Sat, 19 Oct 2013 12:16:43 +0200
8024069: replace_in_map() should operate on parent maps
Summary: type information gets lost because replace_in_map() doesn't update parent maps
Reviewed-by: kvn, twisti
1 /*
2 * Copyright (c) 2000, 2012, 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
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7 * published by the Free Software Foundation.
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
25 #include "precompiled.hpp"
26 #include "memory/allocation.inline.hpp"
27 #include "opto/addnode.hpp"
28 #include "opto/cfgnode.hpp"
29 #include "opto/connode.hpp"
30 #include "opto/loopnode.hpp"
31 #include "opto/phaseX.hpp"
32 #include "opto/runtime.hpp"
33 #include "opto/subnode.hpp"
35 // Portions of code courtesy of Clifford Click
37 // Optimization - Graph Style
40 extern int explicit_null_checks_elided;
42 //=============================================================================
43 //------------------------------Value------------------------------------------
44 // Return a tuple for whichever arm of the IF is reachable
45 const Type *IfNode::Value( PhaseTransform *phase ) const {
46 if( !in(0) ) return Type::TOP;
47 if( phase->type(in(0)) == Type::TOP )
48 return Type::TOP;
49 const Type *t = phase->type(in(1));
50 if( t == Type::TOP ) // data is undefined
51 return TypeTuple::IFNEITHER; // unreachable altogether
52 if( t == TypeInt::ZERO ) // zero, or false
53 return TypeTuple::IFFALSE; // only false branch is reachable
54 if( t == TypeInt::ONE ) // 1, or true
55 return TypeTuple::IFTRUE; // only true branch is reachable
56 assert( t == TypeInt::BOOL, "expected boolean type" );
58 return TypeTuple::IFBOTH; // No progress
59 }
61 const RegMask &IfNode::out_RegMask() const {
62 return RegMask::Empty;
63 }
65 //------------------------------split_if---------------------------------------
66 // Look for places where we merge constants, then test on the merged value.
67 // If the IF test will be constant folded on the path with the constant, we
68 // win by splitting the IF to before the merge point.
69 static Node* split_if(IfNode *iff, PhaseIterGVN *igvn) {
70 // I could be a lot more general here, but I'm trying to squeeze this
71 // in before the Christmas '98 break so I'm gonna be kinda restrictive
72 // on the patterns I accept. CNC
74 // Look for a compare of a constant and a merged value
75 Node *i1 = iff->in(1);
76 if( !i1->is_Bool() ) return NULL;
77 BoolNode *b = i1->as_Bool();
78 Node *cmp = b->in(1);
79 if( cmp->is_FlagsProj() ) return NULL;
80 if( !cmp->is_Cmp() ) return NULL;
81 i1 = cmp->in(1);
82 if( i1 == NULL || !i1->is_Phi() ) return NULL;
83 PhiNode *phi = i1->as_Phi();
84 if( phi->is_copy() ) return NULL;
85 Node *con2 = cmp->in(2);
86 if( !con2->is_Con() ) return NULL;
87 // See that the merge point contains some constants
88 Node *con1=NULL;
89 uint i4;
90 for( i4 = 1; i4 < phi->req(); i4++ ) {
91 con1 = phi->in(i4);
92 if( !con1 ) return NULL; // Do not optimize partially collapsed merges
93 if( con1->is_Con() ) break; // Found a constant
94 // Also allow null-vs-not-null checks
95 const TypePtr *tp = igvn->type(con1)->isa_ptr();
96 if( tp && tp->_ptr == TypePtr::NotNull )
97 break;
98 }
99 if( i4 >= phi->req() ) return NULL; // Found no constants
101 igvn->C->set_has_split_ifs(true); // Has chance for split-if
103 // Make sure that the compare can be constant folded away
104 Node *cmp2 = cmp->clone();
105 cmp2->set_req(1,con1);
106 cmp2->set_req(2,con2);
107 const Type *t = cmp2->Value(igvn);
108 // This compare is dead, so whack it!
109 igvn->remove_dead_node(cmp2);
110 if( !t->singleton() ) return NULL;
112 // No intervening control, like a simple Call
113 Node *r = iff->in(0);
114 if( !r->is_Region() ) return NULL;
115 if( phi->region() != r ) return NULL;
116 // No other users of the cmp/bool
117 if (b->outcnt() != 1 || cmp->outcnt() != 1) {
118 //tty->print_cr("many users of cmp/bool");
119 return NULL;
120 }
122 // Make sure we can determine where all the uses of merged values go
123 for (DUIterator_Fast jmax, j = r->fast_outs(jmax); j < jmax; j++) {
124 Node* u = r->fast_out(j);
125 if( u == r ) continue;
126 if( u == iff ) continue;
127 if( u->outcnt() == 0 ) continue; // use is dead & ignorable
128 if( !u->is_Phi() ) {
129 /*
130 if( u->is_Start() ) {
131 tty->print_cr("Region has inlined start use");
132 } else {
133 tty->print_cr("Region has odd use");
134 u->dump(2);
135 }*/
136 return NULL;
137 }
138 if( u != phi ) {
139 // CNC - do not allow any other merged value
140 //tty->print_cr("Merging another value");
141 //u->dump(2);
142 return NULL;
143 }
144 // Make sure we can account for all Phi uses
145 for (DUIterator_Fast kmax, k = u->fast_outs(kmax); k < kmax; k++) {
146 Node* v = u->fast_out(k); // User of the phi
147 // CNC - Allow only really simple patterns.
