1 /*
2 * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc/shared/barrierSet.hpp"
27 #include "gc/shared/c2/barrierSetC2.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "memory/resourceArea.hpp"
30 #include "oops/objArrayKlass.hpp"
31 #include "opto/addnode.hpp"
32 #include "opto/castnode.hpp"
33 #include "opto/cfgnode.hpp"
34 #include "opto/connode.hpp"
35 #include "opto/convertnode.hpp"
36 #include "opto/inlinetypenode.hpp"
37 #include "opto/loopnode.hpp"
38 #include "opto/machnode.hpp"
39 #include "opto/movenode.hpp"
40 #include "opto/narrowptrnode.hpp"
41 #include "opto/mulnode.hpp"
42 #include "opto/phaseX.hpp"
43 #include "opto/regalloc.hpp"
44 #include "opto/regmask.hpp"
45 #include "opto/runtime.hpp"
46 #include "opto/subnode.hpp"
47 #include "opto/vectornode.hpp"
48 #include "utilities/vmError.hpp"
49
50 // Portions of code courtesy of Clifford Click
51
52 // Optimization - Graph Style
53
54 //=============================================================================
55 //------------------------------Value------------------------------------------
56 // Compute the type of the RegionNode.
57 const Type* RegionNode::Value(PhaseGVN* phase) const {
58 for( uint i=1; i<req(); ++i ) { // For all paths in
59 Node *n = in(i); // Get Control source
60 if( !n ) continue; // Missing inputs are TOP
61 if( phase->type(n) == Type::CONTROL )
62 return Type::CONTROL;
63 }
64 return Type::TOP; // All paths dead? Then so are we
65 }
66
67 //------------------------------Identity---------------------------------------
68 // Check for Region being Identity.
69 Node* RegionNode::Identity(PhaseGVN* phase) {
70 // Cannot have Region be an identity, even if it has only 1 input.
71 // Phi users cannot have their Region input folded away for them,
72 // since they need to select the proper data input
73 return this;
74 }
75
76 //------------------------------merge_region-----------------------------------
77 // If a Region flows into a Region, merge into one big happy merge. This is
78 // hard to do if there is stuff that has to happen
79 static Node *merge_region(RegionNode *region, PhaseGVN *phase) {
80 if( region->Opcode() != Op_Region ) // Do not do to LoopNodes
81 return NULL;
82 Node *progress = NULL; // Progress flag
83 PhaseIterGVN *igvn = phase->is_IterGVN();
84
85 uint rreq = region->req();
86 for( uint i = 1; i < rreq; i++ ) {
87 Node *r = region->in(i);
88 if( r && r->Opcode() == Op_Region && // Found a region?
89 r->in(0) == r && // Not already collapsed?
90 r != region && // Avoid stupid situations
91 r->outcnt() == 2 ) { // Self user and 'region' user only?
92 assert(!r->as_Region()->has_phi(), "no phi users");
93 if( !progress ) { // No progress
94 if (region->has_phi()) {
95 return NULL; // Only flatten if no Phi users
96 // igvn->hash_delete( phi );
97 }
98 igvn->hash_delete( region );
99 progress = region; // Making progress
100 }
101 igvn->hash_delete( r );
102
103 // Append inputs to 'r' onto 'region'
104 for( uint j = 1; j < r->req(); j++ ) {
105 // Move an input from 'r' to 'region'
106 region->add_req(r->in(j));
107 r->set_req(j, phase->C->top());
108 // Update phis of 'region'
109 //for( uint k = 0; k < max; k++ ) {
110 // Node *phi = region->out(k);
111 // if( phi->is_Phi() ) {
112 // phi->add_req(phi->in(i));
113 // }
114 //}
115
116 rreq++; // One more input to Region
117 } // Found a region to merge into Region
118 igvn->_worklist.push(r);
119 // Clobber pointer to the now dead 'r'
120 region->set_req(i, phase->C->top());
121 }
122 }
123
124 return progress;
125 }
126
127
128
129 //--------------------------------has_phi--------------------------------------
130 // Helper function: Return any PhiNode that uses this region or NULL
131 PhiNode* RegionNode::has_phi() const {
132 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
133 Node* phi = fast_out(i);
134 if (phi->is_Phi()) { // Check for Phi users
135 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
136 return phi->as_Phi(); // this one is good enough
137 }
138 }
139
140 return NULL;
141 }
142
143
144 //-----------------------------has_unique_phi----------------------------------
145 // Helper function: Return the only PhiNode that uses this region or NULL
146 PhiNode* RegionNode::has_unique_phi() const {
147 // Check that only one use is a Phi
148 PhiNode* only_phi = NULL;
149 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
150 Node* phi = fast_out(i);
151 if (phi->is_Phi()) { // Check for Phi users
152 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
153 if (only_phi == NULL) {
154 only_phi = phi->as_Phi();
155 } else {
156 return NULL; // multiple phis
157 }
158 }
159 }
160
161 return only_phi;
162 }
163
164
165 //------------------------------check_phi_clipping-----------------------------
166 // Helper function for RegionNode's identification of FP clipping
167 // Check inputs to the Phi
168 static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) {
169 min = NULL;
170 max = NULL;
171 val = NULL;
172 min_idx = 0;
173 max_idx = 0;
174 val_idx = 0;
175 uint phi_max = phi->req();
176 if( phi_max == 4 ) {
177 for( uint j = 1; j < phi_max; ++j ) {
178 Node *n = phi->in(j);
179 int opcode = n->Opcode();
180 switch( opcode ) {
181 case Op_ConI:
182 {
183 if( min == NULL ) {
184 min = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
185 min_idx = j;
186 } else {
187 max = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
188 max_idx = j;
189 if( min->get_int() > max->get_int() ) {
190 // Swap min and max
191 ConNode *temp;
192 uint temp_idx;
193 temp = min; min = max; max = temp;
194 temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx;
195 }
196 }
197 }
198 break;
199 default:
200 {
201 val = n;
202 val_idx = j;
203 }
204 break;
205 }
206 }
207 }
208 return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) );
209 }
210
211
212 //------------------------------check_if_clipping------------------------------
213 // Helper function for RegionNode's identification of FP clipping
214 // Check that inputs to Region come from two IfNodes,
215 //
216 // If
217 // False True
218 // If |
219 // False True |
220 // | | |
221 // RegionNode_inputs
222 //
223 static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) {
224 top_if = NULL;
225 bot_if = NULL;
226
227 // Check control structure above RegionNode for (if ( if ) )
228 Node *in1 = region->in(1);
229 Node *in2 = region->in(2);
230 Node *in3 = region->in(3);
231 // Check that all inputs are projections
232 if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) {
233 Node *in10 = in1->in(0);
234 Node *in20 = in2->in(0);
235 Node *in30 = in3->in(0);
236 // Check that #1 and #2 are ifTrue and ifFalse from same If
237 if( in10 != NULL && in10->is_If() &&
238 in20 != NULL && in20->is_If() &&
239 in30 != NULL && in30->is_If() && in10 == in20 &&
240 (in1->Opcode() != in2->Opcode()) ) {
241 Node *in100 = in10->in(0);
242 Node *in1000 = (in100 != NULL && in100->is_Proj()) ? in100->in(0) : NULL;
243 // Check that control for in10 comes from other branch of IF from in3
244 if( in1000 != NULL && in1000->is_If() &&
245 in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) {
246 // Control pattern checks
247 top_if = (IfNode*)in1000;
248 bot_if = (IfNode*)in10;
249 }
250 }
251 }
252
253 return (top_if != NULL);
254 }
255
256
257 //------------------------------check_convf2i_clipping-------------------------
258 // Helper function for RegionNode's identification of FP clipping
259 // Verify that the value input to the phi comes from "ConvF2I; LShift; RShift"
260 static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) {
261 convf2i = NULL;
262
263 // Check for the RShiftNode
264 Node *rshift = phi->in(idx);
265 assert( rshift, "Previous checks ensure phi input is present");
266 if( rshift->Opcode() != Op_RShiftI ) { return false; }
267
268 // Check for the LShiftNode
269 Node *lshift = rshift->in(1);
270 assert( lshift, "Previous checks ensure phi input is present");
271 if( lshift->Opcode() != Op_LShiftI ) { return false; }
272
273 // Check for the ConvF2INode
274 Node *conv = lshift->in(1);
275 if( conv->Opcode() != Op_ConvF2I ) { return false; }
276
277 // Check that shift amounts are only to get sign bits set after F2I
278 jint max_cutoff = max->get_int();
279 jint min_cutoff = min->get_int();
280 jint left_shift = lshift->in(2)->get_int();
281 jint right_shift = rshift->in(2)->get_int();
282 jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1);
283 if( left_shift != right_shift ||
284 0 > left_shift || left_shift >= BitsPerJavaInteger ||
285 max_post_shift < max_cutoff ||
286 max_post_shift < -min_cutoff ) {
287 // Shifts are necessary but current transformation eliminates them
288 return false;
289 }
290
291 // OK to return the result of ConvF2I without shifting
292 convf2i = (ConvF2INode*)conv;
293 return true;
294 }
295
296
297 //------------------------------check_compare_clipping-------------------------
298 // Helper function for RegionNode's identification of FP clipping
299 static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) {
300 Node *i1 = iff->in(1);
301 if ( !i1->is_Bool() ) { return false; }
302 BoolNode *bool1 = i1->as_Bool();
303 if( less_than && bool1->_test._test != BoolTest::le ) { return false; }
304 else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; }
305 const Node *cmpF = bool1->in(1);
306 if( cmpF->Opcode() != Op_CmpF ) { return false; }
307 // Test that the float value being compared against
308 // is equivalent to the int value used as a limit
309 Node *nodef = cmpF->in(2);
310 if( nodef->Opcode() != Op_ConF ) { return false; }
311 jfloat conf = nodef->getf();
312 jint coni = limit->get_int();
313 if( ((int)conf) != coni ) { return false; }
314 input = cmpF->in(1);
315 return true;
316 }
317
318 //------------------------------is_unreachable_region--------------------------
319 // Check if the RegionNode is part of an unsafe loop and unreachable from root.
320 bool RegionNode::is_unreachable_region(const PhaseGVN* phase) {
321 Node* top = phase->C->top();
322 assert(req() == 2 || (req() == 3 && in(1) != NULL && in(2) == top), "sanity check arguments");
323 if (_is_unreachable_region) {
324 // Return cached result from previous evaluation which should still be valid
325 assert(is_unreachable_from_root(phase), "walk the graph again and check if its indeed unreachable");
326 return true;
327 }
328
329 // First, cut the simple case of fallthrough region when NONE of
330 // region's phis references itself directly or through a data node.
331 if (is_possible_unsafe_loop(phase)) {
332 // If we have a possible unsafe loop, check if the region node is actually unreachable from root.
333 if (is_unreachable_from_root(phase)) {
334 _is_unreachable_region = true;
335 return true;
336 }
337 }
338 return false;
339 }
340
341 bool RegionNode::is_possible_unsafe_loop(const PhaseGVN* phase) const {
342 uint max = outcnt();
343 uint i;
344 for (i = 0; i < max; i++) {
345 Node* n = raw_out(i);
346 if (n != NULL && n->is_Phi()) {
347 PhiNode* phi = n->as_Phi();
348 assert(phi->in(0) == this, "sanity check phi");
349 if (phi->outcnt() == 0) {
350 continue; // Safe case - no loops
351 }
352 if (phi->outcnt() == 1) {
353 Node* u = phi->raw_out(0);
354 // Skip if only one use is an other Phi or Call or Uncommon trap.
355 // It is safe to consider this case as fallthrough.
356 if (u != NULL && (u->is_Phi() || u->is_CFG())) {
357 continue;
358 }
359 }
360 // Check when phi references itself directly or through an other node.
361 if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe) {
362 break; // Found possible unsafe data loop.
363 }
364 }
365 }
366 if (i >= max) {
367 return false; // An unsafe case was NOT found - don't need graph walk.
368 }
369 return true;
370 }
371
372 bool RegionNode::is_unreachable_from_root(const PhaseGVN* phase) const {
373 ResourceMark rm;
374 Node_List nstack;
375 VectorSet visited;
376
377 // Mark all control nodes reachable from root outputs
378 Node* n = (Node*)phase->C->root();
379 nstack.push(n);
380 visited.set(n->_idx);
381 while (nstack.size() != 0) {
382 n = nstack.pop();
383 uint max = n->outcnt();
384 for (uint i = 0; i < max; i++) {
385 Node* m = n->raw_out(i);
386 if (m != NULL && m->is_CFG()) {
387 if (m == this) {
388 return false; // We reached the Region node - it is not dead.
389 }
390 if (!visited.test_set(m->_idx))
391 nstack.push(m);
392 }
393 }
394 }
395 return true; // The Region node is unreachable - it is dead.
396 }
397
398 #ifdef ASSERT
399 // Is this region in an infinite subgraph?
400 // (no path to root except through false NeverBranch exit)
401 bool RegionNode::is_in_infinite_subgraph() {
402 ResourceMark rm;
403 Unique_Node_List worklist;
404 worklist.push(this);
405 return RegionNode::are_all_nodes_in_infinite_subgraph(worklist);
406 }
407
408 // Are all nodes in worklist in infinite subgraph?
409 // (no path to root except through false NeverBranch exit)
410 // worklist is directly used for the traversal
411 bool RegionNode::are_all_nodes_in_infinite_subgraph(Unique_Node_List& worklist) {
412 // BFS traversal down the CFG, except through NeverBranch exits
413 for (uint i = 0; i < worklist.size(); ++i) {
414 Node* n = worklist.at(i);
415 assert(n->is_CFG(), "only traverse CFG");
416 if (n->is_Root()) {
417 // Found root -> there was an exit!
418 return false;
419 } else if (n->is_NeverBranch()) {
420 // Only follow the loop-internal projection, not the NeverBranch exit
421 ProjNode* proj = n->as_NeverBranch()->proj_out_or_null(0);
422 assert(proj != nullptr, "must find loop-internal projection of NeverBranch");
423 worklist.push(proj);
424 } else {
425 // Traverse all CFG outputs
426 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
427 Node* use = n->fast_out(i);
428 if (use->is_CFG()) {
429 worklist.push(use);
430 }
431 }
432 }
433 }
434 // No exit found for any loop -> all are infinite
435 return true;
436 }
437 #endif //ASSERT
438
439 Node* PhiNode::try_clean_mem_phi(PhaseGVN *phase) {
440 // Incremental inlining + PhaseStringOpts sometimes produce:
441 //
442 // cmpP with 1 top input
443 // |
444 // If
445 // / \
446 // IfFalse IfTrue /- Some Node
447 // \ / / /
448 // Region / /-MergeMem
449 // \---Phi
450 //
451 //
452 // It's expected by PhaseStringOpts that the Region goes away and is
453 // replaced by If's control input but because there's still a Phi,
454 // the Region stays in the graph. The top input from the cmpP is
455 // propagated forward and a subgraph that is useful goes away. The
456 // code below replaces the Phi with the MergeMem so that the Region
457 // is simplified.
