1 /*
2 * Copyright (c) 1997, 2021, 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.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
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/regmask.hpp"
44 #include "opto/runtime.hpp"
45 #include "opto/subnode.hpp"
46 #include "opto/vectornode.hpp"
47 #include "utilities/vmError.hpp"
48
49 // Portions of code courtesy of Clifford Click
50
51 // Optimization - Graph Style
52
53 //=============================================================================
54 //------------------------------Value------------------------------------------
55 // Compute the type of the RegionNode.
56 const Type* RegionNode::Value(PhaseGVN* phase) const {
57 for( uint i=1; i<req(); ++i ) { // For all paths in
58 Node *n = in(i); // Get Control source
59 if( !n ) continue; // Missing inputs are TOP
60 if( phase->type(n) == Type::CONTROL )
61 return Type::CONTROL;
62 }
63 return Type::TOP; // All paths dead? Then so are we
64 }
65
66 //------------------------------Identity---------------------------------------
67 // Check for Region being Identity.
68 Node* RegionNode::Identity(PhaseGVN* phase) {
69 // Cannot have Region be an identity, even if it has only 1 input.
70 // Phi users cannot have their Region input folded away for them,
71 // since they need to select the proper data input
72 return this;
73 }
74
75 //------------------------------merge_region-----------------------------------
76 // If a Region flows into a Region, merge into one big happy merge. This is
77 // hard to do if there is stuff that has to happen
78 static Node *merge_region(RegionNode *region, PhaseGVN *phase) {
79 if( region->Opcode() != Op_Region ) // Do not do to LoopNodes
80 return NULL;
81 Node *progress = NULL; // Progress flag
82 PhaseIterGVN *igvn = phase->is_IterGVN();
83
84 uint rreq = region->req();
85 for( uint i = 1; i < rreq; i++ ) {
86 Node *r = region->in(i);
87 if( r && r->Opcode() == Op_Region && // Found a region?
88 r->in(0) == r && // Not already collapsed?
89 r != region && // Avoid stupid situations
90 r->outcnt() == 2 ) { // Self user and 'region' user only?
91 assert(!r->as_Region()->has_phi(), "no phi users");
92 if( !progress ) { // No progress
93 if (region->has_phi()) {
94 return NULL; // Only flatten if no Phi users
95 // igvn->hash_delete( phi );
96 }
97 igvn->hash_delete( region );
98 progress = region; // Making progress
99 }
100 igvn->hash_delete( r );
101
102 // Append inputs to 'r' onto 'region'
103 for( uint j = 1; j < r->req(); j++ ) {
104 // Move an input from 'r' to 'region'
105 region->add_req(r->in(j));
106 r->set_req(j, phase->C->top());
107 // Update phis of 'region'
108 //for( uint k = 0; k < max; k++ ) {
109 // Node *phi = region->out(k);
110 // if( phi->is_Phi() ) {
111 // phi->add_req(phi->in(i));
112 // }
113 //}
114
115 rreq++; // One more input to Region
116 } // Found a region to merge into Region
117 igvn->_worklist.push(r);
118 // Clobber pointer to the now dead 'r'
119 region->set_req(i, phase->C->top());
120 }
121 }
122
123 return progress;
124 }
125
126
127
128 //--------------------------------has_phi--------------------------------------
129 // Helper function: Return any PhiNode that uses this region or NULL
130 PhiNode* RegionNode::has_phi() const {
131 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
132 Node* phi = fast_out(i);
133 if (phi->is_Phi()) { // Check for Phi users
134 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
135 return phi->as_Phi(); // this one is good enough
136 }
137 }
138
139 return NULL;
140 }
141
142
143 //-----------------------------has_unique_phi----------------------------------
144 // Helper function: Return the only PhiNode that uses this region or NULL
145 PhiNode* RegionNode::has_unique_phi() const {
146 // Check that only one use is a Phi
147 PhiNode* only_phi = NULL;
148 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
149 Node* phi = fast_out(i);
150 if (phi->is_Phi()) { // Check for Phi users
151 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
152 if (only_phi == NULL) {
153 only_phi = phi->as_Phi();
154 } else {
155 return NULL; // multiple phis
156 }
157 }
158 }
159
160 return only_phi;
161 }
162
163
164 //------------------------------check_phi_clipping-----------------------------
165 // Helper function for RegionNode's identification of FP clipping
166 // Check inputs to the Phi
167 static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) {
168 min = NULL;
169 max = NULL;
170 val = NULL;
171 min_idx = 0;
172 max_idx = 0;
173 val_idx = 0;
174 uint phi_max = phi->req();
175 if( phi_max == 4 ) {
176 for( uint j = 1; j < phi_max; ++j ) {
177 Node *n = phi->in(j);
178 int opcode = n->Opcode();
179 switch( opcode ) {
180 case Op_ConI:
181 {
182 if( min == NULL ) {
183 min = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
184 min_idx = j;
185 } else {
186 max = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
187 max_idx = j;
188 if( min->get_int() > max->get_int() ) {
189 // Swap min and max
190 ConNode *temp;
191 uint temp_idx;
192 temp = min; min = max; max = temp;
193 temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx;
194 }
195 }
196 }
197 break;
198 default:
199 {
200 val = n;
201 val_idx = j;
202 }
203 break;
204 }
205 }
206 }
207 return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) );
208 }
209
210
211 //------------------------------check_if_clipping------------------------------
212 // Helper function for RegionNode's identification of FP clipping
213 // Check that inputs to Region come from two IfNodes,
214 //
215 // If
216 // False True
217 // If |
218 // False True |
219 // | | |
220 // RegionNode_inputs
221 //
222 static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) {
223 top_if = NULL;
224 bot_if = NULL;
225
226 // Check control structure above RegionNode for (if ( if ) )
227 Node *in1 = region->in(1);
228 Node *in2 = region->in(2);
229 Node *in3 = region->in(3);
230 // Check that all inputs are projections
231 if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) {
232 Node *in10 = in1->in(0);
233 Node *in20 = in2->in(0);
234 Node *in30 = in3->in(0);
235 // Check that #1 and #2 are ifTrue and ifFalse from same If
236 if( in10 != NULL && in10->is_If() &&
237 in20 != NULL && in20->is_If() &&
238 in30 != NULL && in30->is_If() && in10 == in20 &&
239 (in1->Opcode() != in2->Opcode()) ) {
240 Node *in100 = in10->in(0);
241 Node *in1000 = (in100 != NULL && in100->is_Proj()) ? in100->in(0) : NULL;
242 // Check that control for in10 comes from other branch of IF from in3
243 if( in1000 != NULL && in1000->is_If() &&
244 in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) {
245 // Control pattern checks
246 top_if = (IfNode*)in1000;
247 bot_if = (IfNode*)in10;
248 }
249 }
250 }
251
252 return (top_if != NULL);
253 }
254
255
256 //------------------------------check_convf2i_clipping-------------------------
257 // Helper function for RegionNode's identification of FP clipping
258 // Verify that the value input to the phi comes from "ConvF2I; LShift; RShift"
259 static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) {
260 convf2i = NULL;
261
262 // Check for the RShiftNode
263 Node *rshift = phi->in(idx);
264 assert( rshift, "Previous checks ensure phi input is present");
265 if( rshift->Opcode() != Op_RShiftI ) { return false; }
266
267 // Check for the LShiftNode
268 Node *lshift = rshift->in(1);
269 assert( lshift, "Previous checks ensure phi input is present");
270 if( lshift->Opcode() != Op_LShiftI ) { return false; }
271
272 // Check for the ConvF2INode
273 Node *conv = lshift->in(1);
274 if( conv->Opcode() != Op_ConvF2I ) { return false; }
275
276 // Check that shift amounts are only to get sign bits set after F2I
277 jint max_cutoff = max->get_int();
278 jint min_cutoff = min->get_int();
279 jint left_shift = lshift->in(2)->get_int();
280 jint right_shift = rshift->in(2)->get_int();
281 jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1);
282 if( left_shift != right_shift ||
283 0 > left_shift || left_shift >= BitsPerJavaInteger ||
284 max_post_shift < max_cutoff ||
285 max_post_shift < -min_cutoff ) {
286 // Shifts are necessary but current transformation eliminates them
287 return false;
288 }
289
290 // OK to return the result of ConvF2I without shifting
291 convf2i = (ConvF2INode*)conv;
292 return true;
293 }
294
295
296 //------------------------------check_compare_clipping-------------------------
297 // Helper function for RegionNode's identification of FP clipping
298 static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) {
299 Node *i1 = iff->in(1);
300 if ( !i1->is_Bool() ) { return false; }
301 BoolNode *bool1 = i1->as_Bool();
302 if( less_than && bool1->_test._test != BoolTest::le ) { return false; }
303 else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; }
304 const Node *cmpF = bool1->in(1);
305 if( cmpF->Opcode() != Op_CmpF ) { return false; }
306 // Test that the float value being compared against
307 // is equivalent to the int value used as a limit
308 Node *nodef = cmpF->in(2);
309 if( nodef->Opcode() != Op_ConF ) { return false; }
310 jfloat conf = nodef->getf();
311 jint coni = limit->get_int();
312 if( ((int)conf) != coni ) { return false; }
313 input = cmpF->in(1);
314 return true;
315 }
316
317 //------------------------------is_unreachable_region--------------------------
318 // Find if the Region node is reachable from the root.
319 bool RegionNode::is_unreachable_region(const PhaseGVN* phase) {
320 Node* top = phase->C->top();
321 assert(req() == 2 || (req() == 3 && in(1) != NULL && in(2) == top), "sanity check arguments");
322 if (_is_unreachable_region) {
323 // Return cached result from previous evaluation which should still be valid
324 assert(is_unreachable_from_root(phase), "walk the graph again and check if its indeed unreachable");
325 return true;
326 }
327
328 // First, cut the simple case of fallthrough region when NONE of
329 // region's phis references itself directly or through a data node.
330 if (is_possible_unsafe_loop(phase)) {
331 // If we have a possible unsafe loop, check if the region node is actually unreachable from root.
332 if (is_unreachable_from_root(phase)) {
333 _is_unreachable_region = true;
334 return true;
335 }
336 }
337 return false;
338 }
339
340 bool RegionNode::is_possible_unsafe_loop(const PhaseGVN* phase) const {
341 uint max = outcnt();
342 uint i;
343 for (i = 0; i < max; i++) {
344 Node* n = raw_out(i);
345 if (n != NULL && n->is_Phi()) {
346 PhiNode* phi = n->as_Phi();
347 assert(phi->in(0) == this, "sanity check phi");
348 if (phi->outcnt() == 0) {
349 continue; // Safe case - no loops
350 }
351 if (phi->outcnt() == 1) {
352 Node* u = phi->raw_out(0);
353 // Skip if only one use is an other Phi or Call or Uncommon trap.
354 // It is safe to consider this case as fallthrough.
355 if (u != NULL && (u->is_Phi() || u->is_CFG())) {
356 continue;
357 }
358 }
359 // Check when phi references itself directly or through an other node.
360 if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe) {
361 break; // Found possible unsafe data loop.
362 }
363 }
364 }
365 if (i >= max) {
366 return false; // An unsafe case was NOT found - don't need graph walk.
367 }
368 return true;
369 }
370
371 bool RegionNode::is_unreachable_from_root(const PhaseGVN* phase) const {
372 ResourceMark rm;
373 Node_List nstack;
374 VectorSet visited;
375
376 // Mark all control nodes reachable from root outputs
377 Node *n = (Node*)phase->C->root();
378 nstack.push(n);
379 visited.set(n->_idx);
380 while (nstack.size() != 0) {
381 n = nstack.pop();
382 uint max = n->outcnt();
383 for (uint i = 0; i < max; i++) {
384 Node* m = n->raw_out(i);
385 if (m != NULL && m->is_CFG()) {
386 if (m == this) {
387 return false; // We reached the Region node - it is not dead.
388 }
389 if (!visited.test_set(m->_idx))
390 nstack.push(m);
391 }
392 }
393 }
394 return true; // The Region node is unreachable - it is dead.
395 }
396
397 Node* PhiNode::try_clean_mem_phi(PhaseGVN *phase) {
398 // Incremental inlining + PhaseStringOpts sometimes produce:
399 //
400 // cmpP with 1 top input
401 // |
402 // If
403 // / \
404 // IfFalse IfTrue /- Some Node
405 // \ / / /
406 // Region / /-MergeMem
407 // \---Phi
408 //
409 //
410 // It's expected by PhaseStringOpts that the Region goes away and is
411 // replaced by If's control input but because there's still a Phi,
412 // the Region stays in the graph. The top input from the cmpP is
413 // propagated forward and a subgraph that is useful goes away. The
414 // code below replaces the Phi with the MergeMem so that the Region
415 // is simplified.
416
417 if (type() == Type::MEMORY && is_diamond_phi(true)) {
418 MergeMemNode* m = NULL;
419 assert(req() == 3, "same as region");
420 Node* r = in(0);
421 for (uint i = 1; i < 3; ++i) {
422 Node *mem = in(i);
423 if (mem && mem->is_MergeMem() && r->in(i)->outcnt() == 1) {
424 // Nothing is control-dependent on path #i except the region itself.
425 m = mem->as_MergeMem();
426 uint j = 3 - i;
427 Node* other = in(j);
428 if (other && other == m->base_memory()) {
429 // m is a successor memory to other, and is not pinned inside the diamond, so push it out.
430 // This will allow the diamond to collapse completely.
431 return m;
432 }
433 }
434 }
435 }
436 return NULL;
437 }
438
439 //------------------------------Ideal------------------------------------------
440 // Return a node which is more "ideal" than the current node. Must preserve
441 // the CFG, but we can still strip out dead paths.
442 Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) {
443 if( !can_reshape && !in(0) ) return NULL; // Already degraded to a Copy
444 assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge");
445
446 // Check for RegionNode with no Phi users and both inputs come from either
447 // arm of the same IF. If found, then the control-flow split is useless.
