Tue, 17 May 2011 19:11:51 -0700
7045513: JSR 292 inlining causes crashes in methodHandleWalk.cpp
Reviewed-by: jrose
1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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_Cmp() ) return NULL;
80 i1 = cmp->in(1);
81 if( i1 == NULL || !i1->is_Phi() ) return NULL;
82 PhiNode *phi = i1->as_Phi();
83 if( phi->is_copy() ) return NULL;
84 Node *con2 = cmp->in(2);
85 if( !con2->is_Con() ) return NULL;
86 // See that the merge point contains some constants
87 Node *con1=NULL;
88 uint i4;
89 for( i4 = 1; i4 < phi->req(); i4++ ) {
90 con1 = phi->in(i4);
91 if( !con1 ) return NULL; // Do not optimize partially collapsed merges
92 if( con1->is_Con() ) break; // Found a constant
93 // Also allow null-vs-not-null checks
94 const TypePtr *tp = igvn->type(con1)->isa_ptr();
95 if( tp && tp->_ptr == TypePtr::NotNull )
96 break;
97 }
98 if( i4 >= phi->req() ) return NULL; // Found no constants
100 igvn->C->set_has_split_ifs(true); // Has chance for split-if
102 // Make sure that the compare can be constant folded away
103 Node *cmp2 = cmp->clone();
104 cmp2->set_req(1,con1);
105 cmp2->set_req(2,con2);
106 const Type *t = cmp2->Value(igvn);
107 // This compare is dead, so whack it!
108 igvn->remove_dead_node(cmp2);
109 if( !t->singleton() ) return NULL;
111 // No intervening control, like a simple Call
112 Node *r = iff->in(0);
113 if( !r->is_Region() ) return NULL;
114 if( phi->region() != r ) return NULL;
115 // No other users of the cmp/bool
116 if (b->outcnt() != 1 || cmp->outcnt() != 1) {
117 //tty->print_cr("many users of cmp/bool");
118 return NULL;
119 }
121 // Make sure we can determine where all the uses of merged values go
122 for (DUIterator_Fast jmax, j = r->fast_outs(jmax); j < jmax; j++) {
123 Node* u = r->fast_out(j);
124 if( u == r ) continue;
125 if( u == iff ) continue;
126 if( u->outcnt() == 0 ) continue; // use is dead & ignorable
127 if( !u->is_Phi() ) {
128 /*
129 if( u->is_Start() ) {
130 tty->print_cr("Region has inlined start use");
131 } else {
132 tty->print_cr("Region has odd use");
133 u->dump(2);
134 }*/
135 return NULL;
136 }
137 if( u != phi ) {
138 // CNC - do not allow any other merged value
139 //tty->print_cr("Merging another value");
140 //u->dump(2);
141 return NULL;
142 }
143 // Make sure we can account for all Phi uses
144 for (DUIterator_Fast kmax, k = u->fast_outs(kmax); k < kmax; k++) {
145 Node* v = u->fast_out(k); // User of the phi
146 // CNC - Allow only really simple patterns.
147 // In particular I disallow AddP of the Phi, a fairly common pattern
148 if( v == cmp ) continue; // The compare is OK
149 if( (v->is_ConstraintCast()) &&
150 v->in(0)->in(0) == iff )
151 continue; // CastPP/II of the IfNode is OK
152 // Disabled following code because I cannot tell if exactly one
153 // path dominates without a real dominator check. CNC 9/9/1999
154 //uint vop = v->Opcode();
155 //if( vop == Op_Phi ) { // Phi from another merge point might be OK
156 // Node *r = v->in(0); // Get controlling point
157 // if( !r ) return NULL; // Degraded to a copy
158 // // Find exactly one path in (either True or False doms, but not IFF)
159 // int cnt = 0;
160 // for( uint i = 1; i < r->req(); i++ )
161 // if( r->in(i) && r->in(i)->in(0) == iff )
162 // cnt++;
163 // if( cnt == 1 ) continue; // Exactly one of True or False guards Phi
164 //}
165 if( !v->is_Call() ) {
166 /*
167 if( v->Opcode() == Op_AddP ) {
168 tty->print_cr("Phi has AddP use");
169 } else if( v->Opcode() == Op_CastPP ) {
170 tty->print_cr("Phi has CastPP use");
171 } else if( v->Opcode() == Op_CastII ) {
172 tty->print_cr("Phi has CastII use");
173 } else {
174 tty->print_cr("Phi has use I cant be bothered with");
175 }
176 */
177 }
178 return NULL;
180 /* CNC - Cut out all the fancy acceptance tests
181 // Can we clone this use when doing the transformation?
182 // If all uses are from Phis at this merge or constants, then YES.
183 if( !v->in(0) && v != cmp ) {
184 tty->print_cr("Phi has free-floating use");
185 v->dump(2);
186 return NULL;
187 }
188 for( uint l = 1; l < v->req(); l++ ) {
189 if( (!v->in(l)->is_Phi() || v->in(l)->in(0) != r) &&
190 !v->in(l)->is_Con() ) {
191 tty->print_cr("Phi has use");
192 v->dump(2);
193 return NULL;
194 } // End of if Phi-use input is neither Phi nor Constant
195 } // End of for all inputs to Phi-use
196 */
197 } // End of for all uses of Phi
198 } // End of for all uses of Region
200 // Only do this if the IF node is in a sane state
201 if (iff->outcnt() != 2)
202 return NULL;
204 // Got a hit! Do the Mondo Hack!
205 //
206 //ABC a1c def ghi B 1 e h A C a c d f g i
207 // R - Phi - Phi - Phi Rc - Phi - Phi - Phi Rx - Phi - Phi - Phi
208 // cmp - 2 cmp - 2 cmp - 2
209 // bool bool_c bool_x
210 // if if_c if_x
211 // T F T F T F
212 // ..s.. ..t .. ..s.. ..t.. ..s.. ..t..
