ignored_loop_nodes = (int*)a->Amalloc_D(ignored_size);
814 Node_Stack nstack((int)ignored_size);
815 Node *cl_exit = cl->loopexit();
816
817 // First clear the entries
818 for (uint i = 0; i < _body.size(); i++) {
819 ignored_loop_nodes[i] = -1;
820 }
821
822 // Process the loop, some/all of the stack entries will not be in order, ergo
823 // need to preprocess the ignored initial state before we process the loop
824 for (uint i = 0; i < _body.size(); i++) {
825 Node* n = _body.at(i);
826 if (n == cl->incr() ||
827 n->is_reduction() ||
828 n->is_AddP() ||
829 n->is_Cmp() ||
830 n->is_IfTrue() ||
831 n->is_CountedLoop() ||
832 (n == cl_exit)) {
833 ignored_loop_nodes[i] = n->_idx;
834 continue;
835 }
836
837 if (n->is_If()) {
838 IfNode *iff = n->as_If();
839 if (iff->_fcnt != COUNT_UNKNOWN && iff->_prob != PROB_UNKNOWN) {
840 if (is_loop_exit(iff)) {
841 ignored_loop_nodes[i] = n->_idx;
842 continue;
843 }
844 }
845 }
846
847 if (n->is_Phi() && (n->bottom_type() == Type::MEMORY)) {
848 Node* n_tail = n->in(LoopNode::LoopBackControl);
849 if (n_tail != n->in(LoopNode::EntryControl)) {
850 if (!n_tail->is_Mem()) {
851 not_slp = true;
852 break;
853 }
854 }
855 }
856
857 // This must happen after check of phi/if
858 if (n->is_Phi() || n->is_If()) {
859 ignored_loop_nodes[i] = n->_idx;
860 continue;
861 }
862
863 if (n->is_LoadStore() || n->is_MergeMem() ||
864 (n->is_Proj() && !n->as_Proj()->is_CFG())) {
865 not_slp = true;
866 break;
867 }
868
869 if (n->is_Mem()) {
870 Node* adr = n->in(MemNode::Address);
871 Node* n_ctrl = phase->get_ctrl(adr);
872
873 // save a queue of post process nodes
874 if (n_ctrl != NULL && is_member(phase->get_loop(n_ctrl))) {
875 MemNode* current = n->as_Mem();
876 BasicType bt = current->memory_type();
877 if (is_java_primitive(bt) == false) {
878 ignored_loop_nodes[i] = n->_idx;
879 continue;
880 }
881
882 // Process the memory expression
883 int stack_idx = 0;
884 bool have_side_effects = true;
885 if (adr->is_AddP() == false) {
886 nstack.push(adr, stack_idx++);
887 } else {
888 // Mark the components of the memory operation in nstack
889 SWPointer p1(current, &sw, &nstack, true);
890 have_side_effects = p1.node_stack()->is_nonempty();
891 }
892
893 // Process the pointer stack
894 while (have_side_effects) {
895 Node* pointer_node = nstack.node();
896 for (uint j = 0; j < _body.size(); j++) {
897 Node* cur_node = _body.at(j);
898 if (cur_node == pointer_node) {
899 ignored_loop_nodes[j] = cur_node->_idx;
900 break;
901 }
902 }
903 nstack.pop();
904 have_side_effects = nstack.is_nonempty();
905 }
906
907 // Cleanup
908 nstack.clear();
909 }
910 }
911 }
912
913 if (not_slp == false) {
914 // Now we try to find the maximum supported consistent vector which the machine
915 // description can use
916 for (uint i = 0; i < _body.size(); i++) {
917 if (ignored_loop_nodes[i] != -1) continue;
918
919 BasicType bt;
920 Node* n = _body.at(i);
921 if (n->is_Store()) {
922 bt = n->as_Mem()->memory_type();
923 } else {
924 bt = n->bottom_type()->basic_type();
925 }
926
927 int cur_max_vector = Matcher::max_vector_size(bt);
928
929 // If a max vector exists which is not larger than _local_loop_unroll_factor
930 // stop looking, we already have the max vector to map to.
931 if (cur_max_vector <= _local_loop_unroll_factor) {
932 not_slp = true;
933 #ifndef PRODUCT
934 if (TraceSuperWordLoopUnrollAnalysis) {
935 tty->print_cr("slp analysis fails: unroll limit equals max vector\n");
936 }
937 #endif
938 break;
939 }
940
941 // Map the maximal common vector
942 if (VectorNode::implemented(n->Opcode(), cur_max_vector, bt)) {
943 if (cur_max_vector < max_vector) {
944 max_vector = cur_max_vector;
945 }
946 }
947 }
948 if (not_slp == false) _local_loop_unroll_factor = max_vector;
949 }
950
951 if (not_slp) {
952 // Mark the loop as processed so that we do not try again
953 cl->mark_passed_slp();
954 cl->set_slp_max_unroll(_local_loop_unroll_factor);
955 }
956
957 // Now clean things up
958 a->Afree(ignored_loop_nodes, ignored_size);
959 }
960 }
961
962 return (not_slp == false);
963 }
964
965 //------------------------------policy_align-----------------------------------
966 // Return TRUE or FALSE if the loop should be cache-line aligned. Gather the
967 // expression that does the alignment. Note that only one array base can be
968 // aligned in a loop (unless the VM guarantees mutual alignment). Note that
969 // if we vectorize short memory ops into longer memory ops, we may want to
970 // increase alignment.
971 bool IdealLoopTree::policy_align( PhaseIdealLoop *phase ) const {
972 return false;
973 }
974
975 //------------------------------policy_range_check-----------------------------
976 // Return TRUE or FALSE if the loop should be range-check-eliminated.
977 // Actually we do iteration-splitting, a more powerful form of RCE.
978 bool IdealLoopTree::policy_range_check( PhaseIdealLoop *phase ) const {
979 if (!RangeCheckElimination) return false;
980
981 CountedLoopNode *cl = _head->as_CountedLoop();
982 // If we unrolled with no intention of doing RCE and we later
983 // changed our minds, we got no pre-loop. Either we need to
984 // make a new pre-loop, or we gotta disallow RCE.
985 if (cl->is_main_no_pre_loop()) return false; // Disallowed for now.
986 Node *trip_counter = cl->phi();
987
988 // Check loop body for tests of trip-counter plus loop-invariant vs
989 // loop-invariant.
990 for (uint i = 0; i < _body.size(); i++) {
991 Node *iff = _body[i];
992 if (iff->Opcode() == Op_If) { // Test?
993
994 // Comparing trip+off vs limit
995 Node *bol = iff->in(1);
996 if (bol->req() != 2) continue; // dead constant test
997 if (!bol->is_Bool()) {
998 assert(UseLoopPredicate && bol->Opcode() == Op_Conv2B, "predicate check only");
999 continue;
1000 }
1001 if (bol->as_Bool()->_test._test == BoolTest::ne)
1002 continue; // not RC
1003
1004 Node *cmp = bol->in(1);
1005 Node *rc_exp = cmp->in(1);
1006 Node *limit = cmp->in(2);
1007
1008 Node *limit_c = phase->get_ctrl(limit);
1009 if( limit_c == phase->C->top() )
1010 return false; // Found dead test on live IF? No RCE!
1011 if( is_member(phase->get_loop(limit_c) ) ) {
1012 // Compare might have operands swapped; commute them
1013 rc_exp = cmp->in(2);
1014 limit = cmp->in(1);
1015 limit_c = phase->get_ctrl(limit);
1016 if( is_member(phase->get_loop(limit_c) ) )
1017 continue; // Both inputs are loop varying; cannot RCE
1018 }
1019
1020 if (!phase->is_scaled_iv_plus_offset(rc_exp, trip_counter, NULL, NULL)) {
1021 continue;
1022 }
1023 // Yeah! Found a test like 'trip+off vs limit'
1024 // Test is an IfNode, has 2 projections. If BOTH are in the loop
1025 // we need loop unswitching instead of iteration splitting.
1026 if( is_loop_exit(iff) )
1027 return true; // Found reason to split iterations
1028 } // End of is IF
1029 }
1030
1031 return false;
1032 }
1033
1034 //------------------------------policy_peel_only-------------------------------
1035 // Return TRUE or FALSE if the loop should NEVER be RCE'd or aligned. Useful
1036 // for unrolling loops with NO array accesses.
1037 bool IdealLoopTree::policy_peel_only( PhaseIdealLoop *phase ) const {
1038
1039 for( uint i = 0; i < _body.size(); i++ )
1040 if( _body[i]->is_Mem() )
1041 return false;
1042
1043 // No memory accesses at all!
1044 return true;
1045 }
1046
1047 //------------------------------clone_up_backedge_goo--------------------------
1048 // If Node n lives in the back_ctrl block and cannot float, we clone a private
1049 // version of n in preheader_ctrl block and return that, otherwise return n.
1050 Node *PhaseIdealLoop::clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones ) {
1051 if( get_ctrl(n) != back_ctrl ) return n;
1052
1053 // Only visit once
1054 if (visited.test_set(n->_idx)) {
1055 Node *x = clones.find(n->_idx);
1056 if (x != NULL)
1057 return x;
1058 return n;
1059 }
1060
1061 Node *x = NULL; // If required, a clone of 'n'
1062 // Check for 'n' being pinned in the backedge.
1063 if( n->in(0) && n->in(0) == back_ctrl ) {
1064 assert(clones.find(n->_idx) == NULL, "dead loop");
1065 x = n->clone(); // Clone a copy of 'n' to preheader
1066 clones.push(x, n->_idx);
1067 x->set_req( 0, preheader_ctrl ); // Fix x's control input to preheader
1068 }
1069
1070 // Recursive fixup any other input edges into x.
1071 // If there are no changes we can just return 'n', otherwise
1072 // we need to clone a private copy and change it.
1073 for( uint i = 1; i < n->req(); i++ ) {
1074 Node *g = clone_up_backedge_goo( back_ctrl, preheader_ctrl, n->in(i), visited, clones );
1075 if( g != n->in(i) ) {
1076 if( !x ) {
1077 assert(clones.find(n->_idx) == NULL, "dead loop");
1078 x = n->clone();
1079 clones.push(x, n->_idx);
1080 }
1081 x->set_req(i, g);
1082 }
1083 }
1084 if( x ) { // x can legally float to pre-header location
1085 register_new_node( x, preheader_ctrl );
1086 return x;
1087 } else { // raise n to cover LCA of uses
1088 set_ctrl( n, find_non_split_ctrl(back_ctrl->in(0)) );
1089 }
1090 return n;
1091 }
1092
1093 bool PhaseIdealLoop::cast_incr_before_loop(Node* incr, Node* ctrl, Node* loop) {
1094 Node* castii = new CastIINode(incr, TypeInt::INT, true);
1095 castii->set_req(0, ctrl);
1096 register_new_node(castii, ctrl);
1097 for (DUIterator_Fast imax, i = incr->fast_outs(imax); i < imax; i++) {
1098 Node* n = incr->fast_out(i);
1099 if (n->is_Phi() && n->in(0) == loop) {
1100 int nrep = n->replace_edge(incr, castii);
1101 return true;
1102 }
1103 }
1104 return false;
1105 }
1106
1107 //------------------------------insert_pre_post_loops--------------------------
1108 // Insert pre and post loops. If peel_only is set, the pre-loop can not have
1109 // more iterations added. It acts as a 'peel' only, no lower-bound RCE, no
1110 // alignment. Useful to unroll loops that do no array accesses.
1111 void PhaseIdealLoop::insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only ) {
1112
1113 #ifndef PRODUCT
1114 if (TraceLoopOpts) {
1115 if (peel_only)
1116 tty->print("PeelMainPost ");
1117 else
1118 tty->print("PreMainPost ");
1119 loop->dump_head();
1120 }
1121 #endif
1122 C->set_major_progress();
1123
1124 // Find common pieces of the loop being guarded with pre & post loops
1125 CountedLoopNode *main_head = loop->_head->as_CountedLoop();
1126 assert( main_head->is_normal_loop(), "" );
1127 CountedLoopEndNode *main_end = main_head->loopexit();
1128 guarantee(main_end != NULL, "no loop exit node");
1129 assert( main_end->outcnt() == 2, "1 true, 1 false path only" );
1130 uint dd_main_head = dom_depth(main_head);
1131 uint max = main_head->outcnt();
1132
1133 Node *pre_header= main_head->in(LoopNode::EntryControl);
1134 Node *init = main_head->init_trip();
1135 Node *incr = main_end ->incr();
1136 Node *limit = main_end ->limit();
1137 Node *stride = main_end ->stride();
1138 Node *cmp = main_end ->cmp_node();
1139 BoolTest::mask b_test = main_end->test_trip();
1140
1141 // Need only 1 user of 'bol' because I will be hacking the loop bounds.
