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