448 bool has_phis = false;
449 if (can_reshape) { // Need DU info to check for Phi users
450 has_phis = (has_phi() != NULL); // Cache result
451 if (has_phis) {
452 PhiNode* phi = has_unique_phi();
453 if (phi != NULL) {
454 Node* m = phi->try_clean_mem_phi(phase);
455 if (m != NULL) {
456 phase->is_IterGVN()->replace_node(phi, m);
457 has_phis = false;
458 }
459 }
460 }
461
462 if (!has_phis) { // No Phi users? Nothing merging?
463 for (uint i = 1; i < req()-1; i++) {
464 Node *if1 = in(i);
465 if( !if1 ) continue;
466 Node *iff = if1->in(0);
467 if( !iff || !iff->is_If() ) continue;
468 for( uint j=i+1; j<req(); j++ ) {
469 if( in(j) && in(j)->in(0) == iff &&
470 if1->Opcode() != in(j)->Opcode() ) {
471 // Add the IF Projections to the worklist. They (and the IF itself)
472 // will be eliminated if dead.
473 phase->is_IterGVN()->add_users_to_worklist(iff);
474 set_req(i, iff->in(0));// Skip around the useless IF diamond
475 set_req(j, NULL);
476 return this; // Record progress
477 }
478 }
479 }
480 }
481 }
482
483 // Remove TOP or NULL input paths. If only 1 input path remains, this Region
484 // degrades to a copy.
485 bool add_to_worklist = false;
486 bool modified = false;
487 int cnt = 0; // Count of values merging
488 DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count
489 int del_it = 0; // The last input path we delete
490 // For all inputs...
491 for( uint i=1; i<req(); ++i ){// For all paths in
492 Node *n = in(i); // Get the input
493 if( n != NULL ) {
494 // Remove useless control copy inputs
495 if( n->is_Region() && n->as_Region()->is_copy() ) {
496 set_req(i, n->nonnull_req());
497 modified = true;
498 i--;
499 continue;
500 }
501 if( n->is_Proj() ) { // Remove useless rethrows
502 Node *call = n->in(0);
503 if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) {
504 set_req(i, call->in(0));
505 modified = true;
506 i--;
507 continue;
508 }
509 }
510 if( phase->type(n) == Type::TOP ) {
511 set_req(i, NULL); // Ignore TOP inputs
512 modified = true;
513 i--;
514 continue;
515 }
516 cnt++; // One more value merging
517
518 } else if (can_reshape) { // Else found dead path with DU info
519 PhaseIterGVN *igvn = phase->is_IterGVN();
520 del_req(i); // Yank path from self
521 del_it = i;
522 uint max = outcnt();
523 DUIterator j;
524 bool progress = true;
525 while(progress) { // Need to establish property over all users
526 progress = false;
527 for (j = outs(); has_out(j); j++) {
528 Node *n = out(j);
529 if( n->req() != req() && n->is_Phi() ) {
530 assert( n->in(0) == this, "" );
531 igvn->hash_delete(n); // Yank from hash before hacking edges
532 n->set_req_X(i,NULL,igvn);// Correct DU info
533 n->del_req(i); // Yank path from Phis
534 if( max != outcnt() ) {
535 progress = true;
536 j = refresh_out_pos(j);
537 max = outcnt();
538 }
539 }
540 }
541 }
542 add_to_worklist = true;
543 i--;
544 }
545 }
546
547 if (can_reshape && cnt == 1) {
548 // Is it dead loop?
549 // If it is LoopNopde it had 2 (+1 itself) inputs and
550 // one of them was cut. The loop is dead if it was EntryContol.
551 // Loop node may have only one input because entry path
552 // is removed in PhaseIdealLoop::Dominators().
553 assert(!this->is_Loop() || cnt_orig <= 3, "Loop node should have 3 or less inputs");
554 if ((this->is_Loop() && (del_it == LoopNode::EntryControl ||
555 (del_it == 0 && is_unreachable_region(phase)))) ||
556 (!this->is_Loop() && has_phis && is_unreachable_region(phase))) {
557 // Yes, the region will be removed during the next step below.
558 // Cut the backedge input and remove phis since no data paths left.
559 // We don't cut outputs to other nodes here since we need to put them
560 // on the worklist.
561 PhaseIterGVN *igvn = phase->is_IterGVN();
562 if (in(1)->outcnt() == 1) {
563 igvn->_worklist.push(in(1));
564 }
565 del_req(1);
566 cnt = 0;
567 assert( req() == 1, "no more inputs expected" );
568 uint max = outcnt();
569 bool progress = true;
570 Node *top = phase->C->top();
571 DUIterator j;
572 while(progress) {
573 progress = false;
574 for (j = outs(); has_out(j); j++) {
575 Node *n = out(j);
576 if( n->is_Phi() ) {
577 assert(n->in(0) == this, "");
578 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
579 // Break dead loop data path.
580 // Eagerly replace phis with top to avoid regionless phis.
581 igvn->replace_node(n, top);
582 if( max != outcnt() ) {
583 progress = true;
584 j = refresh_out_pos(j);
585 max = outcnt();
586 }
587 }
588 }
589 }
590 add_to_worklist = true;
591 }
592 }
593 if (add_to_worklist) {
594 phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis
595 }
596
597 if( cnt <= 1 ) { // Only 1 path in?
598 set_req(0, NULL); // Null control input for region copy
599 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is.
600 // No inputs or all inputs are NULL.
601 return NULL;
602 } else if (can_reshape) { // Optimization phase - remove the node
603 PhaseIterGVN *igvn = phase->is_IterGVN();
604 // Strip mined (inner) loop is going away, remove outer loop.
605 if (is_CountedLoop() &&
606 as_Loop()->is_strip_mined()) {
607 Node* outer_sfpt = as_CountedLoop()->outer_safepoint();
608 Node* outer_out = as_CountedLoop()->outer_loop_exit();
609 if (outer_sfpt != NULL && outer_out != NULL) {
610 Node* in = outer_sfpt->in(0);
611 igvn->replace_node(outer_out, in);
612 LoopNode* outer = as_CountedLoop()->outer_loop();
613 igvn->replace_input_of(outer, LoopNode::LoopBackControl, igvn->C->top());
614 }
615 }
616 if (is_CountedLoop()) {
617 Node* opaq = as_CountedLoop()->is_canonical_loop_entry();
618 if (opaq != NULL) {
619 // 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
620 // subject to further loop opts.
621 assert(opaq->Opcode() == Op_Opaque1, "");
622 igvn->replace_node(opaq, opaq->in(1));
623 }
624 }
625 Node *parent_ctrl;
626 if( cnt == 0 ) {
627 assert( req() == 1, "no inputs expected" );
628 // During IGVN phase such region will be subsumed by TOP node
629 // so region's phis will have TOP as control node.
630 // Kill phis here to avoid it.
631 // Also set other user's input to top.
632 parent_ctrl = phase->C->top();
633 } else {
634 // The fallthrough case since we already checked dead loops above.
635 parent_ctrl = in(1);
636 assert(parent_ctrl != NULL, "Region is a copy of some non-null control");
637 assert(parent_ctrl != this, "Close dead loop");
638 }
639 if (!add_to_worklist)
640 igvn->add_users_to_worklist(this); // Check for further allowed opts
641 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
642 Node* n = last_out(i);
643 igvn->hash_delete(n); // Remove from worklist before modifying edges
644 if (n->outcnt() == 0) {
645 int uses_found = n->replace_edge(this, phase->C->top(), igvn);
646 if (uses_found > 1) { // (--i) done at the end of the loop.
647 i -= (uses_found - 1);
648 }
649 continue;
650 }
651 if( n->is_Phi() ) { // Collapse all Phis
652 // Eagerly replace phis to avoid regionless phis.
653 Node* in;
654 if( cnt == 0 ) {
655 assert( n->req() == 1, "No data inputs expected" );
656 in = parent_ctrl; // replaced by top
657 } else {
658 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
659 in = n->in(1); // replaced by unique input
660 if( n->as_Phi()->is_unsafe_data_reference(in) )
661 in = phase->C->top(); // replaced by top
662 }
663 igvn->replace_node(n, in);
664 }
665 else if( n->is_Region() ) { // Update all incoming edges
666 assert(n != this, "Must be removed from DefUse edges");
667 int uses_found = n->replace_edge(this, parent_ctrl, igvn);
668 if (uses_found > 1) { // (--i) done at the end of the loop.
669 i -= (uses_found - 1);
670 }
671 }
672 else {
673 assert(n->in(0) == this, "Expect RegionNode to be control parent");
674 n->set_req(0, parent_ctrl);
675 }
676 #ifdef ASSERT
677 for( uint k=0; k < n->req(); k++ ) {
678 assert(n->in(k) != this, "All uses of RegionNode should be gone");
679 }
680 #endif
681 }
682 // Remove the RegionNode itself from DefUse info
683 igvn->remove_dead_node(this);
684 return NULL;
685 }
686 return this; // Record progress
687 }
688
689
690 // If a Region flows into a Region, merge into one big happy merge.
691 if (can_reshape) {
692 Node *m = merge_region(this, phase);
693 if (m != NULL) return m;
694 }
695
696 // Check if this region is the root of a clipping idiom on floats
697 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
698 // Check that only one use is a Phi and that it simplifies to two constants +
699 PhiNode* phi = has_unique_phi();
700 if (phi != NULL) { // One Phi user
701 // Check inputs to the Phi
702 ConNode *min;
703 ConNode *max;
704 Node *val;
705 uint min_idx;
706 uint max_idx;
707 uint val_idx;
708 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) {
709 IfNode *top_if;
710 IfNode *bot_if;
711 if( check_if_clipping( this, bot_if, top_if ) ) {
712 // Control pattern checks, now verify compares
713 Node *top_in = NULL; // value being compared against
714 Node *bot_in = NULL;
715 if( check_compare_clipping( true, bot_if, min, bot_in ) &&
716 check_compare_clipping( false, top_if, max, top_in ) ) {
717 if( bot_in == top_in ) {
718 PhaseIterGVN *gvn = phase->is_IterGVN();
719 assert( gvn != NULL, "Only had DefUse info in IterGVN");
720 // Only remaining check is that bot_in == top_in == (Phi's val + mods)
721
722 // Check for the ConvF2INode
723 ConvF2INode *convf2i;
724 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
725 convf2i->in(1) == bot_in ) {
726 // Matched pattern, including LShiftI; RShiftI, replace with integer compares
727 // max test
728 Node *cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, min ));
729 Node *boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::lt ));
730 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt ));
731 Node *if_min= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
732 Node *ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
733 // min test
734 cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, max ));
735 boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::gt ));
736 iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
737 Node *if_max= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
738 ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
739 // update input edges to region node
740 set_req_X( min_idx, if_min, gvn );
741 set_req_X( max_idx, if_max, gvn );
742 set_req_X( val_idx, ifF, gvn );
743 // remove unnecessary 'LShiftI; RShiftI' idiom
744 gvn->hash_delete(phi);
745 phi->set_req_X( val_idx, convf2i, gvn );
746 gvn->hash_find_insert(phi);
747 // Return transformed region node
748 return this;
749 }
750 }
751 }
752 }
753 }
754 }
755 }
756
757 if (can_reshape) {
758 modified |= optimize_trichotomy(phase->is_IterGVN());
759 }
760
761 return modified ? this : NULL;
762 }
763
764 //------------------------------optimize_trichotomy--------------------------
765 // Optimize nested comparisons of the following kind:
766 //
767 // int compare(int a, int b) {
768 // return (a < b) ? -1 : (a == b) ? 0 : 1;
769 // }
770 //
771 // Shape 1:
772 // if (compare(a, b) == 1) { ... } -> if (a > b) { ... }
773 //
774 // Shape 2:
775 // if (compare(a, b) == 0) { ... } -> if (a == b) { ... }
776 //
777 // Above code leads to the following IR shapes where both Ifs compare the
778 // same value and two out of three region inputs idx1 and idx2 map to
779 // the same value and control flow.
780 //
781 // (1) If (2) If
782 // / \ / \
783 // Proj Proj Proj Proj
784 // | \ | \
785 // | If | If If
786 // | / \ | / \ / \
787 // | Proj Proj | Proj Proj ==> Proj Proj
788 // | / / \ | / | /
789 // Region / \ | / | /
790 // \ / \ | / | /
791 // Region Region Region
792 //
793 // The method returns true if 'this' is modified and false otherwise.
794 bool RegionNode::optimize_trichotomy(PhaseIterGVN* igvn) {
795 int idx1 = 1, idx2 = 2;
796 Node* region = NULL;
797 if (req() == 3 && in(1) != NULL && in(2) != NULL) {
798 // Shape 1: Check if one of the inputs is a region that merges two control
799 // inputs and has no other users (especially no Phi users).
800 region = in(1)->isa_Region() ? in(1) : in(2)->isa_Region();
801 if (region == NULL || region->outcnt() != 2 || region->req() != 3) {
802 return false; // No suitable region input found
803 }
804 } else if (req() == 4) {
805 // Shape 2: Check if two control inputs map to the same value of the unique phi
806 // user and treat these as if they would come from another region (shape (1)).
807 PhiNode* phi = has_unique_phi();
808 if (phi == NULL) {
809 return false; // No unique phi user
810 }
811 if (phi->in(idx1) != phi->in(idx2)) {
812 idx2 = 3;
813 if (phi->in(idx1) != phi->in(idx2)) {
814 idx1 = 2;
815 if (phi->in(idx1) != phi->in(idx2)) {
816 return false; // No equal phi inputs found
817 }
818 }
819 }
820 assert(phi->in(idx1) == phi->in(idx2), "must be"); // Region is merging same value
821 region = this;
822 }
823 if (region == NULL || region->in(idx1) == NULL || region->in(idx2) == NULL) {
824 return false; // Region does not merge two control inputs
825 }
826 // At this point we know that region->in(idx1) and region->(idx2) map to the same
827 // value and control flow. Now search for ifs that feed into these region inputs.