213 //
214 // Split the paths coming into the merge point into 2 separate groups of
215 // merges. On the left will be all the paths feeding constants into the
216 // Cmp's Phi. On the right will be the remaining paths. The Cmp's Phi
217 // will fold up into a constant; this will let the Cmp fold up as well as
218 // all the control flow. Below the original IF we have 2 control
219 // dependent regions, 's' and 't'. Now we will merge the two paths
220 // just prior to 's' and 't' from the two IFs. At least 1 path (and quite
221 // likely 2 or more) will promptly constant fold away.
222 PhaseGVN *phase = igvn;
224 // Make a region merging constants and a region merging the rest
225 uint req_c = 0;
226 Node* predicate_proj = NULL;
227 for (uint ii = 1; ii < r->req(); ii++) {
228 if (phi->in(ii) == con1) {
229 req_c++;
230 }
231 Node* proj = PhaseIdealLoop::find_predicate(r->in(ii));
232 if (proj != NULL) {
233 assert(predicate_proj == NULL, "only one predicate entry expected");
234 predicate_proj = proj;
235 }
236 }
237 Node* predicate_c = NULL;
238 Node* predicate_x = NULL;
239 bool counted_loop = r->is_CountedLoop();
241 Node *region_c = new (igvn->C, req_c + 1) RegionNode(req_c + 1);
242 Node *phi_c = con1;
243 uint len = r->req();
244 Node *region_x = new (igvn->C, len - req_c) RegionNode(len - req_c);
245 Node *phi_x = PhiNode::make_blank(region_x, phi);
246 for (uint i = 1, i_c = 1, i_x = 1; i < len; i++) {
247 if (phi->in(i) == con1) {
248 region_c->init_req( i_c++, r ->in(i) );
249 if (r->in(i) == predicate_proj)
250 predicate_c = predicate_proj;
251 } else {
252 region_x->init_req( i_x, r ->in(i) );
253 phi_x ->init_req( i_x++, phi->in(i) );
254 if (r->in(i) == predicate_proj)
255 predicate_x = predicate_proj;
256 }
257 }
259 // Register the new RegionNodes but do not transform them. Cannot
260 // transform until the entire Region/Phi conglomerate has been hacked
261 // as a single huge transform.
262 igvn->register_new_node_with_optimizer( region_c );
263 igvn->register_new_node_with_optimizer( region_x );
264 // Prevent the untimely death of phi_x. Currently he has no uses. He is
265 // about to get one. If this only use goes away, then phi_x will look dead.
266 // However, he will be picking up some more uses down below.
267 Node *hook = new (igvn->C, 4) Node(4);
268 hook->init_req(0, phi_x);
269 hook->init_req(1, phi_c);
270 phi_x = phase->transform( phi_x );
272 // Make the compare
273 Node *cmp_c = phase->makecon(t);
274 Node *cmp_x = cmp->clone();
275 cmp_x->set_req(1,phi_x);
276 cmp_x->set_req(2,con2);
277 cmp_x = phase->transform(cmp_x);
278 // Make the bool
279 Node *b_c = phase->transform(new (igvn->C, 2) BoolNode(cmp_c,b->_test._test));
280 Node *b_x = phase->transform(new (igvn->C, 2) BoolNode(cmp_x,b->_test._test));
281 // Make the IfNode
282 IfNode *iff_c = new (igvn->C, 2) IfNode(region_c,b_c,iff->_prob,iff->_fcnt);
283 igvn->set_type_bottom(iff_c);
284 igvn->_worklist.push(iff_c);
285 hook->init_req(2, iff_c);
287 IfNode *iff_x = new (igvn->C, 2) IfNode(region_x,b_x,iff->_prob, iff->_fcnt);
288 igvn->set_type_bottom(iff_x);
289 igvn->_worklist.push(iff_x);
290 hook->init_req(3, iff_x);
292 // Make the true/false arms
293 Node *iff_c_t = phase->transform(new (igvn->C, 1) IfTrueNode (iff_c));
294 Node *iff_c_f = phase->transform(new (igvn->C, 1) IfFalseNode(iff_c));
295 if (predicate_c != NULL) {
296 assert(predicate_x == NULL, "only one predicate entry expected");
297 // Clone loop predicates to each path
298 iff_c_t = igvn->clone_loop_predicates(predicate_c, iff_c_t, !counted_loop);
299 iff_c_f = igvn->clone_loop_predicates(predicate_c, iff_c_f, !counted_loop);
300 }
301 Node *iff_x_t = phase->transform(new (igvn->C, 1) IfTrueNode (iff_x));
302 Node *iff_x_f = phase->transform(new (igvn->C, 1) IfFalseNode(iff_x));
303 if (predicate_x != NULL) {
304 assert(predicate_c == NULL, "only one predicate entry expected");
305 // Clone loop predicates to each path
306 iff_x_t = igvn->clone_loop_predicates(predicate_x, iff_x_t, !counted_loop);
307 iff_x_f = igvn->clone_loop_predicates(predicate_x, iff_x_f, !counted_loop);
308 }
310 // Merge the TRUE paths
311 Node *region_s = new (igvn->C, 3) RegionNode(3);
312 igvn->_worklist.push(region_s);
313 region_s->init_req(1, iff_c_t);
314 region_s->init_req(2, iff_x_t);
315 igvn->register_new_node_with_optimizer( region_s );
317 // Merge the FALSE paths
318 Node *region_f = new (igvn->C, 3) RegionNode(3);
319 igvn->_worklist.push(region_f);
320 region_f->init_req(1, iff_c_f);
321 region_f->init_req(2, iff_x_f);
322 igvn->register_new_node_with_optimizer( region_f );
324 igvn->hash_delete(cmp);// Remove soon-to-be-dead node from hash table.
