1 /*
2 * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc/shared/barrierSet.hpp"
27 #include "gc/shared/c2/barrierSetC2.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "memory/resourceArea.hpp"
30 #include "oops/objArrayKlass.hpp"
31 #include "opto/addnode.hpp"
32 #include "opto/castnode.hpp"
33 #include "opto/cfgnode.hpp"
34 #include "opto/connode.hpp"
35 #include "opto/convertnode.hpp"
36 #include "opto/inlinetypenode.hpp"
37 #include "opto/loopnode.hpp"
38 #include "opto/machnode.hpp"
39 #include "opto/movenode.hpp"
40 #include "opto/narrowptrnode.hpp"
41 #include "opto/mulnode.hpp"
42 #include "opto/phaseX.hpp"
43 #include "opto/regalloc.hpp"
44 #include "opto/regmask.hpp"
45 #include "opto/runtime.hpp"
46 #include "opto/subnode.hpp"
47 #include "opto/vectornode.hpp"
48 #include "utilities/vmError.hpp"
49
50 // Portions of code courtesy of Clifford Click
51
52 // Optimization - Graph Style
53
54 //=============================================================================
55 //------------------------------Value------------------------------------------
56 // Compute the type of the RegionNode.
57 const Type* RegionNode::Value(PhaseGVN* phase) const {
58 for( uint i=1; i<req(); ++i ) { // For all paths in
59 Node *n = in(i); // Get Control source
60 if( !n ) continue; // Missing inputs are TOP
61 if( phase->type(n) == Type::CONTROL )
62 return Type::CONTROL;
63 }
64 return Type::TOP; // All paths dead? Then so are we
65 }
66
67 //------------------------------Identity---------------------------------------
68 // Check for Region being Identity.
69 Node* RegionNode::Identity(PhaseGVN* phase) {
70 // Cannot have Region be an identity, even if it has only 1 input.
71 // Phi users cannot have their Region input folded away for them,
72 // since they need to select the proper data input
73 return this;
74 }
75
76 //------------------------------merge_region-----------------------------------
77 // If a Region flows into a Region, merge into one big happy merge. This is
78 // hard to do if there is stuff that has to happen
79 static Node *merge_region(RegionNode *region, PhaseGVN *phase) {
80 if( region->Opcode() != Op_Region ) // Do not do to LoopNodes
81 return nullptr;
82 Node *progress = nullptr; // Progress flag
83 PhaseIterGVN *igvn = phase->is_IterGVN();
84
85 uint rreq = region->req();
86 for( uint i = 1; i < rreq; i++ ) {
87 Node *r = region->in(i);
88 if( r && r->Opcode() == Op_Region && // Found a region?
89 r->in(0) == r && // Not already collapsed?
90 r != region && // Avoid stupid situations
91 r->outcnt() == 2 ) { // Self user and 'region' user only?
92 assert(!r->as_Region()->has_phi(), "no phi users");
93 if( !progress ) { // No progress
94 if (region->has_phi()) {
95 return nullptr; // Only flatten if no Phi users
96 // igvn->hash_delete( phi );
97 }
98 igvn->hash_delete( region );
99 progress = region; // Making progress
100 }
101 igvn->hash_delete( r );
102
103 // Append inputs to 'r' onto 'region'
104 for( uint j = 1; j < r->req(); j++ ) {
105 // Move an input from 'r' to 'region'
106 region->add_req(r->in(j));
107 r->set_req(j, phase->C->top());
108 // Update phis of 'region'
109 //for( uint k = 0; k < max; k++ ) {
110 // Node *phi = region->out(k);
111 // if( phi->is_Phi() ) {
112 // phi->add_req(phi->in(i));
113 // }
114 //}
115
116 rreq++; // One more input to Region
117 } // Found a region to merge into Region
118 igvn->_worklist.push(r);
119 // Clobber pointer to the now dead 'r'
120 region->set_req(i, phase->C->top());
121 }
122 }
123
124 return progress;
125 }
126
127
128
129 //--------------------------------has_phi--------------------------------------
130 // Helper function: Return any PhiNode that uses this region or null
131 PhiNode* RegionNode::has_phi() const {
132 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
133 Node* phi = fast_out(i);
134 if (phi->is_Phi()) { // Check for Phi users
135 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
136 return phi->as_Phi(); // this one is good enough
137 }
138 }
139
140 return nullptr;
141 }
142
143
144 //-----------------------------has_unique_phi----------------------------------
145 // Helper function: Return the only PhiNode that uses this region or null
146 PhiNode* RegionNode::has_unique_phi() const {
147 // Check that only one use is a Phi
148 PhiNode* only_phi = nullptr;
149 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
150 Node* phi = fast_out(i);
151 if (phi->is_Phi()) { // Check for Phi users
152 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
153 if (only_phi == nullptr) {
154 only_phi = phi->as_Phi();
155 } else {
156 return nullptr; // multiple phis
157 }
158 }
159 }
160
161 return only_phi;
162 }
163
164
165 //------------------------------check_phi_clipping-----------------------------
166 // Helper function for RegionNode's identification of FP clipping
167 // Check inputs to the Phi
168 static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) {
169 min = nullptr;
170 max = nullptr;
171 val = nullptr;
172 min_idx = 0;
173 max_idx = 0;
174 val_idx = 0;
175 uint phi_max = phi->req();
176 if( phi_max == 4 ) {
177 for( uint j = 1; j < phi_max; ++j ) {
178 Node *n = phi->in(j);
179 int opcode = n->Opcode();
180 switch( opcode ) {
181 case Op_ConI:
182 {
183 if( min == nullptr ) {
184 min = n->Opcode() == Op_ConI ? (ConNode*)n : nullptr;
185 min_idx = j;
186 } else {
187 max = n->Opcode() == Op_ConI ? (ConNode*)n : nullptr;
188 max_idx = j;
189 if( min->get_int() > max->get_int() ) {
190 // Swap min and max
191 ConNode *temp;
192 uint temp_idx;
193 temp = min; min = max; max = temp;
194 temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx;
195 }
196 }
197 }
198 break;
199 default:
200 {
201 val = n;
202 val_idx = j;
203 }
204 break;
205 }
206 }
207 }
208 return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) );
209 }
210
211
212 //------------------------------check_if_clipping------------------------------
213 // Helper function for RegionNode's identification of FP clipping
214 // Check that inputs to Region come from two IfNodes,
215 //
216 // If
217 // False True
218 // If |
219 // False True |
220 // | | |
221 // RegionNode_inputs
222 //
223 static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) {
224 top_if = nullptr;
225 bot_if = nullptr;
226
227 // Check control structure above RegionNode for (if ( if ) )
228 Node *in1 = region->in(1);
229 Node *in2 = region->in(2);
230 Node *in3 = region->in(3);
231 // Check that all inputs are projections
232 if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) {
233 Node *in10 = in1->in(0);
234 Node *in20 = in2->in(0);
235 Node *in30 = in3->in(0);
236 // Check that #1 and #2 are ifTrue and ifFalse from same If
237 if( in10 != nullptr && in10->is_If() &&
238 in20 != nullptr && in20->is_If() &&
239 in30 != nullptr && in30->is_If() && in10 == in20 &&
240 (in1->Opcode() != in2->Opcode()) ) {
241 Node *in100 = in10->in(0);
242 Node *in1000 = (in100 != nullptr && in100->is_Proj()) ? in100->in(0) : nullptr;
243 // Check that control for in10 comes from other branch of IF from in3
244 if( in1000 != nullptr && in1000->is_If() &&
245 in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) {
246 // Control pattern checks
247 top_if = (IfNode*)in1000;
248 bot_if = (IfNode*)in10;
249 }
250 }
251 }
252
253 return (top_if != nullptr);
254 }
255
256
257 //------------------------------check_convf2i_clipping-------------------------
258 // Helper function for RegionNode's identification of FP clipping
259 // Verify that the value input to the phi comes from "ConvF2I; LShift; RShift"
260 static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) {
261 convf2i = nullptr;
262
263 // Check for the RShiftNode
264 Node *rshift = phi->in(idx);
265 assert( rshift, "Previous checks ensure phi input is present");
266 if( rshift->Opcode() != Op_RShiftI ) { return false; }
267
268 // Check for the LShiftNode
269 Node *lshift = rshift->in(1);
270 assert( lshift, "Previous checks ensure phi input is present");
271 if( lshift->Opcode() != Op_LShiftI ) { return false; }
272
273 // Check for the ConvF2INode
274 Node *conv = lshift->in(1);
275 if( conv->Opcode() != Op_ConvF2I ) { return false; }
276
277 // Check that shift amounts are only to get sign bits set after F2I
278 jint max_cutoff = max->get_int();
279 jint min_cutoff = min->get_int();
280 jint left_shift = lshift->in(2)->get_int();
281 jint right_shift = rshift->in(2)->get_int();
282 jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1);
283 if( left_shift != right_shift ||
284 0 > left_shift || left_shift >= BitsPerJavaInteger ||
285 max_post_shift < max_cutoff ||
286 max_post_shift < -min_cutoff ) {
287 // Shifts are necessary but current transformation eliminates them
288 return false;
289 }
290
291 // OK to return the result of ConvF2I without shifting
292 convf2i = (ConvF2INode*)conv;
293 return true;
294 }
295
296
297 //------------------------------check_compare_clipping-------------------------
298 // Helper function for RegionNode's identification of FP clipping
299 static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) {
300 Node *i1 = iff->in(1);
301 if ( !i1->is_Bool() ) { return false; }
302 BoolNode *bool1 = i1->as_Bool();
303 if( less_than && bool1->_test._test != BoolTest::le ) { return false; }
304 else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; }
305 const Node *cmpF = bool1->in(1);
306 if( cmpF->Opcode() != Op_CmpF ) { return false; }
307 // Test that the float value being compared against
308 // is equivalent to the int value used as a limit
309 Node *nodef = cmpF->in(2);
310 if( nodef->Opcode() != Op_ConF ) { return false; }
311 jfloat conf = nodef->getf();
312 jint coni = limit->get_int();
313 if( ((int)conf) != coni ) { return false; }
314 input = cmpF->in(1);
315 return true;
316 }
317
318 //------------------------------is_unreachable_region--------------------------
319 // Check if the RegionNode is part of an unsafe loop and unreachable from root.
320 bool RegionNode::is_unreachable_region(const PhaseGVN* phase) {
321 Node* top = phase->C->top();
322 assert(req() == 2 || (req() == 3 && in(1) != nullptr && in(2) == top), "sanity check arguments");
323 if (_is_unreachable_region) {
324 // Return cached result from previous evaluation which should still be valid
325 assert(is_unreachable_from_root(phase), "walk the graph again and check if its indeed unreachable");
326 return true;
327 }
328
329 // First, cut the simple case of fallthrough region when NONE of
330 // region's phis references itself directly or through a data node.
331 if (is_possible_unsafe_loop(phase)) {
332 // If we have a possible unsafe loop, check if the region node is actually unreachable from root.
333 if (is_unreachable_from_root(phase)) {
334 _is_unreachable_region = true;
335 return true;
336 }
337 }
338 return false;
339 }
340
341 bool RegionNode::is_possible_unsafe_loop(const PhaseGVN* phase) const {
342 uint max = outcnt();
343 uint i;
344 for (i = 0; i < max; i++) {
345 Node* n = raw_out(i);
346 if (n != nullptr && n->is_Phi()) {
347 PhiNode* phi = n->as_Phi();
348 assert(phi->in(0) == this, "sanity check phi");
349 if (phi->outcnt() == 0) {
350 continue; // Safe case - no loops
351 }
352 if (phi->outcnt() == 1) {
353 Node* u = phi->raw_out(0);
354 // Skip if only one use is an other Phi or Call or Uncommon trap.
355 // It is safe to consider this case as fallthrough.
356 if (u != nullptr && (u->is_Phi() || u->is_CFG())) {
357 continue;
358 }
359 }
360 // Check when phi references itself directly or through an other node.
361 if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe) {
362 break; // Found possible unsafe data loop.
363 }
364 }
365 }
366 if (i >= max) {
367 return false; // An unsafe case was NOT found - don't need graph walk.
368 }
369 return true;
370 }
371
372 bool RegionNode::is_unreachable_from_root(const PhaseGVN* phase) const {
373 ResourceMark rm;
374 Node_List nstack;
375 VectorSet visited;
376
377 // Mark all control nodes reachable from root outputs
378 Node* n = (Node*)phase->C->root();
379 nstack.push(n);
380 visited.set(n->_idx);
381 while (nstack.size() != 0) {
382 n = nstack.pop();
383 uint max = n->outcnt();
384 for (uint i = 0; i < max; i++) {
385 Node* m = n->raw_out(i);
386 if (m != nullptr && m->is_CFG()) {
387 if (m == this) {
388 return false; // We reached the Region node - it is not dead.
389 }
390 if (!visited.test_set(m->_idx))
391 nstack.push(m);
392 }
393 }
394 }
395 return true; // The Region node is unreachable - it is dead.
396 }
397
398 #ifdef ASSERT
399 // Is this region in an infinite subgraph?
400 // (no path to root except through false NeverBranch exit)
401 bool RegionNode::is_in_infinite_subgraph() {
402 ResourceMark rm;
403 Unique_Node_List worklist;
404 worklist.push(this);
405 return RegionNode::are_all_nodes_in_infinite_subgraph(worklist);
406 }
407
408 // Are all nodes in worklist in infinite subgraph?
409 // (no path to root except through false NeverBranch exit)
410 // worklist is directly used for the traversal
411 bool RegionNode::are_all_nodes_in_infinite_subgraph(Unique_Node_List& worklist) {
412 // BFS traversal down the CFG, except through NeverBranch exits
413 for (uint i = 0; i < worklist.size(); ++i) {
414 Node* n = worklist.at(i);
415 assert(n->is_CFG(), "only traverse CFG");
416 if (n->is_Root()) {
417 // Found root -> there was an exit!
418 return false;
419 } else if (n->is_NeverBranch()) {
420 // Only follow the loop-internal projection, not the NeverBranch exit
421 ProjNode* proj = n->as_NeverBranch()->proj_out_or_null(0);
422 assert(proj != nullptr, "must find loop-internal projection of NeverBranch");
423 worklist.push(proj);
424 } else {
425 // Traverse all CFG outputs
426 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
427 Node* use = n->fast_out(i);
428 if (use->is_CFG()) {
429 worklist.push(use);
430 }
431 }
432 }
433 }
434 // No exit found for any loop -> all are infinite
435 return true;
436 }
437 #endif //ASSERT
438
439 void RegionNode::set_loop_status(RegionNode::LoopStatus status) {
440 assert(loop_status() == RegionNode::LoopStatus::NeverIrreducibleEntry, "why set our status again?");
441 _loop_status = status;
442 }
443
444 #ifdef ASSERT
445 void RegionNode::verify_can_be_irreducible_entry() const {
446 assert(loop_status() == RegionNode::LoopStatus::MaybeIrreducibleEntry, "must be marked irreducible");
447 assert(!is_Loop(), "LoopNode cannot be irreducible loop entry");
448 }
449 #endif //ASSERT
450
451 void RegionNode::try_clean_mem_phis(PhaseIterGVN* igvn) {
452 // Incremental inlining + PhaseStringOpts sometimes produce:
453 //
454 // cmpP with 1 top input
455 // |
456 // If
457 // / \
458 // IfFalse IfTrue /- Some Node
459 // \ / / /
460 // Region / /-MergeMem
461 // \---Phi
462 //
463 //
464 // It's expected by PhaseStringOpts that the Region goes away and is
465 // replaced by If's control input but because there's still a Phi,
466 // the Region stays in the graph. The top input from the cmpP is
467 // propagated forward and a subgraph that is useful goes away. The
468 // code in PhiNode::try_clean_memory_phi() replaces the Phi with the
469 // MergeMem in order to remove the Region if its last phi dies.
