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.
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23 */
24
25 #include "precompiled.hpp"
26 #include "gc/shared/barrierSet.hpp"
27 #include "gc/shared/c2/barrierSetC2.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "memory/resourceArea.hpp"
30 #include "oops/objArrayKlass.hpp"
31 #include "opto/addnode.hpp"
32 #include "opto/castnode.hpp"
33 #include "opto/cfgnode.hpp"
34 #include "opto/connode.hpp"
35 #include "opto/convertnode.hpp"
36 #include "opto/loopnode.hpp"
37 #include "opto/machnode.hpp"
38 #include "opto/movenode.hpp"
39 #include "opto/narrowptrnode.hpp"
40 #include "opto/mulnode.hpp"
41 #include "opto/phaseX.hpp"
42 #include "opto/regalloc.hpp"
43 #include "opto/regmask.hpp"
44 #include "opto/runtime.hpp"
45 #include "opto/subnode.hpp"
46 #include "opto/vectornode.hpp"
47 #include "utilities/vmError.hpp"
48
49 // Portions of code courtesy of Clifford Click
50
51 // Optimization - Graph Style
52
53 //=============================================================================
54 //------------------------------Value------------------------------------------
55 // Compute the type of the RegionNode.
56 const Type* RegionNode::Value(PhaseGVN* phase) const {
57 for( uint i=1; i<req(); ++i ) { // For all paths in
58 Node *n = in(i); // Get Control source
59 if( !n ) continue; // Missing inputs are TOP
60 if( phase->type(n) == Type::CONTROL )
61 return Type::CONTROL;
62 }
63 return Type::TOP; // All paths dead? Then so are we
64 }
65
66 //------------------------------Identity---------------------------------------
67 // Check for Region being Identity.
68 Node* RegionNode::Identity(PhaseGVN* phase) {
69 // Cannot have Region be an identity, even if it has only 1 input.
70 // Phi users cannot have their Region input folded away for them,
71 // since they need to select the proper data input
72 return this;
73 }
74
75 //------------------------------merge_region-----------------------------------
76 // If a Region flows into a Region, merge into one big happy merge. This is
77 // hard to do if there is stuff that has to happen
78 static Node *merge_region(RegionNode *region, PhaseGVN *phase) {
79 if( region->Opcode() != Op_Region ) // Do not do to LoopNodes
80 return nullptr;
81 Node *progress = nullptr; // Progress flag
82 PhaseIterGVN *igvn = phase->is_IterGVN();
83
84 uint rreq = region->req();
85 for( uint i = 1; i < rreq; i++ ) {
86 Node *r = region->in(i);
87 if( r && r->Opcode() == Op_Region && // Found a region?
88 r->in(0) == r && // Not already collapsed?
89 r != region && // Avoid stupid situations
90 r->outcnt() == 2 ) { // Self user and 'region' user only?
91 assert(!r->as_Region()->has_phi(), "no phi users");
92 if( !progress ) { // No progress
93 if (region->has_phi()) {
94 return nullptr; // Only flatten if no Phi users
95 // igvn->hash_delete( phi );
96 }
97 igvn->hash_delete( region );
98 progress = region; // Making progress
99 }
100 igvn->hash_delete( r );
101
102 // Append inputs to 'r' onto 'region'
103 for( uint j = 1; j < r->req(); j++ ) {
104 // Move an input from 'r' to 'region'
105 region->add_req(r->in(j));
106 r->set_req(j, phase->C->top());
107 // Update phis of 'region'
108 //for( uint k = 0; k < max; k++ ) {
109 // Node *phi = region->out(k);
110 // if( phi->is_Phi() ) {
111 // phi->add_req(phi->in(i));
112 // }
113 //}
114
115 rreq++; // One more input to Region
116 } // Found a region to merge into Region
117 igvn->_worklist.push(r);
118 // Clobber pointer to the now dead 'r'
119 region->set_req(i, phase->C->top());
120 }
121 }
122
123 return progress;
124 }
125
126
127
128 //--------------------------------has_phi--------------------------------------
129 // Helper function: Return any PhiNode that uses this region or null
130 PhiNode* RegionNode::has_phi() const {
131 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
132 Node* phi = fast_out(i);
133 if (phi->is_Phi()) { // Check for Phi users
134 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
135 return phi->as_Phi(); // this one is good enough
136 }
137 }
138
139 return nullptr;
140 }
141
142
143 //-----------------------------has_unique_phi----------------------------------
144 // Helper function: Return the only PhiNode that uses this region or null
145 PhiNode* RegionNode::has_unique_phi() const {
146 // Check that only one use is a Phi
147 PhiNode* only_phi = nullptr;
148 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
149 Node* phi = fast_out(i);
150 if (phi->is_Phi()) { // Check for Phi users
151 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
152 if (only_phi == nullptr) {
153 only_phi = phi->as_Phi();
154 } else {
155 return nullptr; // multiple phis
156 }
157 }
158 }
159
160 return only_phi;
161 }
162
163
164 //------------------------------check_phi_clipping-----------------------------
165 // Helper function for RegionNode's identification of FP clipping
166 // Check inputs to the Phi
167 static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) {
168 min = nullptr;
169 max = nullptr;
170 val = nullptr;
171 min_idx = 0;
172 max_idx = 0;
173 val_idx = 0;
174 uint phi_max = phi->req();
175 if( phi_max == 4 ) {
176 for( uint j = 1; j < phi_max; ++j ) {
177 Node *n = phi->in(j);
178 int opcode = n->Opcode();
179 switch( opcode ) {
180 case Op_ConI:
181 {
182 if( min == nullptr ) {
183 min = n->Opcode() == Op_ConI ? (ConNode*)n : nullptr;
184 min_idx = j;
185 } else {
186 max = n->Opcode() == Op_ConI ? (ConNode*)n : nullptr;
187 max_idx = j;
188 if( min->get_int() > max->get_int() ) {
189 // Swap min and max
190 ConNode *temp;
191 uint temp_idx;
192 temp = min; min = max; max = temp;
193 temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx;
194 }
195 }
196 }
197 break;
198 default:
199 {
200 val = n;
201 val_idx = j;
202 }
203 break;
204 }
205 }
206 }
207 return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) );
208 }
209
210
211 //------------------------------check_if_clipping------------------------------
212 // Helper function for RegionNode's identification of FP clipping
213 // Check that inputs to Region come from two IfNodes,
214 //
215 // If
216 // False True
217 // If |
218 // False True |
219 // | | |
220 // RegionNode_inputs
221 //
222 static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) {
223 top_if = nullptr;
224 bot_if = nullptr;
225
226 // Check control structure above RegionNode for (if ( if ) )
227 Node *in1 = region->in(1);
228 Node *in2 = region->in(2);
229 Node *in3 = region->in(3);
230 // Check that all inputs are projections
231 if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) {
232 Node *in10 = in1->in(0);
233 Node *in20 = in2->in(0);
234 Node *in30 = in3->in(0);
235 // Check that #1 and #2 are ifTrue and ifFalse from same If
236 if( in10 != nullptr && in10->is_If() &&
237 in20 != nullptr && in20->is_If() &&
238 in30 != nullptr && in30->is_If() && in10 == in20 &&
239 (in1->Opcode() != in2->Opcode()) ) {
240 Node *in100 = in10->in(0);
241 Node *in1000 = (in100 != nullptr && in100->is_Proj()) ? in100->in(0) : nullptr;
242 // Check that control for in10 comes from other branch of IF from in3
243 if( in1000 != nullptr && in1000->is_If() &&
244 in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) {
245 // Control pattern checks
246 top_if = (IfNode*)in1000;
247 bot_if = (IfNode*)in10;
248 }
249 }
250 }
251
252 return (top_if != nullptr);
253 }
254
255
256 //------------------------------check_convf2i_clipping-------------------------
257 // Helper function for RegionNode's identification of FP clipping
258 // Verify that the value input to the phi comes from "ConvF2I; LShift; RShift"
259 static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) {
260 convf2i = nullptr;
261
262 // Check for the RShiftNode
263 Node *rshift = phi->in(idx);
264 assert( rshift, "Previous checks ensure phi input is present");
265 if( rshift->Opcode() != Op_RShiftI ) { return false; }
266
267 // Check for the LShiftNode
268 Node *lshift = rshift->in(1);
269 assert( lshift, "Previous checks ensure phi input is present");
270 if( lshift->Opcode() != Op_LShiftI ) { return false; }
271
272 // Check for the ConvF2INode
273 Node *conv = lshift->in(1);
274 if( conv->Opcode() != Op_ConvF2I ) { return false; }
275
276 // Check that shift amounts are only to get sign bits set after F2I
277 jint max_cutoff = max->get_int();
278 jint min_cutoff = min->get_int();
279 jint left_shift = lshift->in(2)->get_int();
280 jint right_shift = rshift->in(2)->get_int();
281 jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1);
282 if( left_shift != right_shift ||
283 0 > left_shift || left_shift >= BitsPerJavaInteger ||
284 max_post_shift < max_cutoff ||
285 max_post_shift < -min_cutoff ) {
286 // Shifts are necessary but current transformation eliminates them
287 return false;
288 }
289
290 // OK to return the result of ConvF2I without shifting
291 convf2i = (ConvF2INode*)conv;
292 return true;
293 }
294
295
296 //------------------------------check_compare_clipping-------------------------
297 // Helper function for RegionNode's identification of FP clipping
298 static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) {
299 Node *i1 = iff->in(1);
300 if ( !i1->is_Bool() ) { return false; }
301 BoolNode *bool1 = i1->as_Bool();
302 if( less_than && bool1->_test._test != BoolTest::le ) { return false; }
303 else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; }
304 const Node *cmpF = bool1->in(1);
305 if( cmpF->Opcode() != Op_CmpF ) { return false; }
306 // Test that the float value being compared against
307 // is equivalent to the int value used as a limit
308 Node *nodef = cmpF->in(2);
309 if( nodef->Opcode() != Op_ConF ) { return false; }
310 jfloat conf = nodef->getf();
311 jint coni = limit->get_int();
312 if( ((int)conf) != coni ) { return false; }
313 input = cmpF->in(1);
314 return true;
315 }
316
317 //------------------------------is_unreachable_region--------------------------
318 // Check if the RegionNode is part of an unsafe loop and unreachable from root.
319 bool RegionNode::is_unreachable_region(const PhaseGVN* phase) {
320 Node* top = phase->C->top();
321 assert(req() == 2 || (req() == 3 && in(1) != nullptr && in(2) == top), "sanity check arguments");
322 if (_is_unreachable_region) {
323 // Return cached result from previous evaluation which should still be valid
324 assert(is_unreachable_from_root(phase), "walk the graph again and check if its indeed unreachable");
325 return true;
326 }
327
328 // First, cut the simple case of fallthrough region when NONE of
329 // region's phis references itself directly or through a data node.
330 if (is_possible_unsafe_loop(phase)) {
331 // If we have a possible unsafe loop, check if the region node is actually unreachable from root.
332 if (is_unreachable_from_root(phase)) {
333 _is_unreachable_region = true;
334 return true;
335 }
336 }
337 return false;
338 }
339
340 bool RegionNode::is_possible_unsafe_loop(const PhaseGVN* phase) const {
341 uint max = outcnt();
342 uint i;
343 for (i = 0; i < max; i++) {
344 Node* n = raw_out(i);
345 if (n != nullptr && n->is_Phi()) {
346 PhiNode* phi = n->as_Phi();
347 assert(phi->in(0) == this, "sanity check phi");
348 if (phi->outcnt() == 0) {
349 continue; // Safe case - no loops
350 }
351 if (phi->outcnt() == 1) {
352 Node* u = phi->raw_out(0);
353 // Skip if only one use is an other Phi or Call or Uncommon trap.
354 // It is safe to consider this case as fallthrough.
355 if (u != nullptr && (u->is_Phi() || u->is_CFG())) {
356 continue;
357 }
358 }
359 // Check when phi references itself directly or through an other node.
360 if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe) {
361 break; // Found possible unsafe data loop.
362 }
363 }
364 }
365 if (i >= max) {
366 return false; // An unsafe case was NOT found - don't need graph walk.
367 }
368 return true;
369 }
370
371 bool RegionNode::is_unreachable_from_root(const PhaseGVN* phase) const {
372 ResourceMark rm;
373 Node_List nstack;
374 VectorSet visited;
375
376 // Mark all control nodes reachable from root outputs
377 Node* n = (Node*)phase->C->root();
378 nstack.push(n);
379 visited.set(n->_idx);
380 while (nstack.size() != 0) {
381 n = nstack.pop();
382 uint max = n->outcnt();
383 for (uint i = 0; i < max; i++) {
384 Node* m = n->raw_out(i);
385 if (m != nullptr && m->is_CFG()) {
386 if (m == this) {
387 return false; // We reached the Region node - it is not dead.
388 }
389 if (!visited.test_set(m->_idx))
390 nstack.push(m);
391 }
392 }
393 }
394 return true; // The Region node is unreachable - it is dead.
395 }
396
397 #ifdef ASSERT
398 // Is this region in an infinite subgraph?
399 // (no path to root except through false NeverBranch exit)
400 bool RegionNode::is_in_infinite_subgraph() {
401 ResourceMark rm;
402 Unique_Node_List worklist;
403 worklist.push(this);
404 return RegionNode::are_all_nodes_in_infinite_subgraph(worklist);
405 }
406
407 // Are all nodes in worklist in infinite subgraph?
408 // (no path to root except through false NeverBranch exit)
409 // worklist is directly used for the traversal
410 bool RegionNode::are_all_nodes_in_infinite_subgraph(Unique_Node_List& worklist) {
411 // BFS traversal down the CFG, except through NeverBranch exits
412 for (uint i = 0; i < worklist.size(); ++i) {
413 Node* n = worklist.at(i);
414 assert(n->is_CFG(), "only traverse CFG");
415 if (n->is_Root()) {
416 // Found root -> there was an exit!
417 return false;
418 } else if (n->is_NeverBranch()) {
419 // Only follow the loop-internal projection, not the NeverBranch exit
420 ProjNode* proj = n->as_NeverBranch()->proj_out_or_null(0);
421 assert(proj != nullptr, "must find loop-internal projection of NeverBranch");
422 worklist.push(proj);
423 } else {
424 // Traverse all CFG outputs
425 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
426 Node* use = n->fast_out(i);
427 if (use->is_CFG()) {
428 worklist.push(use);
429 }
430 }
431 }
432 }
433 // No exit found for any loop -> all are infinite
434 return true;
435 }
436 #endif //ASSERT
437
438 void RegionNode::set_loop_status(RegionNode::LoopStatus status) {
439 assert(loop_status() == RegionNode::LoopStatus::NeverIrreducibleEntry, "why set our status again?");
440 _loop_status = status;
441 }
442
443 #ifdef ASSERT
444 void RegionNode::verify_can_be_irreducible_entry() const {
445 assert(loop_status() == RegionNode::LoopStatus::MaybeIrreducibleEntry, "must be marked irreducible");
446 assert(!is_Loop(), "LoopNode cannot be irreducible loop entry");
447 }
448 #endif //ASSERT
449
450 void RegionNode::try_clean_mem_phis(PhaseIterGVN* igvn) {
451 // Incremental inlining + PhaseStringOpts sometimes produce:
452 //
453 // cmpP with 1 top input
454 // |
455 // If
456 // / \
457 // IfFalse IfTrue /- Some Node
458 // \ / / /
459 // Region / /-MergeMem
460 // \---Phi
461 //
462 //
463 // It's expected by PhaseStringOpts that the Region goes away and is
464 // replaced by If's control input but because there's still a Phi,
465 // the Region stays in the graph. The top input from the cmpP is
466 // propagated forward and a subgraph that is useful goes away. The
467 // code in PhiNode::try_clean_memory_phi() replaces the Phi with the
468 // MergeMem in order to remove the Region if its last phi dies.
