1 /*
2 * Copyright (c) 2000, 2022, 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.
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23 */
24
25 #include "precompiled.hpp"
26 #include "ci/ciTypeFlow.hpp"
27 #include "memory/allocation.inline.hpp"
28 #include "memory/resourceArea.hpp"
29 #include "opto/addnode.hpp"
30 #include "opto/castnode.hpp"
31 #include "opto/cfgnode.hpp"
32 #include "opto/connode.hpp"
33 #include "opto/loopnode.hpp"
34 #include "opto/phaseX.hpp"
35 #include "opto/runtime.hpp"
36 #include "opto/rootnode.hpp"
37 #include "opto/subnode.hpp"
38
39 // Portions of code courtesy of Clifford Click
40
41 // Optimization - Graph Style
42
43
44 #ifndef PRODUCT
45 extern int explicit_null_checks_elided;
46 #endif
47
48 //=============================================================================
49 //------------------------------Value------------------------------------------
50 // Return a tuple for whichever arm of the IF is reachable
51 const Type* IfNode::Value(PhaseGVN* phase) const {
52 if( !in(0) ) return Type::TOP;
53 if( phase->type(in(0)) == Type::TOP )
54 return Type::TOP;
55 const Type *t = phase->type(in(1));
56 if( t == Type::TOP ) // data is undefined
57 return TypeTuple::IFNEITHER; // unreachable altogether
58 if( t == TypeInt::ZERO ) // zero, or false
59 return TypeTuple::IFFALSE; // only false branch is reachable
60 if( t == TypeInt::ONE ) // 1, or true
61 return TypeTuple::IFTRUE; // only true branch is reachable
62 assert( t == TypeInt::BOOL, "expected boolean type" );
63
64 return TypeTuple::IFBOTH; // No progress
65 }
66
67 const RegMask &IfNode::out_RegMask() const {
68 return RegMask::Empty;
69 }
70
71 //------------------------------split_if---------------------------------------
72 // Look for places where we merge constants, then test on the merged value.
73 // If the IF test will be constant folded on the path with the constant, we
74 // win by splitting the IF to before the merge point.
75 static Node* split_if(IfNode *iff, PhaseIterGVN *igvn) {
76 // I could be a lot more general here, but I'm trying to squeeze this
77 // in before the Christmas '98 break so I'm gonna be kinda restrictive
78 // on the patterns I accept. CNC
79
80 // Look for a compare of a constant and a merged value
81 Node *i1 = iff->in(1);
82 if( !i1->is_Bool() ) return NULL;
83 BoolNode *b = i1->as_Bool();
84 Node *cmp = b->in(1);
85 if( !cmp->is_Cmp() ) return NULL;
86 i1 = cmp->in(1);
87 if( i1 == NULL || !i1->is_Phi() ) return NULL;
88 PhiNode *phi = i1->as_Phi();
89 Node *con2 = cmp->in(2);
90 if( !con2->is_Con() ) return NULL;
91 // See that the merge point contains some constants
92 Node *con1=NULL;
93 uint i4;
94 for( i4 = 1; i4 < phi->req(); i4++ ) {
95 con1 = phi->in(i4);
96 if( !con1 ) return NULL; // Do not optimize partially collapsed merges
97 if( con1->is_Con() ) break; // Found a constant
98 // Also allow null-vs-not-null checks
99 const TypePtr *tp = igvn->type(con1)->isa_ptr();
100 if( tp && tp->_ptr == TypePtr::NotNull )
101 break;
102 }
103 if( i4 >= phi->req() ) return NULL; // Found no constants
104
105 igvn->C->set_has_split_ifs(true); // Has chance for split-if
106
107 // Make sure that the compare can be constant folded away
108 Node *cmp2 = cmp->clone();
109 cmp2->set_req(1,con1);
110 cmp2->set_req(2,con2);
111 const Type *t = cmp2->Value(igvn);
112 // This compare is dead, so whack it!
113 igvn->remove_dead_node(cmp2);
114 if( !t->singleton() ) return NULL;
115
116 // No intervening control, like a simple Call
117 Node* r = iff->in(0);
118 if (!r->is_Region() || r->is_Loop() || phi->region() != r || r->as_Region()->is_copy()) {
119 return NULL;
120 }
121
122 // No other users of the cmp/bool
123 if (b->outcnt() != 1 || cmp->outcnt() != 1) {
124 //tty->print_cr("many users of cmp/bool");
125 return NULL;
126 }
127
128 // Make sure we can determine where all the uses of merged values go
129 for (DUIterator_Fast jmax, j = r->fast_outs(jmax); j < jmax; j++) {
130 Node* u = r->fast_out(j);
131 if( u == r ) continue;
132 if( u == iff ) continue;
133 if( u->outcnt() == 0 ) continue; // use is dead & ignorable
134 if( !u->is_Phi() ) {
135 /*
136 if( u->is_Start() ) {
137 tty->print_cr("Region has inlined start use");
138 } else {
139 tty->print_cr("Region has odd use");
140 u->dump(2);
141 }*/
142 return NULL;
143 }
144 if( u != phi ) {
145 // CNC - do not allow any other merged value
146 //tty->print_cr("Merging another value");
147 //u->dump(2);
148 return NULL;
149 }
150 // Make sure we can account for all Phi uses
151 for (DUIterator_Fast kmax, k = u->fast_outs(kmax); k < kmax; k++) {
152 Node* v = u->fast_out(k); // User of the phi
153 // CNC - Allow only really simple patterns.
154 // In particular I disallow AddP of the Phi, a fairly common pattern
155 if (v == cmp) continue; // The compare is OK
156 if (v->is_ConstraintCast()) {
157 // If the cast is derived from data flow edges, it may not have a control edge.
158 // If so, it should be safe to split. But follow-up code can not deal with
159 // this (l. 359). So skip.
160 if (v->in(0) == NULL) {
161 return NULL;
162 }
163 if (v->in(0)->in(0) == iff) {
164 continue; // CastPP/II of the IfNode is OK
165 }
166 }
167 // Disabled following code because I cannot tell if exactly one
168 // path dominates without a real dominator check. CNC 9/9/1999
169 //uint vop = v->Opcode();
170 //if( vop == Op_Phi ) { // Phi from another merge point might be OK
171 // Node *r = v->in(0); // Get controlling point
172 // if( !r ) return NULL; // Degraded to a copy
173 // // Find exactly one path in (either True or False doms, but not IFF)
174 // int cnt = 0;
175 // for( uint i = 1; i < r->req(); i++ )
176 // if( r->in(i) && r->in(i)->in(0) == iff )
177 // cnt++;
178 // if( cnt == 1 ) continue; // Exactly one of True or False guards Phi
179 //}
180 if( !v->is_Call() ) {
181 /*
182 if( v->Opcode() == Op_AddP ) {
183 tty->print_cr("Phi has AddP use");
184 } else if( v->Opcode() == Op_CastPP ) {
185 tty->print_cr("Phi has CastPP use");
186 } else if( v->Opcode() == Op_CastII ) {
187 tty->print_cr("Phi has CastII use");
188 } else {
189 tty->print_cr("Phi has use I can't be bothered with");
190 }
191 */
192 }
193 return NULL;
194
195 /* CNC - Cut out all the fancy acceptance tests
196 // Can we clone this use when doing the transformation?
197 // If all uses are from Phis at this merge or constants, then YES.
198 if( !v->in(0) && v != cmp ) {
199 tty->print_cr("Phi has free-floating use");
200 v->dump(2);
201 return NULL;
202 }
203 for( uint l = 1; l < v->req(); l++ ) {
204 if( (!v->in(l)->is_Phi() || v->in(l)->in(0) != r) &&
205 !v->in(l)->is_Con() ) {
206 tty->print_cr("Phi has use");
207 v->dump(2);
208 return NULL;
209 } // End of if Phi-use input is neither Phi nor Constant
210 } // End of for all inputs to Phi-use
211 */
212 } // End of for all uses of Phi
213 } // End of for all uses of Region
214
215 // Only do this if the IF node is in a sane state
216 if (iff->outcnt() != 2)
217 return NULL;
218
219 // Got a hit! Do the Mondo Hack!
220 //
221 //ABC a1c def ghi B 1 e h A C a c d f g i
222 // R - Phi - Phi - Phi Rc - Phi - Phi - Phi Rx - Phi - Phi - Phi
223 // cmp - 2 cmp - 2 cmp - 2
224 // bool bool_c bool_x
225 // if if_c if_x
226 // T F T F T F
227 // ..s.. ..t .. ..s.. ..t.. ..s.. ..t..
228 //
229 // Split the paths coming into the merge point into 2 separate groups of
230 // merges. On the left will be all the paths feeding constants into the
231 // Cmp's Phi. On the right will be the remaining paths. The Cmp's Phi
232 // will fold up into a constant; this will let the Cmp fold up as well as
233 // all the control flow. Below the original IF we have 2 control
234 // dependent regions, 's' and 't'. Now we will merge the two paths
235 // just prior to 's' and 't' from the two IFs. At least 1 path (and quite
236 // likely 2 or more) will promptly constant fold away.
237 PhaseGVN *phase = igvn;
238
239 // Make a region merging constants and a region merging the rest
240 uint req_c = 0;
241 for (uint ii = 1; ii < r->req(); ii++) {
242 if (phi->in(ii) == con1) {
243 req_c++;
244 }
245 Node* proj = PhaseIdealLoop::find_predicate(r->in(ii));
246 if (proj != NULL) {
247 // Bail out if splitting through a region with a predicate input (could
248 // also be a loop header before loop opts creates a LoopNode for it).
249 return NULL;
250 }
251 }
252
253 // If all the defs of the phi are the same constant, we already have the desired end state.
254 // Skip the split that would create empty phi and region nodes.
255 if ((r->req() - req_c) == 1) {
256 return NULL;
257 }
258
259 // At this point we know that we can apply the split if optimization. If the region is still on the worklist,
260 // we should wait until it is processed. The region might be removed which makes this optimization redundant.
261 // This also avoids the creation of dead data loops when rewiring data nodes below when a region is dying.
262 if (igvn->_worklist.member(r)) {
263 igvn->_worklist.push(iff); // retry split if later again
264 return NULL;
265 }
266
267 Node *region_c = new RegionNode(req_c + 1);
268 Node *phi_c = con1;
269 uint len = r->req();
270 Node *region_x = new RegionNode(len - req_c);
271 Node *phi_x = PhiNode::make_blank(region_x, phi);
272 for (uint i = 1, i_c = 1, i_x = 1; i < len; i++) {
273 if (phi->in(i) == con1) {
274 region_c->init_req( i_c++, r ->in(i) );
275 } else {
276 region_x->init_req( i_x, r ->in(i) );
277 phi_x ->init_req( i_x++, phi->in(i) );
278 }
279 }
280
281 // Register the new RegionNodes but do not transform them. Cannot
282 // transform until the entire Region/Phi conglomerate has been hacked
283 // as a single huge transform.
