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/runtime.hpp"
36 #include "opto/rootnode.hpp"
37 #include "opto/subnode.hpp"
38
39 // Portions of code courtesy of Clifford Click
40
41 // Optimization - Graph Style
42
43
44 #ifndef PRODUCT
45 extern uint explicit_null_checks_elided;
46 #endif
47
48 //=============================================================================
49 //------------------------------Value------------------------------------------
50 // Return a tuple for whichever arm of the IF is reachable
51 const Type* IfNode::Value(PhaseGVN* phase) const {
52 if( !in(0) ) return Type::TOP;
53 if( phase->type(in(0)) == Type::TOP )
54 return Type::TOP;
55 const Type *t = phase->type(in(1));
56 if( t == Type::TOP ) // data is undefined
57 return TypeTuple::IFNEITHER; // unreachable altogether
58 if( t == TypeInt::ZERO ) // zero, or false
59 return TypeTuple::IFFALSE; // only false branch is reachable
60 if( t == TypeInt::ONE ) // 1, or true
61 return TypeTuple::IFTRUE; // only true branch is reachable
62 assert( t == TypeInt::BOOL, "expected boolean type" );
63
64 return TypeTuple::IFBOTH; // No progress
65 }
66
67 const RegMask &IfNode::out_RegMask() const {
68 return RegMask::Empty;
69 }
70
71 //------------------------------split_if---------------------------------------
72 // Look for places where we merge constants, then test on the merged value.
73 // If the IF test will be constant folded on the path with the constant, we
74 // win by splitting the IF to before the merge point.
75 static Node* split_if(IfNode *iff, PhaseIterGVN *igvn) {
76 // I could be a lot more general here, but I'm trying to squeeze this
77 // in before the Christmas '98 break so I'm gonna be kinda restrictive
78 // on the patterns I accept. CNC
79
80 // Look for a compare of a constant and a merged value
81 Node *i1 = iff->in(1);
82 if( !i1->is_Bool() ) return nullptr;
83 BoolNode *b = i1->as_Bool();
84 Node *cmp = b->in(1);
85 if( !cmp->is_Cmp() ) return nullptr;
86 i1 = cmp->in(1);
87 if( i1 == nullptr || !i1->is_Phi() ) return nullptr;
88 PhiNode *phi = i1->as_Phi();
89 Node *con2 = cmp->in(2);
90 if( !con2->is_Con() ) return nullptr;
91 // See that the merge point contains some constants
92 Node *con1=nullptr;
93 uint i4;
94 RegionNode* phi_region = phi->region();
95 for (i4 = 1; i4 < phi->req(); i4++ ) {
96 con1 = phi->in(i4);
97 // Do not optimize partially collapsed merges
98 if (con1 == nullptr || phi_region->in(i4) == nullptr || igvn->type(phi_region->in(i4)) == Type::TOP) {
99 igvn->_worklist.push(iff);
100 return nullptr;
101 }
102 if( con1->is_Con() ) break; // Found a constant
103 // Also allow null-vs-not-null checks
104 const TypePtr *tp = igvn->type(con1)->isa_ptr();
105 if( tp && tp->_ptr == TypePtr::NotNull )
106 break;
107 }
108 if( i4 >= phi->req() ) return nullptr; // Found no constants
109
110 igvn->C->set_has_split_ifs(true); // Has chance for split-if
111
112 // Make sure that the compare can be constant folded away
113 Node *cmp2 = cmp->clone();
114 cmp2->set_req(1,con1);
115 cmp2->set_req(2,con2);
116 const Type *t = cmp2->Value(igvn);
117 // This compare is dead, so whack it!
118 igvn->remove_dead_node(cmp2);
119 if( !t->singleton() ) return nullptr;
120
121 // No intervening control, like a simple Call
122 Node* r = iff->in(0);
123 if (!r->is_Region() || r->is_Loop() || phi_region != r || r->as_Region()->is_copy()) {
124 return nullptr;
125 }
126
127 // No other users of the cmp/bool
128 if (b->outcnt() != 1 || cmp->outcnt() != 1) {
129 //tty->print_cr("many users of cmp/bool");
130 return nullptr;
131 }
132
133 // Make sure we can determine where all the uses of merged values go
134 for (DUIterator_Fast jmax, j = r->fast_outs(jmax); j < jmax; j++) {
135 Node* u = r->fast_out(j);
136 if( u == r ) continue;
137 if( u == iff ) continue;
138 if( u->outcnt() == 0 ) continue; // use is dead & ignorable
139 if( !u->is_Phi() ) {
140 /*
141 if( u->is_Start() ) {
142 tty->print_cr("Region has inlined start use");
143 } else {
144 tty->print_cr("Region has odd use");
145 u->dump(2);
146 }*/
147 return nullptr;
148 }
149 if( u != phi ) {
150 // CNC - do not allow any other merged value
151 //tty->print_cr("Merging another value");
152 //u->dump(2);
153 return nullptr;
154 }
155 // Make sure we can account for all Phi uses
156 for (DUIterator_Fast kmax, k = u->fast_outs(kmax); k < kmax; k++) {
157 Node* v = u->fast_out(k); // User of the phi
158 // CNC - Allow only really simple patterns.
159 // In particular I disallow AddP of the Phi, a fairly common pattern
160 if (v == cmp) continue; // The compare is OK
161 if (v->is_ConstraintCast()) {
162 // If the cast is derived from data flow edges, it may not have a control edge.
163 // If so, it should be safe to split. But follow-up code can not deal with
164 // this (l. 359). So skip.
165 if (v->in(0) == nullptr) {
166 return nullptr;
167 }
168 if (v->in(0)->in(0) == iff) {
169 continue; // CastPP/II of the IfNode is OK
170 }
171 }
172 // Disabled following code because I cannot tell if exactly one
173 // path dominates without a real dominator check. CNC 9/9/1999
174 //uint vop = v->Opcode();
175 //if( vop == Op_Phi ) { // Phi from another merge point might be OK
176 // Node *r = v->in(0); // Get controlling point
177 // if( !r ) return nullptr; // Degraded to a copy
178 // // Find exactly one path in (either True or False doms, but not IFF)
179 // int cnt = 0;
180 // for( uint i = 1; i < r->req(); i++ )
181 // if( r->in(i) && r->in(i)->in(0) == iff )
182 // cnt++;
183 // if( cnt == 1 ) continue; // Exactly one of True or False guards Phi
184 //}
185 if( !v->is_Call() ) {
186 /*
187 if( v->Opcode() == Op_AddP ) {
188 tty->print_cr("Phi has AddP use");
189 } else if( v->Opcode() == Op_CastPP ) {
190 tty->print_cr("Phi has CastPP use");
191 } else if( v->Opcode() == Op_CastII ) {
192 tty->print_cr("Phi has CastII use");
193 } else {
194 tty->print_cr("Phi has use I can't be bothered with");
195 }
196 */
197 }
198 return nullptr;
199
200 /* CNC - Cut out all the fancy acceptance tests
201 // Can we clone this use when doing the transformation?
202 // If all uses are from Phis at this merge or constants, then YES.
203 if( !v->in(0) && v != cmp ) {
204 tty->print_cr("Phi has free-floating use");
205 v->dump(2);
206 return nullptr;
207 }
208 for( uint l = 1; l < v->req(); l++ ) {
209 if( (!v->in(l)->is_Phi() || v->in(l)->in(0) != r) &&
210 !v->in(l)->is_Con() ) {
211 tty->print_cr("Phi has use");
212 v->dump(2);
213 return nullptr;
214 } // End of if Phi-use input is neither Phi nor Constant
215 } // End of for all inputs to Phi-use
216 */
217 } // End of for all uses of Phi
218 } // End of for all uses of Region
219
220 // Only do this if the IF node is in a sane state
221 if (iff->outcnt() != 2)
222 return nullptr;
223
224 // Got a hit! Do the Mondo Hack!
225 //
226 //ABC a1c def ghi B 1 e h A C a c d f g i
227 // R - Phi - Phi - Phi Rc - Phi - Phi - Phi Rx - Phi - Phi - Phi
228 // cmp - 2 cmp - 2 cmp - 2
229 // bool bool_c bool_x
230 // if if_c if_x
231 // T F T F T F
232 // ..s.. ..t .. ..s.. ..t.. ..s.. ..t..
233 //
234 // Split the paths coming into the merge point into 2 separate groups of
235 // merges. On the left will be all the paths feeding constants into the
236 // Cmp's Phi. On the right will be the remaining paths. The Cmp's Phi
237 // will fold up into a constant; this will let the Cmp fold up as well as
238 // all the control flow. Below the original IF we have 2 control
239 // dependent regions, 's' and 't'. Now we will merge the two paths
240 // just prior to 's' and 't' from the two IFs. At least 1 path (and quite
241 // likely 2 or more) will promptly constant fold away.
242 PhaseGVN *phase = igvn;
243
244 // Make a region merging constants and a region merging the rest
245 uint req_c = 0;
246 for (uint ii = 1; ii < r->req(); ii++) {
247 if (phi->in(ii) == con1) {
248 req_c++;
249 }
250 if (Node::may_be_loop_entry(r->in(ii))) {
251 // Bail out if splitting through a region with a Parse Predicate input (could
252 // also be a loop header before loop opts creates a LoopNode for it).
253 return nullptr;
254 }
255 }
256
257 // If all the defs of the phi are the same constant, we already have the desired end state.
258 // Skip the split that would create empty phi and region nodes.
259 if ((r->req() - req_c) == 1) {
260 return nullptr;
261 }
262
263 // At this point we know that we can apply the split if optimization. If the region is still on the worklist,
264 // we should wait until it is processed. The region might be removed which makes this optimization redundant.
265 // This also avoids the creation of dead data loops when rewiring data nodes below when a region is dying.
266 if (igvn->_worklist.member(r)) {
267 igvn->_worklist.push(iff); // retry split if later again
268 return nullptr;
269 }
270
271 Node *region_c = new RegionNode(req_c + 1);
272 Node *phi_c = con1;
273 uint len = r->req();
274 Node *region_x = new RegionNode(len - req_c);
275 Node *phi_x = PhiNode::make_blank(region_x, phi);
276 for (uint i = 1, i_c = 1, i_x = 1; i < len; i++) {
277 if (phi->in(i) == con1) {
278 region_c->init_req( i_c++, r ->in(i) );
279 } else {
280 region_x->init_req( i_x, r ->in(i) );
281 phi_x ->init_req( i_x++, phi->in(i) );
282 }
283 }
284
285 // Register the new RegionNodes but do not transform them. Cannot
286 // transform until the entire Region/Phi conglomerate has been hacked
287 // as a single huge transform.
288 igvn->register_new_node_with_optimizer( region_c );
289 igvn->register_new_node_with_optimizer( region_x );
290 // Prevent the untimely death of phi_x. Currently he has no uses. He is
291 // about to get one. If this only use goes away, then phi_x will look dead.