1142 Node *bol = main_end->in(CountedLoopEndNode::TestValue);
1143 if( bol->outcnt() != 1 ) {
1144 bol = bol->clone();
1145 register_new_node(bol,main_end->in(CountedLoopEndNode::TestControl));
1146 _igvn.replace_input_of(main_end, CountedLoopEndNode::TestValue, bol);
1147 }
1148 // Need only 1 user of 'cmp' because I will be hacking the loop bounds.
1149 if( cmp->outcnt() != 1 ) {
1150 cmp = cmp->clone();
1151 register_new_node(cmp,main_end->in(CountedLoopEndNode::TestControl));
1152 _igvn.replace_input_of(bol, 1, cmp);
1153 }
1154
1155 //------------------------------
1156 // Step A: Create Post-Loop.
1157 Node* main_exit = main_end->proj_out(false);
1158 assert( main_exit->Opcode() == Op_IfFalse, "" );
1159 int dd_main_exit = dom_depth(main_exit);
1160
1161 // Step A1: Clone the loop body. The clone becomes the post-loop. The main
1162 // loop pre-header illegally has 2 control users (old & new loops).
1163 clone_loop( loop, old_new, dd_main_exit );
1164 assert( old_new[main_end ->_idx]->Opcode() == Op_CountedLoopEnd, "" );
1165 CountedLoopNode *post_head = old_new[main_head->_idx]->as_CountedLoop();
1166 post_head->set_post_loop(main_head);
1167
1168 // Reduce the post-loop trip count.
1169 CountedLoopEndNode* post_end = old_new[main_end ->_idx]->as_CountedLoopEnd();
1170 post_end->_prob = PROB_FAIR;
1171
1172 // Build the main-loop normal exit.
1173 IfFalseNode *new_main_exit = new IfFalseNode(main_end);
1174 _igvn.register_new_node_with_optimizer( new_main_exit );
1175 set_idom(new_main_exit, main_end, dd_main_exit );
1176 set_loop(new_main_exit, loop->_parent);
1177
1178 // Step A2: Build a zero-trip guard for the post-loop. After leaving the
1179 // main-loop, the post-loop may not execute at all. We 'opaque' the incr
1180 // (the main-loop trip-counter exit value) because we will be changing
1181 // the exit value (via unrolling) so we cannot constant-fold away the zero
1182 // trip guard until all unrolling is done.
1183 Node *zer_opaq = new Opaque1Node(C, incr);
1184 Node *zer_cmp = new CmpINode( zer_opaq, limit );
1185 Node *zer_bol = new BoolNode( zer_cmp, b_test );
1186 register_new_node( zer_opaq, new_main_exit );
1187 register_new_node( zer_cmp , new_main_exit );
1188 register_new_node( zer_bol , new_main_exit );
1189
1190 // Build the IfNode
1191 IfNode *zer_iff = new IfNode( new_main_exit, zer_bol, PROB_FAIR, COUNT_UNKNOWN );
1192 _igvn.register_new_node_with_optimizer( zer_iff );
1193 set_idom(zer_iff, new_main_exit, dd_main_exit);
1194 set_loop(zer_iff, loop->_parent);
1195
1196 // Plug in the false-path, taken if we need to skip post-loop
1197 _igvn.replace_input_of(main_exit, 0, zer_iff);
1198 set_idom(main_exit, zer_iff, dd_main_exit);
1199 set_idom(main_exit->unique_out(), zer_iff, dd_main_exit);
1200 // Make the true-path, must enter the post loop
1201 Node *zer_taken = new IfTrueNode( zer_iff );
1202 _igvn.register_new_node_with_optimizer( zer_taken );
1203 set_idom(zer_taken, zer_iff, dd_main_exit);
1204 set_loop(zer_taken, loop->_parent);
1205 // Plug in the true path
1206 _igvn.hash_delete( post_head );
1207 post_head->set_req(LoopNode::EntryControl, zer_taken);
1208 set_idom(post_head, zer_taken, dd_main_exit);
1209
1210 Arena *a = Thread::current()->resource_area();
1211 VectorSet visited(a);
1212 Node_Stack clones(a, main_head->back_control()->outcnt());
1213 // Step A3: Make the fall-in values to the post-loop come from the
1214 // fall-out values of the main-loop.
1215 for (DUIterator_Fast imax, i = main_head->fast_outs(imax); i < imax; i++) {
1216 Node* main_phi = main_head->fast_out(i);
1217 if( main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() >0 ) {
1218 Node *post_phi = old_new[main_phi->_idx];
1219 Node *fallmain = clone_up_backedge_goo(main_head->back_control(),
1220 post_head->init_control(),
1221 main_phi->in(LoopNode::LoopBackControl),
1222 visited, clones);
1223 _igvn.hash_delete(post_phi);
1224 post_phi->set_req( LoopNode::EntryControl, fallmain );
1225 }
1226 }
1227
1228 // Update local caches for next stanza
1229 main_exit = new_main_exit;
1230
1231
1232 //------------------------------
1233 // Step B: Create Pre-Loop.
1234
1235 // Step B1: Clone the loop body. The clone becomes the pre-loop. The main
1236 // loop pre-header illegally has 2 control users (old & new loops).
1237 clone_loop( loop, old_new, dd_main_head );
1238 CountedLoopNode* pre_head = old_new[main_head->_idx]->as_CountedLoop();
1239 CountedLoopEndNode* pre_end = old_new[main_end ->_idx]->as_CountedLoopEnd();
1240 pre_head->set_pre_loop(main_head);
1241 Node *pre_incr = old_new[incr->_idx];
1242
1243 // Reduce the pre-loop trip count.
1244 pre_end->_prob = PROB_FAIR;
1245
1246 // Find the pre-loop normal exit.
1247 Node* pre_exit = pre_end->proj_out(false);
1248 assert( pre_exit->Opcode() == Op_IfFalse, "" );
1249 IfFalseNode *new_pre_exit = new IfFalseNode(pre_end);
1250 _igvn.register_new_node_with_optimizer( new_pre_exit );
1251 set_idom(new_pre_exit, pre_end, dd_main_head);
1252 set_loop(new_pre_exit, loop->_parent);
1253
1254 // Step B2: Build a zero-trip guard for the main-loop. After leaving the
1255 // pre-loop, the main-loop may not execute at all. Later in life this
1256 // zero-trip guard will become the minimum-trip guard when we unroll
1257 // the main-loop.
1258 Node *min_opaq = new Opaque1Node(C, limit);
1259 Node *min_cmp = new CmpINode( pre_incr, min_opaq );
1260 Node *min_bol = new BoolNode( min_cmp, b_test );
1261 register_new_node( min_opaq, new_pre_exit );
1262 register_new_node( min_cmp , new_pre_exit );
1263 register_new_node( min_bol , new_pre_exit );
1264
1265 // Build the IfNode (assume the main-loop is executed always).
1266 IfNode *min_iff = new IfNode( new_pre_exit, min_bol, PROB_ALWAYS, COUNT_UNKNOWN );
1267 _igvn.register_new_node_with_optimizer( min_iff );
1268 set_idom(min_iff, new_pre_exit, dd_main_head);
1269 set_loop(min_iff, loop->_parent);
1270
1271 // Plug in the false-path, taken if we need to skip main-loop
1272 _igvn.hash_delete( pre_exit );
1273 pre_exit->set_req(0, min_iff);
1274 set_idom(pre_exit, min_iff, dd_main_head);
1275 set_idom(pre_exit->unique_out(), min_iff, dd_main_head);
1276 // Make the true-path, must enter the main loop
1277 Node *min_taken = new IfTrueNode( min_iff );
1278 _igvn.register_new_node_with_optimizer( min_taken );
1279 set_idom(min_taken, min_iff, dd_main_head);
1280 set_loop(min_taken, loop->_parent);
1281 // Plug in the true path
1282 _igvn.hash_delete( main_head );
1283 main_head->set_req(LoopNode::EntryControl, min_taken);
1284 set_idom(main_head, min_taken, dd_main_head);
1285
1286 visited.Clear();
1287 clones.clear();
1288 // Step B3: Make the fall-in values to the main-loop come from the
1289 // fall-out values of the pre-loop.
1290 for (DUIterator_Fast i2max, i2 = main_head->fast_outs(i2max); i2 < i2max; i2++) {
1291 Node* main_phi = main_head->fast_out(i2);
1292 if( main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() > 0 ) {
1293 Node *pre_phi = old_new[main_phi->_idx];
1294 Node *fallpre = clone_up_backedge_goo(pre_head->back_control(),
1295 main_head->init_control(),
1296 pre_phi->in(LoopNode::LoopBackControl),
1297 visited, clones);
1298 _igvn.hash_delete(main_phi);
1299 main_phi->set_req( LoopNode::EntryControl, fallpre );
1300 }
1301 }
1302
1303 // Nodes inside the loop may be control dependent on a predicate
1304 // that was moved before the preloop. If the back branch of the main
1305 // or post loops becomes dead, those nodes won't be dependent on the
1306 // test that guards that loop nest anymore which could lead to an
1307 // incorrect array access because it executes independently of the
1308 // test that was guarding the loop nest. We add a special CastII on
1309 // the if branch that enters the loop, between the input induction
1310 // variable value and the induction variable Phi to preserve correct
1311 // dependencies.
1312
1313 // CastII for the post loop:
1314 bool inserted = cast_incr_before_loop(zer_opaq->in(1), zer_taken, post_head);
1315 assert(inserted, "no castII inserted");
1316
1317 // CastII for the main loop:
1318 inserted = cast_incr_before_loop(pre_incr, min_taken, main_head);
1319 assert(inserted, "no castII inserted");
1320
1321 // Step B4: Shorten the pre-loop to run only 1 iteration (for now).
1322 // RCE and alignment may change this later.
1323 Node *cmp_end = pre_end->cmp_node();
1324 assert( cmp_end->in(2) == limit, "" );
1325 Node *pre_limit = new AddINode( init, stride );
1326
1327 // Save the original loop limit in this Opaque1 node for
1328 // use by range check elimination.
1329 Node *pre_opaq = new Opaque1Node(C, pre_limit, limit);
1330
1331 register_new_node( pre_limit, pre_head->in(0) );
1332 register_new_node( pre_opaq , pre_head->in(0) );
1333
1334 // Since no other users of pre-loop compare, I can hack limit directly
1335 assert( cmp_end->outcnt() == 1, "no other users" );
1336 _igvn.hash_delete(cmp_end);
1337 cmp_end->set_req(2, peel_only ? pre_limit : pre_opaq);
1338
1339 // Special case for not-equal loop bounds:
1340 // Change pre loop test, main loop test, and the
1341 // main loop guard test to use lt or gt depending on stride
1342 // direction:
1343 // positive stride use <
1344 // negative stride use >
1345 //
1346 // not-equal test is kept for post loop to handle case
1347 // when init > limit when stride > 0 (and reverse).
1348
1349 if (pre_end->in(CountedLoopEndNode::TestValue)->as_Bool()->_test._test == BoolTest::ne) {
1350
1351 BoolTest::mask new_test = (main_end->stride_con() > 0) ? BoolTest::lt : BoolTest::gt;
1352 // Modify pre loop end condition
1353 Node* pre_bol = pre_end->in(CountedLoopEndNode::TestValue)->as_Bool();
1354 BoolNode* new_bol0 = new BoolNode(pre_bol->in(1), new_test);
1355 register_new_node( new_bol0, pre_head->in(0) );
1356 _igvn.replace_input_of(pre_end, CountedLoopEndNode::TestValue, new_bol0);
1357 // Modify main loop guard condition
1358 assert(min_iff->in(CountedLoopEndNode::TestValue) == min_bol, "guard okay");
1359 BoolNode* new_bol1 = new BoolNode(min_bol->in(1), new_test);
1360 register_new_node( new_bol1, new_pre_exit );
1361 _igvn.hash_delete(min_iff);
1362 min_iff->set_req(CountedLoopEndNode::TestValue, new_bol1);
1363 // Modify main loop end condition
1364 BoolNode* main_bol = main_end->in(CountedLoopEndNode::TestValue)->as_Bool();
1365 BoolNode* new_bol2 = new BoolNode(main_bol->in(1), new_test);
1366 register_new_node( new_bol2, main_end->in(CountedLoopEndNode::TestControl) );
1367 _igvn.replace_input_of(main_end, CountedLoopEndNode::TestValue, new_bol2);
1368 }
1369
1370 // Flag main loop
1371 main_head->set_main_loop();
1372 if( peel_only ) main_head->set_main_no_pre_loop();
1373
1374 // Subtract a trip count for the pre-loop.
