1 /*
2 * Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "compiler/compileLog.hpp"
27 #include "memory/allocation.inline.hpp"
28 #include "opto/addnode.hpp"
29 #include "opto/callnode.hpp"
30 #include "opto/castnode.hpp"
31 #include "opto/connode.hpp"
32 #include "opto/convertnode.hpp"
33 #include "opto/divnode.hpp"
34 #include "opto/loopnode.hpp"
35 #include "opto/mulnode.hpp"
36 #include "opto/movenode.hpp"
37 #include "opto/opaquenode.hpp"
38 #include "opto/rootnode.hpp"
39 #include "opto/runtime.hpp"
40 #include "opto/subnode.hpp"
41 #include "opto/superword.hpp"
42 #include "opto/vectornode.hpp"
43
44 //------------------------------is_loop_exit-----------------------------------
45 // Given an IfNode, return the loop-exiting projection or NULL if both
46 // arms remain in the loop.
47 Node *IdealLoopTree::is_loop_exit(Node *iff) const {
48 if( iff->outcnt() != 2 ) return NULL; // Ignore partially dead tests
49 PhaseIdealLoop *phase = _phase;
50 // Test is an IfNode, has 2 projections. If BOTH are in the loop
51 // we need loop unswitching instead of peeling.
52 if( !is_member(phase->get_loop( iff->raw_out(0) )) )
53 return iff->raw_out(0);
54 if( !is_member(phase->get_loop( iff->raw_out(1) )) )
55 return iff->raw_out(1);
56 return NULL;
57 }
58
59
60 //=============================================================================
61
62
63 //------------------------------record_for_igvn----------------------------
64 // Put loop body on igvn work list
65 void IdealLoopTree::record_for_igvn() {
66 for( uint i = 0; i < _body.size(); i++ ) {
67 Node *n = _body.at(i);
68 _phase->_igvn._worklist.push(n);
69 }
70 }
71
72 //------------------------------compute_exact_trip_count-----------------------
73 // Compute loop exact trip count if possible. Do not recalculate trip count for
74 // split loops (pre-main-post) which have their limits and inits behind Opaque node.
75 void IdealLoopTree::compute_exact_trip_count( PhaseIdealLoop *phase ) {
76 if (!_head->as_Loop()->is_valid_counted_loop()) {
77 return;
78 }
79 CountedLoopNode* cl = _head->as_CountedLoop();
80 // Trip count may become nonexact for iteration split loops since
81 // RCE modifies limits. Note, _trip_count value is not reset since
82 // it is used to limit unrolling of main loop.
83 cl->set_nonexact_trip_count();
84
85 // Loop's test should be part of loop.
86 if (!phase->is_member(this, phase->get_ctrl(cl->loopexit()->in(CountedLoopEndNode::TestValue))))
87 return; // Infinite loop
88
89 #ifdef ASSERT
90 BoolTest::mask bt = cl->loopexit()->test_trip();
91 assert(bt == BoolTest::lt || bt == BoolTest::gt ||
92 bt == BoolTest::ne, "canonical test is expected");
93 #endif
94
95 Node* init_n = cl->init_trip();
96 Node* limit_n = cl->limit();
97 if (init_n != NULL && init_n->is_Con() &&
98 limit_n != NULL && limit_n->is_Con()) {
99 // Use longs to avoid integer overflow.
100 int stride_con = cl->stride_con();
101 jlong init_con = cl->init_trip()->get_int();
102 jlong limit_con = cl->limit()->get_int();
103 int stride_m = stride_con - (stride_con > 0 ? 1 : -1);
104 jlong trip_count = (limit_con - init_con + stride_m)/stride_con;
105 if (trip_count > 0 && (julong)trip_count < (julong)max_juint) {
106 // Set exact trip count.
107 cl->set_exact_trip_count((uint)trip_count);
108 }
109 }
110 }
111
112 //------------------------------compute_profile_trip_cnt----------------------------
113 // Compute loop trip count from profile data as
114 // (backedge_count + loop_exit_count) / loop_exit_count
115 void IdealLoopTree::compute_profile_trip_cnt( PhaseIdealLoop *phase ) {
116 if (!_head->is_CountedLoop()) {
117 return;
118 }
119 CountedLoopNode* head = _head->as_CountedLoop();
120 if (head->profile_trip_cnt() != COUNT_UNKNOWN) {
121 return; // Already computed
122 }
123 float trip_cnt = (float)max_jint; // default is big
124
125 Node* back = head->in(LoopNode::LoopBackControl);
126 while (back != head) {
127 if ((back->Opcode() == Op_IfTrue || back->Opcode() == Op_IfFalse) &&
128 back->in(0) &&
129 back->in(0)->is_If() &&
130 back->in(0)->as_If()->_fcnt != COUNT_UNKNOWN &&
131 back->in(0)->as_If()->_prob != PROB_UNKNOWN) {
132 break;
133 }
134 back = phase->idom(back);
135 }
136 if (back != head) {
137 assert((back->Opcode() == Op_IfTrue || back->Opcode() == Op_IfFalse) &&
138 back->in(0), "if-projection exists");
139 IfNode* back_if = back->in(0)->as_If();
140 float loop_back_cnt = back_if->_fcnt * back_if->_prob;
141
142 // Now compute a loop exit count
143 float loop_exit_cnt = 0.0f;
144 for( uint i = 0; i < _body.size(); i++ ) {
145 Node *n = _body[i];
146 if( n->is_If() ) {
147 IfNode *iff = n->as_If();
148 if( iff->_fcnt != COUNT_UNKNOWN && iff->_prob != PROB_UNKNOWN ) {
149 Node *exit = is_loop_exit(iff);
150 if( exit ) {
151 float exit_prob = iff->_prob;
152 if (exit->Opcode() == Op_IfFalse) exit_prob = 1.0 - exit_prob;
153 if (exit_prob > PROB_MIN) {
154 float exit_cnt = iff->_fcnt * exit_prob;
155 loop_exit_cnt += exit_cnt;
156 }
157 }
158 }
159 }
160 }
161 if (loop_exit_cnt > 0.0f) {
162 trip_cnt = (loop_back_cnt + loop_exit_cnt) / loop_exit_cnt;
163 } else {
164 // No exit count so use
165 trip_cnt = loop_back_cnt;
166 }
167 }
168 #ifndef PRODUCT
169 if (TraceProfileTripCount) {
170 tty->print_cr("compute_profile_trip_cnt lp: %d cnt: %f\n", head->_idx, trip_cnt);
171 }
172 #endif
173 head->set_profile_trip_cnt(trip_cnt);
174 }
175
176 //---------------------is_invariant_addition-----------------------------
177 // Return nonzero index of invariant operand for an Add or Sub
178 // of (nonconstant) invariant and variant values. Helper for reassociate_invariants.
179 int IdealLoopTree::is_invariant_addition(Node* n, PhaseIdealLoop *phase) {
180 int op = n->Opcode();
181 if (op == Op_AddI || op == Op_SubI) {
182 bool in1_invar = this->is_invariant(n->in(1));
183 bool in2_invar = this->is_invariant(n->in(2));
184 if (in1_invar && !in2_invar) return 1;
185 if (!in1_invar && in2_invar) return 2;
186 }
187 return 0;
188 }
189
190 //---------------------reassociate_add_sub-----------------------------
191 // Reassociate invariant add and subtract expressions:
192 //
193 // inv1 + (x + inv2) => ( inv1 + inv2) + x
194 // (x + inv2) + inv1 => ( inv1 + inv2) + x
195 // inv1 + (x - inv2) => ( inv1 - inv2) + x
196 // inv1 - (inv2 - x) => ( inv1 - inv2) + x
197 // (x + inv2) - inv1 => (-inv1 + inv2) + x
198 // (x - inv2) + inv1 => ( inv1 - inv2) + x
199 // (x - inv2) - inv1 => (-inv1 - inv2) + x
200 // inv1 + (inv2 - x) => ( inv1 + inv2) - x
201 // inv1 - (x - inv2) => ( inv1 + inv2) - x
202 // (inv2 - x) + inv1 => ( inv1 + inv2) - x
203 // (inv2 - x) - inv1 => (-inv1 + inv2) - x
204 // inv1 - (x + inv2) => ( inv1 - inv2) - x
205 //
206 Node* IdealLoopTree::reassociate_add_sub(Node* n1, PhaseIdealLoop *phase) {
207 if (!n1->is_Add() && !n1->is_Sub() || n1->outcnt() == 0) return NULL;
208 if (is_invariant(n1)) return NULL;
209 int inv1_idx = is_invariant_addition(n1, phase);
210 if (!inv1_idx) return NULL;
211 // Don't mess with add of constant (igvn moves them to expression tree root.)
212 if (n1->is_Add() && n1->in(2)->is_Con()) return NULL;
213 Node* inv1 = n1->in(inv1_idx);
214 Node* n2 = n1->in(3 - inv1_idx);
215 int inv2_idx = is_invariant_addition(n2, phase);
216 if (!inv2_idx) return NULL;
217 Node* x = n2->in(3 - inv2_idx);
218 Node* inv2 = n2->in(inv2_idx);
219
220 bool neg_x = n2->is_Sub() && inv2_idx == 1;
221 bool neg_inv2 = n2->is_Sub() && inv2_idx == 2;
222 bool neg_inv1 = n1->is_Sub() && inv1_idx == 2;
223 if (n1->is_Sub() && inv1_idx == 1) {
224 neg_x = !neg_x;
225 neg_inv2 = !neg_inv2;
226 }
227 Node* inv1_c = phase->get_ctrl(inv1);
228 Node* inv2_c = phase->get_ctrl(inv2);
229 Node* n_inv1;
230 if (neg_inv1) {
231 Node *zero = phase->_igvn.intcon(0);
232 phase->set_ctrl(zero, phase->C->root());
233 n_inv1 = new SubINode(zero, inv1);
234 phase->register_new_node(n_inv1, inv1_c);
235 } else {
236 n_inv1 = inv1;
237 }
238 Node* inv;
239 if (neg_inv2) {
240 inv = new SubINode(n_inv1, inv2);
241 } else {
242 inv = new AddINode(n_inv1, inv2);
243 }
244 phase->register_new_node(inv, phase->get_early_ctrl(inv));
245
246 Node* addx;
247 if (neg_x) {
248 addx = new SubINode(inv, x);
249 } else {
250 addx = new AddINode(x, inv);
251 }
252 phase->register_new_node(addx, phase->get_ctrl(x));
253 phase->_igvn.replace_node(n1, addx);
254 assert(phase->get_loop(phase->get_ctrl(n1)) == this, "");
255 _body.yank(n1);
256 return addx;
257 }
258
259 //---------------------reassociate_invariants-----------------------------
260 // Reassociate invariant expressions:
261 void IdealLoopTree::reassociate_invariants(PhaseIdealLoop *phase) {
262 for (int i = _body.size() - 1; i >= 0; i--) {
263 Node *n = _body.at(i);
264 for (int j = 0; j < 5; j++) {
265 Node* nn = reassociate_add_sub(n, phase);
266 if (nn == NULL) break;
267 n = nn; // again
268 };
269 }
270 }
271
272 //------------------------------policy_peeling---------------------------------
273 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can
274 // make some loop-invariant test (usually a null-check) happen before the loop.
275 bool IdealLoopTree::policy_peeling( PhaseIdealLoop *phase ) const {
276 Node *test = ((IdealLoopTree*)this)->tail();
277 int body_size = ((IdealLoopTree*)this)->_body.size();
278 // Peeling does loop cloning which can result in O(N^2) node construction
279 if( body_size > 255 /* Prevent overflow for large body_size */
280 || (body_size * body_size + phase->C->live_nodes()) > phase->C->max_node_limit() ) {
281 return false; // too large to safely clone
282 }
283 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 // Check for initial stride being a small enough constant
662 if (abs(cl->stride_con()) > (1<<2)*future_unroll_ct) return false;
663
664 // Don't unroll if the next round of unrolling would push us
665 // over the expected trip count of the loop. One is subtracted
666 // from the expected trip count because the pre-loop normally
667 // executes 1 iteration.
668 if (UnrollLimitForProfileCheck > 0 &&
669 cl->profile_trip_cnt() != COUNT_UNKNOWN &&
670 future_unroll_ct > UnrollLimitForProfileCheck &&
671 (float)future_unroll_ct > cl->profile_trip_cnt() - 1.0) {
672 return false;
673 }
674
675 // When unroll count is greater than LoopUnrollMin, don't unroll if:
676 // the residual iterations are more than 10% of the trip count
677 // and rounds of "unroll,optimize" are not making significant progress
678 // Progress defined as current size less than 20% larger than previous size.
679 if (UseSuperWord && cl->node_count_before_unroll() > 0 &&
680 future_unroll_ct > LoopUnrollMin &&
681 (future_unroll_ct - 1) * 10.0 > cl->profile_trip_cnt() &&
682 1.2 * cl->node_count_before_unroll() < (double)_body.size()) {
683 return false;
684 }
685
686 Node *init_n = cl->init_trip();
687 Node *limit_n = cl->limit();
688 int stride_con = cl->stride_con();
689 // Non-constant bounds.
690 // Protect against over-unrolling when init or/and limit are not constant
691 // (so that trip_count's init value is maxint) but iv range is known.
692 if (init_n == NULL || !init_n->is_Con() ||
693 limit_n == NULL || !limit_n->is_Con()) {
694 Node* phi = cl->phi();
695 if (phi != NULL) {
696 assert(phi->is_Phi() && phi->in(0) == _head, "Counted loop should have iv phi.");
697 const TypeInt* iv_type = phase->_igvn.type(phi)->is_int();
698 int next_stride = stride_con * 2; // stride after this unroll
699 if (next_stride > 0) {
700 if (iv_type->_lo + next_stride <= iv_type->_lo || // overflow
701 iv_type->_lo + next_stride > iv_type->_hi) {
702 return false; // over-unrolling
703 }
704 } else if (next_stride < 0) {
705 if (iv_type->_hi + next_stride >= iv_type->_hi || // overflow
706 iv_type->_hi + next_stride < iv_type->_lo) {
707 return false; // over-unrolling
708 }
709 }
710 }
711 }
712
713 // After unroll limit will be adjusted: new_limit = limit-stride.
714 // Bailout if adjustment overflow.
