1 /*
2 * Copyright (c) 2000, 2023, 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.
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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.
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23 */
24
25 #include "precompiled.hpp"
26 #include "ci/ciTypeFlow.hpp"
27 #include "memory/allocation.inline.hpp"
28 #include "memory/resourceArea.hpp"
29 #include "opto/addnode.hpp"
30 #include "opto/castnode.hpp"
31 #include "opto/cfgnode.hpp"
32 #include "opto/connode.hpp"
33 #include "opto/loopnode.hpp"
34 #include "opto/phaseX.hpp"
35 #include "opto/predicates.hpp"
36 #include "opto/runtime.hpp"
37 #include "opto/rootnode.hpp"
38 #include "opto/subnode.hpp"
39 #include "opto/subtypenode.hpp"
40
41 // Portions of code courtesy of Clifford Click
42
43 // Optimization - Graph Style
44
45
46 #ifndef PRODUCT
47 extern uint explicit_null_checks_elided;
48 #endif
49
50 //=============================================================================
51 //------------------------------Value------------------------------------------
52 // Return a tuple for whichever arm of the IF is reachable
53 const Type* IfNode::Value(PhaseGVN* phase) const {
54 if( !in(0) ) return Type::TOP;
55 if( phase->type(in(0)) == Type::TOP )
56 return Type::TOP;
57 const Type *t = phase->type(in(1));
58 if( t == Type::TOP ) // data is undefined
59 return TypeTuple::IFNEITHER; // unreachable altogether
60 if( t == TypeInt::ZERO ) // zero, or false
61 return TypeTuple::IFFALSE; // only false branch is reachable
62 if( t == TypeInt::ONE ) // 1, or true
63 return TypeTuple::IFTRUE; // only true branch is reachable
64 assert( t == TypeInt::BOOL, "expected boolean type" );
65
66 return TypeTuple::IFBOTH; // No progress
67 }
68
69 const RegMask &IfNode::out_RegMask() const {
70 return RegMask::Empty;
71 }
72
73 //------------------------------split_if---------------------------------------
74 // Look for places where we merge constants, then test on the merged value.
75 // If the IF test will be constant folded on the path with the constant, we
76 // win by splitting the IF to before the merge point.
77 static Node* split_if(IfNode *iff, PhaseIterGVN *igvn) {
78 // I could be a lot more general here, but I'm trying to squeeze this
79 // in before the Christmas '98 break so I'm gonna be kinda restrictive
80 // on the patterns I accept. CNC
81
82 // Look for a compare of a constant and a merged value
83 Node *i1 = iff->in(1);
84 if( !i1->is_Bool() ) return nullptr;
85 BoolNode *b = i1->as_Bool();
86 Node *cmp = b->in(1);
87 if( !cmp->is_Cmp() ) return nullptr;
88 i1 = cmp->in(1);
89 if( i1 == nullptr || !i1->is_Phi() ) return nullptr;
90 PhiNode *phi = i1->as_Phi();
91 Node *con2 = cmp->in(2);
92 if( !con2->is_Con() ) return nullptr;
93 // See that the merge point contains some constants
94 Node *con1=nullptr;
95 uint i4;
96 RegionNode* phi_region = phi->region();
97 for (i4 = 1; i4 < phi->req(); i4++ ) {
98 con1 = phi->in(i4);
99 // Do not optimize partially collapsed merges
100 if (con1 == nullptr || phi_region->in(i4) == nullptr || igvn->type(phi_region->in(i4)) == Type::TOP) {
101 igvn->_worklist.push(iff);
102 return nullptr;
103 }
104 if( con1->is_Con() ) break; // Found a constant
105 // Also allow null-vs-not-null checks
106 const TypePtr *tp = igvn->type(con1)->isa_ptr();
107 if( tp && tp->_ptr == TypePtr::NotNull )
108 break;
109 }
110 if( i4 >= phi->req() ) return nullptr; // Found no constants
111
112 igvn->C->set_has_split_ifs(true); // Has chance for split-if
113
114 // Make sure that the compare can be constant folded away
115 Node *cmp2 = cmp->clone();
116 cmp2->set_req(1,con1);
117 cmp2->set_req(2,con2);
118 const Type *t = cmp2->Value(igvn);
119 // This compare is dead, so whack it!
120 igvn->remove_dead_node(cmp2);
121 if( !t->singleton() ) return nullptr;
122
123 // No intervening control, like a simple Call
124 Node* r = iff->in(0);
125 if (!r->is_Region() || r->is_Loop() || phi_region != r || r->as_Region()->is_copy()) {
126 return nullptr;
127 }
128
129 // No other users of the cmp/bool
130 if (b->outcnt() != 1 || cmp->outcnt() != 1) {
131 //tty->print_cr("many users of cmp/bool");
132 return nullptr;
133 }
134
135 // Make sure we can determine where all the uses of merged values go
136 for (DUIterator_Fast jmax, j = r->fast_outs(jmax); j < jmax; j++) {
137 Node* u = r->fast_out(j);
138 if( u == r ) continue;
139 if( u == iff ) continue;
140 if( u->outcnt() == 0 ) continue; // use is dead & ignorable
141 if( !u->is_Phi() ) {
142 /*
143 if( u->is_Start() ) {
144 tty->print_cr("Region has inlined start use");
145 } else {
146 tty->print_cr("Region has odd use");
147 u->dump(2);
148 }*/
149 return nullptr;
150 }
151 if( u != phi ) {
152 // CNC - do not allow any other merged value
153 //tty->print_cr("Merging another value");
154 //u->dump(2);
155 return nullptr;
156 }
157 // Make sure we can account for all Phi uses
158 for (DUIterator_Fast kmax, k = u->fast_outs(kmax); k < kmax; k++) {
159 Node* v = u->fast_out(k); // User of the phi
160 // CNC - Allow only really simple patterns.
161 // In particular I disallow AddP of the Phi, a fairly common pattern
162 if (v == cmp) continue; // The compare is OK
163 if (v->is_ConstraintCast()) {
164 // If the cast is derived from data flow edges, it may not have a control edge.
165 // If so, it should be safe to split. But follow-up code can not deal with
166 // this (l. 359). So skip.
167 if (v->in(0) == nullptr) {
168 return nullptr;
169 }
170 if (v->in(0)->in(0) == iff) {
171 continue; // CastPP/II of the IfNode is OK
172 }
173 }
174 // Disabled following code because I cannot tell if exactly one
175 // path dominates without a real dominator check. CNC 9/9/1999
176 //uint vop = v->Opcode();
177 //if( vop == Op_Phi ) { // Phi from another merge point might be OK
178 // Node *r = v->in(0); // Get controlling point
179 // if( !r ) return nullptr; // Degraded to a copy
180 // // Find exactly one path in (either True or False doms, but not IFF)
181 // int cnt = 0;
182 // for( uint i = 1; i < r->req(); i++ )
183 // if( r->in(i) && r->in(i)->in(0) == iff )
184 // cnt++;
185 // if( cnt == 1 ) continue; // Exactly one of True or False guards Phi
186 //}
187 if( !v->is_Call() ) {
188 /*
189 if( v->Opcode() == Op_AddP ) {
190 tty->print_cr("Phi has AddP use");
191 } else if( v->Opcode() == Op_CastPP ) {
192 tty->print_cr("Phi has CastPP use");
193 } else if( v->Opcode() == Op_CastII ) {
194 tty->print_cr("Phi has CastII use");
195 } else {
196 tty->print_cr("Phi has use I can't be bothered with");
197 }
198 */
199 }
200 return nullptr;
201
202 /* CNC - Cut out all the fancy acceptance tests
203 // Can we clone this use when doing the transformation?
204 // If all uses are from Phis at this merge or constants, then YES.
205 if( !v->in(0) && v != cmp ) {
206 tty->print_cr("Phi has free-floating use");
207 v->dump(2);
208 return nullptr;
209 }
210 for( uint l = 1; l < v->req(); l++ ) {
211 if( (!v->in(l)->is_Phi() || v->in(l)->in(0) != r) &&
212 !v->in(l)->is_Con() ) {
213 tty->print_cr("Phi has use");
214 v->dump(2);
215 return nullptr;
216 } // End of if Phi-use input is neither Phi nor Constant
217 } // End of for all inputs to Phi-use
218 */
219 } // End of for all uses of Phi
220 } // End of for all uses of Region
221
222 // Only do this if the IF node is in a sane state
223 if (iff->outcnt() != 2)
224 return nullptr;
225
226 // Got a hit! Do the Mondo Hack!
227 //
228 //ABC a1c def ghi B 1 e h A C a c d f g i
229 // R - Phi - Phi - Phi Rc - Phi - Phi - Phi Rx - Phi - Phi - Phi
230 // cmp - 2 cmp - 2 cmp - 2
231 // bool bool_c bool_x
232 // if if_c if_x
233 // T F T F T F
234 // ..s.. ..t .. ..s.. ..t.. ..s.. ..t..
235 //
236 // Split the paths coming into the merge point into 2 separate groups of
237 // merges. On the left will be all the paths feeding constants into the
238 // Cmp's Phi. On the right will be the remaining paths. The Cmp's Phi
239 // will fold up into a constant; this will let the Cmp fold up as well as
240 // all the control flow. Below the original IF we have 2 control
241 // dependent regions, 's' and 't'. Now we will merge the two paths
242 // just prior to 's' and 't' from the two IFs. At least 1 path (and quite
243 // likely 2 or more) will promptly constant fold away.
244 PhaseGVN *phase = igvn;
245
246 // Make a region merging constants and a region merging the rest
247 uint req_c = 0;
248 for (uint ii = 1; ii < r->req(); ii++) {
249 if (phi->in(ii) == con1) {
250 req_c++;
251 }
252 if (Node::may_be_loop_entry(r->in(ii))) {
253 // Bail out if splitting through a region with a Parse Predicate input (could
254 // also be a loop header before loop opts creates a LoopNode for it).
255 return nullptr;
256 }
257 }
258
259 // If all the defs of the phi are the same constant, we already have the desired end state.
260 // Skip the split that would create empty phi and region nodes.
261 if ((r->req() - req_c) == 1) {
262 return nullptr;
263 }
264
265 // At this point we know that we can apply the split if optimization. If the region is still on the worklist,
266 // we should wait until it is processed. The region might be removed which makes this optimization redundant.
267 // This also avoids the creation of dead data loops when rewiring data nodes below when a region is dying.
268 if (igvn->_worklist.member(r)) {
269 igvn->_worklist.push(iff); // retry split if later again
270 return nullptr;
271 }
272
273 Node *region_c = new RegionNode(req_c + 1);
274 Node *phi_c = con1;
275 uint len = r->req();
276 Node *region_x = new RegionNode(len - req_c);
277 Node *phi_x = PhiNode::make_blank(region_x, phi);
278 for (uint i = 1, i_c = 1, i_x = 1; i < len; i++) {
279 if (phi->in(i) == con1) {
280 region_c->init_req( i_c++, r ->in(i) );
281 } else {
282 region_x->init_req( i_x, r ->in(i) );
283 phi_x ->init_req( i_x++, phi->in(i) );
284 }
285 }
286
287 // Register the new RegionNodes but do not transform them. Cannot
288 // transform until the entire Region/Phi conglomerate has been hacked
289 // as a single huge transform.
290 igvn->register_new_node_with_optimizer( region_c );
291 igvn->register_new_node_with_optimizer( region_x );
292 // Prevent the untimely death of phi_x. Currently he has no uses. He is
293 // about to get one. If this only use goes away, then phi_x will look dead.
294 // However, he will be picking up some more uses down below.