1375 main_head->set_trip_count(main_head->trip_count() - 1);
1376
1377 // It's difficult to be precise about the trip-counts
1378 // for the pre/post loops. They are usually very short,
1379 // so guess that 4 trips is a reasonable value.
1380 post_head->set_profile_trip_cnt(4.0);
1381 pre_head->set_profile_trip_cnt(4.0);
1382
1383 // Now force out all loop-invariant dominating tests. The optimizer
1384 // finds some, but we _know_ they are all useless.
1385 peeled_dom_test_elim(loop,old_new);
1386 loop->record_for_igvn();
1387 }
1388
1389 //------------------------------is_invariant-----------------------------
1390 // Return true if n is invariant
1391 bool IdealLoopTree::is_invariant(Node* n) const {
1392 Node *n_c = _phase->has_ctrl(n) ? _phase->get_ctrl(n) : n;
1393 if (n_c->is_top()) return false;
1394 return !is_member(_phase->get_loop(n_c));
1395 }
1396
1397
1398 //------------------------------do_unroll--------------------------------------
1399 // Unroll the loop body one step - make each trip do 2 iterations.
1400 void PhaseIdealLoop::do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip ) {
1401 assert(LoopUnrollLimit, "");
1402 CountedLoopNode *loop_head = loop->_head->as_CountedLoop();
1403 CountedLoopEndNode *loop_end = loop_head->loopexit();
1404 assert(loop_end, "");
1405 #ifndef PRODUCT
1406 if (PrintOpto && VerifyLoopOptimizations) {
1407 tty->print("Unrolling ");
1408 loop->dump_head();
1409 } else if (TraceLoopOpts) {
1410 if (loop_head->trip_count() < (uint)LoopUnrollLimit) {
1411 tty->print("Unroll %d(%2d) ", loop_head->unrolled_count()*2, loop_head->trip_count());
1412 } else {
1413 tty->print("Unroll %d ", loop_head->unrolled_count()*2);
1414 }
1415 loop->dump_head();
1416 }
1417 #endif
1418
1419 // Remember loop node count before unrolling to detect
1420 // if rounds of unroll,optimize are making progress
1421 loop_head->set_node_count_before_unroll(loop->_body.size());
1422
1423 Node *ctrl = loop_head->in(LoopNode::EntryControl);
1424 Node *limit = loop_head->limit();
1425 Node *init = loop_head->init_trip();
1426 Node *stride = loop_head->stride();
1427
1428 Node *opaq = NULL;
1429 if (adjust_min_trip) { // If not maximally unrolling, need adjustment
1430 // Search for zero-trip guard.
1431 assert( loop_head->is_main_loop(), "" );
1432 assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" );
1433 Node *iff = ctrl->in(0);
1434 assert( iff->Opcode() == Op_If, "" );
1435 Node *bol = iff->in(1);
1436 assert( bol->Opcode() == Op_Bool, "" );
1437 Node *cmp = bol->in(1);
1438 assert( cmp->Opcode() == Op_CmpI, "" );
1439 opaq = cmp->in(2);
1440 // Occasionally it's possible for a zero-trip guard Opaque1 node to be
1441 // optimized away and then another round of loop opts attempted.
1442 // We can not optimize this particular loop in that case.
1443 if (opaq->Opcode() != Op_Opaque1)
1444 return; // Cannot find zero-trip guard! Bail out!
1445 // Zero-trip test uses an 'opaque' node which is not shared.
1446 assert(opaq->outcnt() == 1 && opaq->in(1) == limit, "");
1447 }
1448
1449 C->set_major_progress();
1450
1451 Node* new_limit = NULL;
1452 if (UnrollLimitCheck) {
1453 int stride_con = stride->get_int();
1454 int stride_p = (stride_con > 0) ? stride_con : -stride_con;
1455 uint old_trip_count = loop_head->trip_count();
1456 // Verify that unroll policy result is still valid.
1457 assert(old_trip_count > 1 &&
1458 (!adjust_min_trip || stride_p <= (1<<3)*loop_head->unrolled_count()), "sanity");
1459
1460 // Adjust loop limit to keep valid iterations number after unroll.
1461 // Use (limit - stride) instead of (((limit - init)/stride) & (-2))*stride
1462 // which may overflow.
1463 if (!adjust_min_trip) {
1464 assert(old_trip_count > 1 && (old_trip_count & 1) == 0,
1465 "odd trip count for maximally unroll");
1466 // Don't need to adjust limit for maximally unroll since trip count is even.
1467 } else if (loop_head->has_exact_trip_count() && init->is_Con()) {
1468 // Loop's limit is constant. Loop's init could be constant when pre-loop
1469 // become peeled iteration.
1470 jlong init_con = init->get_int();
1471 // We can keep old loop limit if iterations count stays the same:
1472 // old_trip_count == new_trip_count * 2
1473 // Note: since old_trip_count >= 2 then new_trip_count >= 1
1474 // so we also don't need to adjust zero trip test.
1475 jlong limit_con = limit->get_int();
1476 // (stride_con*2) not overflow since stride_con <= 8.
1477 int new_stride_con = stride_con * 2;
1478 int stride_m = new_stride_con - (stride_con > 0 ? 1 : -1);
1479 jlong trip_count = (limit_con - init_con + stride_m)/new_stride_con;
1480 // New trip count should satisfy next conditions.
1481 assert(trip_count > 0 && (julong)trip_count < (julong)max_juint/2, "sanity");
1482 uint new_trip_count = (uint)trip_count;
1483 adjust_min_trip = (old_trip_count != new_trip_count*2);
1484 }
1485
1486 if (adjust_min_trip) {
1487 // Step 2: Adjust the trip limit if it is called for.
1488 // The adjustment amount is -stride. Need to make sure if the
1489 // adjustment underflows or overflows, then the main loop is skipped.
1490 Node* cmp = loop_end->cmp_node();
1491 assert(cmp->in(2) == limit, "sanity");
1492 assert(opaq != NULL && opaq->in(1) == limit, "sanity");
1493
1494 // Verify that policy_unroll result is still valid.
1495 const TypeInt* limit_type = _igvn.type(limit)->is_int();
1496 assert(stride_con > 0 && ((limit_type->_hi - stride_con) < limit_type->_hi) ||
1497 stride_con < 0 && ((limit_type->_lo - stride_con) > limit_type->_lo), "sanity");
1498
1499 if (limit->is_Con()) {
1500 // The check in policy_unroll and the assert above guarantee
1501 // no underflow if limit is constant.
1502 new_limit = _igvn.intcon(limit->get_int() - stride_con);
1503 set_ctrl(new_limit, C->root());
1504 } else {
1505 // Limit is not constant.
1506 if (loop_head->unrolled_count() == 1) { // only for first unroll
1507 // Separate limit by Opaque node in case it is an incremented
1508 // variable from previous loop to avoid using pre-incremented
1509 // value which could increase register pressure.
1510 // Otherwise reorg_offsets() optimization will create a separate
1511 // Opaque node for each use of trip-counter and as result
1512 // zero trip guard limit will be different from loop limit.
1513 assert(has_ctrl(opaq), "should have it");
1514 Node* opaq_ctrl = get_ctrl(opaq);
1515 limit = new Opaque2Node( C, limit );
1516 register_new_node( limit, opaq_ctrl );
1517 }
1518 if (stride_con > 0 && ((limit_type->_lo - stride_con) < limit_type->_lo) ||
1519 stride_con < 0 && ((limit_type->_hi - stride_con) > limit_type->_hi)) {
1520 // No underflow.
1521 new_limit = new SubINode(limit, stride);
1522 } else {
1523 // (limit - stride) may underflow.
1524 // Clamp the adjustment value with MININT or MAXINT:
1525 //
1526 // new_limit = limit-stride
1527 // if (stride > 0)
1528 // new_limit = (limit < new_limit) ? MININT : new_limit;
1529 // else
1530 // new_limit = (limit > new_limit) ? MAXINT : new_limit;
1531 //
1532 BoolTest::mask bt = loop_end->test_trip();
1533 assert(bt == BoolTest::lt || bt == BoolTest::gt, "canonical test is expected");
1534 Node* adj_max = _igvn.intcon((stride_con > 0) ? min_jint : max_jint);
1535 set_ctrl(adj_max, C->root());
1536 Node* old_limit = NULL;
1537 Node* adj_limit = NULL;
1538 Node* bol = limit->is_CMove() ? limit->in(CMoveNode::Condition) : NULL;
1539 if (loop_head->unrolled_count() > 1 &&
1540 limit->is_CMove() && limit->Opcode() == Op_CMoveI &&
1541 limit->in(CMoveNode::IfTrue) == adj_max &&
1542 bol->as_Bool()->_test._test == bt &&
1543 bol->in(1)->Opcode() == Op_CmpI &&
1544 bol->in(1)->in(2) == limit->in(CMoveNode::IfFalse)) {
1545 // Loop was unrolled before.
1546 // Optimize the limit to avoid nested CMove:
1547 // use original limit as old limit.
1548 old_limit = bol->in(1)->in(1);
1549 // Adjust previous adjusted limit.
1550 adj_limit = limit->in(CMoveNode::IfFalse);
1551 adj_limit = new SubINode(adj_limit, stride);
1552 } else {
1553 old_limit = limit;
1554 adj_limit = new SubINode(limit, stride);
1555 }
1556 assert(old_limit != NULL && adj_limit != NULL, "");
1557 register_new_node( adj_limit, ctrl ); // adjust amount
1558 Node* adj_cmp = new CmpINode(old_limit, adj_limit);
1559 register_new_node( adj_cmp, ctrl );
1560 Node* adj_bool = new BoolNode(adj_cmp, bt);
1561 register_new_node( adj_bool, ctrl );
1562 new_limit = new CMoveINode(adj_bool, adj_limit, adj_max, TypeInt::INT);
1563 }
1564 register_new_node(new_limit, ctrl);
1565 }
1566 assert(new_limit != NULL, "");
1567 // Replace in loop test.
1568 assert(loop_end->in(1)->in(1) == cmp, "sanity");
1569 if (cmp->outcnt() == 1 && loop_end->in(1)->outcnt() == 1) {
1570 // Don't need to create new test since only one user.
1571 _igvn.hash_delete(cmp);
1572 cmp->set_req(2, new_limit);
1573 } else {
1574 // Create new test since it is shared.
1575 Node* ctrl2 = loop_end->in(0);
1576 Node* cmp2 = cmp->clone();
1577 cmp2->set_req(2, new_limit);
1578 register_new_node(cmp2, ctrl2);
1579 Node* bol2 = loop_end->in(1)->clone();
1580 bol2->set_req(1, cmp2);
1581 register_new_node(bol2, ctrl2);
1582 _igvn.replace_input_of(loop_end, 1, bol2);
1583 }
1584 // Step 3: Find the min-trip test guaranteed before a 'main' loop.
1585 // Make it a 1-trip test (means at least 2 trips).
1586
1587 // Guard test uses an 'opaque' node which is not shared. Hence I
1588 // can edit it's inputs directly. Hammer in the new limit for the
1589 // minimum-trip guard.
1590 assert(opaq->outcnt() == 1, "");
1591 _igvn.replace_input_of(opaq, 1, new_limit);
1592 }
1593
1594 // Adjust max trip count. The trip count is intentionally rounded
1595 // down here (e.g. 15-> 7-> 3-> 1) because if we unwittingly over-unroll,
1596 // the main, unrolled, part of the loop will never execute as it is protected
1597 // by the min-trip test. See bug 4834191 for a case where we over-unrolled
1598 // and later determined that part of the unrolled loop was dead.
1599 loop_head->set_trip_count(old_trip_count / 2);
1600
1601 // Double the count of original iterations in the unrolled loop body.
1602 loop_head->double_unrolled_count();
1603
1604 } else { // LoopLimitCheck
1605
1606 // Adjust max trip count. The trip count is intentionally rounded
1607 // down here (e.g. 15-> 7-> 3-> 1) because if we unwittingly over-unroll,
1608 // the main, unrolled, part of the loop will never execute as it is protected
1609 // by the min-trip test. See bug 4834191 for a case where we over-unrolled
1610 // and later determined that part of the unrolled loop was dead.
1611 loop_head->set_trip_count(loop_head->trip_count() / 2);
1612
1613 // Double the count of original iterations in the unrolled loop body.
1614 loop_head->double_unrolled_count();
1615
1616 // -----------
1617 // Step 2: Cut back the trip counter for an unroll amount of 2.
