1 /*
2 * Copyright (c) 1997, 2020, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
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23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "gc/shared/barrierSet.hpp"
28 #include "gc/shared/c2/barrierSetC2.hpp"
29 #include "memory/allocation.inline.hpp"
30 #include "memory/resourceArea.hpp"
31 #include "oops/objArrayKlass.hpp"
32 #include "opto/addnode.hpp"
33 #include "opto/castnode.hpp"
34 #include "opto/cfgnode.hpp"
35 #include "opto/connode.hpp"
36 #include "opto/convertnode.hpp"
37 #include "opto/inlinetypenode.hpp"
38 #include "opto/loopnode.hpp"
39 #include "opto/machnode.hpp"
40 #include "opto/movenode.hpp"
41 #include "opto/narrowptrnode.hpp"
42 #include "opto/mulnode.hpp"
43 #include "opto/phaseX.hpp"
44 #include "opto/regmask.hpp"
45 #include "opto/runtime.hpp"
46 #include "opto/subnode.hpp"
47 #include "utilities/vmError.hpp"
48
49 // Portions of code courtesy of Clifford Click
50
51 // Optimization - Graph Style
52
53 //=============================================================================
54 //------------------------------Value------------------------------------------
55 // Compute the type of the RegionNode.
56 const Type* RegionNode::Value(PhaseGVN* phase) const {
57 for( uint i=1; i<req(); ++i ) { // For all paths in
58 Node *n = in(i); // Get Control source
59 if( !n ) continue; // Missing inputs are TOP
60 if( phase->type(n) == Type::CONTROL )
61 return Type::CONTROL;
62 }
63 return Type::TOP; // All paths dead? Then so are we
64 }
65
66 //------------------------------Identity---------------------------------------
67 // Check for Region being Identity.
68 Node* RegionNode::Identity(PhaseGVN* phase) {
69 // Cannot have Region be an identity, even if it has only 1 input.
70 // Phi users cannot have their Region input folded away for them,
71 // since they need to select the proper data input
72 return this;
73 }
74
75 //------------------------------merge_region-----------------------------------
76 // If a Region flows into a Region, merge into one big happy merge. This is
77 // hard to do if there is stuff that has to happen
78 static Node *merge_region(RegionNode *region, PhaseGVN *phase) {
79 if( region->Opcode() != Op_Region ) // Do not do to LoopNodes
80 return NULL;
81 Node *progress = NULL; // Progress flag
82 PhaseIterGVN *igvn = phase->is_IterGVN();
83
84 uint rreq = region->req();
85 for( uint i = 1; i < rreq; i++ ) {
86 Node *r = region->in(i);
87 if( r && r->Opcode() == Op_Region && // Found a region?
88 r->in(0) == r && // Not already collapsed?
89 r != region && // Avoid stupid situations
90 r->outcnt() == 2 ) { // Self user and 'region' user only?
91 assert(!r->as_Region()->has_phi(), "no phi users");
92 if( !progress ) { // No progress
93 if (region->has_phi()) {
94 return NULL; // Only flatten if no Phi users
95 // igvn->hash_delete( phi );
96 }
97 igvn->hash_delete( region );
98 progress = region; // Making progress
99 }
100 igvn->hash_delete( r );
101
102 // Append inputs to 'r' onto 'region'
103 for( uint j = 1; j < r->req(); j++ ) {
104 // Move an input from 'r' to 'region'
105 region->add_req(r->in(j));
106 r->set_req(j, phase->C->top());
107 // Update phis of 'region'
108 //for( uint k = 0; k < max; k++ ) {
109 // Node *phi = region->out(k);
110 // if( phi->is_Phi() ) {
111 // phi->add_req(phi->in(i));
112 // }
113 //}
114
115 rreq++; // One more input to Region
116 } // Found a region to merge into Region
117 igvn->_worklist.push(r);
118 // Clobber pointer to the now dead 'r'
119 region->set_req(i, phase->C->top());
120 }
121 }
122
123 return progress;
124 }
125
126
127
128 //--------------------------------has_phi--------------------------------------
129 // Helper function: Return any PhiNode that uses this region or NULL
130 PhiNode* RegionNode::has_phi() const {
131 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
132 Node* phi = fast_out(i);
133 if (phi->is_Phi()) { // Check for Phi users
134 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
135 return phi->as_Phi(); // this one is good enough
136 }
137 }
138
139 return NULL;
140 }
141
142
143 //-----------------------------has_unique_phi----------------------------------
144 // Helper function: Return the only PhiNode that uses this region or NULL
145 PhiNode* RegionNode::has_unique_phi() const {
146 // Check that only one use is a Phi
147 PhiNode* only_phi = NULL;
148 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
149 Node* phi = fast_out(i);
150 if (phi->is_Phi()) { // Check for Phi users
151 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
152 if (only_phi == NULL) {
153 only_phi = phi->as_Phi();
154 } else {
155 return NULL; // multiple phis
156 }
157 }
158 }
159
160 return only_phi;
161 }
162
163
164 //------------------------------check_phi_clipping-----------------------------
165 // Helper function for RegionNode's identification of FP clipping
166 // Check inputs to the Phi
167 static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) {
168 min = NULL;
169 max = NULL;
170 val = NULL;
171 min_idx = 0;
172 max_idx = 0;
173 val_idx = 0;
174 uint phi_max = phi->req();
175 if( phi_max == 4 ) {
176 for( uint j = 1; j < phi_max; ++j ) {
177 Node *n = phi->in(j);
178 int opcode = n->Opcode();
179 switch( opcode ) {
180 case Op_ConI:
181 {
182 if( min == NULL ) {
183 min = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
184 min_idx = j;
185 } else {
186 max = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
187 max_idx = j;
188 if( min->get_int() > max->get_int() ) {
189 // Swap min and max
190 ConNode *temp;
191 uint temp_idx;
192 temp = min; min = max; max = temp;
193 temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx;
194 }
195 }
196 }
197 break;
198 default:
199 {
200 val = n;
201 val_idx = j;
202 }
203 break;
204 }
205 }
206 }
207 return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) );
208 }
209
210
211 //------------------------------check_if_clipping------------------------------
212 // Helper function for RegionNode's identification of FP clipping
213 // Check that inputs to Region come from two IfNodes,
214 //
215 // If
216 // False True
217 // If |
218 // False True |
219 // | | |
220 // RegionNode_inputs
221 //
222 static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) {
223 top_if = NULL;
224 bot_if = NULL;
225
226 // Check control structure above RegionNode for (if ( if ) )
227 Node *in1 = region->in(1);
228 Node *in2 = region->in(2);
229 Node *in3 = region->in(3);
230 // Check that all inputs are projections
231 if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) {
232 Node *in10 = in1->in(0);
233 Node *in20 = in2->in(0);
234 Node *in30 = in3->in(0);
235 // Check that #1 and #2 are ifTrue and ifFalse from same If
236 if( in10 != NULL && in10->is_If() &&
237 in20 != NULL && in20->is_If() &&
238 in30 != NULL && in30->is_If() && in10 == in20 &&
239 (in1->Opcode() != in2->Opcode()) ) {
240 Node *in100 = in10->in(0);
241 Node *in1000 = (in100 != NULL && in100->is_Proj()) ? in100->in(0) : NULL;
242 // Check that control for in10 comes from other branch of IF from in3
243 if( in1000 != NULL && in1000->is_If() &&
244 in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) {
245 // Control pattern checks
246 top_if = (IfNode*)in1000;
247 bot_if = (IfNode*)in10;
248 }
249 }
250 }
251
252 return (top_if != NULL);
253 }
254
255
256 //------------------------------check_convf2i_clipping-------------------------
257 // Helper function for RegionNode's identification of FP clipping
258 // Verify that the value input to the phi comes from "ConvF2I; LShift; RShift"
259 static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) {
260 convf2i = NULL;
261
262 // Check for the RShiftNode
263 Node *rshift = phi->in(idx);
264 assert( rshift, "Previous checks ensure phi input is present");
265 if( rshift->Opcode() != Op_RShiftI ) { return false; }
266
267 // Check for the LShiftNode
268 Node *lshift = rshift->in(1);
269 assert( lshift, "Previous checks ensure phi input is present");
270 if( lshift->Opcode() != Op_LShiftI ) { return false; }
271
272 // Check for the ConvF2INode
273 Node *conv = lshift->in(1);
274 if( conv->Opcode() != Op_ConvF2I ) { return false; }
275
276 // Check that shift amounts are only to get sign bits set after F2I
277 jint max_cutoff = max->get_int();
278 jint min_cutoff = min->get_int();
279 jint left_shift = lshift->in(2)->get_int();
280 jint right_shift = rshift->in(2)->get_int();
281 jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1);
282 if( left_shift != right_shift ||
283 0 > left_shift || left_shift >= BitsPerJavaInteger ||
284 max_post_shift < max_cutoff ||
285 max_post_shift < -min_cutoff ) {
286 // Shifts are necessary but current transformation eliminates them
287 return false;
288 }
289
290 // OK to return the result of ConvF2I without shifting
291 convf2i = (ConvF2INode*)conv;
292 return true;
293 }
294
295
296 //------------------------------check_compare_clipping-------------------------
297 // Helper function for RegionNode's identification of FP clipping
298 static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) {
299 Node *i1 = iff->in(1);
300 if ( !i1->is_Bool() ) { return false; }
301 BoolNode *bool1 = i1->as_Bool();
302 if( less_than && bool1->_test._test != BoolTest::le ) { return false; }
303 else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; }
304 const Node *cmpF = bool1->in(1);
305 if( cmpF->Opcode() != Op_CmpF ) { return false; }
306 // Test that the float value being compared against
307 // is equivalent to the int value used as a limit
308 Node *nodef = cmpF->in(2);
309 if( nodef->Opcode() != Op_ConF ) { return false; }
310 jfloat conf = nodef->getf();
311 jint coni = limit->get_int();
312 if( ((int)conf) != coni ) { return false; }
313 input = cmpF->in(1);
314 return true;
315 }
316
317 //------------------------------is_unreachable_region--------------------------
318 // Find if the Region node is reachable from the root.
319 bool RegionNode::is_unreachable_region(PhaseGVN *phase) const {
320 assert(req() == 2, "");
321
322 // First, cut the simple case of fallthrough region when NONE of
323 // region's phis references itself directly or through a data node.
324 uint max = outcnt();
325 uint i;
326 for (i = 0; i < max; i++) {
327 Node* phi = raw_out(i);
328 if (phi != NULL && phi->is_Phi()) {
329 assert(phase->eqv(phi->in(0), this) && phi->req() == 2, "");
330 if (phi->outcnt() == 0)
331 continue; // Safe case - no loops
332 if (phi->outcnt() == 1) {
333 Node* u = phi->raw_out(0);
334 // Skip if only one use is an other Phi or Call or Uncommon trap.
335 // It is safe to consider this case as fallthrough.
336 if (u != NULL && (u->is_Phi() || u->is_CFG()))
337 continue;
338 }
339 // Check when phi references itself directly or through an other node.
340 if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe)
341 break; // Found possible unsafe data loop.
342 }
343 }
344 if (i >= max)
345 return false; // An unsafe case was NOT found - don't need graph walk.
346
347 // Unsafe case - check if the Region node is reachable from root.
348 ResourceMark rm;
349
350 Node_List nstack;
351 VectorSet visited;
352
353 // Mark all control nodes reachable from root outputs
354 Node *n = (Node*)phase->C->root();
355 nstack.push(n);
356 visited.set(n->_idx);
357 while (nstack.size() != 0) {
358 n = nstack.pop();
359 uint max = n->outcnt();
360 for (uint i = 0; i < max; i++) {
361 Node* m = n->raw_out(i);
362 if (m != NULL && m->is_CFG()) {
363 if (phase->eqv(m, this)) {
364 return false; // We reached the Region node - it is not dead.
365 }
366 if (!visited.test_set(m->_idx))
367 nstack.push(m);
368 }
369 }
370 }
371
372 return true; // The Region node is unreachable - it is dead.
373 }
374
375 Node* PhiNode::try_clean_mem_phi(PhaseGVN *phase) {
376 // Incremental inlining + PhaseStringOpts sometimes produce:
377 //
378 // cmpP with 1 top input
379 // |
380 // If
381 // / \
382 // IfFalse IfTrue /- Some Node
383 // \ / / /
384 // Region / /-MergeMem
385 // \---Phi
386 //
387 //
388 // It's expected by PhaseStringOpts that the Region goes away and is
389 // replaced by If's control input but because there's still a Phi,
390 // the Region stays in the graph. The top input from the cmpP is
391 // propagated forward and a subgraph that is useful goes away. The
392 // code below replaces the Phi with the MergeMem so that the Region
393 // is simplified.