295 Node *hook = new Node(4);
296 hook->init_req(0, phi_x);
297 hook->init_req(1, phi_c);
298 phi_x = phase->transform( phi_x );
299
300 // Make the compare
301 Node *cmp_c = phase->makecon(t);
302 Node *cmp_x = cmp->clone();
303 cmp_x->set_req(1,phi_x);
304 cmp_x->set_req(2,con2);
305 cmp_x = phase->transform(cmp_x);
306 // Make the bool
307 Node *b_c = phase->transform(new BoolNode(cmp_c,b->_test._test));
308 Node *b_x = phase->transform(new BoolNode(cmp_x,b->_test._test));
309 // Make the IfNode
310 IfNode* iff_c = iff->clone()->as_If();
311 iff_c->set_req(0, region_c);
312 iff_c->set_req(1, b_c);
313 igvn->set_type_bottom(iff_c);
314 igvn->_worklist.push(iff_c);
315 hook->init_req(2, iff_c);
316
317 IfNode* iff_x = iff->clone()->as_If();
318 iff_x->set_req(0, region_x);
319 iff_x->set_req(1, b_x);
320 igvn->set_type_bottom(iff_x);
321 igvn->_worklist.push(iff_x);
322 hook->init_req(3, iff_x);
323
324 // Make the true/false arms
325 Node *iff_c_t = phase->transform(new IfTrueNode (iff_c));
326 Node *iff_c_f = phase->transform(new IfFalseNode(iff_c));
327 Node *iff_x_t = phase->transform(new IfTrueNode (iff_x));
328 Node *iff_x_f = phase->transform(new IfFalseNode(iff_x));
329
330 // Merge the TRUE paths
331 Node *region_s = new RegionNode(3);
332 igvn->_worklist.push(region_s);
333 region_s->init_req(1, iff_c_t);
334 region_s->init_req(2, iff_x_t);
335 igvn->register_new_node_with_optimizer( region_s );
336
337 // Merge the FALSE paths
338 Node *region_f = new RegionNode(3);
339 igvn->_worklist.push(region_f);
340 region_f->init_req(1, iff_c_f);
341 region_f->init_req(2, iff_x_f);
342 igvn->register_new_node_with_optimizer( region_f );
343
344 igvn->hash_delete(cmp);// Remove soon-to-be-dead node from hash table.
345 cmp->set_req(1,nullptr); // Whack the inputs to cmp because it will be dead
346 cmp->set_req(2,nullptr);
347 // Check for all uses of the Phi and give them a new home.
348 // The 'cmp' got cloned, but CastPP/IIs need to be moved.
349 Node *phi_s = nullptr; // do not construct unless needed
350 Node *phi_f = nullptr; // do not construct unless needed
351 for (DUIterator_Last i2min, i2 = phi->last_outs(i2min); i2 >= i2min; --i2) {
352 Node* v = phi->last_out(i2);// User of the phi
353 igvn->rehash_node_delayed(v); // Have to fixup other Phi users
354 uint vop = v->Opcode();
355 Node *proj = nullptr;
356 if( vop == Op_Phi ) { // Remote merge point
357 Node *r = v->in(0);
358 for (uint i3 = 1; i3 < r->req(); i3++)
359 if (r->in(i3) && r->in(i3)->in(0) == iff) {
360 proj = r->in(i3);
361 break;
362 }
363 } else if( v->is_ConstraintCast() ) {
364 proj = v->in(0); // Controlling projection
365 } else {
366 assert( 0, "do not know how to handle this guy" );
367 }
368 guarantee(proj != nullptr, "sanity");
369
370 Node *proj_path_data, *proj_path_ctrl;
371 if( proj->Opcode() == Op_IfTrue ) {
372 if( phi_s == nullptr ) {
373 // Only construct phi_s if needed, otherwise provides
374 // interfering use.
375 phi_s = PhiNode::make_blank(region_s,phi);
376 phi_s->init_req( 1, phi_c );
377 phi_s->init_req( 2, phi_x );
378 hook->add_req(phi_s);
379 phi_s = phase->transform(phi_s);
380 }
381 proj_path_data = phi_s;
382 proj_path_ctrl = region_s;
383 } else {
384 if( phi_f == nullptr ) {
385 // Only construct phi_f if needed, otherwise provides
386 // interfering use.
387 phi_f = PhiNode::make_blank(region_f,phi);
388 phi_f->init_req( 1, phi_c );
389 phi_f->init_req( 2, phi_x );
390 hook->add_req(phi_f);
391 phi_f = phase->transform(phi_f);
392 }
393 proj_path_data = phi_f;
394 proj_path_ctrl = region_f;
395 }
396
397 // Fixup 'v' for for the split
398 if( vop == Op_Phi ) { // Remote merge point
399 uint i;
400 for( i = 1; i < v->req(); i++ )
401 if( v->in(i) == phi )
402 break;
403 v->set_req(i, proj_path_data );
404 } else if( v->is_ConstraintCast() ) {
405 v->set_req(0, proj_path_ctrl );
406 v->set_req(1, proj_path_data );
407 } else
408 ShouldNotReachHere();
409 }
410
411 // Now replace the original iff's True/False with region_s/region_t.
412 // This makes the original iff go dead.
413 for (DUIterator_Last i3min, i3 = iff->last_outs(i3min); i3 >= i3min; --i3) {
414 Node* p = iff->last_out(i3);
415 assert( p->Opcode() == Op_IfTrue || p->Opcode() == Op_IfFalse, "" );
416 Node *u = (p->Opcode() == Op_IfTrue) ? region_s : region_f;
417 // Replace p with u
418 igvn->add_users_to_worklist(p);
419 for (DUIterator_Last lmin, l = p->last_outs(lmin); l >= lmin;) {
420 Node* x = p->last_out(l);
421 igvn->hash_delete(x);
422 uint uses_found = 0;
423 for( uint j = 0; j < x->req(); j++ ) {
424 if( x->in(j) == p ) {
425 x->set_req(j, u);
426 uses_found++;
427 }
428 }
429 l -= uses_found; // we deleted 1 or more copies of this edge
430 }
431 igvn->remove_dead_node(p);
432 }
433
434 // Force the original merge dead
435 igvn->hash_delete(r);
436 // First, remove region's dead users.
437 for (DUIterator_Last lmin, l = r->last_outs(lmin); l >= lmin;) {
438 Node* u = r->last_out(l);
439 if( u == r ) {
440 r->set_req(0, nullptr);
441 } else {
442 assert(u->outcnt() == 0, "only dead users");
443 igvn->remove_dead_node(u);
444 }
445 l -= 1;
446 }
447 igvn->remove_dead_node(r);
448
449 // Now remove the bogus extra edges used to keep things alive
450 igvn->remove_dead_node( hook );
451
452 // Must return either the original node (now dead) or a new node
453 // (Do not return a top here, since that would break the uniqueness of top.)
454 return new ConINode(TypeInt::ZERO);
455 }
456
457 IfNode* IfNode::make_with_same_profile(IfNode* if_node_profile, Node* ctrl, BoolNode* bol) {
458 // Assert here that we only try to create a clone from an If node with the same profiling if that actually makes sense.
459 // Some If node subtypes should not be cloned in this way. In theory, we should not clone BaseCountedLoopEndNodes.
460 // But they can end up being used as normal If nodes when peeling a loop - they serve as zero-trip guard.
461 // Allow them as well.
462 assert(if_node_profile->Opcode() == Op_If || if_node_profile->is_RangeCheck()
463 || if_node_profile->is_BaseCountedLoopEnd(), "should not clone other nodes");
464 if (if_node_profile->is_RangeCheck()) {
465 // RangeCheck nodes could be further optimized.
466 return new RangeCheckNode(ctrl, bol, if_node_profile->_prob, if_node_profile->_fcnt);
467 } else {
468 // Not a RangeCheckNode? Fall back to IfNode.
469 return new IfNode(ctrl, bol, if_node_profile->_prob, if_node_profile->_fcnt);
470 }
471 }
472
473 // if this IfNode follows a range check pattern return the projection
474 // for the failed path
475 ProjNode* IfNode::range_check_trap_proj(int& flip_test, Node*& l, Node*& r) {
476 if (outcnt() != 2) {
477 return nullptr;
478 }
479 Node* b = in(1);
480 if (b == nullptr || !b->is_Bool()) return nullptr;
481 BoolNode* bn = b->as_Bool();
482 Node* cmp = bn->in(1);
483 if (cmp == nullptr) return nullptr;
484 if (cmp->Opcode() != Op_CmpU) return nullptr;
485
486 l = cmp->in(1);
487 r = cmp->in(2);
488 flip_test = 1;
489 if (bn->_test._test == BoolTest::le) {
490 l = cmp->in(2);
491 r = cmp->in(1);
492 flip_test = 2;
493 } else if (bn->_test._test != BoolTest::lt) {
494 return nullptr;
495 }
496 if (l->is_top()) return nullptr; // Top input means dead test
497 if (r->Opcode() != Op_LoadRange && !is_RangeCheck()) return nullptr;
498
499 // We have recognized one of these forms:
500 // Flip 1: If (Bool[<] CmpU(l, LoadRange)) ...
501 // Flip 2: If (Bool[<=] CmpU(LoadRange, l)) ...
502
503 ProjNode* iftrap = proj_out_or_null(flip_test == 2 ? true : false);
504 return iftrap;
505 }
506
507
508 //------------------------------is_range_check---------------------------------
509 // Return 0 if not a range check. Return 1 if a range check and set index and
510 // offset. Return 2 if we had to negate the test. Index is null if the check
511 // is versus a constant.
512 int RangeCheckNode::is_range_check(Node* &range, Node* &index, jint &offset) {
513 int flip_test = 0;
514 Node* l = nullptr;
515 Node* r = nullptr;
516 ProjNode* iftrap = range_check_trap_proj(flip_test, l, r);
517
518 if (iftrap == nullptr) {
519 return 0;
520 }
521
522 // Make sure it's a real range check by requiring an uncommon trap
523 // along the OOB path. Otherwise, it's possible that the user wrote
524 // something which optimized to look like a range check but behaves
525 // in some other way.
526 if (iftrap->is_uncommon_trap_proj(Deoptimization::Reason_range_check) == nullptr) {
527 return 0;
528 }
529
530 // Look for index+offset form
531 Node* ind = l;
532 jint off = 0;
533 if (l->is_top()) {
534 return 0;
535 } else if (l->Opcode() == Op_AddI) {
536 if ((off = l->in(1)->find_int_con(0)) != 0) {
537 ind = l->in(2)->uncast();
538 } else if ((off = l->in(2)->find_int_con(0)) != 0) {
539 ind = l->in(1)->uncast();
540 }
541 } else if ((off = l->find_int_con(-1)) >= 0) {
542 // constant offset with no variable index
543 ind = nullptr;
544 } else {
545 // variable index with no constant offset (or dead negative index)
546 off = 0;
547 }
548
549 // Return all the values:
550 index = ind;
551 offset = off;
552 range = r;
553 return flip_test;
554 }
555
556 //------------------------------adjust_check-----------------------------------
557 // Adjust (widen) a prior range check
558 static void adjust_check(IfProjNode* proj, Node* range, Node* index,
559 int flip, jint off_lo, PhaseIterGVN* igvn) {
560 PhaseGVN *gvn = igvn;
561 // Break apart the old check
562 Node *iff = proj->in(0);
563 Node *bol = iff->in(1);
564 if( bol->is_top() ) return; // In case a partially dead range check appears
565 // bail (or bomb[ASSERT/DEBUG]) if NOT projection-->IfNode-->BoolNode
566 DEBUG_ONLY( if (!bol->is_Bool()) { proj->dump(3); fatal("Expect projection-->IfNode-->BoolNode"); } )
567 if (!bol->is_Bool()) return;
568
569 Node *cmp = bol->in(1);
570 // Compute a new check
571 Node *new_add = gvn->intcon(off_lo);
572 if (index) {
573 new_add = off_lo ? gvn->transform(new AddINode(index, new_add)) : index;
574 }
575 Node *new_cmp = (flip == 1)
576 ? new CmpUNode(new_add, range)
577 : new CmpUNode(range, new_add);
578 new_cmp = gvn->transform(new_cmp);
579 // See if no need to adjust the existing check
580 if (new_cmp == cmp) return;
581 // Else, adjust existing check
582 Node* new_bol = gvn->transform(new BoolNode(new_cmp, bol->as_Bool()->_test._test));
583 igvn->rehash_node_delayed(iff);
584 iff->set_req_X(1, new_bol, igvn);
585 // As part of range check smearing, this range check is widened. Loads and range check Cast nodes that are control
586 // dependent on this range check now depend on multiple dominating range checks. These control dependent nodes end up
587 // at the lowest/nearest dominating check in the graph. To ensure that these Loads/Casts do not float above any of the
588 // dominating checks (even when the lowest dominating check is later replaced by yet another dominating check), we
589 // need to pin them at the lowest dominating check.