284 igvn->register_new_node_with_optimizer( region_c );
285 igvn->register_new_node_with_optimizer( region_x );
286 // Prevent the untimely death of phi_x. Currently he has no uses. He is
287 // about to get one. If this only use goes away, then phi_x will look dead.
288 // However, he will be picking up some more uses down below.
289 Node *hook = new Node(4);
290 hook->init_req(0, phi_x);
291 hook->init_req(1, phi_c);
292 phi_x = phase->transform( phi_x );
293
294 // Make the compare
295 Node *cmp_c = phase->makecon(t);
296 Node *cmp_x = cmp->clone();
297 cmp_x->set_req(1,phi_x);
298 cmp_x->set_req(2,con2);
299 cmp_x = phase->transform(cmp_x);
300 // Make the bool
301 Node *b_c = phase->transform(new BoolNode(cmp_c,b->_test._test));
302 Node *b_x = phase->transform(new BoolNode(cmp_x,b->_test._test));
303 // Make the IfNode
304 IfNode* iff_c = iff->clone()->as_If();
305 iff_c->set_req(0, region_c);
306 iff_c->set_req(1, b_c);
307 igvn->set_type_bottom(iff_c);
308 igvn->_worklist.push(iff_c);
309 hook->init_req(2, iff_c);
310
311 IfNode* iff_x = iff->clone()->as_If();
312 iff_x->set_req(0, region_x);
313 iff_x->set_req(1, b_x);
314 igvn->set_type_bottom(iff_x);
315 igvn->_worklist.push(iff_x);
316 hook->init_req(3, iff_x);
317
318 // Make the true/false arms
319 Node *iff_c_t = phase->transform(new IfTrueNode (iff_c));
320 Node *iff_c_f = phase->transform(new IfFalseNode(iff_c));
321 Node *iff_x_t = phase->transform(new IfTrueNode (iff_x));
322 Node *iff_x_f = phase->transform(new IfFalseNode(iff_x));
323
324 // Merge the TRUE paths
325 Node *region_s = new RegionNode(3);
326 igvn->_worklist.push(region_s);
327 region_s->init_req(1, iff_c_t);
328 region_s->init_req(2, iff_x_t);
329 igvn->register_new_node_with_optimizer( region_s );
330
331 // Merge the FALSE paths
332 Node *region_f = new RegionNode(3);
333 igvn->_worklist.push(region_f);
334 region_f->init_req(1, iff_c_f);
335 region_f->init_req(2, iff_x_f);
336 igvn->register_new_node_with_optimizer( region_f );
337
338 igvn->hash_delete(cmp);// Remove soon-to-be-dead node from hash table.
339 cmp->set_req(1,NULL); // Whack the inputs to cmp because it will be dead
340 cmp->set_req(2,NULL);
341 // Check for all uses of the Phi and give them a new home.
342 // The 'cmp' got cloned, but CastPP/IIs need to be moved.
343 Node *phi_s = NULL; // do not construct unless needed
344 Node *phi_f = NULL; // do not construct unless needed
345 for (DUIterator_Last i2min, i2 = phi->last_outs(i2min); i2 >= i2min; --i2) {
346 Node* v = phi->last_out(i2);// User of the phi
347 igvn->rehash_node_delayed(v); // Have to fixup other Phi users
348 uint vop = v->Opcode();
349 Node *proj = NULL;
350 if( vop == Op_Phi ) { // Remote merge point
351 Node *r = v->in(0);
352 for (uint i3 = 1; i3 < r->req(); i3++)
353 if (r->in(i3) && r->in(i3)->in(0) == iff) {
354 proj = r->in(i3);
355 break;
356 }
357 } else if( v->is_ConstraintCast() ) {
358 proj = v->in(0); // Controlling projection
359 } else {
360 assert( 0, "do not know how to handle this guy" );
361 }
362 guarantee(proj != NULL, "sanity");
363
364 Node *proj_path_data, *proj_path_ctrl;
365 if( proj->Opcode() == Op_IfTrue ) {
366 if( phi_s == NULL ) {
367 // Only construct phi_s if needed, otherwise provides
368 // interfering use.
369 phi_s = PhiNode::make_blank(region_s,phi);
370 phi_s->init_req( 1, phi_c );
371 phi_s->init_req( 2, phi_x );
372 hook->add_req(phi_s);
373 phi_s = phase->transform(phi_s);
374 }
375 proj_path_data = phi_s;
376 proj_path_ctrl = region_s;
377 } else {
378 if( phi_f == NULL ) {
379 // Only construct phi_f if needed, otherwise provides
380 // interfering use.
381 phi_f = PhiNode::make_blank(region_f,phi);
382 phi_f->init_req( 1, phi_c );
383 phi_f->init_req( 2, phi_x );
384 hook->add_req(phi_f);
385 phi_f = phase->transform(phi_f);
386 }
387 proj_path_data = phi_f;
388 proj_path_ctrl = region_f;
389 }
390
391 // Fixup 'v' for for the split
392 if( vop == Op_Phi ) { // Remote merge point
393 uint i;
394 for( i = 1; i < v->req(); i++ )
395 if( v->in(i) == phi )
396 break;
397 v->set_req(i, proj_path_data );
398 } else if( v->is_ConstraintCast() ) {
399 v->set_req(0, proj_path_ctrl );
400 v->set_req(1, proj_path_data );
401 } else
402 ShouldNotReachHere();
403 }
404
405 // Now replace the original iff's True/False with region_s/region_t.
406 // This makes the original iff go dead.
407 for (DUIterator_Last i3min, i3 = iff->last_outs(i3min); i3 >= i3min; --i3) {
408 Node* p = iff->last_out(i3);
409 assert( p->Opcode() == Op_IfTrue || p->Opcode() == Op_IfFalse, "" );
410 Node *u = (p->Opcode() == Op_IfTrue) ? region_s : region_f;
411 // Replace p with u
412 igvn->add_users_to_worklist(p);
413 for (DUIterator_Last lmin, l = p->last_outs(lmin); l >= lmin;) {
414 Node* x = p->last_out(l);
415 igvn->hash_delete(x);
416 uint uses_found = 0;
417 for( uint j = 0; j < x->req(); j++ ) {
418 if( x->in(j) == p ) {
419 x->set_req(j, u);
420 uses_found++;
421 }
422 }
423 l -= uses_found; // we deleted 1 or more copies of this edge
424 }
425 igvn->remove_dead_node(p);
426 }
427
428 // Force the original merge dead
429 igvn->hash_delete(r);
430 // First, remove region's dead users.
431 for (DUIterator_Last lmin, l = r->last_outs(lmin); l >= lmin;) {
432 Node* u = r->last_out(l);
433 if( u == r ) {
434 r->set_req(0, NULL);
435 } else {
436 assert(u->outcnt() == 0, "only dead users");
437 igvn->remove_dead_node(u);
438 }
439 l -= 1;
440 }
441 igvn->remove_dead_node(r);
442
443 // Now remove the bogus extra edges used to keep things alive
444 igvn->remove_dead_node( hook );
445
446 // Must return either the original node (now dead) or a new node
447 // (Do not return a top here, since that would break the uniqueness of top.)
448 return new ConINode(TypeInt::ZERO);
449 }
450
451 // if this IfNode follows a range check pattern return the projection
452 // for the failed path
453 ProjNode* IfNode::range_check_trap_proj(int& flip_test, Node*& l, Node*& r) {
454 if (outcnt() != 2) {
455 return NULL;
456 }
457 Node* b = in(1);
458 if (b == NULL || !b->is_Bool()) return NULL;
459 BoolNode* bn = b->as_Bool();
460 Node* cmp = bn->in(1);
461 if (cmp == NULL) return NULL;
462 if (cmp->Opcode() != Op_CmpU) return NULL;
463
464 l = cmp->in(1);
465 r = cmp->in(2);
466 flip_test = 1;
467 if (bn->_test._test == BoolTest::le) {
468 l = cmp->in(2);
469 r = cmp->in(1);
470 flip_test = 2;
471 } else if (bn->_test._test != BoolTest::lt) {
472 return NULL;
473 }
474 if (l->is_top()) return NULL; // Top input means dead test
475 if (r->Opcode() != Op_LoadRange && !is_RangeCheck()) return NULL;
476
477 // We have recognized one of these forms:
478 // Flip 1: If (Bool[<] CmpU(l, LoadRange)) ...
479 // Flip 2: If (Bool[<=] CmpU(LoadRange, l)) ...
480
481 ProjNode* iftrap = proj_out_or_null(flip_test == 2 ? true : false);
482 return iftrap;
483 }
484
485
486 //------------------------------is_range_check---------------------------------
487 // Return 0 if not a range check. Return 1 if a range check and set index and
488 // offset. Return 2 if we had to negate the test. Index is NULL if the check
489 // is versus a constant.
490 int RangeCheckNode::is_range_check(Node* &range, Node* &index, jint &offset) {
491 int flip_test = 0;
492 Node* l = NULL;
493 Node* r = NULL;
494 ProjNode* iftrap = range_check_trap_proj(flip_test, l, r);
495
496 if (iftrap == NULL) {
497 return 0;
498 }
499
500 // Make sure it's a real range check by requiring an uncommon trap
501 // along the OOB path. Otherwise, it's possible that the user wrote
502 // something which optimized to look like a range check but behaves
503 // in some other way.
