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
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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/loopnode.hpp"
38 #include "opto/machnode.hpp"
39 #include "opto/movenode.hpp"
40 #include "opto/narrowptrnode.hpp"
41 #include "opto/mulnode.hpp"
42 #include "opto/phaseX.hpp"
43 #include "opto/regmask.hpp"
44 #include "opto/runtime.hpp"
45 #include "opto/subnode.hpp"
46 #include "opto/vectornode.hpp"
47 #include "utilities/vmError.hpp"
48
49 // Portions of code courtesy of Clifford Click
50
51 // Optimization - Graph Style
52
53 //=============================================================================
54 //------------------------------Value------------------------------------------
55 // Compute the type of the RegionNode.
Value(PhaseGVN * phase) const56 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.
Identity(PhaseGVN * phase)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
merge_region(RegionNode * region,PhaseGVN * phase)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
has_phi() const130 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
has_unique_phi() const145 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
check_phi_clipping(PhiNode * phi,ConNode * & min,uint & min_idx,ConNode * & max,uint & max_idx,Node * & val,uint & val_idx)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 //
check_if_clipping(const RegionNode * region,IfNode * & bot_if,IfNode * & top_if)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"
check_convf2i_clipping(PhiNode * phi,uint idx,ConvF2INode * & convf2i,Node * min,Node * max)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
check_compare_clipping(bool less_than,IfNode * iff,ConNode * limit,Node * & input)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.
is_unreachable_region(const PhaseGVN * phase)319 bool RegionNode::is_unreachable_region(const PhaseGVN* phase) {
320 Node* top = phase->C->top();
321 assert(req() == 2 || (req() == 3 && in(1) != NULL && in(2) == top), "sanity check arguments");
322 if (_is_unreachable_region) {
323 // Return cached result from previous evaluation which should still be valid
324 assert(is_unreachable_from_root(phase), "walk the graph again and check if its indeed unreachable");
325 return true;
326 }
327
328 // First, cut the simple case of fallthrough region when NONE of
329 // region's phis references itself directly or through a data node.
330 if (is_possible_unsafe_loop(phase)) {
331 // If we have a possible unsafe loop, check if the region node is actually unreachable from root.
332 if (is_unreachable_from_root(phase)) {
333 _is_unreachable_region = true;
334 return true;
335 }
336 }
337 return false;
338 }
339
is_possible_unsafe_loop(const PhaseGVN * phase) const340 bool RegionNode::is_possible_unsafe_loop(const PhaseGVN* phase) const {
341 uint max = outcnt();
342 uint i;
343 for (i = 0; i < max; i++) {
344 Node* n = raw_out(i);
345 if (n != NULL && n->is_Phi()) {
346 PhiNode* phi = n->as_Phi();
347 assert(phi->in(0) == this, "sanity check phi");
348 if (phi->outcnt() == 0) {
349 continue; // Safe case - no loops
350 }
351 if (phi->outcnt() == 1) {
352 Node* u = phi->raw_out(0);
353 // Skip if only one use is an other Phi or Call or Uncommon trap.
354 // It is safe to consider this case as fallthrough.
355 if (u != NULL && (u->is_Phi() || u->is_CFG())) {
356 continue;
357 }
358 }
359 // Check when phi references itself directly or through an other node.
360 if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe) {
361 break; // Found possible unsafe data loop.
362 }
363 }
364 }
365 if (i >= max) {
366 return false; // An unsafe case was NOT found - don't need graph walk.
367 }
368 return true;
369 }
370
is_unreachable_from_root(const PhaseGVN * phase) const371 bool RegionNode::is_unreachable_from_root(const PhaseGVN* phase) const {
372 ResourceMark rm;
373 Node_List nstack;
374 VectorSet visited;
375
376 // Mark all control nodes reachable from root outputs
377 Node *n = (Node*)phase->C->root();
378 nstack.push(n);
379 visited.set(n->_idx);
380 while (nstack.size() != 0) {
381 n = nstack.pop();
382 uint max = n->outcnt();
383 for (uint i = 0; i < max; i++) {
384 Node* m = n->raw_out(i);
385 if (m != NULL && m->is_CFG()) {
386 if (m == this) {
387 return false; // We reached the Region node - it is not dead.
388 }
389 if (!visited.test_set(m->_idx))
390 nstack.push(m);
391 }
392 }
393 }
394 return true; // The Region node is unreachable - it is dead.
395 }
396
try_clean_mem_phi(PhaseGVN * phase)397 bool RegionNode::try_clean_mem_phi(PhaseGVN *phase) {
398 // Incremental inlining + PhaseStringOpts sometimes produce:
399 //
400 // cmpP with 1 top input
401 // |
402 // If
403 // / \
404 // IfFalse IfTrue /- Some Node
405 // \ / / /
406 // Region / /-MergeMem
407 // \---Phi
408 //
409 //
410 // It's expected by PhaseStringOpts that the Region goes away and is
411 // replaced by If's control input but because there's still a Phi,
412 // the Region stays in the graph. The top input from the cmpP is
413 // propagated forward and a subgraph that is useful goes away. The
414 // code below replaces the Phi with the MergeMem so that the Region
415 // is simplified.
416
417 PhiNode* phi = has_unique_phi();
418 if (phi && phi->type() == Type::MEMORY && req() == 3 && phi->is_diamond_phi(true)) {
419 MergeMemNode* m = NULL;
420 assert(phi->req() == 3, "same as region");
421 for (uint i = 1; i < 3; ++i) {
422 Node *mem = phi->in(i);
423 if (mem && mem->is_MergeMem() && in(i)->outcnt() == 1) {
424 // Nothing is control-dependent on path #i except the region itself.
425 m = mem->as_MergeMem();
426 uint j = 3 - i;
427 Node* other = phi->in(j);
428 if (other && other == m->base_memory()) {
429 // m is a successor memory to other, and is not pinned inside the diamond, so push it out.
430 // This will allow the diamond to collapse completely.
431 phase->is_IterGVN()->replace_node(phi, m);
432 return true;
433 }
434 }
435 }
436 }
437 return false;
438 }
439
440 //------------------------------Ideal------------------------------------------
441 // Return a node which is more "ideal" than the current node. Must preserve
442 // the CFG, but we can still strip out dead paths.
Ideal(PhaseGVN * phase,bool can_reshape)443 Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) {
444 if( !can_reshape && !in(0) ) return NULL; // Already degraded to a Copy
445 assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge");
446
447 // Check for RegionNode with no Phi users and both inputs come from either
448 // arm of the same IF. If found, then the control-flow split is useless.
449 bool has_phis = false;
450 if (can_reshape) { // Need DU info to check for Phi users
451 has_phis = (has_phi() != NULL); // Cache result
452 if (has_phis && try_clean_mem_phi(phase)) {
453 has_phis = false;
454 }
455
456 if (!has_phis) { // No Phi users? Nothing merging?
457 for (uint i = 1; i < req()-1; i++) {
458 Node *if1 = in(i);
459 if( !if1 ) continue;
460 Node *iff = if1->in(0);
461 if( !iff || !iff->is_If() ) continue;
462 for( uint j=i+1; j<req(); j++ ) {
463 if( in(j) && in(j)->in(0) == iff &&
464 if1->Opcode() != in(j)->Opcode() ) {
465 // Add the IF Projections to the worklist. They (and the IF itself)
466 // will be eliminated if dead.
467 phase->is_IterGVN()->add_users_to_worklist(iff);
468 set_req(i, iff->in(0));// Skip around the useless IF diamond
469 set_req(j, NULL);
470 return this; // Record progress
471 }
472 }
473 }
474 }
475 }
476
477 // Remove TOP or NULL input paths. If only 1 input path remains, this Region
478 // degrades to a copy.
479 bool add_to_worklist = false;
480 bool modified = false;
481 int cnt = 0; // Count of values merging
482 DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count
483 int del_it = 0; // The last input path we delete
484 // For all inputs...
485 for( uint i=1; i<req(); ++i ){// For all paths in
486 Node *n = in(i); // Get the input
487 if( n != NULL ) {
488 // Remove useless control copy inputs
489 if( n->is_Region() && n->as_Region()->is_copy() ) {
490 set_req(i, n->nonnull_req());
491 modified = true;
492 i--;
493 continue;
494 }
495 if( n->is_Proj() ) { // Remove useless rethrows
496 Node *call = n->in(0);
497 if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) {
498 set_req(i, call->in(0));
499 modified = true;
500 i--;
501 continue;
502 }
503 }
504 if( phase->type(n) == Type::TOP ) {
505 set_req(i, NULL); // Ignore TOP inputs
506 modified = true;
507 i--;
508 continue;
509 }
510 cnt++; // One more value merging
511
512 } else if (can_reshape) { // Else found dead path with DU info
513 PhaseIterGVN *igvn = phase->is_IterGVN();
514 del_req(i); // Yank path from self
515 del_it = i;
516 uint max = outcnt();
517 DUIterator j;
518 bool progress = true;
519 while(progress) { // Need to establish property over all users
520 progress = false;
521 for (j = outs(); has_out(j); j++) {
522 Node *n = out(j);
523 if( n->req() != req() && n->is_Phi() ) {
524 assert( n->in(0) == this, "" );
525 igvn->hash_delete(n); // Yank from hash before hacking edges
526 n->set_req_X(i,NULL,igvn);// Correct DU info
527 n->del_req(i); // Yank path from Phis
528 if( max != outcnt() ) {
529 progress = true;
530 j = refresh_out_pos(j);
531 max = outcnt();
532 }
533 }
534 }
535 }
536 add_to_worklist = true;
537 i--;
538 }
539 }
540
541 if (can_reshape && cnt == 1) {
542 // Is it dead loop?
543 // If it is LoopNopde it had 2 (+1 itself) inputs and
544 // one of them was cut. The loop is dead if it was EntryContol.
545 // Loop node may have only one input because entry path
546 // is removed in PhaseIdealLoop::Dominators().
547 assert(!this->is_Loop() || cnt_orig <= 3, "Loop node should have 3 or less inputs");
548 if ((this->is_Loop() && (del_it == LoopNode::EntryControl ||
549 (del_it == 0 && is_unreachable_region(phase)))) ||
550 (!this->is_Loop() && has_phis && is_unreachable_region(phase))) {
551 // Yes, the region will be removed during the next step below.
552 // Cut the backedge input and remove phis since no data paths left.
553 // We don't cut outputs to other nodes here since we need to put them
554 // on the worklist.
555 PhaseIterGVN *igvn = phase->is_IterGVN();
556 if (in(1)->outcnt() == 1) {
557 igvn->_worklist.push(in(1));
558 }
559 del_req(1);
560 cnt = 0;
561 assert( req() == 1, "no more inputs expected" );
562 uint max = outcnt();
563 bool progress = true;
564 Node *top = phase->C->top();
565 DUIterator j;
566 while(progress) {
567 progress = false;
568 for (j = outs(); has_out(j); j++) {
569 Node *n = out(j);
570 if( n->is_Phi() ) {
571 assert(n->in(0) == this, "");
572 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
573 // Break dead loop data path.
574 // Eagerly replace phis with top to avoid regionless phis.
575 igvn->replace_node(n, top);
576 if( max != outcnt() ) {
577 progress = true;
578 j = refresh_out_pos(j);
579 max = outcnt();
580 }
581 }
582 }
583 }
584 add_to_worklist = true;
585 }
586 }
587 if (add_to_worklist) {
588 phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis
589 }
590
591 if( cnt <= 1 ) { // Only 1 path in?
592 set_req(0, NULL); // Null control input for region copy
593 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is.
594 // No inputs or all inputs are NULL.
595 return NULL;
596 } else if (can_reshape) { // Optimization phase - remove the node
597 PhaseIterGVN *igvn = phase->is_IterGVN();
598 // Strip mined (inner) loop is going away, remove outer loop.
599 if (is_CountedLoop() &&
600 as_Loop()->is_strip_mined()) {
601 Node* outer_sfpt = as_CountedLoop()->outer_safepoint();
602 Node* outer_out = as_CountedLoop()->outer_loop_exit();
603 if (outer_sfpt != NULL && outer_out != NULL) {
604 Node* in = outer_sfpt->in(0);
605 igvn->replace_node(outer_out, in);
606 LoopNode* outer = as_CountedLoop()->outer_loop();
607 igvn->replace_input_of(outer, LoopNode::LoopBackControl, igvn->C->top());
608 }
609 }
610 Node *parent_ctrl;
611 if( cnt == 0 ) {
612 assert( req() == 1, "no inputs expected" );
613 // During IGVN phase such region will be subsumed by TOP node
614 // so region's phis will have TOP as control node.
