1 /*
2 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
24
25 #include "precompiled.hpp"
26 #include "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/valuetypenode.hpp"
47 #include "utilities/vmError.hpp"
48
49 // Portions of code courtesy of Clifford Click
50
51 // Optimization - Graph Style
52
53 //=============================================================================
54 //------------------------------Value------------------------------------------
55 // Compute the type of the RegionNode.
56 const Type* RegionNode::Value(PhaseGVN* phase) const {
57 for( uint i=1; i<req(); ++i ) { // For all paths in
58 Node *n = in(i); // Get Control source
59 if( !n ) continue; // Missing inputs are TOP
60 if( phase->type(n) == Type::CONTROL )
61 return Type::CONTROL;
62 }
63 return Type::TOP; // All paths dead? Then so are we
64 }
65
66 //------------------------------Identity---------------------------------------
67 // Check for Region being Identity.
68 Node* RegionNode::Identity(PhaseGVN* phase) {
69 // Cannot have Region be an identity, even if it has only 1 input.
70 // Phi users cannot have their Region input folded away for them,
71 // since they need to select the proper data input
72 return this;
73 }
74
75 //------------------------------merge_region-----------------------------------
76 // If a Region flows into a Region, merge into one big happy merge. This is
77 // hard to do if there is stuff that has to happen
78 static Node *merge_region(RegionNode *region, PhaseGVN *phase) {
79 if( region->Opcode() != Op_Region ) // Do not do to LoopNodes
80 return NULL;
81 Node *progress = NULL; // Progress flag
82 PhaseIterGVN *igvn = phase->is_IterGVN();
83
84 uint rreq = region->req();
85 for( uint i = 1; i < rreq; i++ ) {
86 Node *r = region->in(i);
87 if( r && r->Opcode() == Op_Region && // Found a region?
88 r->in(0) == r && // Not already collapsed?
89 r != region && // Avoid stupid situations
90 r->outcnt() == 2 ) { // Self user and 'region' user only?
91 assert(!r->as_Region()->has_phi(), "no phi users");
92 if( !progress ) { // No progress
93 if (region->has_phi()) {
94 return NULL; // Only flatten if no Phi users
95 // igvn->hash_delete( phi );
96 }
97 igvn->hash_delete( region );
98 progress = region; // Making progress
99 }
100 igvn->hash_delete( r );
101
102 // Append inputs to 'r' onto 'region'
103 for( uint j = 1; j < r->req(); j++ ) {
104 // Move an input from 'r' to 'region'
105 region->add_req(r->in(j));
106 r->set_req(j, phase->C->top());
107 // Update phis of 'region'
108 //for( uint k = 0; k < max; k++ ) {
109 // Node *phi = region->out(k);
110 // if( phi->is_Phi() ) {
111 // phi->add_req(phi->in(i));
112 // }
113 //}
114
115 rreq++; // One more input to Region
116 } // Found a region to merge into Region
117 igvn->_worklist.push(r);
118 // Clobber pointer to the now dead 'r'
119 region->set_req(i, phase->C->top());
120 }
121 }
122
123 return progress;
124 }
125
126
127
128 //--------------------------------has_phi--------------------------------------
129 // Helper function: Return any PhiNode that uses this region or NULL
130 PhiNode* RegionNode::has_phi() const {
131 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
132 Node* phi = fast_out(i);
133 if (phi->is_Phi()) { // Check for Phi users
134 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
135 return phi->as_Phi(); // this one is good enough
136 }
137 }
138
139 return NULL;
140 }
141
142
143 //-----------------------------has_unique_phi----------------------------------
144 // Helper function: Return the only PhiNode that uses this region or NULL
145 PhiNode* RegionNode::has_unique_phi() const {
146 // Check that only one use is a Phi
147 PhiNode* only_phi = NULL;
148 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
149 Node* phi = fast_out(i);
150 if (phi->is_Phi()) { // Check for Phi users
151 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
152 if (only_phi == NULL) {
153 only_phi = phi->as_Phi();
154 } else {
155 return NULL; // multiple phis
156 }
157 }
158 }
159
160 return only_phi;
161 }
162
163
164 //------------------------------check_phi_clipping-----------------------------
165 // Helper function for RegionNode's identification of FP clipping
166 // Check inputs to the Phi
167 static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) {
168 min = NULL;
169 max = NULL;
170 val = NULL;
171 min_idx = 0;
172 max_idx = 0;
173 val_idx = 0;
174 uint phi_max = phi->req();
175 if( phi_max == 4 ) {
176 for( uint j = 1; j < phi_max; ++j ) {
177 Node *n = phi->in(j);
178 int opcode = n->Opcode();
179 switch( opcode ) {
180 case Op_ConI:
181 {
182 if( min == NULL ) {
183 min = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
184 min_idx = j;
185 } else {
186 max = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
187 max_idx = j;
188 if( min->get_int() > max->get_int() ) {
189 // Swap min and max
190 ConNode *temp;
191 uint temp_idx;
192 temp = min; min = max; max = temp;
193 temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx;
194 }
195 }
196 }
197 break;
198 default:
199 {
200 val = n;
201 val_idx = j;
202 }
203 break;
204 }
205 }
206 }
207 return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) );
208 }
209
210
211 //------------------------------check_if_clipping------------------------------
212 // Helper function for RegionNode's identification of FP clipping
213 // Check that inputs to Region come from two IfNodes,
214 //
215 // If
216 // False True
217 // If |
218 // False True |
219 // | | |
220 // RegionNode_inputs
221 //
222 static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) {
223 top_if = NULL;
224 bot_if = NULL;
225
226 // Check control structure above RegionNode for (if ( if ) )
227 Node *in1 = region->in(1);
228 Node *in2 = region->in(2);
229 Node *in3 = region->in(3);
230 // Check that all inputs are projections
231 if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) {
232 Node *in10 = in1->in(0);
233 Node *in20 = in2->in(0);
234 Node *in30 = in3->in(0);
235 // Check that #1 and #2 are ifTrue and ifFalse from same If
236 if( in10 != NULL && in10->is_If() &&
237 in20 != NULL && in20->is_If() &&
238 in30 != NULL && in30->is_If() && in10 == in20 &&
239 (in1->Opcode() != in2->Opcode()) ) {
240 Node *in100 = in10->in(0);
241 Node *in1000 = (in100 != NULL && in100->is_Proj()) ? in100->in(0) : NULL;
242 // Check that control for in10 comes from other branch of IF from in3
243 if( in1000 != NULL && in1000->is_If() &&
244 in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) {
245 // Control pattern checks
246 top_if = (IfNode*)in1000;
247 bot_if = (IfNode*)in10;
248 }
249 }
250 }
251
252 return (top_if != NULL);
253 }
254
255
256 //------------------------------check_convf2i_clipping-------------------------
257 // Helper function for RegionNode's identification of FP clipping
258 // Verify that the value input to the phi comes from "ConvF2I; LShift; RShift"
259 static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) {
260 convf2i = NULL;
261
262 // Check for the RShiftNode
263 Node *rshift = phi->in(idx);
264 assert( rshift, "Previous checks ensure phi input is present");
265 if( rshift->Opcode() != Op_RShiftI ) { return false; }
266
267 // Check for the LShiftNode
268 Node *lshift = rshift->in(1);
269 assert( lshift, "Previous checks ensure phi input is present");
270 if( lshift->Opcode() != Op_LShiftI ) { return false; }
271
272 // Check for the ConvF2INode
273 Node *conv = lshift->in(1);
274 if( conv->Opcode() != Op_ConvF2I ) { return false; }
275
276 // Check that shift amounts are only to get sign bits set after F2I
277 jint max_cutoff = max->get_int();
278 jint min_cutoff = min->get_int();
279 jint left_shift = lshift->in(2)->get_int();
280 jint right_shift = rshift->in(2)->get_int();
281 jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1);
282 if( left_shift != right_shift ||
283 0 > left_shift || left_shift >= BitsPerJavaInteger ||
284 max_post_shift < max_cutoff ||
285 max_post_shift < -min_cutoff ) {
286 // Shifts are necessary but current transformation eliminates them
287 return false;
288 }
289
290 // OK to return the result of ConvF2I without shifting
291 convf2i = (ConvF2INode*)conv;
292 return true;
293 }
294
295
296 //------------------------------check_compare_clipping-------------------------
297 // Helper function for RegionNode's identification of FP clipping
298 static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) {
299 Node *i1 = iff->in(1);
300 if ( !i1->is_Bool() ) { return false; }
301 BoolNode *bool1 = i1->as_Bool();
302 if( less_than && bool1->_test._test != BoolTest::le ) { return false; }
303 else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; }
304 const Node *cmpF = bool1->in(1);
305 if( cmpF->Opcode() != Op_CmpF ) { return false; }
306 // Test that the float value being compared against
307 // is equivalent to the int value used as a limit
308 Node *nodef = cmpF->in(2);
309 if( nodef->Opcode() != Op_ConF ) { return false; }
310 jfloat conf = nodef->getf();
311 jint coni = limit->get_int();
312 if( ((int)conf) != coni ) { return false; }
313 input = cmpF->in(1);
314 return true;
315 }
316
317 //------------------------------is_unreachable_region--------------------------
318 // Find if the Region node is reachable from the root.
319 bool RegionNode::is_unreachable_region(PhaseGVN *phase) const {
320 assert(req() == 2, "");
321
322 // First, cut the simple case of fallthrough region when NONE of
323 // region's phis references itself directly or through a data node.
324 uint max = outcnt();
325 uint i;
326 for (i = 0; i < max; i++) {
327 Node* phi = raw_out(i);
328 if (phi != NULL && phi->is_Phi()) {
329 assert(phase->eqv(phi->in(0), this) && phi->req() == 2, "");
330 if (phi->outcnt() == 0)
331 continue; // Safe case - no loops
332 if (phi->outcnt() == 1) {
333 Node* u = phi->raw_out(0);
334 // Skip if only one use is an other Phi or Call or Uncommon trap.
335 // It is safe to consider this case as fallthrough.
336 if (u != NULL && (u->is_Phi() || u->is_CFG()))
337 continue;
338 }
339 // Check when phi references itself directly or through an other node.
340 if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe)
341 break; // Found possible unsafe data loop.
342 }
343 }
344 if (i >= max)
345 return false; // An unsafe case was NOT found - don't need graph walk.
346
347 // Unsafe case - check if the Region node is reachable from root.
348 ResourceMark rm;
349
350 Arena *a = Thread::current()->resource_area();
351 Node_List nstack(a);
352 VectorSet visited(a);
353
354 // Mark all control nodes reachable from root outputs
355 Node *n = (Node*)phase->C->root();
356 nstack.push(n);
357 visited.set(n->_idx);
358 while (nstack.size() != 0) {
359 n = nstack.pop();
360 uint max = n->outcnt();
361 for (uint i = 0; i < max; i++) {
362 Node* m = n->raw_out(i);
363 if (m != NULL && m->is_CFG()) {
364 if (phase->eqv(m, this)) {
365 return false; // We reached the Region node - it is not dead.
366 }
367 if (!visited.test_set(m->_idx))
368 nstack.push(m);
369 }
370 }
371 }
372
373 return true; // The Region node is unreachable - it is dead.
374 }
375
376 Node* PhiNode::try_clean_mem_phi(PhaseGVN *phase) {
377 // Incremental inlining + PhaseStringOpts sometimes produce:
378 //
379 // cmpP with 1 top input
380 // |
381 // If
382 // / \
383 // IfFalse IfTrue /- Some Node
384 // \ / / /
385 // Region / /-MergeMem
386 // \---Phi
387 //
388 //
389 // It's expected by PhaseStringOpts that the Region goes away and is
390 // replaced by If's control input but because there's still a Phi,
391 // the Region stays in the graph. The top input from the cmpP is
392 // propagated forward and a subgraph that is useful goes away. The
393 // code below replaces the Phi with the MergeMem so that the Region
394 // is simplified.