504 if (iftrap->is_uncommon_trap_proj(Deoptimization::Reason_range_check) == NULL) {
505 return 0;
506 }
507
508 // Look for index+offset form
509 Node* ind = l;
510 jint off = 0;
511 if (l->is_top()) {
512 return 0;
513 } else if (l->Opcode() == Op_AddI) {
514 if ((off = l->in(1)->find_int_con(0)) != 0) {
515 ind = l->in(2)->uncast();
516 } else if ((off = l->in(2)->find_int_con(0)) != 0) {
517 ind = l->in(1)->uncast();
518 }
519 } else if ((off = l->find_int_con(-1)) >= 0) {
520 // constant offset with no variable index
521 ind = NULL;
522 } else {
523 // variable index with no constant offset (or dead negative index)
524 off = 0;
525 }
526
527 // Return all the values:
528 index = ind;
529 offset = off;
530 range = r;
531 return flip_test;
532 }
533
534 //------------------------------adjust_check-----------------------------------
535 // Adjust (widen) a prior range check
536 static void adjust_check(Node* proj, Node* range, Node* index,
537 int flip, jint off_lo, PhaseIterGVN* igvn) {
538 PhaseGVN *gvn = igvn;
539 // Break apart the old check
540 Node *iff = proj->in(0);
541 Node *bol = iff->in(1);
542 if( bol->is_top() ) return; // In case a partially dead range check appears
543 // bail (or bomb[ASSERT/DEBUG]) if NOT projection-->IfNode-->BoolNode
544 DEBUG_ONLY( if( !bol->is_Bool() ) { proj->dump(3); fatal("Expect projection-->IfNode-->BoolNode"); } )
545 if( !bol->is_Bool() ) return;
546
547 Node *cmp = bol->in(1);
548 // Compute a new check
549 Node *new_add = gvn->intcon(off_lo);
550 if( index ) {
551 new_add = off_lo ? gvn->transform(new AddINode( index, new_add )) : index;
552 }
553 Node *new_cmp = (flip == 1)
554 ? new CmpUNode( new_add, range )
555 : new CmpUNode( range, new_add );
556 new_cmp = gvn->transform(new_cmp);
557 // See if no need to adjust the existing check
558 if( new_cmp == cmp ) return;
559 // Else, adjust existing check
560 Node *new_bol = gvn->transform( new BoolNode( new_cmp, bol->as_Bool()->_test._test ) );
561 igvn->rehash_node_delayed( iff );
562 iff->set_req_X( 1, new_bol, igvn );
563 }
564
565 //------------------------------up_one_dom-------------------------------------
566 // Walk up the dominator tree one step. Return NULL at root or true
567 // complex merges. Skips through small diamonds.
568 Node* IfNode::up_one_dom(Node *curr, bool linear_only) {
569 Node *dom = curr->in(0);
570 if( !dom ) // Found a Region degraded to a copy?
571 return curr->nonnull_req(); // Skip thru it
572
573 if( curr != dom ) // Normal walk up one step?
574 return dom;
575
576 // Use linear_only if we are still parsing, since we cannot
577 // trust the regions to be fully filled in.
578 if (linear_only)
579 return NULL;
580
581 if( dom->is_Root() )
582 return NULL;
583
584 // Else hit a Region. Check for a loop header
585 if( dom->is_Loop() )
586 return dom->in(1); // Skip up thru loops
587
588 // Check for small diamonds
589 Node *din1, *din2, *din3, *din4;
590 if( dom->req() == 3 && // 2-path merge point
591 (din1 = dom ->in(1)) && // Left path exists
592 (din2 = dom ->in(2)) && // Right path exists
593 (din3 = din1->in(0)) && // Left path up one
594 (din4 = din2->in(0)) ) { // Right path up one
595 if( din3->is_Call() && // Handle a slow-path call on either arm
596 (din3 = din3->in(0)) )
597 din3 = din3->in(0);
598 if( din4->is_Call() && // Handle a slow-path call on either arm
599 (din4 = din4->in(0)) )
600 din4 = din4->in(0);
601 if (din3 != NULL && din3 == din4 && din3->is_If()) // Regions not degraded to a copy
602 return din3; // Skip around diamonds
603 }
604
605 // Give up the search at true merges
606 return NULL; // Dead loop? Or hit root?
607 }
608
609
610 //------------------------------filtered_int_type--------------------------------
611 // Return a possibly more restrictive type for val based on condition control flow for an if
612 const TypeInt* IfNode::filtered_int_type(PhaseGVN* gvn, Node* val, Node* if_proj) {
613 assert(if_proj &&
614 (if_proj->Opcode() == Op_IfTrue || if_proj->Opcode() == Op_IfFalse), "expecting an if projection");
615 if (if_proj->in(0) && if_proj->in(0)->is_If()) {
616 IfNode* iff = if_proj->in(0)->as_If();
617 if (iff->in(1) && iff->in(1)->is_Bool()) {
618 BoolNode* bol = iff->in(1)->as_Bool();
619 if (bol->in(1) && bol->in(1)->is_Cmp()) {
620 const CmpNode* cmp = bol->in(1)->as_Cmp();
621 if (cmp->in(1) == val) {
622 const TypeInt* cmp2_t = gvn->type(cmp->in(2))->isa_int();
623 if (cmp2_t != NULL) {
624 jint lo = cmp2_t->_lo;
625 jint hi = cmp2_t->_hi;
626 BoolTest::mask msk = if_proj->Opcode() == Op_IfTrue ? bol->_test._test : bol->_test.negate();
627 switch (msk) {
628 case BoolTest::ne: {
629 // If val is compared to its lower or upper bound, we can narrow the type
630 const TypeInt* val_t = gvn->type(val)->isa_int();
631 if (val_t != NULL && !val_t->singleton() && cmp2_t->is_con()) {
632 if (val_t->_lo == lo) {
633 return TypeInt::make(val_t->_lo + 1, val_t->_hi, val_t->_widen);
634 } else if (val_t->_hi == hi) {
635 return TypeInt::make(val_t->_lo, val_t->_hi - 1, val_t->_widen);
636 }
637 }
638 // Can't refine type
639 return NULL;
640 }
641 case BoolTest::eq:
642 return cmp2_t;
643 case BoolTest::lt:
644 lo = TypeInt::INT->_lo;
645 if (hi != min_jint) {
646 hi = hi - 1;
647 }
648 break;
649 case BoolTest::le:
650 lo = TypeInt::INT->_lo;
651 break;
652 case BoolTest::gt:
653 if (lo != max_jint) {
654 lo = lo + 1;
655 }
656 hi = TypeInt::INT->_hi;
657 break;
658 case BoolTest::ge:
659 // lo unchanged
660 hi = TypeInt::INT->_hi;
661 break;
662 default:
663 break;
664 }
665 const TypeInt* rtn_t = TypeInt::make(lo, hi, cmp2_t->_widen);
666 return rtn_t;
667 }
668 }
669 }
670 }
671 }
672 return NULL;
673 }
674
675 //------------------------------fold_compares----------------------------
676 // See if a pair of CmpIs can be converted into a CmpU. In some cases
677 // the direction of this if is determined by the preceding if so it
678 // can be eliminate entirely.
679 //
680 // Given an if testing (CmpI n v) check for an immediately control
681 // dependent if that is testing (CmpI n v2) and has one projection
682 // leading to this if and the other projection leading to a region
683 // that merges one of this ifs control projections.
684 //
685 // If
686 // / |
687 // / |
688 // / |
689 // If |
690 // /\ |
691 // / \ |
692 // / \ |
693 // / Region
694 //
695 // Or given an if testing (CmpI n v) check for a dominating if that is
696 // testing (CmpI n v2), both having one projection leading to an
697 // uncommon trap. Allow Another independent guard in between to cover
698 // an explicit range check:
699 // if (index < 0 || index >= array.length) {
700 // which may need a null check to guard the LoadRange
701 //
702 // If
703 // / \
704 // / \
705 // / \
706 // If unc
707 // /\
708 // / \
709 // / \
710 // / unc
711 //
712
713 // Is the comparison for this If suitable for folding?
714 bool IfNode::cmpi_folds(PhaseIterGVN* igvn, bool fold_ne) {
715 return in(1) != NULL &&
716 in(1)->is_Bool() &&
717 in(1)->in(1) != NULL &&
718 in(1)->in(1)->Opcode() == Op_CmpI &&
719 in(1)->in(1)->in(2) != NULL &&
720 in(1)->in(1)->in(2) != igvn->C->top() &&
721 (in(1)->as_Bool()->_test.is_less() ||
722 in(1)->as_Bool()->_test.is_greater() ||
723 (fold_ne && in(1)->as_Bool()->_test._test == BoolTest::ne));
724 }
725
726 // Is a dominating control suitable for folding with this if?
727 bool IfNode::is_ctrl_folds(Node* ctrl, PhaseIterGVN* igvn) {
728 return ctrl != NULL &&
729 ctrl->is_Proj() &&
730 ctrl->in(0) != NULL &&
731 ctrl->in(0)->Opcode() == Op_If &&
732 ctrl->in(0)->outcnt() == 2 &&
733 ctrl->in(0)->as_If()->cmpi_folds(igvn, true) &&
734 // Must compare same value
735 ctrl->in(0)->in(1)->in(1)->in(1) != NULL &&
736 ctrl->in(0)->in(1)->in(1)->in(1) != igvn->C->top() &&
737 ctrl->in(0)->in(1)->in(1)->in(1) == in(1)->in(1)->in(1);
738 }
739
740 // Do this If and the dominating If share a region?
741 bool IfNode::has_shared_region(ProjNode* proj, ProjNode*& success, ProjNode*& fail) {
742 ProjNode* otherproj = proj->other_if_proj();
743 Node* otherproj_ctrl_use = otherproj->unique_ctrl_out_or_null();
744 RegionNode* region = (otherproj_ctrl_use != NULL && otherproj_ctrl_use->is_Region()) ? otherproj_ctrl_use->as_Region() : NULL;
745 success = NULL;
746 fail = NULL;
747
748 if (otherproj->outcnt() == 1 && region != NULL && !region->has_phi()) {
749 for (int i = 0; i < 2; i++) {
750 ProjNode* proj = proj_out(i);
751 if (success == NULL && proj->outcnt() == 1 && proj->unique_out() == region) {
752 success = proj;
753 } else if (fail == NULL) {
754 fail = proj;
755 } else {
756 success = fail = NULL;
757 }
758 }
759 }
760 return success != NULL && fail != NULL;
761 }
762
763 bool IfNode::is_dominator_unc(CallStaticJavaNode* dom_unc, CallStaticJavaNode* unc) {
764 // Different methods and methods containing jsrs are not supported.
765 ciMethod* method = unc->jvms()->method();
766 ciMethod* dom_method = dom_unc->jvms()->method();
767 if (method != dom_method || method->has_jsrs()) {
768 return false;
769 }
770 // Check that both traps are in the same activation of the method (instead
771 // of two activations being inlined through different call sites) by verifying
772 // that the call stacks are equal for both JVMStates.
773 JVMState* dom_caller = dom_unc->jvms()->caller();
774 JVMState* caller = unc->jvms()->caller();
775 if ((dom_caller == NULL) != (caller == NULL)) {
776 // The current method must either be inlined into both dom_caller and
777 // caller or must not be inlined at all (top method). Bail out otherwise.
778 return false;
779 } else if (dom_caller != NULL && !dom_caller->same_calls_as(caller)) {
780 return false;
781 }
782 // Check that the bci of the dominating uncommon trap dominates the bci
783 // of the dominated uncommon trap. Otherwise we may not re-execute
784 // the dominated check after deoptimization from the merged uncommon trap.