715 const TypeInt* limit_type = phase->_igvn.type(limit_n)->is_int();
716 if (stride_con > 0 && ((limit_type->_hi - stride_con) >= limit_type->_hi) ||
717 stride_con < 0 && ((limit_type->_lo - stride_con) <= limit_type->_lo))
718 return false; // overflow
719
720 // Adjust body_size to determine if we unroll or not
721 uint body_size = _body.size();
722 // Key test to unroll loop in CRC32 java code
723 int xors_in_loop = 0;
724 // Also count ModL, DivL and MulL which expand mightly
725 for (uint k = 0; k < _body.size(); k++) {
726 Node* n = _body.at(k);
727 switch (n->Opcode()) {
728 case Op_XorI: xors_in_loop++; break; // CRC32 java code
729 case Op_ModL: body_size += 30; break;
730 case Op_DivL: body_size += 30; break;
731 case Op_MulL: body_size += 10; break;
732 case Op_StrComp:
733 case Op_StrEquals:
734 case Op_StrIndexOf:
735 case Op_EncodeISOArray:
736 case Op_AryEq: {
737 // Do not unroll a loop with String intrinsics code.
738 // String intrinsics are large and have loops.
739 return false;
740 }
741 #if INCLUDE_RTM_OPT
742 case Op_FastLock:
743 case Op_FastUnlock: {
744 // Don't unroll RTM locking code because it is large.
745 if (UseRTMLocking) {
746 return false;
747 }
748 }
749 #endif
750 } // switch
751 }
752
753 if (UseSuperWord) {
754 if (!cl->is_reduction_loop()) {
755 phase->mark_reductions(this);
756 }
757
758 // Only attempt slp analysis when user controls do not prohibit it
759 if (LoopMaxUnroll > _local_loop_unroll_factor) {
760 // Once policy_slp_analysis succeeds, mark the loop with the
761 // maximal unroll factor so that we minimize analysis passes
762 if (future_unroll_ct > _local_loop_unroll_factor) {
763 policy_unroll_slp_analysis(cl, phase, future_unroll_ct);
764 }
765 }
766 }
767
768 // Check for being too big
769 if (body_size > (uint)_local_loop_unroll_limit) {
770 if (xors_in_loop >= 4 && body_size < (uint)LoopUnrollLimit*4) return true;
771 // Normal case: loop too big
772 return false;
773 }
774
775 // Unroll once! (Each trip will soon do double iterations)
776 return true;
777 }
778
779 void IdealLoopTree::policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_ct) {
780 // Enable this functionality target by target as needed
781 if (SuperWordLoopUnrollAnalysis) {
782 if (!cl->has_passed_slp()) {
783 SuperWord sw(phase);
784 sw.transform_loop(this, false);
785
786 // If the loop is slp canonical analyze it
787 if (sw.early_return() == false) {
788 sw.unrolling_analysis(cl, _local_loop_unroll_factor);
789 }
790 }
791
792 int slp_max_unroll_factor = cl->slp_max_unroll();
793 if ((slp_max_unroll_factor > 4) &&
794 (slp_max_unroll_factor >= future_unroll_ct)) {
795 int new_limit = cl->node_count_before_unroll() * slp_max_unroll_factor;
796 if (new_limit > LoopUnrollLimit) {
797 #ifndef PRODUCT
798 if (TraceSuperWordLoopUnrollAnalysis) {
799 tty->print_cr("slp analysis is applying unroll limit %d, the original limit was %d\n",
800 new_limit, _local_loop_unroll_limit);
801 }
802 #endif
803 _local_loop_unroll_limit = new_limit;
804 }
805 }
806 }
807 }
808
809 //------------------------------policy_align-----------------------------------
810 // Return TRUE or FALSE if the loop should be cache-line aligned. Gather the
811 // expression that does the alignment. Note that only one array base can be
812 // aligned in a loop (unless the VM guarantees mutual alignment). Note that
813 // if we vectorize short memory ops into longer memory ops, we may want to
814 // increase alignment.
815 bool IdealLoopTree::policy_align( PhaseIdealLoop *phase ) const {
816 return false;
817 }
818
819 //------------------------------policy_range_check-----------------------------
820 // Return TRUE or FALSE if the loop should be range-check-eliminated.
821 // Actually we do iteration-splitting, a more powerful form of RCE.
822 bool IdealLoopTree::policy_range_check( PhaseIdealLoop *phase ) const {
823 if (!RangeCheckElimination) return false;
824
825 CountedLoopNode *cl = _head->as_CountedLoop();
826 // If we unrolled with no intention of doing RCE and we later
827 // changed our minds, we got no pre-loop. Either we need to
828 // make a new pre-loop, or we gotta disallow RCE.
829 if (cl->is_main_no_pre_loop()) return false; // Disallowed for now.
830 Node *trip_counter = cl->phi();
831
832 // Check loop body for tests of trip-counter plus loop-invariant vs
833 // loop-invariant.
834 for (uint i = 0; i < _body.size(); i++) {
835 Node *iff = _body[i];
836 if (iff->Opcode() == Op_If) { // Test?
837
838 // Comparing trip+off vs limit
839 Node *bol = iff->in(1);
840 if (bol->req() != 2) continue; // dead constant test
841 if (!bol->is_Bool()) {
842 assert(UseLoopPredicate && bol->Opcode() == Op_Conv2B, "predicate check only");
843 continue;
844 }
845 if (bol->as_Bool()->_test._test == BoolTest::ne)
846 continue; // not RC
847
848 Node *cmp = bol->in(1);
849 Node *rc_exp = cmp->in(1);
850 Node *limit = cmp->in(2);
851
852 Node *limit_c = phase->get_ctrl(limit);
853 if( limit_c == phase->C->top() )
854 return false; // Found dead test on live IF? No RCE!
855 if( is_member(phase->get_loop(limit_c) ) ) {
856 // Compare might have operands swapped; commute them
857 rc_exp = cmp->in(2);
858 limit = cmp->in(1);
859 limit_c = phase->get_ctrl(limit);
860 if( is_member(phase->get_loop(limit_c) ) )
861 continue; // Both inputs are loop varying; cannot RCE
862 }
863
864 if (!phase->is_scaled_iv_plus_offset(rc_exp, trip_counter, NULL, NULL)) {
865 continue;
866 }
867 // Yeah! Found a test like 'trip+off vs limit'
868 // Test is an IfNode, has 2 projections. If BOTH are in the loop
869 // we need loop unswitching instead of iteration splitting.
870 if( is_loop_exit(iff) )
871 return true; // Found reason to split iterations
872 } // End of is IF
873 }
874
875 return false;
876 }
877
878 //------------------------------policy_peel_only-------------------------------
879 // Return TRUE or FALSE if the loop should NEVER be RCE'd or aligned. Useful
880 // for unrolling loops with NO array accesses.
881 bool IdealLoopTree::policy_peel_only( PhaseIdealLoop *phase ) const {
882
883 for( uint i = 0; i < _body.size(); i++ )
884 if( _body[i]->is_Mem() )
885 return false;
886
887 // No memory accesses at all!
888 return true;
889 }
890
891 //------------------------------clone_up_backedge_goo--------------------------
892 // If Node n lives in the back_ctrl block and cannot float, we clone a private
893 // version of n in preheader_ctrl block and return that, otherwise return n.
894 Node *PhaseIdealLoop::clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones ) {
895 if( get_ctrl(n) != back_ctrl ) return n;
896
897 // Only visit once
898 if (visited.test_set(n->_idx)) {
899 Node *x = clones.find(n->_idx);
900 if (x != NULL)
901 return x;
902 return n;
903 }
904
905 Node *x = NULL; // If required, a clone of 'n'
906 // Check for 'n' being pinned in the backedge.
907 if( n->in(0) && n->in(0) == back_ctrl ) {
908 assert(clones.find(n->_idx) == NULL, "dead loop");
909 x = n->clone(); // Clone a copy of 'n' to preheader
910 clones.push(x, n->_idx);
911 x->set_req( 0, preheader_ctrl ); // Fix x's control input to preheader
912 }
913
914 // Recursive fixup any other input edges into x.
915 // If there are no changes we can just return 'n', otherwise
916 // we need to clone a private copy and change it.
917 for( uint i = 1; i < n->req(); i++ ) {
918 Node *g = clone_up_backedge_goo( back_ctrl, preheader_ctrl, n->in(i), visited, clones );
919 if( g != n->in(i) ) {
920 if( !x ) {
921 assert(clones.find(n->_idx) == NULL, "dead loop");
922 x = n->clone();
923 clones.push(x, n->_idx);
924 }
925 x->set_req(i, g);
926 }
927 }
928 if( x ) { // x can legally float to pre-header location
929 register_new_node( x, preheader_ctrl );
930 return x;
931 } else { // raise n to cover LCA of uses
932 set_ctrl( n, find_non_split_ctrl(back_ctrl->in(0)) );
933 }
934 return n;
935 }
936
937 bool PhaseIdealLoop::cast_incr_before_loop(Node* incr, Node* ctrl, Node* loop) {
938 Node* castii = new CastIINode(incr, TypeInt::INT, true);
939 castii->set_req(0, ctrl);
940 register_new_node(castii, ctrl);
941 for (DUIterator_Fast imax, i = incr->fast_outs(imax); i < imax; i++) {
942 Node* n = incr->fast_out(i);
943 if (n->is_Phi() && n->in(0) == loop) {
944 int nrep = n->replace_edge(incr, castii);
945 return true;
946 }
947 }
948 return false;
949 }
950
951 //------------------------------insert_pre_post_loops--------------------------
952 // Insert pre and post loops. If peel_only is set, the pre-loop can not have
953 // more iterations added. It acts as a 'peel' only, no lower-bound RCE, no
954 // alignment. Useful to unroll loops that do no array accesses.
955 void PhaseIdealLoop::insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only ) {
956
957 #ifndef PRODUCT
958 if (TraceLoopOpts) {
959 if (peel_only)
960 tty->print("PeelMainPost ");
961 else
962 tty->print("PreMainPost ");
963 loop->dump_head();
964 }
965 #endif
966 C->set_major_progress();
967
968 // Find common pieces of the loop being guarded with pre & post loops
969 CountedLoopNode *main_head = loop->_head->as_CountedLoop();
970 assert( main_head->is_normal_loop(), "" );
971 CountedLoopEndNode *main_end = main_head->loopexit();
972 guarantee(main_end != NULL, "no loop exit node");
973 assert( main_end->outcnt() == 2, "1 true, 1 false path only" );
974 uint dd_main_head = dom_depth(main_head);
975 uint max = main_head->outcnt();
976
977 Node *pre_header= main_head->in(LoopNode::EntryControl);
978 Node *init = main_head->init_trip();
979 Node *incr = main_end ->incr();
980 Node *limit = main_end ->limit();
981 Node *stride = main_end ->stride();
982 Node *cmp = main_end ->cmp_node();
983 BoolTest::mask b_test = main_end->test_trip();
984
985 // Need only 1 user of 'bol' because I will be hacking the loop bounds.
986 Node *bol = main_end->in(CountedLoopEndNode::TestValue);
987 if( bol->outcnt() != 1 ) {
988 bol = bol->clone();
989 register_new_node(bol,main_end->in(CountedLoopEndNode::TestControl));
990 _igvn.replace_input_of(main_end, CountedLoopEndNode::TestValue, bol);
991 }
992 // Need only 1 user of 'cmp' because I will be hacking the loop bounds.
993 if( cmp->outcnt() != 1 ) {
994 cmp = cmp->clone();
995 register_new_node(cmp,main_end->in(CountedLoopEndNode::TestControl));
996 _igvn.replace_input_of(bol, 1, cmp);
997 }
998
999 //------------------------------
1000 // Step A: Create Post-Loop.
1001 Node* main_exit = main_end->proj_out(false);
1002 assert( main_exit->Opcode() == Op_IfFalse, "" );
1003 int dd_main_exit = dom_depth(main_exit);
1004
1005 // Step A1: Clone the loop body. The clone becomes the post-loop. The main
1006 // loop pre-header illegally has 2 control users (old & new loops).
1007 clone_loop( loop, old_new, dd_main_exit );
1008 assert( old_new[main_end ->_idx]->Opcode() == Op_CountedLoopEnd, "" );
1009 CountedLoopNode *post_head = old_new[main_head->_idx]->as_CountedLoop();
1010 post_head->set_post_loop(main_head);
1011
1012 // Reduce the post-loop trip count.
1013 CountedLoopEndNode* post_end = old_new[main_end ->_idx]->as_CountedLoopEnd();
1014 post_end->_prob = PROB_FAIR;
1015
1016 // Build the main-loop normal exit.
1017 IfFalseNode *new_main_exit = new IfFalseNode(main_end);
1018 _igvn.register_new_node_with_optimizer( new_main_exit );
1019 set_idom(new_main_exit, main_end, dd_main_exit );
1020 set_loop(new_main_exit, loop->_parent);
1021
1022 // Step A2: Build a zero-trip guard for the post-loop. After leaving the
1023 // main-loop, the post-loop may not execute at all. We 'opaque' the incr
1024 // (the main-loop trip-counter exit value) because we will be changing
1025 // the exit value (via unrolling) so we cannot constant-fold away the zero
1026 // trip guard until all unrolling is done.
1027 Node *zer_opaq = new Opaque1Node(C, incr);
1028 Node *zer_cmp = new CmpINode( zer_opaq, limit );
1029 Node *zer_bol = new BoolNode( zer_cmp, b_test );
1030 register_new_node( zer_opaq, new_main_exit );
1031 register_new_node( zer_cmp , new_main_exit );
1032 register_new_node( zer_bol , new_main_exit );
1033
1034 // Build the IfNode
1035 IfNode *zer_iff = new IfNode( new_main_exit, zer_bol, PROB_FAIR, COUNT_UNKNOWN );
1036 _igvn.register_new_node_with_optimizer( zer_iff );
1037 set_idom(zer_iff, new_main_exit, dd_main_exit);
1038 set_loop(zer_iff, loop->_parent);
1039
1040 // Plug in the false-path, taken if we need to skip post-loop
1041 _igvn.replace_input_of(main_exit, 0, zer_iff);
1042 set_idom(main_exit, zer_iff, dd_main_exit);
1043 set_idom(main_exit->unique_out(), zer_iff, dd_main_exit);
1044 // Make the true-path, must enter the post loop
1045 Node *zer_taken = new IfTrueNode( zer_iff );
1046 _igvn.register_new_node_with_optimizer( zer_taken );
1047 set_idom(zer_taken, zer_iff, dd_main_exit);
1048 set_loop(zer_taken, loop->_parent);
1049 // Plug in the true path
1050 _igvn.hash_delete( post_head );
1051 post_head->set_req(LoopNode::EntryControl, zer_taken);
1052 set_idom(post_head, zer_taken, dd_main_exit);
1053
1054 Arena *a = Thread::current()->resource_area();
1055 VectorSet visited(a);
1056 Node_Stack clones(a, main_head->back_control()->outcnt());
1057 // Step A3: Make the fall-in values to the post-loop come from the
1058 // fall-out values of the main-loop.
