1 /*
2 * Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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 // put body of outer strip mined loop on igvn work list as well
71 if (_head->is_CountedLoop() && _head->as_Loop()->is_strip_mined()) {
72 CountedLoopNode* l = _head->as_CountedLoop();
73 Node* outer_loop = l->outer_loop();
74 assert(outer_loop != NULL, "missing piece of strip mined loop");
75 _phase->_igvn._worklist.push(outer_loop);
76 Node* outer_loop_tail = l->outer_loop_tail();
77 assert(outer_loop_tail != NULL, "missing piece of strip mined loop");
78 _phase->_igvn._worklist.push(outer_loop_tail);
79 Node* outer_loop_end = l->outer_loop_end();
80 assert(outer_loop_end != NULL, "missing piece of strip mined loop");
81 _phase->_igvn._worklist.push(outer_loop_end);
82 Node* outer_safepoint = l->outer_safepoint();
83 assert(outer_safepoint != NULL, "missing piece of strip mined loop");
84 _phase->_igvn._worklist.push(outer_safepoint);
85 Node* cle_out = _head->as_CountedLoop()->loopexit()->proj_out(false);
86 assert(cle_out != NULL, "missing piece of strip mined loop");
87 _phase->_igvn._worklist.push(cle_out);
88 }
89 }
90
91 //------------------------------compute_exact_trip_count-----------------------
92 // Compute loop trip count if possible. Do not recalculate trip count for
93 // split loops (pre-main-post) which have their limits and inits behind Opaque node.
94 void IdealLoopTree::compute_trip_count(PhaseIdealLoop* phase) {
95 if (!_head->as_Loop()->is_valid_counted_loop()) {
96 return;
97 }
98 CountedLoopNode* cl = _head->as_CountedLoop();
99 // Trip count may become nonexact for iteration split loops since
100 // RCE modifies limits. Note, _trip_count value is not reset since
101 // it is used to limit unrolling of main loop.
102 cl->set_nonexact_trip_count();
103
104 // Loop's test should be part of loop.
105 if (!phase->is_member(this, phase->get_ctrl(cl->loopexit()->in(CountedLoopEndNode::TestValue))))
106 return; // Infinite loop
107
108 #ifdef ASSERT
109 BoolTest::mask bt = cl->loopexit()->test_trip();
110 assert(bt == BoolTest::lt || bt == BoolTest::gt ||
111 bt == BoolTest::ne, "canonical test is expected");
112 #endif
113
114 Node* init_n = cl->init_trip();
115 Node* limit_n = cl->limit();
116 if (init_n != NULL && limit_n != NULL) {
117 // Use longs to avoid integer overflow.
118 int stride_con = cl->stride_con();
119 const TypeInt* init_type = phase->_igvn.type(init_n)->is_int();
120 const TypeInt* limit_type = phase->_igvn.type(limit_n)->is_int();
121 jlong init_con = (stride_con > 0) ? init_type->_lo : init_type->_hi;
122 jlong limit_con = (stride_con > 0) ? limit_type->_hi : limit_type->_lo;
123 int stride_m = stride_con - (stride_con > 0 ? 1 : -1);
124 jlong trip_count = (limit_con - init_con + stride_m)/stride_con;
125 if (trip_count > 0 && (julong)trip_count < (julong)max_juint) {
126 if (init_n->is_Con() && limit_n->is_Con()) {
127 // Set exact trip count.
128 cl->set_exact_trip_count((uint)trip_count);
129 } else if (cl->unrolled_count() == 1) {
130 // Set maximum trip count before unrolling.
131 cl->set_trip_count((uint)trip_count);
132 }
133 }
134 }
135 }
136
137 //------------------------------compute_profile_trip_cnt----------------------------
138 // Compute loop trip count from profile data as
139 // (backedge_count + loop_exit_count) / loop_exit_count
140
141 float IdealLoopTree::compute_profile_trip_cnt_helper(Node* n) {
142 if (n->is_If()) {
143 IfNode *iff = n->as_If();
144 if (iff->_fcnt != COUNT_UNKNOWN && iff->_prob != PROB_UNKNOWN) {
145 Node *exit = is_loop_exit(iff);
146 if (exit) {
147 float exit_prob = iff->_prob;
148 if (exit->Opcode() == Op_IfFalse) exit_prob = 1.0 - exit_prob;
149 if (exit_prob > PROB_MIN) {
150 float exit_cnt = iff->_fcnt * exit_prob;
151 return exit_cnt;
152 }
153 }
154 }
155 }
156 if (n->is_Jump()) {
157 JumpNode *jmp = n->as_Jump();
158 if (jmp->_fcnt != COUNT_UNKNOWN) {
159 float* probs = jmp->_probs;
160 float exit_prob = 0;
161 PhaseIdealLoop *phase = _phase;
162 for (DUIterator_Fast imax, i = jmp->fast_outs(imax); i < imax; i++) {
163 JumpProjNode* u = jmp->fast_out(i)->as_JumpProj();
164 if (!is_member(_phase->get_loop(u))) {
165 exit_prob += probs[u->_con];
166 }
167 }
168 return exit_prob * jmp->_fcnt;
169 }
170 }
171 return 0;
172 }
173
174 void IdealLoopTree::compute_profile_trip_cnt(PhaseIdealLoop *phase) {
175 if (!_head->is_Loop()) {
176 return;
177 }
178 LoopNode* head = _head->as_Loop();
179 if (head->profile_trip_cnt() != COUNT_UNKNOWN) {
180 return; // Already computed
181 }
182 float trip_cnt = (float)max_jint; // default is big
183
184 Node* back = head->in(LoopNode::LoopBackControl);
185 while (back != head) {
186 if ((back->Opcode() == Op_IfTrue || back->Opcode() == Op_IfFalse) &&
187 back->in(0) &&
188 back->in(0)->is_If() &&
189 back->in(0)->as_If()->_fcnt != COUNT_UNKNOWN &&
190 back->in(0)->as_If()->_prob != PROB_UNKNOWN &&
191 (back->Opcode() == Op_IfTrue ? 1-back->in(0)->as_If()->_prob : back->in(0)->as_If()->_prob) > PROB_MIN) {
192 break;
193 }
194 back = phase->idom(back);
195 }
196 if (back != head) {
197 assert((back->Opcode() == Op_IfTrue || back->Opcode() == Op_IfFalse) &&
198 back->in(0), "if-projection exists");
199 IfNode* back_if = back->in(0)->as_If();
200 float loop_back_cnt = back_if->_fcnt * (back->Opcode() == Op_IfTrue ? back_if->_prob : (1 - back_if->_prob));
201
202 // Now compute a loop exit count
203 float loop_exit_cnt = 0.0f;
204 if (_child == NULL) {
205 for( uint i = 0; i < _body.size(); i++ ) {
206 Node *n = _body[i];
207 loop_exit_cnt += compute_profile_trip_cnt_helper(n);
208 }
209 } else {
210 ResourceMark rm;
211 Unique_Node_List wq;
212 wq.push(back);
213 for (uint i = 0; i < wq.size(); i++) {
214 Node *n = wq.at(i);
215 assert(n->is_CFG(), "only control nodes");
216 if (n != head) {
217 if (n->is_Region()) {
218 for (uint j = 1; j < n->req(); j++) {
219 wq.push(n->in(j));
220 }
221 } else {
222 loop_exit_cnt += compute_profile_trip_cnt_helper(n);
223 wq.push(n->in(0));
224 }
225 }
226 }
227
228 }
229 if (loop_exit_cnt > 0.0f) {
230 trip_cnt = (loop_back_cnt + loop_exit_cnt) / loop_exit_cnt;
231 } else {
232 // No exit count so use
233 trip_cnt = loop_back_cnt;
234 }
235 } else {
236 head->mark_profile_trip_failed();
237 }
238 #ifndef PRODUCT
239 if (TraceProfileTripCount) {
240 tty->print_cr("compute_profile_trip_cnt lp: %d cnt: %f\n", head->_idx, trip_cnt);
241 }
242 #endif
243 head->set_profile_trip_cnt(trip_cnt);
244 }
245
246 //---------------------is_invariant_addition-----------------------------
247 // Return nonzero index of invariant operand for an Add or Sub
248 // of (nonconstant) invariant and variant values. Helper for reassociate_invariants.
249 int IdealLoopTree::is_invariant_addition(Node* n, PhaseIdealLoop *phase) {
250 int op = n->Opcode();
251 if (op == Op_AddI || op == Op_SubI) {
252 bool in1_invar = this->is_invariant(n->in(1));
253 bool in2_invar = this->is_invariant(n->in(2));
254 if (in1_invar && !in2_invar) return 1;
255 if (!in1_invar && in2_invar) return 2;
256 }
257 return 0;
258 }
259
260 //---------------------reassociate_add_sub-----------------------------
261 // Reassociate invariant add and subtract expressions:
262 //
263 // inv1 + (x + inv2) => ( inv1 + inv2) + x
264 // (x + inv2) + inv1 => ( inv1 + inv2) + x
265 // inv1 + (x - inv2) => ( inv1 - inv2) + x
266 // inv1 - (inv2 - x) => ( inv1 - inv2) + x
267 // (x + inv2) - inv1 => (-inv1 + inv2) + x
268 // (x - inv2) + inv1 => ( inv1 - inv2) + x
269 // (x - inv2) - inv1 => (-inv1 - inv2) + x
270 // inv1 + (inv2 - x) => ( inv1 + inv2) - x
271 // inv1 - (x - inv2) => ( inv1 + inv2) - x
272 // (inv2 - x) + inv1 => ( inv1 + inv2) - x
273 // (inv2 - x) - inv1 => (-inv1 + inv2) - x
274 // inv1 - (x + inv2) => ( inv1 - inv2) - x
275 //
276 Node* IdealLoopTree::reassociate_add_sub(Node* n1, PhaseIdealLoop *phase) {
277 if ((!n1->is_Add() && !n1->is_Sub()) || n1->outcnt() == 0) return NULL;
278 if (is_invariant(n1)) return NULL;
279 int inv1_idx = is_invariant_addition(n1, phase);
280 if (!inv1_idx) return NULL;
281 // Don't mess with add of constant (igvn moves them to expression tree root.)
282 if (n1->is_Add() && n1->in(2)->is_Con()) return NULL;
283 Node* inv1 = n1->in(inv1_idx);
284 Node* n2 = n1->in(3 - inv1_idx);
285 int inv2_idx = is_invariant_addition(n2, phase);
286 if (!inv2_idx) return NULL;
287 Node* x = n2->in(3 - inv2_idx);
288 Node* inv2 = n2->in(inv2_idx);
289
290 bool neg_x = n2->is_Sub() && inv2_idx == 1;
291 bool neg_inv2 = n2->is_Sub() && inv2_idx == 2;
292 bool neg_inv1 = n1->is_Sub() && inv1_idx == 2;
293 if (n1->is_Sub() && inv1_idx == 1) {
294 neg_x = !neg_x;
295 neg_inv2 = !neg_inv2;
296 }
297 Node* inv1_c = phase->get_ctrl(inv1);
298 Node* inv2_c = phase->get_ctrl(inv2);
299 Node* n_inv1;
300 if (neg_inv1) {
301 Node *zero = phase->_igvn.intcon(0);
302 phase->set_ctrl(zero, phase->C->root());
303 n_inv1 = new SubINode(zero, inv1);
304 phase->register_new_node(n_inv1, inv1_c);
305 } else {
306 n_inv1 = inv1;
307 }
308 Node* inv;
309 if (neg_inv2) {
310 inv = new SubINode(n_inv1, inv2);
311 } else {
312 inv = new AddINode(n_inv1, inv2);
313 }
314 phase->register_new_node(inv, phase->get_early_ctrl(inv));
315
316 Node* addx;
317 if (neg_x) {
318 addx = new SubINode(inv, x);
319 } else {
320 addx = new AddINode(x, inv);
321 }
322 phase->register_new_node(addx, phase->get_ctrl(x));
323 phase->_igvn.replace_node(n1, addx);
324 assert(phase->get_loop(phase->get_ctrl(n1)) == this, "");
325 _body.yank(n1);
326 return addx;
327 }
328
329 //---------------------reassociate_invariants-----------------------------
330 // Reassociate invariant expressions:
331 void IdealLoopTree::reassociate_invariants(PhaseIdealLoop *phase) {
332 for (int i = _body.size() - 1; i >= 0; i--) {
333 Node *n = _body.at(i);
334 for (int j = 0; j < 5; j++) {
335 Node* nn = reassociate_add_sub(n, phase);
336 if (nn == NULL) break;
337 n = nn; // again
338 };
339 }
340 }
341
342 //------------------------------policy_peeling---------------------------------
343 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can
344 // make some loop-invariant test (usually a null-check) happen before the loop.
345 bool IdealLoopTree::policy_peeling( PhaseIdealLoop *phase ) const {
346 Node *test = ((IdealLoopTree*)this)->tail();
347 int body_size = ((IdealLoopTree*)this)->_body.size();
348 // Peeling does loop cloning which can result in O(N^2) node construction
349 if( body_size > 255 /* Prevent overflow for large body_size */
350 || (body_size * body_size + phase->C->live_nodes()) > phase->C->max_node_limit() ) {
351 return false; // too large to safely clone
352 }
353
354 // check for vectorized loops, any peeling done was already applied
355 if (_head->is_CountedLoop() && _head->as_CountedLoop()->do_unroll_only()) return false;
356
357 while( test != _head ) { // Scan till run off top of loop
358 if( test->is_If() ) { // Test?
359 Node *ctrl = phase->get_ctrl(test->in(1));
360 if (ctrl->is_top())
361 return false; // Found dead test on live IF? No peeling!
362 // Standard IF only has one input value to check for loop invariance
363 assert(test->Opcode() == Op_If || test->Opcode() == Op_CountedLoopEnd || test->Opcode() == Op_RangeCheck, "Check this code when new subtype is added");
364 // Condition is not a member of this loop?
365 if( !is_member(phase->get_loop(ctrl)) &&
366 is_loop_exit(test) )
367 return true; // Found reason to peel!
368 }
369 // Walk up dominators to loop _head looking for test which is
370 // executed on every path thru loop.
371 test = phase->idom(test);
372 }
373 return false;
374 }
375
376 //------------------------------peeled_dom_test_elim---------------------------
377 // If we got the effect of peeling, either by actually peeling or by making
378 // a pre-loop which must execute at least once, we can remove all
379 // loop-invariant dominated tests in the main body.
380 void PhaseIdealLoop::peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new ) {
381 bool progress = true;
382 while( progress ) {
383 progress = false; // Reset for next iteration
384 Node *prev = loop->_head->in(LoopNode::LoopBackControl);//loop->tail();
385 Node *test = prev->in(0);
386 while( test != loop->_head ) { // Scan till run off top of loop
387
388 int p_op = prev->Opcode();
389 if( (p_op == Op_IfFalse || p_op == Op_IfTrue) &&
390 test->is_If() && // Test?
391 !test->in(1)->is_Con() && // And not already obvious?
392 // Condition is not a member of this loop?
393 !loop->is_member(get_loop(get_ctrl(test->in(1))))){
394 // Walk loop body looking for instances of this test
395 for( uint i = 0; i < loop->_body.size(); i++ ) {
396 Node *n = loop->_body.at(i);
397 if( n->is_If() && n->in(1) == test->in(1) /*&& n != loop->tail()->in(0)*/ ) {
398 // IfNode was dominated by version in peeled loop body
399 progress = true;
400 dominated_by( old_new[prev->_idx], n );
401 }
402 }
403 }
404 prev = test;
405 test = idom(test);
406 } // End of scan tests in loop
407
408 } // End of while( progress )
409 }
410
411 //------------------------------do_peeling-------------------------------------
412 // Peel the first iteration of the given loop.
413 // Step 1: Clone the loop body. The clone becomes the peeled iteration.
414 // The pre-loop illegally has 2 control users (old & new loops).
415 // Step 2: Make the old-loop fall-in edges point to the peeled iteration.
416 // Do this by making the old-loop fall-in edges act as if they came
417 // around the loopback from the prior iteration (follow the old-loop
418 // backedges) and then map to the new peeled iteration. This leaves
419 // the pre-loop with only 1 user (the new peeled iteration), but the
420 // peeled-loop backedge has 2 users.
421 // Step 3: Cut the backedge on the clone (so its not a loop) and remove the
422 // extra backedge user.
423 //
424 // orig
425 //
426 // stmt1
427 // |
428 // v
429 // loop predicate
430 // |
431 // v
432 // loop<----+
433 // | |
434 // stmt2 |
435 // | |
436 // v |
437 // if ^
438 // / \ |
439 // / \ |
440 // v v |
441 // false true |
442 // / \ |
443 // / ----+
444 // |
445 // v
446 // exit
447 //
448 //
449 // after clone loop
450 //
451 // stmt1
452 // |
453 // v
454 // loop predicate
455 // / \
456 // clone / \ orig
457 // / \
458 // / \
459 // v v
460 // +---->loop clone loop<----+
461 // | | | |
462 // | stmt2 clone stmt2 |
463 // | | | |
464 // | v v |
465 // ^ if clone If ^
466 // | / \ / \ |
467 // | / \ / \ |
468 // | v v v v |
469 // | true false false true |
470 // | / \ / \ |
471 // +---- \ / ----+
472 // \ /
473 // 1v v2
474 // region
475 // |
476 // v
477 // exit
478 //
479 //
480 // after peel and predicate move
481 //
482 // stmt1
483 // /
484 // /
485 // clone / orig
486 // /
487 // / +----------+
488 // / | |
489 // / loop predicate |
490 // / | |
491 // v v |
492 // TOP-->loop clone loop<----+ |
493 // | | | |
494 // stmt2 clone stmt2 | |
495 // | | | ^
496 // v v | |
497 // if clone If ^ |
498 // / \ / \ | |
499 // / \ / \ | |
500 // v v v v | |
501 // true false false true | |
502 // | \ / \ | |
503 // | \ / ----+ ^
504 // | \ / |
505 // | 1v v2 |
506 // v region |
507 // | | |
508 // | v |
509 // | exit |
510 // | |
511 // +--------------->-----------------+
512 //
513 //
514 // final graph
515 //
516 // stmt1
517 // |
518 // v
519 // stmt2 clone
520 // |
521 // v
522 // if clone
523 // / |
524 // / |
525 // v v
526 // false true
527 // | |
528 // | v
529 // | loop predicate
530 // | |
531 // | v
532 // | loop<----+
533 // | | |
534 // | stmt2 |
535 // | | |
536 // | v |
537 // v if ^
538 // | / \ |
539 // | / \ |
540 // | v v |
541 // | false true |
542 // | | \ |
543 // v v --+
544 // region
545 // |
546 // v
547 // exit
548 //
549 void PhaseIdealLoop::do_peeling( IdealLoopTree *loop, Node_List &old_new ) {
550
551 C->set_major_progress();
552 // Peeling a 'main' loop in a pre/main/post situation obfuscates the
553 // 'pre' loop from the main and the 'pre' can no longer have its
554 // iterations adjusted. Therefore, we need to declare this loop as
555 // no longer a 'main' loop; it will need new pre and post loops before
556 // we can do further RCE.
557 #ifndef PRODUCT
558 if (TraceLoopOpts) {
559 tty->print("Peel ");
560 loop->dump_head();
561 }
562 #endif
563 LoopNode* head = loop->_head->as_Loop();
564 bool counted_loop = head->is_CountedLoop();
565 if (counted_loop) {
566 CountedLoopNode *cl = head->as_CountedLoop();
567 assert(cl->trip_count() > 0, "peeling a fully unrolled loop");
568 cl->set_trip_count(cl->trip_count() - 1);
569 if (cl->is_main_loop()) {
570 cl->set_normal_loop();
571 #ifndef PRODUCT
572 if (PrintOpto && VerifyLoopOptimizations) {
573 tty->print("Peeling a 'main' loop; resetting to 'normal' ");
574 loop->dump_head();
575 }
576 #endif
577 }
578 }
579 Node* entry = head->in(LoopNode::EntryControl);
580
581 // Step 1: Clone the loop body. The clone becomes the peeled iteration.