785 ciTypeFlow* flow = dom_method->get_flow_analysis();
786 int bci = unc->jvms()->bci();
787 int dom_bci = dom_unc->jvms()->bci();
788 if (!flow->is_dominated_by(bci, dom_bci)) {
789 return false;
790 }
791
792 return true;
793 }
794
795 // Return projection that leads to an uncommon trap if any
796 ProjNode* IfNode::uncommon_trap_proj(CallStaticJavaNode*& call) const {
797 for (int i = 0; i < 2; i++) {
798 call = proj_out(i)->is_uncommon_trap_proj(Deoptimization::Reason_none);
799 if (call != NULL) {
800 return proj_out(i);
801 }
802 }
803 return NULL;
804 }
805
806 // Do this If and the dominating If both branch out to an uncommon trap
807 bool IfNode::has_only_uncommon_traps(ProjNode* proj, ProjNode*& success, ProjNode*& fail, PhaseIterGVN* igvn) {
808 ProjNode* otherproj = proj->other_if_proj();
809 CallStaticJavaNode* dom_unc = otherproj->is_uncommon_trap_proj(Deoptimization::Reason_none);
810
811 if (otherproj->outcnt() == 1 && dom_unc != NULL) {
812 // We need to re-execute the folded Ifs after deoptimization from the merged traps
813 if (!dom_unc->jvms()->should_reexecute()) {
814 return false;
815 }
816
817 CallStaticJavaNode* unc = NULL;
818 ProjNode* unc_proj = uncommon_trap_proj(unc);
819 if (unc_proj != NULL && unc_proj->outcnt() == 1) {
820 if (dom_unc == unc) {
821 // Allow the uncommon trap to be shared through a region
822 RegionNode* r = unc->in(0)->as_Region();
823 if (r->outcnt() != 2 || r->req() != 3 || r->find_edge(otherproj) == -1 || r->find_edge(unc_proj) == -1) {
824 return false;
825 }
826 assert(r->has_phi() == NULL, "simple region shouldn't have a phi");
827 } else if (dom_unc->in(0) != otherproj || unc->in(0) != unc_proj) {
828 return false;
829 }
830
831 if (!is_dominator_unc(dom_unc, unc)) {
832 return false;
833 }
834
835 // See merge_uncommon_traps: the reason of the uncommon trap
836 // will be changed and the state of the dominating If will be
837 // used. Checked that we didn't apply this transformation in a
838 // previous compilation and it didn't cause too many traps
839 ciMethod* dom_method = dom_unc->jvms()->method();
840 int dom_bci = dom_unc->jvms()->bci();
841 if (!igvn->C->too_many_traps(dom_method, dom_bci, Deoptimization::Reason_unstable_fused_if) &&
842 !igvn->C->too_many_traps(dom_method, dom_bci, Deoptimization::Reason_range_check) &&
843 // Return true if c2 manages to reconcile with UnstableIf optimization. See the comments for it.
844 igvn->C->remove_unstable_if_trap(dom_unc, true/*yield*/)) {
845 success = unc_proj;
846 fail = unc_proj->other_if_proj();
847 return true;
848 }
849 }
850 }
851 return false;
852 }
853
854 // Check that the 2 CmpI can be folded into as single CmpU and proceed with the folding
855 bool IfNode::fold_compares_helper(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn) {
856 Node* this_cmp = in(1)->in(1);
857 BoolNode* this_bool = in(1)->as_Bool();
858 IfNode* dom_iff = proj->in(0)->as_If();
859 BoolNode* dom_bool = dom_iff->in(1)->as_Bool();
860 Node* lo = dom_iff->in(1)->in(1)->in(2);
861 Node* hi = this_cmp->in(2);
862 Node* n = this_cmp->in(1);
863 ProjNode* otherproj = proj->other_if_proj();
864
865 const TypeInt* lo_type = IfNode::filtered_int_type(igvn, n, otherproj);
866 const TypeInt* hi_type = IfNode::filtered_int_type(igvn, n, success);
867
868 BoolTest::mask lo_test = dom_bool->_test._test;
869 BoolTest::mask hi_test = this_bool->_test._test;
870 BoolTest::mask cond = hi_test;
871
872 // convert:
873 //
874 // dom_bool = x {<,<=,>,>=} a
875 // / \
876 // proj = {True,False} / \ otherproj = {False,True}
877 // /
878 // this_bool = x {<,<=} b
879 // / \
880 // fail = {True,False} / \ success = {False,True}
881 // /
882 //
883 // (Second test guaranteed canonicalized, first one may not have
884 // been canonicalized yet)
885 //
886 // into:
887 //
888 // cond = (x - lo) {<u,<=u,>u,>=u} adjusted_lim
889 // / \
890 // fail / \ success
891 // /
892 //
893
894 // Figure out which of the two tests sets the upper bound and which
895 // sets the lower bound if any.
896 Node* adjusted_lim = NULL;
897 if (lo_type != NULL && hi_type != NULL && hi_type->_lo > lo_type->_hi &&
898 hi_type->_hi == max_jint && lo_type->_lo == min_jint && lo_test != BoolTest::ne) {
899 assert((dom_bool->_test.is_less() && !proj->_con) ||
900 (dom_bool->_test.is_greater() && proj->_con), "incorrect test");
901
902 // this_bool = <
903 // dom_bool = >= (proj = True) or dom_bool = < (proj = False)
904 // x in [a, b[ on the fail (= True) projection, b > a-1 (because of hi_type->_lo > lo_type->_hi test above):
905 // lo = a, hi = b, adjusted_lim = b-a, cond = <u
906 // dom_bool = > (proj = True) or dom_bool = <= (proj = False)
907 // x in ]a, b[ on the fail (= True) projection, b > a:
908 // lo = a+1, hi = b, adjusted_lim = b-a-1, cond = <u
909 // this_bool = <=
910 // dom_bool = >= (proj = True) or dom_bool = < (proj = False)
911 // x in [a, b] on the fail (= True) projection, b+1 > a-1:
912 // lo = a, hi = b, adjusted_lim = b-a+1, cond = <u
913 // lo = a, hi = b, adjusted_lim = b-a, cond = <=u doesn't work because b = a - 1 is possible, then b-a = -1
914 // dom_bool = > (proj = True) or dom_bool = <= (proj = False)
915 // x in ]a, b] on the fail (= True) projection b+1 > a:
916 // lo = a+1, hi = b, adjusted_lim = b-a, cond = <u
917 // 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
918
919 if (hi_test == BoolTest::lt) {
920 if (lo_test == BoolTest::gt || lo_test == BoolTest::le) {
921 lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
922 }
923 } else if (hi_test == BoolTest::le) {
924 if (lo_test == BoolTest::ge || lo_test == BoolTest::lt) {
925 adjusted_lim = igvn->transform(new SubINode(hi, lo));
926 adjusted_lim = igvn->transform(new AddINode(adjusted_lim, igvn->intcon(1)));
927 cond = BoolTest::lt;
928 } else if (lo_test == BoolTest::gt || lo_test == BoolTest::le) {
929 adjusted_lim = igvn->transform(new SubINode(hi, lo));
930 lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
931 cond = BoolTest::lt;
932 } else {
933 assert(false, "unhandled lo_test: %d", lo_test);
934 return false;
935 }
936 } else {
937 assert(igvn->_worklist.member(in(1)) && in(1)->Value(igvn) != igvn->type(in(1)), "unhandled hi_test: %d", hi_test);
938 return false;
939 }
940 // this test was canonicalized
941 assert(this_bool->_test.is_less() && fail->_con, "incorrect test");
942 } else if (lo_type != NULL && hi_type != NULL && lo_type->_lo > hi_type->_hi &&
943 lo_type->_hi == max_jint && hi_type->_lo == min_jint && lo_test != BoolTest::ne) {
944
945 // this_bool = <
946 // dom_bool = < (proj = True) or dom_bool = >= (proj = False)
947 // x in [b, a[ on the fail (= False) projection, a > b-1 (because of lo_type->_lo > hi_type->_hi above):
948 // lo = b, hi = a, adjusted_lim = a-b, cond = >=u
949 // dom_bool = <= (proj = True) or dom_bool = > (proj = False)
950 // x in [b, a] on the fail (= False) projection, a+1 > b-1:
951 // lo = b, hi = a, adjusted_lim = a-b+1, cond = >=u
952 // lo = b, hi = a, adjusted_lim = a-b, cond = >u doesn't work because a = b - 1 is possible, then b-a = -1
953 // this_bool = <=
954 // dom_bool = < (proj = True) or dom_bool = >= (proj = False)
955 // x in ]b, a[ on the fail (= False) projection, a > b:
956 // lo = b+1, hi = a, adjusted_lim = a-b-1, cond = >=u
957 // dom_bool = <= (proj = True) or dom_bool = > (proj = False)
958 // x in ]b, a] on the fail (= False) projection, a+1 > b:
959 // lo = b+1, hi = a, adjusted_lim = a-b, cond = >=u
960 // 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
961
962 swap(lo, hi);
963 swap(lo_type, hi_type);
964 swap(lo_test, hi_test);
965
966 assert((dom_bool->_test.is_less() && proj->_con) ||
967 (dom_bool->_test.is_greater() && !proj->_con), "incorrect test");
968
969 cond = (hi_test == BoolTest::le || hi_test == BoolTest::gt) ? BoolTest::gt : BoolTest::ge;
970
971 if (lo_test == BoolTest::lt) {
972 if (hi_test == BoolTest::lt || hi_test == BoolTest::ge) {
973 cond = BoolTest::ge;
974 } else if (hi_test == BoolTest::le || hi_test == BoolTest::gt) {
975 adjusted_lim = igvn->transform(new SubINode(hi, lo));
976 adjusted_lim = igvn->transform(new AddINode(adjusted_lim, igvn->intcon(1)));
977 cond = BoolTest::ge;
978 } else {
979 assert(false, "unhandled hi_test: %d", hi_test);
980 return false;
981 }
982 } else if (lo_test == BoolTest::le) {
983 if (hi_test == BoolTest::lt || hi_test == BoolTest::ge) {
984 lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
985 cond = BoolTest::ge;
986 } else if (hi_test == BoolTest::le || hi_test == BoolTest::gt) {
987 adjusted_lim = igvn->transform(new SubINode(hi, lo));
988 lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
989 cond = BoolTest::ge;
990 } else {
991 assert(false, "unhandled hi_test: %d", hi_test);
992 return false;
993 }
994 } else {
995 assert(igvn->_worklist.member(in(1)) && in(1)->Value(igvn) != igvn->type(in(1)), "unhandled lo_test: %d", lo_test);
996 return false;
997 }
998 // this test was canonicalized
999 assert(this_bool->_test.is_less() && !fail->_con, "incorrect test");
1000 } else {
1001 const TypeInt* failtype = filtered_int_type(igvn, n, proj);
1002 if (failtype != NULL) {
1003 const TypeInt* type2 = filtered_int_type(igvn, n, fail);
1004 if (type2 != NULL) {
1005 failtype = failtype->join(type2)->is_int();
1006 if (failtype->_lo > failtype->_hi) {
1007 // previous if determines the result of this if so
1008 // replace Bool with constant
1009 igvn->replace_input_of(this, 1, igvn->intcon(success->_con));
1010 return true;
1011 }
1012 }
1013 }
1014 lo = NULL;
1015 hi = NULL;
1016 }
1017
1018 if (lo && hi) {
1019 Node* hook = new Node(1);
1020 hook->init_req(0, lo); // Add a use to lo to prevent him from dying
1021 // Merge the two compares into a single unsigned compare by building (CmpU (n - lo) (hi - lo))
1022 Node* adjusted_val = igvn->transform(new SubINode(n, lo));
1023 if (adjusted_lim == NULL) {
1024 adjusted_lim = igvn->transform(new SubINode(hi, lo));
1025 }
1026 hook->destruct(igvn);
1027
1028 int lo = igvn->type(adjusted_lim)->is_int()->_lo;
1029 if (lo < 0) {
1030 // If range check elimination applies to this comparison, it includes code to protect from overflows that may
1031 // cause the main loop to be skipped entirely. Delay this transformation.