1059 for (DUIterator_Fast imax, i = main_head->fast_outs(imax); i < imax; i++) {
1060 Node* main_phi = main_head->fast_out(i);
1061 if( main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() >0 ) {
1062 Node *post_phi = old_new[main_phi->_idx];
1063 Node *fallmain = clone_up_backedge_goo(main_head->back_control(),
1064 post_head->init_control(),
1065 main_phi->in(LoopNode::LoopBackControl),
1066 visited, clones);
1067 _igvn.hash_delete(post_phi);
1068 post_phi->set_req( LoopNode::EntryControl, fallmain );
1069 }
1070 }
1071
1072 // Update local caches for next stanza
1073 main_exit = new_main_exit;
1074
1075
1076 //------------------------------
1077 // Step B: Create Pre-Loop.
1078
1079 // Step B1: Clone the loop body. The clone becomes the pre-loop. The main
1080 // loop pre-header illegally has 2 control users (old & new loops).
1081 clone_loop( loop, old_new, dd_main_head );
1082 CountedLoopNode* pre_head = old_new[main_head->_idx]->as_CountedLoop();
1083 CountedLoopEndNode* pre_end = old_new[main_end ->_idx]->as_CountedLoopEnd();
1084 pre_head->set_pre_loop(main_head);
1085 Node *pre_incr = old_new[incr->_idx];
1086
1087 // Reduce the pre-loop trip count.
1088 pre_end->_prob = PROB_FAIR;
1089
1090 // Find the pre-loop normal exit.
1091 Node* pre_exit = pre_end->proj_out(false);
1092 assert( pre_exit->Opcode() == Op_IfFalse, "" );
1093 IfFalseNode *new_pre_exit = new IfFalseNode(pre_end);
1094 _igvn.register_new_node_with_optimizer( new_pre_exit );
1095 set_idom(new_pre_exit, pre_end, dd_main_head);
1096 set_loop(new_pre_exit, loop->_parent);
1097
1098 // Step B2: Build a zero-trip guard for the main-loop. After leaving the
1099 // pre-loop, the main-loop may not execute at all. Later in life this
1100 // zero-trip guard will become the minimum-trip guard when we unroll
1101 // the main-loop.
1102 Node *min_opaq = new Opaque1Node(C, limit);
1103 Node *min_cmp = new CmpINode( pre_incr, min_opaq );
1104 Node *min_bol = new BoolNode( min_cmp, b_test );
1105 register_new_node( min_opaq, new_pre_exit );
1106 register_new_node( min_cmp , new_pre_exit );
1107 register_new_node( min_bol , new_pre_exit );
1108
1109 // Build the IfNode (assume the main-loop is executed always).
1110 IfNode *min_iff = new IfNode( new_pre_exit, min_bol, PROB_ALWAYS, COUNT_UNKNOWN );
1111 _igvn.register_new_node_with_optimizer( min_iff );
1112 set_idom(min_iff, new_pre_exit, dd_main_head);
1113 set_loop(min_iff, loop->_parent);
1114
1115 // Plug in the false-path, taken if we need to skip main-loop
1116 _igvn.hash_delete( pre_exit );
1117 pre_exit->set_req(0, min_iff);
1118 set_idom(pre_exit, min_iff, dd_main_head);
1119 set_idom(pre_exit->unique_out(), min_iff, dd_main_head);
1120 // Make the true-path, must enter the main loop
1121 Node *min_taken = new IfTrueNode( min_iff );
1122 _igvn.register_new_node_with_optimizer( min_taken );
1123 set_idom(min_taken, min_iff, dd_main_head);
1124 set_loop(min_taken, loop->_parent);
1125 // Plug in the true path
1126 _igvn.hash_delete( main_head );
1127 main_head->set_req(LoopNode::EntryControl, min_taken);
1128 set_idom(main_head, min_taken, dd_main_head);
1129
1130 visited.Clear();
1131 clones.clear();
1132 // Step B3: Make the fall-in values to the main-loop come from the
1133 // fall-out values of the pre-loop.
1134 for (DUIterator_Fast i2max, i2 = main_head->fast_outs(i2max); i2 < i2max; i2++) {
1135 Node* main_phi = main_head->fast_out(i2);
1136 if( main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() > 0 ) {
1137 Node *pre_phi = old_new[main_phi->_idx];
1138 Node *fallpre = clone_up_backedge_goo(pre_head->back_control(),
1139 main_head->init_control(),
1140 pre_phi->in(LoopNode::LoopBackControl),
1141 visited, clones);
1142 _igvn.hash_delete(main_phi);
1143 main_phi->set_req( LoopNode::EntryControl, fallpre );
1144 }
1145 }
1146
1147 // Nodes inside the loop may be control dependent on a predicate
1148 // that was moved before the preloop. If the back branch of the main
1149 // or post loops becomes dead, those nodes won't be dependent on the
1150 // test that guards that loop nest anymore which could lead to an
1151 // incorrect array access because it executes independently of the
1152 // test that was guarding the loop nest. We add a special CastII on
1153 // the if branch that enters the loop, between the input induction
1154 // variable value and the induction variable Phi to preserve correct
1155 // dependencies.
1156
1157 // CastII for the post loop:
1158 bool inserted = cast_incr_before_loop(zer_opaq->in(1), zer_taken, post_head);
1159 assert(inserted, "no castII inserted");
1160
1161 // CastII for the main loop:
1162 inserted = cast_incr_before_loop(pre_incr, min_taken, main_head);
1163 assert(inserted, "no castII inserted");
1164
1165 // Step B4: Shorten the pre-loop to run only 1 iteration (for now).
1166 // RCE and alignment may change this later.
1167 Node *cmp_end = pre_end->cmp_node();
1168 assert( cmp_end->in(2) == limit, "" );
1169 Node *pre_limit = new AddINode( init, stride );
1170
1171 // Save the original loop limit in this Opaque1 node for
1172 // use by range check elimination.
1173 Node *pre_opaq = new Opaque1Node(C, pre_limit, limit);
1174
1175 register_new_node( pre_limit, pre_head->in(0) );
1176 register_new_node( pre_opaq , pre_head->in(0) );
1177
1178 // Since no other users of pre-loop compare, I can hack limit directly
1179 assert( cmp_end->outcnt() == 1, "no other users" );
1180 _igvn.hash_delete(cmp_end);
1181 cmp_end->set_req(2, peel_only ? pre_limit : pre_opaq);
1182
1183 // Special case for not-equal loop bounds:
1184 // Change pre loop test, main loop test, and the
1185 // main loop guard test to use lt or gt depending on stride
1186 // direction:
1187 // positive stride use <
1188 // negative stride use >
1189 //
1190 // not-equal test is kept for post loop to handle case
1191 // when init > limit when stride > 0 (and reverse).
1192
1193 if (pre_end->in(CountedLoopEndNode::TestValue)->as_Bool()->_test._test == BoolTest::ne) {
1194
1195 BoolTest::mask new_test = (main_end->stride_con() > 0) ? BoolTest::lt : BoolTest::gt;
1196 // Modify pre loop end condition
1197 Node* pre_bol = pre_end->in(CountedLoopEndNode::TestValue)->as_Bool();
1198 BoolNode* new_bol0 = new BoolNode(pre_bol->in(1), new_test);
1199 register_new_node( new_bol0, pre_head->in(0) );
1200 _igvn.replace_input_of(pre_end, CountedLoopEndNode::TestValue, new_bol0);
1201 // Modify main loop guard condition
1202 assert(min_iff->in(CountedLoopEndNode::TestValue) == min_bol, "guard okay");
1203 BoolNode* new_bol1 = new BoolNode(min_bol->in(1), new_test);
1204 register_new_node( new_bol1, new_pre_exit );
1205 _igvn.hash_delete(min_iff);
1206 min_iff->set_req(CountedLoopEndNode::TestValue, new_bol1);
1207 // Modify main loop end condition
1208 BoolNode* main_bol = main_end->in(CountedLoopEndNode::TestValue)->as_Bool();
1209 BoolNode* new_bol2 = new BoolNode(main_bol->in(1), new_test);
1210 register_new_node( new_bol2, main_end->in(CountedLoopEndNode::TestControl) );
1211 _igvn.replace_input_of(main_end, CountedLoopEndNode::TestValue, new_bol2);
1212 }
1213
1214 // Flag main loop
1215 main_head->set_main_loop();
1216 if( peel_only ) main_head->set_main_no_pre_loop();
1217
1218 // Subtract a trip count for the pre-loop.
1219 main_head->set_trip_count(main_head->trip_count() - 1);
1220
1221 // It's difficult to be precise about the trip-counts
1222 // for the pre/post loops. They are usually very short,
1223 // so guess that 4 trips is a reasonable value.
1224 post_head->set_profile_trip_cnt(4.0);
1225 pre_head->set_profile_trip_cnt(4.0);
1226
1227 // Now force out all loop-invariant dominating tests. The optimizer
1228 // finds some, but we _know_ they are all useless.
1229 peeled_dom_test_elim(loop,old_new);
1230 loop->record_for_igvn();
1231 }
1232
1233 //------------------------------is_invariant-----------------------------
1234 // Return true if n is invariant
1235 bool IdealLoopTree::is_invariant(Node* n) const {
1236 Node *n_c = _phase->has_ctrl(n) ? _phase->get_ctrl(n) : n;
1237 if (n_c->is_top()) return false;
1238 return !is_member(_phase->get_loop(n_c));
1239 }
1240
1241
1242 //------------------------------do_unroll--------------------------------------
1243 // Unroll the loop body one step - make each trip do 2 iterations.
1244 void PhaseIdealLoop::do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip ) {
1245 assert(LoopUnrollLimit, "");
1246 CountedLoopNode *loop_head = loop->_head->as_CountedLoop();
1247 CountedLoopEndNode *loop_end = loop_head->loopexit();
1248 assert(loop_end, "");
1249 #ifndef PRODUCT
1250 if (PrintOpto && VerifyLoopOptimizations) {
1251 tty->print("Unrolling ");
1252 loop->dump_head();
1253 } else if (TraceLoopOpts) {
1254 if (loop_head->trip_count() < (uint)LoopUnrollLimit) {
1255 tty->print("Unroll %d(%2d) ", loop_head->unrolled_count()*2, loop_head->trip_count());
1256 } else {
1257 tty->print("Unroll %d ", loop_head->unrolled_count()*2);
1258 }
1259 loop->dump_head();
1260 }
1261
1262 if (C->do_vector_loop() && (PrintOpto && VerifyLoopOptimizations || TraceLoopOpts)) {
1263 Arena* arena = Thread::current()->resource_area();
1264 Node_Stack stack(arena, C->unique() >> 2);
1265 Node_List rpo_list;
1266 VectorSet visited(arena);
1267 visited.set(loop_head->_idx);
1268 rpo( loop_head, stack, visited, rpo_list );
1269 dump(loop, rpo_list.size(), rpo_list );
1270 }
1271 #endif
1272
1273 // Remember loop node count before unrolling to detect
1274 // if rounds of unroll,optimize are making progress
1275 loop_head->set_node_count_before_unroll(loop->_body.size());
1276
1277 Node *ctrl = loop_head->in(LoopNode::EntryControl);
1278 Node *limit = loop_head->limit();
1279 Node *init = loop_head->init_trip();
1280 Node *stride = loop_head->stride();
1281
1282 Node *opaq = NULL;
1283 if (adjust_min_trip) { // If not maximally unrolling, need adjustment
1284 // Search for zero-trip guard.
1285 assert( loop_head->is_main_loop(), "" );
1286 assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" );
1287 Node *iff = ctrl->in(0);
1288 assert( iff->Opcode() == Op_If, "" );
1289 Node *bol = iff->in(1);
1290 assert( bol->Opcode() == Op_Bool, "" );
1291 Node *cmp = bol->in(1);
1292 assert( cmp->Opcode() == Op_CmpI, "" );
1293 opaq = cmp->in(2);
1294 // Occasionally it's possible for a zero-trip guard Opaque1 node to be
1295 // optimized away and then another round of loop opts attempted.
1296 // We can not optimize this particular loop in that case.
1297 if (opaq->Opcode() != Op_Opaque1)
1298 return; // Cannot find zero-trip guard! Bail out!
1299 // Zero-trip test uses an 'opaque' node which is not shared.
1300 assert(opaq->outcnt() == 1 && opaq->in(1) == limit, "");
1301 }
1302
1303 C->set_major_progress();
1304
1305 Node* new_limit = NULL;
1306 if (UnrollLimitCheck) {
1307 int stride_con = stride->get_int();
1308 int stride_p = (stride_con > 0) ? stride_con : -stride_con;
1309 uint old_trip_count = loop_head->trip_count();
1310 // Verify that unroll policy result is still valid.
1311 assert(old_trip_count > 1 &&
1312 (!adjust_min_trip || stride_p <= (1<<3)*loop_head->unrolled_count()), "sanity");
1313
1314 // Adjust loop limit to keep valid iterations number after unroll.
1315 // Use (limit - stride) instead of (((limit - init)/stride) & (-2))*stride
1316 // which may overflow.
1317 if (!adjust_min_trip) {
1318 assert(old_trip_count > 1 && (old_trip_count & 1) == 0,
1319 "odd trip count for maximally unroll");
1320 // Don't need to adjust limit for maximally unroll since trip count is even.
1321 } else if (loop_head->has_exact_trip_count() && init->is_Con()) {
1322 // Loop's limit is constant. Loop's init could be constant when pre-loop
1323 // become peeled iteration.
1324 jlong init_con = init->get_int();
1325 // We can keep old loop limit if iterations count stays the same:
1326 // old_trip_count == new_trip_count * 2
1327 // Note: since old_trip_count >= 2 then new_trip_count >= 1
1328 // so we also don't need to adjust zero trip test.
