1 /*
2 * Copyright (c) 1998, 2024, 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 "ci/ciMethodData.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "gc/shared/barrierSet.hpp"
29 #include "gc/shared/c2/barrierSetC2.hpp"
30 #include "libadt/vectset.hpp"
31 #include "memory/allocation.inline.hpp"
32 #include "memory/resourceArea.hpp"
33 #include "opto/addnode.hpp"
34 #include "opto/arraycopynode.hpp"
35 #include "opto/callnode.hpp"
36 #include "opto/castnode.hpp"
37 #include "opto/connode.hpp"
38 #include "opto/convertnode.hpp"
39 #include "opto/divnode.hpp"
40 #include "opto/idealGraphPrinter.hpp"
41 #include "opto/loopnode.hpp"
42 #include "opto/movenode.hpp"
43 #include "opto/mulnode.hpp"
44 #include "opto/opaquenode.hpp"
45 #include "opto/predicates.hpp"
46 #include "opto/rootnode.hpp"
47 #include "opto/runtime.hpp"
48 #include "opto/vectorization.hpp"
49 #include "runtime/sharedRuntime.hpp"
50 #include "utilities/checkedCast.hpp"
51 #include "utilities/powerOfTwo.hpp"
52
53 //=============================================================================
54 //--------------------------is_cloop_ind_var-----------------------------------
55 // Determine if a node is a counted loop induction variable.
56 // NOTE: The method is declared in "node.hpp".
57 bool Node::is_cloop_ind_var() const {
58 return (is_Phi() &&
59 as_Phi()->region()->is_CountedLoop() &&
60 as_Phi()->region()->as_CountedLoop()->phi() == this);
61 }
62
63 //=============================================================================
64 //------------------------------dump_spec--------------------------------------
65 // Dump special per-node info
66 #ifndef PRODUCT
67 void LoopNode::dump_spec(outputStream *st) const {
68 RegionNode::dump_spec(st);
69 if (is_inner_loop()) st->print( "inner " );
70 if (is_partial_peel_loop()) st->print( "partial_peel " );
71 if (partial_peel_has_failed()) st->print( "partial_peel_failed " );
72 }
73 #endif
74
75 //------------------------------is_valid_counted_loop-------------------------
76 bool LoopNode::is_valid_counted_loop(BasicType bt) const {
77 if (is_BaseCountedLoop() && as_BaseCountedLoop()->bt() == bt) {
78 BaseCountedLoopNode* l = as_BaseCountedLoop();
79 BaseCountedLoopEndNode* le = l->loopexit_or_null();
80 if (le != nullptr &&
81 le->proj_out_or_null(1 /* true */) == l->in(LoopNode::LoopBackControl)) {
82 Node* phi = l->phi();
83 Node* exit = le->proj_out_or_null(0 /* false */);
84 if (exit != nullptr && exit->Opcode() == Op_IfFalse &&
85 phi != nullptr && phi->is_Phi() &&
86 phi->in(LoopNode::LoopBackControl) == l->incr() &&
87 le->loopnode() == l && le->stride_is_con()) {
88 return true;
89 }
90 }
91 }
92 return false;
93 }
94
95 //------------------------------get_early_ctrl---------------------------------
96 // Compute earliest legal control
97 Node *PhaseIdealLoop::get_early_ctrl( Node *n ) {
98 assert( !n->is_Phi() && !n->is_CFG(), "this code only handles data nodes" );
99 uint i;
100 Node *early;
101 if (n->in(0) && !n->is_expensive()) {
102 early = n->in(0);
103 if (!early->is_CFG()) // Might be a non-CFG multi-def
104 early = get_ctrl(early); // So treat input as a straight data input
105 i = 1;
106 } else {
107 early = get_ctrl(n->in(1));
108 i = 2;
109 }
110 uint e_d = dom_depth(early);
111 assert( early, "" );
112 for (; i < n->req(); i++) {
113 Node *cin = get_ctrl(n->in(i));
114 assert( cin, "" );
115 // Keep deepest dominator depth
116 uint c_d = dom_depth(cin);
117 if (c_d > e_d) { // Deeper guy?
118 early = cin; // Keep deepest found so far
119 e_d = c_d;
120 } else if (c_d == e_d && // Same depth?
121 early != cin) { // If not equal, must use slower algorithm
122 // If same depth but not equal, one _must_ dominate the other
123 // and we want the deeper (i.e., dominated) guy.
124 Node *n1 = early;
125 Node *n2 = cin;
126 while (1) {
127 n1 = idom(n1); // Walk up until break cycle
128 n2 = idom(n2);
129 if (n1 == cin || // Walked early up to cin
130 dom_depth(n2) < c_d)
131 break; // early is deeper; keep him
132 if (n2 == early || // Walked cin up to early
133 dom_depth(n1) < c_d) {
134 early = cin; // cin is deeper; keep him
135 break;
136 }
137 }
138 e_d = dom_depth(early); // Reset depth register cache
139 }
140 }
141
142 // Return earliest legal location
143 assert(early == find_non_split_ctrl(early), "unexpected early control");
144
145 if (n->is_expensive() && !_verify_only && !_verify_me) {
146 assert(n->in(0), "should have control input");
147 early = get_early_ctrl_for_expensive(n, early);
148 }
149
150 return early;
151 }
152
153 //------------------------------get_early_ctrl_for_expensive---------------------------------
154 // Move node up the dominator tree as high as legal while still beneficial
155 Node *PhaseIdealLoop::get_early_ctrl_for_expensive(Node *n, Node* earliest) {
156 assert(n->in(0) && n->is_expensive(), "expensive node with control input here");
157 assert(OptimizeExpensiveOps, "optimization off?");
158
159 Node* ctl = n->in(0);
160 assert(ctl->is_CFG(), "expensive input 0 must be cfg");
161 uint min_dom_depth = dom_depth(earliest);
162 #ifdef ASSERT
163 if (!is_dominator(ctl, earliest) && !is_dominator(earliest, ctl)) {
164 dump_bad_graph("Bad graph detected in get_early_ctrl_for_expensive", n, earliest, ctl);
165 assert(false, "Bad graph detected in get_early_ctrl_for_expensive");
166 }
167 #endif
168 if (dom_depth(ctl) < min_dom_depth) {
169 return earliest;
170 }
171
172 while (true) {
173 Node* next = ctl;
174 // Moving the node out of a loop on the projection of an If
175 // confuses Loop Predication. So, once we hit a loop in an If branch
176 // that doesn't branch to an UNC, we stop. The code that process
177 // expensive nodes will notice the loop and skip over it to try to
178 // move the node further up.
179 if (ctl->is_CountedLoop() && ctl->in(1) != nullptr && ctl->in(1)->in(0) != nullptr && ctl->in(1)->in(0)->is_If()) {
180 if (!ctl->in(1)->as_Proj()->is_uncommon_trap_if_pattern()) {
181 break;
182 }
183 next = idom(ctl->in(1)->in(0));
184 } else if (ctl->is_Proj()) {
185 // We only move it up along a projection if the projection is
186 // the single control projection for its parent: same code path,
187 // if it's a If with UNC or fallthrough of a call.
188 Node* parent_ctl = ctl->in(0);
189 if (parent_ctl == nullptr) {
190 break;
191 } else if (parent_ctl->is_CountedLoopEnd() && parent_ctl->as_CountedLoopEnd()->loopnode() != nullptr) {
192 next = parent_ctl->as_CountedLoopEnd()->loopnode()->init_control();
193 } else if (parent_ctl->is_If()) {
194 if (!ctl->as_Proj()->is_uncommon_trap_if_pattern()) {
195 break;
196 }
197 assert(idom(ctl) == parent_ctl, "strange");
198 next = idom(parent_ctl);
199 } else if (ctl->is_CatchProj()) {
200 if (ctl->as_Proj()->_con != CatchProjNode::fall_through_index) {
201 break;
202 }
203 assert(parent_ctl->in(0)->in(0)->is_Call(), "strange graph");
204 next = parent_ctl->in(0)->in(0)->in(0);
205 } else {
206 // Check if parent control has a single projection (this
207 // control is the only possible successor of the parent
208 // control). If so, we can try to move the node above the
209 // parent control.
210 int nb_ctl_proj = 0;
211 for (DUIterator_Fast imax, i = parent_ctl->fast_outs(imax); i < imax; i++) {
212 Node *p = parent_ctl->fast_out(i);
213 if (p->is_Proj() && p->is_CFG()) {
214 nb_ctl_proj++;
215 if (nb_ctl_proj > 1) {
216 break;
217 }
218 }
219 }
220
221 if (nb_ctl_proj > 1) {
222 break;
223 }
224 assert(parent_ctl->is_Start() || parent_ctl->is_MemBar() || parent_ctl->is_Call() ||
225 BarrierSet::barrier_set()->barrier_set_c2()->is_gc_barrier_node(parent_ctl), "unexpected node");
226 assert(idom(ctl) == parent_ctl, "strange");
227 next = idom(parent_ctl);
228 }
229 } else {
230 next = idom(ctl);
231 }
232 if (next->is_Root() || next->is_Start() || dom_depth(next) < min_dom_depth) {
233 break;
234 }
235 ctl = next;
236 }
237
238 if (ctl != n->in(0)) {
239 _igvn.replace_input_of(n, 0, ctl);
240 _igvn.hash_insert(n);
241 }
242
243 return ctl;
244 }
245
246
247 //------------------------------set_early_ctrl---------------------------------
248 // Set earliest legal control
249 void PhaseIdealLoop::set_early_ctrl(Node* n, bool update_body) {
250 Node *early = get_early_ctrl(n);
251
252 // Record earliest legal location
253 set_ctrl(n, early);
254 IdealLoopTree *loop = get_loop(early);
255 if (update_body && loop->_child == nullptr) {
256 loop->_body.push(n);
257 }
258 }
259
260 //------------------------------set_subtree_ctrl-------------------------------
261 // set missing _ctrl entries on new nodes
262 void PhaseIdealLoop::set_subtree_ctrl(Node* n, bool update_body) {
263 // Already set? Get out.
264 if (_loop_or_ctrl[n->_idx]) return;
265 // Recursively set _loop_or_ctrl array to indicate where the Node goes
266 uint i;
267 for (i = 0; i < n->req(); ++i) {
268 Node *m = n->in(i);
269 if (m && m != C->root()) {
270 set_subtree_ctrl(m, update_body);
271 }
272 }
273
274 // Fixup self
275 set_early_ctrl(n, update_body);
276 }
277
278 IdealLoopTree* PhaseIdealLoop::insert_outer_loop(IdealLoopTree* loop, LoopNode* outer_l, Node* outer_ift) {
279 IdealLoopTree* outer_ilt = new IdealLoopTree(this, outer_l, outer_ift);
280 IdealLoopTree* parent = loop->_parent;
281 IdealLoopTree* sibling = parent->_child;
282 if (sibling == loop) {
283 parent->_child = outer_ilt;
284 } else {
285 while (sibling->_next != loop) {
286 sibling = sibling->_next;
287 }
288 sibling->_next = outer_ilt;
289 }
290 outer_ilt->_next = loop->_next;
291 outer_ilt->_parent = parent;
292 outer_ilt->_child = loop;
293 outer_ilt->_nest = loop->_nest;
294 loop->_parent = outer_ilt;
295 loop->_next = nullptr;
296 loop->_nest++;
297 assert(loop->_nest <= SHRT_MAX, "sanity");
298 return outer_ilt;
299 }
300
301 // Create a skeleton strip mined outer loop: a Loop head before the
302 // inner strip mined loop, a safepoint and an exit condition guarded
303 // by an opaque node after the inner strip mined loop with a backedge
304 // to the loop head. The inner strip mined loop is left as it is. Only
305 // once loop optimizations are over, do we adjust the inner loop exit
306 // condition to limit its number of iterations, set the outer loop
307 // exit condition and add Phis to the outer loop head. Some loop
308 // optimizations that operate on the inner strip mined loop need to be
309 // aware of the outer strip mined loop: loop unswitching needs to
310 // clone the outer loop as well as the inner, unrolling needs to only
311 // clone the inner loop etc. No optimizations need to change the outer
312 // strip mined loop as it is only a skeleton.
313 IdealLoopTree* PhaseIdealLoop::create_outer_strip_mined_loop(BoolNode *test, Node *cmp, Node *init_control,
314 IdealLoopTree* loop, float cl_prob, float le_fcnt,
315 Node*& entry_control, Node*& iffalse) {
316 Node* outer_test = _igvn.intcon(0);
317 set_ctrl(outer_test, C->root());
318 Node *orig = iffalse;
319 iffalse = iffalse->clone();
320 _igvn.register_new_node_with_optimizer(iffalse);
321 set_idom(iffalse, idom(orig), dom_depth(orig));
322
323 IfNode *outer_le = new OuterStripMinedLoopEndNode(iffalse, outer_test, cl_prob, le_fcnt);
324 Node *outer_ift = new IfTrueNode (outer_le);
325 Node* outer_iff = orig;
326 _igvn.replace_input_of(outer_iff, 0, outer_le);
327
328 LoopNode *outer_l = new OuterStripMinedLoopNode(C, init_control, outer_ift);
329 entry_control = outer_l;
330
331 IdealLoopTree* outer_ilt = insert_outer_loop(loop, outer_l, outer_ift);
332
333 set_loop(iffalse, outer_ilt);
334 // When this code runs, loop bodies have not yet been populated.
335 const bool body_populated = false;
336 register_control(outer_le, outer_ilt, iffalse, body_populated);
337 register_control(outer_ift, outer_ilt, outer_le, body_populated);
338 set_idom(outer_iff, outer_le, dom_depth(outer_le));
339 _igvn.register_new_node_with_optimizer(outer_l);
340 set_loop(outer_l, outer_ilt);
341 set_idom(outer_l, init_control, dom_depth(init_control)+1);
342
343 return outer_ilt;
344 }
345
346 void PhaseIdealLoop::insert_loop_limit_check_predicate(ParsePredicateSuccessProj* loop_limit_check_parse_proj,
347 Node* cmp_limit, Node* bol) {
348 assert(loop_limit_check_parse_proj->in(0)->is_ParsePredicate(), "must be parse predicate");
349 Node* new_predicate_proj = create_new_if_for_predicate(loop_limit_check_parse_proj, nullptr,
350 Deoptimization::Reason_loop_limit_check,
351 Op_If);
352 Node* iff = new_predicate_proj->in(0);
353 cmp_limit = _igvn.register_new_node_with_optimizer(cmp_limit);
354 bol = _igvn.register_new_node_with_optimizer(bol);
355 set_subtree_ctrl(bol, false);
356 _igvn.replace_input_of(iff, 1, bol);
357
358 #ifndef PRODUCT
359 // report that the loop predication has been actually performed
360 // for this loop
361 if (TraceLoopLimitCheck) {
362 tty->print_cr("Counted Loop Limit Check generated:");
363 debug_only( bol->dump(2); )
364 }
365 #endif
366 }
367
368 Node* PhaseIdealLoop::loop_exit_control(Node* x, IdealLoopTree* loop) {
369 // Counted loop head must be a good RegionNode with only 3 not null
370 // control input edges: Self, Entry, LoopBack.
371 if (x->in(LoopNode::Self) == nullptr || x->req() != 3 || loop->_irreducible) {
372 return nullptr;
373 }
374 Node *init_control = x->in(LoopNode::EntryControl);
375 Node *back_control = x->in(LoopNode::LoopBackControl);
376 if (init_control == nullptr || back_control == nullptr) { // Partially dead
377 return nullptr;
378 }
379 // Must also check for TOP when looking for a dead loop
380 if (init_control->is_top() || back_control->is_top()) {
381 return nullptr;
382 }
383
384 // Allow funny placement of Safepoint
385 if (back_control->Opcode() == Op_SafePoint) {
386 back_control = back_control->in(TypeFunc::Control);
387 }
388
389 // Controlling test for loop
390 Node *iftrue = back_control;
391 uint iftrue_op = iftrue->Opcode();
392 if (iftrue_op != Op_IfTrue &&
393 iftrue_op != Op_IfFalse) {
394 // I have a weird back-control. Probably the loop-exit test is in
395 // the middle of the loop and I am looking at some trailing control-flow
396 // merge point. To fix this I would have to partially peel the loop.
397 return nullptr; // Obscure back-control
398 }
399
400 // Get boolean guarding loop-back test
401 Node *iff = iftrue->in(0);
402 if (get_loop(iff) != loop || !iff->in(1)->is_Bool()) {
403 return nullptr;
404 }
405 return iftrue;
406 }
407
408 Node* PhaseIdealLoop::loop_exit_test(Node* back_control, IdealLoopTree* loop, Node*& incr, Node*& limit, BoolTest::mask& bt, float& cl_prob) {
409 Node* iftrue = back_control;
410 uint iftrue_op = iftrue->Opcode();
411 Node* iff = iftrue->in(0);
412 BoolNode* test = iff->in(1)->as_Bool();
413 bt = test->_test._test;
414 cl_prob = iff->as_If()->_prob;
415 if (iftrue_op == Op_IfFalse) {
416 bt = BoolTest(bt).negate();
417 cl_prob = 1.0 - cl_prob;
418 }
419 // Get backedge compare
420 Node* cmp = test->in(1);
421 if (!cmp->is_Cmp()) {
422 return nullptr;
423 }
424
425 // Find the trip-counter increment & limit. Limit must be loop invariant.
426 incr = cmp->in(1);
427 limit = cmp->in(2);
428
429 // ---------
430 // need 'loop()' test to tell if limit is loop invariant
431 // ---------
432
433 if (!is_member(loop, get_ctrl(incr))) { // Swapped trip counter and limit?
434 Node* tmp = incr; // Then reverse order into the CmpI
435 incr = limit;
436 limit = tmp;
437 bt = BoolTest(bt).commute(); // And commute the exit test
438 }
439 if (is_member(loop, get_ctrl(limit))) { // Limit must be loop-invariant
440 return nullptr;
441 }
442 if (!is_member(loop, get_ctrl(incr))) { // Trip counter must be loop-variant
443 return nullptr;
444 }
445 return cmp;
446 }
447
448 Node* PhaseIdealLoop::loop_iv_incr(Node* incr, Node* x, IdealLoopTree* loop, Node*& phi_incr) {
449 if (incr->is_Phi()) {
450 if (incr->as_Phi()->region() != x || incr->req() != 3) {
451 return nullptr; // Not simple trip counter expression
452 }
453 phi_incr = incr;
454 incr = phi_incr->in(LoopNode::LoopBackControl); // Assume incr is on backedge of Phi
455 if (!is_member(loop, get_ctrl(incr))) { // Trip counter must be loop-variant
456 return nullptr;
457 }
458 }
459 return incr;
460 }
461
462 Node* PhaseIdealLoop::loop_iv_stride(Node* incr, IdealLoopTree* loop, Node*& xphi) {
463 assert(incr->Opcode() == Op_AddI || incr->Opcode() == Op_AddL, "caller resp.");
464 // Get merge point
465 xphi = incr->in(1);
466 Node *stride = incr->in(2);
467 if (!stride->is_Con()) { // Oops, swap these
468 if (!xphi->is_Con()) { // Is the other guy a constant?
469 return nullptr; // Nope, unknown stride, bail out
470 }
471 Node *tmp = xphi; // 'incr' is commutative, so ok to swap
472 xphi = stride;
473 stride = tmp;
474 }
475 return stride;
476 }
477
478 PhiNode* PhaseIdealLoop::loop_iv_phi(Node* xphi, Node* phi_incr, Node* x, IdealLoopTree* loop) {
479 if (!xphi->is_Phi()) {
480 return nullptr; // Too much math on the trip counter
481 }
482 if (phi_incr != nullptr && phi_incr != xphi) {
483 return nullptr;
484 }
485 PhiNode *phi = xphi->as_Phi();
486
487 // Phi must be of loop header; backedge must wrap to increment
488 if (phi->region() != x) {
489 return nullptr;
490 }
491 return phi;
492 }
493
494 static int check_stride_overflow(jlong final_correction, const TypeInteger* limit_t, BasicType bt) {
495 if (final_correction > 0) {
496 if (limit_t->lo_as_long() > (max_signed_integer(bt) - final_correction)) {
497 return -1;
498 }
499 if (limit_t->hi_as_long() > (max_signed_integer(bt) - final_correction)) {
500 return 1;
501 }
502 } else {
503 if (limit_t->hi_as_long() < (min_signed_integer(bt) - final_correction)) {
504 return -1;
505 }
506 if (limit_t->lo_as_long() < (min_signed_integer(bt) - final_correction)) {
507 return 1;
508 }
509 }
510 return 0;
511 }
512
513 static bool condition_stride_ok(BoolTest::mask bt, jlong stride_con) {
514 // If the condition is inverted and we will be rolling
515 // through MININT to MAXINT, then bail out.
516 if (bt == BoolTest::eq || // Bail out, but this loop trips at most twice!
517 // Odd stride
518 (bt == BoolTest::ne && stride_con != 1 && stride_con != -1) ||
519 // Count down loop rolls through MAXINT
520 ((bt == BoolTest::le || bt == BoolTest::lt) && stride_con < 0) ||
521 // Count up loop rolls through MININT
522 ((bt == BoolTest::ge || bt == BoolTest::gt) && stride_con > 0)) {
523 return false; // Bail out
524 }
525 return true;
526 }
527
528 Node* PhaseIdealLoop::loop_nest_replace_iv(Node* iv_to_replace, Node* inner_iv, Node* outer_phi, Node* inner_head,
529 BasicType bt) {
530 Node* iv_as_long;
531 if (bt == T_LONG) {
532 iv_as_long = new ConvI2LNode(inner_iv, TypeLong::INT);
533 register_new_node(iv_as_long, inner_head);
534 } else {
535 iv_as_long = inner_iv;
536 }
537 Node* iv_replacement = AddNode::make(outer_phi, iv_as_long, bt);
538 register_new_node(iv_replacement, inner_head);
539 for (DUIterator_Last imin, i = iv_to_replace->last_outs(imin); i >= imin;) {
540 Node* u = iv_to_replace->last_out(i);
541 #ifdef ASSERT
542 if (!is_dominator(inner_head, ctrl_or_self(u))) {
543 assert(u->is_Phi(), "should be a Phi");
544 for (uint j = 1; j < u->req(); j++) {
545 if (u->in(j) == iv_to_replace) {
546 assert(is_dominator(inner_head, u->in(0)->in(j)), "iv use above loop?");
547 }
548 }
549 }
550 #endif
551 _igvn.rehash_node_delayed(u);
552 int nb = u->replace_edge(iv_to_replace, iv_replacement, &_igvn);
553 i -= nb;
554 }
555 return iv_replacement;
556 }
557
558 // Add a Parse Predicate with an uncommon trap on the failing/false path. Normal control will continue on the true path.
559 void PhaseIdealLoop::add_parse_predicate(Deoptimization::DeoptReason reason, Node* inner_head, IdealLoopTree* loop,
560 SafePointNode* sfpt) {
561 if (!C->too_many_traps(reason)) {
562 ParsePredicateNode* parse_predicate = new ParsePredicateNode(inner_head->in(LoopNode::EntryControl), reason, &_igvn);
563 register_control(parse_predicate, loop, inner_head->in(LoopNode::EntryControl));
564 Node* if_false = new IfFalseNode(parse_predicate);
565 register_control(if_false, _ltree_root, parse_predicate);
566 Node* if_true = new IfTrueNode(parse_predicate);
567 register_control(if_true, loop, parse_predicate);
568
569 int trap_request = Deoptimization::make_trap_request(reason, Deoptimization::Action_maybe_recompile);
570 address call_addr = OptoRuntime::uncommon_trap_blob()->entry_point();
571 const TypePtr* no_memory_effects = nullptr;
572 JVMState* jvms = sfpt->jvms();
573 CallNode* unc = new CallStaticJavaNode(OptoRuntime::uncommon_trap_Type(), call_addr, "uncommon_trap",
574 no_memory_effects);
575
576 Node* mem = nullptr;
577 Node* i_o = nullptr;
578 if (sfpt->is_Call()) {
579 mem = sfpt->proj_out(TypeFunc::Memory);
580 i_o = sfpt->proj_out(TypeFunc::I_O);
581 } else {
582 mem = sfpt->memory();
583 i_o = sfpt->i_o();
584 }
585
586 Node *frame = new ParmNode(C->start(), TypeFunc::FramePtr);
587 register_new_node(frame, C->start());
588 Node *ret = new ParmNode(C->start(), TypeFunc::ReturnAdr);
589 register_new_node(ret, C->start());
590
591 unc->init_req(TypeFunc::Control, if_false);
592 unc->init_req(TypeFunc::I_O, i_o);
593 unc->init_req(TypeFunc::Memory, mem); // may gc ptrs
594 unc->init_req(TypeFunc::FramePtr, frame);
595 unc->init_req(TypeFunc::ReturnAdr, ret);
596 unc->init_req(TypeFunc::Parms+0, _igvn.intcon(trap_request));
597 unc->set_cnt(PROB_UNLIKELY_MAG(4));
598 unc->copy_call_debug_info(&_igvn, sfpt);
599
600 for (uint i = TypeFunc::Parms; i < unc->req(); i++) {
601 set_subtree_ctrl(unc->in(i), false);
602 }
603 register_control(unc, _ltree_root, if_false);
604
605 Node* ctrl = new ProjNode(unc, TypeFunc::Control);
606 register_control(ctrl, _ltree_root, unc);
607 Node* halt = new HaltNode(ctrl, frame, "uncommon trap returned which should never happen" PRODUCT_ONLY(COMMA /*reachable*/false));
608 register_control(halt, _ltree_root, ctrl);
609 _igvn.add_input_to(C->root(), halt);
610
611 _igvn.replace_input_of(inner_head, LoopNode::EntryControl, if_true);
612 set_idom(inner_head, if_true, dom_depth(inner_head));
613 }
614 }
615
616 // Find a safepoint node that dominates the back edge. We need a
617 // SafePointNode so we can use its jvm state to create empty
618 // predicates.
619 static bool no_side_effect_since_safepoint(Compile* C, Node* x, Node* mem, MergeMemNode* mm, PhaseIdealLoop* phase) {
620 SafePointNode* safepoint = nullptr;
621 for (DUIterator_Fast imax, i = x->fast_outs(imax); i < imax; i++) {
622 Node* u = x->fast_out(i);
623 if (u->is_memory_phi()) {
624 Node* m = u->in(LoopNode::LoopBackControl);
625 if (u->adr_type() == TypePtr::BOTTOM) {
626 if (m->is_MergeMem() && mem->is_MergeMem()) {
627 if (m != mem DEBUG_ONLY(|| true)) {
628 // MergeMemStream can modify m, for example to adjust the length to mem.
629 // This is unfortunate, and probably unnecessary. But as it is, we need
630 // to add m to the igvn worklist, else we may have a modified node that
631 // is not on the igvn worklist.
632 phase->igvn()._worklist.push(m);
633 for (MergeMemStream mms(m->as_MergeMem(), mem->as_MergeMem()); mms.next_non_empty2(); ) {
634 if (!mms.is_empty()) {
635 if (mms.memory() != mms.memory2()) {
636 return false;
637 }
638 #ifdef ASSERT
639 if (mms.alias_idx() != Compile::AliasIdxBot) {
640 mm->set_memory_at(mms.alias_idx(), mem->as_MergeMem()->base_memory());
641 }
642 #endif
643 }
644 }
645 }
646 } else if (mem->is_MergeMem()) {
647 if (m != mem->as_MergeMem()->base_memory()) {
648 return false;
649 }
650 } else {
651 return false;
652 }
653 } else {
654 if (mem->is_MergeMem()) {
655 if (m != mem->as_MergeMem()->memory_at(C->get_alias_index(u->adr_type()))) {
656 return false;
657 }
658 #ifdef ASSERT
659 mm->set_memory_at(C->get_alias_index(u->adr_type()), mem->as_MergeMem()->base_memory());
660 #endif
661 } else {
662 if (m != mem) {
663 return false;
664 }
665 }
666 }
667 }
668 }
669 return true;
670 }
671
672 SafePointNode* PhaseIdealLoop::find_safepoint(Node* back_control, Node* x, IdealLoopTree* loop) {
673 IfNode* exit_test = back_control->in(0)->as_If();
674 SafePointNode* safepoint = nullptr;
675 if (exit_test->in(0)->is_SafePoint() && exit_test->in(0)->outcnt() == 1) {
676 safepoint = exit_test->in(0)->as_SafePoint();
677 } else {
678 Node* c = back_control;
679 while (c != x && c->Opcode() != Op_SafePoint) {
680 c = idom(c);
681 }
682
683 if (c->Opcode() == Op_SafePoint) {
684 safepoint = c->as_SafePoint();
685 }
686
687 if (safepoint == nullptr) {
688 return nullptr;
689 }
690
691 Node* mem = safepoint->in(TypeFunc::Memory);
692
693 // We can only use that safepoint if there's no side effect between the backedge and the safepoint.
694
695 // mm is used for book keeping
696 MergeMemNode* mm = nullptr;
697 #ifdef ASSERT
698 if (mem->is_MergeMem()) {
699 mm = mem->clone()->as_MergeMem();
700 _igvn._worklist.push(mm);
701 for (MergeMemStream mms(mem->as_MergeMem()); mms.next_non_empty(); ) {
702 if (mms.alias_idx() != Compile::AliasIdxBot && loop != get_loop(ctrl_or_self(mms.memory()))) {
703 mm->set_memory_at(mms.alias_idx(), mem->as_MergeMem()->base_memory());
704 }
705 }
706 }
707 #endif
708 if (!no_side_effect_since_safepoint(C, x, mem, mm, this)) {
709 safepoint = nullptr;
710 } else {
711 assert(mm == nullptr|| _igvn.transform(mm) == mem->as_MergeMem()->base_memory(), "all memory state should have been processed");
712 }
713 #ifdef ASSERT
714 if (mm != nullptr) {
715 _igvn.remove_dead_node(mm);
716 }
717 #endif
718 }
719 return safepoint;
720 }
721
722 // If the loop has the shape of a counted loop but with a long
723 // induction variable, transform the loop in a loop nest: an inner
724 // loop that iterates for at most max int iterations with an integer
725 // induction variable and an outer loop that iterates over the full
726 // range of long values from the initial loop in (at most) max int
727 // steps. That is:
728 //
729 // x: for (long phi = init; phi < limit; phi += stride) {
730 // // phi := Phi(L, init, incr)
731 // // incr := AddL(phi, longcon(stride))
732 // long incr = phi + stride;
733 // ... use phi and incr ...
734 // }
735 //
736 // OR:
737 //
738 // x: for (long phi = init; (phi += stride) < limit; ) {
739 // // phi := Phi(L, AddL(init, stride), incr)
740 // // incr := AddL(phi, longcon(stride))
741 // long incr = phi + stride;
742 // ... use phi and (phi + stride) ...
743 // }
744 //
745 // ==transform=>
746 //
747 // const ulong inner_iters_limit = INT_MAX - stride - 1; //near 0x7FFFFFF0
748 // assert(stride <= inner_iters_limit); // else abort transform
749 // assert((extralong)limit + stride <= LONG_MAX); // else deopt
750 // outer_head: for (long outer_phi = init;;) {
751 // // outer_phi := Phi(outer_head, init, AddL(outer_phi, I2L(inner_phi)))
752 // ulong inner_iters_max = (ulong) MAX(0, ((extralong)limit + stride - outer_phi));
753 // long inner_iters_actual = MIN(inner_iters_limit, inner_iters_max);
754 // assert(inner_iters_actual == (int)inner_iters_actual);
755 // int inner_phi, inner_incr;
756 // x: for (inner_phi = 0;; inner_phi = inner_incr) {
757 // // inner_phi := Phi(x, intcon(0), inner_incr)
758 // // inner_incr := AddI(inner_phi, intcon(stride))
759 // inner_incr = inner_phi + stride;
760 // if (inner_incr < inner_iters_actual) {
761 // ... use phi=>(outer_phi+inner_phi) ...
762 // continue;
763 // }
764 // else break;
765 // }
766 // if ((outer_phi+inner_phi) < limit) //OR (outer_phi+inner_incr) < limit
767 // continue;
768 // else break;
769 // }
770 //
771 // The same logic is used to transform an int counted loop that contains long range checks into a loop nest of 2 int
772 // loops with long range checks transformed to int range checks in the inner loop.
773 bool PhaseIdealLoop::create_loop_nest(IdealLoopTree* loop, Node_List &old_new) {
774 Node* x = loop->_head;
775 // Only for inner loops
776 if (loop->_child != nullptr || !x->is_BaseCountedLoop() || x->as_Loop()->is_loop_nest_outer_loop()) {
777 return false;
778 }
779
780 if (x->is_CountedLoop() && !x->as_CountedLoop()->is_main_loop() && !x->as_CountedLoop()->is_normal_loop()) {
781 return false;
782 }
783
784 BaseCountedLoopNode* head = x->as_BaseCountedLoop();
785 BasicType bt = x->as_BaseCountedLoop()->bt();
786
787 check_counted_loop_shape(loop, x, bt);
788
789 #ifndef PRODUCT
790 if (bt == T_LONG) {
791 Atomic::inc(&_long_loop_candidates);
792 }
793 #endif
794
795 jlong stride_con_long = head->stride_con();
796 assert(stride_con_long != 0, "missed some peephole opt");
797 // We can't iterate for more than max int at a time.
798 if (stride_con_long != (jint)stride_con_long || stride_con_long == min_jint) {
799 assert(bt == T_LONG, "only for long loops");
800 return false;
801 }
802 jint stride_con = checked_cast<jint>(stride_con_long);
803 // The number of iterations for the integer count loop: guarantee no
804 // overflow: max_jint - stride_con max. -1 so there's no need for a
805 // loop limit check if the exit test is <= or >=.
806 int iters_limit = max_jint - ABS(stride_con) - 1;
807 #ifdef ASSERT
808 if (bt == T_LONG && StressLongCountedLoop > 0) {
809 iters_limit = iters_limit / StressLongCountedLoop;
810 }
811 #endif
812 // At least 2 iterations so counted loop construction doesn't fail
813 if (iters_limit/ABS(stride_con) < 2) {
814 return false;
815 }
816
817 PhiNode* phi = head->phi()->as_Phi();
818 Node* incr = head->incr();
819
820 Node* back_control = head->in(LoopNode::LoopBackControl);
821
822 // data nodes on back branch not supported
823 if (back_control->outcnt() > 1) {
824 return false;
825 }
826
827 Node* limit = head->limit();
828 // We'll need to use the loop limit before the inner loop is entered
829 if (!is_dominator(get_ctrl(limit), x)) {
830 return false;
831 }
832
833 IfNode* exit_test = head->loopexit();
834
835 assert(back_control->Opcode() == Op_IfTrue, "wrong projection for back edge");
836
837 Node_List range_checks;
838 iters_limit = extract_long_range_checks(loop, stride_con, iters_limit, phi, range_checks);
839
840 if (bt == T_INT) {
841 // The only purpose of creating a loop nest is to handle long range checks. If there are none, do not proceed further.
842 if (range_checks.size() == 0) {
843 return false;
844 }
845 }
846
847 // Take what we know about the number of iterations of the long counted loop into account when computing the limit of
848 // the inner loop.
849 const Node* init = head->init_trip();
850 const TypeInteger* lo = _igvn.type(init)->is_integer(bt);
851 const TypeInteger* hi = _igvn.type(limit)->is_integer(bt);
852 if (stride_con < 0) {
853 swap(lo, hi);
854 }
855 if (hi->hi_as_long() <= lo->lo_as_long()) {
856 // not a loop after all
857 return false;
858 }
859
860 if (range_checks.size() > 0) {
861 // This transformation requires peeling one iteration. Also, if it has range checks and they are eliminated by Loop
862 // Predication, then 2 Hoisted Check Predicates are added for one range check. Finally, transforming a long range
863 // check requires extra logic to be executed before the loop is entered and for the outer loop. As a result, the
864 // transformations can't pay off for a small number of iterations: roughly, if the loop runs for 3 iterations, it's
865 // going to execute as many range checks once transformed with range checks eliminated (1 peeled iteration with
866 // range checks + 2 predicates per range checks) as it would have not transformed. It also has to pay for the extra
867 // logic on loop entry and for the outer loop.
868 loop->compute_trip_count(this);
869 if (head->is_CountedLoop() && head->as_CountedLoop()->has_exact_trip_count()) {
870 if (head->as_CountedLoop()->trip_count() <= 3) {
871 return false;
872 }
873 } else {
874 loop->compute_profile_trip_cnt(this);
875 if (!head->is_profile_trip_failed() && head->profile_trip_cnt() <= 3) {
876 return false;
877 }
878 }
879 }
880
881 julong orig_iters = (julong)hi->hi_as_long() - lo->lo_as_long();
882 iters_limit = checked_cast<int>(MIN2((julong)iters_limit, orig_iters));
883
884 // We need a safepoint to insert Parse Predicates for the inner loop.