1618 // Loop will normally trip (limit - init)/stride_con. Since it's a
1619 // CountedLoop this is exact (stride divides limit-init exactly).
1620 // We are going to double the loop body, so we want to knock off any
1621 // odd iteration: (trip_cnt & ~1). Then back compute a new limit.
1622 Node *span = new SubINode( limit, init );
1623 register_new_node( span, ctrl );
1624 Node *trip = new DivINode( 0, span, stride );
1625 register_new_node( trip, ctrl );
1626 Node *mtwo = _igvn.intcon(-2);
1627 set_ctrl(mtwo, C->root());
1628 Node *rond = new AndINode( trip, mtwo );
1629 register_new_node( rond, ctrl );
1630 Node *spn2 = new MulINode( rond, stride );
1631 register_new_node( spn2, ctrl );
1632 new_limit = new AddINode( spn2, init );
1633 register_new_node( new_limit, ctrl );
1634
1635 // Hammer in the new limit
1636 Node *ctrl2 = loop_end->in(0);
1637 Node *cmp2 = new CmpINode( loop_head->incr(), new_limit );
1638 register_new_node( cmp2, ctrl2 );
1639 Node *bol2 = new BoolNode( cmp2, loop_end->test_trip() );
1640 register_new_node( bol2, ctrl2 );
1641 _igvn.replace_input_of(loop_end, CountedLoopEndNode::TestValue, bol2);
1642
1643 // Step 3: Find the min-trip test guaranteed before a 'main' loop.
1644 // Make it a 1-trip test (means at least 2 trips).
1645 if( adjust_min_trip ) {
1646 assert( new_limit != NULL, "" );
1647 // Guard test uses an 'opaque' node which is not shared. Hence I
1648 // can edit it's inputs directly. Hammer in the new limit for the
1649 // minimum-trip guard.
1650 assert( opaq->outcnt() == 1, "" );
1651 _igvn.hash_delete(opaq);
1652 opaq->set_req(1, new_limit);
1653 }
1654 } // LoopLimitCheck
1655
1656 // ---------
1657 // Step 4: Clone the loop body. Move it inside the loop. This loop body
1658 // represents the odd iterations; since the loop trips an even number of
1659 // times its backedge is never taken. Kill the backedge.
1660 uint dd = dom_depth(loop_head);
1661 clone_loop( loop, old_new, dd );
1662
1663 // Make backedges of the clone equal to backedges of the original.
1664 // Make the fall-in from the original come from the fall-out of the clone.
1665 for (DUIterator_Fast jmax, j = loop_head->fast_outs(jmax); j < jmax; j++) {
1666 Node* phi = loop_head->fast_out(j);
1667 if( phi->is_Phi() && phi->in(0) == loop_head && phi->outcnt() > 0 ) {
1668 Node *newphi = old_new[phi->_idx];
1669 _igvn.hash_delete( phi );
1670 _igvn.hash_delete( newphi );
1671
1672 phi ->set_req(LoopNode:: EntryControl, newphi->in(LoopNode::LoopBackControl));
1673 newphi->set_req(LoopNode::LoopBackControl, phi ->in(LoopNode::LoopBackControl));
1674 phi ->set_req(LoopNode::LoopBackControl, C->top());
1675 }
1676 }
1677 Node *clone_head = old_new[loop_head->_idx];
1678 _igvn.hash_delete( clone_head );
1679 loop_head ->set_req(LoopNode:: EntryControl, clone_head->in(LoopNode::LoopBackControl));
1680 clone_head->set_req(LoopNode::LoopBackControl, loop_head ->in(LoopNode::LoopBackControl));
1681 loop_head ->set_req(LoopNode::LoopBackControl, C->top());
1682 loop->_head = clone_head; // New loop header
1683
1684 set_idom(loop_head, loop_head ->in(LoopNode::EntryControl), dd);
1685 set_idom(clone_head, clone_head->in(LoopNode::EntryControl), dd);
1686
1687 // Kill the clone's backedge
1688 Node *newcle = old_new[loop_end->_idx];
1689 _igvn.hash_delete( newcle );
1690 Node *one = _igvn.intcon(1);
1691 set_ctrl(one, C->root());
1692 newcle->set_req(1, one);
1693 // Force clone into same loop body
1694 uint max = loop->_body.size();
1695 for( uint k = 0; k < max; k++ ) {
1696 Node *old = loop->_body.at(k);
1697 Node *nnn = old_new[old->_idx];
1698 loop->_body.push(nnn);
1699 if (!has_ctrl(old))
1700 set_loop(nnn, loop);
1701 }
1702
1703 loop->record_for_igvn();
1704 }
1705
1706 //------------------------------do_maximally_unroll----------------------------
1707
1708 void PhaseIdealLoop::do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new ) {
1709 CountedLoopNode *cl = loop->_head->as_CountedLoop();
1710 assert(cl->has_exact_trip_count(), "trip count is not exact");
1711 assert(cl->trip_count() > 0, "");
1712 #ifndef PRODUCT
1713 if (TraceLoopOpts) {
1714 tty->print("MaxUnroll %d ", cl->trip_count());
1715 loop->dump_head();
1716 }
1717 #endif
1718
1719 // If loop is tripping an odd number of times, peel odd iteration
1720 if ((cl->trip_count() & 1) == 1) {
1721 do_peeling(loop, old_new);
1722 }
1723
1724 // Now its tripping an even number of times remaining. Double loop body.
1725 // Do not adjust pre-guards; they are not needed and do not exist.
1726 if (cl->trip_count() > 0) {
1727 assert((cl->trip_count() & 1) == 0, "missed peeling");
1728 do_unroll(loop, old_new, false);
1729 }
1730 }
1731
1732 void PhaseIdealLoop::mark_reductions(IdealLoopTree *loop) {
1733 if (SuperWordReductions == false) return;
1734
1735 CountedLoopNode* loop_head = loop->_head->as_CountedLoop();
1736 if (loop_head->unrolled_count() > 1) {
1737 return;
1738 }
1739
1740 Node* trip_phi = loop_head->phi();
1741 for (DUIterator_Fast imax, i = loop_head->fast_outs(imax); i < imax; i++) {
1742 Node* phi = loop_head->fast_out(i);
1743 if (phi->is_Phi() && phi->outcnt() > 0 && phi != trip_phi) {
1744 // For definitions which are loop inclusive and not tripcounts.
1745 Node* def_node = phi->in(LoopNode::LoopBackControl);
1746
1747 if (def_node != NULL) {
1748 Node* n_ctrl = get_ctrl(def_node);
1749 if (n_ctrl != NULL && loop->is_member(get_loop(n_ctrl))) {
1750 // Now test it to see if it fits the standard pattern for a reduction operator.
1751 int opc = def_node->Opcode();
1752 if (opc != ReductionNode::opcode(opc, def_node->bottom_type()->basic_type())) {
1753 if (!def_node->is_reduction()) { // Not marked yet
1754 // To be a reduction, the arithmetic node must have the phi as input and provide a def to it
1755 for (unsigned j = 1; j < def_node->req(); j++) {
1756 Node* in = def_node->in(j);
1757 if (in == phi) {
1758 loop_head->mark_has_reductions();
1759 def_node->add_flag(Node::Flag_is_reduction);
1760 break;
1761 }
1762 }
1763 }
1764 }
1765 }
1766 }
1767 }
1768 }
1769 }
1770
1771 //------------------------------dominates_backedge---------------------------------
1772 // Returns true if ctrl is executed on every complete iteration
1773 bool IdealLoopTree::dominates_backedge(Node* ctrl) {
1774 assert(ctrl->is_CFG(), "must be control");
1775 Node* backedge = _head->as_Loop()->in(LoopNode::LoopBackControl);
1776 return _phase->dom_lca_internal(ctrl, backedge) == ctrl;
1777 }
1778
1779 //------------------------------adjust_limit-----------------------------------
1780 // Helper function for add_constraint().
1781 Node* PhaseIdealLoop::adjust_limit(int stride_con, Node * scale, Node *offset, Node *rc_limit, Node *loop_limit, Node *pre_ctrl) {
1782 // Compute "I :: (limit-offset)/scale"
1783 Node *con = new SubINode(rc_limit, offset);
1784 register_new_node(con, pre_ctrl);
1785 Node *X = new DivINode(0, con, scale);
1786 register_new_node(X, pre_ctrl);
1787
1788 // Adjust loop limit
1789 loop_limit = (stride_con > 0)
1790 ? (Node*)(new MinINode(loop_limit, X))
1791 : (Node*)(new MaxINode(loop_limit, X));
1792 register_new_node(loop_limit, pre_ctrl);
1793 return loop_limit;
1794 }
1795
1796 //------------------------------add_constraint---------------------------------
1797 // Constrain the main loop iterations so the conditions:
1798 // low_limit <= scale_con * I + offset < upper_limit
1799 // always holds true. That is, either increase the number of iterations in
1800 // the pre-loop or the post-loop until the condition holds true in the main
1801 // loop. Stride, scale, offset and limit are all loop invariant. Further,
1802 // stride and scale are constants (offset and limit often are).
1803 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 ) {
1804 // For positive stride, the pre-loop limit always uses a MAX function
1805 // and the main loop a MIN function. For negative stride these are
1806 // reversed.
1807
1808 // Also for positive stride*scale the affine function is increasing, so the
1809 // pre-loop must check for underflow and the post-loop for overflow.
1810 // Negative stride*scale reverses this; pre-loop checks for overflow and
1811 // post-loop for underflow.
1812
1813 Node *scale = _igvn.intcon(scale_con);
1814 set_ctrl(scale, C->root());
1815
1816 if ((stride_con^scale_con) >= 0) { // Use XOR to avoid overflow
1817 // The overflow limit: scale*I+offset < upper_limit
1818 // For main-loop compute
1819 // ( if (scale > 0) /* and stride > 0 */
1820 // I < (upper_limit-offset)/scale
1821 // else /* scale < 0 and stride < 0 */
1822 // I > (upper_limit-offset)/scale
1823 // )
1824 //
1825 // (upper_limit-offset) may overflow or underflow.
1826 // But it is fine since main loop will either have
1827 // less iterations or will be skipped in such case.
1828 *main_limit = adjust_limit(stride_con, scale, offset, upper_limit, *main_limit, pre_ctrl);
1829
1830 // The underflow limit: low_limit <= scale*I+offset.
1831 // For pre-loop compute
1832 // NOT(scale*I+offset >= low_limit)
1833 // scale*I+offset < low_limit
1834 // ( if (scale > 0) /* and stride > 0 */
1835 // I < (low_limit-offset)/scale
1836 // else /* scale < 0 and stride < 0 */
1837 // I > (low_limit-offset)/scale
1838 // )
1839
1840 if (low_limit->get_int() == -max_jint) {
1841 if (!RangeLimitCheck) return;
1842 // We need this guard when scale*pre_limit+offset >= limit
1843 // due to underflow. So we need execute pre-loop until
1844 // scale*I+offset >= min_int. But (min_int-offset) will
1845 // underflow when offset > 0 and X will be > original_limit
1846 // when stride > 0. To avoid it we replace positive offset with 0.
1847 //
1848 // Also (min_int+1 == -max_int) is used instead of min_int here
1849 // to avoid problem with scale == -1 (min_int/(-1) == min_int).
1850 Node* shift = _igvn.intcon(31);
1851 set_ctrl(shift, C->root());
1852 Node* sign = new RShiftINode(offset, shift);
1853 register_new_node(sign, pre_ctrl);
1854 offset = new AndINode(offset, sign);
1855 register_new_node(offset, pre_ctrl);
1856 } else {
1857 assert(low_limit->get_int() == 0, "wrong low limit for range check");
1858 // The only problem we have here when offset == min_int
1859 // since (0-min_int) == min_int. It may be fine for stride > 0
1860 // but for stride < 0 X will be < original_limit. To avoid it
1861 // max(pre_limit, original_limit) is used in do_range_check().
1862 }
1863 // Pass (-stride) to indicate pre_loop_cond = NOT(main_loop_cond);
1864 *pre_limit = adjust_limit((-stride_con), scale, offset, low_limit, *pre_limit, pre_ctrl);
1865
1866 } else { // stride_con*scale_con < 0
1867 // For negative stride*scale pre-loop checks for overflow and
1868 // post-loop for underflow.
1869 //
1870 // The overflow limit: scale*I+offset < upper_limit
1871 // For pre-loop compute
1872 // NOT(scale*I+offset < upper_limit)
1873 // scale*I+offset >= upper_limit
1874 // scale*I+offset+1 > upper_limit
1875 // ( if (scale < 0) /* and stride > 0 */
1876 // I < (upper_limit-(offset+1))/scale
1877 // else /* scale > 0 and stride < 0 */
1878 // I > (upper_limit-(offset+1))/scale
1879 // )
1880 //
1881 // (upper_limit-offset-1) may underflow or overflow.