582 // The pre-loop illegally has 2 control users (old & new loops).
583 clone_loop(loop, old_new, dom_depth(head->skip_strip_mined()), ControlAroundStripMined);
584
585 // Step 2: Make the old-loop fall-in edges point to the peeled iteration.
586 // Do this by making the old-loop fall-in edges act as if they came
587 // around the loopback from the prior iteration (follow the old-loop
588 // backedges) and then map to the new peeled iteration. This leaves
589 // the pre-loop with only 1 user (the new peeled iteration), but the
590 // peeled-loop backedge has 2 users.
591 Node* new_entry = old_new[head->in(LoopNode::LoopBackControl)->_idx];
592 _igvn.hash_delete(head->skip_strip_mined());
593 head->skip_strip_mined()->set_req(LoopNode::EntryControl, new_entry);
594 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
595 Node* old = head->fast_out(j);
596 if (old->in(0) == loop->_head && old->req() == 3 && old->is_Phi()) {
597 Node* new_exit_value = old_new[old->in(LoopNode::LoopBackControl)->_idx];
598 if (!new_exit_value ) // Backedge value is ALSO loop invariant?
599 // Then loop body backedge value remains the same.
600 new_exit_value = old->in(LoopNode::LoopBackControl);
601 _igvn.hash_delete(old);
602 old->set_req(LoopNode::EntryControl, new_exit_value);
603 }
604 }
605
606
607 // Step 3: Cut the backedge on the clone (so its not a loop) and remove the
608 // extra backedge user.
609 Node* new_head = old_new[head->_idx];
610 _igvn.hash_delete(new_head);
611 new_head->set_req(LoopNode::LoopBackControl, C->top());
612 for (DUIterator_Fast j2max, j2 = new_head->fast_outs(j2max); j2 < j2max; j2++) {
613 Node* use = new_head->fast_out(j2);
614 if (use->in(0) == new_head && use->req() == 3 && use->is_Phi()) {
615 _igvn.hash_delete(use);
616 use->set_req(LoopNode::LoopBackControl, C->top());
617 }
618 }
619
620
621 // Step 4: Correct dom-depth info. Set to loop-head depth.
622 int dd = dom_depth(head);
623 set_idom(head, head->in(1), dd);
624 for (uint j3 = 0; j3 < loop->_body.size(); j3++) {
625 Node *old = loop->_body.at(j3);
626 Node *nnn = old_new[old->_idx];
627 if (!has_ctrl(nnn))
628 set_idom(nnn, idom(nnn), dd-1);
629 }
630
631 // Now force out all loop-invariant dominating tests. The optimizer
632 // finds some, but we _know_ they are all useless.
633 peeled_dom_test_elim(loop,old_new);
634
635 loop->record_for_igvn();
636 }
637
638 #define EMPTY_LOOP_SIZE 7 // number of nodes in an empty loop
639
640 //------------------------------policy_maximally_unroll------------------------
641 // Calculate exact loop trip count and return true if loop can be maximally
642 // unrolled.
643 bool IdealLoopTree::policy_maximally_unroll( PhaseIdealLoop *phase ) const {
644 CountedLoopNode *cl = _head->as_CountedLoop();
645 assert(cl->is_normal_loop(), "");
646 if (!cl->is_valid_counted_loop())
647 return false; // Malformed counted loop
648
649 if (!cl->has_exact_trip_count()) {
650 // Trip count is not exact.
651 return false;
652 }
653
654 uint trip_count = cl->trip_count();
655 // Note, max_juint is used to indicate unknown trip count.
656 assert(trip_count > 1, "one iteration loop should be optimized out already");
657 assert(trip_count < max_juint, "exact trip_count should be less than max_uint.");
658
659 // Real policy: if we maximally unroll, does it get too big?
660 // Allow the unrolled mess to get larger than standard loop
661 // size. After all, it will no longer be a loop.
662 uint body_size = _body.size();
663 uint unroll_limit = (uint)LoopUnrollLimit * 4;
664 assert( (intx)unroll_limit == LoopUnrollLimit * 4, "LoopUnrollLimit must fit in 32bits");
665 if (trip_count > unroll_limit || body_size > unroll_limit) {
666 return false;
667 }
668
669 // Fully unroll a loop with few iterations regardless next
670 // conditions since following loop optimizations will split
671 // such loop anyway (pre-main-post).
672 if (trip_count <= 3)
673 return true;
674
675 // Take into account that after unroll conjoined heads and tails will fold,
676 // otherwise policy_unroll() may allow more unrolling than max unrolling.
677 uint new_body_size = EMPTY_LOOP_SIZE + (body_size - EMPTY_LOOP_SIZE) * trip_count;
678 uint tst_body_size = (new_body_size - EMPTY_LOOP_SIZE) / trip_count + EMPTY_LOOP_SIZE;
679 if (body_size != tst_body_size) // Check for int overflow
680 return false;
681 if (new_body_size > unroll_limit ||
682 // Unrolling can result in a large amount of node construction
683 new_body_size >= phase->C->max_node_limit() - phase->C->live_nodes()) {
684 return false;
685 }
686
687 // Do not unroll a loop with String intrinsics code.
688 // String intrinsics are large and have loops.
689 for (uint k = 0; k < _body.size(); k++) {
690 Node* n = _body.at(k);
691 switch (n->Opcode()) {
692 case Op_StrComp:
693 case Op_StrEquals:
694 case Op_StrIndexOf:
695 case Op_StrIndexOfChar:
696 case Op_EncodeISOArray:
697 case Op_AryEq:
698 case Op_HasNegatives: {
699 return false;
700 }
701 #if INCLUDE_RTM_OPT
702 case Op_FastLock:
703 case Op_FastUnlock: {
704 // Don't unroll RTM locking code because it is large.
705 if (UseRTMLocking) {
706 return false;
707 }
708 }
709 #endif
710 } // switch
711 }
712
713 return true; // Do maximally unroll
714 }
715
716
717 //------------------------------policy_unroll----------------------------------
718 // Return TRUE or FALSE if the loop should be unrolled or not. Unroll if
719 // the loop is a CountedLoop and the body is small enough.
720 bool IdealLoopTree::policy_unroll(PhaseIdealLoop *phase) {
721
722 CountedLoopNode *cl = _head->as_CountedLoop();
723 assert(cl->is_normal_loop() || cl->is_main_loop(), "");
724
725 if (!cl->is_valid_counted_loop())
726 return false; // Malformed counted loop
727
728 // Protect against over-unrolling.
729 // After split at least one iteration will be executed in pre-loop.
730 if (cl->trip_count() <= (uint)(cl->is_normal_loop() ? 2 : 1)) return false;
731
732 _local_loop_unroll_limit = LoopUnrollLimit;
733 _local_loop_unroll_factor = 4;
734 int future_unroll_ct = cl->unrolled_count() * 2;
735 if (!cl->is_vectorized_loop()) {
736 if (future_unroll_ct > LoopMaxUnroll) return false;
737 } else {
738 // obey user constraints on vector mapped loops with additional unrolling applied
739 int unroll_constraint = (cl->slp_max_unroll()) ? cl->slp_max_unroll() : 1;
740 if ((future_unroll_ct / unroll_constraint) > LoopMaxUnroll) return false;
741 }
742
743 // Check for initial stride being a small enough constant
744 if (abs(cl->stride_con()) > (1<<2)*future_unroll_ct) return false;
745
746 // Don't unroll if the next round of unrolling would push us
747 // over the expected trip count of the loop. One is subtracted
748 // from the expected trip count because the pre-loop normally
749 // executes 1 iteration.
750 if (UnrollLimitForProfileCheck > 0 &&
751 cl->profile_trip_cnt() != COUNT_UNKNOWN &&
752 future_unroll_ct > UnrollLimitForProfileCheck &&
753 (float)future_unroll_ct > cl->profile_trip_cnt() - 1.0) {
754 return false;
755 }
756
757 // When unroll count is greater than LoopUnrollMin, don't unroll if:
758 // the residual iterations are more than 10% of the trip count
759 // and rounds of "unroll,optimize" are not making significant progress
760 // Progress defined as current size less than 20% larger than previous size.
761 if (UseSuperWord && cl->node_count_before_unroll() > 0 &&
762 future_unroll_ct > LoopUnrollMin &&
763 (future_unroll_ct - 1) * (100 / LoopPercentProfileLimit) > cl->profile_trip_cnt() &&
764 1.2 * cl->node_count_before_unroll() < (double)_body.size()) {
765 return false;
766 }
767
768 Node *init_n = cl->init_trip();
769 Node *limit_n = cl->limit();
770 int stride_con = cl->stride_con();
771 if (limit_n == NULL) return false; // We will dereference it below.
772
773 // Non-constant bounds.
774 // Protect against over-unrolling when init or/and limit are not constant
775 // (so that trip_count's init value is maxint) but iv range is known.
776 if (init_n == NULL || !init_n->is_Con() || !limit_n->is_Con()) {
777 Node* phi = cl->phi();
778 if (phi != NULL) {
779 assert(phi->is_Phi() && phi->in(0) == _head, "Counted loop should have iv phi.");
780 const TypeInt* iv_type = phase->_igvn.type(phi)->is_int();
781 int next_stride = stride_con * 2; // stride after this unroll
782 if (next_stride > 0) {
783 if (iv_type->_lo + next_stride <= iv_type->_lo || // overflow
784 iv_type->_lo + next_stride > iv_type->_hi) {
785 return false; // over-unrolling
786 }
787 } else if (next_stride < 0) {
788 if (iv_type->_hi + next_stride >= iv_type->_hi || // overflow
789 iv_type->_hi + next_stride < iv_type->_lo) {
790 return false; // over-unrolling
791 }
792 }
793 }
794 }
795
796 // After unroll limit will be adjusted: new_limit = limit-stride.
797 // Bailout if adjustment overflow.
798 const TypeInt* limit_type = phase->_igvn.type(limit_n)->is_int();
799 if ((stride_con > 0 && ((limit_type->_hi - stride_con) >= limit_type->_hi)) ||
800 (stride_con < 0 && ((limit_type->_lo - stride_con) <= limit_type->_lo)))
801 return false; // overflow
802
803 // Adjust body_size to determine if we unroll or not
804 uint body_size = _body.size();
805 // Key test to unroll loop in CRC32 java code
806 int xors_in_loop = 0;
807 // Also count ModL, DivL and MulL which expand mightly
808 for (uint k = 0; k < _body.size(); k++) {
809 Node* n = _body.at(k);
810 switch (n->Opcode()) {
811 case Op_XorI: xors_in_loop++; break; // CRC32 java code
812 case Op_ModL: body_size += 30; break;
813 case Op_DivL: body_size += 30; break;
814 case Op_MulL: body_size += 10; break;
815 case Op_StrComp:
816 case Op_StrEquals:
817 case Op_StrIndexOf:
818 case Op_StrIndexOfChar:
819 case Op_EncodeISOArray:
820 case Op_AryEq:
821 case Op_HasNegatives: {
822 // Do not unroll a loop with String intrinsics code.
823 // String intrinsics are large and have loops.
824 return false;
825 }
826 #if INCLUDE_RTM_OPT
827 case Op_FastLock:
828 case Op_FastUnlock: {
829 // Don't unroll RTM locking code because it is large.
830 if (UseRTMLocking) {
831 return false;
832 }
833 }
834 #endif
835 } // switch
836 }
837
838 if (UseSuperWord) {
839 if (!cl->is_reduction_loop()) {
840 phase->mark_reductions(this);
841 }
842
843 // Only attempt slp analysis when user controls do not prohibit it
844 if (LoopMaxUnroll > _local_loop_unroll_factor) {
845 // Once policy_slp_analysis succeeds, mark the loop with the
846 // maximal unroll factor so that we minimize analysis passes
847 if (future_unroll_ct >= _local_loop_unroll_factor) {
848 policy_unroll_slp_analysis(cl, phase, future_unroll_ct);
849 }
850 }
851 }
852
853 int slp_max_unroll_factor = cl->slp_max_unroll();
854 if ((LoopMaxUnroll < slp_max_unroll_factor) && FLAG_IS_DEFAULT(LoopMaxUnroll) && UseSubwordForMaxVector) {
855 LoopMaxUnroll = slp_max_unroll_factor;
856 }
857 if (cl->has_passed_slp()) {
858 if (slp_max_unroll_factor >= future_unroll_ct) return true;
859 // Normal case: loop too big
860 return false;
861 }
862
863 // Check for being too big
864 if (body_size > (uint)_local_loop_unroll_limit) {
865 if ((cl->is_subword_loop() || xors_in_loop >= 4) && body_size < (uint)LoopUnrollLimit * 4) {
866 return true;
867 }
868 // Normal case: loop too big
869 return false;
870 }
871
872 if (cl->do_unroll_only()) {
873 if (TraceSuperWordLoopUnrollAnalysis) {
874 tty->print_cr("policy_unroll passed vector loop(vlen=%d,factor = %d)\n", slp_max_unroll_factor, future_unroll_ct);
875 }
876 }
877
878 // Unroll once! (Each trip will soon do double iterations)
879 return true;
880 }
881
882 void IdealLoopTree::policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_ct) {
883 // Enable this functionality target by target as needed
884 if (SuperWordLoopUnrollAnalysis) {
885 if (!cl->was_slp_analyzed()) {
886 SuperWord sw(phase);
887 sw.transform_loop(this, false);
888
889 // If the loop is slp canonical analyze it
890 if (sw.early_return() == false) {
891 sw.unrolling_analysis(_local_loop_unroll_factor);
892 }
893 }
894
895 if (cl->has_passed_slp()) {
896 int slp_max_unroll_factor = cl->slp_max_unroll();
897 if (slp_max_unroll_factor >= future_unroll_ct) {
898 int new_limit = cl->node_count_before_unroll() * slp_max_unroll_factor;
899 if (new_limit > LoopUnrollLimit) {
900 if (TraceSuperWordLoopUnrollAnalysis) {
901 tty->print_cr("slp analysis unroll=%d, default limit=%d\n", new_limit, _local_loop_unroll_limit);
902 }
903 _local_loop_unroll_limit = new_limit;
904 }
905 }
906 }
907 }
908 }
909
910 //------------------------------policy_align-----------------------------------
911 // Return TRUE or FALSE if the loop should be cache-line aligned. Gather the
912 // expression that does the alignment. Note that only one array base can be
913 // aligned in a loop (unless the VM guarantees mutual alignment). Note that
914 // if we vectorize short memory ops into longer memory ops, we may want to
915 // increase alignment.
916 bool IdealLoopTree::policy_align( PhaseIdealLoop *phase ) const {
917 return false;
918 }
919
920 //------------------------------policy_range_check-----------------------------
921 // Return TRUE or FALSE if the loop should be range-check-eliminated.
922 // Actually we do iteration-splitting, a more powerful form of RCE.
923 bool IdealLoopTree::policy_range_check( PhaseIdealLoop *phase ) const {
924 if (!RangeCheckElimination) return false;
925
926 CountedLoopNode *cl = _head->as_CountedLoop();
927 // If we unrolled with no intention of doing RCE and we later
928 // changed our minds, we got no pre-loop. Either we need to
929 // make a new pre-loop, or we gotta disallow RCE.
930 if (cl->is_main_no_pre_loop()) return false; // Disallowed for now.
931 Node *trip_counter = cl->phi();
932
933 // check for vectorized loops, some opts are no longer needed
934 if (cl->do_unroll_only()) return false;
935
936 // Check loop body for tests of trip-counter plus loop-invariant vs
937 // loop-invariant.
938 for (uint i = 0; i < _body.size(); i++) {
939 Node *iff = _body[i];
940 if (iff->Opcode() == Op_If ||
941 iff->Opcode() == Op_RangeCheck) { // Test?
942
943 // Comparing trip+off vs limit
944 Node *bol = iff->in(1);
945 if (bol->req() != 2) continue; // dead constant test
946 if (!bol->is_Bool()) {
947 assert(bol->Opcode() == Op_Conv2B, "predicate check only");
948 continue;
949 }
950 if (bol->as_Bool()->_test._test == BoolTest::ne)
951 continue; // not RC
952
953 Node *cmp = bol->in(1);
954 Node *rc_exp = cmp->in(1);
955 Node *limit = cmp->in(2);
956
957 Node *limit_c = phase->get_ctrl(limit);
958 if( limit_c == phase->C->top() )
959 return false; // Found dead test on live IF? No RCE!
960 if( is_member(phase->get_loop(limit_c) ) ) {
961 // Compare might have operands swapped; commute them
962 rc_exp = cmp->in(2);
963 limit = cmp->in(1);
964 limit_c = phase->get_ctrl(limit);
965 if( is_member(phase->get_loop(limit_c) ) )
966 continue; // Both inputs are loop varying; cannot RCE
967 }
968
969 if (!phase->is_scaled_iv_plus_offset(rc_exp, trip_counter, NULL, NULL)) {
970 continue;
971 }
972 // Yeah! Found a test like 'trip+off vs limit'
973 // Test is an IfNode, has 2 projections. If BOTH are in the loop
974 // we need loop unswitching instead of iteration splitting.
975 if( is_loop_exit(iff) )
976 return true; // Found reason to split iterations
977 } // End of is IF
978 }
979
980 return false;
981 }
982
983 //------------------------------policy_peel_only-------------------------------
984 // Return TRUE or FALSE if the loop should NEVER be RCE'd or aligned. Useful
985 // for unrolling loops with NO array accesses.
986 bool IdealLoopTree::policy_peel_only( PhaseIdealLoop *phase ) const {
987 // check for vectorized loops, any peeling done was already applied
988 if (_head->is_CountedLoop() && _head->as_CountedLoop()->do_unroll_only()) return false;
989
990 for( uint i = 0; i < _body.size(); i++ )
991 if( _body[i]->is_Mem() )
992 return false;
993
994 // No memory accesses at all!
995 return true;
996 }
997
998 //------------------------------clone_up_backedge_goo--------------------------
999 // If Node n lives in the back_ctrl block and cannot float, we clone a private
1000 // version of n in preheader_ctrl block and return that, otherwise return n.
1001 Node *PhaseIdealLoop::clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones ) {
1002 if( get_ctrl(n) != back_ctrl ) return n;
1003
1004 // Only visit once
1005 if (visited.test_set(n->_idx)) {
1006 Node *x = clones.find(n->_idx);
1007 if (x != NULL)
1008 return x;
1009 return n;
1010 }
1011
1012 Node *x = NULL; // If required, a clone of 'n'
1013 // Check for 'n' being pinned in the backedge.
1014 if( n->in(0) && n->in(0) == back_ctrl ) {
1015 assert(clones.find(n->_idx) == NULL, "dead loop");
1016 x = n->clone(); // Clone a copy of 'n' to preheader
1017 clones.push(x, n->_idx);
1018 x->set_req( 0, preheader_ctrl ); // Fix x's control input to preheader
1019 }
1020
1021 // Recursive fixup any other input edges into x.
1022 // If there are no changes we can just return 'n', otherwise
1023 // we need to clone a private copy and change it.