828 ProjNode* proj1 = region->in(idx1)->isa_Proj();
829 ProjNode* proj2 = region->in(idx2)->isa_Proj();
830 if (proj1 == NULL || proj1->outcnt() != 1 ||
831 proj2 == NULL || proj2->outcnt() != 1) {
832 return false; // No projection inputs with region as unique user found
833 }
834 assert(proj1 != proj2, "should be different projections");
835 IfNode* iff1 = proj1->in(0)->isa_If();
836 IfNode* iff2 = proj2->in(0)->isa_If();
837 if (iff1 == NULL || iff1->outcnt() != 2 ||
838 iff2 == NULL || iff2->outcnt() != 2) {
839 return false; // No ifs found
840 }
841 if (iff1 == iff2) {
842 igvn->add_users_to_worklist(iff1); // Make sure dead if is eliminated
843 igvn->replace_input_of(region, idx1, iff1->in(0));
844 igvn->replace_input_of(region, idx2, igvn->C->top());
845 return (region == this); // Remove useless if (both projections map to the same control/value)
846 }
847 BoolNode* bol1 = iff1->in(1)->isa_Bool();
848 BoolNode* bol2 = iff2->in(1)->isa_Bool();
849 if (bol1 == NULL || bol2 == NULL) {
850 return false; // No bool inputs found
851 }
852 Node* cmp1 = bol1->in(1);
853 Node* cmp2 = bol2->in(1);
854 bool commute = false;
855 if (!cmp1->is_Cmp() || !cmp2->is_Cmp()) {
856 return false; // No comparison
857 } else if (cmp1->Opcode() == Op_CmpF || cmp1->Opcode() == Op_CmpD ||
858 cmp2->Opcode() == Op_CmpF || cmp2->Opcode() == Op_CmpD ||
859 cmp1->Opcode() == Op_CmpP || cmp1->Opcode() == Op_CmpN ||
860 cmp2->Opcode() == Op_CmpP || cmp2->Opcode() == Op_CmpN ||
861 cmp1->is_SubTypeCheck() || cmp2->is_SubTypeCheck() ||
862 cmp1->is_FlatArrayCheck() || cmp2->is_FlatArrayCheck()) {
863 // Floats and pointers don't exactly obey trichotomy. To be on the safe side, don't transform their tests.
864 // SubTypeCheck is not commutative
865 return false;
866 } else if (cmp1 != cmp2) {
867 if (cmp1->in(1) == cmp2->in(2) &&
868 cmp1->in(2) == cmp2->in(1)) {
869 commute = true; // Same but swapped inputs, commute the test
870 } else {
871 return false; // Ifs are not comparing the same values
872 }
873 }
874 proj1 = proj1->other_if_proj();
875 proj2 = proj2->other_if_proj();
876 if (!((proj1->unique_ctrl_out() == iff2 &&
877 proj2->unique_ctrl_out() == this) ||
878 (proj2->unique_ctrl_out() == iff1 &&
879 proj1->unique_ctrl_out() == this))) {
880 return false; // Ifs are not connected through other projs
881 }
882 // Found 'iff -> proj -> iff -> proj -> this' shape where all other projs are merged
883 // through 'region' and map to the same value. Merge the boolean tests and replace
884 // the ifs by a single comparison.
885 BoolTest test1 = (proj1->_con == 1) ? bol1->_test : bol1->_test.negate();
886 BoolTest test2 = (proj2->_con == 1) ? bol2->_test : bol2->_test.negate();
887 test1 = commute ? test1.commute() : test1;
888 // After possibly commuting test1, if we can merge test1 & test2, then proj2/iff2/bol2 are the nodes to refine.
889 BoolTest::mask res = test1.merge(test2);
890 if (res == BoolTest::illegal) {
891 return false; // Unable to merge tests
892 }
893 // Adjust iff1 to always pass (only iff2 will remain)
894 igvn->replace_input_of(iff1, 1, igvn->intcon(proj1->_con));
895 if (res == BoolTest::never) {
896 // Merged test is always false, adjust iff2 to always fail
897 igvn->replace_input_of(iff2, 1, igvn->intcon(1 - proj2->_con));
898 } else {
899 // Replace bool input of iff2 with merged test
900 BoolNode* new_bol = new BoolNode(bol2->in(1), res);
901 igvn->replace_input_of(iff2, 1, igvn->transform((proj2->_con == 1) ? new_bol : new_bol->negate(igvn)));
902 if (new_bol->outcnt() == 0) {
903 igvn->remove_dead_node(new_bol);
904 }
905 }
906 return false;
907 }
908
909 const RegMask &RegionNode::out_RegMask() const {
910 return RegMask::Empty;
911 }
912
913 // Find the one non-null required input. RegionNode only
914 Node *Node::nonnull_req() const {
915 assert( is_Region(), "" );
916 for( uint i = 1; i < _cnt; i++ )
917 if( in(i) )
918 return in(i);
919 ShouldNotReachHere();
920 return NULL;
921 }
922
923
924 //=============================================================================
925 // note that these functions assume that the _adr_type field is flattened
926 uint PhiNode::hash() const {
927 const Type* at = _adr_type;
928 return TypeNode::hash() + (at ? at->hash() : 0);
929 }
930 bool PhiNode::cmp( const Node &n ) const {
931 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
932 }
933 static inline
934 const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
935 if (at == NULL || at == TypePtr::BOTTOM) return at;
936 return Compile::current()->alias_type(at)->adr_type();
937 }
938
939 //----------------------------make---------------------------------------------
940 // create a new phi with edges matching r and set (initially) to x
941 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
942 uint preds = r->req(); // Number of predecessor paths
943 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");
944 PhiNode* p = new PhiNode(r, t, at);
945 for (uint j = 1; j < preds; j++) {
946 // Fill in all inputs, except those which the region does not yet have
947 if (r->in(j) != NULL)
948 p->init_req(j, x);
949 }
950 return p;
951 }
952 PhiNode* PhiNode::make(Node* r, Node* x) {
953 const Type* t = x->bottom_type();
954 const TypePtr* at = NULL;
955 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
956 return make(r, x, t, at);
957 }
958 PhiNode* PhiNode::make_blank(Node* r, Node* x) {
959 const Type* t = x->bottom_type();
960 const TypePtr* at = NULL;
961 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
962 return new PhiNode(r, t, at);
963 }
964
965
966 //------------------------slice_memory-----------------------------------------
967 // create a new phi with narrowed memory type
968 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
969 PhiNode* mem = (PhiNode*) clone();
970 *(const TypePtr**)&mem->_adr_type = adr_type;
971 // convert self-loops, or else we get a bad graph
972 for (uint i = 1; i < req(); i++) {
973 if ((const Node*)in(i) == this) mem->set_req(i, mem);
974 }
975 mem->verify_adr_type();
976 return mem;
977 }
978
979 //------------------------split_out_instance-----------------------------------
980 // Split out an instance type from a bottom phi.
981 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const {
982 const TypeOopPtr *t_oop = at->isa_oopptr();
983 assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr");
984 const TypePtr *t = adr_type();
985 assert(type() == Type::MEMORY &&
986 (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
987 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
988 t->is_oopptr()->cast_to_exactness(true)
989 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
990 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop),
991 "bottom or raw memory required");
992
993 // Check if an appropriate node already exists.
994 Node *region = in(0);
995 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) {
996 Node* use = region->fast_out(k);
997 if( use->is_Phi()) {
998 PhiNode *phi2 = use->as_Phi();
999 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) {
1000 return phi2;
1001 }
1002 }
1003 }
1004 Compile *C = igvn->C;
1005 Arena *a = Thread::current()->resource_area();
1006 Node_Array node_map = new Node_Array(a);
1007 Node_Stack stack(a, C->live_nodes() >> 4);
1008 PhiNode *nphi = slice_memory(at);
1009 igvn->register_new_node_with_optimizer( nphi );
1010 node_map.map(_idx, nphi);
1011 stack.push((Node *)this, 1);
1012 while(!stack.is_empty()) {
1013 PhiNode *ophi = stack.node()->as_Phi();
1014 uint i = stack.index();
1015 assert(i >= 1, "not control edge");
1016 stack.pop();
1017 nphi = node_map[ophi->_idx]->as_Phi();
1018 for (; i < ophi->req(); i++) {
1019 Node *in = ophi->in(i);
1020 if (in == NULL || igvn->type(in) == Type::TOP)
1021 continue;
1022 Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, NULL, igvn);
1023 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL;
1024 if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) {
1025 opt = node_map[optphi->_idx];
1026 if (opt == NULL) {
1027 stack.push(ophi, i);
1028 nphi = optphi->slice_memory(at);
1029 igvn->register_new_node_with_optimizer( nphi );
1030 node_map.map(optphi->_idx, nphi);
1031 ophi = optphi;
1032 i = 0; // will get incremented at top of loop
1033 continue;
1034 }
1035 }
1036 nphi->set_req(i, opt);
1037 }
1038 }
1039 return nphi;
1040 }
1041
1042 //------------------------verify_adr_type--------------------------------------
1043 #ifdef ASSERT
1044 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
1045 if (visited.test_set(_idx)) return; //already visited
1046
1047 // recheck constructor invariants:
1048 verify_adr_type(false);
1049
1050 // recheck local phi/phi consistency:
1051 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
1052 "adr_type must be consistent across phi nest");
1053
1054 // walk around
1055 for (uint i = 1; i < req(); i++) {
1056 Node* n = in(i);
1057 if (n == NULL) continue;
1058 const Node* np = in(i);
1059 if (np->is_Phi()) {
1060 np->as_Phi()->verify_adr_type(visited, at);
1061 } else if (n->bottom_type() == Type::TOP
1062 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
1063 // ignore top inputs
1064 } else {
1065 const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
1066 // recheck phi/non-phi consistency at leaves:
1067 assert((nat != NULL) == (at != NULL), "");
1068 assert(nat == at || nat == TypePtr::BOTTOM,
1069 "adr_type must be consistent at leaves of phi nest");
1070 }
1071 }
1072 }
1073
1074 // Verify a whole nest of phis rooted at this one.
1075 void PhiNode::verify_adr_type(bool recursive) const {
1076 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
1077 if (Node::in_dump()) return; // muzzle asserts when printing
1078
1079 assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only");
1080 // Flat array element shouldn't get their own memory slice until flattened_accesses_share_alias is cleared.
1081 // It could be the graph has no loads/stores and flattened_accesses_share_alias is never cleared. EA could still
1082 // creates per element Phis but that wouldn't be a problem as there are no memory accesses for that array.
1083 assert(_adr_type == NULL || _adr_type->isa_aryptr() == NULL ||
1084 _adr_type->is_aryptr()->is_known_instance() ||
1085 !_adr_type->is_aryptr()->is_flat() ||
1086 !Compile::current()->flattened_accesses_share_alias() ||
1087 _adr_type == TypeAryPtr::INLINES, "flat array element shouldn't get its own slice yet");
1088
1089 if (!VerifyAliases) return; // verify thoroughly only if requested
1090
1091 assert(_adr_type == flatten_phi_adr_type(_adr_type),
1092 "Phi::adr_type must be pre-normalized");
1093
1094 if (recursive) {
1095 VectorSet visited;
1096 verify_adr_type(visited, _adr_type);
1097 }
1098 }
1099 #endif
1100
1101
1102 //------------------------------Value------------------------------------------
1103 // Compute the type of the PhiNode
1104 const Type* PhiNode::Value(PhaseGVN* phase) const {
1105 Node *r = in(0); // RegionNode
1106 if( !r ) // Copy or dead
1107 return in(1) ? phase->type(in(1)) : Type::TOP;
1108
1109 // Note: During parsing, phis are often transformed before their regions.
1110 // This means we have to use type_or_null to defend against untyped regions.
1111 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1112 return Type::TOP;
1113
1114 // Check for trip-counted loop. If so, be smarter.
1115 BaseCountedLoopNode* l = r->is_BaseCountedLoop() ? r->as_BaseCountedLoop() : NULL;
1116 if (l && ((const Node*)l->phi() == this)) { // Trip counted loop!
1117 // protect against init_trip() or limit() returning NULL
1118 if (l->can_be_counted_loop(phase)) {
1119 const Node* init = l->init_trip();
1120 const Node* limit = l->limit();
1121 const Node* stride = l->stride();
1122 if (init != NULL && limit != NULL && stride != NULL) {
1123 const TypeInteger* lo = phase->type(init)->isa_integer(l->bt());
1124 const TypeInteger* hi = phase->type(limit)->isa_integer(l->bt());
1125 const TypeInteger* stride_t = phase->type(stride)->isa_integer(l->bt());
1126 if (lo != NULL && hi != NULL && stride_t != NULL) { // Dying loops might have TOP here
1127 assert(stride_t->hi_as_long() >= stride_t->lo_as_long(), "bad stride type");
1128 BoolTest::mask bt = l->loopexit()->test_trip();
1129 // If the loop exit condition is "not equal", the condition
1130 // would not trigger if init > limit (if stride > 0) or if
1131 // init < limit if (stride > 0) so we can't deduce bounds
1132 // for the iv from the exit condition.
1133 if (bt != BoolTest::ne) {
1134 if (stride_t->hi_as_long() < 0) { // Down-counter loop
1135 swap(lo, hi);
1136 return TypeInteger::make(MIN2(lo->lo_as_long(), hi->lo_as_long()), hi->hi_as_long(), 3, l->bt())->filter_speculative(_type);
1137 } else if (stride_t->lo_as_long() >= 0) {
1138 return TypeInteger::make(lo->lo_as_long(), MAX2(lo->hi_as_long(), hi->hi_as_long()), 3, l->bt())->filter_speculative(_type);
1139 }
1140 }
1141 }
1142 }
1143 } else if (l->in(LoopNode::LoopBackControl) != NULL &&
1144 in(LoopNode::EntryControl) != NULL &&
1145 phase->type(l->in(LoopNode::LoopBackControl)) == Type::TOP) {
1146 // During CCP, if we saturate the type of a counted loop's Phi
1147 // before the special code for counted loop above has a chance
1148 // to run (that is as long as the type of the backedge's control
1149 // is top), we might end up with non monotonic types
1150 return phase->type(in(LoopNode::EntryControl))->filter_speculative(_type);
1151 }
1152 }
1153
1154 // Until we have harmony between classes and interfaces in the type
1155 // lattice, we must tread carefully around phis which implicitly
1156 // convert the one to the other.