469
470 if (!is_diamond()) {
471 return;
472 }
473
474 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
475 Node* phi = fast_out(i);
476 if (phi->is_Phi() && phi->as_Phi()->try_clean_memory_phi(igvn)) {
477 --i;
478 --imax;
479 }
480 }
481 }
482
483 // Does this region merge a simple diamond formed by a proper IfNode?
484 //
485 // Cmp
486 // /
487 // ctrl Bool
488 // \ /
489 // IfNode
490 // / \
491 // IfFalse IfTrue
492 // \ /
493 // Region
494 bool RegionNode::is_diamond() const {
495 if (req() != 3) {
496 return false;
497 }
498
499 Node* left_path = in(1);
500 Node* right_path = in(2);
501 if (left_path == nullptr || right_path == nullptr) {
502 return false;
503 }
504 Node* diamond_if = left_path->in(0);
505 if (diamond_if == nullptr || !diamond_if->is_If() || diamond_if != right_path->in(0)) {
506 // Not an IfNode merging a diamond or TOP.
507 return false;
508 }
509
510 // Check for a proper bool/cmp
511 const Node* bol = diamond_if->in(1);
512 if (!bol->is_Bool()) {
513 return false;
514 }
515 const Node* cmp = bol->in(1);
516 if (!cmp->is_Cmp()) {
517 return false;
518 }
519 return true;
520 }
521 //------------------------------Ideal------------------------------------------
522 // Return a node which is more "ideal" than the current node. Must preserve
523 // the CFG, but we can still strip out dead paths.
524 Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) {
525 if( !can_reshape && !in(0) ) return nullptr; // Already degraded to a Copy
526 assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge");
527
528 // Check for RegionNode with no Phi users and both inputs come from either
529 // arm of the same IF. If found, then the control-flow split is useless.
530 bool has_phis = false;
531 if (can_reshape) { // Need DU info to check for Phi users
532 try_clean_mem_phis(phase->is_IterGVN());
533 has_phis = (has_phi() != nullptr); // Cache result
534
535 if (!has_phis) { // No Phi users? Nothing merging?
536 for (uint i = 1; i < req()-1; i++) {
537 Node *if1 = in(i);
538 if( !if1 ) continue;
539 Node *iff = if1->in(0);
540 if( !iff || !iff->is_If() ) continue;
541 for( uint j=i+1; j<req(); j++ ) {
542 if( in(j) && in(j)->in(0) == iff &&
543 if1->Opcode() != in(j)->Opcode() ) {
544 // Add the IF Projections to the worklist. They (and the IF itself)
545 // will be eliminated if dead.
546 phase->is_IterGVN()->add_users_to_worklist(iff);
547 set_req(i, iff->in(0));// Skip around the useless IF diamond
548 set_req(j, nullptr);
549 return this; // Record progress
550 }
551 }
552 }
553 }
554 }
555
556 // Remove TOP or null input paths. If only 1 input path remains, this Region
557 // degrades to a copy.
558 bool add_to_worklist = true;
559 bool modified = false;
560 int cnt = 0; // Count of values merging
561 DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count
562 DEBUG_ONLY( uint outcnt_orig = outcnt(); )
563 int del_it = 0; // The last input path we delete
564 bool found_top = false; // irreducible loops need to check reachability if we find TOP
565 // For all inputs...
566 for( uint i=1; i<req(); ++i ){// For all paths in
567 Node *n = in(i); // Get the input
568 if( n != nullptr ) {
569 // Remove useless control copy inputs
570 if( n->is_Region() && n->as_Region()->is_copy() ) {
571 set_req(i, n->nonnull_req());
572 modified = true;
573 i--;
574 continue;
575 }
576 if( n->is_Proj() ) { // Remove useless rethrows
577 Node *call = n->in(0);
578 if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) {
579 set_req(i, call->in(0));
580 modified = true;
581 i--;
582 continue;
583 }
584 }
585 if( phase->type(n) == Type::TOP ) {
586 set_req_X(i, nullptr, phase); // Ignore TOP inputs
587 modified = true;
588 found_top = true;
589 i--;
590 continue;
591 }
592 cnt++; // One more value merging
593 } else if (can_reshape) { // Else found dead path with DU info
594 PhaseIterGVN *igvn = phase->is_IterGVN();
595 del_req(i); // Yank path from self
596 del_it = i;
597
598 for (DUIterator_Fast jmax, j = fast_outs(jmax); j < jmax; j++) {
599 Node* use = fast_out(j);
600
601 if (use->req() != req() && use->is_Phi()) {
602 assert(use->in(0) == this, "unexpected control input");
603 igvn->hash_delete(use); // Yank from hash before hacking edges
604 use->set_req_X(i, nullptr, igvn);// Correct DU info
605 use->del_req(i); // Yank path from Phis
606 }
607 }
608
609 if (add_to_worklist) {
610 igvn->add_users_to_worklist(this);
611 add_to_worklist = false;
612 }
613
614 i--;
615 }
616 }
617
618 assert(outcnt() == outcnt_orig, "not expect to remove any use");
619
620 if (can_reshape && found_top && loop_status() == RegionNode::LoopStatus::MaybeIrreducibleEntry) {
621 // Is it a dead irreducible loop?
622 // If an irreducible loop loses one of the multiple entries
623 // that went into the loop head, or any secondary entries,
624 // we need to verify if the irreducible loop is still reachable,
625 // as the special logic in is_unreachable_region only works
626 // for reducible loops.
627 if (is_unreachable_from_root(phase)) {
628 // The irreducible loop is dead - must remove it
629 PhaseIterGVN* igvn = phase->is_IterGVN();
630 remove_unreachable_subgraph(igvn);
631 return nullptr;
632 }
633 } else if (can_reshape && cnt == 1) {
634 // Is it dead loop?
635 // If it is LoopNopde it had 2 (+1 itself) inputs and
636 // one of them was cut. The loop is dead if it was EntryContol.
637 // Loop node may have only one input because entry path
638 // is removed in PhaseIdealLoop::Dominators().
639 assert(!this->is_Loop() || cnt_orig <= 3, "Loop node should have 3 or less inputs");
640 if ((this->is_Loop() && (del_it == LoopNode::EntryControl ||
641 (del_it == 0 && is_unreachable_region(phase)))) ||
642 (!this->is_Loop() && has_phis && is_unreachable_region(phase))) {
643 PhaseIterGVN* igvn = phase->is_IterGVN();
644 remove_unreachable_subgraph(igvn);
645 return nullptr;
646 }
647 }
648
649 if( cnt <= 1 ) { // Only 1 path in?
650 set_req(0, nullptr); // Null control input for region copy
651 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is.
652 // No inputs or all inputs are null.
653 return nullptr;
654 } else if (can_reshape) { // Optimization phase - remove the node
655 PhaseIterGVN *igvn = phase->is_IterGVN();
656 // Strip mined (inner) loop is going away, remove outer loop.
657 if (is_CountedLoop() &&
658 as_Loop()->is_strip_mined()) {
659 Node* outer_sfpt = as_CountedLoop()->outer_safepoint();
660 Node* outer_out = as_CountedLoop()->outer_loop_exit();
661 if (outer_sfpt != nullptr && outer_out != nullptr) {
662 Node* in = outer_sfpt->in(0);
663 igvn->replace_node(outer_out, in);
664 LoopNode* outer = as_CountedLoop()->outer_loop();
665 igvn->replace_input_of(outer, LoopNode::LoopBackControl, igvn->C->top());
666 }
667 }
668 if (is_CountedLoop()) {
669 Node* opaq = as_CountedLoop()->is_canonical_loop_entry();
670 if (opaq != nullptr) {
671 // 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
672 // subject to further loop opts.
673 assert(opaq->Opcode() == Op_OpaqueZeroTripGuard, "");
674 igvn->replace_node(opaq, opaq->in(1));
675 }
676 }
677 Node *parent_ctrl;
678 if( cnt == 0 ) {
679 assert( req() == 1, "no inputs expected" );
680 // During IGVN phase such region will be subsumed by TOP node
681 // so region's phis will have TOP as control node.
682 // Kill phis here to avoid it.
683 // Also set other user's input to top.
684 parent_ctrl = phase->C->top();
685 } else {
686 // The fallthrough case since we already checked dead loops above.
687 parent_ctrl = in(1);
688 assert(parent_ctrl != nullptr, "Region is a copy of some non-null control");
689 assert(parent_ctrl != this, "Close dead loop");
690 }
691 if (add_to_worklist) {
692 igvn->add_users_to_worklist(this); // Check for further allowed opts
693 }
694 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
695 Node* n = last_out(i);
696 igvn->hash_delete(n); // Remove from worklist before modifying edges
697 if (n->outcnt() == 0) {
698 int uses_found = n->replace_edge(this, phase->C->top(), igvn);
699 if (uses_found > 1) { // (--i) done at the end of the loop.
700 i -= (uses_found - 1);
701 }
702 continue;
703 }
704 if( n->is_Phi() ) { // Collapse all Phis
705 // Eagerly replace phis to avoid regionless phis.
706 Node* in;
707 if( cnt == 0 ) {
708 assert( n->req() == 1, "No data inputs expected" );
709 in = parent_ctrl; // replaced by top
710 } else {
711 assert( n->req() == 2 && n->in(1) != nullptr, "Only one data input expected" );
712 in = n->in(1); // replaced by unique input
713 if( n->as_Phi()->is_unsafe_data_reference(in) )
714 in = phase->C->top(); // replaced by top
715 }
716 igvn->replace_node(n, in);
717 }
718 else if( n->is_Region() ) { // Update all incoming edges
719 assert(n != this, "Must be removed from DefUse edges");
720 int uses_found = n->replace_edge(this, parent_ctrl, igvn);
721 if (uses_found > 1) { // (--i) done at the end of the loop.
722 i -= (uses_found - 1);
723 }
724 }
725 else {
726 assert(n->in(0) == this, "Expect RegionNode to be control parent");
727 n->set_req(0, parent_ctrl);
728 }
729 #ifdef ASSERT
730 for( uint k=0; k < n->req(); k++ ) {
731 assert(n->in(k) != this, "All uses of RegionNode should be gone");
732 }
733 #endif
734 }
735 // Remove the RegionNode itself from DefUse info
736 igvn->remove_dead_node(this);
737 return nullptr;
738 }
739 return this; // Record progress
740 }
741
742
743 // If a Region flows into a Region, merge into one big happy merge.
744 if (can_reshape) {
745 Node *m = merge_region(this, phase);
746 if (m != nullptr) return m;
747 }
748
749 // Check if this region is the root of a clipping idiom on floats
750 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
751 // Check that only one use is a Phi and that it simplifies to two constants +
752 PhiNode* phi = has_unique_phi();
753 if (phi != nullptr) { // One Phi user
754 // Check inputs to the Phi
755 ConNode *min;
756 ConNode *max;
757 Node *val;
758 uint min_idx;
759 uint max_idx;
760 uint val_idx;
761 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) {
762 IfNode *top_if;
763 IfNode *bot_if;
764 if( check_if_clipping( this, bot_if, top_if ) ) {
765 // Control pattern checks, now verify compares
766 Node *top_in = nullptr; // value being compared against
767 Node *bot_in = nullptr;
768 if( check_compare_clipping( true, bot_if, min, bot_in ) &&
769 check_compare_clipping( false, top_if, max, top_in ) ) {
770 if( bot_in == top_in ) {
771 PhaseIterGVN *gvn = phase->is_IterGVN();
772 assert( gvn != nullptr, "Only had DefUse info in IterGVN");
773 // Only remaining check is that bot_in == top_in == (Phi's val + mods)
774
775 // Check for the ConvF2INode
776 ConvF2INode *convf2i;
777 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
778 convf2i->in(1) == bot_in ) {
779 // Matched pattern, including LShiftI; RShiftI, replace with integer compares
780 // max test
781 Node *cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, min ));
782 Node *boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::lt ));
783 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt ));
784 Node *if_min= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
785 Node *ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
786 // min test
787 cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, max ));
788 boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::gt ));
789 iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
790 Node *if_max= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
791 ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
792 // update input edges to region node
793 set_req_X( min_idx, if_min, gvn );
794 set_req_X( max_idx, if_max, gvn );
795 set_req_X( val_idx, ifF, gvn );
796 // remove unnecessary 'LShiftI; RShiftI' idiom
797 gvn->hash_delete(phi);
798 phi->set_req_X( val_idx, convf2i, gvn );
799 gvn->hash_find_insert(phi);
800 // Return transformed region node
801 return this;
802 }
803 }
804 }
805 }
806 }
807 }
808 }
809
810 if (can_reshape) {
811 modified |= optimize_trichotomy(phase->is_IterGVN());
812 }
813
814 return modified ? this : nullptr;
815 }
816
817 //--------------------------remove_unreachable_subgraph----------------------
818 // This region and therefore all nodes on the input control path(s) are unreachable
819 // from root. To avoid incomplete removal of unreachable subgraphs, walk up the CFG
820 // and aggressively replace all nodes by top.
821 // If a control node "def" with a single control output "use" has its single output
822 // "use" replaced with top, then "use" removes itself. This has the consequence that
823 // when we visit "use", it already has all inputs removed. They are lost and we cannot
824 // traverse them. This is why we fist find all unreachable nodes, and then remove
825 // them in a second step.
826 void RegionNode::remove_unreachable_subgraph(PhaseIterGVN* igvn) {
827 Node* top = igvn->C->top();
828 ResourceMark rm;
829 Unique_Node_List unreachable; // visit each only once
830 unreachable.push(this);
831 // Recursively find all control inputs.
832 for (uint i = 0; i < unreachable.size(); i++) {
833 Node* n = unreachable.at(i);
834 for (uint i = 0; i < n->req(); ++i) {
835 Node* m = n->in(i);
836 assert(m == nullptr || !m->is_Root(), "Should be unreachable from root");
837 if (m != nullptr && m->is_CFG()) {
838 unreachable.push(m);
839 }
840 }
841 }
842 // Remove all unreachable nodes.
843 for (uint i = 0; i < unreachable.size(); i++) {
844 Node* n = unreachable.at(i);
845 if (n->is_Region()) {
846 // Eagerly replace phis with top to avoid regionless phis.