1024 for( uint i = 1; i < n->req(); i++ ) {
1025 Node *g = clone_up_backedge_goo( back_ctrl, preheader_ctrl, n->in(i), visited, clones );
1026 if( g != n->in(i) ) {
1027 if( !x ) {
1028 assert(clones.find(n->_idx) == NULL, "dead loop");
1029 x = n->clone();
1030 clones.push(x, n->_idx);
1031 }
1032 x->set_req(i, g);
1033 }
1034 }
1035 if( x ) { // x can legally float to pre-header location
1036 register_new_node( x, preheader_ctrl );
1037 return x;
1038 } else { // raise n to cover LCA of uses
1039 set_ctrl( n, find_non_split_ctrl(back_ctrl->in(0)) );
1040 }
1041 return n;
1042 }
1043
1044 Node* PhaseIdealLoop::cast_incr_before_loop(Node* incr, Node* ctrl, Node* loop) {
1045 Node* castii = new CastIINode(incr, TypeInt::INT, true);
1046 castii->set_req(0, ctrl);
1047 register_new_node(castii, ctrl);
1048 for (DUIterator_Fast imax, i = incr->fast_outs(imax); i < imax; i++) {
1049 Node* n = incr->fast_out(i);
1050 if (n->is_Phi() && n->in(0) == loop) {
1051 int nrep = n->replace_edge(incr, castii);
1052 return castii;
1053 }
1054 }
1055 return NULL;
1056 }
1057
1058 // Make a copy of the skeleton range check predicates before the main
1059 // loop and set the initial value of loop as input. After unrolling,
1060 // the range of values for the induction variable in the main loop can
1061 // fall outside the allowed range of values by the array access (main
1062 // loop is never executed). When that happens, range check
1063 // CastII/ConvI2L nodes cause some data paths to die. For consistency,
1064 // the control paths must die too but the range checks were removed by
1065 // predication. The range checks that we add here guarantee that they do.
1066 void PhaseIdealLoop::duplicate_predicates_helper(Node* predicate, Node* castii, IdealLoopTree* outer_loop,
1067 LoopNode* outer_main_head, uint dd_main_head) {
1068 if (predicate != NULL) {
1069 IfNode* iff = predicate->in(0)->as_If();
1070 ProjNode* uncommon_proj = iff->proj_out(1 - predicate->as_Proj()->_con);
1071 Node* rgn = uncommon_proj->unique_ctrl_out();
1072 assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct");
1073 assert(iff->in(1)->in(1)->Opcode() == Op_Opaque1, "unexpected predicate shape");
1074 predicate = iff->in(0);
1075 Node* current_proj = outer_main_head->in(LoopNode::EntryControl);
1076 Node* prev_proj = current_proj;
1077 while (predicate != NULL && predicate->is_Proj() && predicate->in(0)->is_If()) {
1078 iff = predicate->in(0)->as_If();
1079 uncommon_proj = iff->proj_out(1 - predicate->as_Proj()->_con);
1080 if (uncommon_proj->unique_ctrl_out() != rgn)
1081 break;
1082 if (iff->in(1)->Opcode() == Op_Opaque4) {
1083 // Clone the predicate twice and initialize one with the initial
1084 // value of the loop induction variable. Leave the other predicate
1085 // to be initialized when increasing the stride during loop unrolling.
1086 prev_proj = update_skeleton_predicate(iff, castii, predicate, uncommon_proj, current_proj, outer_loop, prev_proj);
1087 Node* value = new Opaque1Node(C, castii);
1088 register_new_node(value, current_proj);
1089 prev_proj = update_skeleton_predicate(iff, value, predicate, uncommon_proj, current_proj, outer_loop, prev_proj);
1090 // Remove the skeleton predicate from the pre-loop
1091 _igvn.replace_input_of(iff, 1, _igvn.intcon(1));
1092 }
1093 predicate = predicate->in(0)->in(0);
1094 }
1095 _igvn.replace_input_of(outer_main_head, LoopNode::EntryControl, prev_proj);
1096 set_idom(outer_main_head, prev_proj, dd_main_head);
1097 }
1098 }
1099
1100 Node* PhaseIdealLoop::update_skeleton_predicate(Node* iff, Node* value, Node* predicate, Node* uncommon_proj,
1101 Node* current_proj, IdealLoopTree* outer_loop, Node* prev_proj) {
1102 bool clone = (outer_loop != NULL); // Clone the predicate?
1103 Node_Stack to_clone(2);
1104 to_clone.push(iff->in(1), 1);
1105 uint current = C->unique();
1106 Node* result = NULL;
1107 // Look for the opaque node to replace with the new value
1108 // and clone everything in between. We keep the Opaque4 node
1109 // so the duplicated predicates are eliminated once loop
1110 // opts are over: they are here only to keep the IR graph
1111 // consistent.
1112 do {
1113 Node* n = to_clone.node();
1114 uint i = to_clone.index();
1115 Node* m = n->in(i);
1116 int op = m->Opcode();
1117 if (m->is_Bool() ||
1118 m->is_Cmp() ||
1119 op == Op_AndL ||
1120 op == Op_OrL ||
1121 op == Op_RShiftL ||
1122 op == Op_LShiftL ||
1123 op == Op_AddL ||
1124 op == Op_AddI ||
1125 op == Op_MulL ||
1126 op == Op_MulI ||
1127 op == Op_SubL ||
1128 op == Op_SubI ||
1129 op == Op_ConvI2L) {
1130 to_clone.push(m, 1);
1131 continue;
1132 }
1133 if (op == Op_Opaque1) {
1134 if (!clone) {
1135 // Update the input of the Opaque1Node and exit
1136 _igvn.replace_input_of(m, 1, value);
1137 return prev_proj;
1138 }
1139 if (n->_idx < current) {
1140 n = n->clone();
1141 }
1142 n->set_req(i, value);
1143 register_new_node(n, current_proj);
1144 to_clone.set_node(n);
1145 }
1146 for (;;) {
1147 Node* cur = to_clone.node();
1148 uint j = to_clone.index();
1149 if (j+1 < cur->req()) {
1150 to_clone.set_index(j+1);
1151 break;
1152 }
1153 to_clone.pop();
1154 if (to_clone.size() == 0) {
1155 result = cur;
1156 break;
1157 }
1158 Node* next = to_clone.node();
1159 j = to_clone.index();
1160 if (clone && cur->_idx >= current) {
1161 if (next->_idx < current) {
1162 next = next->clone();
1163 register_new_node(next, current_proj);
1164 to_clone.set_node(next);
1165 }
1166 assert(next->in(j) != cur, "input should have been cloned");
1167 next->set_req(j, cur);
1168 }
1169 }
1170 } while (result == NULL);
1171 if (!clone) {
1172 return NULL;
1173 }
1174 assert(result->_idx >= current, "new node expected");
1175
1176 Node* proj = predicate->clone();
1177 Node* other_proj = uncommon_proj->clone();
1178 Node* new_iff = iff->clone();
1179 new_iff->set_req(1, result);
1180 proj->set_req(0, new_iff);
1181 other_proj->set_req(0, new_iff);
1182 Node *frame = new ParmNode(C->start(), TypeFunc::FramePtr);
1183 register_new_node(frame, C->start());
1184 // It's impossible for the predicate to fail at runtime. Use an Halt node.
1185 Node* halt = new HaltNode(other_proj, frame);
1186 C->root()->add_req(halt);
1187 new_iff->set_req(0, prev_proj);
1188
1189 register_control(new_iff, outer_loop->_parent, prev_proj);
1190 register_control(proj, outer_loop->_parent, new_iff);
1191 register_control(other_proj, _ltree_root, new_iff);
1192 register_control(halt, _ltree_root, other_proj);
1193 return proj;
1194 }
1195
1196 void PhaseIdealLoop::duplicate_predicates(CountedLoopNode* pre_head, Node* castii, IdealLoopTree* outer_loop,
1197 LoopNode* outer_main_head, uint dd_main_head) {
1198 if (UseLoopPredicate) {
1199 Node* entry = pre_head->in(LoopNode::EntryControl);
1200 Node* predicate = NULL;
1201 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
1202 if (predicate != NULL) {
1203 entry = skip_loop_predicates(entry);
1204 }
1205 Node* profile_predicate = NULL;
1206 if (UseProfiledLoopPredicate) {
1207 profile_predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_profile_predicate);
1208 if (profile_predicate != NULL) {
1209 entry = skip_loop_predicates(entry);
1210 }
1211 }
1212 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
1213 duplicate_predicates_helper(predicate, castii, outer_loop, outer_main_head, dd_main_head);
1214 duplicate_predicates_helper(profile_predicate, castii, outer_loop, outer_main_head, dd_main_head);
1215 }
1216 }
1217
1218 //------------------------------insert_pre_post_loops--------------------------
1219 // Insert pre and post loops. If peel_only is set, the pre-loop can not have
1220 // more iterations added. It acts as a 'peel' only, no lower-bound RCE, no
1221 // alignment. Useful to unroll loops that do no array accesses.
1222 void PhaseIdealLoop::insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only ) {
1223
1224 #ifndef PRODUCT
1225 if (TraceLoopOpts) {
1226 if (peel_only)
1227 tty->print("PeelMainPost ");
1228 else
1229 tty->print("PreMainPost ");
1230 loop->dump_head();
1231 }
1232 #endif
1233 C->set_major_progress();
1234
1235 // Find common pieces of the loop being guarded with pre & post loops
1236 CountedLoopNode *main_head = loop->_head->as_CountedLoop();
1237 assert( main_head->is_normal_loop(), "" );
1238 CountedLoopEndNode *main_end = main_head->loopexit();
1239 assert( main_end->outcnt() == 2, "1 true, 1 false path only" );
1240
1241 Node *pre_header= main_head->in(LoopNode::EntryControl);
1242 Node *init = main_head->init_trip();
1243 Node *incr = main_end ->incr();
1244 Node *limit = main_end ->limit();
1245 Node *stride = main_end ->stride();
1246 Node *cmp = main_end ->cmp_node();
1247 BoolTest::mask b_test = main_end->test_trip();
1248
1249 // Need only 1 user of 'bol' because I will be hacking the loop bounds.
1250 Node *bol = main_end->in(CountedLoopEndNode::TestValue);
1251 if( bol->outcnt() != 1 ) {
1252 bol = bol->clone();
1253 register_new_node(bol,main_end->in(CountedLoopEndNode::TestControl));
1254 _igvn.replace_input_of(main_end, CountedLoopEndNode::TestValue, bol);
1255 }
1256 // Need only 1 user of 'cmp' because I will be hacking the loop bounds.
1257 if( cmp->outcnt() != 1 ) {
1258 cmp = cmp->clone();
1259 register_new_node(cmp,main_end->in(CountedLoopEndNode::TestControl));
1260 _igvn.replace_input_of(bol, 1, cmp);
1261 }
1262
1263 // Add the post loop
1264 CountedLoopNode *post_head = NULL;
1265 Node *main_exit = insert_post_loop(loop, old_new, main_head, main_end, incr, limit, post_head);
1266
1267 //------------------------------
1268 // Step B: Create Pre-Loop.
1269
1270 // Step B1: Clone the loop body. The clone becomes the pre-loop. The main
1271 // loop pre-header illegally has 2 control users (old & new loops).
1272 LoopNode* outer_main_head = main_head;
1273 IdealLoopTree* outer_loop = loop;
1274 if (main_head->is_strip_mined()) {
1275 main_head->verify_strip_mined(1);
1276 outer_main_head = main_head->outer_loop();
1277 outer_loop = loop->_parent;
1278 assert(outer_loop->_head == outer_main_head, "broken loop tree");
1279 }
1280 uint dd_main_head = dom_depth(outer_main_head);
1281 clone_loop(loop, old_new, dd_main_head, ControlAroundStripMined);
1282 CountedLoopNode* pre_head = old_new[main_head->_idx]->as_CountedLoop();
1283 CountedLoopEndNode* pre_end = old_new[main_end ->_idx]->as_CountedLoopEnd();
1284 pre_head->set_pre_loop(main_head);
1285 Node *pre_incr = old_new[incr->_idx];
1286
1287 // Reduce the pre-loop trip count.
1288 pre_end->_prob = PROB_FAIR;
1289
1290 // Find the pre-loop normal exit.
1291 Node* pre_exit = pre_end->proj_out(false);
1292 assert( pre_exit->Opcode() == Op_IfFalse, "" );
1293 IfFalseNode *new_pre_exit = new IfFalseNode(pre_end);
1294 _igvn.register_new_node_with_optimizer( new_pre_exit );
1295 set_idom(new_pre_exit, pre_end, dd_main_head);
1296 set_loop(new_pre_exit, outer_loop->_parent);
1297
1298 // Step B2: Build a zero-trip guard for the main-loop. After leaving the
1299 // pre-loop, the main-loop may not execute at all. Later in life this
1300 // zero-trip guard will become the minimum-trip guard when we unroll
1301 // the main-loop.
1302 Node *min_opaq = new Opaque1Node(C, limit);
1303 Node *min_cmp = new CmpINode( pre_incr, min_opaq );
1304 Node *min_bol = new BoolNode( min_cmp, b_test );
1305 register_new_node( min_opaq, new_pre_exit );
1306 register_new_node( min_cmp , new_pre_exit );
1307 register_new_node( min_bol , new_pre_exit );
1308
1309 // Build the IfNode (assume the main-loop is executed always).
1310 IfNode *min_iff = new IfNode( new_pre_exit, min_bol, PROB_ALWAYS, COUNT_UNKNOWN );
1311 _igvn.register_new_node_with_optimizer( min_iff );
1312 set_idom(min_iff, new_pre_exit, dd_main_head);
1313 set_loop(min_iff, outer_loop->_parent);
1314
1315 // Plug in the false-path, taken if we need to skip main-loop
1316 _igvn.hash_delete( pre_exit );
1317 pre_exit->set_req(0, min_iff);
1318 set_idom(pre_exit, min_iff, dd_main_head);
1319 set_idom(pre_exit->unique_ctrl_out(), min_iff, dd_main_head);
1320 // Make the true-path, must enter the main loop
1321 Node *min_taken = new IfTrueNode( min_iff );
1322 _igvn.register_new_node_with_optimizer( min_taken );
1323 set_idom(min_taken, min_iff, dd_main_head);
1324 set_loop(min_taken, outer_loop->_parent);
1325 // Plug in the true path
1326 _igvn.hash_delete(outer_main_head);
1327 outer_main_head->set_req(LoopNode::EntryControl, min_taken);
1328 set_idom(outer_main_head, min_taken, dd_main_head);
1329
1330 Arena *a = Thread::current()->resource_area();
1331 VectorSet visited(a);
1332 Node_Stack clones(a, main_head->back_control()->outcnt());
1333 // Step B3: Make the fall-in values to the main-loop come from the
1334 // fall-out values of the pre-loop.
1335 for (DUIterator_Fast i2max, i2 = main_head->fast_outs(i2max); i2 < i2max; i2++) {
1336 Node* main_phi = main_head->fast_out(i2);
1337 if( main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() > 0 ) {
1338 Node *pre_phi = old_new[main_phi->_idx];
1339 Node *fallpre = clone_up_backedge_goo(pre_head->back_control(),
1340 main_head->skip_strip_mined()->in(LoopNode::EntryControl),
1341 pre_phi->in(LoopNode::LoopBackControl),
1342 visited, clones);
1343 _igvn.hash_delete(main_phi);
1344 main_phi->set_req( LoopNode::EntryControl, fallpre );
1345 }
1346 }
1347
1348 // Nodes inside the loop may be control dependent on a predicate
1349 // that was moved before the preloop. If the back branch of the main
1350 // or post loops becomes dead, those nodes won't be dependent on the
1351 // test that guards that loop nest anymore which could lead to an
1352 // incorrect array access because it executes independently of the
1353 // test that was guarding the loop nest. We add a special CastII on
1354 // the if branch that enters the loop, between the input induction
1355 // variable value and the induction variable Phi to preserve correct
1356 // dependencies.
1357
1358 // CastII for the main loop:
1359 Node* castii = cast_incr_before_loop( pre_incr, min_taken, main_head );
1360 assert(castii != NULL, "no castII inserted");
1361 duplicate_predicates(pre_head, castii, outer_loop, outer_main_head, dd_main_head);
1362
1363 // Step B4: Shorten the pre-loop to run only 1 iteration (for now).
1364 // RCE and alignment may change this later.
1365 Node *cmp_end = pre_end->cmp_node();
1366 assert( cmp_end->in(2) == limit, "" );
1367 Node *pre_limit = new AddINode( init, stride );
1368
1369 // Save the original loop limit in this Opaque1 node for
1370 // use by range check elimination.
1371 Node *pre_opaq = new Opaque1Node(C, pre_limit, limit);
1372
1373 register_new_node( pre_limit, pre_head->in(0) );
1374 register_new_node( pre_opaq , pre_head->in(0) );
1375
1376 // Since no other users of pre-loop compare, I can hack limit directly
1377 assert( cmp_end->outcnt() == 1, "no other users" );
1378 _igvn.hash_delete(cmp_end);
1379 cmp_end->set_req(2, peel_only ? pre_limit : pre_opaq);
1380
1381 // Special case for not-equal loop bounds:
1382 // Change pre loop test, main loop test, and the
1383 // main loop guard test to use lt or gt depending on stride
1384 // direction:
1385 // positive stride use <
1386 // negative stride use >
1387 //
1388 // not-equal test is kept for post loop to handle case
1389 // when init > limit when stride > 0 (and reverse).
1390
1391 if (pre_end->in(CountedLoopEndNode::TestValue)->as_Bool()->_test._test == BoolTest::ne) {
1392
1393 BoolTest::mask new_test = (main_end->stride_con() > 0) ? BoolTest::lt : BoolTest::gt;
1394 // Modify pre loop end condition
1395 Node* pre_bol = pre_end->in(CountedLoopEndNode::TestValue)->as_Bool();
1396 BoolNode* new_bol0 = new BoolNode(pre_bol->in(1), new_test);
1397 register_new_node( new_bol0, pre_head->in(0) );
1398 _igvn.replace_input_of(pre_end, CountedLoopEndNode::TestValue, new_bol0);
1399 // Modify main loop guard condition
1400 assert(min_iff->in(CountedLoopEndNode::TestValue) == min_bol, "guard okay");
1401 BoolNode* new_bol1 = new BoolNode(min_bol->in(1), new_test);
1402 register_new_node( new_bol1, new_pre_exit );
1403 _igvn.hash_delete(min_iff);
1404 min_iff->set_req(CountedLoopEndNode::TestValue, new_bol1);
1405 // Modify main loop end condition
1406 BoolNode* main_bol = main_end->in(CountedLoopEndNode::TestValue)->as_Bool();
1407 BoolNode* new_bol2 = new BoolNode(main_bol->in(1), new_test);
1408 register_new_node( new_bol2, main_end->in(CountedLoopEndNode::TestControl) );
1409 _igvn.replace_input_of(main_end, CountedLoopEndNode::TestValue, new_bol2);
1410 }
1411
1412 // Flag main loop
1413 main_head->set_main_loop();
1414 if( peel_only ) main_head->set_main_no_pre_loop();
1415
1416 // Subtract a trip count for the pre-loop.
1417 main_head->set_trip_count(main_head->trip_count() - 1);
1418
1419 // It's difficult to be precise about the trip-counts
1420 // for the pre/post loops. They are usually very short,
1421 // so guess that 4 trips is a reasonable value.
1422 post_head->set_profile_trip_cnt(4.0);
1423 pre_head->set_profile_trip_cnt(4.0);
1424
1425 // Now force out all loop-invariant dominating tests. The optimizer
1426 // finds some, but we _know_ they are all useless.
1427 peeled_dom_test_elim(loop,old_new);
1428 loop->record_for_igvn();
1429 }
1430
1431 //------------------------------insert_vector_post_loop------------------------
1432 // Insert a copy of the atomic unrolled vectorized main loop as a post loop,
1433 // unroll_policy has already informed us that more unrolling is about to happen to
1434 // the main loop. The resultant post loop will serve as a vectorized drain loop.
