1 /*
2 * Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "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 #include "utilities/macros.hpp"
39 #if INCLUDE_SHENANDOAHGC
40 #include "gc/shenandoah/shenandoahHeap.hpp"
41 #include "gc/shenandoah/c2/shenandoahSupport.hpp"
42 #endif
43
44 // Portions of code courtesy of Clifford Click
45
46 // Optimization - Graph Style
47
48
49 #ifndef PRODUCT
50 extern int explicit_null_checks_elided;
51 #endif
52
53 //=============================================================================
54 //------------------------------Value------------------------------------------
55 // Return a tuple for whichever arm of the IF is reachable
56 const Type* IfNode::Value(PhaseGVN* phase) const {
57 if( !in(0) ) return Type::TOP;
58 if( phase->type(in(0)) == Type::TOP )
59 return Type::TOP;
60 const Type *t = phase->type(in(1));
61 if( t == Type::TOP ) // data is undefined
62 return TypeTuple::IFNEITHER; // unreachable altogether
63 if( t == TypeInt::ZERO ) // zero, or false
64 return TypeTuple::IFFALSE; // only false branch is reachable
65 if( t == TypeInt::ONE ) // 1, or true
66 return TypeTuple::IFTRUE; // only true branch is reachable
67 assert( t == TypeInt::BOOL, "expected boolean type" );
68
69 return TypeTuple::IFBOTH; // No progress
70 }
71
72 const RegMask &IfNode::out_RegMask() const {
73 return RegMask::Empty;
74 }
75
76 //------------------------------split_if---------------------------------------
77 // Look for places where we merge constants, then test on the merged value.
78 // If the IF test will be constant folded on the path with the constant, we
79 // win by splitting the IF to before the merge point.
80 static Node* split_if(IfNode *iff, PhaseIterGVN *igvn) {
81 // I could be a lot more general here, but I'm trying to squeeze this
82 // in before the Christmas '98 break so I'm gonna be kinda restrictive
83 // on the patterns I accept. CNC
84
85 // Look for a compare of a constant and a merged value
86 Node *i1 = iff->in(1);
87 if( !i1->is_Bool() ) return NULL;
88 BoolNode *b = i1->as_Bool();
89 Node *cmp = b->in(1);
90 if( !cmp->is_Cmp() ) return NULL;
91 i1 = cmp->in(1);
92 if( i1 == NULL || !i1->is_Phi() ) return NULL;
93 PhiNode *phi = i1->as_Phi();
94 if( phi->is_copy() ) return NULL;
95 Node *con2 = cmp->in(2);
96 if( !con2->is_Con() ) return NULL;
97 // See that the merge point contains some constants
98 Node *con1=NULL;
99 uint i4;
100 for( i4 = 1; i4 < phi->req(); i4++ ) {
101 con1 = phi->in(i4);
102 if( !con1 ) return NULL; // Do not optimize partially collapsed merges
103 if( con1->is_Con() ) break; // Found a constant
104 // Also allow null-vs-not-null checks
105 const TypePtr *tp = igvn->type(con1)->isa_ptr();
106 if( tp && tp->_ptr == TypePtr::NotNull )
107 break;
108 }
109 if( i4 >= phi->req() ) return NULL; // Found no constants
110
111 igvn->C->set_has_split_ifs(true); // Has chance for split-if
112
113 // Make sure that the compare can be constant folded away
114 Node *cmp2 = cmp->clone();
115 cmp2->set_req(1,con1);
116 cmp2->set_req(2,con2);
117 const Type *t = cmp2->Value(igvn);
118 // This compare is dead, so whack it!
119 igvn->remove_dead_node(cmp2);
120 if( !t->singleton() ) return NULL;
121
122 // No intervening control, like a simple Call
123 Node *r = iff->in(0);
124 if( !r->is_Region() ) return NULL;
125 if (r->is_Loop() && r->in(LoopNode::LoopBackControl)->is_top()) return NULL; // going away anyway
126 if( phi->region() != r ) return NULL;
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 NULL;
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 NULL;
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 NULL;
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) == NULL) {
166 return NULL;
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 NULL; // 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 cant be bothered with");
195 }
196 */
197 }
198 return NULL;
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 NULL;
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 NULL;
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 NULL;
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 Node* predicate_proj = NULL;
247 int nb_predicate_proj = 0;
248 for (uint ii = 1; ii < r->req(); ii++) {
249 if (phi->in(ii) == con1) {
250 req_c++;
251 }
252 Node* proj = PhaseIdealLoop::find_predicate(r->in(ii));
253 if (proj != NULL) {
254 nb_predicate_proj++;
255 predicate_proj = proj;
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 NULL;
263 }
264
265 if (nb_predicate_proj > 1) {
266 // Can happen in case of loop unswitching and when the loop is
267 // optimized out: it's not a loop anymore so we don't care about
268 // predicates.
269 assert(!r->is_Loop(), "this must not be a loop anymore");
270 predicate_proj = NULL;
271 }
272 Node* predicate_c = NULL;
273 Node* predicate_x = NULL;
274 bool counted_loop = r->is_CountedLoop();
275 if (counted_loop) {
276 // Ignore counted loops for now because the split-if logic does not work
277 // in all the cases (for example, with strip mined loops). Also, above
278 // checks only pass for already degraded loops without a tripcount phi
279 // and these are essentially dead and will go away during igvn.
280 return NULL;
281 }
282
283 Node *region_c = new RegionNode(req_c + 1);
284 Node *phi_c = con1;
285 uint len = r->req();
286 Node *region_x = new RegionNode(len - req_c);
287 Node *phi_x = PhiNode::make_blank(region_x, phi);
288 for (uint i = 1, i_c = 1, i_x = 1; i < len; i++) {
289 if (phi->in(i) == con1) {
290 region_c->init_req( i_c++, r ->in(i) );
291 if (r->in(i) == predicate_proj)
292 predicate_c = predicate_proj;
293 } else {
294 region_x->init_req( i_x, r ->in(i) );
295 phi_x ->init_req( i_x++, phi->in(i) );
296 if (r->in(i) == predicate_proj)
297 predicate_x = predicate_proj;
298 }
299 }
300 if (predicate_c != NULL && (req_c > 1)) {
301 assert(predicate_x == NULL, "only one predicate entry expected");
302 predicate_c = NULL; // Do not clone predicate below merge point
303 }
304 if (predicate_x != NULL && ((len - req_c) > 2)) {
305 assert(predicate_c == NULL, "only one predicate entry expected");
306 predicate_x = NULL; // Do not clone predicate below merge point
307 }
308
309 // Register the new RegionNodes but do not transform them. Cannot
310 // transform until the entire Region/Phi conglomerate has been hacked
311 // as a single huge transform.
312 igvn->register_new_node_with_optimizer( region_c );
313 igvn->register_new_node_with_optimizer( region_x );
314 // Prevent the untimely death of phi_x. Currently he has no uses. He is
315 // about to get one. If this only use goes away, then phi_x will look dead.
316 // However, he will be picking up some more uses down below.
317 Node *hook = new Node(4);
318 hook->init_req(0, phi_x);
319 hook->init_req(1, phi_c);
320 phi_x = phase->transform( phi_x );
321
322 // Make the compare
323 Node *cmp_c = phase->makecon(t);
324 Node *cmp_x = cmp->clone();
325 cmp_x->set_req(1,phi_x);
326 cmp_x->set_req(2,con2);
327 cmp_x = phase->transform(cmp_x);
328 // Make the bool
329 Node *b_c = phase->transform(new BoolNode(cmp_c,b->_test._test));
330 Node *b_x = phase->transform(new BoolNode(cmp_x,b->_test._test));
331 // Make the IfNode
332 IfNode* iff_c = iff->clone()->as_If();
333 iff_c->set_req(0, region_c);
334 iff_c->set_req(1, b_c);
335 igvn->set_type_bottom(iff_c);
336 igvn->_worklist.push(iff_c);
337 hook->init_req(2, iff_c);
338
339 IfNode* iff_x = iff->clone()->as_If();
340 iff_x->set_req(0, region_x);
341 iff_x->set_req(1, b_x);
342 igvn->set_type_bottom(iff_x);
343 igvn->_worklist.push(iff_x);
344 hook->init_req(3, iff_x);
345
346 // Make the true/false arms
347 Node *iff_c_t = phase->transform(new IfTrueNode (iff_c));
348 Node *iff_c_f = phase->transform(new IfFalseNode(iff_c));
349 if (predicate_c != NULL) {
350 assert(predicate_x == NULL, "only one predicate entry expected");
351 // Clone loop predicates to each path
352 iff_c_t = igvn->clone_loop_predicates(predicate_c, iff_c_t, !counted_loop);
353 iff_c_f = igvn->clone_loop_predicates(predicate_c, iff_c_f, !counted_loop);
354 }
355 Node *iff_x_t = phase->transform(new IfTrueNode (iff_x));
356 Node *iff_x_f = phase->transform(new IfFalseNode(iff_x));
357 if (predicate_x != NULL) {
358 assert(predicate_c == NULL, "only one predicate entry expected");
359 // Clone loop predicates to each path
360 iff_x_t = igvn->clone_loop_predicates(predicate_x, iff_x_t, !counted_loop);
361 iff_x_f = igvn->clone_loop_predicates(predicate_x, iff_x_f, !counted_loop);
362 }
363
364 // Merge the TRUE paths
365 Node *region_s = new RegionNode(3);
366 igvn->_worklist.push(region_s);
367 region_s->init_req(1, iff_c_t);
368 region_s->init_req(2, iff_x_t);
369 igvn->register_new_node_with_optimizer( region_s );
370
371 // Merge the FALSE paths
372 Node *region_f = new RegionNode(3);
373 igvn->_worklist.push(region_f);
374 region_f->init_req(1, iff_c_f);
375 region_f->init_req(2, iff_x_f);
376 igvn->register_new_node_with_optimizer( region_f );
377
378 igvn->hash_delete(cmp);// Remove soon-to-be-dead node from hash table.