615 // Kill phis here to avoid it.
616 // Also set other user's input to top.
617 parent_ctrl = phase->C->top();
618 } else {
619 // The fallthrough case since we already checked dead loops above.
620 parent_ctrl = in(1);
621 assert(parent_ctrl != NULL, "Region is a copy of some non-null control");
622 assert(parent_ctrl != this, "Close dead loop");
623 }
624 if (!add_to_worklist)
625 igvn->add_users_to_worklist(this); // Check for further allowed opts
626 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
627 Node* n = last_out(i);
628 igvn->hash_delete(n); // Remove from worklist before modifying edges
629 if( n->is_Phi() ) { // Collapse all Phis
630 // Eagerly replace phis to avoid regionless phis.
631 Node* in;
632 if( cnt == 0 ) {
633 assert( n->req() == 1, "No data inputs expected" );
634 in = parent_ctrl; // replaced by top
635 } else {
636 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
637 in = n->in(1); // replaced by unique input
638 if( n->as_Phi()->is_unsafe_data_reference(in) )
639 in = phase->C->top(); // replaced by top
640 }
641 igvn->replace_node(n, in);
642 }
643 else if( n->is_Region() ) { // Update all incoming edges
644 assert(n != this, "Must be removed from DefUse edges");
645 uint uses_found = 0;
646 for( uint k=1; k < n->req(); k++ ) {
647 if( n->in(k) == this ) {
648 n->set_req(k, parent_ctrl);
649 uses_found++;
650 }
651 }
652 if( uses_found > 1 ) { // (--i) done at the end of the loop.
653 i -= (uses_found - 1);
654 }
655 }
656 else {
657 assert(n->in(0) == this, "Expect RegionNode to be control parent");
658 n->set_req(0, parent_ctrl);
659 }
660 #ifdef ASSERT
661 for( uint k=0; k < n->req(); k++ ) {
662 assert(n->in(k) != this, "All uses of RegionNode should be gone");
663 }
664 #endif
665 }
666 // Remove the RegionNode itself from DefUse info
667 igvn->remove_dead_node(this);
668 return NULL;
669 }
670 return this; // Record progress
671 }
672
673
674 // If a Region flows into a Region, merge into one big happy merge.
675 if (can_reshape) {
676 Node *m = merge_region(this, phase);
677 if (m != NULL) return m;
678 }
679
680 // Check if this region is the root of a clipping idiom on floats
681 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
682 // Check that only one use is a Phi and that it simplifies to two constants +
683 PhiNode* phi = has_unique_phi();
684 if (phi != NULL) { // One Phi user
685 // Check inputs to the Phi
686 ConNode *min;
687 ConNode *max;
688 Node *val;
689 uint min_idx;
690 uint max_idx;
691 uint val_idx;
692 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) {
693 IfNode *top_if;
694 IfNode *bot_if;
695 if( check_if_clipping( this, bot_if, top_if ) ) {
696 // Control pattern checks, now verify compares
697 Node *top_in = NULL; // value being compared against
698 Node *bot_in = NULL;
699 if( check_compare_clipping( true, bot_if, min, bot_in ) &&
700 check_compare_clipping( false, top_if, max, top_in ) ) {
701 if( bot_in == top_in ) {
702 PhaseIterGVN *gvn = phase->is_IterGVN();
703 assert( gvn != NULL, "Only had DefUse info in IterGVN");
704 // Only remaining check is that bot_in == top_in == (Phi's val + mods)
705
706 // Check for the ConvF2INode
707 ConvF2INode *convf2i;
708 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
709 convf2i->in(1) == bot_in ) {
710 // Matched pattern, including LShiftI; RShiftI, replace with integer compares
711 // max test
712 Node *cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, min ));
713 Node *boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::lt ));
714 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt ));
715 Node *if_min= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
716 Node *ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
717 // min test
718 cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, max ));
719 boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::gt ));
720 iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
721 Node *if_max= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
722 ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
723 // update input edges to region node
724 set_req_X( min_idx, if_min, gvn );
725 set_req_X( max_idx, if_max, gvn );
726 set_req_X( val_idx, ifF, gvn );
727 // remove unnecessary 'LShiftI; RShiftI' idiom
728 gvn->hash_delete(phi);
729 phi->set_req_X( val_idx, convf2i, gvn );
730 gvn->hash_find_insert(phi);
731 // Return transformed region node
732 return this;
733 }
734 }
735 }
736 }
737 }
738 }
739 }
740
741 if (can_reshape) {
742 modified |= optimize_trichotomy(phase->is_IterGVN());
743 }
744
745 return modified ? this : NULL;
746 }
747
748 //------------------------------optimize_trichotomy--------------------------
749 // Optimize nested comparisons of the following kind:
750 //
751 // int compare(int a, int b) {
752 // return (a < b) ? -1 : (a == b) ? 0 : 1;
753 // }
754 //
755 // Shape 1:
756 // if (compare(a, b) == 1) { ... } -> if (a > b) { ... }
757 //
758 // Shape 2:
759 // if (compare(a, b) == 0) { ... } -> if (a == b) { ... }
760 //
761 // Above code leads to the following IR shapes where both Ifs compare the
762 // same value and two out of three region inputs idx1 and idx2 map to
763 // the same value and control flow.
764 //
765 // (1) If (2) If
766 // / \ / \
767 // Proj Proj Proj Proj
768 // | \ | \
769 // | If | If If
770 // | / \ | / \ / \
771 // | Proj Proj | Proj Proj ==> Proj Proj
772 // | / / \ | / | /
773 // Region / \ | / | /
774 // \ / \ | / | /
775 // Region Region Region
776 //
777 // The method returns true if 'this' is modified and false otherwise.
optimize_trichotomy(PhaseIterGVN * igvn)778 bool RegionNode::optimize_trichotomy(PhaseIterGVN* igvn) {
779 int idx1 = 1, idx2 = 2;
780 Node* region = NULL;
781 if (req() == 3 && in(1) != NULL && in(2) != NULL) {
782 // Shape 1: Check if one of the inputs is a region that merges two control
783 // inputs and has no other users (especially no Phi users).
784 region = in(1)->isa_Region() ? in(1) : in(2)->isa_Region();
785 if (region == NULL || region->outcnt() != 2 || region->req() != 3) {
786 return false; // No suitable region input found
787 }
788 } else if (req() == 4) {
789 // Shape 2: Check if two control inputs map to the same value of the unique phi
790 // user and treat these as if they would come from another region (shape (1)).
791 PhiNode* phi = has_unique_phi();
792 if (phi == NULL) {
793 return false; // No unique phi user
794 }
795 if (phi->in(idx1) != phi->in(idx2)) {
796 idx2 = 3;
797 if (phi->in(idx1) != phi->in(idx2)) {
798 idx1 = 2;
799 if (phi->in(idx1) != phi->in(idx2)) {
800 return false; // No equal phi inputs found
801 }
802 }
803 }
804 assert(phi->in(idx1) == phi->in(idx2), "must be"); // Region is merging same value
805 region = this;
806 }
807 if (region == NULL || region->in(idx1) == NULL || region->in(idx2) == NULL) {
808 return false; // Region does not merge two control inputs
809 }
810 // At this point we know that region->in(idx1) and region->(idx2) map to the same
811 // value and control flow. Now search for ifs that feed into these region inputs.
812 ProjNode* proj1 = region->in(idx1)->isa_Proj();
813 ProjNode* proj2 = region->in(idx2)->isa_Proj();
814 if (proj1 == NULL || proj1->outcnt() != 1 ||
815 proj2 == NULL || proj2->outcnt() != 1) {
816 return false; // No projection inputs with region as unique user found
817 }
818 assert(proj1 != proj2, "should be different projections");
819 IfNode* iff1 = proj1->in(0)->isa_If();
820 IfNode* iff2 = proj2->in(0)->isa_If();
821 if (iff1 == NULL || iff1->outcnt() != 2 ||
822 iff2 == NULL || iff2->outcnt() != 2) {
823 return false; // No ifs found
824 }
825 if (iff1 == iff2) {
826 igvn->add_users_to_worklist(iff1); // Make sure dead if is eliminated
827 igvn->replace_input_of(region, idx1, iff1->in(0));
828 igvn->replace_input_of(region, idx2, igvn->C->top());
829 return (region == this); // Remove useless if (both projections map to the same control/value)
830 }
831 BoolNode* bol1 = iff1->in(1)->isa_Bool();
832 BoolNode* bol2 = iff2->in(1)->isa_Bool();
833 if (bol1 == NULL || bol2 == NULL) {
834 return false; // No bool inputs found
835 }
836 Node* cmp1 = bol1->in(1);
837 Node* cmp2 = bol2->in(1);
838 bool commute = false;
839 if (!cmp1->is_Cmp() || !cmp2->is_Cmp()) {
840 return false; // No comparison
841 } else if (cmp1->Opcode() == Op_CmpF || cmp1->Opcode() == Op_CmpD ||
842 cmp2->Opcode() == Op_CmpF || cmp2->Opcode() == Op_CmpD ||
843 cmp1->Opcode() == Op_CmpP || cmp1->Opcode() == Op_CmpN ||
844 cmp2->Opcode() == Op_CmpP || cmp2->Opcode() == Op_CmpN ||
845 cmp1->is_SubTypeCheck() || cmp2->is_SubTypeCheck()) {
846 // Floats and pointers don't exactly obey trichotomy. To be on the safe side, don't transform their tests.
847 // SubTypeCheck is not commutative
848 return false;
849 } else if (cmp1 != cmp2) {
850 if (cmp1->in(1) == cmp2->in(2) &&
851 cmp1->in(2) == cmp2->in(1)) {
852 commute = true; // Same but swapped inputs, commute the test
853 } else {
854 return false; // Ifs are not comparing the same values
855 }
856 }
857 proj1 = proj1->other_if_proj();
858 proj2 = proj2->other_if_proj();
859 if (!((proj1->unique_ctrl_out() == iff2 &&
860 proj2->unique_ctrl_out() == this) ||
861 (proj2->unique_ctrl_out() == iff1 &&
862 proj1->unique_ctrl_out() == this))) {
863 return false; // Ifs are not connected through other projs
864 }
865 // Found 'iff -> proj -> iff -> proj -> this' shape where all other projs are merged
866 // through 'region' and map to the same value. Merge the boolean tests and replace
867 // the ifs by a single comparison.
868 BoolTest test1 = (proj1->_con == 1) ? bol1->_test : bol1->_test.negate();
869 BoolTest test2 = (proj2->_con == 1) ? bol2->_test : bol2->_test.negate();
870 test1 = commute ? test1.commute() : test1;
871 // After possibly commuting test1, if we can merge test1 & test2, then proj2/iff2/bol2 are the nodes to refine.
