1 /*
2 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "memory/allocation.inline.hpp"
28 #include "memory/resourceArea.hpp"
29 #include "oops/objArrayKlass.hpp"
30 #include "opto/addnode.hpp"
31 #include "opto/castnode.hpp"
32 #include "opto/cfgnode.hpp"
33 #include "opto/connode.hpp"
34 #include "opto/convertnode.hpp"
35 #include "opto/loopnode.hpp"
36 #include "opto/machnode.hpp"
37 #include "opto/movenode.hpp"
38 #include "opto/narrowptrnode.hpp"
39 #include "opto/mulnode.hpp"
40 #include "opto/phaseX.hpp"
41 #include "opto/regmask.hpp"
42 #include "opto/runtime.hpp"
43 #include "opto/subnode.hpp"
44 #include "opto/valuetypenode.hpp"
45 #include "utilities/vmError.hpp"
46
47 // Portions of code courtesy of Clifford Click
48
49 // Optimization - Graph Style
50
51 //=============================================================================
52 //------------------------------Value------------------------------------------
53 // Compute the type of the RegionNode.
54 const Type* RegionNode::Value(PhaseGVN* phase) const {
55 for( uint i=1; i<req(); ++i ) { // For all paths in
56 Node *n = in(i); // Get Control source
57 if( !n ) continue; // Missing inputs are TOP
58 if( phase->type(n) == Type::CONTROL )
59 return Type::CONTROL;
60 }
61 return Type::TOP; // All paths dead? Then so are we
62 }
63
64 //------------------------------Identity---------------------------------------
65 // Check for Region being Identity.
66 Node* RegionNode::Identity(PhaseGVN* phase) {
67 // Cannot have Region be an identity, even if it has only 1 input.
68 // Phi users cannot have their Region input folded away for them,
69 // since they need to select the proper data input
70 return this;
71 }
72
73 //------------------------------merge_region-----------------------------------
74 // If a Region flows into a Region, merge into one big happy merge. This is
75 // hard to do if there is stuff that has to happen
76 static Node *merge_region(RegionNode *region, PhaseGVN *phase) {
77 if( region->Opcode() != Op_Region ) // Do not do to LoopNodes
78 return NULL;
79 Node *progress = NULL; // Progress flag
80 PhaseIterGVN *igvn = phase->is_IterGVN();
81
82 uint rreq = region->req();
83 for( uint i = 1; i < rreq; i++ ) {
84 Node *r = region->in(i);
85 if( r && r->Opcode() == Op_Region && // Found a region?
86 r->in(0) == r && // Not already collapsed?
87 r != region && // Avoid stupid situations
88 r->outcnt() == 2 ) { // Self user and 'region' user only?
89 assert(!r->as_Region()->has_phi(), "no phi users");
90 if( !progress ) { // No progress
91 if (region->has_phi()) {
92 return NULL; // Only flatten if no Phi users
93 // igvn->hash_delete( phi );
94 }
95 igvn->hash_delete( region );
96 progress = region; // Making progress
97 }
98 igvn->hash_delete( r );
99
100 // Append inputs to 'r' onto 'region'
101 for( uint j = 1; j < r->req(); j++ ) {
102 // Move an input from 'r' to 'region'
103 region->add_req(r->in(j));
104 r->set_req(j, phase->C->top());
105 // Update phis of 'region'
106 //for( uint k = 0; k < max; k++ ) {
107 // Node *phi = region->out(k);
108 // if( phi->is_Phi() ) {
109 // phi->add_req(phi->in(i));
110 // }
111 //}
112
113 rreq++; // One more input to Region
114 } // Found a region to merge into Region
115 igvn->_worklist.push(r);
116 // Clobber pointer to the now dead 'r'
117 region->set_req(i, phase->C->top());
118 }
119 }
120
121 return progress;
122 }
123
124
125
126 //--------------------------------has_phi--------------------------------------
127 // Helper function: Return any PhiNode that uses this region or NULL
128 PhiNode* RegionNode::has_phi() const {
129 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
130 Node* phi = fast_out(i);
131 if (phi->is_Phi()) { // Check for Phi users
132 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
133 return phi->as_Phi(); // this one is good enough
134 }
135 }
136
137 return NULL;
138 }
139
140
141 //-----------------------------has_unique_phi----------------------------------
142 // Helper function: Return the only PhiNode that uses this region or NULL
143 PhiNode* RegionNode::has_unique_phi() const {
144 // Check that only one use is a Phi
145 PhiNode* only_phi = NULL;
146 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
147 Node* phi = fast_out(i);
148 if (phi->is_Phi()) { // Check for Phi users
149 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
150 if (only_phi == NULL) {
151 only_phi = phi->as_Phi();
152 } else {
153 return NULL; // multiple phis
154 }
155 }
156 }
157
158 return only_phi;
159 }
160
161
162 //------------------------------check_phi_clipping-----------------------------
163 // Helper function for RegionNode's identification of FP clipping
164 // Check inputs to the Phi
165 static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) {
166 min = NULL;
167 max = NULL;
168 val = NULL;
169 min_idx = 0;
170 max_idx = 0;
171 val_idx = 0;
172 uint phi_max = phi->req();
173 if( phi_max == 4 ) {
174 for( uint j = 1; j < phi_max; ++j ) {
175 Node *n = phi->in(j);
176 int opcode = n->Opcode();
177 switch( opcode ) {
178 case Op_ConI:
179 {
180 if( min == NULL ) {
181 min = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
182 min_idx = j;
183 } else {
184 max = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
185 max_idx = j;
186 if( min->get_int() > max->get_int() ) {
187 // Swap min and max
188 ConNode *temp;
189 uint temp_idx;
190 temp = min; min = max; max = temp;
191 temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx;
192 }
193 }
194 }
195 break;
196 default:
197 {
198 val = n;
199 val_idx = j;
200 }
201 break;
202 }
203 }
204 }
205 return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) );
206 }
207
208
209 //------------------------------check_if_clipping------------------------------
210 // Helper function for RegionNode's identification of FP clipping
211 // Check that inputs to Region come from two IfNodes,
212 //
213 // If
214 // False True
215 // If |
216 // False True |
217 // | | |
218 // RegionNode_inputs
219 //
220 static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) {
221 top_if = NULL;
222 bot_if = NULL;
223
224 // Check control structure above RegionNode for (if ( if ) )
225 Node *in1 = region->in(1);
226 Node *in2 = region->in(2);
227 Node *in3 = region->in(3);
228 // Check that all inputs are projections
229 if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) {
230 Node *in10 = in1->in(0);
231 Node *in20 = in2->in(0);
232 Node *in30 = in3->in(0);
233 // Check that #1 and #2 are ifTrue and ifFalse from same If
234 if( in10 != NULL && in10->is_If() &&
235 in20 != NULL && in20->is_If() &&
236 in30 != NULL && in30->is_If() && in10 == in20 &&
237 (in1->Opcode() != in2->Opcode()) ) {
238 Node *in100 = in10->in(0);
239 Node *in1000 = (in100 != NULL && in100->is_Proj()) ? in100->in(0) : NULL;
240 // Check that control for in10 comes from other branch of IF from in3
241 if( in1000 != NULL && in1000->is_If() &&
242 in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) {
243 // Control pattern checks
244 top_if = (IfNode*)in1000;
245 bot_if = (IfNode*)in10;
246 }
247 }
248 }
249
250 return (top_if != NULL);
251 }
252
253
254 //------------------------------check_convf2i_clipping-------------------------
255 // Helper function for RegionNode's identification of FP clipping
256 // Verify that the value input to the phi comes from "ConvF2I; LShift; RShift"
257 static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) {
258 convf2i = NULL;
259
260 // Check for the RShiftNode
261 Node *rshift = phi->in(idx);
262 assert( rshift, "Previous checks ensure phi input is present");
263 if( rshift->Opcode() != Op_RShiftI ) { return false; }
264
265 // Check for the LShiftNode
266 Node *lshift = rshift->in(1);
267 assert( lshift, "Previous checks ensure phi input is present");
268 if( lshift->Opcode() != Op_LShiftI ) { return false; }
269
270 // Check for the ConvF2INode
271 Node *conv = lshift->in(1);
272 if( conv->Opcode() != Op_ConvF2I ) { return false; }
273
274 // Check that shift amounts are only to get sign bits set after F2I
275 jint max_cutoff = max->get_int();
276 jint min_cutoff = min->get_int();
277 jint left_shift = lshift->in(2)->get_int();
278 jint right_shift = rshift->in(2)->get_int();
279 jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1);
280 if( left_shift != right_shift ||
281 0 > left_shift || left_shift >= BitsPerJavaInteger ||
282 max_post_shift < max_cutoff ||
283 max_post_shift < -min_cutoff ) {
284 // Shifts are necessary but current transformation eliminates them
285 return false;
286 }
287
288 // OK to return the result of ConvF2I without shifting
289 convf2i = (ConvF2INode*)conv;
290 return true;
291 }
292
293
294 //------------------------------check_compare_clipping-------------------------
295 // Helper function for RegionNode's identification of FP clipping
296 static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) {
297 Node *i1 = iff->in(1);
298 if ( !i1->is_Bool() ) { return false; }
299 BoolNode *bool1 = i1->as_Bool();
300 if( less_than && bool1->_test._test != BoolTest::le ) { return false; }
301 else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; }
302 const Node *cmpF = bool1->in(1);
303 if( cmpF->Opcode() != Op_CmpF ) { return false; }
304 // Test that the float value being compared against
305 // is equivalent to the int value used as a limit
306 Node *nodef = cmpF->in(2);
307 if( nodef->Opcode() != Op_ConF ) { return false; }
308 jfloat conf = nodef->getf();
309 jint coni = limit->get_int();
310 if( ((int)conf) != coni ) { return false; }
311 input = cmpF->in(1);
312 return true;
313 }
314
315 //------------------------------is_unreachable_region--------------------------
316 // Find if the Region node is reachable from the root.