148 // In particular I disallow AddP of the Phi, a fairly common pattern
149 if( v == cmp ) continue; // The compare is OK
150 if( (v->is_ConstraintCast()) &&
151 v->in(0)->in(0) == iff )
152 continue; // CastPP/II of the IfNode is OK
153 // Disabled following code because I cannot tell if exactly one
154 // path dominates without a real dominator check. CNC 9/9/1999
155 //uint vop = v->Opcode();
156 //if( vop == Op_Phi ) { // Phi from another merge point might be OK
157 // Node *r = v->in(0); // Get controlling point
158 // if( !r ) return NULL; // Degraded to a copy
159 // // Find exactly one path in (either True or False doms, but not IFF)
160 // int cnt = 0;
161 // for( uint i = 1; i < r->req(); i++ )
162 // if( r->in(i) && r->in(i)->in(0) == iff )
163 // cnt++;
164 // if( cnt == 1 ) continue; // Exactly one of True or False guards Phi
165 //}
166 if( !v->is_Call() ) {
167 /*
168 if( v->Opcode() == Op_AddP ) {
169 tty->print_cr("Phi has AddP use");
170 } else if( v->Opcode() == Op_CastPP ) {
171 tty->print_cr("Phi has CastPP use");
172 } else if( v->Opcode() == Op_CastII ) {
173 tty->print_cr("Phi has CastII use");
174 } else {
175 tty->print_cr("Phi has use I cant be bothered with");
176 }
177 */
178 }
179 return NULL;
181 /* CNC - Cut out all the fancy acceptance tests
182 // Can we clone this use when doing the transformation?
183 // If all uses are from Phis at this merge or constants, then YES.
184 if( !v->in(0) && v != cmp ) {
185 tty->print_cr("Phi has free-floating use");
186 v->dump(2);
187 return NULL;
188 }
189 for( uint l = 1; l < v->req(); l++ ) {
190 if( (!v->in(l)->is_Phi() || v->in(l)->in(0) != r) &&
191 !v->in(l)->is_Con() ) {
192 tty->print_cr("Phi has use");
193 v->dump(2);
194 return NULL;
195 } // End of if Phi-use input is neither Phi nor Constant
196 } // End of for all inputs to Phi-use
197 */
198 } // End of for all uses of Phi
199 } // End of for all uses of Region
201 // Only do this if the IF node is in a sane state
202 if (iff->outcnt() != 2)
203 return NULL;
205 // Got a hit! Do the Mondo Hack!
206 //
207 //ABC a1c def ghi B 1 e h A C a c d f g i
208 // R - Phi - Phi - Phi Rc - Phi - Phi - Phi Rx - Phi - Phi - Phi
209 // cmp - 2 cmp - 2 cmp - 2
210 // bool bool_c bool_x
211 // if if_c if_x
212 // T F T F T F
213 // ..s.. ..t .. ..s.. ..t.. ..s.. ..t..
214 //
215 // Split the paths coming into the merge point into 2 separate groups of
216 // merges. On the left will be all the paths feeding constants into the
217 // Cmp's Phi. On the right will be the remaining paths. The Cmp's Phi
218 // will fold up into a constant; this will let the Cmp fold up as well as
219 // all the control flow. Below the original IF we have 2 control
220 // dependent regions, 's' and 't'. Now we will merge the two paths
221 // just prior to 's' and 't' from the two IFs. At least 1 path (and quite
222 // likely 2 or more) will promptly constant fold away.
223 PhaseGVN *phase = igvn;
225 // Make a region merging constants and a region merging the rest
226 uint req_c = 0;
227 Node* predicate_proj = NULL;
228 for (uint ii = 1; ii < r->req(); ii++) {
229 if (phi->in(ii) == con1) {
230 req_c++;
231 }
232 Node* proj = PhaseIdealLoop::find_predicate(r->in(ii));
233 if (proj != NULL) {
234 assert(predicate_proj == NULL, "only one predicate entry expected");
235 predicate_proj = proj;
236 }
237 }
238 Node* predicate_c = NULL;
239 Node* predicate_x = NULL;
240 bool counted_loop = r->is_CountedLoop();
242 Node *region_c = new (igvn->C) RegionNode(req_c + 1);
243 Node *phi_c = con1;
244 uint len = r->req();
245 Node *region_x = new (igvn->C) RegionNode(len - req_c);
246 Node *phi_x = PhiNode::make_blank(region_x, phi);
247 for (uint i = 1, i_c = 1, i_x = 1; i < len; i++) {
248 if (phi->in(i) == con1) {
249 region_c->init_req( i_c++, r ->in(i) );
250 if (r->in(i) == predicate_proj)
251 predicate_c = predicate_proj;
252 } else {
253 region_x->init_req( i_x, r ->in(i) );
254 phi_x ->init_req( i_x++, phi->in(i) );
255 if (r->in(i) == predicate_proj)
256 predicate_x = predicate_proj;
257 }
258 }
259 if (predicate_c != NULL && (req_c > 1)) {
260 assert(predicate_x == NULL, "only one predicate entry expected");
261 predicate_c = NULL; // Do not clone predicate below merge point
262 }
263 if (predicate_x != NULL && ((len - req_c) > 2)) {
264 assert(predicate_c == NULL, "only one predicate entry expected");
265 predicate_x = NULL; // Do not clone predicate below merge point
266 }
268 // Register the new RegionNodes but do not transform them. Cannot
269 // transform until the entire Region/Phi conglomerate has been hacked
270 // as a single huge transform.
271 igvn->register_new_node_with_optimizer( region_c );
272 igvn->register_new_node_with_optimizer( region_x );
273 // Prevent the untimely death of phi_x. Currently he has no uses. He is
274 // about to get one. If this only use goes away, then phi_x will look dead.
275 // However, he will be picking up some more uses down below.