1157 const TypePtr* ttp = _type->make_ptr();
1158 const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL;
1159 const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_instklassptr() : NULL;
1160 bool is_intf = false;
1161 if (ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
1162 is_intf = true;
1163 } else if (ttkp != NULL && ttkp->is_loaded() && ttkp->klass()->is_interface()) {
1164 is_intf = true;
1165 }
1166
1167 // Default case: merge all inputs
1168 const Type *t = Type::TOP; // Merged type starting value
1169 for (uint i = 1; i < req(); ++i) {// For all paths in
1170 // Reachable control path?
1171 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
1172 const Type* ti = phase->type(in(i));
1173 // We assume that each input of an interface-valued Phi is a true
1174 // subtype of that interface. This might not be true of the meet
1175 // of all the input types. The lattice is not distributive in
1176 // such cases. Ward off asserts in type.cpp by refusing to do
1177 // meets between interfaces and proper classes.
1178 const TypePtr* tip = ti->make_ptr();
1179 const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL;
1180 if (tiip) {
1181 bool ti_is_intf = false;
1182 ciKlass* k = tiip->klass();
1183 if (k->is_loaded() && k->is_interface())
1184 ti_is_intf = true;
1185 if (is_intf != ti_is_intf)
1186 { t = _type; break; }
1187 }
1188 t = t->meet_speculative(ti);
1189 }
1190 }
1191
1192 // The worst-case type (from ciTypeFlow) should be consistent with "t".
1193 // That is, we expect that "t->higher_equal(_type)" holds true.
1194 // There are various exceptions:
1195 // - Inputs which are phis might in fact be widened unnecessarily.
1196 // For example, an input might be a widened int while the phi is a short.
1197 // - Inputs might be BotPtrs but this phi is dependent on a null check,
1198 // and postCCP has removed the cast which encodes the result of the check.
1199 // - The type of this phi is an interface, and the inputs are classes.
1200 // - Value calls on inputs might produce fuzzy results.
1201 // (Occurrences of this case suggest improvements to Value methods.)
1202 //
1203 // It is not possible to see Type::BOTTOM values as phi inputs,
1204 // because the ciTypeFlow pre-pass produces verifier-quality types.
1205 const Type* ft = t->filter_speculative(_type); // Worst case type
1206
1207 #ifdef ASSERT
1208 // The following logic has been moved into TypeOopPtr::filter.
1209 const Type* jt = t->join_speculative(_type);
1210 if (jt->empty()) { // Emptied out???
1211
1212 // Check for evil case of 't' being a class and '_type' expecting an
1213 // interface. This can happen because the bytecodes do not contain
1214 // enough type info to distinguish a Java-level interface variable
1215 // from a Java-level object variable. If we meet 2 classes which
1216 // both implement interface I, but their meet is at 'j/l/O' which
1217 // doesn't implement I, we have no way to tell if the result should
1218 // be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows
1219 // into a Phi which "knows" it's an Interface type we'll have to
1220 // uplift the type.
1221 if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
1222 assert(ft == _type, ""); // Uplift to interface
1223 } else if (!t->empty() && ttkp != NULL && ttkp->is_loaded() && ttkp->klass()->is_interface()) {
1224 assert(ft == _type, ""); // Uplift to interface
1225 } else {
1226 // We also have to handle 'evil cases' of interface- vs. class-arrays
1227 Type::get_arrays_base_elements(jt, _type, NULL, &ttip);
1228 if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
1229 assert(ft == _type, ""); // Uplift to array of interface
1230 } else {
1231 // Otherwise it's something stupid like non-overlapping int ranges
1232 // found on dying counted loops.
1233 assert(ft == Type::TOP, ""); // Canonical empty value
1234 }
1235 }
1236 }
1237
1238 else {
1239
1240 // If we have an interface-typed Phi and we narrow to a class type, the join
1241 // should report back the class. However, if we have a J/L/Object
1242 // class-typed Phi and an interface flows in, it's possible that the meet &
1243 // join report an interface back out. This isn't possible but happens
1244 // because the type system doesn't interact well with interfaces.
1245 const TypePtr *jtp = jt->make_ptr();
1246 const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL;
1247 const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_instklassptr() : NULL;
1248 if( jtip && ttip ) {
1249 if( jtip->is_loaded() && jtip->klass()->is_interface() &&
1250 ttip->is_loaded() && !ttip->klass()->is_interface() ) {
1251 assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) ||
1252 ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), "");
1253 jt = ft;
1254 }
1255 }
1256 if( jtkp && ttkp ) {
1257 if( jtkp->is_loaded() && jtkp->klass()->is_interface() &&
1258 !jtkp->klass_is_exact() && // Keep exact interface klass (6894807)
1259 ttkp->is_loaded() && !ttkp->klass()->is_interface() ) {
1260 assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) ||
1261 ft->isa_narrowklass() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), "");
1262 jt = ft;
1263 }
1264 }
1265 if (jt != ft && jt->base() == ft->base()) {
1266 if (jt->isa_int() &&
1267 jt->is_int()->_lo == ft->is_int()->_lo &&
1268 jt->is_int()->_hi == ft->is_int()->_hi)
1269 jt = ft;
1270 if (jt->isa_long() &&
1271 jt->is_long()->_lo == ft->is_long()->_lo &&
1272 jt->is_long()->_hi == ft->is_long()->_hi)
1273 jt = ft;
1274 }
1275 if (jt != ft) {
1276 tty->print("merge type: "); t->dump(); tty->cr();
1277 tty->print("kill type: "); _type->dump(); tty->cr();
1278 tty->print("join type: "); jt->dump(); tty->cr();
1279 tty->print("filter type: "); ft->dump(); tty->cr();
1280 }
1281 assert(jt == ft, "");
1282 }
1283 #endif //ASSERT
1284
1285 // Deal with conversion problems found in data loops.
1286 ft = phase->saturate(ft, phase->type_or_null(this), _type);
1287
1288 return ft;
1289 }
1290
1291
1292 //------------------------------is_diamond_phi---------------------------------
1293 // Does this Phi represent a simple well-shaped diamond merge? Return the
1294 // index of the true path or 0 otherwise.
1295 // If check_control_only is true, do not inspect the If node at the
1296 // top, and return -1 (not an edge number) on success.
1297 int PhiNode::is_diamond_phi(bool check_control_only) const {
1298 // Check for a 2-path merge
1299 Node *region = in(0);
1300 if( !region ) return 0;
1301 if( region->req() != 3 ) return 0;
1302 if( req() != 3 ) return 0;
1303 // Check that both paths come from the same If
1304 Node *ifp1 = region->in(1);
1305 Node *ifp2 = region->in(2);
1306 if( !ifp1 || !ifp2 ) return 0;
1307 Node *iff = ifp1->in(0);
1308 if( !iff || !iff->is_If() ) return 0;
1309 if( iff != ifp2->in(0) ) return 0;
1310 if (check_control_only) return -1;
1311 // Check for a proper bool/cmp
1312 const Node *b = iff->in(1);
1313 if( !b->is_Bool() ) return 0;
1314 const Node *cmp = b->in(1);
1315 if( !cmp->is_Cmp() ) return 0;
1316
1317 // Check for branching opposite expected
1318 if( ifp2->Opcode() == Op_IfTrue ) {
1319 assert( ifp1->Opcode() == Op_IfFalse, "" );
1320 return 2;
1321 } else {
1322 assert( ifp1->Opcode() == Op_IfTrue, "" );
1323 return 1;
1324 }
1325 }
1326
1327 //----------------------------check_cmove_id-----------------------------------
1328 // Check for CMove'ing a constant after comparing against the constant.
1329 // Happens all the time now, since if we compare equality vs a constant in
1330 // the parser, we "know" the variable is constant on one path and we force
1331 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
1332 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more
1333 // general in that we don't need constants. Since CMove's are only inserted
1334 // in very special circumstances, we do it here on generic Phi's.
1335 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
1336 assert(true_path !=0, "only diamond shape graph expected");
1337
1338 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1339 // phi->region->if_proj->ifnode->bool->cmp
1340 Node* region = in(0);
1341 Node* iff = region->in(1)->in(0);
1342 BoolNode* b = iff->in(1)->as_Bool();
1343 Node* cmp = b->in(1);
1344 Node* tval = in(true_path);
1345 Node* fval = in(3-true_path);
1346 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
1347 if (id == NULL)
1348 return NULL;
1349
1350 // Either value might be a cast that depends on a branch of 'iff'.
1351 // Since the 'id' value will float free of the diamond, either
1352 // decast or return failure.
1353 Node* ctl = id->in(0);
1354 if (ctl != NULL && ctl->in(0) == iff) {
1355 if (id->is_ConstraintCast()) {
1356 return id->in(1);
1357 } else {
1358 // Don't know how to disentangle this value.
1359 return NULL;
1360 }
1361 }
1362
1363 return id;
1364 }
1365
1366 //------------------------------Identity---------------------------------------
1367 // Check for Region being Identity.
1368 Node* PhiNode::Identity(PhaseGVN* phase) {
1369 // Check for no merging going on
1370 // (There used to be special-case code here when this->region->is_Loop.
1371 // It would check for a tributary phi on the backedge that the main phi
1372 // trivially, perhaps with a single cast. The unique_input method
1373 // does all this and more, by reducing such tributaries to 'this'.)
1374 Node* uin = unique_input(phase, false);
1375 if (uin != NULL) {
1376 return uin;
1377 }
1378
1379 int true_path = is_diamond_phi();
1380 if (true_path != 0) {
1381 Node* id = is_cmove_id(phase, true_path);
1382 if (id != NULL) return id;
1383 }
1384
1385 if (phase->is_IterGVN()) {
1386 Node* m = try_clean_mem_phi(phase);
1387 if (m != NULL) {
1388 return m;
1389 }
1390 }
1391
1392
1393 // Looking for phis with identical inputs. If we find one that has
1394 // type TypePtr::BOTTOM, replace the current phi with the bottom phi.
1395 if (phase->is_IterGVN() && type() == Type::MEMORY && adr_type() !=
1396 TypePtr::BOTTOM && !adr_type()->is_known_instance()) {
1397 uint phi_len = req();
1398 Node* phi_reg = region();
1399 for (DUIterator_Fast imax, i = phi_reg->fast_outs(imax); i < imax; i++) {
1400 Node* u = phi_reg->fast_out(i);
1401 if (u->is_Phi() && u->as_Phi()->type() == Type::MEMORY &&
1402 u->adr_type() == TypePtr::BOTTOM && u->in(0) == phi_reg &&
1403 u->req() == phi_len) {
1404 for (uint j = 1; j < phi_len; j++) {
1405 if (in(j) != u->in(j)) {
1406 u = NULL;
1407 break;
1408 }
1409 }
1410 if (u != NULL) {
1411 return u;
1412 }
1413 }
1414 }
1415 }
1416
1417 return this; // No identity
1418 }
1419
1420 //-----------------------------unique_input------------------------------------
1421 // Find the unique value, discounting top, self-loops, and casts.
1422 // Return top if there are no inputs, and self if there are multiple.
1423 Node* PhiNode::unique_input(PhaseTransform* phase, bool uncast) {
1424 // 1) One unique direct input,
1425 // or if uncast is true:
1426 // 2) some of the inputs have an intervening ConstraintCast
1427 // 3) an input is a self loop
1428 //
1429 // 1) input or 2) input or 3) input __
1430 // / \ / \ \ / \
1431 // \ / | cast phi cast
1432 // phi \ / / \ /
1433 // phi / --
1434
1435 Node* r = in(0); // RegionNode
1436 Node* input = NULL; // The unique direct input (maybe uncasted = ConstraintCasts removed)
1437
1438 for (uint i = 1, cnt = req(); i < cnt; ++i) {
1439 Node* rc = r->in(i);
1440 if (rc == NULL || phase->type(rc) == Type::TOP)
1441 continue; // ignore unreachable control path
1442 Node* n = in(i);
1443 if (n == NULL)
1444 continue;
1445 Node* un = n;
1446 if (uncast) {
1447 #ifdef ASSERT
1448 Node* m = un->uncast();
1449 #endif
1450 while (un != NULL && un->req() == 2 && un->is_ConstraintCast()) {
1451 Node* next = un->in(1);
1452 if (phase->type(next)->isa_rawptr() && phase->type(un)->isa_oopptr()) {
1453 // risk exposing raw ptr at safepoint
1454 break;
1455 }
1456 un = next;
1457 }
1458 assert(m == un || un->in(1) == m, "Only expected at CheckCastPP from allocation");
1459 }
1460 if (un == NULL || un == this || phase->type(un) == Type::TOP) {
1461 continue; // ignore if top, or in(i) and "this" are in a data cycle
1462 }
1463 // Check for a unique input (maybe uncasted)
1464 if (input == NULL) {
1465 input = un;
1466 } else if (input != un) {
1467 input = NodeSentinel; // no unique input
1468 }
1469 }
1470 if (input == NULL) {
1471 return phase->C->top(); // no inputs
1472 }
1473
1474 if (input != NodeSentinel) {
1475 return input; // one unique direct input
1476 }
1477
1478 // Nothing.
1479 return NULL;
1480 }
1481
1482 //------------------------------is_x2logic-------------------------------------
1483 // Check for simple convert-to-boolean pattern
1484 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
1485 // Convert Phi to an ConvIB.
1486 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
1487 assert(true_path !=0, "only diamond shape graph expected");
1488 // Convert the true/false index into an expected 0/1 return.
1489 // Map 2->0 and 1->1.