394
395 if (type() == Type::MEMORY && is_diamond_phi(true)) {
396 MergeMemNode* m = NULL;
397 assert(req() == 3, "same as region");
398 Node* r = in(0);
399 for (uint i = 1; i < 3; ++i) {
400 Node *mem = in(i);
401 if (mem && mem->is_MergeMem() && r->in(i)->outcnt() == 1) {
402 // Nothing is control-dependent on path #i except the region itself.
403 m = mem->as_MergeMem();
404 uint j = 3 - i;
405 Node* other = in(j);
406 if (other && other == m->base_memory()) {
407 // m is a successor memory to other, and is not pinned inside the diamond, so push it out.
408 // This will allow the diamond to collapse completely.
409 return m;
410 }
411 }
412 }
413 }
414 return NULL;
415 }
416
417 //------------------------------Ideal------------------------------------------
418 // Return a node which is more "ideal" than the current node. Must preserve
419 // the CFG, but we can still strip out dead paths.
420 Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) {
421 if( !can_reshape && !in(0) ) return NULL; // Already degraded to a Copy
422 assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge");
423
424 // Check for RegionNode with no Phi users and both inputs come from either
425 // arm of the same IF. If found, then the control-flow split is useless.
426 bool has_phis = false;
427 if (can_reshape) { // Need DU info to check for Phi users
428 has_phis = (has_phi() != NULL); // Cache result
429 if (has_phis) {
430 PhiNode* phi = has_unique_phi();
431 if (phi != NULL) {
432 Node* m = phi->try_clean_mem_phi(phase);
433 if (m != NULL) {
434 phase->is_IterGVN()->replace_node(phi, m);
435 has_phis = false;
436 }
437 }
438 }
439
440 if (!has_phis) { // No Phi users? Nothing merging?
441 for (uint i = 1; i < req()-1; i++) {
442 Node *if1 = in(i);
443 if( !if1 ) continue;
444 Node *iff = if1->in(0);
445 if( !iff || !iff->is_If() ) continue;
446 for( uint j=i+1; j<req(); j++ ) {
447 if( in(j) && in(j)->in(0) == iff &&
448 if1->Opcode() != in(j)->Opcode() ) {
449 // Add the IF Projections to the worklist. They (and the IF itself)
450 // will be eliminated if dead.
451 phase->is_IterGVN()->add_users_to_worklist(iff);
452 set_req(i, iff->in(0));// Skip around the useless IF diamond
453 set_req(j, NULL);
454 return this; // Record progress
455 }
456 }
457 }
458 }
459 }
460
461 // Remove TOP or NULL input paths. If only 1 input path remains, this Region
462 // degrades to a copy.
463 bool add_to_worklist = false;
464 bool modified = false;
465 int cnt = 0; // Count of values merging
466 DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count
467 int del_it = 0; // The last input path we delete
468 // For all inputs...
469 for( uint i=1; i<req(); ++i ){// For all paths in
470 Node *n = in(i); // Get the input
471 if( n != NULL ) {
472 // Remove useless control copy inputs
473 if( n->is_Region() && n->as_Region()->is_copy() ) {
474 set_req(i, n->nonnull_req());
475 modified = true;
476 i--;
477 continue;
478 }
479 if( n->is_Proj() ) { // Remove useless rethrows
480 Node *call = n->in(0);
481 if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) {
482 set_req(i, call->in(0));
483 modified = true;
484 i--;
485 continue;
486 }
487 }
488 if( phase->type(n) == Type::TOP ) {
489 set_req(i, NULL); // Ignore TOP inputs
490 modified = true;
491 i--;
492 continue;
493 }
494 cnt++; // One more value merging
495
496 } else if (can_reshape) { // Else found dead path with DU info
497 PhaseIterGVN *igvn = phase->is_IterGVN();
498 del_req(i); // Yank path from self
499 del_it = i;
500 uint max = outcnt();
501 DUIterator j;
502 bool progress = true;
503 while(progress) { // Need to establish property over all users
504 progress = false;
505 for (j = outs(); has_out(j); j++) {
506 Node *n = out(j);
507 if( n->req() != req() && n->is_Phi() ) {
508 assert( n->in(0) == this, "" );
509 igvn->hash_delete(n); // Yank from hash before hacking edges
510 n->set_req_X(i,NULL,igvn);// Correct DU info
511 n->del_req(i); // Yank path from Phis
512 if( max != outcnt() ) {
513 progress = true;
514 j = refresh_out_pos(j);
515 max = outcnt();
516 }
517 }
518 }
519 }
520 add_to_worklist = true;
521 i--;
522 }
523 }
524
525 if (can_reshape && cnt == 1) {
526 // Is it dead loop?
527 // If it is LoopNopde it had 2 (+1 itself) inputs and
528 // one of them was cut. The loop is dead if it was EntryContol.
529 // Loop node may have only one input because entry path
530 // is removed in PhaseIdealLoop::Dominators().
531 assert(!this->is_Loop() || cnt_orig <= 3, "Loop node should have 3 or less inputs");
532 if ((this->is_Loop() && (del_it == LoopNode::EntryControl ||
533 (del_it == 0 && is_unreachable_region(phase)))) ||
534 (!this->is_Loop() && has_phis && is_unreachable_region(phase))) {
535 // Yes, the region will be removed during the next step below.
536 // Cut the backedge input and remove phis since no data paths left.
537 // We don't cut outputs to other nodes here since we need to put them
538 // on the worklist.
539 PhaseIterGVN *igvn = phase->is_IterGVN();
540 if (in(1)->outcnt() == 1) {
541 igvn->_worklist.push(in(1));
542 }
543 del_req(1);
544 cnt = 0;
545 assert( req() == 1, "no more inputs expected" );
546 uint max = outcnt();
547 bool progress = true;
548 Node *top = phase->C->top();
549 DUIterator j;
550 while(progress) {
551 progress = false;
552 for (j = outs(); has_out(j); j++) {
553 Node *n = out(j);
554 if( n->is_Phi() ) {
555 assert( igvn->eqv(n->in(0), this), "" );
556 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
557 // Break dead loop data path.
558 // Eagerly replace phis with top to avoid phis copies generation.
559 igvn->replace_node(n, top);
560 if( max != outcnt() ) {
561 progress = true;
562 j = refresh_out_pos(j);
563 max = outcnt();
564 }
565 }
566 }
567 }
568 add_to_worklist = true;
569 }
570 }
571 if (add_to_worklist) {
572 phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis
573 }
574
575 if( cnt <= 1 ) { // Only 1 path in?
576 set_req(0, NULL); // Null control input for region copy
577 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is.
578 // No inputs or all inputs are NULL.
579 return NULL;
580 } else if (can_reshape) { // Optimization phase - remove the node
581 PhaseIterGVN *igvn = phase->is_IterGVN();
582 // Strip mined (inner) loop is going away, remove outer loop.
583 if (is_CountedLoop() &&
584 as_Loop()->is_strip_mined()) {
585 Node* outer_sfpt = as_CountedLoop()->outer_safepoint();
586 Node* outer_out = as_CountedLoop()->outer_loop_exit();
587 if (outer_sfpt != NULL && outer_out != NULL) {
588 Node* in = outer_sfpt->in(0);
589 igvn->replace_node(outer_out, in);
590 LoopNode* outer = as_CountedLoop()->outer_loop();
591 igvn->replace_input_of(outer, LoopNode::LoopBackControl, igvn->C->top());
592 }
593 }
594 Node *parent_ctrl;
595 if( cnt == 0 ) {
596 assert( req() == 1, "no inputs expected" );
597 // During IGVN phase such region will be subsumed by TOP node
598 // so region's phis will have TOP as control node.
599 // Kill phis here to avoid it. PhiNode::is_copy() will be always false.
600 // Also set other user's input to top.
601 parent_ctrl = phase->C->top();
602 } else {
603 // The fallthrough case since we already checked dead loops above.
604 parent_ctrl = in(1);
605 assert(parent_ctrl != NULL, "Region is a copy of some non-null control");
606 assert(!igvn->eqv(parent_ctrl, this), "Close dead loop");
607 }
608 if (!add_to_worklist)
609 igvn->add_users_to_worklist(this); // Check for further allowed opts
610 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
611 Node* n = last_out(i);
612 igvn->hash_delete(n); // Remove from worklist before modifying edges
613 if( n->is_Phi() ) { // Collapse all Phis
614 // Eagerly replace phis to avoid copies generation.
615 Node* in;
616 if( cnt == 0 ) {
617 assert( n->req() == 1, "No data inputs expected" );
618 in = parent_ctrl; // replaced by top
619 } else {
620 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
621 in = n->in(1); // replaced by unique input
622 if( n->as_Phi()->is_unsafe_data_reference(in) )
623 in = phase->C->top(); // replaced by top
624 }
625 igvn->replace_node(n, in);
626 }
627 else if( n->is_Region() ) { // Update all incoming edges
628 assert( !igvn->eqv(n, this), "Must be removed from DefUse edges");
629 uint uses_found = 0;
630 for( uint k=1; k < n->req(); k++ ) {
631 if( n->in(k) == this ) {
632 n->set_req(k, parent_ctrl);
633 uses_found++;
634 }
635 }
636 if( uses_found > 1 ) { // (--i) done at the end of the loop.
637 i -= (uses_found - 1);
638 }
639 }
640 else {
641 assert( igvn->eqv(n->in(0), this), "Expect RegionNode to be control parent");
642 n->set_req(0, parent_ctrl);
643 }
644 #ifdef ASSERT
645 for( uint k=0; k < n->req(); k++ ) {
646 assert( !igvn->eqv(n->in(k), this), "All uses of RegionNode should be gone");
647 }
648 #endif
649 }
650 // Remove the RegionNode itself from DefUse info
651 igvn->remove_dead_node(this);
652 return NULL;
653 }
654 return this; // Record progress
655 }
656
657
658 // If a Region flows into a Region, merge into one big happy merge.
659 if (can_reshape) {
660 Node *m = merge_region(this, phase);
661 if (m != NULL) return m;
662 }
663
664 // Check if this region is the root of a clipping idiom on floats
665 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
666 // Check that only one use is a Phi and that it simplifies to two constants +
667 PhiNode* phi = has_unique_phi();
668 if (phi != NULL) { // One Phi user
669 // Check inputs to the Phi
670 ConNode *min;
671 ConNode *max;
672 Node *val;
673 uint min_idx;
674 uint max_idx;
675 uint val_idx;
676 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) {
677 IfNode *top_if;
678 IfNode *bot_if;
679 if( check_if_clipping( this, bot_if, top_if ) ) {
680 // Control pattern checks, now verify compares
681 Node *top_in = NULL; // value being compared against
682 Node *bot_in = NULL;
683 if( check_compare_clipping( true, bot_if, min, bot_in ) &&
684 check_compare_clipping( false, top_if, max, top_in ) ) {
685 if( bot_in == top_in ) {
686 PhaseIterGVN *gvn = phase->is_IterGVN();
687 assert( gvn != NULL, "Only had DefUse info in IterGVN");
688 // Only remaining check is that bot_in == top_in == (Phi's val + mods)
689
690 // Check for the ConvF2INode
691 ConvF2INode *convf2i;
692 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
693 convf2i->in(1) == bot_in ) {
694 // Matched pattern, including LShiftI; RShiftI, replace with integer compares
695 // max test
696 Node *cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, min ));
697 Node *boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::lt ));
698 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt ));
699 Node *if_min= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
700 Node *ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
701 // min test
702 cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, max ));
703 boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::gt ));
704 iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
705 Node *if_max= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
706 ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
707 // update input edges to region node
708 set_req_X( min_idx, if_min, gvn );
709 set_req_X( max_idx, if_max, gvn );
710 set_req_X( val_idx, ifF, gvn );
711 // remove unnecessary 'LShiftI; RShiftI' idiom
712 gvn->hash_delete(phi);
713 phi->set_req_X( val_idx, convf2i, gvn );
714 gvn->hash_find_insert(phi);
715 // Return transformed region node
716 return this;
717 }
718 }
719 }
720 }
721 }
722 }
723 }
724
725 if (can_reshape) {
726 modified |= optimize_trichotomy(phase->is_IterGVN());
727 }
728
729 return modified ? this : NULL;
730 }
731
732 //------------------------------optimize_trichotomy--------------------------
733 // Optimize nested comparisons of the following kind:
734 //
735 // int compare(int a, int b) {
736 // return (a < b) ? -1 : (a == b) ? 0 : 1;
737 // }
738 //
739 // Shape 1:
740 // if (compare(a, b) == 1) { ... } -> if (a > b) { ... }
741 //
742 // Shape 2:
743 // if (compare(a, b) == 0) { ... } -> if (a == b) { ... }
744 //
745 // Above code leads to the following IR shapes where both Ifs compare the
746 // same value and two out of three region inputs idx1 and idx2 map to
747 // the same value and control flow.
748 //
749 // (1) If (2) If
750 // / \ / \
751 // Proj Proj Proj Proj
752 // | \ | \
753 // | If | If If
754 // | / \ | / \ / \
755 // | Proj Proj | Proj Proj ==> Proj Proj
756 // | / / \ | / | /
757 // Region / \ | / | /
758 // \ / \ | / | /
759 // Region Region Region
760 //
761 // The method returns true if 'this' is modified and false otherwise.