885 SafePointNode* safepoint;
886 if (bt == T_INT && head->as_CountedLoop()->is_strip_mined()) {
887 // Loop is strip mined: use the safepoint of the outer strip mined loop
888 OuterStripMinedLoopNode* outer_loop = head->as_CountedLoop()->outer_loop();
889 assert(outer_loop != nullptr, "no outer loop");
890 safepoint = outer_loop->outer_safepoint();
891 outer_loop->transform_to_counted_loop(&_igvn, this);
892 exit_test = head->loopexit();
893 } else {
894 safepoint = find_safepoint(back_control, x, loop);
895 }
896
897 Node* exit_branch = exit_test->proj_out(false);
898 Node* entry_control = head->in(LoopNode::EntryControl);
899
900 // Clone the control flow of the loop to build an outer loop
901 Node* outer_back_branch = back_control->clone();
902 Node* outer_exit_test = new IfNode(exit_test->in(0), exit_test->in(1), exit_test->_prob, exit_test->_fcnt);
903 Node* inner_exit_branch = exit_branch->clone();
904
905 LoopNode* outer_head = new LoopNode(entry_control, outer_back_branch);
906 IdealLoopTree* outer_ilt = insert_outer_loop(loop, outer_head, outer_back_branch);
907
908 const bool body_populated = true;
909 register_control(outer_head, outer_ilt, entry_control, body_populated);
910
911 _igvn.register_new_node_with_optimizer(inner_exit_branch);
912 set_loop(inner_exit_branch, outer_ilt);
913 set_idom(inner_exit_branch, exit_test, dom_depth(exit_branch));
914
915 outer_exit_test->set_req(0, inner_exit_branch);
916 register_control(outer_exit_test, outer_ilt, inner_exit_branch, body_populated);
917
918 _igvn.replace_input_of(exit_branch, 0, outer_exit_test);
919 set_idom(exit_branch, outer_exit_test, dom_depth(exit_branch));
920
921 outer_back_branch->set_req(0, outer_exit_test);
922 register_control(outer_back_branch, outer_ilt, outer_exit_test, body_populated);
923
924 _igvn.replace_input_of(x, LoopNode::EntryControl, outer_head);
925 set_idom(x, outer_head, dom_depth(x));
926
927 // add an iv phi to the outer loop and use it to compute the inner
928 // loop iteration limit
929 Node* outer_phi = phi->clone();
930 outer_phi->set_req(0, outer_head);
931 register_new_node(outer_phi, outer_head);
932
933 Node* inner_iters_max = nullptr;
934 if (stride_con > 0) {
935 inner_iters_max = MaxNode::max_diff_with_zero(limit, outer_phi, TypeInteger::bottom(bt), _igvn);
936 } else {
937 inner_iters_max = MaxNode::max_diff_with_zero(outer_phi, limit, TypeInteger::bottom(bt), _igvn);
938 }
939
940 Node* inner_iters_limit = _igvn.integercon(iters_limit, bt);
941 // inner_iters_max may not fit in a signed integer (iterating from
942 // Long.MIN_VALUE to Long.MAX_VALUE for instance). Use an unsigned
943 // min.
944 const TypeInteger* inner_iters_actual_range = TypeInteger::make(0, iters_limit, Type::WidenMin, bt);
945 Node* inner_iters_actual = MaxNode::unsigned_min(inner_iters_max, inner_iters_limit, inner_iters_actual_range, _igvn);
946
947 Node* inner_iters_actual_int;
948 if (bt == T_LONG) {
949 inner_iters_actual_int = new ConvL2INode(inner_iters_actual);
950 _igvn.register_new_node_with_optimizer(inner_iters_actual_int);
951 // When the inner loop is transformed to a counted loop, a loop limit check is not expected to be needed because
952 // the loop limit is less or equal to max_jint - stride - 1 (if stride is positive but a similar argument exists for
953 // a negative stride). We add a CastII here to guarantee that, when the counted loop is created in a subsequent loop
954 // opts pass, an accurate range of values for the limits is found.
955 const TypeInt* inner_iters_actual_int_range = TypeInt::make(0, iters_limit, Type::WidenMin);
956 inner_iters_actual_int = new CastIINode(outer_head, inner_iters_actual_int, inner_iters_actual_int_range, ConstraintCastNode::UnconditionalDependency);
957 _igvn.register_new_node_with_optimizer(inner_iters_actual_int);
958 } else {
959 inner_iters_actual_int = inner_iters_actual;
960 }
961
962 Node* int_zero = _igvn.intcon(0);
963 set_ctrl(int_zero, C->root());
964 if (stride_con < 0) {
965 inner_iters_actual_int = new SubINode(int_zero, inner_iters_actual_int);
966 _igvn.register_new_node_with_optimizer(inner_iters_actual_int);
967 }
968
969 // Clone the iv data nodes as an integer iv
970 Node* int_stride = _igvn.intcon(stride_con);
971 set_ctrl(int_stride, C->root());
972 Node* inner_phi = new PhiNode(x->in(0), TypeInt::INT);
973 Node* inner_incr = new AddINode(inner_phi, int_stride);
974 Node* inner_cmp = nullptr;
975 inner_cmp = new CmpINode(inner_incr, inner_iters_actual_int);
976 Node* inner_bol = new BoolNode(inner_cmp, exit_test->in(1)->as_Bool()->_test._test);
977 inner_phi->set_req(LoopNode::EntryControl, int_zero);
978 inner_phi->set_req(LoopNode::LoopBackControl, inner_incr);
979 register_new_node(inner_phi, x);
980 register_new_node(inner_incr, x);
981 register_new_node(inner_cmp, x);
982 register_new_node(inner_bol, x);
983
984 _igvn.replace_input_of(exit_test, 1, inner_bol);
985
986 // Clone inner loop phis to outer loop
987 for (uint i = 0; i < head->outcnt(); i++) {
988 Node* u = head->raw_out(i);
989 if (u->is_Phi() && u != inner_phi && u != phi) {
990 assert(u->in(0) == head, "inconsistent");
991 Node* clone = u->clone();
992 clone->set_req(0, outer_head);
993 register_new_node(clone, outer_head);
994 _igvn.replace_input_of(u, LoopNode::EntryControl, clone);
995 }
996 }
997
998 // Replace inner loop long iv phi as inner loop int iv phi + outer
999 // loop iv phi
1000 Node* iv_add = loop_nest_replace_iv(phi, inner_phi, outer_phi, head, bt);
1001
1002 set_subtree_ctrl(inner_iters_actual_int, body_populated);
1003
1004 LoopNode* inner_head = create_inner_head(loop, head, exit_test);
1005
1006 // Summary of steps from initial loop to loop nest:
1007 //
1008 // == old IR nodes =>
1009 //
1010 // entry_control: {...}
1011 // x:
1012 // for (long phi = init;;) {
1013 // // phi := Phi(x, init, incr)
1014 // // incr := AddL(phi, longcon(stride))
1015 // exit_test:
1016 // if (phi < limit)
1017 // back_control: fallthrough;
1018 // else
1019 // exit_branch: break;
1020 // long incr = phi + stride;
1021 // ... use phi and incr ...
1022 // phi = incr;
1023 // }
1024 //
1025 // == new IR nodes (just before final peel) =>
1026 //
1027 // entry_control: {...}
1028 // long adjusted_limit = limit + stride; //because phi_incr != nullptr
1029 // assert(!limit_check_required || (extralong)limit + stride == adjusted_limit); // else deopt
1030 // ulong inner_iters_limit = max_jint - ABS(stride) - 1; //near 0x7FFFFFF0
1031 // outer_head:
1032 // for (long outer_phi = init;;) {
1033 // // outer_phi := phi->clone(), in(0):=outer_head, => Phi(outer_head, init, incr)
1034 // // REPLACE phi => AddL(outer_phi, I2L(inner_phi))
1035 // // REPLACE incr => AddL(outer_phi, I2L(inner_incr))
1036 // // SO THAT outer_phi := Phi(outer_head, init, AddL(outer_phi, I2L(inner_incr)))
1037 // ulong inner_iters_max = (ulong) MAX(0, ((extralong)adjusted_limit - outer_phi) * SGN(stride));
1038 // int inner_iters_actual_int = (int) MIN(inner_iters_limit, inner_iters_max) * SGN(stride);
1039 // inner_head: x: //in(1) := outer_head
1040 // int inner_phi;
1041 // for (inner_phi = 0;;) {
1042 // // inner_phi := Phi(x, intcon(0), inner_phi + stride)
1043 // int inner_incr = inner_phi + stride;
1044 // bool inner_bol = (inner_incr < inner_iters_actual_int);
1045 // exit_test: //exit_test->in(1) := inner_bol;
1046 // if (inner_bol) // WAS (phi < limit)
1047 // back_control: fallthrough;
1048 // else
1049 // inner_exit_branch: break; //exit_branch->clone()
1050 // ... use phi=>(outer_phi+inner_phi) ...
1051 // inner_phi = inner_phi + stride; // inner_incr
1052 // }
1053 // outer_exit_test: //exit_test->clone(), in(0):=inner_exit_branch
1054 // if ((outer_phi+inner_phi) < limit) // WAS (phi < limit)
1055 // outer_back_branch: fallthrough; //back_control->clone(), in(0):=outer_exit_test
1056 // else
1057 // exit_branch: break; //in(0) := outer_exit_test
1058 // }
1059
1060 if (bt == T_INT) {
1061 outer_phi = new ConvI2LNode(outer_phi);
1062 register_new_node(outer_phi, outer_head);
1063 }
1064
1065 transform_long_range_checks(stride_con, range_checks, outer_phi, inner_iters_actual_int,
1066 inner_phi, iv_add, inner_head);
1067 // Peel one iteration of the loop and use the safepoint at the end
1068 // of the peeled iteration to insert Parse Predicates. If no well
1069 // positioned safepoint peel to guarantee a safepoint in the outer
1070 // loop.
1071 if (safepoint != nullptr || !loop->_has_call) {
1072 old_new.clear();
1073 do_peeling(loop, old_new);
1074 } else {
1075 C->set_major_progress();
1076 }
1077
1078 if (safepoint != nullptr) {
1079 SafePointNode* cloned_sfpt = old_new[safepoint->_idx]->as_SafePoint();
1080
1081 if (UseLoopPredicate) {
1082 add_parse_predicate(Deoptimization::Reason_predicate, inner_head, outer_ilt, cloned_sfpt);
1083 }
1084 if (UseProfiledLoopPredicate) {
1085 add_parse_predicate(Deoptimization::Reason_profile_predicate, inner_head, outer_ilt, cloned_sfpt);
1086 }
1087 add_parse_predicate(Deoptimization::Reason_loop_limit_check, inner_head, outer_ilt, cloned_sfpt);
1088 }
1089
1090 #ifndef PRODUCT
1091 if (bt == T_LONG) {
1092 Atomic::inc(&_long_loop_nests);
1093 }
1094 #endif
1095
1096 inner_head->mark_loop_nest_inner_loop();
1097 outer_head->mark_loop_nest_outer_loop();
1098
1099 return true;
1100 }
1101
1102 int PhaseIdealLoop::extract_long_range_checks(const IdealLoopTree* loop, jint stride_con, int iters_limit, PhiNode* phi,
1103 Node_List& range_checks) {
1104 const jlong min_iters = 2;
1105 jlong reduced_iters_limit = iters_limit;
1106 jlong original_iters_limit = iters_limit;
1107 for (uint i = 0; i < loop->_body.size(); i++) {
1108 Node* c = loop->_body.at(i);
1109 if (c->is_IfProj() && c->in(0)->is_RangeCheck()) {
1110 IfProjNode* if_proj = c->as_IfProj();
1111 CallStaticJavaNode* call = if_proj->is_uncommon_trap_if_pattern();
1112 if (call != nullptr) {
1113 Node* range = nullptr;
1114 Node* offset = nullptr;
1115 jlong scale = 0;
1116 if (loop->is_range_check_if(if_proj, this, T_LONG, phi, range, offset, scale) &&
1117 loop->is_invariant(range) && loop->is_invariant(offset) &&
1118 scale != min_jlong &&
1119 original_iters_limit / ABS(scale) >= min_iters * ABS(stride_con)) {
1120 assert(scale == (jint)scale, "scale should be an int");
1121 reduced_iters_limit = MIN2(reduced_iters_limit, original_iters_limit/ABS(scale));
1122 range_checks.push(c);
1123 }
1124 }
1125 }
1126 }
1127
1128 return checked_cast<int>(reduced_iters_limit);
1129 }
1130
1131 // One execution of the inner loop covers a sub-range of the entire iteration range of the loop: [A,Z), aka [A=init,
1132 // Z=limit). If the loop has at least one trip (which is the case here), the iteration variable i always takes A as its
1133 // first value, followed by A+S (S is the stride), next A+2S, etc. The limit is exclusive, so that the final value B of
1134 // i is never Z. It will be B=Z-1 if S=1, or B=Z+1 if S=-1.
1135
1136 // If |S|>1 the formula for the last value B would require a floor operation, specifically B=floor((Z-sgn(S)-A)/S)*S+A,
1137 // which is B=Z-sgn(S)U for some U in [1,|S|]. So when S>0, i ranges as i:[A,Z) or i:[A,B=Z-U], or else (in reverse)
1138 // as i:(Z,A] or i:[B=Z+U,A]. It will become important to reason about this inclusive range [A,B] or [B,A].
1139
1140 // Within the loop there may be many range checks. Each such range check (R.C.) is of the form 0 <= i*K+L < R, where K
1141 // is a scale factor applied to the loop iteration variable i, and L is some offset; K, L, and R are loop-invariant.
1142 // Because R is never negative (see below), this check can always be simplified to an unsigned check i*K+L <u R.
1143
1144 // When a long loop over a 64-bit variable i (outer_iv) is decomposed into a series of shorter sub-loops over a 32-bit
1145 // variable j (inner_iv), j ranges over a shorter interval j:[0,B_2] or [0,Z_2) (assuming S > 0), where the limit is
1146 // chosen to prevent various cases of 32-bit overflow (including multiplications j*K below). In the sub-loop the
1147 // logical value i is offset from j by a 64-bit constant C, so i ranges in i:C+[0,Z_2).
1148
1149 // For S<0, j ranges (in reverse!) through j:[-|B_2|,0] or (-|Z_2|,0]. For either sign of S, we can say i=j+C and j
1150 // ranges through 32-bit ranges [A_2,B_2] or [B_2,A_2] (A_2=0 of course).
1151
1152 // The disjoint union of all the C+[A_2,B_2] ranges from the sub-loops must be identical to the whole range [A,B].
1153 // Assuming S>0, the first C must be A itself, and the next C value is the previous C+B_2, plus S. If |S|=1, the next
1154 // C value is also the previous C+Z_2. In each sub-loop, j counts from j=A_2=0 and i counts from C+0 and exits at
1155 // j=B_2 (i=C+B_2), just before it gets to i=C+Z_2. Both i and j count up (from C and 0) if S>0; otherwise they count
1156 // down (from C and 0 again).
1157
1158 // Returning to range checks, we see that each i*K+L <u R expands to (C+j)*K+L <u R, or j*K+Q <u R, where Q=(C*K+L).
1159 // (Recall that K and L and R are loop-invariant scale, offset and range values for a particular R.C.) This is still a
1160 // 64-bit comparison, so the range check elimination logic will not apply to it. (The R.C.E. transforms operate only on
1161 // 32-bit indexes and comparisons, because they use 64-bit temporary values to avoid overflow; see
1162 // PhaseIdealLoop::add_constraint.)
1163
1164 // We must transform this comparison so that it gets the same answer, but by means of a 32-bit R.C. (using j not i) of
1165 // the form j*K+L_2 <u32 R_2. Note that L_2 and R_2 must be loop-invariant, but only with respect to the sub-loop. Thus, the
1166 // problem reduces to computing values for L_2 and R_2 (for each R.C. in the loop) in the loop header for the sub-loop.
1167 // Then the standard R.C.E. transforms can take those as inputs and further compute the necessary minimum and maximum
1168 // values for the 32-bit counter j within which the range checks can be eliminated.
1169
1170 // So, given j*K+Q <u R, we need to find some j*K+L_2 <u32 R_2, where L_2 and R_2 fit in 32 bits, and the 32-bit operations do
1171 // not overflow. We also need to cover the cases where i*K+L (= j*K+Q) overflows to a 64-bit negative, since that is
1172 // allowed as an input to the R.C., as long as the R.C. as a whole fails.
1173
1174 // If 32-bit multiplication j*K might overflow, we adjust the sub-loop limit Z_2 closer to zero to reduce j's range.
1175
1176 // For each R.C. j*K+Q <u32 R, the range of mathematical values of j*K+Q in the sub-loop is [Q_min, Q_max], where
1177 // Q_min=Q and Q_max=B_2*K+Q (if S>0 and K>0), Q_min=A_2*K+Q and Q_max=Q (if S<0 and K>0),
1178 // Q_min=B_2*K+Q and Q_max=Q if (S>0 and K<0), Q_min=Q and Q_max=A_2*K+Q (if S<0 and K<0)
1179
1180 // Note that the first R.C. value is always Q=(S*K>0 ? Q_min : Q_max). Also Q_{min,max} = Q + {min,max}(A_2*K,B_2*K).
1181 // If S*K>0 then, as the loop iterations progress, each R.C. value i*K+L = j*K+Q goes up from Q=Q_min towards Q_max.
1182 // If S*K<0 then j*K+Q starts at Q=Q_max and goes down towards Q_min.
1183
1184 // Case A: Some Negatives (but no overflow).
1185 // Number line:
1186 // |s64_min . . . 0 . . . s64_max|
1187 // | . Q_min..Q_max . 0 . . . . | s64 negative
1188 // | . . . . R=0 R< R< R< R< | (against R values)
1189 // | . . . Q_min..0..Q_max . . . | small mixed
1190 // | . . . . R R R< R< R< | (against R values)
1191 //
1192 // R values which are out of range (>Q_max+1) are reduced to max(0,Q_max+1). They are marked on the number line as R<.
1193 //
1194 // So, if Q_min <s64 0, then use this test:
1195 // j*K + s32_trunc(Q_min) <u32 clamp(R, 0, Q_max+1) if S*K>0 (R.C.E. steps upward)
1196 // j*K + s32_trunc(Q_max) <u32 clamp(R, 0, Q_max+1) if S*K<0 (R.C.E. steps downward)
1197 // Both formulas reduce to adding j*K to the 32-bit truncated value of the first R.C. expression value, Q:
1198 // j*K + s32_trunc(Q) <u32 clamp(R, 0, Q_max+1) for all S,K
1199
1200 // If the 32-bit truncation loses information, no harm is done, since certainly the clamp also will return R_2=zero.
1201
1202 // Case B: No Negatives.
1203 // Number line:
1204 // |s64_min . . . 0 . . . s64_max|
1205 // | . . . . 0 Q_min..Q_max . . | small positive
1206 // | . . . . R> R R R< R< | (against R values)
1207 // | . . . . 0 . Q_min..Q_max . | s64 positive
1208 // | . . . . R> R> R R R< | (against R values)
1209 //
1210 // R values which are out of range (<Q_min or >Q_max+1) are reduced as marked: R> up to Q_min, R< down to Q_max+1.
1211 // Then the whole comparison is shifted left by Q_min, so it can take place at zero, which is a nice 32-bit value.
1212 //
1213 // So, if both Q_min, Q_max+1 >=s64 0, then use this test:
1214 // j*K + 0 <u32 clamp(R, Q_min, Q_max+1) - Q_min if S*K>0
1215 // More generally:
1216 // j*K + Q - Q_min <u32 clamp(R, Q_min, Q_max+1) - Q_min for all S,K
1217
1218 // Case C: Overflow in the 64-bit domain
1219 // Number line:
1220 // |..Q_max-2^64 . . 0 . . . Q_min..| s64 overflow
1221 // | . . . . R> R> R> R> R | (against R values)
1222 //
1223 // In this case, Q_min >s64 Q_max+1, even though the mathematical values of Q_min and Q_max+1 are correctly ordered.
1224 // The formulas from the previous case can be used, except that the bad upper bound Q_max is replaced by max_jlong.
1225 // (In fact, we could use any replacement bound from R to max_jlong inclusive, as the input to the clamp function.)
1226 //
1227 // So if Q_min >=s64 0 but Q_max+1 <s64 0, use this test:
1228 // j*K + 0 <u32 clamp(R, Q_min, max_jlong) - Q_min if S*K>0
1229 // More generally:
1230 // j*K + Q - Q_min <u32 clamp(R, Q_min, max_jlong) - Q_min for all S,K
1231 //
1232 // Dropping the bad bound means only Q_min is used to reduce the range of R:
1233 // j*K + Q - Q_min <u32 max(Q_min, R) - Q_min for all S,K
1234 //
1235 // Here the clamp function is a 64-bit min/max that reduces the dynamic range of its R operand to the required [L,H]:
1236 // clamp(X, L, H) := max(L, min(X, H))
1237 // When degenerately L > H, it returns L not H.
1238 //
1239 // All of the formulas above can be merged into a single one:
1240 // L_clamp = Q_min < 0 ? 0 : Q_min --whether and how far to left-shift
1241 // H_clamp = Q_max+1 < Q_min ? max_jlong : Q_max+1
1242 // = Q_max+1 < 0 && Q_min >= 0 ? max_jlong : Q_max+1
1243 // Q_first = Q = (S*K>0 ? Q_min : Q_max) = (C*K+L)
1244 // R_clamp = clamp(R, L_clamp, H_clamp) --reduced dynamic range
1245 // replacement R.C.:
1246 // j*K + Q_first - L_clamp <u32 R_clamp - L_clamp
1247 // or equivalently:
1248 // j*K + L_2 <u32 R_2
1249 // where
1250 // L_2 = Q_first - L_clamp
1251 // R_2 = R_clamp - L_clamp
1252 //
1253 // Note on why R is never negative:
1254 //
1255 // Various details of this transformation would break badly if R could be negative, so this transformation only
1256 // operates after obtaining hard evidence that R<0 is impossible. For example, if R comes from a LoadRange node, we
1257 // know R cannot be negative. For explicit checks (of both int and long) a proof is constructed in
1258 // inline_preconditions_checkIndex, which triggers an uncommon trap if R<0, then wraps R in a ConstraintCastNode with a
1259 // non-negative type. Later on, when IdealLoopTree::is_range_check_if looks for an optimizable R.C., it checks that
1260 // the type of that R node is non-negative. Any "wild" R node that could be negative is not treated as an optimizable
1261 // R.C., but R values from a.length and inside checkIndex are good to go.
1262 //
1263 void PhaseIdealLoop::transform_long_range_checks(int stride_con, const Node_List &range_checks, Node* outer_phi,
1264 Node* inner_iters_actual_int, Node* inner_phi,
1265 Node* iv_add, LoopNode* inner_head) {
1266 Node* long_zero = _igvn.longcon(0);
1267 set_ctrl(long_zero, C->root());
1268 Node* int_zero = _igvn.intcon(0);
1269 set_ctrl(int_zero, this->C->root());
1270 Node* long_one = _igvn.longcon(1);
1271 set_ctrl(long_one, this->C->root());
1272 Node* int_stride = _igvn.intcon(checked_cast<int>(stride_con));
1273 set_ctrl(int_stride, this->C->root());
1274
1275 for (uint i = 0; i < range_checks.size(); i++) {
1276 ProjNode* proj = range_checks.at(i)->as_Proj();
1277 ProjNode* unc_proj = proj->other_if_proj();
1278 RangeCheckNode* rc = proj->in(0)->as_RangeCheck();
1279 jlong scale = 0;
1280 Node* offset = nullptr;
1281 Node* rc_bol = rc->in(1);
1282 Node* rc_cmp = rc_bol->in(1);
1283 if (rc_cmp->Opcode() == Op_CmpU) {
1284 // could be shared and have already been taken care of
1285 continue;
1286 }
1287 bool short_scale = false;
1288 bool ok = is_scaled_iv_plus_offset(rc_cmp->in(1), iv_add, T_LONG, &scale, &offset, &short_scale);
1289 assert(ok, "inconsistent: was tested before");
1290 Node* range = rc_cmp->in(2);
1291 Node* c = rc->in(0);
1292 Node* entry_control = inner_head->in(LoopNode::EntryControl);
1293
1294 Node* R = range;
1295 Node* K = _igvn.longcon(scale);
1296 set_ctrl(K, this->C->root());
1297
1298 Node* L = offset;
1299
1300 if (short_scale) {
1301 // This converts:
1302 // (int)i*K + L <u64 R
1303 // with K an int into:
1304 // i*(long)K + L <u64 unsigned_min((long)max_jint + L + 1, R)
1305 // to protect against an overflow of (int)i*K
1306 //
1307 // Because if (int)i*K overflows, there are K,L where:
1308 // (int)i*K + L <u64 R is false because (int)i*K+L overflows to a negative which becomes a huge u64 value.
1309 // But if i*(long)K + L is >u64 (long)max_jint and still is <u64 R, then
1310 // i*(long)K + L <u64 R is true.
1311 //
1312 // As a consequence simply converting i*K + L <u64 R to i*(long)K + L <u64 R could cause incorrect execution.
1313 //
1314 // It's always true that:
1315 // (int)i*K <u64 (long)max_jint + 1
1316 // which implies (int)i*K + L <u64 (long)max_jint + 1 + L
1317 // As a consequence:
1318 // i*(long)K + L <u64 unsigned_min((long)max_jint + L + 1, R)
1319 // is always false in case of overflow of i*K
1320 //
1321 // Note, there are also K,L where i*K overflows and
1322 // i*K + L <u64 R is true, but
1323 // i*(long)K + L <u64 unsigned_min((long)max_jint + L + 1, R) is false
1324 // So this transformation could cause spurious deoptimizations and failed range check elimination
1325 // (but not incorrect execution) for unlikely corner cases with overflow.
1326 // If this causes problems in practice, we could maybe direct execution to a post-loop, instead of deoptimizing.
1327 Node* max_jint_plus_one_long = _igvn.longcon((jlong)max_jint + 1);
1328 set_ctrl(max_jint_plus_one_long, C->root());
1329 Node* max_range = new AddLNode(max_jint_plus_one_long, L);
1330 register_new_node(max_range, entry_control);
1331 R = MaxNode::unsigned_min(R, max_range, TypeLong::POS, _igvn);
1332 set_subtree_ctrl(R, true);
1333 }
1334
1335 Node* C = outer_phi;
1336
1337 // Start with 64-bit values:
1338 // i*K + L <u64 R
1339 // (C+j)*K + L <u64 R
1340 // j*K + Q <u64 R where Q = Q_first = C*K+L
1341 Node* Q_first = new MulLNode(C, K);
1342 register_new_node(Q_first, entry_control);
1343 Q_first = new AddLNode(Q_first, L);
1344 register_new_node(Q_first, entry_control);
1345
1346 // Compute endpoints of the range of values j*K + Q.
1347 // Q_min = (j=0)*K + Q; Q_max = (j=B_2)*K + Q
1348 Node* Q_min = Q_first;
1349
1350 // Compute the exact ending value B_2 (which is really A_2 if S < 0)
1351 Node* B_2 = new LoopLimitNode(this->C, int_zero, inner_iters_actual_int, int_stride);
1352 register_new_node(B_2, entry_control);
1353 B_2 = new SubINode(B_2, int_stride);
1354 register_new_node(B_2, entry_control);
1355 B_2 = new ConvI2LNode(B_2);
1356 register_new_node(B_2, entry_control);
1357
1358 Node* Q_max = new MulLNode(B_2, K);
1359 register_new_node(Q_max, entry_control);
1360 Q_max = new AddLNode(Q_max, Q_first);
1361 register_new_node(Q_max, entry_control);
1362
1363 if (scale * stride_con < 0) {
1364 swap(Q_min, Q_max);
1365 }
1366 // Now, mathematically, Q_max > Q_min, and they are close enough so that (Q_max-Q_min) fits in 32 bits.
1367
1368 // L_clamp = Q_min < 0 ? 0 : Q_min
1369 Node* Q_min_cmp = new CmpLNode(Q_min, long_zero);
1370 register_new_node(Q_min_cmp, entry_control);
1371 Node* Q_min_bool = new BoolNode(Q_min_cmp, BoolTest::lt);
1372 register_new_node(Q_min_bool, entry_control);
1373 Node* L_clamp = new CMoveLNode(Q_min_bool, Q_min, long_zero, TypeLong::LONG);
1374 register_new_node(L_clamp, entry_control);
1375 // (This could also be coded bitwise as L_clamp = Q_min & ~(Q_min>>63).)
1376
1377 Node* Q_max_plus_one = new AddLNode(Q_max, long_one);
1378 register_new_node(Q_max_plus_one, entry_control);
1379
1380 // H_clamp = Q_max+1 < Q_min ? max_jlong : Q_max+1
1381 // (Because Q_min and Q_max are close, the overflow check could also be encoded as Q_max+1 < 0 & Q_min >= 0.)
1382 Node* max_jlong_long = _igvn.longcon(max_jlong);
1383 set_ctrl(max_jlong_long, this->C->root());
1384 Node* Q_max_cmp = new CmpLNode(Q_max_plus_one, Q_min);
1385 register_new_node(Q_max_cmp, entry_control);
1386 Node* Q_max_bool = new BoolNode(Q_max_cmp, BoolTest::lt);
1387 register_new_node(Q_max_bool, entry_control);
1388 Node* H_clamp = new CMoveLNode(Q_max_bool, Q_max_plus_one, max_jlong_long, TypeLong::LONG);
1389 register_new_node(H_clamp, entry_control);
1390 // (This could also be coded bitwise as H_clamp = ((Q_max+1)<<1 | M)>>>1 where M = (Q_max+1)>>63 & ~Q_min>>63.)
1391
1392 // R_2 = clamp(R, L_clamp, H_clamp) - L_clamp
1393 // that is: R_2 = clamp(R, L_clamp=0, H_clamp=Q_max) if Q_min < 0
1394 // or else: R_2 = clamp(R, L_clamp, H_clamp) - Q_min if Q_min >= 0
1395 // and also: R_2 = clamp(R, L_clamp, Q_max+1) - L_clamp if Q_min < Q_max+1 (no overflow)
1396 // or else: R_2 = clamp(R, L_clamp, *no limit*)- L_clamp if Q_max+1 < Q_min (overflow)
1397 Node* R_2 = clamp(R, L_clamp, H_clamp);
1398 R_2 = new SubLNode(R_2, L_clamp);
1399 register_new_node(R_2, entry_control);
1400 R_2 = new ConvL2INode(R_2, TypeInt::POS);
1401 register_new_node(R_2, entry_control);
1402
1403 // L_2 = Q_first - L_clamp
1404 // We are subtracting L_clamp from both sides of the <u32 comparison.
1405 // If S*K>0, then Q_first == 0 and the R.C. expression at -L_clamp and steps upward to Q_max-L_clamp.
1406 // If S*K<0, then Q_first != 0 and the R.C. expression starts high and steps downward to Q_min-L_clamp.
1407 Node* L_2 = new SubLNode(Q_first, L_clamp);
1408 register_new_node(L_2, entry_control);
1409 L_2 = new ConvL2INode(L_2, TypeInt::INT);
1410 register_new_node(L_2, entry_control);
1411
1412 // Transform the range check using the computed values L_2/R_2
1413 // from: i*K + L <u64 R
1414 // to: j*K + L_2 <u32 R_2
1415 // that is:
1416 // (j*K + Q_first) - L_clamp <u32 clamp(R, L_clamp, H_clamp) - L_clamp
1417 K = _igvn.intcon(checked_cast<int>(scale));
1418 set_ctrl(K, this->C->root());
1419 Node* scaled_iv = new MulINode(inner_phi, K);
1420 register_new_node(scaled_iv, c);
1421 Node* scaled_iv_plus_offset = new AddINode(scaled_iv, L_2);
1422 register_new_node(scaled_iv_plus_offset, c);
1423
1424 Node* new_rc_cmp = new CmpUNode(scaled_iv_plus_offset, R_2);
1425 register_new_node(new_rc_cmp, c);
1426
1427 _igvn.replace_input_of(rc_bol, 1, new_rc_cmp);
1428 }
1429 }
1430
1431 Node* PhaseIdealLoop::clamp(Node* R, Node* L, Node* H) {
1432 Node* min = MaxNode::signed_min(R, H, TypeLong::LONG, _igvn);
1433 set_subtree_ctrl(min, true);
1434 Node* max = MaxNode::signed_max(L, min, TypeLong::LONG, _igvn);
1435 set_subtree_ctrl(max, true);
1436 return max;
1437 }
1438
1439 LoopNode* PhaseIdealLoop::create_inner_head(IdealLoopTree* loop, BaseCountedLoopNode* head,
1440 IfNode* exit_test) {
1441 LoopNode* new_inner_head = new LoopNode(head->in(1), head->in(2));
1442 IfNode* new_inner_exit = new IfNode(exit_test->in(0), exit_test->in(1), exit_test->_prob, exit_test->_fcnt);
1443 _igvn.register_new_node_with_optimizer(new_inner_head);
1444 _igvn.register_new_node_with_optimizer(new_inner_exit);
1445 loop->_body.push(new_inner_head);
1446 loop->_body.push(new_inner_exit);
1447 loop->_body.yank(head);
1448 loop->_body.yank(exit_test);
1449 set_loop(new_inner_head, loop);
1450 set_loop(new_inner_exit, loop);
1451 set_idom(new_inner_head, idom(head), dom_depth(head));
1452 set_idom(new_inner_exit, idom(exit_test), dom_depth(exit_test));
1453 lazy_replace(head, new_inner_head);
1454 lazy_replace(exit_test, new_inner_exit);
1455 loop->_head = new_inner_head;
1456 return new_inner_head;
1457 }
1458
1459 #ifdef ASSERT
1460 void PhaseIdealLoop::check_counted_loop_shape(IdealLoopTree* loop, Node* x, BasicType bt) {
1461 Node* back_control = loop_exit_control(x, loop);
1462 assert(back_control != nullptr, "no back control");
1463
1464 BoolTest::mask mask = BoolTest::illegal;
1465 float cl_prob = 0;
1466 Node* incr = nullptr;
1467 Node* limit = nullptr;
1468
1469 Node* cmp = loop_exit_test(back_control, loop, incr, limit, mask, cl_prob);
1470 assert(cmp != nullptr && cmp->Opcode() == Op_Cmp(bt), "no exit test");
1471
1472 Node* phi_incr = nullptr;
1473 incr = loop_iv_incr(incr, x, loop, phi_incr);
1474 assert(incr != nullptr && incr->Opcode() == Op_Add(bt), "no incr");
1475
1476 Node* xphi = nullptr;
1477 Node* stride = loop_iv_stride(incr, loop, xphi);
1478
1479 assert(stride != nullptr, "no stride");
1480
1481 PhiNode* phi = loop_iv_phi(xphi, phi_incr, x, loop);
1482
1483 assert(phi != nullptr && phi->in(LoopNode::LoopBackControl) == incr, "No phi");
1484
1485 jlong stride_con = stride->get_integer_as_long(bt);
1486
1487 assert(condition_stride_ok(mask, stride_con), "illegal condition");
1488
1489 assert(mask != BoolTest::ne, "unexpected condition");
1490 assert(phi_incr == nullptr, "bad loop shape");
1491 assert(cmp->in(1) == incr, "bad exit test shape");
1492
1493 // Safepoint on backedge not supported
1494 assert(x->in(LoopNode::LoopBackControl)->Opcode() != Op_SafePoint, "no safepoint on backedge");
1495 }
1496 #endif
1497
1498 #ifdef ASSERT
1499 // convert an int counted loop to a long counted to stress handling of
1500 // long counted loops
1501 bool PhaseIdealLoop::convert_to_long_loop(Node* cmp, Node* phi, IdealLoopTree* loop) {
1502 Unique_Node_List iv_nodes;
1503 Node_List old_new;
1504 iv_nodes.push(cmp);
1505 bool failed = false;
1506
1507 for (uint i = 0; i < iv_nodes.size() && !failed; i++) {
1508 Node* n = iv_nodes.at(i);
1509 switch(n->Opcode()) {
1510 case Op_Phi: {
1511 Node* clone = new PhiNode(n->in(0), TypeLong::LONG);
1512 old_new.map(n->_idx, clone);
1513 break;
1514 }
1515 case Op_CmpI: {
1516 Node* clone = new CmpLNode(nullptr, nullptr);
1517 old_new.map(n->_idx, clone);
1518 break;
1519 }
1520 case Op_AddI: {
1521 Node* clone = new AddLNode(nullptr, nullptr);
1522 old_new.map(n->_idx, clone);
1523 break;
1524 }
1525 case Op_CastII: {
1526 failed = true;
1527 break;
1528 }
1529 default:
1530 DEBUG_ONLY(n->dump());
1531 fatal("unexpected");
1532 }
1533
1534 for (uint i = 1; i < n->req(); i++) {
1535 Node* in = n->in(i);
1536 if (in == nullptr) {
1537 continue;
1538 }
1539 if (loop->is_member(get_loop(get_ctrl(in)))) {
1540 iv_nodes.push(in);
1541 }
1542 }
1543 }
1544
1545 if (failed) {
1546 for (uint i = 0; i < iv_nodes.size(); i++) {
1547 Node* n = iv_nodes.at(i);
1548 Node* clone = old_new[n->_idx];
1549 if (clone != nullptr) {
1550 _igvn.remove_dead_node(clone);
1551 }
1552 }
1553 return false;
1554 }
1555
1556 for (uint i = 0; i < iv_nodes.size(); i++) {
1557 Node* n = iv_nodes.at(i);
1558 Node* clone = old_new[n->_idx];
1559 for (uint i = 1; i < n->req(); i++) {
1560 Node* in = n->in(i);
1561 if (in == nullptr) {
1562 continue;
1563 }
1564 Node* in_clone = old_new[in->_idx];
1565 if (in_clone == nullptr) {
1566 assert(_igvn.type(in)->isa_int(), "");
1567 in_clone = new ConvI2LNode(in);
1568 _igvn.register_new_node_with_optimizer(in_clone);
1569 set_subtree_ctrl(in_clone, false);
1570 }
1571 if (in_clone->in(0) == nullptr) {
1572 in_clone->set_req(0, C->top());
1573 clone->set_req(i, in_clone);
1574 in_clone->set_req(0, nullptr);
1575 } else {
1576 clone->set_req(i, in_clone);
1577 }
1578 }
1579 _igvn.register_new_node_with_optimizer(clone);
1580 }
1581 set_ctrl(old_new[phi->_idx], phi->in(0));
1582
1583 for (uint i = 0; i < iv_nodes.size(); i++) {
1584 Node* n = iv_nodes.at(i);
1585 Node* clone = old_new[n->_idx];
1586 set_subtree_ctrl(clone, false);
1587 Node* m = n->Opcode() == Op_CmpI ? clone : nullptr;
1588 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1589 Node* u = n->fast_out(i);
1590 if (iv_nodes.member(u)) {
1591 continue;
1592 }
1593 if (m == nullptr) {
1594 m = new ConvL2INode(clone);
1595 _igvn.register_new_node_with_optimizer(m);
1596 set_subtree_ctrl(m, false);
1597 }
1598 _igvn.rehash_node_delayed(u);
1599 int nb = u->replace_edge(n, m, &_igvn);
1600 --i, imax -= nb;
1601 }
1602 }
1603 return true;
1604 }
1605 #endif
1606
1607 //------------------------------is_counted_loop--------------------------------
1608 bool PhaseIdealLoop::is_counted_loop(Node* x, IdealLoopTree*&loop, BasicType iv_bt) {
1609 PhaseGVN *gvn = &_igvn;
1610
1611 Node* back_control = loop_exit_control(x, loop);
1612 if (back_control == nullptr) {
1613 return false;
1614 }
1615
1616 BoolTest::mask bt = BoolTest::illegal;
1617 float cl_prob = 0;
1618 Node* incr = nullptr;
1619 Node* limit = nullptr;
1620 Node* cmp = loop_exit_test(back_control, loop, incr, limit, bt, cl_prob);
1621 if (cmp == nullptr || cmp->Opcode() != Op_Cmp(iv_bt)) {
1622 return false; // Avoid pointer & float & 64-bit compares
1623 }
1624
1625 // Trip-counter increment must be commutative & associative.