872 BoolTest::mask res = test1.merge(test2);
873 if (res == BoolTest::illegal) {
874 return false; // Unable to merge tests
875 }
876 // Adjust iff1 to always pass (only iff2 will remain)
877 igvn->replace_input_of(iff1, 1, igvn->intcon(proj1->_con));
878 if (res == BoolTest::never) {
879 // Merged test is always false, adjust iff2 to always fail
880 igvn->replace_input_of(iff2, 1, igvn->intcon(1 - proj2->_con));
881 } else {
882 // Replace bool input of iff2 with merged test
883 BoolNode* new_bol = new BoolNode(bol2->in(1), res);
884 igvn->replace_input_of(iff2, 1, igvn->transform((proj2->_con == 1) ? new_bol : new_bol->negate(igvn)));
885 }
886 return false;
887 }
888
out_RegMask() const889 const RegMask &RegionNode::out_RegMask() const {
890 return RegMask::Empty;
891 }
892
893 // Find the one non-null required input. RegionNode only
nonnull_req() const894 Node *Node::nonnull_req() const {
895 assert( is_Region(), "" );
896 for( uint i = 1; i < _cnt; i++ )
897 if( in(i) )
898 return in(i);
899 ShouldNotReachHere();
900 return NULL;
901 }
902
903
904 //=============================================================================
905 // note that these functions assume that the _adr_type field is flattened
hash() const906 uint PhiNode::hash() const {
907 const Type* at = _adr_type;
908 return TypeNode::hash() + (at ? at->hash() : 0);
909 }
cmp(const Node & n) const910 bool PhiNode::cmp( const Node &n ) const {
911 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
912 }
913 static inline
flatten_phi_adr_type(const TypePtr * at)914 const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
915 if (at == NULL || at == TypePtr::BOTTOM) return at;
916 return Compile::current()->alias_type(at)->adr_type();
917 }
918
919 //----------------------------make---------------------------------------------
920 // create a new phi with edges matching r and set (initially) to x
make(Node * r,Node * x,const Type * t,const TypePtr * at)921 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
922 uint preds = r->req(); // Number of predecessor paths
923 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at");
924 PhiNode* p = new PhiNode(r, t, at);
925 for (uint j = 1; j < preds; j++) {
926 // Fill in all inputs, except those which the region does not yet have
927 if (r->in(j) != NULL)
928 p->init_req(j, x);
929 }
930 return p;
931 }
make(Node * r,Node * x)932 PhiNode* PhiNode::make(Node* r, Node* x) {
933 const Type* t = x->bottom_type();
934 const TypePtr* at = NULL;
935 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
936 return make(r, x, t, at);
937 }
make_blank(Node * r,Node * x)938 PhiNode* PhiNode::make_blank(Node* r, Node* x) {
939 const Type* t = x->bottom_type();
940 const TypePtr* at = NULL;
941 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
942 return new PhiNode(r, t, at);
943 }
944
945
946 //------------------------slice_memory-----------------------------------------
947 // create a new phi with narrowed memory type
slice_memory(const TypePtr * adr_type) const948 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
949 PhiNode* mem = (PhiNode*) clone();
950 *(const TypePtr**)&mem->_adr_type = adr_type;
951 // convert self-loops, or else we get a bad graph
952 for (uint i = 1; i < req(); i++) {
953 if ((const Node*)in(i) == this) mem->set_req(i, mem);
954 }
955 mem->verify_adr_type();
956 return mem;
957 }
958
959 //------------------------split_out_instance-----------------------------------
960 // Split out an instance type from a bottom phi.
split_out_instance(const TypePtr * at,PhaseIterGVN * igvn) const961 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const {
962 const TypeOopPtr *t_oop = at->isa_oopptr();
963 assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr");
964 const TypePtr *t = adr_type();
965 assert(type() == Type::MEMORY &&
966 (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
967 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
968 t->is_oopptr()->cast_to_exactness(true)
969 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
970 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop),
971 "bottom or raw memory required");
972
973 // Check if an appropriate node already exists.
974 Node *region = in(0);
975 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) {
976 Node* use = region->fast_out(k);
977 if( use->is_Phi()) {
978 PhiNode *phi2 = use->as_Phi();
979 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) {
980 return phi2;
981 }
982 }
983 }
984 Compile *C = igvn->C;
985 Arena *a = Thread::current()->resource_area();
986 Node_Array node_map = new Node_Array(a);
987 Node_Stack stack(a, C->live_nodes() >> 4);
988 PhiNode *nphi = slice_memory(at);
989 igvn->register_new_node_with_optimizer( nphi );
990 node_map.map(_idx, nphi);
991 stack.push((Node *)this, 1);
992 while(!stack.is_empty()) {
993 PhiNode *ophi = stack.node()->as_Phi();
994 uint i = stack.index();
995 assert(i >= 1, "not control edge");
996 stack.pop();
997 nphi = node_map[ophi->_idx]->as_Phi();
998 for (; i < ophi->req(); i++) {
999 Node *in = ophi->in(i);
1000 if (in == NULL || igvn->type(in) == Type::TOP)
1001 continue;
1002 Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, NULL, igvn);
1003 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL;
1004 if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) {
1005 opt = node_map[optphi->_idx];
1006 if (opt == NULL) {
1007 stack.push(ophi, i);
1008 nphi = optphi->slice_memory(at);
1009 igvn->register_new_node_with_optimizer( nphi );
1010 node_map.map(optphi->_idx, nphi);
1011 ophi = optphi;
1012 i = 0; // will get incremented at top of loop
1013 continue;
1014 }
1015 }
1016 nphi->set_req(i, opt);
1017 }
1018 }
1019 return nphi;
1020 }
1021
1022 //------------------------verify_adr_type--------------------------------------
1023 #ifdef ASSERT
verify_adr_type(VectorSet & visited,const TypePtr * at) const1024 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
1025 if (visited.test_set(_idx)) return; //already visited
1026
1027 // recheck constructor invariants:
1028 verify_adr_type(false);
1029
1030 // recheck local phi/phi consistency:
1031 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
1032 "adr_type must be consistent across phi nest");
1033
1034 // walk around
1035 for (uint i = 1; i < req(); i++) {
1036 Node* n = in(i);
1037 if (n == NULL) continue;
1038 const Node* np = in(i);
1039 if (np->is_Phi()) {
1040 np->as_Phi()->verify_adr_type(visited, at);
1041 } else if (n->bottom_type() == Type::TOP
1042 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
1043 // ignore top inputs
1044 } else {
1045 const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
1046 // recheck phi/non-phi consistency at leaves:
1047 assert((nat != NULL) == (at != NULL), "");
1048 assert(nat == at || nat == TypePtr::BOTTOM,
1049 "adr_type must be consistent at leaves of phi nest");
1050 }
1051 }
1052 }
1053
1054 // Verify a whole nest of phis rooted at this one.
verify_adr_type(bool recursive) const1055 void PhiNode::verify_adr_type(bool recursive) const {
1056 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
1057 if (Node::in_dump()) return; // muzzle asserts when printing
1058
1059 assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only");
1060
1061 if (!VerifyAliases) return; // verify thoroughly only if requested
1062
1063 assert(_adr_type == flatten_phi_adr_type(_adr_type),
1064 "Phi::adr_type must be pre-normalized");
1065
1066 if (recursive) {
1067 VectorSet visited;
1068 verify_adr_type(visited, _adr_type);
1069 }
1070 }
1071 #endif
1072
1073
1074 //------------------------------Value------------------------------------------
1075 // Compute the type of the PhiNode
Value(PhaseGVN * phase) const1076 const Type* PhiNode::Value(PhaseGVN* phase) const {
1077 Node *r = in(0); // RegionNode
1078 if( !r ) // Copy or dead
1079 return in(1) ? phase->type(in(1)) : Type::TOP;
1080
1081 // Note: During parsing, phis are often transformed before their regions.
1082 // This means we have to use type_or_null to defend against untyped regions.
1083 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1084 return Type::TOP;
1085
1086 // Check for trip-counted loop. If so, be smarter.
1087 BaseCountedLoopNode* l = r->is_BaseCountedLoop() ? r->as_BaseCountedLoop() : NULL;
1088 if (l && ((const Node*)l->phi() == this)) { // Trip counted loop!
1089 // protect against init_trip() or limit() returning NULL
1090 if (l->can_be_counted_loop(phase)) {
1091 const Node* init = l->init_trip();
1092 const Node* limit = l->limit();
1093 const Node* stride = l->stride();
1094 if (init != NULL && limit != NULL && stride != NULL) {
1095 const TypeInteger* lo = phase->type(init)->isa_integer(l->bt());
1096 const TypeInteger* hi = phase->type(limit)->isa_integer(l->bt());
1097 const TypeInteger* stride_t = phase->type(stride)->isa_integer(l->bt());
1098 if (lo != NULL && hi != NULL && stride_t != NULL) { // Dying loops might have TOP here
1099 assert(stride_t->hi_as_long() >= stride_t->lo_as_long(), "bad stride type");
1100 BoolTest::mask bt = l->loopexit()->test_trip();
1101 // If the loop exit condition is "not equal", the condition
1102 // would not trigger if init > limit (if stride > 0) or if
1103 // init < limit if (stride > 0) so we can't deduce bounds
1104 // for the iv from the exit condition.
1105 if (bt != BoolTest::ne) {
1106 if (stride_t->hi_as_long() < 0) { // Down-counter loop
1107 swap(lo, hi);
1108 return TypeInteger::make(MIN2(lo->lo_as_long(), hi->lo_as_long()), hi->hi_as_long(), 3, l->bt())->filter_speculative(_type);
1109 } else if (stride_t->lo_as_long() >= 0) {
1110 return TypeInteger::make(lo->lo_as_long(), MAX2(lo->hi_as_long(), hi->hi_as_long()), 3, l->bt())->filter_speculative(_type);
1111 }
1112 }
1113 }
1114 }
1115 } else if (l->in(LoopNode::LoopBackControl) != NULL &&
1116 in(LoopNode::EntryControl) != NULL &&
1117 phase->type(l->in(LoopNode::LoopBackControl)) == Type::TOP) {
1118 // During CCP, if we saturate the type of a counted loop's Phi
1119 // before the special code for counted loop above has a chance
1120 // to run (that is as long as the type of the backedge's control
1121 // is top), we might end up with non monotonic types
1122 return phase->type(in(LoopNode::EntryControl))->filter_speculative(_type);
1123 }
1124 }
1125
1126 // Until we have harmony between classes and interfaces in the type
1127 // lattice, we must tread carefully around phis which implicitly
1128 // convert the one to the other.
1129 const TypePtr* ttp = _type->make_ptr();
1130 const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL;
1131 const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_klassptr() : NULL;
1132 bool is_intf = false;
1133 if (ttip != NULL) {
1134 ciKlass* k = ttip->klass();
1135 if (k->is_loaded() && k->is_interface())
1136 is_intf = true;
1137 }
1138 if (ttkp != NULL) {
1139 ciKlass* k = ttkp->klass();
1140 if (k->is_loaded() && k->is_interface())
1141 is_intf = true;
1142 }
1143
1144 // Default case: merge all inputs
1145 const Type *t = Type::TOP; // Merged type starting value
1146 for (uint i = 1; i < req(); ++i) {// For all paths in
1147 // Reachable control path?
1148 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
1149 const Type* ti = phase->type(in(i));
1150 // We assume that each input of an interface-valued Phi is a true
1151 // subtype of that interface. This might not be true of the meet
1152 // of all the input types. The lattice is not distributive in
1153 // such cases. Ward off asserts in type.cpp by refusing to do
1154 // meets between interfaces and proper classes.
1155 const TypePtr* tip = ti->make_ptr();
1156 const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL;
1157 if (tiip) {
1158 bool ti_is_intf = false;
1159 ciKlass* k = tiip->klass();
1160 if (k->is_loaded() && k->is_interface())
1161 ti_is_intf = true;
1162 if (is_intf != ti_is_intf)
1163 { t = _type; break; }
1164 }
1165 t = t->meet_speculative(ti);
1166 }
1167 }
1168
1169 // The worst-case type (from ciTypeFlow) should be consistent with "t".
1170 // That is, we expect that "t->higher_equal(_type)" holds true.
1171 // There are various exceptions:
1172 // - Inputs which are phis might in fact be widened unnecessarily.
1173 // For example, an input might be a widened int while the phi is a short.
1174 // - Inputs might be BotPtrs but this phi is dependent on a null check,
1175 // and postCCP has removed the cast which encodes the result of the check.
1176 // - The type of this phi is an interface, and the inputs are classes.
1177 // - Value calls on inputs might produce fuzzy results.
1178 // (Occurrences of this case suggest improvements to Value methods.)
1179 //
1180 // It is not possible to see Type::BOTTOM values as phi inputs,
1181 // because the ciTypeFlow pre-pass produces verifier-quality types.
1182 const Type* ft = t->filter_speculative(_type); // Worst case type
1183
1184 #ifdef ASSERT
1185 // The following logic has been moved into TypeOopPtr::filter.
1186 const Type* jt = t->join_speculative(_type);
1187 if (jt->empty()) { // Emptied out???
1188
1189 // Check for evil case of 't' being a class and '_type' expecting an
1190 // interface. This can happen because the bytecodes do not contain
1191 // enough type info to distinguish a Java-level interface variable
1192 // from a Java-level object variable. If we meet 2 classes which
1193 // both implement interface I, but their meet is at 'j/l/O' which
1194 // doesn't implement I, we have no way to tell if the result should
1195 // be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows
1196 // into a Phi which "knows" it's an Interface type we'll have to
1197 // uplift the type.
1198 if (!t->empty() && ttip && ttip->is_loaded() && ttip->klass()->is_interface()) {
1199 assert(ft == _type, ""); // Uplift to interface
1200 } else if (!t->empty() && ttkp && ttkp->is_loaded() && ttkp->klass()->is_interface()) {
1201 assert(ft == _type, ""); // Uplift to interface
1202 } else {
1203 // We also have to handle 'evil cases' of interface- vs. class-arrays
1204 Type::get_arrays_base_elements(jt, _type, NULL, &ttip);
1205 if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
1206 assert(ft == _type, ""); // Uplift to array of interface
1207 } else {
1208 // Otherwise it's something stupid like non-overlapping int ranges
1209 // found on dying counted loops.