458
459 if (type() == Type::MEMORY && is_diamond_phi(true)) {
460 MergeMemNode* m = NULL;
461 assert(req() == 3, "same as region");
462 Node* r = in(0);
463 for (uint i = 1; i < 3; ++i) {
464 Node *mem = in(i);
465 if (mem && mem->is_MergeMem() && r->in(i)->outcnt() == 1) {
466 // Nothing is control-dependent on path #i except the region itself.
467 m = mem->as_MergeMem();
468 uint j = 3 - i;
469 Node* other = in(j);
470 if (other && other == m->base_memory()) {
471 // m is a successor memory to other, and is not pinned inside the diamond, so push it out.
472 // This will allow the diamond to collapse completely.
473 return m;
474 }
475 }
476 }
477 }
478 return NULL;
479 }
480
481 //------------------------------Ideal------------------------------------------
482 // Return a node which is more "ideal" than the current node. Must preserve
483 // the CFG, but we can still strip out dead paths.
484 Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) {
485 if( !can_reshape && !in(0) ) return NULL; // Already degraded to a Copy
486 assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge");
487
488 // Check for RegionNode with no Phi users and both inputs come from either
489 // arm of the same IF. If found, then the control-flow split is useless.
490 bool has_phis = false;
491 if (can_reshape) { // Need DU info to check for Phi users
492 has_phis = (has_phi() != NULL); // Cache result
493 if (has_phis) {
494 PhiNode* phi = has_unique_phi();
495 if (phi != NULL) {
496 Node* m = phi->try_clean_mem_phi(phase);
497 if (m != NULL) {
498 phase->is_IterGVN()->replace_node(phi, m);
499 has_phis = false;
500 }
501 }
502 }
503
504 if (!has_phis) { // No Phi users? Nothing merging?
505 for (uint i = 1; i < req()-1; i++) {
506 Node *if1 = in(i);
507 if( !if1 ) continue;
508 Node *iff = if1->in(0);
509 if( !iff || !iff->is_If() ) continue;
510 for( uint j=i+1; j<req(); j++ ) {
511 if( in(j) && in(j)->in(0) == iff &&
512 if1->Opcode() != in(j)->Opcode() ) {
513 // Add the IF Projections to the worklist. They (and the IF itself)
514 // will be eliminated if dead.
515 phase->is_IterGVN()->add_users_to_worklist(iff);
516 set_req(i, iff->in(0));// Skip around the useless IF diamond
517 set_req(j, NULL);
518 return this; // Record progress
519 }
520 }
521 }
522 }
523 }
524
525 // Remove TOP or NULL input paths. If only 1 input path remains, this Region
526 // degrades to a copy.
527 bool add_to_worklist = true;
528 bool modified = false;
529 int cnt = 0; // Count of values merging
530 DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count
531 int del_it = 0; // The last input path we delete
532 // For all inputs...
533 for( uint i=1; i<req(); ++i ){// For all paths in
534 Node *n = in(i); // Get the input
535 if( n != NULL ) {
536 // Remove useless control copy inputs
537 if( n->is_Region() && n->as_Region()->is_copy() ) {
538 set_req(i, n->nonnull_req());
539 modified = true;
540 i--;
541 continue;
542 }
543 if( n->is_Proj() ) { // Remove useless rethrows
544 Node *call = n->in(0);
545 if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) {
546 set_req(i, call->in(0));
547 modified = true;
548 i--;
549 continue;
550 }
551 }
552 if( phase->type(n) == Type::TOP ) {
553 set_req_X(i, NULL, phase); // Ignore TOP inputs
554 modified = true;
555 i--;
556 continue;
557 }
558 cnt++; // One more value merging
559
560 } else if (can_reshape) { // Else found dead path with DU info
561 PhaseIterGVN *igvn = phase->is_IterGVN();
562 del_req(i); // Yank path from self
563 del_it = i;
564 uint max = outcnt();
565 DUIterator j;
566 bool progress = true;
567 while(progress) { // Need to establish property over all users
568 progress = false;
569 for (j = outs(); has_out(j); j++) {
570 Node *n = out(j);
571 if( n->req() != req() && n->is_Phi() ) {
572 assert( n->in(0) == this, "" );
573 igvn->hash_delete(n); // Yank from hash before hacking edges
574 n->set_req_X(i,NULL,igvn);// Correct DU info
575 n->del_req(i); // Yank path from Phis
576 if( max != outcnt() ) {
577 progress = true;
578 j = refresh_out_pos(j);
579 max = outcnt();
580 }
581 }
582 }
583 }
584 add_to_worklist = false;
585 phase->is_IterGVN()->add_users_to_worklist(this);
586 i--;
587 }
588 }
589
590 if (can_reshape && cnt == 1) {
591 // Is it dead loop?
592 // If it is LoopNopde it had 2 (+1 itself) inputs and
593 // one of them was cut. The loop is dead if it was EntryContol.
594 // Loop node may have only one input because entry path
595 // is removed in PhaseIdealLoop::Dominators().
596 assert(!this->is_Loop() || cnt_orig <= 3, "Loop node should have 3 or less inputs");
597 if ((this->is_Loop() && (del_it == LoopNode::EntryControl ||
598 (del_it == 0 && is_unreachable_region(phase)))) ||
599 (!this->is_Loop() && has_phis && is_unreachable_region(phase))) {
600 // This region and therefore all nodes on the input control path(s) are unreachable
601 // from root. To avoid incomplete removal of unreachable subgraphs, walk up the CFG
602 // and aggressively replace all nodes by top.
603 PhaseIterGVN* igvn = phase->is_IterGVN();
604 Node* top = phase->C->top();
605 ResourceMark rm;
606 Node_List nstack;
607 VectorSet visited;
608 nstack.push(this);
609 visited.set(_idx);
610 while (nstack.size() != 0) {
611 Node* n = nstack.pop();
612 for (uint i = 0; i < n->req(); ++i) {
613 Node* m = n->in(i);
614 assert(m != (Node*)phase->C->root(), "Should be unreachable from root");
615 if (m != NULL && m->is_CFG() && !visited.test_set(m->_idx)) {
616 nstack.push(m);
617 }
618 }
619 if (n->is_Region()) {
620 // Eagerly replace phis with top to avoid regionless phis.
621 n->set_req(0, NULL);
622 bool progress = true;
623 uint max = n->outcnt();
624 DUIterator j;
625 while (progress) {
626 progress = false;
627 for (j = n->outs(); n->has_out(j); j++) {
628 Node* u = n->out(j);
629 if (u->is_Phi()) {
630 igvn->replace_node(u, top);
631 if (max != n->outcnt()) {
632 progress = true;
633 j = n->refresh_out_pos(j);
634 max = n->outcnt();
635 }
636 }
637 }
638 }
639 }
640 igvn->replace_node(n, top);
641 }
642 return NULL;
643 }
644 }
645
646 if( cnt <= 1 ) { // Only 1 path in?
647 set_req(0, NULL); // Null control input for region copy
648 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is.
649 // No inputs or all inputs are NULL.
650 return NULL;
651 } else if (can_reshape) { // Optimization phase - remove the node
652 PhaseIterGVN *igvn = phase->is_IterGVN();
653 // Strip mined (inner) loop is going away, remove outer loop.
654 if (is_CountedLoop() &&
655 as_Loop()->is_strip_mined()) {
656 Node* outer_sfpt = as_CountedLoop()->outer_safepoint();
657 Node* outer_out = as_CountedLoop()->outer_loop_exit();
658 if (outer_sfpt != NULL && outer_out != NULL) {
659 Node* in = outer_sfpt->in(0);
660 igvn->replace_node(outer_out, in);
661 LoopNode* outer = as_CountedLoop()->outer_loop();
662 igvn->replace_input_of(outer, LoopNode::LoopBackControl, igvn->C->top());
663 }
664 }
665 if (is_CountedLoop()) {
666 Node* opaq = as_CountedLoop()->is_canonical_loop_entry();
667 if (opaq != NULL) {
668 // This is not a loop anymore. No need to keep the Opaque1 node on the test that guards the loop as it won't be
669 // subject to further loop opts.
670 assert(opaq->Opcode() == Op_OpaqueZeroTripGuard, "");
671 igvn->replace_node(opaq, opaq->in(1));
672 }
673 }
674 Node *parent_ctrl;
675 if( cnt == 0 ) {
676 assert( req() == 1, "no inputs expected" );
677 // During IGVN phase such region will be subsumed by TOP node
678 // so region's phis will have TOP as control node.
679 // Kill phis here to avoid it.
680 // Also set other user's input to top.
681 parent_ctrl = phase->C->top();
682 } else {
683 // The fallthrough case since we already checked dead loops above.
684 parent_ctrl = in(1);
685 assert(parent_ctrl != NULL, "Region is a copy of some non-null control");
686 assert(parent_ctrl != this, "Close dead loop");
687 }
688 if (add_to_worklist) {
689 igvn->add_users_to_worklist(this); // Check for further allowed opts
690 }
691 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
692 Node* n = last_out(i);
693 igvn->hash_delete(n); // Remove from worklist before modifying edges
694 if (n->outcnt() == 0) {
695 int uses_found = n->replace_edge(this, phase->C->top(), igvn);
696 if (uses_found > 1) { // (--i) done at the end of the loop.
697 i -= (uses_found - 1);
698 }
699 continue;
700 }
701 if( n->is_Phi() ) { // Collapse all Phis
702 // Eagerly replace phis to avoid regionless phis.
703 Node* in;
704 if( cnt == 0 ) {
705 assert( n->req() == 1, "No data inputs expected" );
706 in = parent_ctrl; // replaced by top
707 } else {
708 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
709 in = n->in(1); // replaced by unique input
710 if( n->as_Phi()->is_unsafe_data_reference(in) )
711 in = phase->C->top(); // replaced by top
712 }
713 igvn->replace_node(n, in);
714 }
715 else if( n->is_Region() ) { // Update all incoming edges
716 assert(n != this, "Must be removed from DefUse edges");
717 int uses_found = n->replace_edge(this, parent_ctrl, igvn);
718 if (uses_found > 1) { // (--i) done at the end of the loop.
719 i -= (uses_found - 1);
720 }
721 }
722 else {
723 assert(n->in(0) == this, "Expect RegionNode to be control parent");
724 n->set_req(0, parent_ctrl);
725 }
726 #ifdef ASSERT
727 for( uint k=0; k < n->req(); k++ ) {
728 assert(n->in(k) != this, "All uses of RegionNode should be gone");
729 }
730 #endif
731 }
732 // Remove the RegionNode itself from DefUse info
733 igvn->remove_dead_node(this);
734 return NULL;
735 }
736 return this; // Record progress
737 }
738
739
740 // If a Region flows into a Region, merge into one big happy merge.
741 if (can_reshape) {
742 Node *m = merge_region(this, phase);
743 if (m != NULL) return m;
744 }
745
746 // Check if this region is the root of a clipping idiom on floats
747 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
748 // Check that only one use is a Phi and that it simplifies to two constants +
749 PhiNode* phi = has_unique_phi();
750 if (phi != NULL) { // One Phi user
751 // Check inputs to the Phi
752 ConNode *min;
753 ConNode *max;
754 Node *val;
755 uint min_idx;
756 uint max_idx;
757 uint val_idx;
758 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) {
759 IfNode *top_if;
760 IfNode *bot_if;
761 if( check_if_clipping( this, bot_if, top_if ) ) {
762 // Control pattern checks, now verify compares
763 Node *top_in = NULL; // value being compared against
764 Node *bot_in = NULL;
765 if( check_compare_clipping( true, bot_if, min, bot_in ) &&
766 check_compare_clipping( false, top_if, max, top_in ) ) {
767 if( bot_in == top_in ) {
768 PhaseIterGVN *gvn = phase->is_IterGVN();
769 assert( gvn != NULL, "Only had DefUse info in IterGVN");
770 // Only remaining check is that bot_in == top_in == (Phi's val + mods)
771
772 // Check for the ConvF2INode
773 ConvF2INode *convf2i;
774 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
775 convf2i->in(1) == bot_in ) {
776 // Matched pattern, including LShiftI; RShiftI, replace with integer compares
777 // max test
778 Node *cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, min ));
779 Node *boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::lt ));
780 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt ));
781 Node *if_min= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
782 Node *ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
783 // min test
784 cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, max ));
785 boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::gt ));
786 iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
787 Node *if_max= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
788 ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
789 // update input edges to region node
790 set_req_X( min_idx, if_min, gvn );
791 set_req_X( max_idx, if_max, gvn );
792 set_req_X( val_idx, ifF, gvn );
793 // remove unnecessary 'LShiftI; RShiftI' idiom
794 gvn->hash_delete(phi);
795 phi->set_req_X( val_idx, convf2i, gvn );
796 gvn->hash_find_insert(phi);
797 // Return transformed region node
798 return this;
799 }
800 }
801 }
802 }
803 }
804 }
805 }
806
807 if (can_reshape) {
808 modified |= optimize_trichotomy(phase->is_IterGVN());
809 }
810
811 return modified ? this : NULL;
812 }
813
814 //------------------------------optimize_trichotomy--------------------------
815 // Optimize nested comparisons of the following kind:
816 //
817 // int compare(int a, int b) {
818 // return (a < b) ? -1 : (a == b) ? 0 : 1;
819 // }
820 //
821 // Shape 1:
822 // if (compare(a, b) == 1) { ... } -> if (a > b) { ... }
823 //
824 // Shape 2:
825 // if (compare(a, b) == 0) { ... } -> if (a == b) { ... }
826 //
827 // Above code leads to the following IR shapes where both Ifs compare the
828 // same value and two out of three region inputs idx1 and idx2 map to
829 // the same value and control flow.
830 //
831 // (1) If (2) If
832 // / \ / \
833 // Proj Proj Proj Proj
834 // | \ | \
835 // | If | If If
836 // | / \ | / \ / \
837 // | Proj Proj | Proj Proj ==> Proj Proj
838 // | / / \ | / | /
839 // Region / \ | / | /
840 // \ / \ | / | /
841 // Region Region Region
842 //
843 // The method returns true if 'this' is modified and false otherwise.