1435 void PhaseIdealLoop::insert_vector_post_loop(IdealLoopTree *loop, Node_List &old_new) {
1436 if (!loop->_head->is_CountedLoop()) return;
1437
1438 CountedLoopNode *cl = loop->_head->as_CountedLoop();
1439
1440 // only process vectorized main loops
1441 if (!cl->is_vectorized_loop() || !cl->is_main_loop()) return;
1442
1443 int slp_max_unroll_factor = cl->slp_max_unroll();
1444 int cur_unroll = cl->unrolled_count();
1445
1446 if (slp_max_unroll_factor == 0) return;
1447
1448 // only process atomic unroll vector loops (not super unrolled after vectorization)
1449 if (cur_unroll != slp_max_unroll_factor) return;
1450
1451 // we only ever process this one time
1452 if (cl->has_atomic_post_loop()) return;
1453
1454 #ifndef PRODUCT
1455 if (TraceLoopOpts) {
1456 tty->print("PostVector ");
1457 loop->dump_head();
1458 }
1459 #endif
1460 C->set_major_progress();
1461
1462 // Find common pieces of the loop being guarded with pre & post loops
1463 CountedLoopNode *main_head = loop->_head->as_CountedLoop();
1464 CountedLoopEndNode *main_end = main_head->loopexit();
1465 // diagnostic to show loop end is not properly formed
1466 assert(main_end->outcnt() == 2, "1 true, 1 false path only");
1467
1468 // mark this loop as processed
1469 main_head->mark_has_atomic_post_loop();
1470
1471 Node *incr = main_end->incr();
1472 Node *limit = main_end->limit();
1473
1474 // In this case we throw away the result as we are not using it to connect anything else.
1475 CountedLoopNode *post_head = NULL;
1476 insert_post_loop(loop, old_new, main_head, main_end, incr, limit, post_head);
1477
1478 // It's difficult to be precise about the trip-counts
1479 // for post loops. They are usually very short,
1480 // so guess that unit vector trips is a reasonable value.
1481 post_head->set_profile_trip_cnt(cur_unroll);
1482
1483 // Now force out all loop-invariant dominating tests. The optimizer
1484 // finds some, but we _know_ they are all useless.
1485 peeled_dom_test_elim(loop, old_new);
1486 loop->record_for_igvn();
1487 }
1488
1489
1490 //-------------------------insert_scalar_rced_post_loop------------------------
1491 // Insert a copy of the rce'd main loop as a post loop,
1492 // We have not unrolled the main loop, so this is the right time to inject this.
1493 // Later we will examine the partner of this post loop pair which still has range checks
1494 // to see inject code which tests at runtime if the range checks are applicable.
1495 void PhaseIdealLoop::insert_scalar_rced_post_loop(IdealLoopTree *loop, Node_List &old_new) {
1496 if (!loop->_head->is_CountedLoop()) return;
1497
1498 CountedLoopNode *cl = loop->_head->as_CountedLoop();
1499
1500 // only process RCE'd main loops
1501 if (!cl->is_main_loop() || cl->range_checks_present()) return;
1502
1503 #ifndef PRODUCT
1504 if (TraceLoopOpts) {
1505 tty->print("PostScalarRce ");
1506 loop->dump_head();
1507 }
1508 #endif
1509 C->set_major_progress();
1510
1511 // Find common pieces of the loop being guarded with pre & post loops
1512 CountedLoopNode *main_head = loop->_head->as_CountedLoop();
1513 CountedLoopEndNode *main_end = main_head->loopexit();
1514 // diagnostic to show loop end is not properly formed
1515 assert(main_end->outcnt() == 2, "1 true, 1 false path only");
1516
1517 Node *incr = main_end->incr();
1518 Node *limit = main_end->limit();
1519
1520 // In this case we throw away the result as we are not using it to connect anything else.
1521 CountedLoopNode *post_head = NULL;
1522 insert_post_loop(loop, old_new, main_head, main_end, incr, limit, post_head);
1523
1524 // It's difficult to be precise about the trip-counts
1525 // for post loops. They are usually very short,
1526 // so guess that unit vector trips is a reasonable value.
1527 post_head->set_profile_trip_cnt(4.0);
1528 post_head->set_is_rce_post_loop();
1529
1530 // Now force out all loop-invariant dominating tests. The optimizer
1531 // finds some, but we _know_ they are all useless.
1532 peeled_dom_test_elim(loop, old_new);
1533 loop->record_for_igvn();
1534 }
1535
1536
1537 //------------------------------insert_post_loop-------------------------------
1538 // Insert post loops. Add a post loop to the given loop passed.
1539 Node *PhaseIdealLoop::insert_post_loop(IdealLoopTree *loop, Node_List &old_new,
1540 CountedLoopNode *main_head, CountedLoopEndNode *main_end,
1541 Node *incr, Node *limit, CountedLoopNode *&post_head) {
1542 IfNode* outer_main_end = main_end;
1543 IdealLoopTree* outer_loop = loop;
1544 if (main_head->is_strip_mined()) {
1545 main_head->verify_strip_mined(1);
1546 outer_main_end = main_head->outer_loop_end();
1547 outer_loop = loop->_parent;
1548 assert(outer_loop->_head == main_head->in(LoopNode::EntryControl), "broken loop tree");
1549 }
1550
1551 //------------------------------
1552 // Step A: Create a new post-Loop.
1553 Node* main_exit = outer_main_end->proj_out(false);
1554 assert(main_exit->Opcode() == Op_IfFalse, "");
1555 int dd_main_exit = dom_depth(main_exit);
1556
1557 // Step A1: Clone the loop body of main. The clone becomes the post-loop.
1558 // The main loop pre-header illegally has 2 control users (old & new loops).
1559 clone_loop(loop, old_new, dd_main_exit, ControlAroundStripMined);
1560 assert(old_new[main_end->_idx]->Opcode() == Op_CountedLoopEnd, "");
1561 post_head = old_new[main_head->_idx]->as_CountedLoop();
1562 post_head->set_normal_loop();
1563 post_head->set_post_loop(main_head);
1564
1565 // Reduce the post-loop trip count.
1566 CountedLoopEndNode* post_end = old_new[main_end->_idx]->as_CountedLoopEnd();
1567 post_end->_prob = PROB_FAIR;
1568
1569 // Build the main-loop normal exit.
1570 IfFalseNode *new_main_exit = new IfFalseNode(outer_main_end);
1571 _igvn.register_new_node_with_optimizer(new_main_exit);
1572 set_idom(new_main_exit, outer_main_end, dd_main_exit);
1573 set_loop(new_main_exit, outer_loop->_parent);
1574
1575 // Step A2: Build a zero-trip guard for the post-loop. After leaving the
1576 // main-loop, the post-loop may not execute at all. We 'opaque' the incr
1577 // (the previous loop trip-counter exit value) because we will be changing
1578 // the exit value (via additional unrolling) so we cannot constant-fold away the zero
1579 // trip guard until all unrolling is done.
1580 Node *zer_opaq = new Opaque1Node(C, incr);
1581 Node *zer_cmp = new CmpINode(zer_opaq, limit);
1582 Node *zer_bol = new BoolNode(zer_cmp, main_end->test_trip());
1583 register_new_node(zer_opaq, new_main_exit);
1584 register_new_node(zer_cmp, new_main_exit);
1585 register_new_node(zer_bol, new_main_exit);
1586
1587 // Build the IfNode
1588 IfNode *zer_iff = new IfNode(new_main_exit, zer_bol, PROB_FAIR, COUNT_UNKNOWN);
1589 _igvn.register_new_node_with_optimizer(zer_iff);
1590 set_idom(zer_iff, new_main_exit, dd_main_exit);
1591 set_loop(zer_iff, outer_loop->_parent);
1592
1593 // Plug in the false-path, taken if we need to skip this post-loop
1594 _igvn.replace_input_of(main_exit, 0, zer_iff);
1595 set_idom(main_exit, zer_iff, dd_main_exit);
1596 set_idom(main_exit->unique_out(), zer_iff, dd_main_exit);
1597 // Make the true-path, must enter this post loop
1598 Node *zer_taken = new IfTrueNode(zer_iff);
1599 _igvn.register_new_node_with_optimizer(zer_taken);
1600 set_idom(zer_taken, zer_iff, dd_main_exit);
1601 set_loop(zer_taken, outer_loop->_parent);
1602 // Plug in the true path
1603 _igvn.hash_delete(post_head);
1604 post_head->set_req(LoopNode::EntryControl, zer_taken);
1605 set_idom(post_head, zer_taken, dd_main_exit);
1606
1607 Arena *a = Thread::current()->resource_area();
1608 VectorSet visited(a);
1609 Node_Stack clones(a, main_head->back_control()->outcnt());
1610 // Step A3: Make the fall-in values to the post-loop come from the
1611 // fall-out values of the main-loop.
1612 for (DUIterator_Fast imax, i = main_head->fast_outs(imax); i < imax; i++) {
1613 Node* main_phi = main_head->fast_out(i);
1614 if (main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() >0) {
1615 Node *cur_phi = old_new[main_phi->_idx];
1616 Node *fallnew = clone_up_backedge_goo(main_head->back_control(),
1617 post_head->init_control(),
1618 main_phi->in(LoopNode::LoopBackControl),
1619 visited, clones);
1620 _igvn.hash_delete(cur_phi);
1621 cur_phi->set_req(LoopNode::EntryControl, fallnew);
1622 }
1623 }
1624
1625 // CastII for the new post loop:
1626 Node* castii = cast_incr_before_loop(zer_opaq->in(1), zer_taken, post_head);
1627 assert(castii != NULL, "no castII inserted");
1628
1629 return new_main_exit;
1630 }
1631
1632 //------------------------------is_invariant-----------------------------
1633 // Return true if n is invariant
1634 bool IdealLoopTree::is_invariant(Node* n) const {
1635 Node *n_c = _phase->has_ctrl(n) ? _phase->get_ctrl(n) : n;
1636 if (n_c->is_top()) return false;
1637 return !is_member(_phase->get_loop(n_c));
1638 }
1639
1640
1641 //------------------------------do_unroll--------------------------------------
1642 // Unroll the loop body one step - make each trip do 2 iterations.
1643 void PhaseIdealLoop::do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip ) {
1644 assert(LoopUnrollLimit, "");
1645 CountedLoopNode *loop_head = loop->_head->as_CountedLoop();
1646 CountedLoopEndNode *loop_end = loop_head->loopexit();
1647 #ifndef PRODUCT
1648 if (PrintOpto && VerifyLoopOptimizations) {
1649 tty->print("Unrolling ");
1650 loop->dump_head();
1651 } else if (TraceLoopOpts) {
1652 if (loop_head->trip_count() < (uint)LoopUnrollLimit) {
1653 tty->print("Unroll %d(%2d) ", loop_head->unrolled_count()*2, loop_head->trip_count());
1654 } else {
1655 tty->print("Unroll %d ", loop_head->unrolled_count()*2);
1656 }
1657 loop->dump_head();
1658 }
1659
1660 if (C->do_vector_loop() && (PrintOpto && (VerifyLoopOptimizations || TraceLoopOpts))) {
1661 Arena* arena = Thread::current()->resource_area();
1662 Node_Stack stack(arena, C->live_nodes() >> 2);
1663 Node_List rpo_list;
1664 VectorSet visited(arena);
1665 visited.set(loop_head->_idx);
1666 rpo( loop_head, stack, visited, rpo_list );
1667 dump(loop, rpo_list.size(), rpo_list );
1668 }
1669 #endif
1670
1671 // Remember loop node count before unrolling to detect
1672 // if rounds of unroll,optimize are making progress
1673 loop_head->set_node_count_before_unroll(loop->_body.size());
1674
1675 Node *ctrl = loop_head->skip_strip_mined()->in(LoopNode::EntryControl);
1676 Node *limit = loop_head->limit();
1677 Node *init = loop_head->init_trip();
1678 Node *stride = loop_head->stride();
1679
1680 Node *opaq = NULL;
1681 if (adjust_min_trip) { // If not maximally unrolling, need adjustment
1682 // Search for zero-trip guard.
1683
1684 // Check the shape of the graph at the loop entry. If an inappropriate
1685 // graph shape is encountered, the compiler bails out loop unrolling;
1686 // compilation of the method will still succeed.
1687 if (!is_canonical_loop_entry(loop_head)) {
1688 return;
1689 }
1690 opaq = loop_head->skip_predicates()->in(0)->in(1)->in(1)->in(2);
1691 // Zero-trip test uses an 'opaque' node which is not shared.
1692 assert(opaq->outcnt() == 1 && opaq->in(1) == limit, "");
1693 }
1694
1695 C->set_major_progress();
1696
1697 Node* new_limit = NULL;
1698 int stride_con = stride->get_int();
1699 int stride_p = (stride_con > 0) ? stride_con : -stride_con;
1700 uint old_trip_count = loop_head->trip_count();
1701 // Verify that unroll policy result is still valid.
1702 assert(old_trip_count > 1 &&
1703 (!adjust_min_trip || stride_p <= (1<<3)*loop_head->unrolled_count()), "sanity");
1704
1705 if (UseLoopPredicate) {
1706 // Search for skeleton predicates and update them according to the new stride
1707 Node* entry = ctrl;
1708 while (entry != NULL && entry->is_Proj() && entry->in(0)->is_If()) {
1709 IfNode* iff = entry->in(0)->as_If();
1710 ProjNode* proj = iff->proj_out(1 - entry->as_Proj()->_con);
1711 if (proj->unique_ctrl_out()->Opcode() != Op_Halt) {
1712 break;
1713 }
1714 if (iff->in(1)->Opcode() == Op_Opaque4) {
1715 // Compute the value of the loop induction variable at the end of the
1716 // first iteration of the unrolled loop: init + new_stride_con - init_inc
1717 int init_inc = stride_con/loop_head->unrolled_count();
1718 assert(init_inc != 0, "invalid loop increment");
1719 int new_stride_con = stride_con * 2;
1720 Node* max_value = _igvn.intcon(new_stride_con - init_inc);
1721 max_value = new AddINode(init, max_value);
1722 register_new_node(max_value, get_ctrl(iff->in(1)));
1723 update_skeleton_predicate(iff, max_value);
1724 }
1725 entry = entry->in(0)->in(0);
1726 }
1727 }
1728
1729 // Adjust loop limit to keep valid iterations number after unroll.
1730 // Use (limit - stride) instead of (((limit - init)/stride) & (-2))*stride
1731 // which may overflow.
1732 if (!adjust_min_trip) {
1733 assert(old_trip_count > 1 && (old_trip_count & 1) == 0,
1734 "odd trip count for maximally unroll");
1735 // Don't need to adjust limit for maximally unroll since trip count is even.
1736 } else if (loop_head->has_exact_trip_count() && init->is_Con()) {
1737 // Loop's limit is constant. Loop's init could be constant when pre-loop
1738 // become peeled iteration.
1739 jlong init_con = init->get_int();
1740 // We can keep old loop limit if iterations count stays the same:
1741 // old_trip_count == new_trip_count * 2
1742 // Note: since old_trip_count >= 2 then new_trip_count >= 1
1743 // so we also don't need to adjust zero trip test.
1744 jlong limit_con = limit->get_int();
1745 // (stride_con*2) not overflow since stride_con <= 8.
1746 int new_stride_con = stride_con * 2;
1747 int stride_m = new_stride_con - (stride_con > 0 ? 1 : -1);
1748 jlong trip_count = (limit_con - init_con + stride_m)/new_stride_con;
1749 // New trip count should satisfy next conditions.
1750 assert(trip_count > 0 && (julong)trip_count < (julong)max_juint/2, "sanity");
1751 uint new_trip_count = (uint)trip_count;
1752 adjust_min_trip = (old_trip_count != new_trip_count*2);
1753 }
1754
1755 if (adjust_min_trip) {
1756 // Step 2: Adjust the trip limit if it is called for.
1757 // The adjustment amount is -stride. Need to make sure if the
1758 // adjustment underflows or overflows, then the main loop is skipped.
1759 Node* cmp = loop_end->cmp_node();
1760 assert(cmp->in(2) == limit, "sanity");
1761 assert(opaq != NULL && opaq->in(1) == limit, "sanity");
1762
1763 // Verify that policy_unroll result is still valid.
1764 const TypeInt* limit_type = _igvn.type(limit)->is_int();
1765 assert(stride_con > 0 && ((limit_type->_hi - stride_con) < limit_type->_hi) ||
1766 stride_con < 0 && ((limit_type->_lo - stride_con) > limit_type->_lo), "sanity");
1767
1768 if (limit->is_Con()) {
1769 // The check in policy_unroll and the assert above guarantee
1770 // no underflow if limit is constant.
1771 new_limit = _igvn.intcon(limit->get_int() - stride_con);
1772 set_ctrl(new_limit, C->root());
1773 } else {
1774 // Limit is not constant.
1775 if (loop_head->unrolled_count() == 1) { // only for first unroll
1776 // Separate limit by Opaque node in case it is an incremented
1777 // variable from previous loop to avoid using pre-incremented
1778 // value which could increase register pressure.
1779 // Otherwise reorg_offsets() optimization will create a separate
1780 // Opaque node for each use of trip-counter and as result
1781 // zero trip guard limit will be different from loop limit.
1782 assert(has_ctrl(opaq), "should have it");
1783 Node* opaq_ctrl = get_ctrl(opaq);
1784 limit = new Opaque2Node( C, limit );
1785 register_new_node( limit, opaq_ctrl );
1786 }
1787 if ((stride_con > 0 && (java_subtract(limit_type->_lo, stride_con) < limit_type->_lo)) ||
1788 (stride_con < 0 && (java_subtract(limit_type->_hi, stride_con) > limit_type->_hi))) {
1789 // No underflow.
1790 new_limit = new SubINode(limit, stride);
1791 } else {
1792 // (limit - stride) may underflow.
1793 // Clamp the adjustment value with MININT or MAXINT:
1794 //
1795 // new_limit = limit-stride
1796 // if (stride > 0)
1797 // new_limit = (limit < new_limit) ? MININT : new_limit;
1798 // else
1799 // new_limit = (limit > new_limit) ? MAXINT : new_limit;
1800 //
1801 BoolTest::mask bt = loop_end->test_trip();
1802 assert(bt == BoolTest::lt || bt == BoolTest::gt, "canonical test is expected");
1803 Node* adj_max = _igvn.intcon((stride_con > 0) ? min_jint : max_jint);
1804 set_ctrl(adj_max, C->root());
1805 Node* old_limit = NULL;
1806 Node* adj_limit = NULL;
1807 Node* bol = limit->is_CMove() ? limit->in(CMoveNode::Condition) : NULL;
1808 if (loop_head->unrolled_count() > 1 &&
1809 limit->is_CMove() && limit->Opcode() == Op_CMoveI &&
1810 limit->in(CMoveNode::IfTrue) == adj_max &&
1811 bol->as_Bool()->_test._test == bt &&
1812 bol->in(1)->Opcode() == Op_CmpI &&
1813 bol->in(1)->in(2) == limit->in(CMoveNode::IfFalse)) {
1814 // Loop was unrolled before.
1815 // Optimize the limit to avoid nested CMove:
1816 // use original limit as old limit.
1817 old_limit = bol->in(1)->in(1);
1818 // Adjust previous adjusted limit.