379 cmp->set_req(1,NULL); // Whack the inputs to cmp because it will be dead
380 cmp->set_req(2,NULL);
381 // Check for all uses of the Phi and give them a new home.
382 // The 'cmp' got cloned, but CastPP/IIs need to be moved.
383 Node *phi_s = NULL; // do not construct unless needed
384 Node *phi_f = NULL; // do not construct unless needed
385 for (DUIterator_Last i2min, i2 = phi->last_outs(i2min); i2 >= i2min; --i2) {
386 Node* v = phi->last_out(i2);// User of the phi
387 igvn->rehash_node_delayed(v); // Have to fixup other Phi users
388 uint vop = v->Opcode();
389 Node *proj = NULL;
390 if( vop == Op_Phi ) { // Remote merge point
391 Node *r = v->in(0);
392 for (uint i3 = 1; i3 < r->req(); i3++)
393 if (r->in(i3) && r->in(i3)->in(0) == iff) {
394 proj = r->in(i3);
395 break;
396 }
397 } else if( v->is_ConstraintCast() ) {
398 proj = v->in(0); // Controlling projection
399 } else {
400 assert( 0, "do not know how to handle this guy" );
401 }
402 guarantee(proj != NULL, "sanity");
403
404 Node *proj_path_data, *proj_path_ctrl;
405 if( proj->Opcode() == Op_IfTrue ) {
406 if( phi_s == NULL ) {
407 // Only construct phi_s if needed, otherwise provides
408 // interfering use.
409 phi_s = PhiNode::make_blank(region_s,phi);
410 phi_s->init_req( 1, phi_c );
411 phi_s->init_req( 2, phi_x );
412 hook->add_req(phi_s);
413 phi_s = phase->transform(phi_s);
414 }
415 proj_path_data = phi_s;
416 proj_path_ctrl = region_s;
417 } else {
418 if( phi_f == NULL ) {
419 // Only construct phi_f if needed, otherwise provides
420 // interfering use.
421 phi_f = PhiNode::make_blank(region_f,phi);
422 phi_f->init_req( 1, phi_c );
423 phi_f->init_req( 2, phi_x );
424 hook->add_req(phi_f);
425 phi_f = phase->transform(phi_f);
426 }
427 proj_path_data = phi_f;
428 proj_path_ctrl = region_f;
429 }
430
431 // Fixup 'v' for for the split
432 if( vop == Op_Phi ) { // Remote merge point
433 uint i;
434 for( i = 1; i < v->req(); i++ )
435 if( v->in(i) == phi )
436 break;
437 v->set_req(i, proj_path_data );
438 } else if( v->is_ConstraintCast() ) {
439 v->set_req(0, proj_path_ctrl );
440 v->set_req(1, proj_path_data );
441 } else
442 ShouldNotReachHere();
443 }
444
445 // Now replace the original iff's True/False with region_s/region_t.
446 // This makes the original iff go dead.
447 for (DUIterator_Last i3min, i3 = iff->last_outs(i3min); i3 >= i3min; --i3) {
448 Node* p = iff->last_out(i3);
449 assert( p->Opcode() == Op_IfTrue || p->Opcode() == Op_IfFalse, "" );
450 Node *u = (p->Opcode() == Op_IfTrue) ? region_s : region_f;
451 // Replace p with u
452 igvn->add_users_to_worklist(p);
453 for (DUIterator_Last lmin, l = p->last_outs(lmin); l >= lmin;) {
454 Node* x = p->last_out(l);
455 igvn->hash_delete(x);
456 uint uses_found = 0;
457 for( uint j = 0; j < x->req(); j++ ) {
458 if( x->in(j) == p ) {
459 x->set_req(j, u);
460 uses_found++;
461 }
462 }
463 l -= uses_found; // we deleted 1 or more copies of this edge
464 }
465 igvn->remove_dead_node(p);
466 }
467
468 // Force the original merge dead
469 igvn->hash_delete(r);
470 // First, remove region's dead users.
471 for (DUIterator_Last lmin, l = r->last_outs(lmin); l >= lmin;) {
472 Node* u = r->last_out(l);
473 if( u == r ) {
474 r->set_req(0, NULL);
475 } else {
476 assert(u->outcnt() == 0, "only dead users");
477 igvn->remove_dead_node(u);
478 }
479 l -= 1;
480 }
481 igvn->remove_dead_node(r);
482
483 // Now remove the bogus extra edges used to keep things alive
484 igvn->remove_dead_node( hook );
485
486 // Must return either the original node (now dead) or a new node
487 // (Do not return a top here, since that would break the uniqueness of top.)
488 return new ConINode(TypeInt::ZERO);
489 }
490
491 // if this IfNode follows a range check pattern return the projection
492 // for the failed path
493 ProjNode* IfNode::range_check_trap_proj(int& flip_test, Node*& l, Node*& r) {
494 if (outcnt() != 2) {
495 return NULL;
496 }
497 Node* b = in(1);
498 if (b == NULL || !b->is_Bool()) return NULL;
499 BoolNode* bn = b->as_Bool();
500 Node* cmp = bn->in(1);
501 if (cmp == NULL) return NULL;
502 if (cmp->Opcode() != Op_CmpU) return NULL;
503
504 l = cmp->in(1);
505 r = cmp->in(2);
506 flip_test = 1;
507 if (bn->_test._test == BoolTest::le) {
508 l = cmp->in(2);
509 r = cmp->in(1);
510 flip_test = 2;
511 } else if (bn->_test._test != BoolTest::lt) {
512 return NULL;
513 }
514 if (l->is_top()) return NULL; // Top input means dead test
515 if (r->Opcode() != Op_LoadRange && !is_RangeCheck()) return NULL;
516
517 // We have recognized one of these forms:
518 // Flip 1: If (Bool[<] CmpU(l, LoadRange)) ...
519 // Flip 2: If (Bool[<=] CmpU(LoadRange, l)) ...
520
521 ProjNode* iftrap = proj_out_or_null(flip_test == 2 ? true : false);
522 return iftrap;
523 }
524
525
526 //------------------------------is_range_check---------------------------------
527 // Return 0 if not a range check. Return 1 if a range check and set index and
528 // offset. Return 2 if we had to negate the test. Index is NULL if the check
529 // is versus a constant.
530 int RangeCheckNode::is_range_check(Node* &range, Node* &index, jint &offset) {
531 int flip_test = 0;
532 Node* l = NULL;
533 Node* r = NULL;
534 ProjNode* iftrap = range_check_trap_proj(flip_test, l, r);
535
536 if (iftrap == NULL) {
537 return 0;
538 }
539
540 // Make sure it's a real range check by requiring an uncommon trap
541 // along the OOB path. Otherwise, it's possible that the user wrote
542 // something which optimized to look like a range check but behaves
543 // in some other way.