1032 // Example:
1033 // for (int i = 0; i < limit; i++) {
1034 // if (i < max_jint && i > min_jint) {...
1035 // }
1036 // Comparisons folded as:
1037 // i - min_jint - 1 <u -2
1038 // when RC applies, main loop limit becomes:
1039 // min(limit, max(-2 + min_jint + 1, min_jint))
1040 // = min(limit, min_jint)
1041 // = min_jint
1042 if (!igvn->C->post_loop_opts_phase()) {
1043 if (adjusted_val->outcnt() == 0) {
1044 igvn->remove_dead_node(adjusted_val);
1045 }
1046 if (adjusted_lim->outcnt() == 0) {
1047 igvn->remove_dead_node(adjusted_lim);
1048 }
1049 igvn->C->record_for_post_loop_opts_igvn(this);
1050 return false;
1051 }
1052 }
1053
1054 Node* newcmp = igvn->transform(new CmpUNode(adjusted_val, adjusted_lim));
1055 Node* newbool = igvn->transform(new BoolNode(newcmp, cond));
1056
1057 igvn->replace_input_of(dom_iff, 1, igvn->intcon(proj->_con));
1058 igvn->replace_input_of(this, 1, newbool);
1059
1060 return true;
1061 }
1062 return false;
1063 }
1064
1065 // Merge the branches that trap for this If and the dominating If into
1066 // a single region that branches to the uncommon trap for the
1067 // dominating If
1068 Node* IfNode::merge_uncommon_traps(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn) {
1069 Node* res = this;
1070 assert(success->in(0) == this, "bad projection");
1071
1072 ProjNode* otherproj = proj->other_if_proj();
1073
1074 CallStaticJavaNode* unc = success->is_uncommon_trap_proj(Deoptimization::Reason_none);
1075 CallStaticJavaNode* dom_unc = otherproj->is_uncommon_trap_proj(Deoptimization::Reason_none);
1076
1077 if (unc != dom_unc) {
1078 Node* r = new RegionNode(3);
1079
1080 r->set_req(1, otherproj);
1081 r->set_req(2, success);
1082 r = igvn->transform(r);
1083 assert(r->is_Region(), "can't go away");
1084
1085 // Make both If trap at the state of the first If: once the CmpI
1086 // nodes are merged, if we trap we don't know which of the CmpI
1087 // nodes would have caused the trap so we have to restart
1088 // execution at the first one
1089 igvn->replace_input_of(dom_unc, 0, r);
1090 igvn->replace_input_of(unc, 0, igvn->C->top());
1091 }
1092 int trap_request = dom_unc->uncommon_trap_request();
1093 Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(trap_request);
1094 Deoptimization::DeoptAction action = Deoptimization::trap_request_action(trap_request);
1095
1096 int flip_test = 0;
1097 Node* l = NULL;
1098 Node* r = NULL;
1099
1100 if (success->in(0)->as_If()->range_check_trap_proj(flip_test, l, r) != NULL) {
1101 // If this looks like a range check, change the trap to
1102 // Reason_range_check so the compiler recognizes it as a range
1103 // check and applies the corresponding optimizations
1104 trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_range_check, action);
1105
1106 improve_address_types(l, r, fail, igvn);
1107
1108 res = igvn->transform(new RangeCheckNode(in(0), in(1), _prob, _fcnt));
1109 } else if (unc != dom_unc) {
1110 // If we trap we won't know what CmpI would have caused the trap
1111 // so use a special trap reason to mark this pair of CmpI nodes as
1112 // bad candidate for folding. On recompilation we won't fold them
1113 // and we may trap again but this time we'll know what branch
1114 // traps
1115 trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_unstable_fused_if, action);
1116 }
1117 igvn->replace_input_of(dom_unc, TypeFunc::Parms, igvn->intcon(trap_request));
1118 return res;
1119 }
1120
1121 // If we are turning 2 CmpI nodes into a CmpU that follows the pattern
1122 // of a rangecheck on index i, on 64 bit the compares may be followed
1123 // by memory accesses using i as index. In that case, the CmpU tells
1124 // us something about the values taken by i that can help the compiler
1125 // (see Compile::conv_I2X_index())
1126 void IfNode::improve_address_types(Node* l, Node* r, ProjNode* fail, PhaseIterGVN* igvn) {
1127 #ifdef _LP64
1128 ResourceMark rm;
1129 Node_Stack stack(2);
1130
1131 assert(r->Opcode() == Op_LoadRange, "unexpected range check");
1132 const TypeInt* array_size = igvn->type(r)->is_int();
1133
1134 stack.push(l, 0);
1135
1136 while(stack.size() > 0) {
1137 Node* n = stack.node();
1138 uint start = stack.index();
1139
1140 uint i = start;
1141 for (; i < n->outcnt(); i++) {
1142 Node* use = n->raw_out(i);
1143 if (stack.size() == 1) {
1144 if (use->Opcode() == Op_ConvI2L) {
1145 const TypeLong* bounds = use->as_Type()->type()->is_long();
1146 if (bounds->_lo <= array_size->_lo && bounds->_hi >= array_size->_hi &&
1147 (bounds->_lo != array_size->_lo || bounds->_hi != array_size->_hi)) {
1148 stack.set_index(i+1);
1149 stack.push(use, 0);
1150 break;
1151 }
1152 }
1153 } else if (use->is_Mem()) {
1154 Node* ctrl = use->in(0);
1155 for (int i = 0; i < 10 && ctrl != NULL && ctrl != fail; i++) {
1156 ctrl = up_one_dom(ctrl);
1157 }
1158 if (ctrl == fail) {
1159 Node* init_n = stack.node_at(1);
1160 assert(init_n->Opcode() == Op_ConvI2L, "unexpected first node");
1161 // Create a new narrow ConvI2L node that is dependent on the range check
1162 Node* new_n = igvn->C->conv_I2X_index(igvn, l, array_size, fail);
1163
1164 // The type of the ConvI2L may be widen and so the new
1165 // ConvI2L may not be better than an existing ConvI2L
1166 if (new_n != init_n) {
1167 for (uint j = 2; j < stack.size(); j++) {
1168 Node* n = stack.node_at(j);
1169 Node* clone = n->clone();
1170 int rep = clone->replace_edge(init_n, new_n, igvn);
1171 assert(rep > 0, "can't find expected node?");
1172 clone = igvn->transform(clone);
1173 init_n = n;
1174 new_n = clone;
1175 }
1176 igvn->hash_delete(use);
1177 int rep = use->replace_edge(init_n, new_n, igvn);
1178 assert(rep > 0, "can't find expected node?");
1179 igvn->transform(use);
1180 if (init_n->outcnt() == 0) {
1181 igvn->_worklist.push(init_n);
1182 }
1183 }
1184 }
1185 } else if (use->in(0) == NULL && (igvn->type(use)->isa_long() ||
1186 igvn->type(use)->isa_ptr())) {
1187 stack.set_index(i+1);
1188 stack.push(use, 0);
1189 break;
1190 }
1191 }
1192 if (i == n->outcnt()) {
1193 stack.pop();
1194 }
1195 }
1196 #endif
1197 }
1198
1199 bool IfNode::is_cmp_with_loadrange(ProjNode* proj) {
1200 if (in(1) != NULL &&
1201 in(1)->in(1) != NULL &&
1202 in(1)->in(1)->in(2) != NULL) {
1203 Node* other = in(1)->in(1)->in(2);
1204 if (other->Opcode() == Op_LoadRange &&
1205 ((other->in(0) != NULL && other->in(0) == proj) ||
1206 (other->in(0) == NULL &&
1207 other->in(2) != NULL &&
1208 other->in(2)->is_AddP() &&
1209 other->in(2)->in(1) != NULL &&
1210 other->in(2)->in(1)->Opcode() == Op_CastPP &&
1211 other->in(2)->in(1)->in(0) == proj))) {
1212 return true;
1213 }
1214 }
1215 return false;
1216 }
1217
1218 bool IfNode::is_null_check(ProjNode* proj, PhaseIterGVN* igvn) {
1219 Node* other = in(1)->in(1)->in(2);
1220 if (other->in(MemNode::Address) != NULL &&
1221 proj->in(0)->in(1) != NULL &&
1222 proj->in(0)->in(1)->is_Bool() &&
1223 proj->in(0)->in(1)->in(1) != NULL &&
1224 proj->in(0)->in(1)->in(1)->Opcode() == Op_CmpP &&
1225 proj->in(0)->in(1)->in(1)->in(2) != NULL &&
1226 proj->in(0)->in(1)->in(1)->in(1) == other->in(MemNode::Address)->in(AddPNode::Address)->uncast() &&
1227 igvn->type(proj->in(0)->in(1)->in(1)->in(2)) == TypePtr::NULL_PTR) {
1228 return true;
1229 }
1230 return false;
1231 }
1232
1233 // Returns true if this IfNode belongs to a flat array check
1234 // and returns the corresponding array in the 'array' parameter.