1819 adj_limit = limit->in(CMoveNode::IfFalse);
1820 adj_limit = new SubINode(adj_limit, stride);
1821 } else {
1822 old_limit = limit;
1823 adj_limit = new SubINode(limit, stride);
1824 }
1825 assert(old_limit != NULL && adj_limit != NULL, "");
1826 register_new_node( adj_limit, ctrl ); // adjust amount
1827 Node* adj_cmp = new CmpINode(old_limit, adj_limit);
1828 register_new_node( adj_cmp, ctrl );
1829 Node* adj_bool = new BoolNode(adj_cmp, bt);
1830 register_new_node( adj_bool, ctrl );
1831 new_limit = new CMoveINode(adj_bool, adj_limit, adj_max, TypeInt::INT);
1832 }
1833 register_new_node(new_limit, ctrl);
1834 }
1835 assert(new_limit != NULL, "");
1836 // Replace in loop test.
1837 assert(loop_end->in(1)->in(1) == cmp, "sanity");
1838 if (cmp->outcnt() == 1 && loop_end->in(1)->outcnt() == 1) {
1839 // Don't need to create new test since only one user.
1840 _igvn.hash_delete(cmp);
1841 cmp->set_req(2, new_limit);
1842 } else {
1843 // Create new test since it is shared.
1844 Node* ctrl2 = loop_end->in(0);
1845 Node* cmp2 = cmp->clone();
1846 cmp2->set_req(2, new_limit);
1847 register_new_node(cmp2, ctrl2);
1848 Node* bol2 = loop_end->in(1)->clone();
1849 bol2->set_req(1, cmp2);
1850 register_new_node(bol2, ctrl2);
1851 _igvn.replace_input_of(loop_end, 1, bol2);
1852 }
1853 // Step 3: Find the min-trip test guaranteed before a 'main' loop.
1854 // Make it a 1-trip test (means at least 2 trips).
1855
1856 // Guard test uses an 'opaque' node which is not shared. Hence I
1857 // can edit it's inputs directly. Hammer in the new limit for the
1858 // minimum-trip guard.
1859 assert(opaq->outcnt() == 1, "");
1860 _igvn.replace_input_of(opaq, 1, new_limit);
1861 }
1862
1863 // Adjust max trip count. The trip count is intentionally rounded
1864 // down here (e.g. 15-> 7-> 3-> 1) because if we unwittingly over-unroll,
1865 // the main, unrolled, part of the loop will never execute as it is protected
1866 // by the min-trip test. See bug 4834191 for a case where we over-unrolled
1867 // and later determined that part of the unrolled loop was dead.
1868 loop_head->set_trip_count(old_trip_count / 2);
1869
1870 // Double the count of original iterations in the unrolled loop body.
1871 loop_head->double_unrolled_count();
1872
1873 // ---------
1874 // Step 4: Clone the loop body. Move it inside the loop. This loop body
1875 // represents the odd iterations; since the loop trips an even number of
1876 // times its backedge is never taken. Kill the backedge.
1877 uint dd = dom_depth(loop_head);
1878 clone_loop(loop, old_new, dd, IgnoreStripMined);
1879
1880 // Make backedges of the clone equal to backedges of the original.
1881 // Make the fall-in from the original come from the fall-out of the clone.
1882 for (DUIterator_Fast jmax, j = loop_head->fast_outs(jmax); j < jmax; j++) {
1883 Node* phi = loop_head->fast_out(j);
1884 if( phi->is_Phi() && phi->in(0) == loop_head && phi->outcnt() > 0 ) {
1885 Node *newphi = old_new[phi->_idx];
1886 _igvn.hash_delete( phi );
1887 _igvn.hash_delete( newphi );
1888
1889 phi ->set_req(LoopNode:: EntryControl, newphi->in(LoopNode::LoopBackControl));
1890 newphi->set_req(LoopNode::LoopBackControl, phi ->in(LoopNode::LoopBackControl));
1891 phi ->set_req(LoopNode::LoopBackControl, C->top());
1892 }
1893 }
1894 Node *clone_head = old_new[loop_head->_idx];
1895 _igvn.hash_delete( clone_head );
1896 loop_head ->set_req(LoopNode:: EntryControl, clone_head->in(LoopNode::LoopBackControl));
1897 clone_head->set_req(LoopNode::LoopBackControl, loop_head ->in(LoopNode::LoopBackControl));
1898 loop_head ->set_req(LoopNode::LoopBackControl, C->top());
1899 loop->_head = clone_head; // New loop header
1900
1901 set_idom(loop_head, loop_head ->in(LoopNode::EntryControl), dd);
1902 set_idom(clone_head, clone_head->in(LoopNode::EntryControl), dd);
1903
1904 // Kill the clone's backedge
1905 Node *newcle = old_new[loop_end->_idx];
1906 _igvn.hash_delete( newcle );
1907 Node *one = _igvn.intcon(1);
1908 set_ctrl(one, C->root());
1909 newcle->set_req(1, one);
1910 // Force clone into same loop body
1911 uint max = loop->_body.size();
1912 for( uint k = 0; k < max; k++ ) {
1913 Node *old = loop->_body.at(k);
1914 Node *nnn = old_new[old->_idx];
1915 loop->_body.push(nnn);
1916 if (!has_ctrl(old))
1917 set_loop(nnn, loop);
1918 }
1919
1920 loop->record_for_igvn();
1921 loop_head->clear_strip_mined();
1922
1923 #ifndef PRODUCT
1924 if (C->do_vector_loop() && (PrintOpto && (VerifyLoopOptimizations || TraceLoopOpts))) {
1925 tty->print("\nnew loop after unroll\n"); loop->dump_head();
1926 for (uint i = 0; i < loop->_body.size(); i++) {
1927 loop->_body.at(i)->dump();
1928 }
1929 if(C->clone_map().is_debug()) {
1930 tty->print("\nCloneMap\n");
1931 Dict* dict = C->clone_map().dict();
1932 DictI i(dict);
1933 tty->print_cr("Dict@%p[%d] = ", dict, dict->Size());
1934 for (int ii = 0; i.test(); ++i, ++ii) {
1935 NodeCloneInfo cl((uint64_t)dict->operator[]((void*)i._key));
1936 tty->print("%d->%d:%d,", (int)(intptr_t)i._key, cl.idx(), cl.gen());
1937 if (ii % 10 == 9) {
1938 tty->print_cr(" ");
1939 }
1940 }
1941 tty->print_cr(" ");
1942 }
1943 }
1944 #endif
1945
1946 }
1947
1948 //------------------------------do_maximally_unroll----------------------------
1949
1950 void PhaseIdealLoop::do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new ) {
1951 CountedLoopNode *cl = loop->_head->as_CountedLoop();
1952 assert(cl->has_exact_trip_count(), "trip count is not exact");
1953 assert(cl->trip_count() > 0, "");
1954 #ifndef PRODUCT
1955 if (TraceLoopOpts) {
1956 tty->print("MaxUnroll %d ", cl->trip_count());
1957 loop->dump_head();
1958 }
1959 #endif
1960
1961 // If loop is tripping an odd number of times, peel odd iteration
1962 if ((cl->trip_count() & 1) == 1) {
1963 do_peeling(loop, old_new);
1964 }
1965
1966 // Now its tripping an even number of times remaining. Double loop body.
1967 // Do not adjust pre-guards; they are not needed and do not exist.
1968 if (cl->trip_count() > 0) {
1969 assert((cl->trip_count() & 1) == 0, "missed peeling");
1970 do_unroll(loop, old_new, false);
1971 }
1972 }
1973
1974 void PhaseIdealLoop::mark_reductions(IdealLoopTree *loop) {
1975 if (SuperWordReductions == false) return;
1976
1977 CountedLoopNode* loop_head = loop->_head->as_CountedLoop();
1978 if (loop_head->unrolled_count() > 1) {
1979 return;
1980 }
1981
1982 Node* trip_phi = loop_head->phi();
1983 for (DUIterator_Fast imax, i = loop_head->fast_outs(imax); i < imax; i++) {
1984 Node* phi = loop_head->fast_out(i);
1985 if (phi->is_Phi() && phi->outcnt() > 0 && phi != trip_phi) {
1986 // For definitions which are loop inclusive and not tripcounts.
1987 Node* def_node = phi->in(LoopNode::LoopBackControl);
1988
1989 if (def_node != NULL) {
1990 Node* n_ctrl = get_ctrl(def_node);
1991 if (n_ctrl != NULL && loop->is_member(get_loop(n_ctrl))) {
1992 // Now test it to see if it fits the standard pattern for a reduction operator.
1993 int opc = def_node->Opcode();
1994 if (opc != ReductionNode::opcode(opc, def_node->bottom_type()->basic_type())) {
1995 if (!def_node->is_reduction()) { // Not marked yet
1996 // To be a reduction, the arithmetic node must have the phi as input and provide a def to it
1997 bool ok = false;
1998 for (unsigned j = 1; j < def_node->req(); j++) {
1999 Node* in = def_node->in(j);
2000 if (in == phi) {
2001 ok = true;
2002 break;
2003 }
2004 }
2005
2006 // do nothing if we did not match the initial criteria
2007 if (ok == false) {
2008 continue;
2009 }
2010
2011 // The result of the reduction must not be used in the loop
2012 for (DUIterator_Fast imax, i = def_node->fast_outs(imax); i < imax && ok; i++) {
2013 Node* u = def_node->fast_out(i);
2014 if (!loop->is_member(get_loop(ctrl_or_self(u)))) {
2015 continue;
2016 }
2017 if (u == phi) {
2018 continue;
2019 }
2020 ok = false;
2021 }
2022
2023 // iff the uses conform
2024 if (ok) {
2025 def_node->add_flag(Node::Flag_is_reduction);
2026 loop_head->mark_has_reductions();
2027 }
2028 }
2029 }
2030 }
2031 }
2032 }
2033 }
2034 }
2035
2036 //------------------------------adjust_limit-----------------------------------
2037 // Helper function for add_constraint().
2038 Node* PhaseIdealLoop::adjust_limit(int stride_con, Node * scale, Node *offset, Node *rc_limit, Node *loop_limit, Node *pre_ctrl) {
2039 // Compute "I :: (limit-offset)/scale"
2040 Node *con = new SubINode(rc_limit, offset);
2041 register_new_node(con, pre_ctrl);
2042 Node *X = new DivINode(0, con, scale);
2043 register_new_node(X, pre_ctrl);
2044
2045 // Adjust loop limit
2046 loop_limit = (stride_con > 0)
2047 ? (Node*)(new MinINode(loop_limit, X))
2048 : (Node*)(new MaxINode(loop_limit, X));
2049 register_new_node(loop_limit, pre_ctrl);
2050 return loop_limit;
2051 }
2052
2053 //------------------------------add_constraint---------------------------------
2054 // Constrain the main loop iterations so the conditions:
2055 // low_limit <= scale_con * I + offset < upper_limit
2056 // always holds true. That is, either increase the number of iterations in
2057 // the pre-loop or the post-loop until the condition holds true in the main
2058 // loop. Stride, scale, offset and limit are all loop invariant. Further,
2059 // stride and scale are constants (offset and limit often are).
2060 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 ) {
2061 // For positive stride, the pre-loop limit always uses a MAX function
2062 // and the main loop a MIN function. For negative stride these are
2063 // reversed.
2064
2065 // Also for positive stride*scale the affine function is increasing, so the
2066 // pre-loop must check for underflow and the post-loop for overflow.
2067 // Negative stride*scale reverses this; pre-loop checks for overflow and
2068 // post-loop for underflow.
2069
2070 Node *scale = _igvn.intcon(scale_con);
2071 set_ctrl(scale, C->root());
2072
2073 if ((stride_con^scale_con) >= 0) { // Use XOR to avoid overflow
2074 // The overflow limit: scale*I+offset < upper_limit
2075 // For main-loop compute
2076 // ( if (scale > 0) /* and stride > 0 */
2077 // I < (upper_limit-offset)/scale
2078 // else /* scale < 0 and stride < 0 */
2079 // I > (upper_limit-offset)/scale
2080 // )
2081 //
2082 // (upper_limit-offset) may overflow or underflow.
2083 // But it is fine since main loop will either have
2084 // less iterations or will be skipped in such case.
2085 *main_limit = adjust_limit(stride_con, scale, offset, upper_limit, *main_limit, pre_ctrl);
2086
2087 // The underflow limit: low_limit <= scale*I+offset.
2088 // For pre-loop compute
2089 // NOT(scale*I+offset >= low_limit)
2090 // scale*I+offset < low_limit
2091 // ( if (scale > 0) /* and stride > 0 */
2092 // I < (low_limit-offset)/scale
2093 // else /* scale < 0 and stride < 0 */
2094 // I > (low_limit-offset)/scale
2095 // )
2096
2097 if (low_limit->get_int() == -max_jint) {
2098 // We need this guard when scale*pre_limit+offset >= limit
2099 // due to underflow. So we need execute pre-loop until
2100 // scale*I+offset >= min_int. But (min_int-offset) will
2101 // underflow when offset > 0 and X will be > original_limit
2102 // when stride > 0. To avoid it we replace positive offset with 0.
2103 //
2104 // Also (min_int+1 == -max_int) is used instead of min_int here
2105 // to avoid problem with scale == -1 (min_int/(-1) == min_int).
2106 Node* shift = _igvn.intcon(31);
2107 set_ctrl(shift, C->root());
2108 Node* sign = new RShiftINode(offset, shift);
2109 register_new_node(sign, pre_ctrl);
2110 offset = new AndINode(offset, sign);
2111 register_new_node(offset, pre_ctrl);
2112 } else {
2113 assert(low_limit->get_int() == 0, "wrong low limit for range check");
2114 // The only problem we have here when offset == min_int
2115 // since (0-min_int) == min_int. It may be fine for stride > 0
2116 // but for stride < 0 X will be < original_limit. To avoid it
2117 // max(pre_limit, original_limit) is used in do_range_check().
2118 }
2119 // Pass (-stride) to indicate pre_loop_cond = NOT(main_loop_cond);
2120 *pre_limit = adjust_limit((-stride_con), scale, offset, low_limit, *pre_limit, pre_ctrl);
2121
2122 } else { // stride_con*scale_con < 0
2123 // For negative stride*scale pre-loop checks for overflow and
2124 // post-loop for underflow.
2125 //
2126 // The overflow limit: scale*I+offset < upper_limit
2127 // For pre-loop compute
2128 // NOT(scale*I+offset < upper_limit)
2129 // scale*I+offset >= upper_limit
2130 // scale*I+offset+1 > upper_limit
2131 // ( if (scale < 0) /* and stride > 0 */
2132 // I < (upper_limit-(offset+1))/scale
2133 // else /* scale > 0 and stride < 0 */
2134 // I > (upper_limit-(offset+1))/scale
2135 // )
2136 //
2137 // (upper_limit-offset-1) may underflow or overflow.
2138 // To avoid it min(pre_limit, original_limit) is used
2139 // in do_range_check() for stride > 0 and max() for < 0.
2140 Node *one = _igvn.intcon(1);
2141 set_ctrl(one, C->root());
2142
2143 Node *plus_one = new AddINode(offset, one);
2144 register_new_node( plus_one, pre_ctrl );
2145 // Pass (-stride) to indicate pre_loop_cond = NOT(main_loop_cond);
2146 *pre_limit = adjust_limit((-stride_con), scale, plus_one, upper_limit, *pre_limit, pre_ctrl);
2147
2148 if (low_limit->get_int() == -max_jint) {
2149 // We need this guard when scale*main_limit+offset >= limit
2150 // due to underflow. So we need execute main-loop while
2151 // scale*I+offset+1 > min_int. But (min_int-offset-1) will
2152 // underflow when (offset+1) > 0 and X will be < main_limit
2153 // when scale < 0 (and stride > 0). To avoid it we replace
2154 // positive (offset+1) with 0.
2155 //
2156 // Also (min_int+1 == -max_int) is used instead of min_int here
2157 // to avoid problem with scale == -1 (min_int/(-1) == min_int).
2158 Node* shift = _igvn.intcon(31);
2159 set_ctrl(shift, C->root());
2160 Node* sign = new RShiftINode(plus_one, shift);
2161 register_new_node(sign, pre_ctrl);
2162 plus_one = new AndINode(plus_one, sign);
2163 register_new_node(plus_one, pre_ctrl);
2164 } else {
2165 assert(low_limit->get_int() == 0, "wrong low limit for range check");
2166 // The only problem we have here when offset == max_int
2167 // since (max_int+1) == min_int and (0-min_int) == min_int.
2168 // But it is fine since main loop will either have
2169 // less iterations or will be skipped in such case.
2170 }
2171 // The underflow limit: low_limit <= scale*I+offset.
2172 // For main-loop compute
2173 // scale*I+offset+1 > low_limit
2174 // ( if (scale < 0) /* and stride > 0 */
2175 // I < (low_limit-(offset+1))/scale
2176 // else /* scale > 0 and stride < 0 */
2177 // I > (low_limit-(offset+1))/scale
2178 // )
2179
2180 *main_limit = adjust_limit(stride_con, scale, plus_one, low_limit, *main_limit, pre_ctrl);
2181 }
2182 }
2183
2184
2185 //------------------------------is_scaled_iv---------------------------------
2186 // Return true if exp is a constant times an induction var
2187 bool PhaseIdealLoop::is_scaled_iv(Node* exp, Node* iv, int* p_scale) {
2188 if (exp == iv) {
2189 if (p_scale != NULL) {
2190 *p_scale = 1;
2191 }
2192 return true;
2193 }
2194 int opc = exp->Opcode();
2195 if (opc == Op_MulI) {
2196 if (exp->in(1) == iv && exp->in(2)->is_Con()) {
2197 if (p_scale != NULL) {
2198 *p_scale = exp->in(2)->get_int();
2199 }
2200 return true;
2201 }
2202 if (exp->in(2) == iv && exp->in(1)->is_Con()) {
2203 if (p_scale != NULL) {
2204 *p_scale = exp->in(1)->get_int();
2205 }
2206 return true;
2207 }
2208 } else if (opc == Op_LShiftI) {
2209 if (exp->in(1) == iv && exp->in(2)->is_Con()) {
2210 if (p_scale != NULL) {
2211 *p_scale = 1 << exp->in(2)->get_int();
2212 }
2213 return true;
2214 }
2215 }
2216 return false;
2217 }
2218
2219 //-----------------------------is_scaled_iv_plus_offset------------------------------
2220 // Return true if exp is a simple induction variable expression: k1*iv + (invar + k2)
2221 bool PhaseIdealLoop::is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth) {
2222 if (is_scaled_iv(exp, iv, p_scale)) {
2223 if (p_offset != NULL) {
2224 Node *zero = _igvn.intcon(0);
2225 set_ctrl(zero, C->root());
2226 *p_offset = zero;
2227 }
2228 return true;
2229 }
2230 int opc = exp->Opcode();
2231 if (opc == Op_AddI) {
2232 if (is_scaled_iv(exp->in(1), iv, p_scale)) {
2233 if (p_offset != NULL) {
2234 *p_offset = exp->in(2);
2235 }
2236 return true;
2237 }
2238 if (is_scaled_iv(exp->in(2), iv, p_scale)) {
2239 if (p_offset != NULL) {
2240 *p_offset = exp->in(1);
2241 }
2242 return true;
2243 }
2244 if (exp->in(2)->is_Con()) {
2245 Node* offset2 = NULL;
2246 if (depth < 2 &&
2247 is_scaled_iv_plus_offset(exp->in(1), iv, p_scale,
2248 p_offset != NULL ? &offset2 : NULL, depth+1)) {
2249 if (p_offset != NULL) {
2250 Node *ctrl_off2 = get_ctrl(offset2);
2251 Node* offset = new AddINode(offset2, exp->in(2));
2252 register_new_node(offset, ctrl_off2);
2253 *p_offset = offset;
2254 }
2255 return true;
2256 }
2257 }
2258 } else if (opc == Op_SubI) {
2259 if (is_scaled_iv(exp->in(1), iv, p_scale)) {
2260 if (p_offset != NULL) {
2261 Node *zero = _igvn.intcon(0);
2262 set_ctrl(zero, C->root());
2263 Node *ctrl_off = get_ctrl(exp->in(2));
2264 Node* offset = new SubINode(zero, exp->in(2));
2265 register_new_node(offset, ctrl_off);
2266 *p_offset = offset;
2267 }
2268 return true;
2269 }
2270 if (is_scaled_iv(exp->in(2), iv, p_scale)) {
2271 if (p_offset != NULL) {
2272 *p_scale *= -1;
2273 *p_offset = exp->in(1);
2274 }
2275 return true;
2276 }
2277 }
2278 return false;
2279 }
2280
2281 // Same as PhaseIdealLoop::duplicate_predicates() but for range checks
2282 // eliminated by iteration splitting.