1882 // To avoid it min(pre_limit, original_limit) is used
1883 // in do_range_check() for stride > 0 and max() for < 0.
1884 Node *one = _igvn.intcon(1);
1885 set_ctrl(one, C->root());
1886
1887 Node *plus_one = new AddINode(offset, one);
1888 register_new_node( plus_one, pre_ctrl );
1889 // Pass (-stride) to indicate pre_loop_cond = NOT(main_loop_cond);
1890 *pre_limit = adjust_limit((-stride_con), scale, plus_one, upper_limit, *pre_limit, pre_ctrl);
1891
1892 if (low_limit->get_int() == -max_jint) {
1893 if (!RangeLimitCheck) return;
1894 // We need this guard when scale*main_limit+offset >= limit
1895 // due to underflow. So we need execute main-loop while
1896 // scale*I+offset+1 > min_int. But (min_int-offset-1) will
1897 // underflow when (offset+1) > 0 and X will be < main_limit
1898 // when scale < 0 (and stride > 0). To avoid it we replace
1899 // positive (offset+1) with 0.
1900 //
1901 // Also (min_int+1 == -max_int) is used instead of min_int here
1902 // to avoid problem with scale == -1 (min_int/(-1) == min_int).
1903 Node* shift = _igvn.intcon(31);
1904 set_ctrl(shift, C->root());
1905 Node* sign = new RShiftINode(plus_one, shift);
1906 register_new_node(sign, pre_ctrl);
1907 plus_one = new AndINode(plus_one, sign);
1908 register_new_node(plus_one, pre_ctrl);
1909 } else {
1910 assert(low_limit->get_int() == 0, "wrong low limit for range check");
1911 // The only problem we have here when offset == max_int
1912 // since (max_int+1) == min_int and (0-min_int) == min_int.
1913 // But it is fine since main loop will either have
1914 // less iterations or will be skipped in such case.
1915 }
1916 // The underflow limit: low_limit <= scale*I+offset.
1917 // For main-loop compute
1918 // scale*I+offset+1 > low_limit
1919 // ( if (scale < 0) /* and stride > 0 */
1920 // I < (low_limit-(offset+1))/scale
1921 // else /* scale > 0 and stride < 0 */
1922 // I > (low_limit-(offset+1))/scale
1923 // )
1924
1925 *main_limit = adjust_limit(stride_con, scale, plus_one, low_limit, *main_limit, pre_ctrl);
1926 }
1927 }
1928
1929
1930 //------------------------------is_scaled_iv---------------------------------
1931 // Return true if exp is a constant times an induction var
1932 bool PhaseIdealLoop::is_scaled_iv(Node* exp, Node* iv, int* p_scale) {
1933 if (exp == iv) {
1934 if (p_scale != NULL) {
1935 *p_scale = 1;
1936 }
1937 return true;
1938 }
1939 int opc = exp->Opcode();
1940 if (opc == Op_MulI) {
1941 if (exp->in(1) == iv && exp->in(2)->is_Con()) {
1942 if (p_scale != NULL) {
1943 *p_scale = exp->in(2)->get_int();
1944 }
1945 return true;
1946 }
1947 if (exp->in(2) == iv && exp->in(1)->is_Con()) {
1948 if (p_scale != NULL) {
1949 *p_scale = exp->in(1)->get_int();
1950 }
1951 return true;
1952 }
1953 } else if (opc == Op_LShiftI) {
1954 if (exp->in(1) == iv && exp->in(2)->is_Con()) {
1955 if (p_scale != NULL) {
1956 *p_scale = 1 << exp->in(2)->get_int();
1957 }
1958 return true;
1959 }
1960 }
1961 return false;
1962 }
1963
1964 //-----------------------------is_scaled_iv_plus_offset------------------------------
1965 // Return true if exp is a simple induction variable expression: k1*iv + (invar + k2)
1966 bool PhaseIdealLoop::is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth) {
1967 if (is_scaled_iv(exp, iv, p_scale)) {
1968 if (p_offset != NULL) {
1969 Node *zero = _igvn.intcon(0);
1970 set_ctrl(zero, C->root());
1971 *p_offset = zero;
1972 }
1973 return true;
1974 }
1975 int opc = exp->Opcode();
1976 if (opc == Op_AddI) {
1977 if (is_scaled_iv(exp->in(1), iv, p_scale)) {
1978 if (p_offset != NULL) {
1979 *p_offset = exp->in(2);
1980 }
1981 return true;
1982 }
1983 if (exp->in(2)->is_Con()) {
1984 Node* offset2 = NULL;
1985 if (depth < 2 &&
1986 is_scaled_iv_plus_offset(exp->in(1), iv, p_scale,
1987 p_offset != NULL ? &offset2 : NULL, depth+1)) {
1988 if (p_offset != NULL) {
1989 Node *ctrl_off2 = get_ctrl(offset2);
1990 Node* offset = new AddINode(offset2, exp->in(2));
1991 register_new_node(offset, ctrl_off2);
1992 *p_offset = offset;
1993 }
1994 return true;
1995 }
1996 }
1997 } else if (opc == Op_SubI) {
1998 if (is_scaled_iv(exp->in(1), iv, p_scale)) {
1999 if (p_offset != NULL) {
2000 Node *zero = _igvn.intcon(0);
2001 set_ctrl(zero, C->root());
2002 Node *ctrl_off = get_ctrl(exp->in(2));
2003 Node* offset = new SubINode(zero, exp->in(2));
2004 register_new_node(offset, ctrl_off);
2005 *p_offset = offset;
2006 }
2007 return true;
2008 }
2009 if (is_scaled_iv(exp->in(2), iv, p_scale)) {
2010 if (p_offset != NULL) {
2011 *p_scale *= -1;
2012 *p_offset = exp->in(1);
2013 }
2014 return true;
2015 }
2016 }
2017 return false;
2018 }
2019
2020 //------------------------------do_range_check---------------------------------
2021 // Eliminate range-checks and other trip-counter vs loop-invariant tests.
2022 void PhaseIdealLoop::do_range_check( IdealLoopTree *loop, Node_List &old_new ) {
2023 #ifndef PRODUCT
2024 if (PrintOpto && VerifyLoopOptimizations) {
2025 tty->print("Range Check Elimination ");
2026 loop->dump_head();
2027 } else if (TraceLoopOpts) {
2028 tty->print("RangeCheck ");
2029 loop->dump_head();
2030 }
2031 #endif
2032 assert(RangeCheckElimination, "");
2033 CountedLoopNode *cl = loop->_head->as_CountedLoop();
2034 assert(cl->is_main_loop(), "");
2035
2036 // protect against stride not being a constant
2037 if (!cl->stride_is_con())
2038 return;
2039
2040 // Find the trip counter; we are iteration splitting based on it
2041 Node *trip_counter = cl->phi();
2042 // Find the main loop limit; we will trim it's iterations
2043 // to not ever trip end tests
2044 Node *main_limit = cl->limit();
2045
2046 // Need to find the main-loop zero-trip guard
2047 Node *ctrl = cl->in(LoopNode::EntryControl);
2048 assert(ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "");
2049 Node *iffm = ctrl->in(0);
2050 assert(iffm->Opcode() == Op_If, "");
2051 Node *bolzm = iffm->in(1);
2052 assert(bolzm->Opcode() == Op_Bool, "");
2053 Node *cmpzm = bolzm->in(1);
2054 assert(cmpzm->is_Cmp(), "");
2055 Node *opqzm = cmpzm->in(2);
2056 // Can not optimize a loop if zero-trip Opaque1 node is optimized
2057 // away and then another round of loop opts attempted.
2058 if (opqzm->Opcode() != Op_Opaque1)
2059 return;
2060 assert(opqzm->in(1) == main_limit, "do not understand situation");
2061
2062 // Find the pre-loop limit; we will expand it's iterations to
2063 // not ever trip low tests.
2064 Node *p_f = iffm->in(0);
2065 assert(p_f->Opcode() == Op_IfFalse, "");
2066 CountedLoopEndNode *pre_end = p_f->in(0)->as_CountedLoopEnd();
2067 assert(pre_end->loopnode()->is_pre_loop(), "");
2068 Node *pre_opaq1 = pre_end->limit();
2069 // Occasionally it's possible for a pre-loop Opaque1 node to be
2070 // optimized away and then another round of loop opts attempted.
2071 // We can not optimize this particular loop in that case.
2072 if (pre_opaq1->Opcode() != Op_Opaque1)
2073 return;
2074 Opaque1Node *pre_opaq = (Opaque1Node*)pre_opaq1;
2075 Node *pre_limit = pre_opaq->in(1);
2076
2077 // Where do we put new limit calculations
2078 Node *pre_ctrl = pre_end->loopnode()->in(LoopNode::EntryControl);
2079
2080 // Ensure the original loop limit is available from the
2081 // pre-loop Opaque1 node.
2082 Node *orig_limit = pre_opaq->original_loop_limit();
2083 if (orig_limit == NULL || _igvn.type(orig_limit) == Type::TOP)
2084 return;
2085
2086 // Must know if its a count-up or count-down loop
2087
2088 int stride_con = cl->stride_con();
2089 Node *zero = _igvn.intcon(0);
2090 Node *one = _igvn.intcon(1);
2091 // Use symmetrical int range [-max_jint,max_jint]
2092 Node *mini = _igvn.intcon(-max_jint);
2093 set_ctrl(zero, C->root());
2094 set_ctrl(one, C->root());
2095 set_ctrl(mini, C->root());
2096
2097 // Range checks that do not dominate the loop backedge (ie.
2098 // conditionally executed) can lengthen the pre loop limit beyond
2099 // the original loop limit. To prevent this, the pre limit is
2100 // (for stride > 0) MINed with the original loop limit (MAXed
2101 // stride < 0) when some range_check (rc) is conditionally
2102 // executed.
2103 bool conditional_rc = false;
2104
2105 // Check loop body for tests of trip-counter plus loop-invariant vs
2106 // loop-invariant.
2107 for( uint i = 0; i < loop->_body.size(); i++ ) {
2108 Node *iff = loop->_body[i];
2109 if( iff->Opcode() == Op_If ) { // Test?
2110
2111 // Test is an IfNode, has 2 projections. If BOTH are in the loop
2112 // we need loop unswitching instead of iteration splitting.
2113 Node *exit = loop->is_loop_exit(iff);
2114 if( !exit ) continue;
2115 int flip = (exit->Opcode() == Op_IfTrue) ? 1 : 0;
2116
2117 // Get boolean condition to test
2118 Node *i1 = iff->in(1);
2119 if( !i1->is_Bool() ) continue;
2120 BoolNode *bol = i1->as_Bool();
2121 BoolTest b_test = bol->_test;
2122 // Flip sense of test if exit condition is flipped
2123 if( flip )
2124 b_test = b_test.negate();
2125
2126 // Get compare
2127 Node *cmp = bol->in(1);
2128
2129 // Look for trip_counter + offset vs limit
2130 Node *rc_exp = cmp->in(1);
2131 Node *limit = cmp->in(2);
2132 jint scale_con= 1; // Assume trip counter not scaled
2133
2134 Node *limit_c = get_ctrl(limit);
2135 if( loop->is_member(get_loop(limit_c) ) ) {
2136 // Compare might have operands swapped; commute them
2137 b_test = b_test.commute();
2138 rc_exp = cmp->in(2);
2139 limit = cmp->in(1);
2140 limit_c = get_ctrl(limit);
2141 if( loop->is_member(get_loop(limit_c) ) )
2142 continue; // Both inputs are loop varying; cannot RCE
2143 }
2144 // Here we know 'limit' is loop invariant
2145
2146 // 'limit' maybe pinned below the zero trip test (probably from a
2147 // previous round of rce), in which case, it can't be used in the
2148 // zero trip test expression which must occur before the zero test's if.
2149 if( limit_c == ctrl ) {
2150 continue; // Don't rce this check but continue looking for other candidates.
2151 }
2152
2153 // Check for scaled induction variable plus an offset
2154 Node *offset = NULL;
2155
2156 if (!is_scaled_iv_plus_offset(rc_exp, trip_counter, &scale_con, &offset)) {
2157 continue;
2158 }
2159
2160 Node *offset_c = get_ctrl(offset);
2161 if( loop->is_member( get_loop(offset_c) ) )
2162 continue; // Offset is not really loop invariant
2163 // Here we know 'offset' is loop invariant.