544 if (iftrap->is_uncommon_trap_proj(Deoptimization::Reason_range_check) == NULL) {
545 return 0;
546 }
547
548 // Look for index+offset form
549 Node* ind = l;
550 jint off = 0;
551 if (l->is_top()) {
552 return 0;
553 } else if (l->Opcode() == Op_AddI) {
554 if ((off = l->in(1)->find_int_con(0)) != 0) {
555 ind = l->in(2)->uncast();
556 } else if ((off = l->in(2)->find_int_con(0)) != 0) {
557 ind = l->in(1)->uncast();
558 }
559 } else if ((off = l->find_int_con(-1)) >= 0) {
560 // constant offset with no variable index
561 ind = NULL;
562 } else {
563 // variable index with no constant offset (or dead negative index)
564 off = 0;
565 }
566
567 // Return all the values:
568 index = ind;
569 offset = off;
570 range = r;
571 return flip_test;
572 }
573
574 //------------------------------adjust_check-----------------------------------
575 // Adjust (widen) a prior range check
576 static void adjust_check(Node* proj, Node* range, Node* index,
577 int flip, jint off_lo, PhaseIterGVN* igvn) {
578 PhaseGVN *gvn = igvn;
579 // Break apart the old check
580 Node *iff = proj->in(0);
581 Node *bol = iff->in(1);
582 if( bol->is_top() ) return; // In case a partially dead range check appears
583 // bail (or bomb[ASSERT/DEBUG]) if NOT projection-->IfNode-->BoolNode
584 DEBUG_ONLY( if( !bol->is_Bool() ) { proj->dump(3); fatal("Expect projection-->IfNode-->BoolNode"); } )
585 if( !bol->is_Bool() ) return;
586
587 Node *cmp = bol->in(1);
588 // Compute a new check
589 Node *new_add = gvn->intcon(off_lo);
590 if( index ) {
591 new_add = off_lo ? gvn->transform(new AddINode( index, new_add )) : index;
592 }
593 Node *new_cmp = (flip == 1)
594 ? new CmpUNode( new_add, range )
595 : new CmpUNode( range, new_add );
596 new_cmp = gvn->transform(new_cmp);
597 // See if no need to adjust the existing check
598 if( new_cmp == cmp ) return;
599 // Else, adjust existing check
600 Node *new_bol = gvn->transform( new BoolNode( new_cmp, bol->as_Bool()->_test._test ) );
601 igvn->rehash_node_delayed( iff );
602 iff->set_req_X( 1, new_bol, igvn );
603 }
604
605 //------------------------------up_one_dom-------------------------------------
606 // Walk up the dominator tree one step. Return NULL at root or true
607 // complex merges. Skips through small diamonds.
608 Node* IfNode::up_one_dom(Node *curr, bool linear_only) {
609 Node *dom = curr->in(0);
610 if( !dom ) // Found a Region degraded to a copy?
611 return curr->nonnull_req(); // Skip thru it
612
613 if( curr != dom ) // Normal walk up one step?
614 return dom;
615
616 // Use linear_only if we are still parsing, since we cannot
617 // trust the regions to be fully filled in.
618 if (linear_only)
619 return NULL;
620
621 if( dom->is_Root() )
622 return NULL;
623
624 // Else hit a Region. Check for a loop header
625 if( dom->is_Loop() )
626 return dom->in(1); // Skip up thru loops
627
628 // Check for small diamonds
629 Node *din1, *din2, *din3, *din4;
630 if( dom->req() == 3 && // 2-path merge point
631 (din1 = dom ->in(1)) && // Left path exists
632 (din2 = dom ->in(2)) && // Right path exists
633 (din3 = din1->in(0)) && // Left path up one
634 (din4 = din2->in(0)) ) { // Right path up one
635 if( din3->is_Call() && // Handle a slow-path call on either arm
636 (din3 = din3->in(0)) )
637 din3 = din3->in(0);
638 if( din4->is_Call() && // Handle a slow-path call on either arm
639 (din4 = din4->in(0)) )
640 din4 = din4->in(0);
641 if( din3 == din4 && din3->is_If() )
642 return din3; // Skip around diamonds
643 }
644
645 // Give up the search at true merges
646 return NULL; // Dead loop? Or hit root?
647 }
648
649
650 //------------------------------filtered_int_type--------------------------------
651 // Return a possibly more restrictive type for val based on condition control flow for an if
652 const TypeInt* IfNode::filtered_int_type(PhaseGVN* gvn, Node *val, Node* if_proj) {
653 assert(if_proj &&
654 (if_proj->Opcode() == Op_IfTrue || if_proj->Opcode() == Op_IfFalse), "expecting an if projection");
655 if (if_proj->in(0) && if_proj->in(0)->is_If()) {
656 IfNode* iff = if_proj->in(0)->as_If();
657 if (iff->in(1) && iff->in(1)->is_Bool()) {
658 BoolNode* bol = iff->in(1)->as_Bool();
659 if (bol->in(1) && bol->in(1)->is_Cmp()) {
660 const CmpNode* cmp = bol->in(1)->as_Cmp();
661 if (cmp->in(1) == val) {
662 const TypeInt* cmp2_t = gvn->type(cmp->in(2))->isa_int();
663 if (cmp2_t != NULL) {
664 jint lo = cmp2_t->_lo;
665 jint hi = cmp2_t->_hi;
666 BoolTest::mask msk = if_proj->Opcode() == Op_IfTrue ? bol->_test._test : bol->_test.negate();
667 switch (msk) {
668 case BoolTest::ne:
669 // Can't refine type
670 return NULL;
671 case BoolTest::eq:
672 return cmp2_t;
673 case BoolTest::lt:
674 lo = TypeInt::INT->_lo;
675 if (hi - 1 < hi) {
676 hi = hi - 1;
677 }
678 break;
679 case BoolTest::le:
680 lo = TypeInt::INT->_lo;
681 break;
682 case BoolTest::gt:
683 if (lo + 1 > lo) {
684 lo = lo + 1;
685 }
686 hi = TypeInt::INT->_hi;
687 break;
688 case BoolTest::ge:
689 // lo unchanged
690 hi = TypeInt::INT->_hi;
691 break;
692 default:
693 break;
694 }
695 const TypeInt* rtn_t = TypeInt::make(lo, hi, cmp2_t->_widen);
696 return rtn_t;
697 }
698 }
699 }
700 }
701 }
702 return NULL;
703 }
704
705 //------------------------------fold_compares----------------------------
706 // See if a pair of CmpIs can be converted into a CmpU. In some cases
707 // the direction of this if is determined by the preceding if so it
708 // can be eliminate entirely.
709 //
710 // Given an if testing (CmpI n v) check for an immediately control
711 // dependent if that is testing (CmpI n v2) and has one projection
712 // leading to this if and the other projection leading to a region
713 // that merges one of this ifs control projections.
714 //
715 // If
716 // / |
717 // / |
718 // / |
719 // If |
720 // /\ |
721 // / \ |
722 // / \ |
723 // / Region
724 //
725 // Or given an if testing (CmpI n v) check for a dominating if that is
726 // testing (CmpI n v2), both having one projection leading to an
727 // uncommon trap. Allow Another independent guard in between to cover
728 // an explicit range check:
729 // if (index < 0 || index >= array.length) {
730 // which may need a null check to guard the LoadRange
731 //
732 // If
733 // / \
734 // / \
735 // / \
736 // If unc
737 // /\
738 // / \
739 // / \
740 // / unc
741 //
742
743 // Is the comparison for this If suitable for folding?
744 bool IfNode::cmpi_folds(PhaseIterGVN* igvn) {
745 return in(1) != NULL &&
746 in(1)->is_Bool() &&
747 in(1)->in(1) != NULL &&
748 in(1)->in(1)->Opcode() == Op_CmpI &&
749 in(1)->in(1)->in(2) != NULL &&
750 in(1)->in(1)->in(2) != igvn->C->top() &&
751 (in(1)->as_Bool()->_test.is_less() ||
752 in(1)->as_Bool()->_test.is_greater());
753 }
754
755 // Is a dominating control suitable for folding with this if?
756 bool IfNode::is_ctrl_folds(Node* ctrl, PhaseIterGVN* igvn) {
757 return ctrl != NULL &&
758 ctrl->is_Proj() &&
759 ctrl->in(0) != NULL &&
760 ctrl->in(0)->Opcode() == Op_If &&
761 ctrl->in(0)->outcnt() == 2 &&
762 ctrl->in(0)->as_If()->cmpi_folds(igvn) &&
763 // Must compare same value
764 ctrl->in(0)->in(1)->in(1)->in(1) != NULL &&
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();
772 RegionNode* region = (otherproj_ctrl_use != NULL && otherproj_ctrl_use->is_Region()) ? otherproj_ctrl_use->as_Region() : NULL;
773 success = NULL;
774 fail = NULL;
775
776 if (otherproj->outcnt() == 1 && region != NULL && !region->has_phi()) {
777 for (int i = 0; i < 2; i++) {
778 ProjNode* proj = proj_out(i);
779 if (success == NULL && proj->outcnt() == 1 && proj->unique_out() == region) {
780 success = proj;
781 } else if (fail == NULL) {
782 fail = proj;
783 } else {
784 success = fail = NULL;
785 }
786 }
787 }
788 return success != NULL && fail != NULL;
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 == NULL) != (caller == NULL)) {
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 != NULL && !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(Deoptimization::Reason_none);
827 if (call != NULL) {
828 return proj_out(i);
829 }
830 }
831 return NULL;
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(Deoptimization::Reason_none);
838
839 if (otherproj->outcnt() == 1 && dom_unc != NULL) {
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 = NULL;
846 ProjNode* unc_proj = uncommon_trap_proj(unc);
847 if (unc_proj != NULL && 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() == NULL, "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 success = unc_proj;
872 fail = unc_proj->other_if_proj();
873 return true;
874 }
875 }
876 }
877 return false;
878 }
879
880 // Check that the 2 CmpI can be folded into as single CmpU and proceed with the folding
881 bool IfNode::fold_compares_helper(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn) {
882 Node* this_cmp = in(1)->in(1);
883 BoolNode* this_bool = in(1)->as_Bool();
884 IfNode* dom_iff = proj->in(0)->as_If();
885 BoolNode* dom_bool = dom_iff->in(1)->as_Bool();
886 Node* lo = dom_iff->in(1)->in(1)->in(2);
887 Node* hi = this_cmp->in(2);
888 Node* n = this_cmp->in(1);
889 ProjNode* otherproj = proj->other_if_proj();
890
891 const TypeInt* lo_type = IfNode::filtered_int_type(igvn, n, otherproj);
892 const TypeInt* hi_type = IfNode::filtered_int_type(igvn, n, success);
893
894 BoolTest::mask lo_test = dom_bool->_test._test;
895 BoolTest::mask hi_test = this_bool->_test._test;
896 BoolTest::mask cond = hi_test;
897
898 // convert:
899 //
900 // dom_bool = x {<,<=,>,>=} a
901 // / \
902 // proj = {True,False} / \ otherproj = {False,True}
903 // /
904 // this_bool = x {<,<=} b
905 // / \
906 // fail = {True,False} / \ success = {False,True}
907 // /
908 //
909 // (Second test guaranteed canonicalized, first one may not have
910 // been canonicalized yet)
911 //
912 // into:
913 //
914 // cond = (x - lo) {<u,<=u,>u,>=u} adjusted_lim
915 // / \
916 // fail / \ success
917 // /
918 //
919
920 // Figure out which of the two tests sets the upper bound and which
921 // sets the lower bound if any.