292 // However, he will be picking up some more uses down below.
293 Node *hook = new Node(4);
294 hook->init_req(0, phi_x);
295 hook->init_req(1, phi_c);
296 phi_x = phase->transform( phi_x );
297
298 // Make the compare
299 Node *cmp_c = phase->makecon(t);
300 Node *cmp_x = cmp->clone();
301 cmp_x->set_req(1,phi_x);
302 cmp_x->set_req(2,con2);
303 cmp_x = phase->transform(cmp_x);
304 // Make the bool
305 Node *b_c = phase->transform(new BoolNode(cmp_c,b->_test._test));
306 Node *b_x = phase->transform(new BoolNode(cmp_x,b->_test._test));
307 // Make the IfNode
308 IfNode* iff_c = iff->clone()->as_If();
309 iff_c->set_req(0, region_c);
310 iff_c->set_req(1, b_c);
311 igvn->set_type_bottom(iff_c);
312 igvn->_worklist.push(iff_c);
313 hook->init_req(2, iff_c);
314
315 IfNode* iff_x = iff->clone()->as_If();
316 iff_x->set_req(0, region_x);
317 iff_x->set_req(1, b_x);
318 igvn->set_type_bottom(iff_x);
319 igvn->_worklist.push(iff_x);
320 hook->init_req(3, iff_x);
321
322 // Make the true/false arms
323 Node *iff_c_t = phase->transform(new IfTrueNode (iff_c));
324 Node *iff_c_f = phase->transform(new IfFalseNode(iff_c));
325 Node *iff_x_t = phase->transform(new IfTrueNode (iff_x));
326 Node *iff_x_f = phase->transform(new IfFalseNode(iff_x));
327
328 // Merge the TRUE paths
329 Node *region_s = new RegionNode(3);
330 igvn->_worklist.push(region_s);
331 region_s->init_req(1, iff_c_t);
332 region_s->init_req(2, iff_x_t);
333 igvn->register_new_node_with_optimizer( region_s );
334
335 // Merge the FALSE paths
336 Node *region_f = new RegionNode(3);
337 igvn->_worklist.push(region_f);
338 region_f->init_req(1, iff_c_f);
339 region_f->init_req(2, iff_x_f);
340 igvn->register_new_node_with_optimizer( region_f );
341
342 igvn->hash_delete(cmp);// Remove soon-to-be-dead node from hash table.
343 cmp->set_req(1,nullptr); // Whack the inputs to cmp because it will be dead
344 cmp->set_req(2,nullptr);
345 // Check for all uses of the Phi and give them a new home.
346 // The 'cmp' got cloned, but CastPP/IIs need to be moved.
347 Node *phi_s = nullptr; // do not construct unless needed
348 Node *phi_f = nullptr; // do not construct unless needed
349 for (DUIterator_Last i2min, i2 = phi->last_outs(i2min); i2 >= i2min; --i2) {
350 Node* v = phi->last_out(i2);// User of the phi
351 igvn->rehash_node_delayed(v); // Have to fixup other Phi users
352 uint vop = v->Opcode();
353 Node *proj = nullptr;
354 if( vop == Op_Phi ) { // Remote merge point
355 Node *r = v->in(0);
356 for (uint i3 = 1; i3 < r->req(); i3++)
357 if (r->in(i3) && r->in(i3)->in(0) == iff) {
358 proj = r->in(i3);
359 break;
360 }
361 } else if( v->is_ConstraintCast() ) {
362 proj = v->in(0); // Controlling projection
363 } else {
364 assert( 0, "do not know how to handle this guy" );
365 }
366 guarantee(proj != nullptr, "sanity");
367
368 Node *proj_path_data, *proj_path_ctrl;
369 if( proj->Opcode() == Op_IfTrue ) {
370 if( phi_s == nullptr ) {
371 // Only construct phi_s if needed, otherwise provides
372 // interfering use.
373 phi_s = PhiNode::make_blank(region_s,phi);
374 phi_s->init_req( 1, phi_c );
375 phi_s->init_req( 2, phi_x );
376 hook->add_req(phi_s);
377 phi_s = phase->transform(phi_s);
378 }
379 proj_path_data = phi_s;
380 proj_path_ctrl = region_s;
381 } else {
382 if( phi_f == nullptr ) {
383 // Only construct phi_f if needed, otherwise provides
384 // interfering use.
385 phi_f = PhiNode::make_blank(region_f,phi);
386 phi_f->init_req( 1, phi_c );
387 phi_f->init_req( 2, phi_x );
388 hook->add_req(phi_f);
389 phi_f = phase->transform(phi_f);
390 }
391 proj_path_data = phi_f;
392 proj_path_ctrl = region_f;
393 }
394
395 // Fixup 'v' for for the split
396 if( vop == Op_Phi ) { // Remote merge point
397 uint i;
398 for( i = 1; i < v->req(); i++ )
399 if( v->in(i) == phi )
400 break;
401 v->set_req(i, proj_path_data );
402 } else if( v->is_ConstraintCast() ) {
403 v->set_req(0, proj_path_ctrl );
404 v->set_req(1, proj_path_data );
405 } else
406 ShouldNotReachHere();
407 }
408
409 // Now replace the original iff's True/False with region_s/region_t.
410 // This makes the original iff go dead.
411 for (DUIterator_Last i3min, i3 = iff->last_outs(i3min); i3 >= i3min; --i3) {
412 Node* p = iff->last_out(i3);
413 assert( p->Opcode() == Op_IfTrue || p->Opcode() == Op_IfFalse, "" );
414 Node *u = (p->Opcode() == Op_IfTrue) ? region_s : region_f;
415 // Replace p with u
416 igvn->add_users_to_worklist(p);
417 for (DUIterator_Last lmin, l = p->last_outs(lmin); l >= lmin;) {
418 Node* x = p->last_out(l);
419 igvn->hash_delete(x);
420 uint uses_found = 0;
421 for( uint j = 0; j < x->req(); j++ ) {
422 if( x->in(j) == p ) {
423 x->set_req(j, u);
424 uses_found++;
425 }
426 }
427 l -= uses_found; // we deleted 1 or more copies of this edge
428 }
429 igvn->remove_dead_node(p);
430 }
431
432 // Force the original merge dead
433 igvn->hash_delete(r);
434 // First, remove region's dead users.
435 for (DUIterator_Last lmin, l = r->last_outs(lmin); l >= lmin;) {
436 Node* u = r->last_out(l);
437 if( u == r ) {
438 r->set_req(0, nullptr);
439 } else {
440 assert(u->outcnt() == 0, "only dead users");
441 igvn->remove_dead_node(u);
442 }
443 l -= 1;
444 }
445 igvn->remove_dead_node(r);
446
447 // Now remove the bogus extra edges used to keep things alive
448 igvn->remove_dead_node( hook );
449
450 // Must return either the original node (now dead) or a new node
451 // (Do not return a top here, since that would break the uniqueness of top.)
452 return new ConINode(TypeInt::ZERO);
453 }
454
455 // if this IfNode follows a range check pattern return the projection
456 // for the failed path
457 ProjNode* IfNode::range_check_trap_proj(int& flip_test, Node*& l, Node*& r) {
458 if (outcnt() != 2) {
459 return nullptr;
460 }
461 Node* b = in(1);
462 if (b == nullptr || !b->is_Bool()) return nullptr;
463 BoolNode* bn = b->as_Bool();
464 Node* cmp = bn->in(1);
465 if (cmp == nullptr) return nullptr;
466 if (cmp->Opcode() != Op_CmpU) return nullptr;
467
468 l = cmp->in(1);
469 r = cmp->in(2);
470 flip_test = 1;
471 if (bn->_test._test == BoolTest::le) {
472 l = cmp->in(2);
473 r = cmp->in(1);
474 flip_test = 2;
475 } else if (bn->_test._test != BoolTest::lt) {
476 return nullptr;
477 }
478 if (l->is_top()) return nullptr; // Top input means dead test
479 if (r->Opcode() != Op_LoadRange && !is_RangeCheck()) return nullptr;
480
481 // We have recognized one of these forms:
482 // Flip 1: If (Bool[<] CmpU(l, LoadRange)) ...
483 // Flip 2: If (Bool[<=] CmpU(LoadRange, l)) ...
484
485 ProjNode* iftrap = proj_out_or_null(flip_test == 2 ? true : false);
486 return iftrap;
487 }
488
489
490 //------------------------------is_range_check---------------------------------
491 // Return 0 if not a range check. Return 1 if a range check and set index and
492 // offset. Return 2 if we had to negate the test. Index is null if the check
493 // is versus a constant.
494 int RangeCheckNode::is_range_check(Node* &range, Node* &index, jint &offset) {
495 int flip_test = 0;
496 Node* l = nullptr;
497 Node* r = nullptr;
498 ProjNode* iftrap = range_check_trap_proj(flip_test, l, r);
499
500 if (iftrap == nullptr) {
501 return 0;
502 }
503
504 // Make sure it's a real range check by requiring an uncommon trap
505 // along the OOB path. Otherwise, it's possible that the user wrote
506 // something which optimized to look like a range check but behaves
507 // in some other way.
508 if (iftrap->is_uncommon_trap_proj(Deoptimization::Reason_range_check) == nullptr) {
509 return 0;
510 }
511
512 // Look for index+offset form
513 Node* ind = l;
514 jint off = 0;
515 if (l->is_top()) {
516 return 0;
517 } else if (l->Opcode() == Op_AddI) {
518 if ((off = l->in(1)->find_int_con(0)) != 0) {
519 ind = l->in(2)->uncast();
520 } else if ((off = l->in(2)->find_int_con(0)) != 0) {
521 ind = l->in(1)->uncast();
522 }
523 } else if ((off = l->find_int_con(-1)) >= 0) {
524 // constant offset with no variable index
525 ind = nullptr;
526 } else {
527 // variable index with no constant offset (or dead negative index)
528 off = 0;
529 }
530
531 // Return all the values:
532 index = ind;
533 offset = off;
534 range = r;
535 return flip_test;
536 }
537
538 //------------------------------adjust_check-----------------------------------
539 // Adjust (widen) a prior range check
540 static void adjust_check(Node* proj, Node* range, Node* index,
541 int flip, jint off_lo, PhaseIterGVN* igvn) {
542 PhaseGVN *gvn = igvn;
543 // Break apart the old check
544 Node *iff = proj->in(0);
545 Node *bol = iff->in(1);
546 if( bol->is_top() ) return; // In case a partially dead range check appears
547 // bail (or bomb[ASSERT/DEBUG]) if NOT projection-->IfNode-->BoolNode
548 DEBUG_ONLY( if( !bol->is_Bool() ) { proj->dump(3); fatal("Expect projection-->IfNode-->BoolNode"); } )
549 if( !bol->is_Bool() ) return;
550
551 Node *cmp = bol->in(1);
552 // Compute a new check
553 Node *new_add = gvn->intcon(off_lo);
554 if( index ) {
555 new_add = off_lo ? gvn->transform(new AddINode( index, new_add )) : index;
556 }
557 Node *new_cmp = (flip == 1)
558 ? new CmpUNode( new_add, range )
559 : new CmpUNode( range, new_add );
560 new_cmp = gvn->transform(new_cmp);
561 // See if no need to adjust the existing check
562 if( new_cmp == cmp ) return;
563 // Else, adjust existing check
564 Node *new_bol = gvn->transform( new BoolNode( new_cmp, bol->as_Bool()->_test._test ) );
565 igvn->rehash_node_delayed( iff );
566 iff->set_req_X( 1, new_bol, igvn );
567 }
568
569 //------------------------------up_one_dom-------------------------------------
570 // Walk up the dominator tree one step. Return null at root or true
571 // complex merges. Skips through small diamonds.