395
396 if (type() == Type::MEMORY && is_diamond_phi(true)) {
397 MergeMemNode* m = NULL;
398 assert(req() == 3, "same as region");
399 Node* r = in(0);
400 for (uint i = 1; i < 3; ++i) {
401 Node *mem = in(i);
402 if (mem && mem->is_MergeMem() && r->in(i)->outcnt() == 1) {
403 // Nothing is control-dependent on path #i except the region itself.
404 m = mem->as_MergeMem();
405 uint j = 3 - i;
406 Node* other = in(j);
407 if (other && other == m->base_memory()) {
408 // m is a successor memory to other, and is not pinned inside the diamond, so push it out.
409 // This will allow the diamond to collapse completely.
410 return m;
411 }
412 }
413 }
414 }
415 return NULL;
416 }
417
418 //------------------------------Ideal------------------------------------------
419 // Return a node which is more "ideal" than the current node. Must preserve
420 // the CFG, but we can still strip out dead paths.
421 Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) {
422 if( !can_reshape && !in(0) ) return NULL; // Already degraded to a Copy
423 assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge");
424
425 // Check for RegionNode with no Phi users and both inputs come from either
426 // arm of the same IF. If found, then the control-flow split is useless.
427 bool has_phis = false;
428 if (can_reshape) { // Need DU info to check for Phi users
429 has_phis = (has_phi() != NULL); // Cache result
430 if (has_phis) {
431 PhiNode* phi = has_unique_phi();
432 if (phi != NULL) {
433 Node* m = phi->try_clean_mem_phi(phase);
434 if (m != NULL) {
435 phase->is_IterGVN()->replace_node(phi, m);
436 has_phis = false;
437 }
438 }
439 }
440
441 if (!has_phis) { // No Phi users? Nothing merging?
442 for (uint i = 1; i < req()-1; i++) {
443 Node *if1 = in(i);
444 if( !if1 ) continue;
445 Node *iff = if1->in(0);
446 if( !iff || !iff->is_If() ) continue;
447 for( uint j=i+1; j<req(); j++ ) {
448 if( in(j) && in(j)->in(0) == iff &&
449 if1->Opcode() != in(j)->Opcode() ) {
450 // Add the IF Projections to the worklist. They (and the IF itself)
451 // will be eliminated if dead.
452 phase->is_IterGVN()->add_users_to_worklist(iff);
453 set_req(i, iff->in(0));// Skip around the useless IF diamond
454 set_req(j, NULL);
455 return this; // Record progress
456 }
457 }
458 }
459 }
460 }
461
462 // Remove TOP or NULL input paths. If only 1 input path remains, this Region
463 // degrades to a copy.
464 bool add_to_worklist = false;
465 bool modified = false;
466 int cnt = 0; // Count of values merging
467 DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count
468 int del_it = 0; // The last input path we delete
469 // For all inputs...
470 for( uint i=1; i<req(); ++i ){// For all paths in
471 Node *n = in(i); // Get the input
472 if( n != NULL ) {
473 // Remove useless control copy inputs
474 if( n->is_Region() && n->as_Region()->is_copy() ) {
475 set_req(i, n->nonnull_req());
476 modified = true;
477 i--;
478 continue;
479 }
480 if( n->is_Proj() ) { // Remove useless rethrows
481 Node *call = n->in(0);
482 if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) {
483 set_req(i, call->in(0));
484 modified = true;
485 i--;
486 continue;
487 }
488 }
489 if( phase->type(n) == Type::TOP ) {
490 set_req(i, NULL); // Ignore TOP inputs
491 modified = true;
492 i--;
493 continue;
494 }
495 cnt++; // One more value merging
496
497 } else if (can_reshape) { // Else found dead path with DU info
498 PhaseIterGVN *igvn = phase->is_IterGVN();
499 del_req(i); // Yank path from self
500 del_it = i;
501 uint max = outcnt();
502 DUIterator j;
503 bool progress = true;
504 while(progress) { // Need to establish property over all users
505 progress = false;
506 for (j = outs(); has_out(j); j++) {
507 Node *n = out(j);
508 if( n->req() != req() && n->is_Phi() ) {
509 assert( n->in(0) == this, "" );
510 igvn->hash_delete(n); // Yank from hash before hacking edges
511 n->set_req_X(i,NULL,igvn);// Correct DU info
512 n->del_req(i); // Yank path from Phis
513 if( max != outcnt() ) {
514 progress = true;
515 j = refresh_out_pos(j);
516 max = outcnt();
517 }
518 }
519 }
520 }
521 add_to_worklist = true;
522 i--;
523 }
524 }
525
526 if (can_reshape && cnt == 1) {
527 // Is it dead loop?
528 // If it is LoopNopde it had 2 (+1 itself) inputs and
529 // one of them was cut. The loop is dead if it was EntryContol.
530 // Loop node may have only one input because entry path
531 // is removed in PhaseIdealLoop::Dominators().
532 assert(!this->is_Loop() || cnt_orig <= 3, "Loop node should have 3 or less inputs");
533 if ((this->is_Loop() && (del_it == LoopNode::EntryControl ||
534 (del_it == 0 && is_unreachable_region(phase)))) ||
535 (!this->is_Loop() && has_phis && is_unreachable_region(phase))) {
536 // Yes, the region will be removed during the next step below.
537 // Cut the backedge input and remove phis since no data paths left.
538 // We don't cut outputs to other nodes here since we need to put them
539 // on the worklist.
540 PhaseIterGVN *igvn = phase->is_IterGVN();
541 if (in(1)->outcnt() == 1) {
542 igvn->_worklist.push(in(1));
543 }
544 del_req(1);
545 cnt = 0;
546 assert( req() == 1, "no more inputs expected" );
547 uint max = outcnt();
548 bool progress = true;
549 Node *top = phase->C->top();
550 DUIterator j;
551 while(progress) {
552 progress = false;
553 for (j = outs(); has_out(j); j++) {
554 Node *n = out(j);
555 if( n->is_Phi() ) {
556 assert( igvn->eqv(n->in(0), this), "" );
557 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
558 // Break dead loop data path.
559 // Eagerly replace phis with top to avoid phis copies generation.
560 igvn->replace_node(n, top);
561 if( max != outcnt() ) {
562 progress = true;
563 j = refresh_out_pos(j);
564 max = outcnt();
565 }
566 }
567 }
568 }
569 add_to_worklist = true;
570 }
571 }
572 if (add_to_worklist) {
573 phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis
574 }
575
576 if( cnt <= 1 ) { // Only 1 path in?
577 set_req(0, NULL); // Null control input for region copy
578 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is.
579 // No inputs or all inputs are NULL.
580 return NULL;
581 } else if (can_reshape) { // Optimization phase - remove the node
582 PhaseIterGVN *igvn = phase->is_IterGVN();
583 // Strip mined (inner) loop is going away, remove outer loop.
584 if (is_CountedLoop() &&
585 as_Loop()->is_strip_mined()) {
586 Node* outer_sfpt = as_CountedLoop()->outer_safepoint();
587 Node* outer_out = as_CountedLoop()->outer_loop_exit();
588 if (outer_sfpt != NULL && outer_out != NULL) {
589 Node* in = outer_sfpt->in(0);
590 igvn->replace_node(outer_out, in);
591 LoopNode* outer = as_CountedLoop()->outer_loop();
592 igvn->replace_input_of(outer, LoopNode::LoopBackControl, igvn->C->top());
593 }
594 }
595 Node *parent_ctrl;
596 if( cnt == 0 ) {
597 assert( req() == 1, "no inputs expected" );
598 // During IGVN phase such region will be subsumed by TOP node
599 // so region's phis will have TOP as control node.
600 // Kill phis here to avoid it. PhiNode::is_copy() will be always false.
601 // Also set other user's input to top.
602 parent_ctrl = phase->C->top();
603 } else {
604 // The fallthrough case since we already checked dead loops above.
605 parent_ctrl = in(1);
606 assert(parent_ctrl != NULL, "Region is a copy of some non-null control");
607 assert(!igvn->eqv(parent_ctrl, this), "Close dead loop");
608 }
609 if (!add_to_worklist)
610 igvn->add_users_to_worklist(this); // Check for further allowed opts
611 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
612 Node* n = last_out(i);
613 igvn->hash_delete(n); // Remove from worklist before modifying edges
614 if( n->is_Phi() ) { // Collapse all Phis
615 // Eagerly replace phis to avoid copies generation.
616 Node* in;
617 if( cnt == 0 ) {
618 assert( n->req() == 1, "No data inputs expected" );
619 in = parent_ctrl; // replaced by top
620 } else {
621 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
622 in = n->in(1); // replaced by unique input
623 if( n->as_Phi()->is_unsafe_data_reference(in) )
624 in = phase->C->top(); // replaced by top
625 }
626 igvn->replace_node(n, in);
627 }
628 else if( n->is_Region() ) { // Update all incoming edges
629 assert( !igvn->eqv(n, this), "Must be removed from DefUse edges");
630 uint uses_found = 0;
631 for( uint k=1; k < n->req(); k++ ) {
632 if( n->in(k) == this ) {
633 n->set_req(k, parent_ctrl);
634 uses_found++;
635 }
636 }
637 if( uses_found > 1 ) { // (--i) done at the end of the loop.
638 i -= (uses_found - 1);
639 }
640 }
641 else {
642 assert( igvn->eqv(n->in(0), this), "Expect RegionNode to be control parent");
643 n->set_req(0, parent_ctrl);
644 }
645 #ifdef ASSERT
646 for( uint k=0; k < n->req(); k++ ) {
647 assert( !igvn->eqv(n->in(k), this), "All uses of RegionNode should be gone");
648 }
649 #endif
650 }
651 // Remove the RegionNode itself from DefUse info
652 igvn->remove_dead_node(this);
653 return NULL;
654 }
655 return this; // Record progress
656 }
657
658
659 // If a Region flows into a Region, merge into one big happy merge.
660 if (can_reshape) {
661 Node *m = merge_region(this, phase);
662 if (m != NULL) return m;
663 }
664
665 // Check if this region is the root of a clipping idiom on floats
666 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
667 // Check that only one use is a Phi and that it simplifies to two constants +
668 PhiNode* phi = has_unique_phi();
669 if (phi != NULL) { // One Phi user
670 // Check inputs to the Phi
671 ConNode *min;
672 ConNode *max;
673 Node *val;
674 uint min_idx;
675 uint max_idx;
676 uint val_idx;
677 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) {
678 IfNode *top_if;
679 IfNode *bot_if;
680 if( check_if_clipping( this, bot_if, top_if ) ) {
681 // Control pattern checks, now verify compares
682 Node *top_in = NULL; // value being compared against
683 Node *bot_in = NULL;
684 if( check_compare_clipping( true, bot_if, min, bot_in ) &&
685 check_compare_clipping( false, top_if, max, top_in ) ) {
686 if( bot_in == top_in ) {
687 PhaseIterGVN *gvn = phase->is_IterGVN();
688 assert( gvn != NULL, "Only had DefUse info in IterGVN");
689 // Only remaining check is that bot_in == top_in == (Phi's val + mods)
690
691 // Check for the ConvF2INode
692 ConvF2INode *convf2i;
693 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
694 convf2i->in(1) == bot_in ) {
695 // Matched pattern, including LShiftI; RShiftI, replace with integer compares
696 // max test
697 Node *cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, min ));
698 Node *boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::lt ));
699 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt ));
700 Node *if_min= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
701 Node *ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
702 // min test
703 cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, max ));
704 boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::gt ));
705 iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
706 Node *if_max= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
707 ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
708 // update input edges to region node
709 set_req_X( min_idx, if_min, gvn );
710 set_req_X( max_idx, if_max, gvn );
711 set_req_X( val_idx, ifF, gvn );
712 // remove unnecessary 'LShiftI; RShiftI' idiom
713 gvn->hash_delete(phi);
714 phi->set_req_X( val_idx, convf2i, gvn );
715 gvn->hash_find_insert(phi);
716 // Return transformed region node
717 return this;
718 }
719 }
720 }
721 }
722 }
723 }
724 }
725
726 if (can_reshape) {
727 modified |= optimize_trichotomy(phase->is_IterGVN());
728 }
729
730 return modified ? this : NULL;
731 }
732
733 //------------------------------optimize_trichotomy--------------------------
734 // Optimize nested comparisons of the following kind:
735 //
736 // int compare(int a, int b) {
737 // return (a < b) ? -1 : (a == b) ? 0 : 1;
738 // }
739 //
740 // Shape 1:
741 // if (compare(a, b) == 1) { ... } -> if (a > b) { ... }
742 //
743 // Shape 2:
744 // if (compare(a, b) == 0) { ... } -> if (a == b) { ... }
745 //
746 // Above code leads to the following IR shapes where both Ifs compare the
747 // same value and two out of three region inputs idx1 and idx2 map to
748 // the same value and control flow.