325 cmp->set_req(1,NULL); // Whack the inputs to cmp because it will be dead
326 cmp->set_req(2,NULL);
327 // Check for all uses of the Phi and give them a new home.
328 // The 'cmp' got cloned, but CastPP/IIs need to be moved.
329 Node *phi_s = NULL; // do not construct unless needed
330 Node *phi_f = NULL; // do not construct unless needed
331 for (DUIterator_Last i2min, i2 = phi->last_outs(i2min); i2 >= i2min; --i2) {
332 Node* v = phi->last_out(i2);// User of the phi
333 igvn->hash_delete(v); // Have to fixup other Phi users
334 igvn->_worklist.push(v);
335 uint vop = v->Opcode();
336 Node *proj = NULL;
337 if( vop == Op_Phi ) { // Remote merge point
338 Node *r = v->in(0);
339 for (uint i3 = 1; i3 < r->req(); i3++)
340 if (r->in(i3) && r->in(i3)->in(0) == iff) {
341 proj = r->in(i3);
342 break;
343 }
344 } else if( v->is_ConstraintCast() ) {
345 proj = v->in(0); // Controlling projection
346 } else {
347 assert( 0, "do not know how to handle this guy" );
348 }
350 Node *proj_path_data, *proj_path_ctrl;
351 if( proj->Opcode() == Op_IfTrue ) {
352 if( phi_s == NULL ) {
353 // Only construct phi_s if needed, otherwise provides
354 // interfering use.
355 phi_s = PhiNode::make_blank(region_s,phi);
356 phi_s->init_req( 1, phi_c );
357 phi_s->init_req( 2, phi_x );
358 hook->add_req(phi_s);
359 phi_s = phase->transform(phi_s);
360 }
361 proj_path_data = phi_s;
362 proj_path_ctrl = region_s;
363 } else {
364 if( phi_f == NULL ) {
365 // Only construct phi_f if needed, otherwise provides
366 // interfering use.
367 phi_f = PhiNode::make_blank(region_f,phi);
368 phi_f->init_req( 1, phi_c );
369 phi_f->init_req( 2, phi_x );
370 hook->add_req(phi_f);
371 phi_f = phase->transform(phi_f);
372 }
373 proj_path_data = phi_f;
374 proj_path_ctrl = region_f;
375 }
377 // Fixup 'v' for for the split
378 if( vop == Op_Phi ) { // Remote merge point
379 uint i;
380 for( i = 1; i < v->req(); i++ )
381 if( v->in(i) == phi )
382 break;
383 v->set_req(i, proj_path_data );
384 } else if( v->is_ConstraintCast() ) {
385 v->set_req(0, proj_path_ctrl );
386 v->set_req(1, proj_path_data );
387 } else
388 ShouldNotReachHere();
389 }
391 // Now replace the original iff's True/False with region_s/region_t.
392 // This makes the original iff go dead.
393 for (DUIterator_Last i3min, i3 = iff->last_outs(i3min); i3 >= i3min; --i3) {
394 Node* p = iff->last_out(i3);
395 assert( p->Opcode() == Op_IfTrue || p->Opcode() == Op_IfFalse, "" );
396 Node *u = (p->Opcode() == Op_IfTrue) ? region_s : region_f;
397 // Replace p with u
398 igvn->add_users_to_worklist(p);
399 for (DUIterator_Last lmin, l = p->last_outs(lmin); l >= lmin;) {
400 Node* x = p->last_out(l);
401 igvn->hash_delete(x);
402 uint uses_found = 0;
403 for( uint j = 0; j < x->req(); j++ ) {
404 if( x->in(j) == p ) {
405 x->set_req(j, u);
406 uses_found++;
407 }
408 }
409 l -= uses_found; // we deleted 1 or more copies of this edge
410 }
411 igvn->remove_dead_node(p);
412 }
414 // Force the original merge dead
415 igvn->hash_delete(r);
416 // First, remove region's dead users.
417 for (DUIterator_Last lmin, l = r->last_outs(lmin); l >= lmin;) {
418 Node* u = r->last_out(l);
419 if( u == r ) {
420 r->set_req(0, NULL);
421 } else {
422 assert(u->outcnt() == 0, "only dead users");
423 igvn->remove_dead_node(u);
424 }
425 l -= 1;
426 }
427 igvn->remove_dead_node(r);
429 // Now remove the bogus extra edges used to keep things alive
430 igvn->remove_dead_node( hook );
432 // Must return either the original node (now dead) or a new node
433 // (Do not return a top here, since that would break the uniqueness of top.)
434 return new (igvn->C, 1) ConINode(TypeInt::ZERO);
435 }
437 //------------------------------is_range_check---------------------------------
438 // Return 0 if not a range check. Return 1 if a range check and set index and
439 // offset. Return 2 if we had to negate the test. Index is NULL if the check
440 // is versus a constant.
441 int IfNode::is_range_check(Node* &range, Node* &index, jint &offset) {
442 Node* b = in(1);
443 if (b == NULL || !b->is_Bool()) return 0;
444 BoolNode* bn = b->as_Bool();
445 Node* cmp = bn->in(1);
446 if (cmp == NULL) return 0;
447 if (cmp->Opcode() != Op_CmpU) return 0;
449 Node* l = cmp->in(1);
450 Node* r = cmp->in(2);
451 int flip_test = 1;
452 if (bn->_test._test == BoolTest::le) {
453 l = cmp->in(2);
454 r = cmp->in(1);
455 flip_test = 2;
456 } else if (bn->_test._test != BoolTest::lt) {
457 return 0;
458 }
459 if (l->is_top()) return 0; // Top input means dead test
460 if (r->Opcode() != Op_LoadRange) return 0;
462 // We have recognized one of these forms:
463 // Flip 1: If (Bool[<] CmpU(l, LoadRange)) ...