847 n->set_req(0, nullptr);
848 bool progress = true;
849 uint max = n->outcnt();
850 DUIterator j;
851 while (progress) {
852 progress = false;
853 for (j = n->outs(); n->has_out(j); j++) {
854 Node* u = n->out(j);
855 if (u->is_Phi()) {
856 igvn->replace_node(u, top);
857 if (max != n->outcnt()) {
858 progress = true;
859 j = n->refresh_out_pos(j);
860 max = n->outcnt();
861 }
862 }
863 }
864 }
865 }
866 igvn->replace_node(n, top);
867 }
868 }
869
870 //------------------------------optimize_trichotomy--------------------------
871 // Optimize nested comparisons of the following kind:
872 //
873 // int compare(int a, int b) {
874 // return (a < b) ? -1 : (a == b) ? 0 : 1;
875 // }
876 //
877 // Shape 1:
878 // if (compare(a, b) == 1) { ... } -> if (a > b) { ... }
879 //
880 // Shape 2:
881 // if (compare(a, b) == 0) { ... } -> if (a == b) { ... }
882 //
883 // Above code leads to the following IR shapes where both Ifs compare the
884 // same value and two out of three region inputs idx1 and idx2 map to
885 // the same value and control flow.
886 //
887 // (1) If (2) If
888 // / \ / \
889 // Proj Proj Proj Proj
890 // | \ | \
891 // | If | If If
892 // | / \ | / \ / \
893 // | Proj Proj | Proj Proj ==> Proj Proj
894 // | / / \ | / | /
895 // Region / \ | / | /
896 // \ / \ | / | /
897 // Region Region Region
898 //
899 // The method returns true if 'this' is modified and false otherwise.
900 bool RegionNode::optimize_trichotomy(PhaseIterGVN* igvn) {
901 int idx1 = 1, idx2 = 2;
902 Node* region = nullptr;
903 if (req() == 3 && in(1) != nullptr && in(2) != nullptr) {
904 // Shape 1: Check if one of the inputs is a region that merges two control
905 // inputs and has no other users (especially no Phi users).
906 region = in(1)->isa_Region() ? in(1) : in(2)->isa_Region();
907 if (region == nullptr || region->outcnt() != 2 || region->req() != 3) {
908 return false; // No suitable region input found
909 }
910 } else if (req() == 4) {
911 // Shape 2: Check if two control inputs map to the same value of the unique phi
912 // user and treat these as if they would come from another region (shape (1)).
913 PhiNode* phi = has_unique_phi();
914 if (phi == nullptr) {
915 return false; // No unique phi user
916 }
917 if (phi->in(idx1) != phi->in(idx2)) {
918 idx2 = 3;
919 if (phi->in(idx1) != phi->in(idx2)) {
920 idx1 = 2;
921 if (phi->in(idx1) != phi->in(idx2)) {
922 return false; // No equal phi inputs found
923 }
924 }
925 }
926 assert(phi->in(idx1) == phi->in(idx2), "must be"); // Region is merging same value
927 region = this;
928 }
929 if (region == nullptr || region->in(idx1) == nullptr || region->in(idx2) == nullptr) {
930 return false; // Region does not merge two control inputs
931 }
932 // At this point we know that region->in(idx1) and region->(idx2) map to the same
933 // value and control flow. Now search for ifs that feed into these region inputs.
934 ProjNode* proj1 = region->in(idx1)->isa_Proj();
935 ProjNode* proj2 = region->in(idx2)->isa_Proj();
936 if (proj1 == nullptr || proj1->outcnt() != 1 ||
937 proj2 == nullptr || proj2->outcnt() != 1) {
938 return false; // No projection inputs with region as unique user found
939 }
940 assert(proj1 != proj2, "should be different projections");
941 IfNode* iff1 = proj1->in(0)->isa_If();
942 IfNode* iff2 = proj2->in(0)->isa_If();
943 if (iff1 == nullptr || iff1->outcnt() != 2 ||
944 iff2 == nullptr || iff2->outcnt() != 2) {
945 return false; // No ifs found
946 }
947 if (iff1 == iff2) {
948 igvn->add_users_to_worklist(iff1); // Make sure dead if is eliminated
949 igvn->replace_input_of(region, idx1, iff1->in(0));
950 igvn->replace_input_of(region, idx2, igvn->C->top());
951 return (region == this); // Remove useless if (both projections map to the same control/value)
952 }
953 BoolNode* bol1 = iff1->in(1)->isa_Bool();
954 BoolNode* bol2 = iff2->in(1)->isa_Bool();
955 if (bol1 == nullptr || bol2 == nullptr) {
956 return false; // No bool inputs found
957 }
958 Node* cmp1 = bol1->in(1);
959 Node* cmp2 = bol2->in(1);
960 bool commute = false;
961 if (!cmp1->is_Cmp() || !cmp2->is_Cmp()) {
962 return false; // No comparison
963 } else if (cmp1->Opcode() == Op_CmpF || cmp1->Opcode() == Op_CmpD ||
964 cmp2->Opcode() == Op_CmpF || cmp2->Opcode() == Op_CmpD ||
965 cmp1->Opcode() == Op_CmpP || cmp1->Opcode() == Op_CmpN ||
966 cmp2->Opcode() == Op_CmpP || cmp2->Opcode() == Op_CmpN ||
967 cmp1->is_SubTypeCheck() || cmp2->is_SubTypeCheck()) {
968 // Floats and pointers don't exactly obey trichotomy. To be on the safe side, don't transform their tests.
969 // SubTypeCheck is not commutative
970 return false;
971 } else if (cmp1 != cmp2) {
972 if (cmp1->in(1) == cmp2->in(2) &&
973 cmp1->in(2) == cmp2->in(1)) {
974 commute = true; // Same but swapped inputs, commute the test
975 } else {
976 return false; // Ifs are not comparing the same values
977 }
978 }
979 proj1 = proj1->other_if_proj();
980 proj2 = proj2->other_if_proj();
981 if (!((proj1->unique_ctrl_out_or_null() == iff2 &&
982 proj2->unique_ctrl_out_or_null() == this) ||
983 (proj2->unique_ctrl_out_or_null() == iff1 &&
984 proj1->unique_ctrl_out_or_null() == this))) {
985 return false; // Ifs are not connected through other projs
986 }
987 // Found 'iff -> proj -> iff -> proj -> this' shape where all other projs are merged
988 // through 'region' and map to the same value. Merge the boolean tests and replace
989 // the ifs by a single comparison.
990 BoolTest test1 = (proj1->_con == 1) ? bol1->_test : bol1->_test.negate();
991 BoolTest test2 = (proj2->_con == 1) ? bol2->_test : bol2->_test.negate();
992 test1 = commute ? test1.commute() : test1;
993 // After possibly commuting test1, if we can merge test1 & test2, then proj2/iff2/bol2 are the nodes to refine.
994 BoolTest::mask res = test1.merge(test2);
995 if (res == BoolTest::illegal) {
996 return false; // Unable to merge tests
997 }
998 // Adjust iff1 to always pass (only iff2 will remain)
999 igvn->replace_input_of(iff1, 1, igvn->intcon(proj1->_con));
1000 if (res == BoolTest::never) {
1001 // Merged test is always false, adjust iff2 to always fail
1002 igvn->replace_input_of(iff2, 1, igvn->intcon(1 - proj2->_con));
1003 } else {
1004 // Replace bool input of iff2 with merged test
1005 BoolNode* new_bol = new BoolNode(bol2->in(1), res);
1006 igvn->replace_input_of(iff2, 1, igvn->transform((proj2->_con == 1) ? new_bol : new_bol->negate(igvn)));
1007 if (new_bol->outcnt() == 0) {
1008 igvn->remove_dead_node(new_bol);
1009 }
1010 }
1011 return false;
1012 }
1013
1014 const RegMask &RegionNode::out_RegMask() const {
1015 return RegMask::Empty;
1016 }
1017
1018 #ifndef PRODUCT
1019 void RegionNode::dump_spec(outputStream* st) const {
1020 Node::dump_spec(st);
1021 switch (loop_status()) {
1022 case RegionNode::LoopStatus::MaybeIrreducibleEntry:
1023 st->print("#irreducible ");
1024 break;
1025 case RegionNode::LoopStatus::Reducible:
1026 st->print("#reducible ");
1027 break;
1028 case RegionNode::LoopStatus::NeverIrreducibleEntry:
1029 break; // nothing
1030 }
1031 }
1032 #endif
1033
1034 // Find the one non-null required input. RegionNode only
1035 Node *Node::nonnull_req() const {
1036 assert( is_Region(), "" );
1037 for( uint i = 1; i < _cnt; i++ )
1038 if( in(i) )
1039 return in(i);
1040 ShouldNotReachHere();
1041 return nullptr;
1042 }
1043
1044
1045 //=============================================================================
1046 // note that these functions assume that the _adr_type field is flattened
1047 uint PhiNode::hash() const {
1048 const Type* at = _adr_type;
1049 return TypeNode::hash() + (at ? at->hash() : 0);
1050 }
1051 bool PhiNode::cmp( const Node &n ) const {
1052 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
1053 }
1054 static inline
1055 const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
1056 if (at == nullptr || at == TypePtr::BOTTOM) return at;
1057 return Compile::current()->alias_type(at)->adr_type();
1058 }
1059
1060 //----------------------------make---------------------------------------------
1061 // create a new phi with edges matching r and set (initially) to x
1062 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
1063 uint preds = r->req(); // Number of predecessor paths
1064 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at");
1065 PhiNode* p = new PhiNode(r, t, at);
1066 for (uint j = 1; j < preds; j++) {
1067 // Fill in all inputs, except those which the region does not yet have
1068 if (r->in(j) != nullptr)
1069 p->init_req(j, x);
1070 }
1071 return p;
1072 }
1073 PhiNode* PhiNode::make(Node* r, Node* x) {
1074 const Type* t = x->bottom_type();
1075 const TypePtr* at = nullptr;
1076 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
1077 return make(r, x, t, at);
1078 }
1079 PhiNode* PhiNode::make_blank(Node* r, Node* x) {
1080 const Type* t = x->bottom_type();
1081 const TypePtr* at = nullptr;
1082 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
1083 return new PhiNode(r, t, at);
1084 }
1085
1086
1087 //------------------------slice_memory-----------------------------------------
1088 // create a new phi with narrowed memory type
1089 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
1090 PhiNode* mem = (PhiNode*) clone();
1091 *(const TypePtr**)&mem->_adr_type = adr_type;
1092 // convert self-loops, or else we get a bad graph
1093 for (uint i = 1; i < req(); i++) {
1094 if ((const Node*)in(i) == this) mem->set_req(i, mem);
1095 }
1096 mem->verify_adr_type();
1097 return mem;
1098 }
1099
1100 //------------------------split_out_instance-----------------------------------
1101 // Split out an instance type from a bottom phi.
1102 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const {
1103 const TypeOopPtr *t_oop = at->isa_oopptr();
1104 assert(t_oop != nullptr && t_oop->is_known_instance(), "expecting instance oopptr");
1105
1106 // Check if an appropriate node already exists.
1107 Node *region = in(0);
1108 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) {
1109 Node* use = region->fast_out(k);
1110 if( use->is_Phi()) {
1111 PhiNode *phi2 = use->as_Phi();
1112 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) {
1113 return phi2;
1114 }
1115 }
1116 }
1117 Compile *C = igvn->C;
1118 Node_Array node_map;
1119 Node_Stack stack(C->live_nodes() >> 4);
1120 PhiNode *nphi = slice_memory(at);
1121 igvn->register_new_node_with_optimizer( nphi );
1122 node_map.map(_idx, nphi);
1123 stack.push((Node *)this, 1);
1124 while(!stack.is_empty()) {
1125 PhiNode *ophi = stack.node()->as_Phi();
1126 uint i = stack.index();
1127 assert(i >= 1, "not control edge");
1128 stack.pop();
1129 nphi = node_map[ophi->_idx]->as_Phi();
1130 for (; i < ophi->req(); i++) {
1131 Node *in = ophi->in(i);
1132 if (in == nullptr || igvn->type(in) == Type::TOP)
1133 continue;
1134 Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, nullptr, igvn);
1135 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : nullptr;
1136 if (optphi != nullptr && optphi->adr_type() == TypePtr::BOTTOM) {
1137 opt = node_map[optphi->_idx];
1138 if (opt == nullptr) {
1139 stack.push(ophi, i);
1140 nphi = optphi->slice_memory(at);
1141 igvn->register_new_node_with_optimizer( nphi );
1142 node_map.map(optphi->_idx, nphi);
1143 ophi = optphi;
1144 i = 0; // will get incremented at top of loop
1145 continue;
1146 }
1147 }
1148 nphi->set_req(i, opt);
1149 }
1150 }
1151 return nphi;
1152 }
1153
1154 //------------------------verify_adr_type--------------------------------------
1155 #ifdef ASSERT
1156 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
1157 if (visited.test_set(_idx)) return; //already visited
1158
1159 // recheck constructor invariants:
1160 verify_adr_type(false);
1161
1162 // recheck local phi/phi consistency:
1163 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
1164 "adr_type must be consistent across phi nest");
1165
1166 // walk around
1167 for (uint i = 1; i < req(); i++) {
1168 Node* n = in(i);
1169 if (n == nullptr) continue;
1170 const Node* np = in(i);
1171 if (np->is_Phi()) {
1172 np->as_Phi()->verify_adr_type(visited, at);
1173 } else if (n->bottom_type() == Type::TOP
1174 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
1175 // ignore top inputs
1176 } else {
1177 const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
1178 // recheck phi/non-phi consistency at leaves:
1179 assert((nat != nullptr) == (at != nullptr), "");
1180 assert(nat == at || nat == TypePtr::BOTTOM,
1181 "adr_type must be consistent at leaves of phi nest");
1182 }
1183 }
1184 }
1185
1186 // Verify a whole nest of phis rooted at this one.
1187 void PhiNode::verify_adr_type(bool recursive) const {
1188 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
1189 if (Node::in_dump()) return; // muzzle asserts when printing
1190
1191 assert((_type == Type::MEMORY) == (_adr_type != nullptr), "adr_type for memory phis only");
1192
1193 if (!VerifyAliases) return; // verify thoroughly only if requested
1194
1195 assert(_adr_type == flatten_phi_adr_type(_adr_type),
1196 "Phi::adr_type must be pre-normalized");
1197
1198 if (recursive) {
1199 VectorSet visited;
1200 verify_adr_type(visited, _adr_type);
1201 }
1202 }
1203 #endif
1204
1205
1206 //------------------------------Value------------------------------------------
1207 // Compute the type of the PhiNode
1208 const Type* PhiNode::Value(PhaseGVN* phase) const {
1209 Node *r = in(0); // RegionNode
1210 if( !r ) // Copy or dead
1211 return in(1) ? phase->type(in(1)) : Type::TOP;
1212
1213 // Note: During parsing, phis are often transformed before their regions.
1214 // This means we have to use type_or_null to defend against untyped regions.
1215 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1216 return Type::TOP;
1217
1218 // Check for trip-counted loop. If so, be smarter.
1219 BaseCountedLoopNode* l = r->is_BaseCountedLoop() ? r->as_BaseCountedLoop() : nullptr;
1220 if (l && ((const Node*)l->phi() == this)) { // Trip counted loop!