1329 jlong limit_con = limit->get_int();
1330 // (stride_con*2) not overflow since stride_con <= 8.
1331 int new_stride_con = stride_con * 2;
1332 int stride_m = new_stride_con - (stride_con > 0 ? 1 : -1);
1333 jlong trip_count = (limit_con - init_con + stride_m)/new_stride_con;
1334 // New trip count should satisfy next conditions.
1335 assert(trip_count > 0 && (julong)trip_count < (julong)max_juint/2, "sanity");
1336 uint new_trip_count = (uint)trip_count;
1337 adjust_min_trip = (old_trip_count != new_trip_count*2);
1338 }
1339
1340 if (adjust_min_trip) {
1341 // Step 2: Adjust the trip limit if it is called for.
1342 // The adjustment amount is -stride. Need to make sure if the
1343 // adjustment underflows or overflows, then the main loop is skipped.
1344 Node* cmp = loop_end->cmp_node();
1345 assert(cmp->in(2) == limit, "sanity");
1346 assert(opaq != NULL && opaq->in(1) == limit, "sanity");
1347
1348 // Verify that policy_unroll result is still valid.
1349 const TypeInt* limit_type = _igvn.type(limit)->is_int();
1350 assert(stride_con > 0 && ((limit_type->_hi - stride_con) < limit_type->_hi) ||
1351 stride_con < 0 && ((limit_type->_lo - stride_con) > limit_type->_lo), "sanity");
1352
1353 if (limit->is_Con()) {
1354 // The check in policy_unroll and the assert above guarantee
1355 // no underflow if limit is constant.
1356 new_limit = _igvn.intcon(limit->get_int() - stride_con);
1357 set_ctrl(new_limit, C->root());
1358 } else {
1359 // Limit is not constant.
1360 if (loop_head->unrolled_count() == 1) { // only for first unroll
1361 // Separate limit by Opaque node in case it is an incremented
1362 // variable from previous loop to avoid using pre-incremented
1363 // value which could increase register pressure.
1364 // Otherwise reorg_offsets() optimization will create a separate
1365 // Opaque node for each use of trip-counter and as result
1366 // zero trip guard limit will be different from loop limit.
1367 assert(has_ctrl(opaq), "should have it");
1368 Node* opaq_ctrl = get_ctrl(opaq);
1369 limit = new Opaque2Node( C, limit );
1370 register_new_node( limit, opaq_ctrl );
1371 }
1372 if (stride_con > 0 && ((limit_type->_lo - stride_con) < limit_type->_lo) ||
1373 stride_con < 0 && ((limit_type->_hi - stride_con) > limit_type->_hi)) {
1374 // No underflow.
1375 new_limit = new SubINode(limit, stride);
1376 } else {
1377 // (limit - stride) may underflow.
1378 // Clamp the adjustment value with MININT or MAXINT:
1379 //
1380 // new_limit = limit-stride
1381 // if (stride > 0)
1382 // new_limit = (limit < new_limit) ? MININT : new_limit;
1383 // else
1384 // new_limit = (limit > new_limit) ? MAXINT : new_limit;
1385 //
1386 BoolTest::mask bt = loop_end->test_trip();
1387 assert(bt == BoolTest::lt || bt == BoolTest::gt, "canonical test is expected");
1388 Node* adj_max = _igvn.intcon((stride_con > 0) ? min_jint : max_jint);
1389 set_ctrl(adj_max, C->root());
1390 Node* old_limit = NULL;
1391 Node* adj_limit = NULL;
1392 Node* bol = limit->is_CMove() ? limit->in(CMoveNode::Condition) : NULL;
1393 if (loop_head->unrolled_count() > 1 &&
1394 limit->is_CMove() && limit->Opcode() == Op_CMoveI &&
1395 limit->in(CMoveNode::IfTrue) == adj_max &&
1396 bol->as_Bool()->_test._test == bt &&
1397 bol->in(1)->Opcode() == Op_CmpI &&
1398 bol->in(1)->in(2) == limit->in(CMoveNode::IfFalse)) {
1399 // Loop was unrolled before.
1400 // Optimize the limit to avoid nested CMove:
1401 // use original limit as old limit.
1402 old_limit = bol->in(1)->in(1);
1403 // Adjust previous adjusted limit.
1404 adj_limit = limit->in(CMoveNode::IfFalse);
1405 adj_limit = new SubINode(adj_limit, stride);
1406 } else {
1407 old_limit = limit;
1408 adj_limit = new SubINode(limit, stride);
1409 }
1410 assert(old_limit != NULL && adj_limit != NULL, "");
1411 register_new_node( adj_limit, ctrl ); // adjust amount
1412 Node* adj_cmp = new CmpINode(old_limit, adj_limit);
1413 register_new_node( adj_cmp, ctrl );
1414 Node* adj_bool = new BoolNode(adj_cmp, bt);
1415 register_new_node( adj_bool, ctrl );
1416 new_limit = new CMoveINode(adj_bool, adj_limit, adj_max, TypeInt::INT);
1417 }
1418 register_new_node(new_limit, ctrl);
1419 }
1420 assert(new_limit != NULL, "");
1421 // Replace in loop test.
1422 assert(loop_end->in(1)->in(1) == cmp, "sanity");
1423 if (cmp->outcnt() == 1 && loop_end->in(1)->outcnt() == 1) {
1424 // Don't need to create new test since only one user.
1425 _igvn.hash_delete(cmp);
1426 cmp->set_req(2, new_limit);
1427 } else {
1428 // Create new test since it is shared.
1429 Node* ctrl2 = loop_end->in(0);
1430 Node* cmp2 = cmp->clone();
1431 cmp2->set_req(2, new_limit);
1432 register_new_node(cmp2, ctrl2);
1433 Node* bol2 = loop_end->in(1)->clone();
1434 bol2->set_req(1, cmp2);
1435 register_new_node(bol2, ctrl2);
1436 _igvn.replace_input_of(loop_end, 1, bol2);
1437 }
1438 // Step 3: Find the min-trip test guaranteed before a 'main' loop.
1439 // Make it a 1-trip test (means at least 2 trips).
1440
1441 // Guard test uses an 'opaque' node which is not shared. Hence I
1442 // can edit it's inputs directly. Hammer in the new limit for the
1443 // minimum-trip guard.
1444 assert(opaq->outcnt() == 1, "");
1445 _igvn.replace_input_of(opaq, 1, new_limit);
1446 }
1447
1448 // Adjust max trip count. The trip count is intentionally rounded
1449 // down here (e.g. 15-> 7-> 3-> 1) because if we unwittingly over-unroll,
1450 // the main, unrolled, part of the loop will never execute as it is protected
1451 // by the min-trip test. See bug 4834191 for a case where we over-unrolled
1452 // and later determined that part of the unrolled loop was dead.
1453 loop_head->set_trip_count(old_trip_count / 2);
1454
1455 // Double the count of original iterations in the unrolled loop body.
1456 loop_head->double_unrolled_count();
1457
1458 } else { // LoopLimitCheck
1459
1460 // Adjust max trip count. The trip count is intentionally rounded
1461 // down here (e.g. 15-> 7-> 3-> 1) because if we unwittingly over-unroll,
1462 // the main, unrolled, part of the loop will never execute as it is protected
1463 // by the min-trip test. See bug 4834191 for a case where we over-unrolled
1464 // and later determined that part of the unrolled loop was dead.
1465 loop_head->set_trip_count(loop_head->trip_count() / 2);
1466
1467 // Double the count of original iterations in the unrolled loop body.
1468 loop_head->double_unrolled_count();
1469
1470 // -----------
1471 // Step 2: Cut back the trip counter for an unroll amount of 2.
1472 // Loop will normally trip (limit - init)/stride_con. Since it's a
1473 // CountedLoop this is exact (stride divides limit-init exactly).
1474 // We are going to double the loop body, so we want to knock off any
1475 // odd iteration: (trip_cnt & ~1). Then back compute a new limit.
1476 Node *span = new SubINode( limit, init );
1477 register_new_node( span, ctrl );
1478 Node *trip = new DivINode( 0, span, stride );
1479 register_new_node( trip, ctrl );
1480 Node *mtwo = _igvn.intcon(-2);
1481 set_ctrl(mtwo, C->root());
1482 Node *rond = new AndINode( trip, mtwo );
1483 register_new_node( rond, ctrl );
1484 Node *spn2 = new MulINode( rond, stride );
1485 register_new_node( spn2, ctrl );
1486 new_limit = new AddINode( spn2, init );
1487 register_new_node( new_limit, ctrl );
1488
1489 // Hammer in the new limit
1490 Node *ctrl2 = loop_end->in(0);
1491 Node *cmp2 = new CmpINode( loop_head->incr(), new_limit );
1492 register_new_node( cmp2, ctrl2 );
1493 Node *bol2 = new BoolNode( cmp2, loop_end->test_trip() );
1494 register_new_node( bol2, ctrl2 );
1495 _igvn.replace_input_of(loop_end, CountedLoopEndNode::TestValue, bol2);
1496
1497 // Step 3: Find the min-trip test guaranteed before a 'main' loop.
1498 // Make it a 1-trip test (means at least 2 trips).
1499 if( adjust_min_trip ) {
1500 assert( new_limit != NULL, "" );
1501 // Guard test uses an 'opaque' node which is not shared. Hence I
1502 // can edit it's inputs directly. Hammer in the new limit for the
1503 // minimum-trip guard.
1504 assert( opaq->outcnt() == 1, "" );
1505 _igvn.hash_delete(opaq);
1506 opaq->set_req(1, new_limit);
1507 }
1508 } // LoopLimitCheck
1509
1510 // ---------
1511 // Step 4: Clone the loop body. Move it inside the loop. This loop body
1512 // represents the odd iterations; since the loop trips an even number of
1513 // times its backedge is never taken. Kill the backedge.
1514 uint dd = dom_depth(loop_head);
1515 clone_loop( loop, old_new, dd );
1516
1517 // Make backedges of the clone equal to backedges of the original.
1518 // Make the fall-in from the original come from the fall-out of the clone.
1519 for (DUIterator_Fast jmax, j = loop_head->fast_outs(jmax); j < jmax; j++) {
1520 Node* phi = loop_head->fast_out(j);
1521 if( phi->is_Phi() && phi->in(0) == loop_head && phi->outcnt() > 0 ) {
1522 Node *newphi = old_new[phi->_idx];
1523 _igvn.hash_delete( phi );
1524 _igvn.hash_delete( newphi );
1525
1526 phi ->set_req(LoopNode:: EntryControl, newphi->in(LoopNode::LoopBackControl));
1527 newphi->set_req(LoopNode::LoopBackControl, phi ->in(LoopNode::LoopBackControl));
1528 phi ->set_req(LoopNode::LoopBackControl, C->top());
1529 }
1530 }
1531 Node *clone_head = old_new[loop_head->_idx];
1532 _igvn.hash_delete( clone_head );
1533 loop_head ->set_req(LoopNode:: EntryControl, clone_head->in(LoopNode::LoopBackControl));
1534 clone_head->set_req(LoopNode::LoopBackControl, loop_head ->in(LoopNode::LoopBackControl));
1535 loop_head ->set_req(LoopNode::LoopBackControl, C->top());
1536 loop->_head = clone_head; // New loop header
1537
1538 set_idom(loop_head, loop_head ->in(LoopNode::EntryControl), dd);
1539 set_idom(clone_head, clone_head->in(LoopNode::EntryControl), dd);
1540
1541 // Kill the clone's backedge
1542 Node *newcle = old_new[loop_end->_idx];
1543 _igvn.hash_delete( newcle );
1544 Node *one = _igvn.intcon(1);
1545 set_ctrl(one, C->root());
1546 newcle->set_req(1, one);
1547 // Force clone into same loop body
1548 uint max = loop->_body.size();
1549 for( uint k = 0; k < max; k++ ) {
1550 Node *old = loop->_body.at(k);
1551 Node *nnn = old_new[old->_idx];
1552 loop->_body.push(nnn);
1553 if (!has_ctrl(old))
1554 set_loop(nnn, loop);
1555 }
1556
1557 loop->record_for_igvn();
1558
1559 #ifndef PRODUCT
1560 if (C->do_vector_loop() && (PrintOpto && VerifyLoopOptimizations || TraceLoopOpts)) {
1561 tty->print("\nnew loop after unroll\n"); loop->dump_head();
1562 for (uint i = 0; i < loop->_body.size(); i++) {
1563 loop->_body.at(i)->dump();
1564 }
1565 if(C->clone_map().is_debug()) {
1566 tty->print("\nCloneMap\n");
1567 Dict* dict = C->clone_map().dict();
1568 DictI i(dict);
1569 tty->print_cr("Dict@%p[%d] = ", dict, dict->Size());
1570 for (int ii = 0; i.test(); ++i, ++ii) {
1571 NodeCloneInfo cl((uint64_t)dict->operator[]((void*)i._key));
1572 tty->print("%d->%d:%d,", (int)(intptr_t)i._key, cl.idx(), cl.gen());
1573 if (ii % 10 == 9) {
1574 tty->print_cr(" ");
1575 }
1576 }
1577 tty->print_cr(" ");
1578 }
1579 }
1580 #endif
1581
1582 }
1583
1584 //------------------------------do_maximally_unroll----------------------------
1585
1586 void PhaseIdealLoop::do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new ) {
1587 CountedLoopNode *cl = loop->_head->as_CountedLoop();
1588 assert(cl->has_exact_trip_count(), "trip count is not exact");
1589 assert(cl->trip_count() > 0, "");
1590 #ifndef PRODUCT
1591 if (TraceLoopOpts) {
1592 tty->print("MaxUnroll %d ", cl->trip_count());
1593 loop->dump_head();
1594 }
1595 #endif
1596
1597 // If loop is tripping an odd number of times, peel odd iteration
1598 if ((cl->trip_count() & 1) == 1) {
1599 do_peeling(loop, old_new);
1600 }
1601
1602 // Now its tripping an even number of times remaining. Double loop body.
1603 // Do not adjust pre-guards; they are not needed and do not exist.