1235 bool IfNode::is_flat_array_check(PhaseTransform* phase, Node** array) {
1236 Node* bol = in(1);
1237 if (!bol->is_Bool()) {
1238 return false;
1239 }
1240 Node* cmp = bol->in(1);
1241 if (cmp->isa_FlatArrayCheck()) {
1242 if (array != NULL) {
1243 *array = cmp->in(FlatArrayCheckNode::ArrayOrKlass);
1244 }
1245 return true;
1246 }
1247 return false;
1248 }
1249
1250 // Check that the If that is in between the 2 integer comparisons has
1251 // no side effect
1252 bool IfNode::is_side_effect_free_test(ProjNode* proj, PhaseIterGVN* igvn) {
1253 if (proj == NULL) {
1254 return false;
1255 }
1256 CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
1257 if (unc != NULL && proj->outcnt() <= 2) {
1258 if (proj->outcnt() == 1 ||
1259 // Allow simple null check from LoadRange
1260 (is_cmp_with_loadrange(proj) && is_null_check(proj, igvn))) {
1261 CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
1262 CallStaticJavaNode* dom_unc = proj->in(0)->in(0)->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
1263 assert(dom_unc != NULL, "is_uncommon_trap_if_pattern returned NULL");
1264
1265 // reroute_side_effect_free_unc changes the state of this
1266 // uncommon trap to restart execution at the previous
1267 // CmpI. Check that this change in a previous compilation didn't
1268 // cause too many traps.
1269 int trap_request = unc->uncommon_trap_request();
1270 Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(trap_request);
1271
1272 if (igvn->C->too_many_traps(dom_unc->jvms()->method(), dom_unc->jvms()->bci(), reason)) {
1273 return false;
1274 }
1275
1276 if (!is_dominator_unc(dom_unc, unc)) {
1277 return false;
1278 }
1279
1280 return true;
1281 }
1282 }
1283 return false;
1284 }
1285
1286 // Make the If between the 2 integer comparisons trap at the state of
1287 // the first If: the last CmpI is the one replaced by a CmpU and the
1288 // first CmpI is eliminated, so the test between the 2 CmpI nodes
1289 // won't be guarded by the first CmpI anymore. It can trap in cases
1290 // where the first CmpI would have prevented it from executing: on a
1291 // trap, we need to restart execution at the state of the first CmpI
1292 void IfNode::reroute_side_effect_free_unc(ProjNode* proj, ProjNode* dom_proj, PhaseIterGVN* igvn) {
1293 CallStaticJavaNode* dom_unc = dom_proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
1294 ProjNode* otherproj = proj->other_if_proj();
1295 CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
1296 Node* call_proj = dom_unc->unique_ctrl_out();
1297 Node* halt = call_proj->unique_ctrl_out();
1298
1299 Node* new_unc = dom_unc->clone();
1300 call_proj = call_proj->clone();
1301 halt = halt->clone();
1302 Node* c = otherproj->clone();
1303
1304 c = igvn->transform(c);
1305 new_unc->set_req(TypeFunc::Parms, unc->in(TypeFunc::Parms));
1306 new_unc->set_req(0, c);
1307 new_unc = igvn->transform(new_unc);
1308 call_proj->set_req(0, new_unc);
1309 call_proj = igvn->transform(call_proj);
1310 halt->set_req(0, call_proj);
1311 halt = igvn->transform(halt);
1312
1313 igvn->replace_node(otherproj, igvn->C->top());
1314 igvn->C->root()->add_req(halt);
1315 }
1316
1317 Node* IfNode::fold_compares(PhaseIterGVN* igvn) {
1318 if (Opcode() != Op_If) return NULL;
1319
1320 if (cmpi_folds(igvn)) {
1321 Node* ctrl = in(0);
1322 if (is_ctrl_folds(ctrl, igvn) && ctrl->outcnt() == 1) {
1323 // A integer comparison immediately dominated by another integer
1324 // comparison
1325 ProjNode* success = NULL;
1326 ProjNode* fail = NULL;
1327 ProjNode* dom_cmp = ctrl->as_Proj();
1328 if (has_shared_region(dom_cmp, success, fail) &&
1329 // Next call modifies graph so must be last
1330 fold_compares_helper(dom_cmp, success, fail, igvn)) {
1331 return this;
1332 }
1333 if (has_only_uncommon_traps(dom_cmp, success, fail, igvn) &&
1334 // Next call modifies graph so must be last
1335 fold_compares_helper(dom_cmp, success, fail, igvn)) {
1336 return merge_uncommon_traps(dom_cmp, success, fail, igvn);
1337 }
1338 return NULL;
1339 } else if (ctrl->in(0) != NULL &&
1340 ctrl->in(0)->in(0) != NULL) {
1341 ProjNode* success = NULL;
1342 ProjNode* fail = NULL;
1343 Node* dom = ctrl->in(0)->in(0);
1344 ProjNode* dom_cmp = dom->isa_Proj();
1345 ProjNode* other_cmp = ctrl->isa_Proj();
1346
1347 // Check if it's an integer comparison dominated by another
1348 // integer comparison with another test in between
1349 if (is_ctrl_folds(dom, igvn) &&
1350 has_only_uncommon_traps(dom_cmp, success, fail, igvn) &&
1351 is_side_effect_free_test(other_cmp, igvn) &&
1352 // Next call modifies graph so must be last
1353 fold_compares_helper(dom_cmp, success, fail, igvn)) {
1354 reroute_side_effect_free_unc(other_cmp, dom_cmp, igvn);
1355 return merge_uncommon_traps(dom_cmp, success, fail, igvn);
1356 }
1357 }
1358 }
1359 return NULL;
1360 }
1361
1362 //------------------------------remove_useless_bool----------------------------
1363 // Check for people making a useless boolean: things like
1364 // if( (x < y ? true : false) ) { ... }
1365 // Replace with if( x < y ) { ... }
1366 static Node *remove_useless_bool(IfNode *iff, PhaseGVN *phase) {
1367 Node *i1 = iff->in(1);
1368 if( !i1->is_Bool() ) return NULL;
1369 BoolNode *bol = i1->as_Bool();
1370
1371 Node *cmp = bol->in(1);
1372 if( cmp->Opcode() != Op_CmpI ) return NULL;
1373
1374 // Must be comparing against a bool
1375 const Type *cmp2_t = phase->type( cmp->in(2) );
1376 if( cmp2_t != TypeInt::ZERO &&
1377 cmp2_t != TypeInt::ONE )
1378 return NULL;
1379
1380 // Find a prior merge point merging the boolean
1381 i1 = cmp->in(1);
1382 if( !i1->is_Phi() ) return NULL;
1383 PhiNode *phi = i1->as_Phi();
1384 if( phase->type( phi ) != TypeInt::BOOL )
1385 return NULL;
1386
1387 // Check for diamond pattern
1388 int true_path = phi->is_diamond_phi();
1389 if( true_path == 0 ) return NULL;
1390
1391 // Make sure that iff and the control of the phi are different. This
1392 // should really only happen for dead control flow since it requires
1393 // an illegal cycle.
1394 if (phi->in(0)->in(1)->in(0) == iff) return NULL;
1395
1396 // phi->region->if_proj->ifnode->bool->cmp
1397 BoolNode *bol2 = phi->in(0)->in(1)->in(0)->in(1)->as_Bool();
1398
1399 // Now get the 'sense' of the test correct so we can plug in
1400 // either iff2->in(1) or its complement.
1401 int flip = 0;
1402 if( bol->_test._test == BoolTest::ne ) flip = 1-flip;
1403 else if( bol->_test._test != BoolTest::eq ) return NULL;
1404 if( cmp2_t == TypeInt::ZERO ) flip = 1-flip;
1405
1406 const Type *phi1_t = phase->type( phi->in(1) );
1407 const Type *phi2_t = phase->type( phi->in(2) );
1408 // Check for Phi(0,1) and flip
1409 if( phi1_t == TypeInt::ZERO ) {
1410 if( phi2_t != TypeInt::ONE ) return NULL;
1411 flip = 1-flip;
1412 } else {
1413 // Check for Phi(1,0)
1414 if( phi1_t != TypeInt::ONE ) return NULL;
1415 if( phi2_t != TypeInt::ZERO ) return NULL;
1416 }
1417 if( true_path == 2 ) {
1418 flip = 1-flip;
1419 }
1420
1421 Node* new_bol = (flip ? phase->transform( bol2->negate(phase) ) : bol2);
1422 assert(new_bol != iff->in(1), "must make progress");
1423 iff->set_req_X(1, new_bol, phase);
1424 // Intervening diamond probably goes dead
1425 phase->C->set_major_progress();
1426 return iff;
1427 }
1428
1429 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff);
1430
1431 struct RangeCheck {
1432 Node* ctl;
1433 jint off;
1434 };
1435
1436 Node* IfNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
1437 if (remove_dead_region(phase, can_reshape)) return this;
1438 // No Def-Use info?
1439 if (!can_reshape) return NULL;
1440
1441 // Don't bother trying to transform a dead if
1442 if (in(0)->is_top()) return NULL;
1443 // Don't bother trying to transform an if with a dead test
1444 if (in(1)->is_top()) return NULL;
1445 // Another variation of a dead test
1446 if (in(1)->is_Con()) return NULL;
1447 // Another variation of a dead if
1448 if (outcnt() < 2) return NULL;
1449
1450 // Canonicalize the test.
1451 Node* idt_if = idealize_test(phase, this);
1452 if (idt_if != NULL) return idt_if;
1453
1454 // Try to split the IF
1455 PhaseIterGVN *igvn = phase->is_IterGVN();
1456 Node *s = split_if(this, igvn);
1457 if (s != NULL) return s;
1458
1459 return NodeSentinel;
1460 }
1461
1462 //------------------------------Ideal------------------------------------------
1463 // Return a node which is more "ideal" than the current node. Strip out
1464 // control copies
1465 Node* IfNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1466 Node* res = Ideal_common(phase, can_reshape);
1467 if (res != NodeSentinel) {
1468 return res;
1469 }
1470
1471 // Check for people making a useless boolean: things like
1472 // if( (x < y ? true : false) ) { ... }
1473 // Replace with if( x < y ) { ... }
1474 Node* bol2 = remove_useless_bool(this, phase);
1475 if (bol2) return bol2;
1476
1477 if (in(0) == NULL) return NULL; // Dead loop?
1478
1479 PhaseIterGVN* igvn = phase->is_IterGVN();
1480 Node* result = fold_compares(igvn);
1481 if (result != NULL) {
1482 return result;
1483 }
1484
1485 // Scan for an equivalent test
1486 int dist = 4; // Cutoff limit for search
1487 if (is_If() && in(1)->is_Bool()) {
1488 Node* cmp = in(1)->in(1);
1489 if (cmp->Opcode() == Op_CmpP &&
1490 cmp->in(2) != NULL && // make sure cmp is not already dead
1491 cmp->in(2)->bottom_type() == TypePtr::NULL_PTR) {
1492 dist = 64; // Limit for null-pointer scans
1493 }
1494 }
1495
1496 Node* prev_dom = search_identical(dist);
1497
1498 if (prev_dom != NULL) {
1499 // Replace dominated IfNode
1500 return dominated_by(prev_dom, igvn);
1501 }
1502
1503 return simple_subsuming(igvn);
1504 }
1505
1506 //------------------------------dominated_by-----------------------------------
1507 Node* IfNode::dominated_by(Node* prev_dom, PhaseIterGVN *igvn) {
1508 #ifndef PRODUCT
1509 if (TraceIterativeGVN) {
1510 tty->print(" Removing IfNode: "); this->dump();
1511 }
1512 #endif
1513
1514 igvn->hash_delete(this); // Remove self to prevent spurious V-N
1515 Node *idom = in(0);
1516 // Need opcode to decide which way 'this' test goes
1517 int prev_op = prev_dom->Opcode();
1518 Node *top = igvn->C->top(); // Shortcut to top
1519
1520 // Loop predicates may have depending checks which should not
1521 // be skipped. For example, range check predicate has two checks
1522 // for lower and upper bounds.