1210 assert(ft == Type::TOP, ""); // Canonical empty value
1211 }
1212 }
1213 }
1214
1215 else {
1216
1217 // If we have an interface-typed Phi and we narrow to a class type, the join
1218 // should report back the class. However, if we have a J/L/Object
1219 // class-typed Phi and an interface flows in, it's possible that the meet &
1220 // join report an interface back out. This isn't possible but happens
1221 // because the type system doesn't interact well with interfaces.
1222 const TypePtr *jtp = jt->make_ptr();
1223 const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL;
1224 const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_klassptr() : NULL;
1225 if( jtip && ttip ) {
1226 if( jtip->is_loaded() && jtip->klass()->is_interface() &&
1227 ttip->is_loaded() && !ttip->klass()->is_interface() ) {
1228 assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) ||
1229 ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), "");
1230 jt = ft;
1231 }
1232 }
1233 if( jtkp && ttkp ) {
1234 if( jtkp->is_loaded() && jtkp->klass()->is_interface() &&
1235 !jtkp->klass_is_exact() && // Keep exact interface klass (6894807)
1236 ttkp->is_loaded() && !ttkp->klass()->is_interface() ) {
1237 assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) ||
1238 ft->isa_narrowklass() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), "");
1239 jt = ft;
1240 }
1241 }
1242 if (jt != ft && jt->base() == ft->base()) {
1243 if (jt->isa_int() &&
1244 jt->is_int()->_lo == ft->is_int()->_lo &&
1245 jt->is_int()->_hi == ft->is_int()->_hi)
1246 jt = ft;
1247 if (jt->isa_long() &&
1248 jt->is_long()->_lo == ft->is_long()->_lo &&
1249 jt->is_long()->_hi == ft->is_long()->_hi)
1250 jt = ft;
1251 }
1252 if (jt != ft) {
1253 tty->print("merge type: "); t->dump(); tty->cr();
1254 tty->print("kill type: "); _type->dump(); tty->cr();
1255 tty->print("join type: "); jt->dump(); tty->cr();
1256 tty->print("filter type: "); ft->dump(); tty->cr();
1257 }
1258 assert(jt == ft, "");
1259 }
1260 #endif //ASSERT
1261
1262 // Deal with conversion problems found in data loops.
1263 ft = phase->saturate(ft, phase->type_or_null(this), _type);
1264
1265 return ft;
1266 }
1267
1268
1269 //------------------------------is_diamond_phi---------------------------------
1270 // Does this Phi represent a simple well-shaped diamond merge? Return the
1271 // index of the true path or 0 otherwise.
1272 // If check_control_only is true, do not inspect the If node at the
1273 // top, and return -1 (not an edge number) on success.
is_diamond_phi(bool check_control_only) const1274 int PhiNode::is_diamond_phi(bool check_control_only) const {
1275 // Check for a 2-path merge
1276 Node *region = in(0);
1277 if( !region ) return 0;
1278 if( region->req() != 3 ) return 0;
1279 if( req() != 3 ) return 0;
1280 // Check that both paths come from the same If
1281 Node *ifp1 = region->in(1);
1282 Node *ifp2 = region->in(2);
1283 if( !ifp1 || !ifp2 ) return 0;
1284 Node *iff = ifp1->in(0);
1285 if( !iff || !iff->is_If() ) return 0;
1286 if( iff != ifp2->in(0) ) return 0;
1287 if (check_control_only) return -1;
1288 // Check for a proper bool/cmp
1289 const Node *b = iff->in(1);
1290 if( !b->is_Bool() ) return 0;
1291 const Node *cmp = b->in(1);
1292 if( !cmp->is_Cmp() ) return 0;
1293
1294 // Check for branching opposite expected
1295 if( ifp2->Opcode() == Op_IfTrue ) {
1296 assert( ifp1->Opcode() == Op_IfFalse, "" );
1297 return 2;
1298 } else {
1299 assert( ifp1->Opcode() == Op_IfTrue, "" );
1300 return 1;
1301 }
1302 }
1303
1304 //----------------------------check_cmove_id-----------------------------------
1305 // Check for CMove'ing a constant after comparing against the constant.
1306 // Happens all the time now, since if we compare equality vs a constant in
1307 // the parser, we "know" the variable is constant on one path and we force
1308 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
1309 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more
1310 // general in that we don't need constants. Since CMove's are only inserted
1311 // in very special circumstances, we do it here on generic Phi's.
is_cmove_id(PhaseTransform * phase,int true_path)1312 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
1313 assert(true_path !=0, "only diamond shape graph expected");
1314
1315 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1316 // phi->region->if_proj->ifnode->bool->cmp
1317 Node* region = in(0);
1318 Node* iff = region->in(1)->in(0);
1319 BoolNode* b = iff->in(1)->as_Bool();
1320 Node* cmp = b->in(1);
1321 Node* tval = in(true_path);
1322 Node* fval = in(3-true_path);
1323 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
1324 if (id == NULL)
1325 return NULL;
1326
1327 // Either value might be a cast that depends on a branch of 'iff'.
1328 // Since the 'id' value will float free of the diamond, either
1329 // decast or return failure.
1330 Node* ctl = id->in(0);
1331 if (ctl != NULL && ctl->in(0) == iff) {
1332 if (id->is_ConstraintCast()) {
1333 return id->in(1);
1334 } else {
1335 // Don't know how to disentangle this value.
1336 return NULL;
1337 }
1338 }
1339
1340 return id;
1341 }
1342
1343 //------------------------------Identity---------------------------------------
1344 // Check for Region being Identity.
Identity(PhaseGVN * phase)1345 Node* PhiNode::Identity(PhaseGVN* phase) {
1346 // Check for no merging going on
1347 // (There used to be special-case code here when this->region->is_Loop.
1348 // It would check for a tributary phi on the backedge that the main phi
1349 // trivially, perhaps with a single cast. The unique_input method
1350 // does all this and more, by reducing such tributaries to 'this'.)
1351 Node* uin = unique_input(phase, false);
1352 if (uin != NULL) {
1353 return uin;
1354 }
1355
1356 int true_path = is_diamond_phi();
1357 if (true_path != 0) {
1358 Node* id = is_cmove_id(phase, true_path);
1359 if (id != NULL) return id;
1360 }
1361
1362 // Looking for phis with identical inputs. If we find one that has
1363 // type TypePtr::BOTTOM, replace the current phi with the bottom phi.
1364 if (phase->is_IterGVN() && type() == Type::MEMORY && adr_type() !=
1365 TypePtr::BOTTOM && !adr_type()->is_known_instance()) {
1366 uint phi_len = req();
1367 Node* phi_reg = region();
1368 for (DUIterator_Fast imax, i = phi_reg->fast_outs(imax); i < imax; i++) {
1369 Node* u = phi_reg->fast_out(i);
1370 if (u->is_Phi() && u->as_Phi()->type() == Type::MEMORY &&
1371 u->adr_type() == TypePtr::BOTTOM && u->in(0) == phi_reg &&
1372 u->req() == phi_len) {
1373 for (uint j = 1; j < phi_len; j++) {
1374 if (in(j) != u->in(j)) {
1375 u = NULL;
1376 break;
1377 }
1378 }
1379 if (u != NULL) {
1380 return u;
1381 }
1382 }
1383 }
1384 }
1385
1386 return this; // No identity
1387 }
1388
1389 //-----------------------------unique_input------------------------------------
1390 // Find the unique value, discounting top, self-loops, and casts.
1391 // Return top if there are no inputs, and self if there are multiple.
unique_input(PhaseTransform * phase,bool uncast)1392 Node* PhiNode::unique_input(PhaseTransform* phase, bool uncast) {
1393 // 1) One unique direct input,
1394 // or if uncast is true:
1395 // 2) some of the inputs have an intervening ConstraintCast
1396 // 3) an input is a self loop
1397 //
1398 // 1) input or 2) input or 3) input __
1399 // / \ / \ \ / \
1400 // \ / | cast phi cast
1401 // phi \ / / \ /
1402 // phi / --
1403
1404 Node* r = in(0); // RegionNode
1405 Node* input = NULL; // The unique direct input (maybe uncasted = ConstraintCasts removed)
1406
1407 for (uint i = 1, cnt = req(); i < cnt; ++i) {
1408 Node* rc = r->in(i);
1409 if (rc == NULL || phase->type(rc) == Type::TOP)
1410 continue; // ignore unreachable control path
1411 Node* n = in(i);
1412 if (n == NULL)
1413 continue;
1414 Node* un = n;
1415 if (uncast) {
1416 #ifdef ASSERT
1417 Node* m = un->uncast();
1418 #endif
1419 while (un != NULL && un->req() == 2 && un->is_ConstraintCast()) {
1420 Node* next = un->in(1);
1421 if (phase->type(next)->isa_rawptr() && phase->type(un)->isa_oopptr()) {
1422 // risk exposing raw ptr at safepoint
1423 break;
1424 }
1425 un = next;
1426 }
1427 assert(m == un || un->in(1) == m, "Only expected at CheckCastPP from allocation");
1428 }
1429 if (un == NULL || un == this || phase->type(un) == Type::TOP) {
1430 continue; // ignore if top, or in(i) and "this" are in a data cycle
1431 }
1432 // Check for a unique input (maybe uncasted)
1433 if (input == NULL) {
1434 input = un;
1435 } else if (input != un) {
1436 input = NodeSentinel; // no unique input
1437 }
1438 }
1439 if (input == NULL) {
1440 return phase->C->top(); // no inputs
1441 }
1442
1443 if (input != NodeSentinel) {
1444 return input; // one unique direct input
1445 }
1446
1447 // Nothing.
1448 return NULL;
1449 }
1450
1451 //------------------------------is_x2logic-------------------------------------
1452 // Check for simple convert-to-boolean pattern
1453 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
1454 // Convert Phi to an ConvIB.
is_x2logic(PhaseGVN * phase,PhiNode * phi,int true_path)1455 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
1456 assert(true_path !=0, "only diamond shape graph expected");
1457 // Convert the true/false index into an expected 0/1 return.
1458 // Map 2->0 and 1->1.
1459 int flipped = 2-true_path;
1460
1461 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1462 // phi->region->if_proj->ifnode->bool->cmp
1463 Node *region = phi->in(0);
1464 Node *iff = region->in(1)->in(0);
1465 BoolNode *b = (BoolNode*)iff->in(1);
1466 const CmpNode *cmp = (CmpNode*)b->in(1);
1467
1468 Node *zero = phi->in(1);
1469 Node *one = phi->in(2);
1470 const Type *tzero = phase->type( zero );
1471 const Type *tone = phase->type( one );
1472
1473 // Check for compare vs 0
1474 const Type *tcmp = phase->type(cmp->in(2));
1475 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
1476 // Allow cmp-vs-1 if the other input is bounded by 0-1
1477 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
1478 return NULL;
1479 flipped = 1-flipped; // Test is vs 1 instead of 0!
1480 }
1481
1482 // Check for setting zero/one opposite expected
1483 if( tzero == TypeInt::ZERO ) {
1484 if( tone == TypeInt::ONE ) {
1485 } else return NULL;
1486 } else if( tzero == TypeInt::ONE ) {
1487 if( tone == TypeInt::ZERO ) {
1488 flipped = 1-flipped;
1489 } else return NULL;
1490 } else return NULL;
1491
1492 // Check for boolean test backwards
1493 if( b->_test._test == BoolTest::ne ) {
1494 } else if( b->_test._test == BoolTest::eq ) {
1495 flipped = 1-flipped;
1496 } else return NULL;
1497
1498 // Build int->bool conversion
1499 Node *n = new Conv2BNode(cmp->in(1));
1500 if( flipped )
1501 n = new XorINode( phase->transform(n), phase->intcon(1) );
1502
1503 return n;
1504 }
1505
1506 //------------------------------is_cond_add------------------------------------
1507 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;"
1508 // To be profitable the control flow has to disappear; there can be no other
1509 // values merging here. We replace the test-and-branch with:
1510 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by
1511 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
1512 // Then convert Y to 0-or-Y and finally add.