844 bool RegionNode::optimize_trichotomy(PhaseIterGVN* igvn) {
845 int idx1 = 1, idx2 = 2;
846 Node* region = NULL;
847 if (req() == 3 && in(1) != NULL && in(2) != NULL) {
848 // Shape 1: Check if one of the inputs is a region that merges two control
849 // inputs and has no other users (especially no Phi users).
850 region = in(1)->isa_Region() ? in(1) : in(2)->isa_Region();
851 if (region == NULL || region->outcnt() != 2 || region->req() != 3) {
852 return false; // No suitable region input found
853 }
854 } else if (req() == 4) {
855 // Shape 2: Check if two control inputs map to the same value of the unique phi
856 // user and treat these as if they would come from another region (shape (1)).
857 PhiNode* phi = has_unique_phi();
858 if (phi == NULL) {
859 return false; // No unique phi user
860 }
861 if (phi->in(idx1) != phi->in(idx2)) {
862 idx2 = 3;
863 if (phi->in(idx1) != phi->in(idx2)) {
864 idx1 = 2;
865 if (phi->in(idx1) != phi->in(idx2)) {
866 return false; // No equal phi inputs found
867 }
868 }
869 }
870 assert(phi->in(idx1) == phi->in(idx2), "must be"); // Region is merging same value
871 region = this;
872 }
873 if (region == NULL || region->in(idx1) == NULL || region->in(idx2) == NULL) {
874 return false; // Region does not merge two control inputs
875 }
876 // At this point we know that region->in(idx1) and region->(idx2) map to the same
877 // value and control flow. Now search for ifs that feed into these region inputs.
878 ProjNode* proj1 = region->in(idx1)->isa_Proj();
879 ProjNode* proj2 = region->in(idx2)->isa_Proj();
880 if (proj1 == NULL || proj1->outcnt() != 1 ||
881 proj2 == NULL || proj2->outcnt() != 1) {
882 return false; // No projection inputs with region as unique user found
883 }
884 assert(proj1 != proj2, "should be different projections");
885 IfNode* iff1 = proj1->in(0)->isa_If();
886 IfNode* iff2 = proj2->in(0)->isa_If();
887 if (iff1 == NULL || iff1->outcnt() != 2 ||
888 iff2 == NULL || iff2->outcnt() != 2) {
889 return false; // No ifs found
890 }
891 if (iff1 == iff2) {
892 igvn->add_users_to_worklist(iff1); // Make sure dead if is eliminated
893 igvn->replace_input_of(region, idx1, iff1->in(0));
894 igvn->replace_input_of(region, idx2, igvn->C->top());
895 return (region == this); // Remove useless if (both projections map to the same control/value)
896 }
897 BoolNode* bol1 = iff1->in(1)->isa_Bool();
898 BoolNode* bol2 = iff2->in(1)->isa_Bool();
899 if (bol1 == NULL || bol2 == NULL) {
900 return false; // No bool inputs found
901 }
902 Node* cmp1 = bol1->in(1);
903 Node* cmp2 = bol2->in(1);
904 bool commute = false;
905 if (!cmp1->is_Cmp() || !cmp2->is_Cmp()) {
906 return false; // No comparison
907 } else if (cmp1->Opcode() == Op_CmpF || cmp1->Opcode() == Op_CmpD ||
908 cmp2->Opcode() == Op_CmpF || cmp2->Opcode() == Op_CmpD ||
909 cmp1->Opcode() == Op_CmpP || cmp1->Opcode() == Op_CmpN ||
910 cmp2->Opcode() == Op_CmpP || cmp2->Opcode() == Op_CmpN ||
911 cmp1->is_SubTypeCheck() || cmp2->is_SubTypeCheck() ||
912 cmp1->is_FlatArrayCheck() || cmp2->is_FlatArrayCheck()) {
913 // Floats and pointers don't exactly obey trichotomy. To be on the safe side, don't transform their tests.
914 // SubTypeCheck is not commutative
915 return false;
916 } else if (cmp1 != cmp2) {
917 if (cmp1->in(1) == cmp2->in(2) &&
918 cmp1->in(2) == cmp2->in(1)) {
919 commute = true; // Same but swapped inputs, commute the test
920 } else {
921 return false; // Ifs are not comparing the same values
922 }
923 }
924 proj1 = proj1->other_if_proj();
925 proj2 = proj2->other_if_proj();
926 if (!((proj1->unique_ctrl_out_or_null() == iff2 &&
927 proj2->unique_ctrl_out_or_null() == this) ||
928 (proj2->unique_ctrl_out_or_null() == iff1 &&
929 proj1->unique_ctrl_out_or_null() == this))) {
930 return false; // Ifs are not connected through other projs
931 }
932 // Found 'iff -> proj -> iff -> proj -> this' shape where all other projs are merged
933 // through 'region' and map to the same value. Merge the boolean tests and replace
934 // the ifs by a single comparison.
935 BoolTest test1 = (proj1->_con == 1) ? bol1->_test : bol1->_test.negate();
936 BoolTest test2 = (proj2->_con == 1) ? bol2->_test : bol2->_test.negate();
937 test1 = commute ? test1.commute() : test1;
938 // After possibly commuting test1, if we can merge test1 & test2, then proj2/iff2/bol2 are the nodes to refine.
939 BoolTest::mask res = test1.merge(test2);
940 if (res == BoolTest::illegal) {
941 return false; // Unable to merge tests
942 }
943 // Adjust iff1 to always pass (only iff2 will remain)
944 igvn->replace_input_of(iff1, 1, igvn->intcon(proj1->_con));
945 if (res == BoolTest::never) {
946 // Merged test is always false, adjust iff2 to always fail
947 igvn->replace_input_of(iff2, 1, igvn->intcon(1 - proj2->_con));
948 } else {
949 // Replace bool input of iff2 with merged test
950 BoolNode* new_bol = new BoolNode(bol2->in(1), res);
951 igvn->replace_input_of(iff2, 1, igvn->transform((proj2->_con == 1) ? new_bol : new_bol->negate(igvn)));
952 if (new_bol->outcnt() == 0) {
953 igvn->remove_dead_node(new_bol);
954 }
955 }
956 return false;
957 }
958
959 const RegMask &RegionNode::out_RegMask() const {
960 return RegMask::Empty;
961 }
962
963 // Find the one non-null required input. RegionNode only
964 Node *Node::nonnull_req() const {
965 assert( is_Region(), "" );
966 for( uint i = 1; i < _cnt; i++ )
967 if( in(i) )
968 return in(i);
969 ShouldNotReachHere();
970 return NULL;
971 }
972
973
974 //=============================================================================
975 // note that these functions assume that the _adr_type field is flattened
976 uint PhiNode::hash() const {
977 const Type* at = _adr_type;
978 return TypeNode::hash() + (at ? at->hash() : 0);
979 }
980 bool PhiNode::cmp( const Node &n ) const {
981 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
982 }
983 static inline
984 const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
985 if (at == NULL || at == TypePtr::BOTTOM) return at;
986 return Compile::current()->alias_type(at)->adr_type();
987 }
988
989 //----------------------------make---------------------------------------------
990 // create a new phi with edges matching r and set (initially) to x
991 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
992 uint preds = r->req(); // Number of predecessor paths
993 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at) || (flatten_phi_adr_type(at) == TypeAryPtr::INLINES && Compile::current()->flattened_accesses_share_alias()), "flatten at");
994 PhiNode* p = new PhiNode(r, t, at);
995 for (uint j = 1; j < preds; j++) {
996 // Fill in all inputs, except those which the region does not yet have
997 if (r->in(j) != NULL)
998 p->init_req(j, x);
999 }
1000 return p;
1001 }
1002 PhiNode* PhiNode::make(Node* r, Node* x) {
1003 const Type* t = x->bottom_type();
1004 const TypePtr* at = NULL;
1005 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
1006 return make(r, x, t, at);
1007 }
1008 PhiNode* PhiNode::make_blank(Node* r, Node* x) {
1009 const Type* t = x->bottom_type();
1010 const TypePtr* at = NULL;
1011 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
1012 return new PhiNode(r, t, at);
1013 }
1014
1015
1016 //------------------------slice_memory-----------------------------------------
1017 // create a new phi with narrowed memory type
1018 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
1019 PhiNode* mem = (PhiNode*) clone();
1020 *(const TypePtr**)&mem->_adr_type = adr_type;
1021 // convert self-loops, or else we get a bad graph
1022 for (uint i = 1; i < req(); i++) {
1023 if ((const Node*)in(i) == this) mem->set_req(i, mem);
1024 }
1025 mem->verify_adr_type();
1026 return mem;
1027 }
1028
1029 //------------------------split_out_instance-----------------------------------
1030 // Split out an instance type from a bottom phi.
1031 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const {
1032 const TypeOopPtr *t_oop = at->isa_oopptr();
1033 assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr");
1034
1035 // Check if an appropriate node already exists.
1036 Node *region = in(0);
1037 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) {
1038 Node* use = region->fast_out(k);
1039 if( use->is_Phi()) {
1040 PhiNode *phi2 = use->as_Phi();
1041 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) {
1042 return phi2;
1043 }
1044 }
1045 }
1046 Compile *C = igvn->C;
1047 Arena *a = Thread::current()->resource_area();
1048 Node_Array node_map = new Node_Array(a);
1049 Node_Stack stack(a, C->live_nodes() >> 4);
1050 PhiNode *nphi = slice_memory(at);
1051 igvn->register_new_node_with_optimizer( nphi );
1052 node_map.map(_idx, nphi);
1053 stack.push((Node *)this, 1);
1054 while(!stack.is_empty()) {
1055 PhiNode *ophi = stack.node()->as_Phi();
1056 uint i = stack.index();
1057 assert(i >= 1, "not control edge");
1058 stack.pop();
1059 nphi = node_map[ophi->_idx]->as_Phi();
1060 for (; i < ophi->req(); i++) {
1061 Node *in = ophi->in(i);
1062 if (in == NULL || igvn->type(in) == Type::TOP)
1063 continue;
1064 Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, NULL, igvn);
1065 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL;
1066 if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) {
1067 opt = node_map[optphi->_idx];
1068 if (opt == NULL) {
1069 stack.push(ophi, i);
1070 nphi = optphi->slice_memory(at);
1071 igvn->register_new_node_with_optimizer( nphi );
1072 node_map.map(optphi->_idx, nphi);
1073 ophi = optphi;
1074 i = 0; // will get incremented at top of loop
1075 continue;
1076 }
1077 }
1078 nphi->set_req(i, opt);
1079 }
1080 }
1081 return nphi;
1082 }
1083
1084 //------------------------verify_adr_type--------------------------------------
1085 #ifdef ASSERT
1086 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
1087 if (visited.test_set(_idx)) return; //already visited
1088
1089 // recheck constructor invariants:
1090 verify_adr_type(false);
1091
1092 // recheck local phi/phi consistency:
1093 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
1094 "adr_type must be consistent across phi nest");
1095
1096 // walk around
1097 for (uint i = 1; i < req(); i++) {
1098 Node* n = in(i);
1099 if (n == NULL) continue;
1100 const Node* np = in(i);
1101 if (np->is_Phi()) {
1102 np->as_Phi()->verify_adr_type(visited, at);
1103 } else if (n->bottom_type() == Type::TOP
1104 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
1105 // ignore top inputs
1106 } else {
1107 const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
1108 // recheck phi/non-phi consistency at leaves:
1109 assert((nat != NULL) == (at != NULL), "");
1110 assert(nat == at || nat == TypePtr::BOTTOM,
1111 "adr_type must be consistent at leaves of phi nest");
1112 }
1113 }
1114 }
1115
1116 // Verify a whole nest of phis rooted at this one.
1117 void PhiNode::verify_adr_type(bool recursive) const {
1118 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
1119 if (Node::in_dump()) return; // muzzle asserts when printing
1120
1121 assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only");
1122 // Flat array element shouldn't get their own memory slice until flattened_accesses_share_alias is cleared.
1123 // It could be the graph has no loads/stores and flattened_accesses_share_alias is never cleared. EA could still
1124 // creates per element Phis but that wouldn't be a problem as there are no memory accesses for that array.
1125 assert(_adr_type == NULL || _adr_type->isa_aryptr() == NULL ||
1126 _adr_type->is_aryptr()->is_known_instance() ||
1127 !_adr_type->is_aryptr()->is_flat() ||
1128 !Compile::current()->flattened_accesses_share_alias() ||
1129 _adr_type == TypeAryPtr::INLINES, "flat array element shouldn't get its own slice yet");
1130
1131 if (!VerifyAliases) return; // verify thoroughly only if requested
1132
1133 assert(_adr_type == flatten_phi_adr_type(_adr_type),
1134 "Phi::adr_type must be pre-normalized");
1135
1136 if (recursive) {
1137 VectorSet visited;
1138 verify_adr_type(visited, _adr_type);
1139 }
1140 }
1141 #endif
1142
1143
1144 //------------------------------Value------------------------------------------
1145 // Compute the type of the PhiNode
1146 const Type* PhiNode::Value(PhaseGVN* phase) const {
1147 Node *r = in(0); // RegionNode
1148 if( !r ) // Copy or dead
1149 return in(1) ? phase->type(in(1)) : Type::TOP;
1150
1151 // Note: During parsing, phis are often transformed before their regions.
1152 // This means we have to use type_or_null to defend against untyped regions.
1153 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1154 return Type::TOP;
1155
1156 // Check for trip-counted loop. If so, be smarter.
1157 BaseCountedLoopNode* l = r->is_BaseCountedLoop() ? r->as_BaseCountedLoop() : NULL;
1158 if (l && ((const Node*)l->phi() == this)) { // Trip counted loop!
1159 // protect against init_trip() or limit() returning NULL
1160 if (l->can_be_counted_loop(phase)) {
1161 const Node* init = l->init_trip();
1162 const Node* limit = l->limit();
1163 const Node* stride = l->stride();
1164 if (init != NULL && limit != NULL && stride != NULL) {
1165 const TypeInteger* lo = phase->type(init)->isa_integer(l->bt());
1166 const TypeInteger* hi = phase->type(limit)->isa_integer(l->bt());
1167 const TypeInteger* stride_t = phase->type(stride)->isa_integer(l->bt());
1168 if (lo != NULL && hi != NULL && stride_t != NULL) { // Dying loops might have TOP here
1169 assert(stride_t->is_con(), "bad stride type");
1170 BoolTest::mask bt = l->loopexit()->test_trip();
1171 // If the loop exit condition is "not equal", the condition
1172 // would not trigger if init > limit (if stride > 0) or if
1173 // init < limit if (stride > 0) so we can't deduce bounds
1174 // for the iv from the exit condition.