317 bool RegionNode::is_unreachable_region(PhaseGVN *phase) const {
318 assert(req() == 2, "");
319
320 // First, cut the simple case of fallthrough region when NONE of
321 // region's phis references itself directly or through a data node.
322 uint max = outcnt();
323 uint i;
324 for (i = 0; i < max; i++) {
325 Node* phi = raw_out(i);
326 if (phi != NULL && phi->is_Phi()) {
327 assert(phase->eqv(phi->in(0), this) && phi->req() == 2, "");
328 if (phi->outcnt() == 0)
329 continue; // Safe case - no loops
330 if (phi->outcnt() == 1) {
331 Node* u = phi->raw_out(0);
332 // Skip if only one use is an other Phi or Call or Uncommon trap.
333 // It is safe to consider this case as fallthrough.
334 if (u != NULL && (u->is_Phi() || u->is_CFG()))
335 continue;
336 }
337 // Check when phi references itself directly or through an other node.
338 if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe)
339 break; // Found possible unsafe data loop.
340 }
341 }
342 if (i >= max)
343 return false; // An unsafe case was NOT found - don't need graph walk.
344
345 // Unsafe case - check if the Region node is reachable from root.
346 ResourceMark rm;
347
348 Arena *a = Thread::current()->resource_area();
349 Node_List nstack(a);
350 VectorSet visited(a);
351
352 // Mark all control nodes reachable from root outputs
353 Node *n = (Node*)phase->C->root();
354 nstack.push(n);
355 visited.set(n->_idx);
356 while (nstack.size() != 0) {
357 n = nstack.pop();
358 uint max = n->outcnt();
359 for (uint i = 0; i < max; i++) {
360 Node* m = n->raw_out(i);
361 if (m != NULL && m->is_CFG()) {
362 if (phase->eqv(m, this)) {
363 return false; // We reached the Region node - it is not dead.
364 }
365 if (!visited.test_set(m->_idx))
366 nstack.push(m);
367 }
368 }
369 }
370
371 return true; // The Region node is unreachable - it is dead.
372 }
373
374 bool RegionNode::try_clean_mem_phi(PhaseGVN *phase) {
375 // Incremental inlining + PhaseStringOpts sometimes produce:
376 //
377 // cmpP with 1 top input
378 // |
379 // If
380 // / \
381 // IfFalse IfTrue /- Some Node
382 // \ / / /
383 // Region / /-MergeMem
384 // \---Phi
385 //
386 //
387 // It's expected by PhaseStringOpts that the Region goes away and is
388 // replaced by If's control input but because there's still a Phi,
389 // the Region stays in the graph. The top input from the cmpP is
390 // propagated forward and a subgraph that is useful goes away. The
391 // code below replaces the Phi with the MergeMem so that the Region
392 // is simplified.
393
394 PhiNode* phi = has_unique_phi();
395 if (phi && phi->type() == Type::MEMORY && req() == 3 && phi->is_diamond_phi(true)) {
396 MergeMemNode* m = NULL;
397 assert(phi->req() == 3, "same as region");
398 for (uint i = 1; i < 3; ++i) {
399 Node *mem = phi->in(i);
400 if (mem && mem->is_MergeMem() && in(i)->outcnt() == 1) {
401 // Nothing is control-dependent on path #i except the region itself.
402 m = mem->as_MergeMem();
403 uint j = 3 - i;
404 Node* other = phi->in(j);
405 if (other && other == m->base_memory()) {
406 // m is a successor memory to other, and is not pinned inside the diamond, so push it out.
407 // This will allow the diamond to collapse completely.
408 phase->is_IterGVN()->replace_node(phi, m);
409 return true;
410 }
411 }
412 }
413 }
414 return false;
415 }
416
417 //------------------------------Ideal------------------------------------------
418 // Return a node which is more "ideal" than the current node. Must preserve
419 // the CFG, but we can still strip out dead paths.
420 Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) {
421 if( !can_reshape && !in(0) ) return NULL; // Already degraded to a Copy
422 assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge");
423
424 // Check for RegionNode with no Phi users and both inputs come from either
425 // arm of the same IF. If found, then the control-flow split is useless.
426 bool has_phis = false;
427 if (can_reshape) { // Need DU info to check for Phi users
428 has_phis = (has_phi() != NULL); // Cache result
429 if (has_phis && try_clean_mem_phi(phase)) {
430 has_phis = false;
431 }
432
433 if (!has_phis) { // No Phi users? Nothing merging?
434 for (uint i = 1; i < req()-1; i++) {
435 Node *if1 = in(i);
436 if( !if1 ) continue;
437 Node *iff = if1->in(0);
438 if( !iff || !iff->is_If() ) continue;
439 for( uint j=i+1; j<req(); j++ ) {
440 if( in(j) && in(j)->in(0) == iff &&
441 if1->Opcode() != in(j)->Opcode() ) {
442 // Add the IF Projections to the worklist. They (and the IF itself)
443 // will be eliminated if dead.
444 phase->is_IterGVN()->add_users_to_worklist(iff);
445 set_req(i, iff->in(0));// Skip around the useless IF diamond
446 set_req(j, NULL);
447 return this; // Record progress
448 }
449 }
450 }
451 }
452 }
453
454 // Remove TOP or NULL input paths. If only 1 input path remains, this Region
455 // degrades to a copy.
456 bool add_to_worklist = false;
457 bool modified = false;
458 int cnt = 0; // Count of values merging
459 DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count
460 int del_it = 0; // The last input path we delete
461 // For all inputs...