276 Node *hook = new (igvn->C) Node(4);
277 hook->init_req(0, phi_x);
278 hook->init_req(1, phi_c);
279 phi_x = phase->transform( phi_x );
281 // Make the compare
282 Node *cmp_c = phase->makecon(t);
283 Node *cmp_x = cmp->clone();
284 cmp_x->set_req(1,phi_x);
285 cmp_x->set_req(2,con2);
286 cmp_x = phase->transform(cmp_x);
287 // Make the bool
288 Node *b_c = phase->transform(new (igvn->C) BoolNode(cmp_c,b->_test._test));
289 Node *b_x = phase->transform(new (igvn->C) BoolNode(cmp_x,b->_test._test));
290 // Make the IfNode
291 IfNode *iff_c = new (igvn->C) IfNode(region_c,b_c,iff->_prob,iff->_fcnt);
292 igvn->set_type_bottom(iff_c);
293 igvn->_worklist.push(iff_c);
294 hook->init_req(2, iff_c);
296 IfNode *iff_x = new (igvn->C) IfNode(region_x,b_x,iff->_prob, iff->_fcnt);
297 igvn->set_type_bottom(iff_x);
298 igvn->_worklist.push(iff_x);
299 hook->init_req(3, iff_x);
301 // Make the true/false arms
302 Node *iff_c_t = phase->transform(new (igvn->C) IfTrueNode (iff_c));
303 Node *iff_c_f = phase->transform(new (igvn->C) IfFalseNode(iff_c));
304 if (predicate_c != NULL) {
305 assert(predicate_x == NULL, "only one predicate entry expected");
306 // Clone loop predicates to each path
307 iff_c_t = igvn->clone_loop_predicates(predicate_c, iff_c_t, !counted_loop);
308 iff_c_f = igvn->clone_loop_predicates(predicate_c, iff_c_f, !counted_loop);
309 }
310 Node *iff_x_t = phase->transform(new (igvn->C) IfTrueNode (iff_x));
311 Node *iff_x_f = phase->transform(new (igvn->C) IfFalseNode(iff_x));
312 if (predicate_x != NULL) {
313 assert(predicate_c == NULL, "only one predicate entry expected");
314 // Clone loop predicates to each path
315 iff_x_t = igvn->clone_loop_predicates(predicate_x, iff_x_t, !counted_loop);
316 iff_x_f = igvn->clone_loop_predicates(predicate_x, iff_x_f, !counted_loop);
317 }
319 // Merge the TRUE paths
320 Node *region_s = new (igvn->C) RegionNode(3);
321 igvn->_worklist.push(region_s);
322 region_s->init_req(1, iff_c_t);
323 region_s->init_req(2, iff_x_t);
324 igvn->register_new_node_with_optimizer( region_s );
326 // Merge the FALSE paths
327 Node *region_f = new (igvn->C) RegionNode(3);
328 igvn->_worklist.push(region_f);
329 region_f->init_req(1, iff_c_f);
330 region_f->init_req(2, iff_x_f);
331 igvn->register_new_node_with_optimizer( region_f );
333 igvn->hash_delete(cmp);// Remove soon-to-be-dead node from hash table.
334 cmp->set_req(1,NULL); // Whack the inputs to cmp because it will be dead
335 cmp->set_req(2,NULL);
336 // Check for all uses of the Phi and give them a new home.
337 // The 'cmp' got cloned, but CastPP/IIs need to be moved.
338 Node *phi_s = NULL; // do not construct unless needed
339 Node *phi_f = NULL; // do not construct unless needed
340 for (DUIterator_Last i2min, i2 = phi->last_outs(i2min); i2 >= i2min; --i2) {
341 Node* v = phi->last_out(i2);// User of the phi
342 igvn->rehash_node_delayed(v); // Have to fixup other Phi users
343 uint vop = v->Opcode();
344 Node *proj = NULL;
345 if( vop == Op_Phi ) { // Remote merge point
346 Node *r = v->in(0);
347 for (uint i3 = 1; i3 < r->req(); i3++)
348 if (r->in(i3) && r->in(i3)->in(0) == iff) {
349 proj = r->in(i3);
350 break;
351 }
352 } else if( v->is_ConstraintCast() ) {
353 proj = v->in(0); // Controlling projection
354 } else {
355 assert( 0, "do not know how to handle this guy" );
356 }
358 Node *proj_path_data, *proj_path_ctrl;
359 if( proj->Opcode() == Op_IfTrue ) {
360 if( phi_s == NULL ) {
361 // Only construct phi_s if needed, otherwise provides
362 // interfering use.
363 phi_s = PhiNode::make_blank(region_s,phi);
364 phi_s->init_req( 1, phi_c );
365 phi_s->init_req( 2, phi_x );
366 hook->add_req(phi_s);
367 phi_s = phase->transform(phi_s);
368 }
369 proj_path_data = phi_s;
370 proj_path_ctrl = region_s;
371 } else {
372 if( phi_f == NULL ) {
373 // Only construct phi_f if needed, otherwise provides
374 // interfering use.
375 phi_f = PhiNode::make_blank(region_f,phi);
376 phi_f->init_req( 1, phi_c );
377 phi_f->init_req( 2, phi_x );
378 hook->add_req(phi_f);
379 phi_f = phase->transform(phi_f);
380 }
381 proj_path_data = phi_f;
382 proj_path_ctrl = region_f;
383 }
385 // Fixup 'v' for for the split
386 if( vop == Op_Phi ) { // Remote merge point
387 uint i;
388 for( i = 1; i < v->req(); i++ )
389 if( v->in(i) == phi )
390 break;
391 v->set_req(i, proj_path_data );
392 } else if( v->is_ConstraintCast() ) {
393 v->set_req(0, proj_path_ctrl );
394 v->set_req(1, proj_path_data );
395 } else
396 ShouldNotReachHere();
397 }
399 // Now replace the original iff's True/False with region_s/region_t.
400 // This makes the original iff go dead.
401 for (DUIterator_Last i3min, i3 = iff->last_outs(i3min); i3 >= i3min; --i3) {
402 Node* p = iff->last_out(i3);
403 assert( p->Opcode() == Op_IfTrue || p->Opcode() == Op_IfFalse, "" );
404 Node *u = (p->Opcode() == Op_IfTrue) ? region_s : region_f;
405 // Replace p with u
406 igvn->add_users_to_worklist(p);
407 for (DUIterator_Last lmin, l = p->last_outs(lmin); l >= lmin;) {
408 Node* x = p->last_out(l);
409 igvn->hash_delete(x);
410 uint uses_found = 0;
411 for( uint j = 0; j < x->req(); j++ ) {
412 if( x->in(j) == p ) {
413 x->set_req(j, u);
414 uses_found++;
415 }
416 }
417 l -= uses_found; // we deleted 1 or more copies of this edge
418 }
419 igvn->remove_dead_node(p);
420 }
422 // Force the original merge dead
423 igvn->hash_delete(r);
424 // First, remove region's dead users.