590 proj->pin_array_access_nodes(igvn);
591 }
592
593 //------------------------------up_one_dom-------------------------------------
594 // Walk up the dominator tree one step. Return null at root or true
595 // complex merges. Skips through small diamonds.
596 Node* IfNode::up_one_dom(Node *curr, bool linear_only) {
597 Node *dom = curr->in(0);
598 if( !dom ) // Found a Region degraded to a copy?
599 return curr->nonnull_req(); // Skip thru it
600
601 if( curr != dom ) // Normal walk up one step?
602 return dom;
603
604 // Use linear_only if we are still parsing, since we cannot
605 // trust the regions to be fully filled in.
606 if (linear_only)
607 return nullptr;
608
609 if( dom->is_Root() )
610 return nullptr;
611
612 // Else hit a Region. Check for a loop header
613 if( dom->is_Loop() )
614 return dom->in(1); // Skip up thru loops
615
616 // Check for small diamonds
617 Node *din1, *din2, *din3, *din4;
618 if( dom->req() == 3 && // 2-path merge point
619 (din1 = dom ->in(1)) && // Left path exists
620 (din2 = dom ->in(2)) && // Right path exists
621 (din3 = din1->in(0)) && // Left path up one
622 (din4 = din2->in(0)) ) { // Right path up one
623 if( din3->is_Call() && // Handle a slow-path call on either arm
624 (din3 = din3->in(0)) )
625 din3 = din3->in(0);
626 if( din4->is_Call() && // Handle a slow-path call on either arm
627 (din4 = din4->in(0)) )
628 din4 = din4->in(0);
629 if (din3 != nullptr && din3 == din4 && din3->is_If()) // Regions not degraded to a copy
630 return din3; // Skip around diamonds
631 }
632
633 // Give up the search at true merges
634 return nullptr; // Dead loop? Or hit root?
635 }
636
637
638 //------------------------------filtered_int_type--------------------------------
639 // Return a possibly more restrictive type for val based on condition control flow for an if
640 const TypeInt* IfNode::filtered_int_type(PhaseGVN* gvn, Node* val, Node* if_proj) {
641 assert(if_proj &&
642 (if_proj->Opcode() == Op_IfTrue || if_proj->Opcode() == Op_IfFalse), "expecting an if projection");
643 if (if_proj->in(0) && if_proj->in(0)->is_If()) {
644 IfNode* iff = if_proj->in(0)->as_If();
645 if (iff->in(1) && iff->in(1)->is_Bool()) {
646 BoolNode* bol = iff->in(1)->as_Bool();
647 if (bol->in(1) && bol->in(1)->is_Cmp()) {
648 const CmpNode* cmp = bol->in(1)->as_Cmp();
649 if (cmp->in(1) == val) {
650 const TypeInt* cmp2_t = gvn->type(cmp->in(2))->isa_int();
651 if (cmp2_t != nullptr) {
652 jint lo = cmp2_t->_lo;
653 jint hi = cmp2_t->_hi;
654 BoolTest::mask msk = if_proj->Opcode() == Op_IfTrue ? bol->_test._test : bol->_test.negate();
655 switch (msk) {
656 case BoolTest::ne: {
657 // If val is compared to its lower or upper bound, we can narrow the type
658 const TypeInt* val_t = gvn->type(val)->isa_int();
659 if (val_t != nullptr && !val_t->singleton() && cmp2_t->is_con()) {
660 if (val_t->_lo == lo) {
661 return TypeInt::make(val_t->_lo + 1, val_t->_hi, val_t->_widen);
662 } else if (val_t->_hi == hi) {
663 return TypeInt::make(val_t->_lo, val_t->_hi - 1, val_t->_widen);
664 }
665 }
666 // Can't refine type
667 return nullptr;
668 }
669 case BoolTest::eq:
670 return cmp2_t;
671 case BoolTest::lt:
672 lo = TypeInt::INT->_lo;
673 if (hi != min_jint) {
674 hi = hi - 1;
675 }
676 break;
677 case BoolTest::le:
678 lo = TypeInt::INT->_lo;
679 break;
680 case BoolTest::gt:
681 if (lo != max_jint) {
682 lo = lo + 1;
683 }
684 hi = TypeInt::INT->_hi;
685 break;
686 case BoolTest::ge:
687 // lo unchanged
688 hi = TypeInt::INT->_hi;
689 break;
690 default:
691 break;
692 }
693 const TypeInt* rtn_t = TypeInt::make(lo, hi, cmp2_t->_widen);
694 return rtn_t;
695 }
696 }
697 }
698 }
699 }
700 return nullptr;
701 }
702
703 //------------------------------fold_compares----------------------------
704 // See if a pair of CmpIs can be converted into a CmpU. In some cases
705 // the direction of this if is determined by the preceding if so it
706 // can be eliminate entirely.
707 //
708 // Given an if testing (CmpI n v) check for an immediately control
709 // dependent if that is testing (CmpI n v2) and has one projection
710 // leading to this if and the other projection leading to a region
711 // that merges one of this ifs control projections.
712 //
713 // If
714 // / |
715 // / |
716 // / |
717 // If |
718 // /\ |
719 // / \ |
720 // / \ |
721 // / Region
722 //
723 // Or given an if testing (CmpI n v) check for a dominating if that is
724 // testing (CmpI n v2), both having one projection leading to an
725 // uncommon trap. Allow Another independent guard in between to cover
726 // an explicit range check:
727 // if (index < 0 || index >= array.length) {
728 // which may need a null check to guard the LoadRange
729 //
730 // If
731 // / \
732 // / \
733 // / \
734 // If unc
735 // /\
736 // / \
737 // / \
738 // / unc
739 //
740
741 // Is the comparison for this If suitable for folding?
742 bool IfNode::cmpi_folds(PhaseIterGVN* igvn, bool fold_ne) {
743 return in(1) != nullptr &&
744 in(1)->is_Bool() &&
745 in(1)->in(1) != nullptr &&
746 in(1)->in(1)->Opcode() == Op_CmpI &&
747 in(1)->in(1)->in(2) != nullptr &&
748 in(1)->in(1)->in(2) != igvn->C->top() &&
749 (in(1)->as_Bool()->_test.is_less() ||
750 in(1)->as_Bool()->_test.is_greater() ||
751 (fold_ne && in(1)->as_Bool()->_test._test == BoolTest::ne));
752 }
753
754 // Is a dominating control suitable for folding with this if?
755 bool IfNode::is_ctrl_folds(Node* ctrl, PhaseIterGVN* igvn) {
756 return ctrl != nullptr &&
757 ctrl->is_Proj() &&
758 ctrl->in(0) != nullptr &&
759 ctrl->in(0)->Opcode() == Op_If &&
760 ctrl->in(0)->outcnt() == 2 &&
761 ctrl->in(0)->as_If()->cmpi_folds(igvn, true) &&
762 // Must compare same value
763 ctrl->in(0)->in(1)->in(1)->in(1) != nullptr &&
764 ctrl->in(0)->in(1)->in(1)->in(1) != igvn->C->top() &&
765 ctrl->in(0)->in(1)->in(1)->in(1) == in(1)->in(1)->in(1);
766 }
767
768 // Do this If and the dominating If share a region?
769 bool IfNode::has_shared_region(ProjNode* proj, ProjNode*& success, ProjNode*& fail) {
770 ProjNode* otherproj = proj->other_if_proj();
771 Node* otherproj_ctrl_use = otherproj->unique_ctrl_out_or_null();
772 RegionNode* region = (otherproj_ctrl_use != nullptr && otherproj_ctrl_use->is_Region()) ? otherproj_ctrl_use->as_Region() : nullptr;
773 success = nullptr;
774 fail = nullptr;
775
776 if (otherproj->outcnt() == 1 && region != nullptr && !region->has_phi()) {
777 for (int i = 0; i < 2; i++) {
778 ProjNode* proj = proj_out(i);
779 if (success == nullptr && proj->outcnt() == 1 && proj->unique_out() == region) {
780 success = proj;
781 } else if (fail == nullptr) {
782 fail = proj;
783 } else {
784 success = fail = nullptr;
785 }
786 }
787 }
788 return success != nullptr && fail != nullptr;
789 }
790
791 bool IfNode::is_dominator_unc(CallStaticJavaNode* dom_unc, CallStaticJavaNode* unc) {
792 // Different methods and methods containing jsrs are not supported.
793 ciMethod* method = unc->jvms()->method();
794 ciMethod* dom_method = dom_unc->jvms()->method();
795 if (method != dom_method || method->has_jsrs()) {
796 return false;
797 }
798 // Check that both traps are in the same activation of the method (instead
799 // of two activations being inlined through different call sites) by verifying
800 // that the call stacks are equal for both JVMStates.
801 JVMState* dom_caller = dom_unc->jvms()->caller();
802 JVMState* caller = unc->jvms()->caller();
803 if ((dom_caller == nullptr) != (caller == nullptr)) {
804 // The current method must either be inlined into both dom_caller and
805 // caller or must not be inlined at all (top method). Bail out otherwise.
806 return false;
807 } else if (dom_caller != nullptr && !dom_caller->same_calls_as(caller)) {
808 return false;
809 }
810 // Check that the bci of the dominating uncommon trap dominates the bci
811 // of the dominated uncommon trap. Otherwise we may not re-execute
812 // the dominated check after deoptimization from the merged uncommon trap.
813 ciTypeFlow* flow = dom_method->get_flow_analysis();
814 int bci = unc->jvms()->bci();
815 int dom_bci = dom_unc->jvms()->bci();
816 if (!flow->is_dominated_by(bci, dom_bci)) {
817 return false;
818 }
819
820 return true;
821 }
822
823 // Return projection that leads to an uncommon trap if any
824 ProjNode* IfNode::uncommon_trap_proj(CallStaticJavaNode*& call) const {
825 for (int i = 0; i < 2; i++) {
826 call = proj_out(i)->is_uncommon_trap_proj();
827 if (call != nullptr) {
828 return proj_out(i);
829 }
830 }
831 return nullptr;
832 }
833
834 // Do this If and the dominating If both branch out to an uncommon trap
835 bool IfNode::has_only_uncommon_traps(ProjNode* proj, ProjNode*& success, ProjNode*& fail, PhaseIterGVN* igvn) {
836 ProjNode* otherproj = proj->other_if_proj();
837 CallStaticJavaNode* dom_unc = otherproj->is_uncommon_trap_proj();
838
839 if (otherproj->outcnt() == 1 && dom_unc != nullptr) {
840 // We need to re-execute the folded Ifs after deoptimization from the merged traps
841 if (!dom_unc->jvms()->should_reexecute()) {
842 return false;
843 }
844
845 CallStaticJavaNode* unc = nullptr;
846 ProjNode* unc_proj = uncommon_trap_proj(unc);
847 if (unc_proj != nullptr && unc_proj->outcnt() == 1) {
848 if (dom_unc == unc) {
849 // Allow the uncommon trap to be shared through a region
850 RegionNode* r = unc->in(0)->as_Region();
851 if (r->outcnt() != 2 || r->req() != 3 || r->find_edge(otherproj) == -1 || r->find_edge(unc_proj) == -1) {
852 return false;
853 }
854 assert(r->has_phi() == nullptr, "simple region shouldn't have a phi");
855 } else if (dom_unc->in(0) != otherproj || unc->in(0) != unc_proj) {
856 return false;
857 }
858
859 if (!is_dominator_unc(dom_unc, unc)) {
860 return false;
861 }
862
863 // See merge_uncommon_traps: the reason of the uncommon trap
864 // will be changed and the state of the dominating If will be
865 // used. Checked that we didn't apply this transformation in a
866 // previous compilation and it didn't cause too many traps
867 ciMethod* dom_method = dom_unc->jvms()->method();
868 int dom_bci = dom_unc->jvms()->bci();
869 if (!igvn->C->too_many_traps(dom_method, dom_bci, Deoptimization::Reason_unstable_fused_if) &&
870 !igvn->C->too_many_traps(dom_method, dom_bci, Deoptimization::Reason_range_check) &&
871 // Return true if c2 manages to reconcile with UnstableIf optimization. See the comments for it.