749 //
750 // (1) If (2) If
751 // / \ / \
752 // Proj Proj Proj Proj
753 // | \ | \
754 // | If | If If
755 // | / \ | / \ / \
756 // | Proj Proj | Proj Proj ==> Proj Proj
757 // | / / \ | / | /
758 // Region / \ | / | /
759 // \ / \ | / | /
760 // Region Region Region
761 //
762 // The method returns true if 'this' is modified and false otherwise.
763 bool RegionNode::optimize_trichotomy(PhaseIterGVN* igvn) {
764 int idx1 = 1, idx2 = 2;
765 Node* region = NULL;
766 if (req() == 3 && in(1) != NULL && in(2) != NULL) {
767 // Shape 1: Check if one of the inputs is a region that merges two control
768 // inputs and has no other users (especially no Phi users).
769 region = in(1)->isa_Region() ? in(1) : in(2)->isa_Region();
770 if (region == NULL || region->outcnt() != 2 || region->req() != 3) {
771 return false; // No suitable region input found
772 }
773 } else if (req() == 4) {
774 // Shape 2: Check if two control inputs map to the same value of the unique phi
775 // user and treat these as if they would come from another region (shape (1)).
776 PhiNode* phi = has_unique_phi();
777 if (phi == NULL) {
778 return false; // No unique phi user
779 }
780 if (phi->in(idx1) != phi->in(idx2)) {
781 idx2 = 3;
782 if (phi->in(idx1) != phi->in(idx2)) {
783 idx1 = 2;
784 if (phi->in(idx1) != phi->in(idx2)) {
785 return false; // No equal phi inputs found
786 }
787 }
788 }
789 assert(phi->in(idx1) == phi->in(idx2), "must be"); // Region is merging same value
790 region = this;
791 }
792 if (region == NULL || region->in(idx1) == NULL || region->in(idx2) == NULL) {
793 return false; // Region does not merge two control inputs
794 }
795 // At this point we know that region->in(idx1) and region->(idx2) map to the same
796 // value and control flow. Now search for ifs that feed into these region inputs.
797 ProjNode* proj1 = region->in(idx1)->isa_Proj();
798 ProjNode* proj2 = region->in(idx2)->isa_Proj();
799 if (proj1 == NULL || proj1->outcnt() != 1 ||
800 proj2 == NULL || proj2->outcnt() != 1) {
801 return false; // No projection inputs with region as unique user found
802 }
803 assert(proj1 != proj2, "should be different projections");
804 IfNode* iff1 = proj1->in(0)->isa_If();
805 IfNode* iff2 = proj2->in(0)->isa_If();
806 if (iff1 == NULL || iff1->outcnt() != 2 ||
807 iff2 == NULL || iff2->outcnt() != 2) {
808 return false; // No ifs found
809 }
810 if (iff1 == iff2) {
811 igvn->add_users_to_worklist(iff1); // Make sure dead if is eliminated
812 igvn->replace_input_of(region, idx1, iff1->in(0));
813 igvn->replace_input_of(region, idx2, igvn->C->top());
814 return (region == this); // Remove useless if (both projections map to the same control/value)
815 }
816 BoolNode* bol1 = iff1->in(1)->isa_Bool();
817 BoolNode* bol2 = iff2->in(1)->isa_Bool();
818 if (bol1 == NULL || bol2 == NULL) {
819 return false; // No bool inputs found
820 }
821 Node* cmp1 = bol1->in(1);
822 Node* cmp2 = bol2->in(1);
823 bool commute = false;
824 if (!cmp1->is_Cmp() || !cmp2->is_Cmp()) {
825 return false; // No comparison
826 } else if (cmp1->Opcode() == Op_CmpF || cmp1->Opcode() == Op_CmpD ||
827 cmp2->Opcode() == Op_CmpF || cmp2->Opcode() == Op_CmpD ||
828 cmp1->Opcode() == Op_CmpP || cmp1->Opcode() == Op_CmpN ||
829 cmp2->Opcode() == Op_CmpP || cmp2->Opcode() == Op_CmpN) {
830 // Floats and pointers don't exactly obey trichotomy. To be on the safe side, don't transform their tests.
831 return false;
832 } else if (cmp1 != cmp2) {
833 if (cmp1->in(1) == cmp2->in(2) &&
834 cmp1->in(2) == cmp2->in(1)) {
835 commute = true; // Same but swapped inputs, commute the test
836 } else {
837 return false; // Ifs are not comparing the same values
838 }
839 }
840 proj1 = proj1->other_if_proj();
841 proj2 = proj2->other_if_proj();
842 if (!((proj1->unique_ctrl_out() == iff2 &&
843 proj2->unique_ctrl_out() == this) ||
844 (proj2->unique_ctrl_out() == iff1 &&
845 proj1->unique_ctrl_out() == this))) {
846 return false; // Ifs are not connected through other projs
847 }
848 // Found 'iff -> proj -> iff -> proj -> this' shape where all other projs are merged
849 // through 'region' and map to the same value. Merge the boolean tests and replace
850 // the ifs by a single comparison.
851 BoolTest test1 = (proj1->_con == 1) ? bol1->_test : bol1->_test.negate();
852 BoolTest test2 = (proj2->_con == 1) ? bol2->_test : bol2->_test.negate();
853 test1 = commute ? test1.commute() : test1;
854 // After possibly commuting test1, if we can merge test1 & test2, then proj2/iff2/bol2 are the nodes to refine.
855 BoolTest::mask res = test1.merge(test2);
856 if (res == BoolTest::illegal) {
857 return false; // Unable to merge tests
858 }
859 // Adjust iff1 to always pass (only iff2 will remain)
860 igvn->replace_input_of(iff1, 1, igvn->intcon(proj1->_con));
861 if (res == BoolTest::never) {
862 // Merged test is always false, adjust iff2 to always fail
863 igvn->replace_input_of(iff2, 1, igvn->intcon(1 - proj2->_con));
864 } else {
865 // Replace bool input of iff2 with merged test
866 BoolNode* new_bol = new BoolNode(bol2->in(1), res);
867 igvn->replace_input_of(iff2, 1, igvn->transform((proj2->_con == 1) ? new_bol : new_bol->negate(igvn)));
868 }
869 return false;
870 }
871
872 const RegMask &RegionNode::out_RegMask() const {
873 return RegMask::Empty;
874 }
875
876 // Find the one non-null required input. RegionNode only
877 Node *Node::nonnull_req() const {
878 assert( is_Region(), "" );
879 for( uint i = 1; i < _cnt; i++ )
880 if( in(i) )
881 return in(i);
882 ShouldNotReachHere();
883 return NULL;
884 }
885
886
887 //=============================================================================
888 // note that these functions assume that the _adr_type field is flattened
889 uint PhiNode::hash() const {
890 const Type* at = _adr_type;
891 return TypeNode::hash() + (at ? at->hash() : 0);
892 }
893 uint PhiNode::cmp( const Node &n ) const {
894 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
895 }
896 static inline
897 const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
898 if (at == NULL || at == TypePtr::BOTTOM) return at;
899 return Compile::current()->alias_type(at)->adr_type();
900 }
901
902 //----------------------------make---------------------------------------------
903 // create a new phi with edges matching r and set (initially) to x
904 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
905 uint preds = r->req(); // Number of predecessor paths
906 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at");
907 PhiNode* p = new PhiNode(r, t, at);
908 for (uint j = 1; j < preds; j++) {
909 // Fill in all inputs, except those which the region does not yet have
910 if (r->in(j) != NULL)
911 p->init_req(j, x);
912 }
913 return p;
914 }
915 PhiNode* PhiNode::make(Node* r, Node* x) {
916 const Type* t = x->bottom_type();
917 const TypePtr* at = NULL;
918 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
919 return make(r, x, t, at);
920 }
921 PhiNode* PhiNode::make_blank(Node* r, Node* x) {
922 const Type* t = x->bottom_type();
923 const TypePtr* at = NULL;
924 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
925 return new PhiNode(r, t, at);
926 }
927
928
929 //------------------------slice_memory-----------------------------------------
930 // create a new phi with narrowed memory type
931 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
932 PhiNode* mem = (PhiNode*) clone();
933 *(const TypePtr**)&mem->_adr_type = adr_type;
934 // convert self-loops, or else we get a bad graph
935 for (uint i = 1; i < req(); i++) {
936 if ((const Node*)in(i) == this) mem->set_req(i, mem);
937 }
938 mem->verify_adr_type();
939 return mem;
940 }
941
942 //------------------------split_out_instance-----------------------------------
943 // Split out an instance type from a bottom phi.
944 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const {
945 const TypeOopPtr *t_oop = at->isa_oopptr();
946 assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr");
947 const TypePtr *t = adr_type();
948 assert(type() == Type::MEMORY &&
949 (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
950 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
951 t->is_oopptr()->cast_to_exactness(true)
952 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
953 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop),
954 "bottom or raw memory required");
955
956 // Check if an appropriate node already exists.
957 Node *region = in(0);
958 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) {
959 Node* use = region->fast_out(k);
960 if( use->is_Phi()) {
961 PhiNode *phi2 = use->as_Phi();
962 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) {
963 return phi2;
964 }
965 }
966 }
967 Compile *C = igvn->C;
968 Arena *a = Thread::current()->resource_area();
969 Node_Array node_map = new Node_Array(a);
970 Node_Stack stack(a, C->live_nodes() >> 4);
971 PhiNode *nphi = slice_memory(at);
972 igvn->register_new_node_with_optimizer( nphi );
973 node_map.map(_idx, nphi);
974 stack.push((Node *)this, 1);
975 while(!stack.is_empty()) {
976 PhiNode *ophi = stack.node()->as_Phi();
977 uint i = stack.index();
978 assert(i >= 1, "not control edge");
979 stack.pop();
980 nphi = node_map[ophi->_idx]->as_Phi();
981 for (; i < ophi->req(); i++) {
982 Node *in = ophi->in(i);
983 if (in == NULL || igvn->type(in) == Type::TOP)
984 continue;
985 Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, NULL, igvn);
986 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL;
987 if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) {
988 opt = node_map[optphi->_idx];
989 if (opt == NULL) {
990 stack.push(ophi, i);
991 nphi = optphi->slice_memory(at);
992 igvn->register_new_node_with_optimizer( nphi );
993 node_map.map(optphi->_idx, nphi);
994 ophi = optphi;
995 i = 0; // will get incremented at top of loop
996 continue;
997 }
998 }
999 nphi->set_req(i, opt);
1000 }
1001 }
1002 return nphi;
1003 }
1004
1005 //------------------------verify_adr_type--------------------------------------
1006 #ifdef ASSERT
1007 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
1008 if (visited.test_set(_idx)) return; //already visited
1009
1010 // recheck constructor invariants:
1011 verify_adr_type(false);
1012
1013 // recheck local phi/phi consistency:
1014 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
1015 "adr_type must be consistent across phi nest");
1016
1017 // walk around
1018 for (uint i = 1; i < req(); i++) {
1019 Node* n = in(i);
1020 if (n == NULL) continue;
1021 const Node* np = in(i);
1022 if (np->is_Phi()) {
1023 np->as_Phi()->verify_adr_type(visited, at);
1024 } else if (n->bottom_type() == Type::TOP
1025 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
1026 // ignore top inputs
1027 } else {
1028 const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
1029 // recheck phi/non-phi consistency at leaves:
1030 assert((nat != NULL) == (at != NULL), "");
1031 assert(nat == at || nat == TypePtr::BOTTOM,
1032 "adr_type must be consistent at leaves of phi nest");
1033 }
1034 }
1035 }
1036
1037 // Verify a whole nest of phis rooted at this one.