470
471 if (!is_diamond()) {
472 return;
473 }
474
475 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
476 Node* phi = fast_out(i);
477 if (phi->is_Phi() && phi->as_Phi()->try_clean_memory_phi(igvn)) {
478 --i;
479 --imax;
480 }
481 }
482 }
483
484 // Does this region merge a simple diamond formed by a proper IfNode?
485 //
486 // Cmp
487 // /
488 // ctrl Bool
489 // \ /
490 // IfNode
491 // / \
492 // IfFalse IfTrue
493 // \ /
494 // Region
495 bool RegionNode::is_diamond() const {
496 if (req() != 3) {
497 return false;
498 }
499
500 Node* left_path = in(1);
501 Node* right_path = in(2);
502 if (left_path == nullptr || right_path == nullptr) {
503 return false;
504 }
505 Node* diamond_if = left_path->in(0);
506 if (diamond_if == nullptr || !diamond_if->is_If() || diamond_if != right_path->in(0)) {
507 // Not an IfNode merging a diamond or TOP.
508 return false;
509 }
510
511 // Check for a proper bool/cmp
512 const Node* bol = diamond_if->in(1);
513 if (!bol->is_Bool()) {
514 return false;
515 }
516 const Node* cmp = bol->in(1);
517 if (!cmp->is_Cmp()) {
518 return false;
519 }
520 return true;
521 }
522
523 //------------------------------Ideal------------------------------------------
524 // Return a node which is more "ideal" than the current node. Must preserve
525 // the CFG, but we can still strip out dead paths.
526 Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) {
527 if( !can_reshape && !in(0) ) return nullptr; // Already degraded to a Copy
528 assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge");
529
530 // Check for RegionNode with no Phi users and both inputs come from either
531 // arm of the same IF. If found, then the control-flow split is useless.
532 bool has_phis = false;
533 if (can_reshape) { // Need DU info to check for Phi users
534 try_clean_mem_phis(phase->is_IterGVN());
535 has_phis = (has_phi() != nullptr); // Cache result
536
537 if (!has_phis) { // No Phi users? Nothing merging?
538 for (uint i = 1; i < req()-1; i++) {
539 Node *if1 = in(i);
540 if( !if1 ) continue;
541 Node *iff = if1->in(0);
542 if( !iff || !iff->is_If() ) continue;
543 for( uint j=i+1; j<req(); j++ ) {
544 if( in(j) && in(j)->in(0) == iff &&
545 if1->Opcode() != in(j)->Opcode() ) {
546 // Add the IF Projections to the worklist. They (and the IF itself)
547 // will be eliminated if dead.
548 phase->is_IterGVN()->add_users_to_worklist(iff);
549 set_req(i, iff->in(0));// Skip around the useless IF diamond
550 set_req(j, nullptr);
551 return this; // Record progress
552 }
553 }
554 }
555 }
556 }
557
558 // Remove TOP or null input paths. If only 1 input path remains, this Region
559 // degrades to a copy.
560 bool add_to_worklist = true;
561 bool modified = false;
562 int cnt = 0; // Count of values merging
563 DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count
564 DEBUG_ONLY( uint outcnt_orig = outcnt(); )
565 int del_it = 0; // The last input path we delete
566 bool found_top = false; // irreducible loops need to check reachability if we find TOP
567 // For all inputs...
568 for( uint i=1; i<req(); ++i ){// For all paths in
569 Node *n = in(i); // Get the input
570 if( n != nullptr ) {
571 // Remove useless control copy inputs
572 if( n->is_Region() && n->as_Region()->is_copy() ) {
573 set_req(i, n->nonnull_req());
574 modified = true;
575 i--;
576 continue;
577 }
578 if( n->is_Proj() ) { // Remove useless rethrows
579 Node *call = n->in(0);
580 if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) {
581 set_req(i, call->in(0));
582 modified = true;
583 i--;
584 continue;
585 }
586 }
587 if( phase->type(n) == Type::TOP ) {
588 set_req_X(i, nullptr, phase); // Ignore TOP inputs
589 modified = true;
590 found_top = true;
591 i--;
592 continue;
593 }
594 cnt++; // One more value merging
595 } else if (can_reshape) { // Else found dead path with DU info
596 PhaseIterGVN *igvn = phase->is_IterGVN();
597 del_req(i); // Yank path from self
598 del_it = i;
599
600 for (DUIterator_Fast jmax, j = fast_outs(jmax); j < jmax; j++) {
601 Node* use = fast_out(j);
602
603 if (use->req() != req() && use->is_Phi()) {
604 assert(use->in(0) == this, "unexpected control input");
605 igvn->hash_delete(use); // Yank from hash before hacking edges
606 use->set_req_X(i, nullptr, igvn);// Correct DU info
607 use->del_req(i); // Yank path from Phis
608 }
609 }
610
611 if (add_to_worklist) {
612 igvn->add_users_to_worklist(this);
613 add_to_worklist = false;
614 }
615
616 i--;
617 }
618 }
619
620 assert(outcnt() == outcnt_orig, "not expect to remove any use");
621
622 if (can_reshape && found_top && loop_status() == RegionNode::LoopStatus::MaybeIrreducibleEntry) {
623 // Is it a dead irreducible loop?
624 // If an irreducible loop loses one of the multiple entries
625 // that went into the loop head, or any secondary entries,
626 // we need to verify if the irreducible loop is still reachable,
627 // as the special logic in is_unreachable_region only works
628 // for reducible loops.
629 if (is_unreachable_from_root(phase)) {
630 // The irreducible loop is dead - must remove it
631 PhaseIterGVN* igvn = phase->is_IterGVN();
632 remove_unreachable_subgraph(igvn);
633 return nullptr;
634 }
635 } else if (can_reshape && cnt == 1) {
636 // Is it dead loop?
637 // If it is LoopNopde it had 2 (+1 itself) inputs and
638 // one of them was cut. The loop is dead if it was EntryContol.
639 // Loop node may have only one input because entry path
640 // is removed in PhaseIdealLoop::Dominators().
641 assert(!this->is_Loop() || cnt_orig <= 3, "Loop node should have 3 or less inputs");
642 if ((this->is_Loop() && (del_it == LoopNode::EntryControl ||
643 (del_it == 0 && is_unreachable_region(phase)))) ||
644 (!this->is_Loop() && has_phis && is_unreachable_region(phase))) {
645 PhaseIterGVN* igvn = phase->is_IterGVN();
646 remove_unreachable_subgraph(igvn);
647 return nullptr;
648 }
649 }
650
651 if( cnt <= 1 ) { // Only 1 path in?
652 set_req(0, nullptr); // Null control input for region copy
653 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is.
654 // No inputs or all inputs are null.
655 return nullptr;
656 } else if (can_reshape) { // Optimization phase - remove the node
657 PhaseIterGVN *igvn = phase->is_IterGVN();
658 // Strip mined (inner) loop is going away, remove outer loop.
659 if (is_CountedLoop() &&
660 as_Loop()->is_strip_mined()) {
661 Node* outer_sfpt = as_CountedLoop()->outer_safepoint();
662 Node* outer_out = as_CountedLoop()->outer_loop_exit();
663 if (outer_sfpt != nullptr && outer_out != nullptr) {
664 Node* in = outer_sfpt->in(0);
665 igvn->replace_node(outer_out, in);
666 LoopNode* outer = as_CountedLoop()->outer_loop();
667 igvn->replace_input_of(outer, LoopNode::LoopBackControl, igvn->C->top());
668 }
669 }
670 if (is_CountedLoop()) {
671 Node* opaq = as_CountedLoop()->is_canonical_loop_entry();
672 if (opaq != nullptr) {
673 // 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
674 // subject to further loop opts.
675 assert(opaq->Opcode() == Op_OpaqueZeroTripGuard, "");
676 igvn->replace_node(opaq, opaq->in(1));
677 }
678 }
679 Node *parent_ctrl;
680 if( cnt == 0 ) {
681 assert( req() == 1, "no inputs expected" );
682 // During IGVN phase such region will be subsumed by TOP node
683 // so region's phis will have TOP as control node.
684 // Kill phis here to avoid it.
685 // Also set other user's input to top.
686 parent_ctrl = phase->C->top();
687 } else {
688 // The fallthrough case since we already checked dead loops above.
689 parent_ctrl = in(1);
690 assert(parent_ctrl != nullptr, "Region is a copy of some non-null control");
691 assert(parent_ctrl != this, "Close dead loop");
692 }
693 if (add_to_worklist) {
694 igvn->add_users_to_worklist(this); // Check for further allowed opts
695 }
696 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
697 Node* n = last_out(i);
698 igvn->hash_delete(n); // Remove from worklist before modifying edges
699 if (n->outcnt() == 0) {
700 int uses_found = n->replace_edge(this, phase->C->top(), igvn);
701 if (uses_found > 1) { // (--i) done at the end of the loop.
702 i -= (uses_found - 1);
703 }
704 continue;
705 }
706 if( n->is_Phi() ) { // Collapse all Phis
707 // Eagerly replace phis to avoid regionless phis.
708 Node* in;
709 if( cnt == 0 ) {
710 assert( n->req() == 1, "No data inputs expected" );
711 in = parent_ctrl; // replaced by top
712 } else {
713 assert( n->req() == 2 && n->in(1) != nullptr, "Only one data input expected" );
714 in = n->in(1); // replaced by unique input
715 if( n->as_Phi()->is_unsafe_data_reference(in) )
716 in = phase->C->top(); // replaced by top
717 }
718 igvn->replace_node(n, in);
719 }
720 else if( n->is_Region() ) { // Update all incoming edges
721 assert(n != this, "Must be removed from DefUse edges");
722 int uses_found = n->replace_edge(this, parent_ctrl, igvn);
723 if (uses_found > 1) { // (--i) done at the end of the loop.
724 i -= (uses_found - 1);
725 }
726 }
727 else {
728 assert(n->in(0) == this, "Expect RegionNode to be control parent");
729 n->set_req(0, parent_ctrl);
730 }
731 #ifdef ASSERT
732 for( uint k=0; k < n->req(); k++ ) {
733 assert(n->in(k) != this, "All uses of RegionNode should be gone");
734 }
735 #endif
736 }
737 // Remove the RegionNode itself from DefUse info
738 igvn->remove_dead_node(this);
739 return nullptr;
740 }
741 return this; // Record progress
742 }
743
744
745 // If a Region flows into a Region, merge into one big happy merge.
746 if (can_reshape) {
747 Node *m = merge_region(this, phase);
748 if (m != nullptr) return m;
749 }
750
751 // Check if this region is the root of a clipping idiom on floats
752 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
753 // Check that only one use is a Phi and that it simplifies to two constants +
754 PhiNode* phi = has_unique_phi();
755 if (phi != nullptr) { // One Phi user
756 // Check inputs to the Phi
757 ConNode *min;
758 ConNode *max;
759 Node *val;
760 uint min_idx;
761 uint max_idx;
762 uint val_idx;
763 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) {
764 IfNode *top_if;
765 IfNode *bot_if;
766 if( check_if_clipping( this, bot_if, top_if ) ) {
767 // Control pattern checks, now verify compares
768 Node *top_in = nullptr; // value being compared against
769 Node *bot_in = nullptr;
770 if( check_compare_clipping( true, bot_if, min, bot_in ) &&
771 check_compare_clipping( false, top_if, max, top_in ) ) {
772 if( bot_in == top_in ) {
773 PhaseIterGVN *gvn = phase->is_IterGVN();
774 assert( gvn != nullptr, "Only had DefUse info in IterGVN");
775 // Only remaining check is that bot_in == top_in == (Phi's val + mods)
776
777 // Check for the ConvF2INode
778 ConvF2INode *convf2i;
779 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
780 convf2i->in(1) == bot_in ) {
781 // Matched pattern, including LShiftI; RShiftI, replace with integer compares
782 // max test
783 Node *cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, min ));
784 Node *boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::lt ));
785 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt ));
786 Node *if_min= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
787 Node *ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
788 // min test
789 cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, max ));
790 boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::gt ));
791 iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
792 Node *if_max= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
793 ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
794 // update input edges to region node
795 set_req_X( min_idx, if_min, gvn );
796 set_req_X( max_idx, if_max, gvn );
797 set_req_X( val_idx, ifF, gvn );
798 // remove unnecessary 'LShiftI; RShiftI' idiom
799 gvn->hash_delete(phi);
800 phi->set_req_X( val_idx, convf2i, gvn );
801 gvn->hash_find_insert(phi);
802 // Return transformed region node
803 return this;
804 }
805 }
806 }
807 }
808 }
809 }
810 }
811
812 if (can_reshape) {
813 modified |= optimize_trichotomy(phase->is_IterGVN());
814 }
815
816 return modified ? this : nullptr;
817 }
818
819 //--------------------------remove_unreachable_subgraph----------------------
820 // This region and therefore all nodes on the input control path(s) are unreachable
821 // from root. To avoid incomplete removal of unreachable subgraphs, walk up the CFG
822 // and aggressively replace all nodes by top.
823 // If a control node "def" with a single control output "use" has its single output
824 // "use" replaced with top, then "use" removes itself. This has the consequence that
825 // when we visit "use", it already has all inputs removed. They are lost and we cannot
826 // traverse them. This is why we fist find all unreachable nodes, and then remove
827 // them in a second step.
828 void RegionNode::remove_unreachable_subgraph(PhaseIterGVN* igvn) {
829 Node* top = igvn->C->top();
830 ResourceMark rm;
831 Unique_Node_List unreachable; // visit each only once
832 unreachable.push(this);
833 // Recursively find all control inputs.
834 for (uint i = 0; i < unreachable.size(); i++) {
835 Node* n = unreachable.at(i);
836 for (uint i = 0; i < n->req(); ++i) {
837 Node* m = n->in(i);
838 assert(m == nullptr || !m->is_Root(), "Should be unreachable from root");
839 if (m != nullptr && m->is_CFG()) {
840 unreachable.push(m);
841 }
842 }
843 }
844 // Remove all unreachable nodes.
845 for (uint i = 0; i < unreachable.size(); i++) {
846 Node* n = unreachable.at(i);
847 if (n->is_Region()) {
848 // Eagerly replace phis with top to avoid regionless phis.
849 n->set_req(0, nullptr);
850 bool progress = true;
851 uint max = n->outcnt();
852 DUIterator j;
853 while (progress) {
854 progress = false;
855 for (j = n->outs(); n->has_out(j); j++) {
856 Node* u = n->out(j);
857 if (u->is_Phi()) {
858 igvn->replace_node(u, top);
859 if (max != n->outcnt()) {
860 progress = true;
861 j = n->refresh_out_pos(j);
862 max = n->outcnt();
863 }
864 }
865 }
866 }
867 }
868 igvn->replace_node(n, top);
869 }
870 }
871
872 //------------------------------optimize_trichotomy--------------------------
873 // Optimize nested comparisons of the following kind:
874 //
875 // int compare(int a, int b) {
876 // return (a < b) ? -1 : (a == b) ? 0 : 1;
877 // }
878 //
879 // Shape 1:
880 // if (compare(a, b) == 1) { ... } -> if (a > b) { ... }
881 //
882 // Shape 2:
883 // if (compare(a, b) == 0) { ... } -> if (a == b) { ... }
884 //
885 // Above code leads to the following IR shapes where both Ifs compare the
886 // same value and two out of three region inputs idx1 and idx2 map to
887 // the same value and control flow.