1626 if (incr->Opcode() == Op_Cast(iv_bt)) {
1627 incr = incr->in(1);
1628 }
1629
1630 Node* phi_incr = nullptr;
1631 incr = loop_iv_incr(incr, x, loop, phi_incr);
1632 if (incr == nullptr) {
1633 return false;
1634 }
1635
1636 Node* trunc1 = nullptr;
1637 Node* trunc2 = nullptr;
1638 const TypeInteger* iv_trunc_t = nullptr;
1639 Node* orig_incr = incr;
1640 if (!(incr = CountedLoopNode::match_incr_with_optional_truncation(incr, &trunc1, &trunc2, &iv_trunc_t, iv_bt))) {
1641 return false; // Funny increment opcode
1642 }
1643 assert(incr->Opcode() == Op_Add(iv_bt), "wrong increment code");
1644
1645 Node* xphi = nullptr;
1646 Node* stride = loop_iv_stride(incr, loop, xphi);
1647
1648 if (stride == nullptr) {
1649 return false;
1650 }
1651
1652 if (xphi->Opcode() == Op_Cast(iv_bt)) {
1653 xphi = xphi->in(1);
1654 }
1655
1656 // Stride must be constant
1657 jlong stride_con = stride->get_integer_as_long(iv_bt);
1658 assert(stride_con != 0, "missed some peephole opt");
1659
1660 PhiNode* phi = loop_iv_phi(xphi, phi_incr, x, loop);
1661
1662 if (phi == nullptr ||
1663 (trunc1 == nullptr && phi->in(LoopNode::LoopBackControl) != incr) ||
1664 (trunc1 != nullptr && phi->in(LoopNode::LoopBackControl) != trunc1)) {
1665 return false;
1666 }
1667
1668 Node* iftrue = back_control;
1669 uint iftrue_op = iftrue->Opcode();
1670 Node* iff = iftrue->in(0);
1671 BoolNode* test = iff->in(1)->as_Bool();
1672
1673 const TypeInteger* limit_t = gvn->type(limit)->is_integer(iv_bt);
1674 if (trunc1 != nullptr) {
1675 // When there is a truncation, we must be sure that after the truncation
1676 // the trip counter will end up higher than the limit, otherwise we are looking
1677 // at an endless loop. Can happen with range checks.
1678
1679 // Example:
1680 // int i = 0;
1681 // while (true)
1682 // sum + = array[i];
1683 // i++;
1684 // i = i && 0x7fff;
1685 // }
1686 //
1687 // If the array is shorter than 0x8000 this exits through a AIOOB
1688 // - Counted loop transformation is ok
1689 // If the array is longer then this is an endless loop
1690 // - No transformation can be done.
1691
1692 const TypeInteger* incr_t = gvn->type(orig_incr)->is_integer(iv_bt);
1693 if (limit_t->hi_as_long() > incr_t->hi_as_long()) {
1694 // if the limit can have a higher value than the increment (before the phi)
1695 return false;
1696 }
1697 }
1698
1699 Node *init_trip = phi->in(LoopNode::EntryControl);
1700
1701 // If iv trunc type is smaller than int, check for possible wrap.
1702 if (!TypeInteger::bottom(iv_bt)->higher_equal(iv_trunc_t)) {
1703 assert(trunc1 != nullptr, "must have found some truncation");
1704
1705 // Get a better type for the phi (filtered thru if's)
1706 const TypeInteger* phi_ft = filtered_type(phi);
1707
1708 // Can iv take on a value that will wrap?
1709 //
1710 // Ensure iv's limit is not within "stride" of the wrap value.
1711 //
1712 // Example for "short" type
1713 // Truncation ensures value is in the range -32768..32767 (iv_trunc_t)
1714 // If the stride is +10, then the last value of the induction
1715 // variable before the increment (phi_ft->_hi) must be
1716 // <= 32767 - 10 and (phi_ft->_lo) must be >= -32768 to
1717 // ensure no truncation occurs after the increment.
1718
1719 if (stride_con > 0) {
1720 if (iv_trunc_t->hi_as_long() - phi_ft->hi_as_long() < stride_con ||
1721 iv_trunc_t->lo_as_long() > phi_ft->lo_as_long()) {
1722 return false; // truncation may occur
1723 }
1724 } else if (stride_con < 0) {
1725 if (iv_trunc_t->lo_as_long() - phi_ft->lo_as_long() > stride_con ||
1726 iv_trunc_t->hi_as_long() < phi_ft->hi_as_long()) {
1727 return false; // truncation may occur
1728 }
1729 }
1730 // No possibility of wrap so truncation can be discarded
1731 // Promote iv type to Int
1732 } else {
1733 assert(trunc1 == nullptr && trunc2 == nullptr, "no truncation for int");
1734 }
1735
1736 if (!condition_stride_ok(bt, stride_con)) {
1737 return false;
1738 }
1739
1740 const TypeInteger* init_t = gvn->type(init_trip)->is_integer(iv_bt);
1741
1742 if (stride_con > 0) {
1743 if (init_t->lo_as_long() > max_signed_integer(iv_bt) - stride_con) {
1744 return false; // cyclic loop
1745 }
1746 } else {
1747 if (init_t->hi_as_long() < min_signed_integer(iv_bt) - stride_con) {
1748 return false; // cyclic loop
1749 }
1750 }
1751
1752 if (phi_incr != nullptr && bt != BoolTest::ne) {
1753 // check if there is a possibility of IV overflowing after the first increment
1754 if (stride_con > 0) {
1755 if (init_t->hi_as_long() > max_signed_integer(iv_bt) - stride_con) {
1756 return false;
1757 }
1758 } else {
1759 if (init_t->lo_as_long() < min_signed_integer(iv_bt) - stride_con) {
1760 return false;
1761 }
1762 }
1763 }
1764
1765 // =================================================
1766 // ---- SUCCESS! Found A Trip-Counted Loop! -----
1767 //
1768
1769 if (x->Opcode() == Op_Region) {
1770 // x has not yet been transformed to Loop or LongCountedLoop.
1771 // This should only happen if we are inside an infinite loop.
1772 // It happens like this:
1773 // build_loop_tree -> do not attach infinite loop and nested loops
1774 // beautify_loops -> does not transform the infinite and nested loops to LoopNode, because not attached yet
1775 // build_loop_tree -> find and attach infinite and nested loops
1776 // counted_loop -> nested Regions are not yet transformed to LoopNodes, we land here
1777 assert(x->as_Region()->is_in_infinite_subgraph(),
1778 "x can only be a Region and not Loop if inside infinite loop");
1779 // Come back later when Region is transformed to LoopNode
1780 return false;
1781 }
1782
1783 assert(x->Opcode() == Op_Loop || x->Opcode() == Op_LongCountedLoop, "regular loops only");
1784 C->print_method(PHASE_BEFORE_CLOOPS, 3, x);
1785
1786 // ===================================================
1787 // We can only convert this loop to a counted loop if we can guarantee that the iv phi will never overflow at runtime.
1788 // This is an implicit assumption taken by some loop optimizations. We therefore must ensure this property at all cost.
1789 // At this point, we've already excluded some trivial cases where an overflow could have been proven statically.
1790 // But even though we cannot prove that an overflow will *not* happen, we still want to speculatively convert this loop
1791 // to a counted loop. This can be achieved by adding additional iv phi overflow checks before the loop. If they fail,
1792 // we trap and resume execution before the loop without having executed any iteration of the loop, yet.
1793 //
1794 // These additional iv phi overflow checks can be inserted as Loop Limit Check Predicates above the Loop Limit Check
1795 // Parse Predicate which captures a JVM state just before the entry of the loop. If there is no such Parse Predicate,
1796 // we cannot generate a Loop Limit Check Predicate and thus cannot speculatively convert the loop to a counted loop.
1797 //
1798 // In the following, we only focus on int loops with stride > 0 to keep things simple. The argumentation and proof
1799 // for stride < 0 is analogously. For long loops, we would replace max_int with max_long.
1800 //
1801 //
1802 // The loop to be converted does not always need to have the often used shape:
1803 //
1804 // i = init
1805 // i = init loop:
1806 // do { ...
1807 // // ... equivalent i+=stride
1808 // i+=stride <==> if (i < limit)
1809 // } while (i < limit); goto loop
1810 // exit:
1811 // ...
1812 //
1813 // where the loop exit check uses the post-incremented iv phi and a '<'-operator.
1814 //
1815 // We could also have '<='-operator (or '>='-operator for negative strides) or use the pre-incremented iv phi value
1816 // in the loop exit check:
1817 //
1818 // i = init
1819 // loop:
1820 // ...
1821 // if (i <= limit)
1822 // i+=stride
1823 // goto loop
1824 // exit:
1825 // ...
1826 //
1827 // Let's define the following terms:
1828 // - iv_pre_i: The pre-incremented iv phi before the i-th iteration.
1829 // - iv_post_i: The post-incremented iv phi after the i-th iteration.
1830 //
1831 // The iv_pre_i and iv_post_i have the following relation:
1832 // iv_pre_i + stride = iv_post_i
1833 //
1834 // When converting a loop to a counted loop, we want to have a canonicalized loop exit check of the form:
1835 // iv_post_i < adjusted_limit
1836 //
1837 // If that is not the case, we need to canonicalize the loop exit check by using different values for adjusted_limit:
1838 // (LE1) iv_post_i < limit: Already canonicalized. We can directly use limit as adjusted_limit.
1839 // -> adjusted_limit = limit.
1840 // (LE2) iv_post_i <= limit:
1841 // iv_post_i < limit + 1
1842 // -> adjusted limit = limit + 1
1843 // (LE3) iv_pre_i < limit:
1844 // iv_pre_i + stride < limit + stride
1845 // iv_post_i < limit + stride
1846 // -> adjusted_limit = limit + stride
1847 // (LE4) iv_pre_i <= limit:
1848 // iv_pre_i < limit + 1
1849 // iv_pre_i + stride < limit + stride + 1
1850 // iv_post_i < limit + stride + 1
1851 // -> adjusted_limit = limit + stride + 1
1852 //
1853 // Note that:
1854 // (AL) limit <= adjusted_limit.
1855 //
1856 // The following loop invariant has to hold for counted loops with n iterations (i.e. loop exit check true after n-th
1857 // loop iteration) and a canonicalized loop exit check to guarantee that no iv_post_i over- or underflows:
1858 // (INV) For i = 1..n, min_int <= iv_post_i <= max_int
1859 //
1860 // To prove (INV), we require the following two conditions/assumptions:
1861 // (i): adjusted_limit - 1 + stride <= max_int
1862 // (ii): init < limit
1863 //
1864 // If we can prove (INV), we know that there can be no over- or underflow of any iv phi value. We prove (INV) by
1865 // induction by assuming (i) and (ii).
1866 //
1867 // Proof by Induction
1868 // ------------------
1869 // > Base case (i = 1): We show that (INV) holds after the first iteration:
1870 // min_int <= iv_post_1 = init + stride <= max_int
1871 // Proof:
1872 // First, we note that (ii) implies
1873 // (iii) init <= limit - 1
1874 // max_int >= adjusted_limit - 1 + stride [using (i)]
1875 // >= limit - 1 + stride [using (AL)]
1876 // >= init + stride [using (iii)]
1877 // >= min_int [using stride > 0, no underflow]
1878 // Thus, no overflow happens after the first iteration and (INV) holds for i = 1.
1879 //
1880 // Note that to prove the base case we need (i) and (ii).
1881 //
1882 // > Induction Hypothesis (i = j, j > 1): Assume that (INV) holds after the j-th iteration:
1883 // min_int <= iv_post_j <= max_int
1884 // > Step case (i = j + 1): We show that (INV) also holds after the j+1-th iteration:
1885 // min_int <= iv_post_{j+1} = iv_post_j + stride <= max_int
1886 // Proof:
1887 // If iv_post_j >= adjusted_limit:
1888 // We exit the loop after the j-th iteration, and we don't execute the j+1-th iteration anymore. Thus, there is
1889 // also no iv_{j+1}. Since (INV) holds for iv_j, there is nothing left to prove.
1890 // If iv_post_j < adjusted_limit:
1891 // First, we note that:
1892 // (iv) iv_post_j <= adjusted_limit - 1
1893 // max_int >= adjusted_limit - 1 + stride [using (i)]
1894 // >= iv_post_j + stride [using (iv)]
1895 // >= min_int [using stride > 0, no underflow]
1896 //
1897 // Note that to prove the step case we only need (i).
1898 //
1899 // Thus, by assuming (i) and (ii), we proved (INV).
1900 //
1901 //
1902 // It is therefore enough to add the following two Loop Limit Check Predicates to check assumptions (i) and (ii):
1903 //
1904 // (1) Loop Limit Check Predicate for (i):
1905 // Using (i): adjusted_limit - 1 + stride <= max_int
1906 //
1907 // This condition is now restated to use limit instead of adjusted_limit:
1908 //
1909 // To prevent an overflow of adjusted_limit -1 + stride itself, we rewrite this check to
1910 // max_int - stride + 1 >= adjusted_limit
1911 // We can merge the two constants into
1912 // canonicalized_correction = stride - 1
1913 // which gives us
1914 // max_int - canonicalized_correction >= adjusted_limit
1915 //
1916 // To directly use limit instead of adjusted_limit in the predicate condition, we split adjusted_limit into:
1917 // adjusted_limit = limit + limit_correction
1918 // Since stride > 0 and limit_correction <= stride + 1, we can restate this with no over- or underflow into:
1919 // max_int - canonicalized_correction - limit_correction >= limit
1920 // Since canonicalized_correction and limit_correction are both constants, we can replace them with a new constant:
1921 // (v) final_correction = canonicalized_correction + limit_correction
1922 //
1923 // which gives us:
1924 //
1925 // Final predicate condition:
1926 // max_int - final_correction >= limit
1927 //
1928 // However, we need to be careful that (v) does not over- or underflow.
1929 // We know that:
1930 // canonicalized_correction = stride - 1
1931 // and
1932 // limit_correction <= stride + 1
1933 // and thus
1934 // canonicalized_correction + limit_correction <= 2 * stride
1935 // To prevent an over- or underflow of (v), we must ensure that
1936 // 2 * stride <= max_int
1937 // which can safely be checked without over- or underflow with
1938 // (vi) stride != min_int AND abs(stride) <= max_int / 2
1939 //
1940 // We could try to further optimize the cases where (vi) does not hold but given that such large strides are
1941 // very uncommon and the loop would only run for a very few iterations anyway, we simply bail out if (vi) fails.
1942 //
1943 // (2) Loop Limit Check Predicate for (ii):
1944 // Using (ii): init < limit
1945 //
1946 // This Loop Limit Check Predicate is not required if we can prove at compile time that either:
1947 // (2.1) type(init) < type(limit)
1948 // In this case, we know:
1949 // all possible values of init < all possible values of limit
1950 // and we can skip the predicate.
1951 //
1952 // (2.2) init < limit is already checked before (i.e. found as a dominating check)
1953 // In this case, we do not need to re-check the condition and can skip the predicate.
1954 // This is often found for while- and for-loops which have the following shape:
1955 //
1956 // if (init < limit) { // Dominating test. Do not need the Loop Limit Check Predicate below.
1957 // i = init;
1958 // if (init >= limit) { trap(); } // Here we would insert the Loop Limit Check Predicate
1959 // do {
1960 // i += stride;
1961 // } while (i < limit);
1962 // }
1963 //
1964 // (2.3) init + stride <= max_int
1965 // In this case, there is no overflow of the iv phi after the first loop iteration.
1966 // In the proof of the base case above we showed that init + stride <= max_int by using assumption (ii):
1967 // init < limit
1968 // In the proof of the step case above, we did not need (ii) anymore. Therefore, if we already know at
1969 // compile time that init + stride <= max_int then we have trivially proven the base case and that
1970 // there is no overflow of the iv phi after the first iteration. In this case, we don't need to check (ii)
1971 // again and can skip the predicate.
1972
1973 // Check (vi) and bail out if the stride is too big.
1974 if (stride_con == min_signed_integer(iv_bt) || (ABS(stride_con) > max_signed_integer(iv_bt) / 2)) {
1975 return false;
1976 }
1977
1978 // Accounting for (LE3) and (LE4) where we use pre-incremented phis in the loop exit check.
1979 const jlong limit_correction_for_pre_iv_exit_check = (phi_incr != nullptr) ? stride_con : 0;
1980
1981 // Accounting for (LE2) and (LE4) where we use <= or >= in the loop exit check.
1982 const bool includes_limit = (bt == BoolTest::le || bt == BoolTest::ge);
1983 const jlong limit_correction_for_le_ge_exit_check = (includes_limit ? (stride_con > 0 ? 1 : -1) : 0);
1984
1985 const jlong limit_correction = limit_correction_for_pre_iv_exit_check + limit_correction_for_le_ge_exit_check;
1986 const jlong canonicalized_correction = stride_con + (stride_con > 0 ? -1 : 1);
1987 const jlong final_correction = canonicalized_correction + limit_correction;
1988
1989 int sov = check_stride_overflow(final_correction, limit_t, iv_bt);
1990 Node* init_control = x->in(LoopNode::EntryControl);
1991
1992 // If sov==0, limit's type always satisfies the condition, for
1993 // example, when it is an array length.
1994 if (sov != 0) {
1995 if (sov < 0) {
1996 return false; // Bailout: integer overflow is certain.
1997 }
1998 // (1) Loop Limit Check Predicate is required because we could not statically prove that
1999 // limit + final_correction = adjusted_limit - 1 + stride <= max_int
2000 assert(!x->as_Loop()->is_loop_nest_inner_loop(), "loop was transformed");
2001 const Predicates predicates(init_control);
2002 const PredicateBlock* loop_limit_check_predicate_block = predicates.loop_limit_check_predicate_block();
2003 if (!loop_limit_check_predicate_block->has_parse_predicate()) {
2004 // The Loop Limit Check Parse Predicate is not generated if this method trapped here before.
2005 #ifdef ASSERT
2006 if (TraceLoopLimitCheck) {
2007 tty->print("Missing Loop Limit Check Parse Predicate:");
2008 loop->dump_head();
2009 x->dump(1);
2010 }
2011 #endif
2012 return false;
2013 }
2014
2015 ParsePredicateNode* loop_limit_check_parse_predicate = loop_limit_check_predicate_block->parse_predicate();
2016 if (!is_dominator(get_ctrl(limit), loop_limit_check_parse_predicate->in(0))) {
2017 return false;
2018 }
2019
2020 Node* cmp_limit;
2021 Node* bol;
2022
2023 if (stride_con > 0) {
2024 cmp_limit = CmpNode::make(limit, _igvn.integercon(max_signed_integer(iv_bt) - final_correction, iv_bt), iv_bt);
2025 bol = new BoolNode(cmp_limit, BoolTest::le);
2026 } else {
2027 cmp_limit = CmpNode::make(limit, _igvn.integercon(min_signed_integer(iv_bt) - final_correction, iv_bt), iv_bt);
2028 bol = new BoolNode(cmp_limit, BoolTest::ge);
2029 }
2030
2031 insert_loop_limit_check_predicate(init_control->as_IfTrue(), cmp_limit, bol);
2032 }
2033
2034 // (2.3)
2035 const bool init_plus_stride_could_overflow =
2036 (stride_con > 0 && init_t->hi_as_long() > max_signed_integer(iv_bt) - stride_con) ||
2037 (stride_con < 0 && init_t->lo_as_long() < min_signed_integer(iv_bt) - stride_con);
2038 // (2.1)
2039 const bool init_gte_limit = (stride_con > 0 && init_t->hi_as_long() >= limit_t->lo_as_long()) ||
2040 (stride_con < 0 && init_t->lo_as_long() <= limit_t->hi_as_long());
2041
2042 if (init_gte_limit && // (2.1)
2043 ((bt == BoolTest::ne || init_plus_stride_could_overflow) && // (2.3)
2044 !has_dominating_loop_limit_check(init_trip, limit, stride_con, iv_bt, init_control))) { // (2.2)
2045 // (2) Iteration Loop Limit Check Predicate is required because neither (2.1), (2.2), nor (2.3) holds.
2046 // We use the following condition:
2047 // - stride > 0: init < limit
2048 // - stride < 0: init > limit
2049 //
2050 // This predicate is always required if we have a non-equal-operator in the loop exit check (where stride = 1 is
2051 // a requirement). We transform the loop exit check by using a less-than-operator. By doing so, we must always
2052 // check that init < limit. Otherwise, we could have a different number of iterations at runtime.
2053
2054 const Predicates predicates(init_control);
2055 const PredicateBlock* loop_limit_check_predicate_block = predicates.loop_limit_check_predicate_block();
2056 if (!loop_limit_check_predicate_block->has_parse_predicate()) {
2057 // The Loop Limit Check Parse Predicate is not generated if this method trapped here before.
2058 #ifdef ASSERT
2059 if (TraceLoopLimitCheck) {
2060 tty->print("Missing Loop Limit Check Parse Predicate:");
2061 loop->dump_head();
2062 x->dump(1);
2063 }
2064 #endif
2065 return false;
2066 }
2067
2068 ParsePredicateNode* loop_limit_check_parse_predicate = loop_limit_check_predicate_block->parse_predicate();
2069 Node* parse_predicate_entry = loop_limit_check_parse_predicate->in(0);
2070 if (!is_dominator(get_ctrl(limit), parse_predicate_entry) ||
2071 !is_dominator(get_ctrl(init_trip), parse_predicate_entry)) {
2072 return false;
2073 }
2074
2075 Node* cmp_limit;
2076 Node* bol;
2077
2078 if (stride_con > 0) {
2079 cmp_limit = CmpNode::make(init_trip, limit, iv_bt);
2080 bol = new BoolNode(cmp_limit, BoolTest::lt);
2081 } else {
2082 cmp_limit = CmpNode::make(init_trip, limit, iv_bt);
2083 bol = new BoolNode(cmp_limit, BoolTest::gt);
2084 }
2085
2086 insert_loop_limit_check_predicate(init_control->as_IfTrue(), cmp_limit, bol);
2087 }
2088
2089 if (bt == BoolTest::ne) {
2090 // Now we need to canonicalize the loop condition if it is 'ne'.
2091 assert(stride_con == 1 || stride_con == -1, "simple increment only - checked before");
2092 if (stride_con > 0) {
2093 // 'ne' can be replaced with 'lt' only when init < limit. This is ensured by the inserted predicate above.
2094 bt = BoolTest::lt;
2095 } else {
2096 assert(stride_con < 0, "must be");
2097 // 'ne' can be replaced with 'gt' only when init > limit. This is ensured by the inserted predicate above.
2098 bt = BoolTest::gt;
2099 }
2100 }
2101
2102 Node* sfpt = nullptr;
2103 if (loop->_child == nullptr) {
2104 sfpt = find_safepoint(back_control, x, loop);
2105 } else {
2106 sfpt = iff->in(0);
2107 if (sfpt->Opcode() != Op_SafePoint) {
2108 sfpt = nullptr;
2109 }
2110 }
2111
2112 if (x->in(LoopNode::LoopBackControl)->Opcode() == Op_SafePoint) {
2113 Node* backedge_sfpt = x->in(LoopNode::LoopBackControl);
2114 if (((iv_bt == T_INT && LoopStripMiningIter != 0) ||
2115 iv_bt == T_LONG) &&
2116 sfpt == nullptr) {
2117 // Leaving the safepoint on the backedge and creating a
2118 // CountedLoop will confuse optimizations. We can't move the
2119 // safepoint around because its jvm state wouldn't match a new
2120 // location. Give up on that loop.
2121 return false;
2122 }
2123 if (is_deleteable_safept(backedge_sfpt)) {
2124 lazy_replace(backedge_sfpt, iftrue);
2125 if (loop->_safepts != nullptr) {
2126 loop->_safepts->yank(backedge_sfpt);
2127 }
2128 loop->_tail = iftrue;
2129 }
2130 }
2131
2132
2133 #ifdef ASSERT
2134 if (iv_bt == T_INT &&
2135 !x->as_Loop()->is_loop_nest_inner_loop() &&
2136 StressLongCountedLoop > 0 &&
2137 trunc1 == nullptr &&
2138 convert_to_long_loop(cmp, phi, loop)) {
2139 return false;
2140 }
2141 #endif
2142
2143 Node* adjusted_limit = limit;
2144 if (phi_incr != nullptr) {
2145 // If compare points directly to the phi we need to adjust
2146 // the compare so that it points to the incr. Limit have
2147 // to be adjusted to keep trip count the same and we
2148 // should avoid int overflow.
2149 //
2150 // i = init; do {} while(i++ < limit);
2151 // is converted to
2152 // i = init; do {} while(++i < limit+1);
2153 //
2154 adjusted_limit = gvn->transform(AddNode::make(limit, stride, iv_bt));
2155 }
2156
2157 if (includes_limit) {
2158 // The limit check guaranties that 'limit <= (max_jint - stride)' so
2159 // we can convert 'i <= limit' to 'i < limit+1' since stride != 0.
2160 //
2161 Node* one = (stride_con > 0) ? gvn->integercon( 1, iv_bt) : gvn->integercon(-1, iv_bt);
2162 adjusted_limit = gvn->transform(AddNode::make(adjusted_limit, one, iv_bt));
2163 if (bt == BoolTest::le)
2164 bt = BoolTest::lt;
2165 else if (bt == BoolTest::ge)
2166 bt = BoolTest::gt;
2167 else
2168 ShouldNotReachHere();
2169 }
2170 set_subtree_ctrl(adjusted_limit, false);
2171
2172 // Build a canonical trip test.
2173 // Clone code, as old values may be in use.
2174 incr = incr->clone();
2175 incr->set_req(1,phi);
2176 incr->set_req(2,stride);
2177 incr = _igvn.register_new_node_with_optimizer(incr);
2178 set_early_ctrl(incr, false);
2179 _igvn.rehash_node_delayed(phi);
2180 phi->set_req_X( LoopNode::LoopBackControl, incr, &_igvn );
2181
2182 // If phi type is more restrictive than Int, raise to
2183 // Int to prevent (almost) infinite recursion in igvn
2184 // which can only handle integer types for constants or minint..maxint.
2185 if (!TypeInteger::bottom(iv_bt)->higher_equal(phi->bottom_type())) {
2186 Node* nphi = PhiNode::make(phi->in(0), phi->in(LoopNode::EntryControl), TypeInteger::bottom(iv_bt));
2187 nphi->set_req(LoopNode::LoopBackControl, phi->in(LoopNode::LoopBackControl));
2188 nphi = _igvn.register_new_node_with_optimizer(nphi);
2189 set_ctrl(nphi, get_ctrl(phi));
2190 _igvn.replace_node(phi, nphi);
2191 phi = nphi->as_Phi();
2192 }
2193 cmp = cmp->clone();
2194 cmp->set_req(1,incr);
2195 cmp->set_req(2, adjusted_limit);
2196 cmp = _igvn.register_new_node_with_optimizer(cmp);
2197 set_ctrl(cmp, iff->in(0));
2198
2199 test = test->clone()->as_Bool();
2200 (*(BoolTest*)&test->_test)._test = bt;
2201 test->set_req(1,cmp);
2202 _igvn.register_new_node_with_optimizer(test);
2203 set_ctrl(test, iff->in(0));
2204
2205 // Replace the old IfNode with a new LoopEndNode
2206 Node *lex = _igvn.register_new_node_with_optimizer(BaseCountedLoopEndNode::make(iff->in(0), test, cl_prob, iff->as_If()->_fcnt, iv_bt));
2207 IfNode *le = lex->as_If();
2208 uint dd = dom_depth(iff);
2209 set_idom(le, le->in(0), dd); // Update dominance for loop exit
2210 set_loop(le, loop);
2211
2212 // Get the loop-exit control
2213 Node *iffalse = iff->as_If()->proj_out(!(iftrue_op == Op_IfTrue));
2214
2215 // Need to swap loop-exit and loop-back control?
2216 if (iftrue_op == Op_IfFalse) {
2217 Node *ift2=_igvn.register_new_node_with_optimizer(new IfTrueNode (le));
2218 Node *iff2=_igvn.register_new_node_with_optimizer(new IfFalseNode(le));
2219
2220 loop->_tail = back_control = ift2;
2221 set_loop(ift2, loop);
2222 set_loop(iff2, get_loop(iffalse));
2223
2224 // Lazy update of 'get_ctrl' mechanism.
2225 lazy_replace(iffalse, iff2);
2226 lazy_replace(iftrue, ift2);
2227
2228 // Swap names
2229 iffalse = iff2;
2230 iftrue = ift2;
2231 } else {
2232 _igvn.rehash_node_delayed(iffalse);
2233 _igvn.rehash_node_delayed(iftrue);
2234 iffalse->set_req_X( 0, le, &_igvn );
2235 iftrue ->set_req_X( 0, le, &_igvn );
2236 }
2237
2238 set_idom(iftrue, le, dd+1);
2239 set_idom(iffalse, le, dd+1);
2240 assert(iff->outcnt() == 0, "should be dead now");
2241 lazy_replace( iff, le ); // fix 'get_ctrl'
2242
2243 Node* entry_control = init_control;
2244 bool strip_mine_loop = iv_bt == T_INT &&
2245 loop->_child == nullptr &&
2246 sfpt != nullptr &&
2247 !loop->_has_call &&
2248 is_deleteable_safept(sfpt);
2249 IdealLoopTree* outer_ilt = nullptr;
2250 if (strip_mine_loop) {
2251 outer_ilt = create_outer_strip_mined_loop(test, cmp, init_control, loop,
2252 cl_prob, le->_fcnt, entry_control,
2253 iffalse);
2254 }
2255
2256 // Now setup a new CountedLoopNode to replace the existing LoopNode
2257 BaseCountedLoopNode *l = BaseCountedLoopNode::make(entry_control, back_control, iv_bt);
2258 l->set_unswitch_count(x->as_Loop()->unswitch_count()); // Preserve
2259 // The following assert is approximately true, and defines the intention
2260 // of can_be_counted_loop. It fails, however, because phase->type
2261 // is not yet initialized for this loop and its parts.
2262 //assert(l->can_be_counted_loop(this), "sanity");
2263 _igvn.register_new_node_with_optimizer(l);
2264 set_loop(l, loop);
2265 loop->_head = l;
2266 // Fix all data nodes placed at the old loop head.
2267 // Uses the lazy-update mechanism of 'get_ctrl'.
2268 lazy_replace( x, l );
2269 set_idom(l, entry_control, dom_depth(entry_control) + 1);
2270
2271 if (iv_bt == T_INT && (LoopStripMiningIter == 0 || strip_mine_loop)) {
2272 // Check for immediately preceding SafePoint and remove
2273 if (sfpt != nullptr && (strip_mine_loop || is_deleteable_safept(sfpt))) {
2274 if (strip_mine_loop) {
2275 Node* outer_le = outer_ilt->_tail->in(0);
2276 Node* sfpt_clone = sfpt->clone();
2277 sfpt_clone->set_req(0, iffalse);
2278 outer_le->set_req(0, sfpt_clone);
2279
2280 Node* polladdr = sfpt_clone->in(TypeFunc::Parms);
2281 if (polladdr != nullptr && polladdr->is_Load()) {
2282 // Polling load should be pinned outside inner loop.
2283 Node* new_polladdr = polladdr->clone();
2284 new_polladdr->set_req(0, iffalse);
2285 _igvn.register_new_node_with_optimizer(new_polladdr, polladdr);
2286 set_ctrl(new_polladdr, iffalse);
2287 sfpt_clone->set_req(TypeFunc::Parms, new_polladdr);
2288 }
2289 // When this code runs, loop bodies have not yet been populated.
2290 const bool body_populated = false;
2291 register_control(sfpt_clone, outer_ilt, iffalse, body_populated);
2292 set_idom(outer_le, sfpt_clone, dom_depth(sfpt_clone));
2293 }
2294 lazy_replace(sfpt, sfpt->in(TypeFunc::Control));
2295 if (loop->_safepts != nullptr) {
2296 loop->_safepts->yank(sfpt);
2297 }
2298 }
2299 }
2300
2301 #ifdef ASSERT
2302 assert(l->is_valid_counted_loop(iv_bt), "counted loop shape is messed up");
2303 assert(l == loop->_head && l->phi() == phi && l->loopexit_or_null() == lex, "" );
2304 #endif
2305 #ifndef PRODUCT
2306 if (TraceLoopOpts) {
2307 tty->print("Counted ");
2308 loop->dump_head();
2309 }
2310 #endif
2311
2312 C->print_method(PHASE_AFTER_CLOOPS, 3, l);
2313
2314 // Capture bounds of the loop in the induction variable Phi before
2315 // subsequent transformation (iteration splitting) obscures the
2316 // bounds
2317 l->phi()->as_Phi()->set_type(l->phi()->Value(&_igvn));
2318
2319 if (strip_mine_loop) {
2320 l->mark_strip_mined();
2321 l->verify_strip_mined(1);
2322 outer_ilt->_head->as_Loop()->verify_strip_mined(1);
2323 loop = outer_ilt;
2324 }
2325
2326 #ifndef PRODUCT
2327 if (x->as_Loop()->is_loop_nest_inner_loop() && iv_bt == T_LONG) {
2328 Atomic::inc(&_long_loop_counted_loops);
2329 }
2330 #endif
2331 if (iv_bt == T_LONG && x->as_Loop()->is_loop_nest_outer_loop()) {
2332 l->mark_loop_nest_outer_loop();
2333 }
2334
2335 return true;
2336 }
2337
2338 // Check if there is a dominating loop limit check of the form 'init < limit' starting at the loop entry.
2339 // If there is one, then we do not need to create an additional Loop Limit Check Predicate.
2340 bool PhaseIdealLoop::has_dominating_loop_limit_check(Node* init_trip, Node* limit, const jlong stride_con,
2341 const BasicType iv_bt, Node* loop_entry) {
2342 // Eagerly call transform() on the Cmp and Bool node to common them up if possible. This is required in order to
2343 // successfully find a dominated test with the If node below.
2344 Node* cmp_limit;
2345 Node* bol;
2346 if (stride_con > 0) {
2347 cmp_limit = _igvn.transform(CmpNode::make(init_trip, limit, iv_bt));
2348 bol = _igvn.transform(new BoolNode(cmp_limit, BoolTest::lt));
2349 } else {
2350 cmp_limit = _igvn.transform(CmpNode::make(init_trip, limit, iv_bt));
2351 bol = _igvn.transform(new BoolNode(cmp_limit, BoolTest::gt));
2352 }
2353
2354 // Check if there is already a dominating init < limit check. If so, we do not need a Loop Limit Check Predicate.
2355 IfNode* iff = new IfNode(loop_entry, bol, PROB_MIN, COUNT_UNKNOWN);
2356 // Also add fake IfProj nodes in order to call transform() on the newly created IfNode.
2357 IfFalseNode* if_false = new IfFalseNode(iff);
2358 IfTrueNode* if_true = new IfTrueNode(iff);
2359 Node* dominated_iff = _igvn.transform(iff);
2360 // ConI node? Found dominating test (IfNode::dominated_by() returns a ConI node).
2361 const bool found_dominating_test = dominated_iff != nullptr && dominated_iff->is_ConI();
2362
2363 // Kill the If with its projections again in the next IGVN round by cutting it off from the graph.
2364 _igvn.replace_input_of(iff, 0, C->top());
2365 _igvn.replace_input_of(iff, 1, C->top());
2366 return found_dominating_test;
2367 }
2368
2369 //----------------------exact_limit-------------------------------------------
2370 Node* PhaseIdealLoop::exact_limit( IdealLoopTree *loop ) {
2371 assert(loop->_head->is_CountedLoop(), "");
2372 CountedLoopNode *cl = loop->_head->as_CountedLoop();
2373 assert(cl->is_valid_counted_loop(T_INT), "");
2374
2375 if (cl->stride_con() == 1 ||
2376 cl->stride_con() == -1 ||
2377 cl->limit()->Opcode() == Op_LoopLimit) {
2378 // Old code has exact limit (it could be incorrect in case of int overflow).
2379 // Loop limit is exact with stride == 1. And loop may already have exact limit.
2380 return cl->limit();
2381 }
2382 Node *limit = nullptr;
2383 #ifdef ASSERT
2384 BoolTest::mask bt = cl->loopexit()->test_trip();
2385 assert(bt == BoolTest::lt || bt == BoolTest::gt, "canonical test is expected");
2386 #endif
2387 if (cl->has_exact_trip_count()) {
2388 // Simple case: loop has constant boundaries.
2389 // Use jlongs to avoid integer overflow.
2390 int stride_con = cl->stride_con();
2391 jlong init_con = cl->init_trip()->get_int();
2392 jlong limit_con = cl->limit()->get_int();
2393 julong trip_cnt = cl->trip_count();
2394 jlong final_con = init_con + trip_cnt*stride_con;
2395 int final_int = (int)final_con;
2396 // The final value should be in integer range since the loop
2397 // is counted and the limit was checked for overflow.
2398 assert(final_con == (jlong)final_int, "final value should be integer");
2399 limit = _igvn.intcon(final_int);
2400 } else {
2401 // Create new LoopLimit node to get exact limit (final iv value).
2402 limit = new LoopLimitNode(C, cl->init_trip(), cl->limit(), cl->stride());
2403 register_new_node(limit, cl->in(LoopNode::EntryControl));
2404 }
2405 assert(limit != nullptr, "sanity");
2406 return limit;
2407 }
2408
2409 //------------------------------Ideal------------------------------------------
2410 // Return a node which is more "ideal" than the current node.
2411 // Attempt to convert into a counted-loop.