1221 // protect against init_trip() or limit() returning null
1222 if (l->can_be_counted_loop(phase)) {
1223 const Node* init = l->init_trip();
1224 const Node* limit = l->limit();
1225 const Node* stride = l->stride();
1226 if (init != nullptr && limit != nullptr && stride != nullptr) {
1227 const TypeInteger* lo = phase->type(init)->isa_integer(l->bt());
1228 const TypeInteger* hi = phase->type(limit)->isa_integer(l->bt());
1229 const TypeInteger* stride_t = phase->type(stride)->isa_integer(l->bt());
1230 if (lo != nullptr && hi != nullptr && stride_t != nullptr) { // Dying loops might have TOP here
1231 assert(stride_t->is_con(), "bad stride type");
1232 BoolTest::mask bt = l->loopexit()->test_trip();
1233 // If the loop exit condition is "not equal", the condition
1234 // would not trigger if init > limit (if stride > 0) or if
1235 // init < limit if (stride > 0) so we can't deduce bounds
1236 // for the iv from the exit condition.
1237 if (bt != BoolTest::ne) {
1238 jlong stride_con = stride_t->get_con_as_long(l->bt());
1239 if (stride_con < 0) { // Down-counter loop
1240 swap(lo, hi);
1241 jlong iv_range_lower_limit = lo->lo_as_long();
1242 // Prevent overflow when adding one below
1243 if (iv_range_lower_limit < max_signed_integer(l->bt())) {
1244 // The loop exit condition is: iv + stride > limit (iv is this Phi). So the loop iterates until
1245 // iv + stride <= limit
1246 // We know that: limit >= lo->lo_as_long() and stride <= -1
1247 // So when the loop exits, iv has to be at most lo->lo_as_long() + 1
1248 iv_range_lower_limit += 1; // lo is after decrement
1249 // Exact bounds for the phi can be computed when ABS(stride) greater than 1 if bounds are constant.
1250 if (lo->is_con() && hi->is_con() && hi->lo_as_long() > lo->hi_as_long() && stride_con != -1) {
1251 julong uhi = static_cast<julong>(hi->lo_as_long());
1252 julong ulo = static_cast<julong>(lo->hi_as_long());
1253 julong diff = ((uhi - ulo - 1) / (-stride_con)) * (-stride_con);
1254 julong ufirst = hi->lo_as_long() - diff;
1255 iv_range_lower_limit = reinterpret_cast<jlong &>(ufirst);
1256 assert(iv_range_lower_limit >= lo->lo_as_long() + 1, "should end up with narrower range");
1257 }
1258 }
1259 return TypeInteger::make(MIN2(iv_range_lower_limit, hi->lo_as_long()), hi->hi_as_long(), 3, l->bt())->filter_speculative(_type);
1260 } else if (stride_con >= 0) {
1261 jlong iv_range_upper_limit = hi->hi_as_long();
1262 // Prevent overflow when subtracting one below
1263 if (iv_range_upper_limit > min_signed_integer(l->bt())) {
1264 // The loop exit condition is: iv + stride < limit (iv is this Phi). So the loop iterates until
1265 // iv + stride >= limit
1266 // We know that: limit <= hi->hi_as_long() and stride >= 1
1267 // So when the loop exits, iv has to be at most hi->hi_as_long() - 1
1268 iv_range_upper_limit -= 1;
1269 // Exact bounds for the phi can be computed when ABS(stride) greater than 1 if bounds are constant.
1270 if (lo->is_con() && hi->is_con() && hi->lo_as_long() > lo->hi_as_long() && stride_con != 1) {
1271 julong uhi = static_cast<julong>(hi->lo_as_long());
1272 julong ulo = static_cast<julong>(lo->hi_as_long());
1273 julong diff = ((uhi - ulo - 1) / stride_con) * stride_con;
1274 julong ulast = lo->hi_as_long() + diff;
1275 iv_range_upper_limit = reinterpret_cast<jlong &>(ulast);
1276 assert(iv_range_upper_limit <= hi->hi_as_long() - 1, "should end up with narrower range");
1277 }
1278 }
1279 return TypeInteger::make(lo->lo_as_long(), MAX2(lo->hi_as_long(), iv_range_upper_limit), 3, l->bt())->filter_speculative(_type);
1280 }
1281 }
1282 }
1283 }
1284 } else if (l->in(LoopNode::LoopBackControl) != nullptr &&
1285 in(LoopNode::EntryControl) != nullptr &&
1286 phase->type(l->in(LoopNode::LoopBackControl)) == Type::TOP) {
1287 // During CCP, if we saturate the type of a counted loop's Phi
1288 // before the special code for counted loop above has a chance
1289 // to run (that is as long as the type of the backedge's control
1290 // is top), we might end up with non monotonic types
1291 return phase->type(in(LoopNode::EntryControl))->filter_speculative(_type);
1292 }
1293 }
1294
1295 // Default case: merge all inputs
1296 const Type *t = Type::TOP; // Merged type starting value
1297 for (uint i = 1; i < req(); ++i) {// For all paths in
1298 // Reachable control path?
1299 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
1300 const Type* ti = phase->type(in(i));
1301 t = t->meet_speculative(ti);
1302 }
1303 }
1304
1305 // The worst-case type (from ciTypeFlow) should be consistent with "t".
1306 // That is, we expect that "t->higher_equal(_type)" holds true.
1307 // There are various exceptions:
1308 // - Inputs which are phis might in fact be widened unnecessarily.
1309 // For example, an input might be a widened int while the phi is a short.
1310 // - Inputs might be BotPtrs but this phi is dependent on a null check,
1311 // and postCCP has removed the cast which encodes the result of the check.
1312 // - The type of this phi is an interface, and the inputs are classes.
1313 // - Value calls on inputs might produce fuzzy results.
1314 // (Occurrences of this case suggest improvements to Value methods.)
1315 //
1316 // It is not possible to see Type::BOTTOM values as phi inputs,
1317 // because the ciTypeFlow pre-pass produces verifier-quality types.
1318 const Type* ft = t->filter_speculative(_type); // Worst case type
1319
1320 #ifdef ASSERT
1321 // The following logic has been moved into TypeOopPtr::filter.
1322 const Type* jt = t->join_speculative(_type);
1323 if (jt->empty()) { // Emptied out???
1324 // Otherwise it's something stupid like non-overlapping int ranges
1325 // found on dying counted loops.
1326 assert(ft == Type::TOP, ""); // Canonical empty value
1327 }
1328
1329 else {
1330
1331 if (jt != ft && jt->base() == ft->base()) {
1332 if (jt->isa_int() &&
1333 jt->is_int()->_lo == ft->is_int()->_lo &&
1334 jt->is_int()->_hi == ft->is_int()->_hi)
1335 jt = ft;
1336 if (jt->isa_long() &&
1337 jt->is_long()->_lo == ft->is_long()->_lo &&
1338 jt->is_long()->_hi == ft->is_long()->_hi)
1339 jt = ft;
1340 }
1341 if (jt != ft) {
1342 tty->print("merge type: "); t->dump(); tty->cr();
1343 tty->print("kill type: "); _type->dump(); tty->cr();
1344 tty->print("join type: "); jt->dump(); tty->cr();
1345 tty->print("filter type: "); ft->dump(); tty->cr();
1346 }
1347 assert(jt == ft, "");
1348 }
1349 #endif //ASSERT
1350
1351 // Deal with conversion problems found in data loops.
1352 ft = phase->saturate_and_maybe_push_to_igvn_worklist(this, ft);
1353 return ft;
1354 }
1355
1356 // Does this Phi represent a simple well-shaped diamond merge? Return the
1357 // index of the true path or 0 otherwise.
1358 int PhiNode::is_diamond_phi() const {
1359 Node* region = in(0);
1360 assert(region != nullptr && region->is_Region(), "phi must have region");
1361 if (!region->as_Region()->is_diamond()) {
1362 return 0;
1363 }
1364
1365 if (region->in(1)->is_IfTrue()) {
1366 assert(region->in(2)->is_IfFalse(), "bad If");
1367 return 1;
1368 } else {
1369 // Flipped projections.
1370 assert(region->in(2)->is_IfTrue(), "bad If");
1371 return 2;
1372 }
1373 }
1374
1375 // Do the following transformation if we find the corresponding graph shape, remove the involved memory phi and return
1376 // true. Otherwise, return false if the transformation cannot be applied.
1377 //
1378 // If If
1379 // / \ / \
1380 // IfFalse IfTrue /- Some Node IfFalse IfTrue
1381 // \ / / / \ / Some Node
1382 // Region / /-MergeMem ===> Region |
1383 // / \---Phi | MergeMem
1384 // [other phis] \ [other phis] |
1385 // use use
1386 bool PhiNode::try_clean_memory_phi(PhaseIterGVN* igvn) {
1387 if (_type != Type::MEMORY) {
1388 return false;
1389 }
1390 assert(is_diamond_phi() > 0, "sanity");
1391 assert(req() == 3, "same as region");
1392 const Node* region = in(0);
1393 for (uint i = 1; i < 3; i++) {
1394 Node* phi_input = in(i);
1395 if (phi_input != nullptr && phi_input->is_MergeMem() && region->in(i)->outcnt() == 1) {
1396 // Nothing is control-dependent on path #i except the region itself.
1397 MergeMemNode* merge_mem = phi_input->as_MergeMem();
1398 uint j = 3 - i;
1399 Node* other_phi_input = in(j);
1400 if (other_phi_input != nullptr && other_phi_input == merge_mem->base_memory()) {
1401 // merge_mem is a successor memory to other_phi_input, and is not pinned inside the diamond, so push it out.
1402 // This will allow the diamond to collapse completely if there are no other phis left.
1403 igvn->replace_node(this, merge_mem);
1404 return true;
1405 }
1406 }
1407 }
1408 return false;
1409 }
1410 //----------------------------check_cmove_id-----------------------------------
1411 // Check for CMove'ing a constant after comparing against the constant.
1412 // Happens all the time now, since if we compare equality vs a constant in
1413 // the parser, we "know" the variable is constant on one path and we force
1414 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
1415 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more
1416 // general in that we don't need constants. Since CMove's are only inserted
1417 // in very special circumstances, we do it here on generic Phi's.
1418 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
1419 assert(true_path !=0, "only diamond shape graph expected");
1420
1421 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1422 // phi->region->if_proj->ifnode->bool->cmp
1423 Node* region = in(0);
1424 Node* iff = region->in(1)->in(0);
1425 BoolNode* b = iff->in(1)->as_Bool();
1426 Node* cmp = b->in(1);
1427 Node* tval = in(true_path);
1428 Node* fval = in(3-true_path);
1429 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
1430 if (id == nullptr)
1431 return nullptr;
1432
1433 // Either value might be a cast that depends on a branch of 'iff'.
1434 // Since the 'id' value will float free of the diamond, either
1435 // decast or return failure.
1436 Node* ctl = id->in(0);
1437 if (ctl != nullptr && ctl->in(0) == iff) {
1438 if (id->is_ConstraintCast()) {
1439 return id->in(1);
1440 } else {
1441 // Don't know how to disentangle this value.
1442 return nullptr;
1443 }
1444 }
1445
1446 return id;
1447 }
1448
1449 //------------------------------Identity---------------------------------------
1450 // Check for Region being Identity.
1451 Node* PhiNode::Identity(PhaseGVN* phase) {
1452 if (must_wait_for_region_in_irreducible_loop(phase)) {
1453 return this;
1454 }
1455 // Check for no merging going on
1456 // (There used to be special-case code here when this->region->is_Loop.
1457 // It would check for a tributary phi on the backedge that the main phi
1458 // trivially, perhaps with a single cast. The unique_input method
1459 // does all this and more, by reducing such tributaries to 'this'.)
1460 Node* uin = unique_input(phase, false);
1461 if (uin != nullptr) {
1462 return uin;
1463 }
1464
1465 int true_path = is_diamond_phi();
1466 // Delay CMove'ing identity if Ideal has not had the chance to handle unsafe cases, yet.
1467 if (true_path != 0 && !(phase->is_IterGVN() && wait_for_region_igvn(phase))) {
1468 Node* id = is_cmove_id(phase, true_path);
1469 if (id != nullptr) {
1470 return id;
1471 }
1472 }
1473
1474 // Looking for phis with identical inputs. If we find one that has
1475 // type TypePtr::BOTTOM, replace the current phi with the bottom phi.
1476 if (phase->is_IterGVN() && type() == Type::MEMORY && adr_type() !=
1477 TypePtr::BOTTOM && !adr_type()->is_known_instance()) {
1478 uint phi_len = req();
1479 Node* phi_reg = region();
1480 for (DUIterator_Fast imax, i = phi_reg->fast_outs(imax); i < imax; i++) {
1481 Node* u = phi_reg->fast_out(i);
1482 if (u->is_Phi() && u->as_Phi()->type() == Type::MEMORY &&
1483 u->adr_type() == TypePtr::BOTTOM && u->in(0) == phi_reg &&
1484 u->req() == phi_len) {
1485 for (uint j = 1; j < phi_len; j++) {
1486 if (in(j) != u->in(j)) {
1487 u = nullptr;
1488 break;
1489 }
1490 }
1491 if (u != nullptr) {
1492 return u;
1493 }
1494 }
1495 }
1496 }
1497
1498 return this; // No identity
1499 }
1500
1501 //-----------------------------unique_input------------------------------------
1502 // Find the unique value, discounting top, self-loops, and casts.
1503 // Return top if there are no inputs, and self if there are multiple.
1504 Node* PhiNode::unique_input(PhaseValues* phase, bool uncast) {
1505 // 1) One unique direct input,
1506 // or if uncast is true:
1507 // 2) some of the inputs have an intervening ConstraintCast
1508 // 3) an input is a self loop
1509 //
1510 // 1) input or 2) input or 3) input __
1511 // / \ / \ \ / \
1512 // \ / | cast phi cast
1513 // phi \ / / \ /
1514 // phi / --
1515
1516 Node* r = in(0); // RegionNode
1517 Node* input = nullptr; // The unique direct input (maybe uncasted = ConstraintCasts removed)
1518
1519 for (uint i = 1, cnt = req(); i < cnt; ++i) {
1520 Node* rc = r->in(i);
1521 if (rc == nullptr || phase->type(rc) == Type::TOP)
1522 continue; // ignore unreachable control path
1523 Node* n = in(i);
1524 if (n == nullptr)
1525 continue;
1526 Node* un = n;
1527 if (uncast) {
1528 #ifdef ASSERT
1529 Node* m = un->uncast();
1530 #endif
1531 while (un != nullptr && un->req() == 2 && un->is_ConstraintCast()) {
1532 Node* next = un->in(1);
1533 if (phase->type(next)->isa_rawptr() && phase->type(un)->isa_oopptr()) {
1534 // risk exposing raw ptr at safepoint
1535 break;
1536 }
1537 un = next;
1538 }
1539 assert(m == un || un->in(1) == m, "Only expected at CheckCastPP from allocation");
1540 }
1541 if (un == nullptr || un == this || phase->type(un) == Type::TOP) {
1542 continue; // ignore if top, or in(i) and "this" are in a data cycle
1543 }
1544 // Check for a unique input (maybe uncasted)
1545 if (input == nullptr) {
1546 input = un;
1547 } else if (input != un) {
1548 input = NodeSentinel; // no unique input
1549 }
1550 }
1551 if (input == nullptr) {
1552 return phase->C->top(); // no inputs
1553 }
1554
1555 if (input != NodeSentinel) {
1556 return input; // one unique direct input
1557 }
1558
1559 // Nothing.