888 //
889 // (1) If (2) If
890 // / \ / \
891 // Proj Proj Proj Proj
892 // | \ | \
893 // | If | If If
894 // | / \ | / \ / \
895 // | Proj Proj | Proj Proj ==> Proj Proj
896 // | / / \ | / | /
897 // Region / \ | / | /
898 // \ / \ | / | /
899 // Region Region Region
900 //
901 // The method returns true if 'this' is modified and false otherwise.
902 bool RegionNode::optimize_trichotomy(PhaseIterGVN* igvn) {
903 int idx1 = 1, idx2 = 2;
904 Node* region = nullptr;
905 if (req() == 3 && in(1) != nullptr && in(2) != nullptr) {
906 // Shape 1: Check if one of the inputs is a region that merges two control
907 // inputs and has no other users (especially no Phi users).
908 region = in(1)->isa_Region() ? in(1) : in(2)->isa_Region();
909 if (region == nullptr || region->outcnt() != 2 || region->req() != 3) {
910 return false; // No suitable region input found
911 }
912 } else if (req() == 4) {
913 // Shape 2: Check if two control inputs map to the same value of the unique phi
914 // user and treat these as if they would come from another region (shape (1)).
915 PhiNode* phi = has_unique_phi();
916 if (phi == nullptr) {
917 return false; // No unique phi user
918 }
919 if (phi->in(idx1) != phi->in(idx2)) {
920 idx2 = 3;
921 if (phi->in(idx1) != phi->in(idx2)) {
922 idx1 = 2;
923 if (phi->in(idx1) != phi->in(idx2)) {
924 return false; // No equal phi inputs found
925 }
926 }
927 }
928 assert(phi->in(idx1) == phi->in(idx2), "must be"); // Region is merging same value
929 region = this;
930 }
931 if (region == nullptr || region->in(idx1) == nullptr || region->in(idx2) == nullptr) {
932 return false; // Region does not merge two control inputs
933 }
934 // At this point we know that region->in(idx1) and region->(idx2) map to the same
935 // value and control flow. Now search for ifs that feed into these region inputs.
936 ProjNode* proj1 = region->in(idx1)->isa_Proj();
937 ProjNode* proj2 = region->in(idx2)->isa_Proj();
938 if (proj1 == nullptr || proj1->outcnt() != 1 ||
939 proj2 == nullptr || proj2->outcnt() != 1) {
940 return false; // No projection inputs with region as unique user found
941 }
942 assert(proj1 != proj2, "should be different projections");
943 IfNode* iff1 = proj1->in(0)->isa_If();
944 IfNode* iff2 = proj2->in(0)->isa_If();
945 if (iff1 == nullptr || iff1->outcnt() != 2 ||
946 iff2 == nullptr || iff2->outcnt() != 2) {
947 return false; // No ifs found
948 }
949 if (iff1 == iff2) {
950 igvn->add_users_to_worklist(iff1); // Make sure dead if is eliminated
951 igvn->replace_input_of(region, idx1, iff1->in(0));
952 igvn->replace_input_of(region, idx2, igvn->C->top());
953 return (region == this); // Remove useless if (both projections map to the same control/value)
954 }
955 BoolNode* bol1 = iff1->in(1)->isa_Bool();
956 BoolNode* bol2 = iff2->in(1)->isa_Bool();
957 if (bol1 == nullptr || bol2 == nullptr) {
958 return false; // No bool inputs found
959 }
960 Node* cmp1 = bol1->in(1);
961 Node* cmp2 = bol2->in(1);
962 bool commute = false;
963 if (!cmp1->is_Cmp() || !cmp2->is_Cmp()) {
964 return false; // No comparison
965 } else if (cmp1->Opcode() == Op_CmpF || cmp1->Opcode() == Op_CmpD ||
966 cmp2->Opcode() == Op_CmpF || cmp2->Opcode() == Op_CmpD ||
967 cmp1->Opcode() == Op_CmpP || cmp1->Opcode() == Op_CmpN ||
968 cmp2->Opcode() == Op_CmpP || cmp2->Opcode() == Op_CmpN ||
969 cmp1->is_SubTypeCheck() || cmp2->is_SubTypeCheck() ||
970 cmp1->is_FlatArrayCheck() || cmp2->is_FlatArrayCheck()) {
971 // Floats and pointers don't exactly obey trichotomy. To be on the safe side, don't transform their tests.
972 // SubTypeCheck is not commutative
973 return false;
974 } else if (cmp1 != cmp2) {
975 if (cmp1->in(1) == cmp2->in(2) &&
976 cmp1->in(2) == cmp2->in(1)) {
977 commute = true; // Same but swapped inputs, commute the test
978 } else {
979 return false; // Ifs are not comparing the same values
980 }
981 }
982 proj1 = proj1->other_if_proj();
983 proj2 = proj2->other_if_proj();
984 if (!((proj1->unique_ctrl_out_or_null() == iff2 &&
985 proj2->unique_ctrl_out_or_null() == this) ||
986 (proj2->unique_ctrl_out_or_null() == iff1 &&
987 proj1->unique_ctrl_out_or_null() == this))) {
988 return false; // Ifs are not connected through other projs
989 }
990 // Found 'iff -> proj -> iff -> proj -> this' shape where all other projs are merged
991 // through 'region' and map to the same value. Merge the boolean tests and replace
992 // the ifs by a single comparison.
993 BoolTest test1 = (proj1->_con == 1) ? bol1->_test : bol1->_test.negate();
994 BoolTest test2 = (proj2->_con == 1) ? bol2->_test : bol2->_test.negate();
995 test1 = commute ? test1.commute() : test1;
996 // After possibly commuting test1, if we can merge test1 & test2, then proj2/iff2/bol2 are the nodes to refine.
997 BoolTest::mask res = test1.merge(test2);
998 if (res == BoolTest::illegal) {
999 return false; // Unable to merge tests
1000 }
1001 // Adjust iff1 to always pass (only iff2 will remain)
1002 igvn->replace_input_of(iff1, 1, igvn->intcon(proj1->_con));
1003 if (res == BoolTest::never) {
1004 // Merged test is always false, adjust iff2 to always fail
1005 igvn->replace_input_of(iff2, 1, igvn->intcon(1 - proj2->_con));
1006 } else {
1007 // Replace bool input of iff2 with merged test
1008 BoolNode* new_bol = new BoolNode(bol2->in(1), res);
1009 igvn->replace_input_of(iff2, 1, igvn->transform((proj2->_con == 1) ? new_bol : new_bol->negate(igvn)));
1010 if (new_bol->outcnt() == 0) {
1011 igvn->remove_dead_node(new_bol);
1012 }
1013 }
1014 return false;
1015 }
1016
1017 const RegMask &RegionNode::out_RegMask() const {
1018 return RegMask::Empty;
1019 }
1020
1021 #ifndef PRODUCT
1022 void RegionNode::dump_spec(outputStream* st) const {
1023 Node::dump_spec(st);
1024 switch (loop_status()) {
1025 case RegionNode::LoopStatus::MaybeIrreducibleEntry:
1026 st->print("#irreducible ");
1027 break;
1028 case RegionNode::LoopStatus::Reducible:
1029 st->print("#reducible ");
1030 break;
1031 case RegionNode::LoopStatus::NeverIrreducibleEntry:
1032 break; // nothing
1033 }
1034 }
1035 #endif
1036
1037 // Find the one non-null required input. RegionNode only
1038 Node *Node::nonnull_req() const {
1039 assert( is_Region(), "" );
1040 for( uint i = 1; i < _cnt; i++ )
1041 if( in(i) )
1042 return in(i);
1043 ShouldNotReachHere();
1044 return nullptr;
1045 }
1046
1047
1048 //=============================================================================
1049 // note that these functions assume that the _adr_type field is flat
1050 uint PhiNode::hash() const {
1051 const Type* at = _adr_type;
1052 return TypeNode::hash() + (at ? at->hash() : 0);
1053 }
1054 bool PhiNode::cmp( const Node &n ) const {
1055 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
1056 }
1057 static inline
1058 const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
1059 if (at == nullptr || at == TypePtr::BOTTOM) return at;
1060 return Compile::current()->alias_type(at)->adr_type();
1061 }
1062
1063 //----------------------------make---------------------------------------------
1064 // create a new phi with edges matching r and set (initially) to x
1065 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
1066 uint preds = r->req(); // Number of predecessor paths
1067 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at) || (flatten_phi_adr_type(at) == TypeAryPtr::INLINES && Compile::current()->flat_accesses_share_alias()), "flatten at");
1068 PhiNode* p = new PhiNode(r, t, at);
1069 for (uint j = 1; j < preds; j++) {
1070 // Fill in all inputs, except those which the region does not yet have
1071 if (r->in(j) != nullptr)
1072 p->init_req(j, x);
1073 }
1074 return p;
1075 }
1076 PhiNode* PhiNode::make(Node* r, Node* x) {
1077 const Type* t = x->bottom_type();
1078 const TypePtr* at = nullptr;
1079 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
1080 return make(r, x, t, at);
1081 }
1082 PhiNode* PhiNode::make_blank(Node* r, Node* x) {
1083 const Type* t = x->bottom_type();
1084 const TypePtr* at = nullptr;
1085 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
1086 return new PhiNode(r, t, at);
1087 }
1088
1089
1090 //------------------------slice_memory-----------------------------------------
1091 // create a new phi with narrowed memory type
1092 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
1093 PhiNode* mem = (PhiNode*) clone();
1094 *(const TypePtr**)&mem->_adr_type = adr_type;
1095 // convert self-loops, or else we get a bad graph
1096 for (uint i = 1; i < req(); i++) {
1097 if ((const Node*)in(i) == this) mem->set_req(i, mem);
1098 }
1099 mem->verify_adr_type();
1100 return mem;
1101 }
1102
1103 //------------------------split_out_instance-----------------------------------
1104 // Split out an instance type from a bottom phi.
1105 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const {
1106 const TypeOopPtr *t_oop = at->isa_oopptr();
1107 assert(t_oop != nullptr && t_oop->is_known_instance(), "expecting instance oopptr");
1108
1109 // Check if an appropriate node already exists.
1110 Node *region = in(0);
1111 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) {
1112 Node* use = region->fast_out(k);
1113 if( use->is_Phi()) {
1114 PhiNode *phi2 = use->as_Phi();
1115 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) {
1116 return phi2;
1117 }
1118 }
1119 }
1120 Compile *C = igvn->C;
1121 Node_Array node_map;
1122 Node_Stack stack(C->live_nodes() >> 4);
1123 PhiNode *nphi = slice_memory(at);
1124 igvn->register_new_node_with_optimizer( nphi );
1125 node_map.map(_idx, nphi);
1126 stack.push((Node *)this, 1);
1127 while(!stack.is_empty()) {
1128 PhiNode *ophi = stack.node()->as_Phi();
1129 uint i = stack.index();
1130 assert(i >= 1, "not control edge");
1131 stack.pop();
1132 nphi = node_map[ophi->_idx]->as_Phi();
1133 for (; i < ophi->req(); i++) {
1134 Node *in = ophi->in(i);
1135 if (in == nullptr || igvn->type(in) == Type::TOP)
1136 continue;
1137 Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, nullptr, igvn);
1138 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : nullptr;
1139 if (optphi != nullptr && optphi->adr_type() == TypePtr::BOTTOM) {
1140 opt = node_map[optphi->_idx];
1141 if (opt == nullptr) {
1142 stack.push(ophi, i);
1143 nphi = optphi->slice_memory(at);
1144 igvn->register_new_node_with_optimizer( nphi );
1145 node_map.map(optphi->_idx, nphi);
1146 ophi = optphi;
1147 i = 0; // will get incremented at top of loop
1148 continue;
1149 }
1150 }
1151 nphi->set_req(i, opt);
1152 }
1153 }
1154 return nphi;
1155 }
1156
1157 //------------------------verify_adr_type--------------------------------------
1158 #ifdef ASSERT
1159 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
1160 if (visited.test_set(_idx)) return; //already visited
1161
1162 // recheck constructor invariants:
1163 verify_adr_type(false);
1164
1165 // recheck local phi/phi consistency:
1166 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
1167 "adr_type must be consistent across phi nest");
1168
1169 // walk around
1170 for (uint i = 1; i < req(); i++) {
1171 Node* n = in(i);
1172 if (n == nullptr) continue;
1173 const Node* np = in(i);
1174 if (np->is_Phi()) {
1175 np->as_Phi()->verify_adr_type(visited, at);
1176 } else if (n->bottom_type() == Type::TOP
1177 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
1178 // ignore top inputs
1179 } else {
1180 const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
1181 // recheck phi/non-phi consistency at leaves:
1182 assert((nat != nullptr) == (at != nullptr), "");
1183 assert(nat == at || nat == TypePtr::BOTTOM,
1184 "adr_type must be consistent at leaves of phi nest");
1185 }
1186 }
1187 }
1188
1189 // Verify a whole nest of phis rooted at this one.
1190 void PhiNode::verify_adr_type(bool recursive) const {
1191 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
1192 if (Node::in_dump()) return; // muzzle asserts when printing
1193
1194 assert((_type == Type::MEMORY) == (_adr_type != nullptr), "adr_type for memory phis only");
1195 // Flat array element shouldn't get their own memory slice until flat_accesses_share_alias is cleared.
1196 // It could be the graph has no loads/stores and flat_accesses_share_alias is never cleared. EA could still
1197 // creates per element Phis but that wouldn't be a problem as there are no memory accesses for that array.
1198 assert(_adr_type == nullptr || _adr_type->isa_aryptr() == nullptr ||
1199 _adr_type->is_aryptr()->is_known_instance() ||
1200 !_adr_type->is_aryptr()->is_flat() ||
1201 !Compile::current()->flat_accesses_share_alias() ||
1202 _adr_type == TypeAryPtr::INLINES, "flat array element shouldn't get its own slice yet");
1203
1204 if (!VerifyAliases) return; // verify thoroughly only if requested
1205
1206 assert(_adr_type == flatten_phi_adr_type(_adr_type),
1207 "Phi::adr_type must be pre-normalized");
1208
1209 if (recursive) {
1210 VectorSet visited;
1211 verify_adr_type(visited, _adr_type);
1212 }
1213 }
1214 #endif
1215
1216
1217 //------------------------------Value------------------------------------------
1218 // Compute the type of the PhiNode
1219 const Type* PhiNode::Value(PhaseGVN* phase) const {
1220 Node *r = in(0); // RegionNode
1221 if( !r ) // Copy or dead
1222 return in(1) ? phase->type(in(1)) : Type::TOP;
1223
1224 // Note: During parsing, phis are often transformed before their regions.
1225 // This means we have to use type_or_null to defend against untyped regions.
1226 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1227 return Type::TOP;
1228
1229 // Check for trip-counted loop. If so, be smarter.
1230 BaseCountedLoopNode* l = r->is_BaseCountedLoop() ? r->as_BaseCountedLoop() : nullptr;
1231 if (l && ((const Node*)l->phi() == this)) { // Trip counted loop!