2412 Node *LoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2413 if (!can_be_counted_loop(phase) && !is_OuterStripMinedLoop()) {
2414 phase->C->set_major_progress();
2415 }
2416 return RegionNode::Ideal(phase, can_reshape);
2417 }
2418
2419 #ifdef ASSERT
2420 void LoopNode::verify_strip_mined(int expect_skeleton) const {
2421 const OuterStripMinedLoopNode* outer = nullptr;
2422 const CountedLoopNode* inner = nullptr;
2423 if (is_strip_mined()) {
2424 if (!is_valid_counted_loop(T_INT)) {
2425 return; // Skip malformed counted loop
2426 }
2427 assert(is_CountedLoop(), "no Loop should be marked strip mined");
2428 inner = as_CountedLoop();
2429 outer = inner->in(LoopNode::EntryControl)->as_OuterStripMinedLoop();
2430 } else if (is_OuterStripMinedLoop()) {
2431 outer = this->as_OuterStripMinedLoop();
2432 inner = outer->unique_ctrl_out()->as_CountedLoop();
2433 assert(inner->is_valid_counted_loop(T_INT) && inner->is_strip_mined(), "OuterStripMinedLoop should have been removed");
2434 assert(!is_strip_mined(), "outer loop shouldn't be marked strip mined");
2435 }
2436 if (inner != nullptr || outer != nullptr) {
2437 assert(inner != nullptr && outer != nullptr, "missing loop in strip mined nest");
2438 Node* outer_tail = outer->in(LoopNode::LoopBackControl);
2439 Node* outer_le = outer_tail->in(0);
2440 assert(outer_le->Opcode() == Op_OuterStripMinedLoopEnd, "tail of outer loop should be an If");
2441 Node* sfpt = outer_le->in(0);
2442 assert(sfpt->Opcode() == Op_SafePoint, "where's the safepoint?");
2443 Node* inner_out = sfpt->in(0);
2444 CountedLoopEndNode* cle = inner_out->in(0)->as_CountedLoopEnd();
2445 assert(cle == inner->loopexit_or_null(), "mismatch");
2446 bool has_skeleton = outer_le->in(1)->bottom_type()->singleton() && outer_le->in(1)->bottom_type()->is_int()->get_con() == 0;
2447 if (has_skeleton) {
2448 assert(expect_skeleton == 1 || expect_skeleton == -1, "unexpected skeleton node");
2449 assert(outer->outcnt() == 2, "only control nodes");
2450 } else {
2451 assert(expect_skeleton == 0 || expect_skeleton == -1, "no skeleton node?");
2452 uint phis = 0;
2453 uint be_loads = 0;
2454 Node* be = inner->in(LoopNode::LoopBackControl);
2455 for (DUIterator_Fast imax, i = inner->fast_outs(imax); i < imax; i++) {
2456 Node* u = inner->fast_out(i);
2457 if (u->is_Phi()) {
2458 phis++;
2459 for (DUIterator_Fast jmax, j = be->fast_outs(jmax); j < jmax; j++) {
2460 Node* n = be->fast_out(j);
2461 if (n->is_Load()) {
2462 assert(n->in(0) == be || n->find_prec_edge(be) > 0, "should be on the backedge");
2463 do {
2464 n = n->raw_out(0);
2465 } while (!n->is_Phi());
2466 if (n == u) {
2467 be_loads++;
2468 break;
2469 }
2470 }
2471 }
2472 }
2473 }
2474 assert(be_loads <= phis, "wrong number phis that depends on a pinned load");
2475 for (DUIterator_Fast imax, i = outer->fast_outs(imax); i < imax; i++) {
2476 Node* u = outer->fast_out(i);
2477 assert(u == outer || u == inner || u->is_Phi(), "nothing between inner and outer loop");
2478 }
2479 uint stores = 0;
2480 for (DUIterator_Fast imax, i = inner_out->fast_outs(imax); i < imax; i++) {
2481 Node* u = inner_out->fast_out(i);
2482 if (u->is_Store()) {
2483 stores++;
2484 }
2485 }
2486 // Late optimization of loads on backedge can cause Phi of outer loop to be eliminated but Phi of inner loop is
2487 // not guaranteed to be optimized out.
2488 assert(outer->outcnt() >= phis + 2 - be_loads && outer->outcnt() <= phis + 2 + stores + 1, "only phis");
2489 }
2490 assert(sfpt->outcnt() == 1, "no data node");
2491 assert(outer_tail->outcnt() == 1 || !has_skeleton, "no data node");
2492 }
2493 }
2494 #endif
2495
2496 //=============================================================================
2497 //------------------------------Ideal------------------------------------------
2498 // Return a node which is more "ideal" than the current node.
2499 // Attempt to convert into a counted-loop.
2500 Node *CountedLoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2501 return RegionNode::Ideal(phase, can_reshape);
2502 }
2503
2504 //------------------------------dump_spec--------------------------------------
2505 // Dump special per-node info
2506 #ifndef PRODUCT
2507 void CountedLoopNode::dump_spec(outputStream *st) const {
2508 LoopNode::dump_spec(st);
2509 if (stride_is_con()) {
2510 st->print("stride: %d ",stride_con());
2511 }
2512 if (is_pre_loop ()) st->print("pre of N%d" , _main_idx);
2513 if (is_main_loop()) st->print("main of N%d", _idx);
2514 if (is_post_loop()) st->print("post of N%d", _main_idx);
2515 if (is_strip_mined()) st->print(" strip mined");
2516 }
2517 #endif
2518
2519 //=============================================================================
2520 jlong BaseCountedLoopEndNode::stride_con() const {
2521 return stride()->bottom_type()->is_integer(bt())->get_con_as_long(bt());
2522 }
2523
2524
2525 BaseCountedLoopEndNode* BaseCountedLoopEndNode::make(Node* control, Node* test, float prob, float cnt, BasicType bt) {
2526 if (bt == T_INT) {
2527 return new CountedLoopEndNode(control, test, prob, cnt);
2528 }
2529 assert(bt == T_LONG, "unsupported");
2530 return new LongCountedLoopEndNode(control, test, prob, cnt);
2531 }
2532
2533 //=============================================================================
2534 //------------------------------Value-----------------------------------------
2535 const Type* LoopLimitNode::Value(PhaseGVN* phase) const {
2536 const Type* init_t = phase->type(in(Init));
2537 const Type* limit_t = phase->type(in(Limit));
2538 const Type* stride_t = phase->type(in(Stride));
2539 // Either input is TOP ==> the result is TOP
2540 if (init_t == Type::TOP) return Type::TOP;
2541 if (limit_t == Type::TOP) return Type::TOP;
2542 if (stride_t == Type::TOP) return Type::TOP;
2543
2544 int stride_con = stride_t->is_int()->get_con();
2545 if (stride_con == 1)
2546 return bottom_type(); // Identity
2547
2548 if (init_t->is_int()->is_con() && limit_t->is_int()->is_con()) {
2549 // Use jlongs to avoid integer overflow.
2550 jlong init_con = init_t->is_int()->get_con();
2551 jlong limit_con = limit_t->is_int()->get_con();
2552 int stride_m = stride_con - (stride_con > 0 ? 1 : -1);
2553 jlong trip_count = (limit_con - init_con + stride_m)/stride_con;
2554 jlong final_con = init_con + stride_con*trip_count;
2555 int final_int = (int)final_con;
2556 // The final value should be in integer range since the loop
2557 // is counted and the limit was checked for overflow.
2558 // Assert checks for overflow only if all input nodes are ConINodes, as during CCP
2559 // there might be a temporary overflow from PhiNodes see JDK-8309266
2560 assert((in(Init)->is_ConI() && in(Limit)->is_ConI() && in(Stride)->is_ConI()) ? final_con == (jlong)final_int : true, "final value should be integer");
2561 if (final_con == (jlong)final_int) {
2562 return TypeInt::make(final_int);
2563 } else {
2564 return bottom_type();
2565 }
2566 }
2567
2568 return bottom_type(); // TypeInt::INT
2569 }
2570
2571 //------------------------------Ideal------------------------------------------
2572 // Return a node which is more "ideal" than the current node.
2573 Node *LoopLimitNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2574 if (phase->type(in(Init)) == Type::TOP ||
2575 phase->type(in(Limit)) == Type::TOP ||
2576 phase->type(in(Stride)) == Type::TOP)
2577 return nullptr; // Dead
2578
2579 int stride_con = phase->type(in(Stride))->is_int()->get_con();
2580 if (stride_con == 1)
2581 return nullptr; // Identity
2582
2583 if (in(Init)->is_Con() && in(Limit)->is_Con())
2584 return nullptr; // Value
2585
2586 // Delay following optimizations until all loop optimizations
2587 // done to keep Ideal graph simple.
2588 if (!can_reshape || !phase->C->post_loop_opts_phase()) {
2589 return nullptr;
2590 }
2591
2592 const TypeInt* init_t = phase->type(in(Init) )->is_int();
2593 const TypeInt* limit_t = phase->type(in(Limit))->is_int();
2594 int stride_p;
2595 jlong lim, ini;
2596 julong max;
2597 if (stride_con > 0) {
2598 stride_p = stride_con;
2599 lim = limit_t->_hi;
2600 ini = init_t->_lo;
2601 max = (julong)max_jint;
2602 } else {
2603 stride_p = -stride_con;
2604 lim = init_t->_hi;
2605 ini = limit_t->_lo;
2606 max = (julong)min_jint;
2607 }
2608 julong range = lim - ini + stride_p;
2609 if (range <= max) {
2610 // Convert to integer expression if it is not overflow.
2611 Node* stride_m = phase->intcon(stride_con - (stride_con > 0 ? 1 : -1));
2612 Node *range = phase->transform(new SubINode(in(Limit), in(Init)));
2613 Node *bias = phase->transform(new AddINode(range, stride_m));
2614 Node *trip = phase->transform(new DivINode(nullptr, bias, in(Stride)));
2615 Node *span = phase->transform(new MulINode(trip, in(Stride)));
2616 return new AddINode(span, in(Init)); // exact limit
2617 }
2618
2619 if (is_power_of_2(stride_p) || // divisor is 2^n
2620 !Matcher::has_match_rule(Op_LoopLimit)) { // or no specialized Mach node?
2621 // Convert to long expression to avoid integer overflow
2622 // and let igvn optimizer convert this division.
2623 //
2624 Node* init = phase->transform( new ConvI2LNode(in(Init)));
2625 Node* limit = phase->transform( new ConvI2LNode(in(Limit)));
2626 Node* stride = phase->longcon(stride_con);
2627 Node* stride_m = phase->longcon(stride_con - (stride_con > 0 ? 1 : -1));
2628
2629 Node *range = phase->transform(new SubLNode(limit, init));
2630 Node *bias = phase->transform(new AddLNode(range, stride_m));
2631 Node *span;
2632 if (stride_con > 0 && is_power_of_2(stride_p)) {
2633 // bias >= 0 if stride >0, so if stride is 2^n we can use &(-stride)
2634 // and avoid generating rounding for division. Zero trip guard should
2635 // guarantee that init < limit but sometimes the guard is missing and
2636 // we can get situation when init > limit. Note, for the empty loop
2637 // optimization zero trip guard is generated explicitly which leaves
2638 // only RCE predicate where exact limit is used and the predicate
2639 // will simply fail forcing recompilation.
2640 Node* neg_stride = phase->longcon(-stride_con);
2641 span = phase->transform(new AndLNode(bias, neg_stride));
2642 } else {
2643 Node *trip = phase->transform(new DivLNode(nullptr, bias, stride));
2644 span = phase->transform(new MulLNode(trip, stride));
2645 }
2646 // Convert back to int
2647 Node *span_int = phase->transform(new ConvL2INode(span));
2648 return new AddINode(span_int, in(Init)); // exact limit
2649 }
2650
2651 return nullptr; // No progress
2652 }
2653
2654 //------------------------------Identity---------------------------------------
2655 // If stride == 1 return limit node.
2656 Node* LoopLimitNode::Identity(PhaseGVN* phase) {
2657 int stride_con = phase->type(in(Stride))->is_int()->get_con();
2658 if (stride_con == 1 || stride_con == -1)
2659 return in(Limit);
2660 return this;
2661 }
2662
2663 //=============================================================================
2664 //----------------------match_incr_with_optional_truncation--------------------
2665 // Match increment with optional truncation:
2666 // CHAR: (i+1)&0x7fff, BYTE: ((i+1)<<8)>>8, or SHORT: ((i+1)<<16)>>16
2667 // Return null for failure. Success returns the increment node.
2668 Node* CountedLoopNode::match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2,
2669 const TypeInteger** trunc_type,
2670 BasicType bt) {
2671 // Quick cutouts:
2672 if (expr == nullptr || expr->req() != 3) return nullptr;
2673
2674 Node *t1 = nullptr;
2675 Node *t2 = nullptr;
2676 Node* n1 = expr;
2677 int n1op = n1->Opcode();
2678 const TypeInteger* trunc_t = TypeInteger::bottom(bt);
2679
2680 if (bt == T_INT) {
2681 // Try to strip (n1 & M) or (n1 << N >> N) from n1.
2682 if (n1op == Op_AndI &&
2683 n1->in(2)->is_Con() &&
2684 n1->in(2)->bottom_type()->is_int()->get_con() == 0x7fff) {
2685 // %%% This check should match any mask of 2**K-1.
2686 t1 = n1;
2687 n1 = t1->in(1);
2688 n1op = n1->Opcode();
2689 trunc_t = TypeInt::CHAR;
2690 } else if (n1op == Op_RShiftI &&
2691 n1->in(1) != nullptr &&
2692 n1->in(1)->Opcode() == Op_LShiftI &&
2693 n1->in(2) == n1->in(1)->in(2) &&
2694 n1->in(2)->is_Con()) {
2695 jint shift = n1->in(2)->bottom_type()->is_int()->get_con();
2696 // %%% This check should match any shift in [1..31].
2697 if (shift == 16 || shift == 8) {
2698 t1 = n1;
2699 t2 = t1->in(1);
2700 n1 = t2->in(1);
2701 n1op = n1->Opcode();
2702 if (shift == 16) {
2703 trunc_t = TypeInt::SHORT;
2704 } else if (shift == 8) {
2705 trunc_t = TypeInt::BYTE;
2706 }
2707 }
2708 }
2709 }
2710
2711 // If (maybe after stripping) it is an AddI, we won:
2712 if (n1op == Op_Add(bt)) {
2713 *trunc1 = t1;
2714 *trunc2 = t2;
2715 *trunc_type = trunc_t;
2716 return n1;
2717 }
2718
2719 // failed
2720 return nullptr;
2721 }
2722
2723 LoopNode* CountedLoopNode::skip_strip_mined(int expect_skeleton) {
2724 if (is_strip_mined() && in(EntryControl) != nullptr && in(EntryControl)->is_OuterStripMinedLoop()) {
2725 verify_strip_mined(expect_skeleton);
2726 return in(EntryControl)->as_Loop();
2727 }
2728 return this;
2729 }
2730
2731 OuterStripMinedLoopNode* CountedLoopNode::outer_loop() const {
2732 assert(is_strip_mined(), "not a strip mined loop");
2733 Node* c = in(EntryControl);
2734 if (c == nullptr || c->is_top() || !c->is_OuterStripMinedLoop()) {
2735 return nullptr;
2736 }
2737 return c->as_OuterStripMinedLoop();
2738 }
2739
2740 IfTrueNode* OuterStripMinedLoopNode::outer_loop_tail() const {
2741 Node* c = in(LoopBackControl);
2742 if (c == nullptr || c->is_top()) {
2743 return nullptr;
2744 }
2745 return c->as_IfTrue();
2746 }
2747
2748 IfTrueNode* CountedLoopNode::outer_loop_tail() const {
2749 LoopNode* l = outer_loop();
2750 if (l == nullptr) {
2751 return nullptr;
2752 }
2753 return l->outer_loop_tail();
2754 }
2755
2756 OuterStripMinedLoopEndNode* OuterStripMinedLoopNode::outer_loop_end() const {
2757 IfTrueNode* proj = outer_loop_tail();
2758 if (proj == nullptr) {
2759 return nullptr;
2760 }
2761 Node* c = proj->in(0);
2762 if (c == nullptr || c->is_top() || c->outcnt() != 2) {
2763 return nullptr;
2764 }
2765 return c->as_OuterStripMinedLoopEnd();
2766 }
2767
2768 OuterStripMinedLoopEndNode* CountedLoopNode::outer_loop_end() const {
2769 LoopNode* l = outer_loop();
2770 if (l == nullptr) {
2771 return nullptr;
2772 }
2773 return l->outer_loop_end();
2774 }
2775
2776 IfFalseNode* OuterStripMinedLoopNode::outer_loop_exit() const {
2777 IfNode* le = outer_loop_end();
2778 if (le == nullptr) {
2779 return nullptr;
2780 }
2781 Node* c = le->proj_out_or_null(false);
2782 if (c == nullptr) {
2783 return nullptr;
2784 }
2785 return c->as_IfFalse();
2786 }
2787
2788 IfFalseNode* CountedLoopNode::outer_loop_exit() const {
2789 LoopNode* l = outer_loop();
2790 if (l == nullptr) {
2791 return nullptr;
2792 }
2793 return l->outer_loop_exit();
2794 }
2795
2796 SafePointNode* OuterStripMinedLoopNode::outer_safepoint() const {
2797 IfNode* le = outer_loop_end();
2798 if (le == nullptr) {
2799 return nullptr;
2800 }
2801 Node* c = le->in(0);
2802 if (c == nullptr || c->is_top()) {
2803 return nullptr;
2804 }
2805 assert(c->Opcode() == Op_SafePoint, "broken outer loop");
2806 return c->as_SafePoint();
2807 }
2808
2809 SafePointNode* CountedLoopNode::outer_safepoint() const {
2810 LoopNode* l = outer_loop();
2811 if (l == nullptr) {
2812 return nullptr;
2813 }
2814 return l->outer_safepoint();
2815 }
2816
2817 Node* CountedLoopNode::skip_assertion_predicates_with_halt() {
2818 Node* ctrl = in(LoopNode::EntryControl);
2819 if (is_main_loop()) {
2820 ctrl = skip_strip_mined()->in(LoopNode::EntryControl);
2821 }
2822 if (is_main_loop() || is_post_loop()) {
2823 AssertionPredicatesWithHalt assertion_predicates(ctrl);
2824 return assertion_predicates.entry();
2825 }
2826 return ctrl;
2827 }
2828
2829
2830 int CountedLoopNode::stride_con() const {
2831 CountedLoopEndNode* cle = loopexit_or_null();
2832 return cle != nullptr ? cle->stride_con() : 0;
2833 }
2834
2835 BaseCountedLoopNode* BaseCountedLoopNode::make(Node* entry, Node* backedge, BasicType bt) {
2836 if (bt == T_INT) {
2837 return new CountedLoopNode(entry, backedge);
2838 }
2839 assert(bt == T_LONG, "unsupported");
2840 return new LongCountedLoopNode(entry, backedge);
2841 }
2842
2843 void OuterStripMinedLoopNode::fix_sunk_stores(CountedLoopEndNode* inner_cle, LoopNode* inner_cl, PhaseIterGVN* igvn,
2844 PhaseIdealLoop* iloop) {
2845 Node* cle_out = inner_cle->proj_out(false);
2846 Node* cle_tail = inner_cle->proj_out(true);
2847 if (cle_out->outcnt() > 1) {
2848 // Look for chains of stores that were sunk
2849 // out of the inner loop and are in the outer loop
2850 for (DUIterator_Fast imax, i = cle_out->fast_outs(imax); i < imax; i++) {
2851 Node* u = cle_out->fast_out(i);
2852 if (u->is_Store()) {
2853 int alias_idx = igvn->C->get_alias_index(u->adr_type());
2854 Node* first = u;
2855 for (;;) {
2856 Node* next = first->in(MemNode::Memory);
2857 if (!next->is_Store() || next->in(0) != cle_out) {
2858 break;
2859 }
2860 assert(igvn->C->get_alias_index(next->adr_type()) == alias_idx, "");
2861 first = next;
2862 }
2863 Node* last = u;
2864 for (;;) {
2865 Node* next = nullptr;
2866 for (DUIterator_Fast jmax, j = last->fast_outs(jmax); j < jmax; j++) {
2867 Node* uu = last->fast_out(j);
2868 if (uu->is_Store() && uu->in(0) == cle_out) {
2869 assert(next == nullptr, "only one in the outer loop");
2870 next = uu;
2871 assert(igvn->C->get_alias_index(next->adr_type()) == alias_idx, "");
2872 }
2873 }
2874 if (next == nullptr) {
2875 break;
2876 }
2877 last = next;
2878 }
2879 Node* phi = nullptr;
2880 for (DUIterator_Fast jmax, j = inner_cl->fast_outs(jmax); j < jmax; j++) {
2881 Node* uu = inner_cl->fast_out(j);
2882 if (uu->is_Phi()) {
2883 Node* be = uu->in(LoopNode::LoopBackControl);
2884 if (be->is_Store() && be->in(0) == inner_cl->in(LoopNode::LoopBackControl)) {
2885 assert(igvn->C->get_alias_index(uu->adr_type()) != alias_idx && igvn->C->get_alias_index(uu->adr_type()) != Compile::AliasIdxBot, "unexpected store");
2886 }
2887 if (be == last || be == first->in(MemNode::Memory)) {
2888 assert(igvn->C->get_alias_index(uu->adr_type()) == alias_idx || igvn->C->get_alias_index(uu->adr_type()) == Compile::AliasIdxBot, "unexpected alias");
2889 assert(phi == nullptr, "only one phi");
2890 phi = uu;
2891 }
2892 }
2893 }
2894 #ifdef ASSERT
2895 for (DUIterator_Fast jmax, j = inner_cl->fast_outs(jmax); j < jmax; j++) {
2896 Node* uu = inner_cl->fast_out(j);
2897 if (uu->is_memory_phi()) {
2898 if (uu->adr_type() == igvn->C->get_adr_type(igvn->C->get_alias_index(u->adr_type()))) {
2899 assert(phi == uu, "what's that phi?");
2900 } else if (uu->adr_type() == TypePtr::BOTTOM) {
2901 Node* n = uu->in(LoopNode::LoopBackControl);
2902 uint limit = igvn->C->live_nodes();
2903 uint i = 0;
2904 while (n != uu) {
2905 i++;
2906 assert(i < limit, "infinite loop");
2907 if (n->is_Proj()) {
2908 n = n->in(0);
2909 } else if (n->is_SafePoint() || n->is_MemBar()) {
2910 n = n->in(TypeFunc::Memory);
2911 } else if (n->is_Phi()) {
2912 n = n->in(1);
2913 } else if (n->is_MergeMem()) {
2914 n = n->as_MergeMem()->memory_at(igvn->C->get_alias_index(u->adr_type()));
2915 } else if (n->is_Store() || n->is_LoadStore() || n->is_ClearArray()) {
2916 n = n->in(MemNode::Memory);
2917 } else {
2918 n->dump();
2919 ShouldNotReachHere();
2920 }
2921 }
2922 }
2923 }
2924 }
2925 #endif
2926 if (phi == nullptr) {
2927 // If an entire chains was sunk, the
2928 // inner loop has no phi for that memory
2929 // slice, create one for the outer loop
2930 phi = PhiNode::make(inner_cl, first->in(MemNode::Memory), Type::MEMORY,
2931 igvn->C->get_adr_type(igvn->C->get_alias_index(u->adr_type())));
2932 phi->set_req(LoopNode::LoopBackControl, last);
2933 phi = register_new_node(phi, inner_cl, igvn, iloop);
2934 igvn->replace_input_of(first, MemNode::Memory, phi);
2935 } else {
2936 // Or fix the outer loop fix to include
2937 // that chain of stores.
2938 Node* be = phi->in(LoopNode::LoopBackControl);
2939 assert(!(be->is_Store() && be->in(0) == inner_cl->in(LoopNode::LoopBackControl)), "store on the backedge + sunk stores: unsupported");
2940 if (be == first->in(MemNode::Memory)) {
2941 if (be == phi->in(LoopNode::LoopBackControl)) {
2942 igvn->replace_input_of(phi, LoopNode::LoopBackControl, last);
2943 } else {
2944 igvn->replace_input_of(be, MemNode::Memory, last);
2945 }
2946 } else {
2947 #ifdef ASSERT
2948 if (be == phi->in(LoopNode::LoopBackControl)) {
2949 assert(phi->in(LoopNode::LoopBackControl) == last, "");
2950 } else {
2951 assert(be->in(MemNode::Memory) == last, "");
2952 }
2953 #endif
2954 }
2955 }
2956 }
2957 }
2958 }
2959 }
2960
2961 void OuterStripMinedLoopNode::adjust_strip_mined_loop(PhaseIterGVN* igvn) {
2962 // Look for the outer & inner strip mined loop, reduce number of
2963 // iterations of the inner loop, set exit condition of outer loop,
2964 // construct required phi nodes for outer loop.
2965 CountedLoopNode* inner_cl = unique_ctrl_out()->as_CountedLoop();
2966 assert(inner_cl->is_strip_mined(), "inner loop should be strip mined");
2967 if (LoopStripMiningIter == 0) {
2968 remove_outer_loop_and_safepoint(igvn);
2969 return;
2970 }
2971 if (LoopStripMiningIter == 1) {
2972 transform_to_counted_loop(igvn, nullptr);
2973 return;
2974 }
2975 Node* inner_iv_phi = inner_cl->phi();
2976 if (inner_iv_phi == nullptr) {
2977 IfNode* outer_le = outer_loop_end();
2978 Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt));
2979 igvn->replace_node(outer_le, iff);
2980 inner_cl->clear_strip_mined();
2981 return;
2982 }
2983 CountedLoopEndNode* inner_cle = inner_cl->loopexit();
2984
2985 int stride = inner_cl->stride_con();
2986 // For a min int stride, LoopStripMiningIter * stride overflows the int range for all values of LoopStripMiningIter
2987 // except 0 or 1. Those values are handled early on in this method and causes the method to return. So for a min int
2988 // stride, the method is guaranteed to return at the next check below.
2989 jlong scaled_iters_long = ((jlong)LoopStripMiningIter) * ABS((jlong)stride);
2990 int scaled_iters = (int)scaled_iters_long;
2991 if ((jlong)scaled_iters != scaled_iters_long) {
2992 // Remove outer loop and safepoint (too few iterations)
2993 remove_outer_loop_and_safepoint(igvn);
2994 return;
2995 }
2996 jlong short_scaled_iters = LoopStripMiningIterShortLoop * ABS(stride);
2997 const TypeInt* inner_iv_t = igvn->type(inner_iv_phi)->is_int();
2998 jlong iter_estimate = (jlong)inner_iv_t->_hi - (jlong)inner_iv_t->_lo;
2999 assert(iter_estimate > 0, "broken");
3000 if (iter_estimate <= short_scaled_iters) {
3001 // Remove outer loop and safepoint: loop executes less than LoopStripMiningIterShortLoop
3002 remove_outer_loop_and_safepoint(igvn);
3003 return;
3004 }
3005 if (iter_estimate <= scaled_iters_long) {
3006 // We would only go through one iteration of
3007 // the outer loop: drop the outer loop but
3008 // keep the safepoint so we don't run for
3009 // too long without a safepoint
3010 IfNode* outer_le = outer_loop_end();
3011 Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt));
3012 igvn->replace_node(outer_le, iff);
3013 inner_cl->clear_strip_mined();
3014 return;
3015 }
3016
3017 Node* cle_tail = inner_cle->proj_out(true);
3018 ResourceMark rm;
3019 Node_List old_new;
3020 if (cle_tail->outcnt() > 1) {
3021 // Look for nodes on backedge of inner loop and clone them
3022 Unique_Node_List backedge_nodes;
3023 for (DUIterator_Fast imax, i = cle_tail->fast_outs(imax); i < imax; i++) {
3024 Node* u = cle_tail->fast_out(i);
3025 if (u != inner_cl) {
3026 assert(!u->is_CFG(), "control flow on the backedge?");
3027 backedge_nodes.push(u);
3028 }
3029 }
3030 uint last = igvn->C->unique();
3031 for (uint next = 0; next < backedge_nodes.size(); next++) {
3032 Node* n = backedge_nodes.at(next);
3033 old_new.map(n->_idx, n->clone());
3034 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
3035 Node* u = n->fast_out(i);
3036 assert(!u->is_CFG(), "broken");
3037 if (u->_idx >= last) {
3038 continue;
3039 }
3040 if (!u->is_Phi()) {
3041 backedge_nodes.push(u);
3042 } else {
3043 assert(u->in(0) == inner_cl, "strange phi on the backedge");
3044 }
3045 }
3046 }
3047 // Put the clones on the outer loop backedge
3048 Node* le_tail = outer_loop_tail();
3049 for (uint next = 0; next < backedge_nodes.size(); next++) {
3050 Node *n = old_new[backedge_nodes.at(next)->_idx];
3051 for (uint i = 1; i < n->req(); i++) {
3052 if (n->in(i) != nullptr && old_new[n->in(i)->_idx] != nullptr) {
3053 n->set_req(i, old_new[n->in(i)->_idx]);
3054 }
3055 }
3056 if (n->in(0) != nullptr && n->in(0) == cle_tail) {
3057 n->set_req(0, le_tail);
3058 }
3059 igvn->register_new_node_with_optimizer(n);
3060 }
3061 }
3062
3063 Node* iv_phi = nullptr;
3064 // Make a clone of each phi in the inner loop
3065 // for the outer loop
3066 for (uint i = 0; i < inner_cl->outcnt(); i++) {
3067 Node* u = inner_cl->raw_out(i);
3068 if (u->is_Phi()) {
3069 assert(u->in(0) == inner_cl, "inconsistent");
3070 Node* phi = u->clone();
3071 phi->set_req(0, this);
3072 Node* be = old_new[phi->in(LoopNode::LoopBackControl)->_idx];
3073 if (be != nullptr) {
3074 phi->set_req(LoopNode::LoopBackControl, be);
3075 }
3076 phi = igvn->transform(phi);
3077 igvn->replace_input_of(u, LoopNode::EntryControl, phi);
3078 if (u == inner_iv_phi) {
3079 iv_phi = phi;
3080 }
3081 }
3082 }
3083
3084 if (iv_phi != nullptr) {
3085 // Now adjust the inner loop's exit condition
3086 Node* limit = inner_cl->limit();
3087 // If limit < init for stride > 0 (or limit > init for stride < 0),
3088 // the loop body is run only once. Given limit - init (init - limit resp.)
3089 // would be negative, the unsigned comparison below would cause
3090 // the loop body to be run for LoopStripMiningIter.
3091 Node* max = nullptr;
3092 if (stride > 0) {
3093 max = MaxNode::max_diff_with_zero(limit, iv_phi, TypeInt::INT, *igvn);
3094 } else {
3095 max = MaxNode::max_diff_with_zero(iv_phi, limit, TypeInt::INT, *igvn);
3096 }
3097 // sub is positive and can be larger than the max signed int
3098 // value. Use an unsigned min.
3099 Node* const_iters = igvn->intcon(scaled_iters);
3100 Node* min = MaxNode::unsigned_min(max, const_iters, TypeInt::make(0, scaled_iters, Type::WidenMin), *igvn);
3101 // min is the number of iterations for the next inner loop execution:
3102 // unsigned_min(max(limit - iv_phi, 0), scaled_iters) if stride > 0
3103 // unsigned_min(max(iv_phi - limit, 0), scaled_iters) if stride < 0
3104
3105 Node* new_limit = nullptr;
3106 if (stride > 0) {
3107 new_limit = igvn->transform(new AddINode(min, iv_phi));
3108 } else {
3109 new_limit = igvn->transform(new SubINode(iv_phi, min));
3110 }
3111 Node* inner_cmp = inner_cle->cmp_node();
3112 Node* inner_bol = inner_cle->in(CountedLoopEndNode::TestValue);
3113 Node* outer_bol = inner_bol;
3114 // cmp node for inner loop may be shared
3115 inner_cmp = inner_cmp->clone();
3116 inner_cmp->set_req(2, new_limit);
3117 inner_bol = inner_bol->clone();
3118 inner_bol->set_req(1, igvn->transform(inner_cmp));
3119 igvn->replace_input_of(inner_cle, CountedLoopEndNode::TestValue, igvn->transform(inner_bol));
3120 // Set the outer loop's exit condition too
3121 igvn->replace_input_of(outer_loop_end(), 1, outer_bol);
3122 } else {
3123 assert(false, "should be able to adjust outer loop");
3124 IfNode* outer_le = outer_loop_end();
3125 Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt));
3126 igvn->replace_node(outer_le, iff);
3127 inner_cl->clear_strip_mined();
3128 }
3129 }
3130
3131 void OuterStripMinedLoopNode::transform_to_counted_loop(PhaseIterGVN* igvn, PhaseIdealLoop* iloop) {
3132 CountedLoopNode* inner_cl = unique_ctrl_out()->as_CountedLoop();
3133 CountedLoopEndNode* cle = inner_cl->loopexit();
3134 Node* inner_test = cle->in(1);
3135 IfNode* outer_le = outer_loop_end();
3136 CountedLoopEndNode* inner_cle = inner_cl->loopexit();
3137 Node* safepoint = outer_safepoint();
3138
3139 fix_sunk_stores(inner_cle, inner_cl, igvn, iloop);
3140
3141 // make counted loop exit test always fail
3142 ConINode* zero = igvn->intcon(0);
3143 if (iloop != nullptr) {
3144 iloop->set_ctrl(zero, igvn->C->root());
3145 }
3146 igvn->replace_input_of(cle, 1, zero);
3147 // replace outer loop end with CountedLoopEndNode with formers' CLE's exit test
3148 Node* new_end = new CountedLoopEndNode(outer_le->in(0), inner_test, cle->_prob, cle->_fcnt);
3149 register_control(new_end, inner_cl, outer_le->in(0), igvn, iloop);
3150 if (iloop == nullptr) {
3151 igvn->replace_node(outer_le, new_end);
3152 } else {
3153 iloop->lazy_replace(outer_le, new_end);
3154 }
3155 // the backedge of the inner loop must be rewired to the new loop end
3156 Node* backedge = cle->proj_out(true);
3157 igvn->replace_input_of(backedge, 0, new_end);
3158 if (iloop != nullptr) {
3159 iloop->set_idom(backedge, new_end, iloop->dom_depth(new_end) + 1);
3160 }
3161 // make the outer loop go away
3162 igvn->replace_input_of(in(LoopBackControl), 0, igvn->C->top());
3163 igvn->replace_input_of(this, LoopBackControl, igvn->C->top());
3164 inner_cl->clear_strip_mined();
3165 if (iloop != nullptr) {
3166 Unique_Node_List wq;
3167 wq.push(safepoint);
3168
3169 IdealLoopTree* outer_loop_ilt = iloop->get_loop(this);
3170 IdealLoopTree* loop = iloop->get_loop(inner_cl);
3171
3172 for (uint i = 0; i < wq.size(); i++) {
3173 Node* n = wq.at(i);
3174 for (uint j = 0; j < n->req(); ++j) {
3175 Node* in = n->in(j);
3176 if (in == nullptr || in->is_CFG()) {
3177 continue;
3178 }
3179 if (iloop->get_loop(iloop->get_ctrl(in)) != outer_loop_ilt) {
3180 continue;
3181 }
3182 assert(!loop->_body.contains(in), "");
3183 loop->_body.push(in);
3184 wq.push(in);
3185 }
3186 }
3187 iloop->set_loop(safepoint, loop);
3188 loop->_body.push(safepoint);
3189 iloop->set_loop(safepoint->in(0), loop);
3190 loop->_body.push(safepoint->in(0));
3191 outer_loop_ilt->_tail = igvn->C->top();
3192 }
3193 }
3194
3195 void OuterStripMinedLoopNode::remove_outer_loop_and_safepoint(PhaseIterGVN* igvn) const {
3196 CountedLoopNode* inner_cl = unique_ctrl_out()->as_CountedLoop();
3197 Node* outer_sfpt = outer_safepoint();
3198 Node* outer_out = outer_loop_exit();
3199 igvn->replace_node(outer_out, outer_sfpt->in(0));
3200 igvn->replace_input_of(outer_sfpt, 0, igvn->C->top());
3201 inner_cl->clear_strip_mined();
3202 }
3203
3204 Node* OuterStripMinedLoopNode::register_new_node(Node* node, LoopNode* ctrl, PhaseIterGVN* igvn, PhaseIdealLoop* iloop) {
3205 if (iloop == nullptr) {
3206 return igvn->transform(node);
3207 }
3208 iloop->register_new_node(node, ctrl);
3209 return node;
3210 }
3211
3212 Node* OuterStripMinedLoopNode::register_control(Node* node, Node* loop, Node* idom, PhaseIterGVN* igvn,
3213 PhaseIdealLoop* iloop) {
3214 if (iloop == nullptr) {
3215 return igvn->transform(node);
3216 }
3217 iloop->register_control(node, iloop->get_loop(loop), idom);
3218 return node;
3219 }
3220
3221 const Type* OuterStripMinedLoopEndNode::Value(PhaseGVN* phase) const {
3222 if (!in(0)) return Type::TOP;
3223 if (phase->type(in(0)) == Type::TOP)
3224 return Type::TOP;
3225
3226 // Until expansion, the loop end condition is not set so this should not constant fold.
3227 if (is_expanded(phase)) {
3228 return IfNode::Value(phase);
3229 }
3230
3231 return TypeTuple::IFBOTH;
3232 }
3233
3234 bool OuterStripMinedLoopEndNode::is_expanded(PhaseGVN *phase) const {
3235 // The outer strip mined loop head only has Phi uses after expansion
3236 if (phase->is_IterGVN()) {
3237 Node* backedge = proj_out_or_null(true);
3238 if (backedge != nullptr) {
3239 Node* head = backedge->unique_ctrl_out_or_null();
3240 if (head != nullptr && head->is_OuterStripMinedLoop()) {
3241 if (head->find_out_with(Op_Phi) != nullptr) {
3242 return true;
3243 }
3244 }
3245 }
3246 }
3247 return false;
3248 }
3249
3250 Node *OuterStripMinedLoopEndNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3251 if (remove_dead_region(phase, can_reshape)) return this;
3252
3253 return nullptr;
3254 }
3255
3256 //------------------------------filtered_type--------------------------------
3257 // Return a type based on condition control flow
3258 // A successful return will be a type that is restricted due
3259 // to a series of dominating if-tests, such as:
3260 // if (i < 10) {
3261 // if (i > 0) {
3262 // here: "i" type is [1..10)
3263 // }
3264 // }
3265 // or a control flow merge
3266 // if (i < 10) {
3267 // do {
3268 // phi( , ) -- at top of loop type is [min_int..10)
3269 // i = ?