1604 if (cl->trip_count() > 0) {
1605 assert((cl->trip_count() & 1) == 0, "missed peeling");
1606 do_unroll(loop, old_new, false);
1607 }
1608 }
1609
1610 void PhaseIdealLoop::mark_reductions(IdealLoopTree *loop) {
1611 if (SuperWordReductions == false) return;
1612
1613 CountedLoopNode* loop_head = loop->_head->as_CountedLoop();
1614 if (loop_head->unrolled_count() > 1) {
1615 return;
1616 }
1617
1618 Node* trip_phi = loop_head->phi();
1619 for (DUIterator_Fast imax, i = loop_head->fast_outs(imax); i < imax; i++) {
1620 Node* phi = loop_head->fast_out(i);
1621 if (phi->is_Phi() && phi->outcnt() > 0 && phi != trip_phi) {
1622 // For definitions which are loop inclusive and not tripcounts.
1623 Node* def_node = phi->in(LoopNode::LoopBackControl);
1624
1625 if (def_node != NULL) {
1626 Node* n_ctrl = get_ctrl(def_node);
1627 if (n_ctrl != NULL && loop->is_member(get_loop(n_ctrl))) {
1628 // Now test it to see if it fits the standard pattern for a reduction operator.
1629 int opc = def_node->Opcode();
1630 if (opc != ReductionNode::opcode(opc, def_node->bottom_type()->basic_type())) {
1631 if (!def_node->is_reduction()) { // Not marked yet
1632 // To be a reduction, the arithmetic node must have the phi as input and provide a def to it
1633 for (unsigned j = 1; j < def_node->req(); j++) {
1634 Node* in = def_node->in(j);
1635 if (in == phi) {
1636 loop_head->mark_has_reductions();
1637 def_node->add_flag(Node::Flag_is_reduction);
1638 break;
1639 }
1640 }
1641 }
1642 }
1643 }
1644 }
1645 }
1646 }
1647 }
1648
1649 //------------------------------dominates_backedge---------------------------------
1650 // Returns true if ctrl is executed on every complete iteration
1651 bool IdealLoopTree::dominates_backedge(Node* ctrl) {
1652 assert(ctrl->is_CFG(), "must be control");
1653 Node* backedge = _head->as_Loop()->in(LoopNode::LoopBackControl);
1654 return _phase->dom_lca_internal(ctrl, backedge) == ctrl;
1655 }
1656
1657 //------------------------------adjust_limit-----------------------------------
1658 // Helper function for add_constraint().
1659 Node* PhaseIdealLoop::adjust_limit(int stride_con, Node * scale, Node *offset, Node *rc_limit, Node *loop_limit, Node *pre_ctrl) {
1660 // Compute "I :: (limit-offset)/scale"
1661 Node *con = new SubINode(rc_limit, offset);
1662 register_new_node(con, pre_ctrl);
1663 Node *X = new DivINode(0, con, scale);
1664 register_new_node(X, pre_ctrl);
1665
1666 // Adjust loop limit
1667 loop_limit = (stride_con > 0)
1668 ? (Node*)(new MinINode(loop_limit, X))
1669 : (Node*)(new MaxINode(loop_limit, X));
1670 register_new_node(loop_limit, pre_ctrl);
1671 return loop_limit;
1672 }
1673
1674 //------------------------------add_constraint---------------------------------
1675 // Constrain the main loop iterations so the conditions:
1676 // low_limit <= scale_con * I + offset < upper_limit
1677 // always holds true. That is, either increase the number of iterations in
1678 // the pre-loop or the post-loop until the condition holds true in the main
1679 // loop. Stride, scale, offset and limit are all loop invariant. Further,
1680 // stride and scale are constants (offset and limit often are).
1681 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 ) {
1682 // For positive stride, the pre-loop limit always uses a MAX function
1683 // and the main loop a MIN function. For negative stride these are
1684 // reversed.
1685
1686 // Also for positive stride*scale the affine function is increasing, so the
1687 // pre-loop must check for underflow and the post-loop for overflow.
1688 // Negative stride*scale reverses this; pre-loop checks for overflow and
1689 // post-loop for underflow.
1690
1691 Node *scale = _igvn.intcon(scale_con);
1692 set_ctrl(scale, C->root());
1693
1694 if ((stride_con^scale_con) >= 0) { // Use XOR to avoid overflow
1695 // The overflow limit: scale*I+offset < upper_limit
1696 // For main-loop compute
1697 // ( if (scale > 0) /* and stride > 0 */
1698 // I < (upper_limit-offset)/scale
1699 // else /* scale < 0 and stride < 0 */
1700 // I > (upper_limit-offset)/scale
1701 // )
1702 //
1703 // (upper_limit-offset) may overflow or underflow.
1704 // But it is fine since main loop will either have
1705 // less iterations or will be skipped in such case.
1706 *main_limit = adjust_limit(stride_con, scale, offset, upper_limit, *main_limit, pre_ctrl);
1707
1708 // The underflow limit: low_limit <= scale*I+offset.
1709 // For pre-loop compute
1710 // NOT(scale*I+offset >= low_limit)
1711 // scale*I+offset < low_limit
1712 // ( if (scale > 0) /* and stride > 0 */
1713 // I < (low_limit-offset)/scale
1714 // else /* scale < 0 and stride < 0 */
1715 // I > (low_limit-offset)/scale
1716 // )
1717
1718 if (low_limit->get_int() == -max_jint) {
1719 if (!RangeLimitCheck) return;
1720 // We need this guard when scale*pre_limit+offset >= limit
1721 // due to underflow. So we need execute pre-loop until
1722 // scale*I+offset >= min_int. But (min_int-offset) will
1723 // underflow when offset > 0 and X will be > original_limit
1724 // when stride > 0. To avoid it we replace positive offset with 0.
1725 //
1726 // Also (min_int+1 == -max_int) is used instead of min_int here
1727 // to avoid problem with scale == -1 (min_int/(-1) == min_int).
1728 Node* shift = _igvn.intcon(31);
1729 set_ctrl(shift, C->root());
1730 Node* sign = new RShiftINode(offset, shift);
1731 register_new_node(sign, pre_ctrl);
1732 offset = new AndINode(offset, sign);
1733 register_new_node(offset, pre_ctrl);
1734 } else {
1735 assert(low_limit->get_int() == 0, "wrong low limit for range check");
1736 // The only problem we have here when offset == min_int
1737 // since (0-min_int) == min_int. It may be fine for stride > 0
1738 // but for stride < 0 X will be < original_limit. To avoid it
1739 // max(pre_limit, original_limit) is used in do_range_check().
1740 }
1741 // Pass (-stride) to indicate pre_loop_cond = NOT(main_loop_cond);
1742 *pre_limit = adjust_limit((-stride_con), scale, offset, low_limit, *pre_limit, pre_ctrl);
1743
1744 } else { // stride_con*scale_con < 0
1745 // For negative stride*scale pre-loop checks for overflow and
1746 // post-loop for underflow.
1747 //
1748 // The overflow limit: scale*I+offset < upper_limit
1749 // For pre-loop compute
1750 // NOT(scale*I+offset < upper_limit)
1751 // scale*I+offset >= upper_limit
1752 // scale*I+offset+1 > upper_limit
1753 // ( if (scale < 0) /* and stride > 0 */
1754 // I < (upper_limit-(offset+1))/scale
1755 // else /* scale > 0 and stride < 0 */
1756 // I > (upper_limit-(offset+1))/scale
1757 // )
1758 //
1759 // (upper_limit-offset-1) may underflow or overflow.
1760 // To avoid it min(pre_limit, original_limit) is used
1761 // in do_range_check() for stride > 0 and max() for < 0.
1762 Node *one = _igvn.intcon(1);
1763 set_ctrl(one, C->root());
1764
1765 Node *plus_one = new AddINode(offset, one);
1766 register_new_node( plus_one, pre_ctrl );
1767 // Pass (-stride) to indicate pre_loop_cond = NOT(main_loop_cond);
1768 *pre_limit = adjust_limit((-stride_con), scale, plus_one, upper_limit, *pre_limit, pre_ctrl);
1769
1770 if (low_limit->get_int() == -max_jint) {
1771 if (!RangeLimitCheck) return;
1772 // We need this guard when scale*main_limit+offset >= limit
1773 // due to underflow. So we need execute main-loop while
1774 // scale*I+offset+1 > min_int. But (min_int-offset-1) will
1775 // underflow when (offset+1) > 0 and X will be < main_limit
1776 // when scale < 0 (and stride > 0). To avoid it we replace
1777 // positive (offset+1) with 0.
1778 //
1779 // Also (min_int+1 == -max_int) is used instead of min_int here
1780 // to avoid problem with scale == -1 (min_int/(-1) == min_int).
1781 Node* shift = _igvn.intcon(31);
1782 set_ctrl(shift, C->root());
1783 Node* sign = new RShiftINode(plus_one, shift);
1784 register_new_node(sign, pre_ctrl);
1785 plus_one = new AndINode(plus_one, sign);
1786 register_new_node(plus_one, pre_ctrl);
1787 } else {
1788 assert(low_limit->get_int() == 0, "wrong low limit for range check");
1789 // The only problem we have here when offset == max_int
1790 // since (max_int+1) == min_int and (0-min_int) == min_int.
1791 // But it is fine since main loop will either have
1792 // less iterations or will be skipped in such case.
1793 }
1794 // The underflow limit: low_limit <= scale*I+offset.
1795 // For main-loop compute
1796 // scale*I+offset+1 > low_limit
1797 // ( if (scale < 0) /* and stride > 0 */
1798 // I < (low_limit-(offset+1))/scale
1799 // else /* scale > 0 and stride < 0 */
1800 // I > (low_limit-(offset+1))/scale
1801 // )
1802
1803 *main_limit = adjust_limit(stride_con, scale, plus_one, low_limit, *main_limit, pre_ctrl);
1804 }
1805 }
1806
1807
1808 //------------------------------is_scaled_iv---------------------------------
1809 // Return true if exp is a constant times an induction var
1810 bool PhaseIdealLoop::is_scaled_iv(Node* exp, Node* iv, int* p_scale) {
1811 if (exp == iv) {
1812 if (p_scale != NULL) {
1813 *p_scale = 1;
1814 }
1815 return true;
1816 }
1817 int opc = exp->Opcode();
1818 if (opc == Op_MulI) {
1819 if (exp->in(1) == iv && exp->in(2)->is_Con()) {
1820 if (p_scale != NULL) {
1821 *p_scale = exp->in(2)->get_int();
1822 }
1823 return true;
1824 }
1825 if (exp->in(2) == iv && exp->in(1)->is_Con()) {
1826 if (p_scale != NULL) {
1827 *p_scale = exp->in(1)->get_int();
1828 }
1829 return true;
1830 }
1831 } else if (opc == Op_LShiftI) {
1832 if (exp->in(1) == iv && exp->in(2)->is_Con()) {
1833 if (p_scale != NULL) {
1834 *p_scale = 1 << exp->in(2)->get_int();
1835 }
1836 return true;
1837 }
1838 }
1839 return false;
1840 }
1841
1842 //-----------------------------is_scaled_iv_plus_offset------------------------------
1843 // Return true if exp is a simple induction variable expression: k1*iv + (invar + k2)
1844 bool PhaseIdealLoop::is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth) {
1845 if (is_scaled_iv(exp, iv, p_scale)) {
1846 if (p_offset != NULL) {
1847 Node *zero = _igvn.intcon(0);
1848 set_ctrl(zero, C->root());
1849 *p_offset = zero;
1850 }
1851 return true;
1852 }
1853 int opc = exp->Opcode();
1854 if (opc == Op_AddI) {
1855 if (is_scaled_iv(exp->in(1), iv, p_scale)) {
1856 if (p_offset != NULL) {
1857 *p_offset = exp->in(2);
1858 }
1859 return true;
1860 }
1861 if (exp->in(2)->is_Con()) {
1862 Node* offset2 = NULL;
1863 if (depth < 2 &&
1864 is_scaled_iv_plus_offset(exp->in(1), iv, p_scale,
1865 p_offset != NULL ? &offset2 : NULL, depth+1)) {
1866 if (p_offset != NULL) {
1867 Node *ctrl_off2 = get_ctrl(offset2);
1868 Node* offset = new AddINode(offset2, exp->in(2));
1869 register_new_node(offset, ctrl_off2);
1870 *p_offset = offset;
1871 }
1872 return true;
1873 }
1874 }
1875 } else if (opc == Op_SubI) {
1876 if (is_scaled_iv(exp->in(1), iv, p_scale)) {
1877 if (p_offset != NULL) {
1878 Node *zero = _igvn.intcon(0);
1879 set_ctrl(zero, C->root());
1880 Node *ctrl_off = get_ctrl(exp->in(2));
1881 Node* offset = new SubINode(zero, exp->in(2));
1882 register_new_node(offset, ctrl_off);
1883 *p_offset = offset;
1884 }
1885 return true;
1886 }
1887 if (is_scaled_iv(exp->in(2), iv, p_scale)) {
1888 if (p_offset != NULL) {
1889 *p_scale *= -1;
1890 *p_offset = exp->in(1);
1891 }
1892 return true;
1893 }
1894 }
1895 return false;
1896 }
1897
1898 //------------------------------do_range_check---------------------------------
1899 // Eliminate range-checks and other trip-counter vs loop-invariant tests.
1900 void PhaseIdealLoop::do_range_check( IdealLoopTree *loop, Node_List &old_new ) {
1901 #ifndef PRODUCT
1902 if (PrintOpto && VerifyLoopOptimizations) {
1903 tty->print("Range Check Elimination ");
1904 loop->dump_head();
1905 } else if (TraceLoopOpts) {
1906 tty->print("RangeCheck ");
1907 loop->dump_head();
1908 }
1909 #endif
1910 assert(RangeCheckElimination, "");
1911 CountedLoopNode *cl = loop->_head->as_CountedLoop();
1912 assert(cl->is_main_loop(), "");
1913
1914 // protect against stride not being a constant
1915 if (!cl->stride_is_con())
1916 return;
1917
1918 // Find the trip counter; we are iteration splitting based on it
1919 Node *trip_counter = cl->phi();
1920 // Find the main loop limit; we will trim it's iterations
1921 // to not ever trip end tests
1922 Node *main_limit = cl->limit();
1923
1924 // Need to find the main-loop zero-trip guard
1925 Node *ctrl = cl->in(LoopNode::EntryControl);
1926 assert(ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "");
1927 Node *iffm = ctrl->in(0);
1928 assert(iffm->Opcode() == Op_If, "");
1929 Node *bolzm = iffm->in(1);
1930 assert(bolzm->Opcode() == Op_Bool, "");
1931 Node *cmpzm = bolzm->in(1);
1932 assert(cmpzm->is_Cmp(), "");
1933 Node *opqzm = cmpzm->in(2);
1934 // Can not optimize a loop if zero-trip Opaque1 node is optimized
1935 // away and then another round of loop opts attempted.
