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.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "gc/shared/c2/barrierSetC2.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "memory/resourceArea.hpp"
30 #include "oops/objArrayKlass.hpp"
31 #include "opto/addnode.hpp"
32 #include "opto/castnode.hpp"
33 #include "opto/cfgnode.hpp"
34 #include "opto/connode.hpp"
35 #include "opto/convertnode.hpp"
36 #include "opto/loopnode.hpp"
37 #include "opto/machnode.hpp"
38 #include "opto/movenode.hpp"
39 #include "opto/narrowptrnode.hpp"
40 #include "opto/mulnode.hpp"
41 #include "opto/phaseX.hpp"
42 #include "opto/regmask.hpp"
43 #include "opto/runtime.hpp"
44 #include "opto/subnode.hpp"
45 #include "utilities/vmError.hpp"
46
47 // Portions of code courtesy of Clifford Click
48
49 // Optimization - Graph Style
50
51 //=============================================================================
52 //------------------------------Value------------------------------------------
53 // Compute the type of the RegionNode.
54 const Type* RegionNode::Value(PhaseGVN* phase) const {
55 for( uint i=1; i<req(); ++i ) { // For all paths in
56 Node *n = in(i); // Get Control source
57 if( !n ) continue; // Missing inputs are TOP
58 if( phase->type(n) == Type::CONTROL )
59 return Type::CONTROL;
60 }
61 return Type::TOP; // All paths dead? Then so are we
62 }
63
64 //------------------------------Identity---------------------------------------
65 // Check for Region being Identity.
66 Node* RegionNode::Identity(PhaseGVN* phase) {
67 // Cannot have Region be an identity, even if it has only 1 input.
68 // Phi users cannot have their Region input folded away for them,
69 // since they need to select the proper data input
70 return this;
71 }
72
73 //------------------------------merge_region-----------------------------------
74 // If a Region flows into a Region, merge into one big happy merge. This is
75 // hard to do if there is stuff that has to happen
76 static Node *merge_region(RegionNode *region, PhaseGVN *phase) {
77 if( region->Opcode() != Op_Region ) // Do not do to LoopNodes
78 return NULL;
79 Node *progress = NULL; // Progress flag
80 PhaseIterGVN *igvn = phase->is_IterGVN();
81
82 uint rreq = region->req();
83 for( uint i = 1; i < rreq; i++ ) {
84 Node *r = region->in(i);
85 if( r && r->Opcode() == Op_Region && // Found a region?
86 r->in(0) == r && // Not already collapsed?
87 r != region && // Avoid stupid situations
88 r->outcnt() == 2 ) { // Self user and 'region' user only?
89 assert(!r->as_Region()->has_phi(), "no phi users");
90 if( !progress ) { // No progress
91 if (region->has_phi()) {
92 return NULL; // Only flatten if no Phi users
93 // igvn->hash_delete( phi );
94 }
95 igvn->hash_delete( region );
96 progress = region; // Making progress
97 }
98 igvn->hash_delete( r );
99
100 // Append inputs to 'r' onto 'region'
101 for( uint j = 1; j < r->req(); j++ ) {
102 // Move an input from 'r' to 'region'
103 region->add_req(r->in(j));
104 r->set_req(j, phase->C->top());
105 // Update phis of 'region'
106 //for( uint k = 0; k < max; k++ ) {
107 // Node *phi = region->out(k);
108 // if( phi->is_Phi() ) {
109 // phi->add_req(phi->in(i));
110 // }
111 //}
112
113 rreq++; // One more input to Region
114 } // Found a region to merge into Region
115 igvn->_worklist.push(r);
116 // Clobber pointer to the now dead 'r'
117 region->set_req(i, phase->C->top());
118 }
119 }
120
121 return progress;
122 }
123
124
125
126 //--------------------------------has_phi--------------------------------------
127 // Helper function: Return any PhiNode that uses this region or NULL
128 PhiNode* RegionNode::has_phi() const {
129 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
130 Node* phi = fast_out(i);
131 if (phi->is_Phi()) { // Check for Phi users
132 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
133 return phi->as_Phi(); // this one is good enough
134 }
135 }
136
137 return NULL;
138 }
139
140
141 //-----------------------------has_unique_phi----------------------------------
142 // Helper function: Return the only PhiNode that uses this region or NULL
143 PhiNode* RegionNode::has_unique_phi() const {
144 // Check that only one use is a Phi
145 PhiNode* only_phi = NULL;
146 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
147 Node* phi = fast_out(i);
148 if (phi->is_Phi()) { // Check for Phi users
149 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
150 if (only_phi == NULL) {
151 only_phi = phi->as_Phi();
152 } else {
153 return NULL; // multiple phis
154 }
155 }
156 }
157
158 return only_phi;
159 }
160
161
162 //------------------------------check_phi_clipping-----------------------------
163 // Helper function for RegionNode's identification of FP clipping
164 // Check inputs to the Phi
165 static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) {
166 min = NULL;
167 max = NULL;
168 val = NULL;
169 min_idx = 0;
170 max_idx = 0;
171 val_idx = 0;
172 uint phi_max = phi->req();
173 if( phi_max == 4 ) {
174 for( uint j = 1; j < phi_max; ++j ) {
175 Node *n = phi->in(j);
176 int opcode = n->Opcode();
177 switch( opcode ) {
178 case Op_ConI:
179 {
180 if( min == NULL ) {
181 min = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
182 min_idx = j;
183 } else {
184 max = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
185 max_idx = j;
186 if( min->get_int() > max->get_int() ) {
187 // Swap min and max
188 ConNode *temp;
189 uint temp_idx;
190 temp = min; min = max; max = temp;
191 temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx;
192 }
193 }
194 }
195 break;
196 default:
197 {
198 val = n;
199 val_idx = j;
200 }
201 break;
202 }
203 }
204 }
205 return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) );
206 }
207
208
209 //------------------------------check_if_clipping------------------------------
210 // Helper function for RegionNode's identification of FP clipping
211 // Check that inputs to Region come from two IfNodes,
212 //
213 // If
214 // False True
215 // If |
216 // False True |
217 // | | |
218 // RegionNode_inputs
219 //
220 static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) {
221 top_if = NULL;
222 bot_if = NULL;
223
224 // Check control structure above RegionNode for (if ( if ) )
225 Node *in1 = region->in(1);
226 Node *in2 = region->in(2);
227 Node *in3 = region->in(3);
228 // Check that all inputs are projections
229 if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) {
230 Node *in10 = in1->in(0);
231 Node *in20 = in2->in(0);
232 Node *in30 = in3->in(0);
233 // Check that #1 and #2 are ifTrue and ifFalse from same If
234 if( in10 != NULL && in10->is_If() &&
235 in20 != NULL && in20->is_If() &&
236 in30 != NULL && in30->is_If() && in10 == in20 &&
237 (in1->Opcode() != in2->Opcode()) ) {
238 Node *in100 = in10->in(0);
239 Node *in1000 = (in100 != NULL && in100->is_Proj()) ? in100->in(0) : NULL;
240 // Check that control for in10 comes from other branch of IF from in3
241 if( in1000 != NULL && in1000->is_If() &&
242 in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) {
243 // Control pattern checks
244 top_if = (IfNode*)in1000;
245 bot_if = (IfNode*)in10;
246 }
247 }
248 }
249
250 return (top_if != NULL);
251 }
252
253
254 //------------------------------check_convf2i_clipping-------------------------
255 // Helper function for RegionNode's identification of FP clipping
256 // Verify that the value input to the phi comes from "ConvF2I; LShift; RShift"
257 static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) {
258 convf2i = NULL;
259
260 // Check for the RShiftNode
261 Node *rshift = phi->in(idx);
262 assert( rshift, "Previous checks ensure phi input is present");
263 if( rshift->Opcode() != Op_RShiftI ) { return false; }
264
265 // Check for the LShiftNode
266 Node *lshift = rshift->in(1);
267 assert( lshift, "Previous checks ensure phi input is present");
268 if( lshift->Opcode() != Op_LShiftI ) { return false; }
269
270 // Check for the ConvF2INode
271 Node *conv = lshift->in(1);
272 if( conv->Opcode() != Op_ConvF2I ) { return false; }
273
274 // Check that shift amounts are only to get sign bits set after F2I
275 jint max_cutoff = max->get_int();
276 jint min_cutoff = min->get_int();
277 jint left_shift = lshift->in(2)->get_int();
278 jint right_shift = rshift->in(2)->get_int();
279 jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1);
280 if( left_shift != right_shift ||
281 0 > left_shift || left_shift >= BitsPerJavaInteger ||
282 max_post_shift < max_cutoff ||
283 max_post_shift < -min_cutoff ) {
284 // Shifts are necessary but current transformation eliminates them
285 return false;
286 }
287
288 // OK to return the result of ConvF2I without shifting
289 convf2i = (ConvF2INode*)conv;
290 return true;
291 }
292
293
294 //------------------------------check_compare_clipping-------------------------
295 // Helper function for RegionNode's identification of FP clipping
296 static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) {
297 Node *i1 = iff->in(1);
298 if ( !i1->is_Bool() ) { return false; }
299 BoolNode *bool1 = i1->as_Bool();
300 if( less_than && bool1->_test._test != BoolTest::le ) { return false; }
301 else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; }
302 const Node *cmpF = bool1->in(1);
303 if( cmpF->Opcode() != Op_CmpF ) { return false; }
304 // Test that the float value being compared against
305 // is equivalent to the int value used as a limit
306 Node *nodef = cmpF->in(2);
307 if( nodef->Opcode() != Op_ConF ) { return false; }
308 jfloat conf = nodef->getf();
309 jint coni = limit->get_int();
310 if( ((int)conf) != coni ) { return false; }
311 input = cmpF->in(1);
312 return true;
313 }
314
315 //------------------------------is_unreachable_region--------------------------
316 // Find if the Region node is reachable from the root.
317 bool RegionNode::is_unreachable_region(PhaseGVN *phase) const {
318 assert(req() == 2, "");
319
320 // First, cut the simple case of fallthrough region when NONE of
321 // region's phis references itself directly or through a data node.
322 uint max = outcnt();
323 uint i;
324 for (i = 0; i < max; i++) {
325 Node* phi = raw_out(i);
326 if (phi != NULL && phi->is_Phi()) {
327 assert(phase->eqv(phi->in(0), this) && phi->req() == 2, "");
328 if (phi->outcnt() == 0)
329 continue; // Safe case - no loops
330 if (phi->outcnt() == 1) {
331 Node* u = phi->raw_out(0);
332 // Skip if only one use is an other Phi or Call or Uncommon trap.
333 // It is safe to consider this case as fallthrough.
334 if (u != NULL && (u->is_Phi() || u->is_CFG()))
335 continue;
336 }
337 // Check when phi references itself directly or through an other node.
338 if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe)
339 break; // Found possible unsafe data loop.
340 }
341 }
342 if (i >= max)
343 return false; // An unsafe case was NOT found - don't need graph walk.
344
345 // Unsafe case - check if the Region node is reachable from root.
346 ResourceMark rm;
347
348 Arena *a = Thread::current()->resource_area();
349 Node_List nstack(a);
350 VectorSet visited(a);
351
352 // Mark all control nodes reachable from root outputs
353 Node *n = (Node*)phase->C->root();
354 nstack.push(n);
355 visited.set(n->_idx);
356 while (nstack.size() != 0) {
357 n = nstack.pop();
358 uint max = n->outcnt();
359 for (uint i = 0; i < max; i++) {
360 Node* m = n->raw_out(i);
361 if (m != NULL && m->is_CFG()) {
362 if (phase->eqv(m, this)) {
363 return false; // We reached the Region node - it is not dead.
364 }
365 if (!visited.test_set(m->_idx))
366 nstack.push(m);
367 }
368 }
369 }
370
371 return true; // The Region node is unreachable - it is dead.