762 bool RegionNode::optimize_trichotomy(PhaseIterGVN* igvn) {
763 int idx1 = 1, idx2 = 2;
764 Node* region = NULL;
765 if (req() == 3 && in(1) != NULL && in(2) != NULL) {
766 // Shape 1: Check if one of the inputs is a region that merges two control
767 // inputs and has no other users (especially no Phi users).
768 region = in(1)->isa_Region() ? in(1) : in(2)->isa_Region();
769 if (region == NULL || region->outcnt() != 2 || region->req() != 3) {
770 return false; // No suitable region input found
771 }
772 } else if (req() == 4) {
773 // Shape 2: Check if two control inputs map to the same value of the unique phi
774 // user and treat these as if they would come from another region (shape (1)).
775 PhiNode* phi = has_unique_phi();
776 if (phi == NULL) {
777 return false; // No unique phi user
778 }
779 if (phi->in(idx1) != phi->in(idx2)) {
780 idx2 = 3;
781 if (phi->in(idx1) != phi->in(idx2)) {
782 idx1 = 2;
783 if (phi->in(idx1) != phi->in(idx2)) {
784 return false; // No equal phi inputs found
785 }
786 }
787 }
788 assert(phi->in(idx1) == phi->in(idx2), "must be"); // Region is merging same value
789 region = this;
790 }
791 if (region == NULL || region->in(idx1) == NULL || region->in(idx2) == NULL) {
792 return false; // Region does not merge two control inputs
793 }
794 // At this point we know that region->in(idx1) and region->(idx2) map to the same
795 // value and control flow. Now search for ifs that feed into these region inputs.
796 ProjNode* proj1 = region->in(idx1)->isa_Proj();
797 ProjNode* proj2 = region->in(idx2)->isa_Proj();
798 if (proj1 == NULL || proj1->outcnt() != 1 ||
799 proj2 == NULL || proj2->outcnt() != 1) {
800 return false; // No projection inputs with region as unique user found
801 }
802 assert(proj1 != proj2, "should be different projections");
803 IfNode* iff1 = proj1->in(0)->isa_If();
804 IfNode* iff2 = proj2->in(0)->isa_If();
805 if (iff1 == NULL || iff1->outcnt() != 2 ||
806 iff2 == NULL || iff2->outcnt() != 2) {
807 return false; // No ifs found
808 }
809 if (iff1 == iff2) {
810 igvn->add_users_to_worklist(iff1); // Make sure dead if is eliminated
811 igvn->replace_input_of(region, idx1, iff1->in(0));
812 igvn->replace_input_of(region, idx2, igvn->C->top());
813 return (region == this); // Remove useless if (both projections map to the same control/value)
814 }
815 BoolNode* bol1 = iff1->in(1)->isa_Bool();
816 BoolNode* bol2 = iff2->in(1)->isa_Bool();
817 if (bol1 == NULL || bol2 == NULL) {
818 return false; // No bool inputs found
819 }
820 Node* cmp1 = bol1->in(1);
821 Node* cmp2 = bol2->in(1);
822 bool commute = false;
823 if (!cmp1->is_Cmp() || !cmp2->is_Cmp()) {
824 return false; // No comparison
825 } else if (cmp1->Opcode() == Op_CmpF || cmp1->Opcode() == Op_CmpD ||
826 cmp2->Opcode() == Op_CmpF || cmp2->Opcode() == Op_CmpD ||
827 cmp1->Opcode() == Op_CmpP || cmp1->Opcode() == Op_CmpN ||
828 cmp2->Opcode() == Op_CmpP || cmp2->Opcode() == Op_CmpN) {
829 // Floats and pointers don't exactly obey trichotomy. To be on the safe side, don't transform their tests.
830 return false;
831 } else if (cmp1 != cmp2) {
832 if (cmp1->in(1) == cmp2->in(2) &&
833 cmp1->in(2) == cmp2->in(1)) {
834 commute = true; // Same but swapped inputs, commute the test
835 } else {
836 return false; // Ifs are not comparing the same values
837 }
838 }
839 proj1 = proj1->other_if_proj();
840 proj2 = proj2->other_if_proj();
841 if (!((proj1->unique_ctrl_out() == iff2 &&
842 proj2->unique_ctrl_out() == this) ||
843 (proj2->unique_ctrl_out() == iff1 &&
844 proj1->unique_ctrl_out() == this))) {
845 return false; // Ifs are not connected through other projs
846 }
847 // Found 'iff -> proj -> iff -> proj -> this' shape where all other projs are merged
848 // through 'region' and map to the same value. Merge the boolean tests and replace
849 // the ifs by a single comparison.
850 BoolTest test1 = (proj1->_con == 1) ? bol1->_test : bol1->_test.negate();
851 BoolTest test2 = (proj2->_con == 1) ? bol2->_test : bol2->_test.negate();
852 test1 = commute ? test1.commute() : test1;
853 // After possibly commuting test1, if we can merge test1 & test2, then proj2/iff2/bol2 are the nodes to refine.
854 BoolTest::mask res = test1.merge(test2);
855 if (res == BoolTest::illegal) {
856 return false; // Unable to merge tests
857 }
858 // Adjust iff1 to always pass (only iff2 will remain)
859 igvn->replace_input_of(iff1, 1, igvn->intcon(proj1->_con));
860 if (res == BoolTest::never) {
861 // Merged test is always false, adjust iff2 to always fail
862 igvn->replace_input_of(iff2, 1, igvn->intcon(1 - proj2->_con));
863 } else {
864 // Replace bool input of iff2 with merged test
865 BoolNode* new_bol = new BoolNode(bol2->in(1), res);
866 igvn->replace_input_of(iff2, 1, igvn->transform((proj2->_con == 1) ? new_bol : new_bol->negate(igvn)));
867 }
868 return false;
869 }
870
871 const RegMask &RegionNode::out_RegMask() const {
872 return RegMask::Empty;
873 }
874
875 // Find the one non-null required input. RegionNode only
876 Node *Node::nonnull_req() const {
877 assert( is_Region(), "" );
878 for( uint i = 1; i < _cnt; i++ )
879 if( in(i) )
880 return in(i);
881 ShouldNotReachHere();
882 return NULL;
883 }
884
885
886 //=============================================================================
887 // note that these functions assume that the _adr_type field is flattened
888 uint PhiNode::hash() const {
889 const Type* at = _adr_type;
890 return TypeNode::hash() + (at ? at->hash() : 0);
891 }
892 bool PhiNode::cmp( const Node &n ) const {
893 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
894 }
895 static inline
896 const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
897 if (at == NULL || at == TypePtr::BOTTOM) return at;
898 return Compile::current()->alias_type(at)->adr_type();
899 }
900
901 //----------------------------make---------------------------------------------
902 // create a new phi with edges matching r and set (initially) to x
903 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
904 uint preds = r->req(); // Number of predecessor paths
905 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at) || (flatten_phi_adr_type(at) == TypeAryPtr::INLINES && Compile::current()->flattened_accesses_share_alias()), "flatten at");
906 PhiNode* p = new PhiNode(r, t, at);
907 for (uint j = 1; j < preds; j++) {
908 // Fill in all inputs, except those which the region does not yet have
909 if (r->in(j) != NULL)
910 p->init_req(j, x);
911 }
912 return p;
913 }
914 PhiNode* PhiNode::make(Node* r, Node* x) {
915 const Type* t = x->bottom_type();
916 const TypePtr* at = NULL;
917 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
918 return make(r, x, t, at);
919 }
920 PhiNode* PhiNode::make_blank(Node* r, Node* x) {
921 const Type* t = x->bottom_type();
922 const TypePtr* at = NULL;
923 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
924 return new PhiNode(r, t, at);
925 }
926
927
928 //------------------------slice_memory-----------------------------------------
929 // create a new phi with narrowed memory type
930 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
931 PhiNode* mem = (PhiNode*) clone();
932 *(const TypePtr**)&mem->_adr_type = adr_type;
933 // convert self-loops, or else we get a bad graph
934 for (uint i = 1; i < req(); i++) {
935 if ((const Node*)in(i) == this) mem->set_req(i, mem);
936 }
937 mem->verify_adr_type();
938 return mem;
939 }
940
941 //------------------------split_out_instance-----------------------------------
942 // Split out an instance type from a bottom phi.
943 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const {
944 const TypeOopPtr *t_oop = at->isa_oopptr();
945 assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr");
946 const TypePtr *t = adr_type();
947 assert(type() == Type::MEMORY &&
948 (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
949 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
950 t->is_oopptr()->cast_to_exactness(true)
951 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
952 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop),
953 "bottom or raw memory required");
954
955 // Check if an appropriate node already exists.
956 Node *region = in(0);
957 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) {
958 Node* use = region->fast_out(k);
959 if( use->is_Phi()) {
960 PhiNode *phi2 = use->as_Phi();
961 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) {
962 return phi2;
963 }
964 }
965 }
966 Compile *C = igvn->C;
967 Arena *a = Thread::current()->resource_area();
968 Node_Array node_map = new Node_Array(a);
969 Node_Stack stack(a, C->live_nodes() >> 4);
970 PhiNode *nphi = slice_memory(at);
971 igvn->register_new_node_with_optimizer( nphi );
972 node_map.map(_idx, nphi);
973 stack.push((Node *)this, 1);
974 while(!stack.is_empty()) {
975 PhiNode *ophi = stack.node()->as_Phi();
976 uint i = stack.index();
977 assert(i >= 1, "not control edge");
978 stack.pop();
979 nphi = node_map[ophi->_idx]->as_Phi();
980 for (; i < ophi->req(); i++) {
981 Node *in = ophi->in(i);
982 if (in == NULL || igvn->type(in) == Type::TOP)
983 continue;
984 Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, NULL, igvn);
985 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL;
986 if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) {
987 opt = node_map[optphi->_idx];
988 if (opt == NULL) {
989 stack.push(ophi, i);
990 nphi = optphi->slice_memory(at);
991 igvn->register_new_node_with_optimizer( nphi );
992 node_map.map(optphi->_idx, nphi);
993 ophi = optphi;
994 i = 0; // will get incremented at top of loop
995 continue;
996 }
997 }
998 nphi->set_req(i, opt);
999 }
1000 }
1001 return nphi;
1002 }
1003
1004 //------------------------verify_adr_type--------------------------------------
1005 #ifdef ASSERT
1006 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
1007 if (visited.test_set(_idx)) return; //already visited
1008
1009 // recheck constructor invariants:
1010 verify_adr_type(false);
1011
1012 // recheck local phi/phi consistency:
1013 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
1014 "adr_type must be consistent across phi nest");
1015
1016 // walk around
1017 for (uint i = 1; i < req(); i++) {
1018 Node* n = in(i);
1019 if (n == NULL) continue;
1020 const Node* np = in(i);
1021 if (np->is_Phi()) {
1022 np->as_Phi()->verify_adr_type(visited, at);
1023 } else if (n->bottom_type() == Type::TOP
1024 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
1025 // ignore top inputs
1026 } else {
1027 const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
1028 // recheck phi/non-phi consistency at leaves:
1029 assert((nat != NULL) == (at != NULL), "");
1030 assert(nat == at || nat == TypePtr::BOTTOM,
1031 "adr_type must be consistent at leaves of phi nest");
1032 }
1033 }
1034 }
1035
1036 // Verify a whole nest of phis rooted at this one.
1037 void PhiNode::verify_adr_type(bool recursive) const {
1038 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
1039 if (Node::in_dump()) return; // muzzle asserts when printing
1040
1041 assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only");
1042
1043 if (!VerifyAliases) return; // verify thoroughly only if requested
1044
1045 assert(_adr_type == flatten_phi_adr_type(_adr_type),
1046 "Phi::adr_type must be pre-normalized");
1047
1048 if (recursive) {
1049 VectorSet visited;
1050 verify_adr_type(visited, _adr_type);
1051 }
1052 }
1053 #endif
1054
1055
1056 //------------------------------Value------------------------------------------
1057 // Compute the type of the PhiNode
1058 const Type* PhiNode::Value(PhaseGVN* phase) const {
1059 Node *r = in(0); // RegionNode
1060 if( !r ) // Copy or dead
1061 return in(1) ? phase->type(in(1)) : Type::TOP;
1062
1063 // Note: During parsing, phis are often transformed before their regions.
1064 // This means we have to use type_or_null to defend against untyped regions.
1065 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1066 return Type::TOP;
1067
1068 // Check for trip-counted loop. If so, be smarter.
1069 CountedLoopNode* l = r->is_CountedLoop() ? r->as_CountedLoop() : NULL;
1070 if (l && ((const Node*)l->phi() == this)) { // Trip counted loop!