1232 // protect against init_trip() or limit() returning null
1233 if (l->can_be_counted_loop(phase)) {
1234 const Node* init = l->init_trip();
1235 const Node* limit = l->limit();
1236 const Node* stride = l->stride();
1237 if (init != nullptr && limit != nullptr && stride != nullptr) {
1238 const TypeInteger* lo = phase->type(init)->isa_integer(l->bt());
1239 const TypeInteger* hi = phase->type(limit)->isa_integer(l->bt());
1240 const TypeInteger* stride_t = phase->type(stride)->isa_integer(l->bt());
1241 if (lo != nullptr && hi != nullptr && stride_t != nullptr) { // Dying loops might have TOP here
1242 assert(stride_t->is_con(), "bad stride type");
1243 BoolTest::mask bt = l->loopexit()->test_trip();
1244 // If the loop exit condition is "not equal", the condition
1245 // would not trigger if init > limit (if stride > 0) or if
1246 // init < limit if (stride > 0) so we can't deduce bounds
1247 // for the iv from the exit condition.
1248 if (bt != BoolTest::ne) {
1249 jlong stride_con = stride_t->get_con_as_long(l->bt());
1250 if (stride_con < 0) { // Down-counter loop
1251 swap(lo, hi);
1252 jlong iv_range_lower_limit = lo->lo_as_long();
1253 // Prevent overflow when adding one below
1254 if (iv_range_lower_limit < max_signed_integer(l->bt())) {
1255 // The loop exit condition is: iv + stride > limit (iv is this Phi). So the loop iterates until
1256 // iv + stride <= limit
1257 // We know that: limit >= lo->lo_as_long() and stride <= -1
1258 // So when the loop exits, iv has to be at most lo->lo_as_long() + 1
1259 iv_range_lower_limit += 1; // lo is after decrement
1260 // Exact bounds for the phi can be computed when ABS(stride) greater than 1 if bounds are constant.
1261 if (lo->is_con() && hi->is_con() && hi->lo_as_long() > lo->hi_as_long() && stride_con != -1) {
1262 julong uhi = static_cast<julong>(hi->lo_as_long());
1263 julong ulo = static_cast<julong>(lo->hi_as_long());
1264 julong diff = ((uhi - ulo - 1) / (-stride_con)) * (-stride_con);
1265 julong ufirst = hi->lo_as_long() - diff;
1266 iv_range_lower_limit = reinterpret_cast<jlong &>(ufirst);
1267 assert(iv_range_lower_limit >= lo->lo_as_long() + 1, "should end up with narrower range");
1268 }
1269 }
1270 return TypeInteger::make(MIN2(iv_range_lower_limit, hi->lo_as_long()), hi->hi_as_long(), 3, l->bt())->filter_speculative(_type);
1271 } else if (stride_con >= 0) {
1272 jlong iv_range_upper_limit = hi->hi_as_long();
1273 // Prevent overflow when subtracting one below
1274 if (iv_range_upper_limit > min_signed_integer(l->bt())) {
1275 // The loop exit condition is: iv + stride < limit (iv is this Phi). So the loop iterates until
1276 // iv + stride >= limit
1277 // We know that: limit <= hi->hi_as_long() and stride >= 1
1278 // So when the loop exits, iv has to be at most hi->hi_as_long() - 1
1279 iv_range_upper_limit -= 1;
1280 // Exact bounds for the phi can be computed when ABS(stride) greater than 1 if bounds are constant.
1281 if (lo->is_con() && hi->is_con() && hi->lo_as_long() > lo->hi_as_long() && stride_con != 1) {
1282 julong uhi = static_cast<julong>(hi->lo_as_long());
1283 julong ulo = static_cast<julong>(lo->hi_as_long());
1284 julong diff = ((uhi - ulo - 1) / stride_con) * stride_con;
1285 julong ulast = lo->hi_as_long() + diff;
1286 iv_range_upper_limit = reinterpret_cast<jlong &>(ulast);
1287 assert(iv_range_upper_limit <= hi->hi_as_long() - 1, "should end up with narrower range");
1288 }
1289 }
1290 return TypeInteger::make(lo->lo_as_long(), MAX2(lo->hi_as_long(), iv_range_upper_limit), 3, l->bt())->filter_speculative(_type);
1291 }
1292 }
1293 }
1294 }
1295 } else if (l->in(LoopNode::LoopBackControl) != nullptr &&
1296 in(LoopNode::EntryControl) != nullptr &&
1297 phase->type(l->in(LoopNode::LoopBackControl)) == Type::TOP) {
1298 // During CCP, if we saturate the type of a counted loop's Phi
1299 // before the special code for counted loop above has a chance
1300 // to run (that is as long as the type of the backedge's control
1301 // is top), we might end up with non monotonic types
1302 return phase->type(in(LoopNode::EntryControl))->filter_speculative(_type);
1303 }
1304 }
1305
1306 // Default case: merge all inputs
1307 const Type *t = Type::TOP; // Merged type starting value
1308 for (uint i = 1; i < req(); ++i) {// For all paths in
1309 // Reachable control path?
1310 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
1311 const Type* ti = phase->type(in(i));
1312 t = t->meet_speculative(ti);
1313 }
1314 }
1315
1316 // The worst-case type (from ciTypeFlow) should be consistent with "t".
1317 // That is, we expect that "t->higher_equal(_type)" holds true.
1318 // There are various exceptions:
1319 // - Inputs which are phis might in fact be widened unnecessarily.
1320 // For example, an input might be a widened int while the phi is a short.
1321 // - Inputs might be BotPtrs but this phi is dependent on a null check,
1322 // and postCCP has removed the cast which encodes the result of the check.
1323 // - The type of this phi is an interface, and the inputs are classes.
1324 // - Value calls on inputs might produce fuzzy results.
1325 // (Occurrences of this case suggest improvements to Value methods.)
1326 //
1327 // It is not possible to see Type::BOTTOM values as phi inputs,
1328 // because the ciTypeFlow pre-pass produces verifier-quality types.
1329 const Type* ft = t->filter_speculative(_type); // Worst case type
1330
1331 #ifdef ASSERT
1332 // The following logic has been moved into TypeOopPtr::filter.
1333 const Type* jt = t->join_speculative(_type);
1334 if (jt->empty()) { // Emptied out???
1335 // Otherwise it's something stupid like non-overlapping int ranges
1336 // found on dying counted loops.
1337 assert(ft == Type::TOP, ""); // Canonical empty value
1338 }
1339
1340 else {
1341
1342 if (jt != ft && jt->base() == ft->base()) {
1343 if (jt->isa_int() &&
1344 jt->is_int()->_lo == ft->is_int()->_lo &&
1345 jt->is_int()->_hi == ft->is_int()->_hi)
1346 jt = ft;
1347 if (jt->isa_long() &&
1348 jt->is_long()->_lo == ft->is_long()->_lo &&
1349 jt->is_long()->_hi == ft->is_long()->_hi)
1350 jt = ft;
1351 }
1352 if (jt != ft) {
1353 tty->print("merge type: "); t->dump(); tty->cr();
1354 tty->print("kill type: "); _type->dump(); tty->cr();
1355 tty->print("join type: "); jt->dump(); tty->cr();
1356 tty->print("filter type: "); ft->dump(); tty->cr();
1357 }
1358 assert(jt == ft, "");
1359 }
1360 #endif //ASSERT
1361
1362 // Deal with conversion problems found in data loops.
1363 ft = phase->saturate_and_maybe_push_to_igvn_worklist(this, ft);
1364 return ft;
1365 }
1366
1367 // Does this Phi represent a simple well-shaped diamond merge? Return the
1368 // index of the true path or 0 otherwise.
1369 int PhiNode::is_diamond_phi() const {
1370 Node* region = in(0);
1371 assert(region != nullptr && region->is_Region(), "phi must have region");
1372 if (!region->as_Region()->is_diamond()) {
1373 return 0;
1374 }
1375
1376 if (region->in(1)->is_IfTrue()) {
1377 assert(region->in(2)->is_IfFalse(), "bad If");
1378 return 1;
1379 } else {
1380 // Flipped projections.
1381 assert(region->in(2)->is_IfTrue(), "bad If");
1382 return 2;
1383 }
1384 }
1385
1386 // Do the following transformation if we find the corresponding graph shape, remove the involved memory phi and return
1387 // true. Otherwise, return false if the transformation cannot be applied.
1388 //
1389 // If If
1390 // / \ / \
1391 // IfFalse IfTrue /- Some Node IfFalse IfTrue
1392 // \ / / / \ / Some Node
1393 // Region / /-MergeMem ===> Region |
1394 // / \---Phi | MergeMem
1395 // [other phis] \ [other phis] |
1396 // use use
1397 bool PhiNode::try_clean_memory_phi(PhaseIterGVN* igvn) {
1398 if (_type != Type::MEMORY) {
1399 return false;
1400 }
1401 assert(is_diamond_phi() > 0, "sanity");
1402 assert(req() == 3, "same as region");
1403 const Node* region = in(0);
1404 for (uint i = 1; i < 3; i++) {
1405 Node* phi_input = in(i);
1406 if (phi_input != nullptr && phi_input->is_MergeMem() && region->in(i)->outcnt() == 1) {
1407 // Nothing is control-dependent on path #i except the region itself.
1408 MergeMemNode* merge_mem = phi_input->as_MergeMem();
1409 uint j = 3 - i;
1410 Node* other_phi_input = in(j);
1411 if (other_phi_input != nullptr && other_phi_input == merge_mem->base_memory()) {
1412 // merge_mem is a successor memory to other_phi_input, and is not pinned inside the diamond, so push it out.
1413 // This will allow the diamond to collapse completely if there are no other phis left.
1414 igvn->replace_node(this, merge_mem);
1415 return true;
1416 }
1417 }
1418 }
1419 return false;
1420 }
1421
1422 //----------------------------check_cmove_id-----------------------------------
1423 // Check for CMove'ing a constant after comparing against the constant.
1424 // Happens all the time now, since if we compare equality vs a constant in
1425 // the parser, we "know" the variable is constant on one path and we force
1426 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
1427 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more
1428 // general in that we don't need constants. Since CMove's are only inserted
1429 // in very special circumstances, we do it here on generic Phi's.
1430 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
1431 assert(true_path !=0, "only diamond shape graph expected");
1432
1433 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1434 // phi->region->if_proj->ifnode->bool->cmp
1435 Node* region = in(0);
1436 Node* iff = region->in(1)->in(0);
1437 BoolNode* b = iff->in(1)->as_Bool();
1438 Node* cmp = b->in(1);
1439 Node* tval = in(true_path);
1440 Node* fval = in(3-true_path);
1441 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
1442 if (id == nullptr)
1443 return nullptr;
1444
1445 // Either value might be a cast that depends on a branch of 'iff'.
1446 // Since the 'id' value will float free of the diamond, either
1447 // decast or return failure.
1448 Node* ctl = id->in(0);
1449 if (ctl != nullptr && ctl->in(0) == iff) {
1450 if (id->is_ConstraintCast()) {
1451 return id->in(1);
1452 } else {
1453 // Don't know how to disentangle this value.
1454 return nullptr;
1455 }
1456 }
1457
1458 return id;
1459 }
1460
1461 //------------------------------Identity---------------------------------------
1462 // Check for Region being Identity.
1463 Node* PhiNode::Identity(PhaseGVN* phase) {
1464 if (must_wait_for_region_in_irreducible_loop(phase)) {
1465 return this;
1466 }
1467 // Check for no merging going on
1468 // (There used to be special-case code here when this->region->is_Loop.
1469 // It would check for a tributary phi on the backedge that the main phi
1470 // trivially, perhaps with a single cast. The unique_input method
1471 // does all this and more, by reducing such tributaries to 'this'.)
1472 Node* uin = unique_input(phase, false);
1473 if (uin != nullptr) {
1474 return uin;
1475 }
1476
1477 int true_path = is_diamond_phi();
1478 // Delay CMove'ing identity if Ideal has not had the chance to handle unsafe cases, yet.
1479 if (true_path != 0 && !(phase->is_IterGVN() && wait_for_region_igvn(phase))) {
1480 Node* id = is_cmove_id(phase, true_path);
1481 if (id != nullptr) {
1482 return id;
1483 }
1484 }
1485
1486 // Looking for phis with identical inputs. If we find one that has
1487 // type TypePtr::BOTTOM, replace the current phi with the bottom phi.
1488 if (phase->is_IterGVN() && type() == Type::MEMORY && adr_type() !=
1489 TypePtr::BOTTOM && !adr_type()->is_known_instance()) {
1490 uint phi_len = req();
1491 Node* phi_reg = region();
1492 for (DUIterator_Fast imax, i = phi_reg->fast_outs(imax); i < imax; i++) {
1493 Node* u = phi_reg->fast_out(i);
1494 if (u->is_Phi() && u->as_Phi()->type() == Type::MEMORY &&
1495 u->adr_type() == TypePtr::BOTTOM && u->in(0) == phi_reg &&
1496 u->req() == phi_len) {
1497 for (uint j = 1; j < phi_len; j++) {
1498 if (in(j) != u->in(j)) {
1499 u = nullptr;
1500 break;
1501 }
1502 }
1503 if (u != nullptr) {
1504 return u;
1505 }
1506 }
1507 }
1508 }
1509
1510 return this; // No identity
1511 }
1512
1513 //-----------------------------unique_input------------------------------------
1514 // Find the unique value, discounting top, self-loops, and casts.
1515 // Return top if there are no inputs, and self if there are multiple.
1516 Node* PhiNode::unique_input(PhaseValues* phase, bool uncast) {
1517 // 1) One unique direct input,
1518 // or if uncast is true:
1519 // 2) some of the inputs have an intervening ConstraintCast
1520 // 3) an input is a self loop
1521 //
1522 // 1) input or 2) input or 3) input __
1523 // / \ / \ \ / \
1524 // \ / | cast phi cast
1525 // phi \ / / \ /
1526 // phi / --
1527
1528 Node* r = in(0); // RegionNode
1529 Node* input = nullptr; // The unique direct input (maybe uncasted = ConstraintCasts removed)
1530
1531 for (uint i = 1, cnt = req(); i < cnt; ++i) {
1532 Node* rc = r->in(i);
1533 if (rc == nullptr || phase->type(rc) == Type::TOP)
1534 continue; // ignore unreachable control path
1535 Node* n = in(i);
1536 if (n == nullptr)
1537 continue;
1538 Node* un = n;
1539 if (uncast) {
1540 #ifdef ASSERT
1541 Node* m = un->uncast();
1542 #endif
1543 while (un != nullptr && un->req() == 2 && un->is_ConstraintCast()) {
1544 Node* next = un->in(1);
1545 if (phase->type(next)->isa_rawptr() && phase->type(un)->isa_oopptr()) {
1546 // risk exposing raw ptr at safepoint
1547 break;
1548 }
1549 un = next;
1550 }
1551 assert(m == un || un->in(1) == m, "Only expected at CheckCastPP from allocation");
1552 }
1553 if (un == nullptr || un == this || phase->type(un) == Type::TOP) {
1554 continue; // ignore if top, or in(i) and "this" are in a data cycle
1555 }
1556 // Check for a unique input (maybe uncasted)
1557 if (input == nullptr) {
1558 input = un;
1559 } else if (input != un) {
1560 input = NodeSentinel; // no unique input
1561 }
1562 }
1563 if (input == nullptr) {
1564 return phase->C->top(); // no inputs
1565 }
1566
1567 if (input != NodeSentinel) {
1568 return input; // one unique direct input
1569 }
1570
1571 // Nothing.