572 Node* IfNode::up_one_dom(Node *curr, bool linear_only) {
573 Node *dom = curr->in(0);
574 if( !dom ) // Found a Region degraded to a copy?
575 return curr->nonnull_req(); // Skip thru it
576
577 if( curr != dom ) // Normal walk up one step?
578 return dom;
579
580 // Use linear_only if we are still parsing, since we cannot
581 // trust the regions to be fully filled in.
582 if (linear_only)
583 return nullptr;
584
585 if( dom->is_Root() )
586 return nullptr;
587
588 // Else hit a Region. Check for a loop header
589 if( dom->is_Loop() )
590 return dom->in(1); // Skip up thru loops
591
592 // Check for small diamonds
593 Node *din1, *din2, *din3, *din4;
594 if( dom->req() == 3 && // 2-path merge point
595 (din1 = dom ->in(1)) && // Left path exists
596 (din2 = dom ->in(2)) && // Right path exists
597 (din3 = din1->in(0)) && // Left path up one
598 (din4 = din2->in(0)) ) { // Right path up one
599 if( din3->is_Call() && // Handle a slow-path call on either arm
600 (din3 = din3->in(0)) )
601 din3 = din3->in(0);
602 if( din4->is_Call() && // Handle a slow-path call on either arm
603 (din4 = din4->in(0)) )
604 din4 = din4->in(0);
605 if (din3 != nullptr && din3 == din4 && din3->is_If()) // Regions not degraded to a copy
606 return din3; // Skip around diamonds
607 }
608
609 // Give up the search at true merges
610 return nullptr; // Dead loop? Or hit root?
611 }
612
613
614 //------------------------------filtered_int_type--------------------------------
615 // Return a possibly more restrictive type for val based on condition control flow for an if
616 const TypeInt* IfNode::filtered_int_type(PhaseGVN* gvn, Node* val, Node* if_proj) {
617 assert(if_proj &&
618 (if_proj->Opcode() == Op_IfTrue || if_proj->Opcode() == Op_IfFalse), "expecting an if projection");
619 if (if_proj->in(0) && if_proj->in(0)->is_If()) {
620 IfNode* iff = if_proj->in(0)->as_If();
621 if (iff->in(1) && iff->in(1)->is_Bool()) {
622 BoolNode* bol = iff->in(1)->as_Bool();
623 if (bol->in(1) && bol->in(1)->is_Cmp()) {
624 const CmpNode* cmp = bol->in(1)->as_Cmp();
625 if (cmp->in(1) == val) {
626 const TypeInt* cmp2_t = gvn->type(cmp->in(2))->isa_int();
627 if (cmp2_t != nullptr) {
628 jint lo = cmp2_t->_lo;
629 jint hi = cmp2_t->_hi;
630 BoolTest::mask msk = if_proj->Opcode() == Op_IfTrue ? bol->_test._test : bol->_test.negate();
631 switch (msk) {
632 case BoolTest::ne: {
633 // If val is compared to its lower or upper bound, we can narrow the type
634 const TypeInt* val_t = gvn->type(val)->isa_int();
635 if (val_t != nullptr && !val_t->singleton() && cmp2_t->is_con()) {
636 if (val_t->_lo == lo) {
637 return TypeInt::make(val_t->_lo + 1, val_t->_hi, val_t->_widen);
638 } else if (val_t->_hi == hi) {
639 return TypeInt::make(val_t->_lo, val_t->_hi - 1, val_t->_widen);
640 }
641 }
642 // Can't refine type
643 return nullptr;
644 }
645 case BoolTest::eq:
646 return cmp2_t;
647 case BoolTest::lt:
648 lo = TypeInt::INT->_lo;
649 if (hi != min_jint) {
650 hi = hi - 1;
651 }
652 break;
653 case BoolTest::le:
654 lo = TypeInt::INT->_lo;
655 break;
656 case BoolTest::gt:
657 if (lo != max_jint) {
658 lo = lo + 1;
659 }
660 hi = TypeInt::INT->_hi;
661 break;
662 case BoolTest::ge:
663 // lo unchanged
664 hi = TypeInt::INT->_hi;
665 break;
666 default:
667 break;
668 }
669 const TypeInt* rtn_t = TypeInt::make(lo, hi, cmp2_t->_widen);
670 return rtn_t;
671 }
672 }
673 }
674 }
675 }
676 return nullptr;
677 }
678
679 //------------------------------fold_compares----------------------------
680 // See if a pair of CmpIs can be converted into a CmpU. In some cases
681 // the direction of this if is determined by the preceding if so it
682 // can be eliminate entirely.
683 //
684 // Given an if testing (CmpI n v) check for an immediately control
685 // dependent if that is testing (CmpI n v2) and has one projection
686 // leading to this if and the other projection leading to a region
687 // that merges one of this ifs control projections.
688 //
689 // If
690 // / |
691 // / |
692 // / |
693 // If |
694 // /\ |
695 // / \ |
696 // / \ |
697 // / Region
698 //
699 // Or given an if testing (CmpI n v) check for a dominating if that is
700 // testing (CmpI n v2), both having one projection leading to an
701 // uncommon trap. Allow Another independent guard in between to cover
702 // an explicit range check:
703 // if (index < 0 || index >= array.length) {
704 // which may need a null check to guard the LoadRange
705 //
706 // If
707 // / \
708 // / \
709 // / \
710 // If unc
711 // /\
712 // / \
713 // / \
714 // / unc
715 //
716
717 // Is the comparison for this If suitable for folding?
718 bool IfNode::cmpi_folds(PhaseIterGVN* igvn, bool fold_ne) {
719 return in(1) != nullptr &&
720 in(1)->is_Bool() &&
721 in(1)->in(1) != nullptr &&
722 in(1)->in(1)->Opcode() == Op_CmpI &&
723 in(1)->in(1)->in(2) != nullptr &&
724 in(1)->in(1)->in(2) != igvn->C->top() &&
725 (in(1)->as_Bool()->_test.is_less() ||
726 in(1)->as_Bool()->_test.is_greater() ||
727 (fold_ne && in(1)->as_Bool()->_test._test == BoolTest::ne));
728 }
729
730 // Is a dominating control suitable for folding with this if?
731 bool IfNode::is_ctrl_folds(Node* ctrl, PhaseIterGVN* igvn) {
732 return ctrl != nullptr &&
733 ctrl->is_Proj() &&
734 ctrl->in(0) != nullptr &&
735 ctrl->in(0)->Opcode() == Op_If &&
736 ctrl->in(0)->outcnt() == 2 &&
737 ctrl->in(0)->as_If()->cmpi_folds(igvn, true) &&
738 // Must compare same value
739 ctrl->in(0)->in(1)->in(1)->in(1) != nullptr &&
740 ctrl->in(0)->in(1)->in(1)->in(1) != igvn->C->top() &&
741 ctrl->in(0)->in(1)->in(1)->in(1) == in(1)->in(1)->in(1);
742 }
743
744 // Do this If and the dominating If share a region?
745 bool IfNode::has_shared_region(ProjNode* proj, ProjNode*& success, ProjNode*& fail) {
746 ProjNode* otherproj = proj->other_if_proj();
747 Node* otherproj_ctrl_use = otherproj->unique_ctrl_out_or_null();
748 RegionNode* region = (otherproj_ctrl_use != nullptr && otherproj_ctrl_use->is_Region()) ? otherproj_ctrl_use->as_Region() : nullptr;
749 success = nullptr;
750 fail = nullptr;
751
752 if (otherproj->outcnt() == 1 && region != nullptr && !region->has_phi()) {
753 for (int i = 0; i < 2; i++) {
754 ProjNode* proj = proj_out(i);
755 if (success == nullptr && proj->outcnt() == 1 && proj->unique_out() == region) {
756 success = proj;
757 } else if (fail == nullptr) {
758 fail = proj;
759 } else {
760 success = fail = nullptr;
761 }
762 }
763 }
764 return success != nullptr && fail != nullptr;
765 }
766
767 bool IfNode::is_dominator_unc(CallStaticJavaNode* dom_unc, CallStaticJavaNode* unc) {
768 // Different methods and methods containing jsrs are not supported.
769 ciMethod* method = unc->jvms()->method();
770 ciMethod* dom_method = dom_unc->jvms()->method();
771 if (method != dom_method || method->has_jsrs()) {
772 return false;
773 }
774 // Check that both traps are in the same activation of the method (instead
775 // of two activations being inlined through different call sites) by verifying
776 // that the call stacks are equal for both JVMStates.
777 JVMState* dom_caller = dom_unc->jvms()->caller();
778 JVMState* caller = unc->jvms()->caller();
779 if ((dom_caller == nullptr) != (caller == nullptr)) {
780 // The current method must either be inlined into both dom_caller and
781 // caller or must not be inlined at all (top method). Bail out otherwise.
782 return false;
783 } else if (dom_caller != nullptr && !dom_caller->same_calls_as(caller)) {
784 return false;
785 }
786 // Check that the bci of the dominating uncommon trap dominates the bci
787 // of the dominated uncommon trap. Otherwise we may not re-execute
788 // the dominated check after deoptimization from the merged uncommon trap.