2283 Node* PhaseIdealLoop::add_range_check_predicate(IdealLoopTree* loop, CountedLoopNode* cl,
2284 Node* predicate_proj, int scale_con, Node* offset,
2285 Node* limit, jint stride_con) {
2286 bool overflow = false;
2287 BoolNode* bol = rc_predicate(loop, predicate_proj, scale_con, offset, cl->init_trip(), NULL, stride_con, limit, (stride_con > 0) != (scale_con > 0), overflow);
2288 Node* opaque_bol = new Opaque4Node(C, bol, _igvn.intcon(1));
2289 register_new_node(opaque_bol, predicate_proj);
2290 IfNode* new_iff = NULL;
2291 if (overflow) {
2292 new_iff = new IfNode(predicate_proj, bol, PROB_MAX, COUNT_UNKNOWN);
2293 } else {
2294 new_iff = new RangeCheckNode(predicate_proj, bol, PROB_MAX, COUNT_UNKNOWN);
2295 }
2296 register_control(new_iff, loop->_parent, predicate_proj);
2297 Node* iffalse = new IfFalseNode(new_iff);
2298 register_control(iffalse, _ltree_root, new_iff);
2299 ProjNode* iftrue = new IfTrueNode(new_iff);
2300 register_control(iftrue, loop->_parent, new_iff);
2301 Node *frame = new ParmNode(C->start(), TypeFunc::FramePtr);
2302 register_new_node(frame, C->start());
2303 Node* halt = new HaltNode(iffalse, frame);
2304 register_control(halt, _ltree_root, iffalse);
2305 C->root()->add_req(halt);
2306 return iftrue;
2307 }
2308
2309 //------------------------------do_range_check---------------------------------
2310 // Eliminate range-checks and other trip-counter vs loop-invariant tests.
2311 int PhaseIdealLoop::do_range_check( IdealLoopTree *loop, Node_List &old_new ) {
2312 #ifndef PRODUCT
2313 if (PrintOpto && VerifyLoopOptimizations) {
2314 tty->print("Range Check Elimination ");
2315 loop->dump_head();
2316 } else if (TraceLoopOpts) {
2317 tty->print("RangeCheck ");
2318 loop->dump_head();
2319 }
2320 #endif
2321 assert(RangeCheckElimination, "");
2322 CountedLoopNode *cl = loop->_head->as_CountedLoop();
2323 // If we fail before trying to eliminate range checks, set multiversion state
2324 int closed_range_checks = 1;
2325
2326 // protect against stride not being a constant
2327 if (!cl->stride_is_con())
2328 return closed_range_checks;
2329
2330 // Find the trip counter; we are iteration splitting based on it
2331 Node *trip_counter = cl->phi();
2332 // Find the main loop limit; we will trim it's iterations
2333 // to not ever trip end tests
2334 Node *main_limit = cl->limit();
2335
2336 // Check graph shape. Cannot optimize a loop if zero-trip
2337 // Opaque1 node is optimized away and then another round
2338 // of loop opts attempted.
2339 if (!is_canonical_loop_entry(cl)) {
2340 return closed_range_checks;
2341 }
2342
2343 // Need to find the main-loop zero-trip guard
2344 Node *ctrl = cl->skip_predicates();
2345 Node *iffm = ctrl->in(0);
2346 Node *opqzm = iffm->in(1)->in(1)->in(2);
2347 assert(opqzm->in(1) == main_limit, "do not understand situation");
2348
2349 // Find the pre-loop limit; we will expand its iterations to
2350 // not ever trip low tests.
2351 Node *p_f = iffm->in(0);
2352 // pre loop may have been optimized out
2353 if (p_f->Opcode() != Op_IfFalse) {
2354 return closed_range_checks;
2355 }
2356 CountedLoopEndNode *pre_end = p_f->in(0)->as_CountedLoopEnd();
2357 assert(pre_end->loopnode()->is_pre_loop(), "");
2358 Node *pre_opaq1 = pre_end->limit();
2359 // Occasionally it's possible for a pre-loop Opaque1 node to be
2360 // optimized away and then another round of loop opts attempted.
2361 // We can not optimize this particular loop in that case.
2362 if (pre_opaq1->Opcode() != Op_Opaque1)
2363 return closed_range_checks;
2364 Opaque1Node *pre_opaq = (Opaque1Node*)pre_opaq1;
2365 Node *pre_limit = pre_opaq->in(1);
2366
2367 // Where do we put new limit calculations
2368 Node *pre_ctrl = pre_end->loopnode()->in(LoopNode::EntryControl);
2369
2370 // Ensure the original loop limit is available from the
2371 // pre-loop Opaque1 node.
2372 Node *orig_limit = pre_opaq->original_loop_limit();
2373 if (orig_limit == NULL || _igvn.type(orig_limit) == Type::TOP)
2374 return closed_range_checks;
2375
2376 // Must know if its a count-up or count-down loop
2377
2378 int stride_con = cl->stride_con();
2379 Node *zero = _igvn.intcon(0);
2380 Node *one = _igvn.intcon(1);
2381 // Use symmetrical int range [-max_jint,max_jint]
2382 Node *mini = _igvn.intcon(-max_jint);
2383 set_ctrl(zero, C->root());
2384 set_ctrl(one, C->root());
2385 set_ctrl(mini, C->root());
2386
2387 // Range checks that do not dominate the loop backedge (ie.
2388 // conditionally executed) can lengthen the pre loop limit beyond
2389 // the original loop limit. To prevent this, the pre limit is
2390 // (for stride > 0) MINed with the original loop limit (MAXed
2391 // stride < 0) when some range_check (rc) is conditionally
2392 // executed.
2393 bool conditional_rc = false;
2394
2395 // Count number of range checks and reduce by load range limits, if zero,
2396 // the loop is in canonical form to multiversion.
2397 closed_range_checks = 0;
2398
2399 Node* predicate_proj = cl->skip_strip_mined()->in(LoopNode::EntryControl);
2400 assert(predicate_proj->is_Proj() && predicate_proj->in(0)->is_If(), "if projection only");
2401 // Check loop body for tests of trip-counter plus loop-invariant vs loop-variant.
2402 for( uint i = 0; i < loop->_body.size(); i++ ) {
2403 Node *iff = loop->_body[i];
2404 if (iff->Opcode() == Op_If ||
2405 iff->Opcode() == Op_RangeCheck) { // Test?
2406 // Test is an IfNode, has 2 projections. If BOTH are in the loop
2407 // we need loop unswitching instead of iteration splitting.
2408 closed_range_checks++;
2409 Node *exit = loop->is_loop_exit(iff);
2410 if( !exit ) continue;
2411 int flip = (exit->Opcode() == Op_IfTrue) ? 1 : 0;
2412
2413 // Get boolean condition to test
2414 Node *i1 = iff->in(1);
2415 if( !i1->is_Bool() ) continue;
2416 BoolNode *bol = i1->as_Bool();
2417 BoolTest b_test = bol->_test;
2418 // Flip sense of test if exit condition is flipped
2419 if( flip )
2420 b_test = b_test.negate();
2421
2422 // Get compare
2423 Node *cmp = bol->in(1);
2424
2425 // Look for trip_counter + offset vs limit
2426 Node *rc_exp = cmp->in(1);
2427 Node *limit = cmp->in(2);
2428 int scale_con= 1; // Assume trip counter not scaled
2429
2430 Node *limit_c = get_ctrl(limit);
2431 if( loop->is_member(get_loop(limit_c) ) ) {
2432 // Compare might have operands swapped; commute them
2433 b_test = b_test.commute();
2434 rc_exp = cmp->in(2);
2435 limit = cmp->in(1);
2436 limit_c = get_ctrl(limit);
2437 if( loop->is_member(get_loop(limit_c) ) )
2438 continue; // Both inputs are loop varying; cannot RCE
2439 }
2440 // Here we know 'limit' is loop invariant
2441
2442 // 'limit' maybe pinned below the zero trip test (probably from a
2443 // previous round of rce), in which case, it can't be used in the
2444 // zero trip test expression which must occur before the zero test's if.
2445 if (is_dominator(ctrl, limit_c)) {
2446 continue; // Don't rce this check but continue looking for other candidates.
2447 }
2448
2449 // Check for scaled induction variable plus an offset
2450 Node *offset = NULL;
2451
2452 if (!is_scaled_iv_plus_offset(rc_exp, trip_counter, &scale_con, &offset)) {
2453 continue;
2454 }
2455
2456 Node *offset_c = get_ctrl(offset);
2457 if( loop->is_member( get_loop(offset_c) ) )
2458 continue; // Offset is not really loop invariant
2459 // Here we know 'offset' is loop invariant.
2460
2461 // As above for the 'limit', the 'offset' maybe pinned below the
2462 // zero trip test.
2463 if (is_dominator(ctrl, offset_c)) {
2464 continue; // Don't rce this check but continue looking for other candidates.
2465 }
2466 #ifdef ASSERT
2467 if (TraceRangeLimitCheck) {
2468 tty->print_cr("RC bool node%s", flip ? " flipped:" : ":");
2469 bol->dump(2);
2470 }
2471 #endif
2472 // At this point we have the expression as:
2473 // scale_con * trip_counter + offset :: limit
2474 // where scale_con, offset and limit are loop invariant. Trip_counter
2475 // monotonically increases by stride_con, a constant. Both (or either)
2476 // stride_con and scale_con can be negative which will flip about the
2477 // sense of the test.
2478
2479 // Adjust pre and main loop limits to guard the correct iteration set
2480 if( cmp->Opcode() == Op_CmpU ) {// Unsigned compare is really 2 tests
2481 if( b_test._test == BoolTest::lt ) { // Range checks always use lt
2482 // The underflow and overflow limits: 0 <= scale*I+offset < limit
2483 add_constraint( stride_con, scale_con, offset, zero, limit, pre_ctrl, &pre_limit, &main_limit );
2484 // (0-offset)/scale could be outside of loop iterations range.
2485 conditional_rc = true;
2486 predicate_proj = add_range_check_predicate(loop, cl, predicate_proj, scale_con, offset, limit, stride_con);
2487 } else {
2488 if (PrintOpto) {
2489 tty->print_cr("missed RCE opportunity");
2490 }
2491 continue; // In release mode, ignore it
2492 }
2493 } else { // Otherwise work on normal compares
2494 switch( b_test._test ) {
2495 case BoolTest::gt:
2496 // Fall into GE case
2497 case BoolTest::ge:
2498 // Convert (I*scale+offset) >= Limit to (I*(-scale)+(-offset)) <= -Limit
2499 scale_con = -scale_con;
2500 offset = new SubINode( zero, offset );
2501 register_new_node( offset, pre_ctrl );
2502 limit = new SubINode( zero, limit );
2503 register_new_node( limit, pre_ctrl );
2504 // Fall into LE case
2505 case BoolTest::le:
2506 if (b_test._test != BoolTest::gt) {
2507 // Convert X <= Y to X < Y+1
2508 limit = new AddINode( limit, one );
2509 register_new_node( limit, pre_ctrl );
2510 }
2511 // Fall into LT case
2512 case BoolTest::lt:
2513 // The underflow and overflow limits: MIN_INT <= scale*I+offset < limit
2514 // Note: (MIN_INT+1 == -MAX_INT) is used instead of MIN_INT here
2515 // to avoid problem with scale == -1: MIN_INT/(-1) == MIN_INT.
2516 add_constraint( stride_con, scale_con, offset, mini, limit, pre_ctrl, &pre_limit, &main_limit );
2517 // ((MIN_INT+1)-offset)/scale could be outside of loop iterations range.
2518 // Note: negative offset is replaced with 0 but (MIN_INT+1)/scale could
2519 // still be outside of loop range.
2520 conditional_rc = true;
2521 break;
2522 default:
2523 if (PrintOpto) {
2524 tty->print_cr("missed RCE opportunity");
2525 }
2526 continue; // Unhandled case
2527 }
2528 }
2529
2530 // Kill the eliminated test
2531 C->set_major_progress();
2532 Node *kill_con = _igvn.intcon( 1-flip );
2533 set_ctrl(kill_con, C->root());
2534 _igvn.replace_input_of(iff, 1, kill_con);
2535 // Find surviving projection
2536 assert(iff->is_If(), "");
2537 ProjNode* dp = ((IfNode*)iff)->proj_out(1-flip);
2538 // Find loads off the surviving projection; remove their control edge
2539 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
2540 Node* cd = dp->fast_out(i); // Control-dependent node
2541 if (cd->is_Load() && cd->depends_only_on_test()) { // Loads can now float around in the loop
2542 // Allow the load to float around in the loop, or before it
2543 // but NOT before the pre-loop.
2544 _igvn.replace_input_of(cd, 0, ctrl); // ctrl, not NULL
2545 --i;
2546 --imax;
2547 }
2548 }
2549 if (limit->Opcode() == Op_LoadRange) {
2550 closed_range_checks--;
2551 }
2552
2553 } // End of is IF
2554
2555 }
2556 if (predicate_proj != cl->skip_strip_mined()->in(LoopNode::EntryControl)) {
2557 _igvn.replace_input_of(cl->skip_strip_mined(), LoopNode::EntryControl, predicate_proj);
2558 set_idom(cl->skip_strip_mined(), predicate_proj, dom_depth(cl->skip_strip_mined()));
2559 }
2560
2561 // Update loop limits
2562 if (conditional_rc) {
2563 pre_limit = (stride_con > 0) ? (Node*)new MinINode(pre_limit, orig_limit)
2564 : (Node*)new MaxINode(pre_limit, orig_limit);
2565 register_new_node(pre_limit, pre_ctrl);
2566 }
2567 _igvn.replace_input_of(pre_opaq, 1, pre_limit);
2568
2569 // Note:: we are making the main loop limit no longer precise;
2570 // need to round up based on stride.
2571 cl->set_nonexact_trip_count();
2572 Node *main_cle = cl->loopexit();
2573 Node *main_bol = main_cle->in(1);
2574 // Hacking loop bounds; need private copies of exit test
2575 if( main_bol->outcnt() > 1 ) {// BoolNode shared?
2576 main_bol = main_bol->clone();// Clone a private BoolNode
2577 register_new_node( main_bol, main_cle->in(0) );
2578 _igvn.replace_input_of(main_cle, 1, main_bol);
2579 }
2580 Node *main_cmp = main_bol->in(1);
2581 if( main_cmp->outcnt() > 1 ) { // CmpNode shared?
2582 main_cmp = main_cmp->clone();// Clone a private CmpNode
2583 register_new_node( main_cmp, main_cle->in(0) );
2584 _igvn.replace_input_of(main_bol, 1, main_cmp);
2585 }
2586 // Hack the now-private loop bounds
2587 _igvn.replace_input_of(main_cmp, 2, main_limit);
2588 // The OpaqueNode is unshared by design
2589 assert( opqzm->outcnt() == 1, "cannot hack shared node" );
2590 _igvn.replace_input_of(opqzm, 1, main_limit);
2591
2592 return closed_range_checks;
2593 }
2594
2595 //------------------------------has_range_checks-------------------------------
2596 // Check to see if RCE cleaned the current loop of range-checks.
2597 void PhaseIdealLoop::has_range_checks(IdealLoopTree *loop) {
2598 assert(RangeCheckElimination, "");
2599
2600 // skip if not a counted loop
2601 if (!loop->is_counted()) return;
2602
2603 CountedLoopNode *cl = loop->_head->as_CountedLoop();
2604
2605 // skip this loop if it is already checked
2606 if (cl->has_been_range_checked()) return;
2607
2608 // Now check for existence of range checks
2609 for (uint i = 0; i < loop->_body.size(); i++) {
2610 Node *iff = loop->_body[i];
2611 int iff_opc = iff->Opcode();
2612 if (iff_opc == Op_If || iff_opc == Op_RangeCheck) {
2613 cl->mark_has_range_checks();
2614 break;
2615 }
2616 }
2617 cl->set_has_been_range_checked();
2618 }
2619
2620 //-------------------------multi_version_post_loops----------------------------
2621 // Check the range checks that remain, if simple, use the bounds to guard
2622 // which version to a post loop we execute, one with range checks or one without
2623 bool PhaseIdealLoop::multi_version_post_loops(IdealLoopTree *rce_loop, IdealLoopTree *legacy_loop) {
2624 bool multi_version_succeeded = false;
2625 assert(RangeCheckElimination, "");
2626 CountedLoopNode *legacy_cl = legacy_loop->_head->as_CountedLoop();
2627 assert(legacy_cl->is_post_loop(), "");
2628
2629 // Check for existence of range checks using the unique instance to make a guard with
2630 Unique_Node_List worklist;
2631 for (uint i = 0; i < legacy_loop->_body.size(); i++) {
2632 Node *iff = legacy_loop->_body[i];
2633 int iff_opc = iff->Opcode();
2634 if (iff_opc == Op_If || iff_opc == Op_RangeCheck) {
2635 worklist.push(iff);
2636 }
2637 }
2638
2639 // Find RCE'd post loop so that we can stage its guard.
2640 if (!is_canonical_loop_entry(legacy_cl)) return multi_version_succeeded;
2641 Node* ctrl = legacy_cl->in(LoopNode::EntryControl);
2642 Node* iffm = ctrl->in(0);
2643
2644 // Now we test that both the post loops are connected
2645 Node* post_loop_region = iffm->in(0);
2646 if (post_loop_region == NULL) return multi_version_succeeded;
2647 if (!post_loop_region->is_Region()) return multi_version_succeeded;
2648 Node* covering_region = post_loop_region->in(RegionNode::Control+1);
2649 if (covering_region == NULL) return multi_version_succeeded;
2650 if (!covering_region->is_Region()) return multi_version_succeeded;
2651 Node* p_f = covering_region->in(RegionNode::Control);
2652 if (p_f == NULL) return multi_version_succeeded;
2653 if (!p_f->is_IfFalse()) return multi_version_succeeded;
2654 if (!p_f->in(0)->is_CountedLoopEnd()) return multi_version_succeeded;
2655 CountedLoopEndNode* rce_loop_end = p_f->in(0)->as_CountedLoopEnd();
2656 if (rce_loop_end == NULL) return multi_version_succeeded;
2657 CountedLoopNode* rce_cl = rce_loop_end->loopnode();
2658 if (rce_cl == NULL || !rce_cl->is_post_loop()) return multi_version_succeeded;
2659 CountedLoopNode *known_rce_cl = rce_loop->_head->as_CountedLoop();
2660 if (rce_cl != known_rce_cl) return multi_version_succeeded;
2661
2662 // Then we fetch the cover entry test
2663 ctrl = rce_cl->in(LoopNode::EntryControl);
2664 if (!ctrl->is_IfTrue() && !ctrl->is_IfFalse()) return multi_version_succeeded;
2665
2666 #ifndef PRODUCT
2667 if (TraceLoopOpts) {
2668 tty->print("PostMultiVersion\n");
2669 rce_loop->dump_head();
2670 legacy_loop->dump_head();
2671 }
2672 #endif
2673
2674 // Now fetch the limit we want to compare against
2675 Node *limit = rce_cl->limit();
2676 bool first_time = true;
2677
2678 // If we got this far, we identified the post loop which has been RCE'd and
2679 // we have a work list. Now we will try to transform the if guard to cause
2680 // the loop pair to be multi version executed with the determination left to runtime
2681 // or the optimizer if full information is known about the given arrays at compile time.