1175 if (bt != BoolTest::ne) {
1176 jlong stride_con = stride_t->get_con_as_long(l->bt());
1177 if (stride_con < 0) { // Down-counter loop
1178 swap(lo, hi);
1179 jlong iv_range_lower_limit = lo->lo_as_long();
1180 // Prevent overflow when adding one below
1181 if (iv_range_lower_limit < max_signed_integer(l->bt())) {
1182 // The loop exit condition is: iv + stride > limit (iv is this Phi). So the loop iterates until
1183 // iv + stride <= limit
1184 // We know that: limit >= lo->lo_as_long() and stride <= -1
1185 // So when the loop exits, iv has to be at most lo->lo_as_long() + 1
1186 iv_range_lower_limit += 1; // lo is after decrement
1187 // Exact bounds for the phi can be computed when ABS(stride) greater than 1 if bounds are constant.
1188 if (lo->is_con() && hi->is_con() && hi->lo_as_long() > lo->hi_as_long() && stride_con != -1) {
1189 julong uhi = static_cast<julong>(hi->lo_as_long());
1190 julong ulo = static_cast<julong>(lo->hi_as_long());
1191 julong diff = ((uhi - ulo - 1) / (-stride_con)) * (-stride_con);
1192 julong ufirst = hi->lo_as_long() - diff;
1193 iv_range_lower_limit = reinterpret_cast<jlong &>(ufirst);
1194 assert(iv_range_lower_limit >= lo->lo_as_long() + 1, "should end up with narrower range");
1195 }
1196 }
1197 return TypeInteger::make(MIN2(iv_range_lower_limit, hi->lo_as_long()), hi->hi_as_long(), 3, l->bt())->filter_speculative(_type);
1198 } else if (stride_con >= 0) {
1199 jlong iv_range_upper_limit = hi->hi_as_long();
1200 // Prevent overflow when subtracting one below
1201 if (iv_range_upper_limit > min_signed_integer(l->bt())) {
1202 // The loop exit condition is: iv + stride < limit (iv is this Phi). So the loop iterates until
1203 // iv + stride >= limit
1204 // We know that: limit <= hi->hi_as_long() and stride >= 1
1205 // So when the loop exits, iv has to be at most hi->hi_as_long() - 1
1206 iv_range_upper_limit -= 1;
1207 // Exact bounds for the phi can be computed when ABS(stride) greater than 1 if bounds are constant.
1208 if (lo->is_con() && hi->is_con() && hi->lo_as_long() > lo->hi_as_long() && stride_con != 1) {
1209 julong uhi = static_cast<julong>(hi->lo_as_long());
1210 julong ulo = static_cast<julong>(lo->hi_as_long());
1211 julong diff = ((uhi - ulo - 1) / stride_con) * stride_con;
1212 julong ulast = lo->hi_as_long() + diff;
1213 iv_range_upper_limit = reinterpret_cast<jlong &>(ulast);
1214 assert(iv_range_upper_limit <= hi->hi_as_long() - 1, "should end up with narrower range");
1215 }
1216 }
1217 return TypeInteger::make(lo->lo_as_long(), MAX2(lo->hi_as_long(), iv_range_upper_limit), 3, l->bt())->filter_speculative(_type);
1218 }
1219 }
1220 }
1221 }
1222 } else if (l->in(LoopNode::LoopBackControl) != NULL &&
1223 in(LoopNode::EntryControl) != NULL &&
1224 phase->type(l->in(LoopNode::LoopBackControl)) == Type::TOP) {
1225 // During CCP, if we saturate the type of a counted loop's Phi
1226 // before the special code for counted loop above has a chance
1227 // to run (that is as long as the type of the backedge's control
1228 // is top), we might end up with non monotonic types
1229 return phase->type(in(LoopNode::EntryControl))->filter_speculative(_type);
1230 }
1231 }
1232
1233 // Default case: merge all inputs
1234 const Type *t = Type::TOP; // Merged type starting value
1235 for (uint i = 1; i < req(); ++i) {// For all paths in
1236 // Reachable control path?
1237 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
1238 const Type* ti = phase->type(in(i));
1239 t = t->meet_speculative(ti);
1240 }
1241 }
1242
1243 // The worst-case type (from ciTypeFlow) should be consistent with "t".
1244 // That is, we expect that "t->higher_equal(_type)" holds true.
1245 // There are various exceptions:
1246 // - Inputs which are phis might in fact be widened unnecessarily.
1247 // For example, an input might be a widened int while the phi is a short.
1248 // - Inputs might be BotPtrs but this phi is dependent on a null check,
1249 // and postCCP has removed the cast which encodes the result of the check.
1250 // - The type of this phi is an interface, and the inputs are classes.
1251 // - Value calls on inputs might produce fuzzy results.
1252 // (Occurrences of this case suggest improvements to Value methods.)
1253 //
1254 // It is not possible to see Type::BOTTOM values as phi inputs,
1255 // because the ciTypeFlow pre-pass produces verifier-quality types.
1256 const Type* ft = t->filter_speculative(_type); // Worst case type
1257
1258 #ifdef ASSERT
1259 // The following logic has been moved into TypeOopPtr::filter.
1260 const Type* jt = t->join_speculative(_type);
1261 if (jt->empty()) { // Emptied out???
1262 // Otherwise it's something stupid like non-overlapping int ranges
1263 // found on dying counted loops.
1264 assert(ft == Type::TOP, ""); // Canonical empty value
1265 }
1266
1267 else {
1268
1269 if (jt != ft && jt->base() == ft->base()) {
1270 if (jt->isa_int() &&
1271 jt->is_int()->_lo == ft->is_int()->_lo &&
1272 jt->is_int()->_hi == ft->is_int()->_hi)
1273 jt = ft;
1274 if (jt->isa_long() &&
1275 jt->is_long()->_lo == ft->is_long()->_lo &&
1276 jt->is_long()->_hi == ft->is_long()->_hi)
1277 jt = ft;
1278 }
1279 if (jt != ft) {
1280 tty->print("merge type: "); t->dump(); tty->cr();
1281 tty->print("kill type: "); _type->dump(); tty->cr();
1282 tty->print("join type: "); jt->dump(); tty->cr();
1283 tty->print("filter type: "); ft->dump(); tty->cr();
1284 }
1285 assert(jt == ft, "");
1286 }
1287 #endif //ASSERT
1288
1289 // Deal with conversion problems found in data loops.
1290 ft = phase->saturate(ft, phase->type_or_null(this), _type);
1291
1292 return ft;
1293 }
1294
1295
1296 //------------------------------is_diamond_phi---------------------------------
1297 // Does this Phi represent a simple well-shaped diamond merge? Return the
1298 // index of the true path or 0 otherwise.
1299 // If check_control_only is true, do not inspect the If node at the
1300 // top, and return -1 (not an edge number) on success.
1301 int PhiNode::is_diamond_phi(bool check_control_only) const {
1302 // Check for a 2-path merge
1303 Node *region = in(0);
1304 if( !region ) return 0;
1305 if( region->req() != 3 ) return 0;
1306 if( req() != 3 ) return 0;
1307 // Check that both paths come from the same If
1308 Node *ifp1 = region->in(1);
1309 Node *ifp2 = region->in(2);
1310 if( !ifp1 || !ifp2 ) return 0;
1311 Node *iff = ifp1->in(0);
1312 if( !iff || !iff->is_If() ) return 0;
1313 if( iff != ifp2->in(0) ) return 0;
1314 if (check_control_only) return -1;
1315 // Check for a proper bool/cmp
1316 const Node *b = iff->in(1);
1317 if( !b->is_Bool() ) return 0;
1318 const Node *cmp = b->in(1);
1319 if( !cmp->is_Cmp() ) return 0;
1320
1321 // Check for branching opposite expected
1322 if( ifp2->Opcode() == Op_IfTrue ) {
1323 assert( ifp1->Opcode() == Op_IfFalse, "" );
1324 return 2;
1325 } else {
1326 assert( ifp1->Opcode() == Op_IfTrue, "" );
1327 return 1;
1328 }
1329 }
1330
1331 //----------------------------check_cmove_id-----------------------------------
1332 // Check for CMove'ing a constant after comparing against the constant.
1333 // Happens all the time now, since if we compare equality vs a constant in
1334 // the parser, we "know" the variable is constant on one path and we force
1335 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
1336 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more
1337 // general in that we don't need constants. Since CMove's are only inserted
1338 // in very special circumstances, we do it here on generic Phi's.
1339 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
1340 assert(true_path !=0, "only diamond shape graph expected");
1341
1342 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1343 // phi->region->if_proj->ifnode->bool->cmp
1344 Node* region = in(0);
1345 Node* iff = region->in(1)->in(0);
1346 BoolNode* b = iff->in(1)->as_Bool();
1347 Node* cmp = b->in(1);
1348 Node* tval = in(true_path);
1349 Node* fval = in(3-true_path);
1350 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
1351 if (id == NULL)
1352 return NULL;
1353
1354 // Either value might be a cast that depends on a branch of 'iff'.
1355 // Since the 'id' value will float free of the diamond, either
1356 // decast or return failure.
1357 Node* ctl = id->in(0);
1358 if (ctl != NULL && ctl->in(0) == iff) {
1359 if (id->is_ConstraintCast()) {
1360 return id->in(1);
1361 } else {
1362 // Don't know how to disentangle this value.
1363 return NULL;
1364 }
1365 }
1366
1367 return id;
1368 }
1369
1370 //------------------------------Identity---------------------------------------
1371 // Check for Region being Identity.
1372 Node* PhiNode::Identity(PhaseGVN* phase) {
1373 // Check for no merging going on
1374 // (There used to be special-case code here when this->region->is_Loop.
1375 // It would check for a tributary phi on the backedge that the main phi
1376 // trivially, perhaps with a single cast. The unique_input method
1377 // does all this and more, by reducing such tributaries to 'this'.)
1378 Node* uin = unique_input(phase, false);
1379 if (uin != NULL) {
1380 return uin;
1381 }
1382
1383 int true_path = is_diamond_phi();
1384 // Delay CMove'ing identity if Ideal has not had the chance to handle unsafe cases, yet.
1385 if (true_path != 0 && !(phase->is_IterGVN() && wait_for_region_igvn(phase))) {
1386 Node* id = is_cmove_id(phase, true_path);
1387 if (id != NULL) {
1388 return id;
1389 }
1390 }
1391
1392 if (phase->is_IterGVN()) {
1393 Node* m = try_clean_mem_phi(phase);
1394 if (m != NULL) {
1395 return m;
1396 }
1397 }
1398
1399
1400 // Looking for phis with identical inputs. If we find one that has
1401 // type TypePtr::BOTTOM, replace the current phi with the bottom phi.
1402 if (phase->is_IterGVN() && type() == Type::MEMORY && adr_type() !=
1403 TypePtr::BOTTOM && !adr_type()->is_known_instance()) {
1404 uint phi_len = req();
1405 Node* phi_reg = region();
1406 for (DUIterator_Fast imax, i = phi_reg->fast_outs(imax); i < imax; i++) {
1407 Node* u = phi_reg->fast_out(i);
1408 if (u->is_Phi() && u->as_Phi()->type() == Type::MEMORY &&
1409 u->adr_type() == TypePtr::BOTTOM && u->in(0) == phi_reg &&
1410 u->req() == phi_len) {
1411 for (uint j = 1; j < phi_len; j++) {
1412 if (in(j) != u->in(j)) {
1413 u = NULL;
1414 break;
1415 }
1416 }
1417 if (u != NULL) {
1418 return u;
1419 }
1420 }
1421 }
1422 }
1423
1424 return this; // No identity
1425 }
1426
1427 //-----------------------------unique_input------------------------------------
1428 // Find the unique value, discounting top, self-loops, and casts.
1429 // Return top if there are no inputs, and self if there are multiple.
1430 Node* PhiNode::unique_input(PhaseTransform* phase, bool uncast) {
1431 // 1) One unique direct input,
1432 // or if uncast is true:
1433 // 2) some of the inputs have an intervening ConstraintCast
1434 // 3) an input is a self loop
1435 //
1436 // 1) input or 2) input or 3) input __
1437 // / \ / \ \ / \
1438 // \ / | cast phi cast
1439 // phi \ / / \ /
1440 // phi / --
1441
1442 Node* r = in(0); // RegionNode
1443 Node* input = NULL; // The unique direct input (maybe uncasted = ConstraintCasts removed)
1444
1445 for (uint i = 1, cnt = req(); i < cnt; ++i) {
1446 Node* rc = r->in(i);
1447 if (rc == NULL || phase->type(rc) == Type::TOP)
1448 continue; // ignore unreachable control path
1449 Node* n = in(i);
1450 if (n == NULL)
1451 continue;
1452 Node* un = n;
1453 if (uncast) {
1454 #ifdef ASSERT
1455 Node* m = un->uncast();
1456 #endif
1457 while (un != NULL && un->req() == 2 && un->is_ConstraintCast()) {
1458 Node* next = un->in(1);
1459 if (phase->type(next)->isa_rawptr() && phase->type(un)->isa_oopptr()) {
1460 // risk exposing raw ptr at safepoint
1461 break;
1462 }
1463 un = next;
1464 }
1465 assert(m == un || un->in(1) == m, "Only expected at CheckCastPP from allocation");
1466 }
1467 if (un == NULL || un == this || phase->type(un) == Type::TOP) {
1468 continue; // ignore if top, or in(i) and "this" are in a data cycle
1469 }
1470 // Check for a unique input (maybe uncasted)
1471 if (input == NULL) {
1472 input = un;
1473 } else if (input != un) {
1474 input = NodeSentinel; // no unique input
1475 }
1476 }
1477 if (input == NULL) {
1478 return phase->C->top(); // no inputs
1479 }
1480
1481 if (input != NodeSentinel) {
1482 return input; // one unique direct input
1483 }
1484
1485 // Nothing.
1486 return NULL;
1487 }
1488
1489 //------------------------------is_x2logic-------------------------------------
1490 // Check for simple convert-to-boolean pattern
1491 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
1492 // Convert Phi to an ConvIB.
1493 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
1494 assert(true_path !=0, "only diamond shape graph expected");
1495 // Convert the true/false index into an expected 0/1 return.
1496 // Map 2->0 and 1->1.