3270 // } while ( i < 10)
3271 //
3272 const TypeInt* PhaseIdealLoop::filtered_type( Node *n, Node* n_ctrl) {
3273 assert(n && n->bottom_type()->is_int(), "must be int");
3274 const TypeInt* filtered_t = nullptr;
3275 if (!n->is_Phi()) {
3276 assert(n_ctrl != nullptr || n_ctrl == C->top(), "valid control");
3277 filtered_t = filtered_type_from_dominators(n, n_ctrl);
3278
3279 } else {
3280 Node* phi = n->as_Phi();
3281 Node* region = phi->in(0);
3282 assert(n_ctrl == nullptr || n_ctrl == region, "ctrl parameter must be region");
3283 if (region && region != C->top()) {
3284 for (uint i = 1; i < phi->req(); i++) {
3285 Node* val = phi->in(i);
3286 Node* use_c = region->in(i);
3287 const TypeInt* val_t = filtered_type_from_dominators(val, use_c);
3288 if (val_t != nullptr) {
3289 if (filtered_t == nullptr) {
3290 filtered_t = val_t;
3291 } else {
3292 filtered_t = filtered_t->meet(val_t)->is_int();
3293 }
3294 }
3295 }
3296 }
3297 }
3298 const TypeInt* n_t = _igvn.type(n)->is_int();
3299 if (filtered_t != nullptr) {
3300 n_t = n_t->join(filtered_t)->is_int();
3301 }
3302 return n_t;
3303 }
3304
3305
3306 //------------------------------filtered_type_from_dominators--------------------------------
3307 // Return a possibly more restrictive type for val based on condition control flow of dominators
3308 const TypeInt* PhaseIdealLoop::filtered_type_from_dominators( Node* val, Node *use_ctrl) {
3309 if (val->is_Con()) {
3310 return val->bottom_type()->is_int();
3311 }
3312 uint if_limit = 10; // Max number of dominating if's visited
3313 const TypeInt* rtn_t = nullptr;
3314
3315 if (use_ctrl && use_ctrl != C->top()) {
3316 Node* val_ctrl = get_ctrl(val);
3317 uint val_dom_depth = dom_depth(val_ctrl);
3318 Node* pred = use_ctrl;
3319 uint if_cnt = 0;
3320 while (if_cnt < if_limit) {
3321 if ((pred->Opcode() == Op_IfTrue || pred->Opcode() == Op_IfFalse)) {
3322 if_cnt++;
3323 const TypeInt* if_t = IfNode::filtered_int_type(&_igvn, val, pred);
3324 if (if_t != nullptr) {
3325 if (rtn_t == nullptr) {
3326 rtn_t = if_t;
3327 } else {
3328 rtn_t = rtn_t->join(if_t)->is_int();
3329 }
3330 }
3331 }
3332 pred = idom(pred);
3333 if (pred == nullptr || pred == C->top()) {
3334 break;
3335 }
3336 // Stop if going beyond definition block of val
3337 if (dom_depth(pred) < val_dom_depth) {
3338 break;
3339 }
3340 }
3341 }
3342 return rtn_t;
3343 }
3344
3345
3346 //------------------------------dump_spec--------------------------------------
3347 // Dump special per-node info
3348 #ifndef PRODUCT
3349 void CountedLoopEndNode::dump_spec(outputStream *st) const {
3350 if( in(TestValue) != nullptr && in(TestValue)->is_Bool() ) {
3351 BoolTest bt( test_trip()); // Added this for g++.
3352
3353 st->print("[");
3354 bt.dump_on(st);
3355 st->print("]");
3356 }
3357 st->print(" ");
3358 IfNode::dump_spec(st);
3359 }
3360 #endif
3361
3362 //=============================================================================
3363 //------------------------------is_member--------------------------------------
3364 // Is 'l' a member of 'this'?
3365 bool IdealLoopTree::is_member(const IdealLoopTree *l) const {
3366 while( l->_nest > _nest ) l = l->_parent;
3367 return l == this;
3368 }
3369
3370 //------------------------------set_nest---------------------------------------
3371 // Set loop tree nesting depth. Accumulate _has_call bits.
3372 int IdealLoopTree::set_nest( uint depth ) {
3373 assert(depth <= SHRT_MAX, "sanity");
3374 _nest = depth;
3375 int bits = _has_call;
3376 if( _child ) bits |= _child->set_nest(depth+1);
3377 if( bits ) _has_call = 1;
3378 if( _next ) bits |= _next ->set_nest(depth );
3379 return bits;
3380 }
3381
3382 //------------------------------split_fall_in----------------------------------
3383 // Split out multiple fall-in edges from the loop header. Move them to a
3384 // private RegionNode before the loop. This becomes the loop landing pad.
3385 void IdealLoopTree::split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ) {
3386 PhaseIterGVN &igvn = phase->_igvn;
3387 uint i;
3388
3389 // Make a new RegionNode to be the landing pad.
3390 RegionNode* landing_pad = new RegionNode(fall_in_cnt + 1);
3391 phase->set_loop(landing_pad,_parent);
3392 // If _head was irreducible loop entry, landing_pad may now be too
3393 landing_pad->set_loop_status(_head->as_Region()->loop_status());
3394 // Gather all the fall-in control paths into the landing pad
3395 uint icnt = fall_in_cnt;
3396 uint oreq = _head->req();
3397 for( i = oreq-1; i>0; i-- )
3398 if( !phase->is_member( this, _head->in(i) ) )
3399 landing_pad->set_req(icnt--,_head->in(i));
3400
3401 // Peel off PhiNode edges as well
3402 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
3403 Node *oj = _head->fast_out(j);
3404 if( oj->is_Phi() ) {
3405 PhiNode* old_phi = oj->as_Phi();
3406 assert( old_phi->region() == _head, "" );
3407 igvn.hash_delete(old_phi); // Yank from hash before hacking edges
3408 Node *p = PhiNode::make_blank(landing_pad, old_phi);
3409 uint icnt = fall_in_cnt;
3410 for( i = oreq-1; i>0; i-- ) {
3411 if( !phase->is_member( this, _head->in(i) ) ) {
3412 p->init_req(icnt--, old_phi->in(i));
3413 // Go ahead and clean out old edges from old phi
3414 old_phi->del_req(i);
3415 }
3416 }
3417 // Search for CSE's here, because ZKM.jar does a lot of
3418 // loop hackery and we need to be a little incremental
3419 // with the CSE to avoid O(N^2) node blow-up.
3420 Node *p2 = igvn.hash_find_insert(p); // Look for a CSE
3421 if( p2 ) { // Found CSE
3422 p->destruct(&igvn); // Recover useless new node
3423 p = p2; // Use old node
3424 } else {
3425 igvn.register_new_node_with_optimizer(p, old_phi);
3426 }
3427 // Make old Phi refer to new Phi.
3428 old_phi->add_req(p);
3429 // Check for the special case of making the old phi useless and
3430 // disappear it. In JavaGrande I have a case where this useless
3431 // Phi is the loop limit and prevents recognizing a CountedLoop
3432 // which in turn prevents removing an empty loop.
3433 Node *id_old_phi = old_phi->Identity(&igvn);
3434 if( id_old_phi != old_phi ) { // Found a simple identity?
3435 // Note that I cannot call 'replace_node' here, because
3436 // that will yank the edge from old_phi to the Region and
3437 // I'm mid-iteration over the Region's uses.
3438 for (DUIterator_Last imin, i = old_phi->last_outs(imin); i >= imin; ) {
3439 Node* use = old_phi->last_out(i);
3440 igvn.rehash_node_delayed(use);
3441 uint uses_found = 0;
3442 for (uint j = 0; j < use->len(); j++) {
3443 if (use->in(j) == old_phi) {
3444 if (j < use->req()) use->set_req (j, id_old_phi);
3445 else use->set_prec(j, id_old_phi);
3446 uses_found++;
3447 }
3448 }
3449 i -= uses_found; // we deleted 1 or more copies of this edge
3450 }
3451 }
3452 igvn._worklist.push(old_phi);
3453 }
3454 }
3455 // Finally clean out the fall-in edges from the RegionNode
3456 for( i = oreq-1; i>0; i-- ) {
3457 if( !phase->is_member( this, _head->in(i) ) ) {
3458 _head->del_req(i);
3459 }
3460 }
3461 igvn.rehash_node_delayed(_head);
3462 // Transform landing pad
3463 igvn.register_new_node_with_optimizer(landing_pad, _head);
3464 // Insert landing pad into the header
3465 _head->add_req(landing_pad);
3466 }
3467
3468 //------------------------------split_outer_loop-------------------------------
3469 // Split out the outermost loop from this shared header.
3470 void IdealLoopTree::split_outer_loop( PhaseIdealLoop *phase ) {
3471 PhaseIterGVN &igvn = phase->_igvn;
3472
3473 // Find index of outermost loop; it should also be my tail.
3474 uint outer_idx = 1;
3475 while( _head->in(outer_idx) != _tail ) outer_idx++;
3476
3477 // Make a LoopNode for the outermost loop.
3478 Node *ctl = _head->in(LoopNode::EntryControl);
3479 Node *outer = new LoopNode( ctl, _head->in(outer_idx) );
3480 outer = igvn.register_new_node_with_optimizer(outer, _head);
3481 phase->set_created_loop_node();
3482
3483 // Outermost loop falls into '_head' loop
3484 _head->set_req(LoopNode::EntryControl, outer);
3485 _head->del_req(outer_idx);
3486 // Split all the Phis up between '_head' loop and 'outer' loop.
3487 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
3488 Node *out = _head->fast_out(j);
3489 if( out->is_Phi() ) {
3490 PhiNode *old_phi = out->as_Phi();
3491 assert( old_phi->region() == _head, "" );
3492 Node *phi = PhiNode::make_blank(outer, old_phi);
3493 phi->init_req(LoopNode::EntryControl, old_phi->in(LoopNode::EntryControl));
3494 phi->init_req(LoopNode::LoopBackControl, old_phi->in(outer_idx));
3495 phi = igvn.register_new_node_with_optimizer(phi, old_phi);
3496 // Make old Phi point to new Phi on the fall-in path
3497 igvn.replace_input_of(old_phi, LoopNode::EntryControl, phi);
3498 old_phi->del_req(outer_idx);
3499 }
3500 }
3501
3502 // Use the new loop head instead of the old shared one
3503 _head = outer;
3504 phase->set_loop(_head, this);
3505 }
3506
3507 //------------------------------fix_parent-------------------------------------
3508 static void fix_parent( IdealLoopTree *loop, IdealLoopTree *parent ) {
3509 loop->_parent = parent;
3510 if( loop->_child ) fix_parent( loop->_child, loop );
3511 if( loop->_next ) fix_parent( loop->_next , parent );
3512 }
3513
3514 //------------------------------estimate_path_freq-----------------------------
3515 static float estimate_path_freq( Node *n ) {
3516 // Try to extract some path frequency info
3517 IfNode *iff;
3518 for( int i = 0; i < 50; i++ ) { // Skip through a bunch of uncommon tests
3519 uint nop = n->Opcode();
3520 if( nop == Op_SafePoint ) { // Skip any safepoint
3521 n = n->in(0);
3522 continue;
3523 }
3524 if( nop == Op_CatchProj ) { // Get count from a prior call
3525 // Assume call does not always throw exceptions: means the call-site
3526 // count is also the frequency of the fall-through path.
3527 assert( n->is_CatchProj(), "" );
3528 if( ((CatchProjNode*)n)->_con != CatchProjNode::fall_through_index )
3529 return 0.0f; // Assume call exception path is rare
3530 Node *call = n->in(0)->in(0)->in(0);
3531 assert( call->is_Call(), "expect a call here" );
3532 const JVMState *jvms = ((CallNode*)call)->jvms();
3533 ciMethodData* methodData = jvms->method()->method_data();
3534 if (!methodData->is_mature()) return 0.0f; // No call-site data
3535 ciProfileData* data = methodData->bci_to_data(jvms->bci());
3536 if ((data == nullptr) || !data->is_CounterData()) {
3537 // no call profile available, try call's control input
3538 n = n->in(0);
3539 continue;
3540 }
3541 return data->as_CounterData()->count()/FreqCountInvocations;
3542 }
3543 // See if there's a gating IF test
3544 Node *n_c = n->in(0);
3545 if( !n_c->is_If() ) break; // No estimate available
3546 iff = n_c->as_If();
3547 if( iff->_fcnt != COUNT_UNKNOWN ) // Have a valid count?
3548 // Compute how much count comes on this path
3549 return ((nop == Op_IfTrue) ? iff->_prob : 1.0f - iff->_prob) * iff->_fcnt;
3550 // Have no count info. Skip dull uncommon-trap like branches.
3551 if( (nop == Op_IfTrue && iff->_prob < PROB_LIKELY_MAG(5)) ||
3552 (nop == Op_IfFalse && iff->_prob > PROB_UNLIKELY_MAG(5)) )
3553 break;
3554 // Skip through never-taken branch; look for a real loop exit.
3555 n = iff->in(0);
3556 }
3557 return 0.0f; // No estimate available
3558 }
3559
3560 //------------------------------merge_many_backedges---------------------------
3561 // Merge all the backedges from the shared header into a private Region.
3562 // Feed that region as the one backedge to this loop.
3563 void IdealLoopTree::merge_many_backedges( PhaseIdealLoop *phase ) {
3564 uint i;
3565
3566 // Scan for the top 2 hottest backedges
3567 float hotcnt = 0.0f;
3568 float warmcnt = 0.0f;
3569 uint hot_idx = 0;
3570 // Loop starts at 2 because slot 1 is the fall-in path
3571 for( i = 2; i < _head->req(); i++ ) {
3572 float cnt = estimate_path_freq(_head->in(i));
3573 if( cnt > hotcnt ) { // Grab hottest path
3574 warmcnt = hotcnt;
3575 hotcnt = cnt;
3576 hot_idx = i;
3577 } else if( cnt > warmcnt ) { // And 2nd hottest path
3578 warmcnt = cnt;
3579 }
3580 }
3581
3582 // See if the hottest backedge is worthy of being an inner loop
3583 // by being much hotter than the next hottest backedge.
3584 if( hotcnt <= 0.0001 ||
3585 hotcnt < 2.0*warmcnt ) hot_idx = 0;// No hot backedge
3586
3587 // Peel out the backedges into a private merge point; peel
3588 // them all except optionally hot_idx.
3589 PhaseIterGVN &igvn = phase->_igvn;
3590
3591 Node *hot_tail = nullptr;
3592 // Make a Region for the merge point
3593 Node *r = new RegionNode(1);
3594 for( i = 2; i < _head->req(); i++ ) {
3595 if( i != hot_idx )
3596 r->add_req( _head->in(i) );
3597 else hot_tail = _head->in(i);
3598 }
3599 igvn.register_new_node_with_optimizer(r, _head);
3600 // Plug region into end of loop _head, followed by hot_tail
3601 while( _head->req() > 3 ) _head->del_req( _head->req()-1 );
3602 igvn.replace_input_of(_head, 2, r);
3603 if( hot_idx ) _head->add_req(hot_tail);
3604
3605 // Split all the Phis up between '_head' loop and the Region 'r'
3606 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
3607 Node *out = _head->fast_out(j);
3608 if( out->is_Phi() ) {
3609 PhiNode* n = out->as_Phi();
3610 igvn.hash_delete(n); // Delete from hash before hacking edges
3611 Node *hot_phi = nullptr;
3612 Node *phi = new PhiNode(r, n->type(), n->adr_type());
3613 // Check all inputs for the ones to peel out
3614 uint j = 1;
3615 for( uint i = 2; i < n->req(); i++ ) {
3616 if( i != hot_idx )
3617 phi->set_req( j++, n->in(i) );
3618 else hot_phi = n->in(i);
3619 }
3620 // Register the phi but do not transform until whole place transforms
3621 igvn.register_new_node_with_optimizer(phi, n);
3622 // Add the merge phi to the old Phi
3623 while( n->req() > 3 ) n->del_req( n->req()-1 );
3624 igvn.replace_input_of(n, 2, phi);
3625 if( hot_idx ) n->add_req(hot_phi);
3626 }
3627 }
3628
3629
3630 // Insert a new IdealLoopTree inserted below me. Turn it into a clone
3631 // of self loop tree. Turn self into a loop headed by _head and with
3632 // tail being the new merge point.
3633 IdealLoopTree *ilt = new IdealLoopTree( phase, _head, _tail );
3634 phase->set_loop(_tail,ilt); // Adjust tail
3635 _tail = r; // Self's tail is new merge point
3636 phase->set_loop(r,this);
3637 ilt->_child = _child; // New guy has my children
3638 _child = ilt; // Self has new guy as only child
3639 ilt->_parent = this; // new guy has self for parent
3640 ilt->_nest = _nest; // Same nesting depth (for now)
3641
3642 // Starting with 'ilt', look for child loop trees using the same shared
3643 // header. Flatten these out; they will no longer be loops in the end.
3644 IdealLoopTree **pilt = &_child;
3645 while( ilt ) {
3646 if( ilt->_head == _head ) {
3647 uint i;
3648 for( i = 2; i < _head->req(); i++ )
3649 if( _head->in(i) == ilt->_tail )
3650 break; // Still a loop
3651 if( i == _head->req() ) { // No longer a loop
3652 // Flatten ilt. Hang ilt's "_next" list from the end of
3653 // ilt's '_child' list. Move the ilt's _child up to replace ilt.
3654 IdealLoopTree **cp = &ilt->_child;
3655 while( *cp ) cp = &(*cp)->_next; // Find end of child list
3656 *cp = ilt->_next; // Hang next list at end of child list
3657 *pilt = ilt->_child; // Move child up to replace ilt
3658 ilt->_head = nullptr; // Flag as a loop UNIONED into parent
3659 ilt = ilt->_child; // Repeat using new ilt
3660 continue; // do not advance over ilt->_child
3661 }
3662 assert( ilt->_tail == hot_tail, "expected to only find the hot inner loop here" );
3663 phase->set_loop(_head,ilt);
3664 }
3665 pilt = &ilt->_child; // Advance to next
3666 ilt = *pilt;
3667 }
3668
3669 if( _child ) fix_parent( _child, this );
3670 }
3671
3672 //------------------------------beautify_loops---------------------------------
3673 // Split shared headers and insert loop landing pads.
3674 // Insert a LoopNode to replace the RegionNode.
3675 // Return TRUE if loop tree is structurally changed.
3676 bool IdealLoopTree::beautify_loops( PhaseIdealLoop *phase ) {
3677 bool result = false;
3678 // Cache parts in locals for easy
3679 PhaseIterGVN &igvn = phase->_igvn;
3680
3681 igvn.hash_delete(_head); // Yank from hash before hacking edges
3682
3683 // Check for multiple fall-in paths. Peel off a landing pad if need be.
3684 int fall_in_cnt = 0;
3685 for( uint i = 1; i < _head->req(); i++ )
3686 if( !phase->is_member( this, _head->in(i) ) )
3687 fall_in_cnt++;
3688 assert( fall_in_cnt, "at least 1 fall-in path" );
3689 if( fall_in_cnt > 1 ) // Need a loop landing pad to merge fall-ins
3690 split_fall_in( phase, fall_in_cnt );
3691
3692 // Swap inputs to the _head and all Phis to move the fall-in edge to
3693 // the left.
3694 fall_in_cnt = 1;
3695 while( phase->is_member( this, _head->in(fall_in_cnt) ) )
3696 fall_in_cnt++;
3697 if( fall_in_cnt > 1 ) {
3698 // Since I am just swapping inputs I do not need to update def-use info
3699 Node *tmp = _head->in(1);
3700 igvn.rehash_node_delayed(_head);
3701 _head->set_req( 1, _head->in(fall_in_cnt) );
3702 _head->set_req( fall_in_cnt, tmp );
3703 // Swap also all Phis
3704 for (DUIterator_Fast imax, i = _head->fast_outs(imax); i < imax; i++) {
3705 Node* phi = _head->fast_out(i);
3706 if( phi->is_Phi() ) {
3707 igvn.rehash_node_delayed(phi); // Yank from hash before hacking edges
3708 tmp = phi->in(1);
3709 phi->set_req( 1, phi->in(fall_in_cnt) );
3710 phi->set_req( fall_in_cnt, tmp );
3711 }
3712 }
3713 }
3714 assert( !phase->is_member( this, _head->in(1) ), "left edge is fall-in" );
3715 assert( phase->is_member( this, _head->in(2) ), "right edge is loop" );
3716
3717 // If I am a shared header (multiple backedges), peel off the many
3718 // backedges into a private merge point and use the merge point as
3719 // the one true backedge.
3720 if (_head->req() > 3) {
3721 // Merge the many backedges into a single backedge but leave
3722 // the hottest backedge as separate edge for the following peel.
3723 if (!_irreducible) {
3724 merge_many_backedges( phase );
3725 }
3726
3727 // When recursively beautify my children, split_fall_in can change
3728 // loop tree structure when I am an irreducible loop. Then the head
3729 // of my children has a req() not bigger than 3. Here we need to set
3730 // result to true to catch that case in order to tell the caller to
3731 // rebuild loop tree. See issue JDK-8244407 for details.
3732 result = true;
3733 }
3734
3735 // If I have one hot backedge, peel off myself loop.
3736 // I better be the outermost loop.
3737 if (_head->req() > 3 && !_irreducible) {
3738 split_outer_loop( phase );
3739 result = true;
3740
3741 } else if (!_head->is_Loop() && !_irreducible) {
3742 // Make a new LoopNode to replace the old loop head
3743 Node *l = new LoopNode( _head->in(1), _head->in(2) );
3744 l = igvn.register_new_node_with_optimizer(l, _head);
3745 phase->set_created_loop_node();
3746 // Go ahead and replace _head
3747 phase->_igvn.replace_node( _head, l );
3748 _head = l;
3749 phase->set_loop(_head, this);
3750 }
3751
3752 // Now recursively beautify nested loops
3753 if( _child ) result |= _child->beautify_loops( phase );
3754 if( _next ) result |= _next ->beautify_loops( phase );
3755 return result;
3756 }
3757
3758 //------------------------------allpaths_check_safepts----------------------------
3759 // Allpaths backwards scan. Starting at the head, traversing all backedges, and the body. Terminating each path at first
3760 // safepoint encountered. Helper for check_safepts.
3761 void IdealLoopTree::allpaths_check_safepts(VectorSet &visited, Node_List &stack) {
3762 assert(stack.size() == 0, "empty stack");
3763 stack.push(_head);
3764 visited.clear();
3765 visited.set(_head->_idx);
3766 while (stack.size() > 0) {
3767 Node* n = stack.pop();
3768 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
3769 // Terminate this path
3770 } else if (n->Opcode() == Op_SafePoint) {
3771 if (_phase->get_loop(n) != this) {
3772 if (_required_safept == nullptr) _required_safept = new Node_List();
3773 // save the first we run into on that path: closest to the tail if the head has a single backedge
3774 _required_safept->push(n);
3775 }
3776 // Terminate this path
3777 } else {
3778 uint start = n->is_Region() ? 1 : 0;
3779 uint end = n->is_Region() && (!n->is_Loop() || n == _head) ? n->req() : start + 1;
3780 for (uint i = start; i < end; i++) {
3781 Node* in = n->in(i);
3782 assert(in->is_CFG(), "must be");
3783 if (!visited.test_set(in->_idx) && is_member(_phase->get_loop(in))) {
3784 stack.push(in);
3785 }
3786 }
3787 }
3788 }
3789 }
3790
3791 //------------------------------check_safepts----------------------------
3792 // Given dominators, try to find loops with calls that must always be
3793 // executed (call dominates loop tail). These loops do not need non-call
3794 // safepoints (ncsfpt).
3795 //
3796 // A complication is that a safepoint in a inner loop may be needed
3797 // by an outer loop. In the following, the inner loop sees it has a
3798 // call (block 3) on every path from the head (block 2) to the
3799 // backedge (arc 3->2). So it deletes the ncsfpt (non-call safepoint)
3800 // in block 2, _but_ this leaves the outer loop without a safepoint.
3801 //
3802 // entry 0
3803 // |
3804 // v
3805 // outer 1,2 +->1
3806 // | |
3807 // | v
3808 // | 2<---+ ncsfpt in 2
3809 // |_/|\ |
3810 // | v |
3811 // inner 2,3 / 3 | call in 3
3812 // / | |
3813 // v +--+
3814 // exit 4
3815 //
3816 //
3817 // This method creates a list (_required_safept) of ncsfpt nodes that must
3818 // be protected is created for each loop. When a ncsfpt maybe deleted, it
3819 // is first looked for in the lists for the outer loops of the current loop.
3820 //
3821 // The insights into the problem:
3822 // A) counted loops are okay
3823 // B) innermost loops are okay (only an inner loop can delete
3824 // a ncsfpt needed by an outer loop)
3825 // C) a loop is immune from an inner loop deleting a safepoint
3826 // if the loop has a call on the idom-path
3827 // D) a loop is also immune if it has a ncsfpt (non-call safepoint) on the
3828 // idom-path that is not in a nested loop
3829 // E) otherwise, an ncsfpt on the idom-path that is nested in an inner
3830 // loop needs to be prevented from deletion by an inner loop
3831 //
3832 // There are two analyses:
3833 // 1) The first, and cheaper one, scans the loop body from
3834 // tail to head following the idom (immediate dominator)
3835 // chain, looking for the cases (C,D,E) above.
3836 // Since inner loops are scanned before outer loops, there is summary
3837 // information about inner loops. Inner loops can be skipped over
3838 // when the tail of an inner loop is encountered.
3839 //
3840 // 2) The second, invoked if the first fails to find a call or ncsfpt on
3841 // the idom path (which is rare), scans all predecessor control paths
3842 // from the tail to the head, terminating a path when a call or sfpt
3843 // is encountered, to find the ncsfpt's that are closest to the tail.
3844 //
3845 void IdealLoopTree::check_safepts(VectorSet &visited, Node_List &stack) {
3846 // Bottom up traversal
3847 IdealLoopTree* ch = _child;
3848 if (_child) _child->check_safepts(visited, stack);
3849 if (_next) _next ->check_safepts(visited, stack);
3850
3851 if (!_head->is_CountedLoop() && !_has_sfpt && _parent != nullptr) {
3852 bool has_call = false; // call on dom-path
3853 bool has_local_ncsfpt = false; // ncsfpt on dom-path at this loop depth
3854 Node* nonlocal_ncsfpt = nullptr; // ncsfpt on dom-path at a deeper depth
3855 if (!_irreducible) {
3856 // Scan the dom-path nodes from tail to head
3857 for (Node* n = tail(); n != _head; n = _phase->idom(n)) {
3858 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
3859 has_call = true;
3860 _has_sfpt = 1; // Then no need for a safept!
3861 break;
3862 } else if (n->Opcode() == Op_SafePoint) {
3863 if (_phase->get_loop(n) == this) {
3864 has_local_ncsfpt = true;
3865 break;
3866 }
3867 if (nonlocal_ncsfpt == nullptr) {
3868 nonlocal_ncsfpt = n; // save the one closest to the tail
3869 }
3870 } else {
3871 IdealLoopTree* nlpt = _phase->get_loop(n);
3872 if (this != nlpt) {
3873 // If at an inner loop tail, see if the inner loop has already
3874 // recorded seeing a call on the dom-path (and stop.) If not,
3875 // jump to the head of the inner loop.
3876 assert(is_member(nlpt), "nested loop");
3877 Node* tail = nlpt->_tail;
3878 if (tail->in(0)->is_If()) tail = tail->in(0);
3879 if (n == tail) {
3880 // If inner loop has call on dom-path, so does outer loop
3881 if (nlpt->_has_sfpt) {
3882 has_call = true;
3883 _has_sfpt = 1;
3884 break;
3885 }
3886 // Skip to head of inner loop
3887 assert(_phase->is_dominator(_head, nlpt->_head), "inner head dominated by outer head");
3888 n = nlpt->_head;
3889 if (_head == n) {
3890 // this and nlpt (inner loop) have the same loop head. This should not happen because
3891 // during beautify_loops we call merge_many_backedges. However, infinite loops may not
3892 // have been attached to the loop-tree during build_loop_tree before beautify_loops,
3893 // but then attached in the build_loop_tree afterwards, and so still have unmerged
3894 // backedges. Check if we are indeed in an infinite subgraph, and terminate the scan,
3895 // since we have reached the loop head of this.
3896 assert(_head->as_Region()->is_in_infinite_subgraph(),
3897 "only expect unmerged backedges in infinite loops");
3898 break;
3899 }
3900 }
3901 }
3902 }
3903 }
3904 }
3905 // Record safept's that this loop needs preserved when an
3906 // inner loop attempts to delete it's safepoints.
3907 if (_child != nullptr && !has_call && !has_local_ncsfpt) {
3908 if (nonlocal_ncsfpt != nullptr) {
3909 if (_required_safept == nullptr) _required_safept = new Node_List();
3910 _required_safept->push(nonlocal_ncsfpt);
3911 } else {
3912 // Failed to find a suitable safept on the dom-path. Now use
3913 // an all paths walk from tail to head, looking for safepoints to preserve.
3914 allpaths_check_safepts(visited, stack);
3915 }
3916 }
3917 }
3918 }
3919
3920 //---------------------------is_deleteable_safept----------------------------
3921 // Is safept not required by an outer loop?
3922 bool PhaseIdealLoop::is_deleteable_safept(Node* sfpt) {
3923 assert(sfpt->Opcode() == Op_SafePoint, "");
3924 IdealLoopTree* lp = get_loop(sfpt)->_parent;
3925 while (lp != nullptr) {
3926 Node_List* sfpts = lp->_required_safept;
3927 if (sfpts != nullptr) {
3928 for (uint i = 0; i < sfpts->size(); i++) {
3929 if (sfpt == sfpts->at(i))
3930 return false;
3931 }
3932 }
3933 lp = lp->_parent;
3934 }
3935 return true;
3936 }
3937
3938 //---------------------------replace_parallel_iv-------------------------------
3939 // Replace parallel induction variable (parallel to trip counter)
3940 void PhaseIdealLoop::replace_parallel_iv(IdealLoopTree *loop) {
3941 assert(loop->_head->is_CountedLoop(), "");
3942 CountedLoopNode *cl = loop->_head->as_CountedLoop();
3943 if (!cl->is_valid_counted_loop(T_INT)) {
3944 return; // skip malformed counted loop
3945 }
3946 Node *incr = cl->incr();
3947 if (incr == nullptr) {
3948 return; // Dead loop?
3949 }
3950 Node *init = cl->init_trip();
3951 Node *phi = cl->phi();
3952 int stride_con = cl->stride_con();
3953
3954 // Visit all children, looking for Phis
3955 for (DUIterator i = cl->outs(); cl->has_out(i); i++) {
3956 Node *out = cl->out(i);
3957 // Look for other phis (secondary IVs). Skip dead ones
3958 if (!out->is_Phi() || out == phi || !has_node(out)) {
3959 continue;
3960 }
3961
3962 PhiNode* phi2 = out->as_Phi();
3963 Node* incr2 = phi2->in(LoopNode::LoopBackControl);
3964 // Look for induction variables of the form: X += constant
3965 if (phi2->region() != loop->_head ||
3966 incr2->req() != 3 ||
3967 incr2->in(1)->uncast() != phi2 ||
3968 incr2 == incr ||
3969 incr2->Opcode() != Op_AddI ||
3970 !incr2->in(2)->is_Con()) {
3971 continue;
3972 }
3973
3974 if (incr2->in(1)->is_ConstraintCast() &&
3975 !(incr2->in(1)->in(0)->is_IfProj() && incr2->in(1)->in(0)->in(0)->is_RangeCheck())) {
3976 // Skip AddI->CastII->Phi case if CastII is not controlled by local RangeCheck
3977 continue;
3978 }
3979 // Check for parallel induction variable (parallel to trip counter)
3980 // via an affine function. In particular, count-down loops with
3981 // count-up array indices are common. We only RCE references off
3982 // the trip-counter, so we need to convert all these to trip-counter
3983 // expressions.
3984 Node* init2 = phi2->in(LoopNode::EntryControl);
3985 int stride_con2 = incr2->in(2)->get_int();
3986
3987 // The ratio of the two strides cannot be represented as an int
3988 // if stride_con2 is min_int and stride_con is -1.
3989 if (stride_con2 == min_jint && stride_con == -1) {
3990 continue;
3991 }
3992
3993 // The general case here gets a little tricky. We want to find the
3994 // GCD of all possible parallel IV's and make a new IV using this
3995 // GCD for the loop. Then all possible IVs are simple multiples of
3996 // the GCD. In practice, this will cover very few extra loops.
3997 // Instead we require 'stride_con2' to be a multiple of 'stride_con',
3998 // where +/-1 is the common case, but other integer multiples are
3999 // also easy to handle.
4000 int ratio_con = stride_con2/stride_con;
4001
4002 if ((ratio_con * stride_con) == stride_con2) { // Check for exact
4003 #ifndef PRODUCT
4004 if (TraceLoopOpts) {
4005 tty->print("Parallel IV: %d ", phi2->_idx);
4006 loop->dump_head();
4007 }
4008 #endif
4009 // Convert to using the trip counter. The parallel induction
4010 // variable differs from the trip counter by a loop-invariant
4011 // amount, the difference between their respective initial values.
4012 // It is scaled by the 'ratio_con'.
4013 Node* ratio = _igvn.intcon(ratio_con);
4014 set_ctrl(ratio, C->root());
4015 Node* ratio_init = new MulINode(init, ratio);
4016 _igvn.register_new_node_with_optimizer(ratio_init, init);
4017 set_early_ctrl(ratio_init, false);
4018 Node* diff = new SubINode(init2, ratio_init);
4019 _igvn.register_new_node_with_optimizer(diff, init2);
4020 set_early_ctrl(diff, false);
4021 Node* ratio_idx = new MulINode(phi, ratio);
4022 _igvn.register_new_node_with_optimizer(ratio_idx, phi);
4023 set_ctrl(ratio_idx, cl);
4024 Node* add = new AddINode(ratio_idx, diff);
4025 _igvn.register_new_node_with_optimizer(add);
4026 set_ctrl(add, cl);
4027 _igvn.replace_node( phi2, add );
4028 // Sometimes an induction variable is unused
4029 if (add->outcnt() == 0) {
4030 _igvn.remove_dead_node(add);
4031 }
4032 --i; // deleted this phi; rescan starting with next position
4033 continue;
4034 }
4035 }
4036 }
4037
4038 void IdealLoopTree::remove_safepoints(PhaseIdealLoop* phase, bool keep_one) {
4039 Node* keep = nullptr;
4040 if (keep_one) {
4041 // Look for a safepoint on the idom-path.
4042 for (Node* i = tail(); i != _head; i = phase->idom(i)) {
4043 if (i->Opcode() == Op_SafePoint && phase->get_loop(i) == this) {
4044 keep = i;
4045 break; // Found one
4046 }
4047 }
4048 }
4049
4050 // Don't remove any safepoints if it is requested to keep a single safepoint and
4051 // no safepoint was found on idom-path. It is not safe to remove any safepoint
4052 // in this case since there's no safepoint dominating all paths in the loop body.
4053 bool prune = !keep_one || keep != nullptr;
4054
4055 // Delete other safepoints in this loop.
4056 Node_List* sfpts = _safepts;
4057 if (prune && sfpts != nullptr) {
4058 assert(keep == nullptr || keep->Opcode() == Op_SafePoint, "not safepoint");
4059 for (uint i = 0; i < sfpts->size(); i++) {
4060 Node* n = sfpts->at(i);
4061 assert(phase->get_loop(n) == this, "");
4062 if (n != keep && phase->is_deleteable_safept(n)) {
4063 phase->lazy_replace(n, n->in(TypeFunc::Control));
4064 }
4065 }
4066 }
4067 }
4068
4069 //------------------------------counted_loop-----------------------------------
4070 // Convert to counted loops where possible
4071 void IdealLoopTree::counted_loop( PhaseIdealLoop *phase ) {
4072
4073 // For grins, set the inner-loop flag here
4074 if (!_child) {
4075 if (_head->is_Loop()) _head->as_Loop()->set_inner_loop();
4076 }
4077
4078 IdealLoopTree* loop = this;
4079 if (_head->is_CountedLoop() ||
4080 phase->is_counted_loop(_head, loop, T_INT)) {
4081
4082 if (LoopStripMiningIter == 0 || _head->as_CountedLoop()->is_strip_mined()) {
4083 // Indicate we do not need a safepoint here
4084 _has_sfpt = 1;
4085 }
4086
4087 // Remove safepoints
4088 bool keep_one_sfpt = !(_has_call || _has_sfpt);
4089 remove_safepoints(phase, keep_one_sfpt);
4090
4091 // Look for induction variables
4092 phase->replace_parallel_iv(this);
4093 } else if (_head->is_LongCountedLoop() ||
4094 phase->is_counted_loop(_head, loop, T_LONG)) {
4095 remove_safepoints(phase, true);
4096 } else {
4097 assert(!_head->is_Loop() || !_head->as_Loop()->is_loop_nest_inner_loop(), "transformation to counted loop should not fail");
4098 if (_parent != nullptr && !_irreducible) {
4099 // Not a counted loop. Keep one safepoint.
4100 bool keep_one_sfpt = true;
4101 remove_safepoints(phase, keep_one_sfpt);
4102 }
4103 }
4104
4105 // Recursively
4106 assert(loop->_child != this || (loop->_head->as_Loop()->is_OuterStripMinedLoop() && _head->as_CountedLoop()->is_strip_mined()), "what kind of loop was added?");
4107 assert(loop->_child != this || (loop->_child->_child == nullptr && loop->_child->_next == nullptr), "would miss some loops");
4108 if (loop->_child && loop->_child != this) loop->_child->counted_loop(phase);
4109 if (loop->_next) loop->_next ->counted_loop(phase);
4110 }
4111
4112
4113 // The Estimated Loop Clone Size:
4114 // CloneFactor * (~112% * BodySize + BC) + CC + FanOutTerm,
4115 // where BC and CC are totally ad-hoc/magic "body" and "clone" constants,
4116 // respectively, used to ensure that the node usage estimates made are on the
4117 // safe side, for the most part. The FanOutTerm is an attempt to estimate the
4118 // possible additional/excessive nodes generated due to data and control flow
4119 // merging, for edges reaching outside the loop.