2164
2165 // As above for the 'limit', the 'offset' maybe pinned below the
2166 // zero trip test.
2167 if( offset_c == ctrl ) {
2168 continue; // Don't rce this check but continue looking for other candidates.
2169 }
2170 #ifdef ASSERT
2171 if (TraceRangeLimitCheck) {
2172 tty->print_cr("RC bool node%s", flip ? " flipped:" : ":");
2173 bol->dump(2);
2174 }
2175 #endif
2176 // At this point we have the expression as:
2177 // scale_con * trip_counter + offset :: limit
2178 // where scale_con, offset and limit are loop invariant. Trip_counter
2179 // monotonically increases by stride_con, a constant. Both (or either)
2180 // stride_con and scale_con can be negative which will flip about the
2181 // sense of the test.
2182
2183 // Adjust pre and main loop limits to guard the correct iteration set
2184 if( cmp->Opcode() == Op_CmpU ) {// Unsigned compare is really 2 tests
2185 if( b_test._test == BoolTest::lt ) { // Range checks always use lt
2186 // The underflow and overflow limits: 0 <= scale*I+offset < limit
2187 add_constraint( stride_con, scale_con, offset, zero, limit, pre_ctrl, &pre_limit, &main_limit );
2188 if (!conditional_rc) {
2189 // (0-offset)/scale could be outside of loop iterations range.
2190 conditional_rc = !loop->dominates_backedge(iff) || RangeLimitCheck;
2191 }
2192 } else {
2193 #ifndef PRODUCT
2194 if( PrintOpto )
2195 tty->print_cr("missed RCE opportunity");
2196 #endif
2197 continue; // In release mode, ignore it
2198 }
2199 } else { // Otherwise work on normal compares
2200 switch( b_test._test ) {
2201 case BoolTest::gt:
2202 // Fall into GE case
2203 case BoolTest::ge:
2204 // Convert (I*scale+offset) >= Limit to (I*(-scale)+(-offset)) <= -Limit
2205 scale_con = -scale_con;
2206 offset = new SubINode( zero, offset );
2207 register_new_node( offset, pre_ctrl );
2208 limit = new SubINode( zero, limit );
2209 register_new_node( limit, pre_ctrl );
2210 // Fall into LE case
2211 case BoolTest::le:
2212 if (b_test._test != BoolTest::gt) {
2213 // Convert X <= Y to X < Y+1
2214 limit = new AddINode( limit, one );
2215 register_new_node( limit, pre_ctrl );
2216 }
2217 // Fall into LT case
2218 case BoolTest::lt:
2219 // The underflow and overflow limits: MIN_INT <= scale*I+offset < limit
2220 // Note: (MIN_INT+1 == -MAX_INT) is used instead of MIN_INT here
2221 // to avoid problem with scale == -1: MIN_INT/(-1) == MIN_INT.
2222 add_constraint( stride_con, scale_con, offset, mini, limit, pre_ctrl, &pre_limit, &main_limit );
2223 if (!conditional_rc) {
2224 // ((MIN_INT+1)-offset)/scale could be outside of loop iterations range.
2225 // Note: negative offset is replaced with 0 but (MIN_INT+1)/scale could
2226 // still be outside of loop range.
2227 conditional_rc = !loop->dominates_backedge(iff) || RangeLimitCheck;
2228 }
2229 break;
2230 default:
2231 #ifndef PRODUCT
2232 if( PrintOpto )
2233 tty->print_cr("missed RCE opportunity");
2234 #endif
2235 continue; // Unhandled case
2236 }
2237 }
2238
2239 // Kill the eliminated test
2240 C->set_major_progress();
2241 Node *kill_con = _igvn.intcon( 1-flip );
2242 set_ctrl(kill_con, C->root());
2243 _igvn.replace_input_of(iff, 1, kill_con);
2244 // Find surviving projection
2245 assert(iff->is_If(), "");
2246 ProjNode* dp = ((IfNode*)iff)->proj_out(1-flip);
2247 // Find loads off the surviving projection; remove their control edge
2248 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
2249 Node* cd = dp->fast_out(i); // Control-dependent node
2250 if (cd->is_Load() && cd->depends_only_on_test()) { // Loads can now float around in the loop
2251 // Allow the load to float around in the loop, or before it
2252 // but NOT before the pre-loop.
2253 _igvn.replace_input_of(cd, 0, ctrl); // ctrl, not NULL
2254 --i;
2255 --imax;
2256 }
2257 }
2258
2259 } // End of is IF
2260
2261 }
2262
2263 // Update loop limits
2264 if (conditional_rc) {
2265 pre_limit = (stride_con > 0) ? (Node*)new MinINode(pre_limit, orig_limit)
2266 : (Node*)new MaxINode(pre_limit, orig_limit);
2267 register_new_node(pre_limit, pre_ctrl);
2268 }
2269 _igvn.replace_input_of(pre_opaq, 1, pre_limit);
2270
2271 // Note:: we are making the main loop limit no longer precise;
2272 // need to round up based on stride.
2273 cl->set_nonexact_trip_count();
2274 if (!LoopLimitCheck && stride_con != 1 && stride_con != -1) { // Cutout for common case
2275 // "Standard" round-up logic: ([main_limit-init+(y-1)]/y)*y+init
2276 // Hopefully, compiler will optimize for powers of 2.
2277 Node *ctrl = get_ctrl(main_limit);
2278 Node *stride = cl->stride();
2279 Node *init = cl->init_trip()->uncast();
2280 Node *span = new SubINode(main_limit,init);
2281 register_new_node(span,ctrl);
2282 Node *rndup = _igvn.intcon(stride_con + ((stride_con>0)?-1:1));
2283 Node *add = new AddINode(span,rndup);
2284 register_new_node(add,ctrl);
2285 Node *div = new DivINode(0,add,stride);
2286 register_new_node(div,ctrl);
2287 Node *mul = new MulINode(div,stride);
2288 register_new_node(mul,ctrl);
2289 Node *newlim = new AddINode(mul,init);
2290 register_new_node(newlim,ctrl);
2291 main_limit = newlim;
2292 }
2293
2294 Node *main_cle = cl->loopexit();
2295 Node *main_bol = main_cle->in(1);
2296 // Hacking loop bounds; need private copies of exit test
2297 if( main_bol->outcnt() > 1 ) {// BoolNode shared?
2298 main_bol = main_bol->clone();// Clone a private BoolNode
2299 register_new_node( main_bol, main_cle->in(0) );
2300 _igvn.replace_input_of(main_cle, 1, main_bol);
2301 }
2302 Node *main_cmp = main_bol->in(1);
2303 if( main_cmp->outcnt() > 1 ) { // CmpNode shared?
2304 main_cmp = main_cmp->clone();// Clone a private CmpNode
2305 register_new_node( main_cmp, main_cle->in(0) );
2306 _igvn.replace_input_of(main_bol, 1, main_cmp);
2307 }
2308 // Hack the now-private loop bounds
2309 _igvn.replace_input_of(main_cmp, 2, main_limit);
2310 // The OpaqueNode is unshared by design
2311 assert( opqzm->outcnt() == 1, "cannot hack shared node" );
2312 _igvn.replace_input_of(opqzm, 1, main_limit);
2313 }
2314
2315 //------------------------------DCE_loop_body----------------------------------
2316 // Remove simplistic dead code from loop body
2317 void IdealLoopTree::DCE_loop_body() {
2318 for( uint i = 0; i < _body.size(); i++ )
2319 if( _body.at(i)->outcnt() == 0 )
2320 _body.map( i--, _body.pop() );
2321 }
2322
2323
2324 //------------------------------adjust_loop_exit_prob--------------------------
2325 // Look for loop-exit tests with the 50/50 (or worse) guesses from the parsing stage.
2326 // Replace with a 1-in-10 exit guess.
2327 void IdealLoopTree::adjust_loop_exit_prob( PhaseIdealLoop *phase ) {
2328 Node *test = tail();
2329 while( test != _head ) {
2330 uint top = test->Opcode();
2331 if( top == Op_IfTrue || top == Op_IfFalse ) {
2332 int test_con = ((ProjNode*)test)->_con;
2333 assert(top == (uint)(test_con? Op_IfTrue: Op_IfFalse), "sanity");
2334 IfNode *iff = test->in(0)->as_If();
2335 if( iff->outcnt() == 2 ) { // Ignore dead tests
2336 Node *bol = iff->in(1);
2337 if( bol && bol->req() > 1 && bol->in(1) &&
2338 ((bol->in(1)->Opcode() == Op_StorePConditional ) ||
2339 (bol->in(1)->Opcode() == Op_StoreIConditional ) ||
2340 (bol->in(1)->Opcode() == Op_StoreLConditional ) ||
2341 (bol->in(1)->Opcode() == Op_CompareAndSwapI ) ||
2342 (bol->in(1)->Opcode() == Op_CompareAndSwapL ) ||
2343 (bol->in(1)->Opcode() == Op_CompareAndSwapP ) ||
2344 (bol->in(1)->Opcode() == Op_CompareAndSwapN )))
2345 return; // Allocation loops RARELY take backedge
2346 // Find the OTHER exit path from the IF
2347 Node* ex = iff->proj_out(1-test_con);
2348 float p = iff->_prob;
2349 if( !phase->is_member( this, ex ) && iff->_fcnt == COUNT_UNKNOWN ) {
2350 if( top == Op_IfTrue ) {
2351 if( p < (PROB_FAIR + PROB_UNLIKELY_MAG(3))) {
2352 iff->_prob = PROB_STATIC_FREQUENT;
2353 }
2354 } else {
2355 if( p > (PROB_FAIR - PROB_UNLIKELY_MAG(3))) {
2356 iff->_prob = PROB_STATIC_INFREQUENT;
2357 }
2358 }
2359 }
2360 }
2361 }
2362 test = phase->idom(test);
2363 }
2364 }
2365
2366
2367 //------------------------------policy_do_remove_empty_loop--------------------
2368 // Micro-benchmark spamming. Policy is to always remove empty loops.
2369 // The 'DO' part is to replace the trip counter with the value it will
2370 // have on the last iteration. This will break the loop.
2371 bool IdealLoopTree::policy_do_remove_empty_loop( PhaseIdealLoop *phase ) {
2372 // Minimum size must be empty loop
2373 if (_body.size() > EMPTY_LOOP_SIZE)
2374 return false;
2375
2376 if (!_head->is_CountedLoop())
2377 return false; // Dead loop
2378 CountedLoopNode *cl = _head->as_CountedLoop();
2379 if (!cl->is_valid_counted_loop())
2380 return false; // Malformed loop
2381 if (!phase->is_member(this, phase->get_ctrl(cl->loopexit()->in(CountedLoopEndNode::TestValue))))
2382 return false; // Infinite loop
2383
2384 #ifdef ASSERT
2385 // Ensure only one phi which is the iv.
2386 Node* iv = NULL;
2387 for (DUIterator_Fast imax, i = cl->fast_outs(imax); i < imax; i++) {
2388 Node* n = cl->fast_out(i);
2389 if (n->Opcode() == Op_Phi) {
2390 assert(iv == NULL, "Too many phis" );
2391 iv = n;
2392 }
2393 }
2394 assert(iv == cl->phi(), "Wrong phi" );
2395 #endif
2396
2397 // main and post loops have explicitly created zero trip guard
2398 bool needs_guard = !cl->is_main_loop() && !cl->is_post_loop();
2399 if (needs_guard) {
2400 // Skip guard if values not overlap.
2401 const TypeInt* init_t = phase->_igvn.type(cl->init_trip())->is_int();
2402 const TypeInt* limit_t = phase->_igvn.type(cl->limit())->is_int();
2403 int stride_con = cl->stride_con();
2404 if (stride_con > 0) {
2405 needs_guard = (init_t->_hi >= limit_t->_lo);
2406 } else {
2407 needs_guard = (init_t->_lo <= limit_t->_hi);
2408 }
2409 }
2410 if (needs_guard) {
2411 // Check for an obvious zero trip guard.