1513 // This is a key transform for SpecJava _201_compress.
is_cond_add(PhaseGVN * phase,PhiNode * phi,int true_path)1514 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
1515 assert(true_path !=0, "only diamond shape graph expected");
1516
1517 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1518 // phi->region->if_proj->ifnode->bool->cmp
1519 RegionNode *region = (RegionNode*)phi->in(0);
1520 Node *iff = region->in(1)->in(0);
1521 BoolNode* b = iff->in(1)->as_Bool();
1522 const CmpNode *cmp = (CmpNode*)b->in(1);
1523
1524 // Make sure only merging this one phi here
1525 if (region->has_unique_phi() != phi) return NULL;
1526
1527 // Make sure each arm of the diamond has exactly one output, which we assume
1528 // is the region. Otherwise, the control flow won't disappear.
1529 if (region->in(1)->outcnt() != 1) return NULL;
1530 if (region->in(2)->outcnt() != 1) return NULL;
1531
1532 // Check for "(P < Q)" of type signed int
1533 if (b->_test._test != BoolTest::lt) return NULL;
1534 if (cmp->Opcode() != Op_CmpI) return NULL;
1535
1536 Node *p = cmp->in(1);
1537 Node *q = cmp->in(2);
1538 Node *n1 = phi->in( true_path);
1539 Node *n2 = phi->in(3-true_path);
1540
1541 int op = n1->Opcode();
1542 if( op != Op_AddI // Need zero as additive identity
1543 /*&&op != Op_SubI &&
1544 op != Op_AddP &&
1545 op != Op_XorI &&
1546 op != Op_OrI*/ )
1547 return NULL;
1548
1549 Node *x = n2;
1550 Node *y = NULL;
1551 if( x == n1->in(1) ) {
1552 y = n1->in(2);
1553 } else if( x == n1->in(2) ) {
1554 y = n1->in(1);
1555 } else return NULL;
1556
1557 // Not so profitable if compare and add are constants
1558 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
1559 return NULL;
1560
1561 Node *cmplt = phase->transform( new CmpLTMaskNode(p,q) );
1562 Node *j_and = phase->transform( new AndINode(cmplt,y) );
1563 return new AddINode(j_and,x);
1564 }
1565
1566 //------------------------------is_absolute------------------------------------
1567 // Check for absolute value.
is_absolute(PhaseGVN * phase,PhiNode * phi_root,int true_path)1568 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
1569 assert(true_path !=0, "only diamond shape graph expected");
1570
1571 int cmp_zero_idx = 0; // Index of compare input where to look for zero
1572 int phi_x_idx = 0; // Index of phi input where to find naked x
1573
1574 // ABS ends with the merge of 2 control flow paths.
1575 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
1576 int false_path = 3 - true_path;
1577
1578 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1579 // phi->region->if_proj->ifnode->bool->cmp
1580 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
1581 Node *cmp = bol->in(1);
1582
1583 // Check bool sense
1584 if (cmp->Opcode() == Op_CmpF || cmp->Opcode() == Op_CmpD) {
1585 switch (bol->_test._test) {
1586 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break;
1587 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1588 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1589 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
1590 default: return NULL; break;
1591 }
1592 } else if (cmp->Opcode() == Op_CmpI || cmp->Opcode() == Op_CmpL) {
1593 switch (bol->_test._test) {
1594 case BoolTest::lt:
1595 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1596 case BoolTest::gt:
1597 case BoolTest::ge: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1598 default: return NULL; break;
1599 }
1600 }
1601
1602 // Test is next
1603 const Type *tzero = NULL;
1604 switch (cmp->Opcode()) {
1605 case Op_CmpI: tzero = TypeInt::ZERO; break; // Integer ABS
1606 case Op_CmpL: tzero = TypeLong::ZERO; break; // Long ABS
1607 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS
1608 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS
1609 default: return NULL;
1610 }
1611
1612 // Find zero input of compare; the other input is being abs'd
1613 Node *x = NULL;
1614 bool flip = false;
1615 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
1616 x = cmp->in(3 - cmp_zero_idx);
1617 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
1618 // The test is inverted, we should invert the result...
1619 x = cmp->in(cmp_zero_idx);
1620 flip = true;
1621 } else {
1622 return NULL;
1623 }
1624
1625 // Next get the 2 pieces being selected, one is the original value
1626 // and the other is the negated value.
1627 if( phi_root->in(phi_x_idx) != x ) return NULL;
1628
1629 // Check other phi input for subtract node
1630 Node *sub = phi_root->in(3 - phi_x_idx);
1631
1632 bool is_sub = sub->Opcode() == Op_SubF || sub->Opcode() == Op_SubD ||
1633 sub->Opcode() == Op_SubI || sub->Opcode() == Op_SubL;
1634
1635 // Allow only Sub(0,X) and fail out for all others; Neg is not OK
1636 if (!is_sub || phase->type(sub->in(1)) != tzero || sub->in(2) != x) return NULL;
1637
1638 if (tzero == TypeF::ZERO) {
1639 x = new AbsFNode(x);
1640 if (flip) {
1641 x = new SubFNode(sub->in(1), phase->transform(x));
1642 }
1643 } else if (tzero == TypeD::ZERO) {
1644 x = new AbsDNode(x);
1645 if (flip) {
1646 x = new SubDNode(sub->in(1), phase->transform(x));
1647 }
1648 } else if (tzero == TypeInt::ZERO && Matcher::match_rule_supported(Op_AbsI)) {
1649 x = new AbsINode(x);
1650 if (flip) {
1651 x = new SubINode(sub->in(1), phase->transform(x));
1652 }
1653 } else if (tzero == TypeLong::ZERO && Matcher::match_rule_supported(Op_AbsL)) {
1654 x = new AbsLNode(x);
1655 if (flip) {
1656 x = new SubLNode(sub->in(1), phase->transform(x));
1657 }
1658 } else return NULL;
1659
1660 return x;
1661 }
1662
1663 //------------------------------split_once-------------------------------------
1664 // Helper for split_flow_path
split_once(PhaseIterGVN * igvn,Node * phi,Node * val,Node * n,Node * newn)1665 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
1666 igvn->hash_delete(n); // Remove from hash before hacking edges
1667
1668 uint j = 1;
1669 for (uint i = phi->req()-1; i > 0; i--) {
1670 if (phi->in(i) == val) { // Found a path with val?
1671 // Add to NEW Region/Phi, no DU info
1672 newn->set_req( j++, n->in(i) );
1673 // Remove from OLD Region/Phi
1674 n->del_req(i);
1675 }
1676 }
1677
1678 // Register the new node but do not transform it. Cannot transform until the
1679 // entire Region/Phi conglomerate has been hacked as a single huge transform.
1680 igvn->register_new_node_with_optimizer( newn );
1681
1682 // Now I can point to the new node.
1683 n->add_req(newn);
1684 igvn->_worklist.push(n);
1685 }
1686
1687 //------------------------------split_flow_path--------------------------------
1688 // Check for merging identical values and split flow paths
split_flow_path(PhaseGVN * phase,PhiNode * phi)1689 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) {
1690 BasicType bt = phi->type()->basic_type();
1691 if( bt == T_ILLEGAL || type2size[bt] <= 0 )
1692 return NULL; // Bail out on funny non-value stuff
1693 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a
1694 return NULL; // third unequal input to be worth doing
1695
1696 // Scan for a constant
1697 uint i;
1698 for( i = 1; i < phi->req()-1; i++ ) {
1699 Node *n = phi->in(i);
1700 if( !n ) return NULL;
1701 if( phase->type(n) == Type::TOP ) return NULL;
1702 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN || n->Opcode() == Op_ConNKlass )
1703 break;
1704 }
1705 if( i >= phi->req() ) // Only split for constants
1706 return NULL;
1707
1708 Node *val = phi->in(i); // Constant to split for
1709 uint hit = 0; // Number of times it occurs
1710 Node *r = phi->region();
1711
1712 for( ; i < phi->req(); i++ ){ // Count occurrences of constant
1713 Node *n = phi->in(i);
1714 if( !n ) return NULL;
1715 if( phase->type(n) == Type::TOP ) return NULL;
1716 if( phi->in(i) == val ) {
1717 hit++;
1718 if (PhaseIdealLoop::find_predicate(r->in(i)) != NULL) {
1719 return NULL; // don't split loop entry path
1720 }
1721 }
1722 }
1723
1724 if( hit <= 1 || // Make sure we find 2 or more
1725 hit == phi->req()-1 ) // and not ALL the same value
1726 return NULL;
1727
1728 // Now start splitting out the flow paths that merge the same value.
1729 // Split first the RegionNode.
1730 PhaseIterGVN *igvn = phase->is_IterGVN();
1731 RegionNode *newr = new RegionNode(hit+1);
1732 split_once(igvn, phi, val, r, newr);
1733
1734 // Now split all other Phis than this one
1735 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) {
1736 Node* phi2 = r->fast_out(k);
1737 if( phi2->is_Phi() && phi2->as_Phi() != phi ) {
1738 PhiNode *newphi = PhiNode::make_blank(newr, phi2);
1739 split_once(igvn, phi, val, phi2, newphi);
1740 }
1741 }
1742
1743 // Clean up this guy
1744 igvn->hash_delete(phi);
1745 for( i = phi->req()-1; i > 0; i-- ) {
1746 if( phi->in(i) == val ) {
1747 phi->del_req(i);
1748 }
1749 }
1750 phi->add_req(val);
1751
1752 return phi;
1753 }
1754
1755 //=============================================================================
1756 //------------------------------simple_data_loop_check-------------------------
1757 // Try to determining if the phi node in a simple safe/unsafe data loop.
1758 // Returns:
1759 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
1760 // Safe - safe case when the phi and it's inputs reference only safe data
1761 // nodes;
1762 // Unsafe - the phi and it's inputs reference unsafe data nodes but there
1763 // is no reference back to the phi - need a graph walk
1764 // to determine if it is in a loop;
1765 // UnsafeLoop - unsafe case when the phi references itself directly or through
1766 // unsafe data node.
1767 // Note: a safe data node is a node which could/never reference itself during
1768 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP.
1769 // I mark Phi nodes as safe node not only because they can reference itself
1770 // but also to prevent mistaking the fallthrough case inside an outer loop
1771 // as dead loop when the phi references itselfs through an other phi.
simple_data_loop_check(Node * in) const1772 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const {
1773 // It is unsafe loop if the phi node references itself directly.
1774 if (in == (Node*)this)
1775 return UnsafeLoop; // Unsafe loop
1776 // Unsafe loop if the phi node references itself through an unsafe data node.
1777 // Exclude cases with null inputs or data nodes which could reference
1778 // itself (safe for dead loops).
1779 if (in != NULL && !in->is_dead_loop_safe()) {
1780 // Check inputs of phi's inputs also.
1781 // It is much less expensive then full graph walk.
1782 uint cnt = in->req();
1783 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1;
1784 for (; i < cnt; ++i) {
1785 Node* m = in->in(i);
1786 if (m == (Node*)this)
1787 return UnsafeLoop; // Unsafe loop
1788 if (m != NULL && !m->is_dead_loop_safe()) {
1789 // Check the most common case (about 30% of all cases):
1790 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con).
1791 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL;
1792 if (m1 == (Node*)this)
1793 return UnsafeLoop; // Unsafe loop
1794 if (m1 != NULL && m1 == m->in(2) &&
1795 m1->is_dead_loop_safe() && m->in(3)->is_Con()) {
1796 continue; // Safe case
1797 }
1798 // The phi references an unsafe node - need full analysis.
1799 return Unsafe;
1800 }
1801 }
1802 }
1803 return Safe; // Safe case - we can optimize the phi node.
1804 }
1805
1806 //------------------------------is_unsafe_data_reference-----------------------
1807 // If phi can be reached through the data input - it is data loop.
is_unsafe_data_reference(Node * in) const1808 bool PhiNode::is_unsafe_data_reference(Node *in) const {
1809 assert(req() > 1, "");
1810 // First, check simple cases when phi references itself directly or
1811 // through an other node.
1812 LoopSafety safety = simple_data_loop_check(in);
1813 if (safety == UnsafeLoop)
1814 return true; // phi references itself - unsafe loop
1815 else if (safety == Safe)
1816 return false; // Safe case - phi could be replaced with the unique input.
1817
1818 // Unsafe case when we should go through data graph to determine
1819 // if the phi references itself.
1820
1821 ResourceMark rm;
1822
1823 Node_List nstack;
1824 VectorSet visited;
1825
1826 nstack.push(in); // Start with unique input.
1827 visited.set(in->_idx);
1828 while (nstack.size() != 0) {
1829 Node* n = nstack.pop();
1830 uint cnt = n->req();
1831 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1;
1832 for (; i < cnt; i++) {
1833 Node* m = n->in(i);
1834 if (m == (Node*)this) {
1835 return true; // Data loop
1836 }
1837 if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases.