462 for( uint i=1; i<req(); ++i ){// For all paths in
463 Node *n = in(i); // Get the input
464 if( n != NULL ) {
465 // Remove useless control copy inputs
466 if( n->is_Region() && n->as_Region()->is_copy() ) {
467 set_req(i, n->nonnull_req());
468 modified = true;
469 i--;
470 continue;
471 }
472 if( n->is_Proj() ) { // Remove useless rethrows
473 Node *call = n->in(0);
474 if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) {
475 set_req(i, call->in(0));
476 modified = true;
477 i--;
478 continue;
479 }
480 }
481 if( phase->type(n) == Type::TOP ) {
482 set_req(i, NULL); // Ignore TOP inputs
483 modified = true;
484 i--;
485 continue;
486 }
487 cnt++; // One more value merging
488
489 } else if (can_reshape) { // Else found dead path with DU info
490 PhaseIterGVN *igvn = phase->is_IterGVN();
491 del_req(i); // Yank path from self
492 del_it = i;
493 uint max = outcnt();
494 DUIterator j;
495 bool progress = true;
496 while(progress) { // Need to establish property over all users
497 progress = false;
498 for (j = outs(); has_out(j); j++) {
499 Node *n = out(j);
500 if( n->req() != req() && n->is_Phi() ) {
501 assert( n->in(0) == this, "" );
502 igvn->hash_delete(n); // Yank from hash before hacking edges
503 n->set_req_X(i,NULL,igvn);// Correct DU info
504 n->del_req(i); // Yank path from Phis
505 if( max != outcnt() ) {
506 progress = true;
507 j = refresh_out_pos(j);
508 max = outcnt();
509 }
510 }
511 }
512 }
513 add_to_worklist = true;
514 i--;
515 }
516 }
517
518 if (can_reshape && cnt == 1) {
519 // Is it dead loop?
520 // If it is LoopNopde it had 2 (+1 itself) inputs and
521 // one of them was cut. The loop is dead if it was EntryContol.
522 // Loop node may have only one input because entry path
523 // is removed in PhaseIdealLoop::Dominators().
524 assert(!this->is_Loop() || cnt_orig <= 3, "Loop node should have 3 or less inputs");
525 if ((this->is_Loop() && (del_it == LoopNode::EntryControl ||
526 (del_it == 0 && is_unreachable_region(phase)))) ||
527 (!this->is_Loop() && has_phis && is_unreachable_region(phase))) {
528 // Yes, the region will be removed during the next step below.
529 // Cut the backedge input and remove phis since no data paths left.
530 // We don't cut outputs to other nodes here since we need to put them
531 // on the worklist.
532 PhaseIterGVN *igvn = phase->is_IterGVN();
533 if (in(1)->outcnt() == 1) {
534 igvn->_worklist.push(in(1));
535 }
536 del_req(1);
537 cnt = 0;
538 assert( req() == 1, "no more inputs expected" );
539 uint max = outcnt();
540 bool progress = true;
541 Node *top = phase->C->top();
542 DUIterator j;
543 while(progress) {
544 progress = false;
545 for (j = outs(); has_out(j); j++) {
546 Node *n = out(j);
547 if( n->is_Phi() ) {
548 assert( igvn->eqv(n->in(0), this), "" );
549 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
550 // Break dead loop data path.
551 // Eagerly replace phis with top to avoid phis copies generation.
552 igvn->replace_node(n, top);
553 if( max != outcnt() ) {
554 progress = true;
555 j = refresh_out_pos(j);
556 max = outcnt();
557 }
558 }
559 }
560 }
561 add_to_worklist = true;
562 }
563 }
564 if (add_to_worklist) {
565 phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis
566 }
567
568 if( cnt <= 1 ) { // Only 1 path in?
569 set_req(0, NULL); // Null control input for region copy
570 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is.
571 // No inputs or all inputs are NULL.
572 return NULL;
573 } else if (can_reshape) { // Optimization phase - remove the node
574 PhaseIterGVN *igvn = phase->is_IterGVN();
575 // Strip mined (inner) loop is going away, remove outer loop.
576 if (is_CountedLoop() &&
577 as_Loop()->is_strip_mined()) {
578 Node* outer_sfpt = as_CountedLoop()->outer_safepoint();
579 Node* outer_out = as_CountedLoop()->outer_loop_exit();
580 if (outer_sfpt != NULL && outer_out != NULL) {
581 Node* in = outer_sfpt->in(0);
582 igvn->replace_node(outer_out, in);
583 LoopNode* outer = as_CountedLoop()->outer_loop();
584 igvn->replace_input_of(outer, LoopNode::LoopBackControl, igvn->C->top());
585 }
586 }
587 Node *parent_ctrl;
588 if( cnt == 0 ) {
589 assert( req() == 1, "no inputs expected" );
590 // During IGVN phase such region will be subsumed by TOP node
591 // so region's phis will have TOP as control node.
592 // Kill phis here to avoid it. PhiNode::is_copy() will be always false.
593 // Also set other user's input to top.
594 parent_ctrl = phase->C->top();
595 } else {
596 // The fallthrough case since we already checked dead loops above.
597 parent_ctrl = in(1);
598 assert(parent_ctrl != NULL, "Region is a copy of some non-null control");
599 assert(!igvn->eqv(parent_ctrl, this), "Close dead loop");
600 }
601 if (!add_to_worklist)
602 igvn->add_users_to_worklist(this); // Check for further allowed opts
603 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
604 Node* n = last_out(i);
605 igvn->hash_delete(n); // Remove from worklist before modifying edges
606 if( n->is_Phi() ) { // Collapse all Phis
607 // Eagerly replace phis to avoid copies generation.
608 Node* in;
609 if( cnt == 0 ) {
610 assert( n->req() == 1, "No data inputs expected" );
611 in = parent_ctrl; // replaced by top
612 } else {
613 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
614 in = n->in(1); // replaced by unique input
615 if( n->as_Phi()->is_unsafe_data_reference(in) )
616 in = phase->C->top(); // replaced by top
617 }
618 igvn->replace_node(n, in);
619 }
620 else if( n->is_Region() ) { // Update all incoming edges
621 assert( !igvn->eqv(n, this), "Must be removed from DefUse edges");
622 uint uses_found = 0;
623 for( uint k=1; k < n->req(); k++ ) {
624 if( n->in(k) == this ) {
625 n->set_req(k, parent_ctrl);
626 uses_found++;
627 }
628 }
629 if( uses_found > 1 ) { // (--i) done at the end of the loop.
630 i -= (uses_found - 1);
631 }
632 }
633 else {
634 assert( igvn->eqv(n->in(0), this), "Expect RegionNode to be control parent");
635 n->set_req(0, parent_ctrl);
636 }
637 #ifdef ASSERT
638 for( uint k=0; k < n->req(); k++ ) {
639 assert( !igvn->eqv(n->in(k), this), "All uses of RegionNode should be gone");
640 }
641 #endif
642 }
643 // Remove the RegionNode itself from DefUse info
644 igvn->remove_dead_node(this);
645 return NULL;
646 }
647 return this; // Record progress
648 }
649
650
651 // If a Region flows into a Region, merge into one big happy merge.