425 for (DUIterator_Last lmin, l = r->last_outs(lmin); l >= lmin;) {
426 Node* u = r->last_out(l);
427 if( u == r ) {
428 r->set_req(0, NULL);
429 } else {
430 assert(u->outcnt() == 0, "only dead users");
431 igvn->remove_dead_node(u);
432 }
433 l -= 1;
434 }
435 igvn->remove_dead_node(r);
437 // Now remove the bogus extra edges used to keep things alive
438 igvn->remove_dead_node( hook );
440 // Must return either the original node (now dead) or a new node
441 // (Do not return a top here, since that would break the uniqueness of top.)
442 return new (igvn->C) ConINode(TypeInt::ZERO);
443 }
445 //------------------------------is_range_check---------------------------------
446 // Return 0 if not a range check. Return 1 if a range check and set index and
447 // offset. Return 2 if we had to negate the test. Index is NULL if the check
448 // is versus a constant.
449 int IfNode::is_range_check(Node* &range, Node* &index, jint &offset) {
450 Node* b = in(1);
451 if (b == NULL || !b->is_Bool()) return 0;
452 BoolNode* bn = b->as_Bool();
453 Node* cmp = bn->in(1);
454 if (cmp == NULL) return 0;
455 if (cmp->Opcode() != Op_CmpU) return 0;
457 Node* l = cmp->in(1);
458 Node* r = cmp->in(2);
459 int flip_test = 1;
460 if (bn->_test._test == BoolTest::le) {
461 l = cmp->in(2);
462 r = cmp->in(1);
463 flip_test = 2;
464 } else if (bn->_test._test != BoolTest::lt) {
465 return 0;
466 }
467 if (l->is_top()) return 0; // Top input means dead test
468 if (r->Opcode() != Op_LoadRange) return 0;
470 // We have recognized one of these forms:
471 // Flip 1: If (Bool[<] CmpU(l, LoadRange)) ...
472 // Flip 2: If (Bool[<=] CmpU(LoadRange, l)) ...
474 // Make sure it's a real range check by requiring an uncommon trap
475 // along the OOB path. Otherwise, it's possible that the user wrote
476 // something which optimized to look like a range check but behaves
477 // in some other way.
478 Node* iftrap = proj_out(flip_test == 2 ? true : false);
479 bool found_trap = false;
480 if (iftrap != NULL) {
481 Node* u = iftrap->unique_ctrl_out();
482 if (u != NULL) {
483 // It could be a merge point (Region) for uncommon trap.
484 if (u->is_Region()) {
485 Node* c = u->unique_ctrl_out();
486 if (c != NULL) {
487 iftrap = u;
488 u = c;
489 }
490 }
491 if (u->in(0) == iftrap && u->is_CallStaticJava()) {
492 int req = u->as_CallStaticJava()->uncommon_trap_request();
493 if (Deoptimization::trap_request_reason(req) ==
494 Deoptimization::Reason_range_check) {
495 found_trap = true;
496 }
497 }
498 }
499 }
500 if (!found_trap) return 0; // sorry, no cigar
502 // Look for index+offset form
503 Node* ind = l;
504 jint off = 0;
505 if (l->is_top()) {
506 return 0;
507 } else if (l->is_Add()) {
508 if ((off = l->in(1)->find_int_con(0)) != 0) {
509 ind = l->in(2);
510 } else if ((off = l->in(2)->find_int_con(0)) != 0) {
511 ind = l->in(1);
512 }
513 } else if ((off = l->find_int_con(-1)) >= 0) {
514 // constant offset with no variable index
515 ind = NULL;
516 } else {
517 // variable index with no constant offset (or dead negative index)
518 off = 0;
519 }
521 // Return all the values:
522 index = ind;
523 offset = off;
524 range = r;
525 return flip_test;
526 }
528 //------------------------------adjust_check-----------------------------------
529 // Adjust (widen) a prior range check
530 static void adjust_check(Node* proj, Node* range, Node* index,
531 int flip, jint off_lo, PhaseIterGVN* igvn) {
532 PhaseGVN *gvn = igvn;
533 // Break apart the old check
534 Node *iff = proj->in(0);
535 Node *bol = iff->in(1);
536 if( bol->is_top() ) return; // In case a partially dead range check appears
537 // bail (or bomb[ASSERT/DEBUG]) if NOT projection-->IfNode-->BoolNode
538 DEBUG_ONLY( if( !bol->is_Bool() ) { proj->dump(3); fatal("Expect projection-->IfNode-->BoolNode"); } )
539 if( !bol->is_Bool() ) return;
541 Node *cmp = bol->in(1);
542 // Compute a new check
543 Node *new_add = gvn->intcon(off_lo);
544 if( index ) {
545 new_add = off_lo ? gvn->transform(new (gvn->C) AddINode( index, new_add )) : index;
546 }
547 Node *new_cmp = (flip == 1)
548 ? new (gvn->C) CmpUNode( new_add, range )
549 : new (gvn->C) CmpUNode( range, new_add );
550 new_cmp = gvn->transform(new_cmp);
551 // See if no need to adjust the existing check
552 if( new_cmp == cmp ) return;
553 // Else, adjust existing check
554 Node *new_bol = gvn->transform( new (gvn->C) BoolNode( new_cmp, bol->as_Bool()->_test._test ) );
555 igvn->rehash_node_delayed( iff );
556 iff->set_req_X( 1, new_bol, igvn );
557 }
559 //------------------------------up_one_dom-------------------------------------
560 // Walk up the dominator tree one step. Return NULL at root or true
561 // complex merges. Skips through small diamonds.
562 Node* IfNode::up_one_dom(Node *curr, bool linear_only) {
563 Node *dom = curr->in(0);
564 if( !dom ) // Found a Region degraded to a copy?
565 return curr->nonnull_req(); // Skip thru it
567 if( curr != dom ) // Normal walk up one step?
568 return dom;
570 // Use linear_only if we are still parsing, since we cannot
571 // trust the regions to be fully filled in.