872 igvn->C->remove_unstable_if_trap(dom_unc, true/*yield*/)) {
873 success = unc_proj;
874 fail = unc_proj->other_if_proj();
875 return true;
876 }
877 }
878 }
879 return false;
880 }
881
882 // Check that the 2 CmpI can be folded into as single CmpU and proceed with the folding
883 bool IfNode::fold_compares_helper(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn) {
884 Node* this_cmp = in(1)->in(1);
885 BoolNode* this_bool = in(1)->as_Bool();
886 IfNode* dom_iff = proj->in(0)->as_If();
887 BoolNode* dom_bool = dom_iff->in(1)->as_Bool();
888 Node* lo = dom_iff->in(1)->in(1)->in(2);
889 Node* hi = this_cmp->in(2);
890 Node* n = this_cmp->in(1);
891 ProjNode* otherproj = proj->other_if_proj();
892
893 const TypeInt* lo_type = IfNode::filtered_int_type(igvn, n, otherproj);
894 const TypeInt* hi_type = IfNode::filtered_int_type(igvn, n, success);
895
896 BoolTest::mask lo_test = dom_bool->_test._test;
897 BoolTest::mask hi_test = this_bool->_test._test;
898 BoolTest::mask cond = hi_test;
899
900 // convert:
901 //
902 // dom_bool = x {<,<=,>,>=} a
903 // / \
904 // proj = {True,False} / \ otherproj = {False,True}
905 // /
906 // this_bool = x {<,<=} b
907 // / \
908 // fail = {True,False} / \ success = {False,True}
909 // /
910 //
911 // (Second test guaranteed canonicalized, first one may not have
912 // been canonicalized yet)
913 //
914 // into:
915 //
916 // cond = (x - lo) {<u,<=u,>u,>=u} adjusted_lim
917 // / \
918 // fail / \ success
919 // /
920 //
921
922 // Figure out which of the two tests sets the upper bound and which
923 // sets the lower bound if any.
924 Node* adjusted_lim = nullptr;
925 if (lo_type != nullptr && hi_type != nullptr && hi_type->_lo > lo_type->_hi &&
926 hi_type->_hi == max_jint && lo_type->_lo == min_jint && lo_test != BoolTest::ne) {
927 assert((dom_bool->_test.is_less() && !proj->_con) ||
928 (dom_bool->_test.is_greater() && proj->_con), "incorrect test");
929
930 // this_bool = <
931 // dom_bool = >= (proj = True) or dom_bool = < (proj = False)
932 // x in [a, b[ on the fail (= True) projection, b > a-1 (because of hi_type->_lo > lo_type->_hi test above):
933 // lo = a, hi = b, adjusted_lim = b-a, cond = <u
934 // dom_bool = > (proj = True) or dom_bool = <= (proj = False)
935 // x in ]a, b[ on the fail (= True) projection, b > a:
936 // lo = a+1, hi = b, adjusted_lim = b-a-1, cond = <u
937 // this_bool = <=
938 // dom_bool = >= (proj = True) or dom_bool = < (proj = False)
939 // x in [a, b] on the fail (= True) projection, b+1 > a-1:
940 // lo = a, hi = b, adjusted_lim = b-a+1, cond = <u
941 // lo = a, hi = b, adjusted_lim = b-a, cond = <=u doesn't work because b = a - 1 is possible, then b-a = -1
942 // dom_bool = > (proj = True) or dom_bool = <= (proj = False)
943 // x in ]a, b] on the fail (= True) projection b+1 > a:
944 // lo = a+1, hi = b, adjusted_lim = b-a, cond = <u
945 // lo = a+1, hi = b, adjusted_lim = b-a-1, cond = <=u doesn't work because a = b is possible, then b-a-1 = -1
946
947 if (hi_test == BoolTest::lt) {
948 if (lo_test == BoolTest::gt || lo_test == BoolTest::le) {
949 lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
950 }
951 } else if (hi_test == BoolTest::le) {
952 if (lo_test == BoolTest::ge || lo_test == BoolTest::lt) {
953 adjusted_lim = igvn->transform(new SubINode(hi, lo));
954 adjusted_lim = igvn->transform(new AddINode(adjusted_lim, igvn->intcon(1)));
955 cond = BoolTest::lt;
956 } else if (lo_test == BoolTest::gt || lo_test == BoolTest::le) {
957 adjusted_lim = igvn->transform(new SubINode(hi, lo));
958 lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
959 cond = BoolTest::lt;
960 } else {
961 assert(false, "unhandled lo_test: %d", lo_test);
962 return false;
963 }
964 } else {
965 assert(igvn->_worklist.member(in(1)) && in(1)->Value(igvn) != igvn->type(in(1)), "unhandled hi_test: %d", hi_test);
966 return false;
967 }
968 // this test was canonicalized
969 assert(this_bool->_test.is_less() && fail->_con, "incorrect test");
970 } else if (lo_type != nullptr && hi_type != nullptr && lo_type->_lo > hi_type->_hi &&
971 lo_type->_hi == max_jint && hi_type->_lo == min_jint && lo_test != BoolTest::ne) {
972
973 // this_bool = <
974 // dom_bool = < (proj = True) or dom_bool = >= (proj = False)
975 // x in [b, a[ on the fail (= False) projection, a > b-1 (because of lo_type->_lo > hi_type->_hi above):
976 // lo = b, hi = a, adjusted_lim = a-b, cond = >=u
977 // dom_bool = <= (proj = True) or dom_bool = > (proj = False)
978 // x in [b, a] on the fail (= False) projection, a+1 > b-1:
979 // lo = b, hi = a, adjusted_lim = a-b+1, cond = >=u
980 // lo = b, hi = a, adjusted_lim = a-b, cond = >u doesn't work because a = b - 1 is possible, then b-a = -1
981 // this_bool = <=
982 // dom_bool = < (proj = True) or dom_bool = >= (proj = False)
983 // x in ]b, a[ on the fail (= False) projection, a > b:
984 // lo = b+1, hi = a, adjusted_lim = a-b-1, cond = >=u
985 // dom_bool = <= (proj = True) or dom_bool = > (proj = False)
986 // x in ]b, a] on the fail (= False) projection, a+1 > b:
987 // lo = b+1, hi = a, adjusted_lim = a-b, cond = >=u
988 // lo = b+1, hi = a, adjusted_lim = a-b-1, cond = >u doesn't work because a = b is possible, then b-a-1 = -1
989
990 swap(lo, hi);
991 swap(lo_type, hi_type);
992 swap(lo_test, hi_test);
993
994 assert((dom_bool->_test.is_less() && proj->_con) ||
995 (dom_bool->_test.is_greater() && !proj->_con), "incorrect test");
996
997 cond = (hi_test == BoolTest::le || hi_test == BoolTest::gt) ? BoolTest::gt : BoolTest::ge;
998
999 if (lo_test == BoolTest::lt) {
1000 if (hi_test == BoolTest::lt || hi_test == BoolTest::ge) {
1001 cond = BoolTest::ge;
1002 } else if (hi_test == BoolTest::le || hi_test == BoolTest::gt) {
1003 adjusted_lim = igvn->transform(new SubINode(hi, lo));
1004 adjusted_lim = igvn->transform(new AddINode(adjusted_lim, igvn->intcon(1)));
1005 cond = BoolTest::ge;
1006 } else {
1007 assert(false, "unhandled hi_test: %d", hi_test);
1008 return false;
1009 }
1010 } else if (lo_test == BoolTest::le) {
1011 if (hi_test == BoolTest::lt || hi_test == BoolTest::ge) {
1012 lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
1013 cond = BoolTest::ge;
1014 } else if (hi_test == BoolTest::le || hi_test == BoolTest::gt) {
1015 adjusted_lim = igvn->transform(new SubINode(hi, lo));
1016 lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
1017 cond = BoolTest::ge;
1018 } else {
1019 assert(false, "unhandled hi_test: %d", hi_test);
1020 return false;
1021 }
1022 } else {
1023 assert(igvn->_worklist.member(in(1)) && in(1)->Value(igvn) != igvn->type(in(1)), "unhandled lo_test: %d", lo_test);
1024 return false;
1025 }
1026 // this test was canonicalized
1027 assert(this_bool->_test.is_less() && !fail->_con, "incorrect test");
1028 } else {
1029 const TypeInt* failtype = filtered_int_type(igvn, n, proj);
1030 if (failtype != nullptr) {
1031 const TypeInt* type2 = filtered_int_type(igvn, n, fail);
1032 if (type2 != nullptr) {
1033 failtype = failtype->join(type2)->is_int();
1034 if (failtype->empty()) {
1035 // previous if determines the result of this if so
1036 // replace Bool with constant
1037 igvn->replace_input_of(this, 1, igvn->intcon(success->_con));
1038 return true;
1039 }
1040 }
1041 }
1042 return false;
1043 }
1044
1045 assert(lo != nullptr && hi != nullptr, "sanity");
1046 Node* hook = new Node(lo); // Add a use to lo to prevent him from dying
1047 // Merge the two compares into a single unsigned compare by building (CmpU (n - lo) (hi - lo))
1048 Node* adjusted_val = igvn->transform(new SubINode(n, lo));
1049 if (adjusted_lim == nullptr) {
1050 adjusted_lim = igvn->transform(new SubINode(hi, lo));
1051 }
1052 hook->destruct(igvn);
1053
1054 if (adjusted_val->is_top() || adjusted_lim->is_top()) {
1055 return false;
1056 }
1057
1058 if (igvn->type(adjusted_lim)->is_int()->_lo < 0 &&
1059 !igvn->C->post_loop_opts_phase()) {
1060 // If range check elimination applies to this comparison, it includes code to protect from overflows that may
1061 // cause the main loop to be skipped entirely. Delay this transformation.
1062 // Example:
1063 // for (int i = 0; i < limit; i++) {
1064 // if (i < max_jint && i > min_jint) {...