1572 return nullptr;
1573 }
1574
1575 //------------------------------is_x2logic-------------------------------------
1576 // Check for simple convert-to-boolean pattern
1577 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
1578 // Convert Phi to an ConvIB.
1579 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
1580 assert(true_path !=0, "only diamond shape graph expected");
1581
1582 // If we're late in the optimization process, we may have already expanded Conv2B nodes
1583 if (phase->C->post_loop_opts_phase() && !Matcher::match_rule_supported(Op_Conv2B)) {
1584 return nullptr;
1585 }
1586
1587 // Convert the true/false index into an expected 0/1 return.
1588 // Map 2->0 and 1->1.
1589 int flipped = 2-true_path;
1590
1591 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1592 // phi->region->if_proj->ifnode->bool->cmp
1593 Node *region = phi->in(0);
1594 Node *iff = region->in(1)->in(0);
1595 BoolNode *b = (BoolNode*)iff->in(1);
1596 const CmpNode *cmp = (CmpNode*)b->in(1);
1597
1598 Node *zero = phi->in(1);
1599 Node *one = phi->in(2);
1600 const Type *tzero = phase->type( zero );
1601 const Type *tone = phase->type( one );
1602
1603 // Check for compare vs 0
1604 const Type *tcmp = phase->type(cmp->in(2));
1605 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
1606 // Allow cmp-vs-1 if the other input is bounded by 0-1
1607 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
1608 return nullptr;
1609 flipped = 1-flipped; // Test is vs 1 instead of 0!
1610 }
1611
1612 // Check for setting zero/one opposite expected
1613 if( tzero == TypeInt::ZERO ) {
1614 if( tone == TypeInt::ONE ) {
1615 } else return nullptr;
1616 } else if( tzero == TypeInt::ONE ) {
1617 if( tone == TypeInt::ZERO ) {
1618 flipped = 1-flipped;
1619 } else return nullptr;
1620 } else return nullptr;
1621
1622 // Check for boolean test backwards
1623 if( b->_test._test == BoolTest::ne ) {
1624 } else if( b->_test._test == BoolTest::eq ) {
1625 flipped = 1-flipped;
1626 } else return nullptr;
1627
1628 // Build int->bool conversion
1629 Node* n = new Conv2BNode(cmp->in(1));
1630 if (flipped) {
1631 n = new XorINode(phase->transform(n), phase->intcon(1));
1632 }
1633
1634 return n;
1635 }
1636
1637 //------------------------------is_cond_add------------------------------------
1638 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;"
1639 // To be profitable the control flow has to disappear; there can be no other
1640 // values merging here. We replace the test-and-branch with:
1641 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by
1642 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
1643 // Then convert Y to 0-or-Y and finally add.
1644 // This is a key transform for SpecJava _201_compress.
1645 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
1646 assert(true_path !=0, "only diamond shape graph expected");
1647
1648 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1649 // phi->region->if_proj->ifnode->bool->cmp
1650 RegionNode *region = (RegionNode*)phi->in(0);
1651 Node *iff = region->in(1)->in(0);
1652 BoolNode* b = iff->in(1)->as_Bool();
1653 const CmpNode *cmp = (CmpNode*)b->in(1);
1654
1655 // Make sure only merging this one phi here
1656 if (region->has_unique_phi() != phi) return nullptr;
1657
1658 // Make sure each arm of the diamond has exactly one output, which we assume
1659 // is the region. Otherwise, the control flow won't disappear.
1660 if (region->in(1)->outcnt() != 1) return nullptr;
1661 if (region->in(2)->outcnt() != 1) return nullptr;
1662
1663 // Check for "(P < Q)" of type signed int
1664 if (b->_test._test != BoolTest::lt) return nullptr;
1665 if (cmp->Opcode() != Op_CmpI) return nullptr;
1666
1667 Node *p = cmp->in(1);
1668 Node *q = cmp->in(2);
1669 Node *n1 = phi->in( true_path);
1670 Node *n2 = phi->in(3-true_path);
1671
1672 int op = n1->Opcode();
1673 if( op != Op_AddI // Need zero as additive identity
1674 /*&&op != Op_SubI &&
1675 op != Op_AddP &&
1676 op != Op_XorI &&
1677 op != Op_OrI*/ )
1678 return nullptr;
1679
1680 Node *x = n2;
1681 Node *y = nullptr;
1682 if( x == n1->in(1) ) {
1683 y = n1->in(2);
1684 } else if( x == n1->in(2) ) {
1685 y = n1->in(1);
1686 } else return nullptr;
1687
1688 // Not so profitable if compare and add are constants
1689 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
1690 return nullptr;
1691
1692 Node *cmplt = phase->transform( new CmpLTMaskNode(p,q) );
1693 Node *j_and = phase->transform( new AndINode(cmplt,y) );
1694 return new AddINode(j_and,x);
1695 }
1696
1697 //------------------------------is_absolute------------------------------------
1698 // Check for absolute value.
1699 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
1700 assert(true_path !=0, "only diamond shape graph expected");
1701
1702 int cmp_zero_idx = 0; // Index of compare input where to look for zero
1703 int phi_x_idx = 0; // Index of phi input where to find naked x
1704
1705 // ABS ends with the merge of 2 control flow paths.
1706 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
1707 int false_path = 3 - true_path;
1708
1709 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1710 // phi->region->if_proj->ifnode->bool->cmp
1711 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
1712 Node *cmp = bol->in(1);
1713
1714 // Check bool sense
1715 if (cmp->Opcode() == Op_CmpF || cmp->Opcode() == Op_CmpD) {
1716 switch (bol->_test._test) {
1717 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break;
1718 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1719 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1720 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
1721 default: return nullptr; break;
1722 }
1723 } else if (cmp->Opcode() == Op_CmpI || cmp->Opcode() == Op_CmpL) {
1724 switch (bol->_test._test) {
1725 case BoolTest::lt:
1726 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1727 case BoolTest::gt:
1728 case BoolTest::ge: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1729 default: return nullptr; break;
1730 }
1731 }
1732
1733 // Test is next
1734 const Type *tzero = nullptr;
1735 switch (cmp->Opcode()) {
1736 case Op_CmpI: tzero = TypeInt::ZERO; break; // Integer ABS
1737 case Op_CmpL: tzero = TypeLong::ZERO; break; // Long ABS
1738 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS
1739 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS
1740 default: return nullptr;
1741 }
1742
1743 // Find zero input of compare; the other input is being abs'd
1744 Node *x = nullptr;
1745 bool flip = false;
1746 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
1747 x = cmp->in(3 - cmp_zero_idx);
1748 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
1749 // The test is inverted, we should invert the result...
1750 x = cmp->in(cmp_zero_idx);
1751 flip = true;
1752 } else {
1753 return nullptr;
1754 }
1755
1756 // Next get the 2 pieces being selected, one is the original value
1757 // and the other is the negated value.
1758 if( phi_root->in(phi_x_idx) != x ) return nullptr;
1759
1760 // Check other phi input for subtract node
1761 Node *sub = phi_root->in(3 - phi_x_idx);
1762
1763 bool is_sub = sub->Opcode() == Op_SubF || sub->Opcode() == Op_SubD ||
1764 sub->Opcode() == Op_SubI || sub->Opcode() == Op_SubL;
1765
1766 // Allow only Sub(0,X) and fail out for all others; Neg is not OK
1767 if (!is_sub || phase->type(sub->in(1)) != tzero || sub->in(2) != x) return nullptr;
1768
1769 if (tzero == TypeF::ZERO) {
1770 x = new AbsFNode(x);
1771 if (flip) {
1772 x = new SubFNode(sub->in(1), phase->transform(x));
1773 }
1774 } else if (tzero == TypeD::ZERO) {
1775 x = new AbsDNode(x);
1776 if (flip) {
1777 x = new SubDNode(sub->in(1), phase->transform(x));
1778 }
1779 } else if (tzero == TypeInt::ZERO && Matcher::match_rule_supported(Op_AbsI)) {
1780 x = new AbsINode(x);
1781 if (flip) {
1782 x = new SubINode(sub->in(1), phase->transform(x));
1783 }
1784 } else if (tzero == TypeLong::ZERO && Matcher::match_rule_supported(Op_AbsL)) {
1785 x = new AbsLNode(x);
1786 if (flip) {
1787 x = new SubLNode(sub->in(1), phase->transform(x));
1788 }
1789 } else return nullptr;
1790
1791 return x;
1792 }
1793
1794 //------------------------------split_once-------------------------------------
1795 // Helper for split_flow_path
1796 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
1797 igvn->hash_delete(n); // Remove from hash before hacking edges
1798
1799 uint j = 1;
1800 for (uint i = phi->req()-1; i > 0; i--) {
1801 if (phi->in(i) == val) { // Found a path with val?
1802 // Add to NEW Region/Phi, no DU info
1803 newn->set_req( j++, n->in(i) );
1804 // Remove from OLD Region/Phi
1805 n->del_req(i);
1806 }
1807 }
1808
1809 // Register the new node but do not transform it. Cannot transform until the
1810 // entire Region/Phi conglomerate has been hacked as a single huge transform.
1811 igvn->register_new_node_with_optimizer( newn );
1812
1813 // Now I can point to the new node.
1814 n->add_req(newn);
1815 igvn->_worklist.push(n);
1816 }
1817
1818 //------------------------------split_flow_path--------------------------------
1819 // Check for merging identical values and split flow paths
1820 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) {
1821 // This optimization tries to find two or more inputs of phi with the same constant value
1822 // It then splits them into a separate Phi, and according Region. If this is a loop-entry,
1823 // and the loop entry has multiple fall-in edges, and some of those fall-in edges have that
1824 // constant, and others not, we may split the fall-in edges into separate Phi's, and create
1825 // an irreducible loop. For reducible loops, this never seems to happen, as the multiple
1826 // fall-in edges are already merged before the loop head during parsing. But with irreducible
1827 // loops present the order or merging during parsing can sometimes prevent this.
1828 if (phase->C->has_irreducible_loop()) {
1829 // Avoid this optimization if any irreducible loops are present. Else we may create
1830 // an irreducible loop that we do not detect.
1831 return nullptr;
1832 }
1833 BasicType bt = phi->type()->basic_type();
1834 if( bt == T_ILLEGAL || type2size[bt] <= 0 )
1835 return nullptr; // Bail out on funny non-value stuff
1836 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a
1837 return nullptr; // third unequal input to be worth doing
1838
1839 // Scan for a constant
1840 uint i;
1841 for( i = 1; i < phi->req()-1; i++ ) {
1842 Node *n = phi->in(i);
1843 if( !n ) return nullptr;
1844 if( phase->type(n) == Type::TOP ) return nullptr;
1845 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN || n->Opcode() == Op_ConNKlass )
1846 break;
1847 }
1848 if( i >= phi->req() ) // Only split for constants
1849 return nullptr;
1850
1851 Node *val = phi->in(i); // Constant to split for
1852 uint hit = 0; // Number of times it occurs
1853 Node *r = phi->region();
1854
1855 for( ; i < phi->req(); i++ ){ // Count occurrences of constant
1856 Node *n = phi->in(i);
1857 if( !n ) return nullptr;
1858 if( phase->type(n) == Type::TOP ) return nullptr;
1859 if( phi->in(i) == val ) {
1860 hit++;
1861 if (Node::may_be_loop_entry(r->in(i))) {
1862 return nullptr; // don't split loop entry path
1863 }
1864 }
1865 }
1866
1867 if( hit <= 1 || // Make sure we find 2 or more
1868 hit == phi->req()-1 ) // and not ALL the same value
1869 return nullptr;
1870
1871 // Now start splitting out the flow paths that merge the same value.
1872 // Split first the RegionNode.
1873 PhaseIterGVN *igvn = phase->is_IterGVN();
1874 RegionNode *newr = new RegionNode(hit+1);
1875 split_once(igvn, phi, val, r, newr);
1876
1877 // Now split all other Phis than this one
1878 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) {
1879 Node* phi2 = r->fast_out(k);
1880 if( phi2->is_Phi() && phi2->as_Phi() != phi ) {
1881 PhiNode *newphi = PhiNode::make_blank(newr, phi2);
1882 split_once(igvn, phi, val, phi2, newphi);
1883 }
1884 }
1885
1886 // Clean up this guy
1887 igvn->hash_delete(phi);
1888 for( i = phi->req()-1; i > 0; i-- ) {
1889 if( phi->in(i) == val ) {
1890 phi->del_req(i);
1891 }
1892 }
1893 phi->add_req(val);
1894
1895 return phi;
1896 }
1897
1898 //=============================================================================
1899 //------------------------------simple_data_loop_check-------------------------
1900 // Try to determining if the phi node in a simple safe/unsafe data loop.
1901 // Returns:
1902 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
1903 // Safe - safe case when the phi and it's inputs reference only safe data
1904 // nodes;
1905 // Unsafe - the phi and it's inputs reference unsafe data nodes but there
1906 // is no reference back to the phi - need a graph walk
1907 // to determine if it is in a loop;
1908 // UnsafeLoop - unsafe case when the phi references itself directly or through
1909 // unsafe data node.
1910 // Note: a safe data node is a node which could/never reference itself during
1911 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP.
1912 // I mark Phi nodes as safe node not only because they can reference itself
1913 // but also to prevent mistaking the fallthrough case inside an outer loop
1914 // as dead loop when the phi references itself through an other phi.
1915 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const {
1916 // It is unsafe loop if the phi node references itself directly.
1917 if (in == (Node*)this)
1918 return UnsafeLoop; // Unsafe loop
1919 // Unsafe loop if the phi node references itself through an unsafe data node.
1920 // Exclude cases with null inputs or data nodes which could reference
1921 // itself (safe for dead loops).
1922 if (in != nullptr && !in->is_dead_loop_safe()) {
1923 // Check inputs of phi's inputs also.
1924 // It is much less expensive then full graph walk.
1925 uint cnt = in->req();
1926 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1;
1927 for (; i < cnt; ++i) {
1928 Node* m = in->in(i);
1929 if (m == (Node*)this)
1930 return UnsafeLoop; // Unsafe loop
1931 if (m != nullptr && !m->is_dead_loop_safe()) {
1932 // Check the most common case (about 30% of all cases):
1933 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con).
1934 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : nullptr;
1935 if (m1 == (Node*)this)
1936 return UnsafeLoop; // Unsafe loop
1937 if (m1 != nullptr && m1 == m->in(2) &&
1938 m1->is_dead_loop_safe() && m->in(3)->is_Con()) {
1939 continue; // Safe case
1940 }
1941 // The phi references an unsafe node - need full analysis.
1942 return Unsafe;
1943 }
1944 }
1945 }
1946 return Safe; // Safe case - we can optimize the phi node.
1947 }
1948
1949 //------------------------------is_unsafe_data_reference-----------------------
1950 // If phi can be reached through the data input - it is data loop.
1951 bool PhiNode::is_unsafe_data_reference(Node *in) const {
1952 assert(req() > 1, "");
1953 // First, check simple cases when phi references itself directly or
1954 // through an other node.
1955 LoopSafety safety = simple_data_loop_check(in);
1956 if (safety == UnsafeLoop)
1957 return true; // phi references itself - unsafe loop
1958 else if (safety == Safe)
1959 return false; // Safe case - phi could be replaced with the unique input.
1960
1961 // Unsafe case when we should go through data graph to determine
1962 // if the phi references itself.
1963
1964 ResourceMark rm;
1965
1966 Node_List nstack;
1967 VectorSet visited;
1968
1969 nstack.push(in); // Start with unique input.