572 if (linear_only)
573 return NULL;
575 if( dom->is_Root() )
576 return NULL;
578 // Else hit a Region. Check for a loop header
579 if( dom->is_Loop() )
580 return dom->in(1); // Skip up thru loops
582 // Check for small diamonds
583 Node *din1, *din2, *din3, *din4;
584 if( dom->req() == 3 && // 2-path merge point
585 (din1 = dom ->in(1)) && // Left path exists
586 (din2 = dom ->in(2)) && // Right path exists
587 (din3 = din1->in(0)) && // Left path up one
588 (din4 = din2->in(0)) ) { // Right path up one
589 if( din3->is_Call() && // Handle a slow-path call on either arm
590 (din3 = din3->in(0)) )
591 din3 = din3->in(0);
592 if( din4->is_Call() && // Handle a slow-path call on either arm
593 (din4 = din4->in(0)) )
594 din4 = din4->in(0);
595 if( din3 == din4 && din3->is_If() )
596 return din3; // Skip around diamonds
597 }
599 // Give up the search at true merges
600 return NULL; // Dead loop? Or hit root?
601 }
604 //------------------------------filtered_int_type--------------------------------
605 // Return a possibly more restrictive type for val based on condition control flow for an if
606 const TypeInt* IfNode::filtered_int_type(PhaseGVN* gvn, Node *val, Node* if_proj) {
607 assert(if_proj &&
608 (if_proj->Opcode() == Op_IfTrue || if_proj->Opcode() == Op_IfFalse), "expecting an if projection");
609 if (if_proj->in(0) && if_proj->in(0)->is_If()) {
610 IfNode* iff = if_proj->in(0)->as_If();
611 if (iff->in(1) && iff->in(1)->is_Bool()) {
612 BoolNode* bol = iff->in(1)->as_Bool();
613 if (bol->in(1) && bol->in(1)->is_Cmp()) {
614 const CmpNode* cmp = bol->in(1)->as_Cmp();
615 if (cmp->in(1) == val) {
616 const TypeInt* cmp2_t = gvn->type(cmp->in(2))->isa_int();
617 if (cmp2_t != NULL) {
618 jint lo = cmp2_t->_lo;
619 jint hi = cmp2_t->_hi;
620 BoolTest::mask msk = if_proj->Opcode() == Op_IfTrue ? bol->_test._test : bol->_test.negate();
621 switch (msk) {
622 case BoolTest::ne:
623 // Can't refine type
624 return NULL;
625 case BoolTest::eq:
626 return cmp2_t;
627 case BoolTest::lt:
628 lo = TypeInt::INT->_lo;
629 if (hi - 1 < hi) {
630 hi = hi - 1;
631 }
632 break;
633 case BoolTest::le:
634 lo = TypeInt::INT->_lo;
635 break;
636 case BoolTest::gt:
637 if (lo + 1 > lo) {
638 lo = lo + 1;
639 }
640 hi = TypeInt::INT->_hi;
641 break;
642 case BoolTest::ge:
643 // lo unchanged
644 hi = TypeInt::INT->_hi;
645 break;
646 }
647 const TypeInt* rtn_t = TypeInt::make(lo, hi, cmp2_t->_widen);
648 return rtn_t;
649 }
650 }
651 }
652 }
653 }
654 return NULL;
655 }
657 //------------------------------fold_compares----------------------------
658 // See if a pair of CmpIs can be converted into a CmpU. In some cases
659 // the direction of this if is determined by the preceding if so it
660 // can be eliminate entirely. Given an if testing (CmpI n c) check
661 // for an immediately control dependent if that is testing (CmpI n c2)
662 // and has one projection leading to this if and the other projection
663 // leading to a region that merges one of this ifs control
664 // projections.
665 //
666 // If
667 // / |
668 // / |
669 // / |
670 // If |
671 // /\ |
672 // / \ |
673 // / \ |
674 // / Region
675 //
676 Node* IfNode::fold_compares(PhaseGVN* phase) {
677 if (!phase->C->eliminate_boxing() || Opcode() != Op_If) return NULL;
679 Node* this_cmp = in(1)->in(1);
680 if (this_cmp != NULL && this_cmp->Opcode() == Op_CmpI &&
681 this_cmp->in(2)->is_Con() && this_cmp->in(2) != phase->C->top()) {
682 Node* ctrl = in(0);
683 BoolNode* this_bool = in(1)->as_Bool();
684 Node* n = this_cmp->in(1);
685 int hi = this_cmp->in(2)->get_int();
686 if (ctrl != NULL && ctrl->is_Proj() && ctrl->outcnt() == 1 &&
687 ctrl->in(0)->is_If() &&
688 ctrl->in(0)->outcnt() == 2 &&
689 ctrl->in(0)->in(1)->is_Bool() &&
690 ctrl->in(0)->in(1)->in(1)->Opcode() == Op_CmpI &&
691 ctrl->in(0)->in(1)->in(1)->in(2)->is_Con() &&
692 ctrl->in(0)->in(1)->in(1)->in(2) != phase->C->top() &&
693 ctrl->in(0)->in(1)->in(1)->in(1) == n) {
694 IfNode* dom_iff = ctrl->in(0)->as_If();
695 Node* otherproj = dom_iff->proj_out(!ctrl->as_Proj()->_con);
696 if (otherproj->outcnt() == 1 && otherproj->unique_out()->is_Region() &&
697 this_bool->_test._test != BoolTest::ne && this_bool->_test._test != BoolTest::eq) {
698 // Identify which proj goes to the region and which continues on
699 RegionNode* region = otherproj->unique_out()->as_Region();
700 Node* success = NULL;
701 Node* fail = NULL;
702 for (int i = 0; i < 2; i++) {
703 Node* proj = proj_out(i);
704 if (success == NULL && proj->outcnt() == 1 && proj->unique_out() == region) {
705 success = proj;
706 } else if (fail == NULL) {
707 fail = proj;
708 } else {
709 success = fail = NULL;
710 }
711 }
712 if (success != NULL && fail != NULL && !region->has_phi()) {
713 int lo = dom_iff->in(1)->in(1)->in(2)->get_int();
714 BoolNode* dom_bool = dom_iff->in(1)->as_Bool();
715 Node* dom_cmp = dom_bool->in(1);
716 const TypeInt* failtype = filtered_int_type(phase, n, ctrl);
717 if (failtype != NULL) {
718 const TypeInt* type2 = filtered_int_type(phase, n, fail);
719 if (type2 != NULL) {
720 failtype = failtype->join(type2)->is_int();
721 } else {
722 failtype = NULL;
723 }
724 }