464 // Flip 2: If (Bool[<=] CmpU(LoadRange, l)) ...
466 // Make sure it's a real range check by requiring an uncommon trap
467 // along the OOB path. Otherwise, it's possible that the user wrote
468 // something which optimized to look like a range check but behaves
469 // in some other way.
470 Node* iftrap = proj_out(flip_test == 2 ? true : false);
471 bool found_trap = false;
472 if (iftrap != NULL) {
473 Node* u = iftrap->unique_ctrl_out();
474 if (u != NULL) {
475 // It could be a merge point (Region) for uncommon trap.
476 if (u->is_Region()) {
477 Node* c = u->unique_ctrl_out();
478 if (c != NULL) {
479 iftrap = u;
480 u = c;
481 }
482 }
483 if (u->in(0) == iftrap && u->is_CallStaticJava()) {
484 int req = u->as_CallStaticJava()->uncommon_trap_request();
485 if (Deoptimization::trap_request_reason(req) ==
486 Deoptimization::Reason_range_check) {
487 found_trap = true;
488 }
489 }
490 }
491 }
492 if (!found_trap) return 0; // sorry, no cigar
494 // Look for index+offset form
495 Node* ind = l;
496 jint off = 0;
497 if (l->is_top()) {
498 return 0;
499 } else if (l->is_Add()) {
500 if ((off = l->in(1)->find_int_con(0)) != 0) {
501 ind = l->in(2);
502 } else if ((off = l->in(2)->find_int_con(0)) != 0) {
503 ind = l->in(1);
504 }
505 } else if ((off = l->find_int_con(-1)) >= 0) {
506 // constant offset with no variable index
507 ind = NULL;
508 } else {
509 // variable index with no constant offset (or dead negative index)
510 off = 0;
511 }
513 // Return all the values:
514 index = ind;
515 offset = off;
516 range = r;
517 return flip_test;
518 }
520 //------------------------------adjust_check-----------------------------------
521 // Adjust (widen) a prior range check
522 static void adjust_check(Node* proj, Node* range, Node* index,
523 int flip, jint off_lo, PhaseIterGVN* igvn) {
524 PhaseGVN *gvn = igvn;
525 // Break apart the old check
526 Node *iff = proj->in(0);
527 Node *bol = iff->in(1);
528 if( bol->is_top() ) return; // In case a partially dead range check appears
529 // bail (or bomb[ASSERT/DEBUG]) if NOT projection-->IfNode-->BoolNode
530 DEBUG_ONLY( if( !bol->is_Bool() ) { proj->dump(3); fatal("Expect projection-->IfNode-->BoolNode"); } )
531 if( !bol->is_Bool() ) return;
533 Node *cmp = bol->in(1);
534 // Compute a new check
535 Node *new_add = gvn->intcon(off_lo);
536 if( index ) {
537 new_add = off_lo ? gvn->transform(new (gvn->C, 3) AddINode( index, new_add )) : index;
538 }
539 Node *new_cmp = (flip == 1)
540 ? new (gvn->C, 3) CmpUNode( new_add, range )
541 : new (gvn->C, 3) CmpUNode( range, new_add );
542 new_cmp = gvn->transform(new_cmp);
543 // See if no need to adjust the existing check
544 if( new_cmp == cmp ) return;
545 // Else, adjust existing check
546 Node *new_bol = gvn->transform( new (gvn->C, 2) BoolNode( new_cmp, bol->as_Bool()->_test._test ) );
547 igvn->hash_delete( iff );
548 iff->set_req_X( 1, new_bol, igvn );
549 igvn->_worklist.push( iff );
550 }
552 //------------------------------up_one_dom-------------------------------------
553 // Walk up the dominator tree one step. Return NULL at root or true
554 // complex merges. Skips through small diamonds.
555 Node* IfNode::up_one_dom(Node *curr, bool linear_only) {
556 Node *dom = curr->in(0);
557 if( !dom ) // Found a Region degraded to a copy?
558 return curr->nonnull_req(); // Skip thru it
560 if( curr != dom ) // Normal walk up one step?
561 return dom;
563 // Use linear_only if we are still parsing, since we cannot
564 // trust the regions to be fully filled in.
565 if (linear_only)
566 return NULL;
568 if( dom->is_Root() )
569 return NULL;
571 // Else hit a Region. Check for a loop header
572 if( dom->is_Loop() )
573 return dom->in(1); // Skip up thru loops
575 // Check for small diamonds
576 Node *din1, *din2, *din3, *din4;
577 if( dom->req() == 3 && // 2-path merge point
578 (din1 = dom ->in(1)) && // Left path exists
579 (din2 = dom ->in(2)) && // Right path exists
580 (din3 = din1->in(0)) && // Left path up one
581 (din4 = din2->in(0)) ) { // Right path up one
582 if( din3->is_Call() && // Handle a slow-path call on either arm
583 (din3 = din3->in(0)) )
584 din3 = din3->in(0);
585 if( din4->is_Call() && // Handle a slow-path call on either arm
586 (din4 = din4->in(0)) )
587 din4 = din4->in(0);
588 if( din3 == din4 && din3->is_If() )
589 return din3; // Skip around diamonds
590 }
592 // Give up the search at true merges
593 return NULL; // Dead loop? Or hit root?