2412 Node* inctrl = PhaseIdealLoop::skip_loop_predicates(cl->in(LoopNode::EntryControl));
2413 if (inctrl->Opcode() == Op_IfTrue) {
2414 // The test should look like just the backedge of a CountedLoop
2415 Node* iff = inctrl->in(0);
2416 if (iff->is_If()) {
2417 Node* bol = iff->in(1);
2418 if (bol->is_Bool() && bol->as_Bool()->_test._test == cl->loopexit()->test_trip()) {
2419 Node* cmp = bol->in(1);
2420 if (cmp->is_Cmp() && cmp->in(1) == cl->init_trip() && cmp->in(2) == cl->limit()) {
2421 needs_guard = false;
2422 }
2423 }
2424 }
2425 }
2426 }
2427
2428 #ifndef PRODUCT
2429 if (PrintOpto) {
2430 tty->print("Removing empty loop with%s zero trip guard", needs_guard ? "out" : "");
2431 this->dump_head();
2432 } else if (TraceLoopOpts) {
2433 tty->print("Empty with%s zero trip guard ", needs_guard ? "out" : "");
2434 this->dump_head();
2435 }
2436 #endif
2437
2438 if (needs_guard) {
2439 // Peel the loop to ensure there's a zero trip guard
2440 Node_List old_new;
2441 phase->do_peeling(this, old_new);
2442 }
2443
2444 // Replace the phi at loop head with the final value of the last
2445 // iteration. Then the CountedLoopEnd will collapse (backedge never
2446 // taken) and all loop-invariant uses of the exit values will be correct.
2447 Node *phi = cl->phi();
2448 Node *exact_limit = phase->exact_limit(this);
2449 if (exact_limit != cl->limit()) {
2450 // We also need to replace the original limit to collapse loop exit.
2451 Node* cmp = cl->loopexit()->cmp_node();
2452 assert(cl->limit() == cmp->in(2), "sanity");
2453 phase->_igvn._worklist.push(cmp->in(2)); // put limit on worklist
2454 phase->_igvn.replace_input_of(cmp, 2, exact_limit); // put cmp on worklist
2455 }
2456 // Note: the final value after increment should not overflow since
2457 // counted loop has limit check predicate.
2458 Node *final = new SubINode( exact_limit, cl->stride() );
2459 phase->register_new_node(final,cl->in(LoopNode::EntryControl));
2460 phase->_igvn.replace_node(phi,final);
2461 phase->C->set_major_progress();
2462 return true;
2463 }
2464
2465 //------------------------------policy_do_one_iteration_loop-------------------
2466 // Convert one iteration loop into normal code.
2467 bool IdealLoopTree::policy_do_one_iteration_loop( PhaseIdealLoop *phase ) {
2468 if (!_head->as_Loop()->is_valid_counted_loop())
2469 return false; // Only for counted loop
2470
2471 CountedLoopNode *cl = _head->as_CountedLoop();
2472 if (!cl->has_exact_trip_count() || cl->trip_count() != 1) {
2473 return false;
2474 }
2475
2476 #ifndef PRODUCT
2477 if(TraceLoopOpts) {
2478 tty->print("OneIteration ");
2479 this->dump_head();
2480 }
2481 #endif
2482
2483 Node *init_n = cl->init_trip();
2484 #ifdef ASSERT
2485 // Loop boundaries should be constant since trip count is exact.
2486 assert(init_n->get_int() + cl->stride_con() >= cl->limit()->get_int(), "should be one iteration");
2487 #endif
2488 // Replace the phi at loop head with the value of the init_trip.
2489 // Then the CountedLoopEnd will collapse (backedge will not be taken)
2490 // and all loop-invariant uses of the exit values will be correct.
2491 phase->_igvn.replace_node(cl->phi(), cl->init_trip());
2492 phase->C->set_major_progress();
2493 return true;
2494 }
2495
2496 //=============================================================================
2497 //------------------------------iteration_split_impl---------------------------
2498 bool IdealLoopTree::iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new ) {
2499 // Compute exact loop trip count if possible.
2500 compute_exact_trip_count(phase);
2501
2502 // Convert one iteration loop into normal code.
2503 if (policy_do_one_iteration_loop(phase))
2504 return true;
2505
2506 // Check and remove empty loops (spam micro-benchmarks)
2507 if (policy_do_remove_empty_loop(phase))
2508 return true; // Here we removed an empty loop
2509
2510 bool should_peel = policy_peeling(phase); // Should we peel?
2511
2512 bool should_unswitch = policy_unswitching(phase);
2513
2514 // Non-counted loops may be peeled; exactly 1 iteration is peeled.
2515 // This removes loop-invariant tests (usually null checks).
2516 if (!_head->is_CountedLoop()) { // Non-counted loop
2517 if (PartialPeelLoop && phase->partial_peel(this, old_new)) {
2518 // Partial peel succeeded so terminate this round of loop opts
2519 return false;
2520 }
2521 if (should_peel) { // Should we peel?
2522 #ifndef PRODUCT
2523 if (PrintOpto) tty->print_cr("should_peel");
2524 #endif
2525 phase->do_peeling(this,old_new);
2526 } else if (should_unswitch) {
2527 phase->do_unswitching(this, old_new);
2528 }
2529 return true;
2530 }
2531 CountedLoopNode *cl = _head->as_CountedLoop();
2532
2533 if (!cl->is_valid_counted_loop()) return true; // Ignore various kinds of broken loops
2534
2535 // Do nothing special to pre- and post- loops
2536 if (cl->is_pre_loop() || cl->is_post_loop()) return true;
2537
2538 // Compute loop trip count from profile data
2539 compute_profile_trip_cnt(phase);
2540
2541 // Before attempting fancy unrolling, RCE or alignment, see if we want
2542 // to completely unroll this loop or do loop unswitching.
2543 if (cl->is_normal_loop()) {
2544 if (should_unswitch) {
2545 phase->do_unswitching(this, old_new);
2546 return true;
2547 }
2548 bool should_maximally_unroll = policy_maximally_unroll(phase);
2549 if (should_maximally_unroll) {
2550 // Here we did some unrolling and peeling. Eventually we will
2551 // completely unroll this loop and it will no longer be a loop.
2552 phase->do_maximally_unroll(this,old_new);
2553 return true;
2554 }
2555 }
2556
2557 // Skip next optimizations if running low on nodes. Note that
2558 // policy_unswitching and policy_maximally_unroll have this check.
2559 int nodes_left = phase->C->max_node_limit() - phase->C->live_nodes();
2560 if ((int)(2 * _body.size()) > nodes_left) {
2561 return true;
2562 }
2563
2564 // Counted loops may be peeled, may need some iterations run up
2565 // front for RCE, and may want to align loop refs to a cache
2566 // line. Thus we clone a full loop up front whose trip count is
2567 // at least 1 (if peeling), but may be several more.
2568
2569 // The main loop will start cache-line aligned with at least 1
2570 // iteration of the unrolled body (zero-trip test required) and
2571 // will have some range checks removed.
2572
2573 // A post-loop will finish any odd iterations (leftover after
2574 // unrolling), plus any needed for RCE purposes.
2575
2576 bool should_unroll = policy_unroll(phase);
2577
2578 bool should_rce = policy_range_check(phase);
2579
2580 bool should_align = policy_align(phase);
2581
2582 // If not RCE'ing (iteration splitting) or Aligning, then we do not
2583 // need a pre-loop. We may still need to peel an initial iteration but
2584 // we will not be needing an unknown number of pre-iterations.
2585 //
2586 // Basically, if may_rce_align reports FALSE first time through,
2587 // we will not be able to later do RCE or Aligning on this loop.
2588 bool may_rce_align = !policy_peel_only(phase) || should_rce || should_align;
2589
2590 // If we have any of these conditions (RCE, alignment, unrolling) met, then
2591 // we switch to the pre-/main-/post-loop model. This model also covers
2592 // peeling.
2593 if (should_rce || should_align || should_unroll) {
2594 if (cl->is_normal_loop()) // Convert to 'pre/main/post' loops
2595 phase->insert_pre_post_loops(this,old_new, !may_rce_align);
2596
2597 // Adjust the pre- and main-loop limits to let the pre and post loops run
2598 // with full checks, but the main-loop with no checks. Remove said
2599 // checks from the main body.
2600 if (should_rce)
2601 phase->do_range_check(this,old_new);
2602
2603 // Double loop body for unrolling. Adjust the minimum-trip test (will do
2604 // twice as many iterations as before) and the main body limit (only do
2605 // an even number of trips). If we are peeling, we might enable some RCE
2606 // and we'd rather unroll the post-RCE'd loop SO... do not unroll if
2607 // peeling.
2608 if (should_unroll && !should_peel) {
2609 phase->do_unroll(this, old_new, true);
2610 }
2611
2612 // Adjust the pre-loop limits to align the main body
2613 // iterations.
2614 if (should_align)
2615 Unimplemented();
2616
2617 } else { // Else we have an unchanged counted loop
2618 if (should_peel) // Might want to peel but do nothing else
2619 phase->do_peeling(this,old_new);
2620 }
2621 return true;
2622 }
2623
2624
2625 //=============================================================================
2626 //------------------------------iteration_split--------------------------------
2627 bool IdealLoopTree::iteration_split( PhaseIdealLoop *phase, Node_List &old_new ) {
2628 // Recursively iteration split nested loops
2629 if (_child && !_child->iteration_split(phase, old_new))
2630 return false;
2631
2632 // Clean out prior deadwood
2633 DCE_loop_body();
2634
2635
2636 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage.
2637 // Replace with a 1-in-10 exit guess.
2638 if (_parent /*not the root loop*/ &&
2639 !_irreducible &&
2640 // Also ignore the occasional dead backedge
2641 !tail()->is_top()) {
2642 adjust_loop_exit_prob(phase);
2643 }
2644
2645 // Gate unrolling, RCE and peeling efforts.
2646 if (!_child && // If not an inner loop, do not split
2647 !_irreducible &&
2648 _allow_optimizations &&
2649 !tail()->is_top()) { // Also ignore the occasional dead backedge
2650 if (!_has_call) {
2651 if (!iteration_split_impl(phase, old_new)) {
2652 return false;
2653 }
2654 } else if (policy_unswitching(phase)) {
2655 phase->do_unswitching(this, old_new);
2656 }
2657 }
2658
2659 // Minor offset re-organization to remove loop-fallout uses of
2660 // trip counter when there was no major reshaping.
2661 phase->reorg_offsets(this);
2662
2663 if (_next && !_next->iteration_split(phase, old_new))
2664 return false;
2665 return true;
2666 }
2667
2668
2669 //=============================================================================
2670 // Process all the loops in the loop tree and replace any fill
2671 // patterns with an intrisc version.
2672 bool PhaseIdealLoop::do_intrinsify_fill() {
2673 bool changed = false;
2674 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
2675 IdealLoopTree* lpt = iter.current();
2676 changed |= intrinsify_fill(lpt);
2677 }
2678 return changed;
2679 }
2680
2681
2682 // Examine an inner loop looking for a a single store of an invariant
2683 // value in a unit stride loop,
2684 bool PhaseIdealLoop::match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value,
2685 Node*& shift, Node*& con) {
2686 const char* msg = NULL;
2687 Node* msg_node = NULL;
2688
2689 store_value = NULL;
2690 con = NULL;
2691 shift = NULL;
2692
2693 // Process the loop looking for stores. If there are multiple
2694 // stores or extra control flow give at this point.
2695 CountedLoopNode* head = lpt->_head->as_CountedLoop();
2696 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) {
2697 Node* n = lpt->_body.at(i);
2698 if (n->outcnt() == 0) continue; // Ignore dead
2699 if (n->is_Store()) {
2700 if (store != NULL) {
2701 msg = "multiple stores";
2702 break;
2703 }
2704 int opc = n->Opcode();
2705 if (opc == Op_StoreP || opc == Op_StoreN || opc == Op_StoreNKlass || opc == Op_StoreCM) {
2706 msg = "oop fills not handled";
2707 break;
2708 }
2709 Node* value = n->in(MemNode::ValueIn);
2710 if (!lpt->is_invariant(value)) {
2711 msg = "variant store value";
2712 } else if (!_igvn.type(n->in(MemNode::Address))->isa_aryptr()) {
2713 msg = "not array address";
2714 }
2715 store = n;
2716 store_value = value;
2717 } else if (n->is_If() && n != head->loopexit()) {
2718 msg = "extra control flow";
2719 msg_node = n;
2720 }
2721 }
2722
2723 if (store == NULL) {
2724 // No store in loop
2725 return false;
2726 }
2727
2728 if (msg == NULL && head->stride_con() != 1) {
2729 // could handle negative strides too
2730 if (head->stride_con() < 0) {
2731 msg = "negative stride";
2732 } else {
2733 msg = "non-unit stride";
2734 }
2735 }
2736
2737 if (msg == NULL && !store->in(MemNode::Address)->is_AddP()) {
2738 msg = "can't handle store address";
2739 msg_node = store->in(MemNode::Address);
2740 }
2741
2742 if (msg == NULL &&
2743 (!store->in(MemNode::Memory)->is_Phi() ||
2744 store->in(MemNode::Memory)->in(LoopNode::LoopBackControl) != store)) {
2745 msg = "store memory isn't proper phi";
2746 msg_node = store->in(MemNode::Memory);
2747 }
2748
2749 // Make sure there is an appropriate fill routine
2750 BasicType t = store->as_Mem()->memory_type();
2751 const char* fill_name;
2752 if (msg == NULL &&
2753 StubRoutines::select_fill_function(t, false, fill_name) == NULL) {
2754 msg = "unsupported store";
2755 msg_node = store;
2756 }
2757
2758 if (msg != NULL) {
2759 #ifndef PRODUCT
2760 if (TraceOptimizeFill) {
2761 tty->print_cr("not fill intrinsic candidate: %s", msg);
2762 if (msg_node != NULL) msg_node->dump();
2763 }
2764 #endif
2765 return false;
2766 }
2767
2768 // Make sure the address expression can be handled. It should be
2769 // head->phi * elsize + con. head->phi might have a ConvI2L.