4120 uint IdealLoopTree::est_loop_clone_sz(uint factor) const {
4121
4122 precond(0 < factor && factor < 16);
4123
4124 uint const bc = 13;
4125 uint const cc = 17;
4126 uint const sz = _body.size() + (_body.size() + 7) / 2;
4127 uint estimate = factor * (sz + bc) + cc;
4128
4129 assert((estimate - cc) / factor == sz + bc, "overflow");
4130
4131 return estimate + est_loop_flow_merge_sz();
4132 }
4133
4134 // The Estimated Loop (full-) Unroll Size:
4135 // UnrollFactor * (~106% * BodySize) + CC + FanOutTerm,
4136 // where CC is a (totally) ad-hoc/magic "clone" constant, used to ensure that
4137 // node usage estimates made are on the safe side, for the most part. This is
4138 // a "light" version of the loop clone size calculation (above), based on the
4139 // assumption that most of the loop-construct overhead will be unraveled when
4140 // (fully) unrolled. Defined for unroll factors larger or equal to one (>=1),
4141 // including an overflow check and returning UINT_MAX in case of an overflow.
4142 uint IdealLoopTree::est_loop_unroll_sz(uint factor) const {
4143
4144 precond(factor > 0);
4145
4146 // Take into account that after unroll conjoined heads and tails will fold.
4147 uint const b0 = _body.size() - EMPTY_LOOP_SIZE;
4148 uint const cc = 7;
4149 uint const sz = b0 + (b0 + 15) / 16;
4150 uint estimate = factor * sz + cc;
4151
4152 if ((estimate - cc) / factor != sz) {
4153 return UINT_MAX;
4154 }
4155
4156 return estimate + est_loop_flow_merge_sz();
4157 }
4158
4159 // Estimate the growth effect (in nodes) of merging control and data flow when
4160 // cloning a loop body, based on the amount of control and data flow reaching
4161 // outside of the (current) loop body.
4162 uint IdealLoopTree::est_loop_flow_merge_sz() const {
4163
4164 uint ctrl_edge_out_cnt = 0;
4165 uint data_edge_out_cnt = 0;
4166
4167 for (uint i = 0; i < _body.size(); i++) {
4168 Node* node = _body.at(i);
4169 uint outcnt = node->outcnt();
4170
4171 for (uint k = 0; k < outcnt; k++) {
4172 Node* out = node->raw_out(k);
4173 if (out == nullptr) continue;
4174 if (out->is_CFG()) {
4175 if (!is_member(_phase->get_loop(out))) {
4176 ctrl_edge_out_cnt++;
4177 }
4178 } else if (_phase->has_ctrl(out)) {
4179 Node* ctrl = _phase->get_ctrl(out);
4180 assert(ctrl != nullptr, "must be");
4181 assert(ctrl->is_CFG(), "must be");
4182 if (!is_member(_phase->get_loop(ctrl))) {
4183 data_edge_out_cnt++;
4184 }
4185 }
4186 }
4187 }
4188 // Use data and control count (x2.0) in estimate iff both are > 0. This is
4189 // a rather pessimistic estimate for the most part, in particular for some
4190 // complex loops, but still not enough to capture all loops.
4191 if (ctrl_edge_out_cnt > 0 && data_edge_out_cnt > 0) {
4192 return 2 * (ctrl_edge_out_cnt + data_edge_out_cnt);
4193 }
4194 return 0;
4195 }
4196
4197 #ifndef PRODUCT
4198 //------------------------------dump_head--------------------------------------
4199 // Dump 1 liner for loop header info
4200 void IdealLoopTree::dump_head() {
4201 tty->sp(2 * _nest);
4202 tty->print("Loop: N%d/N%d ", _head->_idx, _tail->_idx);
4203 if (_irreducible) tty->print(" IRREDUCIBLE");
4204 Node* entry = _head->is_Loop() ? _head->as_Loop()->skip_strip_mined(-1)->in(LoopNode::EntryControl)
4205 : _head->in(LoopNode::EntryControl);
4206 const Predicates predicates(entry);
4207 if (predicates.loop_limit_check_predicate_block()->is_non_empty()) {
4208 tty->print(" limit_check");
4209 }
4210 if (UseProfiledLoopPredicate && predicates.profiled_loop_predicate_block()->is_non_empty()) {
4211 tty->print(" profile_predicated");
4212 }
4213 if (UseLoopPredicate && predicates.loop_predicate_block()->is_non_empty()) {
4214 tty->print(" predicated");
4215 }
4216 if (_head->is_CountedLoop()) {
4217 CountedLoopNode *cl = _head->as_CountedLoop();
4218 tty->print(" counted");
4219
4220 Node* init_n = cl->init_trip();
4221 if (init_n != nullptr && init_n->is_Con())
4222 tty->print(" [%d,", cl->init_trip()->get_int());
4223 else
4224 tty->print(" [int,");
4225 Node* limit_n = cl->limit();
4226 if (limit_n != nullptr && limit_n->is_Con())
4227 tty->print("%d),", cl->limit()->get_int());
4228 else
4229 tty->print("int),");
4230 int stride_con = cl->stride_con();
4231 if (stride_con > 0) tty->print("+");
4232 tty->print("%d", stride_con);
4233
4234 tty->print(" (%0.f iters) ", cl->profile_trip_cnt());
4235
4236 if (cl->is_pre_loop ()) tty->print(" pre" );
4237 if (cl->is_main_loop()) tty->print(" main");
4238 if (cl->is_post_loop()) tty->print(" post");
4239 if (cl->is_vectorized_loop()) tty->print(" vector");
4240 if (range_checks_present()) tty->print(" rc ");
4241 }
4242 if (_has_call) tty->print(" has_call");
4243 if (_has_sfpt) tty->print(" has_sfpt");
4244 if (_rce_candidate) tty->print(" rce");
4245 if (_safepts != nullptr && _safepts->size() > 0) {
4246 tty->print(" sfpts={"); _safepts->dump_simple(); tty->print(" }");
4247 }
4248 if (_required_safept != nullptr && _required_safept->size() > 0) {
4249 tty->print(" req={"); _required_safept->dump_simple(); tty->print(" }");
4250 }
4251 if (Verbose) {
4252 tty->print(" body={"); _body.dump_simple(); tty->print(" }");
4253 }
4254 if (_head->is_Loop() && _head->as_Loop()->is_strip_mined()) {
4255 tty->print(" strip_mined");
4256 }
4257 tty->cr();
4258 }
4259
4260 //------------------------------dump-------------------------------------------
4261 // Dump loops by loop tree
4262 void IdealLoopTree::dump() {
4263 dump_head();
4264 if (_child) _child->dump();
4265 if (_next) _next ->dump();
4266 }
4267
4268 #endif
4269
4270 static void log_loop_tree_helper(IdealLoopTree* root, IdealLoopTree* loop, CompileLog* log) {
4271 if (loop == root) {
4272 if (loop->_child != nullptr) {
4273 log->begin_head("loop_tree");
4274 log->end_head();
4275 log_loop_tree_helper(root, loop->_child, log);
4276 log->tail("loop_tree");
4277 assert(loop->_next == nullptr, "what?");
4278 }
4279 } else if (loop != nullptr) {
4280 Node* head = loop->_head;
4281 log->begin_head("loop");
4282 log->print(" idx='%d' ", head->_idx);
4283 if (loop->_irreducible) log->print("irreducible='1' ");
4284 if (head->is_Loop()) {
4285 if (head->as_Loop()->is_inner_loop()) log->print("inner_loop='1' ");
4286 if (head->as_Loop()->is_partial_peel_loop()) log->print("partial_peel_loop='1' ");
4287 } else if (head->is_CountedLoop()) {
4288 CountedLoopNode* cl = head->as_CountedLoop();
4289 if (cl->is_pre_loop()) log->print("pre_loop='%d' ", cl->main_idx());
4290 if (cl->is_main_loop()) log->print("main_loop='%d' ", cl->_idx);
4291 if (cl->is_post_loop()) log->print("post_loop='%d' ", cl->main_idx());
4292 }
4293 log->end_head();
4294 log_loop_tree_helper(root, loop->_child, log);
4295 log->tail("loop");
4296 log_loop_tree_helper(root, loop->_next, log);
4297 }
4298 }
4299
4300 void PhaseIdealLoop::log_loop_tree() {
4301 if (C->log() != nullptr) {
4302 log_loop_tree_helper(_ltree_root, _ltree_root, C->log());
4303 }
4304 }
4305
4306 // Eliminate all Parse and Template Assertion Predicates that are not associated with a loop anymore. The eliminated
4307 // predicates will be removed during the next round of IGVN.
4308 void PhaseIdealLoop::eliminate_useless_predicates() {
4309 if (C->parse_predicate_count() == 0 && C->template_assertion_predicate_count() == 0) {
4310 return; // No predicates left.
4311 }
4312
4313 eliminate_useless_parse_predicates();
4314 eliminate_useless_template_assertion_predicates();
4315 }
4316
4317 // Eliminate all Parse Predicates that do not belong to a loop anymore by marking them useless. These will be removed
4318 // during the next round of IGVN.
4319 void PhaseIdealLoop::eliminate_useless_parse_predicates() {
4320 mark_all_parse_predicates_useless();
4321 if (C->has_loops()) {
4322 mark_loop_associated_parse_predicates_useful();
4323 }
4324 add_useless_parse_predicates_to_igvn_worklist();
4325 }
4326
4327 void PhaseIdealLoop::mark_all_parse_predicates_useless() const {
4328 for (int i = 0; i < C->parse_predicate_count(); i++) {
4329 C->parse_predicate(i)->mark_useless();
4330 }
4331 }
4332
4333 void PhaseIdealLoop::mark_loop_associated_parse_predicates_useful() {
4334 for (LoopTreeIterator iterator(_ltree_root); !iterator.done(); iterator.next()) {
4335 IdealLoopTree* loop = iterator.current();
4336 if (loop->can_apply_loop_predication()) {
4337 mark_useful_parse_predicates_for_loop(loop);
4338 }
4339 }
4340 }
4341
4342 void PhaseIdealLoop::mark_useful_parse_predicates_for_loop(IdealLoopTree* loop) {
4343 Node* entry = loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl);
4344 const Predicates predicates(entry);
4345 ParsePredicateIterator iterator(predicates);
4346 while (iterator.has_next()) {
4347 iterator.next()->mark_useful();
4348 }
4349 }
4350
4351 void PhaseIdealLoop::add_useless_parse_predicates_to_igvn_worklist() {
4352 for (int i = 0; i < C->parse_predicate_count(); i++) {
4353 ParsePredicateNode* parse_predicate_node = C->parse_predicate(i);
4354 if (parse_predicate_node->is_useless()) {
4355 _igvn._worklist.push(parse_predicate_node);
4356 }
4357 }
4358 }
4359
4360
4361 // Eliminate all Template Assertion Predicates that do not belong to their originally associated loop anymore by
4362 // replacing the Opaque4 node of the If node with true. These nodes will be removed during the next round of IGVN.
4363 void PhaseIdealLoop::eliminate_useless_template_assertion_predicates() {
4364 Unique_Node_List useful_predicates;
4365 if (C->has_loops()) {
4366 collect_useful_template_assertion_predicates(useful_predicates);
4367 }
4368 eliminate_useless_template_assertion_predicates(useful_predicates);
4369 }
4370
4371 void PhaseIdealLoop::collect_useful_template_assertion_predicates(Unique_Node_List& useful_predicates) {
4372 for (LoopTreeIterator iterator(_ltree_root); !iterator.done(); iterator.next()) {
4373 IdealLoopTree* loop = iterator.current();
4374 if (loop->can_apply_loop_predication()) {
4375 collect_useful_template_assertion_predicates_for_loop(loop, useful_predicates);
4376 }
4377 }
4378 }
4379
4380 void PhaseIdealLoop::collect_useful_template_assertion_predicates_for_loop(IdealLoopTree* loop,
4381 Unique_Node_List &useful_predicates) {
4382 Node* entry = loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl);
4383 const Predicates predicates(entry);
4384 if (UseProfiledLoopPredicate) {
4385 const PredicateBlock* profiled_loop_predicate_block = predicates.profiled_loop_predicate_block();
4386 if (profiled_loop_predicate_block->has_parse_predicate()) {
4387 IfProjNode* parse_predicate_proj = profiled_loop_predicate_block->parse_predicate_success_proj();
4388 get_assertion_predicates(parse_predicate_proj, useful_predicates, true);
4389 }
4390 }
4391
4392 if (UseLoopPredicate) {
4393 const PredicateBlock* loop_predicate_block = predicates.loop_predicate_block();
4394 if (loop_predicate_block->has_parse_predicate()) {
4395 IfProjNode* parse_predicate_proj = loop_predicate_block->parse_predicate_success_proj();
4396 get_assertion_predicates(parse_predicate_proj, useful_predicates, true);
4397 }
4398 }
4399 }
4400
4401 void PhaseIdealLoop::eliminate_useless_template_assertion_predicates(Unique_Node_List& useful_predicates) {
4402 for (int i = C->template_assertion_predicate_count(); i > 0; i--) {
4403 Opaque4Node* opaque4_node = C->template_assertion_predicate_opaq_node(i - 1)->as_Opaque4();
4404 if (!useful_predicates.member(opaque4_node)) { // not in the useful list
4405 _igvn.replace_node(opaque4_node, opaque4_node->in(2));
4406 }
4407 }
4408 }
4409
4410 // If a post or main loop is removed due to an assert predicate, the opaque that guards the loop is not needed anymore
4411 void PhaseIdealLoop::eliminate_useless_zero_trip_guard() {
4412 if (_zero_trip_guard_opaque_nodes.size() == 0) {
4413 return;
4414 }
4415 Unique_Node_List useful_zero_trip_guard_opaques_nodes;
4416 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
4417 IdealLoopTree* lpt = iter.current();
4418 if (lpt->_child == nullptr && lpt->is_counted()) {
4419 CountedLoopNode* head = lpt->_head->as_CountedLoop();
4420 Node* opaque = head->is_canonical_loop_entry();
4421 if (opaque != nullptr) {
4422 useful_zero_trip_guard_opaques_nodes.push(opaque);
4423 }
4424 }
4425 }
4426 for (uint i = 0; i < _zero_trip_guard_opaque_nodes.size(); ++i) {
4427 OpaqueZeroTripGuardNode* opaque = ((OpaqueZeroTripGuardNode*)_zero_trip_guard_opaque_nodes.at(i));
4428 DEBUG_ONLY(CountedLoopNode* guarded_loop = opaque->guarded_loop());
4429 if (!useful_zero_trip_guard_opaques_nodes.member(opaque)) {
4430 IfNode* iff = opaque->if_node();
4431 IdealLoopTree* loop = get_loop(iff);
4432 while (loop != _ltree_root && loop != nullptr) {
4433 loop = loop->_parent;
4434 }
4435 if (loop == nullptr) {
4436 // unreachable from _ltree_root: zero trip guard is in a newly discovered infinite loop.
4437 // We can't tell if the opaque node is useful or not
4438 assert(guarded_loop == nullptr || guarded_loop->is_in_infinite_subgraph(), "");
4439 } else {
4440 assert(guarded_loop == nullptr, "");
4441 this->_igvn.replace_node(opaque, opaque->in(1));
4442 }
4443 } else {
4444 assert(guarded_loop != nullptr, "");
4445 }
4446 }
4447 }
4448
4449 //------------------------process_expensive_nodes-----------------------------
4450 // Expensive nodes have their control input set to prevent the GVN
4451 // from commoning them and as a result forcing the resulting node to
4452 // be in a more frequent path. Use CFG information here, to change the
4453 // control inputs so that some expensive nodes can be commoned while
4454 // not executed more frequently.
4455 bool PhaseIdealLoop::process_expensive_nodes() {
4456 assert(OptimizeExpensiveOps, "optimization off?");
4457
4458 // Sort nodes to bring similar nodes together
4459 C->sort_expensive_nodes();
4460
4461 bool progress = false;
4462
4463 for (int i = 0; i < C->expensive_count(); ) {
4464 Node* n = C->expensive_node(i);
4465 int start = i;
4466 // Find nodes similar to n
4467 i++;
4468 for (; i < C->expensive_count() && Compile::cmp_expensive_nodes(n, C->expensive_node(i)) == 0; i++);
4469 int end = i;
4470 // And compare them two by two
4471 for (int j = start; j < end; j++) {
4472 Node* n1 = C->expensive_node(j);
4473 if (is_node_unreachable(n1)) {
4474 continue;
4475 }
4476 for (int k = j+1; k < end; k++) {
4477 Node* n2 = C->expensive_node(k);
4478 if (is_node_unreachable(n2)) {
4479 continue;
4480 }
4481
4482 assert(n1 != n2, "should be pair of nodes");
4483
4484 Node* c1 = n1->in(0);
4485 Node* c2 = n2->in(0);
4486
4487 Node* parent_c1 = c1;
4488 Node* parent_c2 = c2;
4489
4490 // The call to get_early_ctrl_for_expensive() moves the
4491 // expensive nodes up but stops at loops that are in a if
4492 // branch. See whether we can exit the loop and move above the
4493 // If.
4494 if (c1->is_Loop()) {
4495 parent_c1 = c1->in(1);
4496 }
4497 if (c2->is_Loop()) {
4498 parent_c2 = c2->in(1);
4499 }
4500
4501 if (parent_c1 == parent_c2) {
4502 _igvn._worklist.push(n1);
4503 _igvn._worklist.push(n2);
4504 continue;
4505 }
4506
4507 // Look for identical expensive node up the dominator chain.
4508 if (is_dominator(c1, c2)) {
4509 c2 = c1;
4510 } else if (is_dominator(c2, c1)) {
4511 c1 = c2;
4512 } else if (parent_c1->is_Proj() && parent_c1->in(0)->is_If() &&
4513 parent_c2->is_Proj() && parent_c1->in(0) == parent_c2->in(0)) {
4514 // Both branches have the same expensive node so move it up
4515 // before the if.
4516 c1 = c2 = idom(parent_c1->in(0));
4517 }
4518 // Do the actual moves
4519 if (n1->in(0) != c1) {
4520 _igvn.replace_input_of(n1, 0, c1);
4521 progress = true;
4522 }
4523 if (n2->in(0) != c2) {
4524 _igvn.replace_input_of(n2, 0, c2);
4525 progress = true;
4526 }
4527 }
4528 }
4529 }
4530
4531 return progress;
4532 }
4533
4534 //=============================================================================
4535 //----------------------------build_and_optimize-------------------------------
4536 // Create a PhaseLoop. Build the ideal Loop tree. Map each Ideal Node to
4537 // its corresponding LoopNode. If 'optimize' is true, do some loop cleanups.
4538 void PhaseIdealLoop::build_and_optimize() {
4539 assert(!C->post_loop_opts_phase(), "no loop opts allowed");
4540
4541 bool do_split_ifs = (_mode == LoopOptsDefault);
4542 bool skip_loop_opts = (_mode == LoopOptsNone);
4543 bool do_max_unroll = (_mode == LoopOptsMaxUnroll);
4544
4545
4546 int old_progress = C->major_progress();
4547 uint orig_worklist_size = _igvn._worklist.size();
4548
4549 // Reset major-progress flag for the driver's heuristics
4550 C->clear_major_progress();
4551
4552 #ifndef PRODUCT
4553 // Capture for later assert
4554 uint unique = C->unique();
4555 _loop_invokes++;
4556 _loop_work += unique;
4557 #endif
4558
4559 // True if the method has at least 1 irreducible loop
4560 _has_irreducible_loops = false;
4561
4562 _created_loop_node = false;
4563
4564 VectorSet visited;
4565 // Pre-grow the mapping from Nodes to IdealLoopTrees.
4566 _loop_or_ctrl.map(C->unique(), nullptr);
4567 memset(_loop_or_ctrl.adr(), 0, wordSize * C->unique());
4568
4569 // Pre-build the top-level outermost loop tree entry
4570 _ltree_root = new IdealLoopTree( this, C->root(), C->root() );
4571 // Do not need a safepoint at the top level
4572 _ltree_root->_has_sfpt = 1;
4573
4574 // Initialize Dominators.
4575 // Checked in clone_loop_predicate() during beautify_loops().
4576 _idom_size = 0;
4577 _idom = nullptr;
4578 _dom_depth = nullptr;
4579 _dom_stk = nullptr;
4580
4581 // Empty pre-order array
4582 allocate_preorders();
4583
4584 // Build a loop tree on the fly. Build a mapping from CFG nodes to
4585 // IdealLoopTree entries. Data nodes are NOT walked.
4586 build_loop_tree();
4587 // Check for bailout, and return
4588 if (C->failing()) {
4589 return;
4590 }
4591
4592 // Verify that the has_loops() flag set at parse time is consistent with the just built loop tree. When the back edge
4593 // is an exception edge, parsing doesn't set has_loops().
4594 assert(_ltree_root->_child == nullptr || C->has_loops() || C->has_exception_backedge(), "parsing found no loops but there are some");
4595 // No loops after all
4596 if( !_ltree_root->_child && !_verify_only ) C->set_has_loops(false);
4597
4598 // There should always be an outer loop containing the Root and Return nodes.
4599 // If not, we have a degenerate empty program. Bail out in this case.
4600 if (!has_node(C->root())) {
4601 if (!_verify_only) {
4602 C->clear_major_progress();
4603 assert(false, "empty program detected during loop optimization");
4604 C->record_method_not_compilable("empty program detected during loop optimization");
4605 }
4606 return;
4607 }
4608
4609 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
4610 // Nothing to do, so get out
4611 bool stop_early = !C->has_loops() && !skip_loop_opts && !do_split_ifs && !do_max_unroll && !_verify_me &&
4612 !_verify_only && !bs->is_gc_specific_loop_opts_pass(_mode);
4613 bool do_expensive_nodes = C->should_optimize_expensive_nodes(_igvn);
4614 bool strip_mined_loops_expanded = bs->strip_mined_loops_expanded(_mode);
4615 if (stop_early && !do_expensive_nodes) {
4616 return;
4617 }
4618
4619 // Set loop nesting depth
4620 _ltree_root->set_nest( 0 );
4621
4622 // Split shared headers and insert loop landing pads.
4623 // Do not bother doing this on the Root loop of course.
4624 if( !_verify_me && !_verify_only && _ltree_root->_child ) {
4625 C->print_method(PHASE_BEFORE_BEAUTIFY_LOOPS, 3);
4626 if( _ltree_root->_child->beautify_loops( this ) ) {
4627 // Re-build loop tree!
4628 _ltree_root->_child = nullptr;
4629 _loop_or_ctrl.clear();
4630 reallocate_preorders();
4631 build_loop_tree();
4632 // Check for bailout, and return
4633 if (C->failing()) {
4634 return;
4635 }
4636 // Reset loop nesting depth
4637 _ltree_root->set_nest( 0 );
4638
4639 C->print_method(PHASE_AFTER_BEAUTIFY_LOOPS, 3);
4640 }
4641 }
4642
4643 // Build Dominators for elision of null checks & loop finding.
4644 // Since nodes do not have a slot for immediate dominator, make
4645 // a persistent side array for that info indexed on node->_idx.
4646 _idom_size = C->unique();
4647 _idom = NEW_RESOURCE_ARRAY( Node*, _idom_size );
4648 _dom_depth = NEW_RESOURCE_ARRAY( uint, _idom_size );
4649 _dom_stk = nullptr; // Allocated on demand in recompute_dom_depth
4650 memset( _dom_depth, 0, _idom_size * sizeof(uint) );
4651
4652 Dominators();
4653
4654 if (!_verify_only) {
4655 // As a side effect, Dominators removed any unreachable CFG paths
4656 // into RegionNodes. It doesn't do this test against Root, so
4657 // we do it here.
4658 for( uint i = 1; i < C->root()->req(); i++ ) {
4659 if (!_loop_or_ctrl[C->root()->in(i)->_idx]) { // Dead path into Root?
4660 _igvn.delete_input_of(C->root(), i);
4661 i--; // Rerun same iteration on compressed edges
4662 }
4663 }
4664
4665 // Given dominators, try to find inner loops with calls that must
4666 // always be executed (call dominates loop tail). These loops do
4667 // not need a separate safepoint.
4668 Node_List cisstack;
4669 _ltree_root->check_safepts(visited, cisstack);
4670 }
4671
4672 // Walk the DATA nodes and place into loops. Find earliest control
4673 // node. For CFG nodes, the _loop_or_ctrl array starts out and remains
4674 // holding the associated IdealLoopTree pointer. For DATA nodes, the
4675 // _loop_or_ctrl array holds the earliest legal controlling CFG node.
4676
4677 // Allocate stack with enough space to avoid frequent realloc
4678 int stack_size = (C->live_nodes() >> 1) + 16; // (live_nodes>>1)+16 from Java2D stats
4679 Node_Stack nstack(stack_size);
4680
4681 visited.clear();
4682 Node_List worklist;
4683 // Don't need C->root() on worklist since
4684 // it will be processed among C->top() inputs
4685 worklist.push(C->top());
4686 visited.set(C->top()->_idx); // Set C->top() as visited now
4687 build_loop_early( visited, worklist, nstack );
4688
4689 // Given early legal placement, try finding counted loops. This placement
4690 // is good enough to discover most loop invariants.
4691 if (!_verify_me && !_verify_only && !strip_mined_loops_expanded) {
4692 _ltree_root->counted_loop( this );
4693 }
4694
4695 // Find latest loop placement. Find ideal loop placement.
4696 visited.clear();
4697 init_dom_lca_tags();
4698 // Need C->root() on worklist when processing outs
4699 worklist.push(C->root());
4700 NOT_PRODUCT( C->verify_graph_edges(); )
4701 worklist.push(C->top());
4702 build_loop_late( visited, worklist, nstack );
4703 if (C->failing()) { return; }
4704
4705 if (_verify_only) {
4706 C->restore_major_progress(old_progress);
4707 assert(C->unique() == unique, "verification _mode made Nodes? ? ?");
4708 assert(_igvn._worklist.size() == orig_worklist_size, "shouldn't push anything");
4709 return;
4710 }
4711
4712 // clear out the dead code after build_loop_late
4713 while (_deadlist.size()) {
4714 _igvn.remove_globally_dead_node(_deadlist.pop());
4715 }
4716
4717 eliminate_useless_zero_trip_guard();
4718
4719 if (stop_early) {
4720 assert(do_expensive_nodes, "why are we here?");
4721 if (process_expensive_nodes()) {
4722 // If we made some progress when processing expensive nodes then
4723 // the IGVN may modify the graph in a way that will allow us to
4724 // make some more progress: we need to try processing expensive
4725 // nodes again.
4726 C->set_major_progress();
4727 }
4728 return;
4729 }
4730
4731 // Some parser-inserted loop predicates could never be used by loop
4732 // predication or they were moved away from loop during some optimizations.
4733 // For example, peeling. Eliminate them before next loop optimizations.
4734 eliminate_useless_predicates();
4735
4736 #ifndef PRODUCT
4737 C->verify_graph_edges();
4738 if (_verify_me) { // Nested verify pass?
4739 // Check to see if the verify _mode is broken
4740 assert(C->unique() == unique, "non-optimize _mode made Nodes? ? ?");
4741 return;
4742 }
4743 DEBUG_ONLY( if (VerifyLoopOptimizations) { verify(); } );
4744 if (TraceLoopOpts && C->has_loops()) {
4745 _ltree_root->dump();
4746 }
4747 #endif
4748
4749 if (skip_loop_opts) {
4750 C->restore_major_progress(old_progress);
4751 return;
4752 }
4753
4754 if (do_max_unroll) {
4755 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
4756 IdealLoopTree* lpt = iter.current();
4757 if (lpt->is_innermost() && lpt->_allow_optimizations && !lpt->_has_call && lpt->is_counted()) {
4758 lpt->compute_trip_count(this);
4759 if (!lpt->do_one_iteration_loop(this) &&
4760 !lpt->do_remove_empty_loop(this)) {
4761 AutoNodeBudget node_budget(this);
4762 if (lpt->_head->as_CountedLoop()->is_normal_loop() &&
4763 lpt->policy_maximally_unroll(this)) {
4764 memset( worklist.adr(), 0, worklist.max()*sizeof(Node*) );
4765 do_maximally_unroll(lpt, worklist);
4766 }
4767 }
4768 }
4769 }
4770
4771 C->restore_major_progress(old_progress);
4772 return;
4773 }
4774
4775 if (bs->optimize_loops(this, _mode, visited, nstack, worklist)) {
4776 return;
4777 }
4778
4779 if (ReassociateInvariants && !C->major_progress()) {
4780 // Reassociate invariants and prep for split_thru_phi
4781 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
4782 IdealLoopTree* lpt = iter.current();
4783 if (!lpt->is_loop()) {
4784 continue;
4785 }
4786 Node* head = lpt->_head;
4787 if (!head->is_BaseCountedLoop() || !lpt->is_innermost()) continue;
4788
4789 // check for vectorized loops, any reassociation of invariants was already done
4790 if (head->is_CountedLoop()) {
4791 if (head->as_CountedLoop()->is_unroll_only()) {
4792 continue;
4793 } else {
4794 AutoNodeBudget node_budget(this);
4795 lpt->reassociate_invariants(this);
4796 }
4797 }
4798 // Because RCE opportunities can be masked by split_thru_phi,
4799 // look for RCE candidates and inhibit split_thru_phi
4800 // on just their loop-phi's for this pass of loop opts
4801 if (SplitIfBlocks && do_split_ifs &&
4802 head->as_BaseCountedLoop()->is_valid_counted_loop(head->as_BaseCountedLoop()->bt()) &&
4803 (lpt->policy_range_check(this, true, T_LONG) ||
4804 (head->is_CountedLoop() && lpt->policy_range_check(this, true, T_INT)))) {
4805 lpt->_rce_candidate = 1; // = true
4806 }
4807 }
4808 }
4809
4810 // Check for aggressive application of split-if and other transforms
4811 // that require basic-block info (like cloning through Phi's)
4812 if (!C->major_progress() && SplitIfBlocks && do_split_ifs) {
4813 visited.clear();
4814 split_if_with_blocks( visited, nstack);
4815 DEBUG_ONLY( if (VerifyLoopOptimizations) { verify(); } );
4816 }
4817
4818 if (!C->major_progress() && do_expensive_nodes && process_expensive_nodes()) {
4819 C->set_major_progress();
4820 }
4821
4822 // Perform loop predication before iteration splitting
4823 if (UseLoopPredicate && C->has_loops() && !C->major_progress() && (C->parse_predicate_count() > 0)) {
4824 _ltree_root->_child->loop_predication(this);
4825 }
4826
4827 if (OptimizeFill && UseLoopPredicate && C->has_loops() && !C->major_progress()) {
4828 if (do_intrinsify_fill()) {
4829 C->set_major_progress();
4830 }
4831 }
4832
4833 // Perform iteration-splitting on inner loops. Split iterations to avoid
4834 // range checks or one-shot null checks.
4835
4836 // If split-if's didn't hack the graph too bad (no CFG changes)
4837 // then do loop opts.
4838 if (C->has_loops() && !C->major_progress()) {
4839 memset( worklist.adr(), 0, worklist.max()*sizeof(Node*) );
4840 _ltree_root->_child->iteration_split( this, worklist );
4841 // No verify after peeling! GCM has hoisted code out of the loop.
4842 // After peeling, the hoisted code could sink inside the peeled area.
4843 // The peeling code does not try to recompute the best location for
4844 // all the code before the peeled area, so the verify pass will always
4845 // complain about it.
4846 }
4847
4848 // Check for bailout, and return
4849 if (C->failing()) {
4850 return;
4851 }
4852
4853 // Do verify graph edges in any case
4854 NOT_PRODUCT( C->verify_graph_edges(); );
4855
4856 if (!do_split_ifs) {
4857 // We saw major progress in Split-If to get here. We forced a
4858 // pass with unrolling and not split-if, however more split-if's
4859 // might make progress. If the unrolling didn't make progress
4860 // then the major-progress flag got cleared and we won't try
4861 // another round of Split-If. In particular the ever-common
4862 // instance-of/check-cast pattern requires at least 2 rounds of
4863 // Split-If to clear out.
4864 C->set_major_progress();
4865 }
4866
4867 // Repeat loop optimizations if new loops were seen
4868 if (created_loop_node()) {
4869 C->set_major_progress();
4870 }
4871
4872 // Keep loop predicates and perform optimizations with them
4873 // until no more loop optimizations could be done.
4874 // After that switch predicates off and do more loop optimizations.
4875 if (!C->major_progress() && (C->parse_predicate_count() > 0)) {
4876 C->mark_parse_predicate_nodes_useless(_igvn);
4877 assert(C->parse_predicate_count() == 0, "should be zero now");
4878 if (TraceLoopOpts) {
4879 tty->print_cr("PredicatesOff");
4880 }
4881 C->set_major_progress();
4882 }
4883
4884 // Auto-vectorize main-loop
4885 if (C->do_superword() && C->has_loops() && !C->major_progress()) {
4886 Compile::TracePhase tp("autoVectorize", &timers[_t_autoVectorize]);
4887
4888 // Shared data structures for all AutoVectorizations, to reduce allocations
4889 // of large arrays.
4890 VSharedData vshared;
4891 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
4892 IdealLoopTree* lpt = iter.current();
4893 AutoVectorizeStatus status = auto_vectorize(lpt, vshared);
4894
4895 if (status == AutoVectorizeStatus::TriedAndFailed) {
4896 // We tried vectorization, but failed. From now on only unroll the loop.
4897 CountedLoopNode* cl = lpt->_head->as_CountedLoop();
4898 if (cl->has_passed_slp()) {
4899 C->set_major_progress();
4900 cl->set_notpassed_slp();
4901 cl->mark_do_unroll_only();
4902 }
4903 }
4904 }
4905 }
4906
4907 // Move UnorderedReduction out of counted loop. Can be introduced by AutoVectorization.
4908 if (C->has_loops() && !C->major_progress()) {
4909 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
4910 IdealLoopTree* lpt = iter.current();
4911 if (lpt->is_counted() && lpt->is_innermost()) {
4912 move_unordered_reduction_out_of_loop(lpt);
4913 }
4914 }
4915 }
4916 }
4917
4918 #ifndef PRODUCT
4919 //------------------------------print_statistics-------------------------------
4920 int PhaseIdealLoop::_loop_invokes=0;// Count of PhaseIdealLoop invokes
4921 int PhaseIdealLoop::_loop_work=0; // Sum of PhaseIdealLoop x unique
4922 volatile int PhaseIdealLoop::_long_loop_candidates=0; // Number of long loops seen
4923 volatile int PhaseIdealLoop::_long_loop_nests=0; // Number of long loops successfully transformed to a nest
4924 volatile int PhaseIdealLoop::_long_loop_counted_loops=0; // Number of long loops successfully transformed to a counted loop
4925 void PhaseIdealLoop::print_statistics() {
4926 tty->print_cr("PhaseIdealLoop=%d, sum _unique=%d, long loops=%d/%d/%d", _loop_invokes, _loop_work, _long_loop_counted_loops, _long_loop_nests, _long_loop_candidates);
4927 }
4928 #endif
4929
4930 #ifdef ASSERT
4931 // Build a verify-only PhaseIdealLoop, and see that it agrees with "this".
4932 void PhaseIdealLoop::verify() const {
4933 ResourceMark rm;
4934 int old_progress = C->major_progress();
4935 bool success = true;
4936
4937 PhaseIdealLoop phase_verify(_igvn, this);
4938 if (C->failing_internal()) {
4939 return;
4940 }
4941
4942 // Verify ctrl and idom of every node.
4943 success &= verify_idom_and_nodes(C->root(), &phase_verify);
4944
4945 // Verify loop-tree.
4946 success &= _ltree_root->verify_tree(phase_verify._ltree_root);
4947
4948 assert(success, "VerifyLoopOptimizations failed");
4949
4950 // Major progress was cleared by creating a verify version of PhaseIdealLoop.
4951 C->restore_major_progress(old_progress);
4952 }
4953
4954 // Perform a BFS starting at n, through all inputs.
4955 // Call verify_idom and verify_node on all nodes of BFS traversal.
4956 bool PhaseIdealLoop::verify_idom_and_nodes(Node* root, const PhaseIdealLoop* phase_verify) const {
4957 Unique_Node_List worklist;
4958 worklist.push(root);
4959 bool success = true;
4960 for (uint i = 0; i < worklist.size(); i++) {
4961 Node* n = worklist.at(i);
4962 // process node
4963 success &= verify_idom(n, phase_verify);
4964 success &= verify_loop_ctrl(n, phase_verify);
4965 // visit inputs
4966 for (uint j = 0; j < n->req(); j++) {
4967 if (n->in(j) != nullptr) {
4968 worklist.push(n->in(j));
4969 }
4970 }
4971 }
4972 return success;
4973 }
4974
4975 // Verify dominator structure (IDOM).
4976 bool PhaseIdealLoop::verify_idom(Node* n, const PhaseIdealLoop* phase_verify) const {
4977 // Verify IDOM for all CFG nodes (except root).
4978 if (!n->is_CFG() || n->is_Root()) {
4979 return true; // pass
4980 }
4981
4982 if (n->_idx >= _idom_size) {
4983 tty->print("CFG Node with no idom: ");
4984 n->dump();
4985 return false; // fail
4986 }
4987
4988 Node* id = idom_no_update(n);
4989 Node* id_verify = phase_verify->idom_no_update(n);
4990 if (id != id_verify) {
4991 tty->print("Mismatching idom for node: ");
4992 n->dump();
4993 tty->print(" We have idom: ");
4994 id->dump();
4995 tty->print(" Verify has idom: ");
4996 id_verify->dump();
4997 tty->cr();
4998 return false; // fail
4999 }
5000 return true; // pass
5001 }
5002
5003 // Verify "_loop_or_ctrl": control and loop membership.
5004 // (0) _loop_or_ctrl[i] == nullptr -> node not reachable.
5005 // (1) has_ctrl -> check lowest bit. 1 -> data node. 0 -> ctrl node.
5006 // (2) has_ctrl true: get_ctrl_no_update returns ctrl of data node.
5007 // (3) has_ctrl false: get_loop_idx returns IdealLoopTree for ctrl node.
5008 bool PhaseIdealLoop::verify_loop_ctrl(Node* n, const PhaseIdealLoop* phase_verify) const {
5009 const uint i = n->_idx;
5010 // The loop-tree was built from def to use (top-down).
5011 // The verification happens from use to def (bottom-up).
5012 // We may thus find nodes during verification that are not in the loop-tree.