2682 Node *last_min = NULL;
2683 multi_version_succeeded = true;
2684 while (worklist.size()) {
2685 Node* rc_iffm = worklist.pop();
2686 if (rc_iffm->is_If()) {
2687 Node *rc_bolzm = rc_iffm->in(1);
2688 if (rc_bolzm->is_Bool()) {
2689 Node *rc_cmpzm = rc_bolzm->in(1);
2690 if (rc_cmpzm->is_Cmp()) {
2691 Node *rc_left = rc_cmpzm->in(2);
2692 if (rc_left->Opcode() != Op_LoadRange) {
2693 multi_version_succeeded = false;
2694 break;
2695 }
2696 if (first_time) {
2697 last_min = rc_left;
2698 first_time = false;
2699 } else {
2700 Node *cur_min = new MinINode(last_min, rc_left);
2701 last_min = cur_min;
2702 _igvn.register_new_node_with_optimizer(last_min);
2703 }
2704 }
2705 }
2706 }
2707 }
2708
2709 // All we have to do is update the limit of the rce loop
2710 // with the min of our expression and the current limit.
2711 // We will use this expression to replace the current limit.
2712 if (last_min && multi_version_succeeded) {
2713 Node *cur_min = new MinINode(last_min, limit);
2714 _igvn.register_new_node_with_optimizer(cur_min);
2715 Node *cmp_node = rce_loop_end->cmp_node();
2716 _igvn.replace_input_of(cmp_node, 2, cur_min);
2717 set_ctrl(cur_min, ctrl);
2718 set_loop(cur_min, rce_loop->_parent);
2719
2720 legacy_cl->mark_is_multiversioned();
2721 rce_cl->mark_is_multiversioned();
2722 multi_version_succeeded = true;
2723
2724 C->set_major_progress();
2725 }
2726
2727 return multi_version_succeeded;
2728 }
2729
2730 //-------------------------poison_rce_post_loop--------------------------------
2731 // Causes the rce'd post loop to be optimized away if multiversioning fails
2732 void PhaseIdealLoop::poison_rce_post_loop(IdealLoopTree *rce_loop) {
2733 CountedLoopNode *rce_cl = rce_loop->_head->as_CountedLoop();
2734 Node* ctrl = rce_cl->in(LoopNode::EntryControl);
2735 if (ctrl->is_IfTrue() || ctrl->is_IfFalse()) {
2736 Node* iffm = ctrl->in(0);
2737 if (iffm->is_If()) {
2738 Node* cur_bool = iffm->in(1);
2739 if (cur_bool->is_Bool()) {
2740 Node* cur_cmp = cur_bool->in(1);
2741 if (cur_cmp->is_Cmp()) {
2742 BoolTest::mask new_test = BoolTest::gt;
2743 BoolNode *new_bool = new BoolNode(cur_cmp, new_test);
2744 _igvn.replace_node(cur_bool, new_bool);
2745 _igvn._worklist.push(new_bool);
2746 Node* left_op = cur_cmp->in(1);
2747 _igvn.replace_input_of(cur_cmp, 2, left_op);
2748 C->set_major_progress();
2749 }
2750 }
2751 }
2752 }
2753 }
2754
2755 //------------------------------DCE_loop_body----------------------------------
2756 // Remove simplistic dead code from loop body
2757 void IdealLoopTree::DCE_loop_body() {
2758 for( uint i = 0; i < _body.size(); i++ )
2759 if( _body.at(i)->outcnt() == 0 )
2760 _body.map( i--, _body.pop() );
2761 }
2762
2763
2764 //------------------------------adjust_loop_exit_prob--------------------------
2765 // Look for loop-exit tests with the 50/50 (or worse) guesses from the parsing stage.
2766 // Replace with a 1-in-10 exit guess.
2767 void IdealLoopTree::adjust_loop_exit_prob( PhaseIdealLoop *phase ) {
2768 Node *test = tail();
2769 while( test != _head ) {
2770 uint top = test->Opcode();
2771 if( top == Op_IfTrue || top == Op_IfFalse ) {
2772 int test_con = ((ProjNode*)test)->_con;
2773 assert(top == (uint)(test_con? Op_IfTrue: Op_IfFalse), "sanity");
2774 IfNode *iff = test->in(0)->as_If();
2775 if( iff->outcnt() == 2 ) { // Ignore dead tests
2776 Node *bol = iff->in(1);
2777 if( bol && bol->req() > 1 && bol->in(1) &&
2778 ((bol->in(1)->Opcode() == Op_StorePConditional ) ||
2779 (bol->in(1)->Opcode() == Op_StoreIConditional ) ||
2780 (bol->in(1)->Opcode() == Op_StoreLConditional ) ||
2781 (bol->in(1)->Opcode() == Op_CompareAndExchangeB ) ||
2782 (bol->in(1)->Opcode() == Op_CompareAndExchangeS ) ||
2783 (bol->in(1)->Opcode() == Op_CompareAndExchangeI ) ||
2784 (bol->in(1)->Opcode() == Op_CompareAndExchangeL ) ||
2785 (bol->in(1)->Opcode() == Op_CompareAndExchangeP ) ||
2786 (bol->in(1)->Opcode() == Op_CompareAndExchangeN ) ||
2787 (bol->in(1)->Opcode() == Op_WeakCompareAndSwapB ) ||
2788 (bol->in(1)->Opcode() == Op_WeakCompareAndSwapS ) ||
2789 (bol->in(1)->Opcode() == Op_WeakCompareAndSwapI ) ||
2790 (bol->in(1)->Opcode() == Op_WeakCompareAndSwapL ) ||
2791 (bol->in(1)->Opcode() == Op_WeakCompareAndSwapP ) ||
2792 (bol->in(1)->Opcode() == Op_WeakCompareAndSwapN ) ||
2793 (bol->in(1)->Opcode() == Op_CompareAndSwapB ) ||
2794 (bol->in(1)->Opcode() == Op_CompareAndSwapS ) ||
2795 (bol->in(1)->Opcode() == Op_CompareAndSwapI ) ||
2796 (bol->in(1)->Opcode() == Op_CompareAndSwapL ) ||
2797 (bol->in(1)->Opcode() == Op_CompareAndSwapP ) ||
2798 (bol->in(1)->Opcode() == Op_CompareAndSwapN )))
2799 return; // Allocation loops RARELY take backedge
2800 // Find the OTHER exit path from the IF
2801 Node* ex = iff->proj_out(1-test_con);
2802 float p = iff->_prob;
2803 if( !phase->is_member( this, ex ) && iff->_fcnt == COUNT_UNKNOWN ) {
2804 if( top == Op_IfTrue ) {
2805 if( p < (PROB_FAIR + PROB_UNLIKELY_MAG(3))) {
2806 iff->_prob = PROB_STATIC_FREQUENT;
2807 }
2808 } else {
2809 if( p > (PROB_FAIR - PROB_UNLIKELY_MAG(3))) {
2810 iff->_prob = PROB_STATIC_INFREQUENT;
2811 }
2812 }
2813 }
2814 }
2815 }
2816 test = phase->idom(test);
2817 }
2818 }
2819
2820 #ifdef ASSERT
2821 static CountedLoopNode* locate_pre_from_main(CountedLoopNode *cl) {
2822 Node *ctrl = cl->skip_predicates();
2823 assert(ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "");
2824 Node *iffm = ctrl->in(0);
2825 assert(iffm->Opcode() == Op_If, "");
2826 Node *p_f = iffm->in(0);
2827 assert(p_f->Opcode() == Op_IfFalse, "");
2828 CountedLoopEndNode *pre_end = p_f->in(0)->as_CountedLoopEnd();
2829 assert(pre_end->loopnode()->is_pre_loop(), "");
2830 return pre_end->loopnode();
2831 }
2832 #endif
2833
2834 // Remove the main and post loops and make the pre loop execute all
2835 // iterations. Useful when the pre loop is found empty.
2836 void IdealLoopTree::remove_main_post_loops(CountedLoopNode *cl, PhaseIdealLoop *phase) {
2837 CountedLoopEndNode* pre_end = cl->loopexit();
2838 Node* pre_cmp = pre_end->cmp_node();
2839 if (pre_cmp->in(2)->Opcode() != Op_Opaque1) {
2840 // Only safe to remove the main loop if the compiler optimized it
2841 // out based on an unknown number of iterations
2842 return;
2843 }
2844
2845 // Can we find the main loop?
2846 if (_next == NULL) {
2847 return;
2848 }
2849
2850 Node* next_head = _next->_head;
2851 if (!next_head->is_CountedLoop()) {
2852 return;
2853 }
2854
2855 CountedLoopNode* main_head = next_head->as_CountedLoop();
2856 if (!main_head->is_main_loop()) {
2857 return;
2858 }
2859
2860 assert(locate_pre_from_main(main_head) == cl, "bad main loop");
2861 Node* main_iff = main_head->skip_predicates()->in(0);
2862
2863 // Remove the Opaque1Node of the pre loop and make it execute all iterations
2864 phase->_igvn.replace_input_of(pre_cmp, 2, pre_cmp->in(2)->in(2));
2865 // Remove the Opaque1Node of the main loop so it can be optimized out
2866 Node* main_cmp = main_iff->in(1)->in(1);
2867 assert(main_cmp->in(2)->Opcode() == Op_Opaque1, "main loop has no opaque node?");
2868 phase->_igvn.replace_input_of(main_cmp, 2, main_cmp->in(2)->in(1));
2869 }
2870
2871 //------------------------------policy_do_remove_empty_loop--------------------
2872 // Micro-benchmark spamming. Policy is to always remove empty loops.
2873 // The 'DO' part is to replace the trip counter with the value it will
2874 // have on the last iteration. This will break the loop.
2875 bool IdealLoopTree::policy_do_remove_empty_loop( PhaseIdealLoop *phase ) {
2876 // Minimum size must be empty loop
2877 if (_body.size() > EMPTY_LOOP_SIZE)
2878 return false;
2879
2880 if (!_head->is_CountedLoop())
2881 return false; // Dead loop
2882 CountedLoopNode *cl = _head->as_CountedLoop();
2883 if (!cl->is_valid_counted_loop())
2884 return false; // Malformed loop
2885 if (!phase->is_member(this, phase->get_ctrl(cl->loopexit()->in(CountedLoopEndNode::TestValue))))
2886 return false; // Infinite loop
2887
2888 if (cl->is_pre_loop()) {
2889 // If the loop we are removing is a pre-loop then the main and
2890 // post loop can be removed as well
2891 remove_main_post_loops(cl, phase);
2892 }
2893
2894 #ifdef ASSERT
2895 // Ensure only one phi which is the iv.
2896 Node* iv = NULL;
2897 for (DUIterator_Fast imax, i = cl->fast_outs(imax); i < imax; i++) {
2898 Node* n = cl->fast_out(i);
2899 if (n->Opcode() == Op_Phi) {
2900 assert(iv == NULL, "Too many phis" );
2901 iv = n;
2902 }
2903 }
2904 assert(iv == cl->phi(), "Wrong phi" );
2905 #endif
2906
2907 // main and post loops have explicitly created zero trip guard
2908 bool needs_guard = !cl->is_main_loop() && !cl->is_post_loop();
2909 if (needs_guard) {
2910 // Skip guard if values not overlap.
2911 const TypeInt* init_t = phase->_igvn.type(cl->init_trip())->is_int();
2912 const TypeInt* limit_t = phase->_igvn.type(cl->limit())->is_int();
2913 int stride_con = cl->stride_con();
2914 if (stride_con > 0) {
2915 needs_guard = (init_t->_hi >= limit_t->_lo);
2916 } else {
2917 needs_guard = (init_t->_lo <= limit_t->_hi);
2918 }
2919 }
2920 if (needs_guard) {
2921 // Check for an obvious zero trip guard.
2922 Node* inctrl = PhaseIdealLoop::skip_all_loop_predicates(cl->skip_predicates());
2923 if (inctrl->Opcode() == Op_IfTrue || inctrl->Opcode() == Op_IfFalse) {
2924 bool maybe_swapped = (inctrl->Opcode() == Op_IfFalse);
2925 // The test should look like just the backedge of a CountedLoop
2926 Node* iff = inctrl->in(0);
2927 if (iff->is_If()) {
2928 Node* bol = iff->in(1);
2929 if (bol->is_Bool()) {
2930 BoolTest test = bol->as_Bool()->_test;
2931 if (maybe_swapped) {
2932 test._test = test.commute();
2933 test._test = test.negate();
2934 }
2935 if (test._test == cl->loopexit()->test_trip()) {
2936 Node* cmp = bol->in(1);
2937 int init_idx = maybe_swapped ? 2 : 1;
2938 int limit_idx = maybe_swapped ? 1 : 2;
2939 if (cmp->is_Cmp() && cmp->in(init_idx) == cl->init_trip() && cmp->in(limit_idx) == cl->limit()) {
2940 needs_guard = false;
2941 }
2942 }
2943 }
2944 }
2945 }
2946 }
2947
2948 #ifndef PRODUCT
2949 if (PrintOpto) {
2950 tty->print("Removing empty loop with%s zero trip guard", needs_guard ? "out" : "");
2951 this->dump_head();
2952 } else if (TraceLoopOpts) {
2953 tty->print("Empty with%s zero trip guard ", needs_guard ? "out" : "");
2954 this->dump_head();
2955 }
2956 #endif
2957
2958 if (needs_guard) {
2959 // Peel the loop to ensure there's a zero trip guard
2960 Node_List old_new;
2961 phase->do_peeling(this, old_new);
2962 }
2963
2964 // Replace the phi at loop head with the final value of the last
2965 // iteration. Then the CountedLoopEnd will collapse (backedge never
2966 // taken) and all loop-invariant uses of the exit values will be correct.
2967 Node *phi = cl->phi();
2968 Node *exact_limit = phase->exact_limit(this);
2969 if (exact_limit != cl->limit()) {
2970 // We also need to replace the original limit to collapse loop exit.
2971 Node* cmp = cl->loopexit()->cmp_node();
2972 assert(cl->limit() == cmp->in(2), "sanity");
2973 phase->_igvn._worklist.push(cmp->in(2)); // put limit on worklist
2974 phase->_igvn.replace_input_of(cmp, 2, exact_limit); // put cmp on worklist
2975 }
2976 // Note: the final value after increment should not overflow since
2977 // counted loop has limit check predicate.
2978 Node *final = new SubINode( exact_limit, cl->stride() );
2979 phase->register_new_node(final,cl->in(LoopNode::EntryControl));
2980 phase->_igvn.replace_node(phi,final);
2981 phase->C->set_major_progress();
2982 return true;
2983 }
2984
2985 //------------------------------policy_do_one_iteration_loop-------------------
2986 // Convert one iteration loop into normal code.
2987 bool IdealLoopTree::policy_do_one_iteration_loop( PhaseIdealLoop *phase ) {
2988 if (!_head->as_Loop()->is_valid_counted_loop())
2989 return false; // Only for counted loop
2990
2991 CountedLoopNode *cl = _head->as_CountedLoop();
2992 if (!cl->has_exact_trip_count() || cl->trip_count() != 1) {
2993 return false;
2994 }
2995
2996 #ifndef PRODUCT
2997 if(TraceLoopOpts) {
2998 tty->print("OneIteration ");
2999 this->dump_head();
3000 }
3001 #endif
3002
3003 Node *init_n = cl->init_trip();
3004 #ifdef ASSERT
3005 // Loop boundaries should be constant since trip count is exact.
3006 assert(init_n->get_int() + cl->stride_con() >= cl->limit()->get_int(), "should be one iteration");
3007 #endif
3008 // Replace the phi at loop head with the value of the init_trip.
3009 // Then the CountedLoopEnd will collapse (backedge will not be taken)
3010 // and all loop-invariant uses of the exit values will be correct.
3011 phase->_igvn.replace_node(cl->phi(), cl->init_trip());
3012 phase->C->set_major_progress();
3013 return true;
3014 }
3015
3016 //=============================================================================
3017 //------------------------------iteration_split_impl---------------------------
3018 bool IdealLoopTree::iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new ) {
3019 // Compute loop trip count if possible.
3020 compute_trip_count(phase);
3021
3022 // Convert one iteration loop into normal code.
3023 if (policy_do_one_iteration_loop(phase))
3024 return true;
3025
3026 // Check and remove empty loops (spam micro-benchmarks)
3027 if (policy_do_remove_empty_loop(phase))
3028 return true; // Here we removed an empty loop
3029
3030 bool should_peel = policy_peeling(phase); // Should we peel?
3031
3032 bool should_unswitch = policy_unswitching(phase);
3033
3034 // Non-counted loops may be peeled; exactly 1 iteration is peeled.
3035 // This removes loop-invariant tests (usually null checks).
3036 if (!_head->is_CountedLoop()) { // Non-counted loop
3037 if (PartialPeelLoop && phase->partial_peel(this, old_new)) {
3038 // Partial peel succeeded so terminate this round of loop opts
3039 return false;
3040 }
3041 if (should_peel) { // Should we peel?
3042 if (PrintOpto) { tty->print_cr("should_peel"); }
3043 phase->do_peeling(this,old_new);
3044 } else if (should_unswitch) {
3045 phase->do_unswitching(this, old_new);
3046 }
3047 return true;
3048 }
3049 CountedLoopNode *cl = _head->as_CountedLoop();
3050
3051 if (!cl->is_valid_counted_loop()) return true; // Ignore various kinds of broken loops
3052
3053 // Do nothing special to pre- and post- loops
3054 if (cl->is_pre_loop() || cl->is_post_loop()) return true;
3055
3056 // Compute loop trip count from profile data
3057 compute_profile_trip_cnt(phase);
3058
3059 // Before attempting fancy unrolling, RCE or alignment, see if we want
3060 // to completely unroll this loop or do loop unswitching.
3061 if (cl->is_normal_loop()) {
3062 if (should_unswitch) {
3063 phase->do_unswitching(this, old_new);
3064 return true;
3065 }
3066 bool should_maximally_unroll = policy_maximally_unroll(phase);
3067 if (should_maximally_unroll) {
3068 // Here we did some unrolling and peeling. Eventually we will
3069 // completely unroll this loop and it will no longer be a loop.
3070 phase->do_maximally_unroll(this,old_new);
3071 return true;
3072 }
3073 }
3074
3075 // Skip next optimizations if running low on nodes. Note that
3076 // policy_unswitching and policy_maximally_unroll have this check.
3077 int nodes_left = phase->C->max_node_limit() - phase->C->live_nodes();
3078 if ((int)(2 * _body.size()) > nodes_left) {
3079 return true;
3080 }
3081
3082 // Counted loops may be peeled, may need some iterations run up
3083 // front for RCE, and may want to align loop refs to a cache
3084 // line. Thus we clone a full loop up front whose trip count is
3085 // at least 1 (if peeling), but may be several more.
3086
3087 // The main loop will start cache-line aligned with at least 1
3088 // iteration of the unrolled body (zero-trip test required) and
3089 // will have some range checks removed.
3090
3091 // A post-loop will finish any odd iterations (leftover after
3092 // unrolling), plus any needed for RCE purposes.