1560 return nullptr;
1561 }
1562
1563 //------------------------------is_x2logic-------------------------------------
1564 // Check for simple convert-to-boolean pattern
1565 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
1566 // Convert Phi to an ConvIB.
1567 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
1568 assert(true_path !=0, "only diamond shape graph expected");
1569
1570 // If we're late in the optimization process, we may have already expanded Conv2B nodes
1571 if (phase->C->post_loop_opts_phase() && !Matcher::match_rule_supported(Op_Conv2B)) {
1572 return nullptr;
1573 }
1574
1575 // Convert the true/false index into an expected 0/1 return.
1576 // Map 2->0 and 1->1.
1577 int flipped = 2-true_path;
1578
1579 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1580 // phi->region->if_proj->ifnode->bool->cmp
1581 Node *region = phi->in(0);
1582 Node *iff = region->in(1)->in(0);
1583 BoolNode *b = (BoolNode*)iff->in(1);
1584 const CmpNode *cmp = (CmpNode*)b->in(1);
1585
1586 Node *zero = phi->in(1);
1587 Node *one = phi->in(2);
1588 const Type *tzero = phase->type( zero );
1589 const Type *tone = phase->type( one );
1590
1591 // Check for compare vs 0
1592 const Type *tcmp = phase->type(cmp->in(2));
1593 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
1594 // Allow cmp-vs-1 if the other input is bounded by 0-1
1595 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
1596 return nullptr;
1597 flipped = 1-flipped; // Test is vs 1 instead of 0!
1598 }
1599
1600 // Check for setting zero/one opposite expected
1601 if( tzero == TypeInt::ZERO ) {
1602 if( tone == TypeInt::ONE ) {
1603 } else return nullptr;
1604 } else if( tzero == TypeInt::ONE ) {
1605 if( tone == TypeInt::ZERO ) {
1606 flipped = 1-flipped;
1607 } else return nullptr;
1608 } else return nullptr;
1609
1610 // Check for boolean test backwards
1611 if( b->_test._test == BoolTest::ne ) {
1612 } else if( b->_test._test == BoolTest::eq ) {
1613 flipped = 1-flipped;
1614 } else return nullptr;
1615
1616 // Build int->bool conversion
1617 Node* n = new Conv2BNode(cmp->in(1));
1618 if (flipped) {
1619 n = new XorINode(phase->transform(n), phase->intcon(1));
1620 }
1621
1622 return n;
1623 }
1624
1625 //------------------------------is_cond_add------------------------------------
1626 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;"
1627 // To be profitable the control flow has to disappear; there can be no other
1628 // values merging here. We replace the test-and-branch with:
1629 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by
1630 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
1631 // Then convert Y to 0-or-Y and finally add.
1632 // This is a key transform for SpecJava _201_compress.
1633 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
1634 assert(true_path !=0, "only diamond shape graph expected");
1635
1636 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1637 // phi->region->if_proj->ifnode->bool->cmp
1638 RegionNode *region = (RegionNode*)phi->in(0);
1639 Node *iff = region->in(1)->in(0);
1640 BoolNode* b = iff->in(1)->as_Bool();
1641 const CmpNode *cmp = (CmpNode*)b->in(1);
1642
1643 // Make sure only merging this one phi here
1644 if (region->has_unique_phi() != phi) return nullptr;
1645
1646 // Make sure each arm of the diamond has exactly one output, which we assume
1647 // is the region. Otherwise, the control flow won't disappear.
1648 if (region->in(1)->outcnt() != 1) return nullptr;
1649 if (region->in(2)->outcnt() != 1) return nullptr;
1650
1651 // Check for "(P < Q)" of type signed int
1652 if (b->_test._test != BoolTest::lt) return nullptr;
1653 if (cmp->Opcode() != Op_CmpI) return nullptr;
1654
1655 Node *p = cmp->in(1);
1656 Node *q = cmp->in(2);
1657 Node *n1 = phi->in( true_path);
1658 Node *n2 = phi->in(3-true_path);
1659
1660 int op = n1->Opcode();
1661 if( op != Op_AddI // Need zero as additive identity
1662 /*&&op != Op_SubI &&
1663 op != Op_AddP &&
1664 op != Op_XorI &&
1665 op != Op_OrI*/ )
1666 return nullptr;
1667
1668 Node *x = n2;
1669 Node *y = nullptr;
1670 if( x == n1->in(1) ) {
1671 y = n1->in(2);
1672 } else if( x == n1->in(2) ) {
1673 y = n1->in(1);
1674 } else return nullptr;
1675
1676 // Not so profitable if compare and add are constants
1677 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
1678 return nullptr;
1679
1680 Node *cmplt = phase->transform( new CmpLTMaskNode(p,q) );
1681 Node *j_and = phase->transform( new AndINode(cmplt,y) );
1682 return new AddINode(j_and,x);
1683 }
1684
1685 //------------------------------is_absolute------------------------------------
1686 // Check for absolute value.
1687 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
1688 assert(true_path !=0, "only diamond shape graph expected");
1689
1690 int cmp_zero_idx = 0; // Index of compare input where to look for zero
1691 int phi_x_idx = 0; // Index of phi input where to find naked x
1692
1693 // ABS ends with the merge of 2 control flow paths.
1694 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
1695 int false_path = 3 - true_path;
1696
1697 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1698 // phi->region->if_proj->ifnode->bool->cmp
1699 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
1700 Node *cmp = bol->in(1);
1701
1702 // Check bool sense
1703 if (cmp->Opcode() == Op_CmpF || cmp->Opcode() == Op_CmpD) {
1704 switch (bol->_test._test) {
1705 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break;
1706 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1707 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1708 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
1709 default: return nullptr; break;
1710 }
1711 } else if (cmp->Opcode() == Op_CmpI || cmp->Opcode() == Op_CmpL) {
1712 switch (bol->_test._test) {
1713 case BoolTest::lt:
1714 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1715 case BoolTest::gt:
1716 case BoolTest::ge: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1717 default: return nullptr; break;
1718 }
1719 }
1720
1721 // Test is next
1722 const Type *tzero = nullptr;
1723 switch (cmp->Opcode()) {
1724 case Op_CmpI: tzero = TypeInt::ZERO; break; // Integer ABS
1725 case Op_CmpL: tzero = TypeLong::ZERO; break; // Long ABS
1726 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS
1727 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS
1728 default: return nullptr;
1729 }
1730
1731 // Find zero input of compare; the other input is being abs'd
1732 Node *x = nullptr;
1733 bool flip = false;
1734 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
1735 x = cmp->in(3 - cmp_zero_idx);
1736 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
1737 // The test is inverted, we should invert the result...
1738 x = cmp->in(cmp_zero_idx);
1739 flip = true;
1740 } else {
1741 return nullptr;
1742 }
1743
1744 // Next get the 2 pieces being selected, one is the original value
1745 // and the other is the negated value.
1746 if( phi_root->in(phi_x_idx) != x ) return nullptr;
1747
1748 // Check other phi input for subtract node
1749 Node *sub = phi_root->in(3 - phi_x_idx);
1750
1751 bool is_sub = sub->Opcode() == Op_SubF || sub->Opcode() == Op_SubD ||
1752 sub->Opcode() == Op_SubI || sub->Opcode() == Op_SubL;
1753
1754 // Allow only Sub(0,X) and fail out for all others; Neg is not OK
1755 if (!is_sub || phase->type(sub->in(1)) != tzero || sub->in(2) != x) return nullptr;
1756
1757 if (tzero == TypeF::ZERO) {
1758 x = new AbsFNode(x);
1759 if (flip) {
1760 x = new SubFNode(sub->in(1), phase->transform(x));
1761 }
1762 } else if (tzero == TypeD::ZERO) {
1763 x = new AbsDNode(x);
1764 if (flip) {
1765 x = new SubDNode(sub->in(1), phase->transform(x));
1766 }
1767 } else if (tzero == TypeInt::ZERO && Matcher::match_rule_supported(Op_AbsI)) {
1768 x = new AbsINode(x);
1769 if (flip) {
1770 x = new SubINode(sub->in(1), phase->transform(x));
1771 }
1772 } else if (tzero == TypeLong::ZERO && Matcher::match_rule_supported(Op_AbsL)) {
1773 x = new AbsLNode(x);
1774 if (flip) {
1775 x = new SubLNode(sub->in(1), phase->transform(x));
1776 }
1777 } else return nullptr;
1778
1779 return x;
1780 }
1781
1782 //------------------------------split_once-------------------------------------
1783 // Helper for split_flow_path
1784 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
1785 igvn->hash_delete(n); // Remove from hash before hacking edges
1786
1787 uint j = 1;
1788 for (uint i = phi->req()-1; i > 0; i--) {
1789 if (phi->in(i) == val) { // Found a path with val?
1790 // Add to NEW Region/Phi, no DU info
1791 newn->set_req( j++, n->in(i) );
1792 // Remove from OLD Region/Phi
1793 n->del_req(i);
1794 }
1795 }
1796
1797 // Register the new node but do not transform it. Cannot transform until the
1798 // entire Region/Phi conglomerate has been hacked as a single huge transform.
1799 igvn->register_new_node_with_optimizer( newn );
1800
1801 // Now I can point to the new node.
1802 n->add_req(newn);
1803 igvn->_worklist.push(n);
1804 }
1805
1806 //------------------------------split_flow_path--------------------------------
1807 // Check for merging identical values and split flow paths
1808 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) {
1809 // This optimization tries to find two or more inputs of phi with the same constant value
1810 // It then splits them into a separate Phi, and according Region. If this is a loop-entry,
1811 // and the loop entry has multiple fall-in edges, and some of those fall-in edges have that
1812 // constant, and others not, we may split the fall-in edges into separate Phi's, and create
1813 // an irreducible loop. For reducible loops, this never seems to happen, as the multiple
1814 // fall-in edges are already merged before the loop head during parsing. But with irreducible
1815 // loops present the order or merging during parsing can sometimes prevent this.
1816 if (phase->C->has_irreducible_loop()) {
1817 // Avoid this optimization if any irreducible loops are present. Else we may create
1818 // an irreducible loop that we do not detect.
1819 return nullptr;
1820 }
1821 BasicType bt = phi->type()->basic_type();
1822 if( bt == T_ILLEGAL || type2size[bt] <= 0 )
1823 return nullptr; // Bail out on funny non-value stuff
1824 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a
1825 return nullptr; // third unequal input to be worth doing
1826
1827 // Scan for a constant
1828 uint i;
1829 for( i = 1; i < phi->req()-1; i++ ) {
1830 Node *n = phi->in(i);
1831 if( !n ) return nullptr;
1832 if( phase->type(n) == Type::TOP ) return nullptr;
1833 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN || n->Opcode() == Op_ConNKlass )
1834 break;
1835 }
1836 if( i >= phi->req() ) // Only split for constants
1837 return nullptr;
1838
1839 Node *val = phi->in(i); // Constant to split for
1840 uint hit = 0; // Number of times it occurs
1841 Node *r = phi->region();
1842
1843 for( ; i < phi->req(); i++ ){ // Count occurrences of constant
1844 Node *n = phi->in(i);
1845 if( !n ) return nullptr;
1846 if( phase->type(n) == Type::TOP ) return nullptr;
1847 if( phi->in(i) == val ) {
1848 hit++;
1849 if (Node::may_be_loop_entry(r->in(i))) {
1850 return nullptr; // don't split loop entry path
1851 }
1852 }
1853 }
1854
1855 if( hit <= 1 || // Make sure we find 2 or more
1856 hit == phi->req()-1 ) // and not ALL the same value
1857 return nullptr;
1858
1859 // Now start splitting out the flow paths that merge the same value.
1860 // Split first the RegionNode.
1861 PhaseIterGVN *igvn = phase->is_IterGVN();
1862 RegionNode *newr = new RegionNode(hit+1);
1863 split_once(igvn, phi, val, r, newr);
1864
1865 // Now split all other Phis than this one
1866 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) {
1867 Node* phi2 = r->fast_out(k);
1868 if( phi2->is_Phi() && phi2->as_Phi() != phi ) {
1869 PhiNode *newphi = PhiNode::make_blank(newr, phi2);
1870 split_once(igvn, phi, val, phi2, newphi);
1871 }
1872 }
1873
1874 // Clean up this guy
1875 igvn->hash_delete(phi);
1876 for( i = phi->req()-1; i > 0; i-- ) {
1877 if( phi->in(i) == val ) {
1878 phi->del_req(i);
1879 }
1880 }
1881 phi->add_req(val);
1882
1883 return phi;
1884 }
1885
1886 // Returns the BasicType of a given convert node and a type, with special handling to ensure that conversions to
1887 // and from half float will return the SHORT basic type, as that wouldn't be returned typically from TypeInt.
1888 static BasicType get_convert_type(Node* convert, const Type* type) {
1889 int convert_op = convert->Opcode();
1890 if (type->isa_int() && (convert_op == Op_ConvHF2F || convert_op == Op_ConvF2HF)) {
1891 return T_SHORT;
1892 }
1893
1894 return type->basic_type();
1895 }
1896
1897 //=============================================================================
1898 //------------------------------simple_data_loop_check-------------------------
1899 // Try to determining if the phi node in a simple safe/unsafe data loop.
1900 // Returns:
1901 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
1902 // Safe - safe case when the phi and it's inputs reference only safe data
1903 // nodes;
1904 // Unsafe - the phi and it's inputs reference unsafe data nodes but there
1905 // is no reference back to the phi - need a graph walk
1906 // to determine if it is in a loop;
1907 // UnsafeLoop - unsafe case when the phi references itself directly or through
1908 // unsafe data node.
1909 // Note: a safe data node is a node which could/never reference itself during
1910 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP.
1911 // I mark Phi nodes as safe node not only because they can reference itself
1912 // but also to prevent mistaking the fallthrough case inside an outer loop
1913 // as dead loop when the phi references itself through an other phi.
1914 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const {
1915 // It is unsafe loop if the phi node references itself directly.
1916 if (in == (Node*)this)
1917 return UnsafeLoop; // Unsafe loop
1918 // Unsafe loop if the phi node references itself through an unsafe data node.
1919 // Exclude cases with null inputs or data nodes which could reference
1920 // itself (safe for dead loops).
1921 if (in != nullptr && !in->is_dead_loop_safe()) {
1922 // Check inputs of phi's inputs also.
1923 // It is much less expensive then full graph walk.
1924 uint cnt = in->req();
1925 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1;
1926 for (; i < cnt; ++i) {
1927 Node* m = in->in(i);
1928 if (m == (Node*)this)
1929 return UnsafeLoop; // Unsafe loop
1930 if (m != nullptr && !m->is_dead_loop_safe()) {
1931 // Check the most common case (about 30% of all cases):
1932 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con).
1933 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : nullptr;
1934 if (m1 == (Node*)this)
1935 return UnsafeLoop; // Unsafe loop
1936 if (m1 != nullptr && m1 == m->in(2) &&
1937 m1->is_dead_loop_safe() && m->in(3)->is_Con()) {
1938 continue; // Safe case
1939 }
1940 // The phi references an unsafe node - need full analysis.
1941 return Unsafe;
1942 }
1943 }
1944 }
1945 return Safe; // Safe case - we can optimize the phi node.
1946 }
1947
1948 //------------------------------is_unsafe_data_reference-----------------------
1949 // If phi can be reached through the data input - it is data loop.