789 ciTypeFlow* flow = dom_method->get_flow_analysis();
790 int bci = unc->jvms()->bci();
791 int dom_bci = dom_unc->jvms()->bci();
792 if (!flow->is_dominated_by(bci, dom_bci)) {
793 return false;
794 }
795
796 return true;
797 }
798
799 // Return projection that leads to an uncommon trap if any
800 ProjNode* IfNode::uncommon_trap_proj(CallStaticJavaNode*& call) const {
801 for (int i = 0; i < 2; i++) {
802 call = proj_out(i)->is_uncommon_trap_proj(Deoptimization::Reason_none);
803 if (call != nullptr) {
804 return proj_out(i);
805 }
806 }
807 return nullptr;
808 }
809
810 // Do this If and the dominating If both branch out to an uncommon trap
811 bool IfNode::has_only_uncommon_traps(ProjNode* proj, ProjNode*& success, ProjNode*& fail, PhaseIterGVN* igvn) {
812 ProjNode* otherproj = proj->other_if_proj();
813 CallStaticJavaNode* dom_unc = otherproj->is_uncommon_trap_proj(Deoptimization::Reason_none);
814
815 if (otherproj->outcnt() == 1 && dom_unc != nullptr) {
816 // We need to re-execute the folded Ifs after deoptimization from the merged traps
817 if (!dom_unc->jvms()->should_reexecute()) {
818 return false;
819 }
820
821 CallStaticJavaNode* unc = nullptr;
822 ProjNode* unc_proj = uncommon_trap_proj(unc);
823 if (unc_proj != nullptr && unc_proj->outcnt() == 1) {
824 if (dom_unc == unc) {
825 // Allow the uncommon trap to be shared through a region
826 RegionNode* r = unc->in(0)->as_Region();
827 if (r->outcnt() != 2 || r->req() != 3 || r->find_edge(otherproj) == -1 || r->find_edge(unc_proj) == -1) {
828 return false;
829 }
830 assert(r->has_phi() == nullptr, "simple region shouldn't have a phi");
831 } else if (dom_unc->in(0) != otherproj || unc->in(0) != unc_proj) {
832 return false;
833 }
834
835 if (!is_dominator_unc(dom_unc, unc)) {
836 return false;
837 }
838
839 // See merge_uncommon_traps: the reason of the uncommon trap
840 // will be changed and the state of the dominating If will be
841 // used. Checked that we didn't apply this transformation in a
842 // previous compilation and it didn't cause too many traps
843 ciMethod* dom_method = dom_unc->jvms()->method();
844 int dom_bci = dom_unc->jvms()->bci();
845 if (!igvn->C->too_many_traps(dom_method, dom_bci, Deoptimization::Reason_unstable_fused_if) &&
846 !igvn->C->too_many_traps(dom_method, dom_bci, Deoptimization::Reason_range_check) &&
847 // Return true if c2 manages to reconcile with UnstableIf optimization. See the comments for it.
848 igvn->C->remove_unstable_if_trap(dom_unc, true/*yield*/)) {
849 success = unc_proj;
850 fail = unc_proj->other_if_proj();
851 return true;
852 }
853 }
854 }
855 return false;
856 }
857
858 // Check that the 2 CmpI can be folded into as single CmpU and proceed with the folding
859 bool IfNode::fold_compares_helper(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn) {
860 Node* this_cmp = in(1)->in(1);
861 BoolNode* this_bool = in(1)->as_Bool();
862 IfNode* dom_iff = proj->in(0)->as_If();
863 BoolNode* dom_bool = dom_iff->in(1)->as_Bool();
864 Node* lo = dom_iff->in(1)->in(1)->in(2);
865 Node* hi = this_cmp->in(2);
866 Node* n = this_cmp->in(1);
867 ProjNode* otherproj = proj->other_if_proj();
868
869 const TypeInt* lo_type = IfNode::filtered_int_type(igvn, n, otherproj);
870 const TypeInt* hi_type = IfNode::filtered_int_type(igvn, n, success);
871
872 BoolTest::mask lo_test = dom_bool->_test._test;
873 BoolTest::mask hi_test = this_bool->_test._test;
874 BoolTest::mask cond = hi_test;
875
876 // convert:
877 //
878 // dom_bool = x {<,<=,>,>=} a
879 // / \
880 // proj = {True,False} / \ otherproj = {False,True}
881 // /
882 // this_bool = x {<,<=} b
883 // / \
884 // fail = {True,False} / \ success = {False,True}
885 // /
886 //
887 // (Second test guaranteed canonicalized, first one may not have
888 // been canonicalized yet)
889 //
890 // into:
891 //
892 // cond = (x - lo) {<u,<=u,>u,>=u} adjusted_lim
893 // / \
894 // fail / \ success
895 // /
896 //
897
898 // Figure out which of the two tests sets the upper bound and which
899 // sets the lower bound if any.
900 Node* adjusted_lim = nullptr;
901 if (lo_type != nullptr && hi_type != nullptr && hi_type->_lo > lo_type->_hi &&
902 hi_type->_hi == max_jint && lo_type->_lo == min_jint && lo_test != BoolTest::ne) {
903 assert((dom_bool->_test.is_less() && !proj->_con) ||
904 (dom_bool->_test.is_greater() && proj->_con), "incorrect test");
905
906 // this_bool = <
907 // dom_bool = >= (proj = True) or dom_bool = < (proj = False)
908 // x in [a, b[ on the fail (= True) projection, b > a-1 (because of hi_type->_lo > lo_type->_hi test above):
909 // lo = a, hi = b, adjusted_lim = b-a, cond = <u
910 // dom_bool = > (proj = True) or dom_bool = <= (proj = False)
911 // x in ]a, b[ on the fail (= True) projection, b > a:
912 // lo = a+1, hi = b, adjusted_lim = b-a-1, cond = <u
913 // this_bool = <=
914 // dom_bool = >= (proj = True) or dom_bool = < (proj = False)
915 // x in [a, b] on the fail (= True) projection, b+1 > a-1:
916 // lo = a, hi = b, adjusted_lim = b-a+1, cond = <u
917 // lo = a, hi = b, adjusted_lim = b-a, cond = <=u doesn't work because b = a - 1 is possible, then b-a = -1
918 // dom_bool = > (proj = True) or dom_bool = <= (proj = False)
919 // x in ]a, b] on the fail (= True) projection b+1 > a:
920 // lo = a+1, hi = b, adjusted_lim = b-a, cond = <u
921 // 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
922
923 if (hi_test == BoolTest::lt) {
924 if (lo_test == BoolTest::gt || lo_test == BoolTest::le) {
925 lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
926 }
927 } else if (hi_test == BoolTest::le) {
928 if (lo_test == BoolTest::ge || lo_test == BoolTest::lt) {
929 adjusted_lim = igvn->transform(new SubINode(hi, lo));
930 adjusted_lim = igvn->transform(new AddINode(adjusted_lim, igvn->intcon(1)));
931 cond = BoolTest::lt;
932 } else if (lo_test == BoolTest::gt || lo_test == BoolTest::le) {
933 adjusted_lim = igvn->transform(new SubINode(hi, lo));
934 lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
935 cond = BoolTest::lt;
936 } else {
937 assert(false, "unhandled lo_test: %d", lo_test);
938 return false;
939 }
940 } else {
941 assert(igvn->_worklist.member(in(1)) && in(1)->Value(igvn) != igvn->type(in(1)), "unhandled hi_test: %d", hi_test);
942 return false;
943 }
944 // this test was canonicalized
945 assert(this_bool->_test.is_less() && fail->_con, "incorrect test");
946 } else if (lo_type != nullptr && hi_type != nullptr && lo_type->_lo > hi_type->_hi &&
947 lo_type->_hi == max_jint && hi_type->_lo == min_jint && lo_test != BoolTest::ne) {
948
949 // this_bool = <
950 // dom_bool = < (proj = True) or dom_bool = >= (proj = False)
951 // x in [b, a[ on the fail (= False) projection, a > b-1 (because of lo_type->_lo > hi_type->_hi above):
952 // lo = b, hi = a, adjusted_lim = a-b, cond = >=u
953 // dom_bool = <= (proj = True) or dom_bool = > (proj = False)
954 // x in [b, a] on the fail (= False) projection, a+1 > b-1:
955 // lo = b, hi = a, adjusted_lim = a-b+1, cond = >=u
956 // lo = b, hi = a, adjusted_lim = a-b, cond = >u doesn't work because a = b - 1 is possible, then b-a = -1
957 // this_bool = <=
958 // dom_bool = < (proj = True) or dom_bool = >= (proj = False)
959 // x in ]b, a[ on the fail (= False) projection, a > b:
960 // lo = b+1, hi = a, adjusted_lim = a-b-1, cond = >=u
961 // dom_bool = <= (proj = True) or dom_bool = > (proj = False)
962 // x in ]b, a] on the fail (= False) projection, a+1 > b:
963 // lo = b+1, hi = a, adjusted_lim = a-b, cond = >=u
964 // 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
965
966 swap(lo, hi);
967 swap(lo_type, hi_type);
968 swap(lo_test, hi_test);
969
970 assert((dom_bool->_test.is_less() && proj->_con) ||
971 (dom_bool->_test.is_greater() && !proj->_con), "incorrect test");
972
973 cond = (hi_test == BoolTest::le || hi_test == BoolTest::gt) ? BoolTest::gt : BoolTest::ge;
974
975 if (lo_test == BoolTest::lt) {
976 if (hi_test == BoolTest::lt || hi_test == BoolTest::ge) {
977 cond = BoolTest::ge;
978 } else if (hi_test == BoolTest::le || hi_test == BoolTest::gt) {
979 adjusted_lim = igvn->transform(new SubINode(hi, lo));
980 adjusted_lim = igvn->transform(new AddINode(adjusted_lim, igvn->intcon(1)));
981 cond = BoolTest::ge;
982 } else {
983 assert(false, "unhandled hi_test: %d", hi_test);
984 return false;
985 }
986 } else if (lo_test == BoolTest::le) {
987 if (hi_test == BoolTest::lt || hi_test == BoolTest::ge) {
988 lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
989 cond = BoolTest::ge;
990 } else if (hi_test == BoolTest::le || hi_test == BoolTest::gt) {
991 adjusted_lim = igvn->transform(new SubINode(hi, lo));
992 lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
993 cond = BoolTest::ge;
994 } else {
995 assert(false, "unhandled hi_test: %d", hi_test);
996 return false;
997 }
998 } else {
999 assert(igvn->_worklist.member(in(1)) && in(1)->Value(igvn) != igvn->type(in(1)), "unhandled lo_test: %d", lo_test);
1000 return false;
1001 }
1002 // this test was canonicalized
1003 assert(this_bool->_test.is_less() && !fail->_con, "incorrect test");
1004 } else {
1005 const TypeInt* failtype = filtered_int_type(igvn, n, proj);
1006 if (failtype != nullptr) {
1007 const TypeInt* type2 = filtered_int_type(igvn, n, fail);
1008 if (type2 != nullptr) {
1009 failtype = failtype->join(type2)->is_int();
1010 if (failtype->_lo > failtype->_hi) {
1011 // previous if determines the result of this if so
1012 // replace Bool with constant
1013 igvn->replace_input_of(this, 1, igvn->intcon(success->_con));
1014 return true;
1015 }
1016 }
1017 }
1018 lo = nullptr;
1019 hi = nullptr;
1020 }
1021
1022 if (lo && hi) {
1023 Node* hook = new Node(1);
1024 hook->init_req(0, lo); // Add a use to lo to prevent him from dying
1025 // Merge the two compares into a single unsigned compare by building (CmpU (n - lo) (hi - lo))
1026 Node* adjusted_val = igvn->transform(new SubINode(n, lo));
1027 if (adjusted_lim == nullptr) {
1028 adjusted_lim = igvn->transform(new SubINode(hi, lo));
1029 }
1030 hook->destruct(igvn);
1031
1032 int lo = igvn->type(adjusted_lim)->is_int()->_lo;
1033 if (lo < 0) {
1034 // If range check elimination applies to this comparison, it includes code to protect from overflows that may
1035 // cause the main loop to be skipped entirely. Delay this transformation.