1065 // }
1066 // Comparisons folded as:
1067 // i - min_jint - 1 <u -2
1068 // when RC applies, main loop limit becomes:
1069 // min(limit, max(-2 + min_jint + 1, min_jint))
1070 // = min(limit, min_jint)
1071 // = min_jint
1072 if (adjusted_val->outcnt() == 0) {
1073 igvn->remove_dead_node(adjusted_val);
1074 }
1075 if (adjusted_lim->outcnt() == 0) {
1076 igvn->remove_dead_node(adjusted_lim);
1077 }
1078 igvn->C->record_for_post_loop_opts_igvn(this);
1079 return false;
1080 }
1081
1082 Node* newcmp = igvn->transform(new CmpUNode(adjusted_val, adjusted_lim));
1083 Node* newbool = igvn->transform(new BoolNode(newcmp, cond));
1084
1085 igvn->replace_input_of(dom_iff, 1, igvn->intcon(proj->_con));
1086 igvn->replace_input_of(this, 1, newbool);
1087
1088 return true;
1089 }
1090
1091 // Merge the branches that trap for this If and the dominating If into
1092 // a single region that branches to the uncommon trap for the
1093 // dominating If
1094 Node* IfNode::merge_uncommon_traps(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn) {
1095 Node* res = this;
1096 assert(success->in(0) == this, "bad projection");
1097
1098 ProjNode* otherproj = proj->other_if_proj();
1099
1100 CallStaticJavaNode* unc = success->is_uncommon_trap_proj();
1101 CallStaticJavaNode* dom_unc = otherproj->is_uncommon_trap_proj();
1102
1103 if (unc != dom_unc) {
1104 Node* r = new RegionNode(3);
1105
1106 r->set_req(1, otherproj);
1107 r->set_req(2, success);
1108 r = igvn->transform(r);
1109 assert(r->is_Region(), "can't go away");
1110
1111 // Make both If trap at the state of the first If: once the CmpI
1112 // nodes are merged, if we trap we don't know which of the CmpI
1113 // nodes would have caused the trap so we have to restart
1114 // execution at the first one
1115 igvn->replace_input_of(dom_unc, 0, r);
1116 igvn->replace_input_of(unc, 0, igvn->C->top());
1117 }
1118 int trap_request = dom_unc->uncommon_trap_request();
1119 Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(trap_request);
1120 Deoptimization::DeoptAction action = Deoptimization::trap_request_action(trap_request);
1121
1122 int flip_test = 0;
1123 Node* l = nullptr;
1124 Node* r = nullptr;
1125
1126 if (success->in(0)->as_If()->range_check_trap_proj(flip_test, l, r) != nullptr) {
1127 // If this looks like a range check, change the trap to
1128 // Reason_range_check so the compiler recognizes it as a range
1129 // check and applies the corresponding optimizations
1130 trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_range_check, action);
1131
1132 improve_address_types(l, r, fail, igvn);
1133
1134 res = igvn->transform(new RangeCheckNode(in(0), in(1), _prob, _fcnt));
1135 } else if (unc != dom_unc) {
1136 // If we trap we won't know what CmpI would have caused the trap
1137 // so use a special trap reason to mark this pair of CmpI nodes as
1138 // bad candidate for folding. On recompilation we won't fold them
1139 // and we may trap again but this time we'll know what branch
1140 // traps
1141 trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_unstable_fused_if, action);
1142 }
1143 igvn->replace_input_of(dom_unc, TypeFunc::Parms, igvn->intcon(trap_request));
1144 return res;
1145 }
1146
1147 // If we are turning 2 CmpI nodes into a CmpU that follows the pattern
1148 // of a rangecheck on index i, on 64 bit the compares may be followed
1149 // by memory accesses using i as index. In that case, the CmpU tells
1150 // us something about the values taken by i that can help the compiler
1151 // (see Compile::conv_I2X_index())
1152 void IfNode::improve_address_types(Node* l, Node* r, ProjNode* fail, PhaseIterGVN* igvn) {
1153 #ifdef _LP64
1154 ResourceMark rm;
1155 Node_Stack stack(2);
1156
1157 assert(r->Opcode() == Op_LoadRange, "unexpected range check");
1158 const TypeInt* array_size = igvn->type(r)->is_int();
1159
1160 stack.push(l, 0);
1161
1162 while(stack.size() > 0) {
1163 Node* n = stack.node();
1164 uint start = stack.index();
1165
1166 uint i = start;
1167 for (; i < n->outcnt(); i++) {
1168 Node* use = n->raw_out(i);
1169 if (stack.size() == 1) {
1170 if (use->Opcode() == Op_ConvI2L) {
1171 const TypeLong* bounds = use->as_Type()->type()->is_long();
1172 if (bounds->_lo <= array_size->_lo && bounds->_hi >= array_size->_hi &&
1173 (bounds->_lo != array_size->_lo || bounds->_hi != array_size->_hi)) {
1174 stack.set_index(i+1);
1175 stack.push(use, 0);
1176 break;
1177 }
1178 }
1179 } else if (use->is_Mem()) {
1180 Node* ctrl = use->in(0);
1181 for (int i = 0; i < 10 && ctrl != nullptr && ctrl != fail; i++) {
1182 ctrl = up_one_dom(ctrl);
1183 }
1184 if (ctrl == fail) {
1185 Node* init_n = stack.node_at(1);
1186 assert(init_n->Opcode() == Op_ConvI2L, "unexpected first node");
1187 // Create a new narrow ConvI2L node that is dependent on the range check
1188 Node* new_n = igvn->C->conv_I2X_index(igvn, l, array_size, fail);
1189
1190 // The type of the ConvI2L may be widen and so the new
1191 // ConvI2L may not be better than an existing ConvI2L
1192 if (new_n != init_n) {
1193 for (uint j = 2; j < stack.size(); j++) {
1194 Node* n = stack.node_at(j);
1195 Node* clone = n->clone();
1196 int rep = clone->replace_edge(init_n, new_n, igvn);
1197 assert(rep > 0, "can't find expected node?");
1198 clone = igvn->transform(clone);
1199 init_n = n;
1200 new_n = clone;
1201 }
1202 igvn->hash_delete(use);
1203 int rep = use->replace_edge(init_n, new_n, igvn);
1204 assert(rep > 0, "can't find expected node?");
1205 igvn->transform(use);
1206 if (init_n->outcnt() == 0) {
1207 igvn->_worklist.push(init_n);
1208 }
1209 }
1210 }
1211 } else if (use->in(0) == nullptr && (igvn->type(use)->isa_long() ||
1212 igvn->type(use)->isa_ptr())) {
1213 stack.set_index(i+1);
1214 stack.push(use, 0);
1215 break;
1216 }
1217 }
1218 if (i == n->outcnt()) {
1219 stack.pop();
1220 }
1221 }
1222 #endif
1223 }
1224
1225 bool IfNode::is_cmp_with_loadrange(ProjNode* proj) {
1226 if (in(1) != nullptr &&
1227 in(1)->in(1) != nullptr &&
1228 in(1)->in(1)->in(2) != nullptr) {
1229 Node* other = in(1)->in(1)->in(2);
1230 if (other->Opcode() == Op_LoadRange &&
1231 ((other->in(0) != nullptr && other->in(0) == proj) ||
1232 (other->in(0) == nullptr &&
1233 other->in(2) != nullptr &&
1234 other->in(2)->is_AddP() &&
1235 other->in(2)->in(1) != nullptr &&
1236 other->in(2)->in(1)->Opcode() == Op_CastPP &&
1237 other->in(2)->in(1)->in(0) == proj))) {
1238 return true;
1239 }
1240 }
1241 return false;
1242 }
1243
1244 bool IfNode::is_null_check(ProjNode* proj, PhaseIterGVN* igvn) {
1245 Node* other = in(1)->in(1)->in(2);
1246 if (other->in(MemNode::Address) != nullptr &&
1247 proj->in(0)->in(1) != nullptr &&
1248 proj->in(0)->in(1)->is_Bool() &&
1249 proj->in(0)->in(1)->in(1) != nullptr &&
1250 proj->in(0)->in(1)->in(1)->Opcode() == Op_CmpP &&
1251 proj->in(0)->in(1)->in(1)->in(2) != nullptr &&
1252 proj->in(0)->in(1)->in(1)->in(1) == other->in(MemNode::Address)->in(AddPNode::Address)->uncast() &&
1253 igvn->type(proj->in(0)->in(1)->in(1)->in(2)) == TypePtr::NULL_PTR) {
1254 return true;
1255 }
1256 return false;
1257 }
1258
1259 // Check that the If that is in between the 2 integer comparisons has
1260 // no side effect
1261 bool IfNode::is_side_effect_free_test(ProjNode* proj, PhaseIterGVN* igvn) {
1262 if (proj == nullptr) {
1263 return false;
1264 }
1265 CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern();
1266 if (unc != nullptr && proj->outcnt() <= 2) {
1267 if (proj->outcnt() == 1 ||
1268 // Allow simple null check from LoadRange
1269 (is_cmp_with_loadrange(proj) && is_null_check(proj, igvn))) {
1270 CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern();
1271 CallStaticJavaNode* dom_unc = proj->in(0)->in(0)->as_Proj()->is_uncommon_trap_if_pattern();
1272 assert(dom_unc != nullptr, "is_uncommon_trap_if_pattern returned null");
1273
1274 // reroute_side_effect_free_unc changes the state of this
1275 // uncommon trap to restart execution at the previous
1276 // CmpI. Check that this change in a previous compilation didn't
1277 // cause too many traps.
1278 int trap_request = unc->uncommon_trap_request();
1279 Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(trap_request);
1280
1281 if (igvn->C->too_many_traps(dom_unc->jvms()->method(), dom_unc->jvms()->bci(), reason)) {
1282 return false;
1283 }
1284
1285 if (!is_dominator_unc(dom_unc, unc)) {
1286 return false;
1287 }
1288
1289 return true;
1290 }
1291 }
1292 return false;
1293 }
1294
1295 // Make the If between the 2 integer comparisons trap at the state of
1296 // the first If: the last CmpI is the one replaced by a CmpU and the
1297 // first CmpI is eliminated, so the test between the 2 CmpI nodes
1298 // won't be guarded by the first CmpI anymore. It can trap in cases
1299 // where the first CmpI would have prevented it from executing: on a
1300 // trap, we need to restart execution at the state of the first CmpI
1301 void IfNode::reroute_side_effect_free_unc(ProjNode* proj, ProjNode* dom_proj, PhaseIterGVN* igvn) {
1302 CallStaticJavaNode* dom_unc = dom_proj->is_uncommon_trap_if_pattern();
1303 ProjNode* otherproj = proj->other_if_proj();
1304 CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern();
1305 Node* call_proj = dom_unc->unique_ctrl_out();
1306 Node* halt = call_proj->unique_ctrl_out();
1307
1308 Node* new_unc = dom_unc->clone();
1309 call_proj = call_proj->clone();
1310 halt = halt->clone();
1311 Node* c = otherproj->clone();
1312
1313 c = igvn->transform(c);
1314 new_unc->set_req(TypeFunc::Parms, unc->in(TypeFunc::Parms));
1315 new_unc->set_req(0, c);
1316 new_unc = igvn->transform(new_unc);
1317 call_proj->set_req(0, new_unc);
1318 call_proj = igvn->transform(call_proj);
1319 halt->set_req(0, call_proj);
1320 halt = igvn->transform(halt);
1321
1322 igvn->replace_node(otherproj, igvn->C->top());
1323 igvn->C->root()->add_req(halt);
1324 }
1325
1326 Node* IfNode::fold_compares(PhaseIterGVN* igvn) {
1327 if (Opcode() != Op_If) return nullptr;
1328
1329 if (cmpi_folds(igvn)) {
1330 Node* ctrl = in(0);
1331 if (is_ctrl_folds(ctrl, igvn) && ctrl->outcnt() == 1) {
1332 // A integer comparison immediately dominated by another integer
1333 // comparison
1334 ProjNode* success = nullptr;
1335 ProjNode* fail = nullptr;
1336 ProjNode* dom_cmp = ctrl->as_Proj();
1337 if (has_shared_region(dom_cmp, success, fail) &&
1338 // Next call modifies graph so must be last
1339 fold_compares_helper(dom_cmp, success, fail, igvn)) {
1340 return this;
1341 }
1342 if (has_only_uncommon_traps(dom_cmp, success, fail, igvn) &&
1343 // Next call modifies graph so must be last
1344 fold_compares_helper(dom_cmp, success, fail, igvn)) {
1345 return merge_uncommon_traps(dom_cmp, success, fail, igvn);
1346 }
1347 return nullptr;
1348 } else if (ctrl->in(0) != nullptr &&
1349 ctrl->in(0)->in(0) != nullptr) {
1350 ProjNode* success = nullptr;
1351 ProjNode* fail = nullptr;
1352 Node* dom = ctrl->in(0)->in(0);
1353 ProjNode* dom_cmp = dom->isa_Proj();
1354 ProjNode* other_cmp = ctrl->isa_Proj();
1355
1356 // Check if it's an integer comparison dominated by another
1357 // integer comparison with another test in between
1358 if (is_ctrl_folds(dom, igvn) &&
1359 has_only_uncommon_traps(dom_cmp, success, fail, igvn) &&
1360 is_side_effect_free_test(other_cmp, igvn) &&
1361 // Next call modifies graph so must be last
1362 fold_compares_helper(dom_cmp, success, fail, igvn)) {
1363 reroute_side_effect_free_unc(other_cmp, dom_cmp, igvn);
1364 return merge_uncommon_traps(dom_cmp, success, fail, igvn);
1365 }
1366 }
1367 }
1368 return nullptr;
1369 }
1370
1371 //------------------------------remove_useless_bool----------------------------
1372 // Check for people making a useless boolean: things like
1373 // if( (x < y ? true : false) ) { ... }
1374 // Replace with if( x < y ) { ... }
1375 static Node *remove_useless_bool(IfNode *iff, PhaseGVN *phase) {
1376 Node *i1 = iff->in(1);
1377 if( !i1->is_Bool() ) return nullptr;
1378 BoolNode *bol = i1->as_Bool();
1379
1380 Node *cmp = bol->in(1);
1381 if( cmp->Opcode() != Op_CmpI ) return nullptr;
1382
1383 // Must be comparing against a bool
1384 const Type *cmp2_t = phase->type( cmp->in(2) );
1385 if( cmp2_t != TypeInt::ZERO &&
1386 cmp2_t != TypeInt::ONE )
1387 return nullptr;
1388
1389 // Find a prior merge point merging the boolean
1390 i1 = cmp->in(1);
1391 if( !i1->is_Phi() ) return nullptr;
1392 PhiNode *phi = i1->as_Phi();
1393 if( phase->type( phi ) != TypeInt::BOOL )
1394 return nullptr;
1395
1396 // Check for diamond pattern
1397 int true_path = phi->is_diamond_phi();
1398 if( true_path == 0 ) return nullptr;
1399
1400 // Make sure that iff and the control of the phi are different. This
1401 // should really only happen for dead control flow since it requires
1402 // an illegal cycle.