1038 void PhiNode::verify_adr_type(bool recursive) const {
1039 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
1040 if (Node::in_dump()) return; // muzzle asserts when printing
1041
1042 assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only");
1043
1044 if (!VerifyAliases) return; // verify thoroughly only if requested
1045
1046 assert(_adr_type == flatten_phi_adr_type(_adr_type),
1047 "Phi::adr_type must be pre-normalized");
1048
1049 if (recursive) {
1050 VectorSet visited(Thread::current()->resource_area());
1051 verify_adr_type(visited, _adr_type);
1052 }
1053 }
1054 #endif
1055
1056
1057 //------------------------------Value------------------------------------------
1058 // Compute the type of the PhiNode
1059 const Type* PhiNode::Value(PhaseGVN* phase) const {
1060 Node *r = in(0); // RegionNode
1061 if( !r ) // Copy or dead
1062 return in(1) ? phase->type(in(1)) : Type::TOP;
1063
1064 // Note: During parsing, phis are often transformed before their regions.
1065 // This means we have to use type_or_null to defend against untyped regions.
1066 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1067 return Type::TOP;
1068
1069 // Check for trip-counted loop. If so, be smarter.
1070 CountedLoopNode* l = r->is_CountedLoop() ? r->as_CountedLoop() : NULL;
1071 if (l && ((const Node*)l->phi() == this)) { // Trip counted loop!
1072 // protect against init_trip() or limit() returning NULL
1073 if (l->can_be_counted_loop(phase)) {
1074 const Node *init = l->init_trip();
1075 const Node *limit = l->limit();
1076 const Node* stride = l->stride();
1077 if (init != NULL && limit != NULL && stride != NULL) {
1078 const TypeInt* lo = phase->type(init)->isa_int();
1079 const TypeInt* hi = phase->type(limit)->isa_int();
1080 const TypeInt* stride_t = phase->type(stride)->isa_int();
1081 if (lo != NULL && hi != NULL && stride_t != NULL) { // Dying loops might have TOP here
1082 assert(stride_t->_hi >= stride_t->_lo, "bad stride type");
1083 BoolTest::mask bt = l->loopexit()->test_trip();
1084 // If the loop exit condition is "not equal", the condition
1085 // would not trigger if init > limit (if stride > 0) or if
1086 // init < limit if (stride > 0) so we can't deduce bounds
1087 // for the iv from the exit condition.
1088 if (bt != BoolTest::ne) {
1089 if (stride_t->_hi < 0) { // Down-counter loop
1090 swap(lo, hi);
1091 return TypeInt::make(MIN2(lo->_lo, hi->_lo) , hi->_hi, 3);
1092 } else if (stride_t->_lo >= 0) {
1093 return TypeInt::make(lo->_lo, MAX2(lo->_hi, hi->_hi), 3);
1094 }
1095 }
1096 }
1097 }
1098 } else if (l->in(LoopNode::LoopBackControl) != NULL &&
1099 in(LoopNode::EntryControl) != NULL &&
1100 phase->type(l->in(LoopNode::LoopBackControl)) == Type::TOP) {
1101 // During CCP, if we saturate the type of a counted loop's Phi
1102 // before the special code for counted loop above has a chance
1103 // to run (that is as long as the type of the backedge's control
1104 // is top), we might end up with non monotonic types
1105 return phase->type(in(LoopNode::EntryControl))->filter_speculative(_type);
1106 }
1107 }
1108
1109 // Until we have harmony between classes and interfaces in the type
1110 // lattice, we must tread carefully around phis which implicitly
1111 // convert the one to the other.
1112 const TypePtr* ttp = _type->make_ptr();
1113 const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL;
1114 const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_klassptr() : NULL;
1115 bool is_intf = false;
1116 if (ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
1117 is_intf = true;
1118 } else if (ttkp != NULL && ttkp->is_loaded() && ttkp->klass()->is_interface()) {
1119 is_intf = true;
1120 }
1121
1122 // Default case: merge all inputs
1123 const Type *t = Type::TOP; // Merged type starting value
1124 for (uint i = 1; i < req(); ++i) {// For all paths in
1125 // Reachable control path?
1126 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
1127 const Type* ti = phase->type(in(i));
1128 // We assume that each input of an interface-valued Phi is a true
1129 // subtype of that interface. This might not be true of the meet
1130 // of all the input types. The lattice is not distributive in
1131 // such cases. Ward off asserts in type.cpp by refusing to do
1132 // meets between interfaces and proper classes.
1133 const TypePtr* tip = ti->make_ptr();
1134 const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL;
1135 if (tiip) {
1136 bool ti_is_intf = false;
1137 ciKlass* k = tiip->klass();
1138 if (k->is_loaded() && k->is_interface())
1139 ti_is_intf = true;
1140 if (is_intf != ti_is_intf)
1141 { t = _type; break; }
1142 }
1143 t = t->meet_speculative(ti);
1144 }
1145 }
1146
1147 // The worst-case type (from ciTypeFlow) should be consistent with "t".
1148 // That is, we expect that "t->higher_equal(_type)" holds true.
1149 // There are various exceptions:
1150 // - Inputs which are phis might in fact be widened unnecessarily.
1151 // For example, an input might be a widened int while the phi is a short.
1152 // - Inputs might be BotPtrs but this phi is dependent on a null check,
1153 // and postCCP has removed the cast which encodes the result of the check.
1154 // - The type of this phi is an interface, and the inputs are classes.
1155 // - Value calls on inputs might produce fuzzy results.
1156 // (Occurrences of this case suggest improvements to Value methods.)
1157 //
1158 // It is not possible to see Type::BOTTOM values as phi inputs,
1159 // because the ciTypeFlow pre-pass produces verifier-quality types.
1160 const Type* ft = t->filter_speculative(_type); // Worst case type
1161
1162 #ifdef ASSERT
1163 // The following logic has been moved into TypeOopPtr::filter.
1164 const Type* jt = t->join_speculative(_type);
1165 if (jt->empty()) { // Emptied out???
1166
1167 // Check for evil case of 't' being a class and '_type' expecting an
1168 // interface. This can happen because the bytecodes do not contain
1169 // enough type info to distinguish a Java-level interface variable
1170 // from a Java-level object variable. If we meet 2 classes which
1171 // both implement interface I, but their meet is at 'j/l/O' which
1172 // doesn't implement I, we have no way to tell if the result should
1173 // be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows
1174 // into a Phi which "knows" it's an Interface type we'll have to
1175 // uplift the type.
1176 if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
1177 assert(ft == _type, ""); // Uplift to interface
1178 } else if (!t->empty() && ttkp != NULL && ttkp->is_loaded() && ttkp->klass()->is_interface()) {
1179 assert(ft == _type, ""); // Uplift to interface
1180 } else {
1181 // We also have to handle 'evil cases' of interface- vs. class-arrays
1182 Type::get_arrays_base_elements(jt, _type, NULL, &ttip);
1183 if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
1184 assert(ft == _type, ""); // Uplift to array of interface
1185 } else {
1186 // Otherwise it's something stupid like non-overlapping int ranges
1187 // found on dying counted loops.
1188 assert(ft == Type::TOP, ""); // Canonical empty value
1189 }
1190 }
1191 }
1192
1193 else {
1194
1195 // If we have an interface-typed Phi and we narrow to a class type, the join
1196 // should report back the class. However, if we have a J/L/Object
1197 // class-typed Phi and an interface flows in, it's possible that the meet &
1198 // join report an interface back out. This isn't possible but happens
1199 // because the type system doesn't interact well with interfaces.
1200 const TypePtr *jtp = jt->make_ptr();
1201 const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL;
1202 const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_klassptr() : NULL;
1203 if( jtip && ttip ) {
1204 if( jtip->is_loaded() && jtip->klass()->is_interface() &&
1205 ttip->is_loaded() && !ttip->klass()->is_interface() ) {
1206 assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) ||
1207 ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), "");
1208 jt = ft;
1209 }
1210 }
1211 if( jtkp && ttkp ) {
1212 if( jtkp->is_loaded() && jtkp->klass()->is_interface() &&
1213 !jtkp->klass_is_exact() && // Keep exact interface klass (6894807)
1214 ttkp->is_loaded() && !ttkp->klass()->is_interface() ) {
1215 assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) ||
1216 ft->isa_narrowklass() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), "");
1217 jt = ft;
1218 }
1219 }
1220 if (jt != ft && jt->base() == ft->base()) {
1221 if (jt->isa_int() &&
1222 jt->is_int()->_lo == ft->is_int()->_lo &&
1223 jt->is_int()->_hi == ft->is_int()->_hi)
1224 jt = ft;
1225 if (jt->isa_long() &&
1226 jt->is_long()->_lo == ft->is_long()->_lo &&
1227 jt->is_long()->_hi == ft->is_long()->_hi)
1228 jt = ft;
1229 }
1230 if (jt != ft) {
1231 tty->print("merge type: "); t->dump(); tty->cr();
1232 tty->print("kill type: "); _type->dump(); tty->cr();
1233 tty->print("join type: "); jt->dump(); tty->cr();
1234 tty->print("filter type: "); ft->dump(); tty->cr();
1235 }
1236 assert(jt == ft, "");
1237 }
1238 #endif //ASSERT
1239
1240 // Deal with conversion problems found in data loops.
1241 ft = phase->saturate(ft, phase->type_or_null(this), _type);
1242
1243 return ft;
1244 }
1245
1246
1247 //------------------------------is_diamond_phi---------------------------------
1248 // Does this Phi represent a simple well-shaped diamond merge? Return the
1249 // index of the true path or 0 otherwise.
1250 // If check_control_only is true, do not inspect the If node at the
1251 // top, and return -1 (not an edge number) on success.
1252 int PhiNode::is_diamond_phi(bool check_control_only) const {
1253 // Check for a 2-path merge
1254 Node *region = in(0);
1255 if( !region ) return 0;
1256 if( region->req() != 3 ) return 0;
1257 if( req() != 3 ) return 0;
1258 // Check that both paths come from the same If
1259 Node *ifp1 = region->in(1);
1260 Node *ifp2 = region->in(2);
1261 if( !ifp1 || !ifp2 ) return 0;
1262 Node *iff = ifp1->in(0);
1263 if( !iff || !iff->is_If() ) return 0;
1264 if( iff != ifp2->in(0) ) return 0;
1265 if (check_control_only) return -1;
1266 // Check for a proper bool/cmp
1267 const Node *b = iff->in(1);
1268 if( !b->is_Bool() ) return 0;
1269 const Node *cmp = b->in(1);
1270 if( !cmp->is_Cmp() ) return 0;
1271
1272 // Check for branching opposite expected
1273 if( ifp2->Opcode() == Op_IfTrue ) {
1274 assert( ifp1->Opcode() == Op_IfFalse, "" );
1275 return 2;
1276 } else {
1277 assert( ifp1->Opcode() == Op_IfTrue, "" );
1278 return 1;
1279 }
1280 }
1281
1282 //----------------------------check_cmove_id-----------------------------------
1283 // Check for CMove'ing a constant after comparing against the constant.
1284 // Happens all the time now, since if we compare equality vs a constant in
1285 // the parser, we "know" the variable is constant on one path and we force
1286 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
1287 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more
1288 // general in that we don't need constants. Since CMove's are only inserted
1289 // in very special circumstances, we do it here on generic Phi's.
1290 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
1291 assert(true_path !=0, "only diamond shape graph expected");
1292
1293 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1294 // phi->region->if_proj->ifnode->bool->cmp
1295 Node* region = in(0);
1296 Node* iff = region->in(1)->in(0);
1297 BoolNode* b = iff->in(1)->as_Bool();
1298 Node* cmp = b->in(1);
1299 Node* tval = in(true_path);
1300 Node* fval = in(3-true_path);
1301 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
1302 if (id == NULL)
1303 return NULL;
1304
1305 // Either value might be a cast that depends on a branch of 'iff'.
1306 // Since the 'id' value will float free of the diamond, either
1307 // decast or return failure.