652 if (can_reshape) {
653 Node *m = merge_region(this, phase);
654 if (m != NULL) return m;
655 }
656
657 // Check if this region is the root of a clipping idiom on floats
658 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
659 // Check that only one use is a Phi and that it simplifies to two constants +
660 PhiNode* phi = has_unique_phi();
661 if (phi != NULL) { // One Phi user
662 // Check inputs to the Phi
663 ConNode *min;
664 ConNode *max;
665 Node *val;
666 uint min_idx;
667 uint max_idx;
668 uint val_idx;
669 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) {
670 IfNode *top_if;
671 IfNode *bot_if;
672 if( check_if_clipping( this, bot_if, top_if ) ) {
673 // Control pattern checks, now verify compares
674 Node *top_in = NULL; // value being compared against
675 Node *bot_in = NULL;
676 if( check_compare_clipping( true, bot_if, min, bot_in ) &&
677 check_compare_clipping( false, top_if, max, top_in ) ) {
678 if( bot_in == top_in ) {
679 PhaseIterGVN *gvn = phase->is_IterGVN();
680 assert( gvn != NULL, "Only had DefUse info in IterGVN");
681 // Only remaining check is that bot_in == top_in == (Phi's val + mods)
682
683 // Check for the ConvF2INode
684 ConvF2INode *convf2i;
685 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
686 convf2i->in(1) == bot_in ) {
687 // Matched pattern, including LShiftI; RShiftI, replace with integer compares
688 // max test
689 Node *cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, min ));
690 Node *boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::lt ));
691 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt ));
692 Node *if_min= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
693 Node *ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
694 // min test
695 cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, max ));
696 boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::gt ));
697 iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
698 Node *if_max= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
699 ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
700 // update input edges to region node
701 set_req_X( min_idx, if_min, gvn );
702 set_req_X( max_idx, if_max, gvn );
703 set_req_X( val_idx, ifF, gvn );
704 // remove unnecessary 'LShiftI; RShiftI' idiom
705 gvn->hash_delete(phi);
706 phi->set_req_X( val_idx, convf2i, gvn );
707 gvn->hash_find_insert(phi);
708 // Return transformed region node
709 return this;
710 }
711 }
712 }
713 }
714 }
715 }
716 }
717
718 return modified ? this : NULL;
719 }
720
721
722
723 const RegMask &RegionNode::out_RegMask() const {
724 return RegMask::Empty;
725 }
726
727 // Find the one non-null required input. RegionNode only
728 Node *Node::nonnull_req() const {
729 assert( is_Region(), "" );
730 for( uint i = 1; i < _cnt; i++ )
731 if( in(i) )
732 return in(i);
733 ShouldNotReachHere();
734 return NULL;
735 }
736
737
738 //=============================================================================
739 // note that these functions assume that the _adr_type field is flattened
740 uint PhiNode::hash() const {
741 const Type* at = _adr_type;
742 return TypeNode::hash() + (at ? at->hash() : 0);
743 }
744 uint PhiNode::cmp( const Node &n ) const {
745 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
746 }
747 static inline
748 const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
749 if (at == NULL || at == TypePtr::BOTTOM) return at;
750 return Compile::current()->alias_type(at)->adr_type();
751 }
752
753 //----------------------------make---------------------------------------------
754 // create a new phi with edges matching r and set (initially) to x
755 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
756 uint preds = r->req(); // Number of predecessor paths
757 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at");
758 PhiNode* p = new PhiNode(r, t, at);
759 for (uint j = 1; j < preds; j++) {
760 // Fill in all inputs, except those which the region does not yet have
761 if (r->in(j) != NULL)
762 p->init_req(j, x);
763 }
764 return p;
765 }
766 PhiNode* PhiNode::make(Node* r, Node* x) {
767 const Type* t = x->bottom_type();
768 const TypePtr* at = NULL;
769 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
770 return make(r, x, t, at);
771 }
772 PhiNode* PhiNode::make_blank(Node* r, Node* x) {
773 const Type* t = x->bottom_type();
774 const TypePtr* at = NULL;
775 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
776 return new PhiNode(r, t, at);
777 }
778
779
780 //------------------------slice_memory-----------------------------------------
781 // create a new phi with narrowed memory type
782 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
783 PhiNode* mem = (PhiNode*) clone();
784 *(const TypePtr**)&mem->_adr_type = adr_type;
785 // convert self-loops, or else we get a bad graph
786 for (uint i = 1; i < req(); i++) {
787 if ((const Node*)in(i) == this) mem->set_req(i, mem);
788 }
789 mem->verify_adr_type();
790 return mem;
791 }
792
793 //------------------------split_out_instance-----------------------------------
794 // Split out an instance type from a bottom phi.
795 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const {
796 const TypeOopPtr *t_oop = at->isa_oopptr();
797 assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr");
798 const TypePtr *t = adr_type();
799 assert(type() == Type::MEMORY &&
800 (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
801 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
802 t->is_oopptr()->cast_to_exactness(true)
803 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
804 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop),
805 "bottom or raw memory required");
806
807 // Check if an appropriate node already exists.
808 Node *region = in(0);
809 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) {
810 Node* use = region->fast_out(k);
811 if( use->is_Phi()) {
812 PhiNode *phi2 = use->as_Phi();
813 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) {
814 return phi2;
815 }
816 }
817 }
818 Compile *C = igvn->C;
819 Arena *a = Thread::current()->resource_area();
820 Node_Array node_map = new Node_Array(a);
821 Node_Stack stack(a, C->live_nodes() >> 4);
822 PhiNode *nphi = slice_memory(at);
823 igvn->register_new_node_with_optimizer( nphi );
824 node_map.map(_idx, nphi);
825 stack.push((Node *)this, 1);
826 while(!stack.is_empty()) {
827 PhiNode *ophi = stack.node()->as_Phi();
828 uint i = stack.index();
829 assert(i >= 1, "not control edge");
830 stack.pop();
831 nphi = node_map[ophi->_idx]->as_Phi();
832 for (; i < ophi->req(); i++) {
833 Node *in = ophi->in(i);
834 if (in == NULL || igvn->type(in) == Type::TOP)
835 continue;
836 Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, NULL, igvn);
837 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL;
838 if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) {
839 opt = node_map[optphi->_idx];
840 if (opt == NULL) {
841 stack.push(ophi, i);
842 nphi = optphi->slice_memory(at);
843 igvn->register_new_node_with_optimizer( nphi );
844 node_map.map(optphi->_idx, nphi);
845 ophi = optphi;
846 i = 0; // will get incremented at top of loop
847 continue;
848 }
849 }
850 nphi->set_req(i, opt);
851 }
852 }
853 return nphi;
854 }
855
856 //------------------------verify_adr_type--------------------------------------
857 #ifdef ASSERT
858 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
859 if (visited.test_set(_idx)) return; //already visited
860
861 // recheck constructor invariants:
862 verify_adr_type(false);
863
864 // recheck local phi/phi consistency:
865 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
866 "adr_type must be consistent across phi nest");
867
868 // walk around
869 for (uint i = 1; i < req(); i++) {
870 Node* n = in(i);
871 if (n == NULL) continue;
872 const Node* np = in(i);
873 if (np->is_Phi()) {
874 np->as_Phi()->verify_adr_type(visited, at);
875 } else if (n->bottom_type() == Type::TOP
876 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
877 // ignore top inputs
878 } else {
879 const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
880 // recheck phi/non-phi consistency at leaves:
881 assert((nat != NULL) == (at != NULL), "");
882 assert(nat == at || nat == TypePtr::BOTTOM,
883 "adr_type must be consistent at leaves of phi nest");
884 }
885 }
886 }
887
888 // Verify a whole nest of phis rooted at this one.
889 void PhiNode::verify_adr_type(bool recursive) const {
890 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
891 if (Node::in_dump()) return; // muzzle asserts when printing
892
893 assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only");
894
895 if (!VerifyAliases) return; // verify thoroughly only if requested
896
897 assert(_adr_type == flatten_phi_adr_type(_adr_type),
898 "Phi::adr_type must be pre-normalized");
899
900 if (recursive) {
901 VectorSet visited(Thread::current()->resource_area());
902 verify_adr_type(visited, _adr_type);
903 }
904 }
905 #endif
906
907
908 //------------------------------Value------------------------------------------
909 // Compute the type of the PhiNode
910 const Type* PhiNode::Value(PhaseGVN* phase) const {
911 Node *r = in(0); // RegionNode
912 if( !r ) // Copy or dead
913 return in(1) ? phase->type(in(1)) : Type::TOP;
914
915 // Note: During parsing, phis are often transformed before their regions.
916 // This means we have to use type_or_null to defend against untyped regions.
917 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
918 return Type::TOP;
919
920 // Check for trip-counted loop. If so, be smarter.
921 CountedLoopNode* l = r->is_CountedLoop() ? r->as_CountedLoop() : NULL;
922 if (l && ((const Node*)l->phi() == this)) { // Trip counted loop!
923 // protect against init_trip() or limit() returning NULL
924 if (l->can_be_counted_loop(phase)) {
925 const Node *init = l->init_trip();
926 const Node *limit = l->limit();
927 const Node* stride = l->stride();
928 if (init != NULL && limit != NULL && stride != NULL) {
929 const TypeInt* lo = phase->type(init)->isa_int();
930 const TypeInt* hi = phase->type(limit)->isa_int();
931 const TypeInt* stride_t = phase->type(stride)->isa_int();
932 if (lo != NULL && hi != NULL && stride_t != NULL) { // Dying loops might have TOP here
933 assert(stride_t->_hi >= stride_t->_lo, "bad stride type");
934 BoolTest::mask bt = l->loopexit()->test_trip();
935 // If the loop exit condition is "not equal", the condition
936 // would not trigger if init > limit (if stride > 0) or if
937 // init < limit if (stride > 0) so we can't deduce bounds
938 // for the iv from the exit condition.