922 Node* adjusted_lim = NULL;
923 if (lo_type != NULL && hi_type != NULL && hi_type->_lo > lo_type->_hi &&
924 hi_type->_hi == max_jint && lo_type->_lo == min_jint) {
925 assert((dom_bool->_test.is_less() && !proj->_con) ||
926 (dom_bool->_test.is_greater() && proj->_con), "incorrect test");
927 // this test was canonicalized
928 assert(this_bool->_test.is_less() && fail->_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 {
952 assert(hi_test == BoolTest::le, "bad test");
953 if (lo_test == BoolTest::ge || lo_test == BoolTest::lt) {
954 adjusted_lim = igvn->transform(new SubINode(hi, lo));
955 adjusted_lim = igvn->transform(new AddINode(adjusted_lim, igvn->intcon(1)));
956 cond = BoolTest::lt;
957 } else {
958 assert(lo_test == BoolTest::gt || lo_test == BoolTest::le, "bad test");
959 adjusted_lim = igvn->transform(new SubINode(hi, lo));
960 lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
961 cond = BoolTest::lt;
962 }
963 }
964 } else if (lo_type != NULL && hi_type != NULL && lo_type->_lo > hi_type->_hi &&
965 lo_type->_hi == max_jint && hi_type->_lo == min_jint) {
966
967 // this_bool = <
968 // dom_bool = < (proj = True) or dom_bool = >= (proj = False)
969 // x in [b, a[ on the fail (= False) projection, a > b-1 (because of lo_type->_lo > hi_type->_hi above):
970 // lo = b, hi = a, adjusted_lim = a-b, cond = >=u
971 // dom_bool = <= (proj = True) or dom_bool = > (proj = False)
972 // x in [b, a] on the fail (= False) projection, a+1 > b-1:
973 // lo = b, hi = a, adjusted_lim = a-b+1, cond = >=u
974 // lo = b, hi = a, adjusted_lim = a-b, cond = >u doesn't work because a = b - 1 is possible, then b-a = -1
975 // this_bool = <=
976 // dom_bool = < (proj = True) or dom_bool = >= (proj = False)
977 // x in ]b, a[ on the fail (= False) projection, a > b:
978 // lo = b+1, hi = a, adjusted_lim = a-b-1, cond = >=u
979 // dom_bool = <= (proj = True) or dom_bool = > (proj = False)
980 // x in ]b, a] on the fail (= False) projection, a+1 > b:
981 // lo = b+1, hi = a, adjusted_lim = a-b, cond = >=u
982 // 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
983
984 swap(lo, hi);
985 swap(lo_type, hi_type);
986 swap(lo_test, hi_test);
987
988 assert((dom_bool->_test.is_less() && proj->_con) ||
989 (dom_bool->_test.is_greater() && !proj->_con), "incorrect test");
990 // this test was canonicalized
991 assert(this_bool->_test.is_less() && !fail->_con, "incorrect test");
992
993 cond = (hi_test == BoolTest::le || hi_test == BoolTest::gt) ? BoolTest::gt : BoolTest::ge;
994
995 if (lo_test == BoolTest::lt) {
996 if (hi_test == BoolTest::lt || hi_test == BoolTest::ge) {
997 cond = BoolTest::ge;
998 } else {
999 assert(hi_test == BoolTest::le || hi_test == BoolTest::gt, "bad test");
1000 adjusted_lim = igvn->transform(new SubINode(hi, lo));
1001 adjusted_lim = igvn->transform(new AddINode(adjusted_lim, igvn->intcon(1)));
1002 cond = BoolTest::ge;
1003 }
1004 } else if (lo_test == BoolTest::le) {
1005 if (hi_test == BoolTest::lt || hi_test == BoolTest::ge) {
1006 lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
1007 cond = BoolTest::ge;
1008 } else {
1009 assert(hi_test == BoolTest::le || hi_test == BoolTest::gt, "bad test");
1010 adjusted_lim = igvn->transform(new SubINode(hi, lo));
1011 lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
1012 cond = BoolTest::ge;
1013 }
1014 }
1015 } else {
1016 const TypeInt* failtype = filtered_int_type(igvn, n, proj);
1017 if (failtype != NULL) {
1018 const TypeInt* type2 = filtered_int_type(igvn, n, fail);
1019 if (type2 != NULL) {
1020 failtype = failtype->join(type2)->is_int();
1021 if (failtype->_lo > failtype->_hi) {
1022 // previous if determines the result of this if so
1023 // replace Bool with constant
1024 igvn->_worklist.push(in(1));
1025 igvn->replace_input_of(this, 1, igvn->intcon(success->_con));
1026 return true;
1027 }
1028 }
1029 }
1030 lo = NULL;
1031 hi = NULL;
1032 }
1033
1034 if (lo && hi) {
1035 // Merge the two compares into a single unsigned compare by building (CmpU (n - lo) (hi - lo))
1036 Node* adjusted_val = igvn->transform(new SubINode(n, lo));
1037 if (adjusted_lim == NULL) {
1038 adjusted_lim = igvn->transform(new SubINode(hi, lo));
1039 }
1040 Node* newcmp = igvn->transform(new CmpUNode(adjusted_val, adjusted_lim));
1041 Node* newbool = igvn->transform(new BoolNode(newcmp, cond));
1042
1043 igvn->replace_input_of(dom_iff, 1, igvn->intcon(proj->_con));
1044 igvn->_worklist.push(in(1));
1045 igvn->replace_input_of(this, 1, newbool);
1046
1047 return true;
1048 }
1049 return false;
1050 }
1051
1052 // Merge the branches that trap for this If and the dominating If into
1053 // a single region that branches to the uncommon trap for the
1054 // dominating If
1055 Node* IfNode::merge_uncommon_traps(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn) {
1056 Node* res = this;
1057 assert(success->in(0) == this, "bad projection");
1058
1059 ProjNode* otherproj = proj->other_if_proj();
1060
1061 CallStaticJavaNode* unc = success->is_uncommon_trap_proj(Deoptimization::Reason_none);
1062 CallStaticJavaNode* dom_unc = otherproj->is_uncommon_trap_proj(Deoptimization::Reason_none);
1063
1064 if (unc != dom_unc) {
1065 Node* r = new RegionNode(3);
1066
1067 r->set_req(1, otherproj);
1068 r->set_req(2, success);
1069 r = igvn->transform(r);
1070 assert(r->is_Region(), "can't go away");
1071
1072 // Make both If trap at the state of the first If: once the CmpI
1073 // nodes are merged, if we trap we don't know which of the CmpI
1074 // nodes would have caused the trap so we have to restart
1075 // execution at the first one
1076 igvn->replace_input_of(dom_unc, 0, r);
1077 igvn->replace_input_of(unc, 0, igvn->C->top());
1078 }
1079 int trap_request = dom_unc->uncommon_trap_request();
1080 Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(trap_request);
1081 Deoptimization::DeoptAction action = Deoptimization::trap_request_action(trap_request);