1936 if (opqzm->Opcode() != Op_Opaque1)
1937 return;
1938 assert(opqzm->in(1) == main_limit, "do not understand situation");
1939
1940 // Find the pre-loop limit; we will expand it's iterations to
1941 // not ever trip low tests.
1942 Node *p_f = iffm->in(0);
1943 assert(p_f->Opcode() == Op_IfFalse, "");
1944 CountedLoopEndNode *pre_end = p_f->in(0)->as_CountedLoopEnd();
1945 assert(pre_end->loopnode()->is_pre_loop(), "");
1946 Node *pre_opaq1 = pre_end->limit();
1947 // Occasionally it's possible for a pre-loop Opaque1 node to be
1948 // optimized away and then another round of loop opts attempted.
1949 // We can not optimize this particular loop in that case.
1950 if (pre_opaq1->Opcode() != Op_Opaque1)
1951 return;
1952 Opaque1Node *pre_opaq = (Opaque1Node*)pre_opaq1;
1953 Node *pre_limit = pre_opaq->in(1);
1954
1955 // Where do we put new limit calculations
1956 Node *pre_ctrl = pre_end->loopnode()->in(LoopNode::EntryControl);
1957
1958 // Ensure the original loop limit is available from the
1959 // pre-loop Opaque1 node.
1960 Node *orig_limit = pre_opaq->original_loop_limit();
1961 if (orig_limit == NULL || _igvn.type(orig_limit) == Type::TOP)
1962 return;
1963
1964 // Must know if its a count-up or count-down loop
1965
1966 int stride_con = cl->stride_con();
1967 Node *zero = _igvn.intcon(0);
1968 Node *one = _igvn.intcon(1);
1969 // Use symmetrical int range [-max_jint,max_jint]
1970 Node *mini = _igvn.intcon(-max_jint);
1971 set_ctrl(zero, C->root());
1972 set_ctrl(one, C->root());
1973 set_ctrl(mini, C->root());
1974
1975 // Range checks that do not dominate the loop backedge (ie.
1976 // conditionally executed) can lengthen the pre loop limit beyond
1977 // the original loop limit. To prevent this, the pre limit is
1978 // (for stride > 0) MINed with the original loop limit (MAXed
1979 // stride < 0) when some range_check (rc) is conditionally
1980 // executed.
1981 bool conditional_rc = false;
1982
1983 // Check loop body for tests of trip-counter plus loop-invariant vs
1984 // loop-invariant.
1985 for( uint i = 0; i < loop->_body.size(); i++ ) {
1986 Node *iff = loop->_body[i];
1987 if( iff->Opcode() == Op_If ) { // Test?
1988
1989 // Test is an IfNode, has 2 projections. If BOTH are in the loop
1990 // we need loop unswitching instead of iteration splitting.
1991 Node *exit = loop->is_loop_exit(iff);
1992 if( !exit ) continue;
1993 int flip = (exit->Opcode() == Op_IfTrue) ? 1 : 0;
1994
1995 // Get boolean condition to test
1996 Node *i1 = iff->in(1);
1997 if( !i1->is_Bool() ) continue;
1998 BoolNode *bol = i1->as_Bool();
1999 BoolTest b_test = bol->_test;
2000 // Flip sense of test if exit condition is flipped
2001 if( flip )
2002 b_test = b_test.negate();
2003
2004 // Get compare
2005 Node *cmp = bol->in(1);
2006
2007 // Look for trip_counter + offset vs limit
2008 Node *rc_exp = cmp->in(1);
2009 Node *limit = cmp->in(2);
2010 jint scale_con= 1; // Assume trip counter not scaled
2011
2012 Node *limit_c = get_ctrl(limit);
2013 if( loop->is_member(get_loop(limit_c) ) ) {
2014 // Compare might have operands swapped; commute them
2015 b_test = b_test.commute();
2016 rc_exp = cmp->in(2);
2017 limit = cmp->in(1);
2018 limit_c = get_ctrl(limit);
2019 if( loop->is_member(get_loop(limit_c) ) )
2020 continue; // Both inputs are loop varying; cannot RCE
2021 }
2022 // Here we know 'limit' is loop invariant
2023
2024 // 'limit' maybe pinned below the zero trip test (probably from a
2025 // previous round of rce), in which case, it can't be used in the
2026 // zero trip test expression which must occur before the zero test's if.
2027 if( limit_c == ctrl ) {
2028 continue; // Don't rce this check but continue looking for other candidates.
2029 }
2030
2031 // Check for scaled induction variable plus an offset
2032 Node *offset = NULL;
2033
2034 if (!is_scaled_iv_plus_offset(rc_exp, trip_counter, &scale_con, &offset)) {
2035 continue;
2036 }
2037
2038 Node *offset_c = get_ctrl(offset);
2039 if( loop->is_member( get_loop(offset_c) ) )
2040 continue; // Offset is not really loop invariant
2041 // Here we know 'offset' is loop invariant.
2042
2043 // As above for the 'limit', the 'offset' maybe pinned below the
2044 // zero trip test.
2045 if( offset_c == ctrl ) {
2046 continue; // Don't rce this check but continue looking for other candidates.
2047 }
2048 #ifdef ASSERT
2049 if (TraceRangeLimitCheck) {
2050 tty->print_cr("RC bool node%s", flip ? " flipped:" : ":");
2051 bol->dump(2);
2052 }
2053 #endif
2054 // At this point we have the expression as:
2055 // scale_con * trip_counter + offset :: limit
2056 // where scale_con, offset and limit are loop invariant. Trip_counter
2057 // monotonically increases by stride_con, a constant. Both (or either)
2058 // stride_con and scale_con can be negative which will flip about the
2059 // sense of the test.
2060
2061 // Adjust pre and main loop limits to guard the correct iteration set
2062 if( cmp->Opcode() == Op_CmpU ) {// Unsigned compare is really 2 tests
2063 if( b_test._test == BoolTest::lt ) { // Range checks always use lt
2064 // The underflow and overflow limits: 0 <= scale*I+offset < limit
2065 add_constraint( stride_con, scale_con, offset, zero, limit, pre_ctrl, &pre_limit, &main_limit );
2066 if (!conditional_rc) {
2067 // (0-offset)/scale could be outside of loop iterations range.
2068 conditional_rc = !loop->dominates_backedge(iff) || RangeLimitCheck;
2069 }
2070 } else {
2071 #ifndef PRODUCT
2072 if( PrintOpto )
2073 tty->print_cr("missed RCE opportunity");
2074 #endif
2075 continue; // In release mode, ignore it
2076 }
2077 } else { // Otherwise work on normal compares
2078 switch( b_test._test ) {
2079 case BoolTest::gt:
2080 // Fall into GE case
2081 case BoolTest::ge:
2082 // Convert (I*scale+offset) >= Limit to (I*(-scale)+(-offset)) <= -Limit
2083 scale_con = -scale_con;
2084 offset = new SubINode( zero, offset );
2085 register_new_node( offset, pre_ctrl );
2086 limit = new SubINode( zero, limit );
2087 register_new_node( limit, pre_ctrl );
2088 // Fall into LE case
2089 case BoolTest::le:
2090 if (b_test._test != BoolTest::gt) {
2091 // Convert X <= Y to X < Y+1
2092 limit = new AddINode( limit, one );
2093 register_new_node( limit, pre_ctrl );
2094 }
2095 // Fall into LT case
2096 case BoolTest::lt:
2097 // The underflow and overflow limits: MIN_INT <= scale*I+offset < limit
2098 // Note: (MIN_INT+1 == -MAX_INT) is used instead of MIN_INT here
2099 // to avoid problem with scale == -1: MIN_INT/(-1) == MIN_INT.
2100 add_constraint( stride_con, scale_con, offset, mini, limit, pre_ctrl, &pre_limit, &main_limit );
2101 if (!conditional_rc) {
2102 // ((MIN_INT+1)-offset)/scale could be outside of loop iterations range.
2103 // Note: negative offset is replaced with 0 but (MIN_INT+1)/scale could
2104 // still be outside of loop range.
2105 conditional_rc = !loop->dominates_backedge(iff) || RangeLimitCheck;
2106 }
2107 break;
2108 default:
2109 #ifndef PRODUCT
2110 if( PrintOpto )
2111 tty->print_cr("missed RCE opportunity");
2112 #endif
2113 continue; // Unhandled case
2114 }
2115 }
2116
2117 // Kill the eliminated test
2118 C->set_major_progress();
2119 Node *kill_con = _igvn.intcon( 1-flip );
2120 set_ctrl(kill_con, C->root());
2121 _igvn.replace_input_of(iff, 1, kill_con);
2122 // Find surviving projection
2123 assert(iff->is_If(), "");
2124 ProjNode* dp = ((IfNode*)iff)->proj_out(1-flip);
2125 // Find loads off the surviving projection; remove their control edge
2126 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
2127 Node* cd = dp->fast_out(i); // Control-dependent node
2128 if (cd->is_Load() && cd->depends_only_on_test()) { // Loads can now float around in the loop
2129 // Allow the load to float around in the loop, or before it
2130 // but NOT before the pre-loop.
2131 _igvn.replace_input_of(cd, 0, ctrl); // ctrl, not NULL
2132 --i;
2133 --imax;
2134 }
2135 }
2136
2137 } // End of is IF
2138
2139 }
2140
2141 // Update loop limits
2142 if (conditional_rc) {
2143 pre_limit = (stride_con > 0) ? (Node*)new MinINode(pre_limit, orig_limit)
2144 : (Node*)new MaxINode(pre_limit, orig_limit);
2145 register_new_node(pre_limit, pre_ctrl);
2146 }
2147 _igvn.replace_input_of(pre_opaq, 1, pre_limit);
2148
2149 // Note:: we are making the main loop limit no longer precise;
2150 // need to round up based on stride.
2151 cl->set_nonexact_trip_count();
2152 if (!LoopLimitCheck && stride_con != 1 && stride_con != -1) { // Cutout for common case
2153 // "Standard" round-up logic: ([main_limit-init+(y-1)]/y)*y+init
2154 // Hopefully, compiler will optimize for powers of 2.
2155 Node *ctrl = get_ctrl(main_limit);
2156 Node *stride = cl->stride();
2157 Node *init = cl->init_trip()->uncast();
2158 Node *span = new SubINode(main_limit,init);
2159 register_new_node(span,ctrl);
2160 Node *rndup = _igvn.intcon(stride_con + ((stride_con>0)?-1:1));
2161 Node *add = new AddINode(span,rndup);
2162 register_new_node(add,ctrl);
2163 Node *div = new DivINode(0,add,stride);
2164 register_new_node(div,ctrl);
2165 Node *mul = new MulINode(div,stride);
2166 register_new_node(mul,ctrl);
2167 Node *newlim = new AddINode(mul,init);
2168 register_new_node(newlim,ctrl);
2169 main_limit = newlim;
2170 }
2171
2172 Node *main_cle = cl->loopexit();
2173 Node *main_bol = main_cle->in(1);
2174 // Hacking loop bounds; need private copies of exit test
2175 if( main_bol->outcnt() > 1 ) {// BoolNode shared?
2176 main_bol = main_bol->clone();// Clone a private BoolNode
2177 register_new_node( main_bol, main_cle->in(0) );
2178 _igvn.replace_input_of(main_cle, 1, main_bol);
2179 }
2180 Node *main_cmp = main_bol->in(1);
2181 if( main_cmp->outcnt() > 1 ) { // CmpNode shared?
2182 main_cmp = main_cmp->clone();// Clone a private CmpNode
2183 register_new_node( main_cmp, main_cle->in(0) );
2184 _igvn.replace_input_of(main_bol, 1, main_cmp);
2185 }
2186 // Hack the now-private loop bounds
2187 _igvn.replace_input_of(main_cmp, 2, main_limit);
2188 // The OpaqueNode is unshared by design
2189 assert( opqzm->outcnt() == 1, "cannot hack shared node" );
2190 _igvn.replace_input_of(opqzm, 1, main_limit);
2191 }
2192
2193 //------------------------------DCE_loop_body----------------------------------
2194 // Remove simplistic dead code from loop body
2195 void IdealLoopTree::DCE_loop_body() {
2196 for( uint i = 0; i < _body.size(); i++ )
2197 if( _body.at(i)->outcnt() == 0 )
2198 _body.map( i--, _body.pop() );
2199 }
2200
2201
2202 //------------------------------adjust_loop_exit_prob--------------------------
2203 // Look for loop-exit tests with the 50/50 (or worse) guesses from the parsing stage.
2204 // Replace with a 1-in-10 exit guess.
2205 void IdealLoopTree::adjust_loop_exit_prob( PhaseIdealLoop *phase ) {
2206 Node *test = tail();
2207 while( test != _head ) {
2208 uint top = test->Opcode();
2209 if( top == Op_IfTrue || top == Op_IfFalse ) {
2210 int test_con = ((ProjNode*)test)->_con;
2211 assert(top == (uint)(test_con? Op_IfTrue: Op_IfFalse), "sanity");
2212 IfNode *iff = test->in(0)->as_If();
2213 if( iff->outcnt() == 2 ) { // Ignore dead tests
2214 Node *bol = iff->in(1);
2215 if( bol && bol->req() > 1 && bol->in(1) &&
2216 ((bol->in(1)->Opcode() == Op_StorePConditional ) ||
2217 (bol->in(1)->Opcode() == Op_StoreIConditional ) ||
2218 (bol->in(1)->Opcode() == Op_StoreLConditional ) ||
2219 (bol->in(1)->Opcode() == Op_CompareAndSwapI ) ||
2220 (bol->in(1)->Opcode() == Op_CompareAndSwapL ) ||
2221 (bol->in(1)->Opcode() == Op_CompareAndSwapP ) ||
2222 (bol->in(1)->Opcode() == Op_CompareAndSwapN )))
2223 return; // Allocation loops RARELY take backedge
2224 // Find the OTHER exit path from the IF
2225 Node* ex = iff->proj_out(1-test_con);
2226 float p = iff->_prob;
2227 if( !phase->is_member( this, ex ) && iff->_fcnt == COUNT_UNKNOWN ) {
2228 if( top == Op_IfTrue ) {
2229 if( p < (PROB_FAIR + PROB_UNLIKELY_MAG(3))) {
2230 iff->_prob = PROB_STATIC_FREQUENT;
2231 }
2232 } else {
2233 if( p > (PROB_FAIR - PROB_UNLIKELY_MAG(3))) {
2234 iff->_prob = PROB_STATIC_INFREQUENT;
2235 }
2236 }
2237 }
2238 }
2239 }
2240 test = phase->idom(test);
2241 }
2242 }
2243
2244
2245 //------------------------------policy_do_remove_empty_loop--------------------
2246 // Micro-benchmark spamming. Policy is to always remove empty loops.