1071 // protect against init_trip() or limit() returning NULL
1072 if (l->can_be_counted_loop(phase)) {
1073 const Node *init = l->init_trip();
1074 const Node *limit = l->limit();
1075 const Node* stride = l->stride();
1076 if (init != NULL && limit != NULL && stride != NULL) {
1077 const TypeInt* lo = phase->type(init)->isa_int();
1078 const TypeInt* hi = phase->type(limit)->isa_int();
1079 const TypeInt* stride_t = phase->type(stride)->isa_int();
1080 if (lo != NULL && hi != NULL && stride_t != NULL) { // Dying loops might have TOP here
1081 assert(stride_t->_hi >= stride_t->_lo, "bad stride type");
1082 BoolTest::mask bt = l->loopexit()->test_trip();
1083 // If the loop exit condition is "not equal", the condition
1084 // would not trigger if init > limit (if stride > 0) or if
1085 // init < limit if (stride > 0) so we can't deduce bounds
1086 // for the iv from the exit condition.
1087 if (bt != BoolTest::ne) {
1088 if (stride_t->_hi < 0) { // Down-counter loop
1089 swap(lo, hi);
1090 return TypeInt::make(MIN2(lo->_lo, hi->_lo) , hi->_hi, 3);
1091 } else if (stride_t->_lo >= 0) {
1092 return TypeInt::make(lo->_lo, MAX2(lo->_hi, hi->_hi), 3);
1093 }
1094 }
1095 }
1096 }
1097 } else if (l->in(LoopNode::LoopBackControl) != NULL &&
1098 in(LoopNode::EntryControl) != NULL &&
1099 phase->type(l->in(LoopNode::LoopBackControl)) == Type::TOP) {
1100 // During CCP, if we saturate the type of a counted loop's Phi
1101 // before the special code for counted loop above has a chance
1102 // to run (that is as long as the type of the backedge's control
1103 // is top), we might end up with non monotonic types
1104 return phase->type(in(LoopNode::EntryControl))->filter_speculative(_type);
1105 }
1106 }
1107
1108 // Until we have harmony between classes and interfaces in the type
1109 // lattice, we must tread carefully around phis which implicitly
1110 // convert the one to the other.
1111 const TypePtr* ttp = _type->make_ptr();
1112 const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL;
1113 const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_klassptr() : NULL;
1114 bool is_intf = false;
1115 if (ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
1116 is_intf = true;
1117 } else if (ttkp != NULL && ttkp->is_loaded() && ttkp->klass()->is_interface()) {
1118 is_intf = true;
1119 }
1120
1121 // Default case: merge all inputs
1122 const Type *t = Type::TOP; // Merged type starting value
1123 for (uint i = 1; i < req(); ++i) {// For all paths in
1124 // Reachable control path?
1125 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
1126 const Type* ti = phase->type(in(i));
1127 // We assume that each input of an interface-valued Phi is a true
1128 // subtype of that interface. This might not be true of the meet
1129 // of all the input types. The lattice is not distributive in
1130 // such cases. Ward off asserts in type.cpp by refusing to do
1131 // meets between interfaces and proper classes.
1132 const TypePtr* tip = ti->make_ptr();
1133 const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL;
1134 if (tiip) {
1135 bool ti_is_intf = false;
1136 ciKlass* k = tiip->klass();
1137 if (k->is_loaded() && k->is_interface())
1138 ti_is_intf = true;
1139 if (is_intf != ti_is_intf)
1140 { t = _type; break; }
1141 }
1142 t = t->meet_speculative(ti);
1143 }
1144 }
1145
1146 // The worst-case type (from ciTypeFlow) should be consistent with "t".
1147 // That is, we expect that "t->higher_equal(_type)" holds true.
1148 // There are various exceptions:
1149 // - Inputs which are phis might in fact be widened unnecessarily.
1150 // For example, an input might be a widened int while the phi is a short.
1151 // - Inputs might be BotPtrs but this phi is dependent on a null check,
1152 // and postCCP has removed the cast which encodes the result of the check.
1153 // - The type of this phi is an interface, and the inputs are classes.
1154 // - Value calls on inputs might produce fuzzy results.
1155 // (Occurrences of this case suggest improvements to Value methods.)
1156 //
1157 // It is not possible to see Type::BOTTOM values as phi inputs,
1158 // because the ciTypeFlow pre-pass produces verifier-quality types.
1159 const Type* ft = t->filter_speculative(_type); // Worst case type
1160
1161 #ifdef ASSERT
1162 // The following logic has been moved into TypeOopPtr::filter.
1163 const Type* jt = t->join_speculative(_type);
1164 if (jt->empty()) { // Emptied out???
1165
1166 // Check for evil case of 't' being a class and '_type' expecting an
1167 // interface. This can happen because the bytecodes do not contain
1168 // enough type info to distinguish a Java-level interface variable
1169 // from a Java-level object variable. If we meet 2 classes which
1170 // both implement interface I, but their meet is at 'j/l/O' which
1171 // doesn't implement I, we have no way to tell if the result should
1172 // be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows
1173 // into a Phi which "knows" it's an Interface type we'll have to
1174 // uplift the type.
1175 if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
1176 assert(ft == _type, ""); // Uplift to interface
1177 } else if (!t->empty() && ttkp != NULL && ttkp->is_loaded() && ttkp->klass()->is_interface()) {
1178 assert(ft == _type, ""); // Uplift to interface
1179 } else {
1180 // We also have to handle 'evil cases' of interface- vs. class-arrays
1181 Type::get_arrays_base_elements(jt, _type, NULL, &ttip);
1182 if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
1183 assert(ft == _type, ""); // Uplift to array of interface
1184 } else {
1185 // Otherwise it's something stupid like non-overlapping int ranges
1186 // found on dying counted loops.
1187 assert(ft == Type::TOP, ""); // Canonical empty value
1188 }
1189 }
1190 }
1191
1192 else {
1193
1194 // If we have an interface-typed Phi and we narrow to a class type, the join
1195 // should report back the class. However, if we have a J/L/Object
1196 // class-typed Phi and an interface flows in, it's possible that the meet &
1197 // join report an interface back out. This isn't possible but happens
1198 // because the type system doesn't interact well with interfaces.
1199 const TypePtr *jtp = jt->make_ptr();
1200 const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL;
1201 const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_klassptr() : NULL;
1202 if( jtip && ttip ) {
1203 if( jtip->is_loaded() && jtip->klass()->is_interface() &&
1204 ttip->is_loaded() && !ttip->klass()->is_interface() ) {
1205 assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) ||
1206 ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), "");
1207 jt = ft;
1208 }
1209 }
1210 if( jtkp && ttkp ) {
1211 if( jtkp->is_loaded() && jtkp->klass()->is_interface() &&
1212 !jtkp->klass_is_exact() && // Keep exact interface klass (6894807)
1213 ttkp->is_loaded() && !ttkp->klass()->is_interface() ) {
1214 assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) ||
1215 ft->isa_narrowklass() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), "");
1216 jt = ft;
1217 }
1218 }
1219 if (jt != ft && jt->base() == ft->base()) {
1220 if (jt->isa_int() &&
1221 jt->is_int()->_lo == ft->is_int()->_lo &&
1222 jt->is_int()->_hi == ft->is_int()->_hi)
1223 jt = ft;
1224 if (jt->isa_long() &&
1225 jt->is_long()->_lo == ft->is_long()->_lo &&
1226 jt->is_long()->_hi == ft->is_long()->_hi)
1227 jt = ft;
1228 }
1229 if (jt != ft) {
1230 tty->print("merge type: "); t->dump(); tty->cr();
1231 tty->print("kill type: "); _type->dump(); tty->cr();
1232 tty->print("join type: "); jt->dump(); tty->cr();
1233 tty->print("filter type: "); ft->dump(); tty->cr();
1234 }
1235 assert(jt == ft, "");
1236 }
1237 #endif //ASSERT
1238
1239 // Deal with conversion problems found in data loops.
1240 ft = phase->saturate(ft, phase->type_or_null(this), _type);
1241
1242 return ft;
1243 }
1244
1245
1246 //------------------------------is_diamond_phi---------------------------------
1247 // Does this Phi represent a simple well-shaped diamond merge? Return the
1248 // index of the true path or 0 otherwise.
1249 // If check_control_only is true, do not inspect the If node at the
1250 // top, and return -1 (not an edge number) on success.
1251 int PhiNode::is_diamond_phi(bool check_control_only) const {
1252 // Check for a 2-path merge
1253 Node *region = in(0);
1254 if( !region ) return 0;
1255 if( region->req() != 3 ) return 0;
1256 if( req() != 3 ) return 0;
1257 // Check that both paths come from the same If
1258 Node *ifp1 = region->in(1);
1259 Node *ifp2 = region->in(2);
1260 if( !ifp1 || !ifp2 ) return 0;
1261 Node *iff = ifp1->in(0);
1262 if( !iff || !iff->is_If() ) return 0;
1263 if( iff != ifp2->in(0) ) return 0;
1264 if (check_control_only) return -1;
1265 // Check for a proper bool/cmp
1266 const Node *b = iff->in(1);
1267 if( !b->is_Bool() ) return 0;
1268 const Node *cmp = b->in(1);
1269 if( !cmp->is_Cmp() ) return 0;
1270
1271 // Check for branching opposite expected
1272 if( ifp2->Opcode() == Op_IfTrue ) {
1273 assert( ifp1->Opcode() == Op_IfFalse, "" );
1274 return 2;
1275 } else {
1276 assert( ifp1->Opcode() == Op_IfTrue, "" );
1277 return 1;
1278 }
1279 }
1280
1281 //----------------------------check_cmove_id-----------------------------------
1282 // Check for CMove'ing a constant after comparing against the constant.
1283 // Happens all the time now, since if we compare equality vs a constant in
1284 // the parser, we "know" the variable is constant on one path and we force
1285 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
1286 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more
1287 // general in that we don't need constants. Since CMove's are only inserted
1288 // in very special circumstances, we do it here on generic Phi's.
1289 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
1290 assert(true_path !=0, "only diamond shape graph expected");
1291
1292 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1293 // phi->region->if_proj->ifnode->bool->cmp
1294 Node* region = in(0);
1295 Node* iff = region->in(1)->in(0);
1296 BoolNode* b = iff->in(1)->as_Bool();
1297 Node* cmp = b->in(1);
1298 Node* tval = in(true_path);
1299 Node* fval = in(3-true_path);
1300 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
1301 if (id == NULL)
1302 return NULL;
1303
1304 // Either value might be a cast that depends on a branch of 'iff'.
1305 // Since the 'id' value will float free of the diamond, either
1306 // decast or return failure.
1307 Node* ctl = id->in(0);
1308 if (ctl != NULL && ctl->in(0) == iff) {
1309 if (id->is_ConstraintCast()) {
1310 return id->in(1);
1311 } else {
1312 // Don't know how to disentangle this value.
1313 return NULL;
1314 }
1315 }
1316
1317 return id;
1318 }
1319
1320 //------------------------------Identity---------------------------------------
1321 // Check for Region being Identity.
1322 Node* PhiNode::Identity(PhaseGVN* phase) {
1323 // Check for no merging going on
1324 // (There used to be special-case code here when this->region->is_Loop.
1325 // It would check for a tributary phi on the backedge that the main phi
1326 // trivially, perhaps with a single cast. The unique_input method
1327 // does all this and more, by reducing such tributaries to 'this'.)
1328 Node* uin = unique_input(phase, false);
1329 if (uin != NULL) {
1330 return uin;
1331 }
1332
1333 int true_path = is_diamond_phi();
1334 if (true_path != 0) {
1335 Node* id = is_cmove_id(phase, true_path);
1336 if (id != NULL) return id;
1337 }
1338
1339 if (phase->is_IterGVN()) {
1340 Node* m = try_clean_mem_phi(phase);
1341 if (m != NULL) {
1342 return m;
1343 }
1344 }
1345
1346
1347 // Looking for phis with identical inputs. If we find one that has
1348 // type TypePtr::BOTTOM, replace the current phi with the bottom phi.
1349 if (phase->is_IterGVN() && type() == Type::MEMORY && adr_type() !=
1350 TypePtr::BOTTOM && !adr_type()->is_known_instance()) {
1351 uint phi_len = req();
1352 Node* phi_reg = region();
1353 for (DUIterator_Fast imax, i = phi_reg->fast_outs(imax); i < imax; i++) {
1354 Node* u = phi_reg->fast_out(i);
1355 if (u->is_Phi() && u->as_Phi()->type() == Type::MEMORY &&
1356 u->adr_type() == TypePtr::BOTTOM && u->in(0) == phi_reg &&
1357 u->req() == phi_len) {
1358 for (uint j = 1; j < phi_len; j++) {
1359 if (in(j) != u->in(j)) {
1360 u = NULL;
1361 break;
1362 }
1363 }
1364 if (u != NULL) {
1365 return u;
1366 }
1367 }
1368 }
1369 }
1370
1371 return this; // No identity
1372 }
1373
1374 //-----------------------------unique_input------------------------------------
1375 // Find the unique value, discounting top, self-loops, and casts.