1497 int flipped = 2-true_path;
1498
1499 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1500 // phi->region->if_proj->ifnode->bool->cmp
1501 Node *region = phi->in(0);
1502 Node *iff = region->in(1)->in(0);
1503 BoolNode *b = (BoolNode*)iff->in(1);
1504 const CmpNode *cmp = (CmpNode*)b->in(1);
1505
1506 Node *zero = phi->in(1);
1507 Node *one = phi->in(2);
1508 const Type *tzero = phase->type( zero );
1509 const Type *tone = phase->type( one );
1510
1511 // Check for compare vs 0
1512 const Type *tcmp = phase->type(cmp->in(2));
1513 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
1514 // Allow cmp-vs-1 if the other input is bounded by 0-1
1515 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
1516 return NULL;
1517 flipped = 1-flipped; // Test is vs 1 instead of 0!
1518 }
1519
1520 // Check for setting zero/one opposite expected
1521 if( tzero == TypeInt::ZERO ) {
1522 if( tone == TypeInt::ONE ) {
1523 } else return NULL;
1524 } else if( tzero == TypeInt::ONE ) {
1525 if( tone == TypeInt::ZERO ) {
1526 flipped = 1-flipped;
1527 } else return NULL;
1528 } else return NULL;
1529
1530 // Check for boolean test backwards
1531 if( b->_test._test == BoolTest::ne ) {
1532 } else if( b->_test._test == BoolTest::eq ) {
1533 flipped = 1-flipped;
1534 } else return NULL;
1535
1536 // Build int->bool conversion
1537 Node *n = new Conv2BNode(cmp->in(1));
1538 if( flipped )
1539 n = new XorINode( phase->transform(n), phase->intcon(1) );
1540
1541 return n;
1542 }
1543
1544 //------------------------------is_cond_add------------------------------------
1545 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;"
1546 // To be profitable the control flow has to disappear; there can be no other
1547 // values merging here. We replace the test-and-branch with:
1548 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by
1549 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
1550 // Then convert Y to 0-or-Y and finally add.
1551 // This is a key transform for SpecJava _201_compress.
1552 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
1553 assert(true_path !=0, "only diamond shape graph expected");
1554
1555 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1556 // phi->region->if_proj->ifnode->bool->cmp
1557 RegionNode *region = (RegionNode*)phi->in(0);
1558 Node *iff = region->in(1)->in(0);
1559 BoolNode* b = iff->in(1)->as_Bool();
1560 const CmpNode *cmp = (CmpNode*)b->in(1);
1561
1562 // Make sure only merging this one phi here
1563 if (region->has_unique_phi() != phi) return NULL;
1564
1565 // Make sure each arm of the diamond has exactly one output, which we assume
1566 // is the region. Otherwise, the control flow won't disappear.
1567 if (region->in(1)->outcnt() != 1) return NULL;
1568 if (region->in(2)->outcnt() != 1) return NULL;
1569
1570 // Check for "(P < Q)" of type signed int
1571 if (b->_test._test != BoolTest::lt) return NULL;
1572 if (cmp->Opcode() != Op_CmpI) return NULL;
1573
1574 Node *p = cmp->in(1);
1575 Node *q = cmp->in(2);
1576 Node *n1 = phi->in( true_path);
1577 Node *n2 = phi->in(3-true_path);
1578
1579 int op = n1->Opcode();
1580 if( op != Op_AddI // Need zero as additive identity
1581 /*&&op != Op_SubI &&
1582 op != Op_AddP &&
1583 op != Op_XorI &&
1584 op != Op_OrI*/ )
1585 return NULL;
1586
1587 Node *x = n2;
1588 Node *y = NULL;
1589 if( x == n1->in(1) ) {
1590 y = n1->in(2);
1591 } else if( x == n1->in(2) ) {
1592 y = n1->in(1);
1593 } else return NULL;
1594
1595 // Not so profitable if compare and add are constants
1596 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
1597 return NULL;
1598
1599 Node *cmplt = phase->transform( new CmpLTMaskNode(p,q) );
1600 Node *j_and = phase->transform( new AndINode(cmplt,y) );
1601 return new AddINode(j_and,x);
1602 }
1603
1604 //------------------------------is_absolute------------------------------------
1605 // Check for absolute value.
1606 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
1607 assert(true_path !=0, "only diamond shape graph expected");
1608
1609 int cmp_zero_idx = 0; // Index of compare input where to look for zero
1610 int phi_x_idx = 0; // Index of phi input where to find naked x
1611
1612 // ABS ends with the merge of 2 control flow paths.
1613 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
1614 int false_path = 3 - true_path;
1615
1616 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1617 // phi->region->if_proj->ifnode->bool->cmp
1618 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
1619 Node *cmp = bol->in(1);
1620
1621 // Check bool sense
1622 if (cmp->Opcode() == Op_CmpF || cmp->Opcode() == Op_CmpD) {
1623 switch (bol->_test._test) {
1624 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break;
1625 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1626 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1627 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
1628 default: return NULL; break;
1629 }
1630 } else if (cmp->Opcode() == Op_CmpI || cmp->Opcode() == Op_CmpL) {
1631 switch (bol->_test._test) {
1632 case BoolTest::lt:
1633 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1634 case BoolTest::gt:
1635 case BoolTest::ge: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1636 default: return NULL; break;
1637 }
1638 }
1639
1640 // Test is next
1641 const Type *tzero = NULL;
1642 switch (cmp->Opcode()) {
1643 case Op_CmpI: tzero = TypeInt::ZERO; break; // Integer ABS
1644 case Op_CmpL: tzero = TypeLong::ZERO; break; // Long ABS
1645 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS
1646 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS
1647 default: return NULL;
1648 }
1649
1650 // Find zero input of compare; the other input is being abs'd
1651 Node *x = NULL;
1652 bool flip = false;
1653 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
1654 x = cmp->in(3 - cmp_zero_idx);
1655 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
1656 // The test is inverted, we should invert the result...
1657 x = cmp->in(cmp_zero_idx);
1658 flip = true;
1659 } else {
1660 return NULL;
1661 }
1662
1663 // Next get the 2 pieces being selected, one is the original value
1664 // and the other is the negated value.
1665 if( phi_root->in(phi_x_idx) != x ) return NULL;
1666
1667 // Check other phi input for subtract node
1668 Node *sub = phi_root->in(3 - phi_x_idx);
1669
1670 bool is_sub = sub->Opcode() == Op_SubF || sub->Opcode() == Op_SubD ||
1671 sub->Opcode() == Op_SubI || sub->Opcode() == Op_SubL;
1672
1673 // Allow only Sub(0,X) and fail out for all others; Neg is not OK
1674 if (!is_sub || phase->type(sub->in(1)) != tzero || sub->in(2) != x) return NULL;
1675
1676 if (tzero == TypeF::ZERO) {
1677 x = new AbsFNode(x);
1678 if (flip) {
1679 x = new SubFNode(sub->in(1), phase->transform(x));
1680 }
1681 } else if (tzero == TypeD::ZERO) {
1682 x = new AbsDNode(x);
1683 if (flip) {
1684 x = new SubDNode(sub->in(1), phase->transform(x));
1685 }
1686 } else if (tzero == TypeInt::ZERO && Matcher::match_rule_supported(Op_AbsI)) {
1687 x = new AbsINode(x);
1688 if (flip) {
1689 x = new SubINode(sub->in(1), phase->transform(x));
1690 }
1691 } else if (tzero == TypeLong::ZERO && Matcher::match_rule_supported(Op_AbsL)) {
1692 x = new AbsLNode(x);
1693 if (flip) {
1694 x = new SubLNode(sub->in(1), phase->transform(x));
1695 }
1696 } else return NULL;
1697
1698 return x;
1699 }
1700
1701 //------------------------------split_once-------------------------------------
1702 // Helper for split_flow_path
1703 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
1704 igvn->hash_delete(n); // Remove from hash before hacking edges
1705
1706 uint j = 1;
1707 for (uint i = phi->req()-1; i > 0; i--) {
1708 if (phi->in(i) == val) { // Found a path with val?
1709 // Add to NEW Region/Phi, no DU info
1710 newn->set_req( j++, n->in(i) );
1711 // Remove from OLD Region/Phi
1712 n->del_req(i);
1713 }
1714 }
1715
1716 // Register the new node but do not transform it. Cannot transform until the
1717 // entire Region/Phi conglomerate has been hacked as a single huge transform.
1718 igvn->register_new_node_with_optimizer( newn );
1719
1720 // Now I can point to the new node.
1721 n->add_req(newn);
1722 igvn->_worklist.push(n);
1723 }
1724
1725 //------------------------------split_flow_path--------------------------------
1726 // Check for merging identical values and split flow paths
1727 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) {
1728 BasicType bt = phi->type()->basic_type();
1729 if( bt == T_ILLEGAL || type2size[bt] <= 0 )
1730 return NULL; // Bail out on funny non-value stuff
1731 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a
1732 return NULL; // third unequal input to be worth doing
1733
1734 // Scan for a constant
1735 uint i;
1736 for( i = 1; i < phi->req()-1; i++ ) {
1737 Node *n = phi->in(i);
1738 if( !n ) return NULL;
1739 if( phase->type(n) == Type::TOP ) return NULL;
1740 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN || n->Opcode() == Op_ConNKlass )
1741 break;
1742 }
1743 if( i >= phi->req() ) // Only split for constants
1744 return NULL;
1745
1746 Node *val = phi->in(i); // Constant to split for
1747 uint hit = 0; // Number of times it occurs
1748 Node *r = phi->region();
1749
1750 for( ; i < phi->req(); i++ ){ // Count occurrences of constant
1751 Node *n = phi->in(i);
1752 if( !n ) return NULL;
1753 if( phase->type(n) == Type::TOP ) return NULL;
1754 if( phi->in(i) == val ) {
1755 hit++;
1756 if (PhaseIdealLoop::find_predicate(r->in(i)) != NULL) {
1757 return NULL; // don't split loop entry path
1758 }
1759 }
1760 }
1761
1762 if( hit <= 1 || // Make sure we find 2 or more
1763 hit == phi->req()-1 ) // and not ALL the same value
1764 return NULL;
1765
1766 // Now start splitting out the flow paths that merge the same value.
1767 // Split first the RegionNode.
1768 PhaseIterGVN *igvn = phase->is_IterGVN();
1769 RegionNode *newr = new RegionNode(hit+1);
1770 split_once(igvn, phi, val, r, newr);
1771
1772 // Now split all other Phis than this one
1773 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) {
1774 Node* phi2 = r->fast_out(k);
1775 if( phi2->is_Phi() && phi2->as_Phi() != phi ) {
1776 PhiNode *newphi = PhiNode::make_blank(newr, phi2);
1777 split_once(igvn, phi, val, phi2, newphi);
1778 }
1779 }
1780
1781 // Clean up this guy
1782 igvn->hash_delete(phi);
1783 for( i = phi->req()-1; i > 0; i-- ) {
1784 if( phi->in(i) == val ) {
1785 phi->del_req(i);
1786 }
1787 }
1788 phi->add_req(val);
1789
1790 return phi;
1791 }
1792
1793 //=============================================================================
1794 //------------------------------simple_data_loop_check-------------------------
1795 // Try to determining if the phi node in a simple safe/unsafe data loop.
1796 // Returns:
1797 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
1798 // Safe - safe case when the phi and it's inputs reference only safe data
1799 // nodes;
1800 // Unsafe - the phi and it's inputs reference unsafe data nodes but there
1801 // is no reference back to the phi - need a graph walk
1802 // to determine if it is in a loop;
1803 // UnsafeLoop - unsafe case when the phi references itself directly or through
1804 // unsafe data node.
1805 // Note: a safe data node is a node which could/never reference itself during
1806 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP.
1807 // I mark Phi nodes as safe node not only because they can reference itself
1808 // but also to prevent mistaking the fallthrough case inside an outer loop
1809 // as dead loop when the phi references itself through an other phi.
1810 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const {
1811 // It is unsafe loop if the phi node references itself directly.
1812 if (in == (Node*)this)
1813 return UnsafeLoop; // Unsafe loop
1814 // Unsafe loop if the phi node references itself through an unsafe data node.
1815 // Exclude cases with null inputs or data nodes which could reference
1816 // itself (safe for dead loops).
1817 if (in != NULL && !in->is_dead_loop_safe()) {
1818 // Check inputs of phi's inputs also.
1819 // It is much less expensive then full graph walk.
1820 uint cnt = in->req();
1821 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1;
1822 for (; i < cnt; ++i) {
1823 Node* m = in->in(i);
1824 if (m == (Node*)this)
1825 return UnsafeLoop; // Unsafe loop
1826 if (m != NULL && !m->is_dead_loop_safe()) {
1827 // Check the most common case (about 30% of all cases):
1828 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con).
1829 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL;
1830 if (m1 == (Node*)this)
1831 return UnsafeLoop; // Unsafe loop
1832 if (m1 != NULL && m1 == m->in(2) &&
1833 m1->is_dead_loop_safe() && m->in(3)->is_Con()) {
1834 continue; // Safe case
1835 }
1836 // The phi references an unsafe node - need full analysis.
1837 return Unsafe;
1838 }
1839 }
1840 }
1841 return Safe; // Safe case - we can optimize the phi node.
1842 }
1843
1844 //------------------------------is_unsafe_data_reference-----------------------
1845 // If phi can be reached through the data input - it is data loop.
1846 bool PhiNode::is_unsafe_data_reference(Node *in) const {
1847 assert(req() > 1, "");
1848 // First, check simple cases when phi references itself directly or
1849 // through an other node.
1850 LoopSafety safety = simple_data_loop_check(in);
1851 if (safety == UnsafeLoop)
1852 return true; // phi references itself - unsafe loop
1853 else if (safety == Safe)
1854 return false; // Safe case - phi could be replaced with the unique input.
1855
1856 // Unsafe case when we should go through data graph to determine
1857 // if the phi references itself.
1858
1859 ResourceMark rm;
1860
1861 Node_List nstack;
1862 VectorSet visited;
1863
1864 nstack.push(in); // Start with unique input.
1865 visited.set(in->_idx);
1866 while (nstack.size() != 0) {
1867 Node* n = nstack.pop();
1868 uint cnt = n->req();
1869 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1;
1870 for (; i < cnt; i++) {
1871 Node* m = n->in(i);
1872 if (m == (Node*)this) {
1873 return true; // Data loop
1874 }
1875 if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases.
1876 if (!visited.test_set(m->_idx))
1877 nstack.push(m);
1878 }
1879 }
1880 }
1881 return false; // The phi is not reachable from its inputs
1882 }
1883
1884 // Is this Phi's region or some inputs to the region enqueued for IGVN
1885 // and so could cause the region to be optimized out?