1970 visited.set(in->_idx);
1971 while (nstack.size() != 0) {
1972 Node* n = nstack.pop();
1973 uint cnt = n->req();
1974 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1;
1975 for (; i < cnt; i++) {
1976 Node* m = n->in(i);
1977 if (m == (Node*)this) {
1978 return true; // Data loop
1979 }
1980 if (m != nullptr && !m->is_dead_loop_safe()) { // Only look for unsafe cases.
1981 if (!visited.test_set(m->_idx))
1982 nstack.push(m);
1983 }
1984 }
1985 }
1986 return false; // The phi is not reachable from its inputs
1987 }
1988
1989 // Is this Phi's region or some inputs to the region enqueued for IGVN
1990 // and so could cause the region to be optimized out?
1991 bool PhiNode::wait_for_region_igvn(PhaseGVN* phase) {
1992 PhaseIterGVN* igvn = phase->is_IterGVN();
1993 Unique_Node_List& worklist = igvn->_worklist;
1994 bool delay = false;
1995 Node* r = in(0);
1996 for (uint j = 1; j < req(); j++) {
1997 Node* rc = r->in(j);
1998 Node* n = in(j);
1999
2000 if (rc == nullptr || !rc->is_Proj()) { continue; }
2001 if (worklist.member(rc)) {
2002 delay = true;
2003 break;
2004 }
2005
2006 if (rc->in(0) == nullptr || !rc->in(0)->is_If()) { continue; }
2007 if (worklist.member(rc->in(0))) {
2008 delay = true;
2009 break;
2010 }
2011
2012 if (rc->in(0)->in(1) == nullptr || !rc->in(0)->in(1)->is_Bool()) { continue; }
2013 if (worklist.member(rc->in(0)->in(1))) {
2014 delay = true;
2015 break;
2016 }
2017
2018 if (rc->in(0)->in(1)->in(1) == nullptr || !rc->in(0)->in(1)->in(1)->is_Cmp()) { continue; }
2019 if (worklist.member(rc->in(0)->in(1)->in(1))) {
2020 delay = true;
2021 break;
2022 }
2023 }
2024
2025 if (delay) {
2026 worklist.push(this);
2027 }
2028 return delay;
2029 }
2030
2031 // Push inline type input nodes (and null) down through the phi recursively (can handle data loops).
2032 InlineTypeNode* PhiNode::push_inline_types_through(PhaseGVN* phase, bool can_reshape, ciInlineKlass* vk) {
2033 InlineTypeNode* vt = InlineTypeNode::make_null(*phase, vk)->clone_with_phis(phase, in(0), !_type->maybe_null());
2034 if (can_reshape) {
2035 // Replace phi right away to be able to use the inline
2036 // type node when reaching the phi again through data loops.
2037 PhaseIterGVN* igvn = phase->is_IterGVN();
2038 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
2039 Node* u = fast_out(i);
2040 igvn->rehash_node_delayed(u);
2041 imax -= u->replace_edge(this, vt);
2042 --i;
2043 }
2044 igvn->rehash_node_delayed(this);
2045 assert(outcnt() == 0, "should be dead now");
2046 }
2047 ResourceMark rm;
2048 Node_List casts;
2049 for (uint i = 1; i < req(); ++i) {
2050 Node* n = in(i);
2051 while (n->is_ConstraintCast()) {
2052 casts.push(n);
2053 n = n->in(1);
2054 }
2055 if (phase->type(n)->is_zero_type()) {
2056 n = InlineTypeNode::make_null(*phase, vk);
2057 } else if (n->is_Phi()) {
2058 assert(can_reshape, "can only handle phis during IGVN");
2059 n = phase->transform(n->as_Phi()->push_inline_types_through(phase, can_reshape, vk));
2060 }
2061 while (casts.size() != 0) {
2062 // Push the cast(s) through the InlineTypeNode
2063 Node* cast = casts.pop()->clone();
2064 cast->set_req_X(1, n->as_InlineType()->get_oop(), phase);
2065 n = n->clone();
2066 n->as_InlineType()->set_oop(phase->transform(cast));
2067 n = phase->transform(n);
2068 }
2069 bool transform = !can_reshape && (i == (req()-1)); // Transform phis on last merge
2070 vt->merge_with(phase, n->as_InlineType(), i, transform);
2071 }
2072 return vt;
2073 }
2074
2075 // If the Phi's Region is in an irreducible loop, and the Region
2076 // has had an input removed, but not yet transformed, it could be
2077 // that the Region (and this Phi) are not reachable from Root.
2078 // If we allow the Phi to collapse before the Region, this may lead
2079 // to dead-loop data. Wait for the Region to check for reachability,
2080 // and potentially remove the dead code.
2081 bool PhiNode::must_wait_for_region_in_irreducible_loop(PhaseGVN* phase) const {
2082 RegionNode* region = in(0)->as_Region();
2083 if (region->loop_status() == RegionNode::LoopStatus::MaybeIrreducibleEntry) {
2084 Node* top = phase->C->top();
2085 for (uint j = 1; j < req(); j++) {
2086 Node* rc = region->in(j); // for each control input
2087 if (rc == nullptr || phase->type(rc) == Type::TOP) {
2088 // Region is missing a control input
2089 Node* n = in(j);
2090 if (n != nullptr && n != top) {
2091 // Phi still has its input, so region just lost its input
2092 return true;
2093 }
2094 }
2095 }
2096 }
2097 return false;
2098 }
2099
2100 //------------------------------Ideal------------------------------------------
2101 // Return a node which is more "ideal" than the current node. Must preserve
2102 // the CFG, but we can still strip out dead paths.
2103 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2104 Node *r = in(0); // RegionNode
2105 assert(r != nullptr && r->is_Region(), "this phi must have a region");
2106 assert(r->in(0) == nullptr || !r->in(0)->is_Root(), "not a specially hidden merge");
2107
2108 // Note: During parsing, phis are often transformed before their regions.
2109 // This means we have to use type_or_null to defend against untyped regions.
2110 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
2111 return nullptr; // No change
2112
2113 Node *top = phase->C->top();
2114 bool new_phi = (outcnt() == 0); // transforming new Phi
2115 // No change for igvn if new phi is not hooked
2116 if (new_phi && can_reshape)
2117 return nullptr;
2118
2119 if (must_wait_for_region_in_irreducible_loop(phase)) {
2120 return nullptr;
2121 }
2122
2123 // The are 2 situations when only one valid phi's input is left
2124 // (in addition to Region input).
2125 // One: region is not loop - replace phi with this input.
2126 // Two: region is loop - replace phi with top since this data path is dead
2127 // and we need to break the dead data loop.
2128 Node* progress = nullptr; // Record if any progress made
2129 for( uint j = 1; j < req(); ++j ){ // For all paths in
2130 // Check unreachable control paths
2131 Node* rc = r->in(j);
2132 Node* n = in(j); // Get the input
2133 if (rc == nullptr || phase->type(rc) == Type::TOP) {
2134 if (n != top) { // Not already top?
2135 PhaseIterGVN *igvn = phase->is_IterGVN();
2136 if (can_reshape && igvn != nullptr) {
2137 igvn->_worklist.push(r);
2138 }
2139 // Nuke it down
2140 set_req_X(j, top, phase);
2141 progress = this; // Record progress
2142 }
2143 }
2144 }
2145
2146 if (can_reshape && outcnt() == 0) {
2147 // set_req() above may kill outputs if Phi is referenced
2148 // only by itself on the dead (top) control path.
2149 return top;
2150 }
2151
2152 bool uncasted = false;
2153 Node* uin = unique_input(phase, false);
2154 if (uin == nullptr && can_reshape &&
2155 // If there is a chance that the region can be optimized out do
2156 // not add a cast node that we can't remove yet.
2157 !wait_for_region_igvn(phase)) {
2158 uncasted = true;
2159 uin = unique_input(phase, true);
2160 }
2161 if (uin == top) { // Simplest case: no alive inputs.
2162 if (can_reshape) // IGVN transformation
2163 return top;
2164 else
2165 return nullptr; // Identity will return TOP
2166 } else if (uin != nullptr) {
2167 // Only one not-null unique input path is left.
2168 // Determine if this input is backedge of a loop.
2169 // (Skip new phis which have no uses and dead regions).
2170 if (outcnt() > 0 && r->in(0) != nullptr) {
2171 if (is_data_loop(r->as_Region(), uin, phase)) {
2172 // Break this data loop to avoid creation of a dead loop.
2173 if (can_reshape) {
2174 return top;
2175 } else {
2176 // We can't return top if we are in Parse phase - cut inputs only
2177 // let Identity to handle the case.
2178 replace_edge(uin, top, phase);
2179 return nullptr;
2180 }
2181 }
2182 }
2183
2184 if (uncasted) {
2185 // Add cast nodes between the phi to be removed and its unique input.
2186 // Wait until after parsing for the type information to propagate from the casts.
2187 assert(can_reshape, "Invalid during parsing");
2188 const Type* phi_type = bottom_type();
2189 // Add casts to carry the control dependency of the Phi that is
2190 // going away
2191 Node* cast = nullptr;
2192 if (phi_type->isa_ptr()) {
2193 const Type* uin_type = phase->type(uin);
2194 if (!phi_type->isa_oopptr() && !uin_type->isa_oopptr()) {
2195 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, ConstraintCastNode::StrongDependency);
2196 } else {
2197 // Use a CastPP for a cast to not null and a CheckCastPP for
2198 // a cast to a new klass (and both if both null-ness and
2199 // klass change).
2200
2201 // If the type of phi is not null but the type of uin may be
2202 // null, uin's type must be casted to not null
2203 if (phi_type->join(TypePtr::NOTNULL) == phi_type->remove_speculative() &&
2204 uin_type->join(TypePtr::NOTNULL) != uin_type->remove_speculative()) {
2205 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, TypePtr::NOTNULL, ConstraintCastNode::StrongDependency);
2206 }
2207
2208 // If the type of phi and uin, both casted to not null,
2209 // differ the klass of uin must be (check)cast'ed to match
2210 // that of phi
2211 if (phi_type->join_speculative(TypePtr::NOTNULL) != uin_type->join_speculative(TypePtr::NOTNULL)) {
2212 Node* n = uin;
2213 if (cast != nullptr) {
2214 cast = phase->transform(cast);
2215 n = cast;
2216 }
2217 cast = ConstraintCastNode::make_cast(Op_CheckCastPP, r, n, phi_type, ConstraintCastNode::StrongDependency);
2218 }
2219 if (cast == nullptr) {
2220 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, ConstraintCastNode::StrongDependency);
2221 }
2222 }
2223 } else {
2224 cast = ConstraintCastNode::make_cast_for_type(r, uin, phi_type, ConstraintCastNode::StrongDependency);
2225 }
2226 assert(cast != nullptr, "cast should be set");
2227 cast = phase->transform(cast);
2228 // set all inputs to the new cast(s) so the Phi is removed by Identity
2229 PhaseIterGVN* igvn = phase->is_IterGVN();
2230 for (uint i = 1; i < req(); i++) {
2231 set_req_X(i, cast, igvn);
2232 }
2233 uin = cast;
2234 }
2235
2236 // One unique input.
2237 debug_only(Node* ident = Identity(phase));
2238 // The unique input must eventually be detected by the Identity call.
2239 #ifdef ASSERT
2240 if (ident != uin && !ident->is_top() && !must_wait_for_region_in_irreducible_loop(phase)) {
2241 // print this output before failing assert
2242 r->dump(3);
2243 this->dump(3);
2244 ident->dump();
2245 uin->dump();
2246 }
2247 #endif
2248 // Identity may not return the expected uin, if it has to wait for the region, in irreducible case
2249 assert(ident == uin || ident->is_top() || must_wait_for_region_in_irreducible_loop(phase), "Identity must clean this up");
2250 return nullptr;
2251 }
2252
2253 Node* opt = nullptr;
2254 int true_path = is_diamond_phi();
2255 if (true_path != 0 &&
2256 // If one of the diamond's branch is in the process of dying then, the Phi's input for that branch might transform
2257 // to top. If that happens replacing the Phi with an operation that consumes the Phi's inputs will cause the Phi
2258 // to be replaced by top. To prevent that, delay the transformation until the branch has a chance to be removed.
2259 !(can_reshape && wait_for_region_igvn(phase))) {
2260 // Check for CMove'ing identity. If it would be unsafe,
2261 // handle it here. In the safe case, let Identity handle it.
2262 Node* unsafe_id = is_cmove_id(phase, true_path);
2263 if( unsafe_id != nullptr && is_unsafe_data_reference(unsafe_id) )
2264 opt = unsafe_id;
2265
2266 // Check for simple convert-to-boolean pattern
2267 if( opt == nullptr )
2268 opt = is_x2logic(phase, this, true_path);
2269
2270 // Check for absolute value
2271 if( opt == nullptr )
2272 opt = is_absolute(phase, this, true_path);
2273
2274 // Check for conditional add
2275 if( opt == nullptr && can_reshape )
2276 opt = is_cond_add(phase, this, true_path);
2277
2278 // These 4 optimizations could subsume the phi:
2279 // have to check for a dead data loop creation.
2280 if( opt != nullptr ) {
2281 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) {
2282 // Found dead loop.
2283 if( can_reshape )
2284 return top;
2285 // We can't return top if we are in Parse phase - cut inputs only
2286 // to stop further optimizations for this phi. Identity will return TOP.
2287 assert(req() == 3, "only diamond merge phi here");
2288 set_req(1, top);
2289 set_req(2, top);
2290 return nullptr;
2291 } else {
2292 return opt;
2293 }
2294 }
2295 }
2296
2297 // Check for merging identical values and split flow paths
2298 if (can_reshape) {
2299 opt = split_flow_path(phase, this);
2300 // This optimization only modifies phi - don't need to check for dead loop.
2301 assert(opt == nullptr || opt == this, "do not elide phi");
2302 if (opt != nullptr) return opt;
2303 }
2304
2305 if (in(1) != nullptr && in(1)->Opcode() == Op_AddP && can_reshape) {
2306 // Try to undo Phi of AddP:
2307 // (Phi (AddP base address offset) (AddP base2 address2 offset2))
2308 // becomes:
2309 // newbase := (Phi base base2)
2310 // newaddress := (Phi address address2)
2311 // newoffset := (Phi offset offset2)
2312 // (AddP newbase newaddress newoffset)
2313 //
2314 // This occurs as a result of unsuccessful split_thru_phi and
2315 // interferes with taking advantage of addressing modes. See the
2316 // clone_shift_expressions code in matcher.cpp
2317 Node* addp = in(1);
2318 Node* base = addp->in(AddPNode::Base);
2319 Node* address = addp->in(AddPNode::Address);
2320 Node* offset = addp->in(AddPNode::Offset);
2321 if (base != nullptr && address != nullptr && offset != nullptr &&
2322 !base->is_top() && !address->is_top() && !offset->is_top()) {
2323 const Type* base_type = base->bottom_type();
2324 const Type* address_type = address->bottom_type();
2325 // make sure that all the inputs are similar to the first one,
2326 // i.e. AddP with base == address and same offset as first AddP
2327 bool doit = true;
2328 for (uint i = 2; i < req(); i++) {
2329 if (in(i) == nullptr ||
2330 in(i)->Opcode() != Op_AddP ||
2331 in(i)->in(AddPNode::Base) == nullptr ||
2332 in(i)->in(AddPNode::Address) == nullptr ||
2333 in(i)->in(AddPNode::Offset) == nullptr ||
2334 in(i)->in(AddPNode::Base)->is_top() ||
2335 in(i)->in(AddPNode::Address)->is_top() ||
2336 in(i)->in(AddPNode::Offset)->is_top()) {
2337 doit = false;
2338 break;
2339 }
2340 if (in(i)->in(AddPNode::Base) != base) {
2341 base = nullptr;
2342 }
2343 if (in(i)->in(AddPNode::Offset) != offset) {
2344 offset = nullptr;
2345 }
2346 if (in(i)->in(AddPNode::Address) != address) {
2347 address = nullptr;
2348 }
2349 // Accumulate type for resulting Phi
2350 base_type = base_type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type());
2351 address_type = address_type->meet_speculative(in(i)->in(AddPNode::Address)->bottom_type());
2352 }
2353 if (doit && base == nullptr) {
2354 // Check for neighboring AddP nodes in a tree.