1490 int flipped = 2-true_path;
1491
1492 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1493 // phi->region->if_proj->ifnode->bool->cmp
1494 Node *region = phi->in(0);
1495 Node *iff = region->in(1)->in(0);
1496 BoolNode *b = (BoolNode*)iff->in(1);
1497 const CmpNode *cmp = (CmpNode*)b->in(1);
1498
1499 Node *zero = phi->in(1);
1500 Node *one = phi->in(2);
1501 const Type *tzero = phase->type( zero );
1502 const Type *tone = phase->type( one );
1503
1504 // Check for compare vs 0
1505 const Type *tcmp = phase->type(cmp->in(2));
1506 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
1507 // Allow cmp-vs-1 if the other input is bounded by 0-1
1508 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
1509 return NULL;
1510 flipped = 1-flipped; // Test is vs 1 instead of 0!
1511 }
1512
1513 // Check for setting zero/one opposite expected
1514 if( tzero == TypeInt::ZERO ) {
1515 if( tone == TypeInt::ONE ) {
1516 } else return NULL;
1517 } else if( tzero == TypeInt::ONE ) {
1518 if( tone == TypeInt::ZERO ) {
1519 flipped = 1-flipped;
1520 } else return NULL;
1521 } else return NULL;
1522
1523 // Check for boolean test backwards
1524 if( b->_test._test == BoolTest::ne ) {
1525 } else if( b->_test._test == BoolTest::eq ) {
1526 flipped = 1-flipped;
1527 } else return NULL;
1528
1529 // Build int->bool conversion
1530 Node *n = new Conv2BNode(cmp->in(1));
1531 if( flipped )
1532 n = new XorINode( phase->transform(n), phase->intcon(1) );
1533
1534 return n;
1535 }
1536
1537 //------------------------------is_cond_add------------------------------------
1538 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;"
1539 // To be profitable the control flow has to disappear; there can be no other
1540 // values merging here. We replace the test-and-branch with:
1541 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by
1542 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
1543 // Then convert Y to 0-or-Y and finally add.
1544 // This is a key transform for SpecJava _201_compress.
1545 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
1546 assert(true_path !=0, "only diamond shape graph expected");
1547
1548 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1549 // phi->region->if_proj->ifnode->bool->cmp
1550 RegionNode *region = (RegionNode*)phi->in(0);
1551 Node *iff = region->in(1)->in(0);
1552 BoolNode* b = iff->in(1)->as_Bool();
1553 const CmpNode *cmp = (CmpNode*)b->in(1);
1554
1555 // Make sure only merging this one phi here
1556 if (region->has_unique_phi() != phi) return NULL;
1557
1558 // Make sure each arm of the diamond has exactly one output, which we assume
1559 // is the region. Otherwise, the control flow won't disappear.
1560 if (region->in(1)->outcnt() != 1) return NULL;
1561 if (region->in(2)->outcnt() != 1) return NULL;
1562
1563 // Check for "(P < Q)" of type signed int
1564 if (b->_test._test != BoolTest::lt) return NULL;
1565 if (cmp->Opcode() != Op_CmpI) return NULL;
1566
1567 Node *p = cmp->in(1);
1568 Node *q = cmp->in(2);
1569 Node *n1 = phi->in( true_path);
1570 Node *n2 = phi->in(3-true_path);
1571
1572 int op = n1->Opcode();
1573 if( op != Op_AddI // Need zero as additive identity
1574 /*&&op != Op_SubI &&
1575 op != Op_AddP &&
1576 op != Op_XorI &&
1577 op != Op_OrI*/ )
1578 return NULL;
1579
1580 Node *x = n2;
1581 Node *y = NULL;
1582 if( x == n1->in(1) ) {
1583 y = n1->in(2);
1584 } else if( x == n1->in(2) ) {
1585 y = n1->in(1);
1586 } else return NULL;
1587
1588 // Not so profitable if compare and add are constants
1589 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
1590 return NULL;
1591
1592 Node *cmplt = phase->transform( new CmpLTMaskNode(p,q) );
1593 Node *j_and = phase->transform( new AndINode(cmplt,y) );
1594 return new AddINode(j_and,x);
1595 }
1596
1597 //------------------------------is_absolute------------------------------------
1598 // Check for absolute value.
1599 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
1600 assert(true_path !=0, "only diamond shape graph expected");
1601
1602 int cmp_zero_idx = 0; // Index of compare input where to look for zero
1603 int phi_x_idx = 0; // Index of phi input where to find naked x
1604
1605 // ABS ends with the merge of 2 control flow paths.
1606 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
1607 int false_path = 3 - true_path;
1608
1609 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1610 // phi->region->if_proj->ifnode->bool->cmp
1611 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
1612 Node *cmp = bol->in(1);
1613
1614 // Check bool sense
1615 if (cmp->Opcode() == Op_CmpF || cmp->Opcode() == Op_CmpD) {
1616 switch (bol->_test._test) {
1617 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break;
1618 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1619 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1620 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
1621 default: return NULL; break;
1622 }
1623 } else if (cmp->Opcode() == Op_CmpI || cmp->Opcode() == Op_CmpL) {
1624 switch (bol->_test._test) {
1625 case BoolTest::lt:
1626 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1627 case BoolTest::gt:
1628 case BoolTest::ge: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1629 default: return NULL; break;
1630 }
1631 }
1632
1633 // Test is next
1634 const Type *tzero = NULL;
1635 switch (cmp->Opcode()) {
1636 case Op_CmpI: tzero = TypeInt::ZERO; break; // Integer ABS
1637 case Op_CmpL: tzero = TypeLong::ZERO; break; // Long ABS
1638 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS
1639 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS
1640 default: return NULL;
1641 }
1642
1643 // Find zero input of compare; the other input is being abs'd
1644 Node *x = NULL;
1645 bool flip = false;
1646 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
1647 x = cmp->in(3 - cmp_zero_idx);
1648 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
1649 // The test is inverted, we should invert the result...
1650 x = cmp->in(cmp_zero_idx);
1651 flip = true;
1652 } else {
1653 return NULL;
1654 }
1655
1656 // Next get the 2 pieces being selected, one is the original value
1657 // and the other is the negated value.
1658 if( phi_root->in(phi_x_idx) != x ) return NULL;
1659
1660 // Check other phi input for subtract node
1661 Node *sub = phi_root->in(3 - phi_x_idx);
1662
1663 bool is_sub = sub->Opcode() == Op_SubF || sub->Opcode() == Op_SubD ||
1664 sub->Opcode() == Op_SubI || sub->Opcode() == Op_SubL;
1665
1666 // Allow only Sub(0,X) and fail out for all others; Neg is not OK
1667 if (!is_sub || phase->type(sub->in(1)) != tzero || sub->in(2) != x) return NULL;
1668
1669 if (tzero == TypeF::ZERO) {
1670 x = new AbsFNode(x);
1671 if (flip) {
1672 x = new SubFNode(sub->in(1), phase->transform(x));
1673 }
1674 } else if (tzero == TypeD::ZERO) {
1675 x = new AbsDNode(x);
1676 if (flip) {
1677 x = new SubDNode(sub->in(1), phase->transform(x));
1678 }
1679 } else if (tzero == TypeInt::ZERO && Matcher::match_rule_supported(Op_AbsI)) {
1680 x = new AbsINode(x);
1681 if (flip) {
1682 x = new SubINode(sub->in(1), phase->transform(x));
1683 }
1684 } else if (tzero == TypeLong::ZERO && Matcher::match_rule_supported(Op_AbsL)) {
1685 x = new AbsLNode(x);
1686 if (flip) {
1687 x = new SubLNode(sub->in(1), phase->transform(x));
1688 }
1689 } else return NULL;
1690
1691 return x;
1692 }
1693
1694 //------------------------------split_once-------------------------------------
1695 // Helper for split_flow_path
1696 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
1697 igvn->hash_delete(n); // Remove from hash before hacking edges
1698
1699 uint j = 1;
1700 for (uint i = phi->req()-1; i > 0; i--) {
1701 if (phi->in(i) == val) { // Found a path with val?
1702 // Add to NEW Region/Phi, no DU info
1703 newn->set_req( j++, n->in(i) );
1704 // Remove from OLD Region/Phi
1705 n->del_req(i);
1706 }
1707 }
1708
1709 // Register the new node but do not transform it. Cannot transform until the
1710 // entire Region/Phi conglomerate has been hacked as a single huge transform.
1711 igvn->register_new_node_with_optimizer( newn );
1712
1713 // Now I can point to the new node.
1714 n->add_req(newn);
1715 igvn->_worklist.push(n);
1716 }
1717
1718 //------------------------------split_flow_path--------------------------------
1719 // Check for merging identical values and split flow paths
1720 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) {
1721 BasicType bt = phi->type()->basic_type();
1722 if( bt == T_ILLEGAL || type2size[bt] <= 0 )
1723 return NULL; // Bail out on funny non-value stuff
1724 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a
1725 return NULL; // third unequal input to be worth doing
1726
1727 // Scan for a constant
1728 uint i;
1729 for( i = 1; i < phi->req()-1; i++ ) {
1730 Node *n = phi->in(i);
1731 if( !n ) return NULL;
1732 if( phase->type(n) == Type::TOP ) return NULL;
1733 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN || n->Opcode() == Op_ConNKlass )
1734 break;
1735 }
1736 if( i >= phi->req() ) // Only split for constants
1737 return NULL;
1738
1739 Node *val = phi->in(i); // Constant to split for
1740 uint hit = 0; // Number of times it occurs
1741 Node *r = phi->region();
1742
1743 for( ; i < phi->req(); i++ ){ // Count occurrences of constant
1744 Node *n = phi->in(i);
1745 if( !n ) return NULL;
1746 if( phase->type(n) == Type::TOP ) return NULL;
1747 if( phi->in(i) == val ) {
1748 hit++;
1749 if (PhaseIdealLoop::find_predicate(r->in(i)) != NULL) {
1750 return NULL; // don't split loop entry path
1751 }
1752 }
1753 }
1754
1755 if( hit <= 1 || // Make sure we find 2 or more
1756 hit == phi->req()-1 ) // and not ALL the same value
1757 return NULL;
1758
1759 // Now start splitting out the flow paths that merge the same value.
1760 // Split first the RegionNode.
1761 PhaseIterGVN *igvn = phase->is_IterGVN();
1762 RegionNode *newr = new RegionNode(hit+1);
1763 split_once(igvn, phi, val, r, newr);
1764
1765 // Now split all other Phis than this one
1766 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) {
1767 Node* phi2 = r->fast_out(k);
1768 if( phi2->is_Phi() && phi2->as_Phi() != phi ) {
1769 PhiNode *newphi = PhiNode::make_blank(newr, phi2);
1770 split_once(igvn, phi, val, phi2, newphi);
1771 }
1772 }
1773
1774 // Clean up this guy
1775 igvn->hash_delete(phi);
1776 for( i = phi->req()-1; i > 0; i-- ) {
1777 if( phi->in(i) == val ) {
1778 phi->del_req(i);
1779 }
1780 }
1781 phi->add_req(val);
1782
1783 return phi;
1784 }
1785
1786 //=============================================================================
1787 //------------------------------simple_data_loop_check-------------------------
1788 // Try to determining if the phi node in a simple safe/unsafe data loop.
1789 // Returns:
1790 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
1791 // Safe - safe case when the phi and it's inputs reference only safe data
1792 // nodes;
1793 // Unsafe - the phi and it's inputs reference unsafe data nodes but there
1794 // is no reference back to the phi - need a graph walk
1795 // to determine if it is in a loop;
1796 // UnsafeLoop - unsafe case when the phi references itself directly or through
1797 // unsafe data node.
1798 // Note: a safe data node is a node which could/never reference itself during
1799 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP.
1800 // I mark Phi nodes as safe node not only because they can reference itself
1801 // but also to prevent mistaking the fallthrough case inside an outer loop
1802 // as dead loop when the phi references itselfs through an other phi.
1803 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const {
1804 // It is unsafe loop if the phi node references itself directly.
1805 if (in == (Node*)this)
1806 return UnsafeLoop; // Unsafe loop
1807 // Unsafe loop if the phi node references itself through an unsafe data node.
1808 // Exclude cases with null inputs or data nodes which could reference
1809 // itself (safe for dead loops).
1810 if (in != NULL && !in->is_dead_loop_safe()) {
1811 // Check inputs of phi's inputs also.
1812 // It is much less expensive then full graph walk.
1813 uint cnt = in->req();
1814 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1;
1815 for (; i < cnt; ++i) {
1816 Node* m = in->in(i);
1817 if (m == (Node*)this)
1818 return UnsafeLoop; // Unsafe loop
1819 if (m != NULL && !m->is_dead_loop_safe()) {
1820 // Check the most common case (about 30% of all cases):
1821 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con).
1822 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL;
1823 if (m1 == (Node*)this)
1824 return UnsafeLoop; // Unsafe loop
1825 if (m1 != NULL && m1 == m->in(2) &&
1826 m1->is_dead_loop_safe() && m->in(3)->is_Con()) {
1827 continue; // Safe case
1828 }
1829 // The phi references an unsafe node - need full analysis.
1830 return Unsafe;
1831 }
1832 }
1833 }
1834 return Safe; // Safe case - we can optimize the phi node.
1835 }
1836
1837 //------------------------------is_unsafe_data_reference-----------------------
1838 // If phi can be reached through the data input - it is data loop.
1839 bool PhiNode::is_unsafe_data_reference(Node *in) const {
1840 assert(req() > 1, "");
1841 // First, check simple cases when phi references itself directly or
1842 // through an other node.
1843 LoopSafety safety = simple_data_loop_check(in);
1844 if (safety == UnsafeLoop)
1845 return true; // phi references itself - unsafe loop
1846 else if (safety == Safe)
1847 return false; // Safe case - phi could be replaced with the unique input.
1848
1849 // Unsafe case when we should go through data graph to determine
1850 // if the phi references itself.
1851
1852 ResourceMark rm;
1853
1854 Node_List nstack;
1855 VectorSet visited;
1856
1857 nstack.push(in); // Start with unique input.