1308 Node* ctl = id->in(0);
1309 if (ctl != NULL && ctl->in(0) == iff) {
1310 if (id->is_ConstraintCast()) {
1311 return id->in(1);
1312 } else {
1313 // Don't know how to disentangle this value.
1314 return NULL;
1315 }
1316 }
1317
1318 return id;
1319 }
1320
1321 //------------------------------Identity---------------------------------------
1322 // Check for Region being Identity.
1323 Node* PhiNode::Identity(PhaseGVN* phase) {
1324 // Check for no merging going on
1325 // (There used to be special-case code here when this->region->is_Loop.
1326 // It would check for a tributary phi on the backedge that the main phi
1327 // trivially, perhaps with a single cast. The unique_input method
1328 // does all this and more, by reducing such tributaries to 'this'.)
1329 Node* uin = unique_input(phase, false);
1330 if (uin != NULL) {
1331 return uin;
1332 }
1333
1334 int true_path = is_diamond_phi();
1335 if (true_path != 0) {
1336 Node* id = is_cmove_id(phase, true_path);
1337 if (id != NULL) return id;
1338 }
1339
1340 if (phase->is_IterGVN()) {
1341 Node* m = try_clean_mem_phi(phase);
1342 if (m != NULL) {
1343 return m;
1344 }
1345 }
1346
1347
1348 return this; // No identity
1349 }
1350
1351 //-----------------------------unique_input------------------------------------
1352 // Find the unique value, discounting top, self-loops, and casts.
1353 // Return top if there are no inputs, and self if there are multiple.
1354 Node* PhiNode::unique_input(PhaseTransform* phase, bool uncast) {
1355 // 1) One unique direct input,
1356 // or if uncast is true:
1357 // 2) some of the inputs have an intervening ConstraintCast
1358 // 3) an input is a self loop
1359 //
1360 // 1) input or 2) input or 3) input __
1361 // / \ / \ \ / \
1362 // \ / | cast phi cast
1363 // phi \ / / \ /
1364 // phi / --
1365
1366 Node* r = in(0); // RegionNode
1367 if (r == NULL) return in(1); // Already degraded to a Copy
1368 Node* input = NULL; // The unique direct input (maybe uncasted = ConstraintCasts removed)
1369
1370 for (uint i = 1, cnt = req(); i < cnt; ++i) {
1371 Node* rc = r->in(i);
1372 if (rc == NULL || phase->type(rc) == Type::TOP)
1373 continue; // ignore unreachable control path
1374 Node* n = in(i);
1375 if (n == NULL)
1376 continue;
1377 Node* un = n;
1378 if (uncast) {
1379 #ifdef ASSERT
1380 Node* m = un->uncast();
1381 #endif
1382 while (un != NULL && un->req() == 2 && un->is_ConstraintCast()) {
1383 Node* next = un->in(1);
1384 if (phase->type(next)->isa_rawptr() && phase->type(un)->isa_oopptr()) {
1385 // risk exposing raw ptr at safepoint
1386 break;
1387 }
1388 un = next;
1389 }
1390 assert(m == un || un->in(1) == m, "Only expected at CheckCastPP from allocation");
1391 }
1392 if (un == NULL || un == this || phase->type(un) == Type::TOP) {
1393 continue; // ignore if top, or in(i) and "this" are in a data cycle
1394 }
1395 // Check for a unique input (maybe uncasted)
1396 if (input == NULL) {
1397 input = un;
1398 } else if (input != un) {
1399 input = NodeSentinel; // no unique input
1400 }
1401 }
1402 if (input == NULL) {
1403 return phase->C->top(); // no inputs
1404 }
1405
1406 if (input != NodeSentinel) {
1407 return input; // one unique direct input
1408 }
1409
1410 // Nothing.
1411 return NULL;
1412 }
1413
1414 //------------------------------is_x2logic-------------------------------------
1415 // Check for simple convert-to-boolean pattern
1416 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
1417 // Convert Phi to an ConvIB.
1418 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
1419 assert(true_path !=0, "only diamond shape graph expected");
1420 // Convert the true/false index into an expected 0/1 return.
1421 // Map 2->0 and 1->1.
1422 int flipped = 2-true_path;
1423
1424 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1425 // phi->region->if_proj->ifnode->bool->cmp
1426 Node *region = phi->in(0);
1427 Node *iff = region->in(1)->in(0);
1428 BoolNode *b = (BoolNode*)iff->in(1);
1429 const CmpNode *cmp = (CmpNode*)b->in(1);
1430
1431 Node *zero = phi->in(1);
1432 Node *one = phi->in(2);
1433 const Type *tzero = phase->type( zero );
1434 const Type *tone = phase->type( one );
1435
1436 // Check for compare vs 0
1437 const Type *tcmp = phase->type(cmp->in(2));
1438 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
1439 // Allow cmp-vs-1 if the other input is bounded by 0-1
1440 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
1441 return NULL;
1442 flipped = 1-flipped; // Test is vs 1 instead of 0!
1443 }
1444
1445 // Check for setting zero/one opposite expected
1446 if( tzero == TypeInt::ZERO ) {
1447 if( tone == TypeInt::ONE ) {
1448 } else return NULL;
1449 } else if( tzero == TypeInt::ONE ) {
1450 if( tone == TypeInt::ZERO ) {
1451 flipped = 1-flipped;
1452 } else return NULL;
1453 } else return NULL;
1454
1455 // Check for boolean test backwards
1456 if( b->_test._test == BoolTest::ne ) {
1457 } else if( b->_test._test == BoolTest::eq ) {
1458 flipped = 1-flipped;
1459 } else return NULL;
1460
1461 // Build int->bool conversion
1462 Node *in1 = cmp->in(1);
1463 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1464 in1 = bs->step_over_gc_barrier(in1);
1465 Node *n = new Conv2BNode(in1);
1466 if( flipped )
1467 n = new XorINode( phase->transform(n), phase->intcon(1) );
1468
1469 return n;
1470 }
1471
1472 //------------------------------is_cond_add------------------------------------
1473 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;"
1474 // To be profitable the control flow has to disappear; there can be no other
1475 // values merging here. We replace the test-and-branch with:
1476 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by
1477 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
1478 // Then convert Y to 0-or-Y and finally add.
1479 // This is a key transform for SpecJava _201_compress.
1480 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
1481 assert(true_path !=0, "only diamond shape graph expected");
1482
1483 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1484 // phi->region->if_proj->ifnode->bool->cmp
1485 RegionNode *region = (RegionNode*)phi->in(0);
1486 Node *iff = region->in(1)->in(0);
1487 BoolNode* b = iff->in(1)->as_Bool();
1488 const CmpNode *cmp = (CmpNode*)b->in(1);
1489
1490 // Make sure only merging this one phi here
1491 if (region->has_unique_phi() != phi) return NULL;
1492
1493 // Make sure each arm of the diamond has exactly one output, which we assume
1494 // is the region. Otherwise, the control flow won't disappear.
1495 if (region->in(1)->outcnt() != 1) return NULL;
1496 if (region->in(2)->outcnt() != 1) return NULL;
1497
1498 // Check for "(P < Q)" of type signed int
1499 if (b->_test._test != BoolTest::lt) return NULL;
1500 if (cmp->Opcode() != Op_CmpI) return NULL;
1501
1502 Node *p = cmp->in(1);
1503 Node *q = cmp->in(2);
1504 Node *n1 = phi->in( true_path);
1505 Node *n2 = phi->in(3-true_path);
1506
1507 int op = n1->Opcode();
1508 if( op != Op_AddI // Need zero as additive identity
1509 /*&&op != Op_SubI &&
1510 op != Op_AddP &&
1511 op != Op_XorI &&
1512 op != Op_OrI*/ )
1513 return NULL;
1514
1515 Node *x = n2;
1516 Node *y = NULL;
1517 if( x == n1->in(1) ) {
1518 y = n1->in(2);
1519 } else if( x == n1->in(2) ) {
1520 y = n1->in(1);
1521 } else return NULL;
1522
1523 // Not so profitable if compare and add are constants
1524 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
1525 return NULL;
1526
1527 Node *cmplt = phase->transform( new CmpLTMaskNode(p,q) );
1528 Node *j_and = phase->transform( new AndINode(cmplt,y) );
1529 return new AddINode(j_and,x);
1530 }
1531
1532 //------------------------------is_absolute------------------------------------
1533 // Check for absolute value.
1534 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
1535 assert(true_path !=0, "only diamond shape graph expected");
1536
1537 int cmp_zero_idx = 0; // Index of compare input where to look for zero
1538 int phi_x_idx = 0; // Index of phi input where to find naked x
1539
1540 // ABS ends with the merge of 2 control flow paths.
1541 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
1542 int false_path = 3 - true_path;
1543
1544 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1545 // phi->region->if_proj->ifnode->bool->cmp
1546 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
1547
1548 // Check bool sense
1549 switch( bol->_test._test ) {
1550 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break;
1551 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1552 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1553 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
1554 default: return NULL; break;
1555 }
1556
1557 // Test is next
1558 Node *cmp = bol->in(1);
1559 const Type *tzero = NULL;
1560 switch( cmp->Opcode() ) {
1561 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS
1562 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS
1563 default: return NULL;
1564 }
1565
1566 // Find zero input of compare; the other input is being abs'd
1567 Node *x = NULL;
1568 bool flip = false;
1569 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
1570 x = cmp->in(3 - cmp_zero_idx);
1571 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
1572 // The test is inverted, we should invert the result...
1573 x = cmp->in(cmp_zero_idx);
1574 flip = true;
1575 } else {
1576 return NULL;
1577 }
1578
1579 // Next get the 2 pieces being selected, one is the original value
1580 // and the other is the negated value.
1581 if( phi_root->in(phi_x_idx) != x ) return NULL;
1582
1583 // Check other phi input for subtract node
1584 Node *sub = phi_root->in(3 - phi_x_idx);
1585
1586 // Allow only Sub(0,X) and fail out for all others; Neg is not OK
1587 if( tzero == TypeF::ZERO ) {
1588 if( sub->Opcode() != Op_SubF ||
1589 sub->in(2) != x ||
1590 phase->type(sub->in(1)) != tzero ) return NULL;
1591 x = new AbsFNode(x);
1592 if (flip) {
1593 x = new SubFNode(sub->in(1), phase->transform(x));
1594 }
1595 } else {
1596 if( sub->Opcode() != Op_SubD ||
1597 sub->in(2) != x ||
1598 phase->type(sub->in(1)) != tzero ) return NULL;
1599 x = new AbsDNode(x);
1600 if (flip) {
1601 x = new SubDNode(sub->in(1), phase->transform(x));
1602 }
1603 }
1604
1605 return x;
1606 }
1607
1608 //------------------------------split_once-------------------------------------
1609 // Helper for split_flow_path
1610 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
1611 igvn->hash_delete(n); // Remove from hash before hacking edges
1612
1613 uint j = 1;
1614 for (uint i = phi->req()-1; i > 0; i--) {
1615 if (phi->in(i) == val) { // Found a path with val?
1616 // Add to NEW Region/Phi, no DU info
1617 newn->set_req( j++, n->in(i) );
1618 // Remove from OLD Region/Phi
1619 n->del_req(i);
1620 }
1621 }
1622
1623 // Register the new node but do not transform it. Cannot transform until the
1624 // entire Region/Phi conglomerate has been hacked as a single huge transform.
1625 igvn->register_new_node_with_optimizer( newn );
1626
1627 // Now I can point to the new node.