3093
3094 bool should_unroll = policy_unroll(phase);
3095
3096 bool should_rce = policy_range_check(phase);
3097
3098 bool should_align = policy_align(phase);
3099
3100 // If not RCE'ing (iteration splitting) or Aligning, then we do not
3101 // need a pre-loop. We may still need to peel an initial iteration but
3102 // we will not be needing an unknown number of pre-iterations.
3103 //
3104 // Basically, if may_rce_align reports FALSE first time through,
3105 // we will not be able to later do RCE or Aligning on this loop.
3106 bool may_rce_align = !policy_peel_only(phase) || should_rce || should_align;
3107
3108 // If we have any of these conditions (RCE, alignment, unrolling) met, then
3109 // we switch to the pre-/main-/post-loop model. This model also covers
3110 // peeling.
3111 if (should_rce || should_align || should_unroll) {
3112 if (cl->is_normal_loop()) // Convert to 'pre/main/post' loops
3113 phase->insert_pre_post_loops(this,old_new, !may_rce_align);
3114
3115 // Adjust the pre- and main-loop limits to let the pre and post loops run
3116 // with full checks, but the main-loop with no checks. Remove said
3117 // checks from the main body.
3118 if (should_rce) {
3119 if (phase->do_range_check(this, old_new) != 0) {
3120 cl->mark_has_range_checks();
3121 }
3122 } else if (PostLoopMultiversioning) {
3123 phase->has_range_checks(this);
3124 }
3125
3126 if (should_unroll && !should_peel && PostLoopMultiversioning) {
3127 // Try to setup multiversioning on main loops before they are unrolled
3128 if (cl->is_main_loop() && (cl->unrolled_count() == 1)) {
3129 phase->insert_scalar_rced_post_loop(this, old_new);
3130 }
3131 }
3132
3133 // Double loop body for unrolling. Adjust the minimum-trip test (will do
3134 // twice as many iterations as before) and the main body limit (only do
3135 // an even number of trips). If we are peeling, we might enable some RCE
3136 // and we'd rather unroll the post-RCE'd loop SO... do not unroll if
3137 // peeling.
3138 if (should_unroll && !should_peel) {
3139 if (SuperWordLoopUnrollAnalysis) {
3140 phase->insert_vector_post_loop(this, old_new);
3141 }
3142 phase->do_unroll(this, old_new, true);
3143 }
3144
3145 // Adjust the pre-loop limits to align the main body
3146 // iterations.
3147 if (should_align)
3148 Unimplemented();
3149
3150 } else { // Else we have an unchanged counted loop
3151 if (should_peel) // Might want to peel but do nothing else
3152 phase->do_peeling(this,old_new);
3153 }
3154 return true;
3155 }
3156
3157
3158 //=============================================================================
3159 //------------------------------iteration_split--------------------------------
3160 bool IdealLoopTree::iteration_split( PhaseIdealLoop *phase, Node_List &old_new ) {
3161 // Recursively iteration split nested loops
3162 if (_child && !_child->iteration_split(phase, old_new))
3163 return false;
3164
3165 // Clean out prior deadwood
3166 DCE_loop_body();
3167
3168
3169 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage.
3170 // Replace with a 1-in-10 exit guess.
3171 if (_parent /*not the root loop*/ &&
3172 !_irreducible &&
3173 // Also ignore the occasional dead backedge
3174 !tail()->is_top()) {
3175 adjust_loop_exit_prob(phase);
3176 }
3177
3178 // Gate unrolling, RCE and peeling efforts.
3179 if (!_child && // If not an inner loop, do not split
3180 !_irreducible &&
3181 _allow_optimizations &&
3182 !tail()->is_top()) { // Also ignore the occasional dead backedge
3183 if (!_has_call) {
3184 if (!iteration_split_impl(phase, old_new)) {
3185 return false;
3186 }
3187 } else if (policy_unswitching(phase)) {
3188 phase->do_unswitching(this, old_new);
3189 }
3190 }
3191
3192 // Minor offset re-organization to remove loop-fallout uses of
3193 // trip counter when there was no major reshaping.
3194 phase->reorg_offsets(this);
3195
3196 if (_next && !_next->iteration_split(phase, old_new))
3197 return false;
3198 return true;
3199 }
3200
3201
3202 //=============================================================================
3203 // Process all the loops in the loop tree and replace any fill
3204 // patterns with an intrinsic version.
3205 bool PhaseIdealLoop::do_intrinsify_fill() {
3206 bool changed = false;
3207 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
3208 IdealLoopTree* lpt = iter.current();
3209 changed |= intrinsify_fill(lpt);
3210 }
3211 return changed;
3212 }
3213
3214
3215 // Examine an inner loop looking for a a single store of an invariant
3216 // value in a unit stride loop,
3217 bool PhaseIdealLoop::match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value,
3218 Node*& shift, Node*& con) {
3219 const char* msg = NULL;
3220 Node* msg_node = NULL;
3221
3222 store_value = NULL;
3223 con = NULL;
3224 shift = NULL;
3225
3226 // Process the loop looking for stores. If there are multiple
3227 // stores or extra control flow give at this point.
3228 CountedLoopNode* head = lpt->_head->as_CountedLoop();
3229 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) {
3230 Node* n = lpt->_body.at(i);
3231 if (n->outcnt() == 0) continue; // Ignore dead
3232 if (n->is_Store()) {
3233 if (store != NULL) {
3234 msg = "multiple stores";
3235 break;
3236 }
3237 int opc = n->Opcode();
3238 if (opc == Op_StoreP || opc == Op_StoreN || opc == Op_StoreNKlass || opc == Op_StoreCM) {
3239 msg = "oop fills not handled";
3240 break;
3241 }
3242 Node* value = n->in(MemNode::ValueIn);
3243 if (!lpt->is_invariant(value)) {
3244 msg = "variant store value";
3245 } else if (!_igvn.type(n->in(MemNode::Address))->isa_aryptr()) {
3246 msg = "not array address";
3247 }
3248 store = n;
3249 store_value = value;
3250 } else if (n->is_If() && n != head->loopexit_or_null()) {
3251 msg = "extra control flow";
3252 msg_node = n;
3253 }
3254 }
3255
3256 if (store == NULL) {
3257 // No store in loop
3258 return false;
3259 }
3260
3261 if (msg == NULL && head->stride_con() != 1) {
3262 // could handle negative strides too
3263 if (head->stride_con() < 0) {
3264 msg = "negative stride";
3265 } else {
3266 msg = "non-unit stride";
3267 }
3268 }
3269
3270 if (msg == NULL && !store->in(MemNode::Address)->is_AddP()) {
3271 msg = "can't handle store address";
3272 msg_node = store->in(MemNode::Address);
3273 }
3274
3275 if (msg == NULL &&
3276 (!store->in(MemNode::Memory)->is_Phi() ||
3277 store->in(MemNode::Memory)->in(LoopNode::LoopBackControl) != store)) {
3278 msg = "store memory isn't proper phi";
3279 msg_node = store->in(MemNode::Memory);
3280 }
3281
3282 // Make sure there is an appropriate fill routine
3283 BasicType t = store->as_Mem()->memory_type();
3284 const char* fill_name;
3285 if (msg == NULL &&
3286 StubRoutines::select_fill_function(t, false, fill_name) == NULL) {
3287 msg = "unsupported store";
3288 msg_node = store;
3289 }
3290
3291 if (msg != NULL) {
3292 #ifndef PRODUCT
3293 if (TraceOptimizeFill) {
3294 tty->print_cr("not fill intrinsic candidate: %s", msg);
3295 if (msg_node != NULL) msg_node->dump();
3296 }
3297 #endif
3298 return false;
3299 }
3300
3301 // Make sure the address expression can be handled. It should be
3302 // head->phi * elsize + con. head->phi might have a ConvI2L(CastII()).
3303 Node* elements[4];
3304 Node* cast = NULL;
3305 Node* conv = NULL;
3306 bool found_index = false;
3307 int count = store->in(MemNode::Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
3308 for (int e = 0; e < count; e++) {
3309 Node* n = elements[e];
3310 if (n->is_Con() && con == NULL) {
3311 con = n;
3312 } else if (n->Opcode() == Op_LShiftX && shift == NULL) {
3313 Node* value = n->in(1);
3314 #ifdef _LP64
3315 if (value->Opcode() == Op_ConvI2L) {
3316 conv = value;
3317 value = value->in(1);
3318 }
3319 if (value->Opcode() == Op_CastII &&
3320 value->as_CastII()->has_range_check()) {
3321 // Skip range check dependent CastII nodes
3322 cast = value;
3323 value = value->in(1);
3324 }
3325 #endif
3326 if (value != head->phi()) {
3327 msg = "unhandled shift in address";
3328 } else {
3329 if (type2aelembytes(store->as_Mem()->memory_type(), true) != (1 << n->in(2)->get_int())) {
3330 msg = "scale doesn't match";
3331 } else {
3332 found_index = true;
3333 shift = n;
3334 }
3335 }
3336 } else if (n->Opcode() == Op_ConvI2L && conv == NULL) {
3337 conv = n;
3338 n = n->in(1);
3339 if (n->Opcode() == Op_CastII &&
3340 n->as_CastII()->has_range_check()) {
3341 // Skip range check dependent CastII nodes
3342 cast = n;
3343 n = n->in(1);
3344 }
3345 if (n == head->phi()) {
3346 found_index = true;
3347 } else {
3348 msg = "unhandled input to ConvI2L";
3349 }
3350 } else if (n == head->phi()) {
3351 // no shift, check below for allowed cases
3352 found_index = true;
3353 } else {
3354 msg = "unhandled node in address";
3355 msg_node = n;
3356 }
3357 }
3358
3359 if (count == -1) {
3360 msg = "malformed address expression";
3361 msg_node = store;
3362 }
3363
3364 if (!found_index) {
3365 msg = "missing use of index";
3366 }
3367
3368 // byte sized items won't have a shift
3369 if (msg == NULL && shift == NULL && t != T_BYTE && t != T_BOOLEAN) {
3370 msg = "can't find shift";
3371 msg_node = store;
3372 }
3373
3374 if (msg != NULL) {
3375 #ifndef PRODUCT
3376 if (TraceOptimizeFill) {
3377 tty->print_cr("not fill intrinsic: %s", msg);
3378 if (msg_node != NULL) msg_node->dump();
3379 }
3380 #endif
3381 return false;
3382 }
3383
3384 // No make sure all the other nodes in the loop can be handled
3385 VectorSet ok(Thread::current()->resource_area());
3386
3387 // store related values are ok
3388 ok.set(store->_idx);
3389 ok.set(store->in(MemNode::Memory)->_idx);
3390
3391 CountedLoopEndNode* loop_exit = head->loopexit();
3392
3393 // Loop structure is ok
3394 ok.set(head->_idx);
3395 ok.set(loop_exit->_idx);
3396 ok.set(head->phi()->_idx);
3397 ok.set(head->incr()->_idx);
3398 ok.set(loop_exit->cmp_node()->_idx);
3399 ok.set(loop_exit->in(1)->_idx);
3400
3401 // Address elements are ok
3402 if (con) ok.set(con->_idx);
3403 if (shift) ok.set(shift->_idx);
3404 if (cast) ok.set(cast->_idx);
3405 if (conv) ok.set(conv->_idx);
3406
3407 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) {
3408 Node* n = lpt->_body.at(i);
3409 if (n->outcnt() == 0) continue; // Ignore dead
3410 if (ok.test(n->_idx)) continue;
3411 // Backedge projection is ok
3412 if (n->is_IfTrue() && n->in(0) == loop_exit) continue;
3413 if (!n->is_AddP()) {
3414 msg = "unhandled node";
3415 msg_node = n;
3416 break;
3417 }
3418 }
3419
3420 // Make sure no unexpected values are used outside the loop
3421 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) {
3422 Node* n = lpt->_body.at(i);
3423 // These values can be replaced with other nodes if they are used
3424 // outside the loop.
3425 if (n == store || n == loop_exit || n == head->incr() || n == store->in(MemNode::Memory)) continue;
3426 for (SimpleDUIterator iter(n); iter.has_next(); iter.next()) {
3427 Node* use = iter.get();
3428 if (!lpt->_body.contains(use)) {
3429 msg = "node is used outside loop";
3430 // lpt->_body.dump();
3431 msg_node = n;
3432 break;
3433 }
3434 }
3435 }
3436
3437 #ifdef ASSERT
3438 if (TraceOptimizeFill) {
3439 if (msg != NULL) {
3440 tty->print_cr("no fill intrinsic: %s", msg);
3441 if (msg_node != NULL) msg_node->dump();
3442 } else {
3443 tty->print_cr("fill intrinsic for:");
3444 }
3445 store->dump();
3446 if (Verbose) {
3447 lpt->_body.dump();
3448 }
3449 }
3450 #endif
3451
3452 return msg == NULL;
3453 }
3454
3455
3456
3457 bool PhaseIdealLoop::intrinsify_fill(IdealLoopTree* lpt) {
3458 // Only for counted inner loops
3459 if (!lpt->is_counted() || !lpt->is_inner()) {
3460 return false;
3461 }
3462
3463 // Must have constant stride
3464 CountedLoopNode* head = lpt->_head->as_CountedLoop();
3465 if (!head->is_valid_counted_loop() || !head->is_normal_loop()) {
3466 return false;
3467 }
3468
3469 head->verify_strip_mined(1);
3470
3471 // Check that the body only contains a store of a loop invariant
3472 // value that is indexed by the loop phi.
3473 Node* store = NULL;
3474 Node* store_value = NULL;
3475 Node* shift = NULL;
3476 Node* offset = NULL;
3477 if (!match_fill_loop(lpt, store, store_value, shift, offset)) {
3478 return false;
3479 }
3480
3481 Node* exit = head->loopexit()->proj_out_or_null(0);
3482 if (exit == NULL) {
3483 return false;
3484 }
3485
3486 #ifndef PRODUCT
3487 if (TraceLoopOpts) {
3488 tty->print("ArrayFill ");
3489 lpt->dump_head();
3490 }
3491 #endif
3492
3493 // Now replace the whole loop body by a call to a fill routine that
3494 // covers the same region as the loop.
3495 Node* base = store->in(MemNode::Address)->as_AddP()->in(AddPNode::Base);
3496
3497 // Build an expression for the beginning of the copy region
3498 Node* index = head->init_trip();
3499 #ifdef _LP64
3500 index = new ConvI2LNode(index);
3501 _igvn.register_new_node_with_optimizer(index);
3502 #endif
3503 if (shift != NULL) {
3504 // byte arrays don't require a shift but others do.
3505 index = new LShiftXNode(index, shift->in(2));
3506 _igvn.register_new_node_with_optimizer(index);
3507 }
3508 index = new AddPNode(base, base, index);
3509 _igvn.register_new_node_with_optimizer(index);
3510 Node* from = new AddPNode(base, index, offset);
3511 _igvn.register_new_node_with_optimizer(from);
3512 // Compute the number of elements to copy
3513 Node* len = new SubINode(head->limit(), head->init_trip());
3514 _igvn.register_new_node_with_optimizer(len);
3515
3516 BasicType t = store->as_Mem()->memory_type();
3517 bool aligned = false;
3518 if (offset != NULL && head->init_trip()->is_Con()) {
3519 int element_size = type2aelembytes(t);
3520 aligned = (offset->find_intptr_t_type()->get_con() + head->init_trip()->get_int() * element_size) % HeapWordSize == 0;
3521 }
3522
3523 // Build a call to the fill routine
3524 const char* fill_name;
3525 address fill = StubRoutines::select_fill_function(t, aligned, fill_name);
3526 assert(fill != NULL, "what?");
3527
3528 // Convert float/double to int/long for fill routines
3529 if (t == T_FLOAT) {
3530 store_value = new MoveF2INode(store_value);
3531 _igvn.register_new_node_with_optimizer(store_value);
3532 } else if (t == T_DOUBLE) {
3533 store_value = new MoveD2LNode(store_value);
3534 _igvn.register_new_node_with_optimizer(store_value);
3535 }
3536
3537 Node* mem_phi = store->in(MemNode::Memory);
3538 Node* result_ctrl;
3539 Node* result_mem;
3540 const TypeFunc* call_type = OptoRuntime::array_fill_Type();
3541 CallLeafNode *call = new CallLeafNoFPNode(call_type, fill,
3542 fill_name, TypeAryPtr::get_array_body_type(t));
3543 uint cnt = 0;
3544 call->init_req(TypeFunc::Parms + cnt++, from);
3545 call->init_req(TypeFunc::Parms + cnt++, store_value);
3546 #ifdef _LP64
3547 len = new ConvI2LNode(len);
3548 _igvn.register_new_node_with_optimizer(len);
3549 #endif
3550 call->init_req(TypeFunc::Parms + cnt++, len);
3551 #ifdef _LP64
3552 call->init_req(TypeFunc::Parms + cnt++, C->top());
3553 #endif
3554 call->init_req(TypeFunc::Control, head->init_control());
3555 call->init_req(TypeFunc::I_O, C->top()); // Does no I/O.
3556 call->init_req(TypeFunc::Memory, mem_phi->in(LoopNode::EntryControl));
3557 call->init_req(TypeFunc::ReturnAdr, C->start()->proj_out_or_null(TypeFunc::ReturnAdr));
3558 call->init_req(TypeFunc::FramePtr, C->start()->proj_out_or_null(TypeFunc::FramePtr));
3559 _igvn.register_new_node_with_optimizer(call);
3560 result_ctrl = new ProjNode(call,TypeFunc::Control);
3561 _igvn.register_new_node_with_optimizer(result_ctrl);
3562 result_mem = new ProjNode(call,TypeFunc::Memory);
3563 _igvn.register_new_node_with_optimizer(result_mem);
3564
3565 /* Disable following optimization until proper fix (add missing checks).
3566
3567 // If this fill is tightly coupled to an allocation and overwrites
3568 // the whole body, allow it to take over the zeroing.
3569 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, this);
3570 if (alloc != NULL && alloc->is_AllocateArray()) {
3571 Node* length = alloc->as_AllocateArray()->Ideal_length();
3572 if (head->limit() == length &&
3573 head->init_trip() == _igvn.intcon(0)) {
3574 if (TraceOptimizeFill) {
3575 tty->print_cr("Eliminated zeroing in allocation");
3576 }
3577 alloc->maybe_set_complete(&_igvn);
3578 } else {
3579 #ifdef ASSERT
3580 if (TraceOptimizeFill) {
3581 tty->print_cr("filling array but bounds don't match");
3582 alloc->dump();
3583 head->init_trip()->dump();
3584 head->limit()->dump();
3585 length->dump();
3586 }
3587 #endif
3588 }
3589 }
3590 */
3591
3592 if (head->is_strip_mined()) {
3593 // Inner strip mined loop goes away so get rid of outer strip
3594 // mined loop
3595 Node* outer_sfpt = head->outer_safepoint();
3596 Node* in = outer_sfpt->in(0);
3597 Node* outer_out = head->outer_loop_exit();
3598 lazy_replace(outer_out, in);
3599 _igvn.replace_input_of(outer_sfpt, 0, C->top());
3600 }
3601
3602 // Redirect the old control and memory edges that are outside the loop.
3603 // Sometimes the memory phi of the head is used as the outgoing
3604 // state of the loop. It's safe in this case to replace it with the
3605 // result_mem.
3606 _igvn.replace_node(store->in(MemNode::Memory), result_mem);
3607 lazy_replace(exit, result_ctrl);
3608 _igvn.replace_node(store, result_mem);
3609 // Any uses the increment outside of the loop become the loop limit.
3610 _igvn.replace_node(head->incr(), head->limit());
3611
3612 // Disconnect the head from the loop.
3613 for (uint i = 0; i < lpt->_body.size(); i++) {
3614 Node* n = lpt->_body.at(i);
3615 _igvn.replace_node(n, C->top());
3616 }
3617
3618 return true;
3619 }