939 if (bt != BoolTest::ne) {
940 if (stride_t->_hi < 0) { // Down-counter loop
941 swap(lo, hi);
942 return TypeInt::make(MIN2(lo->_lo, hi->_lo) , hi->_hi, 3);
943 } else if (stride_t->_lo >= 0) {
944 return TypeInt::make(lo->_lo, MAX2(lo->_hi, hi->_hi), 3);
945 }
946 }
947 }
948 }
949 } else if (l->in(LoopNode::LoopBackControl) != NULL &&
950 in(LoopNode::EntryControl) != NULL &&
951 phase->type(l->in(LoopNode::LoopBackControl)) == Type::TOP) {
952 // During CCP, if we saturate the type of a counted loop's Phi
953 // before the special code for counted loop above has a chance
954 // to run (that is as long as the type of the backedge's control
955 // is top), we might end up with non monotonic types
956 return phase->type(in(LoopNode::EntryControl))->filter_speculative(_type);
957 }
958 }
959
960 // Until we have harmony between classes and interfaces in the type
961 // lattice, we must tread carefully around phis which implicitly
962 // convert the one to the other.
963 const TypePtr* ttp = _type->make_ptr();
964 const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL;
965 const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_klassptr() : NULL;
966 bool is_intf = false;
967 if (ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
968 is_intf = true;
969 } else if (ttkp != NULL && ttkp->is_loaded() && ttkp->klass()->is_interface()) {
970 is_intf = true;
971 }
972
973 // Default case: merge all inputs
974 const Type *t = Type::TOP; // Merged type starting value
975 for (uint i = 1; i < req(); ++i) {// For all paths in
976 // Reachable control path?
977 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
978 const Type* ti = phase->type(in(i));
979 // We assume that each input of an interface-valued Phi is a true
980 // subtype of that interface. This might not be true of the meet
981 // of all the input types. The lattice is not distributive in
982 // such cases. Ward off asserts in type.cpp by refusing to do
983 // meets between interfaces and proper classes.
984 const TypePtr* tip = ti->make_ptr();
985 const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL;
986 if (tiip) {
987 bool ti_is_intf = false;
988 ciKlass* k = tiip->klass();
989 if (k->is_loaded() && k->is_interface())
990 ti_is_intf = true;
991 if (is_intf != ti_is_intf)
992 { t = _type; break; }
993 }
994 t = t->meet_speculative(ti);
995 }
996 }
997
998 // The worst-case type (from ciTypeFlow) should be consistent with "t".
999 // That is, we expect that "t->higher_equal(_type)" holds true.
1000 // There are various exceptions:
1001 // - Inputs which are phis might in fact be widened unnecessarily.
1002 // For example, an input might be a widened int while the phi is a short.
1003 // - Inputs might be BotPtrs but this phi is dependent on a null check,
1004 // and postCCP has removed the cast which encodes the result of the check.
1005 // - The type of this phi is an interface, and the inputs are classes.
1006 // - Value calls on inputs might produce fuzzy results.
1007 // (Occurrences of this case suggest improvements to Value methods.)
1008 //
1009 // It is not possible to see Type::BOTTOM values as phi inputs,
1010 // because the ciTypeFlow pre-pass produces verifier-quality types.
1011 const Type* ft = t->filter_speculative(_type); // Worst case type
1012
1013 #ifdef ASSERT
1014 // The following logic has been moved into TypeOopPtr::filter.
1015 const Type* jt = t->join_speculative(_type);
1016 if (jt->empty()) { // Emptied out???
1017
1018 // Check for evil case of 't' being a class and '_type' expecting an
1019 // interface. This can happen because the bytecodes do not contain
1020 // enough type info to distinguish a Java-level interface variable
1021 // from a Java-level object variable. If we meet 2 classes which
1022 // both implement interface I, but their meet is at 'j/l/O' which
1023 // doesn't implement I, we have no way to tell if the result should
1024 // be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows
1025 // into a Phi which "knows" it's an Interface type we'll have to
1026 // uplift the type.
1027 if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
1028 assert(ft == _type, ""); // Uplift to interface
1029 } else if (!t->empty() && ttkp != NULL && ttkp->is_loaded() && ttkp->klass()->is_interface()) {
1030 assert(ft == _type, ""); // Uplift to interface
1031 } else {
1032 // We also have to handle 'evil cases' of interface- vs. class-arrays
1033 Type::get_arrays_base_elements(jt, _type, NULL, &ttip);
1034 if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
1035 assert(ft == _type, ""); // Uplift to array of interface
1036 } else {
1037 // Otherwise it's something stupid like non-overlapping int ranges
1038 // found on dying counted loops.
1039 assert(ft == Type::TOP, ""); // Canonical empty value
1040 }
1041 }
1042 }
1043
1044 else {
1045
1046 // If we have an interface-typed Phi and we narrow to a class type, the join
1047 // should report back the class. However, if we have a J/L/Object
1048 // class-typed Phi and an interface flows in, it's possible that the meet &
1049 // join report an interface back out. This isn't possible but happens
1050 // because the type system doesn't interact well with interfaces.
1051 const TypePtr *jtp = jt->make_ptr();
1052 const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL;
1053 const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_klassptr() : NULL;
1054 if( jtip && ttip ) {
1055 if( jtip->is_loaded() && jtip->klass()->is_interface() &&
1056 ttip->is_loaded() && !ttip->klass()->is_interface() ) {
1057 assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) ||
1058 ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), "");
1059 jt = ft;
1060 }
1061 }
1062 if( jtkp && ttkp ) {
1063 if( jtkp->is_loaded() && jtkp->klass()->is_interface() &&
1064 !jtkp->klass_is_exact() && // Keep exact interface klass (6894807)
1065 ttkp->is_loaded() && !ttkp->klass()->is_interface() ) {
1066 assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) ||
1067 ft->isa_narrowklass() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), "");
1068 jt = ft;
1069 }
1070 }
1071 if (jt != ft && jt->base() == ft->base()) {
1072 if (jt->isa_int() &&
1073 jt->is_int()->_lo == ft->is_int()->_lo &&
1074 jt->is_int()->_hi == ft->is_int()->_hi)
1075 jt = ft;
1076 if (jt->isa_long() &&
1077 jt->is_long()->_lo == ft->is_long()->_lo &&
1078 jt->is_long()->_hi == ft->is_long()->_hi)
1079 jt = ft;
1080 }
1081 if (jt != ft) {
1082 tty->print("merge type: "); t->dump(); tty->cr();
1083 tty->print("kill type: "); _type->dump(); tty->cr();
1084 tty->print("join type: "); jt->dump(); tty->cr();
1085 tty->print("filter type: "); ft->dump(); tty->cr();
1086 }
1087 assert(jt == ft, "");
1088 }
1089 #endif //ASSERT
1090
1091 // Deal with conversion problems found in data loops.
1092 ft = phase->saturate(ft, phase->type_or_null(this), _type);
1093
1094 return ft;
1095 }
1096
1097
1098 //------------------------------is_diamond_phi---------------------------------
1099 // Does this Phi represent a simple well-shaped diamond merge? Return the
1100 // index of the true path or 0 otherwise.
1101 // If check_control_only is true, do not inspect the If node at the
1102 // top, and return -1 (not an edge number) on success.