594 }
597 //------------------------------filtered_int_type--------------------------------
598 // Return a possibly more restrictive type for val based on condition control flow for an if
599 const TypeInt* IfNode::filtered_int_type(PhaseGVN* gvn, Node *val, Node* if_proj) {
600 assert(if_proj &&
601 (if_proj->Opcode() == Op_IfTrue || if_proj->Opcode() == Op_IfFalse), "expecting an if projection");
602 if (if_proj->in(0) && if_proj->in(0)->is_If()) {
603 IfNode* iff = if_proj->in(0)->as_If();
604 if (iff->in(1) && iff->in(1)->is_Bool()) {
605 BoolNode* bol = iff->in(1)->as_Bool();
606 if (bol->in(1) && bol->in(1)->is_Cmp()) {
607 const CmpNode* cmp = bol->in(1)->as_Cmp();
608 if (cmp->in(1) == val) {
609 const TypeInt* cmp2_t = gvn->type(cmp->in(2))->isa_int();
610 if (cmp2_t != NULL) {
611 jint lo = cmp2_t->_lo;
612 jint hi = cmp2_t->_hi;
613 BoolTest::mask msk = if_proj->Opcode() == Op_IfTrue ? bol->_test._test : bol->_test.negate();
614 switch (msk) {
615 case BoolTest::ne:
616 // Can't refine type
617 return NULL;
618 case BoolTest::eq:
619 return cmp2_t;
620 case BoolTest::lt:
621 lo = TypeInt::INT->_lo;
622 if (hi - 1 < hi) {
623 hi = hi - 1;
624 }
625 break;
626 case BoolTest::le:
627 lo = TypeInt::INT->_lo;
628 break;
629 case BoolTest::gt:
630 if (lo + 1 > lo) {
631 lo = lo + 1;
632 }
633 hi = TypeInt::INT->_hi;
634 break;
635 case BoolTest::ge:
636 // lo unchanged
637 hi = TypeInt::INT->_hi;
638 break;
639 }
640 const TypeInt* rtn_t = TypeInt::make(lo, hi, cmp2_t->_widen);
641 return rtn_t;
642 }
643 }
644 }
645 }
646 }
647 return NULL;
648 }
650 //------------------------------fold_compares----------------------------
651 // See if a pair of CmpIs can be converted into a CmpU. In some cases
652 // the direction of this if is determined by the preceding if so it
653 // can be eliminate entirely. Given an if testing (CmpI n c) check
654 // for an immediately control dependent if that is testing (CmpI n c2)
655 // and has one projection leading to this if and the other projection
656 // leading to a region that merges one of this ifs control
657 // projections.
658 //
659 // If
660 // / |
661 // / |
662 // / |
663 // If |
664 // /\ |
665 // / \ |
666 // / \ |
667 // / Region
668 //
669 Node* IfNode::fold_compares(PhaseGVN* phase) {
670 if (!EliminateAutoBox || Opcode() != Op_If) return NULL;
672 Node* this_cmp = in(1)->in(1);
673 if (this_cmp != NULL && this_cmp->Opcode() == Op_CmpI &&
674 this_cmp->in(2)->is_Con() && this_cmp->in(2) != phase->C->top()) {
675 Node* ctrl = in(0);
676 BoolNode* this_bool = in(1)->as_Bool();
677 Node* n = this_cmp->in(1);
678 int hi = this_cmp->in(2)->get_int();
679 if (ctrl != NULL && ctrl->is_Proj() && ctrl->outcnt() == 1 &&
680 ctrl->in(0)->is_If() &&
681 ctrl->in(0)->outcnt() == 2 &&
682 ctrl->in(0)->in(1)->is_Bool() &&
683 ctrl->in(0)->in(1)->in(1)->Opcode() == Op_CmpI &&
684 ctrl->in(0)->in(1)->in(1)->in(2)->is_Con() &&
685 ctrl->in(0)->in(1)->in(1)->in(1) == n) {
686 IfNode* dom_iff = ctrl->in(0)->as_If();
687 Node* otherproj = dom_iff->proj_out(!ctrl->as_Proj()->_con);
688 if (otherproj->outcnt() == 1 && otherproj->unique_out()->is_Region() &&
689 this_bool->_test._test != BoolTest::ne && this_bool->_test._test != BoolTest::eq) {
690 // Identify which proj goes to the region and which continues on
691 RegionNode* region = otherproj->unique_out()->as_Region();
692 Node* success = NULL;
693 Node* fail = NULL;
694 for (int i = 0; i < 2; i++) {
695 Node* proj = proj_out(i);
696 if (success == NULL && proj->outcnt() == 1 && proj->unique_out() == region) {
697 success = proj;
698 } else if (fail == NULL) {
699 fail = proj;
700 } else {
701 success = fail = NULL;
702 }
703 }
704 if (success != NULL && fail != NULL && !region->has_phi()) {
705 int lo = dom_iff->in(1)->in(1)->in(2)->get_int();
706 BoolNode* dom_bool = dom_iff->in(1)->as_Bool();
707 Node* dom_cmp = dom_bool->in(1);
708 const TypeInt* failtype = filtered_int_type(phase, n, ctrl);
709 if (failtype != NULL) {
710 const TypeInt* type2 = filtered_int_type(phase, n, fail);
711 if (type2 != NULL) {
712 failtype = failtype->join(type2)->is_int();
713 } else {
714 failtype = NULL;
715 }
716 }
718 if (failtype != NULL &&
719 dom_bool->_test._test != BoolTest::ne && dom_bool->_test._test != BoolTest::eq) {
720 int bound = failtype->_hi - failtype->_lo + 1;
721 if (failtype->_hi != max_jint && failtype->_lo != min_jint && bound > 1) {
722 // Merge the two compares into a single unsigned compare by building (CmpU (n - lo) hi)
723 BoolTest::mask cond = fail->as_Proj()->_con ? BoolTest::lt : BoolTest::ge;
724 Node* adjusted = phase->transform(new (phase->C, 3) SubINode(n, phase->intcon(failtype->_lo)));
725 Node* newcmp = phase->transform(new (phase->C, 3) CmpUNode(adjusted, phase->intcon(bound)));