5013 if (_loop_or_ctrl[i] == nullptr || phase_verify->_loop_or_ctrl[i] == nullptr) {
5014 if (_loop_or_ctrl[i] != nullptr || phase_verify->_loop_or_ctrl[i] != nullptr) {
5015 tty->print_cr("Was reachable in only one. this %d, verify %d.",
5016 _loop_or_ctrl[i] != nullptr, phase_verify->_loop_or_ctrl[i] != nullptr);
5017 n->dump();
5018 return false; // fail
5019 }
5020 // Not reachable for both.
5021 return true; // pass
5022 }
5023
5024 if (n->is_CFG() == has_ctrl(n)) {
5025 tty->print_cr("Exactly one should be true: %d for is_CFG, %d for has_ctrl.", n->is_CFG(), has_ctrl(n));
5026 n->dump();
5027 return false; // fail
5028 }
5029
5030 if (has_ctrl(n) != phase_verify->has_ctrl(n)) {
5031 tty->print_cr("Mismatch has_ctrl: %d for this, %d for verify.", has_ctrl(n), phase_verify->has_ctrl(n));
5032 n->dump();
5033 return false; // fail
5034 } else if (has_ctrl(n)) {
5035 assert(phase_verify->has_ctrl(n), "sanity");
5036 // n is a data node.
5037 // Verify that its ctrl is the same.
5038
5039 // Broken part of VerifyLoopOptimizations (A)
5040 // Reason:
5041 // BUG, wrong control set for example in
5042 // PhaseIdealLoop::split_if_with_blocks
5043 // at "set_ctrl(x, new_ctrl);"
5044 /*
5045 if( _loop_or_ctrl[i] != loop_verify->_loop_or_ctrl[i] &&
5046 get_ctrl_no_update(n) != loop_verify->get_ctrl_no_update(n) ) {
5047 tty->print("Mismatched control setting for: ");
5048 n->dump();
5049 if( fail++ > 10 ) return;
5050 Node *c = get_ctrl_no_update(n);
5051 tty->print("We have it as: ");
5052 if( c->in(0) ) c->dump();
5053 else tty->print_cr("N%d",c->_idx);
5054 tty->print("Verify thinks: ");
5055 if( loop_verify->has_ctrl(n) )
5056 loop_verify->get_ctrl_no_update(n)->dump();
5057 else
5058 loop_verify->get_loop_idx(n)->dump();
5059 tty->cr();
5060 }
5061 */
5062 return true; // pass
5063 } else {
5064 assert(!phase_verify->has_ctrl(n), "sanity");
5065 // n is a ctrl node.
5066 // Verify that not has_ctrl, and that get_loop_idx is the same.
5067
5068 // Broken part of VerifyLoopOptimizations (B)
5069 // Reason:
5070 // NeverBranch node for example is added to loop outside its scope.
5071 // Once we run build_loop_tree again, it is added to the correct loop.
5072 /*
5073 if (!C->major_progress()) {
5074 // Loop selection can be messed up if we did a major progress
5075 // operation, like split-if. Do not verify in that case.
5076 IdealLoopTree *us = get_loop_idx(n);
5077 IdealLoopTree *them = loop_verify->get_loop_idx(n);
5078 if( us->_head != them->_head || us->_tail != them->_tail ) {
5079 tty->print("Unequals loops for: ");
5080 n->dump();
5081 if( fail++ > 10 ) return;
5082 tty->print("We have it as: ");
5083 us->dump();
5084 tty->print("Verify thinks: ");
5085 them->dump();
5086 tty->cr();
5087 }
5088 }
5089 */
5090 return true; // pass
5091 }
5092 }
5093
5094 static int compare_tree(IdealLoopTree* const& a, IdealLoopTree* const& b) {
5095 assert(a != nullptr && b != nullptr, "must be");
5096 return a->_head->_idx - b->_head->_idx;
5097 }
5098
5099 GrowableArray<IdealLoopTree*> IdealLoopTree::collect_sorted_children() const {
5100 GrowableArray<IdealLoopTree*> children;
5101 IdealLoopTree* child = _child;
5102 while (child != nullptr) {
5103 assert(child->_parent == this, "all must be children of this");
5104 children.insert_sorted<compare_tree>(child);
5105 child = child->_next;
5106 }
5107 return children;
5108 }
5109
5110 // Verify that tree structures match. Because the CFG can change, siblings
5111 // within the loop tree can be reordered. We attempt to deal with that by
5112 // reordering the verify's loop tree if possible.
5113 bool IdealLoopTree::verify_tree(IdealLoopTree* loop_verify) const {
5114 assert(_head == loop_verify->_head, "mismatched loop head");
5115 assert(this->_parent != nullptr || this->_next == nullptr, "is_root_loop implies has_no_sibling");
5116
5117 // Collect the children
5118 GrowableArray<IdealLoopTree*> children = collect_sorted_children();
5119 GrowableArray<IdealLoopTree*> children_verify = loop_verify->collect_sorted_children();
5120
5121 bool success = true;
5122
5123 // Compare the two children lists
5124 for (int i = 0, j = 0; i < children.length() || j < children_verify.length(); ) {
5125 IdealLoopTree* child = nullptr;
5126 IdealLoopTree* child_verify = nullptr;
5127 // Read from both lists, if possible.
5128 if (i < children.length()) {
5129 child = children.at(i);
5130 }
5131 if (j < children_verify.length()) {
5132 child_verify = children_verify.at(j);
5133 }
5134 assert(child != nullptr || child_verify != nullptr, "must find at least one");
5135 if (child != nullptr && child_verify != nullptr && child->_head != child_verify->_head) {
5136 // We found two non-equal children. Select the smaller one.
5137 if (child->_head->_idx < child_verify->_head->_idx) {
5138 child_verify = nullptr;
5139 } else {
5140 child = nullptr;
5141 }
5142 }
5143 // Process the two children, or potentially log the failure if we only found one.
5144 if (child_verify == nullptr) {
5145 if (child->_irreducible && Compile::current()->major_progress()) {
5146 // Irreducible loops can pick a different header (one of its entries).
5147 } else {
5148 tty->print_cr("We have a loop that verify does not have");
5149 child->dump();
5150 success = false;
5151 }
5152 i++; // step for this
5153 } else if (child == nullptr) {
5154 if (child_verify->_irreducible && Compile::current()->major_progress()) {
5155 // Irreducible loops can pick a different header (one of its entries).
5156 } else if (child_verify->_head->as_Region()->is_in_infinite_subgraph()) {
5157 // Infinite loops do not get attached to the loop-tree on their first visit.
5158 // "this" runs before "loop_verify". It is thus possible that we find the
5159 // infinite loop only for "child_verify". Only finding it with "child" would
5160 // mean that we lost it, which is not ok.
5161 } else {
5162 tty->print_cr("Verify has a loop that we do not have");
5163 child_verify->dump();
5164 success = false;
5165 }
5166 j++; // step for verify
5167 } else {
5168 assert(child->_head == child_verify->_head, "We have both and they are equal");
5169 success &= child->verify_tree(child_verify); // Recursion
5170 i++; // step for this
5171 j++; // step for verify
5172 }
5173 }
5174
5175 // Broken part of VerifyLoopOptimizations (D)
5176 // Reason:
5177 // split_if has to update the _tail, if it is modified. But that is done by
5178 // checking to what loop the iff belongs to. That info can be wrong, and then
5179 // we do not update the _tail correctly.
5180 /*
5181 Node *tail = _tail; // Inline a non-updating version of
5182 while( !tail->in(0) ) // the 'tail()' call.
5183 tail = tail->in(1);
5184 assert( tail == loop->_tail, "mismatched loop tail" );
5185 */
5186
5187 if (_head->is_CountedLoop()) {
5188 CountedLoopNode *cl = _head->as_CountedLoop();
5189
5190 Node* ctrl = cl->init_control();
5191 Node* back = cl->back_control();
5192 assert(ctrl != nullptr && ctrl->is_CFG(), "sane loop in-ctrl");
5193 assert(back != nullptr && back->is_CFG(), "sane loop backedge");
5194 cl->loopexit(); // assert implied
5195 }
5196
5197 // Broken part of VerifyLoopOptimizations (E)
5198 // Reason:
5199 // PhaseIdealLoop::split_thru_region creates new nodes for loop that are not added
5200 // to the loop body. Or maybe they are not added to the correct loop.
5201 // at "Node* x = n->clone();"
5202 /*
5203 // Innermost loops need to verify loop bodies,
5204 // but only if no 'major_progress'
5205 int fail = 0;
5206 if (!Compile::current()->major_progress() && _child == nullptr) {
5207 for( uint i = 0; i < _body.size(); i++ ) {
5208 Node *n = _body.at(i);
5209 if (n->outcnt() == 0) continue; // Ignore dead
5210 uint j;
5211 for( j = 0; j < loop->_body.size(); j++ )
5212 if( loop->_body.at(j) == n )
5213 break;
5214 if( j == loop->_body.size() ) { // Not found in loop body
5215 // Last ditch effort to avoid assertion: Its possible that we
5216 // have some users (so outcnt not zero) but are still dead.
5217 // Try to find from root.
5218 if (Compile::current()->root()->find(n->_idx)) {
5219 fail++;
5220 tty->print("We have that verify does not: ");
5221 n->dump();
5222 }
5223 }
5224 }
5225 for( uint i2 = 0; i2 < loop->_body.size(); i2++ ) {
5226 Node *n = loop->_body.at(i2);
5227 if (n->outcnt() == 0) continue; // Ignore dead
5228 uint j;
5229 for( j = 0; j < _body.size(); j++ )
5230 if( _body.at(j) == n )
5231 break;
5232 if( j == _body.size() ) { // Not found in loop body
5233 // Last ditch effort to avoid assertion: Its possible that we
5234 // have some users (so outcnt not zero) but are still dead.
5235 // Try to find from root.
5236 if (Compile::current()->root()->find(n->_idx)) {
5237 fail++;
5238 tty->print("Verify has that we do not: ");
5239 n->dump();
5240 }
5241 }
5242 }
5243 assert( !fail, "loop body mismatch" );
5244 }
5245 */
5246 return success;
5247 }
5248 #endif
5249
5250 //------------------------------set_idom---------------------------------------
5251 void PhaseIdealLoop::set_idom(Node* d, Node* n, uint dom_depth) {
5252 _nesting.check(); // Check if a potential reallocation in the resource arena is safe
5253 uint idx = d->_idx;
5254 if (idx >= _idom_size) {
5255 uint newsize = next_power_of_2(idx);
5256 _idom = REALLOC_RESOURCE_ARRAY( Node*, _idom,_idom_size,newsize);
5257 _dom_depth = REALLOC_RESOURCE_ARRAY( uint, _dom_depth,_idom_size,newsize);
5258 memset( _dom_depth + _idom_size, 0, (newsize - _idom_size) * sizeof(uint) );
5259 _idom_size = newsize;
5260 }
5261 _idom[idx] = n;
5262 _dom_depth[idx] = dom_depth;
5263 }
5264
5265 //------------------------------recompute_dom_depth---------------------------------------
5266 // The dominator tree is constructed with only parent pointers.
5267 // This recomputes the depth in the tree by first tagging all
5268 // nodes as "no depth yet" marker. The next pass then runs up
5269 // the dom tree from each node marked "no depth yet", and computes
5270 // the depth on the way back down.
5271 void PhaseIdealLoop::recompute_dom_depth() {
5272 uint no_depth_marker = C->unique();
5273 uint i;
5274 // Initialize depth to "no depth yet" and realize all lazy updates
5275 for (i = 0; i < _idom_size; i++) {
5276 // Only indices with a _dom_depth has a Node* or null (otherwise uninitialized).
5277 if (_dom_depth[i] > 0 && _idom[i] != nullptr) {
5278 _dom_depth[i] = no_depth_marker;
5279
5280 // heal _idom if it has a fwd mapping in _loop_or_ctrl
5281 if (_idom[i]->in(0) == nullptr) {
5282 idom(i);
5283 }
5284 }
5285 }
5286 if (_dom_stk == nullptr) {
5287 uint init_size = C->live_nodes() / 100; // Guess that 1/100 is a reasonable initial size.
5288 if (init_size < 10) init_size = 10;
5289 _dom_stk = new GrowableArray<uint>(init_size);
5290 }
5291 // Compute new depth for each node.
5292 for (i = 0; i < _idom_size; i++) {
5293 uint j = i;
5294 // Run up the dom tree to find a node with a depth
5295 while (_dom_depth[j] == no_depth_marker) {
5296 _dom_stk->push(j);
5297 j = _idom[j]->_idx;
5298 }
5299 // Compute the depth on the way back down this tree branch
5300 uint dd = _dom_depth[j] + 1;
5301 while (_dom_stk->length() > 0) {
5302 uint j = _dom_stk->pop();
5303 _dom_depth[j] = dd;
5304 dd++;
5305 }
5306 }
5307 }
5308
5309 //------------------------------sort-------------------------------------------
5310 // Insert 'loop' into the existing loop tree. 'innermost' is a leaf of the
5311 // loop tree, not the root.
5312 IdealLoopTree *PhaseIdealLoop::sort( IdealLoopTree *loop, IdealLoopTree *innermost ) {
5313 if( !innermost ) return loop; // New innermost loop
5314
5315 int loop_preorder = get_preorder(loop->_head); // Cache pre-order number
5316 assert( loop_preorder, "not yet post-walked loop" );
5317 IdealLoopTree **pp = &innermost; // Pointer to previous next-pointer
5318 IdealLoopTree *l = *pp; // Do I go before or after 'l'?
5319
5320 // Insert at start of list
5321 while( l ) { // Insertion sort based on pre-order
5322 if( l == loop ) return innermost; // Already on list!
5323 int l_preorder = get_preorder(l->_head); // Cache pre-order number
5324 assert( l_preorder, "not yet post-walked l" );
5325 // Check header pre-order number to figure proper nesting
5326 if( loop_preorder > l_preorder )
5327 break; // End of insertion
5328 // If headers tie (e.g., shared headers) check tail pre-order numbers.
5329 // Since I split shared headers, you'd think this could not happen.
5330 // BUT: I must first do the preorder numbering before I can discover I
5331 // have shared headers, so the split headers all get the same preorder
5332 // number as the RegionNode they split from.
5333 if( loop_preorder == l_preorder &&
5334 get_preorder(loop->_tail) < get_preorder(l->_tail) )
5335 break; // Also check for shared headers (same pre#)
5336 pp = &l->_parent; // Chain up list
5337 l = *pp;
5338 }
5339 // Link into list
5340 // Point predecessor to me
5341 *pp = loop;
5342 // Point me to successor
5343 IdealLoopTree *p = loop->_parent;
5344 loop->_parent = l; // Point me to successor
5345 if( p ) sort( p, innermost ); // Insert my parents into list as well
5346 return innermost;
5347 }
5348
5349 //------------------------------build_loop_tree--------------------------------
5350 // I use a modified Vick/Tarjan algorithm. I need pre- and a post- visit
5351 // bits. The _loop_or_ctrl[] array is mapped by Node index and holds a null for
5352 // not-yet-pre-walked, pre-order # for pre-but-not-post-walked and holds the
5353 // tightest enclosing IdealLoopTree for post-walked.
5354 //
5355 // During my forward walk I do a short 1-layer lookahead to see if I can find
5356 // a loop backedge with that doesn't have any work on the backedge. This
5357 // helps me construct nested loops with shared headers better.
5358 //
5359 // Once I've done the forward recursion, I do the post-work. For each child
5360 // I check to see if there is a backedge. Backedges define a loop! I
5361 // insert an IdealLoopTree at the target of the backedge.
5362 //
5363 // During the post-work I also check to see if I have several children
5364 // belonging to different loops. If so, then this Node is a decision point
5365 // where control flow can choose to change loop nests. It is at this
5366 // decision point where I can figure out how loops are nested. At this
5367 // time I can properly order the different loop nests from my children.
5368 // Note that there may not be any backedges at the decision point!
5369 //
5370 // Since the decision point can be far removed from the backedges, I can't
5371 // order my loops at the time I discover them. Thus at the decision point
5372 // I need to inspect loop header pre-order numbers to properly nest my
5373 // loops. This means I need to sort my childrens' loops by pre-order.
5374 // The sort is of size number-of-control-children, which generally limits
5375 // it to size 2 (i.e., I just choose between my 2 target loops).
5376 void PhaseIdealLoop::build_loop_tree() {
5377 // Allocate stack of size C->live_nodes()/2 to avoid frequent realloc
5378 GrowableArray <Node *> bltstack(C->live_nodes() >> 1);
5379 Node *n = C->root();
5380 bltstack.push(n);
5381 int pre_order = 1;
5382 int stack_size;
5383
5384 while ( ( stack_size = bltstack.length() ) != 0 ) {
5385 n = bltstack.top(); // Leave node on stack
5386 if ( !is_visited(n) ) {
5387 // ---- Pre-pass Work ----
5388 // Pre-walked but not post-walked nodes need a pre_order number.
5389
5390 set_preorder_visited( n, pre_order ); // set as visited
5391
5392 // ---- Scan over children ----
5393 // Scan first over control projections that lead to loop headers.
5394 // This helps us find inner-to-outer loops with shared headers better.
5395
5396 // Scan children's children for loop headers.
5397 for ( int i = n->outcnt() - 1; i >= 0; --i ) {
5398 Node* m = n->raw_out(i); // Child
5399 if( m->is_CFG() && !is_visited(m) ) { // Only for CFG children
5400 // Scan over children's children to find loop
5401 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
5402 Node* l = m->fast_out(j);
5403 if( is_visited(l) && // Been visited?
5404 !is_postvisited(l) && // But not post-visited
5405 get_preorder(l) < pre_order ) { // And smaller pre-order
5406 // Found! Scan the DFS down this path before doing other paths
5407 bltstack.push(m);
5408 break;
5409 }
5410 }
5411 }
5412 }
5413 pre_order++;
5414 }
5415 else if ( !is_postvisited(n) ) {
5416 // Note: build_loop_tree_impl() adds out edges on rare occasions,
5417 // such as com.sun.rsasign.am::a.
5418 // For non-recursive version, first, process current children.
5419 // On next iteration, check if additional children were added.
5420 for ( int k = n->outcnt() - 1; k >= 0; --k ) {
5421 Node* u = n->raw_out(k);
5422 if ( u->is_CFG() && !is_visited(u) ) {
5423 bltstack.push(u);
5424 }
5425 }
5426 if ( bltstack.length() == stack_size ) {
5427 // There were no additional children, post visit node now
5428 (void)bltstack.pop(); // Remove node from stack
5429 pre_order = build_loop_tree_impl(n, pre_order);
5430 // Check for bailout
5431 if (C->failing()) {
5432 return;
5433 }
5434 // Check to grow _preorders[] array for the case when
5435 // build_loop_tree_impl() adds new nodes.
5436 check_grow_preorders();
5437 }
5438 }
5439 else {
5440 (void)bltstack.pop(); // Remove post-visited node from stack
5441 }
5442 }
5443 DEBUG_ONLY(verify_regions_in_irreducible_loops();)
5444 }
5445
5446 //------------------------------build_loop_tree_impl---------------------------
5447 int PhaseIdealLoop::build_loop_tree_impl(Node* n, int pre_order) {
5448 // ---- Post-pass Work ----
5449 // Pre-walked but not post-walked nodes need a pre_order number.
5450
5451 // Tightest enclosing loop for this Node
5452 IdealLoopTree *innermost = nullptr;
5453
5454 // For all children, see if any edge is a backedge. If so, make a loop
5455 // for it. Then find the tightest enclosing loop for the self Node.
5456 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
5457 Node* m = n->fast_out(i); // Child
5458 if (n == m) continue; // Ignore control self-cycles
5459 if (!m->is_CFG()) continue;// Ignore non-CFG edges
5460
5461 IdealLoopTree *l; // Child's loop
5462 if (!is_postvisited(m)) { // Child visited but not post-visited?
5463 // Found a backedge
5464 assert(get_preorder(m) < pre_order, "should be backedge");
5465 // Check for the RootNode, which is already a LoopNode and is allowed
5466 // to have multiple "backedges".
5467 if (m == C->root()) { // Found the root?
5468 l = _ltree_root; // Root is the outermost LoopNode
5469 } else { // Else found a nested loop
5470 // Insert a LoopNode to mark this loop.
5471 l = new IdealLoopTree(this, m, n);
5472 } // End of Else found a nested loop
5473 if (!has_loop(m)) { // If 'm' does not already have a loop set
5474 set_loop(m, l); // Set loop header to loop now
5475 }
5476 } else { // Else not a nested loop
5477 if (!_loop_or_ctrl[m->_idx]) continue; // Dead code has no loop
5478 IdealLoopTree* m_loop = get_loop(m);
5479 l = m_loop; // Get previously determined loop
5480 // If successor is header of a loop (nest), move up-loop till it
5481 // is a member of some outer enclosing loop. Since there are no
5482 // shared headers (I've split them already) I only need to go up
5483 // at most 1 level.
5484 while (l && l->_head == m) { // Successor heads loop?
5485 l = l->_parent; // Move up 1 for me
5486 }
5487 // If this loop is not properly parented, then this loop
5488 // has no exit path out, i.e. its an infinite loop.
5489 if (!l) {
5490 // Make loop "reachable" from root so the CFG is reachable. Basically
5491 // insert a bogus loop exit that is never taken. 'm', the loop head,
5492 // points to 'n', one (of possibly many) fall-in paths. There may be
5493 // many backedges as well.
5494
5495 if (!_verify_only) {
5496 // Insert the NeverBranch between 'm' and it's control user.
5497 NeverBranchNode *iff = new NeverBranchNode( m );
5498 _igvn.register_new_node_with_optimizer(iff);
5499 set_loop(iff, m_loop);
5500 Node *if_t = new CProjNode( iff, 0 );
5501 _igvn.register_new_node_with_optimizer(if_t);
5502 set_loop(if_t, m_loop);
5503
5504 Node* cfg = nullptr; // Find the One True Control User of m
5505 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
5506 Node* x = m->fast_out(j);
5507 if (x->is_CFG() && x != m && x != iff)
5508 { cfg = x; break; }
5509 }
5510 assert(cfg != nullptr, "must find the control user of m");
5511 uint k = 0; // Probably cfg->in(0)
5512 while( cfg->in(k) != m ) k++; // But check in case cfg is a Region
5513 _igvn.replace_input_of(cfg, k, if_t); // Now point to NeverBranch
5514
5515 // Now create the never-taken loop exit
5516 Node *if_f = new CProjNode( iff, 1 );
5517 _igvn.register_new_node_with_optimizer(if_f);
5518 set_loop(if_f, _ltree_root);
5519 // Find frame ptr for Halt. Relies on the optimizer
5520 // V-N'ing. Easier and quicker than searching through
5521 // the program structure.
5522 Node *frame = new ParmNode( C->start(), TypeFunc::FramePtr );
5523 _igvn.register_new_node_with_optimizer(frame);
5524 // Halt & Catch Fire
5525 Node* halt = new HaltNode(if_f, frame, "never-taken loop exit reached");
5526 _igvn.register_new_node_with_optimizer(halt);
5527 set_loop(halt, _ltree_root);
5528 _igvn.add_input_to(C->root(), halt);
5529 }
5530 set_loop(C->root(), _ltree_root);
5531 // move to outer most loop with same header
5532 l = m_loop;
5533 while (true) {
5534 IdealLoopTree* next = l->_parent;
5535 if (next == nullptr || next->_head != m) {
5536 break;
5537 }
5538 l = next;
5539 }
5540 // properly insert infinite loop in loop tree
5541 sort(_ltree_root, l);
5542 // fix child link from parent
5543 IdealLoopTree* p = l->_parent;
5544 l->_next = p->_child;
5545 p->_child = l;
5546 // code below needs enclosing loop
5547 l = l->_parent;
5548 }
5549 }
5550 if (is_postvisited(l->_head)) {
5551 // We are currently visiting l, but its head has already been post-visited.
5552 // l is irreducible: we just found a second entry m.
5553 _has_irreducible_loops = true;
5554 RegionNode* secondary_entry = m->as_Region();
5555 DEBUG_ONLY(secondary_entry->verify_can_be_irreducible_entry();)
5556
5557 // Walk up the loop-tree, mark all loops that are already post-visited as irreducible
5558 // Since m is a secondary entry to them all.
5559 while( is_postvisited(l->_head) ) {
5560 l->_irreducible = 1; // = true
5561 RegionNode* head = l->_head->as_Region();
5562 DEBUG_ONLY(head->verify_can_be_irreducible_entry();)
5563 l = l->_parent;
5564 // Check for bad CFG here to prevent crash, and bailout of compile
5565 if (l == nullptr) {
5566 #ifndef PRODUCT
5567 if (TraceLoopOpts) {
5568 tty->print_cr("bailout: unhandled CFG: infinite irreducible loop");
5569 m->dump();
5570 }
5571 #endif
5572 // This is a rare case that we do not want to handle in C2.
5573 C->record_method_not_compilable("unhandled CFG detected during loop optimization");
5574 return pre_order;
5575 }
5576 }
5577 }
5578 if (!_verify_only) {
5579 C->set_has_irreducible_loop(_has_irreducible_loops);
5580 }
5581
5582 // This Node might be a decision point for loops. It is only if
5583 // it's children belong to several different loops. The sort call
5584 // does a trivial amount of work if there is only 1 child or all
5585 // children belong to the same loop. If however, the children
5586 // belong to different loops, the sort call will properly set the
5587 // _parent pointers to show how the loops nest.
5588 //
5589 // In any case, it returns the tightest enclosing loop.
5590 innermost = sort( l, innermost );
5591 }
5592
5593 // Def-use info will have some dead stuff; dead stuff will have no
5594 // loop decided on.
5595
5596 // Am I a loop header? If so fix up my parent's child and next ptrs.
5597 if( innermost && innermost->_head == n ) {
5598 assert( get_loop(n) == innermost, "" );
5599 IdealLoopTree *p = innermost->_parent;
5600 IdealLoopTree *l = innermost;
5601 while (p && l->_head == n) {
5602 l->_next = p->_child; // Put self on parents 'next child'
5603 p->_child = l; // Make self as first child of parent
5604 l = p; // Now walk up the parent chain
5605 p = l->_parent;
5606 }
5607 } else {
5608 // Note that it is possible for a LoopNode to reach here, if the
5609 // backedge has been made unreachable (hence the LoopNode no longer
5610 // denotes a Loop, and will eventually be removed).
5611
5612 // Record tightest enclosing loop for self. Mark as post-visited.
5613 set_loop(n, innermost);
5614 // Also record has_call flag early on
5615 if (innermost) {
5616 if( n->is_Call() && !n->is_CallLeaf() && !n->is_macro() ) {
5617 // Do not count uncommon calls
5618 if( !n->is_CallStaticJava() || !n->as_CallStaticJava()->_name ) {
5619 Node *iff = n->in(0)->in(0);
5620 // No any calls for vectorized loops.
5621 if (C->do_superword() ||
5622 !iff->is_If() ||
5623 (n->in(0)->Opcode() == Op_IfFalse && (1.0 - iff->as_If()->_prob) >= 0.01) ||
5624 iff->as_If()->_prob >= 0.01) {
5625 innermost->_has_call = 1;
5626 }
5627 }
5628 } else if( n->is_Allocate() && n->as_Allocate()->_is_scalar_replaceable ) {
5629 // Disable loop optimizations if the loop has a scalar replaceable
5630 // allocation. This disabling may cause a potential performance lost
5631 // if the allocation is not eliminated for some reason.
5632 innermost->_allow_optimizations = false;
5633 innermost->_has_call = 1; // = true
5634 } else if (n->Opcode() == Op_SafePoint) {
5635 // Record all safepoints in this loop.
5636 if (innermost->_safepts == nullptr) innermost->_safepts = new Node_List();
5637 innermost->_safepts->push(n);
5638 }
5639 }
5640 }
5641
5642 // Flag as post-visited now
5643 set_postvisited(n);
5644 return pre_order;
5645 }
5646
5647 #ifdef ASSERT
5648 //--------------------------verify_regions_in_irreducible_loops----------------
5649 // Iterate down from Root through CFG, verify for every region:
5650 // if it is in an irreducible loop it must be marked as such
5651 void PhaseIdealLoop::verify_regions_in_irreducible_loops() {
5652 ResourceMark rm;
5653 if (!_has_irreducible_loops) {
5654 // last build_loop_tree has not found any irreducible loops
5655 // hence no region has to be marked is_in_irreduible_loop
5656 return;
5657 }
5658
5659 RootNode* root = C->root();
5660 Unique_Node_List worklist; // visit all nodes once
5661 worklist.push(root);
5662 bool failure = false;
5663 for (uint i = 0; i < worklist.size(); i++) {
5664 Node* n = worklist.at(i);
5665 if (n->is_Region()) {
5666 RegionNode* region = n->as_Region();
5667 if (is_in_irreducible_loop(region) &&
5668 region->loop_status() == RegionNode::LoopStatus::Reducible) {
5669 failure = true;
5670 tty->print("irreducible! ");
5671 region->dump();
5672 }
5673 }
5674 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
5675 Node* use = n->fast_out(j);
5676 if (use->is_CFG()) {
5677 worklist.push(use); // push if was not pushed before
5678 }
5679 }
5680 }
5681 assert(!failure, "region in irreducible loop was marked as reducible");
5682 }
5683
5684 //---------------------------is_in_irreducible_loop-------------------------
5685 // Analogous to ciTypeFlow::Block::is_in_irreducible_loop
5686 bool PhaseIdealLoop::is_in_irreducible_loop(RegionNode* region) {
5687 if (!_has_irreducible_loops) {
5688 return false; // no irreducible loop in graph
5689 }
5690 IdealLoopTree* l = get_loop(region); // l: innermost loop that contains region
5691 do {
5692 if (l->_irreducible) {
5693 return true; // found it
5694 }
5695 if (l == _ltree_root) {
5696 return false; // reached root, terimnate
5697 }
5698 l = l->_parent;
5699 } while (l != nullptr);
5700 assert(region->is_in_infinite_subgraph(), "must be in infinite subgraph");
5701 // We have "l->_parent == nullptr", which happens only for infinite loops,
5702 // where no parent is attached to the loop. We did not find any irreducible
5703 // loop from this block out to lp. Thus lp only has one entry, and no exit
5704 // (it is infinite and reducible). We can always rewrite an infinite loop
5705 // that is nested inside other loops:
5706 // while(condition) { infinite_loop; }
5707 // with an equivalent program where the infinite loop is an outermost loop
5708 // that is not nested in any loop:
5709 // while(condition) { break; } infinite_loop;
5710 // Thus, we can understand lp as an outermost loop, and can terminate and
5711 // conclude: this block is in no irreducible loop.
5712 return false;
5713 }
5714 #endif
5715
5716 //------------------------------build_loop_early-------------------------------
5717 // Put Data nodes into some loop nest, by setting the _loop_or_ctrl[]->loop mapping.
5718 // First pass computes the earliest controlling node possible. This is the
5719 // controlling input with the deepest dominating depth.
5720 void PhaseIdealLoop::build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) {
5721 while (worklist.size() != 0) {
5722 // Use local variables nstack_top_n & nstack_top_i to cache values
5723 // on nstack's top.
5724 Node *nstack_top_n = worklist.pop();
5725 uint nstack_top_i = 0;
5726 //while_nstack_nonempty:
5727 while (true) {
5728 // Get parent node and next input's index from stack's top.
5729 Node *n = nstack_top_n;
5730 uint i = nstack_top_i;
5731 uint cnt = n->req(); // Count of inputs
5732 if (i == 0) { // Pre-process the node.
5733 if( has_node(n) && // Have either loop or control already?
5734 !has_ctrl(n) ) { // Have loop picked out already?
5735 // During "merge_many_backedges" we fold up several nested loops
5736 // into a single loop. This makes the members of the original
5737 // loop bodies pointing to dead loops; they need to move up
5738 // to the new UNION'd larger loop. I set the _head field of these
5739 // dead loops to null and the _parent field points to the owning
5740 // loop. Shades of UNION-FIND algorithm.
5741 IdealLoopTree *ilt;
5742 while( !(ilt = get_loop(n))->_head ) {
5743 // Normally I would use a set_loop here. But in this one special
5744 // case, it is legal (and expected) to change what loop a Node
5745 // belongs to.
5746 _loop_or_ctrl.map(n->_idx, (Node*)(ilt->_parent));
5747 }
5748 // Remove safepoints ONLY if I've already seen I don't need one.
5749 // (the old code here would yank a 2nd safepoint after seeing a
5750 // first one, even though the 1st did not dominate in the loop body
5751 // and thus could be avoided indefinitely)
5752 if( !_verify_only && !_verify_me && ilt->_has_sfpt && n->Opcode() == Op_SafePoint &&
5753 is_deleteable_safept(n)) {
5754 Node *in = n->in(TypeFunc::Control);
5755 lazy_replace(n,in); // Pull safepoint now
5756 if (ilt->_safepts != nullptr) {
5757 ilt->_safepts->yank(n);
5758 }
5759 // Carry on with the recursion "as if" we are walking
5760 // only the control input
5761 if( !visited.test_set( in->_idx ) ) {
5762 worklist.push(in); // Visit this guy later, using worklist
5763 }
5764 // Get next node from nstack:
5765 // - skip n's inputs processing by setting i > cnt;
5766 // - we also will not call set_early_ctrl(n) since
5767 // has_node(n) == true (see the condition above).
5768 i = cnt + 1;
5769 }
5770 }
5771 } // if (i == 0)
5772
5773 // Visit all inputs
5774 bool done = true; // Assume all n's inputs will be processed
5775 while (i < cnt) {
5776 Node *in = n->in(i);
5777 ++i;
5778 if (in == nullptr) continue;
5779 if (in->pinned() && !in->is_CFG())
5780 set_ctrl(in, in->in(0));
5781 int is_visited = visited.test_set( in->_idx );
5782 if (!has_node(in)) { // No controlling input yet?
5783 assert( !in->is_CFG(), "CFG Node with no controlling input?" );
5784 assert( !is_visited, "visit only once" );
5785 nstack.push(n, i); // Save parent node and next input's index.
5786 nstack_top_n = in; // Process current input now.
5787 nstack_top_i = 0;
5788 done = false; // Not all n's inputs processed.
5789 break; // continue while_nstack_nonempty;
5790 } else if (!is_visited) {
5791 // This guy has a location picked out for him, but has not yet
5792 // been visited. Happens to all CFG nodes, for instance.
5793 // Visit him using the worklist instead of recursion, to break
5794 // cycles. Since he has a location already we do not need to
5795 // find his location before proceeding with the current Node.
5796 worklist.push(in); // Visit this guy later, using worklist
5797 }
5798 }
5799 if (done) {
5800 // All of n's inputs have been processed, complete post-processing.
5801
5802 // Compute earliest point this Node can go.
5803 // CFG, Phi, pinned nodes already know their controlling input.
5804 if (!has_node(n)) {
5805 // Record earliest legal location
5806 set_early_ctrl(n, false);
5807 }
5808 if (nstack.is_empty()) {
5809 // Finished all nodes on stack.
5810 // Process next node on the worklist.
5811 break;
5812 }
5813 // Get saved parent node and next input's index.
5814 nstack_top_n = nstack.node();
5815 nstack_top_i = nstack.index();
5816 nstack.pop();
5817 }
5818 } // while (true)
5819 }
5820 }
5821
5822 //------------------------------dom_lca_internal--------------------------------
5823 // Pair-wise LCA
5824 Node *PhaseIdealLoop::dom_lca_internal( Node *n1, Node *n2 ) const {
5825 if( !n1 ) return n2; // Handle null original LCA
5826 assert( n1->is_CFG(), "" );
5827 assert( n2->is_CFG(), "" );
5828 // find LCA of all uses
5829 uint d1 = dom_depth(n1);
5830 uint d2 = dom_depth(n2);
5831 while (n1 != n2) {
5832 if (d1 > d2) {
5833 n1 = idom(n1);
5834 d1 = dom_depth(n1);
5835 } else if (d1 < d2) {
5836 n2 = idom(n2);
5837 d2 = dom_depth(n2);
5838 } else {
5839 // Here d1 == d2. Due to edits of the dominator-tree, sections
5840 // of the tree might have the same depth. These sections have
5841 // to be searched more carefully.
5842
5843 // Scan up all the n1's with equal depth, looking for n2.
5844 Node *t1 = idom(n1);
5845 while (dom_depth(t1) == d1) {
5846 if (t1 == n2) return n2;
5847 t1 = idom(t1);
5848 }
5849 // Scan up all the n2's with equal depth, looking for n1.
5850 Node *t2 = idom(n2);
5851 while (dom_depth(t2) == d2) {
5852 if (t2 == n1) return n1;
5853 t2 = idom(t2);
5854 }
5855 // Move up to a new dominator-depth value as well as up the dom-tree.
5856 n1 = t1;
5857 n2 = t2;
5858 d1 = dom_depth(n1);
5859 d2 = dom_depth(n2);
5860 }
5861 }
5862 return n1;
5863 }
5864
5865 //------------------------------compute_idom-----------------------------------
5866 // Locally compute IDOM using dom_lca call. Correct only if the incoming
5867 // IDOMs are correct.
5868 Node *PhaseIdealLoop::compute_idom( Node *region ) const {
5869 assert( region->is_Region(), "" );
5870 Node *LCA = nullptr;
5871 for( uint i = 1; i < region->req(); i++ ) {
5872 if( region->in(i) != C->top() )
5873 LCA = dom_lca( LCA, region->in(i) );
5874 }
5875 return LCA;
5876 }
5877
5878 bool PhaseIdealLoop::verify_dominance(Node* n, Node* use, Node* LCA, Node* early) {
5879 bool had_error = false;
5880 #ifdef ASSERT
5881 if (early != C->root()) {
5882 // Make sure that there's a dominance path from LCA to early
5883 Node* d = LCA;
5884 while (d != early) {
5885 if (d == C->root()) {
5886 dump_bad_graph("Bad graph detected in compute_lca_of_uses", n, early, LCA);
5887 tty->print_cr("*** Use %d isn't dominated by def %d ***", use->_idx, n->_idx);
5888 had_error = true;
5889 break;
5890 }
5891 d = idom(d);
5892 }
5893 }
5894 #endif
5895 return had_error;
5896 }
5897
5898
5899 Node* PhaseIdealLoop::compute_lca_of_uses(Node* n, Node* early, bool verify) {
5900 // Compute LCA over list of uses
5901 bool had_error = false;
5902 Node *LCA = nullptr;
5903 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax && LCA != early; i++) {
5904 Node* c = n->fast_out(i);
5905 if (_loop_or_ctrl[c->_idx] == nullptr)
5906 continue; // Skip the occasional dead node
5907 if( c->is_Phi() ) { // For Phis, we must land above on the path
5908 for( uint j=1; j<c->req(); j++ ) {// For all inputs
5909 if( c->in(j) == n ) { // Found matching input?