2770 Node* elements[4];
2771 Node* conv = NULL;
2772 bool found_index = false;
2773 int count = store->in(MemNode::Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
2774 for (int e = 0; e < count; e++) {
2775 Node* n = elements[e];
2776 if (n->is_Con() && con == NULL) {
2777 con = n;
2778 } else if (n->Opcode() == Op_LShiftX && shift == NULL) {
2779 Node* value = n->in(1);
2780 #ifdef _LP64
2781 if (value->Opcode() == Op_ConvI2L) {
2782 conv = value;
2783 value = value->in(1);
2784 }
2785 #endif
2786 if (value != head->phi()) {
2787 msg = "unhandled shift in address";
2788 } else {
2789 if (type2aelembytes(store->as_Mem()->memory_type(), true) != (1 << n->in(2)->get_int())) {
2790 msg = "scale doesn't match";
2791 } else {
2792 found_index = true;
2793 shift = n;
2794 }
2795 }
2796 } else if (n->Opcode() == Op_ConvI2L && conv == NULL) {
2797 if (n->in(1) == head->phi()) {
2798 found_index = true;
2799 conv = n;
2800 } else {
2801 msg = "unhandled input to ConvI2L";
2802 }
2803 } else if (n == head->phi()) {
2804 // no shift, check below for allowed cases
2805 found_index = true;
2806 } else {
2807 msg = "unhandled node in address";
2808 msg_node = n;
2809 }
2810 }
2811
2812 if (count == -1) {
2813 msg = "malformed address expression";
2814 msg_node = store;
2815 }
2816
2817 if (!found_index) {
2818 msg = "missing use of index";
2819 }
2820
2821 // byte sized items won't have a shift
2822 if (msg == NULL && shift == NULL && t != T_BYTE && t != T_BOOLEAN) {
2823 msg = "can't find shift";
2824 msg_node = store;
2825 }
2826
2827 if (msg != NULL) {
2828 #ifndef PRODUCT
2829 if (TraceOptimizeFill) {
2830 tty->print_cr("not fill intrinsic: %s", msg);
2831 if (msg_node != NULL) msg_node->dump();
2832 }
2833 #endif
2834 return false;
2835 }
2836
2837 // No make sure all the other nodes in the loop can be handled
2838 VectorSet ok(Thread::current()->resource_area());
2839
2840 // store related values are ok
2841 ok.set(store->_idx);
2842 ok.set(store->in(MemNode::Memory)->_idx);
2843
2844 CountedLoopEndNode* loop_exit = head->loopexit();
2845 guarantee(loop_exit != NULL, "no loop exit node");
2846
2847 // Loop structure is ok
2848 ok.set(head->_idx);
2849 ok.set(loop_exit->_idx);
2850 ok.set(head->phi()->_idx);
2851 ok.set(head->incr()->_idx);
2852 ok.set(loop_exit->cmp_node()->_idx);
2853 ok.set(loop_exit->in(1)->_idx);
2854
2855 // Address elements are ok
2856 if (con) ok.set(con->_idx);
2857 if (shift) ok.set(shift->_idx);
2858 if (conv) ok.set(conv->_idx);
2859
2860 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) {
2861 Node* n = lpt->_body.at(i);
2862 if (n->outcnt() == 0) continue; // Ignore dead
2863 if (ok.test(n->_idx)) continue;
2864 // Backedge projection is ok
2865 if (n->is_IfTrue() && n->in(0) == loop_exit) continue;
2866 if (!n->is_AddP()) {
2867 msg = "unhandled node";
2868 msg_node = n;
2869 break;
2870 }
2871 }
2872
2873 // Make sure no unexpected values are used outside the loop
2874 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) {
2875 Node* n = lpt->_body.at(i);
2876 // These values can be replaced with other nodes if they are used
2877 // outside the loop.
2878 if (n == store || n == loop_exit || n == head->incr() || n == store->in(MemNode::Memory)) continue;
2879 for (SimpleDUIterator iter(n); iter.has_next(); iter.next()) {
2880 Node* use = iter.get();
2881 if (!lpt->_body.contains(use)) {
2882 msg = "node is used outside loop";
2883 // lpt->_body.dump();
2884 msg_node = n;
2885 break;
2886 }
2887 }
2888 }
2889
2890 #ifdef ASSERT
2891 if (TraceOptimizeFill) {
2892 if (msg != NULL) {
2893 tty->print_cr("no fill intrinsic: %s", msg);
2894 if (msg_node != NULL) msg_node->dump();
2895 } else {
2896 tty->print_cr("fill intrinsic for:");
2897 }
2898 store->dump();
2899 if (Verbose) {
2900 lpt->_body.dump();
2901 }
2902 }
2903 #endif
2904
2905 return msg == NULL;
2906 }
2907
2908
2909
2910 bool PhaseIdealLoop::intrinsify_fill(IdealLoopTree* lpt) {
2911 // Only for counted inner loops
2912 if (!lpt->is_counted() || !lpt->is_inner()) {
2913 return false;
2914 }
2915
2916 // Must have constant stride
2917 CountedLoopNode* head = lpt->_head->as_CountedLoop();
2918 if (!head->is_valid_counted_loop() || !head->is_normal_loop()) {
2919 return false;
2920 }
2921
2922 // Check that the body only contains a store of a loop invariant
2923 // value that is indexed by the loop phi.
2924 Node* store = NULL;
2925 Node* store_value = NULL;
2926 Node* shift = NULL;
2927 Node* offset = NULL;
2928 if (!match_fill_loop(lpt, store, store_value, shift, offset)) {
2929 return false;
2930 }
2931
2932 #ifndef PRODUCT
2933 if (TraceLoopOpts) {
2934 tty->print("ArrayFill ");
2935 lpt->dump_head();
2936 }
2937 #endif
2938
2939 // Now replace the whole loop body by a call to a fill routine that
2940 // covers the same region as the loop.
2941 Node* base = store->in(MemNode::Address)->as_AddP()->in(AddPNode::Base);
2942
2943 // Build an expression for the beginning of the copy region
2944 Node* index = head->init_trip();
2945 #ifdef _LP64
2946 index = new ConvI2LNode(index);
2947 _igvn.register_new_node_with_optimizer(index);
2948 #endif
2949 if (shift != NULL) {
2950 // byte arrays don't require a shift but others do.
2951 index = new LShiftXNode(index, shift->in(2));
2952 _igvn.register_new_node_with_optimizer(index);
2953 }
2954 index = new AddPNode(base, base, index);
2955 _igvn.register_new_node_with_optimizer(index);
2956 Node* from = new AddPNode(base, index, offset);
2957 _igvn.register_new_node_with_optimizer(from);
2958 // Compute the number of elements to copy
2959 Node* len = new SubINode(head->limit(), head->init_trip());
2960 _igvn.register_new_node_with_optimizer(len);
2961
2962 BasicType t = store->as_Mem()->memory_type();
2963 bool aligned = false;
2964 if (offset != NULL && head->init_trip()->is_Con()) {
2965 int element_size = type2aelembytes(t);
2966 aligned = (offset->find_intptr_t_type()->get_con() + head->init_trip()->get_int() * element_size) % HeapWordSize == 0;
2967 }
2968
2969 // Build a call to the fill routine
2970 const char* fill_name;
2971 address fill = StubRoutines::select_fill_function(t, aligned, fill_name);
2972 assert(fill != NULL, "what?");
2973
2974 // Convert float/double to int/long for fill routines
2975 if (t == T_FLOAT) {
2976 store_value = new MoveF2INode(store_value);
2977 _igvn.register_new_node_with_optimizer(store_value);
2978 } else if (t == T_DOUBLE) {
2979 store_value = new MoveD2LNode(store_value);
2980 _igvn.register_new_node_with_optimizer(store_value);
2981 }
2982
2983 if (CCallingConventionRequiresIntsAsLongs &&
2984 // See StubRoutines::select_fill_function for types. FLOAT has been converted to INT.
2985 (t == T_FLOAT || t == T_INT || is_subword_type(t))) {
2986 store_value = new ConvI2LNode(store_value);
2987 _igvn.register_new_node_with_optimizer(store_value);
2988 }
2989
2990 Node* mem_phi = store->in(MemNode::Memory);
2991 Node* result_ctrl;
2992 Node* result_mem;
2993 const TypeFunc* call_type = OptoRuntime::array_fill_Type();
2994 CallLeafNode *call = new CallLeafNoFPNode(call_type, fill,
2995 fill_name, TypeAryPtr::get_array_body_type(t));
2996 uint cnt = 0;
2997 call->init_req(TypeFunc::Parms + cnt++, from);
2998 call->init_req(TypeFunc::Parms + cnt++, store_value);
2999 if (CCallingConventionRequiresIntsAsLongs) {
3000 call->init_req(TypeFunc::Parms + cnt++, C->top());
3001 }
3002 #ifdef _LP64
3003 len = new ConvI2LNode(len);
3004 _igvn.register_new_node_with_optimizer(len);
3005 #endif
3006 call->init_req(TypeFunc::Parms + cnt++, len);
3007 #ifdef _LP64
3008 call->init_req(TypeFunc::Parms + cnt++, C->top());
3009 #endif
3010 call->init_req(TypeFunc::Control, head->init_control());
3011 call->init_req(TypeFunc::I_O, C->top()); // Does no I/O.
3012 call->init_req(TypeFunc::Memory, mem_phi->in(LoopNode::EntryControl));
3013 call->init_req(TypeFunc::ReturnAdr, C->start()->proj_out(TypeFunc::ReturnAdr));
3014 call->init_req(TypeFunc::FramePtr, C->start()->proj_out(TypeFunc::FramePtr));
3015 _igvn.register_new_node_with_optimizer(call);
3016 result_ctrl = new ProjNode(call,TypeFunc::Control);
3017 _igvn.register_new_node_with_optimizer(result_ctrl);
3018 result_mem = new ProjNode(call,TypeFunc::Memory);
3019 _igvn.register_new_node_with_optimizer(result_mem);
3020
3021 /* Disable following optimization until proper fix (add missing checks).
3022
3023 // If this fill is tightly coupled to an allocation and overwrites
3024 // the whole body, allow it to take over the zeroing.
3025 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, this);
3026 if (alloc != NULL && alloc->is_AllocateArray()) {
3027 Node* length = alloc->as_AllocateArray()->Ideal_length();
3028 if (head->limit() == length &&
3029 head->init_trip() == _igvn.intcon(0)) {
3030 if (TraceOptimizeFill) {
3031 tty->print_cr("Eliminated zeroing in allocation");
3032 }
3033 alloc->maybe_set_complete(&_igvn);
3034 } else {
3035 #ifdef ASSERT
3036 if (TraceOptimizeFill) {
3037 tty->print_cr("filling array but bounds don't match");
3038 alloc->dump();
3039 head->init_trip()->dump();
3040 head->limit()->dump();
3041 length->dump();
3042 }
3043 #endif
3044 }
3045 }
3046 */
3047
3048 // Redirect the old control and memory edges that are outside the loop.
3049 Node* exit = head->loopexit()->proj_out(0);
3050 // Sometimes the memory phi of the head is used as the outgoing
3051 // state of the loop. It's safe in this case to replace it with the
3052 // result_mem.
3053 _igvn.replace_node(store->in(MemNode::Memory), result_mem);
3054 _igvn.replace_node(exit, result_ctrl);
3055 _igvn.replace_node(store, result_mem);
3056 // Any uses the increment outside of the loop become the loop limit.
3057 _igvn.replace_node(head->incr(), head->limit());
3058
3059 // Disconnect the head from the loop.
3060 for (uint i = 0; i < lpt->_body.size(); i++) {
3061 Node* n = lpt->_body.at(i);
3062 _igvn.replace_node(n, C->top());
3063 }
3064
3065 return true;
3066 }