1082
1083 int flip_test = 0;
1084 Node* l = NULL;
1085 Node* r = NULL;
1086
1087 if (success->in(0)->as_If()->range_check_trap_proj(flip_test, l, r) != NULL) {
1088 // If this looks like a range check, change the trap to
1089 // Reason_range_check so the compiler recognizes it as a range
1090 // check and applies the corresponding optimizations
1091 trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_range_check, action);
1092
1093 improve_address_types(l, r, fail, igvn);
1094
1095 res = igvn->transform(new RangeCheckNode(in(0), in(1), _prob, _fcnt));
1096 } else if (unc != dom_unc) {
1097 // If we trap we won't know what CmpI would have caused the trap
1098 // so use a special trap reason to mark this pair of CmpI nodes as
1099 // bad candidate for folding. On recompilation we won't fold them
1100 // and we may trap again but this time we'll know what branch
1101 // traps
1102 trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_unstable_fused_if, action);
1103 }
1104 igvn->replace_input_of(dom_unc, TypeFunc::Parms, igvn->intcon(trap_request));
1105 return res;
1106 }
1107
1108 // If we are turning 2 CmpI nodes into a CmpU that follows the pattern
1109 // of a rangecheck on index i, on 64 bit the compares may be followed
1110 // by memory accesses using i as index. In that case, the CmpU tells
1111 // us something about the values taken by i that can help the compiler
1112 // (see Compile::conv_I2X_index())
1113 void IfNode::improve_address_types(Node* l, Node* r, ProjNode* fail, PhaseIterGVN* igvn) {
1114 #ifdef _LP64
1115 ResourceMark rm;
1116 Node_Stack stack(2);
1117
1118 assert(r->Opcode() == Op_LoadRange, "unexpected range check");
1119 const TypeInt* array_size = igvn->type(r)->is_int();
1120
1121 stack.push(l, 0);
1122
1123 while(stack.size() > 0) {
1124 Node* n = stack.node();
1125 uint start = stack.index();
1126
1127 uint i = start;
1128 for (; i < n->outcnt(); i++) {
1129 Node* use = n->raw_out(i);
1130 if (stack.size() == 1) {
1131 if (use->Opcode() == Op_ConvI2L) {
1132 const TypeLong* bounds = use->as_Type()->type()->is_long();
1133 if (bounds->_lo <= array_size->_lo && bounds->_hi >= array_size->_hi &&
1134 (bounds->_lo != array_size->_lo || bounds->_hi != array_size->_hi)) {
1135 stack.set_index(i+1);
1136 stack.push(use, 0);
1137 break;
1138 }
1139 }
1140 } else if (use->is_Mem()) {
1141 Node* ctrl = use->in(0);
1142 for (int i = 0; i < 10 && ctrl != NULL && ctrl != fail; i++) {
1143 ctrl = up_one_dom(ctrl);
1144 }
1145 if (ctrl == fail) {
1146 Node* init_n = stack.node_at(1);
1147 assert(init_n->Opcode() == Op_ConvI2L, "unexpected first node");
1148 // Create a new narrow ConvI2L node that is dependent on the range check
1149 Node* new_n = igvn->C->conv_I2X_index(igvn, l, array_size, fail);
1150
1151 // The type of the ConvI2L may be widen and so the new
1152 // ConvI2L may not be better than an existing ConvI2L
1153 if (new_n != init_n) {
1154 for (uint j = 2; j < stack.size(); j++) {
1155 Node* n = stack.node_at(j);
1156 Node* clone = n->clone();
1157 int rep = clone->replace_edge(init_n, new_n);
1158 assert(rep > 0, "can't find expected node?");
1159 clone = igvn->transform(clone);
1160 init_n = n;
1161 new_n = clone;
1162 }
1163 igvn->hash_delete(use);
1164 int rep = use->replace_edge(init_n, new_n);
1165 assert(rep > 0, "can't find expected node?");
1166 igvn->transform(use);
1167 if (init_n->outcnt() == 0) {
1168 igvn->_worklist.push(init_n);
1169 }
1170 }
1171 }
1172 } else if (use->in(0) == NULL && (igvn->type(use)->isa_long() ||
1173 igvn->type(use)->isa_ptr())) {
1174 stack.set_index(i+1);
1175 stack.push(use, 0);
1176 break;
1177 }
1178 }
1179 if (i == n->outcnt()) {
1180 stack.pop();
1181 }
1182 }
1183 #endif
1184 }
1185
1186 bool IfNode::is_cmp_with_loadrange(ProjNode* proj) {
1187 if (in(1) != NULL &&
1188 in(1)->in(1) != NULL &&
1189 in(1)->in(1)->in(2) != NULL) {
1190 Node* other = in(1)->in(1)->in(2);
1191 if (other->Opcode() == Op_LoadRange &&
1192 ((other->in(0) != NULL && other->in(0) == proj) ||
1193 (other->in(0) == NULL &&
1194 other->in(2) != NULL &&
1195 other->in(2)->is_AddP() &&
1196 other->in(2)->in(1) != NULL &&
1197 other->in(2)->in(1)->Opcode() == Op_CastPP &&
1198 other->in(2)->in(1)->in(0) == proj))) {
1199 return true;
1200 }
1201 }
1202 return false;
1203 }
1204
1205 bool IfNode::is_null_check(ProjNode* proj, PhaseIterGVN* igvn) {
1206 Node* other = in(1)->in(1)->in(2);
1207 if (other->in(MemNode::Address) != NULL &&
1208 proj->in(0)->in(1) != NULL &&
1209 proj->in(0)->in(1)->is_Bool() &&
1210 proj->in(0)->in(1)->in(1) != NULL &&
1211 proj->in(0)->in(1)->in(1)->Opcode() == Op_CmpP &&
1212 proj->in(0)->in(1)->in(1)->in(2) != NULL &&
1213 proj->in(0)->in(1)->in(1)->in(1) == other->in(MemNode::Address)->in(AddPNode::Address)->uncast() &&
1214 igvn->type(proj->in(0)->in(1)->in(1)->in(2)) == TypePtr::NULL_PTR) {
1215 return true;
1216 }
1217 return false;
1218 }
1219
1220 // Check that the If that is in between the 2 integer comparisons has
1221 // no side effect
1222 bool IfNode::is_side_effect_free_test(ProjNode* proj, PhaseIterGVN* igvn) {
1223 if (proj == NULL) {
1224 return false;
1225 }
1226 CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
1227 if (unc != NULL && proj->outcnt() <= 2) {
1228 if (proj->outcnt() == 1 ||
1229 // Allow simple null check from LoadRange
1230 (is_cmp_with_loadrange(proj) && is_null_check(proj, igvn))) {
1231 CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
1232 CallStaticJavaNode* dom_unc = proj->in(0)->in(0)->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
1233 assert(dom_unc != NULL, "is_uncommon_trap_if_pattern returned NULL");
1234
1235 // reroute_side_effect_free_unc changes the state of this
1236 // uncommon trap to restart execution at the previous
1237 // CmpI. Check that this change in a previous compilation didn't
1238 // cause too many traps.