2355 // If they have a base, use that it.
2356 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) {
2357 Node* u = this->fast_out(k);
2358 if (u->is_AddP()) {
2359 Node* base2 = u->in(AddPNode::Base);
2360 if (base2 != nullptr && !base2->is_top()) {
2361 if (base == nullptr)
2362 base = base2;
2363 else if (base != base2)
2364 { doit = false; break; }
2365 }
2366 }
2367 }
2368 }
2369 if (doit) {
2370 if (base == nullptr) {
2371 base = new PhiNode(in(0), base_type, nullptr);
2372 for (uint i = 1; i < req(); i++) {
2373 base->init_req(i, in(i)->in(AddPNode::Base));
2374 }
2375 phase->is_IterGVN()->register_new_node_with_optimizer(base);
2376 }
2377 if (address == nullptr) {
2378 address = new PhiNode(in(0), address_type, nullptr);
2379 for (uint i = 1; i < req(); i++) {
2380 address->init_req(i, in(i)->in(AddPNode::Address));
2381 }
2382 phase->is_IterGVN()->register_new_node_with_optimizer(address);
2383 }
2384 if (offset == nullptr) {
2385 offset = new PhiNode(in(0), TypeX_X, nullptr);
2386 for (uint i = 1; i < req(); i++) {
2387 offset->init_req(i, in(i)->in(AddPNode::Offset));
2388 }
2389 phase->is_IterGVN()->register_new_node_with_optimizer(offset);
2390 }
2391 return new AddPNode(base, address, offset);
2392 }
2393 }
2394 }
2395
2396 // Split phis through memory merges, so that the memory merges will go away.
2397 // Piggy-back this transformation on the search for a unique input....
2398 // It will be as if the merged memory is the unique value of the phi.
2399 // (Do not attempt this optimization unless parsing is complete.
2400 // It would make the parser's memory-merge logic sick.)
2401 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.)
2402 if (progress == nullptr && can_reshape && type() == Type::MEMORY) {
2403 // see if this phi should be sliced
2404 uint merge_width = 0;
2405 bool saw_self = false;
2406 // TODO revisit this with JDK-8247216
2407 bool mergemem_only = true;
2408 for( uint i=1; i<req(); ++i ) {// For all paths in
2409 Node *ii = in(i);
2410 // TOP inputs should not be counted as safe inputs because if the
2411 // Phi references itself through all other inputs then splitting the
2412 // Phi through memory merges would create dead loop at later stage.
2413 if (ii == top) {
2414 return nullptr; // Delay optimization until graph is cleaned.
2415 }
2416 if (ii->is_MergeMem()) {
2417 MergeMemNode* n = ii->as_MergeMem();
2418 merge_width = MAX2(merge_width, n->req());
2419 saw_self = saw_self || (n->base_memory() == this);
2420 } else {
2421 mergemem_only = false;
2422 }
2423 }
2424
2425 // This restriction is temporarily necessary to ensure termination:
2426 if (!mergemem_only && !saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0;
2427
2428 if (merge_width > Compile::AliasIdxRaw) {
2429 // found at least one non-empty MergeMem
2430 const TypePtr* at = adr_type();
2431 if (at != TypePtr::BOTTOM) {
2432 // Patch the existing phi to select an input from the merge:
2433 // Phi:AT1(...MergeMem(m0, m1, m2)...) into
2434 // Phi:AT1(...m1...)
2435 int alias_idx = phase->C->get_alias_index(at);
2436 for (uint i=1; i<req(); ++i) {
2437 Node *ii = in(i);
2438 if (ii->is_MergeMem()) {
2439 MergeMemNode* n = ii->as_MergeMem();
2440 // compress paths and change unreachable cycles to TOP
2441 // If not, we can update the input infinitely along a MergeMem cycle
2442 // Equivalent code is in MemNode::Ideal_common
2443 Node *m = phase->transform(n);
2444 if (outcnt() == 0) { // Above transform() may kill us!
2445 return top;
2446 }
2447 // If transformed to a MergeMem, get the desired slice
2448 // Otherwise the returned node represents memory for every slice
2449 Node *new_mem = (m->is_MergeMem()) ?
2450 m->as_MergeMem()->memory_at(alias_idx) : m;
2451 // Update input if it is progress over what we have now
2452 if (new_mem != ii) {
2453 set_req_X(i, new_mem, phase->is_IterGVN());
2454 progress = this;
2455 }
2456 }
2457 }
2458 } else {
2459 // We know that at least one MergeMem->base_memory() == this
2460 // (saw_self == true). If all other inputs also references this phi
2461 // (directly or through data nodes) - it is a dead loop.
2462 bool saw_safe_input = false;
2463 for (uint j = 1; j < req(); ++j) {
2464 Node* n = in(j);
2465 if (n->is_MergeMem()) {
2466 MergeMemNode* mm = n->as_MergeMem();
2467 if (mm->base_memory() == this || mm->base_memory() == mm->empty_memory()) {
2468 // Skip this input if it references back to this phi or if the memory path is dead
2469 continue;
2470 }
2471 }
2472 if (!is_unsafe_data_reference(n)) {
2473 saw_safe_input = true; // found safe input
2474 break;
2475 }
2476 }
2477 if (!saw_safe_input) {
2478 // There is a dead loop: All inputs are either dead or reference back to this phi
2479 return top;
2480 }
2481
2482 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into
2483 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...))
2484 PhaseIterGVN* igvn = phase->is_IterGVN();
2485 assert(igvn != nullptr, "sanity check");
2486 Node* hook = new Node(1);
2487 PhiNode* new_base = (PhiNode*) clone();
2488 // Must eagerly register phis, since they participate in loops.
2489 igvn->register_new_node_with_optimizer(new_base);
2490 hook->add_req(new_base);
2491
2492 MergeMemNode* result = MergeMemNode::make(new_base);
2493 for (uint i = 1; i < req(); ++i) {
2494 Node *ii = in(i);
2495 if (ii->is_MergeMem()) {
2496 MergeMemNode* n = ii->as_MergeMem();
2497 if (igvn) {
2498 // TODO revisit this with JDK-8247216
2499 // Put 'n' on the worklist because it might be modified by MergeMemStream::iteration_setup
2500 igvn->_worklist.push(n);
2501 }
2502 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) {
2503 // If we have not seen this slice yet, make a phi for it.
2504 bool made_new_phi = false;
2505 if (mms.is_empty()) {
2506 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C));
2507 made_new_phi = true;
2508 igvn->register_new_node_with_optimizer(new_phi);
2509 hook->add_req(new_phi);
2510 mms.set_memory(new_phi);
2511 }
2512 Node* phi = mms.memory();
2513 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice");
2514 phi->set_req(i, mms.memory2());
2515 }
2516 }
2517 }
2518 // Distribute all self-loops.
2519 { // (Extra braces to hide mms.)
2520 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2521 Node* phi = mms.memory();
2522 for (uint i = 1; i < req(); ++i) {
2523 if (phi->in(i) == this) phi->set_req(i, phi);
2524 }
2525 }
2526 }
2527 // Already replace this phi node to cut it off from the graph to not interfere in dead loop checks during the
2528 // transformations of the new phi nodes below. Otherwise, we could wrongly conclude that there is no dead loop
2529 // because we are finding this phi node again. Also set the type of the new MergeMem node in case we are also
2530 // visiting it in the transformations below.
2531 igvn->replace_node(this, result);
2532 igvn->set_type(result, result->bottom_type());
2533
2534 // now transform the new nodes, and return the mergemem
2535 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2536 Node* phi = mms.memory();
2537 mms.set_memory(phase->transform(phi));
2538 }
2539 hook->destruct(igvn);
2540 // Replace self with the result.
2541 return result;
2542 }
2543 }
2544 //
2545 // Other optimizations on the memory chain
2546 //
2547 const TypePtr* at = adr_type();
2548 for( uint i=1; i<req(); ++i ) {// For all paths in
2549 Node *ii = in(i);
2550 Node *new_in = MemNode::optimize_memory_chain(ii, at, nullptr, phase);
2551 if (ii != new_in ) {
2552 set_req(i, new_in);
2553 progress = this;
2554 }
2555 }
2556 }
2557
2558 #ifdef _LP64
2559 // Push DecodeN/DecodeNKlass down through phi.
2560 // The rest of phi graph will transform by split EncodeP node though phis up.
2561 if ((UseCompressedOops || UseCompressedClassPointers) && can_reshape && progress == nullptr) {
2562 bool may_push = true;
2563 bool has_decodeN = false;
2564 bool is_decodeN = false;
2565 for (uint i=1; i<req(); ++i) {// For all paths in
2566 Node *ii = in(i);
2567 if (ii->is_DecodeNarrowPtr() && ii->bottom_type() == bottom_type()) {
2568 // Do optimization if a non dead path exist.
2569 if (ii->in(1)->bottom_type() != Type::TOP) {
2570 has_decodeN = true;
2571 is_decodeN = ii->is_DecodeN();
2572 }
2573 } else if (!ii->is_Phi()) {
2574 may_push = false;
2575 }
2576 }
2577
2578 if (has_decodeN && may_push) {
2579 PhaseIterGVN *igvn = phase->is_IterGVN();
2580 // Make narrow type for new phi.
2581 const Type* narrow_t;
2582 if (is_decodeN) {
2583 narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr());
2584 } else {
2585 narrow_t = TypeNarrowKlass::make(this->bottom_type()->is_ptr());
2586 }
2587 PhiNode* new_phi = new PhiNode(r, narrow_t);
2588 uint orig_cnt = req();
2589 for (uint i=1; i<req(); ++i) {// For all paths in
2590 Node *ii = in(i);
2591 Node* new_ii = nullptr;
2592 if (ii->is_DecodeNarrowPtr()) {
2593 assert(ii->bottom_type() == bottom_type(), "sanity");
2594 new_ii = ii->in(1);
2595 } else {
2596 assert(ii->is_Phi(), "sanity");
2597 if (ii->as_Phi() == this) {
2598 new_ii = new_phi;
2599 } else {
2600 if (is_decodeN) {
2601 new_ii = new EncodePNode(ii, narrow_t);
2602 } else {
2603 new_ii = new EncodePKlassNode(ii, narrow_t);
2604 }
2605 igvn->register_new_node_with_optimizer(new_ii);
2606 }
2607 }
2608 new_phi->set_req(i, new_ii);
2609 }
2610 igvn->register_new_node_with_optimizer(new_phi, this);
2611 if (is_decodeN) {
2612 progress = new DecodeNNode(new_phi, bottom_type());
2613 } else {
2614 progress = new DecodeNKlassNode(new_phi, bottom_type());
2615 }
2616 }
2617 }
2618 #endif
2619
2620 // Check recursively if inputs are either an inline type, constant null
2621 // or another Phi (including self references through data loops). If so,
2622 // push the inline types down through the phis to enable folding of loads.
2623 if (EnableValhalla && _type->isa_ptr() && req() > 2) {
2624 ResourceMark rm;
2625 Unique_Node_List worklist;
2626 worklist.push(this);
2627 bool can_optimize = true;
2628 ciInlineKlass* vk = nullptr;
2629 Node_List casts;
2630
2631 // TODO 8302217 We need to prevent endless pushing through
2632 bool only_phi = (outcnt() != 0);
2633 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
2634 Node* n = fast_out(i);
2635 if (n->is_InlineType() && n->in(1) == this) {
2636 can_optimize = false;
2637 break;
2638 }
2639 if (!n->is_Phi()) {
2640 only_phi = false;
2641 }
2642 }
2643 if (only_phi) {
2644 can_optimize = false;
2645 }
2646 for (uint next = 0; next < worklist.size() && can_optimize; next++) {
2647 Node* phi = worklist.at(next);
2648 for (uint i = 1; i < phi->req() && can_optimize; i++) {
2649 Node* n = phi->in(i);
2650 if (n == nullptr) {
2651 can_optimize = false;
2652 break;
2653 }
2654 while (n->is_ConstraintCast()) {
2655 if (n->in(0) != nullptr && n->in(0)->is_top()) {
2656 // Will die, don't optimize
2657 can_optimize = false;
2658 break;
2659 }
2660 casts.push(n);
2661 n = n->in(1);
2662 }
2663 const Type* t = phase->type(n);
2664 if (n->is_InlineType() && (vk == nullptr || vk == t->inline_klass())) {
2665 vk = (vk == nullptr) ? t->inline_klass() : vk;
2666 } else if (n->is_Phi() && can_reshape && n->bottom_type()->isa_ptr()) {
2667 worklist.push(n);
2668 } else if (!t->is_zero_type()) {
2669 can_optimize = false;
2670 }
2671 }
2672 }
2673 // Check if cast nodes can be pushed through
2674 const Type* t = Type::get_const_type(vk);
2675 while (casts.size() != 0 && can_optimize && t != nullptr) {
2676 Node* cast = casts.pop();
2677 if (t->filter(cast->bottom_type()) == Type::TOP) {
2678 can_optimize = false;
2679 }
2680 }
2681 if (can_optimize && vk != nullptr) {
2682 return push_inline_types_through(phase, can_reshape, vk);
2683 }
2684 }
2685
2686 // Phi (VB ... VB) => VB (Phi ...) (Phi ...)