1950 bool PhiNode::is_unsafe_data_reference(Node *in) const {
1951 assert(req() > 1, "");
1952 // First, check simple cases when phi references itself directly or
1953 // through an other node.
1954 LoopSafety safety = simple_data_loop_check(in);
1955 if (safety == UnsafeLoop)
1956 return true; // phi references itself - unsafe loop
1957 else if (safety == Safe)
1958 return false; // Safe case - phi could be replaced with the unique input.
1959
1960 // Unsafe case when we should go through data graph to determine
1961 // if the phi references itself.
1962
1963 ResourceMark rm;
1964
1965 Node_List nstack;
1966 VectorSet visited;
1967
1968 nstack.push(in); // Start with unique input.
1969 visited.set(in->_idx);
1970 while (nstack.size() != 0) {
1971 Node* n = nstack.pop();
1972 uint cnt = n->req();
1973 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1;
1974 for (; i < cnt; i++) {
1975 Node* m = n->in(i);
1976 if (m == (Node*)this) {
1977 return true; // Data loop
1978 }
1979 if (m != nullptr && !m->is_dead_loop_safe()) { // Only look for unsafe cases.
1980 if (!visited.test_set(m->_idx))
1981 nstack.push(m);
1982 }
1983 }
1984 }
1985 return false; // The phi is not reachable from its inputs
1986 }
1987
1988 // Is this Phi's region or some inputs to the region enqueued for IGVN
1989 // and so could cause the region to be optimized out?
1990 bool PhiNode::wait_for_region_igvn(PhaseGVN* phase) {
1991 PhaseIterGVN* igvn = phase->is_IterGVN();
1992 Unique_Node_List& worklist = igvn->_worklist;
1993 bool delay = false;
1994 Node* r = in(0);
1995 for (uint j = 1; j < req(); j++) {
1996 Node* rc = r->in(j);
1997 Node* n = in(j);
1998
1999 if (rc == nullptr || !rc->is_Proj()) { continue; }
2000 if (worklist.member(rc)) {
2001 delay = true;
2002 break;
2003 }
2004
2005 if (rc->in(0) == nullptr || !rc->in(0)->is_If()) { continue; }
2006 if (worklist.member(rc->in(0))) {
2007 delay = true;
2008 break;
2009 }
2010
2011 if (rc->in(0)->in(1) == nullptr || !rc->in(0)->in(1)->is_Bool()) { continue; }
2012 if (worklist.member(rc->in(0)->in(1))) {
2013 delay = true;
2014 break;
2015 }
2016
2017 if (rc->in(0)->in(1)->in(1) == nullptr || !rc->in(0)->in(1)->in(1)->is_Cmp()) { continue; }
2018 if (worklist.member(rc->in(0)->in(1)->in(1))) {
2019 delay = true;
2020 break;
2021 }
2022 }
2023
2024 if (delay) {
2025 worklist.push(this);
2026 }
2027 return delay;
2028 }
2029
2030 // If the Phi's Region is in an irreducible loop, and the Region
2031 // has had an input removed, but not yet transformed, it could be
2032 // that the Region (and this Phi) are not reachable from Root.
2033 // If we allow the Phi to collapse before the Region, this may lead
2034 // to dead-loop data. Wait for the Region to check for reachability,
2035 // and potentially remove the dead code.
2036 bool PhiNode::must_wait_for_region_in_irreducible_loop(PhaseGVN* phase) const {
2037 RegionNode* region = in(0)->as_Region();
2038 if (region->loop_status() == RegionNode::LoopStatus::MaybeIrreducibleEntry) {
2039 Node* top = phase->C->top();
2040 for (uint j = 1; j < req(); j++) {
2041 Node* rc = region->in(j); // for each control input
2042 if (rc == nullptr || phase->type(rc) == Type::TOP) {
2043 // Region is missing a control input
2044 Node* n = in(j);
2045 if (n != nullptr && n != top) {
2046 // Phi still has its input, so region just lost its input
2047 return true;
2048 }
2049 }
2050 }
2051 }
2052 return false;
2053 }
2054
2055 //------------------------------Ideal------------------------------------------
2056 // Return a node which is more "ideal" than the current node. Must preserve
2057 // the CFG, but we can still strip out dead paths.
2058 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2059 Node *r = in(0); // RegionNode
2060 assert(r != nullptr && r->is_Region(), "this phi must have a region");
2061 assert(r->in(0) == nullptr || !r->in(0)->is_Root(), "not a specially hidden merge");
2062
2063 // Note: During parsing, phis are often transformed before their regions.
2064 // This means we have to use type_or_null to defend against untyped regions.
2065 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
2066 return nullptr; // No change
2067
2068 Node *top = phase->C->top();
2069 bool new_phi = (outcnt() == 0); // transforming new Phi
2070 // No change for igvn if new phi is not hooked
2071 if (new_phi && can_reshape)
2072 return nullptr;
2073
2074 if (must_wait_for_region_in_irreducible_loop(phase)) {
2075 return nullptr;
2076 }
2077
2078 // The are 2 situations when only one valid phi's input is left
2079 // (in addition to Region input).
2080 // One: region is not loop - replace phi with this input.
2081 // Two: region is loop - replace phi with top since this data path is dead
2082 // and we need to break the dead data loop.
2083 Node* progress = nullptr; // Record if any progress made
2084 for( uint j = 1; j < req(); ++j ){ // For all paths in
2085 // Check unreachable control paths
2086 Node* rc = r->in(j);
2087 Node* n = in(j); // Get the input
2088 if (rc == nullptr || phase->type(rc) == Type::TOP) {
2089 if (n != top) { // Not already top?
2090 PhaseIterGVN *igvn = phase->is_IterGVN();
2091 if (can_reshape && igvn != nullptr) {
2092 igvn->_worklist.push(r);
2093 }
2094 // Nuke it down
2095 set_req_X(j, top, phase);
2096 progress = this; // Record progress
2097 }
2098 }
2099 }
2100
2101 if (can_reshape && outcnt() == 0) {
2102 // set_req() above may kill outputs if Phi is referenced
2103 // only by itself on the dead (top) control path.
2104 return top;
2105 }
2106
2107 bool uncasted = false;
2108 Node* uin = unique_input(phase, false);
2109 if (uin == nullptr && can_reshape &&
2110 // If there is a chance that the region can be optimized out do
2111 // not add a cast node that we can't remove yet.
2112 !wait_for_region_igvn(phase)) {
2113 uncasted = true;
2114 uin = unique_input(phase, true);
2115 }
2116 if (uin == top) { // Simplest case: no alive inputs.
2117 if (can_reshape) // IGVN transformation
2118 return top;
2119 else
2120 return nullptr; // Identity will return TOP
2121 } else if (uin != nullptr) {
2122 // Only one not-null unique input path is left.
2123 // Determine if this input is backedge of a loop.
2124 // (Skip new phis which have no uses and dead regions).
2125 if (outcnt() > 0 && r->in(0) != nullptr) {
2126 if (is_data_loop(r->as_Region(), uin, phase)) {
2127 // Break this data loop to avoid creation of a dead loop.
2128 if (can_reshape) {
2129 return top;
2130 } else {
2131 // We can't return top if we are in Parse phase - cut inputs only
2132 // let Identity to handle the case.
2133 replace_edge(uin, top, phase);
2134 return nullptr;
2135 }
2136 }
2137 }
2138
2139 if (uncasted) {
2140 // Add cast nodes between the phi to be removed and its unique input.
2141 // Wait until after parsing for the type information to propagate from the casts.
2142 assert(can_reshape, "Invalid during parsing");
2143 const Type* phi_type = bottom_type();
2144 // Add casts to carry the control dependency of the Phi that is
2145 // going away
2146 Node* cast = nullptr;
2147 const TypeTuple* extra_types = collect_types(phase);
2148 if (phi_type->isa_ptr()) {
2149 const Type* uin_type = phase->type(uin);
2150 if (!phi_type->isa_oopptr() && !uin_type->isa_oopptr()) {
2151 cast = new CastPPNode(r, uin, phi_type, ConstraintCastNode::StrongDependency, extra_types);
2152 } else {
2153 // Use a CastPP for a cast to not null and a CheckCastPP for
2154 // a cast to a new klass (and both if both null-ness and
2155 // klass change).
2156
2157 // If the type of phi is not null but the type of uin may be
2158 // null, uin's type must be casted to not null
2159 if (phi_type->join(TypePtr::NOTNULL) == phi_type->remove_speculative() &&
2160 uin_type->join(TypePtr::NOTNULL) != uin_type->remove_speculative()) {
2161 cast = new CastPPNode(r, uin, TypePtr::NOTNULL, ConstraintCastNode::StrongDependency, extra_types);
2162 }
2163
2164 // If the type of phi and uin, both casted to not null,
2165 // differ the klass of uin must be (check)cast'ed to match
2166 // that of phi
2167 if (phi_type->join_speculative(TypePtr::NOTNULL) != uin_type->join_speculative(TypePtr::NOTNULL)) {
2168 Node* n = uin;
2169 if (cast != nullptr) {
2170 cast = phase->transform(cast);
2171 n = cast;
2172 }
2173 cast = new CheckCastPPNode(r, n, phi_type, ConstraintCastNode::StrongDependency, extra_types);
2174 }
2175 if (cast == nullptr) {
2176 cast = new CastPPNode(r, uin, phi_type, ConstraintCastNode::StrongDependency, extra_types);
2177 }
2178 }
2179 } else {
2180 cast = ConstraintCastNode::make_cast_for_type(r, uin, phi_type, ConstraintCastNode::StrongDependency, extra_types);
2181 }
2182 assert(cast != nullptr, "cast should be set");
2183 cast = phase->transform(cast);
2184 // set all inputs to the new cast(s) so the Phi is removed by Identity
2185 PhaseIterGVN* igvn = phase->is_IterGVN();
2186 for (uint i = 1; i < req(); i++) {
2187 set_req_X(i, cast, igvn);
2188 }
2189 uin = cast;
2190 }
2191
2192 // One unique input.
2193 debug_only(Node* ident = Identity(phase));
2194 // The unique input must eventually be detected by the Identity call.
2195 #ifdef ASSERT
2196 if (ident != uin && !ident->is_top() && !must_wait_for_region_in_irreducible_loop(phase)) {
2197 // print this output before failing assert
2198 r->dump(3);
2199 this->dump(3);
2200 ident->dump();
2201 uin->dump();
2202 }
2203 #endif
2204 // Identity may not return the expected uin, if it has to wait for the region, in irreducible case
2205 assert(ident == uin || ident->is_top() || must_wait_for_region_in_irreducible_loop(phase), "Identity must clean this up");
2206 return nullptr;
2207 }
2208
2209 Node* opt = nullptr;
2210 int true_path = is_diamond_phi();
2211 if (true_path != 0 &&
2212 // If one of the diamond's branch is in the process of dying then, the Phi's input for that branch might transform
2213 // to top. If that happens replacing the Phi with an operation that consumes the Phi's inputs will cause the Phi
2214 // to be replaced by top. To prevent that, delay the transformation until the branch has a chance to be removed.
2215 !(can_reshape && wait_for_region_igvn(phase))) {
2216 // Check for CMove'ing identity. If it would be unsafe,
2217 // handle it here. In the safe case, let Identity handle it.
2218 Node* unsafe_id = is_cmove_id(phase, true_path);
2219 if( unsafe_id != nullptr && is_unsafe_data_reference(unsafe_id) )
2220 opt = unsafe_id;
2221
2222 // Check for simple convert-to-boolean pattern
2223 if( opt == nullptr )
2224 opt = is_x2logic(phase, this, true_path);
2225
2226 // Check for absolute value
2227 if( opt == nullptr )
2228 opt = is_absolute(phase, this, true_path);
2229
2230 // Check for conditional add
2231 if( opt == nullptr && can_reshape )
2232 opt = is_cond_add(phase, this, true_path);
2233
2234 // These 4 optimizations could subsume the phi:
2235 // have to check for a dead data loop creation.
2236 if( opt != nullptr ) {
2237 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) {
2238 // Found dead loop.
2239 if( can_reshape )
2240 return top;
2241 // We can't return top if we are in Parse phase - cut inputs only
2242 // to stop further optimizations for this phi. Identity will return TOP.
2243 assert(req() == 3, "only diamond merge phi here");
2244 set_req(1, top);
2245 set_req(2, top);
2246 return nullptr;
2247 } else {
2248 return opt;
2249 }
2250 }
2251 }
2252
2253 // Check for merging identical values and split flow paths
2254 if (can_reshape) {
2255 opt = split_flow_path(phase, this);
2256 // This optimization only modifies phi - don't need to check for dead loop.
2257 assert(opt == nullptr || opt == this, "do not elide phi");
2258 if (opt != nullptr) return opt;
2259 }
2260
2261 if (in(1) != nullptr && in(1)->Opcode() == Op_AddP && can_reshape) {
2262 // Try to undo Phi of AddP:
2263 // (Phi (AddP base address offset) (AddP base2 address2 offset2))
2264 // becomes:
2265 // newbase := (Phi base base2)
2266 // newaddress := (Phi address address2)
2267 // newoffset := (Phi offset offset2)
2268 // (AddP newbase newaddress newoffset)
2269 //
2270 // This occurs as a result of unsuccessful split_thru_phi and
2271 // interferes with taking advantage of addressing modes. See the
2272 // clone_shift_expressions code in matcher.cpp
2273 Node* addp = in(1);
2274 Node* base = addp->in(AddPNode::Base);
2275 Node* address = addp->in(AddPNode::Address);
2276 Node* offset = addp->in(AddPNode::Offset);
2277 if (base != nullptr && address != nullptr && offset != nullptr &&
2278 !base->is_top() && !address->is_top() && !offset->is_top()) {
2279 const Type* base_type = base->bottom_type();
2280 const Type* address_type = address->bottom_type();
2281 // make sure that all the inputs are similar to the first one,
2282 // i.e. AddP with base == address and same offset as first AddP
2283 bool doit = true;
2284 for (uint i = 2; i < req(); i++) {
2285 if (in(i) == nullptr ||
2286 in(i)->Opcode() != Op_AddP ||
2287 in(i)->in(AddPNode::Base) == nullptr ||
2288 in(i)->in(AddPNode::Address) == nullptr ||
2289 in(i)->in(AddPNode::Offset) == nullptr ||
2290 in(i)->in(AddPNode::Base)->is_top() ||
2291 in(i)->in(AddPNode::Address)->is_top() ||
2292 in(i)->in(AddPNode::Offset)->is_top()) {
2293 doit = false;
2294 break;
2295 }
2296 if (in(i)->in(AddPNode::Base) != base) {
2297 base = nullptr;
2298 }
2299 if (in(i)->in(AddPNode::Offset) != offset) {
2300 offset = nullptr;
2301 }
2302 if (in(i)->in(AddPNode::Address) != address) {
2303 address = nullptr;
2304 }
2305 // Accumulate type for resulting Phi
2306 base_type = base_type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type());
2307 address_type = address_type->meet_speculative(in(i)->in(AddPNode::Address)->bottom_type());
2308 }
2309 if (doit && base == nullptr) {
2310 // Check for neighboring AddP nodes in a tree.
2311 // If they have a base, use that it.