1858 visited.set(in->_idx);
1859 while (nstack.size() != 0) {
1860 Node* n = nstack.pop();
1861 uint cnt = n->req();
1862 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1;
1863 for (; i < cnt; i++) {
1864 Node* m = n->in(i);
1865 if (m == (Node*)this) {
1866 return true; // Data loop
1867 }
1868 if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases.
1869 if (!visited.test_set(m->_idx))
1870 nstack.push(m);
1871 }
1872 }
1873 }
1874 return false; // The phi is not reachable from its inputs
1875 }
1876
1877 // Is this Phi's region or some inputs to the region enqueued for IGVN
1878 // and so could cause the region to be optimized out?
1879 bool PhiNode::wait_for_region_igvn(PhaseGVN* phase) {
1880 PhaseIterGVN* igvn = phase->is_IterGVN();
1881 Unique_Node_List& worklist = igvn->_worklist;
1882 bool delay = false;
1883 Node* r = in(0);
1884 for (uint j = 1; j < req(); j++) {
1885 Node* rc = r->in(j);
1886 Node* n = in(j);
1887 if (rc != NULL &&
1888 rc->is_Proj()) {
1889 if (worklist.member(rc)) {
1890 delay = true;
1891 } else if (rc->in(0) != NULL &&
1892 rc->in(0)->is_If()) {
1893 if (worklist.member(rc->in(0))) {
1894 delay = true;
1895 } else if (rc->in(0)->in(1) != NULL &&
1896 rc->in(0)->in(1)->is_Bool()) {
1897 if (worklist.member(rc->in(0)->in(1))) {
1898 delay = true;
1899 } else if (rc->in(0)->in(1)->in(1) != NULL &&
1900 rc->in(0)->in(1)->in(1)->is_Cmp()) {
1901 if (worklist.member(rc->in(0)->in(1)->in(1))) {
1902 delay = true;
1903 }
1904 }
1905 }
1906 }
1907 }
1908 }
1909 if (delay) {
1910 worklist.push(this);
1911 }
1912 return delay;
1913 }
1914
1915 // Push inline type input nodes (and null) down through the phi recursively (can handle data loops).
1916 InlineTypeBaseNode* PhiNode::push_inline_types_through(PhaseGVN* phase, bool can_reshape, ciInlineKlass* vk, bool is_init) {
1917 InlineTypeBaseNode* vt = NULL;
1918 if (_type->isa_ptr()) {
1919 vt = InlineTypePtrNode::make_null(*phase, vk)->clone_with_phis(phase, in(0), is_init);
1920 } else {
1921 vt = InlineTypeNode::make_null(*phase, vk)->clone_with_phis(phase, in(0), is_init);
1922 }
1923 if (can_reshape) {
1924 // Replace phi right away to be able to use the inline
1925 // type node when reaching the phi again through data loops.
1926 PhaseIterGVN* igvn = phase->is_IterGVN();
1927 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
1928 Node* u = fast_out(i);
1929 igvn->rehash_node_delayed(u);
1930 imax -= u->replace_edge(this, vt);
1931 --i;
1932 }
1933 assert(outcnt() == 0, "should be dead now");
1934 }
1935 ResourceMark rm;
1936 Node_List casts;
1937 for (uint i = 1; i < req(); ++i) {
1938 Node* n = in(i);
1939 while (n->is_ConstraintCast()) {
1940 casts.push(n);
1941 n = n->in(1);
1942 }
1943 if (phase->type(n)->is_zero_type()) {
1944 n = InlineTypePtrNode::make_null(*phase, vk);
1945 } else if (n->is_Phi()) {
1946 assert(can_reshape, "can only handle phis during IGVN");
1947 n = phase->transform(n->as_Phi()->push_inline_types_through(phase, can_reshape, vk, is_init));
1948 }
1949 while (casts.size() != 0) {
1950 // Update the cast input and let ConstraintCastNode::Ideal push it through the InlineTypePtrNode
1951 Node* cast = casts.pop();
1952 phase->hash_delete(cast);
1953 cast->set_req(1, n);
1954 n = phase->transform(cast);
1955 assert(n->is_InlineTypePtr(), "Failed to push cast through InlineTypePtr");
1956 }
1957 bool transform = !can_reshape && (i == (req()-1)); // Transform phis on last merge
1958 vt->merge_with(phase, n->as_InlineTypeBase(), i, transform);
1959 }
1960 return vt;
1961 }
1962
1963 //------------------------------Ideal------------------------------------------
1964 // Return a node which is more "ideal" than the current node. Must preserve
1965 // the CFG, but we can still strip out dead paths.
1966 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1967 Node *r = in(0); // RegionNode
1968 assert(r != NULL && r->is_Region(), "this phi must have a region");
1969 assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge");
1970
1971 // Note: During parsing, phis are often transformed before their regions.
1972 // This means we have to use type_or_null to defend against untyped regions.
1973 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1974 return NULL; // No change
1975
1976 Node *top = phase->C->top();
1977 bool new_phi = (outcnt() == 0); // transforming new Phi
1978 // No change for igvn if new phi is not hooked
1979 if (new_phi && can_reshape)
1980 return NULL;
1981
1982 // The are 2 situations when only one valid phi's input is left
1983 // (in addition to Region input).
1984 // One: region is not loop - replace phi with this input.
1985 // Two: region is loop - replace phi with top since this data path is dead
1986 // and we need to break the dead data loop.
1987 Node* progress = NULL; // Record if any progress made
1988 for( uint j = 1; j < req(); ++j ){ // For all paths in
1989 // Check unreachable control paths
1990 Node* rc = r->in(j);
1991 Node* n = in(j); // Get the input
1992 if (rc == NULL || phase->type(rc) == Type::TOP) {
1993 if (n != top) { // Not already top?
1994 PhaseIterGVN *igvn = phase->is_IterGVN();
1995 if (can_reshape && igvn != NULL) {
1996 igvn->_worklist.push(r);
1997 }
1998 // Nuke it down
1999 set_req_X(j, top, phase);
2000 progress = this; // Record progress
2001 }
2002 }
2003 }
2004
2005 if (can_reshape && outcnt() == 0) {
2006 // set_req() above may kill outputs if Phi is referenced
2007 // only by itself on the dead (top) control path.
2008 return top;
2009 }
2010
2011 bool uncasted = false;
2012 Node* uin = unique_input(phase, false);
2013 if (uin == NULL && can_reshape &&
2014 // If there is a chance that the region can be optimized out do
2015 // not add a cast node that we can't remove yet.
2016 !wait_for_region_igvn(phase)) {
2017 uncasted = true;
2018 uin = unique_input(phase, true);
2019 }
2020 if (uin == top) { // Simplest case: no alive inputs.
2021 if (can_reshape) // IGVN transformation
2022 return top;
2023 else
2024 return NULL; // Identity will return TOP
2025 } else if (uin != NULL) {
2026 // Only one not-NULL unique input path is left.
2027 // Determine if this input is backedge of a loop.
2028 // (Skip new phis which have no uses and dead regions).
2029 if (outcnt() > 0 && r->in(0) != NULL) {
2030 if (is_data_loop(r->as_Region(), uin, phase)) {
2031 // Break this data loop to avoid creation of a dead loop.
2032 if (can_reshape) {
2033 return top;
2034 } else {
2035 // We can't return top if we are in Parse phase - cut inputs only
2036 // let Identity to handle the case.
2037 replace_edge(uin, top, phase);
2038 return NULL;
2039 }
2040 }
2041 }
2042
2043 if (uncasted) {
2044 // Add cast nodes between the phi to be removed and its unique input.
2045 // Wait until after parsing for the type information to propagate from the casts.
2046 assert(can_reshape, "Invalid during parsing");
2047 const Type* phi_type = bottom_type();
2048 // Add casts to carry the control dependency of the Phi that is
2049 // going away
2050 Node* cast = NULL;
2051 if (phi_type->isa_ptr()) {
2052 const Type* uin_type = phase->type(uin);
2053 if (!phi_type->isa_oopptr() && !uin_type->isa_oopptr()) {
2054 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, ConstraintCastNode::StrongDependency);
2055 } else {
2056 // Use a CastPP for a cast to not null and a CheckCastPP for
2057 // a cast to a new klass (and both if both null-ness and
2058 // klass change).
2059
2060 // If the type of phi is not null but the type of uin may be
2061 // null, uin's type must be casted to not null
2062 if (phi_type->join(TypePtr::NOTNULL) == phi_type->remove_speculative() &&
2063 uin_type->join(TypePtr::NOTNULL) != uin_type->remove_speculative()) {
2064 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, TypePtr::NOTNULL, ConstraintCastNode::StrongDependency);
2065 }
2066
2067 // If the type of phi and uin, both casted to not null,
2068 // differ the klass of uin must be (check)cast'ed to match
2069 // that of phi
2070 if (phi_type->join_speculative(TypePtr::NOTNULL) != uin_type->join_speculative(TypePtr::NOTNULL)) {
2071 Node* n = uin;
2072 if (cast != NULL) {
2073 cast = phase->transform(cast);
2074 n = cast;
2075 }
2076 cast = ConstraintCastNode::make_cast(Op_CheckCastPP, r, n, phi_type, ConstraintCastNode::StrongDependency);
2077 }
2078 if (cast == NULL) {
2079 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, ConstraintCastNode::StrongDependency);
2080 }
2081 }
2082 } else {
2083 cast = ConstraintCastNode::make_cast_for_type(r, uin, phi_type, ConstraintCastNode::StrongDependency);
2084 }
2085 assert(cast != NULL, "cast should be set");
2086 cast = phase->transform(cast);
2087 // set all inputs to the new cast(s) so the Phi is removed by Identity
2088 PhaseIterGVN* igvn = phase->is_IterGVN();
2089 for (uint i = 1; i < req(); i++) {
2090 set_req_X(i, cast, igvn);
2091 }
2092 uin = cast;
2093 }
2094
2095 // One unique input.
2096 debug_only(Node* ident = Identity(phase));
2097 // The unique input must eventually be detected by the Identity call.
2098 #ifdef ASSERT
2099 if (ident != uin && !ident->is_top()) {
2100 // print this output before failing assert
2101 r->dump(3);
2102 this->dump(3);
2103 ident->dump();
2104 uin->dump();
2105 }
2106 #endif
2107 assert(ident == uin || ident->is_top(), "Identity must clean this up");
2108 return NULL;
2109 }
2110
2111 Node* opt = NULL;
2112 int true_path = is_diamond_phi();
2113 if (true_path != 0 &&
2114 // If one of the diamond's branch is in the process of dying then, the Phi's input for that branch might transform
2115 // to top. If that happens replacing the Phi with an operation that consumes the Phi's inputs will cause the Phi
2116 // to be replaced by top. To prevent that, delay the transformation until the branch has a chance to be removed.
2117 !(can_reshape && wait_for_region_igvn(phase))) {
2118 // Check for CMove'ing identity. If it would be unsafe,
2119 // handle it here. In the safe case, let Identity handle it.
2120 Node* unsafe_id = is_cmove_id(phase, true_path);
2121 if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) )
2122 opt = unsafe_id;
2123
2124 // Check for simple convert-to-boolean pattern
2125 if( opt == NULL )
2126 opt = is_x2logic(phase, this, true_path);
2127
2128 // Check for absolute value
2129 if( opt == NULL )
2130 opt = is_absolute(phase, this, true_path);
2131
2132 // Check for conditional add
2133 if( opt == NULL && can_reshape )
2134 opt = is_cond_add(phase, this, true_path);
2135
2136 // These 4 optimizations could subsume the phi:
2137 // have to check for a dead data loop creation.
2138 if( opt != NULL ) {
2139 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) {
2140 // Found dead loop.
2141 if( can_reshape )
2142 return top;
2143 // We can't return top if we are in Parse phase - cut inputs only
2144 // to stop further optimizations for this phi. Identity will return TOP.
2145 assert(req() == 3, "only diamond merge phi here");
2146 set_req(1, top);
2147 set_req(2, top);
2148 return NULL;
2149 } else {
2150 return opt;
2151 }
2152 }
2153 }
2154
2155 // Check for merging identical values and split flow paths
2156 if (can_reshape) {
2157 opt = split_flow_path(phase, this);
2158 // This optimization only modifies phi - don't need to check for dead loop.
2159 assert(opt == NULL || opt == this, "do not elide phi");
2160 if (opt != NULL) return opt;
2161 }
2162
2163 if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) {
2164 // Try to undo Phi of AddP:
2165 // (Phi (AddP base address offset) (AddP base2 address2 offset2))
2166 // becomes:
2167 // newbase := (Phi base base2)
2168 // newaddress := (Phi address address2)
2169 // newoffset := (Phi offset offset2)
2170 // (AddP newbase newaddress newoffset)
2171 //
2172 // This occurs as a result of unsuccessful split_thru_phi and
2173 // interferes with taking advantage of addressing modes. See the
2174 // clone_shift_expressions code in matcher.cpp
2175 Node* addp = in(1);
2176 Node* base = addp->in(AddPNode::Base);
2177 Node* address = addp->in(AddPNode::Address);
2178 Node* offset = addp->in(AddPNode::Offset);
2179 if (base != NULL && address != NULL && offset != NULL &&
2180 !base->is_top() && !address->is_top() && !offset->is_top()) {
2181 const Type* base_type = base->bottom_type();
2182 const Type* address_type = address->bottom_type();
2183 // make sure that all the inputs are similar to the first one,
2184 // i.e. AddP with base == address and same offset as first AddP
2185 bool doit = true;
2186 for (uint i = 2; i < req(); i++) {
2187 if (in(i) == NULL ||
2188 in(i)->Opcode() != Op_AddP ||
2189 in(i)->in(AddPNode::Base) == NULL ||
2190 in(i)->in(AddPNode::Address) == NULL ||
2191 in(i)->in(AddPNode::Offset) == NULL ||
2192 in(i)->in(AddPNode::Base)->is_top() ||
2193 in(i)->in(AddPNode::Address)->is_top() ||
2194 in(i)->in(AddPNode::Offset)->is_top()) {
2195 doit = false;
2196 break;
2197 }
2198 if (in(i)->in(AddPNode::Offset) != base) {
2199 base = NULL;
2200 }
2201 if (in(i)->in(AddPNode::Offset) != offset) {
2202 offset = NULL;
2203 }
2204 if (in(i)->in(AddPNode::Address) != address) {
2205 address = NULL;
2206 }
2207 // Accumulate type for resulting Phi
2208 base_type = base_type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type());
2209 address_type = address_type->meet_speculative(in(i)->in(AddPNode::Address)->bottom_type());
2210 }
2211 if (doit && base == NULL) {
2212 // Check for neighboring AddP nodes in a tree.