1886 bool PhiNode::wait_for_region_igvn(PhaseGVN* phase) {
1887 PhaseIterGVN* igvn = phase->is_IterGVN();
1888 Unique_Node_List& worklist = igvn->_worklist;
1889 bool delay = false;
1890 Node* r = in(0);
1891 for (uint j = 1; j < req(); j++) {
1892 Node* rc = r->in(j);
1893 Node* n = in(j);
1894 if (rc != NULL &&
1895 rc->is_Proj()) {
1896 if (worklist.member(rc)) {
1897 delay = true;
1898 } else if (rc->in(0) != NULL &&
1899 rc->in(0)->is_If()) {
1900 if (worklist.member(rc->in(0))) {
1901 delay = true;
1902 } else if (rc->in(0)->in(1) != NULL &&
1903 rc->in(0)->in(1)->is_Bool()) {
1904 if (worklist.member(rc->in(0)->in(1))) {
1905 delay = true;
1906 } else if (rc->in(0)->in(1)->in(1) != NULL &&
1907 rc->in(0)->in(1)->in(1)->is_Cmp()) {
1908 if (worklist.member(rc->in(0)->in(1)->in(1))) {
1909 delay = true;
1910 }
1911 }
1912 }
1913 }
1914 }
1915 }
1916 if (delay) {
1917 worklist.push(this);
1918 }
1919 return delay;
1920 }
1921
1922 // Push inline type input nodes (and null) down through the phi recursively (can handle data loops).
1923 InlineTypeNode* PhiNode::push_inline_types_through(PhaseGVN* phase, bool can_reshape, ciInlineKlass* vk, bool is_init) {
1924 InlineTypeNode* vt = InlineTypeNode::make_null(*phase, vk)->clone_with_phis(phase, in(0), is_init);
1925 if (can_reshape) {
1926 // Replace phi right away to be able to use the inline
1927 // type node when reaching the phi again through data loops.
1928 PhaseIterGVN* igvn = phase->is_IterGVN();
1929 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
1930 Node* u = fast_out(i);
1931 igvn->rehash_node_delayed(u);
1932 imax -= u->replace_edge(this, vt);
1933 --i;
1934 }
1935 igvn->rehash_node_delayed(this);
1936 assert(outcnt() == 0, "should be dead now");
1937 }
1938 ResourceMark rm;
1939 Node_List casts;
1940 for (uint i = 1; i < req(); ++i) {
1941 Node* n = in(i);
1942 while (n->is_ConstraintCast()) {
1943 casts.push(n);
1944 n = n->in(1);
1945 }
1946 if (phase->type(n)->is_zero_type()) {
1947 n = InlineTypeNode::make_null(*phase, vk);
1948 } else if (n->is_Phi()) {
1949 assert(can_reshape, "can only handle phis during IGVN");
1950 n = phase->transform(n->as_Phi()->push_inline_types_through(phase, can_reshape, vk, is_init));
1951 }
1952 while (casts.size() != 0) {
1953 // Push the cast(s) through the InlineTypeNode
1954 Node* cast = casts.pop()->clone();
1955 cast->set_req_X(1, n->as_InlineType()->get_oop(), phase);
1956 n = n->clone();
1957 n->as_InlineType()->set_oop(phase->transform(cast));
1958 n = phase->transform(n);
1959 }
1960 bool transform = !can_reshape && (i == (req()-1)); // Transform phis on last merge
1961 vt->merge_with(phase, n->as_InlineType(), i, transform);
1962 }
1963 return vt;
1964 }
1965
1966 //------------------------------Ideal------------------------------------------
1967 // Return a node which is more "ideal" than the current node. Must preserve
1968 // the CFG, but we can still strip out dead paths.
1969 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1970 Node *r = in(0); // RegionNode
1971 assert(r != NULL && r->is_Region(), "this phi must have a region");
1972 assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge");
1973
1974 // Note: During parsing, phis are often transformed before their regions.
1975 // This means we have to use type_or_null to defend against untyped regions.
1976 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1977 return NULL; // No change
1978
1979 Node *top = phase->C->top();
1980 bool new_phi = (outcnt() == 0); // transforming new Phi
1981 // No change for igvn if new phi is not hooked
1982 if (new_phi && can_reshape)
1983 return NULL;
1984
1985 // The are 2 situations when only one valid phi's input is left
1986 // (in addition to Region input).
1987 // One: region is not loop - replace phi with this input.
1988 // Two: region is loop - replace phi with top since this data path is dead
1989 // and we need to break the dead data loop.
1990 Node* progress = NULL; // Record if any progress made
1991 for( uint j = 1; j < req(); ++j ){ // For all paths in
1992 // Check unreachable control paths
1993 Node* rc = r->in(j);
1994 Node* n = in(j); // Get the input
1995 if (rc == NULL || phase->type(rc) == Type::TOP) {
1996 if (n != top) { // Not already top?
1997 PhaseIterGVN *igvn = phase->is_IterGVN();
1998 if (can_reshape && igvn != NULL) {
1999 igvn->_worklist.push(r);
2000 }
2001 // Nuke it down
2002 set_req_X(j, top, phase);
2003 progress = this; // Record progress
2004 }
2005 }
2006 }
2007
2008 if (can_reshape && outcnt() == 0) {
2009 // set_req() above may kill outputs if Phi is referenced
2010 // only by itself on the dead (top) control path.
2011 return top;
2012 }
2013
2014 bool uncasted = false;
2015 Node* uin = unique_input(phase, false);
2016 if (uin == NULL && can_reshape &&
2017 // If there is a chance that the region can be optimized out do
2018 // not add a cast node that we can't remove yet.
2019 !wait_for_region_igvn(phase)) {
2020 uncasted = true;
2021 uin = unique_input(phase, true);
2022 }
2023 if (uin == top) { // Simplest case: no alive inputs.
2024 if (can_reshape) // IGVN transformation
2025 return top;
2026 else
2027 return NULL; // Identity will return TOP
2028 } else if (uin != NULL) {
2029 // Only one not-NULL unique input path is left.
2030 // Determine if this input is backedge of a loop.
2031 // (Skip new phis which have no uses and dead regions).
2032 if (outcnt() > 0 && r->in(0) != NULL) {
2033 if (is_data_loop(r->as_Region(), uin, phase)) {
2034 // Break this data loop to avoid creation of a dead loop.
2035 if (can_reshape) {
2036 return top;
2037 } else {
2038 // We can't return top if we are in Parse phase - cut inputs only
2039 // let Identity to handle the case.
2040 replace_edge(uin, top, phase);
2041 return NULL;
2042 }
2043 }
2044 }
2045
2046 if (uncasted) {
2047 // Add cast nodes between the phi to be removed and its unique input.
2048 // Wait until after parsing for the type information to propagate from the casts.
2049 assert(can_reshape, "Invalid during parsing");
2050 const Type* phi_type = bottom_type();
2051 // Add casts to carry the control dependency of the Phi that is
2052 // going away
2053 Node* cast = NULL;
2054 if (phi_type->isa_ptr()) {
2055 const Type* uin_type = phase->type(uin);
2056 if (!phi_type->isa_oopptr() && !uin_type->isa_oopptr()) {
2057 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, ConstraintCastNode::StrongDependency);
2058 } else {
2059 // Use a CastPP for a cast to not null and a CheckCastPP for
2060 // a cast to a new klass (and both if both null-ness and
2061 // klass change).
2062
2063 // If the type of phi is not null but the type of uin may be
2064 // null, uin's type must be casted to not null
2065 if (phi_type->join(TypePtr::NOTNULL) == phi_type->remove_speculative() &&
2066 uin_type->join(TypePtr::NOTNULL) != uin_type->remove_speculative()) {
2067 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, TypePtr::NOTNULL, ConstraintCastNode::StrongDependency);
2068 }
2069
2070 // If the type of phi and uin, both casted to not null,
2071 // differ the klass of uin must be (check)cast'ed to match
2072 // that of phi
2073 if (phi_type->join_speculative(TypePtr::NOTNULL) != uin_type->join_speculative(TypePtr::NOTNULL)) {
2074 Node* n = uin;
2075 if (cast != NULL) {
2076 cast = phase->transform(cast);
2077 n = cast;
2078 }
2079 cast = ConstraintCastNode::make_cast(Op_CheckCastPP, r, n, phi_type, ConstraintCastNode::StrongDependency);
2080 }
2081 if (cast == NULL) {
2082 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, ConstraintCastNode::StrongDependency);
2083 }
2084 }
2085 } else {
2086 cast = ConstraintCastNode::make_cast_for_type(r, uin, phi_type, ConstraintCastNode::StrongDependency);
2087 }
2088 assert(cast != NULL, "cast should be set");
2089 cast = phase->transform(cast);
2090 // set all inputs to the new cast(s) so the Phi is removed by Identity
2091 PhaseIterGVN* igvn = phase->is_IterGVN();
2092 for (uint i = 1; i < req(); i++) {
2093 set_req_X(i, cast, igvn);
2094 }
2095 uin = cast;
2096 }
2097
2098 // One unique input.
2099 debug_only(Node* ident = Identity(phase));
2100 // The unique input must eventually be detected by the Identity call.
2101 #ifdef ASSERT
2102 if (ident != uin && !ident->is_top()) {
2103 // print this output before failing assert
2104 r->dump(3);
2105 this->dump(3);
2106 ident->dump();
2107 uin->dump();
2108 }
2109 #endif
2110 assert(ident == uin || ident->is_top(), "Identity must clean this up");
2111 return NULL;
2112 }
2113
2114 Node* opt = NULL;
2115 int true_path = is_diamond_phi();
2116 if (true_path != 0 &&
2117 // If one of the diamond's branch is in the process of dying then, the Phi's input for that branch might transform
2118 // to top. If that happens replacing the Phi with an operation that consumes the Phi's inputs will cause the Phi
2119 // to be replaced by top. To prevent that, delay the transformation until the branch has a chance to be removed.
2120 !(can_reshape && wait_for_region_igvn(phase))) {
2121 // Check for CMove'ing identity. If it would be unsafe,
2122 // handle it here. In the safe case, let Identity handle it.
2123 Node* unsafe_id = is_cmove_id(phase, true_path);
2124 if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) )
2125 opt = unsafe_id;
2126
2127 // Check for simple convert-to-boolean pattern
2128 if( opt == NULL )
2129 opt = is_x2logic(phase, this, true_path);
2130
2131 // Check for absolute value
2132 if( opt == NULL )
2133 opt = is_absolute(phase, this, true_path);
2134
2135 // Check for conditional add
2136 if( opt == NULL && can_reshape )
2137 opt = is_cond_add(phase, this, true_path);
2138
2139 // These 4 optimizations could subsume the phi:
2140 // have to check for a dead data loop creation.
2141 if( opt != NULL ) {
2142 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) {
2143 // Found dead loop.
2144 if( can_reshape )
2145 return top;
2146 // We can't return top if we are in Parse phase - cut inputs only
2147 // to stop further optimizations for this phi. Identity will return TOP.
2148 assert(req() == 3, "only diamond merge phi here");
2149 set_req(1, top);
2150 set_req(2, top);
2151 return NULL;
2152 } else {
2153 return opt;
2154 }
2155 }
2156 }
2157
2158 // Check for merging identical values and split flow paths
2159 if (can_reshape) {
2160 opt = split_flow_path(phase, this);
2161 // This optimization only modifies phi - don't need to check for dead loop.
2162 assert(opt == NULL || opt == this, "do not elide phi");
2163 if (opt != NULL) return opt;
2164 }
2165
2166 if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) {
2167 // Try to undo Phi of AddP:
2168 // (Phi (AddP base address offset) (AddP base2 address2 offset2))
2169 // becomes:
2170 // newbase := (Phi base base2)
2171 // newaddress := (Phi address address2)
2172 // newoffset := (Phi offset offset2)
2173 // (AddP newbase newaddress newoffset)
2174 //
2175 // This occurs as a result of unsuccessful split_thru_phi and
2176 // interferes with taking advantage of addressing modes. See the
2177 // clone_shift_expressions code in matcher.cpp
2178 Node* addp = in(1);
2179 Node* base = addp->in(AddPNode::Base);
2180 Node* address = addp->in(AddPNode::Address);
2181 Node* offset = addp->in(AddPNode::Offset);
2182 if (base != NULL && address != NULL && offset != NULL &&
2183 !base->is_top() && !address->is_top() && !offset->is_top()) {
2184 const Type* base_type = base->bottom_type();
2185 const Type* address_type = address->bottom_type();
2186 // make sure that all the inputs are similar to the first one,
2187 // i.e. AddP with base == address and same offset as first AddP
2188 bool doit = true;
2189 for (uint i = 2; i < req(); i++) {
2190 if (in(i) == NULL ||
2191 in(i)->Opcode() != Op_AddP ||
2192 in(i)->in(AddPNode::Base) == NULL ||
2193 in(i)->in(AddPNode::Address) == NULL ||
2194 in(i)->in(AddPNode::Offset) == NULL ||
2195 in(i)->in(AddPNode::Base)->is_top() ||
2196 in(i)->in(AddPNode::Address)->is_top() ||
2197 in(i)->in(AddPNode::Offset)->is_top()) {
2198 doit = false;
2199 break;
2200 }
2201 if (in(i)->in(AddPNode::Base) != base) {
2202 base = NULL;
2203 }
2204 if (in(i)->in(AddPNode::Offset) != offset) {
2205 offset = NULL;
2206 }
2207 if (in(i)->in(AddPNode::Address) != address) {
2208 address = NULL;
2209 }
2210 // Accumulate type for resulting Phi
2211 base_type = base_type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type());
2212 address_type = address_type->meet_speculative(in(i)->in(AddPNode::Address)->bottom_type());
2213 }
2214 if (doit && base == NULL) {
2215 // Check for neighboring AddP nodes in a tree.
2216 // If they have a base, use that it.
2217 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) {
2218 Node* u = this->fast_out(k);
2219 if (u->is_AddP()) {
2220 Node* base2 = u->in(AddPNode::Base);
2221 if (base2 != NULL && !base2->is_top()) {
2222 if (base == NULL)
2223 base = base2;
2224 else if (base != base2)
2225 { doit = false; break; }
2226 }
2227 }
2228 }
2229 }
2230 if (doit) {
2231 if (base == NULL) {
2232 base = new PhiNode(in(0), base_type, NULL);
2233 for (uint i = 1; i < req(); i++) {
2234 base->init_req(i, in(i)->in(AddPNode::Base));
2235 }
2236 phase->is_IterGVN()->register_new_node_with_optimizer(base);
2237 }
2238 if (address == NULL) {
2239 address = new PhiNode(in(0), address_type, NULL);
2240 for (uint i = 1; i < req(); i++) {
2241 address->init_req(i, in(i)->in(AddPNode::Address));
2242 }
2243 phase->is_IterGVN()->register_new_node_with_optimizer(address);
2244 }
2245 if (offset == NULL) {
2246 offset = new PhiNode(in(0), TypeX_X, NULL);
2247 for (uint i = 1; i < req(); i++) {
2248 offset->init_req(i, in(i)->in(AddPNode::Offset));
2249 }
2250 phase->is_IterGVN()->register_new_node_with_optimizer(offset);
2251 }
2252 return new AddPNode(base, address, offset);
2253 }
2254 }
2255 }
2256
2257 // Split phis through memory merges, so that the memory merges will go away.