1239 int trap_request = unc->uncommon_trap_request();
1240 Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(trap_request);
1241
1242 if (igvn->C->too_many_traps(dom_unc->jvms()->method(), dom_unc->jvms()->bci(), reason)) {
1243 return false;
1244 }
1245
1246 if (!is_dominator_unc(dom_unc, unc)) {
1247 return false;
1248 }
1249
1250 return true;
1251 }
1252 }
1253 return false;
1254 }
1255
1256 // Make the If between the 2 integer comparisons trap at the state of
1257 // the first If: the last CmpI is the one replaced by a CmpU and the
1258 // first CmpI is eliminated, so the test between the 2 CmpI nodes
1259 // won't be guarded by the first CmpI anymore. It can trap in cases
1260 // where the first CmpI would have prevented it from executing: on a
1261 // trap, we need to restart execution at the state of the first CmpI
1262 void IfNode::reroute_side_effect_free_unc(ProjNode* proj, ProjNode* dom_proj, PhaseIterGVN* igvn) {
1263 CallStaticJavaNode* dom_unc = dom_proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
1264 ProjNode* otherproj = proj->other_if_proj();
1265 CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
1266 Node* call_proj = dom_unc->unique_ctrl_out();
1267 Node* halt = call_proj->unique_ctrl_out();
1268
1269 Node* new_unc = dom_unc->clone();
1270 call_proj = call_proj->clone();
1271 halt = halt->clone();
1272 Node* c = otherproj->clone();
1273
1274 c = igvn->transform(c);
1275 new_unc->set_req(TypeFunc::Parms, unc->in(TypeFunc::Parms));
1276 new_unc->set_req(0, c);
1277 new_unc = igvn->transform(new_unc);
1278 call_proj->set_req(0, new_unc);
1279 call_proj = igvn->transform(call_proj);
1280 halt->set_req(0, call_proj);
1281 halt = igvn->transform(halt);
1282
1283 igvn->replace_node(otherproj, igvn->C->top());
1284 igvn->C->root()->add_req(halt);
1285 }
1286
1287 Node* IfNode::fold_compares(PhaseIterGVN* igvn) {
1288 if (Opcode() != Op_If) return NULL;
1289
1290 if (cmpi_folds(igvn)) {
1291 Node* ctrl = in(0);
1292 if (is_ctrl_folds(ctrl, igvn) &&
1293 ctrl->outcnt() == 1) {
1294 // A integer comparison immediately dominated by another integer
1295 // comparison
1296 ProjNode* success = NULL;
1297 ProjNode* fail = NULL;
1298 ProjNode* dom_cmp = ctrl->as_Proj();
1299 if (has_shared_region(dom_cmp, success, fail) &&
1300 // Next call modifies graph so must be last
1301 fold_compares_helper(dom_cmp, success, fail, igvn)) {
1302 return this;
1303 }
1304 if (has_only_uncommon_traps(dom_cmp, success, fail, igvn) &&
1305 // Next call modifies graph so must be last
1306 fold_compares_helper(dom_cmp, success, fail, igvn)) {
1307 return merge_uncommon_traps(dom_cmp, success, fail, igvn);
1308 }
1309 return NULL;
1310 } else if (ctrl->in(0) != NULL &&
1311 ctrl->in(0)->in(0) != NULL) {
1312 ProjNode* success = NULL;
1313 ProjNode* fail = NULL;
1314 Node* dom = ctrl->in(0)->in(0);
1315 ProjNode* dom_cmp = dom->isa_Proj();
1316 ProjNode* other_cmp = ctrl->isa_Proj();
1317
1318 // Check if it's an integer comparison dominated by another
1319 // integer comparison with another test in between
1320 if (is_ctrl_folds(dom, igvn) &&
1321 has_only_uncommon_traps(dom_cmp, success, fail, igvn) &&
1322 is_side_effect_free_test(other_cmp, igvn) &&
1323 // Next call modifies graph so must be last
1324 fold_compares_helper(dom_cmp, success, fail, igvn)) {
1325 reroute_side_effect_free_unc(other_cmp, dom_cmp, igvn);
1326 return merge_uncommon_traps(dom_cmp, success, fail, igvn);
1327 }
1328 }
1329 }
1330 return NULL;
1331 }
1332
1333 //------------------------------remove_useless_bool----------------------------
1334 // Check for people making a useless boolean: things like
1335 // if( (x < y ? true : false) ) { ... }
1336 // Replace with if( x < y ) { ... }
1337 static Node *remove_useless_bool(IfNode *iff, PhaseGVN *phase) {
1338 Node *i1 = iff->in(1);
1339 if( !i1->is_Bool() ) return NULL;
1340 BoolNode *bol = i1->as_Bool();
1341
1342 Node *cmp = bol->in(1);
1343 if( cmp->Opcode() != Op_CmpI ) return NULL;
1344
1345 // Must be comparing against a bool
1346 const Type *cmp2_t = phase->type( cmp->in(2) );
1347 if( cmp2_t != TypeInt::ZERO &&
1348 cmp2_t != TypeInt::ONE )
1349 return NULL;
1350
1351 // Find a prior merge point merging the boolean
1352 i1 = cmp->in(1);
1353 if( !i1->is_Phi() ) return NULL;
1354 PhiNode *phi = i1->as_Phi();
1355 if( phase->type( phi ) != TypeInt::BOOL )
1356 return NULL;
1357
1358 // Check for diamond pattern
1359 int true_path = phi->is_diamond_phi();
1360 if( true_path == 0 ) return NULL;
1361
1362 // Make sure that iff and the control of the phi are different. This
1363 // should really only happen for dead control flow since it requires
1364 // an illegal cycle.
1365 if (phi->in(0)->in(1)->in(0) == iff) return NULL;
1366
1367 // phi->region->if_proj->ifnode->bool->cmp
1368 BoolNode *bol2 = phi->in(0)->in(1)->in(0)->in(1)->as_Bool();
1369
1370 // Now get the 'sense' of the test correct so we can plug in
1371 // either iff2->in(1) or its complement.
1372 int flip = 0;
1373 if( bol->_test._test == BoolTest::ne ) flip = 1-flip;
1374 else if( bol->_test._test != BoolTest::eq ) return NULL;
1375 if( cmp2_t == TypeInt::ZERO ) flip = 1-flip;
1376
1377 const Type *phi1_t = phase->type( phi->in(1) );
1378 const Type *phi2_t = phase->type( phi->in(2) );
1379 // Check for Phi(0,1) and flip
1380 if( phi1_t == TypeInt::ZERO ) {
1381 if( phi2_t != TypeInt::ONE ) return NULL;
1382 flip = 1-flip;
1383 } else {
1384 // Check for Phi(1,0)
1385 if( phi1_t != TypeInt::ONE ) return NULL;
1386 if( phi2_t != TypeInt::ZERO ) return NULL;
1387 }
1388 if( true_path == 2 ) {
1389 flip = 1-flip;
1390 }
1391
1392 Node* new_bol = (flip ? phase->transform( bol2->negate(phase) ) : bol2);
1393 assert(new_bol != iff->in(1), "must make progress");
1394 iff->set_req(1, new_bol);
1395 // Intervening diamond probably goes dead
1396 phase->C->set_major_progress();
1397 return iff;
1398 }
1399
1400 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff);
1401
1402 struct RangeCheck {
1403 Node* ctl;
1404 jint off;
1405 };
1406
1407 Node* IfNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
1408 if (remove_dead_region(phase, can_reshape)) return this;
1409 // No Def-Use info?
1410 if (!can_reshape) return NULL;
1411
1412 // Don't bother trying to transform a dead if
1413 if (in(0)->is_top()) return NULL;
1414 // Don't bother trying to transform an if with a dead test
1415 if (in(1)->is_top()) return NULL;
1416 // Another variation of a dead test
1417 if (in(1)->is_Con()) return NULL;
1418 // Another variation of a dead if
1419 if (outcnt() < 2) return NULL;
1420
1421 // Canonicalize the test.
1422 Node* idt_if = idealize_test(phase, this);
1423 if (idt_if != NULL) return idt_if;
1424
1425 // Try to split the IF
1426 PhaseIterGVN *igvn = phase->is_IterGVN();
1427 Node *s = split_if(this, igvn);
1428 if (s != NULL) return s;
1429
1430 return NodeSentinel;
1431 }
1432
1433 //------------------------------Ideal------------------------------------------
1434 // Return a node which is more "ideal" than the current node. Strip out
1435 // control copies
1436 Node* IfNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1437 Node* res = Ideal_common(phase, can_reshape);
1438 if (res != NodeSentinel) {
1439 return res;
1440 }
1441
1442 // Check for people making a useless boolean: things like
1443 // if( (x < y ? true : false) ) { ... }
1444 // Replace with if( x < y ) { ... }
1445 Node *bol2 = remove_useless_bool(this, phase);
1446 if( bol2 ) return bol2;
1447
1448 if (in(0) == NULL) return NULL; // Dead loop?
1449
1450 PhaseIterGVN *igvn = phase->is_IterGVN();
1451 Node* result = fold_compares(igvn);
1452 if (result != NULL) {
1453 return result;
1454 }
1455
1456 // Scan for an equivalent test
1457 Node *cmp;
1458 int dist = 0; // Cutoff limit for search
1459 int op = Opcode();
1460 if( op == Op_If &&
1461 (cmp=in(1)->in(1))->Opcode() == Op_CmpP ) {
1462 if( cmp->in(2) != NULL && // make sure cmp is not already dead
1463 cmp->in(2)->bottom_type() == TypePtr::NULL_PTR ) {
1464 dist = 64; // Limit for null-pointer scans
1465 } else {
1466 dist = 4; // Do not bother for random pointer tests
1467 }
1468 #if INCLUDE_SHENANDOAHGC
1469 } else if (ShenandoahWriteBarrierNode::is_evacuation_in_progress_test(this)) {
1470 dist = 16;
1471 #endif
1472 } else {
1473 dist = 4; // Limit for random junky scans
1474 }
1475
1476 Node* prev_dom = search_identical(dist);
1477
1478 if (prev_dom == NULL) {
1479 return NULL;
1480 }
1481
1482 // Replace dominated IfNode
1483 return dominated_by(prev_dom, igvn);
1484 }
1485
1486 //------------------------------dominated_by-----------------------------------
1487 Node* IfNode::dominated_by(Node* prev_dom, PhaseIterGVN *igvn) {
1488 #ifndef PRODUCT
1489 if (TraceIterativeGVN) {
1490 tty->print(" Removing IfNode: "); this->dump();
1491 }
1492 if (VerifyOpto && !igvn->allow_progress()) {
1493 // Found an equivalent dominating test,
1494 // we can not guarantee reaching a fix-point for these during iterativeGVN
1495 // since intervening nodes may not change.
1496 return NULL;
1497 }
1498 #endif
1499
1500 igvn->hash_delete(this); // Remove self to prevent spurious V-N
1501 Node *idom = in(0);
1502 // Need opcode to decide which way 'this' test goes
1503 int prev_op = prev_dom->Opcode();
1504 Node *top = igvn->C->top(); // Shortcut to top
1505
1506 // Loop predicates may have depending checks which should not
1507 // be skipped. For example, range check predicate has two checks
1508 // for lower and upper bounds.