726 if (failtype != NULL &&
727 dom_bool->_test._test != BoolTest::ne && dom_bool->_test._test != BoolTest::eq) {
728 int bound = failtype->_hi - failtype->_lo + 1;
729 if (failtype->_hi != max_jint && failtype->_lo != min_jint && bound > 1) {
730 // Merge the two compares into a single unsigned compare by building (CmpU (n - lo) hi)
731 BoolTest::mask cond = fail->as_Proj()->_con ? BoolTest::lt : BoolTest::ge;
732 Node* adjusted = phase->transform(new (phase->C) SubINode(n, phase->intcon(failtype->_lo)));
733 Node* newcmp = phase->transform(new (phase->C) CmpUNode(adjusted, phase->intcon(bound)));
734 Node* newbool = phase->transform(new (phase->C) BoolNode(newcmp, cond));
735 phase->is_IterGVN()->replace_input_of(dom_iff, 1, phase->intcon(ctrl->as_Proj()->_con));
736 phase->hash_delete(this);
737 set_req(1, newbool);
738 return this;
739 }
740 if (failtype->_lo > failtype->_hi) {
741 // previous if determines the result of this if so
742 // replace Bool with constant
743 phase->hash_delete(this);
744 set_req(1, phase->intcon(success->as_Proj()->_con));
745 return this;
746 }
747 }
748 }
749 }
750 }
751 }
752 return NULL;
753 }
755 //------------------------------remove_useless_bool----------------------------
756 // Check for people making a useless boolean: things like
757 // if( (x < y ? true : false) ) { ... }
758 // Replace with if( x < y ) { ... }
759 static Node *remove_useless_bool(IfNode *iff, PhaseGVN *phase) {
760 Node *i1 = iff->in(1);
761 if( !i1->is_Bool() ) return NULL;
762 BoolNode *bol = i1->as_Bool();
764 Node *cmp = bol->in(1);
765 if( cmp->Opcode() != Op_CmpI ) return NULL;
767 // Must be comparing against a bool
768 const Type *cmp2_t = phase->type( cmp->in(2) );
769 if( cmp2_t != TypeInt::ZERO &&
770 cmp2_t != TypeInt::ONE )
771 return NULL;
773 // Find a prior merge point merging the boolean
774 i1 = cmp->in(1);
775 if( !i1->is_Phi() ) return NULL;
776 PhiNode *phi = i1->as_Phi();
777 if( phase->type( phi ) != TypeInt::BOOL )
778 return NULL;
780 // Check for diamond pattern
781 int true_path = phi->is_diamond_phi();
782 if( true_path == 0 ) return NULL;
784 // Make sure that iff and the control of the phi are different. This
785 // should really only happen for dead control flow since it requires
786 // an illegal cycle.
787 if (phi->in(0)->in(1)->in(0) == iff) return NULL;
789 // phi->region->if_proj->ifnode->bool->cmp
790 BoolNode *bol2 = phi->in(0)->in(1)->in(0)->in(1)->as_Bool();
792 // Now get the 'sense' of the test correct so we can plug in
793 // either iff2->in(1) or its complement.
794 int flip = 0;
795 if( bol->_test._test == BoolTest::ne ) flip = 1-flip;
796 else if( bol->_test._test != BoolTest::eq ) return NULL;
797 if( cmp2_t == TypeInt::ZERO ) flip = 1-flip;
799 const Type *phi1_t = phase->type( phi->in(1) );
800 const Type *phi2_t = phase->type( phi->in(2) );
801 // Check for Phi(0,1) and flip
802 if( phi1_t == TypeInt::ZERO ) {
803 if( phi2_t != TypeInt::ONE ) return NULL;
804 flip = 1-flip;
805 } else {
806 // Check for Phi(1,0)
807 if( phi1_t != TypeInt::ONE ) return NULL;
808 if( phi2_t != TypeInt::ZERO ) return NULL;
809 }
810 if( true_path == 2 ) {
811 flip = 1-flip;
812 }
814 Node* new_bol = (flip ? phase->transform( bol2->negate(phase) ) : bol2);
815 assert(new_bol != iff->in(1), "must make progress");
816 iff->set_req(1, new_bol);
817 // Intervening diamond probably goes dead
818 phase->C->set_major_progress();
819 return iff;
820 }
822 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff);
824 //------------------------------Ideal------------------------------------------
825 // Return a node which is more "ideal" than the current node. Strip out
826 // control copies
827 Node *IfNode::Ideal(PhaseGVN *phase, bool can_reshape) {
828 if (remove_dead_region(phase, can_reshape)) return this;
829 // No Def-Use info?
830 if (!can_reshape) return NULL;
831 PhaseIterGVN *igvn = phase->is_IterGVN();
833 // Don't bother trying to transform a dead if
834 if (in(0)->is_top()) return NULL;
835 // Don't bother trying to transform an if with a dead test
836 if (in(1)->is_top()) return NULL;
837 // Another variation of a dead test
838 if (in(1)->is_Con()) return NULL;
839 // Another variation of a dead if
840 if (outcnt() < 2) return NULL;
842 // Canonicalize the test.
843 Node* idt_if = idealize_test(phase, this);
844 if (idt_if != NULL) return idt_if;
846 // Try to split the IF
847 Node *s = split_if(this, igvn);
848 if (s != NULL) return s;
850 // Check for people making a useless boolean: things like
851 // if( (x < y ? true : false) ) { ... }
852 // Replace with if( x < y ) { ... }
853 Node *bol2 = remove_useless_bool(this, phase);
854 if( bol2 ) return bol2;
856 // Setup to scan up the CFG looking for a dominating test
857 Node *dom = in(0);
858 Node *prev_dom = this;
860 // Check for range-check vs other kinds of tests
861 Node *index1, *range1;
862 jint offset1;
863 int flip1 = is_range_check(range1, index1, offset1);
864 if( flip1 ) {
865 Node *first_prev_dom = NULL;
867 // Try to remove extra range checks. All 'up_one_dom' gives up at merges
868 // so all checks we inspect post-dominate the top-most check we find.