1103 int PhiNode::is_diamond_phi(bool check_control_only) const {
1104 // Check for a 2-path merge
1105 Node *region = in(0);
1106 if( !region ) return 0;
1107 if( region->req() != 3 ) return 0;
1108 if( req() != 3 ) return 0;
1109 // Check that both paths come from the same If
1110 Node *ifp1 = region->in(1);
1111 Node *ifp2 = region->in(2);
1112 if( !ifp1 || !ifp2 ) return 0;
1113 Node *iff = ifp1->in(0);
1114 if( !iff || !iff->is_If() ) return 0;
1115 if( iff != ifp2->in(0) ) return 0;
1116 if (check_control_only) return -1;
1117 // Check for a proper bool/cmp
1118 const Node *b = iff->in(1);
1119 if( !b->is_Bool() ) return 0;
1120 const Node *cmp = b->in(1);
1121 if( !cmp->is_Cmp() ) return 0;
1122
1123 // Check for branching opposite expected
1124 if( ifp2->Opcode() == Op_IfTrue ) {
1125 assert( ifp1->Opcode() == Op_IfFalse, "" );
1126 return 2;
1127 } else {
1128 assert( ifp1->Opcode() == Op_IfTrue, "" );
1129 return 1;
1130 }
1131 }
1132
1133 //----------------------------check_cmove_id-----------------------------------
1134 // Check for CMove'ing a constant after comparing against the constant.
1135 // Happens all the time now, since if we compare equality vs a constant in
1136 // the parser, we "know" the variable is constant on one path and we force
1137 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
1138 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more
1139 // general in that we don't need constants. Since CMove's are only inserted
1140 // in very special circumstances, we do it here on generic Phi's.
1141 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
1142 assert(true_path !=0, "only diamond shape graph expected");
1143
1144 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1145 // phi->region->if_proj->ifnode->bool->cmp
1146 Node* region = in(0);
1147 Node* iff = region->in(1)->in(0);
1148 BoolNode* b = iff->in(1)->as_Bool();
1149 Node* cmp = b->in(1);
1150 Node* tval = in(true_path);
1151 Node* fval = in(3-true_path);
1152 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
1153 if (id == NULL)
1154 return NULL;
1155
1156 // Either value might be a cast that depends on a branch of 'iff'.
1157 // Since the 'id' value will float free of the diamond, either
1158 // decast or return failure.
1159 Node* ctl = id->in(0);
1160 if (ctl != NULL && ctl->in(0) == iff) {
1161 if (id->is_ConstraintCast()) {
1162 return id->in(1);
1163 } else {
1164 // Don't know how to disentangle this value.
1165 return NULL;
1166 }
1167 }
1168
1169 return id;
1170 }
1171
1172 //------------------------------Identity---------------------------------------
1173 // Check for Region being Identity.
1174 Node* PhiNode::Identity(PhaseGVN* phase) {
1175 // Check for no merging going on
1176 // (There used to be special-case code here when this->region->is_Loop.
1177 // It would check for a tributary phi on the backedge that the main phi
1178 // trivially, perhaps with a single cast. The unique_input method
1179 // does all this and more, by reducing such tributaries to 'this'.)
1180 Node* uin = unique_input(phase, false);
1181 if (uin != NULL) {
1182 return uin;
1183 }
1184
1185 int true_path = is_diamond_phi();
1186 if (true_path != 0) {
1187 Node* id = is_cmove_id(phase, true_path);
1188 if (id != NULL) return id;
1189 }
1190
1191 return this; // No identity
1192 }
1193
1194 //-----------------------------unique_input------------------------------------
1195 // Find the unique value, discounting top, self-loops, and casts.
1196 // Return top if there are no inputs, and self if there are multiple.
1197 Node* PhiNode::unique_input(PhaseTransform* phase, bool uncast) {
1198 // 1) One unique direct input,
1199 // or if uncast is true:
1200 // 2) some of the inputs have an intervening ConstraintCast
1201 // 3) an input is a self loop
1202 //
1203 // 1) input or 2) input or 3) input __
1204 // / \ / \ \ / \
1205 // \ / | cast phi cast
1206 // phi \ / / \ /
1207 // phi / --
1208
1209 Node* r = in(0); // RegionNode
1210 if (r == NULL) return in(1); // Already degraded to a Copy
1211 Node* input = NULL; // The unique direct input (maybe uncasted = ConstraintCasts removed)
1212
1213 for (uint i = 1, cnt = req(); i < cnt; ++i) {
1214 Node* rc = r->in(i);
1215 if (rc == NULL || phase->type(rc) == Type::TOP)
1216 continue; // ignore unreachable control path
1217 Node* n = in(i);
1218 if (n == NULL)
1219 continue;
1220 Node* un = n;
1221 if (uncast) {
1222 #ifdef ASSERT
1223 Node* m = un->uncast();
1224 #endif
1225 while (un != NULL && un->req() == 2 && un->is_ConstraintCast()) {
1226 Node* next = un->in(1);
1227 if (phase->type(next)->isa_rawptr() && phase->type(un)->isa_oopptr()) {
1228 // risk exposing raw ptr at safepoint
1229 break;
1230 }
1231 un = next;
1232 }
1233 assert(m == un || un->in(1) == m, "Only expected at CheckCastPP from allocation");
1234 }
1235 if (un == NULL || un == this || phase->type(un) == Type::TOP) {
1236 continue; // ignore if top, or in(i) and "this" are in a data cycle
1237 }
1238 // Check for a unique input (maybe uncasted)
1239 if (input == NULL) {
1240 input = un;
1241 } else if (input != un) {
1242 input = NodeSentinel; // no unique input
1243 }
1244 }
1245 if (input == NULL) {
1246 return phase->C->top(); // no inputs
1247 }
1248
1249 if (input != NodeSentinel) {
1250 return input; // one unique direct input
1251 }
1252
1253 // Nothing.
1254 return NULL;
1255 }
1256
1257 //------------------------------is_x2logic-------------------------------------
1258 // Check for simple convert-to-boolean pattern
1259 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
1260 // Convert Phi to an ConvIB.
1261 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
1262 assert(true_path !=0, "only diamond shape graph expected");
1263 // Convert the true/false index into an expected 0/1 return.
1264 // Map 2->0 and 1->1.
1265 int flipped = 2-true_path;
1266
1267 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1268 // phi->region->if_proj->ifnode->bool->cmp
1269 Node *region = phi->in(0);
1270 Node *iff = region->in(1)->in(0);
1271 BoolNode *b = (BoolNode*)iff->in(1);
1272 const CmpNode *cmp = (CmpNode*)b->in(1);
1273
1274 Node *zero = phi->in(1);
1275 Node *one = phi->in(2);
1276 const Type *tzero = phase->type( zero );
1277 const Type *tone = phase->type( one );
1278
1279 // Check for compare vs 0
1280 const Type *tcmp = phase->type(cmp->in(2));
1281 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
1282 // Allow cmp-vs-1 if the other input is bounded by 0-1
1283 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
1284 return NULL;
1285 flipped = 1-flipped; // Test is vs 1 instead of 0!
1286 }
1287
1288 // Check for setting zero/one opposite expected
1289 if( tzero == TypeInt::ZERO ) {
1290 if( tone == TypeInt::ONE ) {
1291 } else return NULL;
1292 } else if( tzero == TypeInt::ONE ) {
1293 if( tone == TypeInt::ZERO ) {
1294 flipped = 1-flipped;
1295 } else return NULL;
1296 } else return NULL;
1297
1298 // Check for boolean test backwards
1299 if( b->_test._test == BoolTest::ne ) {
1300 } else if( b->_test._test == BoolTest::eq ) {
1301 flipped = 1-flipped;
1302 } else return NULL;
1303
1304 // Build int->bool conversion
1305 Node *n = new Conv2BNode( cmp->in(1) );
1306 if( flipped )
1307 n = new XorINode( phase->transform(n), phase->intcon(1) );
1308
1309 return n;
1310 }
1311
1312 //------------------------------is_cond_add------------------------------------
1313 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;"
1314 // To be profitable the control flow has to disappear; there can be no other
1315 // values merging here. We replace the test-and-branch with:
1316 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by
1317 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
1318 // Then convert Y to 0-or-Y and finally add.
1319 // This is a key transform for SpecJava _201_compress.
1320 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
1321 assert(true_path !=0, "only diamond shape graph expected");
1322
1323 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1324 // phi->region->if_proj->ifnode->bool->cmp
1325 RegionNode *region = (RegionNode*)phi->in(0);
1326 Node *iff = region->in(1)->in(0);
1327 BoolNode* b = iff->in(1)->as_Bool();
1328 const CmpNode *cmp = (CmpNode*)b->in(1);
1329
1330 // Make sure only merging this one phi here
1331 if (region->has_unique_phi() != phi) return NULL;
1332
1333 // Make sure each arm of the diamond has exactly one output, which we assume
1334 // is the region. Otherwise, the control flow won't disappear.