2312 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) {
2313 Node* u = this->fast_out(k);
2314 if (u->is_AddP()) {
2315 Node* base2 = u->in(AddPNode::Base);
2316 if (base2 != nullptr && !base2->is_top()) {
2317 if (base == nullptr)
2318 base = base2;
2319 else if (base != base2)
2320 { doit = false; break; }
2321 }
2322 }
2323 }
2324 }
2325 if (doit) {
2326 if (base == nullptr) {
2327 base = new PhiNode(in(0), base_type, nullptr);
2328 for (uint i = 1; i < req(); i++) {
2329 base->init_req(i, in(i)->in(AddPNode::Base));
2330 }
2331 phase->is_IterGVN()->register_new_node_with_optimizer(base);
2332 }
2333 if (address == nullptr) {
2334 address = new PhiNode(in(0), address_type, nullptr);
2335 for (uint i = 1; i < req(); i++) {
2336 address->init_req(i, in(i)->in(AddPNode::Address));
2337 }
2338 phase->is_IterGVN()->register_new_node_with_optimizer(address);
2339 }
2340 if (offset == nullptr) {
2341 offset = new PhiNode(in(0), TypeX_X, nullptr);
2342 for (uint i = 1; i < req(); i++) {
2343 offset->init_req(i, in(i)->in(AddPNode::Offset));
2344 }
2345 phase->is_IterGVN()->register_new_node_with_optimizer(offset);
2346 }
2347 return new AddPNode(base, address, offset);
2348 }
2349 }
2350 }
2351
2352 // Split phis through memory merges, so that the memory merges will go away.
2353 // Piggy-back this transformation on the search for a unique input....
2354 // It will be as if the merged memory is the unique value of the phi.
2355 // (Do not attempt this optimization unless parsing is complete.
2356 // It would make the parser's memory-merge logic sick.)
2357 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.)
2358 if (progress == nullptr && can_reshape && type() == Type::MEMORY) {
2359 // see if this phi should be sliced
2360 uint merge_width = 0;
2361 bool saw_self = false;
2362 for( uint i=1; i<req(); ++i ) {// For all paths in
2363 Node *ii = in(i);
2364 // TOP inputs should not be counted as safe inputs because if the
2365 // Phi references itself through all other inputs then splitting the
2366 // Phi through memory merges would create dead loop at later stage.
2367 if (ii == top) {
2368 return nullptr; // Delay optimization until graph is cleaned.
2369 }
2370 if (ii->is_MergeMem()) {
2371 MergeMemNode* n = ii->as_MergeMem();
2372 merge_width = MAX2(merge_width, n->req());
2373 saw_self = saw_self || (n->base_memory() == this);
2374 }
2375 }
2376
2377 // This restriction is temporarily necessary to ensure termination:
2378 if (!saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0;
2379
2380 if (merge_width > Compile::AliasIdxRaw) {
2381 // found at least one non-empty MergeMem
2382 const TypePtr* at = adr_type();
2383 if (at != TypePtr::BOTTOM) {
2384 // Patch the existing phi to select an input from the merge:
2385 // Phi:AT1(...MergeMem(m0, m1, m2)...) into
2386 // Phi:AT1(...m1...)
2387 int alias_idx = phase->C->get_alias_index(at);
2388 for (uint i=1; i<req(); ++i) {
2389 Node *ii = in(i);
2390 if (ii->is_MergeMem()) {
2391 MergeMemNode* n = ii->as_MergeMem();
2392 // compress paths and change unreachable cycles to TOP
2393 // If not, we can update the input infinitely along a MergeMem cycle
2394 // Equivalent code is in MemNode::Ideal_common
2395 Node *m = phase->transform(n);
2396 if (outcnt() == 0) { // Above transform() may kill us!
2397 return top;
2398 }
2399 // If transformed to a MergeMem, get the desired slice
2400 // Otherwise the returned node represents memory for every slice
2401 Node *new_mem = (m->is_MergeMem()) ?
2402 m->as_MergeMem()->memory_at(alias_idx) : m;
2403 // Update input if it is progress over what we have now
2404 if (new_mem != ii) {
2405 set_req_X(i, new_mem, phase->is_IterGVN());
2406 progress = this;
2407 }
2408 }
2409 }
2410 } else {
2411 // We know that at least one MergeMem->base_memory() == this
2412 // (saw_self == true). If all other inputs also references this phi
2413 // (directly or through data nodes) - it is a dead loop.
2414 bool saw_safe_input = false;
2415 for (uint j = 1; j < req(); ++j) {
2416 Node* n = in(j);
2417 if (n->is_MergeMem()) {
2418 MergeMemNode* mm = n->as_MergeMem();
2419 if (mm->base_memory() == this || mm->base_memory() == mm->empty_memory()) {
2420 // Skip this input if it references back to this phi or if the memory path is dead
2421 continue;
2422 }
2423 }
2424 if (!is_unsafe_data_reference(n)) {
2425 saw_safe_input = true; // found safe input
2426 break;
2427 }
2428 }
2429 if (!saw_safe_input) {
2430 // There is a dead loop: All inputs are either dead or reference back to this phi
2431 return top;
2432 }
2433
2434 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into
2435 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...))
2436 PhaseIterGVN* igvn = phase->is_IterGVN();
2437 assert(igvn != nullptr, "sanity check");
2438 Node* hook = new Node(1);
2439 PhiNode* new_base = (PhiNode*) clone();
2440 // Must eagerly register phis, since they participate in loops.
2441 igvn->register_new_node_with_optimizer(new_base);
2442 hook->add_req(new_base);
2443
2444 MergeMemNode* result = MergeMemNode::make(new_base);
2445 for (uint i = 1; i < req(); ++i) {
2446 Node *ii = in(i);
2447 if (ii->is_MergeMem()) {
2448 MergeMemNode* n = ii->as_MergeMem();
2449 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) {
2450 // If we have not seen this slice yet, make a phi for it.
2451 bool made_new_phi = false;
2452 if (mms.is_empty()) {
2453 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C));
2454 made_new_phi = true;
2455 igvn->register_new_node_with_optimizer(new_phi);
2456 hook->add_req(new_phi);
2457 mms.set_memory(new_phi);
2458 }
2459 Node* phi = mms.memory();
2460 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice");
2461 phi->set_req(i, mms.memory2());
2462 }
2463 }
2464 }
2465 // Distribute all self-loops.
2466 { // (Extra braces to hide mms.)
2467 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2468 Node* phi = mms.memory();
2469 for (uint i = 1; i < req(); ++i) {
2470 if (phi->in(i) == this) phi->set_req(i, phi);
2471 }
2472 }
2473 }
2474 // Already replace this phi node to cut it off from the graph to not interfere in dead loop checks during the
2475 // transformations of the new phi nodes below. Otherwise, we could wrongly conclude that there is no dead loop
2476 // because we are finding this phi node again. Also set the type of the new MergeMem node in case we are also
2477 // visiting it in the transformations below.
2478 igvn->replace_node(this, result);
2479 igvn->set_type(result, result->bottom_type());
2480
2481 // now transform the new nodes, and return the mergemem
2482 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2483 Node* phi = mms.memory();
2484 mms.set_memory(phase->transform(phi));
2485 }
2486 hook->destruct(igvn);
2487 // Replace self with the result.
2488 return result;
2489 }
2490 }
2491 //
2492 // Other optimizations on the memory chain
2493 //
2494 const TypePtr* at = adr_type();
2495 for( uint i=1; i<req(); ++i ) {// For all paths in
2496 Node *ii = in(i);
2497 Node *new_in = MemNode::optimize_memory_chain(ii, at, nullptr, phase);
2498 if (ii != new_in ) {
2499 set_req(i, new_in);
2500 progress = this;
2501 }
2502 }
2503 }
2504
2505 #ifdef _LP64
2506 // Push DecodeN/DecodeNKlass down through phi.
2507 // The rest of phi graph will transform by split EncodeP node though phis up.
2508 if ((UseCompressedOops || UseCompressedClassPointers) && can_reshape && progress == nullptr) {
2509 bool may_push = true;
2510 bool has_decodeN = false;
2511 bool is_decodeN = false;
2512 for (uint i=1; i<req(); ++i) {// For all paths in
2513 Node *ii = in(i);
2514 if (ii->is_DecodeNarrowPtr() && ii->bottom_type() == bottom_type()) {
2515 // Do optimization if a non dead path exist.
2516 if (ii->in(1)->bottom_type() != Type::TOP) {
2517 has_decodeN = true;
2518 is_decodeN = ii->is_DecodeN();
2519 }
2520 } else if (!ii->is_Phi()) {
2521 may_push = false;
2522 }
2523 }
2524
2525 if (has_decodeN && may_push) {
2526 PhaseIterGVN *igvn = phase->is_IterGVN();
2527 // Make narrow type for new phi.
2528 const Type* narrow_t;
2529 if (is_decodeN) {
2530 narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr());
2531 } else {
2532 narrow_t = TypeNarrowKlass::make(this->bottom_type()->is_ptr());
2533 }
2534 PhiNode* new_phi = new PhiNode(r, narrow_t);
2535 uint orig_cnt = req();
2536 for (uint i=1; i<req(); ++i) {// For all paths in
2537 Node *ii = in(i);
2538 Node* new_ii = nullptr;
2539 if (ii->is_DecodeNarrowPtr()) {
2540 assert(ii->bottom_type() == bottom_type(), "sanity");
2541 new_ii = ii->in(1);
2542 } else {
2543 assert(ii->is_Phi(), "sanity");
2544 if (ii->as_Phi() == this) {
2545 new_ii = new_phi;
2546 } else {
2547 if (is_decodeN) {
2548 new_ii = new EncodePNode(ii, narrow_t);
2549 } else {
2550 new_ii = new EncodePKlassNode(ii, narrow_t);
2551 }
2552 igvn->register_new_node_with_optimizer(new_ii);
2553 }
2554 }
2555 new_phi->set_req(i, new_ii);
2556 }
2557 igvn->register_new_node_with_optimizer(new_phi, this);
2558 if (is_decodeN) {
2559 progress = new DecodeNNode(new_phi, bottom_type());
2560 } else {
2561 progress = new DecodeNKlassNode(new_phi, bottom_type());
2562 }
2563 }
2564 }
2565 #endif
2566
2567 // Try to convert a Phi with two duplicated convert nodes into a phi of the pre-conversion type and the convert node
2568 // proceeding the phi, to de-duplicate the convert node and compact the IR.
2569 if (can_reshape && progress == nullptr) {
2570 ConvertNode* convert = in(1)->isa_Convert();
2571 if (convert != nullptr) {
2572 int conv_op = convert->Opcode();
2573 bool ok = true;
2574
2575 // Check the rest of the inputs
2576 for (uint i = 2; i < req(); i++) {
2577 // Make sure that all inputs are of the same type of convert node
2578 if (in(i)->Opcode() != conv_op) {
2579 ok = false;
2580 break;
2581 }
2582 }
2583
2584 if (ok) {
2585 // Find the local bottom type to set as the type of the phi
2586 const Type* source_type = Type::get_const_basic_type(convert->in_type()->basic_type());
2587 const Type* dest_type = convert->bottom_type();
2588
2589 PhiNode* newphi = new PhiNode(in(0), source_type, nullptr);
2590 // Set inputs to the new phi be the inputs of the convert
2591 for (uint i = 1; i < req(); i++) {
2592 newphi->init_req(i, in(i)->in(1));
2593 }
2594
2595 phase->is_IterGVN()->register_new_node_with_optimizer(newphi, this);
2596
2597 return ConvertNode::create_convert(get_convert_type(convert, source_type), get_convert_type(convert, dest_type), newphi);
2598 }
2599 }
2600 }
2601
2602 // Phi (VB ... VB) => VB (Phi ...) (Phi ...)
2603 if (EnableVectorReboxing && can_reshape && progress == nullptr && type()->isa_oopptr()) {
2604 progress = merge_through_phi(this, phase->is_IterGVN());
2605 }
2606
2607 return progress; // Return any progress
2608 }
2609
2610 static int compare_types(const Type* const& e1, const Type* const& e2) {
2611 return (intptr_t)e1 - (intptr_t)e2;
2612 }
2613
2614 // Collect types at casts that are going to be eliminated at that Phi and store them in a TypeTuple.
2615 // Sort the types using an arbitrary order so a list of some types always hashes to the same TypeTuple (and TypeTuple
2616 // pointer comparison is enough to tell if 2 list of types are the same or not)
2617 const TypeTuple* PhiNode::collect_types(PhaseGVN* phase) const {
2618 const Node* region = in(0);
2619 const Type* phi_type = bottom_type();
2620 ResourceMark rm;
2621 GrowableArray<const Type*> types;
2622 for (uint i = 1; i < req(); i++) {
2623 if (region->in(i) == nullptr || phase->type(region->in(i)) == Type::TOP) {
2624 continue;
2625 }
2626 Node* in = Node::in(i);
2627 const Type* t = phase->type(in);
2628 if (in == nullptr || in == this || t == Type::TOP) {
2629 continue;
2630 }
2631 if (t != phi_type && t->higher_equal_speculative(phi_type)) {
2632 types.insert_sorted<compare_types>(t);
2633 }
2634 while (in != nullptr && in->is_ConstraintCast()) {
2635 Node* next = in->in(1);
2636 if (phase->type(next)->isa_rawptr() && phase->type(in)->isa_oopptr()) {
2637 break;
2638 }
2639 ConstraintCastNode* cast = in->as_ConstraintCast();
2640 for (int j = 0; j < cast->extra_types_count(); ++j) {
2641 const Type* extra_t = cast->extra_type_at(j);
2642 if (extra_t != phi_type && extra_t->higher_equal_speculative(phi_type)) {
2643 types.insert_sorted<compare_types>(extra_t);
2644 }
2645 }
2646 in = next;
2647 }
2648 }
2649 const Type **flds = (const Type **)(phase->C->type_arena()->AmallocWords(types.length()*sizeof(Type*)));
2650 for (int i = 0; i < types.length(); ++i) {
2651 flds[i] = types.at(i);
2652 }
2653 return TypeTuple::make(types.length(), flds);
2654 }
2655
2656 Node* PhiNode::clone_through_phi(Node* root_phi, const Type* t, uint c, PhaseIterGVN* igvn) {
2657 Node_Stack stack(1);
2658 VectorSet visited;
2659 Node_List node_map;
2660
2661 stack.push(root_phi, 1); // ignore control
2662 visited.set(root_phi->_idx);
2663
2664 Node* new_phi = new PhiNode(root_phi->in(0), t);
2665 node_map.map(root_phi->_idx, new_phi);
2666
2667 while (stack.is_nonempty()) {
2668 Node* n = stack.node();
2669 uint idx = stack.index();
2670 assert(n->is_Phi(), "not a phi");
2671 if (idx < n->req()) {
2672 stack.set_index(idx + 1);
2673 Node* def = n->in(idx);
2674 if (def == nullptr) {
2675 continue; // ignore dead path
2676 } else if (def->is_Phi()) { // inner node
2677 Node* new_phi = node_map[n->_idx];
2678 if (!visited.test_set(def->_idx)) { // not visited yet
2679 node_map.map(def->_idx, new PhiNode(def->in(0), t));
2680 stack.push(def, 1); // ignore control
2681 }
2682 Node* new_in = node_map[def->_idx];
2683 new_phi->set_req(idx, new_in);
2684 } else if (def->Opcode() == Op_VectorBox) { // leaf
2685 assert(n->is_Phi(), "not a phi");
2686 Node* new_phi = node_map[n->_idx];
2687 new_phi->set_req(idx, def->in(c));
2688 } else {
2689 assert(false, "not optimizeable");
2690 return nullptr;
2691 }
2692 } else {
2693 Node* new_phi = node_map[n->_idx];
2694 igvn->register_new_node_with_optimizer(new_phi, n);
2695 stack.pop();
2696 }
2697 }
2698 return new_phi;
2699 }
2700
2701 Node* PhiNode::merge_through_phi(Node* root_phi, PhaseIterGVN* igvn) {
2702 Node_Stack stack(1);
2703 VectorSet visited;
2704
2705 stack.push(root_phi, 1); // ignore control
2706 visited.set(root_phi->_idx);
2707
2708 VectorBoxNode* cached_vbox = nullptr;
2709 while (stack.is_nonempty()) {
2710 Node* n = stack.node();
2711 uint idx = stack.index();
2712 if (idx < n->req()) {
2713 stack.set_index(idx + 1);
2714 Node* in = n->in(idx);
2715 if (in == nullptr) {
2716 continue; // ignore dead path
2717 } else if (in->isa_Phi()) {
2718 if (!visited.test_set(in->_idx)) {
2719 stack.push(in, 1); // ignore control
2720 }
2721 } else if (in->Opcode() == Op_VectorBox) {
2722 VectorBoxNode* vbox = static_cast<VectorBoxNode*>(in);
2723 if (cached_vbox == nullptr) {
2724 cached_vbox = vbox;
2725 } else if (vbox->vec_type() != cached_vbox->vec_type()) {
2726 // TODO: vector type mismatch can be handled with additional reinterpret casts
2727 assert(Type::cmp(vbox->vec_type(), cached_vbox->vec_type()) != 0, "inconsistent");
2728 return nullptr; // not optimizable: vector type mismatch
2729 } else if (vbox->box_type() != cached_vbox->box_type()) {
2730 assert(Type::cmp(vbox->box_type(), cached_vbox->box_type()) != 0, "inconsistent");
2731 return nullptr; // not optimizable: box type mismatch
2732 }
2733 } else {
2734 return nullptr; // not optimizable: neither Phi nor VectorBox
2735 }
2736 } else {
2737 stack.pop();
2738 }
2739 }
2740 if (cached_vbox == nullptr) {
2741 // We have a Phi dead-loop (no data-input). Phi nodes are considered safe,
2742 // so just avoid this optimization.