372 }
373
374 bool RegionNode::try_clean_mem_phi(PhaseGVN *phase) {
375 // Incremental inlining + PhaseStringOpts sometimes produce:
376 //
377 // cmpP with 1 top input
378 // |
379 // If
380 // / \
381 // IfFalse IfTrue /- Some Node
382 // \ / / /
383 // Region / /-MergeMem
384 // \---Phi
385 //
386 //
387 // It's expected by PhaseStringOpts that the Region goes away and is
388 // replaced by If's control input but because there's still a Phi,
389 // the Region stays in the graph. The top input from the cmpP is
390 // propagated forward and a subgraph that is useful goes away. The
391 // code below replaces the Phi with the MergeMem so that the Region
392 // is simplified.
393
394 PhiNode* phi = has_unique_phi();
395 if (phi && phi->type() == Type::MEMORY && req() == 3 && phi->is_diamond_phi(true)) {
396 MergeMemNode* m = NULL;
397 assert(phi->req() == 3, "same as region");
398 for (uint i = 1; i < 3; ++i) {
399 Node *mem = phi->in(i);
400 if (mem && mem->is_MergeMem() && in(i)->outcnt() == 1) {
401 // Nothing is control-dependent on path #i except the region itself.
402 m = mem->as_MergeMem();
403 uint j = 3 - i;
404 Node* other = phi->in(j);
405 if (other && other == m->base_memory()) {
406 // m is a successor memory to other, and is not pinned inside the diamond, so push it out.
407 // This will allow the diamond to collapse completely.
408 phase->is_IterGVN()->replace_node(phi, m);
409 return true;
410 }
411 }
412 }
413 }
414 return false;
415 }
416
417 //------------------------------Ideal------------------------------------------
418 // Return a node which is more "ideal" than the current node. Must preserve
419 // the CFG, but we can still strip out dead paths.
420 Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) {
421 if( !can_reshape && !in(0) ) return NULL; // Already degraded to a Copy
422 assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge");
423
424 // Check for RegionNode with no Phi users and both inputs come from either
425 // arm of the same IF. If found, then the control-flow split is useless.
426 bool has_phis = false;
427 if (can_reshape) { // Need DU info to check for Phi users
428 has_phis = (has_phi() != NULL); // Cache result
429 if (has_phis && try_clean_mem_phi(phase)) {
430 has_phis = false;
431 }
432
433 if (!has_phis) { // No Phi users? Nothing merging?
434 for (uint i = 1; i < req()-1; i++) {
435 Node *if1 = in(i);
436 if( !if1 ) continue;
437 Node *iff = if1->in(0);
438 if( !iff || !iff->is_If() ) continue;
439 for( uint j=i+1; j<req(); j++ ) {
440 if( in(j) && in(j)->in(0) == iff &&
441 if1->Opcode() != in(j)->Opcode() ) {
442 // Add the IF Projections to the worklist. They (and the IF itself)
443 // will be eliminated if dead.
444 phase->is_IterGVN()->add_users_to_worklist(iff);
445 set_req(i, iff->in(0));// Skip around the useless IF diamond
446 set_req(j, NULL);
447 return this; // Record progress
448 }
449 }
450 }
451 }
452 }
453
454 // Remove TOP or NULL input paths. If only 1 input path remains, this Region
455 // degrades to a copy.
456 bool add_to_worklist = false;
457 bool modified = false;
458 int cnt = 0; // Count of values merging
459 DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count
460 int del_it = 0; // The last input path we delete
461 // For all inputs...
462 for( uint i=1; i<req(); ++i ){// For all paths in
463 Node *n = in(i); // Get the input
464 if( n != NULL ) {
465 // Remove useless control copy inputs
466 if( n->is_Region() && n->as_Region()->is_copy() ) {
467 set_req(i, n->nonnull_req());
468 modified = true;
469 i--;
470 continue;
471 }
472 if( n->is_Proj() ) { // Remove useless rethrows
473 Node *call = n->in(0);
474 if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) {
475 set_req(i, call->in(0));
476 modified = true;
477 i--;
478 continue;
479 }
480 }
481 if( phase->type(n) == Type::TOP ) {
482 set_req(i, NULL); // Ignore TOP inputs
483 modified = true;
484 i--;
485 continue;
486 }
487 cnt++; // One more value merging
488
489 } else if (can_reshape) { // Else found dead path with DU info
490 PhaseIterGVN *igvn = phase->is_IterGVN();
491 del_req(i); // Yank path from self
492 del_it = i;
493 uint max = outcnt();
494 DUIterator j;
495 bool progress = true;
496 while(progress) { // Need to establish property over all users
497 progress = false;
498 for (j = outs(); has_out(j); j++) {
499 Node *n = out(j);
500 if( n->req() != req() && n->is_Phi() ) {
501 assert( n->in(0) == this, "" );
502 igvn->hash_delete(n); // Yank from hash before hacking edges
503 n->set_req_X(i,NULL,igvn);// Correct DU info
504 n->del_req(i); // Yank path from Phis
505 if( max != outcnt() ) {
506 progress = true;
507 j = refresh_out_pos(j);
508 max = outcnt();
509 }
510 }
511 }
512 }
513 add_to_worklist = true;
514 i--;
515 }
516 }
517
518 if (can_reshape && cnt == 1) {
519 // Is it dead loop?
520 // If it is LoopNopde it had 2 (+1 itself) inputs and
521 // one of them was cut. The loop is dead if it was EntryContol.
522 // Loop node may have only one input because entry path
523 // is removed in PhaseIdealLoop::Dominators().
524 assert(!this->is_Loop() || cnt_orig <= 3, "Loop node should have 3 or less inputs");
525 if ((this->is_Loop() && (del_it == LoopNode::EntryControl ||
526 (del_it == 0 && is_unreachable_region(phase)))) ||
527 (!this->is_Loop() && has_phis && is_unreachable_region(phase))) {
528 // Yes, the region will be removed during the next step below.
529 // Cut the backedge input and remove phis since no data paths left.
530 // We don't cut outputs to other nodes here since we need to put them
531 // on the worklist.
532 PhaseIterGVN *igvn = phase->is_IterGVN();
533 if (in(1)->outcnt() == 1) {
534 igvn->_worklist.push(in(1));
535 }
536 del_req(1);
537 cnt = 0;
538 assert( req() == 1, "no more inputs expected" );
539 uint max = outcnt();
540 bool progress = true;
541 Node *top = phase->C->top();
542 DUIterator j;
543 while(progress) {
544 progress = false;
545 for (j = outs(); has_out(j); j++) {
546 Node *n = out(j);
547 if( n->is_Phi() ) {
548 assert( igvn->eqv(n->in(0), this), "" );
549 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
550 // Break dead loop data path.
551 // Eagerly replace phis with top to avoid phis copies generation.
552 igvn->replace_node(n, top);
553 if( max != outcnt() ) {
554 progress = true;
555 j = refresh_out_pos(j);
556 max = outcnt();
557 }
558 }
559 }
560 }
561 add_to_worklist = true;
562 }
563 }
564 if (add_to_worklist) {
565 phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis
566 }
567
568 if( cnt <= 1 ) { // Only 1 path in?
569 set_req(0, NULL); // Null control input for region copy
570 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is.
571 // No inputs or all inputs are NULL.
572 return NULL;
573 } else if (can_reshape) { // Optimization phase - remove the node
574 PhaseIterGVN *igvn = phase->is_IterGVN();
575 // Strip mined (inner) loop is going away, remove outer loop.
576 if (is_CountedLoop() &&
577 as_Loop()->is_strip_mined()) {
578 Node* outer_sfpt = as_CountedLoop()->outer_safepoint();
579 Node* outer_out = as_CountedLoop()->outer_loop_exit();
580 if (outer_sfpt != NULL && outer_out != NULL) {
581 Node* in = outer_sfpt->in(0);
582 igvn->replace_node(outer_out, in);
583 LoopNode* outer = as_CountedLoop()->outer_loop();
584 igvn->replace_input_of(outer, LoopNode::LoopBackControl, igvn->C->top());
585 }
586 }
587 Node *parent_ctrl;
588 if( cnt == 0 ) {
589 assert( req() == 1, "no inputs expected" );
590 // During IGVN phase such region will be subsumed by TOP node
591 // so region's phis will have TOP as control node.
592 // Kill phis here to avoid it. PhiNode::is_copy() will be always false.
593 // Also set other user's input to top.
594 parent_ctrl = phase->C->top();
595 } else {
596 // The fallthrough case since we already checked dead loops above.
597 parent_ctrl = in(1);
598 assert(parent_ctrl != NULL, "Region is a copy of some non-null control");
599 assert(!igvn->eqv(parent_ctrl, this), "Close dead loop");
600 }
601 if (!add_to_worklist)
602 igvn->add_users_to_worklist(this); // Check for further allowed opts
603 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
604 Node* n = last_out(i);
605 igvn->hash_delete(n); // Remove from worklist before modifying edges
606 if( n->is_Phi() ) { // Collapse all Phis
607 // Eagerly replace phis to avoid copies generation.
608 Node* in;
609 if( cnt == 0 ) {
610 assert( n->req() == 1, "No data inputs expected" );
611 in = parent_ctrl; // replaced by top
612 } else {
613 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
614 in = n->in(1); // replaced by unique input
615 if( n->as_Phi()->is_unsafe_data_reference(in) )
616 in = phase->C->top(); // replaced by top
617 }
618 igvn->replace_node(n, in);
619 }
620 else if( n->is_Region() ) { // Update all incoming edges
621 assert( !igvn->eqv(n, this), "Must be removed from DefUse edges");
622 uint uses_found = 0;
623 for( uint k=1; k < n->req(); k++ ) {
624 if( n->in(k) == this ) {
625 n->set_req(k, parent_ctrl);
626 uses_found++;
627 }
628 }
629 if( uses_found > 1 ) { // (--i) done at the end of the loop.
630 i -= (uses_found - 1);
631 }
632 }
633 else {
634 assert( igvn->eqv(n->in(0), this), "Expect RegionNode to be control parent");
635 n->set_req(0, parent_ctrl);
636 }
637 #ifdef ASSERT
638 for( uint k=0; k < n->req(); k++ ) {
639 assert( !igvn->eqv(n->in(k), this), "All uses of RegionNode should be gone");
640 }
641 #endif
642 }
643 // Remove the RegionNode itself from DefUse info
644 igvn->remove_dead_node(this);
645 return NULL;
646 }
647 return this; // Record progress
648 }
649
650
651 // If a Region flows into a Region, merge into one big happy merge.
652 if (can_reshape) {
653 Node *m = merge_region(this, phase);
654 if (m != NULL) return m;
655 }
656
657 // Check if this region is the root of a clipping idiom on floats
658 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
659 // Check that only one use is a Phi and that it simplifies to two constants +
660 PhiNode* phi = has_unique_phi();
661 if (phi != NULL) { // One Phi user
662 // Check inputs to the Phi
663 ConNode *min;
664 ConNode *max;
665 Node *val;
666 uint min_idx;
667 uint max_idx;
668 uint val_idx;
669 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) {
670 IfNode *top_if;
671 IfNode *bot_if;
672 if( check_if_clipping( this, bot_if, top_if ) ) {
673 // Control pattern checks, now verify compares
674 Node *top_in = NULL; // value being compared against
675 Node *bot_in = NULL;
676 if( check_compare_clipping( true, bot_if, min, bot_in ) &&
677 check_compare_clipping( false, top_if, max, top_in ) ) {
678 if( bot_in == top_in ) {
679 PhaseIterGVN *gvn = phase->is_IterGVN();
680 assert( gvn != NULL, "Only had DefUse info in IterGVN");
681 // Only remaining check is that bot_in == top_in == (Phi's val + mods)
682
683 // Check for the ConvF2INode
684 ConvF2INode *convf2i;
685 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
686 convf2i->in(1) == bot_in ) {
687 // Matched pattern, including LShiftI; RShiftI, replace with integer compares
688 // max test
689 Node *cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, min ));
690 Node *boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::lt ));
691 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt ));
692 Node *if_min= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
693 Node *ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
694 // min test
695 cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, max ));
696 boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::gt ));
697 iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
698 Node *if_max= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
699 ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
700 // update input edges to region node
701 set_req_X( min_idx, if_min, gvn );
702 set_req_X( max_idx, if_max, gvn );
703 set_req_X( val_idx, ifF, gvn );
704 // remove unnecessary 'LShiftI; RShiftI' idiom
705 gvn->hash_delete(phi);
706 phi->set_req_X( val_idx, convf2i, gvn );
707 gvn->hash_find_insert(phi);
708 // Return transformed region node
709 return this;
710 }
711 }
712 }
713 }
714 }
715 }
716 }
717
718 if (can_reshape) {
719 modified |= optimize_trichotomy(phase->is_IterGVN());
720 }
721
722 return modified ? this : NULL;
723 }
724
725 //------------------------------optimize_trichotomy--------------------------
726 // Optimize nested comparisons of the following kind:
727 //
728 // int compare(int a, int b) {
729 // return (a < b) ? -1 : (a == b) ? 0 : 1;
730 // }
731 //
732 // Shape 1:
733 // if (compare(a, b) == 1) { ... } -> if (a > b) { ... }
734 //
735 // Shape 2:
736 // if (compare(a, b) == 0) { ... } -> if (a == b) { ... }
737 //
738 // Above code leads to the following IR shapes where both Ifs compare the
739 // same value and two out of three region inputs idx1 and idx2 map to
740 // the same value and control flow.