726 Node* newbool = phase->transform(new (phase->C, 2) BoolNode(newcmp, cond));
727 phase->hash_delete(dom_iff);
728 dom_iff->set_req(1, phase->intcon(ctrl->as_Proj()->_con));
729 phase->is_IterGVN()->_worklist.push(dom_iff);
730 phase->hash_delete(this);
731 set_req(1, newbool);
732 return this;
733 }
734 if (failtype->_lo > failtype->_hi) {
735 // previous if determines the result of this if so
736 // replace Bool with constant
737 phase->hash_delete(this);
738 set_req(1, phase->intcon(success->as_Proj()->_con));
739 return this;
740 }
741 }
742 }
743 }
744 }
745 }
746 return NULL;
747 }
749 //------------------------------remove_useless_bool----------------------------
750 // Check for people making a useless boolean: things like
751 // if( (x < y ? true : false) ) { ... }
752 // Replace with if( x < y ) { ... }
753 static Node *remove_useless_bool(IfNode *iff, PhaseGVN *phase) {
754 Node *i1 = iff->in(1);
755 if( !i1->is_Bool() ) return NULL;
756 BoolNode *bol = i1->as_Bool();
758 Node *cmp = bol->in(1);
759 if( cmp->Opcode() != Op_CmpI ) return NULL;
761 // Must be comparing against a bool
762 const Type *cmp2_t = phase->type( cmp->in(2) );
763 if( cmp2_t != TypeInt::ZERO &&
764 cmp2_t != TypeInt::ONE )
765 return NULL;
767 // Find a prior merge point merging the boolean
768 i1 = cmp->in(1);
769 if( !i1->is_Phi() ) return NULL;
770 PhiNode *phi = i1->as_Phi();
771 if( phase->type( phi ) != TypeInt::BOOL )
772 return NULL;
774 // Check for diamond pattern
775 int true_path = phi->is_diamond_phi();
776 if( true_path == 0 ) return NULL;
778 // Make sure that iff and the control of the phi are different. This
779 // should really only happen for dead control flow since it requires
780 // an illegal cycle.
781 if (phi->in(0)->in(1)->in(0) == iff) return NULL;
783 // phi->region->if_proj->ifnode->bool->cmp
784 BoolNode *bol2 = phi->in(0)->in(1)->in(0)->in(1)->as_Bool();
786 // Now get the 'sense' of the test correct so we can plug in
787 // either iff2->in(1) or its complement.
788 int flip = 0;
789 if( bol->_test._test == BoolTest::ne ) flip = 1-flip;
790 else if( bol->_test._test != BoolTest::eq ) return NULL;
791 if( cmp2_t == TypeInt::ZERO ) flip = 1-flip;
793 const Type *phi1_t = phase->type( phi->in(1) );
794 const Type *phi2_t = phase->type( phi->in(2) );
795 // Check for Phi(0,1) and flip
796 if( phi1_t == TypeInt::ZERO ) {
797 if( phi2_t != TypeInt::ONE ) return NULL;
798 flip = 1-flip;
799 } else {
800 // Check for Phi(1,0)
801 if( phi1_t != TypeInt::ONE ) return NULL;
802 if( phi2_t != TypeInt::ZERO ) return NULL;
803 }
804 if( true_path == 2 ) {
805 flip = 1-flip;
806 }
808 Node* new_bol = (flip ? phase->transform( bol2->negate(phase) ) : bol2);
809 assert(new_bol != iff->in(1), "must make progress");
810 iff->set_req(1, new_bol);
811 // Intervening diamond probably goes dead
812 phase->C->set_major_progress();
813 return iff;
814 }
816 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff);
818 //------------------------------Ideal------------------------------------------
819 // Return a node which is more "ideal" than the current node. Strip out
820 // control copies
821 Node *IfNode::Ideal(PhaseGVN *phase, bool can_reshape) {
822 if (remove_dead_region(phase, can_reshape)) return this;
823 // No Def-Use info?
824 if (!can_reshape) return NULL;
825 PhaseIterGVN *igvn = phase->is_IterGVN();
827 // Don't bother trying to transform a dead if
828 if (in(0)->is_top()) return NULL;
829 // Don't bother trying to transform an if with a dead test
830 if (in(1)->is_top()) return NULL;
831 // Another variation of a dead test
832 if (in(1)->is_Con()) return NULL;
833 // Another variation of a dead if
834 if (outcnt() < 2) return NULL;
836 // Canonicalize the test.
837 Node* idt_if = idealize_test(phase, this);
838 if (idt_if != NULL) return idt_if;
840 // Try to split the IF
841 Node *s = split_if(this, igvn);
842 if (s != NULL) return s;
844 // Check for people making a useless boolean: things like
845 // if( (x < y ? true : false) ) { ... }
846 // Replace with if( x < y ) { ... }
847 Node *bol2 = remove_useless_bool(this, phase);
848 if( bol2 ) return bol2;
850 // Setup to scan up the CFG looking for a dominating test
851 Node *dom = in(0);
852 Node *prev_dom = this;
854 // Check for range-check vs other kinds of tests
855 Node *index1, *range1;
856 jint offset1;
857 int flip1 = is_range_check(range1, index1, offset1);
858 if( flip1 ) {
859 Node *first_prev_dom = NULL;
861 // Try to remove extra range checks. All 'up_one_dom' gives up at merges
862 // so all checks we inspect post-dominate the top-most check we find.
863 // If we are going to fail the current check and we reach the top check
864 // then we are guaranteed to fail, so just start interpreting there.
865 // We 'expand' the top 2 range checks to include all post-dominating
866 // checks.