869 // If we are going to fail the current check and we reach the top check
870 // then we are guaranteed to fail, so just start interpreting there.
871 // We 'expand' the top 2 range checks to include all post-dominating
872 // checks.
874 // The top 2 range checks seen
875 Node *prev_chk1 = NULL;
876 Node *prev_chk2 = NULL;
877 // Low and high offsets seen so far
878 jint off_lo = offset1;
879 jint off_hi = offset1;
881 // Scan for the top 2 checks and collect range of offsets
882 for( int dist = 0; dist < 999; dist++ ) { // Range-Check scan limit
883 if( dom->Opcode() == Op_If && // Not same opcode?
884 prev_dom->in(0) == dom ) { // One path of test does dominate?
885 if( dom == this ) return NULL; // dead loop
886 // See if this is a range check
887 Node *index2, *range2;
888 jint offset2;
889 int flip2 = dom->as_If()->is_range_check(range2, index2, offset2);
890 // See if this is a _matching_ range check, checking against
891 // the same array bounds.
892 if( flip2 == flip1 && range2 == range1 && index2 == index1 &&
893 dom->outcnt() == 2 ) {
894 // Gather expanded bounds
895 off_lo = MIN2(off_lo,offset2);
896 off_hi = MAX2(off_hi,offset2);
897 // Record top 2 range checks
898 prev_chk2 = prev_chk1;
899 prev_chk1 = prev_dom;
900 // If we match the test exactly, then the top test covers
901 // both our lower and upper bounds.
902 if( dom->in(1) == in(1) )
903 prev_chk2 = prev_chk1;
904 }
905 }
906 prev_dom = dom;
907 dom = up_one_dom( dom );
908 if( !dom ) break;
909 }
912 // Attempt to widen the dominating range check to cover some later
913 // ones. Since range checks "fail" by uncommon-trapping to the
914 // interpreter, widening a check can make us speculative enter the
915 // interpreter. If we see range-check deopt's, do not widen!
916 if (!phase->C->allow_range_check_smearing()) return NULL;
918 // Constant indices only need to check the upper bound.
919 // Non-constance indices must check both low and high.
920 if( index1 ) {
921 // Didn't find 2 prior covering checks, so cannot remove anything.
922 if( !prev_chk2 ) return NULL;
923 // 'Widen' the offsets of the 1st and 2nd covering check
924 adjust_check( prev_chk1, range1, index1, flip1, off_lo, igvn );
925 // Do not call adjust_check twice on the same projection
926 // as the first call may have transformed the BoolNode to a ConI
927 if( prev_chk1 != prev_chk2 ) {
928 adjust_check( prev_chk2, range1, index1, flip1, off_hi, igvn );
929 }
930 // Test is now covered by prior checks, dominate it out
931 prev_dom = prev_chk2;
932 } else {
933 // Didn't find prior covering check, so cannot remove anything.
934 if( !prev_chk1 ) return NULL;
935 // 'Widen' the offset of the 1st and only covering check
936 adjust_check( prev_chk1, range1, index1, flip1, off_hi, igvn );
937 // Test is now covered by prior checks, dominate it out
938 prev_dom = prev_chk1;
939 }
942 } else { // Scan for an equivalent test
944 Node *cmp;
945 int dist = 0; // Cutoff limit for search
946 int op = Opcode();
947 if( op == Op_If &&
948 (cmp=in(1)->in(1))->Opcode() == Op_CmpP ) {
949 if( cmp->in(2) != NULL && // make sure cmp is not already dead
950 cmp->in(2)->bottom_type() == TypePtr::NULL_PTR ) {
951 dist = 64; // Limit for null-pointer scans
952 } else {
953 dist = 4; // Do not bother for random pointer tests
954 }
955 } else {
956 dist = 4; // Limit for random junky scans
957 }
959 // Normal equivalent-test check.
960 if( !dom ) return NULL; // Dead loop?
962 Node* result = fold_compares(phase);
963 if (result != NULL) {
964 return result;
965 }
967 // Search up the dominator tree for an If with an identical test
968 while( dom->Opcode() != op || // Not same opcode?
969 dom->in(1) != in(1) || // Not same input 1?
970 (req() == 3 && dom->in(2) != in(2)) || // Not same input 2?
971 prev_dom->in(0) != dom ) { // One path of test does not dominate?
972 if( dist < 0 ) return NULL;
974 dist--;
975 prev_dom = dom;
976 dom = up_one_dom( dom );
977 if( !dom ) return NULL;
978 }
980 // Check that we did not follow a loop back to ourselves
981 if( this == dom )
982 return NULL;
984 if( dist > 2 ) // Add to count of NULL checks elided
985 explicit_null_checks_elided++;
987 } // End of Else scan for an equivalent test
989 // Hit! Remove this IF
990 #ifndef PRODUCT
991 if( TraceIterativeGVN ) {
992 tty->print(" Removing IfNode: "); this->dump();
993 }
994 if( VerifyOpto && !phase->allow_progress() ) {
995 // Found an equivalent dominating test,
996 // we can not guarantee reaching a fix-point for these during iterativeGVN
997 // since intervening nodes may not change.
998 return NULL;
999 }
1000 #endif
1002 // Replace dominated IfNode
1003 dominated_by( prev_dom, igvn );
1005 // Must return either the original node (now dead) or a new node
1006 // (Do not return a top here, since that would break the uniqueness of top.)
1007 return new (phase->C) ConINode(TypeInt::ZERO);
1008 }
1010 //------------------------------dominated_by-----------------------------------
1011 void IfNode::dominated_by( Node *prev_dom, PhaseIterGVN *igvn ) {
1012 igvn->hash_delete(this); // Remove self to prevent spurious V-N
1013 Node *idom = in(0);
1014 // Need opcode to decide which way 'this' test goes
1015 int prev_op = prev_dom->Opcode();
1016 Node *top = igvn->C->top(); // Shortcut to top
1018 // Loop predicates may have depending checks which should not
1019 // be skipped. For example, range check predicate has two checks
1020 // for lower and upper bounds.