741 //
742 // (1) If (2) If
743 // / \ / \
744 // Proj Proj Proj Proj
745 // | \ | \
746 // | If | If If
747 // | / \ | / \ / \
748 // | Proj Proj | Proj Proj ==> Proj Proj
749 // | / / \ | / | /
750 // Region / \ | / | /
751 // \ / \ | / | /
752 // Region Region Region
753 //
754 // The method returns true if 'this' is modified and false otherwise.
755 bool RegionNode::optimize_trichotomy(PhaseIterGVN* igvn) {
756 int idx1 = 1, idx2 = 2;
757 Node* region = NULL;
758 if (req() == 3 && in(1) != NULL && in(2) != NULL) {
759 // Shape 1: Check if one of the inputs is a region that merges two control
760 // inputs and has no other users (especially no Phi users).
761 region = in(1)->isa_Region() ? in(1) : in(2)->isa_Region();
762 if (region == NULL || region->outcnt() != 2 || region->req() != 3) {
763 return false; // No suitable region input found
764 }
765 } else if (req() == 4) {
766 // Shape 2: Check if two control inputs map to the same value of the unique phi
767 // user and treat these as if they would come from another region (shape (1)).
768 PhiNode* phi = has_unique_phi();
769 if (phi == NULL) {
770 return false; // No unique phi user
771 }
772 if (phi->in(idx1) != phi->in(idx2)) {
773 idx2 = 3;
774 if (phi->in(idx1) != phi->in(idx2)) {
775 idx1 = 2;
776 if (phi->in(idx1) != phi->in(idx2)) {
777 return false; // No equal phi inputs found
778 }
779 }
780 }
781 assert(phi->in(idx1) == phi->in(idx2), "must be"); // Region is merging same value
782 region = this;
783 }
784 if (region == NULL || region->in(idx1) == NULL || region->in(idx2) == NULL) {
785 return false; // Region does not merge two control inputs
786 }
787 // At this point we know that region->in(idx1) and region->(idx2) map to the same
788 // value and control flow. Now search for ifs that feed into these region inputs.
789 ProjNode* proj1 = region->in(idx1)->isa_Proj();
790 ProjNode* proj2 = region->in(idx2)->isa_Proj();
791 if (proj1 == NULL || proj1->outcnt() != 1 ||
792 proj2 == NULL || proj2->outcnt() != 1) {
793 return false; // No projection inputs with region as unique user found
794 }
795 assert(proj1 != proj2, "should be different projections");
796 IfNode* iff1 = proj1->in(0)->isa_If();
797 IfNode* iff2 = proj2->in(0)->isa_If();
798 if (iff1 == NULL || iff1->outcnt() != 2 ||
799 iff2 == NULL || iff2->outcnt() != 2) {
800 return false; // No ifs found
801 }
802 if (iff1 == iff2) {
803 igvn->add_users_to_worklist(iff1); // Make sure dead if is eliminated
804 igvn->replace_input_of(region, idx1, iff1->in(0));
805 igvn->replace_input_of(region, idx2, igvn->C->top());
806 return (region == this); // Remove useless if (both projections map to the same control/value)
807 }
808 BoolNode* bol1 = iff1->in(1)->isa_Bool();
809 BoolNode* bol2 = iff2->in(1)->isa_Bool();
810 if (bol1 == NULL || bol2 == NULL) {
811 return false; // No bool inputs found
812 }
813 Node* cmp1 = bol1->in(1);
814 Node* cmp2 = bol2->in(1);
815 bool commute = false;
816 if (!cmp1->is_Cmp() || !cmp2->is_Cmp()) {
817 return false; // No comparison
818 } else if (cmp1->Opcode() == Op_CmpF || cmp1->Opcode() == Op_CmpD ||
819 cmp2->Opcode() == Op_CmpF || cmp2->Opcode() == Op_CmpD ||
820 cmp1->Opcode() == Op_CmpP || cmp1->Opcode() == Op_CmpN ||
821 cmp2->Opcode() == Op_CmpP || cmp2->Opcode() == Op_CmpN) {
822 // Floats and pointers don't exactly obey trichotomy. To be on the safe side, don't transform their tests.
823 return false;
824 } else if (cmp1 != cmp2) {
825 if (cmp1->in(1) == cmp2->in(2) &&
826 cmp1->in(2) == cmp2->in(1)) {
827 commute = true; // Same but swapped inputs, commute the test
828 } else {
829 return false; // Ifs are not comparing the same values
830 }
831 }
832 proj1 = proj1->other_if_proj();
833 proj2 = proj2->other_if_proj();
834 if (!((proj1->unique_ctrl_out() == iff2 &&
835 proj2->unique_ctrl_out() == this) ||
836 (proj2->unique_ctrl_out() == iff1 &&
837 proj1->unique_ctrl_out() == this))) {
838 return false; // Ifs are not connected through other projs
839 }
840 // Found 'iff -> proj -> iff -> proj -> this' shape where all other projs are merged
841 // through 'region' and map to the same value. Merge the boolean tests and replace
842 // the ifs by a single comparison.
843 BoolTest test1 = (proj1->_con == 1) ? bol1->_test : bol1->_test.negate();
844 BoolTest test2 = (proj2->_con == 1) ? bol2->_test : bol2->_test.negate();
845 test1 = commute ? test1.commute() : test1;
846 // After possibly commuting test1, if we can merge test1 & test2, then proj2/iff2/bol2 are the nodes to refine.
847 BoolTest::mask res = test1.merge(test2);
848 if (res == BoolTest::illegal) {
849 return false; // Unable to merge tests
850 }
851 // Adjust iff1 to always pass (only iff2 will remain)
852 igvn->replace_input_of(iff1, 1, igvn->intcon(proj1->_con));
853 if (res == BoolTest::never) {
854 // Merged test is always false, adjust iff2 to always fail
855 igvn->replace_input_of(iff2, 1, igvn->intcon(1 - proj2->_con));
856 } else {
857 // Replace bool input of iff2 with merged test
858 BoolNode* new_bol = new BoolNode(bol2->in(1), res);
859 igvn->replace_input_of(iff2, 1, igvn->transform((proj2->_con == 1) ? new_bol : new_bol->negate(igvn)));
860 }
861 return false;
862 }
863
864 const RegMask &RegionNode::out_RegMask() const {
865 return RegMask::Empty;
866 }
867
868 // Find the one non-null required input. RegionNode only
869 Node *Node::nonnull_req() const {
870 assert( is_Region(), "" );
871 for( uint i = 1; i < _cnt; i++ )
872 if( in(i) )
873 return in(i);
874 ShouldNotReachHere();
875 return NULL;
876 }
877
878
879 //=============================================================================
880 // note that these functions assume that the _adr_type field is flattened
881 uint PhiNode::hash() const {
882 const Type* at = _adr_type;
883 return TypeNode::hash() + (at ? at->hash() : 0);
884 }
885 uint PhiNode::cmp( const Node &n ) const {
886 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
887 }
888 static inline
889 const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
890 if (at == NULL || at == TypePtr::BOTTOM) return at;
891 return Compile::current()->alias_type(at)->adr_type();
892 }
893
894 //----------------------------make---------------------------------------------
895 // create a new phi with edges matching r and set (initially) to x
896 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
897 uint preds = r->req(); // Number of predecessor paths
898 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at");
899 PhiNode* p = new PhiNode(r, t, at);
900 for (uint j = 1; j < preds; j++) {
901 // Fill in all inputs, except those which the region does not yet have
902 if (r->in(j) != NULL)
903 p->init_req(j, x);
904 }
905 return p;
906 }
907 PhiNode* PhiNode::make(Node* r, Node* x) {
908 const Type* t = x->bottom_type();
909 const TypePtr* at = NULL;
910 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
911 return make(r, x, t, at);
912 }
913 PhiNode* PhiNode::make_blank(Node* r, Node* x) {
914 const Type* t = x->bottom_type();
915 const TypePtr* at = NULL;
916 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
917 return new PhiNode(r, t, at);
918 }
919
920
921 //------------------------slice_memory-----------------------------------------
922 // create a new phi with narrowed memory type
923 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
924 PhiNode* mem = (PhiNode*) clone();
925 *(const TypePtr**)&mem->_adr_type = adr_type;
926 // convert self-loops, or else we get a bad graph
927 for (uint i = 1; i < req(); i++) {
928 if ((const Node*)in(i) == this) mem->set_req(i, mem);
929 }
930 mem->verify_adr_type();
931 return mem;
932 }
933
934 //------------------------split_out_instance-----------------------------------
935 // Split out an instance type from a bottom phi.
936 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const {
937 const TypeOopPtr *t_oop = at->isa_oopptr();
938 assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr");
939 const TypePtr *t = adr_type();
940 assert(type() == Type::MEMORY &&
941 (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
942 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
943 t->is_oopptr()->cast_to_exactness(true)
944 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
945 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop),
946 "bottom or raw memory required");
947
948 // Check if an appropriate node already exists.
949 Node *region = in(0);
950 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) {
951 Node* use = region->fast_out(k);
952 if( use->is_Phi()) {
953 PhiNode *phi2 = use->as_Phi();
954 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) {
955 return phi2;
956 }
957 }
958 }
959 Compile *C = igvn->C;
960 Arena *a = Thread::current()->resource_area();
961 Node_Array node_map = new Node_Array(a);
962 Node_Stack stack(a, C->live_nodes() >> 4);
963 PhiNode *nphi = slice_memory(at);
964 igvn->register_new_node_with_optimizer( nphi );
965 node_map.map(_idx, nphi);
966 stack.push((Node *)this, 1);
967 while(!stack.is_empty()) {
968 PhiNode *ophi = stack.node()->as_Phi();
969 uint i = stack.index();
970 assert(i >= 1, "not control edge");
971 stack.pop();
972 nphi = node_map[ophi->_idx]->as_Phi();
973 for (; i < ophi->req(); i++) {
974 Node *in = ophi->in(i);
975 if (in == NULL || igvn->type(in) == Type::TOP)
976 continue;
977 Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, NULL, igvn);
978 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL;
979 if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) {
980 opt = node_map[optphi->_idx];
981 if (opt == NULL) {
982 stack.push(ophi, i);
983 nphi = optphi->slice_memory(at);
984 igvn->register_new_node_with_optimizer( nphi );
985 node_map.map(optphi->_idx, nphi);
986 ophi = optphi;
987 i = 0; // will get incremented at top of loop
988 continue;
989 }
990 }
991 nphi->set_req(i, opt);
992 }
993 }
994 return nphi;
995 }
996
997 //------------------------verify_adr_type--------------------------------------
998 #ifdef ASSERT
999 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
1000 if (visited.test_set(_idx)) return; //already visited
1001
1002 // recheck constructor invariants:
1003 verify_adr_type(false);
1004
1005 // recheck local phi/phi consistency:
1006 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
1007 "adr_type must be consistent across phi nest");
1008
1009 // walk around
1010 for (uint i = 1; i < req(); i++) {
1011 Node* n = in(i);
1012 if (n == NULL) continue;
1013 const Node* np = in(i);
1014 if (np->is_Phi()) {
1015 np->as_Phi()->verify_adr_type(visited, at);
1016 } else if (n->bottom_type() == Type::TOP
1017 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
1018 // ignore top inputs
1019 } else {
1020 const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
1021 // recheck phi/non-phi consistency at leaves:
1022 assert((nat != NULL) == (at != NULL), "");
1023 assert(nat == at || nat == TypePtr::BOTTOM,
1024 "adr_type must be consistent at leaves of phi nest");
1025 }
1026 }
1027 }
1028
1029 // Verify a whole nest of phis rooted at this one.