1838 if (!visited.test_set(m->_idx))
1839 nstack.push(m);
1840 }
1841 }
1842 }
1843 return false; // The phi is not reachable from its inputs
1844 }
1845
1846 // Is this Phi's region or some inputs to the region enqueued for IGVN
1847 // and so could cause the region to be optimized out?
wait_for_region_igvn(PhaseGVN * phase)1848 bool PhiNode::wait_for_region_igvn(PhaseGVN* phase) {
1849 PhaseIterGVN* igvn = phase->is_IterGVN();
1850 Unique_Node_List& worklist = igvn->_worklist;
1851 bool delay = false;
1852 Node* r = in(0);
1853 for (uint j = 1; j < req(); j++) {
1854 Node* rc = r->in(j);
1855 Node* n = in(j);
1856 if (rc != NULL &&
1857 rc->is_Proj()) {
1858 if (worklist.member(rc)) {
1859 delay = true;
1860 } else if (rc->in(0) != NULL &&
1861 rc->in(0)->is_If()) {
1862 if (worklist.member(rc->in(0))) {
1863 delay = true;
1864 } else if (rc->in(0)->in(1) != NULL &&
1865 rc->in(0)->in(1)->is_Bool()) {
1866 if (worklist.member(rc->in(0)->in(1))) {
1867 delay = true;
1868 } else if (rc->in(0)->in(1)->in(1) != NULL &&
1869 rc->in(0)->in(1)->in(1)->is_Cmp()) {
1870 if (worklist.member(rc->in(0)->in(1)->in(1))) {
1871 delay = true;
1872 }
1873 }
1874 }
1875 }
1876 }
1877 }
1878 if (delay) {
1879 worklist.push(this);
1880 }
1881 return delay;
1882 }
1883
1884 //------------------------------Ideal------------------------------------------
1885 // Return a node which is more "ideal" than the current node. Must preserve
1886 // the CFG, but we can still strip out dead paths.
Ideal(PhaseGVN * phase,bool can_reshape)1887 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1888 Node *r = in(0); // RegionNode
1889 assert(r != NULL && r->is_Region(), "this phi must have a region");
1890 assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge");
1891
1892 // Note: During parsing, phis are often transformed before their regions.
1893 // This means we have to use type_or_null to defend against untyped regions.
1894 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1895 return NULL; // No change
1896
1897 Node *top = phase->C->top();
1898 bool new_phi = (outcnt() == 0); // transforming new Phi
1899 // No change for igvn if new phi is not hooked
1900 if (new_phi && can_reshape)
1901 return NULL;
1902
1903 // The are 2 situations when only one valid phi's input is left
1904 // (in addition to Region input).
1905 // One: region is not loop - replace phi with this input.
1906 // Two: region is loop - replace phi with top since this data path is dead
1907 // and we need to break the dead data loop.
1908 Node* progress = NULL; // Record if any progress made
1909 for( uint j = 1; j < req(); ++j ){ // For all paths in
1910 // Check unreachable control paths
1911 Node* rc = r->in(j);
1912 Node* n = in(j); // Get the input
1913 if (rc == NULL || phase->type(rc) == Type::TOP) {
1914 if (n != top) { // Not already top?
1915 PhaseIterGVN *igvn = phase->is_IterGVN();
1916 if (can_reshape && igvn != NULL) {
1917 igvn->_worklist.push(r);
1918 }
1919 // Nuke it down
1920 if (can_reshape) {
1921 set_req_X(j, top, igvn);
1922 } else {
1923 set_req(j, top);
1924 }
1925 progress = this; // Record progress
1926 }
1927 }
1928 }
1929
1930 if (can_reshape && outcnt() == 0) {
1931 // set_req() above may kill outputs if Phi is referenced
1932 // only by itself on the dead (top) control path.
1933 return top;
1934 }
1935
1936 bool uncasted = false;
1937 Node* uin = unique_input(phase, false);
1938 if (uin == NULL && can_reshape &&
1939 // If there is a chance that the region can be optimized out do
1940 // not add a cast node that we can't remove yet.
1941 !wait_for_region_igvn(phase)) {
1942 uncasted = true;
1943 uin = unique_input(phase, true);
1944 }
1945 if (uin == top) { // Simplest case: no alive inputs.
1946 if (can_reshape) // IGVN transformation
1947 return top;
1948 else
1949 return NULL; // Identity will return TOP
1950 } else if (uin != NULL) {
1951 // Only one not-NULL unique input path is left.
1952 // Determine if this input is backedge of a loop.
1953 // (Skip new phis which have no uses and dead regions).
1954 if (outcnt() > 0 && r->in(0) != NULL) {
1955 if (is_data_loop(r->as_Region(), uin, phase)) {
1956 // Break this data loop to avoid creation of a dead loop.
1957 if (can_reshape) {
1958 return top;
1959 } else {
1960 // We can't return top if we are in Parse phase - cut inputs only
1961 // let Identity to handle the case.
1962 replace_edge(uin, top);
1963 return NULL;
1964 }
1965 }
1966 }
1967
1968 if (uncasted) {
1969 // Add cast nodes between the phi to be removed and its unique input.
1970 // Wait until after parsing for the type information to propagate from the casts.
1971 assert(can_reshape, "Invalid during parsing");
1972 const Type* phi_type = bottom_type();
1973 assert(phi_type->isa_int() || phi_type->isa_ptr() || phi_type->isa_long(), "bad phi type");
1974 // Add casts to carry the control dependency of the Phi that is
1975 // going away
1976 Node* cast = NULL;
1977 if (phi_type->isa_int()) {
1978 cast = ConstraintCastNode::make_cast(Op_CastII, r, uin, phi_type, true);
1979 } else if (phi_type->isa_long()) {
1980 cast = ConstraintCastNode::make_cast(Op_CastLL, r, uin, phi_type, true);
1981 } else {
1982 const Type* uin_type = phase->type(uin);
1983 if (!phi_type->isa_oopptr() && !uin_type->isa_oopptr()) {
1984 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true);
1985 } else {
1986 // Use a CastPP for a cast to not null and a CheckCastPP for
1987 // a cast to a new klass (and both if both null-ness and
1988 // klass change).
1989
1990 // If the type of phi is not null but the type of uin may be
1991 // null, uin's type must be casted to not null
1992 if (phi_type->join(TypePtr::NOTNULL) == phi_type->remove_speculative() &&
1993 uin_type->join(TypePtr::NOTNULL) != uin_type->remove_speculative()) {
1994 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, TypePtr::NOTNULL, true);
1995 }
1996
1997 // If the type of phi and uin, both casted to not null,
1998 // differ the klass of uin must be (check)cast'ed to match
1999 // that of phi
2000 if (phi_type->join_speculative(TypePtr::NOTNULL) != uin_type->join_speculative(TypePtr::NOTNULL)) {
2001 Node* n = uin;
2002 if (cast != NULL) {
2003 cast = phase->transform(cast);
2004 n = cast;
2005 }
2006 cast = ConstraintCastNode::make_cast(Op_CheckCastPP, r, n, phi_type, true);
2007 }
2008 if (cast == NULL) {
2009 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true);
2010 }
2011 }
2012 }
2013 assert(cast != NULL, "cast should be set");
2014 cast = phase->transform(cast);
2015 // set all inputs to the new cast(s) so the Phi is removed by Identity
2016 PhaseIterGVN* igvn = phase->is_IterGVN();
2017 for (uint i = 1; i < req(); i++) {
2018 set_req_X(i, cast, igvn);
2019 }
2020 uin = cast;
2021 }
2022
2023 // One unique input.
2024 debug_only(Node* ident = Identity(phase));
2025 // The unique input must eventually be detected by the Identity call.
2026 #ifdef ASSERT
2027 if (ident != uin && !ident->is_top()) {
2028 // print this output before failing assert
2029 r->dump(3);
2030 this->dump(3);
2031 ident->dump();
2032 uin->dump();
2033 }
2034 #endif
2035 assert(ident == uin || ident->is_top(), "Identity must clean this up");
2036 return NULL;
2037 }
2038
2039 Node* opt = NULL;
2040 int true_path = is_diamond_phi();
2041 if( true_path != 0 ) {
2042 // Check for CMove'ing identity. If it would be unsafe,
2043 // handle it here. In the safe case, let Identity handle it.
2044 Node* unsafe_id = is_cmove_id(phase, true_path);
2045 if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) )
2046 opt = unsafe_id;
2047
2048 // Check for simple convert-to-boolean pattern
2049 if( opt == NULL )
2050 opt = is_x2logic(phase, this, true_path);
2051
2052 // Check for absolute value
2053 if( opt == NULL )
2054 opt = is_absolute(phase, this, true_path);
2055
2056 // Check for conditional add
2057 if( opt == NULL && can_reshape )
2058 opt = is_cond_add(phase, this, true_path);
2059
2060 // These 4 optimizations could subsume the phi:
2061 // have to check for a dead data loop creation.
2062 if( opt != NULL ) {
2063 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) {
2064 // Found dead loop.
2065 if( can_reshape )
2066 return top;
2067 // We can't return top if we are in Parse phase - cut inputs only
2068 // to stop further optimizations for this phi. Identity will return TOP.
2069 assert(req() == 3, "only diamond merge phi here");
2070 set_req(1, top);
2071 set_req(2, top);
2072 return NULL;
2073 } else {
2074 return opt;
2075 }
2076 }
2077 }
2078
2079 // Check for merging identical values and split flow paths
2080 if (can_reshape) {
2081 opt = split_flow_path(phase, this);
2082 // This optimization only modifies phi - don't need to check for dead loop.
2083 assert(opt == NULL || opt == this, "do not elide phi");
2084 if (opt != NULL) return opt;
2085 }
2086
2087 if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) {
2088 // Try to undo Phi of AddP:
2089 // (Phi (AddP base address offset) (AddP base2 address2 offset2))
2090 // becomes:
2091 // newbase := (Phi base base2)
2092 // newaddress := (Phi address address2)
2093 // newoffset := (Phi offset offset2)
2094 // (AddP newbase newaddress newoffset)
2095 //
2096 // This occurs as a result of unsuccessful split_thru_phi and
2097 // interferes with taking advantage of addressing modes. See the
2098 // clone_shift_expressions code in matcher.cpp
2099 Node* addp = in(1);
2100 Node* base = addp->in(AddPNode::Base);
2101 Node* address = addp->in(AddPNode::Address);
2102 Node* offset = addp->in(AddPNode::Offset);
2103 if (base != NULL && address != NULL && offset != NULL &&
2104 !base->is_top() && !address->is_top() && !offset->is_top()) {
2105 const Type* base_type = base->bottom_type();
2106 const Type* address_type = address->bottom_type();
2107 // make sure that all the inputs are similar to the first one,
2108 // i.e. AddP with base == address and same offset as first AddP
2109 bool doit = true;
2110 for (uint i = 2; i < req(); i++) {
2111 if (in(i) == NULL ||
2112 in(i)->Opcode() != Op_AddP ||
2113 in(i)->in(AddPNode::Base) == NULL ||
2114 in(i)->in(AddPNode::Address) == NULL ||
2115 in(i)->in(AddPNode::Offset) == NULL ||
2116 in(i)->in(AddPNode::Base)->is_top() ||
2117 in(i)->in(AddPNode::Address)->is_top() ||
2118 in(i)->in(AddPNode::Offset)->is_top()) {
2119 doit = false;
2120 break;
2121 }
2122 if (in(i)->in(AddPNode::Offset) != base) {
2123 base = NULL;
2124 }
2125 if (in(i)->in(AddPNode::Offset) != offset) {
2126 offset = NULL;
2127 }
2128 if (in(i)->in(AddPNode::Address) != address) {
2129 address = NULL;
2130 }
2131 // Accumulate type for resulting Phi
2132 base_type = base_type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type());
2133 address_type = address_type->meet_speculative(in(i)->in(AddPNode::Address)->bottom_type());
2134 }
2135 if (doit && base == NULL) {
2136 // Check for neighboring AddP nodes in a tree.
2137 // If they have a base, use that it.