1628 n->add_req(newn);
1629 igvn->_worklist.push(n);
1630 }
1631
1632 //------------------------------split_flow_path--------------------------------
1633 // Check for merging identical values and split flow paths
1634 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) {
1635 BasicType bt = phi->type()->basic_type();
1636 if( bt == T_ILLEGAL || type2size[bt] <= 0 )
1637 return NULL; // Bail out on funny non-value stuff
1638 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a
1639 return NULL; // third unequal input to be worth doing
1640
1641 // Scan for a constant
1642 uint i;
1643 for( i = 1; i < phi->req()-1; i++ ) {
1644 Node *n = phi->in(i);
1645 if( !n ) return NULL;
1646 if( phase->type(n) == Type::TOP ) return NULL;
1647 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN || n->Opcode() == Op_ConNKlass )
1648 break;
1649 }
1650 if( i >= phi->req() ) // Only split for constants
1651 return NULL;
1652
1653 Node *val = phi->in(i); // Constant to split for
1654 uint hit = 0; // Number of times it occurs
1655 Node *r = phi->region();
1656
1657 for( ; i < phi->req(); i++ ){ // Count occurrences of constant
1658 Node *n = phi->in(i);
1659 if( !n ) return NULL;
1660 if( phase->type(n) == Type::TOP ) return NULL;
1661 if( phi->in(i) == val ) {
1662 hit++;
1663 if (PhaseIdealLoop::find_predicate(r->in(i)) != NULL) {
1664 return NULL; // don't split loop entry path
1665 }
1666 }
1667 }
1668
1669 if( hit <= 1 || // Make sure we find 2 or more
1670 hit == phi->req()-1 ) // and not ALL the same value
1671 return NULL;
1672
1673 // Now start splitting out the flow paths that merge the same value.
1674 // Split first the RegionNode.
1675 PhaseIterGVN *igvn = phase->is_IterGVN();
1676 RegionNode *newr = new RegionNode(hit+1);
1677 split_once(igvn, phi, val, r, newr);
1678
1679 // Now split all other Phis than this one
1680 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) {
1681 Node* phi2 = r->fast_out(k);
1682 if( phi2->is_Phi() && phi2->as_Phi() != phi ) {
1683 PhiNode *newphi = PhiNode::make_blank(newr, phi2);
1684 split_once(igvn, phi, val, phi2, newphi);
1685 }
1686 }
1687
1688 // Clean up this guy
1689 igvn->hash_delete(phi);
1690 for( i = phi->req()-1; i > 0; i-- ) {
1691 if( phi->in(i) == val ) {
1692 phi->del_req(i);
1693 }
1694 }
1695 phi->add_req(val);
1696
1697 return phi;
1698 }
1699
1700 //=============================================================================
1701 //------------------------------simple_data_loop_check-------------------------
1702 // Try to determining if the phi node in a simple safe/unsafe data loop.
1703 // Returns:
1704 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
1705 // Safe - safe case when the phi and it's inputs reference only safe data
1706 // nodes;
1707 // Unsafe - the phi and it's inputs reference unsafe data nodes but there
1708 // is no reference back to the phi - need a graph walk
1709 // to determine if it is in a loop;
1710 // UnsafeLoop - unsafe case when the phi references itself directly or through
1711 // unsafe data node.
1712 // Note: a safe data node is a node which could/never reference itself during
1713 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP.
1714 // I mark Phi nodes as safe node not only because they can reference itself
1715 // but also to prevent mistaking the fallthrough case inside an outer loop
1716 // as dead loop when the phi references itselfs through an other phi.
1717 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const {
1718 // It is unsafe loop if the phi node references itself directly.
1719 if (in == (Node*)this)
1720 return UnsafeLoop; // Unsafe loop
1721 // Unsafe loop if the phi node references itself through an unsafe data node.
1722 // Exclude cases with null inputs or data nodes which could reference
1723 // itself (safe for dead loops).
1724 if (in != NULL && !in->is_dead_loop_safe()) {
1725 // Check inputs of phi's inputs also.
1726 // It is much less expensive then full graph walk.
1727 uint cnt = in->req();
1728 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1;
1729 for (; i < cnt; ++i) {
1730 Node* m = in->in(i);
1731 if (m == (Node*)this)
1732 return UnsafeLoop; // Unsafe loop
1733 if (m != NULL && !m->is_dead_loop_safe()) {
1734 // Check the most common case (about 30% of all cases):
1735 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con).
1736 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL;
1737 if (m1 == (Node*)this)
1738 return UnsafeLoop; // Unsafe loop
1739 if (m1 != NULL && m1 == m->in(2) &&
1740 m1->is_dead_loop_safe() && m->in(3)->is_Con()) {
1741 continue; // Safe case
1742 }
1743 // The phi references an unsafe node - need full analysis.
1744 return Unsafe;
1745 }
1746 }
1747 }
1748 return Safe; // Safe case - we can optimize the phi node.
1749 }
1750
1751 //------------------------------is_unsafe_data_reference-----------------------
1752 // If phi can be reached through the data input - it is data loop.
1753 bool PhiNode::is_unsafe_data_reference(Node *in) const {
1754 assert(req() > 1, "");
1755 // First, check simple cases when phi references itself directly or
1756 // through an other node.
1757 LoopSafety safety = simple_data_loop_check(in);
1758 if (safety == UnsafeLoop)
1759 return true; // phi references itself - unsafe loop
1760 else if (safety == Safe)
1761 return false; // Safe case - phi could be replaced with the unique input.
1762
1763 // Unsafe case when we should go through data graph to determine
1764 // if the phi references itself.
1765
1766 ResourceMark rm;
1767
1768 Arena *a = Thread::current()->resource_area();
1769 Node_List nstack(a);
1770 VectorSet visited(a);
1771
1772 nstack.push(in); // Start with unique input.
1773 visited.set(in->_idx);
1774 while (nstack.size() != 0) {
1775 Node* n = nstack.pop();
1776 uint cnt = n->req();
1777 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1;
1778 for (; i < cnt; i++) {
1779 Node* m = n->in(i);
1780 if (m == (Node*)this) {
1781 return true; // Data loop
1782 }
1783 if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases.
1784 if (!visited.test_set(m->_idx))
1785 nstack.push(m);
1786 }
1787 }
1788 }
1789 return false; // The phi is not reachable from its inputs
1790 }
1791
1792
1793 //------------------------------Ideal------------------------------------------
1794 // Return a node which is more "ideal" than the current node. Must preserve
1795 // the CFG, but we can still strip out dead paths.
1796 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1797 // The next should never happen after 6297035 fix.
1798 if( is_copy() ) // Already degraded to a Copy ?
1799 return NULL; // No change
1800
1801 Node *r = in(0); // RegionNode
1802 assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge");
1803
1804 // Note: During parsing, phis are often transformed before their regions.
1805 // This means we have to use type_or_null to defend against untyped regions.
1806 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1807 return NULL; // No change
1808
1809 // If all inputs are value types of the same type, push the value type node down
1810 // through the phi because value type nodes should be merged through their input values.
1811 if (req() > 2 && in(1) != NULL && in(1)->is_ValueTypeBase() && (can_reshape || in(1)->is_ValueType())) {
1812 int opcode = in(1)->Opcode();
1813 uint i = 2;
1814 // Check if inputs are values of the same type
1815 for (; i < req() && in(i) && in(i)->is_ValueTypeBase() && in(i)->cmp(*in(1)); i++) {
1816 assert(in(i)->Opcode() == opcode, "mixing pointers and values?");
1817 }
1818 if (i == req()) {
1819 ValueTypeBaseNode* vt = in(1)->as_ValueTypeBase()->clone_with_phis(phase, in(0));
1820 for (uint i = 2; i < req(); ++i) {
1821 vt->merge_with(phase, in(i)->as_ValueTypeBase(), i, i == (req()-1));
1822 }
1823 return vt;
1824 }
1825 }
1826
1827 Node *top = phase->C->top();
1828 bool new_phi = (outcnt() == 0); // transforming new Phi
1829 // No change for igvn if new phi is not hooked
1830 if (new_phi && can_reshape)
1831 return NULL;
1832
1833 // The are 2 situations when only one valid phi's input is left
1834 // (in addition to Region input).
1835 // One: region is not loop - replace phi with this input.
1836 // Two: region is loop - replace phi with top since this data path is dead
1837 // and we need to break the dead data loop.
1838 Node* progress = NULL; // Record if any progress made
1839 for( uint j = 1; j < req(); ++j ){ // For all paths in
1840 // Check unreachable control paths
1841 Node* rc = r->in(j);
1842 Node* n = in(j); // Get the input
1843 if (rc == NULL || phase->type(rc) == Type::TOP) {
1844 if (n != top) { // Not already top?
1845 PhaseIterGVN *igvn = phase->is_IterGVN();
1846 if (can_reshape && igvn != NULL) {
1847 igvn->_worklist.push(r);
1848 }
1849 // Nuke it down
1850 if (can_reshape) {
1851 set_req_X(j, top, igvn);
1852 } else {
1853 set_req(j, top);
1854 }
1855 progress = this; // Record progress
1856 }
1857 }
1858 }
1859
1860 if (can_reshape && outcnt() == 0) {
1861 // set_req() above may kill outputs if Phi is referenced
1862 // only by itself on the dead (top) control path.
1863 return top;
1864 }
1865
1866 bool uncasted = false;
1867 Node* uin = unique_input(phase, false);
1868 if (uin == NULL && can_reshape) {
1869 uncasted = true;
1870 uin = unique_input(phase, true);
1871 }
1872 if (uin == top) { // Simplest case: no alive inputs.
1873 if (can_reshape) // IGVN transformation
1874 return top;
1875 else
1876 return NULL; // Identity will return TOP
1877 } else if (uin != NULL) {
1878 // Only one not-NULL unique input path is left.
1879 // Determine if this input is backedge of a loop.
1880 // (Skip new phis which have no uses and dead regions).
1881 if (outcnt() > 0 && r->in(0) != NULL) {
1882 // First, take the short cut when we know it is a loop and
1883 // the EntryControl data path is dead.
1884 // Loop node may have only one input because entry path
1885 // is removed in PhaseIdealLoop::Dominators().
1886 assert(!r->is_Loop() || r->req() <= 3, "Loop node should have 3 or less inputs");
1887 bool is_loop = (r->is_Loop() && r->req() == 3);
1888 // Then, check if there is a data loop when phi references itself directly
1889 // or through other data nodes.
1890 if ((is_loop && !uin->eqv_uncast(in(LoopNode::EntryControl))) ||
1891 (!is_loop && is_unsafe_data_reference(uin))) {
1892 // Break this data loop to avoid creation of a dead loop.
1893 if (can_reshape) {
1894 return top;
1895 } else {
1896 // We can't return top if we are in Parse phase - cut inputs only
1897 // let Identity to handle the case.
1898 replace_edge(uin, top);
1899 return NULL;
1900 }
1901 }
1902 }
1903
1904 if (uncasted) {
1905 // Add cast nodes between the phi to be removed and its unique input.
1906 // Wait until after parsing for the type information to propagate from the casts.
1907 assert(can_reshape, "Invalid during parsing");
1908 const Type* phi_type = bottom_type();
1909 assert(phi_type->isa_int() || phi_type->isa_ptr(), "bad phi type");
1910 // Add casts to carry the control dependency of the Phi that is
1911 // going away
1912 Node* cast = NULL;
1913 if (phi_type->isa_int()) {
1914 cast = ConstraintCastNode::make_cast(Op_CastII, r, uin, phi_type, true);
1915 } else {
1916 const Type* uin_type = phase->type(uin);
1917 if (!phi_type->isa_oopptr() && !uin_type->isa_oopptr()) {
1918 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true);
1919 } else {
1920 // Use a CastPP for a cast to not null and a CheckCastPP for
1921 // a cast to a new klass (and both if both null-ness and
1922 // klass change).
1923
1924 // If the type of phi is not null but the type of uin may be
1925 // null, uin's type must be casted to not null
1926 if (phi_type->join(TypePtr::NOTNULL) == phi_type->remove_speculative() &&
1927 uin_type->join(TypePtr::NOTNULL) != uin_type->remove_speculative()) {
1928 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, TypePtr::NOTNULL, true);
1929 }
1930
1931 // If the type of phi and uin, both casted to not null,
1932 // differ the klass of uin must be (check)cast'ed to match
1933 // that of phi
1934 if (phi_type->join_speculative(TypePtr::NOTNULL) != uin_type->join_speculative(TypePtr::NOTNULL)) {
1935 Node* n = uin;
1936 if (cast != NULL) {
1937 cast = phase->transform(cast);
1938 n = cast;
1939 }
1940 cast = ConstraintCastNode::make_cast(Op_CheckCastPP, r, n, phi_type, true);
1941 }
1942 if (cast == NULL) {
1943 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true);
1944 }
1945 }
1946 }
1947 assert(cast != NULL, "cast should be set");
1948 cast = phase->transform(cast);
1949 // set all inputs to the new cast(s) so the Phi is removed by Identity
1950 PhaseIterGVN* igvn = phase->is_IterGVN();
1951 for (uint i = 1; i < req(); i++) {
1952 set_req_X(i, cast, igvn);
1953 }
1954 uin = cast;
1955 }
1956
1957 // One unique input.