2258 // Piggy-back this transformation on the search for a unique input....
2259 // It will be as if the merged memory is the unique value of the phi.
2260 // (Do not attempt this optimization unless parsing is complete.
2261 // It would make the parser's memory-merge logic sick.)
2262 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.)
2263 if (progress == NULL && can_reshape && type() == Type::MEMORY) {
2264 // see if this phi should be sliced
2265 uint merge_width = 0;
2266 bool saw_self = false;
2267 // TODO revisit this with JDK-8247216
2268 bool mergemem_only = true;
2269 for( uint i=1; i<req(); ++i ) {// For all paths in
2270 Node *ii = in(i);
2271 // TOP inputs should not be counted as safe inputs because if the
2272 // Phi references itself through all other inputs then splitting the
2273 // Phi through memory merges would create dead loop at later stage.
2274 if (ii == top) {
2275 return NULL; // Delay optimization until graph is cleaned.
2276 }
2277 if (ii->is_MergeMem()) {
2278 MergeMemNode* n = ii->as_MergeMem();
2279 merge_width = MAX2(merge_width, n->req());
2280 saw_self = saw_self || (n->base_memory() == this);
2281 } else {
2282 mergemem_only = false;
2283 }
2284 }
2285
2286 // This restriction is temporarily necessary to ensure termination:
2287 if (!mergemem_only && !saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0;
2288
2289 if (merge_width > Compile::AliasIdxRaw) {
2290 // found at least one non-empty MergeMem
2291 const TypePtr* at = adr_type();
2292 if (at != TypePtr::BOTTOM) {
2293 // Patch the existing phi to select an input from the merge:
2294 // Phi:AT1(...MergeMem(m0, m1, m2)...) into
2295 // Phi:AT1(...m1...)
2296 int alias_idx = phase->C->get_alias_index(at);
2297 for (uint i=1; i<req(); ++i) {
2298 Node *ii = in(i);
2299 if (ii->is_MergeMem()) {
2300 MergeMemNode* n = ii->as_MergeMem();
2301 // compress paths and change unreachable cycles to TOP
2302 // If not, we can update the input infinitely along a MergeMem cycle
2303 // Equivalent code is in MemNode::Ideal_common
2304 Node *m = phase->transform(n);
2305 if (outcnt() == 0) { // Above transform() may kill us!
2306 return top;
2307 }
2308 // If transformed to a MergeMem, get the desired slice
2309 // Otherwise the returned node represents memory for every slice
2310 Node *new_mem = (m->is_MergeMem()) ?
2311 m->as_MergeMem()->memory_at(alias_idx) : m;
2312 // Update input if it is progress over what we have now
2313 if (new_mem != ii) {
2314 set_req_X(i, new_mem, phase->is_IterGVN());
2315 progress = this;
2316 }
2317 }
2318 }
2319 } else {
2320 // We know that at least one MergeMem->base_memory() == this
2321 // (saw_self == true). If all other inputs also references this phi
2322 // (directly or through data nodes) - it is a dead loop.
2323 bool saw_safe_input = false;
2324 for (uint j = 1; j < req(); ++j) {
2325 Node* n = in(j);
2326 if (n->is_MergeMem()) {
2327 MergeMemNode* mm = n->as_MergeMem();
2328 if (mm->base_memory() == this || mm->base_memory() == mm->empty_memory()) {
2329 // Skip this input if it references back to this phi or if the memory path is dead
2330 continue;
2331 }
2332 }
2333 if (!is_unsafe_data_reference(n)) {
2334 saw_safe_input = true; // found safe input
2335 break;
2336 }
2337 }
2338 if (!saw_safe_input) {
2339 // There is a dead loop: All inputs are either dead or reference back to this phi
2340 return top;
2341 }
2342
2343 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into
2344 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...))
2345 PhaseIterGVN* igvn = phase->is_IterGVN();
2346 assert(igvn != NULL, "sanity check");
2347 Node* hook = new Node(1);
2348 PhiNode* new_base = (PhiNode*) clone();
2349 // Must eagerly register phis, since they participate in loops.
2350 igvn->register_new_node_with_optimizer(new_base);
2351 hook->add_req(new_base);
2352
2353 MergeMemNode* result = MergeMemNode::make(new_base);
2354 for (uint i = 1; i < req(); ++i) {
2355 Node *ii = in(i);
2356 if (ii->is_MergeMem()) {
2357 MergeMemNode* n = ii->as_MergeMem();
2358 if (igvn) {
2359 // TODO revisit this with JDK-8247216
2360 // Put 'n' on the worklist because it might be modified by MergeMemStream::iteration_setup
2361 igvn->_worklist.push(n);
2362 }
2363 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) {
2364 // If we have not seen this slice yet, make a phi for it.
2365 bool made_new_phi = false;
2366 if (mms.is_empty()) {
2367 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C));
2368 made_new_phi = true;
2369 igvn->register_new_node_with_optimizer(new_phi);
2370 hook->add_req(new_phi);
2371 mms.set_memory(new_phi);
2372 }
2373 Node* phi = mms.memory();
2374 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice");
2375 phi->set_req(i, mms.memory2());
2376 }
2377 }
2378 }
2379 // Distribute all self-loops.
2380 { // (Extra braces to hide mms.)
2381 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2382 Node* phi = mms.memory();
2383 for (uint i = 1; i < req(); ++i) {
2384 if (phi->in(i) == this) phi->set_req(i, phi);
2385 }
2386 }
2387 }
2388 // Already replace this phi node to cut it off from the graph to not interfere in dead loop checks during the
2389 // transformations of the new phi nodes below. Otherwise, we could wrongly conclude that there is no dead loop
2390 // because we are finding this phi node again. Also set the type of the new MergeMem node in case we are also
2391 // visiting it in the transformations below.
2392 igvn->replace_node(this, result);
2393 igvn->set_type(result, result->bottom_type());
2394
2395 // now transform the new nodes, and return the mergemem
2396 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2397 Node* phi = mms.memory();
2398 mms.set_memory(phase->transform(phi));
2399 }
2400 hook->destruct(igvn);
2401 // Replace self with the result.
2402 return result;
2403 }
2404 }
2405 //
2406 // Other optimizations on the memory chain
2407 //
2408 const TypePtr* at = adr_type();
2409 for( uint i=1; i<req(); ++i ) {// For all paths in
2410 Node *ii = in(i);
2411 Node *new_in = MemNode::optimize_memory_chain(ii, at, NULL, phase);
2412 if (ii != new_in ) {
2413 set_req(i, new_in);
2414 progress = this;
2415 }
2416 }
2417 }
2418
2419 #ifdef _LP64
2420 // Push DecodeN/DecodeNKlass down through phi.
2421 // The rest of phi graph will transform by split EncodeP node though phis up.
2422 if ((UseCompressedOops || UseCompressedClassPointers) && can_reshape && progress == NULL) {
2423 bool may_push = true;
2424 bool has_decodeN = false;
2425 bool is_decodeN = false;
2426 for (uint i=1; i<req(); ++i) {// For all paths in
2427 Node *ii = in(i);
2428 if (ii->is_DecodeNarrowPtr() && ii->bottom_type() == bottom_type()) {
2429 // Do optimization if a non dead path exist.
2430 if (ii->in(1)->bottom_type() != Type::TOP) {
2431 has_decodeN = true;
2432 is_decodeN = ii->is_DecodeN();
2433 }
2434 } else if (!ii->is_Phi()) {
2435 may_push = false;
2436 }
2437 }
2438
2439 if (has_decodeN && may_push) {
2440 PhaseIterGVN *igvn = phase->is_IterGVN();
2441 // Make narrow type for new phi.
2442 const Type* narrow_t;
2443 if (is_decodeN) {
2444 narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr());
2445 } else {
2446 narrow_t = TypeNarrowKlass::make(this->bottom_type()->is_ptr());
2447 }
2448 PhiNode* new_phi = new PhiNode(r, narrow_t);
2449 uint orig_cnt = req();
2450 for (uint i=1; i<req(); ++i) {// For all paths in
2451 Node *ii = in(i);
2452 Node* new_ii = NULL;
2453 if (ii->is_DecodeNarrowPtr()) {
2454 assert(ii->bottom_type() == bottom_type(), "sanity");
2455 new_ii = ii->in(1);
2456 } else {
2457 assert(ii->is_Phi(), "sanity");
2458 if (ii->as_Phi() == this) {
2459 new_ii = new_phi;
2460 } else {
2461 if (is_decodeN) {
2462 new_ii = new EncodePNode(ii, narrow_t);
2463 } else {
2464 new_ii = new EncodePKlassNode(ii, narrow_t);
2465 }
2466 igvn->register_new_node_with_optimizer(new_ii);
2467 }
2468 }
2469 new_phi->set_req(i, new_ii);
2470 }
2471 igvn->register_new_node_with_optimizer(new_phi, this);
2472 if (is_decodeN) {
2473 progress = new DecodeNNode(new_phi, bottom_type());
2474 } else {
2475 progress = new DecodeNKlassNode(new_phi, bottom_type());
2476 }
2477 }
2478 }
2479 #endif
2480
2481 // Check recursively if inputs are either an inline type, constant null
2482 // or another Phi (including self references through data loops). If so,
2483 // push the inline types down through the phis to enable folding of loads.
2484 if (EnableValhalla && _type->isa_ptr() && req() > 2) {
2485 ResourceMark rm;
2486 Unique_Node_List worklist;
2487 worklist.push(this);
2488 bool can_optimize = true;
2489 ciInlineKlass* vk = NULL;
2490 // true if all IsInit inputs of all InlineType* nodes are true
2491 bool is_init = true;
2492 Node_List casts;
2493
2494 // TODO 8302217 We need to prevent endless pushing through
2495 bool only_phi = (outcnt() != 0);
2496 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
2497 Node* n = fast_out(i);
2498 if (n->is_InlineType() && n->in(1) == this) {
2499 can_optimize = false;
2500 break;
2501 }
2502 if (!n->is_Phi()) {
2503 only_phi = false;
2504 }
2505 }
2506 if (only_phi) {
2507 can_optimize = false;
2508 }
2509 for (uint next = 0; next < worklist.size() && can_optimize; next++) {
2510 Node* phi = worklist.at(next);
2511 for (uint i = 1; i < phi->req() && can_optimize; i++) {
2512 Node* n = phi->in(i);
2513 if (n == NULL) {
2514 can_optimize = false;
2515 break;
2516 }
2517 while (n->is_ConstraintCast()) {
2518 if (n->in(0) != NULL && n->in(0)->is_top()) {
2519 // Will die, don't optimize
2520 can_optimize = false;
2521 break;
2522 }
2523 casts.push(n);
2524 n = n->in(1);
2525 }
2526 const Type* t = phase->type(n);
2527 if (n->is_InlineType() && (vk == NULL || vk == t->inline_klass())) {
2528 vk = (vk == NULL) ? t->inline_klass() : vk;
2529 if (phase->find_int_con(n->as_InlineType()->get_is_init(), 0) != 1) {
2530 is_init = false;
2531 }
2532 } else if (n->is_Phi() && can_reshape && n->bottom_type()->isa_ptr()) {
2533 worklist.push(n);
2534 } else if (t->is_zero_type()) {
2535 is_init = false;
2536 } else {
2537 can_optimize = false;
2538 }
2539 }
2540 }
2541 // Check if cast nodes can be pushed through
2542 const Type* t = Type::get_const_type(vk);
2543 while (casts.size() != 0 && can_optimize && t != NULL) {
2544 Node* cast = casts.pop();
2545 if (t->filter(cast->bottom_type()) == Type::TOP) {
2546 can_optimize = false;
2547 }
2548 }
2549 if (can_optimize && vk != NULL) {
2550 // TODO 8302217
2551 // assert(!_type->isa_ptr() || _type->maybe_null() || is_init, "Phi not null but a possible null was seen");
2552 return push_inline_types_through(phase, can_reshape, vk, is_init);
2553 }
2554 }
2555
2556 // Phi (VB ... VB) => VB (Phi ...) (Phi ...)