2138 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) {
2139 Node* u = this->fast_out(k);
2140 if (u->is_AddP()) {
2141 Node* base2 = u->in(AddPNode::Base);
2142 if (base2 != NULL && !base2->is_top()) {
2143 if (base == NULL)
2144 base = base2;
2145 else if (base != base2)
2146 { doit = false; break; }
2147 }
2148 }
2149 }
2150 }
2151 if (doit) {
2152 if (base == NULL) {
2153 base = new PhiNode(in(0), base_type, NULL);
2154 for (uint i = 1; i < req(); i++) {
2155 base->init_req(i, in(i)->in(AddPNode::Base));
2156 }
2157 phase->is_IterGVN()->register_new_node_with_optimizer(base);
2158 }
2159 if (address == NULL) {
2160 address = new PhiNode(in(0), address_type, NULL);
2161 for (uint i = 1; i < req(); i++) {
2162 address->init_req(i, in(i)->in(AddPNode::Address));
2163 }
2164 phase->is_IterGVN()->register_new_node_with_optimizer(address);
2165 }
2166 if (offset == NULL) {
2167 offset = new PhiNode(in(0), TypeX_X, NULL);
2168 for (uint i = 1; i < req(); i++) {
2169 offset->init_req(i, in(i)->in(AddPNode::Offset));
2170 }
2171 phase->is_IterGVN()->register_new_node_with_optimizer(offset);
2172 }
2173 return new AddPNode(base, address, offset);
2174 }
2175 }
2176 }
2177
2178 // Split phis through memory merges, so that the memory merges will go away.
2179 // Piggy-back this transformation on the search for a unique input....
2180 // It will be as if the merged memory is the unique value of the phi.
2181 // (Do not attempt this optimization unless parsing is complete.
2182 // It would make the parser's memory-merge logic sick.)
2183 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.)
2184 if (progress == NULL && can_reshape && type() == Type::MEMORY) {
2185 // see if this phi should be sliced
2186 uint merge_width = 0;
2187 bool saw_self = false;
2188 for( uint i=1; i<req(); ++i ) {// For all paths in
2189 Node *ii = in(i);
2190 // TOP inputs should not be counted as safe inputs because if the
2191 // Phi references itself through all other inputs then splitting the
2192 // Phi through memory merges would create dead loop at later stage.
2193 if (ii == top) {
2194 return NULL; // Delay optimization until graph is cleaned.
2195 }
2196 if (ii->is_MergeMem()) {
2197 MergeMemNode* n = ii->as_MergeMem();
2198 merge_width = MAX2(merge_width, n->req());
2199 saw_self = saw_self || (n->base_memory() == this);
2200 }
2201 }
2202
2203 // This restriction is temporarily necessary to ensure termination:
2204 if (!saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0;
2205
2206 if (merge_width > Compile::AliasIdxRaw) {
2207 // found at least one non-empty MergeMem
2208 const TypePtr* at = adr_type();
2209 if (at != TypePtr::BOTTOM) {
2210 // Patch the existing phi to select an input from the merge:
2211 // Phi:AT1(...MergeMem(m0, m1, m2)...) into
2212 // Phi:AT1(...m1...)
2213 int alias_idx = phase->C->get_alias_index(at);
2214 for (uint i=1; i<req(); ++i) {
2215 Node *ii = in(i);
2216 if (ii->is_MergeMem()) {
2217 MergeMemNode* n = ii->as_MergeMem();
2218 // compress paths and change unreachable cycles to TOP
2219 // If not, we can update the input infinitely along a MergeMem cycle
2220 // Equivalent code is in MemNode::Ideal_common
2221 Node *m = phase->transform(n);
2222 if (outcnt() == 0) { // Above transform() may kill us!
2223 return top;
2224 }
2225 // If transformed to a MergeMem, get the desired slice
2226 // Otherwise the returned node represents memory for every slice
2227 Node *new_mem = (m->is_MergeMem()) ?
2228 m->as_MergeMem()->memory_at(alias_idx) : m;
2229 // Update input if it is progress over what we have now
2230 if (new_mem != ii) {
2231 set_req(i, new_mem);
2232 progress = this;
2233 }
2234 }
2235 }
2236 } else {
2237 // We know that at least one MergeMem->base_memory() == this
2238 // (saw_self == true). If all other inputs also references this phi
2239 // (directly or through data nodes) - it is a dead loop.
2240 bool saw_safe_input = false;
2241 for (uint j = 1; j < req(); ++j) {
2242 Node* n = in(j);
2243 if (n->is_MergeMem()) {
2244 MergeMemNode* mm = n->as_MergeMem();
2245 if (mm->base_memory() == this || mm->base_memory() == mm->empty_memory()) {
2246 // Skip this input if it references back to this phi or if the memory path is dead
2247 continue;
2248 }
2249 }
2250 if (!is_unsafe_data_reference(n)) {
2251 saw_safe_input = true; // found safe input
2252 break;
2253 }
2254 }
2255 if (!saw_safe_input) {
2256 // There is a dead loop: All inputs are either dead or reference back to this phi
2257 return top;
2258 }
2259
2260 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into
2261 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...))
2262 PhaseIterGVN* igvn = phase->is_IterGVN();
2263 Node* hook = new Node(1);
2264 PhiNode* new_base = (PhiNode*) clone();
2265 // Must eagerly register phis, since they participate in loops.
2266 if (igvn) {
2267 igvn->register_new_node_with_optimizer(new_base);
2268 hook->add_req(new_base);
2269 }
2270 MergeMemNode* result = MergeMemNode::make(new_base);
2271 for (uint i = 1; i < req(); ++i) {
2272 Node *ii = in(i);
2273 if (ii->is_MergeMem()) {
2274 MergeMemNode* n = ii->as_MergeMem();
2275 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) {
2276 // If we have not seen this slice yet, make a phi for it.
2277 bool made_new_phi = false;
2278 if (mms.is_empty()) {
2279 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C));
2280 made_new_phi = true;
2281 if (igvn) {
2282 igvn->register_new_node_with_optimizer(new_phi);
2283 hook->add_req(new_phi);
2284 }
2285 mms.set_memory(new_phi);
2286 }
2287 Node* phi = mms.memory();
2288 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice");
2289 phi->set_req(i, mms.memory2());
2290 }
2291 }
2292 }
2293 // Distribute all self-loops.
2294 { // (Extra braces to hide mms.)
2295 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2296 Node* phi = mms.memory();
2297 for (uint i = 1; i < req(); ++i) {
2298 if (phi->in(i) == this) phi->set_req(i, phi);
2299 }
2300 }
2301 }
2302 // now transform the new nodes, and return the mergemem
2303 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2304 Node* phi = mms.memory();
2305 mms.set_memory(phase->transform(phi));
2306 }
2307 hook->destruct(igvn);
2308 // Replace self with the result.
2309 return result;
2310 }
2311 }
2312 //
2313 // Other optimizations on the memory chain
2314 //
2315 const TypePtr* at = adr_type();
2316 for( uint i=1; i<req(); ++i ) {// For all paths in
2317 Node *ii = in(i);
2318 Node *new_in = MemNode::optimize_memory_chain(ii, at, NULL, phase);
2319 if (ii != new_in ) {
2320 set_req(i, new_in);
2321 progress = this;
2322 }
2323 }
2324 }
2325
2326 #ifdef _LP64
2327 // Push DecodeN/DecodeNKlass down through phi.
2328 // The rest of phi graph will transform by split EncodeP node though phis up.
2329 if ((UseCompressedOops || UseCompressedClassPointers) && can_reshape && progress == NULL) {
2330 bool may_push = true;
2331 bool has_decodeN = false;
2332 bool is_decodeN = false;
2333 for (uint i=1; i<req(); ++i) {// For all paths in
2334 Node *ii = in(i);
2335 if (ii->is_DecodeNarrowPtr() && ii->bottom_type() == bottom_type()) {
2336 // Do optimization if a non dead path exist.
2337 if (ii->in(1)->bottom_type() != Type::TOP) {
2338 has_decodeN = true;
2339 is_decodeN = ii->is_DecodeN();
2340 }
2341 } else if (!ii->is_Phi()) {
2342 may_push = false;
2343 }
2344 }
2345
2346 if (has_decodeN && may_push) {
2347 PhaseIterGVN *igvn = phase->is_IterGVN();
2348 // Make narrow type for new phi.
2349 const Type* narrow_t;
2350 if (is_decodeN) {
2351 narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr());
2352 } else {
2353 narrow_t = TypeNarrowKlass::make(this->bottom_type()->is_ptr());
2354 }
2355 PhiNode* new_phi = new PhiNode(r, narrow_t);
2356 uint orig_cnt = req();
2357 for (uint i=1; i<req(); ++i) {// For all paths in
2358 Node *ii = in(i);
2359 Node* new_ii = NULL;
2360 if (ii->is_DecodeNarrowPtr()) {
2361 assert(ii->bottom_type() == bottom_type(), "sanity");
2362 new_ii = ii->in(1);
2363 } else {
2364 assert(ii->is_Phi(), "sanity");
2365 if (ii->as_Phi() == this) {
2366 new_ii = new_phi;
2367 } else {
2368 if (is_decodeN) {
2369 new_ii = new EncodePNode(ii, narrow_t);
2370 } else {
2371 new_ii = new EncodePKlassNode(ii, narrow_t);
2372 }
2373 igvn->register_new_node_with_optimizer(new_ii);
2374 }
2375 }
2376 new_phi->set_req(i, new_ii);
2377 }
2378 igvn->register_new_node_with_optimizer(new_phi, this);
2379 if (is_decodeN) {
2380 progress = new DecodeNNode(new_phi, bottom_type());
2381 } else {
2382 progress = new DecodeNKlassNode(new_phi, bottom_type());
2383 }
2384 }
2385 }
2386 #endif
2387
2388 // Phi (VB ... VB) => VB (Phi ...) (Phi ...)
2389 if (EnableVectorReboxing && can_reshape && progress == NULL) {
2390 PhaseIterGVN* igvn = phase->is_IterGVN();
2391
2392 bool all_inputs_are_equiv_vboxes = true;
2393 for (uint i = 1; i < req(); ++i) {
2394 Node* n = in(i);
2395 if (in(i)->Opcode() != Op_VectorBox) {
2396 all_inputs_are_equiv_vboxes = false;
2397 break;
2398 }
2399 // Check that vector type of vboxes is equivalent
2400 if (i != 1) {
2401 if (Type::cmp(in(i-0)->in(VectorBoxNode::Value)->bottom_type(),
2402 in(i-1)->in(VectorBoxNode::Value)->bottom_type()) != 0) {
2403 all_inputs_are_equiv_vboxes = false;
2404 break;
2405 }
2406 if (Type::cmp(in(i-0)->in(VectorBoxNode::Box)->bottom_type(),
2407 in(i-1)->in(VectorBoxNode::Box)->bottom_type()) != 0) {
2408 all_inputs_are_equiv_vboxes = false;
2409 break;
2410 }
2411 }
2412 }
2413
2414 if (all_inputs_are_equiv_vboxes) {
2415 VectorBoxNode* vbox = static_cast<VectorBoxNode*>(in(1));
2416 PhiNode* new_vbox_phi = new PhiNode(r, vbox->box_type());
2417 PhiNode* new_vect_phi = new PhiNode(r, vbox->vec_type());
2418 for (uint i = 1; i < req(); ++i) {
2419 VectorBoxNode* old_vbox = static_cast<VectorBoxNode*>(in(i));
2420 new_vbox_phi->set_req(i, old_vbox->in(VectorBoxNode::Box));
2421 new_vect_phi->set_req(i, old_vbox->in(VectorBoxNode::Value));
2422 }
2423 igvn->register_new_node_with_optimizer(new_vbox_phi, this);
2424 igvn->register_new_node_with_optimizer(new_vect_phi, this);
2425 progress = new VectorBoxNode(igvn->C, new_vbox_phi, new_vect_phi, vbox->box_type(), vbox->vec_type());
2426 }
2427 }
2428
2429 return progress; // Return any progress
2430 }
2431
is_data_loop(RegionNode * r,Node * uin,const PhaseGVN * phase)2432 bool PhiNode::is_data_loop(RegionNode* r, Node* uin, const PhaseGVN* phase) {
2433 // First, take the short cut when we know it is a loop and the EntryControl data path is dead.
2434 // The loop node may only have one input because the entry path was removed in PhaseIdealLoop::Dominators().
2435 // Then, check if there is a data loop when the phi references itself directly or through other data nodes.
2436 assert(!r->is_Loop() || r->req() <= 3, "Loop node should have 3 or less inputs");
2437 const bool is_loop = (r->is_Loop() && r->req() == 3);
2438 const Node* top = phase->C->top();
2439 if (is_loop) {
2440 return !uin->eqv_uncast(in(LoopNode::EntryControl));
2441 } else {
2442 // We have a data loop either with an unsafe data reference or if a region is unreachable.