1030 void PhiNode::verify_adr_type(bool recursive) const {
1031 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
1032 if (Node::in_dump()) return; // muzzle asserts when printing
1033
1034 assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only");
1035
1036 if (!VerifyAliases) return; // verify thoroughly only if requested
1037
1038 assert(_adr_type == flatten_phi_adr_type(_adr_type),
1039 "Phi::adr_type must be pre-normalized");
1040
1041 if (recursive) {
1042 VectorSet visited(Thread::current()->resource_area());
1043 verify_adr_type(visited, _adr_type);
1044 }
1045 }
1046 #endif
1047
1048
1049 //------------------------------Value------------------------------------------
1050 // Compute the type of the PhiNode
1051 const Type* PhiNode::Value(PhaseGVN* phase) const {
1052 Node *r = in(0); // RegionNode
1053 if( !r ) // Copy or dead
1054 return in(1) ? phase->type(in(1)) : Type::TOP;
1055
1056 // Note: During parsing, phis are often transformed before their regions.
1057 // This means we have to use type_or_null to defend against untyped regions.
1058 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1059 return Type::TOP;
1060
1061 // Check for trip-counted loop. If so, be smarter.
1062 CountedLoopNode* l = r->is_CountedLoop() ? r->as_CountedLoop() : NULL;
1063 if (l && ((const Node*)l->phi() == this)) { // Trip counted loop!
1064 // protect against init_trip() or limit() returning NULL
1065 if (l->can_be_counted_loop(phase)) {
1066 const Node *init = l->init_trip();
1067 const Node *limit = l->limit();
1068 const Node* stride = l->stride();
1069 if (init != NULL && limit != NULL && stride != NULL) {
1070 const TypeInt* lo = phase->type(init)->isa_int();
1071 const TypeInt* hi = phase->type(limit)->isa_int();
1072 const TypeInt* stride_t = phase->type(stride)->isa_int();
1073 if (lo != NULL && hi != NULL && stride_t != NULL) { // Dying loops might have TOP here
1074 assert(stride_t->_hi >= stride_t->_lo, "bad stride type");
1075 BoolTest::mask bt = l->loopexit()->test_trip();
1076 // If the loop exit condition is "not equal", the condition
1077 // would not trigger if init > limit (if stride > 0) or if
1078 // init < limit if (stride > 0) so we can't deduce bounds
1079 // for the iv from the exit condition.
1080 if (bt != BoolTest::ne) {
1081 if (stride_t->_hi < 0) { // Down-counter loop
1082 swap(lo, hi);
1083 return TypeInt::make(MIN2(lo->_lo, hi->_lo) , hi->_hi, 3);
1084 } else if (stride_t->_lo >= 0) {
1085 return TypeInt::make(lo->_lo, MAX2(lo->_hi, hi->_hi), 3);
1086 }
1087 }
1088 }
1089 }
1090 } else if (l->in(LoopNode::LoopBackControl) != NULL &&
1091 in(LoopNode::EntryControl) != NULL &&
1092 phase->type(l->in(LoopNode::LoopBackControl)) == Type::TOP) {
1093 // During CCP, if we saturate the type of a counted loop's Phi
1094 // before the special code for counted loop above has a chance
1095 // to run (that is as long as the type of the backedge's control
1096 // is top), we might end up with non monotonic types
1097 return phase->type(in(LoopNode::EntryControl))->filter_speculative(_type);
1098 }
1099 }
1100
1101 // Until we have harmony between classes and interfaces in the type
1102 // lattice, we must tread carefully around phis which implicitly
1103 // convert the one to the other.
1104 const TypePtr* ttp = _type->make_ptr();
1105 const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL;
1106 const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_klassptr() : NULL;
1107 bool is_intf = false;
1108 if (ttip != NULL) {
1109 ciKlass* k = ttip->klass();
1110 if (k->is_loaded() && k->is_interface())
1111 is_intf = true;
1112 }
1113 if (ttkp != NULL) {
1114 ciKlass* k = ttkp->klass();
1115 if (k->is_loaded() && k->is_interface())
1116 is_intf = true;
1117 }
1118
1119 // Default case: merge all inputs
1120 const Type *t = Type::TOP; // Merged type starting value
1121 for (uint i = 1; i < req(); ++i) {// For all paths in
1122 // Reachable control path?
1123 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
1124 const Type* ti = phase->type(in(i));
1125 // We assume that each input of an interface-valued Phi is a true
1126 // subtype of that interface. This might not be true of the meet
1127 // of all the input types. The lattice is not distributive in
1128 // such cases. Ward off asserts in type.cpp by refusing to do
1129 // meets between interfaces and proper classes.
1130 const TypePtr* tip = ti->make_ptr();
1131 const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL;
1132 if (tiip) {
1133 bool ti_is_intf = false;
1134 ciKlass* k = tiip->klass();
1135 if (k->is_loaded() && k->is_interface())
1136 ti_is_intf = true;
1137 if (is_intf != ti_is_intf)
1138 { t = _type; break; }
1139 }
1140 t = t->meet_speculative(ti);
1141 }
1142 }
1143
1144 // The worst-case type (from ciTypeFlow) should be consistent with "t".
1145 // That is, we expect that "t->higher_equal(_type)" holds true.
1146 // There are various exceptions:
1147 // - Inputs which are phis might in fact be widened unnecessarily.
1148 // For example, an input might be a widened int while the phi is a short.
1149 // - Inputs might be BotPtrs but this phi is dependent on a null check,
1150 // and postCCP has removed the cast which encodes the result of the check.
1151 // - The type of this phi is an interface, and the inputs are classes.
1152 // - Value calls on inputs might produce fuzzy results.
1153 // (Occurrences of this case suggest improvements to Value methods.)
1154 //
1155 // It is not possible to see Type::BOTTOM values as phi inputs,
1156 // because the ciTypeFlow pre-pass produces verifier-quality types.
1157 const Type* ft = t->filter_speculative(_type); // Worst case type
1158
1159 #ifdef ASSERT
1160 // The following logic has been moved into TypeOopPtr::filter.
1161 const Type* jt = t->join_speculative(_type);
1162 if (jt->empty()) { // Emptied out???
1163
1164 // Check for evil case of 't' being a class and '_type' expecting an
1165 // interface. This can happen because the bytecodes do not contain
1166 // enough type info to distinguish a Java-level interface variable
1167 // from a Java-level object variable. If we meet 2 classes which
1168 // both implement interface I, but their meet is at 'j/l/O' which
1169 // doesn't implement I, we have no way to tell if the result should
1170 // be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows
1171 // into a Phi which "knows" it's an Interface type we'll have to
1172 // uplift the type.
1173 if (!t->empty() && ttip && ttip->is_loaded() && ttip->klass()->is_interface()) {
1174 assert(ft == _type, ""); // Uplift to interface
1175 } else if (!t->empty() && ttkp && ttkp->is_loaded() && ttkp->klass()->is_interface()) {
1176 assert(ft == _type, ""); // Uplift to interface
1177 } else {
1178 // We also have to handle 'evil cases' of interface- vs. class-arrays
1179 Type::get_arrays_base_elements(jt, _type, NULL, &ttip);
1180 if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
1181 assert(ft == _type, ""); // Uplift to array of interface
1182 } else {
1183 // Otherwise it's something stupid like non-overlapping int ranges
1184 // found on dying counted loops.
1185 assert(ft == Type::TOP, ""); // Canonical empty value
1186 }
1187 }
1188 }
1189
1190 else {
1191
1192 // If we have an interface-typed Phi and we narrow to a class type, the join
1193 // should report back the class. However, if we have a J/L/Object
1194 // class-typed Phi and an interface flows in, it's possible that the meet &
1195 // join report an interface back out. This isn't possible but happens
1196 // because the type system doesn't interact well with interfaces.
1197 const TypePtr *jtp = jt->make_ptr();
1198 const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL;
1199 const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_klassptr() : NULL;
1200 if( jtip && ttip ) {
1201 if( jtip->is_loaded() && jtip->klass()->is_interface() &&
1202 ttip->is_loaded() && !ttip->klass()->is_interface() ) {
1203 assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) ||
1204 ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), "");
1205 jt = ft;
1206 }
1207 }
1208 if( jtkp && ttkp ) {
1209 if( jtkp->is_loaded() && jtkp->klass()->is_interface() &&
1210 !jtkp->klass_is_exact() && // Keep exact interface klass (6894807)
1211 ttkp->is_loaded() && !ttkp->klass()->is_interface() ) {
1212 assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) ||
1213 ft->isa_narrowklass() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), "");
1214 jt = ft;
1215 }
1216 }
1217 if (jt != ft && jt->base() == ft->base()) {
1218 if (jt->isa_int() &&
1219 jt->is_int()->_lo == ft->is_int()->_lo &&
1220 jt->is_int()->_hi == ft->is_int()->_hi)
1221 jt = ft;
1222 if (jt->isa_long() &&
1223 jt->is_long()->_lo == ft->is_long()->_lo &&
1224 jt->is_long()->_hi == ft->is_long()->_hi)
1225 jt = ft;
1226 }
1227 if (jt != ft) {
1228 tty->print("merge type: "); t->dump(); tty->cr();
1229 tty->print("kill type: "); _type->dump(); tty->cr();
1230 tty->print("join type: "); jt->dump(); tty->cr();
1231 tty->print("filter type: "); ft->dump(); tty->cr();
1232 }
1233 assert(jt == ft, "");
1234 }
1235 #endif //ASSERT
1236
1237 // Deal with conversion problems found in data loops.
1238 ft = phase->saturate(ft, phase->type_or_null(this), _type);
1239
1240 return ft;
1241 }
1242
1243
1244 //------------------------------is_diamond_phi---------------------------------
1245 // Does this Phi represent a simple well-shaped diamond merge? Return the
1246 // index of the true path or 0 otherwise.
1247 // If check_control_only is true, do not inspect the If node at the
1248 // top, and return -1 (not an edge number) on success.
1249 int PhiNode::is_diamond_phi(bool check_control_only) const {
1250 // Check for a 2-path merge
1251 Node *region = in(0);
1252 if( !region ) return 0;
1253 if( region->req() != 3 ) return 0;
1254 if( req() != 3 ) return 0;
1255 // Check that both paths come from the same If
1256 Node *ifp1 = region->in(1);
1257 Node *ifp2 = region->in(2);
1258 if( !ifp1 || !ifp2 ) return 0;
1259 Node *iff = ifp1->in(0);
1260 if( !iff || !iff->is_If() ) return 0;
1261 if( iff != ifp2->in(0) ) return 0;
1262 if (check_control_only) return -1;
1263 // Check for a proper bool/cmp
1264 const Node *b = iff->in(1);
1265 if( !b->is_Bool() ) return 0;
1266 const Node *cmp = b->in(1);
1267 if( !cmp->is_Cmp() ) return 0;
1268
1269 // Check for branching opposite expected
1270 if( ifp2->Opcode() == Op_IfTrue ) {
1271 assert( ifp1->Opcode() == Op_IfFalse, "" );
1272 return 2;
1273 } else {
1274 assert( ifp1->Opcode() == Op_IfTrue, "" );
1275 return 1;
1276 }
1277 }
1278
1279 //----------------------------check_cmove_id-----------------------------------
1280 // Check for CMove'ing a constant after comparing against the constant.
