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