1509 ProjNode* unc_proj = proj_out(1 - prev_dom->as_Proj()->_con)->as_Proj();
1510 if (unc_proj != NULL &&
1511 (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate) != NULL ||
1512 unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_profile_predicate) != NULL)) {
1513 prev_dom = idom;
1514 }
1515
1516 // Now walk the current IfNode's projections.
1517 // Loop ends when 'this' has no more uses.
1518 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
1519 Node *ifp = last_out(i); // Get IfTrue/IfFalse
1520 igvn->add_users_to_worklist(ifp);
1521 // Check which projection it is and set target.
1522 // Data-target is either the dominating projection of the same type
1523 // or TOP if the dominating projection is of opposite type.
1524 // Data-target will be used as the new control edge for the non-CFG
1525 // nodes like Casts and Loads.
1526 Node *data_target = (ifp->Opcode() == prev_op) ? prev_dom : top;
1527 // Control-target is just the If's immediate dominator or TOP.
1528 Node *ctrl_target = (ifp->Opcode() == prev_op) ? idom : top;
1529
1530 // For each child of an IfTrue/IfFalse projection, reroute.
1531 // Loop ends when projection has no more uses.
1532 for (DUIterator_Last jmin, j = ifp->last_outs(jmin); j >= jmin; --j) {
1533 Node* s = ifp->last_out(j); // Get child of IfTrue/IfFalse
1534 if( !s->depends_only_on_test() ) {
1535 // Find the control input matching this def-use edge.
1536 // For Regions it may not be in slot 0.
1537 uint l;
1538 for( l = 0; s->in(l) != ifp; l++ ) { }
1539 igvn->replace_input_of(s, l, ctrl_target);
1540 } else { // Else, for control producers,
1541 igvn->replace_input_of(s, 0, data_target); // Move child to data-target
1542 }
1543 } // End for each child of a projection
1544
1545 igvn->remove_dead_node(ifp);
1546 } // End for each IfTrue/IfFalse child of If
1547
1548 // Kill the IfNode
1549 igvn->remove_dead_node(this);
1550
1551 // Must return either the original node (now dead) or a new node
1552 // (Do not return a top here, since that would break the uniqueness of top.)
1553 return new ConINode(TypeInt::ZERO);
1554 }
1555
1556 Node* IfNode::search_identical(int dist) {
1557 // Setup to scan up the CFG looking for a dominating test
1558 Node* dom = in(0);
1559 Node* prev_dom = this;
1560 int op = Opcode();
1561 #if INCLUDE_SHENANDOAHGC
1562 bool evac_in_progress = ShenandoahWriteBarrierNode::is_evacuation_in_progress_test(this);
1563 #endif
1564 // Search up the dominator tree for an If with an identical test
1565 while (dom->Opcode() != op || // Not same opcode?
1566 (dom->in(1) != in(1) SHENANDOAHGC_ONLY(&& (!evac_in_progress || !ShenandoahWriteBarrierNode::is_evacuation_in_progress_test(dom->as_If())))) || // Not same input 1?
1567 prev_dom->in(0) != dom) { // One path of test does not dominate?
1568 if (dist < 0) return NULL;
1569
1570 dist--;
1571 prev_dom = dom;
1572 dom = up_one_dom(dom);
1573 if (!dom) return NULL;
1574 }
1575
1576 // Check that we did not follow a loop back to ourselves
1577 if (this == dom) {
1578 return NULL;
1579 }
1580
1581 #ifndef PRODUCT
1582 if (dist > 2) { // Add to count of NULL checks elided
1583 explicit_null_checks_elided++;
1584 }
1585 #endif
1586
1587 return prev_dom;
1588 }
1589
1590 //------------------------------Identity---------------------------------------
1591 // If the test is constant & we match, then we are the input Control
1592 Node* IfProjNode::Identity(PhaseGVN* phase) {
1593 // Can only optimize if cannot go the other way
1594 const TypeTuple *t = phase->type(in(0))->is_tuple();
1595 if (t == TypeTuple::IFNEITHER || (always_taken(t) &&
1596 // During parsing (GVN) we don't remove dead code aggressively.
1597 // Cut off dead branch and let PhaseRemoveUseless take care of it.
1598 (!phase->is_IterGVN() ||
1599 // During IGVN, first wait for the dead branch to be killed.
1600 // Otherwise, the IfNode's control will have two control uses (the IfNode
1601 // that doesn't go away because it still has uses and this branch of the
1602 // If) which breaks other optimizations. Node::has_special_unique_user()
1603 // will cause this node to be reprocessed once the dead branch is killed.
1604 in(0)->outcnt() == 1))) {
1605 // IfNode control
1606 return in(0)->in(0);
1607 }
1608 // no progress
1609 return this;
1610 }
1611
1612 #ifndef PRODUCT
1613 //-------------------------------related---------------------------------------
1614 // An IfProjNode's related node set consists of its input (an IfNode) including
1615 // the IfNode's condition, plus all of its outputs at level 1. In compact mode,
1616 // the restrictions for IfNode apply (see IfNode::rel).
1617 void IfProjNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
1618 Node* ifNode = this->in(0);
1619 in_rel->append(ifNode);
1620 if (compact) {
1621 ifNode->collect_nodes(in_rel, 3, false, true);
1622 } else {
1623 ifNode->collect_nodes_in_all_data(in_rel, false);
1624 }
1625 this->collect_nodes(out_rel, -1, false, false);
1626 }
1627
1628 //------------------------------dump_spec--------------------------------------
1629 void IfNode::dump_spec(outputStream *st) const {
1630 st->print("P=%f, C=%f",_prob,_fcnt);
1631 }
1632
1633 //-------------------------------related---------------------------------------
1634 // For an IfNode, the set of related output nodes is just the output nodes till
1635 // depth 2, i.e, the IfTrue/IfFalse projection nodes plus the nodes they refer.
1636 // The related input nodes contain no control nodes, but all data nodes
1637 // pertaining to the condition. In compact mode, the input nodes are collected
1638 // up to a depth of 3.
1639 void IfNode::related(GrowableArray <Node *> *in_rel, GrowableArray <Node *> *out_rel, bool compact) const {
1640 if (compact) {
1641 this->collect_nodes(in_rel, 3, false, true);
1642 } else {
1643 this->collect_nodes_in_all_data(in_rel, false);
1644 }
1645 this->collect_nodes(out_rel, -2, false, false);
1646 }
1647 #endif
1648
1649 //------------------------------idealize_test----------------------------------
1650 // Try to canonicalize tests better. Peek at the Cmp/Bool/If sequence and
1651 // come up with a canonical sequence. Bools getting 'eq', 'gt' and 'ge' forms
1652 // converted to 'ne', 'le' and 'lt' forms. IfTrue/IfFalse get swapped as
1653 // needed.
1654 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff) {
1655 assert(iff->in(0) != NULL, "If must be live");
1656
1657 if (iff->outcnt() != 2) return NULL; // Malformed projections.
1658 Node* old_if_f = iff->proj_out(false);
1659 Node* old_if_t = iff->proj_out(true);
1660
1661 // CountedLoopEnds want the back-control test to be TRUE, irregardless of
1662 // whether they are testing a 'gt' or 'lt' condition. The 'gt' condition
1663 // happens in count-down loops
1664 if (iff->is_CountedLoopEnd()) return NULL;
1665 if (!iff->in(1)->is_Bool()) return NULL; // Happens for partially optimized IF tests
1666 BoolNode *b = iff->in(1)->as_Bool();
1667 BoolTest bt = b->_test;
1668 // Test already in good order?
1669 if( bt.is_canonical() )
1670 return NULL;
1671
1672 // Flip test to be canonical. Requires flipping the IfFalse/IfTrue and
1673 // cloning the IfNode.
1674 Node* new_b = phase->transform( new BoolNode(b->in(1), bt.negate()) );
1675 if( !new_b->is_Bool() ) return NULL;
1676 b = new_b->as_Bool();
1677
1678 PhaseIterGVN *igvn = phase->is_IterGVN();
1679 assert( igvn, "Test is not canonical in parser?" );
1680
1681 // The IF node never really changes, but it needs to be cloned
1682 iff = iff->clone()->as_If();
1683 iff->set_req(1, b);
1684 iff->_prob = 1.0-iff->_prob;
1685
1686 Node *prior = igvn->hash_find_insert(iff);
1687 if( prior ) {
1688 igvn->remove_dead_node(iff);
1689 iff = (IfNode*)prior;
1690 } else {
1691 // Cannot call transform on it just yet
1692 igvn->set_type_bottom(iff);
1693 }
1694 igvn->_worklist.push(iff);
1695
1696 // Now handle projections. Cloning not required.