2247 // The 'DO' part is to replace the trip counter with the value it will
2248 // have on the last iteration. This will break the loop.
2249 bool IdealLoopTree::policy_do_remove_empty_loop( PhaseIdealLoop *phase ) {
2250 // Minimum size must be empty loop
2251 if (_body.size() > EMPTY_LOOP_SIZE)
2252 return false;
2253
2254 if (!_head->is_CountedLoop())
2255 return false; // Dead loop
2256 CountedLoopNode *cl = _head->as_CountedLoop();
2257 if (!cl->is_valid_counted_loop())
2258 return false; // Malformed loop
2259 if (!phase->is_member(this, phase->get_ctrl(cl->loopexit()->in(CountedLoopEndNode::TestValue))))
2260 return false; // Infinite loop
2261
2262 #ifdef ASSERT
2263 // Ensure only one phi which is the iv.
2264 Node* iv = NULL;
2265 for (DUIterator_Fast imax, i = cl->fast_outs(imax); i < imax; i++) {
2266 Node* n = cl->fast_out(i);
2267 if (n->Opcode() == Op_Phi) {
2268 assert(iv == NULL, "Too many phis" );
2269 iv = n;
2270 }
2271 }
2272 assert(iv == cl->phi(), "Wrong phi" );
2273 #endif
2274
2275 // main and post loops have explicitly created zero trip guard
2276 bool needs_guard = !cl->is_main_loop() && !cl->is_post_loop();
2277 if (needs_guard) {
2278 // Skip guard if values not overlap.
2279 const TypeInt* init_t = phase->_igvn.type(cl->init_trip())->is_int();
2280 const TypeInt* limit_t = phase->_igvn.type(cl->limit())->is_int();
2281 int stride_con = cl->stride_con();
2282 if (stride_con > 0) {
2283 needs_guard = (init_t->_hi >= limit_t->_lo);
2284 } else {
2285 needs_guard = (init_t->_lo <= limit_t->_hi);
2286 }
2287 }
2288 if (needs_guard) {
2289 // Check for an obvious zero trip guard.
2290 Node* inctrl = PhaseIdealLoop::skip_loop_predicates(cl->in(LoopNode::EntryControl));
2291 if (inctrl->Opcode() == Op_IfTrue) {
2292 // The test should look like just the backedge of a CountedLoop
2293 Node* iff = inctrl->in(0);
2294 if (iff->is_If()) {
2295 Node* bol = iff->in(1);
2296 if (bol->is_Bool() && bol->as_Bool()->_test._test == cl->loopexit()->test_trip()) {
2297 Node* cmp = bol->in(1);
2298 if (cmp->is_Cmp() && cmp->in(1) == cl->init_trip() && cmp->in(2) == cl->limit()) {
2299 needs_guard = false;
2300 }
2301 }
2302 }
2303 }
2304 }
2305
2306 #ifndef PRODUCT
2307 if (PrintOpto) {
2308 tty->print("Removing empty loop with%s zero trip guard", needs_guard ? "out" : "");
2309 this->dump_head();
2310 } else if (TraceLoopOpts) {
2311 tty->print("Empty with%s zero trip guard ", needs_guard ? "out" : "");
2312 this->dump_head();
2313 }
2314 #endif
2315
2316 if (needs_guard) {
2317 // Peel the loop to ensure there's a zero trip guard
2318 Node_List old_new;
2319 phase->do_peeling(this, old_new);
2320 }
2321
2322 // Replace the phi at loop head with the final value of the last
2323 // iteration. Then the CountedLoopEnd will collapse (backedge never
2324 // taken) and all loop-invariant uses of the exit values will be correct.
2325 Node *phi = cl->phi();
2326 Node *exact_limit = phase->exact_limit(this);
2327 if (exact_limit != cl->limit()) {
2328 // We also need to replace the original limit to collapse loop exit.
2329 Node* cmp = cl->loopexit()->cmp_node();
2330 assert(cl->limit() == cmp->in(2), "sanity");
2331 phase->_igvn._worklist.push(cmp->in(2)); // put limit on worklist
2332 phase->_igvn.replace_input_of(cmp, 2, exact_limit); // put cmp on worklist
2333 }
2334 // Note: the final value after increment should not overflow since
2335 // counted loop has limit check predicate.
2336 Node *final = new SubINode( exact_limit, cl->stride() );
2337 phase->register_new_node(final,cl->in(LoopNode::EntryControl));
2338 phase->_igvn.replace_node(phi,final);
2339 phase->C->set_major_progress();
2340 return true;
2341 }
2342
2343 //------------------------------policy_do_one_iteration_loop-------------------
2344 // Convert one iteration loop into normal code.
2345 bool IdealLoopTree::policy_do_one_iteration_loop( PhaseIdealLoop *phase ) {
2346 if (!_head->as_Loop()->is_valid_counted_loop())
2347 return false; // Only for counted loop
2348
2349 CountedLoopNode *cl = _head->as_CountedLoop();
2350 if (!cl->has_exact_trip_count() || cl->trip_count() != 1) {
2351 return false;
2352 }
2353
2354 #ifndef PRODUCT
2355 if(TraceLoopOpts) {
2356 tty->print("OneIteration ");
2357 this->dump_head();
2358 }
2359 #endif
2360
2361 Node *init_n = cl->init_trip();
2362 #ifdef ASSERT
2363 // Loop boundaries should be constant since trip count is exact.
2364 assert(init_n->get_int() + cl->stride_con() >= cl->limit()->get_int(), "should be one iteration");
2365 #endif
2366 // Replace the phi at loop head with the value of the init_trip.
2367 // Then the CountedLoopEnd will collapse (backedge will not be taken)
2368 // and all loop-invariant uses of the exit values will be correct.
2369 phase->_igvn.replace_node(cl->phi(), cl->init_trip());
2370 phase->C->set_major_progress();
2371 return true;
2372 }
2373
2374 //=============================================================================
2375 //------------------------------iteration_split_impl---------------------------
2376 bool IdealLoopTree::iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new ) {
2377 // Compute exact loop trip count if possible.
2378 compute_exact_trip_count(phase);
2379
2380 // Convert one iteration loop into normal code.
2381 if (policy_do_one_iteration_loop(phase))
2382 return true;
2383
2384 // Check and remove empty loops (spam micro-benchmarks)
2385 if (policy_do_remove_empty_loop(phase))
2386 return true; // Here we removed an empty loop
2387
2388 bool should_peel = policy_peeling(phase); // Should we peel?
2389
2390 bool should_unswitch = policy_unswitching(phase);
2391
2392 // Non-counted loops may be peeled; exactly 1 iteration is peeled.
2393 // This removes loop-invariant tests (usually null checks).
2394 if (!_head->is_CountedLoop()) { // Non-counted loop
2395 if (PartialPeelLoop && phase->partial_peel(this, old_new)) {
2396 // Partial peel succeeded so terminate this round of loop opts
2397 return false;
2398 }
2399 if (should_peel) { // Should we peel?
2400 #ifndef PRODUCT
2401 if (PrintOpto) tty->print_cr("should_peel");
2402 #endif
2403 phase->do_peeling(this,old_new);
2404 } else if (should_unswitch) {
2405 phase->do_unswitching(this, old_new);
2406 }
2407 return true;
2408 }
2409 CountedLoopNode *cl = _head->as_CountedLoop();
2410
2411 if (!cl->is_valid_counted_loop()) return true; // Ignore various kinds of broken loops
2412
2413 // Do nothing special to pre- and post- loops
2414 if (cl->is_pre_loop() || cl->is_post_loop()) return true;
2415
2416 // Compute loop trip count from profile data
2417 compute_profile_trip_cnt(phase);
2418
2419 // Before attempting fancy unrolling, RCE or alignment, see if we want
2420 // to completely unroll this loop or do loop unswitching.
2421 if (cl->is_normal_loop()) {
2422 if (should_unswitch) {
2423 phase->do_unswitching(this, old_new);
2424 return true;
2425 }
2426 bool should_maximally_unroll = policy_maximally_unroll(phase);
2427 if (should_maximally_unroll) {
2428 // Here we did some unrolling and peeling. Eventually we will
2429 // completely unroll this loop and it will no longer be a loop.
2430 phase->do_maximally_unroll(this,old_new);
2431 return true;
2432 }
2433 }
2434
2435 // Skip next optimizations if running low on nodes. Note that
2436 // policy_unswitching and policy_maximally_unroll have this check.
2437 int nodes_left = phase->C->max_node_limit() - phase->C->live_nodes();
2438 if ((int)(2 * _body.size()) > nodes_left) {
2439 return true;
2440 }
2441
2442 // Counted loops may be peeled, may need some iterations run up
2443 // front for RCE, and may want to align loop refs to a cache
2444 // line. Thus we clone a full loop up front whose trip count is
2445 // at least 1 (if peeling), but may be several more.
2446
2447 // The main loop will start cache-line aligned with at least 1
2448 // iteration of the unrolled body (zero-trip test required) and
2449 // will have some range checks removed.
2450
2451 // A post-loop will finish any odd iterations (leftover after
2452 // unrolling), plus any needed for RCE purposes.
2453
2454 bool should_unroll = policy_unroll(phase);
2455
2456 bool should_rce = policy_range_check(phase);
2457
2458 bool should_align = policy_align(phase);
2459
2460 // If not RCE'ing (iteration splitting) or Aligning, then we do not
2461 // need a pre-loop. We may still need to peel an initial iteration but
2462 // we will not be needing an unknown number of pre-iterations.
2463 //
2464 // Basically, if may_rce_align reports FALSE first time through,
2465 // we will not be able to later do RCE or Aligning on this loop.
2466 bool may_rce_align = !policy_peel_only(phase) || should_rce || should_align;
2467
2468 // If we have any of these conditions (RCE, alignment, unrolling) met, then
2469 // we switch to the pre-/main-/post-loop model. This model also covers
2470 // peeling.
2471 if (should_rce || should_align || should_unroll) {
2472 if (cl->is_normal_loop()) // Convert to 'pre/main/post' loops
2473 phase->insert_pre_post_loops(this,old_new, !may_rce_align);
2474
2475 // Adjust the pre- and main-loop limits to let the pre and post loops run
2476 // with full checks, but the main-loop with no checks. Remove said
2477 // checks from the main body.
2478 if (should_rce)
2479 phase->do_range_check(this,old_new);
2480
2481 // Double loop body for unrolling. Adjust the minimum-trip test (will do
2482 // twice as many iterations as before) and the main body limit (only do
2483 // an even number of trips). If we are peeling, we might enable some RCE
2484 // and we'd rather unroll the post-RCE'd loop SO... do not unroll if
2485 // peeling.
2486 if (should_unroll && !should_peel) {
2487 phase->do_unroll(this, old_new, true);
2488 }
2489
2490 // Adjust the pre-loop limits to align the main body
2491 // iterations.
2492 if (should_align)
2493 Unimplemented();
2494
2495 } else { // Else we have an unchanged counted loop
2496 if (should_peel) // Might want to peel but do nothing else
2497 phase->do_peeling(this,old_new);
2498 }
2499 return true;
2500 }
2501
2502
2503 //=============================================================================
2504 //------------------------------iteration_split--------------------------------
2505 bool IdealLoopTree::iteration_split( PhaseIdealLoop *phase, Node_List &old_new ) {
2506 // Recursively iteration split nested loops
2507 if (_child && !_child->iteration_split(phase, old_new))
2508 return false;
2509
2510 // Clean out prior deadwood
2511 DCE_loop_body();
2512
2513
2514 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage.
2515 // Replace with a 1-in-10 exit guess.
2516 if (_parent /*not the root loop*/ &&
2517 !_irreducible &&
2518 // Also ignore the occasional dead backedge
2519 !tail()->is_top()) {
2520 adjust_loop_exit_prob(phase);
2521 }
2522
2523 // Gate unrolling, RCE and peeling efforts.
2524 if (!_child && // If not an inner loop, do not split
2525 !_irreducible &&
2526 _allow_optimizations &&
2527 !tail()->is_top()) { // Also ignore the occasional dead backedge
2528 if (!_has_call) {
2529 if (!iteration_split_impl(phase, old_new)) {
2530 return false;
2531 }
2532 } else if (policy_unswitching(phase)) {
2533 phase->do_unswitching(this, old_new);
2534 }
2535 }
2536
2537 // Minor offset re-organization to remove loop-fallout uses of
2538 // trip counter when there was no major reshaping.
2539 phase->reorg_offsets(this);
2540
2541 if (_next && !_next->iteration_split(phase, old_new))
2542 return false;
2543 return true;
2544 }
2545
2546
2547 //=============================================================================
2548 // Process all the loops in the loop tree and replace any fill
2549 // patterns with an intrisc version.
2550 bool PhaseIdealLoop::do_intrinsify_fill() {
2551 bool changed = false;
2552 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
2553 IdealLoopTree* lpt = iter.current();
2554 changed |= intrinsify_fill(lpt);
2555 }
2556 return changed;
2557 }
2558
2559
2560 // Examine an inner loop looking for a a single store of an invariant
2561 // value in a unit stride loop,
2562 bool PhaseIdealLoop::match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value,
2563 Node*& shift, Node*& con) {
2564 const char* msg = NULL;
2565 Node* msg_node = NULL;
2566
2567 store_value = NULL;
2568 con = NULL;
2569 shift = NULL;
2570
2571 // Process the loop looking for stores. If there are multiple
2572 // stores or extra control flow give at this point.