1281 // Happens all the time now, since if we compare equality vs a constant in
1282 // the parser, we "know" the variable is constant on one path and we force
1283 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
1284 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more
1285 // general in that we don't need constants. Since CMove's are only inserted
1286 // in very special circumstances, we do it here on generic Phi's.
1287 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
1288 assert(true_path !=0, "only diamond shape graph expected");
1289
1290 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1291 // phi->region->if_proj->ifnode->bool->cmp
1292 Node* region = in(0);
1293 Node* iff = region->in(1)->in(0);
1294 BoolNode* b = iff->in(1)->as_Bool();
1295 Node* cmp = b->in(1);
1296 Node* tval = in(true_path);
1297 Node* fval = in(3-true_path);
1298 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
1299 if (id == NULL)
1300 return NULL;
1301
1302 // Either value might be a cast that depends on a branch of 'iff'.
1303 // Since the 'id' value will float free of the diamond, either
1304 // decast or return failure.
1305 Node* ctl = id->in(0);
1306 if (ctl != NULL && ctl->in(0) == iff) {
1307 if (id->is_ConstraintCast()) {
1308 return id->in(1);
1309 } else {
1310 // Don't know how to disentangle this value.
1311 return NULL;
1312 }
1313 }
1314
1315 return id;
1316 }
1317
1318 //------------------------------Identity---------------------------------------
1319 // Check for Region being Identity.
1320 Node* PhiNode::Identity(PhaseGVN* phase) {
1321 // Check for no merging going on
1322 // (There used to be special-case code here when this->region->is_Loop.
1323 // It would check for a tributary phi on the backedge that the main phi
1324 // trivially, perhaps with a single cast. The unique_input method
1325 // does all this and more, by reducing such tributaries to 'this'.)
1326 Node* uin = unique_input(phase, false);
1327 if (uin != NULL) {
1328 return uin;
1329 }
1330
1331 int true_path = is_diamond_phi();
1332 if (true_path != 0) {
1333 Node* id = is_cmove_id(phase, true_path);
1334 if (id != NULL) return id;
1335 }
1336
1337 return this; // No identity
1338 }
1339
1340 //-----------------------------unique_input------------------------------------
1341 // Find the unique value, discounting top, self-loops, and casts.
1342 // Return top if there are no inputs, and self if there are multiple.
1343 Node* PhiNode::unique_input(PhaseTransform* phase, bool uncast) {
1344 // 1) One unique direct input,
1345 // or if uncast is true:
1346 // 2) some of the inputs have an intervening ConstraintCast
1347 // 3) an input is a self loop
1348 //
1349 // 1) input or 2) input or 3) input __
1350 // / \ / \ \ / \
1351 // \ / | cast phi cast
1352 // phi \ / / \ /
1353 // phi / --
1354
1355 Node* r = in(0); // RegionNode
1356 if (r == NULL) return in(1); // Already degraded to a Copy
1357 Node* input = NULL; // The unique direct input (maybe uncasted = ConstraintCasts removed)
1358
1359 for (uint i = 1, cnt = req(); i < cnt; ++i) {
1360 Node* rc = r->in(i);
1361 if (rc == NULL || phase->type(rc) == Type::TOP)
1362 continue; // ignore unreachable control path
1363 Node* n = in(i);
1364 if (n == NULL)
1365 continue;
1366 Node* un = n;
1367 if (uncast) {
1368 #ifdef ASSERT
1369 Node* m = un->uncast();
1370 #endif
1371 while (un != NULL && un->req() == 2 && un->is_ConstraintCast()) {
1372 Node* next = un->in(1);
1373 if (phase->type(next)->isa_rawptr() && phase->type(un)->isa_oopptr()) {
1374 // risk exposing raw ptr at safepoint
1375 break;
1376 }
1377 un = next;
1378 }
1379 assert(m == un || un->in(1) == m, "Only expected at CheckCastPP from allocation");
1380 }
1381 if (un == NULL || un == this || phase->type(un) == Type::TOP) {
1382 continue; // ignore if top, or in(i) and "this" are in a data cycle
1383 }
1384 // Check for a unique input (maybe uncasted)
1385 if (input == NULL) {
1386 input = un;
1387 } else if (input != un) {
1388 input = NodeSentinel; // no unique input
1389 }
1390 }
1391 if (input == NULL) {
1392 return phase->C->top(); // no inputs
1393 }
1394
1395 if (input != NodeSentinel) {
1396 return input; // one unique direct input
1397 }
1398
1399 // Nothing.
1400 return NULL;
1401 }
1402
1403 //------------------------------is_x2logic-------------------------------------
1404 // Check for simple convert-to-boolean pattern
1405 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
1406 // Convert Phi to an ConvIB.
1407 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
1408 assert(true_path !=0, "only diamond shape graph expected");
1409 // Convert the true/false index into an expected 0/1 return.
1410 // Map 2->0 and 1->1.
1411 int flipped = 2-true_path;
1412
1413 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1414 // phi->region->if_proj->ifnode->bool->cmp
1415 Node *region = phi->in(0);
1416 Node *iff = region->in(1)->in(0);
1417 BoolNode *b = (BoolNode*)iff->in(1);
1418 const CmpNode *cmp = (CmpNode*)b->in(1);
1419
1420 Node *zero = phi->in(1);
1421 Node *one = phi->in(2);
1422 const Type *tzero = phase->type( zero );
1423 const Type *tone = phase->type( one );
1424
1425 // Check for compare vs 0
1426 const Type *tcmp = phase->type(cmp->in(2));
1427 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
1428 // Allow cmp-vs-1 if the other input is bounded by 0-1
1429 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
1430 return NULL;
1431 flipped = 1-flipped; // Test is vs 1 instead of 0!
1432 }
1433
1434 // Check for setting zero/one opposite expected
1435 if( tzero == TypeInt::ZERO ) {
1436 if( tone == TypeInt::ONE ) {
1437 } else return NULL;
1438 } else if( tzero == TypeInt::ONE ) {
1439 if( tone == TypeInt::ZERO ) {
1440 flipped = 1-flipped;
1441 } else return NULL;
1442 } else return NULL;
1443
1444 // Check for boolean test backwards
1445 if( b->_test._test == BoolTest::ne ) {
1446 } else if( b->_test._test == BoolTest::eq ) {
1447 flipped = 1-flipped;
1448 } else return NULL;
1449
1450 // Build int->bool conversion
1451 Node *in1 = cmp->in(1);
1452 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1453 in1 = bs->step_over_gc_barrier(in1);
1454 Node *n = new Conv2BNode(in1);
1455 if( flipped )
1456 n = new XorINode( phase->transform(n), phase->intcon(1) );
1457
1458 return n;
1459 }
1460
1461 //------------------------------is_cond_add------------------------------------
1462 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;"
1463 // To be profitable the control flow has to disappear; there can be no other
1464 // values merging here. We replace the test-and-branch with:
1465 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by
1466 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
1467 // Then convert Y to 0-or-Y and finally add.
1468 // This is a key transform for SpecJava _201_compress.
1469 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
1470 assert(true_path !=0, "only diamond shape graph expected");
1471
1472 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1473 // phi->region->if_proj->ifnode->bool->cmp
1474 RegionNode *region = (RegionNode*)phi->in(0);
1475 Node *iff = region->in(1)->in(0);
1476 BoolNode* b = iff->in(1)->as_Bool();
1477 const CmpNode *cmp = (CmpNode*)b->in(1);
1478
1479 // Make sure only merging this one phi here
1480 if (region->has_unique_phi() != phi) return NULL;
1481
1482 // Make sure each arm of the diamond has exactly one output, which we assume
1483 // is the region. Otherwise, the control flow won't disappear.
1484 if (region->in(1)->outcnt() != 1) return NULL;
1485 if (region->in(2)->outcnt() != 1) return NULL;
1486
1487 // Check for "(P < Q)" of type signed int
1488 if (b->_test._test != BoolTest::lt) return NULL;
1489 if (cmp->Opcode() != Op_CmpI) return NULL;
1490
1491 Node *p = cmp->in(1);
1492 Node *q = cmp->in(2);
1493 Node *n1 = phi->in( true_path);
1494 Node *n2 = phi->in(3-true_path);
1495
1496 int op = n1->Opcode();
1497 if( op != Op_AddI // Need zero as additive identity
1498 /*&&op != Op_SubI &&
1499 op != Op_AddP &&
1500 op != Op_XorI &&
1501 op != Op_OrI*/ )
1502 return NULL;
1503
1504 Node *x = n2;
1505 Node *y = NULL;
1506 if( x == n1->in(1) ) {
1507 y = n1->in(2);
1508 } else if( x == n1->in(2) ) {
1509 y = n1->in(1);
1510 } else return NULL;
1511
1512 // Not so profitable if compare and add are constants
1513 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
1514 return NULL;
1515
1516 Node *cmplt = phase->transform( new CmpLTMaskNode(p,q) );
1517 Node *j_and = phase->transform( new AndINode(cmplt,y) );
1518 return new AddINode(j_and,x);
1519 }
1520
1521 //------------------------------is_absolute------------------------------------
1522 // Check for absolute value.
1523 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
1524 assert(true_path !=0, "only diamond shape graph expected");
1525
1526 int cmp_zero_idx = 0; // Index of compare input where to look for zero
1527 int phi_x_idx = 0; // Index of phi input where to find naked x
1528
1529 // ABS ends with the merge of 2 control flow paths.
1530 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
1531 int false_path = 3 - true_path;
1532
1533 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1534 // phi->region->if_proj->ifnode->bool->cmp
1535 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
1536
1537 // Check bool sense
1538 switch( bol->_test._test ) {
1539 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break;
1540 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1541 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1542 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
1543 default: return NULL; break;
1544 }
1545
1546 // Test is next
1547 Node *cmp = bol->in(1);
1548 const Type *tzero = NULL;
1549 switch( cmp->Opcode() ) {
1550 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS
1551 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS
1552 default: return NULL;
1553 }
1554
1555 // Find zero input of compare; the other input is being abs'd
1556 Node *x = NULL;
1557 bool flip = false;
1558 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
1559 x = cmp->in(3 - cmp_zero_idx);
1560 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
1561 // The test is inverted, we should invert the result...
1562 x = cmp->in(cmp_zero_idx);
1563 flip = true;
1564 } else {
1565 return NULL;
1566 }
1567
1568 // Next get the 2 pieces being selected, one is the original value
1569 // and the other is the negated value.
1570 if( phi_root->in(phi_x_idx) != x ) return NULL;
1571
1572 // Check other phi input for subtract node
1573 Node *sub = phi_root->in(3 - phi_x_idx);
1574
1575 // Allow only Sub(0,X) and fail out for all others; Neg is not OK
1576 if( tzero == TypeF::ZERO ) {
1577 if( sub->Opcode() != Op_SubF ||
1578 sub->in(2) != x ||
1579 phase->type(sub->in(1)) != tzero ) return NULL;
1580 x = new AbsFNode(x);
1581 if (flip) {
1582 x = new SubFNode(sub->in(1), phase->transform(x));
1583 }
1584 } else {
1585 if( sub->Opcode() != Op_SubD ||
1586 sub->in(2) != x ||
1587 phase->type(sub->in(1)) != tzero ) return NULL;
1588 x = new AbsDNode(x);
1589 if (flip) {
1590 x = new SubDNode(sub->in(1), phase->transform(x));
1591 }
1592 }
1593
1594 return x;
1595 }
1596
1597 //------------------------------split_once-------------------------------------
1598 // Helper for split_flow_path
1599 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
1600 igvn->hash_delete(n); // Remove from hash before hacking edges
1601
1602 uint j = 1;
1603 for (uint i = phi->req()-1; i > 0; i--) {
1604 if (phi->in(i) == val) { // Found a path with val?
1605 // Add to NEW Region/Phi, no DU info
1606 newn->set_req( j++, n->in(i) );
1607 // Remove from OLD Region/Phi
1608 n->del_req(i);
1609 }
1610 }
1611
1612 // Register the new node but do not transform it. Cannot transform until the
1613 // entire Region/Phi conglomerate has been hacked as a single huge transform.