2213 // If they have a base, use that it.
2214 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) {
2215 Node* u = this->fast_out(k);
2216 if (u->is_AddP()) {
2217 Node* base2 = u->in(AddPNode::Base);
2218 if (base2 != NULL && !base2->is_top()) {
2219 if (base == NULL)
2220 base = base2;
2221 else if (base != base2)
2222 { doit = false; break; }
2223 }
2224 }
2225 }
2226 }
2227 if (doit) {
2228 if (base == NULL) {
2229 base = new PhiNode(in(0), base_type, NULL);
2230 for (uint i = 1; i < req(); i++) {
2231 base->init_req(i, in(i)->in(AddPNode::Base));
2232 }
2233 phase->is_IterGVN()->register_new_node_with_optimizer(base);
2234 }
2235 if (address == NULL) {
2236 address = new PhiNode(in(0), address_type, NULL);
2237 for (uint i = 1; i < req(); i++) {
2238 address->init_req(i, in(i)->in(AddPNode::Address));
2239 }
2240 phase->is_IterGVN()->register_new_node_with_optimizer(address);
2241 }
2242 if (offset == NULL) {
2243 offset = new PhiNode(in(0), TypeX_X, NULL);
2244 for (uint i = 1; i < req(); i++) {
2245 offset->init_req(i, in(i)->in(AddPNode::Offset));
2246 }
2247 phase->is_IterGVN()->register_new_node_with_optimizer(offset);
2248 }
2249 return new AddPNode(base, address, offset);
2250 }
2251 }
2252 }
2253
2254 // Split phis through memory merges, so that the memory merges will go away.
2255 // Piggy-back this transformation on the search for a unique input....
2256 // It will be as if the merged memory is the unique value of the phi.
2257 // (Do not attempt this optimization unless parsing is complete.
2258 // It would make the parser's memory-merge logic sick.)
2259 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.)
2260 if (progress == NULL && can_reshape && type() == Type::MEMORY) {
2261 // see if this phi should be sliced
2262 uint merge_width = 0;
2263 bool saw_self = false;
2264 // TODO revisit this with JDK-8247216
2265 bool mergemem_only = true;
2266 for( uint i=1; i<req(); ++i ) {// For all paths in
2267 Node *ii = in(i);
2268 // TOP inputs should not be counted as safe inputs because if the
2269 // Phi references itself through all other inputs then splitting the
2270 // Phi through memory merges would create dead loop at later stage.
2271 if (ii == top) {
2272 return NULL; // Delay optimization until graph is cleaned.
2273 }
2274 if (ii->is_MergeMem()) {
2275 MergeMemNode* n = ii->as_MergeMem();
2276 merge_width = MAX2(merge_width, n->req());
2277 saw_self = saw_self || (n->base_memory() == this);
2278 } else {
2279 mergemem_only = false;
2280 }
2281 }
2282
2283 // This restriction is temporarily necessary to ensure termination:
2284 if (!mergemem_only && !saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0;
2285
2286 if (merge_width > Compile::AliasIdxRaw) {
2287 // found at least one non-empty MergeMem
2288 const TypePtr* at = adr_type();
2289 if (at != TypePtr::BOTTOM) {
2290 // Patch the existing phi to select an input from the merge:
2291 // Phi:AT1(...MergeMem(m0, m1, m2)...) into
2292 // Phi:AT1(...m1...)
2293 int alias_idx = phase->C->get_alias_index(at);
2294 for (uint i=1; i<req(); ++i) {
2295 Node *ii = in(i);
2296 if (ii->is_MergeMem()) {
2297 MergeMemNode* n = ii->as_MergeMem();
2298 // compress paths and change unreachable cycles to TOP
2299 // If not, we can update the input infinitely along a MergeMem cycle
2300 // Equivalent code is in MemNode::Ideal_common
2301 Node *m = phase->transform(n);
2302 if (outcnt() == 0) { // Above transform() may kill us!
2303 return top;
2304 }
2305 // If transformed to a MergeMem, get the desired slice
2306 // Otherwise the returned node represents memory for every slice
2307 Node *new_mem = (m->is_MergeMem()) ?
2308 m->as_MergeMem()->memory_at(alias_idx) : m;
2309 // Update input if it is progress over what we have now
2310 if (new_mem != ii) {
2311 set_req_X(i, new_mem, phase->is_IterGVN());
2312 progress = this;
2313 }
2314 }
2315 }
2316 } else {
2317 // We know that at least one MergeMem->base_memory() == this
2318 // (saw_self == true). If all other inputs also references this phi
2319 // (directly or through data nodes) - it is a dead loop.
2320 bool saw_safe_input = false;
2321 for (uint j = 1; j < req(); ++j) {
2322 Node* n = in(j);
2323 if (n->is_MergeMem()) {
2324 MergeMemNode* mm = n->as_MergeMem();
2325 if (mm->base_memory() == this || mm->base_memory() == mm->empty_memory()) {
2326 // Skip this input if it references back to this phi or if the memory path is dead
2327 continue;
2328 }
2329 }
2330 if (!is_unsafe_data_reference(n)) {
2331 saw_safe_input = true; // found safe input
2332 break;
2333 }
2334 }
2335 if (!saw_safe_input) {
2336 // There is a dead loop: All inputs are either dead or reference back to this phi
2337 return top;
2338 }
2339
2340 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into
2341 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...))
2342 PhaseIterGVN* igvn = phase->is_IterGVN();
2343 Node* hook = new Node(1);
2344 PhiNode* new_base = (PhiNode*) clone();
2345 // Must eagerly register phis, since they participate in loops.
2346 if (igvn) {
2347 igvn->register_new_node_with_optimizer(new_base);
2348 hook->add_req(new_base);
2349 }
2350 MergeMemNode* result = MergeMemNode::make(new_base);
2351 for (uint i = 1; i < req(); ++i) {
2352 Node *ii = in(i);
2353 if (ii->is_MergeMem()) {
2354 MergeMemNode* n = ii->as_MergeMem();
2355 if (igvn) {
2356 // TODO revisit this with JDK-8247216
2357 // Put 'n' on the worklist because it might be modified by MergeMemStream::iteration_setup
2358 igvn->_worklist.push(n);
2359 }
2360 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) {
2361 // If we have not seen this slice yet, make a phi for it.
2362 bool made_new_phi = false;
2363 if (mms.is_empty()) {
2364 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C));
2365 made_new_phi = true;
2366 if (igvn) {
2367 igvn->register_new_node_with_optimizer(new_phi);
2368 hook->add_req(new_phi);
2369 }
2370 mms.set_memory(new_phi);
2371 }
2372 Node* phi = mms.memory();
2373 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice");
2374 phi->set_req(i, mms.memory2());
2375 }
2376 }
2377 }
2378 // Distribute all self-loops.
2379 { // (Extra braces to hide mms.)
2380 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2381 Node* phi = mms.memory();
2382 for (uint i = 1; i < req(); ++i) {
2383 if (phi->in(i) == this) phi->set_req(i, phi);
2384 }
2385 }
2386 }
2387 // now transform the new nodes, and return the mergemem
2388 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2389 Node* phi = mms.memory();
2390 mms.set_memory(phase->transform(phi));
2391 }
2392 hook->destruct(igvn);
2393 // Replace self with the result.
2394 return result;
2395 }
2396 }
2397 //
2398 // Other optimizations on the memory chain
2399 //
2400 const TypePtr* at = adr_type();
2401 for( uint i=1; i<req(); ++i ) {// For all paths in
2402 Node *ii = in(i);
2403 Node *new_in = MemNode::optimize_memory_chain(ii, at, NULL, phase);
2404 if (ii != new_in ) {
2405 set_req(i, new_in);
2406 progress = this;
2407 }
2408 }
2409 }
2410
2411 #ifdef _LP64
2412 // Push DecodeN/DecodeNKlass down through phi.
2413 // The rest of phi graph will transform by split EncodeP node though phis up.
2414 if ((UseCompressedOops || UseCompressedClassPointers) && can_reshape && progress == NULL) {
2415 bool may_push = true;
2416 bool has_decodeN = false;
2417 bool is_decodeN = false;
2418 for (uint i=1; i<req(); ++i) {// For all paths in
2419 Node *ii = in(i);
2420 if (ii->is_DecodeNarrowPtr() && ii->bottom_type() == bottom_type()) {
2421 // Do optimization if a non dead path exist.
2422 if (ii->in(1)->bottom_type() != Type::TOP) {
2423 has_decodeN = true;
2424 is_decodeN = ii->is_DecodeN();
2425 }
2426 } else if (!ii->is_Phi()) {
2427 may_push = false;
2428 }
2429 }
2430
2431 if (has_decodeN && may_push) {
2432 PhaseIterGVN *igvn = phase->is_IterGVN();
2433 // Make narrow type for new phi.
2434 const Type* narrow_t;
2435 if (is_decodeN) {
2436 narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr());
2437 } else {
2438 narrow_t = TypeNarrowKlass::make(this->bottom_type()->is_ptr());
2439 }
2440 PhiNode* new_phi = new PhiNode(r, narrow_t);
2441 uint orig_cnt = req();
2442 for (uint i=1; i<req(); ++i) {// For all paths in
2443 Node *ii = in(i);
2444 Node* new_ii = NULL;
2445 if (ii->is_DecodeNarrowPtr()) {
2446 assert(ii->bottom_type() == bottom_type(), "sanity");
2447 new_ii = ii->in(1);
2448 } else {
2449 assert(ii->is_Phi(), "sanity");
2450 if (ii->as_Phi() == this) {
2451 new_ii = new_phi;
2452 } else {
2453 if (is_decodeN) {
2454 new_ii = new EncodePNode(ii, narrow_t);
2455 } else {
2456 new_ii = new EncodePKlassNode(ii, narrow_t);
2457 }
2458 igvn->register_new_node_with_optimizer(new_ii);
2459 }
2460 }
2461 new_phi->set_req(i, new_ii);
2462 }
2463 igvn->register_new_node_with_optimizer(new_phi, this);
2464 if (is_decodeN) {
2465 progress = new DecodeNNode(new_phi, bottom_type());
2466 } else {
2467 progress = new DecodeNKlassNode(new_phi, bottom_type());
2468 }
2469 }
2470 }
2471 #endif
2472
2473 // Phi (VB ... VB) => VB (Phi ...) (Phi ...)
2474 if (EnableVectorReboxing && can_reshape && progress == NULL) {
2475 PhaseIterGVN* igvn = phase->is_IterGVN();
2476
2477 bool all_inputs_are_equiv_vboxes = true;
2478 for (uint i = 1; i < req(); ++i) {
2479 Node* n = in(i);
2480 if (in(i)->Opcode() != Op_VectorBox) {
2481 all_inputs_are_equiv_vboxes = false;
2482 break;
2483 }
2484 // Check that vector type of vboxes is equivalent
2485 if (i != 1) {
2486 if (Type::cmp(in(i-0)->in(VectorBoxNode::Value)->bottom_type(),
2487 in(i-1)->in(VectorBoxNode::Value)->bottom_type()) != 0) {
2488 all_inputs_are_equiv_vboxes = false;
2489 break;
2490 }
2491 if (Type::cmp(in(i-0)->in(VectorBoxNode::Box)->bottom_type(),
2492 in(i-1)->in(VectorBoxNode::Box)->bottom_type()) != 0) {
2493 all_inputs_are_equiv_vboxes = false;
2494 break;
2495 }
2496 }
2497 }
2498
2499 if (all_inputs_are_equiv_vboxes) {
2500 VectorBoxNode* vbox = static_cast<VectorBoxNode*>(in(1));
2501 PhiNode* new_vbox_phi = new PhiNode(r, vbox->box_type());
2502 PhiNode* new_vect_phi = new PhiNode(r, vbox->vec_type());
2503 for (uint i = 1; i < req(); ++i) {
2504 VectorBoxNode* old_vbox = static_cast<VectorBoxNode*>(in(i));
2505 new_vbox_phi->set_req(i, old_vbox->in(VectorBoxNode::Box));
2506 new_vect_phi->set_req(i, old_vbox->in(VectorBoxNode::Value));
2507 }
2508 igvn->register_new_node_with_optimizer(new_vbox_phi, this);
2509 igvn->register_new_node_with_optimizer(new_vect_phi, this);
2510 progress = new VectorBoxNode(igvn->C, new_vbox_phi, new_vect_phi, vbox->box_type(), vbox->vec_type());
2511 }
2512 }
2513
2514 // Check recursively if inputs are either an inline type, constant null
2515 // or another Phi (including self references through data loops). If so,
2516 // push the inline types down through the phis to enable folding of loads.