1376 // Return top if there are no inputs, and self if there are multiple.
1377 Node* PhiNode::unique_input(PhaseTransform* phase, bool uncast) {
1378 // 1) One unique direct input,
1379 // or if uncast is true:
1380 // 2) some of the inputs have an intervening ConstraintCast
1381 // 3) an input is a self loop
1382 //
1383 // 1) input or 2) input or 3) input __
1384 // / \ / \ \ / \
1385 // \ / | cast phi cast
1386 // phi \ / / \ /
1387 // phi / --
1388
1389 Node* r = in(0); // RegionNode
1390 if (r == NULL) return in(1); // Already degraded to a Copy
1391 Node* input = NULL; // The unique direct input (maybe uncasted = ConstraintCasts removed)
1392
1393 for (uint i = 1, cnt = req(); i < cnt; ++i) {
1394 Node* rc = r->in(i);
1395 if (rc == NULL || phase->type(rc) == Type::TOP)
1396 continue; // ignore unreachable control path
1397 Node* n = in(i);
1398 if (n == NULL)
1399 continue;
1400 Node* un = n;
1401 if (uncast) {
1402 #ifdef ASSERT
1403 Node* m = un->uncast();
1404 #endif
1405 while (un != NULL && un->req() == 2 && un->is_ConstraintCast()) {
1406 Node* next = un->in(1);
1407 if (phase->type(next)->isa_rawptr() && phase->type(un)->isa_oopptr()) {
1408 // risk exposing raw ptr at safepoint
1409 break;
1410 }
1411 un = next;
1412 }
1413 assert(m == un || un->in(1) == m, "Only expected at CheckCastPP from allocation");
1414 }
1415 if (un == NULL || un == this || phase->type(un) == Type::TOP) {
1416 continue; // ignore if top, or in(i) and "this" are in a data cycle
1417 }
1418 // Check for a unique input (maybe uncasted)
1419 if (input == NULL) {
1420 input = un;
1421 } else if (input != un) {
1422 input = NodeSentinel; // no unique input
1423 }
1424 }
1425 if (input == NULL) {
1426 return phase->C->top(); // no inputs
1427 }
1428
1429 if (input != NodeSentinel) {
1430 return input; // one unique direct input
1431 }
1432
1433 // Nothing.
1434 return NULL;
1435 }
1436
1437 //------------------------------is_x2logic-------------------------------------
1438 // Check for simple convert-to-boolean pattern
1439 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
1440 // Convert Phi to an ConvIB.
1441 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
1442 assert(true_path !=0, "only diamond shape graph expected");
1443 // Convert the true/false index into an expected 0/1 return.
1444 // Map 2->0 and 1->1.
1445 int flipped = 2-true_path;
1446
1447 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1448 // phi->region->if_proj->ifnode->bool->cmp
1449 Node *region = phi->in(0);
1450 Node *iff = region->in(1)->in(0);
1451 BoolNode *b = (BoolNode*)iff->in(1);
1452 const CmpNode *cmp = (CmpNode*)b->in(1);
1453
1454 Node *zero = phi->in(1);
1455 Node *one = phi->in(2);
1456 const Type *tzero = phase->type( zero );
1457 const Type *tone = phase->type( one );
1458
1459 // Check for compare vs 0
1460 const Type *tcmp = phase->type(cmp->in(2));
1461 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
1462 // Allow cmp-vs-1 if the other input is bounded by 0-1
1463 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
1464 return NULL;
1465 flipped = 1-flipped; // Test is vs 1 instead of 0!
1466 }
1467
1468 // Check for setting zero/one opposite expected
1469 if( tzero == TypeInt::ZERO ) {
1470 if( tone == TypeInt::ONE ) {
1471 } else return NULL;
1472 } else if( tzero == TypeInt::ONE ) {
1473 if( tone == TypeInt::ZERO ) {
1474 flipped = 1-flipped;
1475 } else return NULL;
1476 } else return NULL;
1477
1478 // Check for boolean test backwards
1479 if( b->_test._test == BoolTest::ne ) {
1480 } else if( b->_test._test == BoolTest::eq ) {
1481 flipped = 1-flipped;
1482 } else return NULL;
1483
1484 // Build int->bool conversion
1485 Node *n = new Conv2BNode(cmp->in(1));
1486 if( flipped )
1487 n = new XorINode( phase->transform(n), phase->intcon(1) );
1488
1489 return n;
1490 }
1491
1492 //------------------------------is_cond_add------------------------------------
1493 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;"
1494 // To be profitable the control flow has to disappear; there can be no other
1495 // values merging here. We replace the test-and-branch with:
1496 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by
1497 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
1498 // Then convert Y to 0-or-Y and finally add.
1499 // This is a key transform for SpecJava _201_compress.
1500 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
1501 assert(true_path !=0, "only diamond shape graph expected");
1502
1503 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1504 // phi->region->if_proj->ifnode->bool->cmp
1505 RegionNode *region = (RegionNode*)phi->in(0);
1506 Node *iff = region->in(1)->in(0);
1507 BoolNode* b = iff->in(1)->as_Bool();
1508 const CmpNode *cmp = (CmpNode*)b->in(1);
1509
1510 // Make sure only merging this one phi here
1511 if (region->has_unique_phi() != phi) return NULL;
1512
1513 // Make sure each arm of the diamond has exactly one output, which we assume
1514 // is the region. Otherwise, the control flow won't disappear.
1515 if (region->in(1)->outcnt() != 1) return NULL;
1516 if (region->in(2)->outcnt() != 1) return NULL;
1517
1518 // Check for "(P < Q)" of type signed int
1519 if (b->_test._test != BoolTest::lt) return NULL;
1520 if (cmp->Opcode() != Op_CmpI) return NULL;
1521
1522 Node *p = cmp->in(1);
1523 Node *q = cmp->in(2);
1524 Node *n1 = phi->in( true_path);
1525 Node *n2 = phi->in(3-true_path);
1526
1527 int op = n1->Opcode();
1528 if( op != Op_AddI // Need zero as additive identity
1529 /*&&op != Op_SubI &&
1530 op != Op_AddP &&
1531 op != Op_XorI &&
1532 op != Op_OrI*/ )
1533 return NULL;
1534
1535 Node *x = n2;
1536 Node *y = NULL;
1537 if( x == n1->in(1) ) {
1538 y = n1->in(2);
1539 } else if( x == n1->in(2) ) {
1540 y = n1->in(1);
1541 } else return NULL;
1542
1543 // Not so profitable if compare and add are constants
1544 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
1545 return NULL;
1546
1547 Node *cmplt = phase->transform( new CmpLTMaskNode(p,q) );
1548 Node *j_and = phase->transform( new AndINode(cmplt,y) );
1549 return new AddINode(j_and,x);
1550 }
1551
1552 //------------------------------is_absolute------------------------------------
1553 // Check for absolute value.
1554 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
1555 assert(true_path !=0, "only diamond shape graph expected");
1556
1557 int cmp_zero_idx = 0; // Index of compare input where to look for zero
1558 int phi_x_idx = 0; // Index of phi input where to find naked x
1559
1560 // ABS ends with the merge of 2 control flow paths.
1561 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
1562 int false_path = 3 - true_path;
1563
1564 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1565 // phi->region->if_proj->ifnode->bool->cmp
1566 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
1567 Node *cmp = bol->in(1);
1568
1569 // Check bool sense
1570 if (cmp->Opcode() == Op_CmpF || cmp->Opcode() == Op_CmpD) {
1571 switch (bol->_test._test) {
1572 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break;
1573 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1574 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1575 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
1576 default: return NULL; break;
1577 }
1578 } else if (cmp->Opcode() == Op_CmpI || cmp->Opcode() == Op_CmpL) {
1579 switch (bol->_test._test) {
1580 case BoolTest::lt:
1581 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1582 case BoolTest::gt:
1583 case BoolTest::ge: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1584 default: return NULL; break;
1585 }
1586 }
1587
1588 // Test is next
1589 const Type *tzero = NULL;
1590 switch (cmp->Opcode()) {
1591 case Op_CmpI: tzero = TypeInt::ZERO; break; // Integer ABS
1592 case Op_CmpL: tzero = TypeLong::ZERO; break; // Long ABS
1593 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS
1594 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS
1595 default: return NULL;
1596 }
1597
1598 // Find zero input of compare; the other input is being abs'd
1599 Node *x = NULL;
1600 bool flip = false;
1601 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
1602 x = cmp->in(3 - cmp_zero_idx);
1603 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
1604 // The test is inverted, we should invert the result...
1605 x = cmp->in(cmp_zero_idx);
1606 flip = true;
1607 } else {
1608 return NULL;
1609 }
1610
1611 // Next get the 2 pieces being selected, one is the original value
1612 // and the other is the negated value.
1613 if( phi_root->in(phi_x_idx) != x ) return NULL;
1614
1615 // Check other phi input for subtract node
1616 Node *sub = phi_root->in(3 - phi_x_idx);
1617
1618 // Allow only Sub(0,X) and fail out for all others; Neg is not OK
1619 if( tzero == TypeF::ZERO ) {
1620 if( sub->Opcode() != Op_SubF ||
1621 sub->in(2) != x ||
1622 phase->type(sub->in(1)) != tzero ) return NULL;
1623 x = new AbsFNode(x);
1624 if (flip) {
1625 x = new SubFNode(sub->in(1), phase->transform(x));
1626 }
1627 } else if (tzero == TypeD::ZERO) {
1628 if( sub->Opcode() != Op_SubD ||
1629 sub->in(2) != x ||
1630 phase->type(sub->in(1)) != tzero ) return NULL;
1631 x = new AbsDNode(x);
1632 if (flip) {
1633 x = new SubDNode(sub->in(1), phase->transform(x));
1634 }
1635 } else if (tzero == TypeInt::ZERO) {
1636 if (sub->Opcode() != Op_SubI ||
1637 sub->in(2) != x ||
1638 phase->type(sub->in(1)) != tzero) return NULL;
1639 x = new AbsINode(x);
1640 if (flip) {
1641 x = new SubINode(sub->in(1), phase->transform(x));
1642 }
1643 } else {
1644 if (sub->Opcode() != Op_SubL ||
1645 sub->in(2) != x ||
1646 phase->type(sub->in(1)) != tzero) return NULL;
1647 x = new AbsLNode(x);
1648 if (flip) {
1649 x = new SubLNode(sub->in(1), phase->transform(x));
1650 }
1651 }
1652
1653 return x;
1654 }
1655
1656 //------------------------------split_once-------------------------------------
1657 // Helper for split_flow_path
1658 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
1659 igvn->hash_delete(n); // Remove from hash before hacking edges
1660
1661 uint j = 1;
1662 for (uint i = phi->req()-1; i > 0; i--) {
1663 if (phi->in(i) == val) { // Found a path with val?
1664 // Add to NEW Region/Phi, no DU info
1665 newn->set_req( j++, n->in(i) );
1666 // Remove from OLD Region/Phi
1667 n->del_req(i);
1668 }
1669 }
1670
1671 // Register the new node but do not transform it. Cannot transform until the
1672 // entire Region/Phi conglomerate has been hacked as a single huge transform.
1673 igvn->register_new_node_with_optimizer( newn );
1674
1675 // Now I can point to the new node.
1676 n->add_req(newn);
1677 igvn->_worklist.push(n);
1678 }
1679
1680 //------------------------------split_flow_path--------------------------------
1681 // Check for merging identical values and split flow paths
1682 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) {
1683 BasicType bt = phi->type()->basic_type();
1684 if( bt == T_ILLEGAL || type2size[bt] <= 0 )
1685 return NULL; // Bail out on funny non-value stuff
1686 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a
1687 return NULL; // third unequal input to be worth doing
1688
1689 // Scan for a constant
1690 uint i;
1691 for( i = 1; i < phi->req()-1; i++ ) {
1692 Node *n = phi->in(i);
1693 if( !n ) return NULL;
1694 if( phase->type(n) == Type::TOP ) return NULL;
1695 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN || n->Opcode() == Op_ConNKlass )
1696 break;
1697 }
1698 if( i >= phi->req() ) // Only split for constants
1699 return NULL;
1700
1701 Node *val = phi->in(i); // Constant to split for
1702 uint hit = 0; // Number of times it occurs
1703 Node *r = phi->region();
1704
1705 for( ; i < phi->req(); i++ ){ // Count occurrences of constant
1706 Node *n = phi->in(i);
1707 if( !n ) return NULL;
1708 if( phase->type(n) == Type::TOP ) return NULL;
1709 if( phi->in(i) == val ) {
1710 hit++;
1711 if (PhaseIdealLoop::find_predicate(r->in(i)) != NULL) {
1712 return NULL; // don't split loop entry path
1713 }
1714 }
1715 }
1716
1717 if( hit <= 1 || // Make sure we find 2 or more
1718 hit == phi->req()-1 ) // and not ALL the same value
1719 return NULL;
1720
1721 // Now start splitting out the flow paths that merge the same value.