1614 igvn->register_new_node_with_optimizer( newn );
1615
1616 // Now I can point to the new node.
1617 n->add_req(newn);
1618 igvn->_worklist.push(n);
1619 }
1620
1621 //------------------------------split_flow_path--------------------------------
1622 // Check for merging identical values and split flow paths
1623 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) {
1624 BasicType bt = phi->type()->basic_type();
1625 if( bt == T_ILLEGAL || type2size[bt] <= 0 )
1626 return NULL; // Bail out on funny non-value stuff
1627 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a
1628 return NULL; // third unequal input to be worth doing
1629
1630 // Scan for a constant
1631 uint i;
1632 for( i = 1; i < phi->req()-1; i++ ) {
1633 Node *n = phi->in(i);
1634 if( !n ) return NULL;
1635 if( phase->type(n) == Type::TOP ) return NULL;
1636 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN || n->Opcode() == Op_ConNKlass )
1637 break;
1638 }
1639 if( i >= phi->req() ) // Only split for constants
1640 return NULL;
1641
1642 Node *val = phi->in(i); // Constant to split for
1643 uint hit = 0; // Number of times it occurs
1644 Node *r = phi->region();
1645
1646 for( ; i < phi->req(); i++ ){ // Count occurrences of constant
1647 Node *n = phi->in(i);
1648 if( !n ) return NULL;
1649 if( phase->type(n) == Type::TOP ) return NULL;
1650 if( phi->in(i) == val ) {
1651 hit++;
1652 if (PhaseIdealLoop::find_predicate(r->in(i)) != NULL) {
1653 return NULL; // don't split loop entry path
1654 }
1655 }
1656 }
1657
1658 if( hit <= 1 || // Make sure we find 2 or more
1659 hit == phi->req()-1 ) // and not ALL the same value
1660 return NULL;
1661
1662 // Now start splitting out the flow paths that merge the same value.
1663 // Split first the RegionNode.
1664 PhaseIterGVN *igvn = phase->is_IterGVN();
1665 RegionNode *newr = new RegionNode(hit+1);
1666 split_once(igvn, phi, val, r, newr);
1667
1668 // Now split all other Phis than this one
1669 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) {
1670 Node* phi2 = r->fast_out(k);
1671 if( phi2->is_Phi() && phi2->as_Phi() != phi ) {
1672 PhiNode *newphi = PhiNode::make_blank(newr, phi2);
1673 split_once(igvn, phi, val, phi2, newphi);
1674 }
1675 }
1676
1677 // Clean up this guy
1678 igvn->hash_delete(phi);
1679 for( i = phi->req()-1; i > 0; i-- ) {
1680 if( phi->in(i) == val ) {
1681 phi->del_req(i);
1682 }
1683 }
1684 phi->add_req(val);
1685
1686 return phi;
1687 }
1688
1689 //=============================================================================
1690 //------------------------------simple_data_loop_check-------------------------
1691 // Try to determining if the phi node in a simple safe/unsafe data loop.
1692 // Returns:
1693 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
1694 // Safe - safe case when the phi and it's inputs reference only safe data
1695 // nodes;
1696 // Unsafe - the phi and it's inputs reference unsafe data nodes but there
1697 // is no reference back to the phi - need a graph walk
1698 // to determine if it is in a loop;
1699 // UnsafeLoop - unsafe case when the phi references itself directly or through
1700 // unsafe data node.
1701 // Note: a safe data node is a node which could/never reference itself during
1702 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP.
1703 // I mark Phi nodes as safe node not only because they can reference itself
1704 // but also to prevent mistaking the fallthrough case inside an outer loop
1705 // as dead loop when the phi references itselfs through an other phi.
1706 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const {
1707 // It is unsafe loop if the phi node references itself directly.
1708 if (in == (Node*)this)
1709 return UnsafeLoop; // Unsafe loop
1710 // Unsafe loop if the phi node references itself through an unsafe data node.
1711 // Exclude cases with null inputs or data nodes which could reference
1712 // itself (safe for dead loops).
1713 if (in != NULL && !in->is_dead_loop_safe()) {
1714 // Check inputs of phi's inputs also.
1715 // It is much less expensive then full graph walk.
1716 uint cnt = in->req();
1717 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1;
1718 for (; i < cnt; ++i) {
1719 Node* m = in->in(i);
1720 if (m == (Node*)this)
1721 return UnsafeLoop; // Unsafe loop
1722 if (m != NULL && !m->is_dead_loop_safe()) {
1723 // Check the most common case (about 30% of all cases):
1724 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con).
1725 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL;
1726 if (m1 == (Node*)this)
1727 return UnsafeLoop; // Unsafe loop
1728 if (m1 != NULL && m1 == m->in(2) &&
1729 m1->is_dead_loop_safe() && m->in(3)->is_Con()) {
1730 continue; // Safe case
1731 }
1732 // The phi references an unsafe node - need full analysis.
1733 return Unsafe;
1734 }
1735 }
1736 }
1737 return Safe; // Safe case - we can optimize the phi node.
1738 }
1739
1740 //------------------------------is_unsafe_data_reference-----------------------
1741 // If phi can be reached through the data input - it is data loop.
1742 bool PhiNode::is_unsafe_data_reference(Node *in) const {
1743 assert(req() > 1, "");
1744 // First, check simple cases when phi references itself directly or
1745 // through an other node.
1746 LoopSafety safety = simple_data_loop_check(in);
1747 if (safety == UnsafeLoop)
1748 return true; // phi references itself - unsafe loop
1749 else if (safety == Safe)
1750 return false; // Safe case - phi could be replaced with the unique input.
1751
1752 // Unsafe case when we should go through data graph to determine
1753 // if the phi references itself.
1754
1755 ResourceMark rm;
1756
1757 Arena *a = Thread::current()->resource_area();
1758 Node_List nstack(a);
1759 VectorSet visited(a);
1760
1761 nstack.push(in); // Start with unique input.
1762 visited.set(in->_idx);
1763 while (nstack.size() != 0) {
1764 Node* n = nstack.pop();
1765 uint cnt = n->req();
1766 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1;
1767 for (; i < cnt; i++) {
1768 Node* m = n->in(i);
1769 if (m == (Node*)this) {
1770 return true; // Data loop
1771 }
1772 if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases.
1773 if (!visited.test_set(m->_idx))
1774 nstack.push(m);
1775 }
1776 }
1777 }
1778 return false; // The phi is not reachable from its inputs
1779 }
1780
1781
1782 //------------------------------Ideal------------------------------------------
1783 // Return a node which is more "ideal" than the current node. Must preserve
1784 // the CFG, but we can still strip out dead paths.
1785 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1786 // The next should never happen after 6297035 fix.
1787 if( is_copy() ) // Already degraded to a Copy ?
1788 return NULL; // No change
1789
1790 Node *r = in(0); // RegionNode
1791 assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge");
1792
1793 // Note: During parsing, phis are often transformed before their regions.
1794 // This means we have to use type_or_null to defend against untyped regions.
1795 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1796 return NULL; // No change
1797
1798 Node *top = phase->C->top();
1799 bool new_phi = (outcnt() == 0); // transforming new Phi
1800 // No change for igvn if new phi is not hooked
1801 if (new_phi && can_reshape)
1802 return NULL;
1803
1804 // The are 2 situations when only one valid phi's input is left
1805 // (in addition to Region input).
1806 // One: region is not loop - replace phi with this input.
1807 // Two: region is loop - replace phi with top since this data path is dead
1808 // and we need to break the dead data loop.
1809 Node* progress = NULL; // Record if any progress made
1810 for( uint j = 1; j < req(); ++j ){ // For all paths in
1811 // Check unreachable control paths
1812 Node* rc = r->in(j);
1813 Node* n = in(j); // Get the input
1814 if (rc == NULL || phase->type(rc) == Type::TOP) {
1815 if (n != top) { // Not already top?
1816 PhaseIterGVN *igvn = phase->is_IterGVN();
1817 if (can_reshape && igvn != NULL) {
1818 igvn->_worklist.push(r);
1819 }
1820 // Nuke it down
1821 if (can_reshape) {
1822 set_req_X(j, top, igvn);
1823 } else {
1824 set_req(j, top);
1825 }
1826 progress = this; // Record progress
1827 }
1828 }
1829 }
1830
1831 if (can_reshape && outcnt() == 0) {
1832 // set_req() above may kill outputs if Phi is referenced
1833 // only by itself on the dead (top) control path.
1834 return top;
1835 }
1836
1837 bool uncasted = false;
1838 Node* uin = unique_input(phase, false);
1839 if (uin == NULL && can_reshape) {
1840 uncasted = true;
1841 uin = unique_input(phase, true);
1842 }
1843 if (uin == top) { // Simplest case: no alive inputs.
1844 if (can_reshape) // IGVN transformation
1845 return top;
1846 else
1847 return NULL; // Identity will return TOP
1848 } else if (uin != NULL) {
1849 // Only one not-NULL unique input path is left.
1850 // Determine if this input is backedge of a loop.
1851 // (Skip new phis which have no uses and dead regions).
1852 if (outcnt() > 0 && r->in(0) != NULL) {
1853 // First, take the short cut when we know it is a loop and
1854 // the EntryControl data path is dead.
1855 // Loop node may have only one input because entry path
1856 // is removed in PhaseIdealLoop::Dominators().
1857 assert(!r->is_Loop() || r->req() <= 3, "Loop node should have 3 or less inputs");
1858 bool is_loop = (r->is_Loop() && r->req() == 3);
1859 // Then, check if there is a data loop when phi references itself directly
1860 // or through other data nodes.
1861 if ((is_loop && !uin->eqv_uncast(in(LoopNode::EntryControl))) ||
1862 (!is_loop && is_unsafe_data_reference(uin))) {
1863 // Break this data loop to avoid creation of a dead loop.
1864 if (can_reshape) {
1865 return top;
1866 } else {
1867 // We can't return top if we are in Parse phase - cut inputs only
1868 // let Identity to handle the case.
1869 replace_edge(uin, top);
1870 return NULL;
1871 }
1872 }
1873 }
1874
1875 if (uncasted) {
1876 // Add cast nodes between the phi to be removed and its unique input.
1877 // Wait until after parsing for the type information to propagate from the casts.
1878 assert(can_reshape, "Invalid during parsing");
1879 const Type* phi_type = bottom_type();
1880 assert(phi_type->isa_int() || phi_type->isa_ptr(), "bad phi type");
1881 // Add casts to carry the control dependency of the Phi that is
1882 // going away
1883 Node* cast = NULL;
1884 if (phi_type->isa_int()) {
1885 cast = ConstraintCastNode::make_cast(Op_CastII, r, uin, phi_type, true);
1886 } else {
1887 const Type* uin_type = phase->type(uin);
1888 if (!phi_type->isa_oopptr() && !uin_type->isa_oopptr()) {
1889 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true);
1890 } else {
1891 // Use a CastPP for a cast to not null and a CheckCastPP for
1892 // a cast to a new klass (and both if both null-ness and
1893 // klass change).
1894
1895 // If the type of phi is not null but the type of uin may be
1896 // null, uin's type must be casted to not null
1897 if (phi_type->join(TypePtr::NOTNULL) == phi_type->remove_speculative() &&
1898 uin_type->join(TypePtr::NOTNULL) != uin_type->remove_speculative()) {
1899 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, TypePtr::NOTNULL, true);
1900 }
1901
1902 // If the type of phi and uin, both casted to not null,
1903 // differ the klass of uin must be (check)cast'ed to match
1904 // that of phi
1905 if (phi_type->join_speculative(TypePtr::NOTNULL) != uin_type->join_speculative(TypePtr::NOTNULL)) {
1906 Node* n = uin;
1907 if (cast != NULL) {
1908 cast = phase->transform(cast);
1909 n = cast;
1910 }
1911 cast = ConstraintCastNode::make_cast(Op_CheckCastPP, r, n, phi_type, true);
1912 }
1913 if (cast == NULL) {
1914 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true);
1915 }
1916 }
1917 }
1918 assert(cast != NULL, "cast should be set");
1919 cast = phase->transform(cast);
1920 // set all inputs to the new cast(s) so the Phi is removed by Identity
1921 PhaseIterGVN* igvn = phase->is_IterGVN();
1922 for (uint i = 1; i < req(); i++) {
1923 set_req_X(i, cast, igvn);
1924 }
1925 uin = cast;
1926 }
1927
1928 // One unique input.