1697 Node* new_if_f = (Node*)(new IfFalseNode( iff ));
1698 Node* new_if_t = (Node*)(new IfTrueNode ( iff ));
1699
1700 igvn->register_new_node_with_optimizer(new_if_f);
1701 igvn->register_new_node_with_optimizer(new_if_t);
1702 // Flip test, so flip trailing control
1703 igvn->replace_node(old_if_f, new_if_t);
1704 igvn->replace_node(old_if_t, new_if_f);
1705
1706 // Progress
1707 return iff;
1708 }
1709
1710 bool IfNode::is_g1_marking_if(PhaseTransform *phase) const {
1711 if (Opcode() != Op_If) {
1712 return false;
1713 }
1714
1715 Node* bol = in(1);
1716 assert(bol->is_Bool(), "");
1717 Node* cmpx = bol->in(1);
1718 if (bol->as_Bool()->_test._test == BoolTest::ne &&
1719 cmpx->is_Cmp() && cmpx->in(2) == phase->intcon(0) &&
1720 cmpx->in(1)->is_g1_marking_load()) {
1721 return true;
1722 }
1723 return false;
1724 }
1725
1726 #if INCLUDE_SHENANDOAHGC
1727 bool IfNode::is_shenandoah_marking_if(PhaseTransform *phase) const {
1728 if (!UseShenandoahGC) {
1729 return false;
1730 }
1731
1732 if (Opcode() != Op_If) {
1733 return false;
1734 }
1735
1736 Node* bol = in(1);
1737 assert(bol->is_Bool(), "");
1738 Node* cmpx = bol->in(1);
1739 if (bol->as_Bool()->_test._test == BoolTest::ne &&
1740 cmpx->is_Cmp() && cmpx->in(2) == phase->intcon(0) &&
1741 cmpx->in(1)->in(1)->is_shenandoah_state_load() &&
1742 cmpx->in(1)->in(2)->is_Con() &&
1743 cmpx->in(1)->in(2) == phase->intcon(ShenandoahHeap::MARKING)) {
1744 return true;
1745 }
1746
1747 return false;
1748 }
1749 #endif
1750
1751
1752 Node* RangeCheckNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1753 Node* res = Ideal_common(phase, can_reshape);
1754 if (res != NodeSentinel) {
1755 return res;
1756 }
1757
1758 PhaseIterGVN *igvn = phase->is_IterGVN();
1759 // Setup to scan up the CFG looking for a dominating test
1760 Node* prev_dom = this;
1761
1762 // Check for range-check vs other kinds of tests
1763 Node* index1;
1764 Node* range1;
1765 jint offset1;
1766 int flip1 = is_range_check(range1, index1, offset1);
1767 if (flip1) {
1768 Node* dom = in(0);
1769 // Try to remove extra range checks. All 'up_one_dom' gives up at merges
1770 // so all checks we inspect post-dominate the top-most check we find.
1771 // If we are going to fail the current check and we reach the top check
1772 // then we are guaranteed to fail, so just start interpreting there.
1773 // We 'expand' the top 3 range checks to include all post-dominating
1774 // checks.
1775
1776 // The top 3 range checks seen
1777 const int NRC =3;
1778 RangeCheck prev_checks[NRC];
1779 int nb_checks = 0;
1780
1781 // Low and high offsets seen so far
1782 jint off_lo = offset1;
1783 jint off_hi = offset1;
1784
1785 bool found_immediate_dominator = false;
1786
1787 // Scan for the top checks and collect range of offsets
1788 for (int dist = 0; dist < 999; dist++) { // Range-Check scan limit
1789 if (dom->Opcode() == Op_RangeCheck && // Not same opcode?
1790 prev_dom->in(0) == dom) { // One path of test does dominate?
1791 if (dom == this) return NULL; // dead loop
1792 // See if this is a range check
1793 Node* index2;
1794 Node* range2;
1795 jint offset2;
1796 int flip2 = dom->as_RangeCheck()->is_range_check(range2, index2, offset2);
1797 // See if this is a _matching_ range check, checking against
1798 // the same array bounds.
1799 if (flip2 == flip1 && range2 == range1 && index2 == index1 &&
1800 dom->outcnt() == 2) {
1801 if (nb_checks == 0 && dom->in(1) == in(1)) {
1802 // Found an immediately dominating test at the same offset.
1803 // This kind of back-to-back test can be eliminated locally,
1804 // and there is no need to search further for dominating tests.
1805 assert(offset2 == offset1, "Same test but different offsets");
1806 found_immediate_dominator = true;
1807 break;
1808 }
1809 // Gather expanded bounds
1810 off_lo = MIN2(off_lo,offset2);
1811 off_hi = MAX2(off_hi,offset2);
1812 // Record top NRC range checks
1813 prev_checks[nb_checks%NRC].ctl = prev_dom;
1814 prev_checks[nb_checks%NRC].off = offset2;
1815 nb_checks++;
1816 }
1817 }
1818 prev_dom = dom;
1819 dom = up_one_dom(dom);
1820 if (!dom) break;
1821 }
1822
1823 if (!found_immediate_dominator) {
1824 // Attempt to widen the dominating range check to cover some later
1825 // ones. Since range checks "fail" by uncommon-trapping to the
1826 // interpreter, widening a check can make us speculatively enter
1827 // the interpreter. If we see range-check deopt's, do not widen!
1828 if (!phase->C->allow_range_check_smearing()) return NULL;
1829
1830 // Didn't find prior covering check, so cannot remove anything.
1831 if (nb_checks == 0) {
1832 return NULL;
1833 }
1834 // Constant indices only need to check the upper bound.
1835 // Non-constant indices must check both low and high.
1836 int chk0 = (nb_checks - 1) % NRC;
1837 if (index1) {
1838 if (nb_checks == 1) {
1839 return NULL;
1840 } else {
1841 // If the top range check's constant is the min or max of
1842 // all constants we widen the next one to cover the whole
1843 // range of constants.
1844 RangeCheck rc0 = prev_checks[chk0];
1845 int chk1 = (nb_checks - 2) % NRC;
1846 RangeCheck rc1 = prev_checks[chk1];
1847 if (rc0.off == off_lo) {
1848 adjust_check(rc1.ctl, range1, index1, flip1, off_hi, igvn);
1849 prev_dom = rc1.ctl;
1850 } else if (rc0.off == off_hi) {
1851 adjust_check(rc1.ctl, range1, index1, flip1, off_lo, igvn);
1852 prev_dom = rc1.ctl;
1853 } else {
1854 // If the top test's constant is not the min or max of all
1855 // constants, we need 3 range checks. We must leave the
1856 // top test unchanged because widening it would allow the
1857 // accesses it protects to successfully read/write out of
1858 // bounds.
1859 if (nb_checks == 2) {
1860 return NULL;
1861 }
1862 int chk2 = (nb_checks - 3) % NRC;
1863 RangeCheck rc2 = prev_checks[chk2];
1864 // The top range check a+i covers interval: -a <= i < length-a
1865 // The second range check b+i covers interval: -b <= i < length-b
1866 if (rc1.off <= rc0.off) {
1867 // if b <= a, we change the second range check to:
1868 // -min_of_all_constants <= i < length-min_of_all_constants
1869 // Together top and second range checks now cover:
1870 // -min_of_all_constants <= i < length-a
1871 // which is more restrictive than -b <= i < length-b:
1872 // -b <= -min_of_all_constants <= i < length-a <= length-b
1873 // The third check is then changed to:
1874 // -max_of_all_constants <= i < length-max_of_all_constants
1875 // so 2nd and 3rd checks restrict allowed values of i to:
1876 // -min_of_all_constants <= i < length-max_of_all_constants
1877 adjust_check(rc1.ctl, range1, index1, flip1, off_lo, igvn);
1878 adjust_check(rc2.ctl, range1, index1, flip1, off_hi, igvn);
1879 } else {
1880 // if b > a, we change the second range check to:
1881 // -max_of_all_constants <= i < length-max_of_all_constants
1882 // Together top and second range checks now cover:
1883 // -a <= i < length-max_of_all_constants
1884 // which is more restrictive than -b <= i < length-b:
1885 // -b < -a <= i < length-max_of_all_constants <= length-b
1886 // The third check is then changed to:
1887 // -max_of_all_constants <= i < length-max_of_all_constants
1888 // so 2nd and 3rd checks restrict allowed values of i to:
1889 // -min_of_all_constants <= i < length-max_of_all_constants
1890 adjust_check(rc1.ctl, range1, index1, flip1, off_hi, igvn);
1891 adjust_check(rc2.ctl, range1, index1, flip1, off_lo, igvn);
1892 }
1893 prev_dom = rc2.ctl;
1894 }
1895 }
1896 } else {
1897 RangeCheck rc0 = prev_checks[chk0];
1898 // 'Widen' the offset of the 1st and only covering check
1899 adjust_check(rc0.ctl, range1, index1, flip1, off_hi, igvn);
1900 // Test is now covered by prior checks, dominate it out
1901 prev_dom = rc0.ctl;
1902 }
1903 }
1904 } else {
1905 prev_dom = search_identical(4);
1906
1907 if (prev_dom == NULL) {
1908 return NULL;
1909 }
1910 }
1911
1912 // Replace dominated IfNode
1913 return dominated_by(prev_dom, igvn);
1914 }