1958 debug_only(Node* ident = Identity(phase));
1959 // The unique input must eventually be detected by the Identity call.
1960 #ifdef ASSERT
1961 if (ident != uin && !ident->is_top()) {
1962 // print this output before failing assert
1963 r->dump(3);
1964 this->dump(3);
1965 ident->dump();
1966 uin->dump();
1967 }
1968 #endif
1969 assert(ident == uin || ident->is_top(), "Identity must clean this up");
1970 return NULL;
1971 }
1972
1973 Node* opt = NULL;
1974 int true_path = is_diamond_phi();
1975 if( true_path != 0 ) {
1976 // Check for CMove'ing identity. If it would be unsafe,
1977 // handle it here. In the safe case, let Identity handle it.
1978 Node* unsafe_id = is_cmove_id(phase, true_path);
1979 if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) )
1980 opt = unsafe_id;
1981
1982 // Check for simple convert-to-boolean pattern
1983 if( opt == NULL )
1984 opt = is_x2logic(phase, this, true_path);
1985
1986 // Check for absolute value
1987 if( opt == NULL )
1988 opt = is_absolute(phase, this, true_path);
1989
1990 // Check for conditional add
1991 if( opt == NULL && can_reshape )
1992 opt = is_cond_add(phase, this, true_path);
1993
1994 // These 4 optimizations could subsume the phi:
1995 // have to check for a dead data loop creation.
1996 if( opt != NULL ) {
1997 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) {
1998 // Found dead loop.
1999 if( can_reshape )
2000 return top;
2001 // We can't return top if we are in Parse phase - cut inputs only
2002 // to stop further optimizations for this phi. Identity will return TOP.
2003 assert(req() == 3, "only diamond merge phi here");
2004 set_req(1, top);
2005 set_req(2, top);
2006 return NULL;
2007 } else {
2008 return opt;
2009 }
2010 }
2011 }
2012
2013 // Check for merging identical values and split flow paths
2014 if (can_reshape) {
2015 opt = split_flow_path(phase, this);
2016 // This optimization only modifies phi - don't need to check for dead loop.
2017 assert(opt == NULL || phase->eqv(opt, this), "do not elide phi");
2018 if (opt != NULL) return opt;
2019 }
2020
2021 if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) {
2022 // Try to undo Phi of AddP:
2023 // (Phi (AddP base base y) (AddP base2 base2 y))
2024 // becomes:
2025 // newbase := (Phi base base2)
2026 // (AddP newbase newbase y)
2027 //
2028 // This occurs as a result of unsuccessful split_thru_phi and
2029 // interferes with taking advantage of addressing modes. See the
2030 // clone_shift_expressions code in matcher.cpp
2031 Node* addp = in(1);
2032 const Type* type = addp->in(AddPNode::Base)->bottom_type();
2033 Node* y = addp->in(AddPNode::Offset);
2034 if (y != NULL && addp->in(AddPNode::Base) == addp->in(AddPNode::Address)) {
2035 // make sure that all the inputs are similar to the first one,
2036 // i.e. AddP with base == address and same offset as first AddP
2037 bool doit = true;
2038 for (uint i = 2; i < req(); i++) {
2039 if (in(i) == NULL ||
2040 in(i)->Opcode() != Op_AddP ||
2041 in(i)->in(AddPNode::Base) != in(i)->in(AddPNode::Address) ||
2042 in(i)->in(AddPNode::Offset) != y) {
2043 doit = false;
2044 break;
2045 }
2046 // Accumulate type for resulting Phi
2047 type = type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type());
2048 }
2049 Node* base = NULL;
2050 if (doit) {
2051 // Check for neighboring AddP nodes in a tree.
2052 // If they have a base, use that it.
2053 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) {
2054 Node* u = this->fast_out(k);
2055 if (u->is_AddP()) {
2056 Node* base2 = u->in(AddPNode::Base);
2057 if (base2 != NULL && !base2->is_top()) {
2058 if (base == NULL)
2059 base = base2;
2060 else if (base != base2)
2061 { doit = false; break; }
2062 }
2063 }
2064 }
2065 }
2066 if (doit) {
2067 if (base == NULL) {
2068 base = new PhiNode(in(0), type, NULL);
2069 for (uint i = 1; i < req(); i++) {
2070 base->init_req(i, in(i)->in(AddPNode::Base));
2071 }
2072 phase->is_IterGVN()->register_new_node_with_optimizer(base);
2073 }
2074 return new AddPNode(base, base, y);
2075 }
2076 }
2077 }
2078
2079 // Split phis through memory merges, so that the memory merges will go away.
2080 // Piggy-back this transformation on the search for a unique input....
2081 // It will be as if the merged memory is the unique value of the phi.
2082 // (Do not attempt this optimization unless parsing is complete.
2083 // It would make the parser's memory-merge logic sick.)
2084 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.)
2085 if (progress == NULL && can_reshape && type() == Type::MEMORY) {
2086 // see if this phi should be sliced
2087 uint merge_width = 0;
2088 bool saw_self = false;
2089 for( uint i=1; i<req(); ++i ) {// For all paths in
2090 Node *ii = in(i);
2091 // TOP inputs should not be counted as safe inputs because if the
2092 // Phi references itself through all other inputs then splitting the
2093 // Phi through memory merges would create dead loop at later stage.
2094 if (ii == top) {
2095 return NULL; // Delay optimization until graph is cleaned.
2096 }
2097 if (ii->is_MergeMem()) {
2098 MergeMemNode* n = ii->as_MergeMem();
2099 merge_width = MAX2(merge_width, n->req());
2100 saw_self = saw_self || phase->eqv(n->base_memory(), this);
2101 }
2102 }
2103
2104 // This restriction is temporarily necessary to ensure termination:
2105 if (!saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0;
2106
2107 if (merge_width > Compile::AliasIdxRaw) {
2108 // found at least one non-empty MergeMem
2109 const TypePtr* at = adr_type();
2110 if (at != TypePtr::BOTTOM) {
2111 // Patch the existing phi to select an input from the merge:
2112 // Phi:AT1(...MergeMem(m0, m1, m2)...) into
2113 // Phi:AT1(...m1...)
2114 int alias_idx = phase->C->get_alias_index(at);
2115 for (uint i=1; i<req(); ++i) {
2116 Node *ii = in(i);
2117 if (ii->is_MergeMem()) {
2118 MergeMemNode* n = ii->as_MergeMem();
2119 // compress paths and change unreachable cycles to TOP
2120 // If not, we can update the input infinitely along a MergeMem cycle
2121 // Equivalent code is in MemNode::Ideal_common
2122 Node *m = phase->transform(n);
2123 if (outcnt() == 0) { // Above transform() may kill us!
2124 return top;
2125 }
2126 // If transformed to a MergeMem, get the desired slice
2127 // Otherwise the returned node represents memory for every slice
2128 Node *new_mem = (m->is_MergeMem()) ?
2129 m->as_MergeMem()->memory_at(alias_idx) : m;
2130 // Update input if it is progress over what we have now
2131 if (new_mem != ii) {
2132 set_req(i, new_mem);
2133 progress = this;
2134 }
2135 }
2136 }
2137 } else {
2138 // We know that at least one MergeMem->base_memory() == this
2139 // (saw_self == true). If all other inputs also references this phi
2140 // (directly or through data nodes) - it is dead loop.
2141 bool saw_safe_input = false;
2142 for (uint j = 1; j < req(); ++j) {
2143 Node *n = in(j);
2144 if (n->is_MergeMem() && n->as_MergeMem()->base_memory() == this)
2145 continue; // skip known cases
2146 if (!is_unsafe_data_reference(n)) {
2147 saw_safe_input = true; // found safe input
2148 break;
2149 }
2150 }
2151 if (!saw_safe_input)
2152 return top; // all inputs reference back to this phi - dead loop
2153
2154 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into
2155 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...))
2156 PhaseIterGVN *igvn = phase->is_IterGVN();
2157 Node* hook = new Node(1);
2158 PhiNode* new_base = (PhiNode*) clone();
2159 // Must eagerly register phis, since they participate in loops.
2160 if (igvn) {
2161 igvn->register_new_node_with_optimizer(new_base);
2162 hook->add_req(new_base);
2163 }
2164 MergeMemNode* result = MergeMemNode::make(new_base);
2165 for (uint i = 1; i < req(); ++i) {
2166 Node *ii = in(i);
2167 if (ii->is_MergeMem()) {
2168 MergeMemNode* n = ii->as_MergeMem();
2169 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) {
2170 // If we have not seen this slice yet, make a phi for it.
2171 bool made_new_phi = false;
2172 if (mms.is_empty()) {
2173 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C));
2174 made_new_phi = true;
2175 if (igvn) {
2176 igvn->register_new_node_with_optimizer(new_phi);
2177 hook->add_req(new_phi);
2178 }
2179 mms.set_memory(new_phi);
2180 }
2181 Node* phi = mms.memory();
2182 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice");
2183 phi->set_req(i, mms.memory2());
2184 }
2185 }
2186 }
2187 // Distribute all self-loops.
2188 { // (Extra braces to hide mms.)
2189 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2190 Node* phi = mms.memory();
2191 for (uint i = 1; i < req(); ++i) {
2192 if (phi->in(i) == this) phi->set_req(i, phi);
2193 }
2194 }
2195 }
2196 // now transform the new nodes, and return the mergemem
2197 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2198 Node* phi = mms.memory();
2199 mms.set_memory(phase->transform(phi));
2200 }
2201 if (igvn) { // Unhook.
2202 igvn->hash_delete(hook);
2203 for (uint i = 1; i < hook->req(); i++) {
2204 hook->set_req(i, NULL);
2205 }
2206 }
2207 // Replace self with the result.
2208 return result;
2209 }
2210 }
2211 //
2212 // Other optimizations on the memory chain
2213 //
2214 const TypePtr* at = adr_type();
2215 for( uint i=1; i<req(); ++i ) {// For all paths in
2216 Node *ii = in(i);
2217 Node *new_in = MemNode::optimize_memory_chain(ii, at, NULL, phase);
2218 if (ii != new_in ) {
2219 set_req(i, new_in);
2220 progress = this;
2221 }
2222 }
2223 }
2224
2225 #ifdef _LP64
2226 // Push DecodeN/DecodeNKlass down through phi.
2227 // The rest of phi graph will transform by split EncodeP node though phis up.
2228 if ((UseCompressedOops || UseCompressedClassPointers) && can_reshape && progress == NULL) {
2229 bool may_push = true;
2230 bool has_decodeN = false;
2231 bool is_decodeN = false;
2232 for (uint i=1; i<req(); ++i) {// For all paths in
2233 Node *ii = in(i);
2234 if (ii->is_DecodeNarrowPtr() && ii->bottom_type() == bottom_type()) {
2235 // Do optimization if a non dead path exist.
2236 if (ii->in(1)->bottom_type() != Type::TOP) {
2237 has_decodeN = true;
2238 is_decodeN = ii->is_DecodeN();
2239 }
2240 } else if (!ii->is_Phi()) {
2241 may_push = false;
2242 }
2243 }
2244
2245 if (has_decodeN && may_push) {
2246 PhaseIterGVN *igvn = phase->is_IterGVN();
2247 // Make narrow type for new phi.