1722 // Split first the RegionNode.
1723 PhaseIterGVN *igvn = phase->is_IterGVN();
1724 RegionNode *newr = new RegionNode(hit+1);
1725 split_once(igvn, phi, val, r, newr);
1726
1727 // Now split all other Phis than this one
1728 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) {
1729 Node* phi2 = r->fast_out(k);
1730 if( phi2->is_Phi() && phi2->as_Phi() != phi ) {
1731 PhiNode *newphi = PhiNode::make_blank(newr, phi2);
1732 split_once(igvn, phi, val, phi2, newphi);
1733 }
1734 }
1735
1736 // Clean up this guy
1737 igvn->hash_delete(phi);
1738 for( i = phi->req()-1; i > 0; i-- ) {
1739 if( phi->in(i) == val ) {
1740 phi->del_req(i);
1741 }
1742 }
1743 phi->add_req(val);
1744
1745 return phi;
1746 }
1747
1748 //=============================================================================
1749 //------------------------------simple_data_loop_check-------------------------
1750 // Try to determining if the phi node in a simple safe/unsafe data loop.
1751 // Returns:
1752 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
1753 // Safe - safe case when the phi and it's inputs reference only safe data
1754 // nodes;
1755 // Unsafe - the phi and it's inputs reference unsafe data nodes but there
1756 // is no reference back to the phi - need a graph walk
1757 // to determine if it is in a loop;
1758 // UnsafeLoop - unsafe case when the phi references itself directly or through
1759 // unsafe data node.
1760 // Note: a safe data node is a node which could/never reference itself during
1761 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP.
1762 // I mark Phi nodes as safe node not only because they can reference itself
1763 // but also to prevent mistaking the fallthrough case inside an outer loop
1764 // as dead loop when the phi references itselfs through an other phi.
1765 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const {
1766 // It is unsafe loop if the phi node references itself directly.
1767 if (in == (Node*)this)
1768 return UnsafeLoop; // Unsafe loop
1769 // Unsafe loop if the phi node references itself through an unsafe data node.
1770 // Exclude cases with null inputs or data nodes which could reference
1771 // itself (safe for dead loops).
1772 if (in != NULL && !in->is_dead_loop_safe()) {
1773 // Check inputs of phi's inputs also.
1774 // It is much less expensive then full graph walk.
1775 uint cnt = in->req();
1776 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1;
1777 for (; i < cnt; ++i) {
1778 Node* m = in->in(i);
1779 if (m == (Node*)this)
1780 return UnsafeLoop; // Unsafe loop
1781 if (m != NULL && !m->is_dead_loop_safe()) {
1782 // Check the most common case (about 30% of all cases):
1783 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con).
1784 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL;
1785 if (m1 == (Node*)this)
1786 return UnsafeLoop; // Unsafe loop
1787 if (m1 != NULL && m1 == m->in(2) &&
1788 m1->is_dead_loop_safe() && m->in(3)->is_Con()) {
1789 continue; // Safe case
1790 }
1791 // The phi references an unsafe node - need full analysis.
1792 return Unsafe;
1793 }
1794 }
1795 }
1796 return Safe; // Safe case - we can optimize the phi node.
1797 }
1798
1799 //------------------------------is_unsafe_data_reference-----------------------
1800 // If phi can be reached through the data input - it is data loop.
1801 bool PhiNode::is_unsafe_data_reference(Node *in) const {
1802 assert(req() > 1, "");
1803 // First, check simple cases when phi references itself directly or
1804 // through an other node.
1805 LoopSafety safety = simple_data_loop_check(in);
1806 if (safety == UnsafeLoop)
1807 return true; // phi references itself - unsafe loop
1808 else if (safety == Safe)
1809 return false; // Safe case - phi could be replaced with the unique input.
1810
1811 // Unsafe case when we should go through data graph to determine
1812 // if the phi references itself.
1813
1814 ResourceMark rm;
1815
1816 Node_List nstack;
1817 VectorSet visited;
1818
1819 nstack.push(in); // Start with unique input.
1820 visited.set(in->_idx);
1821 while (nstack.size() != 0) {
1822 Node* n = nstack.pop();
1823 uint cnt = n->req();
1824 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1;
1825 for (; i < cnt; i++) {
1826 Node* m = n->in(i);
1827 if (m == (Node*)this) {
1828 return true; // Data loop
1829 }
1830 if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases.
1831 if (!visited.test_set(m->_idx))
1832 nstack.push(m);
1833 }
1834 }
1835 }
1836 return false; // The phi is not reachable from its inputs
1837 }
1838
1839 // Is this Phi's region or some inputs to the region enqueued for IGVN
1840 // and so could cause the region to be optimized out?
1841 bool PhiNode::wait_for_region_igvn(PhaseGVN* phase) {
1842 PhaseIterGVN* igvn = phase->is_IterGVN();
1843 Unique_Node_List& worklist = igvn->_worklist;
1844 bool delay = false;
1845 Node* r = in(0);
1846 for (uint j = 1; j < req(); j++) {
1847 Node* rc = r->in(j);
1848 Node* n = in(j);
1849 if (rc != NULL &&
1850 rc->is_Proj()) {
1851 if (worklist.member(rc)) {
1852 delay = true;
1853 } else if (rc->in(0) != NULL &&
1854 rc->in(0)->is_If()) {
1855 if (worklist.member(rc->in(0))) {
1856 delay = true;
1857 } else if (rc->in(0)->in(1) != NULL &&
1858 rc->in(0)->in(1)->is_Bool()) {
1859 if (worklist.member(rc->in(0)->in(1))) {
1860 delay = true;
1861 } else if (rc->in(0)->in(1)->in(1) != NULL &&
1862 rc->in(0)->in(1)->in(1)->is_Cmp()) {
1863 if (worklist.member(rc->in(0)->in(1)->in(1))) {
1864 delay = true;
1865 }
1866 }
1867 }
1868 }
1869 }
1870 }
1871 if (delay) {
1872 worklist.push(this);
1873 }
1874 return delay;
1875 }
1876
1877 //------------------------------Ideal------------------------------------------
1878 // Return a node which is more "ideal" than the current node. Must preserve
1879 // the CFG, but we can still strip out dead paths.
1880 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1881 // The next should never happen after 6297035 fix.
1882 if( is_copy() ) // Already degraded to a Copy ?
1883 return NULL; // No change
1884
1885 Node *r = in(0); // RegionNode
1886 assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge");
1887
1888 // Note: During parsing, phis are often transformed before their regions.
1889 // This means we have to use type_or_null to defend against untyped regions.
1890 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1891 return NULL; // No change
1892
1893 // If all inputs are inline types of the same type, push the inline type node down
1894 // through the phi because inline type nodes should be merged through their input values.
1895 if (req() > 2 && in(1) != NULL && in(1)->is_InlineTypeBase() && (can_reshape || in(1)->is_InlineType())) {
1896 int opcode = in(1)->Opcode();
1897 uint i = 2;
1898 // Check if inputs are values of the same type
1899 for (; i < req() && in(i) && in(i)->is_InlineTypeBase() && in(i)->cmp(*in(1)); i++) {
1900 assert(in(i)->Opcode() == opcode, "mixing pointers and values?");
1901 }
1902 if (i == req()) {
1903 InlineTypeBaseNode* vt = in(1)->as_InlineTypeBase()->clone_with_phis(phase, in(0));
1904 for (uint i = 2; i < req(); ++i) {
1905 vt->merge_with(phase, in(i)->as_InlineTypeBase(), i, i == (req()-1));
1906 }
1907 return vt;
1908 }
1909 }
1910
1911 Node *top = phase->C->top();
1912 bool new_phi = (outcnt() == 0); // transforming new Phi
1913 // No change for igvn if new phi is not hooked
1914 if (new_phi && can_reshape)
1915 return NULL;
1916
1917 // The are 2 situations when only one valid phi's input is left
1918 // (in addition to Region input).
1919 // One: region is not loop - replace phi with this input.
1920 // Two: region is loop - replace phi with top since this data path is dead
1921 // and we need to break the dead data loop.
1922 Node* progress = NULL; // Record if any progress made
1923 for( uint j = 1; j < req(); ++j ){ // For all paths in
1924 // Check unreachable control paths
1925 Node* rc = r->in(j);
1926 Node* n = in(j); // Get the input
1927 if (rc == NULL || phase->type(rc) == Type::TOP) {
1928 if (n != top) { // Not already top?
1929 PhaseIterGVN *igvn = phase->is_IterGVN();
1930 if (can_reshape && igvn != NULL) {
1931 igvn->_worklist.push(r);
1932 }
1933 // Nuke it down
1934 if (can_reshape) {
1935 set_req_X(j, top, igvn);
1936 } else {
1937 set_req(j, top);
1938 }
1939 progress = this; // Record progress
1940 }
1941 }
1942 }
1943
1944 if (can_reshape && outcnt() == 0) {
1945 // set_req() above may kill outputs if Phi is referenced
1946 // only by itself on the dead (top) control path.
1947 return top;
1948 }
1949
1950 bool uncasted = false;
1951 Node* uin = unique_input(phase, false);
1952 if (uin == NULL && can_reshape &&
1953 // If there is a chance that the region can be optimized out do
1954 // not add a cast node that we can't remove yet.
1955 !wait_for_region_igvn(phase)) {
1956 uncasted = true;
1957 uin = unique_input(phase, true);
1958 }
1959 if (uin == top) { // Simplest case: no alive inputs.
1960 if (can_reshape) // IGVN transformation
1961 return top;
1962 else
1963 return NULL; // Identity will return TOP
1964 } else if (uin != NULL) {
1965 // Only one not-NULL unique input path is left.
1966 // Determine if this input is backedge of a loop.
1967 // (Skip new phis which have no uses and dead regions).
1968 if (outcnt() > 0 && r->in(0) != NULL) {
1969 // First, take the short cut when we know it is a loop and
1970 // the EntryControl data path is dead.
1971 // Loop node may have only one input because entry path
1972 // is removed in PhaseIdealLoop::Dominators().
1973 assert(!r->is_Loop() || r->req() <= 3, "Loop node should have 3 or less inputs");
1974 bool is_loop = (r->is_Loop() && r->req() == 3);
1975 // Then, check if there is a data loop when phi references itself directly
1976 // or through other data nodes.
1977 if ((is_loop && !uin->eqv_uncast(in(LoopNode::EntryControl))) ||
1978 (!is_loop && is_unsafe_data_reference(uin))) {
1979 // Break this data loop to avoid creation of a dead loop.
1980 if (can_reshape) {
1981 return top;
1982 } else {
1983 // We can't return top if we are in Parse phase - cut inputs only
1984 // let Identity to handle the case.
1985 replace_edge(uin, top);
1986 return NULL;
1987 }
1988 }
1989 }
1990
1991 if (uncasted) {
1992 // Add cast nodes between the phi to be removed and its unique input.
1993 // Wait until after parsing for the type information to propagate from the casts.
1994 assert(can_reshape, "Invalid during parsing");
1995 const Type* phi_type = bottom_type();
1996 assert(phi_type->isa_int() || phi_type->isa_ptr(), "bad phi type");
1997 // Add casts to carry the control dependency of the Phi that is
1998 // going away
1999 Node* cast = NULL;
2000 if (phi_type->isa_int()) {
2001 cast = ConstraintCastNode::make_cast(Op_CastII, r, uin, phi_type, true);
2002 } else {
2003 const Type* uin_type = phase->type(uin);
2004 if (!phi_type->isa_oopptr() && !uin_type->isa_oopptr()) {
2005 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true);
2006 } else {
2007 // Use a CastPP for a cast to not null and a CheckCastPP for
2008 // a cast to a new klass (and both if both null-ness and
2009 // klass change).
2010
2011 // If the type of phi is not null but the type of uin may be
2012 // null, uin's type must be casted to not null
2013 if (phi_type->join(TypePtr::NOTNULL) == phi_type->remove_speculative() &&
2014 uin_type->join(TypePtr::NOTNULL) != uin_type->remove_speculative()) {
2015 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, TypePtr::NOTNULL, true);
2016 }
2017
2018 // If the type of phi and uin, both casted to not null,
2019 // differ the klass of uin must be (check)cast'ed to match
2020 // that of phi
2021 if (phi_type->join_speculative(TypePtr::NOTNULL) != uin_type->join_speculative(TypePtr::NOTNULL)) {
2022 Node* n = uin;
2023 if (cast != NULL) {
2024 cast = phase->transform(cast);
2025 n = cast;
2026 }
2027 cast = ConstraintCastNode::make_cast(Op_CheckCastPP, r, n, phi_type, true);
2028 }
2029 if (cast == NULL) {
2030 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true);
2031 }
2032 }
2033 }
2034 assert(cast != NULL, "cast should be set");
2035 cast = phase->transform(cast);
2036 // set all inputs to the new cast(s) so the Phi is removed by Identity
2037 PhaseIterGVN* igvn = phase->is_IterGVN();
2038 for (uint i = 1; i < req(); i++) {
2039 set_req_X(i, cast, igvn);
2040 }
2041 uin = cast;
2042 }
2043
2044 // One unique input.