1335 if (region->in(1)->outcnt() != 1) return NULL;
1336 if (region->in(2)->outcnt() != 1) return NULL;
1337
1338 // Check for "(P < Q)" of type signed int
1339 if (b->_test._test != BoolTest::lt) return NULL;
1340 if (cmp->Opcode() != Op_CmpI) return NULL;
1341
1342 Node *p = cmp->in(1);
1343 Node *q = cmp->in(2);
1344 Node *n1 = phi->in( true_path);
1345 Node *n2 = phi->in(3-true_path);
1346
1347 int op = n1->Opcode();
1348 if( op != Op_AddI // Need zero as additive identity
1349 /*&&op != Op_SubI &&
1350 op != Op_AddP &&
1351 op != Op_XorI &&
1352 op != Op_OrI*/ )
1353 return NULL;
1354
1355 Node *x = n2;
1356 Node *y = NULL;
1357 if( x == n1->in(1) ) {
1358 y = n1->in(2);
1359 } else if( x == n1->in(2) ) {
1360 y = n1->in(1);
1361 } else return NULL;
1362
1363 // Not so profitable if compare and add are constants
1364 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
1365 return NULL;
1366
1367 Node *cmplt = phase->transform( new CmpLTMaskNode(p,q) );
1368 Node *j_and = phase->transform( new AndINode(cmplt,y) );
1369 return new AddINode(j_and,x);
1370 }
1371
1372 //------------------------------is_absolute------------------------------------
1373 // Check for absolute value.
1374 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
1375 assert(true_path !=0, "only diamond shape graph expected");
1376
1377 int cmp_zero_idx = 0; // Index of compare input where to look for zero
1378 int phi_x_idx = 0; // Index of phi input where to find naked x
1379
1380 // ABS ends with the merge of 2 control flow paths.
1381 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
1382 int false_path = 3 - true_path;
1383
1384 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1385 // phi->region->if_proj->ifnode->bool->cmp
1386 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
1387
1388 // Check bool sense
1389 switch( bol->_test._test ) {
1390 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break;
1391 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1392 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1393 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
1394 default: return NULL; break;
1395 }
1396
1397 // Test is next
1398 Node *cmp = bol->in(1);
1399 const Type *tzero = NULL;
1400 switch( cmp->Opcode() ) {
1401 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS
1402 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS
1403 default: return NULL;
1404 }
1405
1406 // Find zero input of compare; the other input is being abs'd
1407 Node *x = NULL;
1408 bool flip = false;
1409 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
1410 x = cmp->in(3 - cmp_zero_idx);
1411 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
1412 // The test is inverted, we should invert the result...
1413 x = cmp->in(cmp_zero_idx);
1414 flip = true;
1415 } else {
1416 return NULL;
1417 }
1418
1419 // Next get the 2 pieces being selected, one is the original value
1420 // and the other is the negated value.
1421 if( phi_root->in(phi_x_idx) != x ) return NULL;
1422
1423 // Check other phi input for subtract node
1424 Node *sub = phi_root->in(3 - phi_x_idx);
1425
1426 // Allow only Sub(0,X) and fail out for all others; Neg is not OK
1427 if( tzero == TypeF::ZERO ) {
1428 if( sub->Opcode() != Op_SubF ||
1429 sub->in(2) != x ||
1430 phase->type(sub->in(1)) != tzero ) return NULL;
1431 x = new AbsFNode(x);
1432 if (flip) {
1433 x = new SubFNode(sub->in(1), phase->transform(x));
1434 }
1435 } else {
1436 if( sub->Opcode() != Op_SubD ||
1437 sub->in(2) != x ||
1438 phase->type(sub->in(1)) != tzero ) return NULL;
1439 x = new AbsDNode(x);
1440 if (flip) {
1441 x = new SubDNode(sub->in(1), phase->transform(x));
1442 }
1443 }
1444
1445 return x;
1446 }
1447
1448 //------------------------------split_once-------------------------------------
1449 // Helper for split_flow_path
1450 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
1451 igvn->hash_delete(n); // Remove from hash before hacking edges
1452
1453 uint j = 1;
1454 for (uint i = phi->req()-1; i > 0; i--) {
1455 if (phi->in(i) == val) { // Found a path with val?
1456 // Add to NEW Region/Phi, no DU info
1457 newn->set_req( j++, n->in(i) );
1458 // Remove from OLD Region/Phi
1459 n->del_req(i);
1460 }
1461 }
1462
1463 // Register the new node but do not transform it. Cannot transform until the
1464 // entire Region/Phi conglomerate has been hacked as a single huge transform.
1465 igvn->register_new_node_with_optimizer( newn );
1466
1467 // Now I can point to the new node.
1468 n->add_req(newn);
1469 igvn->_worklist.push(n);
1470 }
1471
1472 //------------------------------split_flow_path--------------------------------
1473 // Check for merging identical values and split flow paths
1474 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) {
1475 BasicType bt = phi->type()->basic_type();
1476 if( bt == T_ILLEGAL || type2size[bt] <= 0 )
1477 return NULL; // Bail out on funny non-value stuff
1478 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a
1479 return NULL; // third unequal input to be worth doing
1480
1481 // Scan for a constant
1482 uint i;
1483 for( i = 1; i < phi->req()-1; i++ ) {
1484 Node *n = phi->in(i);
1485 if( !n ) return NULL;
1486 if( phase->type(n) == Type::TOP ) return NULL;
1487 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN || n->Opcode() == Op_ConNKlass )
1488 break;
1489 }
1490 if( i >= phi->req() ) // Only split for constants
1491 return NULL;
1492
1493 Node *val = phi->in(i); // Constant to split for
1494 uint hit = 0; // Number of times it occurs
1495 Node *r = phi->region();
1496
1497 for( ; i < phi->req(); i++ ){ // Count occurrences of constant
1498 Node *n = phi->in(i);
1499 if( !n ) return NULL;
1500 if( phase->type(n) == Type::TOP ) return NULL;
1501 if( phi->in(i) == val ) {
1502 hit++;
1503 if (PhaseIdealLoop::find_predicate(r->in(i)) != NULL) {
1504 return NULL; // don't split loop entry path
1505 }
1506 }
1507 }
1508
1509 if( hit <= 1 || // Make sure we find 2 or more
1510 hit == phi->req()-1 ) // and not ALL the same value
1511 return NULL;
1512
1513 // Now start splitting out the flow paths that merge the same value.
1514 // Split first the RegionNode.
1515 PhaseIterGVN *igvn = phase->is_IterGVN();
1516 RegionNode *newr = new RegionNode(hit+1);
1517 split_once(igvn, phi, val, r, newr);
1518
1519 // Now split all other Phis than this one
1520 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) {
1521 Node* phi2 = r->fast_out(k);
1522 if( phi2->is_Phi() && phi2->as_Phi() != phi ) {
1523 PhiNode *newphi = PhiNode::make_blank(newr, phi2);
1524 split_once(igvn, phi, val, phi2, newphi);
1525 }
1526 }
1527
1528 // Clean up this guy
1529 igvn->hash_delete(phi);
1530 for( i = phi->req()-1; i > 0; i-- ) {
1531 if( phi->in(i) == val ) {
1532 phi->del_req(i);
1533 }
1534 }
1535 phi->add_req(val);
1536
1537 return phi;
1538 }
1539
1540 //=============================================================================
1541 //------------------------------simple_data_loop_check-------------------------
1542 // Try to determining if the phi node in a simple safe/unsafe data loop.
1543 // Returns:
1544 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
1545 // Safe - safe case when the phi and it's inputs reference only safe data
1546 // nodes;
1547 // Unsafe - the phi and it's inputs reference unsafe data nodes but there
1548 // is no reference back to the phi - need a graph walk
1549 // to determine if it is in a loop;
1550 // UnsafeLoop - unsafe case when the phi references itself directly or through
1551 // unsafe data node.