1036 // Example:
1037 // for (int i = 0; i < limit; i++) {
1038 // if (i < max_jint && i > min_jint) {...
1039 // }
1040 // Comparisons folded as:
1041 // i - min_jint - 1 <u -2
1042 // when RC applies, main loop limit becomes:
1043 // min(limit, max(-2 + min_jint + 1, min_jint))
1044 // = min(limit, min_jint)
1045 // = min_jint
1046 if (!igvn->C->post_loop_opts_phase()) {
1047 if (adjusted_val->outcnt() == 0) {
1048 igvn->remove_dead_node(adjusted_val);
1049 }
1050 if (adjusted_lim->outcnt() == 0) {
1051 igvn->remove_dead_node(adjusted_lim);
1052 }
1053 igvn->C->record_for_post_loop_opts_igvn(this);
1054 return false;
1055 }
1056 }
1057
1058 Node* newcmp = igvn->transform(new CmpUNode(adjusted_val, adjusted_lim));
1059 Node* newbool = igvn->transform(new BoolNode(newcmp, cond));
1060
1061 igvn->replace_input_of(dom_iff, 1, igvn->intcon(proj->_con));
1062 igvn->replace_input_of(this, 1, newbool);
1063
1064 return true;
1065 }
1066 return false;
1067 }
1068
1069 // Merge the branches that trap for this If and the dominating If into
1070 // a single region that branches to the uncommon trap for the
1071 // dominating If
1072 Node* IfNode::merge_uncommon_traps(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn) {
1073 Node* res = this;
1074 assert(success->in(0) == this, "bad projection");
1075
1076 ProjNode* otherproj = proj->other_if_proj();
1077
1078 CallStaticJavaNode* unc = success->is_uncommon_trap_proj(Deoptimization::Reason_none);
1079 CallStaticJavaNode* dom_unc = otherproj->is_uncommon_trap_proj(Deoptimization::Reason_none);
1080
1081 if (unc != dom_unc) {
1082 Node* r = new RegionNode(3);
1083
1084 r->set_req(1, otherproj);
1085 r->set_req(2, success);
1086 r = igvn->transform(r);
1087 assert(r->is_Region(), "can't go away");
1088
1089 // Make both If trap at the state of the first If: once the CmpI
1090 // nodes are merged, if we trap we don't know which of the CmpI
1091 // nodes would have caused the trap so we have to restart
1092 // execution at the first one
1093 igvn->replace_input_of(dom_unc, 0, r);
1094 igvn->replace_input_of(unc, 0, igvn->C->top());
1095 }
1096 int trap_request = dom_unc->uncommon_trap_request();
1097 Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(trap_request);
1098 Deoptimization::DeoptAction action = Deoptimization::trap_request_action(trap_request);
1099
1100 int flip_test = 0;
1101 Node* l = nullptr;
1102 Node* r = nullptr;
1103
1104 if (success->in(0)->as_If()->range_check_trap_proj(flip_test, l, r) != nullptr) {
1105 // If this looks like a range check, change the trap to
1106 // Reason_range_check so the compiler recognizes it as a range
1107 // check and applies the corresponding optimizations
1108 trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_range_check, action);
1109
1110 improve_address_types(l, r, fail, igvn);
1111
1112 res = igvn->transform(new RangeCheckNode(in(0), in(1), _prob, _fcnt));
1113 } else if (unc != dom_unc) {
1114 // If we trap we won't know what CmpI would have caused the trap
1115 // so use a special trap reason to mark this pair of CmpI nodes as
1116 // bad candidate for folding. On recompilation we won't fold them
1117 // and we may trap again but this time we'll know what branch
1118 // traps
1119 trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_unstable_fused_if, action);
1120 }
1121 igvn->replace_input_of(dom_unc, TypeFunc::Parms, igvn->intcon(trap_request));
1122 return res;
1123 }
1124
1125 // If we are turning 2 CmpI nodes into a CmpU that follows the pattern
1126 // of a rangecheck on index i, on 64 bit the compares may be followed
1127 // by memory accesses using i as index. In that case, the CmpU tells
1128 // us something about the values taken by i that can help the compiler
1129 // (see Compile::conv_I2X_index())
1130 void IfNode::improve_address_types(Node* l, Node* r, ProjNode* fail, PhaseIterGVN* igvn) {
1131 #ifdef _LP64
1132 ResourceMark rm;
1133 Node_Stack stack(2);
1134
1135 assert(r->Opcode() == Op_LoadRange, "unexpected range check");
1136 const TypeInt* array_size = igvn->type(r)->is_int();
1137
1138 stack.push(l, 0);
1139
1140 while(stack.size() > 0) {
1141 Node* n = stack.node();
1142 uint start = stack.index();
1143
1144 uint i = start;
1145 for (; i < n->outcnt(); i++) {
1146 Node* use = n->raw_out(i);
1147 if (stack.size() == 1) {
1148 if (use->Opcode() == Op_ConvI2L) {
1149 const TypeLong* bounds = use->as_Type()->type()->is_long();
1150 if (bounds->_lo <= array_size->_lo && bounds->_hi >= array_size->_hi &&
1151 (bounds->_lo != array_size->_lo || bounds->_hi != array_size->_hi)) {
1152 stack.set_index(i+1);
1153 stack.push(use, 0);
1154 break;
1155 }
1156 }
1157 } else if (use->is_Mem()) {
1158 Node* ctrl = use->in(0);
1159 for (int i = 0; i < 10 && ctrl != nullptr && ctrl != fail; i++) {
1160 ctrl = up_one_dom(ctrl);
1161 }
1162 if (ctrl == fail) {
1163 Node* init_n = stack.node_at(1);
1164 assert(init_n->Opcode() == Op_ConvI2L, "unexpected first node");
1165 // Create a new narrow ConvI2L node that is dependent on the range check
1166 Node* new_n = igvn->C->conv_I2X_index(igvn, l, array_size, fail);
1167
1168 // The type of the ConvI2L may be widen and so the new
1169 // ConvI2L may not be better than an existing ConvI2L
1170 if (new_n != init_n) {
1171 for (uint j = 2; j < stack.size(); j++) {
1172 Node* n = stack.node_at(j);
1173 Node* clone = n->clone();
1174 int rep = clone->replace_edge(init_n, new_n, igvn);
1175 assert(rep > 0, "can't find expected node?");
1176 clone = igvn->transform(clone);
1177 init_n = n;
1178 new_n = clone;
1179 }
1180 igvn->hash_delete(use);
1181 int rep = use->replace_edge(init_n, new_n, igvn);
1182 assert(rep > 0, "can't find expected node?");
1183 igvn->transform(use);
1184 if (init_n->outcnt() == 0) {
1185 igvn->_worklist.push(init_n);
1186 }
1187 }
1188 }
1189 } else if (use->in(0) == nullptr && (igvn->type(use)->isa_long() ||
1190 igvn->type(use)->isa_ptr())) {
1191 stack.set_index(i+1);
1192 stack.push(use, 0);
1193 break;
1194 }
1195 }
1196 if (i == n->outcnt()) {
1197 stack.pop();
1198 }
1199 }
1200 #endif
1201 }
1202
1203 bool IfNode::is_cmp_with_loadrange(ProjNode* proj) {
1204 if (in(1) != nullptr &&
1205 in(1)->in(1) != nullptr &&
1206 in(1)->in(1)->in(2) != nullptr) {
1207 Node* other = in(1)->in(1)->in(2);
1208 if (other->Opcode() == Op_LoadRange &&
1209 ((other->in(0) != nullptr && other->in(0) == proj) ||
1210 (other->in(0) == nullptr &&
1211 other->in(2) != nullptr &&
1212 other->in(2)->is_AddP() &&
1213 other->in(2)->in(1) != nullptr &&
1214 other->in(2)->in(1)->Opcode() == Op_CastPP &&
1215 other->in(2)->in(1)->in(0) == proj))) {
1216 return true;
1217 }
1218 }
1219 return false;
1220 }
1221
1222 bool IfNode::is_null_check(ProjNode* proj, PhaseIterGVN* igvn) {
1223 Node* other = in(1)->in(1)->in(2);
1224 if (other->in(MemNode::Address) != nullptr &&
1225 proj->in(0)->in(1) != nullptr &&
1226 proj->in(0)->in(1)->is_Bool() &&
1227 proj->in(0)->in(1)->in(1) != nullptr &&
1228 proj->in(0)->in(1)->in(1)->Opcode() == Op_CmpP &&
1229 proj->in(0)->in(1)->in(1)->in(2) != nullptr &&
1230 proj->in(0)->in(1)->in(1)->in(1) == other->in(MemNode::Address)->in(AddPNode::Address)->uncast() &&
1231 igvn->type(proj->in(0)->in(1)->in(1)->in(2)) == TypePtr::NULL_PTR) {
1232 return true;
1233 }
1234 return false;
1235 }
1236
1237 // Returns true if this IfNode belongs to a flat array check
1238 // and returns the corresponding array in the 'array' parameter.
1239 bool IfNode::is_flat_array_check(PhaseTransform* phase, Node** array) {
1240 Node* bol = in(1);
1241 if (!bol->is_Bool()) {
1242 return false;
1243 }
1244 Node* cmp = bol->in(1);
1245 if (cmp->isa_FlatArrayCheck()) {
1246 if (array != nullptr) {
1247 *array = cmp->in(FlatArrayCheckNode::ArrayOrKlass);
1248 }
1249 return true;
1250 }
1251 return false;
1252 }
1253
1254 // Check that the If that is in between the 2 integer comparisons has
1255 // no side effect
1256 bool IfNode::is_side_effect_free_test(ProjNode* proj, PhaseIterGVN* igvn) {
1257 if (proj == nullptr) {
1258 return false;
1259 }
1260 CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
1261 if (unc != nullptr && proj->outcnt() <= 2) {
1262 if (proj->outcnt() == 1 ||
1263 // Allow simple null check from LoadRange
1264 (is_cmp_with_loadrange(proj) && is_null_check(proj, igvn))) {
1265 CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
1266 CallStaticJavaNode* dom_unc = proj->in(0)->in(0)->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
1267 assert(dom_unc != nullptr, "is_uncommon_trap_if_pattern returned null");
1268
1269 // reroute_side_effect_free_unc changes the state of this
1270 // uncommon trap to restart execution at the previous
1271 // CmpI. Check that this change in a previous compilation didn't
1272 // cause too many traps.