1021 ProjNode* unc_proj = proj_out(1 - prev_dom->as_Proj()->_con)->as_Proj();
1022 if (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate))
1023 prev_dom = idom;
1025 // Now walk the current IfNode's projections.
1026 // Loop ends when 'this' has no more uses.
1027 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
1028 Node *ifp = last_out(i); // Get IfTrue/IfFalse
1029 igvn->add_users_to_worklist(ifp);
1030 // Check which projection it is and set target.
1031 // Data-target is either the dominating projection of the same type
1032 // or TOP if the dominating projection is of opposite type.
1033 // Data-target will be used as the new control edge for the non-CFG
1034 // nodes like Casts and Loads.
1035 Node *data_target = (ifp->Opcode() == prev_op) ? prev_dom : top;
1036 // Control-target is just the If's immediate dominator or TOP.
1037 Node *ctrl_target = (ifp->Opcode() == prev_op) ? idom : top;
1039 // For each child of an IfTrue/IfFalse projection, reroute.
1040 // Loop ends when projection has no more uses.
1041 for (DUIterator_Last jmin, j = ifp->last_outs(jmin); j >= jmin; --j) {
1042 Node* s = ifp->last_out(j); // Get child of IfTrue/IfFalse
1043 if( !s->depends_only_on_test() ) {
1044 // Find the control input matching this def-use edge.
1045 // For Regions it may not be in slot 0.
1046 uint l;
1047 for( l = 0; s->in(l) != ifp; l++ ) { }
1048 igvn->replace_input_of(s, l, ctrl_target);
1049 } else { // Else, for control producers,
1050 igvn->replace_input_of(s, 0, data_target); // Move child to data-target
1051 }
1052 } // End for each child of a projection
1054 igvn->remove_dead_node(ifp);
1055 } // End for each IfTrue/IfFalse child of If
1057 // Kill the IfNode
1058 igvn->remove_dead_node(this);
1059 }
1061 //------------------------------Identity---------------------------------------
1062 // If the test is constant & we match, then we are the input Control
1063 Node *IfTrueNode::Identity( PhaseTransform *phase ) {
1064 // Can only optimize if cannot go the other way
1065 const TypeTuple *t = phase->type(in(0))->is_tuple();
1066 return ( t == TypeTuple::IFNEITHER || t == TypeTuple::IFTRUE )
1067 ? in(0)->in(0) // IfNode control
1068 : this; // no progress
1069 }
1071 //------------------------------dump_spec--------------------------------------
1072 #ifndef PRODUCT
1073 void IfNode::dump_spec(outputStream *st) const {
1074 st->print("P=%f, C=%f",_prob,_fcnt);
1075 }
1076 #endif
1078 //------------------------------idealize_test----------------------------------
1079 // Try to canonicalize tests better. Peek at the Cmp/Bool/If sequence and
1080 // come up with a canonical sequence. Bools getting 'eq', 'gt' and 'ge' forms
1081 // converted to 'ne', 'le' and 'lt' forms. IfTrue/IfFalse get swapped as
1082 // needed.
1083 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff) {
1084 assert(iff->in(0) != NULL, "If must be live");
1086 if (iff->outcnt() != 2) return NULL; // Malformed projections.
1087 Node* old_if_f = iff->proj_out(false);
1088 Node* old_if_t = iff->proj_out(true);
1090 // CountedLoopEnds want the back-control test to be TRUE, irregardless of
1091 // whether they are testing a 'gt' or 'lt' condition. The 'gt' condition
1092 // happens in count-down loops
1093 if (iff->is_CountedLoopEnd()) return NULL;
1094 if (!iff->in(1)->is_Bool()) return NULL; // Happens for partially optimized IF tests
1095 BoolNode *b = iff->in(1)->as_Bool();
1096 BoolTest bt = b->_test;
1097 // Test already in good order?
1098 if( bt.is_canonical() )
1099 return NULL;
1101 // Flip test to be canonical. Requires flipping the IfFalse/IfTrue and
1102 // cloning the IfNode.
1103 Node* new_b = phase->transform( new (phase->C) BoolNode(b->in(1), bt.negate()) );
1104 if( !new_b->is_Bool() ) return NULL;
1105 b = new_b->as_Bool();
1107 PhaseIterGVN *igvn = phase->is_IterGVN();
1108 assert( igvn, "Test is not canonical in parser?" );
1110 // The IF node never really changes, but it needs to be cloned
1111 iff = new (phase->C) IfNode( iff->in(0), b, 1.0-iff->_prob, iff->_fcnt);
1113 Node *prior = igvn->hash_find_insert(iff);
1114 if( prior ) {
1115 igvn->remove_dead_node(iff);
1116 iff = (IfNode*)prior;
1117 } else {
1118 // Cannot call transform on it just yet
1119 igvn->set_type_bottom(iff);
1120 }
1121 igvn->_worklist.push(iff);
1123 // Now handle projections. Cloning not required.
1124 Node* new_if_f = (Node*)(new (phase->C) IfFalseNode( iff ));
1125 Node* new_if_t = (Node*)(new (phase->C) IfTrueNode ( iff ));
1127 igvn->register_new_node_with_optimizer(new_if_f);
1128 igvn->register_new_node_with_optimizer(new_if_t);
1129 // Flip test, so flip trailing control
1130 igvn->replace_node(old_if_f, new_if_t);
1131 igvn->replace_node(old_if_t, new_if_f);
1133 // Progress
1134 return iff;
1135 }
1137 //------------------------------Identity---------------------------------------
1138 // If the test is constant & we match, then we are the input Control
1139 Node *IfFalseNode::Identity( PhaseTransform *phase ) {
1140 // Can only optimize if cannot go the other way
1141 const TypeTuple *t = phase->type(in(0))->is_tuple();
1142 return ( t == TypeTuple::IFNEITHER || t == TypeTuple::IFFALSE )
1143 ? in(0)->in(0) // IfNode control
1144 : this; // no progress
1145 }