1403 if (phi->in(0)->in(1)->in(0) == iff) return nullptr;
1404
1405 // phi->region->if_proj->ifnode->bool->cmp
1406 BoolNode *bol2 = phi->in(0)->in(1)->in(0)->in(1)->as_Bool();
1407
1408 // Now get the 'sense' of the test correct so we can plug in
1409 // either iff2->in(1) or its complement.
1410 int flip = 0;
1411 if( bol->_test._test == BoolTest::ne ) flip = 1-flip;
1412 else if( bol->_test._test != BoolTest::eq ) return nullptr;
1413 if( cmp2_t == TypeInt::ZERO ) flip = 1-flip;
1414
1415 const Type *phi1_t = phase->type( phi->in(1) );
1416 const Type *phi2_t = phase->type( phi->in(2) );
1417 // Check for Phi(0,1) and flip
1418 if( phi1_t == TypeInt::ZERO ) {
1419 if( phi2_t != TypeInt::ONE ) return nullptr;
1420 flip = 1-flip;
1421 } else {
1422 // Check for Phi(1,0)
1423 if( phi1_t != TypeInt::ONE ) return nullptr;
1424 if( phi2_t != TypeInt::ZERO ) return nullptr;
1425 }
1426 if( true_path == 2 ) {
1427 flip = 1-flip;
1428 }
1429
1430 Node* new_bol = (flip ? phase->transform( bol2->negate(phase) ) : bol2);
1431 assert(new_bol != iff->in(1), "must make progress");
1432 iff->set_req_X(1, new_bol, phase);
1433 // Intervening diamond probably goes dead
1434 phase->C->set_major_progress();
1435 return iff;
1436 }
1437
1438 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff);
1439
1440 struct RangeCheck {
1441 IfProjNode* ctl;
1442 jint off;
1443 };
1444
1445 Node* IfNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
1446 if (remove_dead_region(phase, can_reshape)) return this;
1447 // No Def-Use info?
1448 if (!can_reshape) return nullptr;
1449
1450 // Don't bother trying to transform a dead if
1451 if (in(0)->is_top()) return nullptr;
1452 // Don't bother trying to transform an if with a dead test
1453 if (in(1)->is_top()) return nullptr;
1454 // Another variation of a dead test
1455 if (in(1)->is_Con()) return nullptr;
1456 // Another variation of a dead if
1457 if (outcnt() < 2) return nullptr;
1458
1459 // Canonicalize the test.
1460 Node* idt_if = idealize_test(phase, this);
1461 if (idt_if != nullptr) return idt_if;
1462
1463 // Try to split the IF
1464 PhaseIterGVN *igvn = phase->is_IterGVN();
1465 Node *s = split_if(this, igvn);
1466 if (s != nullptr) return s;
1467
1468 return NodeSentinel;
1469 }
1470
1471 //------------------------------Ideal------------------------------------------
1472 // Return a node which is more "ideal" than the current node. Strip out
1473 // control copies
1474 Node* IfNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1475 Node* res = Ideal_common(phase, can_reshape);
1476 if (res != NodeSentinel) {
1477 return res;
1478 }
1479
1480 // Check for people making a useless boolean: things like
1481 // if( (x < y ? true : false) ) { ... }
1482 // Replace with if( x < y ) { ... }
1483 Node* bol2 = remove_useless_bool(this, phase);
1484 if (bol2) return bol2;
1485
1486 if (in(0) == nullptr) return nullptr; // Dead loop?
1487
1488 PhaseIterGVN* igvn = phase->is_IterGVN();
1489 Node* result = fold_compares(igvn);
1490 if (result != nullptr) {
1491 return result;
1492 }
1493
1494 // Scan for an equivalent test
1495 int dist = 4; // Cutoff limit for search
1496 if (is_If() && in(1)->is_Bool()) {
1497 Node* cmp = in(1)->in(1);
1498 if (cmp->Opcode() == Op_CmpP &&
1499 cmp->in(2) != nullptr && // make sure cmp is not already dead
1500 cmp->in(2)->bottom_type() == TypePtr::NULL_PTR) {
1501 dist = 64; // Limit for null-pointer scans
1502 }
1503 }
1504
1505 Node* prev_dom = search_identical(dist, igvn);
1506
1507 if (prev_dom != nullptr) {
1508 // Replace dominated IfNode
1509 return dominated_by(prev_dom, igvn, false);
1510 }
1511
1512 return simple_subsuming(igvn);
1513 }
1514
1515 //------------------------------dominated_by-----------------------------------
1516 Node* IfNode::dominated_by(Node* prev_dom, PhaseIterGVN* igvn, bool pin_array_access_nodes) {
1517 #ifndef PRODUCT
1518 if (TraceIterativeGVN) {
1519 tty->print(" Removing IfNode: "); this->dump();
1520 }
1521 #endif
1522
1523 igvn->hash_delete(this); // Remove self to prevent spurious V-N
1524 Node *idom = in(0);
1525 // Need opcode to decide which way 'this' test goes
1526 int prev_op = prev_dom->Opcode();
1527 Node *top = igvn->C->top(); // Shortcut to top
1528
1529 // Now walk the current IfNode's projections.
1530 // Loop ends when 'this' has no more uses.
1531 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
1532 Node *ifp = last_out(i); // Get IfTrue/IfFalse
1533 igvn->add_users_to_worklist(ifp);
1534 // Check which projection it is and set target.
1535 // Data-target is either the dominating projection of the same type
1536 // or TOP if the dominating projection is of opposite type.
1537 // Data-target will be used as the new control edge for the non-CFG
1538 // nodes like Casts and Loads.
1539 Node *data_target = (ifp->Opcode() == prev_op) ? prev_dom : top;
1540 // Control-target is just the If's immediate dominator or TOP.
1541 Node *ctrl_target = (ifp->Opcode() == prev_op) ? idom : top;
1542
1543 // For each child of an IfTrue/IfFalse projection, reroute.
1544 // Loop ends when projection has no more uses.
1545 for (DUIterator_Last jmin, j = ifp->last_outs(jmin); j >= jmin; --j) {
1546 Node* s = ifp->last_out(j); // Get child of IfTrue/IfFalse
1547 if (s->depends_only_on_test() && igvn->no_dependent_zero_check(s)) {
1548 // For control producers.
1549 // Do not rewire Div and Mod nodes which could have a zero divisor to avoid skipping their zero check.
1550 igvn->replace_input_of(s, 0, data_target); // Move child to data-target
1551 if (pin_array_access_nodes && data_target != top) {
1552 // As a result of range check smearing, Loads and range check Cast nodes that are control dependent on this
1553 // range check (that is about to be removed) now depend on multiple dominating range checks. After the removal
1554 // of this range check, these control dependent nodes end up at the lowest/nearest dominating check in the
1555 // graph. To ensure that these Loads/Casts do not float above any of the dominating checks (even when the
1556 // lowest dominating check is later replaced by yet another dominating check), we need to pin them at the
1557 // lowest dominating check.
1558 Node* clone = s->pin_array_access_node();
1559 if (clone != nullptr) {
1560 clone = igvn->transform(clone);
1561 igvn->replace_node(s, clone);
1562 }
1563 }
1564 } else {
1565 // Find the control input matching this def-use edge.
1566 // For Regions it may not be in slot 0.
1567 uint l;
1568 for (l = 0; s->in(l) != ifp; l++) { }
1569 igvn->replace_input_of(s, l, ctrl_target);
1570 }
1571 } // End for each child of a projection
1572
1573 igvn->remove_dead_node(ifp);
1574 } // End for each IfTrue/IfFalse child of If
1575
1576 // Kill the IfNode
1577 igvn->remove_dead_node(this);
1578
1579 // Must return either the original node (now dead) or a new node
1580 // (Do not return a top here, since that would break the uniqueness of top.)
1581 return new ConINode(TypeInt::ZERO);
1582 }
1583
1584 Node* IfNode::search_identical(int dist, PhaseIterGVN* igvn) {
1585 // Setup to scan up the CFG looking for a dominating test
1586 Node* dom = in(0);
1587 Node* prev_dom = this;
1588 int op = Opcode();
1589 // Search up the dominator tree for an If with an identical test
1590 while (dom->Opcode() != op || // Not same opcode?
1591 !same_condition(dom, igvn) || // Not same input 1?
1592 prev_dom->in(0) != dom) { // One path of test does not dominate?
1593 if (dist < 0) return nullptr;
1594
1595 dist--;
1596 prev_dom = dom;
1597 dom = up_one_dom(dom);
1598 if (!dom) return nullptr;
1599 }
1600
1601 // Check that we did not follow a loop back to ourselves
1602 if (this == dom) {
1603 return nullptr;
1604 }
1605
1606 #ifndef PRODUCT
1607 if (dist > 2) { // Add to count of null checks elided
1608 explicit_null_checks_elided++;
1609 }
1610 #endif
1611
1612 return prev_dom;
1613 }
1614
1615 bool IfNode::same_condition(const Node* dom, PhaseIterGVN* igvn) const {
1616 Node* dom_bool = dom->in(1);
1617 Node* this_bool = in(1);
1618 if (dom_bool == this_bool) {
1619 return true;
1620 }
1621
1622 if (dom_bool == nullptr || !dom_bool->is_Bool() ||
1623 this_bool == nullptr || !this_bool->is_Bool()) {
1624 return false;
1625 }
1626 Node* dom_cmp = dom_bool->in(1);
1627 Node* this_cmp = this_bool->in(1);
1628
1629 // If the comparison is a subtype check, then SubTypeCheck nodes may have profile data attached to them and may be
1630 // different nodes even-though they perform the same subtype check
1631 if (dom_cmp == nullptr || !dom_cmp->is_SubTypeCheck() ||
1632 this_cmp == nullptr || !this_cmp->is_SubTypeCheck()) {
1633 return false;
1634 }
1635
1636 if (dom_cmp->in(1) != this_cmp->in(1) ||
1637 dom_cmp->in(2) != this_cmp->in(2) ||
1638 dom_bool->as_Bool()->_test._test != this_bool->as_Bool()->_test._test) {
1639 return false;
1640 }
1641
1642 return true;
1643 }
1644
1645
1646 static int subsuming_bool_test_encode(Node*);
1647
1648 // Check if dominating test is subsuming 'this' one.
1649 //
1650 // cmp
1651 // / \
1652 // (r1) bool \
1653 // / bool (r2)
1654 // (dom) if \
1655 // \ )
1656 // (pre) if[TF] /
1657 // \ /
1658 // if (this)
1659 // \r1
1660 // r2\ eqT eqF neT neF ltT ltF leT leF gtT gtF geT geF
1661 // eq t f f t f - - f f - - f
1662 // ne f t t f t - - t t - - t
1663 // lt f - - f t f - f f - f t
1664 // le t - - t t - t f f t - t
1665 // gt f - - f f - f t t f - f
1666 // ge t - - t f t - t t - t f
1667 //
1668 Node* IfNode::simple_subsuming(PhaseIterGVN* igvn) {
1669 // Table encoding: N/A (na), True-branch (tb), False-branch (fb).