1273 int trap_request = unc->uncommon_trap_request();
1274 Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(trap_request);
1275
1276 if (igvn->C->too_many_traps(dom_unc->jvms()->method(), dom_unc->jvms()->bci(), reason)) {
1277 return false;
1278 }
1279
1280 if (!is_dominator_unc(dom_unc, unc)) {
1281 return false;
1282 }
1283
1284 return true;
1285 }
1286 }
1287 return false;
1288 }
1289
1290 // Make the If between the 2 integer comparisons trap at the state of
1291 // the first If: the last CmpI is the one replaced by a CmpU and the
1292 // first CmpI is eliminated, so the test between the 2 CmpI nodes
1293 // won't be guarded by the first CmpI anymore. It can trap in cases
1294 // where the first CmpI would have prevented it from executing: on a
1295 // trap, we need to restart execution at the state of the first CmpI
1296 void IfNode::reroute_side_effect_free_unc(ProjNode* proj, ProjNode* dom_proj, PhaseIterGVN* igvn) {
1297 CallStaticJavaNode* dom_unc = dom_proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
1298 ProjNode* otherproj = proj->other_if_proj();
1299 CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
1300 Node* call_proj = dom_unc->unique_ctrl_out();
1301 Node* halt = call_proj->unique_ctrl_out();
1302
1303 Node* new_unc = dom_unc->clone();
1304 call_proj = call_proj->clone();
1305 halt = halt->clone();
1306 Node* c = otherproj->clone();
1307
1308 c = igvn->transform(c);
1309 new_unc->set_req(TypeFunc::Parms, unc->in(TypeFunc::Parms));
1310 new_unc->set_req(0, c);
1311 new_unc = igvn->transform(new_unc);
1312 call_proj->set_req(0, new_unc);
1313 call_proj = igvn->transform(call_proj);
1314 halt->set_req(0, call_proj);
1315 halt = igvn->transform(halt);
1316
1317 igvn->replace_node(otherproj, igvn->C->top());
1318 igvn->C->root()->add_req(halt);
1319 }
1320
1321 Node* IfNode::fold_compares(PhaseIterGVN* igvn) {
1322 if (Opcode() != Op_If) return nullptr;
1323
1324 if (cmpi_folds(igvn)) {
1325 Node* ctrl = in(0);
1326 if (is_ctrl_folds(ctrl, igvn) && ctrl->outcnt() == 1) {
1327 // A integer comparison immediately dominated by another integer
1328 // comparison
1329 ProjNode* success = nullptr;
1330 ProjNode* fail = nullptr;
1331 ProjNode* dom_cmp = ctrl->as_Proj();
1332 if (has_shared_region(dom_cmp, success, fail) &&
1333 // Next call modifies graph so must be last
1334 fold_compares_helper(dom_cmp, success, fail, igvn)) {
1335 return this;
1336 }
1337 if (has_only_uncommon_traps(dom_cmp, success, fail, igvn) &&
1338 // Next call modifies graph so must be last
1339 fold_compares_helper(dom_cmp, success, fail, igvn)) {
1340 return merge_uncommon_traps(dom_cmp, success, fail, igvn);
1341 }
1342 return nullptr;
1343 } else if (ctrl->in(0) != nullptr &&
1344 ctrl->in(0)->in(0) != nullptr) {
1345 ProjNode* success = nullptr;
1346 ProjNode* fail = nullptr;
1347 Node* dom = ctrl->in(0)->in(0);
1348 ProjNode* dom_cmp = dom->isa_Proj();
1349 ProjNode* other_cmp = ctrl->isa_Proj();
1350
1351 // Check if it's an integer comparison dominated by another
1352 // integer comparison with another test in between
1353 if (is_ctrl_folds(dom, igvn) &&
1354 has_only_uncommon_traps(dom_cmp, success, fail, igvn) &&
1355 is_side_effect_free_test(other_cmp, igvn) &&
1356 // Next call modifies graph so must be last
1357 fold_compares_helper(dom_cmp, success, fail, igvn)) {
1358 reroute_side_effect_free_unc(other_cmp, dom_cmp, igvn);
1359 return merge_uncommon_traps(dom_cmp, success, fail, igvn);
1360 }
1361 }
1362 }
1363 return nullptr;
1364 }
1365
1366 //------------------------------remove_useless_bool----------------------------
1367 // Check for people making a useless boolean: things like
1368 // if( (x < y ? true : false) ) { ... }
1369 // Replace with if( x < y ) { ... }
1370 static Node *remove_useless_bool(IfNode *iff, PhaseGVN *phase) {
1371 Node *i1 = iff->in(1);
1372 if( !i1->is_Bool() ) return nullptr;
1373 BoolNode *bol = i1->as_Bool();
1374
1375 Node *cmp = bol->in(1);
1376 if( cmp->Opcode() != Op_CmpI ) return nullptr;
1377
1378 // Must be comparing against a bool
1379 const Type *cmp2_t = phase->type( cmp->in(2) );
1380 if( cmp2_t != TypeInt::ZERO &&
1381 cmp2_t != TypeInt::ONE )
1382 return nullptr;
1383
1384 // Find a prior merge point merging the boolean
1385 i1 = cmp->in(1);
1386 if( !i1->is_Phi() ) return nullptr;
1387 PhiNode *phi = i1->as_Phi();
1388 if( phase->type( phi ) != TypeInt::BOOL )
1389 return nullptr;
1390
1391 // Check for diamond pattern
1392 int true_path = phi->is_diamond_phi();
1393 if( true_path == 0 ) return nullptr;
1394
1395 // Make sure that iff and the control of the phi are different. This
1396 // should really only happen for dead control flow since it requires
1397 // an illegal cycle.
1398 if (phi->in(0)->in(1)->in(0) == iff) return nullptr;
1399
1400 // phi->region->if_proj->ifnode->bool->cmp
1401 BoolNode *bol2 = phi->in(0)->in(1)->in(0)->in(1)->as_Bool();
1402
1403 // Now get the 'sense' of the test correct so we can plug in
1404 // either iff2->in(1) or its complement.
1405 int flip = 0;
1406 if( bol->_test._test == BoolTest::ne ) flip = 1-flip;
1407 else if( bol->_test._test != BoolTest::eq ) return nullptr;
1408 if( cmp2_t == TypeInt::ZERO ) flip = 1-flip;
1409
1410 const Type *phi1_t = phase->type( phi->in(1) );
1411 const Type *phi2_t = phase->type( phi->in(2) );
1412 // Check for Phi(0,1) and flip
1413 if( phi1_t == TypeInt::ZERO ) {
1414 if( phi2_t != TypeInt::ONE ) return nullptr;
1415 flip = 1-flip;
1416 } else {
1417 // Check for Phi(1,0)
1418 if( phi1_t != TypeInt::ONE ) return nullptr;
1419 if( phi2_t != TypeInt::ZERO ) return nullptr;
1420 }
1421 if( true_path == 2 ) {
1422 flip = 1-flip;
1423 }
1424
1425 Node* new_bol = (flip ? phase->transform( bol2->negate(phase) ) : bol2);
1426 assert(new_bol != iff->in(1), "must make progress");
1427 iff->set_req_X(1, new_bol, phase);
1428 // Intervening diamond probably goes dead
1429 phase->C->set_major_progress();
1430 return iff;
1431 }
1432
1433 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff);
1434
1435 struct RangeCheck {
1436 Node* ctl;
1437 jint off;
1438 };
1439
1440 Node* IfNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
1441 if (remove_dead_region(phase, can_reshape)) return this;
1442 // No Def-Use info?
1443 if (!can_reshape) return nullptr;
1444
1445 // Don't bother trying to transform a dead if
1446 if (in(0)->is_top()) return nullptr;
1447 // Don't bother trying to transform an if with a dead test
1448 if (in(1)->is_top()) return nullptr;
1449 // Another variation of a dead test
1450 if (in(1)->is_Con()) return nullptr;
1451 // Another variation of a dead if
1452 if (outcnt() < 2) return nullptr;
1453
1454 // Canonicalize the test.
1455 Node* idt_if = idealize_test(phase, this);
1456 if (idt_if != nullptr) return idt_if;
1457
1458 // Try to split the IF
1459 PhaseIterGVN *igvn = phase->is_IterGVN();
1460 Node *s = split_if(this, igvn);
1461 if (s != nullptr) return s;
1462
1463 return NodeSentinel;
1464 }
1465
1466 //------------------------------Ideal------------------------------------------
1467 // Return a node which is more "ideal" than the current node. Strip out
1468 // control copies
1469 Node* IfNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1470 Node* res = Ideal_common(phase, can_reshape);
1471 if (res != NodeSentinel) {
1472 return res;
1473 }
1474
1475 // Check for people making a useless boolean: things like
1476 // if( (x < y ? true : false) ) { ... }
1477 // Replace with if( x < y ) { ... }
1478 Node* bol2 = remove_useless_bool(this, phase);
1479 if (bol2) return bol2;
1480
1481 if (in(0) == nullptr) return nullptr; // Dead loop?
1482
1483 PhaseIterGVN* igvn = phase->is_IterGVN();
1484 Node* result = fold_compares(igvn);
1485 if (result != nullptr) {
1486 return result;
1487 }
1488
1489 // Scan for an equivalent test
1490 int dist = 4; // Cutoff limit for search
1491 if (is_If() && in(1)->is_Bool()) {
1492 Node* cmp = in(1)->in(1);
1493 if (cmp->Opcode() == Op_CmpP &&
1494 cmp->in(2) != nullptr && // make sure cmp is not already dead
1495 cmp->in(2)->bottom_type() == TypePtr::NULL_PTR) {
1496 dist = 64; // Limit for null-pointer scans
1497 }
1498 }
1499
1500 Node* prev_dom = search_identical(dist);
1501
1502 if (prev_dom != nullptr) {
1503 // Replace dominated IfNode
1504 return dominated_by(prev_dom, igvn);
1505 }
1506
1507 return simple_subsuming(igvn);
1508 }
1509
1510 //------------------------------dominated_by-----------------------------------
1511 Node* IfNode::dominated_by(Node* prev_dom, PhaseIterGVN *igvn) {
1512 #ifndef PRODUCT
1513 if (TraceIterativeGVN) {
1514 tty->print(" Removing IfNode: "); this->dump();
1515 }
1516 #endif
1517
1518 igvn->hash_delete(this); // Remove self to prevent spurious V-N
1519 Node *idom = in(0);
1520 // Need opcode to decide which way 'this' test goes
1521 int prev_op = prev_dom->Opcode();
1522 Node *top = igvn->C->top(); // Shortcut to top
1523
1524 // Loop predicates may have depending checks which should not
1525 // be skipped. For example, range check predicate has two checks
1526 // for lower and upper bounds.
1527 ProjNode* unc_proj = proj_out(1 - prev_dom->as_Proj()->_con)->as_Proj();
1528 if (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate) != nullptr ||
1529 unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_profile_predicate) != nullptr) {
1530 prev_dom = idom;
1531 }
1532
1533 // Now walk the current IfNode's projections.
1534 // Loop ends when 'this' has no more uses.