2557 if (EnableVectorReboxing && can_reshape && progress == NULL && type()->isa_oopptr()) {
2558 progress = merge_through_phi(this, phase->is_IterGVN());
2559 }
2560
2561 return progress; // Return any progress
2562 }
2563
2564 Node* PhiNode::clone_through_phi(Node* root_phi, const Type* t, uint c, PhaseIterGVN* igvn) {
2565 Node_Stack stack(1);
2566 VectorSet visited;
2567 Node_List node_map;
2568
2569 stack.push(root_phi, 1); // ignore control
2570 visited.set(root_phi->_idx);
2571
2572 Node* new_phi = new PhiNode(root_phi->in(0), t);
2573 node_map.map(root_phi->_idx, new_phi);
2574
2575 while (stack.is_nonempty()) {
2576 Node* n = stack.node();
2577 uint idx = stack.index();
2578 assert(n->is_Phi(), "not a phi");
2579 if (idx < n->req()) {
2580 stack.set_index(idx + 1);
2581 Node* def = n->in(idx);
2582 if (def == NULL) {
2583 continue; // ignore dead path
2584 } else if (def->is_Phi()) { // inner node
2585 Node* new_phi = node_map[n->_idx];
2586 if (!visited.test_set(def->_idx)) { // not visited yet
2587 node_map.map(def->_idx, new PhiNode(def->in(0), t));
2588 stack.push(def, 1); // ignore control
2589 }
2590 Node* new_in = node_map[def->_idx];
2591 new_phi->set_req(idx, new_in);
2592 } else if (def->Opcode() == Op_VectorBox) { // leaf
2593 assert(n->is_Phi(), "not a phi");
2594 Node* new_phi = node_map[n->_idx];
2595 new_phi->set_req(idx, def->in(c));
2596 } else {
2597 assert(false, "not optimizeable");
2598 return NULL;
2599 }
2600 } else {
2601 Node* new_phi = node_map[n->_idx];
2602 igvn->register_new_node_with_optimizer(new_phi, n);
2603 stack.pop();
2604 }
2605 }
2606 return new_phi;
2607 }
2608
2609 Node* PhiNode::merge_through_phi(Node* root_phi, PhaseIterGVN* igvn) {
2610 Node_Stack stack(1);
2611 VectorSet visited;
2612
2613 stack.push(root_phi, 1); // ignore control
2614 visited.set(root_phi->_idx);
2615
2616 VectorBoxNode* cached_vbox = NULL;
2617 while (stack.is_nonempty()) {
2618 Node* n = stack.node();
2619 uint idx = stack.index();
2620 if (idx < n->req()) {
2621 stack.set_index(idx + 1);
2622 Node* in = n->in(idx);
2623 if (in == NULL) {
2624 continue; // ignore dead path
2625 } else if (in->isa_Phi()) {
2626 if (!visited.test_set(in->_idx)) {
2627 stack.push(in, 1); // ignore control
2628 }
2629 } else if (in->Opcode() == Op_VectorBox) {
2630 VectorBoxNode* vbox = static_cast<VectorBoxNode*>(in);
2631 if (cached_vbox == NULL) {
2632 cached_vbox = vbox;
2633 } else if (vbox->vec_type() != cached_vbox->vec_type()) {
2634 // TODO: vector type mismatch can be handled with additional reinterpret casts
2635 assert(Type::cmp(vbox->vec_type(), cached_vbox->vec_type()) != 0, "inconsistent");
2636 return NULL; // not optimizable: vector type mismatch
2637 } else if (vbox->box_type() != cached_vbox->box_type()) {
2638 assert(Type::cmp(vbox->box_type(), cached_vbox->box_type()) != 0, "inconsistent");
2639 return NULL; // not optimizable: box type mismatch
2640 }
2641 } else {
2642 return NULL; // not optimizable: neither Phi nor VectorBox
2643 }
2644 } else {
2645 stack.pop();
2646 }
2647 }
2648
2649 assert(cached_vbox != NULL, "sanity");
2650 const TypeInstPtr* btype = cached_vbox->box_type();
2651 const TypeVect* vtype = cached_vbox->vec_type();
2652 Node* new_vbox_phi = clone_through_phi(root_phi, btype, VectorBoxNode::Box, igvn);
2653 Node* new_vect_phi = clone_through_phi(root_phi, vtype, VectorBoxNode::Value, igvn);
2654 return new VectorBoxNode(igvn->C, new_vbox_phi, new_vect_phi, btype, vtype);
2655 }
2656
2657 bool PhiNode::is_data_loop(RegionNode* r, Node* uin, const PhaseGVN* phase) {
2658 // First, take the short cut when we know it is a loop and the EntryControl data path is dead.
2659 // The loop node may only have one input because the entry path was removed in PhaseIdealLoop::Dominators().
2660 // Then, check if there is a data loop when the phi references itself directly or through other data nodes.
2661 assert(!r->is_Loop() || r->req() <= 3, "Loop node should have 3 or less inputs");
2662 const bool is_loop = (r->is_Loop() && r->req() == 3);
2663 const Node* top = phase->C->top();
2664 if (is_loop) {
2665 return !uin->eqv_uncast(in(LoopNode::EntryControl));
2666 } else {
2667 // We have a data loop either with an unsafe data reference or if a region is unreachable.
2668 return is_unsafe_data_reference(uin)
2669 || (r->req() == 3 && (r->in(1) != top && r->in(2) == top && r->is_unreachable_region(phase)));
2670 }
2671 }
2672
2673 //------------------------------is_tripcount-----------------------------------
2674 bool PhiNode::is_tripcount(BasicType bt) const {
2675 return (in(0) != NULL && in(0)->is_BaseCountedLoop() &&
2676 in(0)->as_BaseCountedLoop()->bt() == bt &&
2677 in(0)->as_BaseCountedLoop()->phi() == this);
2678 }
2679
2680 //------------------------------out_RegMask------------------------------------
2681 const RegMask &PhiNode::in_RegMask(uint i) const {
2682 return i ? out_RegMask() : RegMask::Empty;
2683 }
2684
2685 const RegMask &PhiNode::out_RegMask() const {
2686 uint ideal_reg = _type->ideal_reg();
2687 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
2688 if( ideal_reg == 0 ) return RegMask::Empty;
2689 assert(ideal_reg != Op_RegFlags, "flags register is not spillable");
2690 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
2691 }
2692
2693 #ifndef PRODUCT
2694 void PhiNode::dump_spec(outputStream *st) const {
2695 TypeNode::dump_spec(st);
2696 if (is_tripcount(T_INT) || is_tripcount(T_LONG)) {
2697 st->print(" #tripcount");
2698 }
2699 }
2700 #endif
2701
2702
2703 //=============================================================================
2704 const Type* GotoNode::Value(PhaseGVN* phase) const {
2705 // If the input is reachable, then we are executed.
2706 // If the input is not reachable, then we are not executed.
2707 return phase->type(in(0));
2708 }
2709
2710 Node* GotoNode::Identity(PhaseGVN* phase) {
2711 return in(0); // Simple copy of incoming control
2712 }
2713
2714 const RegMask &GotoNode::out_RegMask() const {
2715 return RegMask::Empty;
2716 }
2717
2718 //=============================================================================
2719 const RegMask &JumpNode::out_RegMask() const {
2720 return RegMask::Empty;
2721 }
2722
2723 //=============================================================================
2724 const RegMask &JProjNode::out_RegMask() const {
2725 return RegMask::Empty;
2726 }
2727
2728 //=============================================================================
2729 const RegMask &CProjNode::out_RegMask() const {
2730 return RegMask::Empty;
2731 }
2732
2733
2734
2735 //=============================================================================
2736
2737 uint PCTableNode::hash() const { return Node::hash() + _size; }
2738 bool PCTableNode::cmp( const Node &n ) const
2739 { return _size == ((PCTableNode&)n)._size; }
2740
2741 const Type *PCTableNode::bottom_type() const {
2742 const Type** f = TypeTuple::fields(_size);
2743 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2744 return TypeTuple::make(_size, f);
2745 }
2746
2747 //------------------------------Value------------------------------------------
2748 // Compute the type of the PCTableNode. If reachable it is a tuple of
2749 // Control, otherwise the table targets are not reachable
2750 const Type* PCTableNode::Value(PhaseGVN* phase) const {
2751 if( phase->type(in(0)) == Type::CONTROL )
2752 return bottom_type();
2753 return Type::TOP; // All paths dead? Then so are we
2754 }
2755
2756 //------------------------------Ideal------------------------------------------
2757 // Return a node which is more "ideal" than the current node. Strip out
2758 // control copies
2759 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2760 return remove_dead_region(phase, can_reshape) ? this : NULL;
2761 }
2762
2763 //=============================================================================
2764 uint JumpProjNode::hash() const {
2765 return Node::hash() + _dest_bci;
2766 }
2767
2768 bool JumpProjNode::cmp( const Node &n ) const {
2769 return ProjNode::cmp(n) &&
2770 _dest_bci == ((JumpProjNode&)n)._dest_bci;
2771 }
2772
2773 #ifndef PRODUCT
2774 void JumpProjNode::dump_spec(outputStream *st) const {
2775 ProjNode::dump_spec(st);
2776 st->print("@bci %d ",_dest_bci);
2777 }
2778
2779 void JumpProjNode::dump_compact_spec(outputStream *st) const {
2780 ProjNode::dump_compact_spec(st);
2781 st->print("(%d)%d@%d", _switch_val, _proj_no, _dest_bci);
2782 }
2783 #endif
2784
2785 //=============================================================================
2786 //------------------------------Value------------------------------------------
2787 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot
2788 // have the default "fall_through_index" path.
2789 const Type* CatchNode::Value(PhaseGVN* phase) const {
2790 // Unreachable? Then so are all paths from here.
2791 if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
2792 // First assume all paths are reachable
2793 const Type** f = TypeTuple::fields(_size);
2794 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2795 // Identify cases that will always throw an exception
2796 // () rethrow call
2797 // () virtual or interface call with NULL receiver
2798 // () call is a check cast with incompatible arguments
2799 if( in(1)->is_Proj() ) {
2800 Node *i10 = in(1)->in(0);
2801 if( i10->is_Call() ) {
2802 CallNode *call = i10->as_Call();
2803 // Rethrows always throw exceptions, never return
2804 if (call->entry_point() == OptoRuntime::rethrow_stub()) {
2805 f[CatchProjNode::fall_through_index] = Type::TOP;
2806 } else if (call->is_AllocateArray()) {
2807 Node* klass_node = call->in(AllocateNode::KlassNode);
2808 Node* length = call->in(AllocateNode::ALength);
2809 const Type* length_type = phase->type(length);
2810 const Type* klass_type = phase->type(klass_node);
2811 Node* valid_length_test = call->in(AllocateNode::ValidLengthTest);
2812 const Type* valid_length_test_t = phase->type(valid_length_test);
2813 if (length_type == Type::TOP || klass_type == Type::TOP || valid_length_test_t == Type::TOP ||
2814 valid_length_test_t->is_int()->is_con(0)) {
2815 f[CatchProjNode::fall_through_index] = Type::TOP;
2816 }
2817 } else if( call->req() > TypeFunc::Parms ) {
2818 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) );
2819 // Check for null receiver to virtual or interface calls
2820 if( call->is_CallDynamicJava() &&
2821 arg0->higher_equal(TypePtr::NULL_PTR) ) {
2822 f[CatchProjNode::fall_through_index] = Type::TOP;
2823 }
2824 } // End of if not a runtime stub
2825 } // End of if have call above me
2826 } // End of slot 1 is not a projection
2827 return TypeTuple::make(_size, f);
2828 }
2829
2830 //=============================================================================
2831 uint CatchProjNode::hash() const {
2832 return Node::hash() + _handler_bci;
2833 }
2834
2835
2836 bool CatchProjNode::cmp( const Node &n ) const {
2837 return ProjNode::cmp(n) &&
2838 _handler_bci == ((CatchProjNode&)n)._handler_bci;
2839 }
2840
2841
2842 //------------------------------Identity---------------------------------------
2843 // If only 1 target is possible, choose it if it is the main control
2844 Node* CatchProjNode::Identity(PhaseGVN* phase) {
2845 // If my value is control and no other value is, then treat as ID
2846 const TypeTuple *t = phase->type(in(0))->is_tuple();
2847 if (t->field_at(_con) != Type::CONTROL) return this;
2848 // If we remove the last CatchProj and elide the Catch/CatchProj, then we
2849 // also remove any exception table entry. Thus we must know the call
2850 // feeding the Catch will not really throw an exception. This is ok for
2851 // the main fall-thru control (happens when we know a call can never throw
2852 // an exception) or for "rethrow", because a further optimization will
2853 // yank the rethrow (happens when we inline a function that can throw an
2854 // exception and the caller has no handler). Not legal, e.g., for passing
2855 // a NULL receiver to a v-call, or passing bad types to a slow-check-cast.
2856 // These cases MUST throw an exception via the runtime system, so the VM
2857 // will be looking for a table entry.
2858 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode
2859 CallNode *call;
2860 if (_con != TypeFunc::Control && // Bail out if not the main control.
2861 !(proj->is_Proj() && // AND NOT a rethrow
2862 proj->in(0)->is_Call() &&
2863 (call = proj->in(0)->as_Call()) &&
2864 call->entry_point() == OptoRuntime::rethrow_stub()))
2865 return this;
2866
2867 // Search for any other path being control
2868 for (uint i = 0; i < t->cnt(); i++) {
2869 if (i != _con && t->field_at(i) == Type::CONTROL)
2870 return this;
2871 }
2872 // Only my path is possible; I am identity on control to the jump
2873 return in(0)->in(0);
2874 }
2875
2876
2877 #ifndef PRODUCT
2878 void CatchProjNode::dump_spec(outputStream *st) const {
2879 ProjNode::dump_spec(st);
2880 st->print("@bci %d ",_handler_bci);
2881 }
2882 #endif
2883
2884 //=============================================================================
2885 //------------------------------Identity---------------------------------------
2886 // Check for CreateEx being Identity.
2887 Node* CreateExNode::Identity(PhaseGVN* phase) {
2888 if( phase->type(in(1)) == Type::TOP ) return in(1);
2889 if( phase->type(in(0)) == Type::TOP ) return in(0);
2890 // We only come from CatchProj, unless the CatchProj goes away.
2891 // If the CatchProj is optimized away, then we just carry the
2892 // exception oop through.
2893
2894 // CheckCastPPNode::Ideal() for inline types reuses the exception
2895 // paths of a call to perform an allocation: we can see a Phi here.
2896 if (in(1)->is_Phi()) {
2897 return this;
2898 }
2899 CallNode *call = in(1)->in(0)->as_Call();
2900
2901 return (in(0)->is_CatchProj() && in(0)->in(0)->is_Catch() &&
2902 in(0)->in(0)->in(1) == in(1)) ? this : call->in(TypeFunc::Parms);
2903 }
2904
2905 //=============================================================================
2906 //------------------------------Value------------------------------------------
2907 // Check for being unreachable.
2908 const Type* NeverBranchNode::Value(PhaseGVN* phase) const {
2909 if (!in(0) || in(0)->is_top()) return Type::TOP;
2910 return bottom_type();
2911 }
2912
2913 //------------------------------Ideal------------------------------------------
2914 // Check for no longer being part of a loop
2915 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2916 if (can_reshape && !in(0)->is_Region()) {
2917 // Dead code elimination can sometimes delete this projection so
2918 // if it's not there, there's nothing to do.
2919 Node* fallthru = proj_out_or_null(0);
2920 if (fallthru != NULL) {
2921 phase->is_IterGVN()->replace_node(fallthru, in(0));
2922 }
2923 return phase->C->top();
2924 }
2925 return NULL;
2926 }
2927
2928 #ifndef PRODUCT
2929 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const {
2930 st->print("%s", Name());
2931 }
2932 #endif
2933
2934 #ifndef PRODUCT
2935 void BlackholeNode::format(PhaseRegAlloc* ra, outputStream* st) const {
2936 st->print("blackhole ");
2937 bool first = true;
2938 for (uint i = 0; i < req(); i++) {
2939 Node* n = in(i);
2940 if (n != NULL && OptoReg::is_valid(ra->get_reg_first(n))) {
2941 if (first) {
2942 first = false;
2943 } else {
2944 st->print(", ");
2945 }
2946 char buf[128];
2947 ra->dump_register(n, buf);
2948 st->print("%s", buf);
2949 }
2950 }
2951 st->cr();
2952 }
2953 #endif
2954