1670 static enum { na, tb, fb } s_short_circuit_map[6][12] = {
1671 /*rel: eq+T eq+F ne+T ne+F lt+T lt+F le+T le+F gt+T gt+F ge+T ge+F*/
1672 /*eq*/{ tb, fb, fb, tb, fb, na, na, fb, fb, na, na, fb },
1673 /*ne*/{ fb, tb, tb, fb, tb, na, na, tb, tb, na, na, tb },
1674 /*lt*/{ fb, na, na, fb, tb, fb, na, fb, fb, na, fb, tb },
1675 /*le*/{ tb, na, na, tb, tb, na, tb, fb, fb, tb, na, tb },
1676 /*gt*/{ fb, na, na, fb, fb, na, fb, tb, tb, fb, na, fb },
1677 /*ge*/{ tb, na, na, tb, fb, tb, na, tb, tb, na, tb, fb }};
1678
1679 Node* pre = in(0);
1680 if (!pre->is_IfTrue() && !pre->is_IfFalse()) {
1681 return nullptr;
1682 }
1683 Node* dom = pre->in(0);
1684 if (!dom->is_If()) {
1685 return nullptr;
1686 }
1687 Node* bol = in(1);
1688 if (!bol->is_Bool()) {
1689 return nullptr;
1690 }
1691 Node* cmp = in(1)->in(1);
1692 if (!cmp->is_Cmp()) {
1693 return nullptr;
1694 }
1695
1696 if (!dom->in(1)->is_Bool()) {
1697 return nullptr;
1698 }
1699 if (dom->in(1)->in(1) != cmp) { // Not same cond?
1700 return nullptr;
1701 }
1702
1703 int drel = subsuming_bool_test_encode(dom->in(1));
1704 int trel = subsuming_bool_test_encode(bol);
1705 int bout = pre->is_IfFalse() ? 1 : 0;
1706
1707 if (drel < 0 || trel < 0) {
1708 return nullptr;
1709 }
1710 int br = s_short_circuit_map[trel][2*drel+bout];
1711 if (br == na) {
1712 return nullptr;
1713 }
1714 #ifndef PRODUCT
1715 if (TraceIterativeGVN) {
1716 tty->print(" Subsumed IfNode: "); dump();
1717 }
1718 #endif
1719 // Replace condition with constant True(1)/False(0).
1720 bool is_always_true = br == tb;
1721 set_req(1, igvn->intcon(is_always_true ? 1 : 0));
1722
1723 // Update any data dependencies to the directly dominating test. This subsumed test is not immediately removed by igvn
1724 // and therefore subsequent optimizations might miss these data dependencies otherwise. There might be a dead loop
1725 // ('always_taken_proj' == 'pre') that is cleaned up later. Skip this case to make the iterator work properly.
1726 Node* always_taken_proj = proj_out(is_always_true);
1727 if (always_taken_proj != pre) {
1728 for (DUIterator_Fast imax, i = always_taken_proj->fast_outs(imax); i < imax; i++) {
1729 Node* u = always_taken_proj->fast_out(i);
1730 if (!u->is_CFG()) {
1731 igvn->replace_input_of(u, 0, pre);
1732 --i;
1733 --imax;
1734 }
1735 }
1736 }
1737
1738 if (bol->outcnt() == 0) {
1739 igvn->remove_dead_node(bol); // Kill the BoolNode.
1740 }
1741 return this;
1742 }
1743
1744 // Map BoolTest to local table encoding. The BoolTest (e)numerals
1745 // { eq = 0, ne = 4, le = 5, ge = 7, lt = 3, gt = 1 }
1746 // are mapped to table indices, while the remaining (e)numerals in BoolTest
1747 // { overflow = 2, no_overflow = 6, never = 8, illegal = 9 }
1748 // are ignored (these are not modeled in the table).
1749 //
1750 static int subsuming_bool_test_encode(Node* node) {
1751 precond(node->is_Bool());
1752 BoolTest::mask x = node->as_Bool()->_test._test;
1753 switch (x) {
1754 case BoolTest::eq: return 0;
1755 case BoolTest::ne: return 1;
1756 case BoolTest::lt: return 2;
1757 case BoolTest::le: return 3;
1758 case BoolTest::gt: return 4;
1759 case BoolTest::ge: return 5;
1760 case BoolTest::overflow:
1761 case BoolTest::no_overflow:
1762 case BoolTest::never:
1763 case BoolTest::illegal:
1764 default:
1765 return -1;
1766 }
1767 }
1768
1769 //------------------------------Identity---------------------------------------
1770 // If the test is constant & we match, then we are the input Control
1771 Node* IfProjNode::Identity(PhaseGVN* phase) {
1772 // Can only optimize if cannot go the other way
1773 const TypeTuple *t = phase->type(in(0))->is_tuple();
1774 if (t == TypeTuple::IFNEITHER || (always_taken(t) &&
1775 // During parsing (GVN) we don't remove dead code aggressively.
1776 // Cut off dead branch and let PhaseRemoveUseless take care of it.
1777 (!phase->is_IterGVN() ||
1778 // During IGVN, first wait for the dead branch to be killed.
1779 // Otherwise, the IfNode's control will have two control uses (the IfNode
1780 // that doesn't go away because it still has uses and this branch of the
1781 // If) which breaks other optimizations. Node::has_special_unique_user()
1782 // will cause this node to be reprocessed once the dead branch is killed.
1783 in(0)->outcnt() == 1))) {
1784 // IfNode control
1785 if (in(0)->is_BaseCountedLoopEnd()) {
1786 // CountedLoopEndNode may be eliminated by if subsuming, replace CountedLoopNode with LoopNode to
1787 // avoid mismatching between CountedLoopNode and CountedLoopEndNode in the following optimization.
1788 Node* head = unique_ctrl_out_or_null();
1789 if (head != nullptr && head->is_BaseCountedLoop() && head->in(LoopNode::LoopBackControl) == this) {
1790 Node* new_head = new LoopNode(head->in(LoopNode::EntryControl), this);
1791 phase->is_IterGVN()->register_new_node_with_optimizer(new_head);
1792 phase->is_IterGVN()->replace_node(head, new_head);
1793 }
1794 }
1795 return in(0)->in(0);
1796 }
1797 // no progress
1798 return this;
1799 }
1800
1801 bool IfNode::is_zero_trip_guard() const {
1802 if (in(1)->is_Bool() && in(1)->in(1)->is_Cmp()) {
1803 return in(1)->in(1)->in(1)->Opcode() == Op_OpaqueZeroTripGuard;
1804 }
1805 return false;
1806 }
1807
1808 void IfProjNode::pin_array_access_nodes(PhaseIterGVN* igvn) {
1809 for (DUIterator i = outs(); has_out(i); i++) {
1810 Node* u = out(i);
1811 if (!u->depends_only_on_test()) {
1812 continue;
1813 }
1814 Node* clone = u->pin_array_access_node();
1815 if (clone != nullptr) {
1816 clone = igvn->transform(clone);
1817 assert(clone != u, "shouldn't common");
1818 igvn->replace_node(u, clone);
1819 --i;
1820 }
1821 }
1822 }
1823
1824 #ifndef PRODUCT
1825 //------------------------------dump_spec--------------------------------------
1826 void IfNode::dump_spec(outputStream *st) const {
1827 st->print("P=%f, C=%f",_prob,_fcnt);
1828 }
1829 #endif
1830
1831 //------------------------------idealize_test----------------------------------
1832 // Try to canonicalize tests better. Peek at the Cmp/Bool/If sequence and
1833 // come up with a canonical sequence. Bools getting 'eq', 'gt' and 'ge' forms
1834 // converted to 'ne', 'le' and 'lt' forms. IfTrue/IfFalse get swapped as
1835 // needed.
1836 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff) {
1837 assert(iff->in(0) != nullptr, "If must be live");
1838
1839 if (iff->outcnt() != 2) return nullptr; // Malformed projections.
1840 Node* old_if_f = iff->proj_out(false);
1841 Node* old_if_t = iff->proj_out(true);
1842
1843 // CountedLoopEnds want the back-control test to be TRUE, regardless of
1844 // whether they are testing a 'gt' or 'lt' condition. The 'gt' condition
1845 // happens in count-down loops
1846 if (iff->is_BaseCountedLoopEnd()) return nullptr;
1847 if (!iff->in(1)->is_Bool()) return nullptr; // Happens for partially optimized IF tests
1848 BoolNode *b = iff->in(1)->as_Bool();
1849 BoolTest bt = b->_test;
1850 // Test already in good order?
1851 if( bt.is_canonical() )
1852 return nullptr;
1853
1854 // Flip test to be canonical. Requires flipping the IfFalse/IfTrue and
1855 // cloning the IfNode.
1856 Node* new_b = phase->transform( new BoolNode(b->in(1), bt.negate()) );
1857 if( !new_b->is_Bool() ) return nullptr;
1858 b = new_b->as_Bool();
1859
1860 PhaseIterGVN *igvn = phase->is_IterGVN();
1861 assert( igvn, "Test is not canonical in parser?" );
1862
1863 // The IF node never really changes, but it needs to be cloned
1864 iff = iff->clone()->as_If();
1865 iff->set_req(1, b);
1866 iff->_prob = 1.0-iff->_prob;
1867
1868 Node *prior = igvn->hash_find_insert(iff);
1869 if( prior ) {
1870 igvn->remove_dead_node(iff);
1871 iff = (IfNode*)prior;
1872 } else {
1873 // Cannot call transform on it just yet
1874 igvn->set_type_bottom(iff);
1875 }
1876 igvn->_worklist.push(iff);
1877
1878 // Now handle projections. Cloning not required.
1879 Node* new_if_f = (Node*)(new IfFalseNode( iff ));
1880 Node* new_if_t = (Node*)(new IfTrueNode ( iff ));
1881
1882 igvn->register_new_node_with_optimizer(new_if_f);
1883 igvn->register_new_node_with_optimizer(new_if_t);
1884 // Flip test, so flip trailing control
1885 igvn->replace_node(old_if_f, new_if_t);
1886 igvn->replace_node(old_if_t, new_if_f);
1887
1888 // Progress
1889 return iff;
1890 }
1891
1892 Node* RangeCheckNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1893 Node* res = Ideal_common(phase, can_reshape);
1894 if (res != NodeSentinel) {
1895 return res;
1896 }
1897
1898 PhaseIterGVN *igvn = phase->is_IterGVN();
1899 // Setup to scan up the CFG looking for a dominating test
1900 Node* prev_dom = this;
1901
1902 // Check for range-check vs other kinds of tests
1903 Node* index1;
1904 Node* range1;
1905 jint offset1;
1906 int flip1 = is_range_check(range1, index1, offset1);
1907 if (flip1) {
1908 Node* dom = in(0);
1909 // Try to remove extra range checks. All 'up_one_dom' gives up at merges
1910 // so all checks we inspect post-dominate the top-most check we find.
1911 // If we are going to fail the current check and we reach the top check
1912 // then we are guaranteed to fail, so just start interpreting there.
1913 // We 'expand' the top 3 range checks to include all post-dominating
1914 // checks.
1915 //
1916 // Example:
1917 // a[i+x] // (1) 1 < x < 6
1918 // a[i+3] // (2)
1919 // a[i+4] // (3)
1920 // a[i+6] // max = max of all constants
1921 // a[i+2]
1922 // a[i+1] // min = min of all constants
1923 //
1924 // If x < 3:
1925 // (1) a[i+x]: Leave unchanged
1926 // (2) a[i+3]: Replace with a[i+max] = a[i+6]: i+x < i+3 <= i+6 -> (2) is covered
1927 // (3) a[i+4]: Replace with a[i+min] = a[i+1]: i+1 < i+4 <= i+6 -> (3) and all following checks are covered
1928 // Remove all other a[i+c] checks
1929 //
1930 // If x >= 3:
1931 // (1) a[i+x]: Leave unchanged
1932 // (2) a[i+3]: Replace with a[i+min] = a[i+1]: i+1 < i+3 <= i+x -> (2) is covered
1933 // (3) a[i+4]: Replace with a[i+max] = a[i+6]: i+1 < i+4 <= i+6 -> (3) and all following checks are covered
1934 // Remove all other a[i+c] checks
1935 //
1936 // We only need the top 2 range checks if x is the min or max of all constants.