1535 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
1536 Node *ifp = last_out(i); // Get IfTrue/IfFalse
1537 igvn->add_users_to_worklist(ifp);
1538 // Check which projection it is and set target.
1539 // Data-target is either the dominating projection of the same type
1540 // or TOP if the dominating projection is of opposite type.
1541 // Data-target will be used as the new control edge for the non-CFG
1542 // nodes like Casts and Loads.
1543 Node *data_target = (ifp->Opcode() == prev_op) ? prev_dom : top;
1544 // Control-target is just the If's immediate dominator or TOP.
1545 Node *ctrl_target = (ifp->Opcode() == prev_op) ? idom : top;
1546
1547 // For each child of an IfTrue/IfFalse projection, reroute.
1548 // Loop ends when projection has no more uses.
1549 for (DUIterator_Last jmin, j = ifp->last_outs(jmin); j >= jmin; --j) {
1550 Node* s = ifp->last_out(j); // Get child of IfTrue/IfFalse
1551 if (s->depends_only_on_test() && igvn->no_dependent_zero_check(s)) {
1552 // For control producers.
1553 // Do not rewire Div and Mod nodes which could have a zero divisor to avoid skipping their zero check.
1554 igvn->replace_input_of(s, 0, data_target); // Move child to data-target
1555 } else {
1556 // Find the control input matching this def-use edge.
1557 // For Regions it may not be in slot 0.
1558 uint l;
1559 for (l = 0; s->in(l) != ifp; l++) { }
1560 igvn->replace_input_of(s, l, ctrl_target);
1561 }
1562 } // End for each child of a projection
1563
1564 igvn->remove_dead_node(ifp);
1565 } // End for each IfTrue/IfFalse child of If
1566
1567 // Kill the IfNode
1568 igvn->remove_dead_node(this);
1569
1570 // Must return either the original node (now dead) or a new node
1571 // (Do not return a top here, since that would break the uniqueness of top.)
1572 return new ConINode(TypeInt::ZERO);
1573 }
1574
1575 Node* IfNode::search_identical(int dist) {
1576 // Setup to scan up the CFG looking for a dominating test
1577 Node* dom = in(0);
1578 Node* prev_dom = this;
1579 int op = Opcode();
1580 // Search up the dominator tree for an If with an identical test
1581 while (dom->Opcode() != op || // Not same opcode?
1582 dom->in(1) != in(1) || // Not same input 1?
1583 prev_dom->in(0) != dom) { // One path of test does not dominate?
1584 if (dist < 0) return nullptr;
1585
1586 dist--;
1587 prev_dom = dom;
1588 dom = up_one_dom(dom);
1589 if (!dom) return nullptr;
1590 }
1591
1592 // Check that we did not follow a loop back to ourselves
1593 if (this == dom) {
1594 return nullptr;
1595 }
1596
1597 #ifndef PRODUCT
1598 if (dist > 2) { // Add to count of null checks elided
1599 explicit_null_checks_elided++;
1600 }
1601 #endif
1602
1603 return prev_dom;
1604 }
1605
1606
1607 static int subsuming_bool_test_encode(Node*);
1608
1609 // Check if dominating test is subsuming 'this' one.
1610 //
1611 // cmp
1612 // / \
1613 // (r1) bool \
1614 // / bool (r2)
1615 // (dom) if \
1616 // \ )
1617 // (pre) if[TF] /
1618 // \ /
1619 // if (this)
1620 // \r1
1621 // r2\ eqT eqF neT neF ltT ltF leT leF gtT gtF geT geF
1622 // eq t f f t f - - f f - - f
1623 // ne f t t f t - - t t - - t
1624 // lt f - - f t f - f f - f t
1625 // le t - - t t - t f f t - t
1626 // gt f - - f f - f t t f - f
1627 // ge t - - t f t - t t - t f
1628 //
1629 Node* IfNode::simple_subsuming(PhaseIterGVN* igvn) {
1630 // Table encoding: N/A (na), True-branch (tb), False-branch (fb).
1631 static enum { na, tb, fb } s_short_circuit_map[6][12] = {
1632 /*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*/
1633 /*eq*/{ tb, fb, fb, tb, fb, na, na, fb, fb, na, na, fb },
1634 /*ne*/{ fb, tb, tb, fb, tb, na, na, tb, tb, na, na, tb },
1635 /*lt*/{ fb, na, na, fb, tb, fb, na, fb, fb, na, fb, tb },
1636 /*le*/{ tb, na, na, tb, tb, na, tb, fb, fb, tb, na, tb },
1637 /*gt*/{ fb, na, na, fb, fb, na, fb, tb, tb, fb, na, fb },
1638 /*ge*/{ tb, na, na, tb, fb, tb, na, tb, tb, na, tb, fb }};
1639
1640 Node* pre = in(0);
1641 if (!pre->is_IfTrue() && !pre->is_IfFalse()) {
1642 return nullptr;
1643 }
1644 Node* dom = pre->in(0);
1645 if (!dom->is_If()) {
1646 return nullptr;
1647 }
1648 Node* bol = in(1);
1649 if (!bol->is_Bool()) {
1650 return nullptr;
1651 }
1652 Node* cmp = in(1)->in(1);
1653 if (!cmp->is_Cmp()) {
1654 return nullptr;
1655 }
1656
1657 if (!dom->in(1)->is_Bool()) {
1658 return nullptr;
1659 }
1660 if (dom->in(1)->in(1) != cmp) { // Not same cond?
1661 return nullptr;
1662 }
1663
1664 int drel = subsuming_bool_test_encode(dom->in(1));
1665 int trel = subsuming_bool_test_encode(bol);
1666 int bout = pre->is_IfFalse() ? 1 : 0;
1667
1668 if (drel < 0 || trel < 0) {
1669 return nullptr;
1670 }
1671 int br = s_short_circuit_map[trel][2*drel+bout];
1672 if (br == na) {
1673 return nullptr;
1674 }
1675 #ifndef PRODUCT
1676 if (TraceIterativeGVN) {
1677 tty->print(" Subsumed IfNode: "); dump();
1678 }
1679 #endif
1680 // Replace condition with constant True(1)/False(0).
1681 bool is_always_true = br == tb;
1682 set_req(1, igvn->intcon(is_always_true ? 1 : 0));
1683
1684 // Update any data dependencies to the directly dominating test. This subsumed test is not immediately removed by igvn
1685 // and therefore subsequent optimizations might miss these data dependencies otherwise. There might be a dead loop
1686 // ('always_taken_proj' == 'pre') that is cleaned up later. Skip this case to make the iterator work properly.
1687 Node* always_taken_proj = proj_out(is_always_true);
1688 if (always_taken_proj != pre) {
1689 for (DUIterator_Fast imax, i = always_taken_proj->fast_outs(imax); i < imax; i++) {
1690 Node* u = always_taken_proj->fast_out(i);
1691 if (!u->is_CFG()) {
1692 igvn->replace_input_of(u, 0, pre);
1693 --i;
1694 --imax;
1695 }
1696 }
1697 }
1698
1699 if (bol->outcnt() == 0) {
1700 igvn->remove_dead_node(bol); // Kill the BoolNode.
1701 }
1702 return this;
1703 }
1704
1705 // Map BoolTest to local table encoding. The BoolTest (e)numerals
1706 // { eq = 0, ne = 4, le = 5, ge = 7, lt = 3, gt = 1 }
1707 // are mapped to table indices, while the remaining (e)numerals in BoolTest
1708 // { overflow = 2, no_overflow = 6, never = 8, illegal = 9 }
1709 // are ignored (these are not modeled in the table).
1710 //
1711 static int subsuming_bool_test_encode(Node* node) {
1712 precond(node->is_Bool());
1713 BoolTest::mask x = node->as_Bool()->_test._test;
1714 switch (x) {
1715 case BoolTest::eq: return 0;
1716 case BoolTest::ne: return 1;
1717 case BoolTest::lt: return 2;
1718 case BoolTest::le: return 3;
1719 case BoolTest::gt: return 4;
1720 case BoolTest::ge: return 5;
1721 case BoolTest::overflow:
1722 case BoolTest::no_overflow:
1723 case BoolTest::never:
1724 case BoolTest::illegal:
1725 default:
1726 return -1;
1727 }
1728 }
1729
1730 //------------------------------Identity---------------------------------------
1731 // If the test is constant & we match, then we are the input Control
1732 Node* IfProjNode::Identity(PhaseGVN* phase) {
1733 // Can only optimize if cannot go the other way
1734 const TypeTuple *t = phase->type(in(0))->is_tuple();
1735 if (t == TypeTuple::IFNEITHER || (always_taken(t) &&
1736 // During parsing (GVN) we don't remove dead code aggressively.
1737 // Cut off dead branch and let PhaseRemoveUseless take care of it.
1738 (!phase->is_IterGVN() ||
1739 // During IGVN, first wait for the dead branch to be killed.
1740 // Otherwise, the IfNode's control will have two control uses (the IfNode
1741 // that doesn't go away because it still has uses and this branch of the
1742 // If) which breaks other optimizations. Node::has_special_unique_user()
1743 // will cause this node to be reprocessed once the dead branch is killed.
1744 in(0)->outcnt() == 1))) {
1745 // IfNode control
1746 if (in(0)->is_BaseCountedLoopEnd()) {
1747 // CountedLoopEndNode may be eliminated by if subsuming, replace CountedLoopNode with LoopNode to
1748 // avoid mismatching between CountedLoopNode and CountedLoopEndNode in the following optimization.
1749 Node* head = unique_ctrl_out_or_null();
1750 if (head != nullptr && head->is_BaseCountedLoop() && head->in(LoopNode::LoopBackControl) == this) {
1751 Node* new_head = new LoopNode(head->in(LoopNode::EntryControl), this);
1752 phase->is_IterGVN()->register_new_node_with_optimizer(new_head);
1753 phase->is_IterGVN()->replace_node(head, new_head);
1754 }
1755 }
1756 return in(0)->in(0);
1757 }
1758 // no progress
1759 return this;
1760 }
1761
1762 #ifndef PRODUCT
1763 //------------------------------dump_spec--------------------------------------
1764 void IfNode::dump_spec(outputStream *st) const {
1765 st->print("P=%f, C=%f",_prob,_fcnt);
1766 }
1767 #endif
1768
1769 //------------------------------idealize_test----------------------------------
1770 // Try to canonicalize tests better. Peek at the Cmp/Bool/If sequence and
1771 // come up with a canonical sequence. Bools getting 'eq', 'gt' and 'ge' forms
1772 // converted to 'ne', 'le' and 'lt' forms. IfTrue/IfFalse get swapped as
1773 // needed.
1774 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff) {
1775 assert(iff->in(0) != nullptr, "If must be live");
1776
1777 if (iff->outcnt() != 2) return nullptr; // Malformed projections.