2045 debug_only(Node* ident = Identity(phase));
2046 // The unique input must eventually be detected by the Identity call.
2047 #ifdef ASSERT
2048 if (ident != uin && !ident->is_top()) {
2049 // print this output before failing assert
2050 r->dump(3);
2051 this->dump(3);
2052 ident->dump();
2053 uin->dump();
2054 }
2055 #endif
2056 assert(ident == uin || ident->is_top(), "Identity must clean this up");
2057 return NULL;
2058 }
2059
2060 Node* opt = NULL;
2061 int true_path = is_diamond_phi();
2062 if( true_path != 0 ) {
2063 // Check for CMove'ing identity. If it would be unsafe,
2064 // handle it here. In the safe case, let Identity handle it.
2065 Node* unsafe_id = is_cmove_id(phase, true_path);
2066 if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) )
2067 opt = unsafe_id;
2068
2069 // Check for simple convert-to-boolean pattern
2070 if( opt == NULL )
2071 opt = is_x2logic(phase, this, true_path);
2072
2073 // Check for absolute value
2074 if( opt == NULL )
2075 opt = is_absolute(phase, this, true_path);
2076
2077 // Check for conditional add
2078 if( opt == NULL && can_reshape )
2079 opt = is_cond_add(phase, this, true_path);
2080
2081 // These 4 optimizations could subsume the phi:
2082 // have to check for a dead data loop creation.
2083 if( opt != NULL ) {
2084 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) {
2085 // Found dead loop.
2086 if( can_reshape )
2087 return top;
2088 // We can't return top if we are in Parse phase - cut inputs only
2089 // to stop further optimizations for this phi. Identity will return TOP.
2090 assert(req() == 3, "only diamond merge phi here");
2091 set_req(1, top);
2092 set_req(2, top);
2093 return NULL;
2094 } else {
2095 return opt;
2096 }
2097 }
2098 }
2099
2100 // Check for merging identical values and split flow paths
2101 if (can_reshape) {
2102 opt = split_flow_path(phase, this);
2103 // This optimization only modifies phi - don't need to check for dead loop.
2104 assert(opt == NULL || phase->eqv(opt, this), "do not elide phi");
2105 if (opt != NULL) return opt;
2106 }
2107
2108 if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) {
2109 // Try to undo Phi of AddP:
2110 // (Phi (AddP base address offset) (AddP base2 address2 offset2))
2111 // becomes:
2112 // newbase := (Phi base base2)
2113 // newaddress := (Phi address address2)
2114 // newoffset := (Phi offset offset2)
2115 // (AddP newbase newaddress newoffset)
2116 //
2117 // This occurs as a result of unsuccessful split_thru_phi and
2118 // interferes with taking advantage of addressing modes. See the
2119 // clone_shift_expressions code in matcher.cpp
2120 Node* addp = in(1);
2121 Node* base = addp->in(AddPNode::Base);
2122 Node* address = addp->in(AddPNode::Address);
2123 Node* offset = addp->in(AddPNode::Offset);
2124 if (base != NULL && address != NULL && offset != NULL &&
2125 !base->is_top() && !address->is_top() && !offset->is_top()) {
2126 const Type* base_type = base->bottom_type();
2127 const Type* address_type = address->bottom_type();
2128 // make sure that all the inputs are similar to the first one,
2129 // i.e. AddP with base == address and same offset as first AddP
2130 bool doit = true;
2131 for (uint i = 2; i < req(); i++) {
2132 if (in(i) == NULL ||
2133 in(i)->Opcode() != Op_AddP ||
2134 in(i)->in(AddPNode::Base) == NULL ||
2135 in(i)->in(AddPNode::Address) == NULL ||
2136 in(i)->in(AddPNode::Offset) == NULL ||
2137 in(i)->in(AddPNode::Base)->is_top() ||
2138 in(i)->in(AddPNode::Address)->is_top() ||
2139 in(i)->in(AddPNode::Offset)->is_top()) {
2140 doit = false;
2141 break;
2142 }
2143 if (in(i)->in(AddPNode::Offset) != base) {
2144 base = NULL;
2145 }
2146 if (in(i)->in(AddPNode::Offset) != offset) {
2147 offset = NULL;
2148 }
2149 if (in(i)->in(AddPNode::Address) != address) {
2150 address = NULL;
2151 }
2152 // Accumulate type for resulting Phi
2153 base_type = base_type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type());
2154 address_type = address_type->meet_speculative(in(i)->in(AddPNode::Address)->bottom_type());
2155 }
2156 if (doit && base == NULL) {
2157 // Check for neighboring AddP nodes in a tree.
2158 // If they have a base, use that it.
2159 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) {
2160 Node* u = this->fast_out(k);
2161 if (u->is_AddP()) {
2162 Node* base2 = u->in(AddPNode::Base);
2163 if (base2 != NULL && !base2->is_top()) {
2164 if (base == NULL)
2165 base = base2;
2166 else if (base != base2)
2167 { doit = false; break; }
2168 }
2169 }
2170 }
2171 }
2172 if (doit) {
2173 if (base == NULL) {
2174 base = new PhiNode(in(0), base_type, NULL);
2175 for (uint i = 1; i < req(); i++) {
2176 base->init_req(i, in(i)->in(AddPNode::Base));
2177 }
2178 phase->is_IterGVN()->register_new_node_with_optimizer(base);
2179 }
2180 if (address == NULL) {
2181 address = new PhiNode(in(0), address_type, NULL);
2182 for (uint i = 1; i < req(); i++) {
2183 address->init_req(i, in(i)->in(AddPNode::Address));
2184 }
2185 phase->is_IterGVN()->register_new_node_with_optimizer(address);
2186 }
2187 if (offset == NULL) {
2188 offset = new PhiNode(in(0), TypeX_X, NULL);
2189 for (uint i = 1; i < req(); i++) {
2190 offset->init_req(i, in(i)->in(AddPNode::Offset));
2191 }
2192 phase->is_IterGVN()->register_new_node_with_optimizer(offset);
2193 }
2194 return new AddPNode(base, address, offset);
2195 }
2196 }
2197 }
2198
2199 // Split phis through memory merges, so that the memory merges will go away.
2200 // Piggy-back this transformation on the search for a unique input....
2201 // It will be as if the merged memory is the unique value of the phi.
2202 // (Do not attempt this optimization unless parsing is complete.
2203 // It would make the parser's memory-merge logic sick.)
2204 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.)
2205 if (progress == NULL && can_reshape && type() == Type::MEMORY) {
2206 // see if this phi should be sliced
2207 uint merge_width = 0;
2208 bool saw_self = false;
2209 // TODO revisit this with JDK-8247216
2210 bool mergemem_only = true;
2211 for( uint i=1; i<req(); ++i ) {// For all paths in
2212 Node *ii = in(i);
2213 // TOP inputs should not be counted as safe inputs because if the
2214 // Phi references itself through all other inputs then splitting the
2215 // Phi through memory merges would create dead loop at later stage.
2216 if (ii == top) {
2217 return NULL; // Delay optimization until graph is cleaned.
2218 }
2219 if (ii->is_MergeMem()) {
2220 MergeMemNode* n = ii->as_MergeMem();
2221 merge_width = MAX2(merge_width, n->req());
2222 saw_self = saw_self || phase->eqv(n->base_memory(), this);
2223 } else {
2224 mergemem_only = false;
2225 }
2226 }
2227
2228 // This restriction is temporarily necessary to ensure termination:
2229 if (!mergemem_only && !saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0;
2230
2231 if (merge_width > Compile::AliasIdxRaw) {
2232 // found at least one non-empty MergeMem
2233 const TypePtr* at = adr_type();
2234 if (at != TypePtr::BOTTOM) {
2235 // Patch the existing phi to select an input from the merge:
2236 // Phi:AT1(...MergeMem(m0, m1, m2)...) into
2237 // Phi:AT1(...m1...)
2238 int alias_idx = phase->C->get_alias_index(at);
2239 for (uint i=1; i<req(); ++i) {
2240 Node *ii = in(i);
2241 if (ii->is_MergeMem()) {
2242 MergeMemNode* n = ii->as_MergeMem();
2243 // compress paths and change unreachable cycles to TOP
2244 // If not, we can update the input infinitely along a MergeMem cycle
2245 // Equivalent code is in MemNode::Ideal_common
2246 Node *m = phase->transform(n);
2247 if (outcnt() == 0) { // Above transform() may kill us!
2248 return top;
2249 }
2250 // If transformed to a MergeMem, get the desired slice
2251 // Otherwise the returned node represents memory for every slice
2252 Node *new_mem = (m->is_MergeMem()) ?
2253 m->as_MergeMem()->memory_at(alias_idx) : m;
2254 // Update input if it is progress over what we have now
2255 if (new_mem != ii) {
2256 set_req(i, new_mem);
2257 progress = this;
2258 }
2259 }
2260 }
2261 } else {
2262 // We know that at least one MergeMem->base_memory() == this
2263 // (saw_self == true). If all other inputs also references this phi
2264 // (directly or through data nodes) - it is dead loop.
2265 bool saw_safe_input = false;
2266 for (uint j = 1; j < req(); ++j) {
2267 Node *n = in(j);
2268 if (n->is_MergeMem() && n->as_MergeMem()->base_memory() == this)
2269 continue; // skip known cases
2270 if (!is_unsafe_data_reference(n)) {
2271 saw_safe_input = true; // found safe input
2272 break;
2273 }
2274 }
2275 if (!saw_safe_input)
2276 return top; // all inputs reference back to this phi - dead loop
2277
2278 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into
2279 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...))
2280 PhaseIterGVN *igvn = phase->is_IterGVN();
2281 Node* hook = new Node(1);
2282 PhiNode* new_base = (PhiNode*) clone();
2283 // Must eagerly register phis, since they participate in loops.
2284 if (igvn) {
2285 igvn->register_new_node_with_optimizer(new_base);
2286 hook->add_req(new_base);
2287 }
2288 MergeMemNode* result = MergeMemNode::make(new_base);
2289 for (uint i = 1; i < req(); ++i) {
2290 Node *ii = in(i);
2291 if (ii->is_MergeMem()) {
2292 MergeMemNode* n = ii->as_MergeMem();
2293 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) {
2294 // If we have not seen this slice yet, make a phi for it.
2295 bool made_new_phi = false;
2296 if (mms.is_empty()) {
2297 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C));
2298 made_new_phi = true;
2299 if (igvn) {
2300 igvn->register_new_node_with_optimizer(new_phi);
2301 hook->add_req(new_phi);
2302 }
2303 mms.set_memory(new_phi);
2304 }
2305 Node* phi = mms.memory();
2306 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice");
2307 phi->set_req(i, mms.memory2());
2308 }
2309 }
2310 }
2311 // Distribute all self-loops.
2312 { // (Extra braces to hide mms.)
2313 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2314 Node* phi = mms.memory();
2315 for (uint i = 1; i < req(); ++i) {
2316 if (phi->in(i) == this) phi->set_req(i, phi);
2317 }
2318 }
2319 }
2320 // now transform the new nodes, and return the mergemem
2321 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2322 Node* phi = mms.memory();
2323 mms.set_memory(phase->transform(phi));
2324 }
2325 if (igvn) { // Unhook.
2326 igvn->hash_delete(hook);
2327 for (uint i = 1; i < hook->req(); i++) {
2328 hook->set_req(i, NULL);
2329 }
2330 }
2331 // Replace self with the result.
2332 return result;
2333 }
2334 }
2335 //
2336 // Other optimizations on the memory chain
2337 //
2338 const TypePtr* at = adr_type();
2339 for( uint i=1; i<req(); ++i ) {// For all paths in
2340 Node *ii = in(i);
2341 Node *new_in = MemNode::optimize_memory_chain(ii, at, NULL, phase);
2342 if (ii != new_in ) {
2343 set_req(i, new_in);
2344 progress = this;
2345 }
2346 }
2347 }
2348
2349 #ifdef _LP64
2350 // Push DecodeN/DecodeNKlass down through phi.
2351 // The rest of phi graph will transform by split EncodeP node though phis up.
2352 if ((UseCompressedOops || UseCompressedClassPointers) && can_reshape && progress == NULL) {
2353 bool may_push = true;
2354 bool has_decodeN = false;
2355 bool is_decodeN = false;
2356 for (uint i=1; i<req(); ++i) {// For all paths in
2357 Node *ii = in(i);
2358 if (ii->is_DecodeNarrowPtr() && ii->bottom_type() == bottom_type()) {
2359 // Do optimization if a non dead path exist.