5910 Node *use = c->in(0)->in(j);
5911 if (_verify_only && use->is_top()) continue;
5912 LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
5913 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error;
5914 }
5915 }
5916 } else {
5917 // For CFG data-users, use is in the block just prior
5918 Node *use = has_ctrl(c) ? get_ctrl(c) : c->in(0);
5919 LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
5920 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error;
5921 }
5922 }
5923 assert(!had_error, "bad dominance");
5924 return LCA;
5925 }
5926
5927 // Check the shape of the graph at the loop entry. In some cases,
5928 // the shape of the graph does not match the shape outlined below.
5929 // That is caused by the Opaque1 node "protecting" the shape of
5930 // the graph being removed by, for example, the IGVN performed
5931 // in PhaseIdealLoop::build_and_optimize().
5932 //
5933 // After the Opaque1 node has been removed, optimizations (e.g., split-if,
5934 // loop unswitching, and IGVN, or a combination of them) can freely change
5935 // the graph's shape. As a result, the graph shape outlined below cannot
5936 // be guaranteed anymore.
5937 Node* CountedLoopNode::is_canonical_loop_entry() {
5938 if (!is_main_loop() && !is_post_loop()) {
5939 return nullptr;
5940 }
5941 Node* ctrl = skip_assertion_predicates_with_halt();
5942
5943 if (ctrl == nullptr || (!ctrl->is_IfTrue() && !ctrl->is_IfFalse())) {
5944 return nullptr;
5945 }
5946 Node* iffm = ctrl->in(0);
5947 if (iffm == nullptr || iffm->Opcode() != Op_If) {
5948 return nullptr;
5949 }
5950 Node* bolzm = iffm->in(1);
5951 if (bolzm == nullptr || !bolzm->is_Bool()) {
5952 return nullptr;
5953 }
5954 Node* cmpzm = bolzm->in(1);
5955 if (cmpzm == nullptr || !cmpzm->is_Cmp()) {
5956 return nullptr;
5957 }
5958
5959 uint input = is_main_loop() ? 2 : 1;
5960 if (input >= cmpzm->req() || cmpzm->in(input) == nullptr) {
5961 return nullptr;
5962 }
5963 bool res = cmpzm->in(input)->Opcode() == Op_OpaqueZeroTripGuard;
5964 #ifdef ASSERT
5965 bool found_opaque = false;
5966 for (uint i = 1; i < cmpzm->req(); i++) {
5967 Node* opnd = cmpzm->in(i);
5968 if (opnd && opnd->is_Opaque1()) {
5969 found_opaque = true;
5970 break;
5971 }
5972 }
5973 assert(found_opaque == res, "wrong pattern");
5974 #endif
5975 return res ? cmpzm->in(input) : nullptr;
5976 }
5977
5978 // Find pre loop end from main loop. Returns nullptr if none.
5979 CountedLoopEndNode* CountedLoopNode::find_pre_loop_end() {
5980 assert(is_main_loop(), "Can only find pre-loop from main-loop");
5981 // The loop cannot be optimized if the graph shape at the loop entry is
5982 // inappropriate.
5983 if (is_canonical_loop_entry() == nullptr) {
5984 return nullptr;
5985 }
5986
5987 Node* p_f = skip_assertion_predicates_with_halt()->in(0)->in(0);
5988 if (!p_f->is_IfFalse() || !p_f->in(0)->is_CountedLoopEnd()) {
5989 return nullptr;
5990 }
5991 CountedLoopEndNode* pre_end = p_f->in(0)->as_CountedLoopEnd();
5992 CountedLoopNode* loop_node = pre_end->loopnode();
5993 if (loop_node == nullptr || !loop_node->is_pre_loop()) {
5994 return nullptr;
5995 }
5996 return pre_end;
5997 }
5998
5999 //------------------------------get_late_ctrl----------------------------------
6000 // Compute latest legal control.
6001 Node *PhaseIdealLoop::get_late_ctrl( Node *n, Node *early ) {
6002 assert(early != nullptr, "early control should not be null");
6003
6004 Node* LCA = compute_lca_of_uses(n, early);
6005 #ifdef ASSERT
6006 if (LCA == C->root() && LCA != early) {
6007 // def doesn't dominate uses so print some useful debugging output
6008 compute_lca_of_uses(n, early, true);
6009 }
6010 #endif
6011
6012 if (n->is_Load() && LCA != early) {
6013 LCA = get_late_ctrl_with_anti_dep(n->as_Load(), early, LCA);
6014 }
6015
6016 assert(LCA == find_non_split_ctrl(LCA), "unexpected late control");
6017 return LCA;
6018 }
6019
6020 // if this is a load, check for anti-dependent stores
6021 // We use a conservative algorithm to identify potential interfering
6022 // instructions and for rescheduling the load. The users of the memory
6023 // input of this load are examined. Any use which is not a load and is
6024 // dominated by early is considered a potentially interfering store.
6025 // This can produce false positives.
6026 Node* PhaseIdealLoop::get_late_ctrl_with_anti_dep(LoadNode* n, Node* early, Node* LCA) {
6027 int load_alias_idx = C->get_alias_index(n->adr_type());
6028 if (C->alias_type(load_alias_idx)->is_rewritable()) {
6029 Unique_Node_List worklist;
6030
6031 Node* mem = n->in(MemNode::Memory);
6032 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
6033 Node* s = mem->fast_out(i);
6034 worklist.push(s);
6035 }
6036 for (uint i = 0; i < worklist.size() && LCA != early; i++) {
6037 Node* s = worklist.at(i);
6038 if (s->is_Load() || s->Opcode() == Op_SafePoint ||
6039 (s->is_CallStaticJava() && s->as_CallStaticJava()->uncommon_trap_request() != 0) ||
6040 s->is_Phi()) {
6041 continue;
6042 } else if (s->is_MergeMem()) {
6043 for (DUIterator_Fast imax, i = s->fast_outs(imax); i < imax; i++) {
6044 Node* s1 = s->fast_out(i);
6045 worklist.push(s1);
6046 }
6047 } else {
6048 Node* sctrl = has_ctrl(s) ? get_ctrl(s) : s->in(0);
6049 assert(sctrl != nullptr || !s->is_reachable_from_root(), "must have control");
6050 if (sctrl != nullptr && !sctrl->is_top() && is_dominator(early, sctrl)) {
6051 const TypePtr* adr_type = s->adr_type();
6052 if (s->is_ArrayCopy()) {
6053 // Copy to known instance needs destination type to test for aliasing
6054 const TypePtr* dest_type = s->as_ArrayCopy()->_dest_type;
6055 if (dest_type != TypeOopPtr::BOTTOM) {
6056 adr_type = dest_type;
6057 }
6058 }
6059 if (C->can_alias(adr_type, load_alias_idx)) {
6060 LCA = dom_lca_for_get_late_ctrl(LCA, sctrl, n);
6061 } else if (s->is_CFG() && s->is_Multi()) {
6062 // Look for the memory use of s (that is the use of its memory projection)
6063 for (DUIterator_Fast imax, i = s->fast_outs(imax); i < imax; i++) {
6064 Node* s1 = s->fast_out(i);
6065 assert(s1->is_Proj(), "projection expected");
6066 if (_igvn.type(s1) == Type::MEMORY) {
6067 for (DUIterator_Fast jmax, j = s1->fast_outs(jmax); j < jmax; j++) {
6068 Node* s2 = s1->fast_out(j);
6069 worklist.push(s2);
6070 }
6071 }
6072 }
6073 }
6074 }
6075 }
6076 }
6077 // For Phis only consider Region's inputs that were reached by following the memory edges
6078 if (LCA != early) {
6079 for (uint i = 0; i < worklist.size(); i++) {
6080 Node* s = worklist.at(i);
6081 if (s->is_Phi() && C->can_alias(s->adr_type(), load_alias_idx)) {
6082 Node* r = s->in(0);
6083 for (uint j = 1; j < s->req(); j++) {
6084 Node* in = s->in(j);
6085 Node* r_in = r->in(j);
6086 // We can't reach any node from a Phi because we don't enqueue Phi's uses above
6087 if (((worklist.member(in) && !in->is_Phi()) || in == mem) && is_dominator(early, r_in)) {
6088 LCA = dom_lca_for_get_late_ctrl(LCA, r_in, n);
6089 }
6090 }
6091 }
6092 }
6093 }
6094 }
6095 return LCA;
6096 }
6097
6098 // Is CFG node 'dominator' dominating node 'n'?
6099 bool PhaseIdealLoop::is_dominator(Node* dominator, Node* n) {
6100 if (dominator == n) {
6101 return true;
6102 }
6103 assert(dominator->is_CFG() && n->is_CFG(), "must have CFG nodes");
6104 uint dd = dom_depth(dominator);
6105 while (dom_depth(n) >= dd) {
6106 if (n == dominator) {
6107 return true;
6108 }
6109 n = idom(n);
6110 }
6111 return false;
6112 }
6113
6114 // Is CFG node 'dominator' strictly dominating node 'n'?
6115 bool PhaseIdealLoop::is_strict_dominator(Node* dominator, Node* n) {
6116 return dominator != n && is_dominator(dominator, n);
6117 }
6118
6119 //------------------------------dom_lca_for_get_late_ctrl_internal-------------
6120 // Pair-wise LCA with tags.
6121 // Tag each index with the node 'tag' currently being processed
6122 // before advancing up the dominator chain using idom().
6123 // Later calls that find a match to 'tag' know that this path has already
6124 // been considered in the current LCA (which is input 'n1' by convention).
6125 // Since get_late_ctrl() is only called once for each node, the tag array
6126 // does not need to be cleared between calls to get_late_ctrl().
6127 // Algorithm trades a larger constant factor for better asymptotic behavior
6128 //
6129 Node *PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal(Node *n1, Node *n2, Node *tag_node) {
6130 uint d1 = dom_depth(n1);
6131 uint d2 = dom_depth(n2);
6132 jlong tag = tag_node->_idx | (((jlong)_dom_lca_tags_round) << 32);
6133
6134 do {
6135 if (d1 > d2) {
6136 // current lca is deeper than n2
6137 _dom_lca_tags.at_put_grow(n1->_idx, tag);
6138 n1 = idom(n1);
6139 d1 = dom_depth(n1);
6140 } else if (d1 < d2) {
6141 // n2 is deeper than current lca
6142 jlong memo = _dom_lca_tags.at_grow(n2->_idx, 0);
6143 if (memo == tag) {
6144 return n1; // Return the current LCA
6145 }
6146 _dom_lca_tags.at_put_grow(n2->_idx, tag);
6147 n2 = idom(n2);
6148 d2 = dom_depth(n2);
6149 } else {
6150 // Here d1 == d2. Due to edits of the dominator-tree, sections
6151 // of the tree might have the same depth. These sections have
6152 // to be searched more carefully.
6153
6154 // Scan up all the n1's with equal depth, looking for n2.
6155 _dom_lca_tags.at_put_grow(n1->_idx, tag);
6156 Node *t1 = idom(n1);
6157 while (dom_depth(t1) == d1) {
6158 if (t1 == n2) return n2;
6159 _dom_lca_tags.at_put_grow(t1->_idx, tag);
6160 t1 = idom(t1);
6161 }
6162 // Scan up all the n2's with equal depth, looking for n1.
6163 _dom_lca_tags.at_put_grow(n2->_idx, tag);
6164 Node *t2 = idom(n2);
6165 while (dom_depth(t2) == d2) {
6166 if (t2 == n1) return n1;
6167 _dom_lca_tags.at_put_grow(t2->_idx, tag);
6168 t2 = idom(t2);
6169 }
6170 // Move up to a new dominator-depth value as well as up the dom-tree.
6171 n1 = t1;
6172 n2 = t2;
6173 d1 = dom_depth(n1);
6174 d2 = dom_depth(n2);
6175 }
6176 } while (n1 != n2);
6177 return n1;
6178 }
6179
6180 //------------------------------init_dom_lca_tags------------------------------
6181 // Tag could be a node's integer index, 32bits instead of 64bits in some cases
6182 // Intended use does not involve any growth for the array, so it could
6183 // be of fixed size.
6184 void PhaseIdealLoop::init_dom_lca_tags() {
6185 uint limit = C->unique() + 1;
6186 _dom_lca_tags.at_grow(limit, 0);
6187 _dom_lca_tags_round = 0;
6188 #ifdef ASSERT
6189 for (uint i = 0; i < limit; ++i) {
6190 assert(_dom_lca_tags.at(i) == 0, "Must be distinct from each node pointer");
6191 }
6192 #endif // ASSERT
6193 }
6194
6195 //------------------------------build_loop_late--------------------------------
6196 // Put Data nodes into some loop nest, by setting the _loop_or_ctrl[]->loop mapping.
6197 // Second pass finds latest legal placement, and ideal loop placement.
6198 void PhaseIdealLoop::build_loop_late( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) {
6199 while (worklist.size() != 0) {
6200 Node *n = worklist.pop();
6201 // Only visit once
6202 if (visited.test_set(n->_idx)) continue;
6203 uint cnt = n->outcnt();
6204 uint i = 0;
6205 while (true) {
6206 assert(_loop_or_ctrl[n->_idx], "no dead nodes");
6207 // Visit all children
6208 if (i < cnt) {
6209 Node* use = n->raw_out(i);
6210 ++i;
6211 // Check for dead uses. Aggressively prune such junk. It might be
6212 // dead in the global sense, but still have local uses so I cannot
6213 // easily call 'remove_dead_node'.
6214 if (_loop_or_ctrl[use->_idx] != nullptr || use->is_top()) { // Not dead?
6215 // Due to cycles, we might not hit the same fixed point in the verify
6216 // pass as we do in the regular pass. Instead, visit such phis as
6217 // simple uses of the loop head.
6218 if( use->in(0) && (use->is_CFG() || use->is_Phi()) ) {
6219 if( !visited.test(use->_idx) )
6220 worklist.push(use);
6221 } else if( !visited.test_set(use->_idx) ) {
6222 nstack.push(n, i); // Save parent and next use's index.
6223 n = use; // Process all children of current use.
6224 cnt = use->outcnt();
6225 i = 0;
6226 }
6227 } else {
6228 // Do not visit around the backedge of loops via data edges.
6229 // push dead code onto a worklist
6230 _deadlist.push(use);
6231 }
6232 } else {
6233 // All of n's children have been processed, complete post-processing.
6234 build_loop_late_post(n);
6235 if (C->failing()) { return; }
6236 if (nstack.is_empty()) {
6237 // Finished all nodes on stack.
6238 // Process next node on the worklist.
6239 break;
6240 }
6241 // Get saved parent node and next use's index. Visit the rest of uses.
6242 n = nstack.node();
6243 cnt = n->outcnt();
6244 i = nstack.index();
6245 nstack.pop();
6246 }
6247 }
6248 }
6249 }
6250
6251 // Verify that no data node is scheduled in the outer loop of a strip
6252 // mined loop.
6253 void PhaseIdealLoop::verify_strip_mined_scheduling(Node *n, Node* least) {
6254 #ifdef ASSERT
6255 if (get_loop(least)->_nest == 0) {
6256 return;
6257 }
6258 IdealLoopTree* loop = get_loop(least);
6259 Node* head = loop->_head;
6260 if (head->is_OuterStripMinedLoop() &&
6261 // Verification can't be applied to fully built strip mined loops
6262 head->as_Loop()->outer_loop_end()->in(1)->find_int_con(-1) == 0) {
6263 Node* sfpt = head->as_Loop()->outer_safepoint();
6264 ResourceMark rm;
6265 Unique_Node_List wq;
6266 wq.push(sfpt);
6267 for (uint i = 0; i < wq.size(); i++) {
6268 Node *m = wq.at(i);
6269 for (uint i = 1; i < m->req(); i++) {
6270 Node* nn = m->in(i);
6271 if (nn == n) {
6272 return;
6273 }
6274 if (nn != nullptr && has_ctrl(nn) && get_loop(get_ctrl(nn)) == loop) {
6275 wq.push(nn);
6276 }
6277 }
6278 }
6279 ShouldNotReachHere();
6280 }
6281 #endif
6282 }
6283
6284
6285 //------------------------------build_loop_late_post---------------------------
6286 // Put Data nodes into some loop nest, by setting the _loop_or_ctrl[]->loop mapping.
6287 // Second pass finds latest legal placement, and ideal loop placement.
6288 void PhaseIdealLoop::build_loop_late_post(Node *n) {
6289 build_loop_late_post_work(n, true);
6290 }
6291
6292 void PhaseIdealLoop::build_loop_late_post_work(Node *n, bool pinned) {
6293
6294 if (n->req() == 2 && (n->Opcode() == Op_ConvI2L || n->Opcode() == Op_CastII) && !C->major_progress() && !_verify_only) {
6295 _igvn._worklist.push(n); // Maybe we'll normalize it, if no more loops.
6296 }
6297
6298 #ifdef ASSERT
6299 if (_verify_only && !n->is_CFG()) {
6300 // Check def-use domination.
6301 compute_lca_of_uses(n, get_ctrl(n), true /* verify */);
6302 }
6303 #endif
6304
6305 // CFG and pinned nodes already handled
6306 if( n->in(0) ) {
6307 if( n->in(0)->is_top() ) return; // Dead?
6308
6309 // We'd like +VerifyLoopOptimizations to not believe that Mod's/Loads
6310 // _must_ be pinned (they have to observe their control edge of course).
6311 // Unlike Stores (which modify an unallocable resource, the memory
6312 // state), Mods/Loads can float around. So free them up.
6313 switch( n->Opcode() ) {
6314 case Op_DivI:
6315 case Op_DivF:
6316 case Op_DivD:
6317 case Op_ModI:
6318 case Op_ModF:
6319 case Op_ModD:
6320 case Op_LoadB: // Same with Loads; they can sink
6321 case Op_LoadUB: // during loop optimizations.
6322 case Op_LoadUS:
6323 case Op_LoadD:
6324 case Op_LoadF:
6325 case Op_LoadI:
6326 case Op_LoadKlass:
6327 case Op_LoadNKlass:
6328 case Op_LoadL:
6329 case Op_LoadS:
6330 case Op_LoadP:
6331 case Op_LoadN:
6332 case Op_LoadRange:
6333 case Op_LoadD_unaligned:
6334 case Op_LoadL_unaligned:
6335 case Op_StrComp: // Does a bunch of load-like effects
6336 case Op_StrEquals:
6337 case Op_StrIndexOf:
6338 case Op_StrIndexOfChar:
6339 case Op_AryEq:
6340 case Op_VectorizedHashCode:
6341 case Op_CountPositives:
6342 pinned = false;
6343 }
6344 if (n->is_CMove() || n->is_ConstraintCast()) {
6345 pinned = false;
6346 }
6347 if( pinned ) {
6348 IdealLoopTree *chosen_loop = get_loop(n->is_CFG() ? n : get_ctrl(n));
6349 if( !chosen_loop->_child ) // Inner loop?
6350 chosen_loop->_body.push(n); // Collect inner loops
6351 return;
6352 }
6353 } else { // No slot zero
6354 if( n->is_CFG() ) { // CFG with no slot 0 is dead
6355 _loop_or_ctrl.map(n->_idx,nullptr); // No block setting, it's globally dead
6356 return;
6357 }
6358 assert(!n->is_CFG() || n->outcnt() == 0, "");
6359 }
6360
6361 // Do I have a "safe range" I can select over?
6362 Node *early = get_ctrl(n);// Early location already computed
6363
6364 // Compute latest point this Node can go
6365 Node *LCA = get_late_ctrl( n, early );
6366 // LCA is null due to uses being dead
6367 if( LCA == nullptr ) {
6368 #ifdef ASSERT
6369 for (DUIterator i1 = n->outs(); n->has_out(i1); i1++) {
6370 assert(_loop_or_ctrl[n->out(i1)->_idx] == nullptr, "all uses must also be dead");
6371 }
6372 #endif
6373 _loop_or_ctrl.map(n->_idx, nullptr); // This node is useless
6374 _deadlist.push(n);
6375 return;
6376 }
6377 assert(LCA != nullptr && !LCA->is_top(), "no dead nodes");
6378
6379 Node *legal = LCA; // Walk 'legal' up the IDOM chain
6380 Node *least = legal; // Best legal position so far
6381 while( early != legal ) { // While not at earliest legal
6382 if (legal->is_Start() && !early->is_Root()) {
6383 #ifdef ASSERT
6384 // Bad graph. Print idom path and fail.
6385 dump_bad_graph("Bad graph detected in build_loop_late", n, early, LCA);
6386 assert(false, "Bad graph detected in build_loop_late");
6387 #endif
6388 C->record_method_not_compilable("Bad graph detected in build_loop_late");
6389 return;
6390 }
6391 // Find least loop nesting depth
6392 legal = idom(legal); // Bump up the IDOM tree
6393 // Check for lower nesting depth
6394 if( get_loop(legal)->_nest < get_loop(least)->_nest )
6395 least = legal;
6396 }
6397 assert(early == legal || legal != C->root(), "bad dominance of inputs");
6398
6399 if (least != early) {
6400 // Move the node above predicates as far up as possible so a
6401 // following pass of Loop Predication doesn't hoist a predicate
6402 // that depends on it above that node.
6403 PredicateEntryIterator predicate_iterator(least);
6404 while (predicate_iterator.has_next()) {
6405 Node* next_predicate_entry = predicate_iterator.next_entry();
6406 if (is_strict_dominator(next_predicate_entry, early)) {
6407 break;
6408 }
6409 least = next_predicate_entry;
6410 }
6411 }
6412 // Try not to place code on a loop entry projection
6413 // which can inhibit range check elimination.
6414 if (least != early && !BarrierSet::barrier_set()->barrier_set_c2()->is_gc_specific_loop_opts_pass(_mode)) {
6415 Node* ctrl_out = least->unique_ctrl_out_or_null();
6416 if (ctrl_out != nullptr && ctrl_out->is_Loop() &&
6417 least == ctrl_out->in(LoopNode::EntryControl) &&
6418 (ctrl_out->is_CountedLoop() || ctrl_out->is_OuterStripMinedLoop())) {
6419 Node* least_dom = idom(least);
6420 if (get_loop(least_dom)->is_member(get_loop(least))) {
6421 least = least_dom;
6422 }
6423 }
6424 }
6425 // Don't extend live ranges of raw oops
6426 if (least != early && n->is_ConstraintCast() && n->in(1)->bottom_type()->isa_rawptr() &&
6427 !n->bottom_type()->isa_rawptr()) {
6428 least = early;
6429 }
6430
6431 #ifdef ASSERT
6432 // Broken part of VerifyLoopOptimizations (F)
6433 // Reason:
6434 // _verify_me->get_ctrl_no_update(n) seems to return wrong result
6435 /*
6436 // If verifying, verify that 'verify_me' has a legal location
6437 // and choose it as our location.
6438 if( _verify_me ) {
6439 Node *v_ctrl = _verify_me->get_ctrl_no_update(n);
6440 Node *legal = LCA;
6441 while( early != legal ) { // While not at earliest legal
6442 if( legal == v_ctrl ) break; // Check for prior good location
6443 legal = idom(legal) ;// Bump up the IDOM tree
6444 }
6445 // Check for prior good location
6446 if( legal == v_ctrl ) least = legal; // Keep prior if found
6447 }
6448 */
6449 #endif
6450
6451 // Assign discovered "here or above" point
6452 least = find_non_split_ctrl(least);
6453 verify_strip_mined_scheduling(n, least);
6454 set_ctrl(n, least);
6455
6456 // Collect inner loop bodies
6457 IdealLoopTree *chosen_loop = get_loop(least);
6458 if( !chosen_loop->_child ) // Inner loop?
6459 chosen_loop->_body.push(n);// Collect inner loops
6460
6461 if (!_verify_only && n->Opcode() == Op_OpaqueZeroTripGuard) {
6462 _zero_trip_guard_opaque_nodes.push(n);
6463 }
6464
6465 }
6466
6467 #ifdef ASSERT
6468 void PhaseIdealLoop::dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA) {
6469 tty->print_cr("%s", msg);
6470 tty->print("n: "); n->dump();
6471 tty->print("early(n): "); early->dump();
6472 if (n->in(0) != nullptr && !n->in(0)->is_top() &&
6473 n->in(0) != early && !n->in(0)->is_Root()) {
6474 tty->print("n->in(0): "); n->in(0)->dump();
6475 }
6476 for (uint i = 1; i < n->req(); i++) {
6477 Node* in1 = n->in(i);
6478 if (in1 != nullptr && in1 != n && !in1->is_top()) {
6479 tty->print("n->in(%d): ", i); in1->dump();
6480 Node* in1_early = get_ctrl(in1);
6481 tty->print("early(n->in(%d)): ", i); in1_early->dump();
6482 if (in1->in(0) != nullptr && !in1->in(0)->is_top() &&
6483 in1->in(0) != in1_early && !in1->in(0)->is_Root()) {
6484 tty->print("n->in(%d)->in(0): ", i); in1->in(0)->dump();
6485 }
6486 for (uint j = 1; j < in1->req(); j++) {
6487 Node* in2 = in1->in(j);
6488 if (in2 != nullptr && in2 != n && in2 != in1 && !in2->is_top()) {
6489 tty->print("n->in(%d)->in(%d): ", i, j); in2->dump();
6490 Node* in2_early = get_ctrl(in2);
6491 tty->print("early(n->in(%d)->in(%d)): ", i, j); in2_early->dump();
6492 if (in2->in(0) != nullptr && !in2->in(0)->is_top() &&
6493 in2->in(0) != in2_early && !in2->in(0)->is_Root()) {
6494 tty->print("n->in(%d)->in(%d)->in(0): ", i, j); in2->in(0)->dump();
6495 }
6496 }
6497 }
6498 }
6499 }
6500 tty->cr();
6501 tty->print("LCA(n): "); LCA->dump();
6502 for (uint i = 0; i < n->outcnt(); i++) {
6503 Node* u1 = n->raw_out(i);
6504 if (u1 == n)
6505 continue;
6506 tty->print("n->out(%d): ", i); u1->dump();
6507 if (u1->is_CFG()) {
6508 for (uint j = 0; j < u1->outcnt(); j++) {
6509 Node* u2 = u1->raw_out(j);
6510 if (u2 != u1 && u2 != n && u2->is_CFG()) {
6511 tty->print("n->out(%d)->out(%d): ", i, j); u2->dump();
6512 }
6513 }
6514 } else {
6515 Node* u1_later = get_ctrl(u1);
6516 tty->print("later(n->out(%d)): ", i); u1_later->dump();
6517 if (u1->in(0) != nullptr && !u1->in(0)->is_top() &&
6518 u1->in(0) != u1_later && !u1->in(0)->is_Root()) {
6519 tty->print("n->out(%d)->in(0): ", i); u1->in(0)->dump();
6520 }
6521 for (uint j = 0; j < u1->outcnt(); j++) {
6522 Node* u2 = u1->raw_out(j);
6523 if (u2 == n || u2 == u1)
6524 continue;
6525 tty->print("n->out(%d)->out(%d): ", i, j); u2->dump();
6526 if (!u2->is_CFG()) {
6527 Node* u2_later = get_ctrl(u2);
6528 tty->print("later(n->out(%d)->out(%d)): ", i, j); u2_later->dump();
6529 if (u2->in(0) != nullptr && !u2->in(0)->is_top() &&
6530 u2->in(0) != u2_later && !u2->in(0)->is_Root()) {
6531 tty->print("n->out(%d)->in(0): ", i); u2->in(0)->dump();
6532 }
6533 }
6534 }
6535 }
6536 }
6537 dump_idoms(early, LCA);
6538 tty->cr();
6539 }
6540
6541 // Class to compute the real LCA given an early node and a wrong LCA in a bad graph.
6542 class RealLCA {
6543 const PhaseIdealLoop* _phase;
6544 Node* _early;
6545 Node* _wrong_lca;
6546 uint _early_index;
6547 int _wrong_lca_index;
6548
6549 // Given idom chains of early and wrong LCA: Walk through idoms starting at StartNode and find the first node which
6550 // is different: Return the previously visited node which must be the real LCA.
6551 // The node lists also contain _early and _wrong_lca, respectively.
6552 Node* find_real_lca(Unique_Node_List& early_with_idoms, Unique_Node_List& wrong_lca_with_idoms) {
6553 int early_index = early_with_idoms.size() - 1;
6554 int wrong_lca_index = wrong_lca_with_idoms.size() - 1;
6555 bool found_difference = false;
6556 do {
6557 if (early_with_idoms[early_index] != wrong_lca_with_idoms[wrong_lca_index]) {
6558 // First time early and wrong LCA idoms differ. Real LCA must be at the previous index.
6559 found_difference = true;
6560 break;
6561 }
6562 early_index--;
6563 wrong_lca_index--;
6564 } while (wrong_lca_index >= 0);
6565
6566 assert(early_index >= 0, "must always find an LCA - cannot be early");
6567 _early_index = early_index;
6568 _wrong_lca_index = wrong_lca_index;
6569 Node* real_lca = early_with_idoms[_early_index + 1]; // Plus one to skip _early.
6570 assert(found_difference || real_lca == _wrong_lca, "wrong LCA dominates early and is therefore the real LCA");
6571 return real_lca;
6572 }
6573
6574 void dump(Node* real_lca) {
6575 tty->cr();
6576 tty->print_cr("idoms of early \"%d %s\":", _early->_idx, _early->Name());
6577 _phase->dump_idom(_early, _early_index + 1);
6578
6579 tty->cr();
6580 tty->print_cr("idoms of (wrong) LCA \"%d %s\":", _wrong_lca->_idx, _wrong_lca->Name());
6581 _phase->dump_idom(_wrong_lca, _wrong_lca_index + 1);
6582
6583 tty->cr();
6584 tty->print("Real LCA of early \"%d %s\" (idom[%d]) and wrong LCA \"%d %s\"",
6585 _early->_idx, _early->Name(), _early_index, _wrong_lca->_idx, _wrong_lca->Name());
6586 if (_wrong_lca_index >= 0) {
6587 tty->print(" (idom[%d])", _wrong_lca_index);
6588 }
6589 tty->print_cr(":");
6590 real_lca->dump();
6591 }
6592
6593 public:
6594 RealLCA(const PhaseIdealLoop* phase, Node* early, Node* wrong_lca)
6595 : _phase(phase), _early(early), _wrong_lca(wrong_lca), _early_index(0), _wrong_lca_index(0) {
6596 assert(!wrong_lca->is_Start(), "StartNode is always a common dominator");
6597 }
6598
6599 void compute_and_dump() {
6600 ResourceMark rm;
6601 Unique_Node_List early_with_idoms;
6602 Unique_Node_List wrong_lca_with_idoms;
6603 early_with_idoms.push(_early);
6604 wrong_lca_with_idoms.push(_wrong_lca);
6605 _phase->get_idoms(_early, 10000, early_with_idoms);
6606 _phase->get_idoms(_wrong_lca, 10000, wrong_lca_with_idoms);
6607 Node* real_lca = find_real_lca(early_with_idoms, wrong_lca_with_idoms);
6608 dump(real_lca);
6609 }
6610 };
6611
6612 // Dump the idom chain of early, of the wrong LCA and dump the real LCA of early and wrong LCA.
6613 void PhaseIdealLoop::dump_idoms(Node* early, Node* wrong_lca) {
6614 assert(!is_dominator(early, wrong_lca), "sanity check that early does not dominate wrong lca");
6615 assert(!has_ctrl(early) && !has_ctrl(wrong_lca), "sanity check, no data nodes");
6616
6617 RealLCA real_lca(this, early, wrong_lca);
6618 real_lca.compute_and_dump();
6619 }
6620 #endif // ASSERT
6621
6622 #ifndef PRODUCT
6623 //------------------------------dump-------------------------------------------
6624 void PhaseIdealLoop::dump() const {
6625 ResourceMark rm;
6626 Node_Stack stack(C->live_nodes() >> 2);
6627 Node_List rpo_list;
6628 VectorSet visited;
6629 visited.set(C->top()->_idx);
6630 rpo(C->root(), stack, visited, rpo_list);
6631 // Dump root loop indexed by last element in PO order
6632 dump(_ltree_root, rpo_list.size(), rpo_list);
6633 }
6634
6635 void PhaseIdealLoop::dump(IdealLoopTree* loop, uint idx, Node_List &rpo_list) const {
6636 loop->dump_head();
6637
6638 // Now scan for CFG nodes in the same loop
6639 for (uint j = idx; j > 0; j--) {
6640 Node* n = rpo_list[j-1];
6641 if (!_loop_or_ctrl[n->_idx]) // Skip dead nodes
6642 continue;
6643
6644 if (get_loop(n) != loop) { // Wrong loop nest
6645 if (get_loop(n)->_head == n && // Found nested loop?
6646 get_loop(n)->_parent == loop)
6647 dump(get_loop(n), rpo_list.size(), rpo_list); // Print it nested-ly
6648 continue;
6649 }
6650
6651 // Dump controlling node
6652 tty->sp(2 * loop->_nest);
6653 tty->print("C");
6654 if (n == C->root()) {
6655 n->dump();
6656 } else {
6657 Node* cached_idom = idom_no_update(n);
6658 Node* computed_idom = n->in(0);
6659 if (n->is_Region()) {
6660 computed_idom = compute_idom(n);
6661 // computed_idom() will return n->in(0) when idom(n) is an IfNode (or
6662 // any MultiBranch ctrl node), so apply a similar transform to
6663 // the cached idom returned from idom_no_update.
6664 cached_idom = find_non_split_ctrl(cached_idom);
6665 }
6666 tty->print(" ID:%d", computed_idom->_idx);
6667 n->dump();
6668 if (cached_idom != computed_idom) {
6669 tty->print_cr("*** BROKEN IDOM! Computed as: %d, cached as: %d",
6670 computed_idom->_idx, cached_idom->_idx);
6671 }
6672 }
6673 // Dump nodes it controls
6674 for (uint k = 0; k < _loop_or_ctrl.max(); k++) {
6675 // (k < C->unique() && get_ctrl(find(k)) == n)
6676 if (k < C->unique() && _loop_or_ctrl[k] == (Node*)((intptr_t)n + 1)) {
6677 Node* m = C->root()->find(k);
6678 if (m && m->outcnt() > 0) {
6679 if (!(has_ctrl(m) && get_ctrl_no_update(m) == n)) {
6680 tty->print_cr("*** BROKEN CTRL ACCESSOR! _loop_or_ctrl[k] is %p, ctrl is %p",
6681 _loop_or_ctrl[k], has_ctrl(m) ? get_ctrl_no_update(m) : nullptr);
6682 }
6683 tty->sp(2 * loop->_nest + 1);
6684 m->dump();
6685 }
6686 }
6687 }
6688 }
6689 }
6690
6691 void PhaseIdealLoop::dump_idom(Node* n, const uint count) const {
6692 if (has_ctrl(n)) {
6693 tty->print_cr("No idom for data nodes");
6694 } else {
6695 ResourceMark rm;
6696 Unique_Node_List idoms;
6697 get_idoms(n, count, idoms);
6698 dump_idoms_in_reverse(n, idoms);
6699 }
6700 }
6701
6702 void PhaseIdealLoop::get_idoms(Node* n, const uint count, Unique_Node_List& idoms) const {
6703 Node* next = n;
6704 for (uint i = 0; !next->is_Start() && i < count; i++) {
6705 next = idom(next);
6706 assert(!idoms.member(next), "duplicated idom is not possible");
6707 idoms.push(next);
6708 }
6709 }
6710
6711 void PhaseIdealLoop::dump_idoms_in_reverse(const Node* n, const Node_List& idom_list) const {
6712 Node* next;
6713 uint padding = 3;
6714 uint node_index_padding_width = static_cast<int>(log10(static_cast<double>(C->unique()))) + 1;
6715 for (int i = idom_list.size() - 1; i >= 0; i--) {
6716 if (i == 9 || i == 99) {
6717 padding++;
6718 }
6719 next = idom_list[i];
6720 tty->print_cr("idom[%d]:%*c%*d %s", i, padding, ' ', node_index_padding_width, next->_idx, next->Name());
6721 }
6722 tty->print_cr("n: %*c%*d %s", padding, ' ', node_index_padding_width, n->_idx, n->Name());
6723 }
6724 #endif // NOT PRODUCT
6725
6726 // Collect a R-P-O for the whole CFG.
6727 // Result list is in post-order (scan backwards for RPO)
6728 void PhaseIdealLoop::rpo(Node* start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list) const {
6729 stk.push(start, 0);
6730 visited.set(start->_idx);
6731
6732 while (stk.is_nonempty()) {
6733 Node* m = stk.node();
6734 uint idx = stk.index();
6735 if (idx < m->outcnt()) {
6736 stk.set_index(idx + 1);
6737 Node* n = m->raw_out(idx);
6738 if (n->is_CFG() && !visited.test_set(n->_idx)) {
6739 stk.push(n, 0);
6740 }
6741 } else {
6742 rpo_list.push(m);
6743 stk.pop();
6744 }
6745 }
6746 }
6747
6748
6749 //=============================================================================
6750 //------------------------------LoopTreeIterator-------------------------------
6751
6752 // Advance to next loop tree using a preorder, left-to-right traversal.
6753 void LoopTreeIterator::next() {
6754 assert(!done(), "must not be done.");
6755 if (_curnt->_child != nullptr) {
6756 _curnt = _curnt->_child;
6757 } else if (_curnt->_next != nullptr) {
6758 _curnt = _curnt->_next;
6759 } else {
6760 while (_curnt != _root && _curnt->_next == nullptr) {
6761 _curnt = _curnt->_parent;
6762 }
6763 if (_curnt == _root) {
6764 _curnt = nullptr;
6765 assert(done(), "must be done.");
6766 } else {
6767 assert(_curnt->_next != nullptr, "must be more to do");
6768 _curnt = _curnt->_next;
6769 }
6770 }
6771 }