2248 const Type* narrow_t;
2249 if (is_decodeN) {
2250 narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr());
2251 } else {
2252 narrow_t = TypeNarrowKlass::make(this->bottom_type()->is_ptr());
2253 }
2254 PhiNode* new_phi = new PhiNode(r, narrow_t);
2255 uint orig_cnt = req();
2256 for (uint i=1; i<req(); ++i) {// For all paths in
2257 Node *ii = in(i);
2258 Node* new_ii = NULL;
2259 if (ii->is_DecodeNarrowPtr()) {
2260 assert(ii->bottom_type() == bottom_type(), "sanity");
2261 new_ii = ii->in(1);
2262 } else {
2263 assert(ii->is_Phi(), "sanity");
2264 if (ii->as_Phi() == this) {
2265 new_ii = new_phi;
2266 } else {
2267 if (is_decodeN) {
2268 new_ii = new EncodePNode(ii, narrow_t);
2269 } else {
2270 new_ii = new EncodePKlassNode(ii, narrow_t);
2271 }
2272 igvn->register_new_node_with_optimizer(new_ii);
2273 }
2274 }
2275 new_phi->set_req(i, new_ii);
2276 }
2277 igvn->register_new_node_with_optimizer(new_phi, this);
2278 if (is_decodeN) {
2279 progress = new DecodeNNode(new_phi, bottom_type());
2280 } else {
2281 progress = new DecodeNKlassNode(new_phi, bottom_type());
2282 }
2283 }
2284 }
2285 #endif
2286
2287 return progress; // Return any progress
2288 }
2289
2290 //------------------------------is_tripcount-----------------------------------
2291 bool PhiNode::is_tripcount() const {
2292 return (in(0) != NULL && in(0)->is_CountedLoop() &&
2293 in(0)->as_CountedLoop()->phi() == this);
2294 }
2295
2296 //------------------------------out_RegMask------------------------------------
2297 const RegMask &PhiNode::in_RegMask(uint i) const {
2298 return i ? out_RegMask() : RegMask::Empty;
2299 }
2300
2301 const RegMask &PhiNode::out_RegMask() const {
2302 uint ideal_reg = _type->ideal_reg();
2303 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
2304 if( ideal_reg == 0 ) return RegMask::Empty;
2305 assert(ideal_reg != Op_RegFlags, "flags register is not spillable");
2306 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
2307 }
2308
2309 #ifndef PRODUCT
2310 void PhiNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2311 // For a PhiNode, the set of related nodes includes all inputs till level 2,
2312 // and all outputs till level 1. In compact mode, inputs till level 1 are
2313 // collected.
2314 this->collect_nodes(in_rel, compact ? 1 : 2, false, false);
2315 this->collect_nodes(out_rel, -1, false, false);
2316 }
2317
2318 void PhiNode::dump_spec(outputStream *st) const {
2319 TypeNode::dump_spec(st);
2320 if (is_tripcount()) {
2321 st->print(" #tripcount");
2322 }
2323 }
2324 #endif
2325
2326
2327 //=============================================================================
2328 const Type* GotoNode::Value(PhaseGVN* phase) const {
2329 // If the input is reachable, then we are executed.
2330 // If the input is not reachable, then we are not executed.
2331 return phase->type(in(0));
2332 }
2333
2334 Node* GotoNode::Identity(PhaseGVN* phase) {
2335 return in(0); // Simple copy of incoming control
2336 }
2337
2338 const RegMask &GotoNode::out_RegMask() const {
2339 return RegMask::Empty;
2340 }
2341
2342 #ifndef PRODUCT
2343 //-----------------------------related-----------------------------------------
2344 // The related nodes of a GotoNode are all inputs at level 1, as well as the
2345 // outputs at level 1. This is regardless of compact mode.
2346 void GotoNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2347 this->collect_nodes(in_rel, 1, false, false);
2348 this->collect_nodes(out_rel, -1, false, false);
2349 }
2350 #endif
2351
2352
2353 //=============================================================================
2354 const RegMask &JumpNode::out_RegMask() const {
2355 return RegMask::Empty;
2356 }
2357
2358 #ifndef PRODUCT
2359 //-----------------------------related-----------------------------------------
2360 // The related nodes of a JumpNode are all inputs at level 1, as well as the
2361 // outputs at level 2 (to include actual jump targets beyond projection nodes).
2362 // This is regardless of compact mode.
2363 void JumpNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2364 this->collect_nodes(in_rel, 1, false, false);
2365 this->collect_nodes(out_rel, -2, false, false);
2366 }
2367 #endif
2368
2369 //=============================================================================
2370 const RegMask &JProjNode::out_RegMask() const {
2371 return RegMask::Empty;
2372 }
2373
2374 //=============================================================================
2375 const RegMask &CProjNode::out_RegMask() const {
2376 return RegMask::Empty;
2377 }
2378
2379
2380
2381 //=============================================================================
2382
2383 uint PCTableNode::hash() const { return Node::hash() + _size; }
2384 uint PCTableNode::cmp( const Node &n ) const
2385 { return _size == ((PCTableNode&)n)._size; }
2386
2387 const Type *PCTableNode::bottom_type() const {
2388 const Type** f = TypeTuple::fields(_size);
2389 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2390 return TypeTuple::make(_size, f);
2391 }
2392
2393 //------------------------------Value------------------------------------------
2394 // Compute the type of the PCTableNode. If reachable it is a tuple of
2395 // Control, otherwise the table targets are not reachable
2396 const Type* PCTableNode::Value(PhaseGVN* phase) const {
2397 if( phase->type(in(0)) == Type::CONTROL )
2398 return bottom_type();
2399 return Type::TOP; // All paths dead? Then so are we
2400 }
2401
2402 //------------------------------Ideal------------------------------------------
2403 // Return a node which is more "ideal" than the current node. Strip out
2404 // control copies
2405 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2406 return remove_dead_region(phase, can_reshape) ? this : NULL;
2407 }
2408
2409 //=============================================================================
2410 uint JumpProjNode::hash() const {
2411 return Node::hash() + _dest_bci;
2412 }
2413
2414 uint JumpProjNode::cmp( const Node &n ) const {
2415 return ProjNode::cmp(n) &&
2416 _dest_bci == ((JumpProjNode&)n)._dest_bci;
2417 }
2418
2419 #ifndef PRODUCT
2420 void JumpProjNode::dump_spec(outputStream *st) const {
2421 ProjNode::dump_spec(st);
2422 st->print("@bci %d ",_dest_bci);
2423 }
2424
2425 void JumpProjNode::dump_compact_spec(outputStream *st) const {
2426 ProjNode::dump_compact_spec(st);
2427 st->print("(%d)%d@%d", _switch_val, _proj_no, _dest_bci);
2428 }
2429
2430 void JumpProjNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2431 // The related nodes of a JumpProjNode are its inputs and outputs at level 1.
2432 this->collect_nodes(in_rel, 1, false, false);
2433 this->collect_nodes(out_rel, -1, false, false);
2434 }
2435 #endif
2436
2437 //=============================================================================
2438 //------------------------------Value------------------------------------------
2439 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot
2440 // have the default "fall_through_index" path.
2441 const Type* CatchNode::Value(PhaseGVN* phase) const {
2442 // Unreachable? Then so are all paths from here.
2443 if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
2444 // First assume all paths are reachable
2445 const Type** f = TypeTuple::fields(_size);
2446 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2447 // Identify cases that will always throw an exception
2448 // () rethrow call
2449 // () virtual or interface call with NULL receiver
2450 // () call is a check cast with incompatible arguments
2451 if( in(1)->is_Proj() ) {
2452 Node *i10 = in(1)->in(0);
2453 if( i10->is_Call() ) {
2454 CallNode *call = i10->as_Call();
2455 // Rethrows always throw exceptions, never return
2456 if (call->entry_point() == OptoRuntime::rethrow_stub()) {
2457 f[CatchProjNode::fall_through_index] = Type::TOP;
2458 } else if( call->req() > TypeFunc::Parms ) {
2459 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) );
2460 // Check for null receiver to virtual or interface calls
2461 if( call->is_CallDynamicJava() &&
2462 arg0->higher_equal(TypePtr::NULL_PTR) ) {
2463 f[CatchProjNode::fall_through_index] = Type::TOP;
2464 }
2465 } // End of if not a runtime stub
2466 } // End of if have call above me
2467 } // End of slot 1 is not a projection
2468 return TypeTuple::make(_size, f);
2469 }
2470
2471 //=============================================================================
2472 uint CatchProjNode::hash() const {
2473 return Node::hash() + _handler_bci;
2474 }
2475
2476
2477 uint CatchProjNode::cmp( const Node &n ) const {
2478 return ProjNode::cmp(n) &&
2479 _handler_bci == ((CatchProjNode&)n)._handler_bci;
2480 }
2481
2482
2483 //------------------------------Identity---------------------------------------
2484 // If only 1 target is possible, choose it if it is the main control
2485 Node* CatchProjNode::Identity(PhaseGVN* phase) {
2486 // If my value is control and no other value is, then treat as ID
2487 const TypeTuple *t = phase->type(in(0))->is_tuple();
2488 if (t->field_at(_con) != Type::CONTROL) return this;
2489 // If we remove the last CatchProj and elide the Catch/CatchProj, then we
2490 // also remove any exception table entry. Thus we must know the call
2491 // feeding the Catch will not really throw an exception. This is ok for
2492 // the main fall-thru control (happens when we know a call can never throw
2493 // an exception) or for "rethrow", because a further optimization will
2494 // yank the rethrow (happens when we inline a function that can throw an
2495 // exception and the caller has no handler). Not legal, e.g., for passing
2496 // a NULL receiver to a v-call, or passing bad types to a slow-check-cast.
2497 // These cases MUST throw an exception via the runtime system, so the VM
2498 // will be looking for a table entry.
2499 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode
2500 CallNode *call;
2501 if (_con != TypeFunc::Control && // Bail out if not the main control.
2502 !(proj->is_Proj() && // AND NOT a rethrow
2503 proj->in(0)->is_Call() &&
2504 (call = proj->in(0)->as_Call()) &&
2505 call->entry_point() == OptoRuntime::rethrow_stub()))
2506 return this;
2507
2508 // Search for any other path being control
2509 for (uint i = 0; i < t->cnt(); i++) {
2510 if (i != _con && t->field_at(i) == Type::CONTROL)
2511 return this;
2512 }
2513 // Only my path is possible; I am identity on control to the jump
2514 return in(0)->in(0);
2515 }
2516
2517
2518 #ifndef PRODUCT
2519 void CatchProjNode::dump_spec(outputStream *st) const {
2520 ProjNode::dump_spec(st);
2521 st->print("@bci %d ",_handler_bci);
2522 }
2523 #endif
2524
2525 //=============================================================================
2526 //------------------------------Identity---------------------------------------
2527 // Check for CreateEx being Identity.
2528 Node* CreateExNode::Identity(PhaseGVN* phase) {
2529 if( phase->type(in(1)) == Type::TOP ) return in(1);
2530 if( phase->type(in(0)) == Type::TOP ) return in(0);
2531 // We only come from CatchProj, unless the CatchProj goes away.
2532 // If the CatchProj is optimized away, then we just carry the
2533 // exception oop through.
2534
2535 // CheckCastPPNode::Ideal() for value types reuses the exception
2536 // paths of a call to perform an allocation: we can see a Phi here.
2537 if (in(1)->is_Phi()) {
2538 return this;
2539 }
2540 CallNode *call = in(1)->in(0)->as_Call();
2541
2542 return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) )
2543 ? this
2544 : call->in(TypeFunc::Parms);
2545 }
2546
2547 //=============================================================================
2548 //------------------------------Value------------------------------------------
2549 // Check for being unreachable.
2550 const Type* NeverBranchNode::Value(PhaseGVN* phase) const {
2551 if (!in(0) || in(0)->is_top()) return Type::TOP;
2552 return bottom_type();
2553 }
2554
2555 //------------------------------Ideal------------------------------------------
2556 // Check for no longer being part of a loop
2557 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2558 if (can_reshape && !in(0)->is_Loop()) {
2559 // Dead code elimination can sometimes delete this projection so
2560 // if it's not there, there's nothing to do.
2561 Node* fallthru = proj_out_or_null(0);
2562 if (fallthru != NULL) {
2563 phase->is_IterGVN()->replace_node(fallthru, in(0));
2564 }
2565 return phase->C->top();
2566 }
2567 return NULL;
2568 }
2569
2570 #ifndef PRODUCT
2571 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const {
2572 st->print("%s", Name());
2573 }
2574 #endif