2360 if (ii->in(1)->bottom_type() != Type::TOP) {
2361 has_decodeN = true;
2362 is_decodeN = ii->is_DecodeN();
2363 }
2364 } else if (!ii->is_Phi()) {
2365 may_push = false;
2366 }
2367 }
2368
2369 if (has_decodeN && may_push) {
2370 PhaseIterGVN *igvn = phase->is_IterGVN();
2371 // Make narrow type for new phi.
2372 const Type* narrow_t;
2373 if (is_decodeN) {
2374 narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr());
2375 } else {
2376 narrow_t = TypeNarrowKlass::make(this->bottom_type()->is_ptr());
2377 }
2378 PhiNode* new_phi = new PhiNode(r, narrow_t);
2379 uint orig_cnt = req();
2380 for (uint i=1; i<req(); ++i) {// For all paths in
2381 Node *ii = in(i);
2382 Node* new_ii = NULL;
2383 if (ii->is_DecodeNarrowPtr()) {
2384 assert(ii->bottom_type() == bottom_type(), "sanity");
2385 new_ii = ii->in(1);
2386 } else {
2387 assert(ii->is_Phi(), "sanity");
2388 if (ii->as_Phi() == this) {
2389 new_ii = new_phi;
2390 } else {
2391 if (is_decodeN) {
2392 new_ii = new EncodePNode(ii, narrow_t);
2393 } else {
2394 new_ii = new EncodePKlassNode(ii, narrow_t);
2395 }
2396 igvn->register_new_node_with_optimizer(new_ii);
2397 }
2398 }
2399 new_phi->set_req(i, new_ii);
2400 }
2401 igvn->register_new_node_with_optimizer(new_phi, this);
2402 if (is_decodeN) {
2403 progress = new DecodeNNode(new_phi, bottom_type());
2404 } else {
2405 progress = new DecodeNKlassNode(new_phi, bottom_type());
2406 }
2407 }
2408 }
2409 #endif
2410
2411 return progress; // Return any progress
2412 }
2413
2414 //------------------------------is_tripcount-----------------------------------
2415 bool PhiNode::is_tripcount() const {
2416 return (in(0) != NULL && in(0)->is_CountedLoop() &&
2417 in(0)->as_CountedLoop()->phi() == this);
2418 }
2419
2420 //------------------------------out_RegMask------------------------------------
2421 const RegMask &PhiNode::in_RegMask(uint i) const {
2422 return i ? out_RegMask() : RegMask::Empty;
2423 }
2424
2425 const RegMask &PhiNode::out_RegMask() const {
2426 uint ideal_reg = _type->ideal_reg();
2427 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
2428 if( ideal_reg == 0 ) return RegMask::Empty;
2429 assert(ideal_reg != Op_RegFlags, "flags register is not spillable");
2430 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
2431 }
2432
2433 #ifndef PRODUCT
2434 void PhiNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2435 // For a PhiNode, the set of related nodes includes all inputs till level 2,
2436 // and all outputs till level 1. In compact mode, inputs till level 1 are
2437 // collected.
2438 this->collect_nodes(in_rel, compact ? 1 : 2, false, false);
2439 this->collect_nodes(out_rel, -1, false, false);
2440 }
2441
2442 void PhiNode::dump_spec(outputStream *st) const {
2443 TypeNode::dump_spec(st);
2444 if (is_tripcount()) {
2445 st->print(" #tripcount");
2446 }
2447 }
2448 #endif
2449
2450
2451 //=============================================================================
2452 const Type* GotoNode::Value(PhaseGVN* phase) const {
2453 // If the input is reachable, then we are executed.
2454 // If the input is not reachable, then we are not executed.
2455 return phase->type(in(0));
2456 }
2457
2458 Node* GotoNode::Identity(PhaseGVN* phase) {
2459 return in(0); // Simple copy of incoming control
2460 }
2461
2462 const RegMask &GotoNode::out_RegMask() const {
2463 return RegMask::Empty;
2464 }
2465
2466 #ifndef PRODUCT
2467 //-----------------------------related-----------------------------------------
2468 // The related nodes of a GotoNode are all inputs at level 1, as well as the
2469 // outputs at level 1. This is regardless of compact mode.
2470 void GotoNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2471 this->collect_nodes(in_rel, 1, false, false);
2472 this->collect_nodes(out_rel, -1, false, false);
2473 }
2474 #endif
2475
2476
2477 //=============================================================================
2478 const RegMask &JumpNode::out_RegMask() const {
2479 return RegMask::Empty;
2480 }
2481
2482 #ifndef PRODUCT
2483 //-----------------------------related-----------------------------------------
2484 // The related nodes of a JumpNode are all inputs at level 1, as well as the
2485 // outputs at level 2 (to include actual jump targets beyond projection nodes).
2486 // This is regardless of compact mode.
2487 void JumpNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2488 this->collect_nodes(in_rel, 1, false, false);
2489 this->collect_nodes(out_rel, -2, false, false);
2490 }
2491 #endif
2492
2493 //=============================================================================
2494 const RegMask &JProjNode::out_RegMask() const {
2495 return RegMask::Empty;
2496 }
2497
2498 //=============================================================================
2499 const RegMask &CProjNode::out_RegMask() const {
2500 return RegMask::Empty;
2501 }
2502
2503
2504
2505 //=============================================================================
2506
2507 uint PCTableNode::hash() const { return Node::hash() + _size; }
2508 bool PCTableNode::cmp( const Node &n ) const
2509 { return _size == ((PCTableNode&)n)._size; }
2510
2511 const Type *PCTableNode::bottom_type() const {
2512 const Type** f = TypeTuple::fields(_size);
2513 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2514 return TypeTuple::make(_size, f);
2515 }
2516
2517 //------------------------------Value------------------------------------------
2518 // Compute the type of the PCTableNode. If reachable it is a tuple of
2519 // Control, otherwise the table targets are not reachable
2520 const Type* PCTableNode::Value(PhaseGVN* phase) const {
2521 if( phase->type(in(0)) == Type::CONTROL )
2522 return bottom_type();
2523 return Type::TOP; // All paths dead? Then so are we
2524 }
2525
2526 //------------------------------Ideal------------------------------------------
2527 // Return a node which is more "ideal" than the current node. Strip out
2528 // control copies
2529 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2530 return remove_dead_region(phase, can_reshape) ? this : NULL;
2531 }
2532
2533 //=============================================================================
2534 uint JumpProjNode::hash() const {
2535 return Node::hash() + _dest_bci;
2536 }
2537
2538 bool JumpProjNode::cmp( const Node &n ) const {
2539 return ProjNode::cmp(n) &&
2540 _dest_bci == ((JumpProjNode&)n)._dest_bci;
2541 }
2542
2543 #ifndef PRODUCT
2544 void JumpProjNode::dump_spec(outputStream *st) const {
2545 ProjNode::dump_spec(st);
2546 st->print("@bci %d ",_dest_bci);
2547 }
2548
2549 void JumpProjNode::dump_compact_spec(outputStream *st) const {
2550 ProjNode::dump_compact_spec(st);
2551 st->print("(%d)%d@%d", _switch_val, _proj_no, _dest_bci);
2552 }
2553
2554 void JumpProjNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2555 // The related nodes of a JumpProjNode are its inputs and outputs at level 1.
2556 this->collect_nodes(in_rel, 1, false, false);
2557 this->collect_nodes(out_rel, -1, false, false);
2558 }
2559 #endif
2560
2561 //=============================================================================
2562 //------------------------------Value------------------------------------------
2563 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot
2564 // have the default "fall_through_index" path.
2565 const Type* CatchNode::Value(PhaseGVN* phase) const {
2566 // Unreachable? Then so are all paths from here.
2567 if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
2568 // First assume all paths are reachable
2569 const Type** f = TypeTuple::fields(_size);
2570 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2571 // Identify cases that will always throw an exception
2572 // () rethrow call
2573 // () virtual or interface call with NULL receiver
2574 // () call is a check cast with incompatible arguments
2575 if( in(1)->is_Proj() ) {
2576 Node *i10 = in(1)->in(0);
2577 if( i10->is_Call() ) {
2578 CallNode *call = i10->as_Call();
2579 // Rethrows always throw exceptions, never return
2580 if (call->entry_point() == OptoRuntime::rethrow_stub()) {
2581 f[CatchProjNode::fall_through_index] = Type::TOP;
2582 } else if( call->req() > TypeFunc::Parms ) {
2583 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) );
2584 // Check for null receiver to virtual or interface calls
2585 if( call->is_CallDynamicJava() &&
2586 arg0->higher_equal(TypePtr::NULL_PTR) ) {
2587 f[CatchProjNode::fall_through_index] = Type::TOP;
2588 }
2589 } // End of if not a runtime stub
2590 } // End of if have call above me
2591 } // End of slot 1 is not a projection
2592 return TypeTuple::make(_size, f);
2593 }
2594
2595 //=============================================================================
2596 uint CatchProjNode::hash() const {
2597 return Node::hash() + _handler_bci;
2598 }
2599
2600
2601 bool CatchProjNode::cmp( const Node &n ) const {
2602 return ProjNode::cmp(n) &&
2603 _handler_bci == ((CatchProjNode&)n)._handler_bci;
2604 }
2605
2606
2607 //------------------------------Identity---------------------------------------
2608 // If only 1 target is possible, choose it if it is the main control
2609 Node* CatchProjNode::Identity(PhaseGVN* phase) {
2610 // If my value is control and no other value is, then treat as ID
2611 const TypeTuple *t = phase->type(in(0))->is_tuple();
2612 if (t->field_at(_con) != Type::CONTROL) return this;
2613 // If we remove the last CatchProj and elide the Catch/CatchProj, then we
2614 // also remove any exception table entry. Thus we must know the call
2615 // feeding the Catch will not really throw an exception. This is ok for
2616 // the main fall-thru control (happens when we know a call can never throw
2617 // an exception) or for "rethrow", because a further optimization will
2618 // yank the rethrow (happens when we inline a function that can throw an
2619 // exception and the caller has no handler). Not legal, e.g., for passing
2620 // a NULL receiver to a v-call, or passing bad types to a slow-check-cast.
2621 // These cases MUST throw an exception via the runtime system, so the VM
2622 // will be looking for a table entry.
2623 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode
2624 CallNode *call;
2625 if (_con != TypeFunc::Control && // Bail out if not the main control.
2626 !(proj->is_Proj() && // AND NOT a rethrow
2627 proj->in(0)->is_Call() &&
2628 (call = proj->in(0)->as_Call()) &&
2629 call->entry_point() == OptoRuntime::rethrow_stub()))
2630 return this;
2631
2632 // Search for any other path being control
2633 for (uint i = 0; i < t->cnt(); i++) {
2634 if (i != _con && t->field_at(i) == Type::CONTROL)
2635 return this;
2636 }
2637 // Only my path is possible; I am identity on control to the jump
2638 return in(0)->in(0);
2639 }
2640
2641
2642 #ifndef PRODUCT
2643 void CatchProjNode::dump_spec(outputStream *st) const {
2644 ProjNode::dump_spec(st);
2645 st->print("@bci %d ",_handler_bci);
2646 }
2647 #endif
2648
2649 //=============================================================================
2650 //------------------------------Identity---------------------------------------
2651 // Check for CreateEx being Identity.
2652 Node* CreateExNode::Identity(PhaseGVN* phase) {
2653 if( phase->type(in(1)) == Type::TOP ) return in(1);
2654 if( phase->type(in(0)) == Type::TOP ) return in(0);
2655 // We only come from CatchProj, unless the CatchProj goes away.
2656 // If the CatchProj is optimized away, then we just carry the
2657 // exception oop through.
2658
2659 // CheckCastPPNode::Ideal() for inline types reuses the exception
2660 // paths of a call to perform an allocation: we can see a Phi here.
2661 if (in(1)->is_Phi()) {
2662 return this;
2663 }
2664 CallNode *call = in(1)->in(0)->as_Call();
2665
2666 return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) )
2667 ? this
2668 : call->in(TypeFunc::Parms);
2669 }
2670
2671 //=============================================================================
2672 //------------------------------Value------------------------------------------
2673 // Check for being unreachable.
2674 const Type* NeverBranchNode::Value(PhaseGVN* phase) const {
2675 if (!in(0) || in(0)->is_top()) return Type::TOP;
2676 return bottom_type();
2677 }
2678
2679 //------------------------------Ideal------------------------------------------
2680 // Check for no longer being part of a loop
2681 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2682 if (can_reshape && !in(0)->is_Loop()) {
2683 // Dead code elimination can sometimes delete this projection so
2684 // if it's not there, there's nothing to do.
2685 Node* fallthru = proj_out_or_null(0);
2686 if (fallthru != NULL) {
2687 phase->is_IterGVN()->replace_node(fallthru, in(0));
2688 }
2689 return phase->C->top();
2690 }
2691 return NULL;
2692 }
2693
2694 #ifndef PRODUCT
2695 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const {
2696 st->print("%s", Name());
2697 }
2698 #endif