1523 ProjNode* unc_proj = proj_out(1 - prev_dom->as_Proj()->_con)->as_Proj();
1524 if (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate) != NULL ||
1525 unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_profile_predicate) != NULL) {
1526 prev_dom = idom;
1527 }
1528
1529 // Now walk the current IfNode's projections.
1530 // Loop ends when 'this' has no more uses.
1531 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
1532 Node *ifp = last_out(i); // Get IfTrue/IfFalse
1533 igvn->add_users_to_worklist(ifp);
1534 // Check which projection it is and set target.
1535 // Data-target is either the dominating projection of the same type
1536 // or TOP if the dominating projection is of opposite type.
1537 // Data-target will be used as the new control edge for the non-CFG
1538 // nodes like Casts and Loads.
1539 Node *data_target = (ifp->Opcode() == prev_op) ? prev_dom : top;
1540 // Control-target is just the If's immediate dominator or TOP.
1541 Node *ctrl_target = (ifp->Opcode() == prev_op) ? idom : top;
1542
1543 // For each child of an IfTrue/IfFalse projection, reroute.
1544 // Loop ends when projection has no more uses.
1545 for (DUIterator_Last jmin, j = ifp->last_outs(jmin); j >= jmin; --j) {
1546 Node* s = ifp->last_out(j); // Get child of IfTrue/IfFalse
1547 if (s->depends_only_on_test() && igvn->no_dependent_zero_check(s)) {
1548 // For control producers.
1549 // Do not rewire Div and Mod nodes which could have a zero divisor to avoid skipping their zero check.
1550 igvn->replace_input_of(s, 0, data_target); // Move child to data-target
1551 } else {
1552 // Find the control input matching this def-use edge.
1553 // For Regions it may not be in slot 0.
1554 uint l;
1555 for (l = 0; s->in(l) != ifp; l++) { }
1556 igvn->replace_input_of(s, l, ctrl_target);
1557 }
1558 } // End for each child of a projection
1559
1560 igvn->remove_dead_node(ifp);
1561 } // End for each IfTrue/IfFalse child of If
1562
1563 // Kill the IfNode
1564 igvn->remove_dead_node(this);
1565
1566 // Must return either the original node (now dead) or a new node
1567 // (Do not return a top here, since that would break the uniqueness of top.)
1568 return new ConINode(TypeInt::ZERO);
1569 }
1570
1571 Node* IfNode::search_identical(int dist) {
1572 // Setup to scan up the CFG looking for a dominating test
1573 Node* dom = in(0);
1574 Node* prev_dom = this;
1575 int op = Opcode();
1576 // Search up the dominator tree for an If with an identical test
1577 while (dom->Opcode() != op || // Not same opcode?
1578 dom->in(1) != in(1) || // Not same input 1?
1579 prev_dom->in(0) != dom) { // One path of test does not dominate?
1580 if (dist < 0) return NULL;
1581
1582 dist--;
1583 prev_dom = dom;
1584 dom = up_one_dom(dom);
1585 if (!dom) return NULL;
1586 }
1587
1588 // Check that we did not follow a loop back to ourselves
1589 if (this == dom) {
1590 return NULL;
1591 }
1592
1593 #ifndef PRODUCT
1594 if (dist > 2) { // Add to count of NULL checks elided
1595 explicit_null_checks_elided++;
1596 }
1597 #endif
1598
1599 return prev_dom;
1600 }
1601
1602
1603 static int subsuming_bool_test_encode(Node*);
1604
1605 // Check if dominating test is subsuming 'this' one.
1606 //
1607 // cmp
1608 // / \
1609 // (r1) bool \
1610 // / bool (r2)
1611 // (dom) if \
1612 // \ )
1613 // (pre) if[TF] /
1614 // \ /
1615 // if (this)
1616 // \r1
1617 // r2\ eqT eqF neT neF ltT ltF leT leF gtT gtF geT geF
1618 // eq t f f t f - - f f - - f
1619 // ne f t t f t - - t t - - t
1620 // lt f - - f t f - f f - f t
1621 // le t - - t t - t f f t - t
1622 // gt f - - f f - f t t f - f
1623 // ge t - - t f t - t t - t f
1624 //
1625 Node* IfNode::simple_subsuming(PhaseIterGVN* igvn) {
1626 // Table encoding: N/A (na), True-branch (tb), False-branch (fb).
1627 static enum { na, tb, fb } s_short_circuit_map[6][12] = {
1628 /*rel: eq+T eq+F ne+T ne+F lt+T lt+F le+T le+F gt+T gt+F ge+T ge+F*/
1629 /*eq*/{ tb, fb, fb, tb, fb, na, na, fb, fb, na, na, fb },
1630 /*ne*/{ fb, tb, tb, fb, tb, na, na, tb, tb, na, na, tb },
1631 /*lt*/{ fb, na, na, fb, tb, fb, na, fb, fb, na, fb, tb },
1632 /*le*/{ tb, na, na, tb, tb, na, tb, fb, fb, tb, na, tb },
1633 /*gt*/{ fb, na, na, fb, fb, na, fb, tb, tb, fb, na, fb },
1634 /*ge*/{ tb, na, na, tb, fb, tb, na, tb, tb, na, tb, fb }};
1635
1636 Node* pre = in(0);
1637 if (!pre->is_IfTrue() && !pre->is_IfFalse()) {
1638 return NULL;
1639 }
1640 Node* dom = pre->in(0);
1641 if (!dom->is_If()) {
1642 return NULL;
1643 }
1644 Node* bol = in(1);
1645 if (!bol->is_Bool()) {
1646 return NULL;
1647 }
1648 Node* cmp = in(1)->in(1);
1649 if (!cmp->is_Cmp()) {
1650 return NULL;
1651 }
1652
1653 if (!dom->in(1)->is_Bool()) {
1654 return NULL;
1655 }
1656 if (dom->in(1)->in(1) != cmp) { // Not same cond?
1657 return NULL;
1658 }
1659
1660 int drel = subsuming_bool_test_encode(dom->in(1));
1661 int trel = subsuming_bool_test_encode(bol);
1662 int bout = pre->is_IfFalse() ? 1 : 0;
1663
1664 if (drel < 0 || trel < 0) {
1665 return NULL;
1666 }
1667 int br = s_short_circuit_map[trel][2*drel+bout];
1668 if (br == na) {
1669 return NULL;
1670 }
1671 #ifndef PRODUCT
1672 if (TraceIterativeGVN) {
1673 tty->print(" Subsumed IfNode: "); dump();
1674 }
1675 #endif
1676 // Replace condition with constant True(1)/False(0).
1677 bool is_always_true = br == tb;
1678 set_req(1, igvn->intcon(is_always_true ? 1 : 0));
1679
1680 // Update any data dependencies to the directly dominating test. This subsumed test is not immediately removed by igvn
1681 // and therefore subsequent optimizations might miss these data dependencies otherwise. There might be a dead loop
1682 // ('always_taken_proj' == 'pre') that is cleaned up later. Skip this case to make the iterator work properly.
1683 Node* always_taken_proj = proj_out(is_always_true);
1684 if (always_taken_proj != pre) {
1685 for (DUIterator_Fast imax, i = always_taken_proj->fast_outs(imax); i < imax; i++) {
1686 Node* u = always_taken_proj->fast_out(i);
1687 if (!u->is_CFG()) {
1688 igvn->replace_input_of(u, 0, pre);
1689 --i;
1690 --imax;
1691 }
1692 }
1693 }
1694
1695 if (bol->outcnt() == 0) {
1696 igvn->remove_dead_node(bol); // Kill the BoolNode.
1697 }
1698 return this;
1699 }
1700
1701 // Map BoolTest to local table encoding. The BoolTest (e)numerals
1702 // { eq = 0, ne = 4, le = 5, ge = 7, lt = 3, gt = 1 }
1703 // are mapped to table indices, while the remaining (e)numerals in BoolTest
1704 // { overflow = 2, no_overflow = 6, never = 8, illegal = 9 }
1705 // are ignored (these are not modeled in the table).
1706 //
1707 static int subsuming_bool_test_encode(Node* node) {
1708 precond(node->is_Bool());
1709 BoolTest::mask x = node->as_Bool()->_test._test;
1710 switch (x) {
1711 case BoolTest::eq: return 0;
1712 case BoolTest::ne: return 1;
1713 case BoolTest::lt: return 2;
1714 case BoolTest::le: return 3;
1715 case BoolTest::gt: return 4;
1716 case BoolTest::ge: return 5;
1717 case BoolTest::overflow:
1718 case BoolTest::no_overflow:
1719 case BoolTest::never:
1720 case BoolTest::illegal:
1721 default:
1722 return -1;
1723 }
1724 }
1725
1726 //------------------------------Identity---------------------------------------
1727 // If the test is constant & we match, then we are the input Control
1728 Node* IfProjNode::Identity(PhaseGVN* phase) {
1729 // Can only optimize if cannot go the other way
1730 const TypeTuple *t = phase->type(in(0))->is_tuple();
1731 if (t == TypeTuple::IFNEITHER || (always_taken(t) &&
1732 // During parsing (GVN) we don't remove dead code aggressively.
1733 // Cut off dead branch and let PhaseRemoveUseless take care of it.
1734 (!phase->is_IterGVN() ||
1735 // During IGVN, first wait for the dead branch to be killed.
1736 // Otherwise, the IfNode's control will have two control uses (the IfNode
1737 // that doesn't go away because it still has uses and this branch of the
1738 // If) which breaks other optimizations. Node::has_special_unique_user()
1739 // will cause this node to be reprocessed once the dead branch is killed.
1740 in(0)->outcnt() == 1))) {
1741 // IfNode control
1742 if (in(0)->is_BaseCountedLoopEnd()) {
1743 // CountedLoopEndNode may be eliminated by if subsuming, replace CountedLoopNode with LoopNode to
1744 // avoid mismatching between CountedLoopNode and CountedLoopEndNode in the following optimization.