2743 return nullptr;
2744 }
2745 const TypeInstPtr* btype = cached_vbox->box_type();
2746 const TypeVect* vtype = cached_vbox->vec_type();
2747 Node* new_vbox_phi = clone_through_phi(root_phi, btype, VectorBoxNode::Box, igvn);
2748 Node* new_vect_phi = clone_through_phi(root_phi, vtype, VectorBoxNode::Value, igvn);
2749 return new VectorBoxNode(igvn->C, new_vbox_phi, new_vect_phi, btype, vtype);
2750 }
2751
2752 bool PhiNode::is_data_loop(RegionNode* r, Node* uin, const PhaseGVN* phase) {
2753 // First, take the short cut when we know it is a loop and the EntryControl data path is dead.
2754 // The loop node may only have one input because the entry path was removed in PhaseIdealLoop::Dominators().
2755 // Then, check if there is a data loop when the phi references itself directly or through other data nodes.
2756 assert(!r->is_Loop() || r->req() <= 3, "Loop node should have 3 or less inputs");
2757 const bool is_loop = (r->is_Loop() && r->req() == 3);
2758 const Node* top = phase->C->top();
2759 if (is_loop) {
2760 return !uin->eqv_uncast(in(LoopNode::EntryControl));
2761 } else {
2762 // We have a data loop either with an unsafe data reference or if a region is unreachable.
2763 return is_unsafe_data_reference(uin)
2764 || (r->req() == 3 && (r->in(1) != top && r->in(2) == top && r->is_unreachable_region(phase)));
2765 }
2766 }
2767
2768 //------------------------------is_tripcount-----------------------------------
2769 bool PhiNode::is_tripcount(BasicType bt) const {
2770 return (in(0) != nullptr && in(0)->is_BaseCountedLoop() &&
2771 in(0)->as_BaseCountedLoop()->bt() == bt &&
2772 in(0)->as_BaseCountedLoop()->phi() == this);
2773 }
2774
2775 //------------------------------out_RegMask------------------------------------
2776 const RegMask &PhiNode::in_RegMask(uint i) const {
2777 return i ? out_RegMask() : RegMask::Empty;
2778 }
2779
2780 const RegMask &PhiNode::out_RegMask() const {
2781 uint ideal_reg = _type->ideal_reg();
2782 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
2783 if( ideal_reg == 0 ) return RegMask::Empty;
2784 assert(ideal_reg != Op_RegFlags, "flags register is not spillable");
2785 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
2786 }
2787
2788 #ifndef PRODUCT
2789 void PhiNode::dump_spec(outputStream *st) const {
2790 TypeNode::dump_spec(st);
2791 if (is_tripcount(T_INT) || is_tripcount(T_LONG)) {
2792 st->print(" #tripcount");
2793 }
2794 }
2795 #endif
2796
2797
2798 //=============================================================================
2799 const Type* GotoNode::Value(PhaseGVN* phase) const {
2800 // If the input is reachable, then we are executed.
2801 // If the input is not reachable, then we are not executed.
2802 return phase->type(in(0));
2803 }
2804
2805 Node* GotoNode::Identity(PhaseGVN* phase) {
2806 return in(0); // Simple copy of incoming control
2807 }
2808
2809 const RegMask &GotoNode::out_RegMask() const {
2810 return RegMask::Empty;
2811 }
2812
2813 //=============================================================================
2814 const RegMask &JumpNode::out_RegMask() const {
2815 return RegMask::Empty;
2816 }
2817
2818 //=============================================================================
2819 const RegMask &JProjNode::out_RegMask() const {
2820 return RegMask::Empty;
2821 }
2822
2823 //=============================================================================
2824 const RegMask &CProjNode::out_RegMask() const {
2825 return RegMask::Empty;
2826 }
2827
2828
2829
2830 //=============================================================================
2831
2832 uint PCTableNode::hash() const { return Node::hash() + _size; }
2833 bool PCTableNode::cmp( const Node &n ) const
2834 { return _size == ((PCTableNode&)n)._size; }
2835
2836 const Type *PCTableNode::bottom_type() const {
2837 const Type** f = TypeTuple::fields(_size);
2838 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2839 return TypeTuple::make(_size, f);
2840 }
2841
2842 //------------------------------Value------------------------------------------
2843 // Compute the type of the PCTableNode. If reachable it is a tuple of
2844 // Control, otherwise the table targets are not reachable
2845 const Type* PCTableNode::Value(PhaseGVN* phase) const {
2846 if( phase->type(in(0)) == Type::CONTROL )
2847 return bottom_type();
2848 return Type::TOP; // All paths dead? Then so are we
2849 }
2850
2851 //------------------------------Ideal------------------------------------------
2852 // Return a node which is more "ideal" than the current node. Strip out
2853 // control copies
2854 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2855 return remove_dead_region(phase, can_reshape) ? this : nullptr;
2856 }
2857
2858 //=============================================================================
2859 uint JumpProjNode::hash() const {
2860 return Node::hash() + _dest_bci;
2861 }
2862
2863 bool JumpProjNode::cmp( const Node &n ) const {
2864 return ProjNode::cmp(n) &&
2865 _dest_bci == ((JumpProjNode&)n)._dest_bci;
2866 }
2867
2868 #ifndef PRODUCT
2869 void JumpProjNode::dump_spec(outputStream *st) const {
2870 ProjNode::dump_spec(st);
2871 st->print("@bci %d ",_dest_bci);
2872 }
2873
2874 void JumpProjNode::dump_compact_spec(outputStream *st) const {
2875 ProjNode::dump_compact_spec(st);
2876 st->print("(%d)%d@%d", _switch_val, _proj_no, _dest_bci);
2877 }
2878 #endif
2879
2880 //=============================================================================
2881 //------------------------------Value------------------------------------------
2882 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot
2883 // have the default "fall_through_index" path.
2884 const Type* CatchNode::Value(PhaseGVN* phase) const {
2885 // Unreachable? Then so are all paths from here.
2886 if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
2887 // First assume all paths are reachable
2888 const Type** f = TypeTuple::fields(_size);
2889 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2890 // Identify cases that will always throw an exception
2891 // () rethrow call
2892 // () virtual or interface call with null receiver
2893 // () call is a check cast with incompatible arguments
2894 if( in(1)->is_Proj() ) {
2895 Node *i10 = in(1)->in(0);
2896 if( i10->is_Call() ) {
2897 CallNode *call = i10->as_Call();
2898 // Rethrows always throw exceptions, never return
2899 if (call->entry_point() == OptoRuntime::rethrow_stub()) {
2900 f[CatchProjNode::fall_through_index] = Type::TOP;
2901 } else if (call->is_AllocateArray()) {
2902 Node* klass_node = call->in(AllocateNode::KlassNode);
2903 Node* length = call->in(AllocateNode::ALength);
2904 const Type* length_type = phase->type(length);
2905 const Type* klass_type = phase->type(klass_node);
2906 Node* valid_length_test = call->in(AllocateNode::ValidLengthTest);
2907 const Type* valid_length_test_t = phase->type(valid_length_test);
2908 if (length_type == Type::TOP || klass_type == Type::TOP || valid_length_test_t == Type::TOP ||
2909 valid_length_test_t->is_int()->is_con(0)) {
2910 f[CatchProjNode::fall_through_index] = Type::TOP;
2911 }
2912 } else if( call->req() > TypeFunc::Parms ) {
2913 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) );
2914 // Check for null receiver to virtual or interface calls
2915 if( call->is_CallDynamicJava() &&
2916 arg0->higher_equal(TypePtr::NULL_PTR) ) {
2917 f[CatchProjNode::fall_through_index] = Type::TOP;
2918 }
2919 } // End of if not a runtime stub
2920 } // End of if have call above me
2921 } // End of slot 1 is not a projection
2922 return TypeTuple::make(_size, f);
2923 }
2924
2925 //=============================================================================
2926 uint CatchProjNode::hash() const {
2927 return Node::hash() + _handler_bci;
2928 }
2929
2930
2931 bool CatchProjNode::cmp( const Node &n ) const {
2932 return ProjNode::cmp(n) &&
2933 _handler_bci == ((CatchProjNode&)n)._handler_bci;
2934 }
2935
2936
2937 //------------------------------Identity---------------------------------------
2938 // If only 1 target is possible, choose it if it is the main control
2939 Node* CatchProjNode::Identity(PhaseGVN* phase) {
2940 // If my value is control and no other value is, then treat as ID
2941 const TypeTuple *t = phase->type(in(0))->is_tuple();
2942 if (t->field_at(_con) != Type::CONTROL) return this;
2943 // If we remove the last CatchProj and elide the Catch/CatchProj, then we
2944 // also remove any exception table entry. Thus we must know the call
2945 // feeding the Catch will not really throw an exception. This is ok for
2946 // the main fall-thru control (happens when we know a call can never throw
2947 // an exception) or for "rethrow", because a further optimization will
2948 // yank the rethrow (happens when we inline a function that can throw an
2949 // exception and the caller has no handler). Not legal, e.g., for passing
2950 // a null receiver to a v-call, or passing bad types to a slow-check-cast.
2951 // These cases MUST throw an exception via the runtime system, so the VM
2952 // will be looking for a table entry.
2953 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode
2954 CallNode *call;
2955 if (_con != TypeFunc::Control && // Bail out if not the main control.
2956 !(proj->is_Proj() && // AND NOT a rethrow
2957 proj->in(0)->is_Call() &&
2958 (call = proj->in(0)->as_Call()) &&
2959 call->entry_point() == OptoRuntime::rethrow_stub()))
2960 return this;
2961
2962 // Search for any other path being control
2963 for (uint i = 0; i < t->cnt(); i++) {
2964 if (i != _con && t->field_at(i) == Type::CONTROL)
2965 return this;
2966 }
2967 // Only my path is possible; I am identity on control to the jump
2968 return in(0)->in(0);
2969 }
2970
2971
2972 #ifndef PRODUCT
2973 void CatchProjNode::dump_spec(outputStream *st) const {
2974 ProjNode::dump_spec(st);
2975 st->print("@bci %d ",_handler_bci);
2976 }
2977 #endif
2978
2979 //=============================================================================
2980 //------------------------------Identity---------------------------------------
2981 // Check for CreateEx being Identity.
2982 Node* CreateExNode::Identity(PhaseGVN* phase) {
2983 if( phase->type(in(1)) == Type::TOP ) return in(1);
2984 if( phase->type(in(0)) == Type::TOP ) return in(0);
2985 if (phase->type(in(0)->in(0)) == Type::TOP) {
2986 assert(in(0)->is_CatchProj(), "control is CatchProj");
2987 return phase->C->top(); // dead code
2988 }
2989 // We only come from CatchProj, unless the CatchProj goes away.
2990 // If the CatchProj is optimized away, then we just carry the
2991 // exception oop through.
2992 CallNode *call = in(1)->in(0)->as_Call();
2993
2994 return (in(0)->is_CatchProj() && in(0)->in(0)->is_Catch() &&
2995 in(0)->in(0)->in(1) == in(1)) ? this : call->in(TypeFunc::Parms);
2996 }
2997
2998 //=============================================================================
2999 //------------------------------Value------------------------------------------
3000 // Check for being unreachable.
3001 const Type* NeverBranchNode::Value(PhaseGVN* phase) const {
3002 if (!in(0) || in(0)->is_top()) return Type::TOP;
3003 return bottom_type();
3004 }
3005
3006 //------------------------------Ideal------------------------------------------
3007 // Check for no longer being part of a loop
3008 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3009 if (can_reshape && !in(0)->is_Region()) {
3010 // Dead code elimination can sometimes delete this projection so
3011 // if it's not there, there's nothing to do.
3012 Node* fallthru = proj_out_or_null(0);
3013 if (fallthru != nullptr) {
3014 phase->is_IterGVN()->replace_node(fallthru, in(0));
3015 }
3016 return phase->C->top();
3017 }
3018 return nullptr;
3019 }
3020
3021 #ifndef PRODUCT
3022 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const {
3023 st->print("%s", Name());
3024 }
3025 #endif
3026
3027 #ifndef PRODUCT
3028 void BlackholeNode::format(PhaseRegAlloc* ra, outputStream* st) const {
3029 st->print("blackhole ");
3030 bool first = true;
3031 for (uint i = 0; i < req(); i++) {
3032 Node* n = in(i);
3033 if (n != nullptr && OptoReg::is_valid(ra->get_reg_first(n))) {
3034 if (first) {
3035 first = false;
3036 } else {
3037 st->print(", ");
3038 }
3039 char buf[128];
3040 ra->dump_register(n, buf, sizeof(buf));
3041 st->print("%s", buf);
3042 }
3043 }
3044 st->cr();
3045 }
3046 #endif
3047