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