2517 if (EnableValhalla && (_type->isa_ptr() || _type->isa_inlinetype()) && req() > 2 && progress == NULL) {
2518 ResourceMark rm;
2519 Unique_Node_List worklist;
2520 worklist.push(this);
2521 bool can_optimize = true;
2522 ciInlineKlass* vk = NULL;
2523 // true if all IsInit inputs of all InlineType* nodes are true
2524 bool is_init = true;
2525 Node_List casts;
2526
2527 for (uint next = 0; next < worklist.size() && can_optimize; next++) {
2528 Node* phi = worklist.at(next);
2529 for (uint i = 1; i < phi->req() && can_optimize; i++) {
2530 Node* n = phi->in(i);
2531 if (n == NULL) {
2532 can_optimize = false;
2533 break;
2534 }
2535 while (n->is_ConstraintCast()) {
2536 casts.push(n);
2537 n = n->in(1);
2538 }
2539 const Type* t = phase->type(n);
2540 if (n->is_InlineTypeBase() && n->as_InlineTypeBase()->can_merge() &&
2541 (vk == NULL || vk == t->inline_klass())) {
2542 vk = (vk == NULL) ? t->inline_klass() : vk;
2543 if (phase->find_int_con(n->as_InlineTypeBase()->get_is_init(), 0) != 1) {
2544 is_init = false;
2545 }
2546 } else if (n->is_Phi() && can_reshape && (n->bottom_type()->isa_ptr() || n->bottom_type()->isa_inlinetype())) {
2547 worklist.push(n);
2548 } else if (t->is_zero_type()) {
2549 is_init = false;
2550 } else {
2551 can_optimize = false;
2552 }
2553 }
2554 }
2555 // Check if cast nodes can be pushed through
2556 const Type* t = Type::get_const_type(vk);
2557 while (casts.size() != 0 && can_optimize && t != NULL) {
2558 Node* cast = casts.pop();
2559 if (t->filter(cast->bottom_type()) == Type::TOP) {
2560 can_optimize = false;
2561 }
2562 }
2563 if (can_optimize && vk != NULL) {
2564 // TODO 8275400
2565 // assert(!_type->isa_ptr() || _type->maybe_null() || is_init, "Phi not null but a possible null was seen");
2566 progress = push_inline_types_through(phase, can_reshape, vk, is_init);
2567 }
2568 }
2569
2570 return progress; // Return any progress
2571 }
2572
2573 bool PhiNode::is_data_loop(RegionNode* r, Node* uin, const PhaseGVN* phase) {
2574 // First, take the short cut when we know it is a loop and the EntryControl data path is dead.
2575 // The loop node may only have one input because the entry path was removed in PhaseIdealLoop::Dominators().
2576 // Then, check if there is a data loop when the phi references itself directly or through other data nodes.
2577 assert(!r->is_Loop() || r->req() <= 3, "Loop node should have 3 or less inputs");
2578 const bool is_loop = (r->is_Loop() && r->req() == 3);
2579 const Node* top = phase->C->top();
2580 if (is_loop) {
2581 return !uin->eqv_uncast(in(LoopNode::EntryControl));
2582 } else {
2583 // We have a data loop either with an unsafe data reference or if a region is unreachable.
2584 return is_unsafe_data_reference(uin)
2585 || (r->req() == 3 && (r->in(1) != top && r->in(2) == top && r->is_unreachable_region(phase)));
2586 }
2587 }
2588
2589 //------------------------------is_tripcount-----------------------------------
2590 bool PhiNode::is_tripcount(BasicType bt) const {
2591 return (in(0) != NULL && in(0)->is_BaseCountedLoop() &&
2592 in(0)->as_BaseCountedLoop()->operates_on(bt, true) &&
2593 in(0)->as_BaseCountedLoop()->phi() == this);
2594 }
2595
2596 //------------------------------out_RegMask------------------------------------
2597 const RegMask &PhiNode::in_RegMask(uint i) const {
2598 return i ? out_RegMask() : RegMask::Empty;
2599 }
2600
2601 const RegMask &PhiNode::out_RegMask() const {
2602 uint ideal_reg = _type->ideal_reg();
2603 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
2604 if( ideal_reg == 0 ) return RegMask::Empty;
2605 assert(ideal_reg != Op_RegFlags, "flags register is not spillable");
2606 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
2607 }
2608
2609 #ifndef PRODUCT
2610 void PhiNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2611 // For a PhiNode, the set of related nodes includes all inputs till level 2,
2612 // and all outputs till level 1. In compact mode, inputs till level 1 are
2613 // collected.
2614 this->collect_nodes(in_rel, compact ? 1 : 2, false, false);
2615 this->collect_nodes(out_rel, -1, false, false);
2616 }
2617
2618 void PhiNode::dump_spec(outputStream *st) const {
2619 TypeNode::dump_spec(st);
2620 if (is_tripcount(T_INT) || is_tripcount(T_LONG)) {
2621 st->print(" #tripcount");
2622 }
2623 }
2624 #endif
2625
2626
2627 //=============================================================================
2628 const Type* GotoNode::Value(PhaseGVN* phase) const {
2629 // If the input is reachable, then we are executed.
2630 // If the input is not reachable, then we are not executed.
2631 return phase->type(in(0));
2632 }
2633
2634 Node* GotoNode::Identity(PhaseGVN* phase) {
2635 return in(0); // Simple copy of incoming control
2636 }
2637
2638 const RegMask &GotoNode::out_RegMask() const {
2639 return RegMask::Empty;
2640 }
2641
2642 #ifndef PRODUCT
2643 //-----------------------------related-----------------------------------------
2644 // The related nodes of a GotoNode are all inputs at level 1, as well as the
2645 // outputs at level 1. This is regardless of compact mode.
2646 void GotoNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2647 this->collect_nodes(in_rel, 1, false, false);
2648 this->collect_nodes(out_rel, -1, false, false);
2649 }
2650 #endif
2651
2652
2653 //=============================================================================
2654 const RegMask &JumpNode::out_RegMask() const {
2655 return RegMask::Empty;
2656 }
2657
2658 #ifndef PRODUCT
2659 //-----------------------------related-----------------------------------------
2660 // The related nodes of a JumpNode are all inputs at level 1, as well as the
2661 // outputs at level 2 (to include actual jump targets beyond projection nodes).
2662 // This is regardless of compact mode.
2663 void JumpNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2664 this->collect_nodes(in_rel, 1, false, false);
2665 this->collect_nodes(out_rel, -2, false, false);
2666 }
2667 #endif
2668
2669 //=============================================================================
2670 const RegMask &JProjNode::out_RegMask() const {
2671 return RegMask::Empty;
2672 }
2673
2674 //=============================================================================
2675 const RegMask &CProjNode::out_RegMask() const {
2676 return RegMask::Empty;
2677 }
2678
2679
2680
2681 //=============================================================================
2682
2683 uint PCTableNode::hash() const { return Node::hash() + _size; }
2684 bool PCTableNode::cmp( const Node &n ) const
2685 { return _size == ((PCTableNode&)n)._size; }
2686
2687 const Type *PCTableNode::bottom_type() const {
2688 const Type** f = TypeTuple::fields(_size);
2689 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2690 return TypeTuple::make(_size, f);
2691 }
2692
2693 //------------------------------Value------------------------------------------
2694 // Compute the type of the PCTableNode. If reachable it is a tuple of
2695 // Control, otherwise the table targets are not reachable
2696 const Type* PCTableNode::Value(PhaseGVN* phase) const {
2697 if( phase->type(in(0)) == Type::CONTROL )
2698 return bottom_type();
2699 return Type::TOP; // All paths dead? Then so are we
2700 }
2701
2702 //------------------------------Ideal------------------------------------------
2703 // Return a node which is more "ideal" than the current node. Strip out
2704 // control copies
2705 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2706 return remove_dead_region(phase, can_reshape) ? this : NULL;
2707 }
2708
2709 //=============================================================================
2710 uint JumpProjNode::hash() const {
2711 return Node::hash() + _dest_bci;
2712 }
2713
2714 bool JumpProjNode::cmp( const Node &n ) const {
2715 return ProjNode::cmp(n) &&
2716 _dest_bci == ((JumpProjNode&)n)._dest_bci;
2717 }
2718
2719 #ifndef PRODUCT
2720 void JumpProjNode::dump_spec(outputStream *st) const {
2721 ProjNode::dump_spec(st);
2722 st->print("@bci %d ",_dest_bci);
2723 }
2724
2725 void JumpProjNode::dump_compact_spec(outputStream *st) const {
2726 ProjNode::dump_compact_spec(st);
2727 st->print("(%d)%d@%d", _switch_val, _proj_no, _dest_bci);
2728 }
2729
2730 void JumpProjNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2731 // The related nodes of a JumpProjNode are its inputs and outputs at level 1.
2732 this->collect_nodes(in_rel, 1, false, false);
2733 this->collect_nodes(out_rel, -1, false, false);
2734 }
2735 #endif
2736
2737 //=============================================================================
2738 //------------------------------Value------------------------------------------
2739 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot
2740 // have the default "fall_through_index" path.
2741 const Type* CatchNode::Value(PhaseGVN* phase) const {
2742 // Unreachable? Then so are all paths from here.
2743 if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
2744 // First assume all paths are reachable
2745 const Type** f = TypeTuple::fields(_size);
2746 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2747 // Identify cases that will always throw an exception
2748 // () rethrow call
2749 // () virtual or interface call with NULL receiver
2750 // () call is a check cast with incompatible arguments
2751 if( in(1)->is_Proj() ) {
2752 Node *i10 = in(1)->in(0);
2753 if( i10->is_Call() ) {
2754 CallNode *call = i10->as_Call();
2755 // Rethrows always throw exceptions, never return
2756 if (call->entry_point() == OptoRuntime::rethrow_stub()) {
2757 f[CatchProjNode::fall_through_index] = Type::TOP;
2758 } else if( call->req() > TypeFunc::Parms ) {
2759 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) );
2760 // Check for null receiver to virtual or interface calls
2761 if( call->is_CallDynamicJava() &&
2762 arg0->higher_equal(TypePtr::NULL_PTR) ) {
2763 f[CatchProjNode::fall_through_index] = Type::TOP;
2764 }
2765 } // End of if not a runtime stub
2766 } // End of if have call above me
2767 } // End of slot 1 is not a projection
2768 return TypeTuple::make(_size, f);
2769 }
2770
2771 //=============================================================================
2772 uint CatchProjNode::hash() const {
2773 return Node::hash() + _handler_bci;
2774 }
2775
2776
2777 bool CatchProjNode::cmp( const Node &n ) const {
2778 return ProjNode::cmp(n) &&
2779 _handler_bci == ((CatchProjNode&)n)._handler_bci;
2780 }
2781
2782
2783 //------------------------------Identity---------------------------------------
2784 // If only 1 target is possible, choose it if it is the main control
2785 Node* CatchProjNode::Identity(PhaseGVN* phase) {
2786 // If my value is control and no other value is, then treat as ID
2787 const TypeTuple *t = phase->type(in(0))->is_tuple();
2788 if (t->field_at(_con) != Type::CONTROL) return this;
2789 // If we remove the last CatchProj and elide the Catch/CatchProj, then we
2790 // also remove any exception table entry. Thus we must know the call
2791 // feeding the Catch will not really throw an exception. This is ok for
2792 // the main fall-thru control (happens when we know a call can never throw
2793 // an exception) or for "rethrow", because a further optimization will
2794 // yank the rethrow (happens when we inline a function that can throw an
2795 // exception and the caller has no handler). Not legal, e.g., for passing
2796 // a NULL receiver to a v-call, or passing bad types to a slow-check-cast.
2797 // These cases MUST throw an exception via the runtime system, so the VM
2798 // will be looking for a table entry.
2799 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode
2800 CallNode *call;
2801 if (_con != TypeFunc::Control && // Bail out if not the main control.
2802 !(proj->is_Proj() && // AND NOT a rethrow
2803 proj->in(0)->is_Call() &&
2804 (call = proj->in(0)->as_Call()) &&
2805 call->entry_point() == OptoRuntime::rethrow_stub()))
2806 return this;
2807
2808 // Search for any other path being control
2809 for (uint i = 0; i < t->cnt(); i++) {
2810 if (i != _con && t->field_at(i) == Type::CONTROL)
2811 return this;
2812 }
2813 // Only my path is possible; I am identity on control to the jump
2814 return in(0)->in(0);
2815 }
2816
2817
2818 #ifndef PRODUCT
2819 void CatchProjNode::dump_spec(outputStream *st) const {
2820 ProjNode::dump_spec(st);
2821 st->print("@bci %d ",_handler_bci);
2822 }
2823 #endif
2824
2825 //=============================================================================
2826 //------------------------------Identity---------------------------------------
2827 // Check for CreateEx being Identity.
2828 Node* CreateExNode::Identity(PhaseGVN* phase) {
2829 if( phase->type(in(1)) == Type::TOP ) return in(1);
2830 if( phase->type(in(0)) == Type::TOP ) return in(0);
2831 // We only come from CatchProj, unless the CatchProj goes away.
2832 // If the CatchProj is optimized away, then we just carry the
2833 // exception oop through.
2834
2835 // CheckCastPPNode::Ideal() for inline types reuses the exception
2836 // paths of a call to perform an allocation: we can see a Phi here.
2837 if (in(1)->is_Phi()) {
2838 return this;
2839 }
2840 CallNode *call = in(1)->in(0)->as_Call();
2841
2842 return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) )
2843 ? this
2844 : call->in(TypeFunc::Parms);
2845 }
2846
2847 //=============================================================================
2848 //------------------------------Value------------------------------------------
2849 // Check for being unreachable.
2850 const Type* NeverBranchNode::Value(PhaseGVN* phase) const {
2851 if (!in(0) || in(0)->is_top()) return Type::TOP;
2852 return bottom_type();
2853 }
2854
2855 //------------------------------Ideal------------------------------------------
2856 // Check for no longer being part of a loop
2857 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2858 if (can_reshape && !in(0)->is_Region()) {
2859 // Dead code elimination can sometimes delete this projection so
2860 // if it's not there, there's nothing to do.
2861 Node* fallthru = proj_out_or_null(0);
2862 if (fallthru != NULL) {
2863 phase->is_IterGVN()->replace_node(fallthru, in(0));
2864 }
2865 return phase->C->top();
2866 }
2867 return NULL;
2868 }
2869
2870 #ifndef PRODUCT
2871 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const {
2872 st->print("%s", Name());
2873 }
2874 #endif