1929 debug_only(Node* ident = Identity(phase));
1930 // The unique input must eventually be detected by the Identity call.
1931 #ifdef ASSERT
1932 if (ident != uin && !ident->is_top()) {
1933 // print this output before failing assert
1934 r->dump(3);
1935 this->dump(3);
1936 ident->dump();
1937 uin->dump();
1938 }
1939 #endif
1940 assert(ident == uin || ident->is_top(), "Identity must clean this up");
1941 return NULL;
1942 }
1943
1944 Node* opt = NULL;
1945 int true_path = is_diamond_phi();
1946 if( true_path != 0 ) {
1947 // Check for CMove'ing identity. If it would be unsafe,
1948 // handle it here. In the safe case, let Identity handle it.
1949 Node* unsafe_id = is_cmove_id(phase, true_path);
1950 if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) )
1951 opt = unsafe_id;
1952
1953 // Check for simple convert-to-boolean pattern
1954 if( opt == NULL )
1955 opt = is_x2logic(phase, this, true_path);
1956
1957 // Check for absolute value
1958 if( opt == NULL )
1959 opt = is_absolute(phase, this, true_path);
1960
1961 // Check for conditional add
1962 if( opt == NULL && can_reshape )
1963 opt = is_cond_add(phase, this, true_path);
1964
1965 // These 4 optimizations could subsume the phi:
1966 // have to check for a dead data loop creation.
1967 if( opt != NULL ) {
1968 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) {
1969 // Found dead loop.
1970 if( can_reshape )
1971 return top;
1972 // We can't return top if we are in Parse phase - cut inputs only
1973 // to stop further optimizations for this phi. Identity will return TOP.
1974 assert(req() == 3, "only diamond merge phi here");
1975 set_req(1, top);
1976 set_req(2, top);
1977 return NULL;
1978 } else {
1979 return opt;
1980 }
1981 }
1982 }
1983
1984 // Check for merging identical values and split flow paths
1985 if (can_reshape) {
1986 opt = split_flow_path(phase, this);
1987 // This optimization only modifies phi - don't need to check for dead loop.
1988 assert(opt == NULL || phase->eqv(opt, this), "do not elide phi");
1989 if (opt != NULL) return opt;
1990 }
1991
1992 if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) {
1993 // Try to undo Phi of AddP:
1994 // (Phi (AddP base base y) (AddP base2 base2 y))
1995 // becomes:
1996 // newbase := (Phi base base2)
1997 // (AddP newbase newbase y)
1998 //
1999 // This occurs as a result of unsuccessful split_thru_phi and
2000 // interferes with taking advantage of addressing modes. See the
2001 // clone_shift_expressions code in matcher.cpp
2002 Node* addp = in(1);
2003 const Type* type = addp->in(AddPNode::Base)->bottom_type();
2004 Node* y = addp->in(AddPNode::Offset);
2005 if (y != NULL && addp->in(AddPNode::Base) == addp->in(AddPNode::Address)) {
2006 // make sure that all the inputs are similar to the first one,
2007 // i.e. AddP with base == address and same offset as first AddP
2008 bool doit = true;
2009 for (uint i = 2; i < req(); i++) {
2010 if (in(i) == NULL ||
2011 in(i)->Opcode() != Op_AddP ||
2012 in(i)->in(AddPNode::Base) != in(i)->in(AddPNode::Address) ||
2013 in(i)->in(AddPNode::Offset) != y) {
2014 doit = false;
2015 break;
2016 }
2017 // Accumulate type for resulting Phi
2018 type = type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type());
2019 }
2020 Node* base = NULL;
2021 if (doit) {
2022 // Check for neighboring AddP nodes in a tree.
2023 // If they have a base, use that it.
2024 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) {
2025 Node* u = this->fast_out(k);
2026 if (u->is_AddP()) {
2027 Node* base2 = u->in(AddPNode::Base);
2028 if (base2 != NULL && !base2->is_top()) {
2029 if (base == NULL)
2030 base = base2;
2031 else if (base != base2)
2032 { doit = false; break; }
2033 }
2034 }
2035 }
2036 }
2037 if (doit) {
2038 if (base == NULL) {
2039 base = new PhiNode(in(0), type, NULL);
2040 for (uint i = 1; i < req(); i++) {
2041 base->init_req(i, in(i)->in(AddPNode::Base));
2042 }
2043 phase->is_IterGVN()->register_new_node_with_optimizer(base);
2044 }
2045 return new AddPNode(base, base, y);
2046 }
2047 }
2048 }
2049
2050 // Split phis through memory merges, so that the memory merges will go away.
2051 // Piggy-back this transformation on the search for a unique input....
2052 // It will be as if the merged memory is the unique value of the phi.
2053 // (Do not attempt this optimization unless parsing is complete.
2054 // It would make the parser's memory-merge logic sick.)
2055 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.)
2056 if (progress == NULL && can_reshape && type() == Type::MEMORY) {
2057 // see if this phi should be sliced
2058 uint merge_width = 0;
2059 bool saw_self = false;
2060 for( uint i=1; i<req(); ++i ) {// For all paths in
2061 Node *ii = in(i);
2062 // TOP inputs should not be counted as safe inputs because if the
2063 // Phi references itself through all other inputs then splitting the
2064 // Phi through memory merges would create dead loop at later stage.
2065 if (ii == top) {
2066 return NULL; // Delay optimization until graph is cleaned.
2067 }
2068 if (ii->is_MergeMem()) {
2069 MergeMemNode* n = ii->as_MergeMem();
2070 merge_width = MAX2(merge_width, n->req());
2071 saw_self = saw_self || phase->eqv(n->base_memory(), this);
2072 }
2073 }
2074
2075 // This restriction is temporarily necessary to ensure termination:
2076 if (!saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0;
2077
2078 if (merge_width > Compile::AliasIdxRaw) {
2079 // found at least one non-empty MergeMem
2080 const TypePtr* at = adr_type();
2081 if (at != TypePtr::BOTTOM) {
2082 // Patch the existing phi to select an input from the merge:
2083 // Phi:AT1(...MergeMem(m0, m1, m2)...) into
2084 // Phi:AT1(...m1...)
2085 int alias_idx = phase->C->get_alias_index(at);
2086 for (uint i=1; i<req(); ++i) {
2087 Node *ii = in(i);
2088 if (ii->is_MergeMem()) {
2089 MergeMemNode* n = ii->as_MergeMem();
2090 // compress paths and change unreachable cycles to TOP
2091 // If not, we can update the input infinitely along a MergeMem cycle
2092 // Equivalent code is in MemNode::Ideal_common
2093 Node *m = phase->transform(n);
2094 if (outcnt() == 0) { // Above transform() may kill us!
2095 return top;
2096 }
2097 // If transformed to a MergeMem, get the desired slice
2098 // Otherwise the returned node represents memory for every slice
2099 Node *new_mem = (m->is_MergeMem()) ?
2100 m->as_MergeMem()->memory_at(alias_idx) : m;
2101 // Update input if it is progress over what we have now
2102 if (new_mem != ii) {
2103 set_req(i, new_mem);
2104 progress = this;
2105 }
2106 }
2107 }
2108 } else {
2109 // We know that at least one MergeMem->base_memory() == this
2110 // (saw_self == true). If all other inputs also references this phi
2111 // (directly or through data nodes) - it is dead loop.
2112 bool saw_safe_input = false;
2113 for (uint j = 1; j < req(); ++j) {
2114 Node *n = in(j);
2115 if (n->is_MergeMem() && n->as_MergeMem()->base_memory() == this)
2116 continue; // skip known cases
2117 if (!is_unsafe_data_reference(n)) {
2118 saw_safe_input = true; // found safe input
2119 break;
2120 }
2121 }
2122 if (!saw_safe_input)
2123 return top; // all inputs reference back to this phi - dead loop
2124
2125 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into
2126 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...))
2127 PhaseIterGVN *igvn = phase->is_IterGVN();
2128 Node* hook = new Node(1);
2129 PhiNode* new_base = (PhiNode*) clone();
2130 // Must eagerly register phis, since they participate in loops.
2131 if (igvn) {
2132 igvn->register_new_node_with_optimizer(new_base);
2133 hook->add_req(new_base);
2134 }
2135 MergeMemNode* result = MergeMemNode::make(new_base);
2136 for (uint i = 1; i < req(); ++i) {
2137 Node *ii = in(i);
2138 if (ii->is_MergeMem()) {
2139 MergeMemNode* n = ii->as_MergeMem();
2140 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) {
2141 // If we have not seen this slice yet, make a phi for it.
2142 bool made_new_phi = false;
2143 if (mms.is_empty()) {
2144 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C));
2145 made_new_phi = true;
2146 if (igvn) {
2147 igvn->register_new_node_with_optimizer(new_phi);
2148 hook->add_req(new_phi);
2149 }
2150 mms.set_memory(new_phi);
2151 }
2152 Node* phi = mms.memory();
2153 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice");
2154 phi->set_req(i, mms.memory2());
2155 }
2156 }
2157 }
2158 // Distribute all self-loops.
2159 { // (Extra braces to hide mms.)
2160 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2161 Node* phi = mms.memory();
2162 for (uint i = 1; i < req(); ++i) {
2163 if (phi->in(i) == this) phi->set_req(i, phi);
2164 }
2165 }
2166 }
2167 // now transform the new nodes, and return the mergemem
2168 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2169 Node* phi = mms.memory();
2170 mms.set_memory(phase->transform(phi));
2171 }
2172 if (igvn) { // Unhook.
2173 igvn->hash_delete(hook);
2174 for (uint i = 1; i < hook->req(); i++) {
2175 hook->set_req(i, NULL);
2176 }
2177 }
2178 // Replace self with the result.
2179 return result;
2180 }
2181 }
2182 //
2183 // Other optimizations on the memory chain
2184 //
2185 const TypePtr* at = adr_type();
2186 for( uint i=1; i<req(); ++i ) {// For all paths in
2187 Node *ii = in(i);
2188 Node *new_in = MemNode::optimize_memory_chain(ii, at, NULL, phase);
2189 if (ii != new_in ) {
2190 set_req(i, new_in);
2191 progress = this;
2192 }
2193 }
2194 }
2195
2196 #ifdef _LP64
2197 // Push DecodeN/DecodeNKlass down through phi.
2198 // The rest of phi graph will transform by split EncodeP node though phis up.
2199 if ((UseCompressedOops || UseCompressedClassPointers) && can_reshape && progress == NULL) {
2200 bool may_push = true;
2201 bool has_decodeN = false;
2202 bool is_decodeN = false;
2203 for (uint i=1; i<req(); ++i) {// For all paths in
2204 Node *ii = in(i);
2205 if (ii->is_DecodeNarrowPtr() && ii->bottom_type() == bottom_type()) {
2206 // Do optimization if a non dead path exist.
2207 if (ii->in(1)->bottom_type() != Type::TOP) {
2208 has_decodeN = true;
2209 is_decodeN = ii->is_DecodeN();
2210 }
2211 } else if (!ii->is_Phi()) {
2212 may_push = false;
2213 }
2214 }
2215
2216 if (has_decodeN && may_push) {
2217 PhaseIterGVN *igvn = phase->is_IterGVN();
2218 // Make narrow type for new phi.
