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