1937 //
1938 // This, however, only works if the interval [i+min,i+max] is not larger than max_int (i.e. abs(max - min) < max_int):
1939 // The theoretical max size of an array is max_int with:
1940 // - Valid index space: [0,max_int-1]
1941 // - Invalid index space: [max_int,-1] // max_int, min_int, min_int - 1 ..., -1
1942 //
1943 // The size of the consecutive valid index space is smaller than the size of the consecutive invalid index space.
1944 // If we choose min and max in such a way that:
1945 // - abs(max - min) < max_int
1946 // - i+max and i+min are inside the valid index space
1947 // then all indices [i+min,i+max] must be in the valid index space. Otherwise, the invalid index space must be
1948 // smaller than the valid index space which is never the case for any array size.
1949 //
1950 // Choosing a smaller array size only makes the valid index space smaller and the invalid index space larger and
1951 // the argument above still holds.
1952 //
1953 // Note that the same optimization with the same maximal accepted interval size can also be found in C1.
1954 const jlong maximum_number_of_min_max_interval_indices = (jlong)max_jint;
1955
1956 // The top 3 range checks seen
1957 const int NRC = 3;
1958 RangeCheck prev_checks[NRC];
1959 int nb_checks = 0;
1960
1961 // Low and high offsets seen so far
1962 jint off_lo = offset1;
1963 jint off_hi = offset1;
1964
1965 bool found_immediate_dominator = false;
1966
1967 // Scan for the top checks and collect range of offsets
1968 for (int dist = 0; dist < 999; dist++) { // Range-Check scan limit
1969 if (dom->Opcode() == Op_RangeCheck && // Not same opcode?
1970 prev_dom->in(0) == dom) { // One path of test does dominate?
1971 if (dom == this) return nullptr; // dead loop
1972 // See if this is a range check
1973 Node* index2;
1974 Node* range2;
1975 jint offset2;
1976 int flip2 = dom->as_RangeCheck()->is_range_check(range2, index2, offset2);
1977 // See if this is a _matching_ range check, checking against
1978 // the same array bounds.
1979 if (flip2 == flip1 && range2 == range1 && index2 == index1 &&
1980 dom->outcnt() == 2) {
1981 if (nb_checks == 0 && dom->in(1) == in(1)) {
1982 // Found an immediately dominating test at the same offset.
1983 // This kind of back-to-back test can be eliminated locally,
1984 // and there is no need to search further for dominating tests.
1985 assert(offset2 == offset1, "Same test but different offsets");
1986 found_immediate_dominator = true;
1987 break;
1988 }
1989
1990 // "x - y" -> must add one to the difference for number of elements in [x,y]
1991 const jlong diff = (jlong)MIN2(offset2, off_lo) - (jlong)MAX2(offset2, off_hi);
1992 if (ABS(diff) < maximum_number_of_min_max_interval_indices) {
1993 // Gather expanded bounds
1994 off_lo = MIN2(off_lo, offset2);
1995 off_hi = MAX2(off_hi, offset2);
1996 // Record top NRC range checks
1997 prev_checks[nb_checks % NRC].ctl = prev_dom->as_IfProj();
1998 prev_checks[nb_checks % NRC].off = offset2;
1999 nb_checks++;
2000 }
2001 }
2002 }
2003 prev_dom = dom;
2004 dom = up_one_dom(dom);
2005 if (!dom) break;
2006 }
2007
2008 if (!found_immediate_dominator) {
2009 // Attempt to widen the dominating range check to cover some later
2010 // ones. Since range checks "fail" by uncommon-trapping to the
2011 // interpreter, widening a check can make us speculatively enter
2012 // the interpreter. If we see range-check deopt's, do not widen!
2013 if (!phase->C->allow_range_check_smearing()) return nullptr;
2014
2015 if (can_reshape && !phase->C->post_loop_opts_phase()) {
2016 // We are about to perform range check smearing (i.e. remove this RangeCheck if it is dominated by
2017 // a series of RangeChecks which have a range that covers this RangeCheck). This can cause array access nodes to
2018 // be pinned. We want to avoid that and first allow range check elimination a chance to remove the RangeChecks
2019 // from loops. Hence, we delay range check smearing until after loop opts.
2020 phase->C->record_for_post_loop_opts_igvn(this);
2021 return nullptr;
2022 }
2023
2024 // Didn't find prior covering check, so cannot remove anything.
2025 if (nb_checks == 0) {
2026 return nullptr;
2027 }
2028 // Constant indices only need to check the upper bound.
2029 // Non-constant indices must check both low and high.
2030 int chk0 = (nb_checks - 1) % NRC;
2031 if (index1) {
2032 if (nb_checks == 1) {
2033 return nullptr;
2034 } else {
2035 // If the top range check's constant is the min or max of
2036 // all constants we widen the next one to cover the whole
2037 // range of constants.
2038 RangeCheck rc0 = prev_checks[chk0];
2039 int chk1 = (nb_checks - 2) % NRC;
2040 RangeCheck rc1 = prev_checks[chk1];
2041 if (rc0.off == off_lo) {
2042 adjust_check(rc1.ctl, range1, index1, flip1, off_hi, igvn);
2043 prev_dom = rc1.ctl;
2044 } else if (rc0.off == off_hi) {
2045 adjust_check(rc1.ctl, range1, index1, flip1, off_lo, igvn);
2046 prev_dom = rc1.ctl;
2047 } else {
2048 // If the top test's constant is not the min or max of all
2049 // constants, we need 3 range checks. We must leave the
2050 // top test unchanged because widening it would allow the
2051 // accesses it protects to successfully read/write out of
2052 // bounds.
2053 if (nb_checks == 2) {
2054 return nullptr;
2055 }
2056 int chk2 = (nb_checks - 3) % NRC;
2057 RangeCheck rc2 = prev_checks[chk2];
2058 // The top range check a+i covers interval: -a <= i < length-a
2059 // The second range check b+i covers interval: -b <= i < length-b
2060 if (rc1.off <= rc0.off) {
2061 // if b <= a, we change the second range check to:
2062 // -min_of_all_constants <= i < length-min_of_all_constants
2063 // Together top and second range checks now cover:
2064 // -min_of_all_constants <= i < length-a
2065 // which is more restrictive than -b <= i < length-b:
2066 // -b <= -min_of_all_constants <= i < length-a <= length-b
2067 // The third check is then changed to:
2068 // -max_of_all_constants <= i < length-max_of_all_constants
2069 // so 2nd and 3rd checks restrict allowed values of i to:
2070 // -min_of_all_constants <= i < length-max_of_all_constants
2071 adjust_check(rc1.ctl, range1, index1, flip1, off_lo, igvn);
2072 adjust_check(rc2.ctl, range1, index1, flip1, off_hi, igvn);
2073 } else {
2074 // if b > a, we change the second range check to:
2075 // -max_of_all_constants <= i < length-max_of_all_constants
2076 // Together top and second range checks now cover:
2077 // -a <= i < length-max_of_all_constants
2078 // which is more restrictive than -b <= i < length-b:
2079 // -b < -a <= i < length-max_of_all_constants <= length-b
2080 // The third check is then changed to:
2081 // -max_of_all_constants <= i < length-max_of_all_constants
2082 // so 2nd and 3rd checks restrict allowed values of i to:
2083 // -min_of_all_constants <= i < length-max_of_all_constants
2084 adjust_check(rc1.ctl, range1, index1, flip1, off_hi, igvn);
2085 adjust_check(rc2.ctl, range1, index1, flip1, off_lo, igvn);
2086 }
2087 prev_dom = rc2.ctl;
2088 }
2089 }
2090 } else {
2091 RangeCheck rc0 = prev_checks[chk0];
2092 // 'Widen' the offset of the 1st and only covering check
2093 adjust_check(rc0.ctl, range1, index1, flip1, off_hi, igvn);
2094 // Test is now covered by prior checks, dominate it out
2095 prev_dom = rc0.ctl;
2096 }
2097 // The last RangeCheck is found to be redundant with a sequence of n (n >= 2) preceding RangeChecks.
2098 // If an array load is control dependent on the eliminated range check, the array load nodes (CastII and Load)
2099 // become control dependent on the last range check of the sequence, but they are really dependent on the entire
2100 // sequence of RangeChecks. If RangeCheck#n is later replaced by a dominating identical check, the array load
2101 // nodes must not float above the n-1 other RangeCheck in the sequence. We pin the array load nodes here to
2102 // guarantee it doesn't happen.
2103 //
2104 // RangeCheck#1 RangeCheck#1
2105 // | \ | \
2106 // | uncommon trap | uncommon trap
2107 // .. ..
2108 // RangeCheck#n -> RangeCheck#n
2109 // | \ | \
2110 // | uncommon trap CastII uncommon trap
2111 // RangeCheck Load
2112 // | \
2113 // CastII uncommon trap
2114 // Load
2115
2116 return dominated_by(prev_dom, igvn, true);
2117 }
2118 } else {
2119 prev_dom = search_identical(4, igvn);
2120
2121 if (prev_dom == nullptr) {
2122 return nullptr;
2123 }
2124 }
2125
2126 // Replace dominated IfNode
2127 return dominated_by(prev_dom, igvn, false);
2128 }
2129
2130 ParsePredicateNode::ParsePredicateNode(Node* control, Deoptimization::DeoptReason deopt_reason, PhaseGVN* gvn)
2131 : IfNode(control, gvn->intcon(1), PROB_MAX, COUNT_UNKNOWN),
2132 _deopt_reason(deopt_reason),
2133 _useless(false) {
2134 init_class_id(Class_ParsePredicate);
2135 gvn->C->add_parse_predicate(this);
2136 gvn->C->record_for_post_loop_opts_igvn(this);
2137 #ifdef ASSERT
2138 switch (deopt_reason) {
2139 case Deoptimization::Reason_predicate:
2140 case Deoptimization::Reason_profile_predicate:
2141 case Deoptimization::Reason_loop_limit_check:
2142 break;
2143 default:
2144 assert(false, "unsupported deoptimization reason for Parse Predicate");
2145 }
2146 #endif // ASSERT
2147 }
2148
2149 Node* ParsePredicateNode::uncommon_trap() const {
2150 ParsePredicateUncommonProj* uncommon_proj = proj_out(0)->as_IfFalse();
2151 Node* uct_region_or_call = uncommon_proj->unique_ctrl_out();
2152 assert(uct_region_or_call->is_Region() || uct_region_or_call->is_Call(), "must be a region or call uct");
2153 return uct_region_or_call;
2154 }
2155
2156 // Fold this node away once it becomes useless or at latest in post loop opts IGVN.
2157 const Type* ParsePredicateNode::Value(PhaseGVN* phase) const {
2158 if (phase->type(in(0)) == Type::TOP) {
2159 return Type::TOP;
2160 }
2161 if (_useless || phase->C->post_loop_opts_phase()) {
2162 return TypeTuple::IFTRUE;
2163 } else {
2164 return bottom_type();
2165 }
2166 }
2167
2168 #ifndef PRODUCT
2169 void ParsePredicateNode::dump_spec(outputStream* st) const {
2170 st->print(" #");
2171 switch (_deopt_reason) {
2172 case Deoptimization::DeoptReason::Reason_predicate:
2173 st->print("Loop ");
2174 break;
2175 case Deoptimization::DeoptReason::Reason_profile_predicate:
2176 st->print("Profiled_Loop ");
2177 break;
2178 case Deoptimization::DeoptReason::Reason_loop_limit_check:
2179 st->print("Loop_Limit_Check ");
2180 break;
2181 default:
2182 fatal("unknown kind");
2183 }
2184 }
2185
2186 #endif // NOT PRODUCT