2573 CountedLoopNode* head = lpt->_head->as_CountedLoop();
2574 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) {
2575 Node* n = lpt->_body.at(i);
2576 if (n->outcnt() == 0) continue; // Ignore dead
2577 if (n->is_Store()) {
2578 if (store != NULL) {
2579 msg = "multiple stores";
2580 break;
2581 }
2582 int opc = n->Opcode();
2583 if (opc == Op_StoreP || opc == Op_StoreN || opc == Op_StoreNKlass || opc == Op_StoreCM) {
2584 msg = "oop fills not handled";
2585 break;
2586 }
2587 Node* value = n->in(MemNode::ValueIn);
2588 if (!lpt->is_invariant(value)) {
2589 msg = "variant store value";
2590 } else if (!_igvn.type(n->in(MemNode::Address))->isa_aryptr()) {
2591 msg = "not array address";
2592 }
2593 store = n;
2594 store_value = value;
2595 } else if (n->is_If() && n != head->loopexit()) {
2596 msg = "extra control flow";
2597 msg_node = n;
2598 }
2599 }
2600
2601 if (store == NULL) {
2602 // No store in loop
2603 return false;
2604 }
2605
2606 if (msg == NULL && head->stride_con() != 1) {
2607 // could handle negative strides too
2608 if (head->stride_con() < 0) {
2609 msg = "negative stride";
2610 } else {
2611 msg = "non-unit stride";
2612 }
2613 }
2614
2615 if (msg == NULL && !store->in(MemNode::Address)->is_AddP()) {
2616 msg = "can't handle store address";
2617 msg_node = store->in(MemNode::Address);
2618 }
2619
2620 if (msg == NULL &&
2621 (!store->in(MemNode::Memory)->is_Phi() ||
2622 store->in(MemNode::Memory)->in(LoopNode::LoopBackControl) != store)) {
2623 msg = "store memory isn't proper phi";
2624 msg_node = store->in(MemNode::Memory);
2625 }
2626
2627 // Make sure there is an appropriate fill routine
2628 BasicType t = store->as_Mem()->memory_type();
2629 const char* fill_name;
2630 if (msg == NULL &&
2631 StubRoutines::select_fill_function(t, false, fill_name) == NULL) {
2632 msg = "unsupported store";
2633 msg_node = store;
2634 }
2635
2636 if (msg != NULL) {
2637 #ifndef PRODUCT
2638 if (TraceOptimizeFill) {
2639 tty->print_cr("not fill intrinsic candidate: %s", msg);
2640 if (msg_node != NULL) msg_node->dump();
2641 }
2642 #endif
2643 return false;
2644 }
2645
2646 // Make sure the address expression can be handled. It should be
2647 // head->phi * elsize + con. head->phi might have a ConvI2L.
2648 Node* elements[4];
2649 Node* conv = NULL;
2650 bool found_index = false;
2651 int count = store->in(MemNode::Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
2652 for (int e = 0; e < count; e++) {
2653 Node* n = elements[e];
2654 if (n->is_Con() && con == NULL) {
2655 con = n;
2656 } else if (n->Opcode() == Op_LShiftX && shift == NULL) {
2657 Node* value = n->in(1);
2658 #ifdef _LP64
2659 if (value->Opcode() == Op_ConvI2L) {
2660 conv = value;
2661 value = value->in(1);
2662 }
2663 #endif
2664 if (value != head->phi()) {
2665 msg = "unhandled shift in address";
2666 } else {
2667 if (type2aelembytes(store->as_Mem()->memory_type(), true) != (1 << n->in(2)->get_int())) {
2668 msg = "scale doesn't match";
2669 } else {
2670 found_index = true;
2671 shift = n;
2672 }
2673 }
2674 } else if (n->Opcode() == Op_ConvI2L && conv == NULL) {
2675 if (n->in(1) == head->phi()) {
2676 found_index = true;
2677 conv = n;
2678 } else {
2679 msg = "unhandled input to ConvI2L";
2680 }
2681 } else if (n == head->phi()) {
2682 // no shift, check below for allowed cases
2683 found_index = true;
2684 } else {
2685 msg = "unhandled node in address";
2686 msg_node = n;
2687 }
2688 }
2689
2690 if (count == -1) {
2691 msg = "malformed address expression";
2692 msg_node = store;
2693 }
2694
2695 if (!found_index) {
2696 msg = "missing use of index";
2697 }
2698
2699 // byte sized items won't have a shift
2700 if (msg == NULL && shift == NULL && t != T_BYTE && t != T_BOOLEAN) {
2701 msg = "can't find shift";
2702 msg_node = store;
2703 }
2704
2705 if (msg != NULL) {
2706 #ifndef PRODUCT
2707 if (TraceOptimizeFill) {
2708 tty->print_cr("not fill intrinsic: %s", msg);
2709 if (msg_node != NULL) msg_node->dump();
2710 }
2711 #endif
2712 return false;
2713 }
2714
2715 // No make sure all the other nodes in the loop can be handled
2716 VectorSet ok(Thread::current()->resource_area());
2717
2718 // store related values are ok
2719 ok.set(store->_idx);
2720 ok.set(store->in(MemNode::Memory)->_idx);
2721
2722 CountedLoopEndNode* loop_exit = head->loopexit();
2723 guarantee(loop_exit != NULL, "no loop exit node");
2724
2725 // Loop structure is ok
2726 ok.set(head->_idx);
2727 ok.set(loop_exit->_idx);
2728 ok.set(head->phi()->_idx);
2729 ok.set(head->incr()->_idx);
2730 ok.set(loop_exit->cmp_node()->_idx);
2731 ok.set(loop_exit->in(1)->_idx);
2732
2733 // Address elements are ok
2734 if (con) ok.set(con->_idx);
2735 if (shift) ok.set(shift->_idx);
2736 if (conv) ok.set(conv->_idx);
2737
2738 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) {
2739 Node* n = lpt->_body.at(i);
2740 if (n->outcnt() == 0) continue; // Ignore dead
2741 if (ok.test(n->_idx)) continue;
2742 // Backedge projection is ok
2743 if (n->is_IfTrue() && n->in(0) == loop_exit) continue;
2744 if (!n->is_AddP()) {
2745 msg = "unhandled node";
2746 msg_node = n;
2747 break;
2748 }
2749 }
2750
2751 // Make sure no unexpected values are used outside the loop
2752 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) {
2753 Node* n = lpt->_body.at(i);
2754 // These values can be replaced with other nodes if they are used
2755 // outside the loop.
2756 if (n == store || n == loop_exit || n == head->incr() || n == store->in(MemNode::Memory)) continue;
2757 for (SimpleDUIterator iter(n); iter.has_next(); iter.next()) {
2758 Node* use = iter.get();
2759 if (!lpt->_body.contains(use)) {
2760 msg = "node is used outside loop";
2761 // lpt->_body.dump();
2762 msg_node = n;
2763 break;
2764 }
2765 }
2766 }
2767
2768 #ifdef ASSERT
2769 if (TraceOptimizeFill) {
2770 if (msg != NULL) {
2771 tty->print_cr("no fill intrinsic: %s", msg);
2772 if (msg_node != NULL) msg_node->dump();
2773 } else {
2774 tty->print_cr("fill intrinsic for:");
2775 }
2776 store->dump();
2777 if (Verbose) {
2778 lpt->_body.dump();
2779 }
2780 }
2781 #endif
2782
2783 return msg == NULL;
2784 }
2785
2786
2787
2788 bool PhaseIdealLoop::intrinsify_fill(IdealLoopTree* lpt) {
2789 // Only for counted inner loops
2790 if (!lpt->is_counted() || !lpt->is_inner()) {
2791 return false;
2792 }
2793
2794 // Must have constant stride
2795 CountedLoopNode* head = lpt->_head->as_CountedLoop();
2796 if (!head->is_valid_counted_loop() || !head->is_normal_loop()) {
2797 return false;
2798 }
2799
2800 // Check that the body only contains a store of a loop invariant
2801 // value that is indexed by the loop phi.
2802 Node* store = NULL;
2803 Node* store_value = NULL;
2804 Node* shift = NULL;
2805 Node* offset = NULL;
2806 if (!match_fill_loop(lpt, store, store_value, shift, offset)) {
2807 return false;
2808 }
2809
2810 #ifndef PRODUCT
2811 if (TraceLoopOpts) {
2812 tty->print("ArrayFill ");
2813 lpt->dump_head();
2814 }
2815 #endif
2816
2817 // Now replace the whole loop body by a call to a fill routine that
2818 // covers the same region as the loop.
2819 Node* base = store->in(MemNode::Address)->as_AddP()->in(AddPNode::Base);
2820
2821 // Build an expression for the beginning of the copy region
2822 Node* index = head->init_trip();
2823 #ifdef _LP64
2824 index = new ConvI2LNode(index);
2825 _igvn.register_new_node_with_optimizer(index);
2826 #endif
2827 if (shift != NULL) {
2828 // byte arrays don't require a shift but others do.
2829 index = new LShiftXNode(index, shift->in(2));
2830 _igvn.register_new_node_with_optimizer(index);
2831 }
2832 index = new AddPNode(base, base, index);
2833 _igvn.register_new_node_with_optimizer(index);
2834 Node* from = new AddPNode(base, index, offset);
2835 _igvn.register_new_node_with_optimizer(from);
2836 // Compute the number of elements to copy
2837 Node* len = new SubINode(head->limit(), head->init_trip());
2838 _igvn.register_new_node_with_optimizer(len);
2839
2840 BasicType t = store->as_Mem()->memory_type();
2841 bool aligned = false;
2842 if (offset != NULL && head->init_trip()->is_Con()) {
2843 int element_size = type2aelembytes(t);
2844 aligned = (offset->find_intptr_t_type()->get_con() + head->init_trip()->get_int() * element_size) % HeapWordSize == 0;
2845 }
2846
2847 // Build a call to the fill routine
2848 const char* fill_name;
2849 address fill = StubRoutines::select_fill_function(t, aligned, fill_name);
2850 assert(fill != NULL, "what?");
2851
2852 // Convert float/double to int/long for fill routines
2853 if (t == T_FLOAT) {
2854 store_value = new MoveF2INode(store_value);
2855 _igvn.register_new_node_with_optimizer(store_value);
2856 } else if (t == T_DOUBLE) {
2857 store_value = new MoveD2LNode(store_value);
2858 _igvn.register_new_node_with_optimizer(store_value);
2859 }
2860
2861 if (CCallingConventionRequiresIntsAsLongs &&
2862 // See StubRoutines::select_fill_function for types. FLOAT has been converted to INT.
2863 (t == T_FLOAT || t == T_INT || is_subword_type(t))) {
2864 store_value = new ConvI2LNode(store_value);
2865 _igvn.register_new_node_with_optimizer(store_value);
2866 }
2867
2868 Node* mem_phi = store->in(MemNode::Memory);
2869 Node* result_ctrl;
2870 Node* result_mem;
2871 const TypeFunc* call_type = OptoRuntime::array_fill_Type();
2872 CallLeafNode *call = new CallLeafNoFPNode(call_type, fill,
2873 fill_name, TypeAryPtr::get_array_body_type(t));
2874 uint cnt = 0;
2875 call->init_req(TypeFunc::Parms + cnt++, from);
2876 call->init_req(TypeFunc::Parms + cnt++, store_value);
2877 if (CCallingConventionRequiresIntsAsLongs) {
2878 call->init_req(TypeFunc::Parms + cnt++, C->top());
2879 }
2880 #ifdef _LP64
2881 len = new ConvI2LNode(len);
2882 _igvn.register_new_node_with_optimizer(len);
2883 #endif
2884 call->init_req(TypeFunc::Parms + cnt++, len);
2885 #ifdef _LP64
2886 call->init_req(TypeFunc::Parms + cnt++, C->top());
2887 #endif
2888 call->init_req(TypeFunc::Control, head->init_control());
2889 call->init_req(TypeFunc::I_O, C->top()); // Does no I/O.
2890 call->init_req(TypeFunc::Memory, mem_phi->in(LoopNode::EntryControl));
2891 call->init_req(TypeFunc::ReturnAdr, C->start()->proj_out(TypeFunc::ReturnAdr));
2892 call->init_req(TypeFunc::FramePtr, C->start()->proj_out(TypeFunc::FramePtr));
2893 _igvn.register_new_node_with_optimizer(call);
2894 result_ctrl = new ProjNode(call,TypeFunc::Control);
2895 _igvn.register_new_node_with_optimizer(result_ctrl);
2896 result_mem = new ProjNode(call,TypeFunc::Memory);
2897 _igvn.register_new_node_with_optimizer(result_mem);
2898
2899 /* Disable following optimization until proper fix (add missing checks).
2900
2901 // If this fill is tightly coupled to an allocation and overwrites
2902 // the whole body, allow it to take over the zeroing.
2903 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, this);
2904 if (alloc != NULL && alloc->is_AllocateArray()) {
2905 Node* length = alloc->as_AllocateArray()->Ideal_length();
2906 if (head->limit() == length &&
2907 head->init_trip() == _igvn.intcon(0)) {
2908 if (TraceOptimizeFill) {
2909 tty->print_cr("Eliminated zeroing in allocation");
2910 }
2911 alloc->maybe_set_complete(&_igvn);
2912 } else {
2913 #ifdef ASSERT
2914 if (TraceOptimizeFill) {
2915 tty->print_cr("filling array but bounds don't match");
2916 alloc->dump();
2917 head->init_trip()->dump();
2918 head->limit()->dump();
2919 length->dump();
2920 }
2921 #endif
2922 }
2923 }
2924 */
2925
2926 // Redirect the old control and memory edges that are outside the loop.
2927 Node* exit = head->loopexit()->proj_out(0);
2928 // Sometimes the memory phi of the head is used as the outgoing
2929 // state of the loop. It's safe in this case to replace it with the
2930 // result_mem.
2931 _igvn.replace_node(store->in(MemNode::Memory), result_mem);
2932 _igvn.replace_node(exit, result_ctrl);
2933 _igvn.replace_node(store, result_mem);
2934 // Any uses the increment outside of the loop become the loop limit.
2935 _igvn.replace_node(head->incr(), head->limit());
2936
2937 // Disconnect the head from the loop.
2938 for (uint i = 0; i < lpt->_body.size(); i++) {
2939 Node* n = lpt->_body.at(i);
2940 _igvn.replace_node(n, C->top());
2941 }
2942
2943 return true;
2944 }