2687 if (EnableVectorReboxing && can_reshape && progress == nullptr && type()->isa_oopptr()) {
2688 progress = merge_through_phi(this, phase->is_IterGVN());
2689 }
2690
2691 return progress; // Return any progress
2692 }
2693
2694 Node* PhiNode::clone_through_phi(Node* root_phi, const Type* t, uint c, PhaseIterGVN* igvn) {
2695 Node_Stack stack(1);
2696 VectorSet visited;
2697 Node_List node_map;
2698
2699 stack.push(root_phi, 1); // ignore control
2700 visited.set(root_phi->_idx);
2701
2702 Node* new_phi = new PhiNode(root_phi->in(0), t);
2703 node_map.map(root_phi->_idx, new_phi);
2704
2705 while (stack.is_nonempty()) {
2706 Node* n = stack.node();
2707 uint idx = stack.index();
2708 assert(n->is_Phi(), "not a phi");
2709 if (idx < n->req()) {
2710 stack.set_index(idx + 1);
2711 Node* def = n->in(idx);
2712 if (def == nullptr) {
2713 continue; // ignore dead path
2714 } else if (def->is_Phi()) { // inner node
2715 Node* new_phi = node_map[n->_idx];
2716 if (!visited.test_set(def->_idx)) { // not visited yet
2717 node_map.map(def->_idx, new PhiNode(def->in(0), t));
2718 stack.push(def, 1); // ignore control
2719 }
2720 Node* new_in = node_map[def->_idx];
2721 new_phi->set_req(idx, new_in);
2722 } else if (def->Opcode() == Op_VectorBox) { // leaf
2723 assert(n->is_Phi(), "not a phi");
2724 Node* new_phi = node_map[n->_idx];
2725 new_phi->set_req(idx, def->in(c));
2726 } else {
2727 assert(false, "not optimizeable");
2728 return nullptr;
2729 }
2730 } else {
2731 Node* new_phi = node_map[n->_idx];
2732 igvn->register_new_node_with_optimizer(new_phi, n);
2733 stack.pop();
2734 }
2735 }
2736 return new_phi;
2737 }
2738
2739 Node* PhiNode::merge_through_phi(Node* root_phi, PhaseIterGVN* igvn) {
2740 Node_Stack stack(1);
2741 VectorSet visited;
2742
2743 stack.push(root_phi, 1); // ignore control
2744 visited.set(root_phi->_idx);
2745
2746 VectorBoxNode* cached_vbox = nullptr;
2747 while (stack.is_nonempty()) {
2748 Node* n = stack.node();
2749 uint idx = stack.index();
2750 if (idx < n->req()) {
2751 stack.set_index(idx + 1);
2752 Node* in = n->in(idx);
2753 if (in == nullptr) {
2754 continue; // ignore dead path
2755 } else if (in->isa_Phi()) {
2756 if (!visited.test_set(in->_idx)) {
2757 stack.push(in, 1); // ignore control
2758 }
2759 } else if (in->Opcode() == Op_VectorBox) {
2760 VectorBoxNode* vbox = static_cast<VectorBoxNode*>(in);
2761 if (cached_vbox == nullptr) {
2762 cached_vbox = vbox;
2763 } else if (vbox->vec_type() != cached_vbox->vec_type()) {
2764 // TODO: vector type mismatch can be handled with additional reinterpret casts
2765 assert(Type::cmp(vbox->vec_type(), cached_vbox->vec_type()) != 0, "inconsistent");
2766 return nullptr; // not optimizable: vector type mismatch
2767 } else if (vbox->box_type() != cached_vbox->box_type()) {
2768 assert(Type::cmp(vbox->box_type(), cached_vbox->box_type()) != 0, "inconsistent");
2769 return nullptr; // not optimizable: box type mismatch
2770 }
2771 } else {
2772 return nullptr; // not optimizable: neither Phi nor VectorBox
2773 }
2774 } else {
2775 stack.pop();
2776 }
2777 }
2778 if (cached_vbox == nullptr) {
2779 // We have a Phi dead-loop (no data-input). Phi nodes are considered safe,
2780 // so just avoid this optimization.
2781 return nullptr;
2782 }
2783 const TypeInstPtr* btype = cached_vbox->box_type();
2784 const TypeVect* vtype = cached_vbox->vec_type();
2785 Node* new_vbox_phi = clone_through_phi(root_phi, btype, VectorBoxNode::Box, igvn);
2786 Node* new_vect_phi = clone_through_phi(root_phi, vtype, VectorBoxNode::Value, igvn);
2787 return new VectorBoxNode(igvn->C, new_vbox_phi, new_vect_phi, btype, vtype);
2788 }
2789
2790 bool PhiNode::is_data_loop(RegionNode* r, Node* uin, const PhaseGVN* phase) {
2791 // First, take the short cut when we know it is a loop and the EntryControl data path is dead.
2792 // The loop node may only have one input because the entry path was removed in PhaseIdealLoop::Dominators().
2793 // Then, check if there is a data loop when the phi references itself directly or through other data nodes.
2794 assert(!r->is_Loop() || r->req() <= 3, "Loop node should have 3 or less inputs");
2795 const bool is_loop = (r->is_Loop() && r->req() == 3);
2796 const Node* top = phase->C->top();
2797 if (is_loop) {
2798 return !uin->eqv_uncast(in(LoopNode::EntryControl));
2799 } else {
2800 // We have a data loop either with an unsafe data reference or if a region is unreachable.
2801 return is_unsafe_data_reference(uin)
2802 || (r->req() == 3 && (r->in(1) != top && r->in(2) == top && r->is_unreachable_region(phase)));
2803 }
2804 }
2805
2806 //------------------------------is_tripcount-----------------------------------
2807 bool PhiNode::is_tripcount(BasicType bt) const {
2808 return (in(0) != nullptr && in(0)->is_BaseCountedLoop() &&
2809 in(0)->as_BaseCountedLoop()->bt() == bt &&
2810 in(0)->as_BaseCountedLoop()->phi() == this);
2811 }
2812
2813 //------------------------------out_RegMask------------------------------------
2814 const RegMask &PhiNode::in_RegMask(uint i) const {
2815 return i ? out_RegMask() : RegMask::Empty;
2816 }
2817
2818 const RegMask &PhiNode::out_RegMask() const {
2819 uint ideal_reg = _type->ideal_reg();
2820 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
2821 if( ideal_reg == 0 ) return RegMask::Empty;
2822 assert(ideal_reg != Op_RegFlags, "flags register is not spillable");
2823 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
2824 }
2825
2826 #ifndef PRODUCT
2827 void PhiNode::dump_spec(outputStream *st) const {
2828 TypeNode::dump_spec(st);
2829 if (is_tripcount(T_INT) || is_tripcount(T_LONG)) {
2830 st->print(" #tripcount");
2831 }
2832 }
2833 #endif
2834
2835
2836 //=============================================================================
2837 const Type* GotoNode::Value(PhaseGVN* phase) const {
2838 // If the input is reachable, then we are executed.
2839 // If the input is not reachable, then we are not executed.
2840 return phase->type(in(0));
2841 }
2842
2843 Node* GotoNode::Identity(PhaseGVN* phase) {
2844 return in(0); // Simple copy of incoming control
2845 }
2846
2847 const RegMask &GotoNode::out_RegMask() const {
2848 return RegMask::Empty;
2849 }
2850
2851 //=============================================================================
2852 const RegMask &JumpNode::out_RegMask() const {
2853 return RegMask::Empty;
2854 }
2855
2856 //=============================================================================
2857 const RegMask &JProjNode::out_RegMask() const {
2858 return RegMask::Empty;
2859 }
2860
2861 //=============================================================================
2862 const RegMask &CProjNode::out_RegMask() const {
2863 return RegMask::Empty;
2864 }
2865
2866
2867
2868 //=============================================================================
2869
2870 uint PCTableNode::hash() const { return Node::hash() + _size; }
2871 bool PCTableNode::cmp( const Node &n ) const
2872 { return _size == ((PCTableNode&)n)._size; }
2873
2874 const Type *PCTableNode::bottom_type() const {
2875 const Type** f = TypeTuple::fields(_size);
2876 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2877 return TypeTuple::make(_size, f);
2878 }
2879
2880 //------------------------------Value------------------------------------------
2881 // Compute the type of the PCTableNode. If reachable it is a tuple of
2882 // Control, otherwise the table targets are not reachable
2883 const Type* PCTableNode::Value(PhaseGVN* phase) const {
2884 if( phase->type(in(0)) == Type::CONTROL )
2885 return bottom_type();
2886 return Type::TOP; // All paths dead? Then so are we
2887 }
2888
2889 //------------------------------Ideal------------------------------------------
2890 // Return a node which is more "ideal" than the current node. Strip out
2891 // control copies
2892 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2893 return remove_dead_region(phase, can_reshape) ? this : nullptr;
2894 }
2895
2896 //=============================================================================
2897 uint JumpProjNode::hash() const {
2898 return Node::hash() + _dest_bci;
2899 }
2900
2901 bool JumpProjNode::cmp( const Node &n ) const {
2902 return ProjNode::cmp(n) &&
2903 _dest_bci == ((JumpProjNode&)n)._dest_bci;
2904 }
2905
2906 #ifndef PRODUCT
2907 void JumpProjNode::dump_spec(outputStream *st) const {
2908 ProjNode::dump_spec(st);
2909 st->print("@bci %d ",_dest_bci);
2910 }
2911
2912 void JumpProjNode::dump_compact_spec(outputStream *st) const {
2913 ProjNode::dump_compact_spec(st);
2914 st->print("(%d)%d@%d", _switch_val, _proj_no, _dest_bci);
2915 }
2916 #endif
2917
2918 //=============================================================================
2919 //------------------------------Value------------------------------------------
2920 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot
2921 // have the default "fall_through_index" path.
2922 const Type* CatchNode::Value(PhaseGVN* phase) const {
2923 // Unreachable? Then so are all paths from here.
2924 if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
2925 // First assume all paths are reachable
2926 const Type** f = TypeTuple::fields(_size);
2927 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2928 // Identify cases that will always throw an exception
2929 // () rethrow call
2930 // () virtual or interface call with null receiver
2931 // () call is a check cast with incompatible arguments
2932 if( in(1)->is_Proj() ) {
2933 Node *i10 = in(1)->in(0);
2934 if( i10->is_Call() ) {
2935 CallNode *call = i10->as_Call();
2936 // Rethrows always throw exceptions, never return
2937 if (call->entry_point() == OptoRuntime::rethrow_stub()) {
2938 f[CatchProjNode::fall_through_index] = Type::TOP;
2939 } else if (call->is_AllocateArray()) {
2940 Node* klass_node = call->in(AllocateNode::KlassNode);
2941 Node* length = call->in(AllocateNode::ALength);
2942 const Type* length_type = phase->type(length);
2943 const Type* klass_type = phase->type(klass_node);
2944 Node* valid_length_test = call->in(AllocateNode::ValidLengthTest);
2945 const Type* valid_length_test_t = phase->type(valid_length_test);
2946 if (length_type == Type::TOP || klass_type == Type::TOP || valid_length_test_t == Type::TOP ||
2947 valid_length_test_t->is_int()->is_con(0)) {
2948 f[CatchProjNode::fall_through_index] = Type::TOP;
2949 }
2950 } else if( call->req() > TypeFunc::Parms ) {
2951 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) );
2952 // Check for null receiver to virtual or interface calls
2953 if( call->is_CallDynamicJava() &&
2954 arg0->higher_equal(TypePtr::NULL_PTR) ) {
2955 f[CatchProjNode::fall_through_index] = Type::TOP;
2956 }
2957 } // End of if not a runtime stub
2958 } // End of if have call above me
2959 } // End of slot 1 is not a projection
2960 return TypeTuple::make(_size, f);
2961 }
2962
2963 //=============================================================================
2964 uint CatchProjNode::hash() const {
2965 return Node::hash() + _handler_bci;
2966 }
2967
2968
2969 bool CatchProjNode::cmp( const Node &n ) const {
2970 return ProjNode::cmp(n) &&
2971 _handler_bci == ((CatchProjNode&)n)._handler_bci;
2972 }
2973
2974
2975 //------------------------------Identity---------------------------------------
2976 // If only 1 target is possible, choose it if it is the main control
2977 Node* CatchProjNode::Identity(PhaseGVN* phase) {
2978 // If my value is control and no other value is, then treat as ID
2979 const TypeTuple *t = phase->type(in(0))->is_tuple();
2980 if (t->field_at(_con) != Type::CONTROL) return this;
2981 // If we remove the last CatchProj and elide the Catch/CatchProj, then we
2982 // also remove any exception table entry. Thus we must know the call
2983 // feeding the Catch will not really throw an exception. This is ok for
2984 // the main fall-thru control (happens when we know a call can never throw
2985 // an exception) or for "rethrow", because a further optimization will
2986 // yank the rethrow (happens when we inline a function that can throw an
2987 // exception and the caller has no handler). Not legal, e.g., for passing
2988 // a null receiver to a v-call, or passing bad types to a slow-check-cast.
2989 // These cases MUST throw an exception via the runtime system, so the VM
2990 // will be looking for a table entry.
2991 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode
2992 CallNode *call;
2993 if (_con != TypeFunc::Control && // Bail out if not the main control.
2994 !(proj->is_Proj() && // AND NOT a rethrow
2995 proj->in(0)->is_Call() &&
2996 (call = proj->in(0)->as_Call()) &&
2997 call->entry_point() == OptoRuntime::rethrow_stub()))
2998 return this;
2999
3000 // Search for any other path being control
3001 for (uint i = 0; i < t->cnt(); i++) {
3002 if (i != _con && t->field_at(i) == Type::CONTROL)
3003 return this;
3004 }
3005 // Only my path is possible; I am identity on control to the jump
3006 return in(0)->in(0);
3007 }
3008
3009
3010 #ifndef PRODUCT
3011 void CatchProjNode::dump_spec(outputStream *st) const {
3012 ProjNode::dump_spec(st);
3013 st->print("@bci %d ",_handler_bci);
3014 }
3015 #endif
3016
3017 //=============================================================================
3018 //------------------------------Identity---------------------------------------
3019 // Check for CreateEx being Identity.
3020 Node* CreateExNode::Identity(PhaseGVN* phase) {
3021 if( phase->type(in(1)) == Type::TOP ) return in(1);
3022 if( phase->type(in(0)) == Type::TOP ) return in(0);
3023 if (phase->type(in(0)->in(0)) == Type::TOP) {
3024 assert(in(0)->is_CatchProj(), "control is CatchProj");
3025 return phase->C->top(); // dead code
3026 }
3027 // We only come from CatchProj, unless the CatchProj goes away.
3028 // If the CatchProj is optimized away, then we just carry the
3029 // exception oop through.
3030
3031 // CheckCastPPNode::Ideal() for inline types reuses the exception
3032 // paths of a call to perform an allocation: we can see a Phi here.
3033 if (in(1)->is_Phi()) {
3034 return this;
3035 }
3036 CallNode *call = in(1)->in(0)->as_Call();
3037
3038 return (in(0)->is_CatchProj() && in(0)->in(0)->is_Catch() &&
3039 in(0)->in(0)->in(1) == in(1)) ? this : call->in(TypeFunc::Parms);
3040 }
3041
3042 //=============================================================================
3043 //------------------------------Value------------------------------------------
3044 // Check for being unreachable.
3045 const Type* NeverBranchNode::Value(PhaseGVN* phase) const {
3046 if (!in(0) || in(0)->is_top()) return Type::TOP;
3047 return bottom_type();
3048 }
3049
3050 //------------------------------Ideal------------------------------------------
3051 // Check for no longer being part of a loop
3052 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3053 if (can_reshape && !in(0)->is_Region()) {
3054 // Dead code elimination can sometimes delete this projection so
3055 // if it's not there, there's nothing to do.
3056 Node* fallthru = proj_out_or_null(0);
3057 if (fallthru != nullptr) {
3058 phase->is_IterGVN()->replace_node(fallthru, in(0));
3059 }
3060 return phase->C->top();
3061 }
3062 return nullptr;
3063 }
3064
3065 #ifndef PRODUCT
3066 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const {
3067 st->print("%s", Name());
3068 }
3069 #endif
3070
3071 #ifndef PRODUCT
3072 void BlackholeNode::format(PhaseRegAlloc* ra, outputStream* st) const {
3073 st->print("blackhole ");
3074 bool first = true;
3075 for (uint i = 0; i < req(); i++) {
3076 Node* n = in(i);
3077 if (n != nullptr && OptoReg::is_valid(ra->get_reg_first(n))) {
3078 if (first) {
3079 first = false;
3080 } else {
3081 st->print(", ");
3082 }
3083 char buf[128];
3084 ra->dump_register(n, buf, sizeof(buf));
3085 st->print("%s", buf);
3086 }
3087 }
3088 st->cr();
3089 }
3090 #endif
3091