868 // The top 2 range checks seen
869 Node *prev_chk1 = NULL;
870 Node *prev_chk2 = NULL;
871 // Low and high offsets seen so far
872 jint off_lo = offset1;
873 jint off_hi = offset1;
875 // Scan for the top 2 checks and collect range of offsets
876 for( int dist = 0; dist < 999; dist++ ) { // Range-Check scan limit
877 if( dom->Opcode() == Op_If && // Not same opcode?
878 prev_dom->in(0) == dom ) { // One path of test does dominate?
879 if( dom == this ) return NULL; // dead loop
880 // See if this is a range check
881 Node *index2, *range2;
882 jint offset2;
883 int flip2 = dom->as_If()->is_range_check(range2, index2, offset2);
884 // See if this is a _matching_ range check, checking against
885 // the same array bounds.
886 if( flip2 == flip1 && range2 == range1 && index2 == index1 &&
887 dom->outcnt() == 2 ) {
888 // Gather expanded bounds
889 off_lo = MIN2(off_lo,offset2);
890 off_hi = MAX2(off_hi,offset2);
891 // Record top 2 range checks
892 prev_chk2 = prev_chk1;
893 prev_chk1 = prev_dom;
894 // If we match the test exactly, then the top test covers
895 // both our lower and upper bounds.
896 if( dom->in(1) == in(1) )
897 prev_chk2 = prev_chk1;
898 }
899 }
900 prev_dom = dom;
901 dom = up_one_dom( dom );
902 if( !dom ) break;
903 }
906 // Attempt to widen the dominating range check to cover some later
907 // ones. Since range checks "fail" by uncommon-trapping to the
908 // interpreter, widening a check can make us speculative enter the
909 // interpreter. If we see range-check deopt's, do not widen!
910 if (!phase->C->allow_range_check_smearing()) return NULL;
912 // Constant indices only need to check the upper bound.
913 // Non-constance indices must check both low and high.
914 if( index1 ) {
915 // Didn't find 2 prior covering checks, so cannot remove anything.
916 if( !prev_chk2 ) return NULL;
917 // 'Widen' the offsets of the 1st and 2nd covering check
918 adjust_check( prev_chk1, range1, index1, flip1, off_lo, igvn );
919 // Do not call adjust_check twice on the same projection
920 // as the first call may have transformed the BoolNode to a ConI
921 if( prev_chk1 != prev_chk2 ) {
922 adjust_check( prev_chk2, range1, index1, flip1, off_hi, igvn );
923 }
924 // Test is now covered by prior checks, dominate it out
925 prev_dom = prev_chk2;
926 } else {
927 // Didn't find prior covering check, so cannot remove anything.
928 if( !prev_chk1 ) return NULL;
929 // 'Widen' the offset of the 1st and only covering check
930 adjust_check( prev_chk1, range1, index1, flip1, off_hi, igvn );
931 // Test is now covered by prior checks, dominate it out
932 prev_dom = prev_chk1;
933 }
936 } else { // Scan for an equivalent test
938 Node *cmp;
939 int dist = 0; // Cutoff limit for search
940 int op = Opcode();
941 if( op == Op_If &&
942 (cmp=in(1)->in(1))->Opcode() == Op_CmpP ) {
943 if( cmp->in(2) != NULL && // make sure cmp is not already dead
944 cmp->in(2)->bottom_type() == TypePtr::NULL_PTR ) {
945 dist = 64; // Limit for null-pointer scans
946 } else {
947 dist = 4; // Do not bother for random pointer tests
948 }
949 } else {
950 dist = 4; // Limit for random junky scans
951 }
953 // Normal equivalent-test check.
954 if( !dom ) return NULL; // Dead loop?
956 Node* result = fold_compares(phase);
957 if (result != NULL) {
958 return result;
959 }
961 // Search up the dominator tree for an If with an identical test
962 while( dom->Opcode() != op || // Not same opcode?
963 dom->in(1) != in(1) || // Not same input 1?
964 (req() == 3 && dom->in(2) != in(2)) || // Not same input 2?
965 prev_dom->in(0) != dom ) { // One path of test does not dominate?
966 if( dist < 0 ) return NULL;
968 dist--;
969 prev_dom = dom;
970 dom = up_one_dom( dom );
971 if( !dom ) return NULL;
972 }
974 // Check that we did not follow a loop back to ourselves
975 if( this == dom )
976 return NULL;
978 if( dist > 2 ) // Add to count of NULL checks elided
979 explicit_null_checks_elided++;
981 } // End of Else scan for an equivalent test
983 // Hit! Remove this IF
984 #ifndef PRODUCT
985 if( TraceIterativeGVN ) {
986 tty->print(" Removing IfNode: "); this->dump();
987 }
988 if( VerifyOpto && !phase->allow_progress() ) {
989 // Found an equivalent dominating test,
990 // we can not guarantee reaching a fix-point for these during iterativeGVN
991 // since intervening nodes may not change.
992 return NULL;
993 }
994 #endif
996 // Replace dominated IfNode
997 dominated_by( prev_dom, igvn );
999 // Must return either the original node (now dead) or a new node
1000 // (Do not return a top here, since that would break the uniqueness of top.)
1001 return new (phase->C, 1) ConINode(TypeInt::ZERO);
1002 }
1004 //------------------------------dominated_by-----------------------------------
1005 void IfNode::dominated_by( Node *prev_dom, PhaseIterGVN *igvn ) {
1006 igvn->hash_delete(this); // Remove self to prevent spurious V-N
1007 Node *idom = in(0);
1008 // Need opcode to decide which way 'this' test goes
1009 int prev_op = prev_dom->Opcode();
1010 Node *top = igvn->C->top(); // Shortcut to top
1012 // Now walk the current IfNode's projections.
1013 // Loop ends when 'this' has no more uses.