2443 return is_unsafe_data_reference(uin)
2444 || (r->req() == 3 && (r->in(1) != top && r->in(2) == top && r->is_unreachable_region(phase)));
2445 }
2446 }
2447
2448 //------------------------------is_tripcount-----------------------------------
is_tripcount(BasicType bt) const2449 bool PhiNode::is_tripcount(BasicType bt) const {
2450 return (in(0) != NULL && in(0)->is_BaseCountedLoop() &&
2451 in(0)->as_BaseCountedLoop()->operates_on(bt, true) &&
2452 in(0)->as_BaseCountedLoop()->phi() == this);
2453 }
2454
2455 //------------------------------out_RegMask------------------------------------
in_RegMask(uint i) const2456 const RegMask &PhiNode::in_RegMask(uint i) const {
2457 return i ? out_RegMask() : RegMask::Empty;
2458 }
2459
out_RegMask() const2460 const RegMask &PhiNode::out_RegMask() const {
2461 uint ideal_reg = _type->ideal_reg();
2462 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
2463 if( ideal_reg == 0 ) return RegMask::Empty;
2464 assert(ideal_reg != Op_RegFlags, "flags register is not spillable");
2465 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
2466 }
2467
2468 #ifndef PRODUCT
related(GrowableArray<Node * > * in_rel,GrowableArray<Node * > * out_rel,bool compact) const2469 void PhiNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2470 // For a PhiNode, the set of related nodes includes all inputs till level 2,
2471 // and all outputs till level 1. In compact mode, inputs till level 1 are
2472 // collected.
2473 this->collect_nodes(in_rel, compact ? 1 : 2, false, false);
2474 this->collect_nodes(out_rel, -1, false, false);
2475 }
2476
dump_spec(outputStream * st) const2477 void PhiNode::dump_spec(outputStream *st) const {
2478 TypeNode::dump_spec(st);
2479 if (is_tripcount(T_INT) || is_tripcount(T_LONG)) {
2480 st->print(" #tripcount");
2481 }
2482 }
2483 #endif
2484
2485
2486 //=============================================================================
Value(PhaseGVN * phase) const2487 const Type* GotoNode::Value(PhaseGVN* phase) const {
2488 // If the input is reachable, then we are executed.
2489 // If the input is not reachable, then we are not executed.
2490 return phase->type(in(0));
2491 }
2492
Identity(PhaseGVN * phase)2493 Node* GotoNode::Identity(PhaseGVN* phase) {
2494 return in(0); // Simple copy of incoming control
2495 }
2496
out_RegMask() const2497 const RegMask &GotoNode::out_RegMask() const {
2498 return RegMask::Empty;
2499 }
2500
2501 #ifndef PRODUCT
2502 //-----------------------------related-----------------------------------------
2503 // The related nodes of a GotoNode are all inputs at level 1, as well as the
2504 // outputs at level 1. This is regardless of compact mode.
related(GrowableArray<Node * > * in_rel,GrowableArray<Node * > * out_rel,bool compact) const2505 void GotoNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2506 this->collect_nodes(in_rel, 1, false, false);
2507 this->collect_nodes(out_rel, -1, false, false);
2508 }
2509 #endif
2510
2511
2512 //=============================================================================
out_RegMask() const2513 const RegMask &JumpNode::out_RegMask() const {
2514 return RegMask::Empty;
2515 }
2516
2517 #ifndef PRODUCT
2518 //-----------------------------related-----------------------------------------
2519 // The related nodes of a JumpNode are all inputs at level 1, as well as the
2520 // outputs at level 2 (to include actual jump targets beyond projection nodes).
2521 // This is regardless of compact mode.
related(GrowableArray<Node * > * in_rel,GrowableArray<Node * > * out_rel,bool compact) const2522 void JumpNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2523 this->collect_nodes(in_rel, 1, false, false);
2524 this->collect_nodes(out_rel, -2, false, false);
2525 }
2526 #endif
2527
2528 //=============================================================================
out_RegMask() const2529 const RegMask &JProjNode::out_RegMask() const {
2530 return RegMask::Empty;
2531 }
2532
2533 //=============================================================================
out_RegMask() const2534 const RegMask &CProjNode::out_RegMask() const {
2535 return RegMask::Empty;
2536 }
2537
2538
2539
2540 //=============================================================================
2541
hash() const2542 uint PCTableNode::hash() const { return Node::hash() + _size; }
cmp(const Node & n) const2543 bool PCTableNode::cmp( const Node &n ) const
2544 { return _size == ((PCTableNode&)n)._size; }
2545
bottom_type() const2546 const Type *PCTableNode::bottom_type() const {
2547 const Type** f = TypeTuple::fields(_size);
2548 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2549 return TypeTuple::make(_size, f);
2550 }
2551
2552 //------------------------------Value------------------------------------------
2553 // Compute the type of the PCTableNode. If reachable it is a tuple of
2554 // Control, otherwise the table targets are not reachable
Value(PhaseGVN * phase) const2555 const Type* PCTableNode::Value(PhaseGVN* phase) const {
2556 if( phase->type(in(0)) == Type::CONTROL )
2557 return bottom_type();
2558 return Type::TOP; // All paths dead? Then so are we
2559 }
2560
2561 //------------------------------Ideal------------------------------------------
2562 // Return a node which is more "ideal" than the current node. Strip out
2563 // control copies
Ideal(PhaseGVN * phase,bool can_reshape)2564 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2565 return remove_dead_region(phase, can_reshape) ? this : NULL;
2566 }
2567
2568 //=============================================================================
hash() const2569 uint JumpProjNode::hash() const {
2570 return Node::hash() + _dest_bci;
2571 }
2572
cmp(const Node & n) const2573 bool JumpProjNode::cmp( const Node &n ) const {
2574 return ProjNode::cmp(n) &&
2575 _dest_bci == ((JumpProjNode&)n)._dest_bci;
2576 }
2577
2578 #ifndef PRODUCT
dump_spec(outputStream * st) const2579 void JumpProjNode::dump_spec(outputStream *st) const {
2580 ProjNode::dump_spec(st);
2581 st->print("@bci %d ",_dest_bci);
2582 }
2583
dump_compact_spec(outputStream * st) const2584 void JumpProjNode::dump_compact_spec(outputStream *st) const {
2585 ProjNode::dump_compact_spec(st);
2586 st->print("(%d)%d@%d", _switch_val, _proj_no, _dest_bci);
2587 }
2588
related(GrowableArray<Node * > * in_rel,GrowableArray<Node * > * out_rel,bool compact) const2589 void JumpProjNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2590 // The related nodes of a JumpProjNode are its inputs and outputs at level 1.
2591 this->collect_nodes(in_rel, 1, false, false);
2592 this->collect_nodes(out_rel, -1, false, false);
2593 }
2594 #endif
2595
2596 //=============================================================================
2597 //------------------------------Value------------------------------------------
2598 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot
2599 // have the default "fall_through_index" path.
Value(PhaseGVN * phase) const2600 const Type* CatchNode::Value(PhaseGVN* phase) const {
2601 // Unreachable? Then so are all paths from here.
2602 if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
2603 // First assume all paths are reachable
2604 const Type** f = TypeTuple::fields(_size);
2605 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2606 // Identify cases that will always throw an exception
2607 // () rethrow call
2608 // () virtual or interface call with NULL receiver
2609 // () call is a check cast with incompatible arguments
2610 if( in(1)->is_Proj() ) {
2611 Node *i10 = in(1)->in(0);
2612 if( i10->is_Call() ) {
2613 CallNode *call = i10->as_Call();
2614 // Rethrows always throw exceptions, never return
2615 if (call->entry_point() == OptoRuntime::rethrow_stub()) {
2616 f[CatchProjNode::fall_through_index] = Type::TOP;
2617 } else if( call->req() > TypeFunc::Parms ) {
2618 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) );
2619 // Check for null receiver to virtual or interface calls
2620 if( call->is_CallDynamicJava() &&
2621 arg0->higher_equal(TypePtr::NULL_PTR) ) {
2622 f[CatchProjNode::fall_through_index] = Type::TOP;
2623 }
2624 } // End of if not a runtime stub
2625 } // End of if have call above me
2626 } // End of slot 1 is not a projection
2627 return TypeTuple::make(_size, f);
2628 }
2629
2630 //=============================================================================
hash() const2631 uint CatchProjNode::hash() const {
2632 return Node::hash() + _handler_bci;
2633 }
2634
2635
cmp(const Node & n) const2636 bool CatchProjNode::cmp( const Node &n ) const {
2637 return ProjNode::cmp(n) &&
2638 _handler_bci == ((CatchProjNode&)n)._handler_bci;
2639 }
2640
2641
2642 //------------------------------Identity---------------------------------------
2643 // If only 1 target is possible, choose it if it is the main control
Identity(PhaseGVN * phase)2644 Node* CatchProjNode::Identity(PhaseGVN* phase) {
2645 // If my value is control and no other value is, then treat as ID
2646 const TypeTuple *t = phase->type(in(0))->is_tuple();
2647 if (t->field_at(_con) != Type::CONTROL) return this;
2648 // If we remove the last CatchProj and elide the Catch/CatchProj, then we
2649 // also remove any exception table entry. Thus we must know the call
2650 // feeding the Catch will not really throw an exception. This is ok for
2651 // the main fall-thru control (happens when we know a call can never throw
2652 // an exception) or for "rethrow", because a further optimization will
2653 // yank the rethrow (happens when we inline a function that can throw an
2654 // exception and the caller has no handler). Not legal, e.g., for passing
2655 // a NULL receiver to a v-call, or passing bad types to a slow-check-cast.
2656 // These cases MUST throw an exception via the runtime system, so the VM
2657 // will be looking for a table entry.
2658 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode
2659 CallNode *call;
2660 if (_con != TypeFunc::Control && // Bail out if not the main control.
2661 !(proj->is_Proj() && // AND NOT a rethrow
2662 proj->in(0)->is_Call() &&
2663 (call = proj->in(0)->as_Call()) &&
2664 call->entry_point() == OptoRuntime::rethrow_stub()))
2665 return this;
2666
2667 // Search for any other path being control
2668 for (uint i = 0; i < t->cnt(); i++) {
2669 if (i != _con && t->field_at(i) == Type::CONTROL)
2670 return this;
2671 }
2672 // Only my path is possible; I am identity on control to the jump
2673 return in(0)->in(0);
2674 }
2675
2676
2677 #ifndef PRODUCT
dump_spec(outputStream * st) const2678 void CatchProjNode::dump_spec(outputStream *st) const {
2679 ProjNode::dump_spec(st);
2680 st->print("@bci %d ",_handler_bci);
2681 }
2682 #endif
2683
2684 //=============================================================================
2685 //------------------------------Identity---------------------------------------
2686 // Check for CreateEx being Identity.
Identity(PhaseGVN * phase)2687 Node* CreateExNode::Identity(PhaseGVN* phase) {
2688 if( phase->type(in(1)) == Type::TOP ) return in(1);
2689 if( phase->type(in(0)) == Type::TOP ) return in(0);
2690 // We only come from CatchProj, unless the CatchProj goes away.
2691 // If the CatchProj is optimized away, then we just carry the
2692 // exception oop through.
2693 CallNode *call = in(1)->in(0)->as_Call();
2694
2695 return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) )
2696 ? this
2697 : call->in(TypeFunc::Parms);
2698 }
2699
2700 //=============================================================================
2701 //------------------------------Value------------------------------------------
2702 // Check for being unreachable.
Value(PhaseGVN * phase) const2703 const Type* NeverBranchNode::Value(PhaseGVN* phase) const {
2704 if (!in(0) || in(0)->is_top()) return Type::TOP;
2705 return bottom_type();
2706 }
2707
2708 //------------------------------Ideal------------------------------------------
2709 // Check for no longer being part of a loop
Ideal(PhaseGVN * phase,bool can_reshape)2710 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2711 if (can_reshape && !in(0)->is_Loop()) {
2712 // Dead code elimination can sometimes delete this projection so
2713 // if it's not there, there's nothing to do.
2714 Node* fallthru = proj_out_or_null(0);
2715 if (fallthru != NULL) {
2716 phase->is_IterGVN()->replace_node(fallthru, in(0));
2717 }
2718 return phase->C->top();
2719 }
2720 return NULL;
2721 }
2722
2723 #ifndef PRODUCT
format(PhaseRegAlloc * ra_,outputStream * st) const2724 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const {
2725 st->print("%s", Name());
2726 }
2727 #endif
2728