1745 Node* head = unique_ctrl_out_or_null();
1746 if (head != NULL && head->is_BaseCountedLoop() && head->in(LoopNode::LoopBackControl) == this) {
1747 Node* new_head = new LoopNode(head->in(LoopNode::EntryControl), this);
1748 phase->is_IterGVN()->register_new_node_with_optimizer(new_head);
1749 phase->is_IterGVN()->replace_node(head, new_head);
1750 }
1751 }
1752 return in(0)->in(0);
1753 }
1754 // no progress
1755 return this;
1756 }
1757
1758 #ifndef PRODUCT
1759 //------------------------------dump_spec--------------------------------------
1760 void IfNode::dump_spec(outputStream *st) const {
1761 st->print("P=%f, C=%f",_prob,_fcnt);
1762 }
1763 #endif
1764
1765 //------------------------------idealize_test----------------------------------
1766 // Try to canonicalize tests better. Peek at the Cmp/Bool/If sequence and
1767 // come up with a canonical sequence. Bools getting 'eq', 'gt' and 'ge' forms
1768 // converted to 'ne', 'le' and 'lt' forms. IfTrue/IfFalse get swapped as
1769 // needed.
1770 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff) {
1771 assert(iff->in(0) != NULL, "If must be live");
1772
1773 if (iff->outcnt() != 2) return NULL; // Malformed projections.
1774 Node* old_if_f = iff->proj_out(false);
1775 Node* old_if_t = iff->proj_out(true);
1776
1777 // CountedLoopEnds want the back-control test to be TRUE, regardless of
1778 // whether they are testing a 'gt' or 'lt' condition. The 'gt' condition
1779 // happens in count-down loops
1780 if (iff->is_BaseCountedLoopEnd()) return NULL;
1781 if (!iff->in(1)->is_Bool()) return NULL; // Happens for partially optimized IF tests
1782 BoolNode *b = iff->in(1)->as_Bool();
1783 BoolTest bt = b->_test;
1784 // Test already in good order?
1785 if( bt.is_canonical() )
1786 return NULL;
1787
1788 // Flip test to be canonical. Requires flipping the IfFalse/IfTrue and
1789 // cloning the IfNode.
1790 Node* new_b = phase->transform( new BoolNode(b->in(1), bt.negate()) );
1791 if( !new_b->is_Bool() ) return NULL;
1792 b = new_b->as_Bool();
1793
1794 PhaseIterGVN *igvn = phase->is_IterGVN();
1795 assert( igvn, "Test is not canonical in parser?" );
1796
1797 // The IF node never really changes, but it needs to be cloned
1798 iff = iff->clone()->as_If();
1799 iff->set_req(1, b);
1800 iff->_prob = 1.0-iff->_prob;
1801
1802 Node *prior = igvn->hash_find_insert(iff);
1803 if( prior ) {
1804 igvn->remove_dead_node(iff);
1805 iff = (IfNode*)prior;
1806 } else {
1807 // Cannot call transform on it just yet
1808 igvn->set_type_bottom(iff);
1809 }
1810 igvn->_worklist.push(iff);
1811
1812 // Now handle projections. Cloning not required.
1813 Node* new_if_f = (Node*)(new IfFalseNode( iff ));
1814 Node* new_if_t = (Node*)(new IfTrueNode ( iff ));
1815
1816 igvn->register_new_node_with_optimizer(new_if_f);
1817 igvn->register_new_node_with_optimizer(new_if_t);
1818 // Flip test, so flip trailing control
1819 igvn->replace_node(old_if_f, new_if_t);
1820 igvn->replace_node(old_if_t, new_if_f);
1821
1822 // Progress
1823 return iff;
1824 }
1825
1826 Node* RangeCheckNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1827 Node* res = Ideal_common(phase, can_reshape);
1828 if (res != NodeSentinel) {
1829 return res;
1830 }
1831
1832 PhaseIterGVN *igvn = phase->is_IterGVN();
1833 // Setup to scan up the CFG looking for a dominating test
1834 Node* prev_dom = this;
1835
1836 // Check for range-check vs other kinds of tests
1837 Node* index1;
1838 Node* range1;
1839 jint offset1;
1840 int flip1 = is_range_check(range1, index1, offset1);
1841 if (flip1) {
1842 Node* dom = in(0);
1843 // Try to remove extra range checks. All 'up_one_dom' gives up at merges
1844 // so all checks we inspect post-dominate the top-most check we find.
1845 // If we are going to fail the current check and we reach the top check
1846 // then we are guaranteed to fail, so just start interpreting there.
1847 // We 'expand' the top 3 range checks to include all post-dominating
1848 // checks.
1849
1850 // The top 3 range checks seen
1851 const int NRC = 3;
1852 RangeCheck prev_checks[NRC];
1853 int nb_checks = 0;
1854
1855 // Low and high offsets seen so far
1856 jint off_lo = offset1;
1857 jint off_hi = offset1;
1858
1859 bool found_immediate_dominator = false;
1860
1861 // Scan for the top checks and collect range of offsets
1862 for (int dist = 0; dist < 999; dist++) { // Range-Check scan limit
1863 if (dom->Opcode() == Op_RangeCheck && // Not same opcode?
1864 prev_dom->in(0) == dom) { // One path of test does dominate?
1865 if (dom == this) return NULL; // dead loop
1866 // See if this is a range check
1867 Node* index2;
1868 Node* range2;
1869 jint offset2;
1870 int flip2 = dom->as_RangeCheck()->is_range_check(range2, index2, offset2);
1871 // See if this is a _matching_ range check, checking against
1872 // the same array bounds.
1873 if (flip2 == flip1 && range2 == range1 && index2 == index1 &&
1874 dom->outcnt() == 2) {
1875 if (nb_checks == 0 && dom->in(1) == in(1)) {
1876 // Found an immediately dominating test at the same offset.
1877 // This kind of back-to-back test can be eliminated locally,
1878 // and there is no need to search further for dominating tests.
1879 assert(offset2 == offset1, "Same test but different offsets");
1880 found_immediate_dominator = true;
1881 break;
1882 }
1883 // Gather expanded bounds
1884 off_lo = MIN2(off_lo,offset2);
1885 off_hi = MAX2(off_hi,offset2);
1886 // Record top NRC range checks
1887 prev_checks[nb_checks%NRC].ctl = prev_dom;
1888 prev_checks[nb_checks%NRC].off = offset2;
1889 nb_checks++;
1890 }
1891 }
1892 prev_dom = dom;
1893 dom = up_one_dom(dom);
1894 if (!dom) break;
1895 }
1896
1897 if (!found_immediate_dominator) {
1898 // Attempt to widen the dominating range check to cover some later
1899 // ones. Since range checks "fail" by uncommon-trapping to the
1900 // interpreter, widening a check can make us speculatively enter
1901 // the interpreter. If we see range-check deopt's, do not widen!
1902 if (!phase->C->allow_range_check_smearing()) return NULL;
1903
1904 // Didn't find prior covering check, so cannot remove anything.
1905 if (nb_checks == 0) {
1906 return NULL;
1907 }
1908 // Constant indices only need to check the upper bound.
1909 // Non-constant indices must check both low and high.
1910 int chk0 = (nb_checks - 1) % NRC;
1911 if (index1) {
1912 if (nb_checks == 1) {
1913 return NULL;
1914 } else {
1915 // If the top range check's constant is the min or max of
1916 // all constants we widen the next one to cover the whole
1917 // range of constants.
1918 RangeCheck rc0 = prev_checks[chk0];
1919 int chk1 = (nb_checks - 2) % NRC;
1920 RangeCheck rc1 = prev_checks[chk1];
1921 if (rc0.off == off_lo) {
1922 adjust_check(rc1.ctl, range1, index1, flip1, off_hi, igvn);
1923 prev_dom = rc1.ctl;
1924 } else if (rc0.off == off_hi) {
1925 adjust_check(rc1.ctl, range1, index1, flip1, off_lo, igvn);
1926 prev_dom = rc1.ctl;
1927 } else {
1928 // If the top test's constant is not the min or max of all
1929 // constants, we need 3 range checks. We must leave the
1930 // top test unchanged because widening it would allow the
1931 // accesses it protects to successfully read/write out of
1932 // bounds.
1933 if (nb_checks == 2) {
1934 return NULL;
1935 }
1936 int chk2 = (nb_checks - 3) % NRC;
1937 RangeCheck rc2 = prev_checks[chk2];
1938 // The top range check a+i covers interval: -a <= i < length-a
1939 // The second range check b+i covers interval: -b <= i < length-b
1940 if (rc1.off <= rc0.off) {
1941 // if b <= a, we change the second range check to:
1942 // -min_of_all_constants <= i < length-min_of_all_constants
1943 // Together top and second range checks now cover:
1944 // -min_of_all_constants <= i < length-a
1945 // which is more restrictive than -b <= i < length-b:
1946 // -b <= -min_of_all_constants <= i < length-a <= length-b
1947 // The third check is then changed to:
1948 // -max_of_all_constants <= i < length-max_of_all_constants
1949 // so 2nd and 3rd checks restrict allowed values of i to:
1950 // -min_of_all_constants <= i < length-max_of_all_constants
1951 adjust_check(rc1.ctl, range1, index1, flip1, off_lo, igvn);
1952 adjust_check(rc2.ctl, range1, index1, flip1, off_hi, igvn);
1953 } else {
1954 // if b > a, we change the second range check to:
1955 // -max_of_all_constants <= i < length-max_of_all_constants
1956 // Together top and second range checks now cover:
1957 // -a <= i < length-max_of_all_constants
1958 // which is more restrictive than -b <= i < length-b:
1959 // -b < -a <= i < length-max_of_all_constants <= length-b
1960 // The third check is then changed to:
1961 // -max_of_all_constants <= i < length-max_of_all_constants
1962 // so 2nd and 3rd checks restrict allowed values of i to:
1963 // -min_of_all_constants <= i < length-max_of_all_constants
1964 adjust_check(rc1.ctl, range1, index1, flip1, off_hi, igvn);
1965 adjust_check(rc2.ctl, range1, index1, flip1, off_lo, igvn);
1966 }
1967 prev_dom = rc2.ctl;
1968 }
1969 }
1970 } else {
1971 RangeCheck rc0 = prev_checks[chk0];
1972 // 'Widen' the offset of the 1st and only covering check
1973 adjust_check(rc0.ctl, range1, index1, flip1, off_hi, igvn);
1974 // Test is now covered by prior checks, dominate it out
1975 prev_dom = rc0.ctl;
1976 }
1977 }
1978 } else {
1979 prev_dom = search_identical(4);
1980
1981 if (prev_dom == NULL) {
1982 return NULL;
1983 }
1984 }
1985
1986 // Replace dominated IfNode
1987 return dominated_by(prev_dom, igvn);
1988 }