2219 const Type* narrow_t;
2220 if (is_decodeN) {
2221 narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr());
2222 } else {
2223 narrow_t = TypeNarrowKlass::make(this->bottom_type()->is_ptr());
2224 }
2225 PhiNode* new_phi = new PhiNode(r, narrow_t);
2226 uint orig_cnt = req();
2227 for (uint i=1; i<req(); ++i) {// For all paths in
2228 Node *ii = in(i);
2229 Node* new_ii = NULL;
2230 if (ii->is_DecodeNarrowPtr()) {
2231 assert(ii->bottom_type() == bottom_type(), "sanity");
2232 new_ii = ii->in(1);
2233 } else {
2234 assert(ii->is_Phi(), "sanity");
2235 if (ii->as_Phi() == this) {
2236 new_ii = new_phi;
2237 } else {
2238 if (is_decodeN) {
2239 new_ii = new EncodePNode(ii, narrow_t);
2240 } else {
2241 new_ii = new EncodePKlassNode(ii, narrow_t);
2242 }
2243 igvn->register_new_node_with_optimizer(new_ii);
2244 }
2245 }
2246 new_phi->set_req(i, new_ii);
2247 }
2248 igvn->register_new_node_with_optimizer(new_phi, this);
2249 if (is_decodeN) {
2250 progress = new DecodeNNode(new_phi, bottom_type());
2251 } else {
2252 progress = new DecodeNKlassNode(new_phi, bottom_type());
2253 }
2254 }
2255 }
2256 #endif
2257
2258 return progress; // Return any progress
2259 }
2260
2261 //------------------------------is_tripcount-----------------------------------
2262 bool PhiNode::is_tripcount() const {
2263 return (in(0) != NULL && in(0)->is_CountedLoop() &&
2264 in(0)->as_CountedLoop()->phi() == this);
2265 }
2266
2267 //------------------------------out_RegMask------------------------------------
2268 const RegMask &PhiNode::in_RegMask(uint i) const {
2269 return i ? out_RegMask() : RegMask::Empty;
2270 }
2271
2272 const RegMask &PhiNode::out_RegMask() const {
2273 uint ideal_reg = _type->ideal_reg();
2274 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
2275 if( ideal_reg == 0 ) return RegMask::Empty;
2276 assert(ideal_reg != Op_RegFlags, "flags register is not spillable");
2277 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
2278 }
2279
2280 #ifndef PRODUCT
2281 void PhiNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2282 // For a PhiNode, the set of related nodes includes all inputs till level 2,
2283 // and all outputs till level 1. In compact mode, inputs till level 1 are
2284 // collected.
2285 this->collect_nodes(in_rel, compact ? 1 : 2, false, false);
2286 this->collect_nodes(out_rel, -1, false, false);
2287 }
2288
2289 void PhiNode::dump_spec(outputStream *st) const {
2290 TypeNode::dump_spec(st);
2291 if (is_tripcount()) {
2292 st->print(" #tripcount");
2293 }
2294 }
2295 #endif
2296
2297
2298 //=============================================================================
2299 const Type* GotoNode::Value(PhaseGVN* phase) const {
2300 // If the input is reachable, then we are executed.
2301 // If the input is not reachable, then we are not executed.
2302 return phase->type(in(0));
2303 }
2304
2305 Node* GotoNode::Identity(PhaseGVN* phase) {
2306 return in(0); // Simple copy of incoming control
2307 }
2308
2309 const RegMask &GotoNode::out_RegMask() const {
2310 return RegMask::Empty;
2311 }
2312
2313 #ifndef PRODUCT
2314 //-----------------------------related-----------------------------------------
2315 // The related nodes of a GotoNode are all inputs at level 1, as well as the
2316 // outputs at level 1. This is regardless of compact mode.
2317 void GotoNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2318 this->collect_nodes(in_rel, 1, false, false);
2319 this->collect_nodes(out_rel, -1, false, false);
2320 }
2321 #endif
2322
2323
2324 //=============================================================================
2325 const RegMask &JumpNode::out_RegMask() const {
2326 return RegMask::Empty;
2327 }
2328
2329 #ifndef PRODUCT
2330 //-----------------------------related-----------------------------------------
2331 // The related nodes of a JumpNode are all inputs at level 1, as well as the
2332 // outputs at level 2 (to include actual jump targets beyond projection nodes).
2333 // This is regardless of compact mode.
2334 void JumpNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2335 this->collect_nodes(in_rel, 1, false, false);
2336 this->collect_nodes(out_rel, -2, false, false);
2337 }
2338 #endif
2339
2340 //=============================================================================
2341 const RegMask &JProjNode::out_RegMask() const {
2342 return RegMask::Empty;
2343 }
2344
2345 //=============================================================================
2346 const RegMask &CProjNode::out_RegMask() const {
2347 return RegMask::Empty;
2348 }
2349
2350
2351
2352 //=============================================================================
2353
2354 uint PCTableNode::hash() const { return Node::hash() + _size; }
2355 uint PCTableNode::cmp( const Node &n ) const
2356 { return _size == ((PCTableNode&)n)._size; }
2357
2358 const Type *PCTableNode::bottom_type() const {
2359 const Type** f = TypeTuple::fields(_size);
2360 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2361 return TypeTuple::make(_size, f);
2362 }
2363
2364 //------------------------------Value------------------------------------------
2365 // Compute the type of the PCTableNode. If reachable it is a tuple of
2366 // Control, otherwise the table targets are not reachable
2367 const Type* PCTableNode::Value(PhaseGVN* phase) const {
2368 if( phase->type(in(0)) == Type::CONTROL )
2369 return bottom_type();
2370 return Type::TOP; // All paths dead? Then so are we
2371 }
2372
2373 //------------------------------Ideal------------------------------------------
2374 // Return a node which is more "ideal" than the current node. Strip out
2375 // control copies
2376 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2377 return remove_dead_region(phase, can_reshape) ? this : NULL;
2378 }
2379
2380 //=============================================================================
2381 uint JumpProjNode::hash() const {
2382 return Node::hash() + _dest_bci;
2383 }
2384
2385 uint JumpProjNode::cmp( const Node &n ) const {
2386 return ProjNode::cmp(n) &&
2387 _dest_bci == ((JumpProjNode&)n)._dest_bci;
2388 }
2389
2390 #ifndef PRODUCT
2391 void JumpProjNode::dump_spec(outputStream *st) const {
2392 ProjNode::dump_spec(st);
2393 st->print("@bci %d ",_dest_bci);
2394 }
2395
2396 void JumpProjNode::dump_compact_spec(outputStream *st) const {
2397 ProjNode::dump_compact_spec(st);
2398 st->print("(%d)%d@%d", _switch_val, _proj_no, _dest_bci);
2399 }
2400
2401 void JumpProjNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2402 // The related nodes of a JumpProjNode are its inputs and outputs at level 1.
2403 this->collect_nodes(in_rel, 1, false, false);
2404 this->collect_nodes(out_rel, -1, false, false);
2405 }
2406 #endif
2407
2408 //=============================================================================
2409 //------------------------------Value------------------------------------------
2410 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot
2411 // have the default "fall_through_index" path.
2412 const Type* CatchNode::Value(PhaseGVN* phase) const {
2413 // Unreachable? Then so are all paths from here.
2414 if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
2415 // First assume all paths are reachable
2416 const Type** f = TypeTuple::fields(_size);
2417 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2418 // Identify cases that will always throw an exception
2419 // () rethrow call
2420 // () virtual or interface call with NULL receiver
2421 // () call is a check cast with incompatible arguments
2422 if( in(1)->is_Proj() ) {
2423 Node *i10 = in(1)->in(0);
2424 if( i10->is_Call() ) {
2425 CallNode *call = i10->as_Call();
2426 // Rethrows always throw exceptions, never return
2427 if (call->entry_point() == OptoRuntime::rethrow_stub()) {
2428 f[CatchProjNode::fall_through_index] = Type::TOP;
2429 } else if( call->req() > TypeFunc::Parms ) {
2430 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) );
2431 // Check for null receiver to virtual or interface calls
2432 if( call->is_CallDynamicJava() &&
2433 arg0->higher_equal(TypePtr::NULL_PTR) ) {
2434 f[CatchProjNode::fall_through_index] = Type::TOP;
2435 }
2436 } // End of if not a runtime stub
2437 } // End of if have call above me
2438 } // End of slot 1 is not a projection
2439 return TypeTuple::make(_size, f);
2440 }
2441
2442 //=============================================================================
2443 uint CatchProjNode::hash() const {
2444 return Node::hash() + _handler_bci;
2445 }
2446
2447
2448 uint CatchProjNode::cmp( const Node &n ) const {
2449 return ProjNode::cmp(n) &&
2450 _handler_bci == ((CatchProjNode&)n)._handler_bci;
2451 }
2452
2453
2454 //------------------------------Identity---------------------------------------
2455 // If only 1 target is possible, choose it if it is the main control
2456 Node* CatchProjNode::Identity(PhaseGVN* phase) {
2457 // If my value is control and no other value is, then treat as ID
2458 const TypeTuple *t = phase->type(in(0))->is_tuple();
2459 if (t->field_at(_con) != Type::CONTROL) return this;
2460 // If we remove the last CatchProj and elide the Catch/CatchProj, then we
2461 // also remove any exception table entry. Thus we must know the call
2462 // feeding the Catch will not really throw an exception. This is ok for
2463 // the main fall-thru control (happens when we know a call can never throw
2464 // an exception) or for "rethrow", because a further optimization will
2465 // yank the rethrow (happens when we inline a function that can throw an
2466 // exception and the caller has no handler). Not legal, e.g., for passing
2467 // a NULL receiver to a v-call, or passing bad types to a slow-check-cast.
2468 // These cases MUST throw an exception via the runtime system, so the VM
2469 // will be looking for a table entry.
2470 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode
2471 CallNode *call;
2472 if (_con != TypeFunc::Control && // Bail out if not the main control.
2473 !(proj->is_Proj() && // AND NOT a rethrow
2474 proj->in(0)->is_Call() &&
2475 (call = proj->in(0)->as_Call()) &&
2476 call->entry_point() == OptoRuntime::rethrow_stub()))
2477 return this;
2478
2479 // Search for any other path being control
2480 for (uint i = 0; i < t->cnt(); i++) {
2481 if (i != _con && t->field_at(i) == Type::CONTROL)
2482 return this;
2483 }
2484 // Only my path is possible; I am identity on control to the jump
2485 return in(0)->in(0);
2486 }
2487
2488
2489 #ifndef PRODUCT
2490 void CatchProjNode::dump_spec(outputStream *st) const {
2491 ProjNode::dump_spec(st);
2492 st->print("@bci %d ",_handler_bci);
2493 }
2494 #endif
2495
2496 //=============================================================================
2497 //------------------------------Identity---------------------------------------
2498 // Check for CreateEx being Identity.
2499 Node* CreateExNode::Identity(PhaseGVN* phase) {
2500 if( phase->type(in(1)) == Type::TOP ) return in(1);
2501 if( phase->type(in(0)) == Type::TOP ) return in(0);
2502 // We only come from CatchProj, unless the CatchProj goes away.
2503 // If the CatchProj is optimized away, then we just carry the
2504 // exception oop through.
2505 CallNode *call = in(1)->in(0)->as_Call();
2506
2507 return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) )
2508 ? this
2509 : call->in(TypeFunc::Parms);
2510 }
2511
2512 //=============================================================================
2513 //------------------------------Value------------------------------------------
2514 // Check for being unreachable.
2515 const Type* NeverBranchNode::Value(PhaseGVN* phase) const {
2516 if (!in(0) || in(0)->is_top()) return Type::TOP;
2517 return bottom_type();
2518 }
2519
2520 //------------------------------Ideal------------------------------------------
2521 // Check for no longer being part of a loop
2522 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2523 if (can_reshape && !in(0)->is_Loop()) {
2524 // Dead code elimination can sometimes delete this projection so
2525 // if it's not there, there's nothing to do.
2526 Node* fallthru = proj_out_or_null(0);
2527 if (fallthru != NULL) {
2528 phase->is_IterGVN()->replace_node(fallthru, in(0));
2529 }
2530 return phase->C->top();
2531 }
2532 return NULL;
2533 }
2534
2535 #ifndef PRODUCT
2536 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const {
2537 st->print("%s", Name());
2538 }
2539 #endif