1778 Node* old_if_f = iff->proj_out(false);
1779 Node* old_if_t = iff->proj_out(true);
1780
1781 // CountedLoopEnds want the back-control test to be TRUE, regardless of
1782 // whether they are testing a 'gt' or 'lt' condition. The 'gt' condition
1783 // happens in count-down loops
1784 if (iff->is_BaseCountedLoopEnd()) return nullptr;
1785 if (!iff->in(1)->is_Bool()) return nullptr; // Happens for partially optimized IF tests
1786 BoolNode *b = iff->in(1)->as_Bool();
1787 BoolTest bt = b->_test;
1788 // Test already in good order?
1789 if( bt.is_canonical() )
1790 return nullptr;
1791
1792 // Flip test to be canonical. Requires flipping the IfFalse/IfTrue and
1793 // cloning the IfNode.
1794 Node* new_b = phase->transform( new BoolNode(b->in(1), bt.negate()) );
1795 if( !new_b->is_Bool() ) return nullptr;
1796 b = new_b->as_Bool();
1797
1798 PhaseIterGVN *igvn = phase->is_IterGVN();
1799 assert( igvn, "Test is not canonical in parser?" );
1800
1801 // The IF node never really changes, but it needs to be cloned
1802 iff = iff->clone()->as_If();
1803 iff->set_req(1, b);
1804 iff->_prob = 1.0-iff->_prob;
1805
1806 Node *prior = igvn->hash_find_insert(iff);
1807 if( prior ) {
1808 igvn->remove_dead_node(iff);
1809 iff = (IfNode*)prior;
1810 } else {
1811 // Cannot call transform on it just yet
1812 igvn->set_type_bottom(iff);
1813 }
1814 igvn->_worklist.push(iff);
1815
1816 // Now handle projections. Cloning not required.
1817 Node* new_if_f = (Node*)(new IfFalseNode( iff ));
1818 Node* new_if_t = (Node*)(new IfTrueNode ( iff ));
1819
1820 igvn->register_new_node_with_optimizer(new_if_f);
1821 igvn->register_new_node_with_optimizer(new_if_t);
1822 // Flip test, so flip trailing control
1823 igvn->replace_node(old_if_f, new_if_t);
1824 igvn->replace_node(old_if_t, new_if_f);
1825
1826 // Progress
1827 return iff;
1828 }
1829
1830 Node* RangeCheckNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1831 Node* res = Ideal_common(phase, can_reshape);
1832 if (res != NodeSentinel) {
1833 return res;
1834 }
1835
1836 PhaseIterGVN *igvn = phase->is_IterGVN();
1837 // Setup to scan up the CFG looking for a dominating test
1838 Node* prev_dom = this;
1839
1840 // Check for range-check vs other kinds of tests
1841 Node* index1;
1842 Node* range1;
1843 jint offset1;
1844 int flip1 = is_range_check(range1, index1, offset1);
1845 if (flip1) {
1846 Node* dom = in(0);
1847 // Try to remove extra range checks. All 'up_one_dom' gives up at merges
1848 // so all checks we inspect post-dominate the top-most check we find.
1849 // If we are going to fail the current check and we reach the top check
1850 // then we are guaranteed to fail, so just start interpreting there.
1851 // We 'expand' the top 3 range checks to include all post-dominating
1852 // checks.
1853
1854 // The top 3 range checks seen
1855 const int NRC = 3;
1856 RangeCheck prev_checks[NRC];
1857 int nb_checks = 0;
1858
1859 // Low and high offsets seen so far
1860 jint off_lo = offset1;
1861 jint off_hi = offset1;
1862
1863 bool found_immediate_dominator = false;
1864
1865 // Scan for the top checks and collect range of offsets
1866 for (int dist = 0; dist < 999; dist++) { // Range-Check scan limit
1867 if (dom->Opcode() == Op_RangeCheck && // Not same opcode?
1868 prev_dom->in(0) == dom) { // One path of test does dominate?
1869 if (dom == this) return nullptr; // dead loop
1870 // See if this is a range check
1871 Node* index2;
1872 Node* range2;
1873 jint offset2;
1874 int flip2 = dom->as_RangeCheck()->is_range_check(range2, index2, offset2);
1875 // See if this is a _matching_ range check, checking against
1876 // the same array bounds.
1877 if (flip2 == flip1 && range2 == range1 && index2 == index1 &&
1878 dom->outcnt() == 2) {
1879 if (nb_checks == 0 && dom->in(1) == in(1)) {
1880 // Found an immediately dominating test at the same offset.
1881 // This kind of back-to-back test can be eliminated locally,
1882 // and there is no need to search further for dominating tests.
1883 assert(offset2 == offset1, "Same test but different offsets");
1884 found_immediate_dominator = true;
1885 break;
1886 }
1887 // Gather expanded bounds
1888 off_lo = MIN2(off_lo,offset2);
1889 off_hi = MAX2(off_hi,offset2);
1890 // Record top NRC range checks
1891 prev_checks[nb_checks%NRC].ctl = prev_dom;
1892 prev_checks[nb_checks%NRC].off = offset2;
1893 nb_checks++;
1894 }
1895 }
1896 prev_dom = dom;
1897 dom = up_one_dom(dom);
1898 if (!dom) break;
1899 }
1900
1901 if (!found_immediate_dominator) {
1902 // Attempt to widen the dominating range check to cover some later
1903 // ones. Since range checks "fail" by uncommon-trapping to the
1904 // interpreter, widening a check can make us speculatively enter
1905 // the interpreter. If we see range-check deopt's, do not widen!
1906 if (!phase->C->allow_range_check_smearing()) return nullptr;
1907
1908 // Didn't find prior covering check, so cannot remove anything.
1909 if (nb_checks == 0) {
1910 return nullptr;
1911 }
1912 // Constant indices only need to check the upper bound.
1913 // Non-constant indices must check both low and high.
1914 int chk0 = (nb_checks - 1) % NRC;
1915 if (index1) {
1916 if (nb_checks == 1) {
1917 return nullptr;
1918 } else {
1919 // If the top range check's constant is the min or max of
1920 // all constants we widen the next one to cover the whole
1921 // range of constants.
1922 RangeCheck rc0 = prev_checks[chk0];
1923 int chk1 = (nb_checks - 2) % NRC;
1924 RangeCheck rc1 = prev_checks[chk1];
1925 if (rc0.off == off_lo) {
1926 adjust_check(rc1.ctl, range1, index1, flip1, off_hi, igvn);
1927 prev_dom = rc1.ctl;
1928 } else if (rc0.off == off_hi) {
1929 adjust_check(rc1.ctl, range1, index1, flip1, off_lo, igvn);
1930 prev_dom = rc1.ctl;
1931 } else {
1932 // If the top test's constant is not the min or max of all
1933 // constants, we need 3 range checks. We must leave the
1934 // top test unchanged because widening it would allow the
1935 // accesses it protects to successfully read/write out of
1936 // bounds.
1937 if (nb_checks == 2) {
1938 return nullptr;
1939 }
1940 int chk2 = (nb_checks - 3) % NRC;
1941 RangeCheck rc2 = prev_checks[chk2];
1942 // The top range check a+i covers interval: -a <= i < length-a
1943 // The second range check b+i covers interval: -b <= i < length-b
1944 if (rc1.off <= rc0.off) {
1945 // if b <= a, we change the second range check to:
1946 // -min_of_all_constants <= i < length-min_of_all_constants
1947 // Together top and second range checks now cover:
1948 // -min_of_all_constants <= i < length-a
1949 // which is more restrictive than -b <= i < length-b:
1950 // -b <= -min_of_all_constants <= i < length-a <= length-b
1951 // The third check is then changed to:
1952 // -max_of_all_constants <= i < length-max_of_all_constants
1953 // so 2nd and 3rd checks restrict allowed values of i to:
1954 // -min_of_all_constants <= i < length-max_of_all_constants
1955 adjust_check(rc1.ctl, range1, index1, flip1, off_lo, igvn);
1956 adjust_check(rc2.ctl, range1, index1, flip1, off_hi, igvn);
1957 } else {
1958 // if b > a, we change the second range check to:
1959 // -max_of_all_constants <= i < length-max_of_all_constants
1960 // Together top and second range checks now cover:
1961 // -a <= i < length-max_of_all_constants
1962 // which is more restrictive than -b <= i < length-b:
1963 // -b < -a <= i < length-max_of_all_constants <= length-b
1964 // The third check is then changed to:
1965 // -max_of_all_constants <= i < length-max_of_all_constants
1966 // so 2nd and 3rd checks restrict allowed values of i to:
1967 // -min_of_all_constants <= i < length-max_of_all_constants
1968 adjust_check(rc1.ctl, range1, index1, flip1, off_hi, igvn);
1969 adjust_check(rc2.ctl, range1, index1, flip1, off_lo, igvn);
1970 }
1971 prev_dom = rc2.ctl;
1972 }
1973 }
1974 } else {
1975 RangeCheck rc0 = prev_checks[chk0];
1976 // 'Widen' the offset of the 1st and only covering check
1977 adjust_check(rc0.ctl, range1, index1, flip1, off_hi, igvn);
1978 // Test is now covered by prior checks, dominate it out
1979 prev_dom = rc0.ctl;
1980 }
1981 }
1982 } else {
1983 prev_dom = search_identical(4);
1984
1985 if (prev_dom == nullptr) {
1986 return nullptr;
1987 }
1988 }
1989
1990 // Replace dominated IfNode
1991 return dominated_by(prev_dom, igvn);
1992 }
1993
1994 ParsePredicateNode::ParsePredicateNode(Node* control, Node* bol, Deoptimization::DeoptReason deopt_reason)
1995 : IfNode(control, bol, PROB_MAX, COUNT_UNKNOWN),
1996 _deopt_reason(deopt_reason) {
1997 init_class_id(Class_ParsePredicate);
1998 assert(bol->Opcode() == Op_Conv2B && bol->in(1) != nullptr && bol->in(1)->is_Opaque1(), "wrong boolean input");
1999 #ifdef ASSERT
2000 switch (deopt_reason) {
2001 case Deoptimization::Reason_predicate:
2002 case Deoptimization::Reason_profile_predicate:
2003 case Deoptimization::Reason_loop_limit_check:
2004 break;
2005 default:
2006 assert(false, "unsupported deoptimization reason for Parse Predicate");
2007 }
2008 #endif // ASSERT
2009 }
2010
2011 #ifndef PRODUCT
2012 void ParsePredicateNode::dump_spec(outputStream* st) const {
2013 st->print(" #");
2014 switch (_deopt_reason) {
2015 case Deoptimization::DeoptReason::Reason_predicate:
2016 st->print("Loop ");
2017 break;
2018 case Deoptimization::DeoptReason::Reason_profile_predicate:
2019 st->print("Profiled_Loop ");
2020 break;
2021 case Deoptimization::DeoptReason::Reason_loop_limit_check:
2022 st->print("Loop_Limit_Check ");
2023 break;
2024 default:
2025 fatal("unknown kind");
2026 }
2027 }
2028 #endif // NOT PRODUCT