1014 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
1015 Node *ifp = last_out(i); // Get IfTrue/IfFalse
1016 igvn->add_users_to_worklist(ifp);
1017 // Check which projection it is and set target.
1018 // Data-target is either the dominating projection of the same type
1019 // or TOP if the dominating projection is of opposite type.
1020 // Data-target will be used as the new control edge for the non-CFG
1021 // nodes like Casts and Loads.
1022 Node *data_target = (ifp->Opcode() == prev_op ) ? prev_dom : top;
1023 // Control-target is just the If's immediate dominator or TOP.
1024 Node *ctrl_target = (ifp->Opcode() == prev_op ) ? idom : top;
1026 // For each child of an IfTrue/IfFalse projection, reroute.
1027 // Loop ends when projection has no more uses.
1028 for (DUIterator_Last jmin, j = ifp->last_outs(jmin); j >= jmin; --j) {
1029 Node* s = ifp->last_out(j); // Get child of IfTrue/IfFalse
1030 igvn->hash_delete(s); // Yank from hash table before edge hacking
1031 if( !s->depends_only_on_test() ) {
1032 // Find the control input matching this def-use edge.
1033 // For Regions it may not be in slot 0.
1034 uint l;
1035 for( l = 0; s->in(l) != ifp; l++ ) { }
1036 s->set_req(l, ctrl_target);
1037 } else { // Else, for control producers,
1038 s->set_req(0, data_target); // Move child to data-target
1039 }
1040 igvn->_worklist.push(s); // Revisit collapsed Phis
1041 } // End for each child of a projection
1043 igvn->remove_dead_node(ifp);
1044 } // End for each IfTrue/IfFalse child of If
1046 // Kill the IfNode
1047 igvn->remove_dead_node(this);
1048 }
1050 //------------------------------Identity---------------------------------------
1051 // If the test is constant & we match, then we are the input Control
1052 Node *IfTrueNode::Identity( PhaseTransform *phase ) {
1053 // Can only optimize if cannot go the other way
1054 const TypeTuple *t = phase->type(in(0))->is_tuple();
1055 return ( t == TypeTuple::IFNEITHER || t == TypeTuple::IFTRUE )
1056 ? in(0)->in(0) // IfNode control
1057 : this; // no progress
1058 }
1060 //------------------------------dump_spec--------------------------------------
1061 #ifndef PRODUCT
1062 void IfNode::dump_spec(outputStream *st) const {
1063 st->print("P=%f, C=%f",_prob,_fcnt);
1064 }
1065 #endif
1067 //------------------------------idealize_test----------------------------------
1068 // Try to canonicalize tests better. Peek at the Cmp/Bool/If sequence and
1069 // come up with a canonical sequence. Bools getting 'eq', 'gt' and 'ge' forms
1070 // converted to 'ne', 'le' and 'lt' forms. IfTrue/IfFalse get swapped as
1071 // needed.
1072 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff) {
1073 assert(iff->in(0) != NULL, "If must be live");
1075 if (iff->outcnt() != 2) return NULL; // Malformed projections.
1076 Node* old_if_f = iff->proj_out(false);
1077 Node* old_if_t = iff->proj_out(true);
1079 // CountedLoopEnds want the back-control test to be TRUE, irregardless of
1080 // whether they are testing a 'gt' or 'lt' condition. The 'gt' condition
1081 // happens in count-down loops
1082 if (iff->is_CountedLoopEnd()) return NULL;
1083 if (!iff->in(1)->is_Bool()) return NULL; // Happens for partially optimized IF tests
1084 BoolNode *b = iff->in(1)->as_Bool();
1085 BoolTest bt = b->_test;
1086 // Test already in good order?
1087 if( bt.is_canonical() )
1088 return NULL;
1090 // Flip test to be canonical. Requires flipping the IfFalse/IfTrue and
1091 // cloning the IfNode.
1092 Node* new_b = phase->transform( new (phase->C, 2) BoolNode(b->in(1), bt.negate()) );
1093 if( !new_b->is_Bool() ) return NULL;
1094 b = new_b->as_Bool();
1096 PhaseIterGVN *igvn = phase->is_IterGVN();
1097 assert( igvn, "Test is not canonical in parser?" );
1099 // The IF node never really changes, but it needs to be cloned
1100 iff = new (phase->C, 2) IfNode( iff->in(0), b, 1.0-iff->_prob, iff->_fcnt);
1102 Node *prior = igvn->hash_find_insert(iff);
1103 if( prior ) {
1104 igvn->remove_dead_node(iff);
1105 iff = (IfNode*)prior;
1106 } else {
1107 // Cannot call transform on it just yet
1108 igvn->set_type_bottom(iff);
1109 }
1110 igvn->_worklist.push(iff);
1112 // Now handle projections. Cloning not required.
1113 Node* new_if_f = (Node*)(new (phase->C, 1) IfFalseNode( iff ));
1114 Node* new_if_t = (Node*)(new (phase->C, 1) IfTrueNode ( iff ));
1116 igvn->register_new_node_with_optimizer(new_if_f);
1117 igvn->register_new_node_with_optimizer(new_if_t);
1118 // Flip test, so flip trailing control
1119 igvn->replace_node(old_if_f, new_if_t);
1120 igvn->replace_node(old_if_t, new_if_f);
1122 // Progress
1123 return iff;
1124 }
1126 //------------------------------Identity---------------------------------------
1127 // If the test is constant & we match, then we are the input Control
1128 Node *IfFalseNode::Identity( PhaseTransform *phase ) {
1129 // Can only optimize if cannot go the other way
1130 const TypeTuple *t = phase->type(in(0))->is_tuple();
1131 return ( t == TypeTuple::IFNEITHER || t == TypeTuple::IFFALSE )
1132 ? in(0)->in(0) // IfNode control
1133 : this; // no progress
1134 }