1552 // Note: a safe data node is a node which could/never reference itself during
1553 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP.
1554 // I mark Phi nodes as safe node not only because they can reference itself
1555 // but also to prevent mistaking the fallthrough case inside an outer loop
1556 // as dead loop when the phi references itselfs through an other phi.
1557 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const {
1558 // It is unsafe loop if the phi node references itself directly.
1559 if (in == (Node*)this)
1560 return UnsafeLoop; // Unsafe loop
1561 // Unsafe loop if the phi node references itself through an unsafe data node.
1562 // Exclude cases with null inputs or data nodes which could reference
1563 // itself (safe for dead loops).
1564 if (in != NULL && !in->is_dead_loop_safe()) {
1565 // Check inputs of phi's inputs also.
1566 // It is much less expensive then full graph walk.
1567 uint cnt = in->req();
1568 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1;
1569 for (; i < cnt; ++i) {
1570 Node* m = in->in(i);
1571 if (m == (Node*)this)
1572 return UnsafeLoop; // Unsafe loop
1573 if (m != NULL && !m->is_dead_loop_safe()) {
1574 // Check the most common case (about 30% of all cases):
1575 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con).
1576 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL;
1577 if (m1 == (Node*)this)
1578 return UnsafeLoop; // Unsafe loop
1579 if (m1 != NULL && m1 == m->in(2) &&
1580 m1->is_dead_loop_safe() && m->in(3)->is_Con()) {
1581 continue; // Safe case
1582 }
1583 // The phi references an unsafe node - need full analysis.
1584 return Unsafe;
1585 }
1586 }
1587 }
1588 return Safe; // Safe case - we can optimize the phi node.
1589 }
1590
1591 //------------------------------is_unsafe_data_reference-----------------------
1592 // If phi can be reached through the data input - it is data loop.
1593 bool PhiNode::is_unsafe_data_reference(Node *in) const {
1594 assert(req() > 1, "");
1595 // First, check simple cases when phi references itself directly or
1596 // through an other node.
1597 LoopSafety safety = simple_data_loop_check(in);
1598 if (safety == UnsafeLoop)
1599 return true; // phi references itself - unsafe loop
1600 else if (safety == Safe)
1601 return false; // Safe case - phi could be replaced with the unique input.
1602
1603 // Unsafe case when we should go through data graph to determine
1604 // if the phi references itself.
1605
1606 ResourceMark rm;
1607
1608 Arena *a = Thread::current()->resource_area();
1609 Node_List nstack(a);
1610 VectorSet visited(a);
1611
1612 nstack.push(in); // Start with unique input.
1613 visited.set(in->_idx);
1614 while (nstack.size() != 0) {
1615 Node* n = nstack.pop();
1616 uint cnt = n->req();
1617 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1;
1618 for (; i < cnt; i++) {
1619 Node* m = n->in(i);
1620 if (m == (Node*)this) {
1621 return true; // Data loop
1622 }
1623 if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases.
1624 if (!visited.test_set(m->_idx))
1625 nstack.push(m);
1626 }
1627 }
1628 }
1629 return false; // The phi is not reachable from its inputs
1630 }
1631
1632
1633 //------------------------------Ideal------------------------------------------
1634 // Return a node which is more "ideal" than the current node. Must preserve
1635 // the CFG, but we can still strip out dead paths.
1636 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1637 // The next should never happen after 6297035 fix.
1638 if( is_copy() ) // Already degraded to a Copy ?
1639 return NULL; // No change
1640
1641 Node *r = in(0); // RegionNode
1642 assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge");
1643
1644 // Note: During parsing, phis are often transformed before their regions.
1645 // This means we have to use type_or_null to defend against untyped regions.
1646 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1647 return NULL; // No change
1648
1649 // If all inputs are value types of the same type, push the value type node down
1650 // through the phi because value type nodes should be merged through their input values.
1651 if (req() > 2 && in(1) != NULL && in(1)->is_ValueTypeBase() && (can_reshape || in(1)->is_ValueType())) {
1652 int opcode = in(1)->Opcode();
1653 uint i = 2;
1654 // Check if inputs are values of the same type
1655 for (; i < req() && in(i) && in(i)->is_ValueTypeBase() && in(i)->cmp(*in(1)); i++) {
1656 assert(in(i)->Opcode() == opcode, "mixing pointers and values?");
1657 }
1658 if (i == req()) {
1659 ValueTypeBaseNode* vt = in(1)->as_ValueTypeBase()->clone_with_phis(phase, in(0));
1660 for (uint i = 2; i < req(); ++i) {
1661 vt->merge_with(phase, in(i)->as_ValueTypeBase(), i, i == (req()-1));
1662 }
1663 return vt;
1664 }
1665 }
1666
1667 if (type()->is_valuetypeptr() && can_reshape) {
1668 // If the Phi merges the result from a mix of constant and non
1669 // constant method handles, only some of its inputs are
1670 // ValueTypePtr nodes and we can't push the ValueTypePtr node down
1671 // to remove the need for allocations. This if fixed by transforming:
1672 //
1673 // (Phi ValueTypePtr#1 Node#2) to (Phi ValueTypePtr#1 CheckCastPP#2)
1674 //
1675 // Then pushing the CheckCastPP up through Phis until it reaches
1676 // the non constant method handle call. The type of the return
1677 // value is then known from the type of the CheckCastPP. A
1678 // ValueTypePtr can be created by adding projections to the call
1679 // for all values being returned. See
1680 // CheckCastPPNode::Ideal(). That ValueTypePtr node can then be
1681 // pushed down through Phis.
1682 const TypeInstPtr* ti = NULL;
1683 for (uint i = 1; i < req(); i++) {
1684 if (in(i) != NULL && in(i)->is_ValueTypePtr()) {
1685 const TypeInstPtr* t = phase->type(in(i))->is_instptr();
1686 t = t->cast_to_ptr_type(TypePtr::BotPTR)->is_instptr();
1687 if (ti == NULL) {
1688 ti = t;
1689 } else {
1690 assert(ti == t, "Phi should merge identical value types");
1691 }
1692 } else {
1693 assert(in(i) == NULL || ti == NULL || phase->type(in(i))->higher_equal(ti) || phase->type(in(i)) == Type::TOP, "bad type");
1694 }
1695 }
1696 if (ti != NULL) {
1697 // One input is a value type. All inputs must have the same type.
1698 bool progress = false;
1699 PhaseIterGVN* igvn = phase->is_IterGVN();
1700 for (uint i = 1; i < req(); i++) {
1701 if (in(i) != NULL && !in(i)->is_Con() && !phase->type(in(i))->higher_equal(ti)) {
1702 // Can't transform because CheckCastPPNode::Identity can
1703 // push the cast up through another Phi and cause this same
1704 // transformation to run again, indefinitely
1705 Node* cast = igvn->register_new_node_with_optimizer(new CheckCastPPNode(NULL, in(i), ti));
1706 set_req(i, cast);
1707 progress = true;
1708 }
1709 }
1710 if (progress) {
1711 return this;
1712 }
1713 }
1714 }
1715
1716 Node *top = phase->C->top();
1717 bool new_phi = (outcnt() == 0); // transforming new Phi
1718 // No change for igvn if new phi is not hooked
1719 if (new_phi && can_reshape)
1720 return NULL;
1721
1722 // The are 2 situations when only one valid phi's input is left
1723 // (in addition to Region input).
1724 // One: region is not loop - replace phi with this input.
1725 // Two: region is loop - replace phi with top since this data path is dead
1726 // and we need to break the dead data loop.
1727 Node* progress = NULL; // Record if any progress made
1728 for( uint j = 1; j < req(); ++j ){ // For all paths in
1729 // Check unreachable control paths
1730 Node* rc = r->in(j);
1731 Node* n = in(j); // Get the input
1732 if (rc == NULL || phase->type(rc) == Type::TOP) {
1733 if (n != top) { // Not already top?
1734 PhaseIterGVN *igvn = phase->is_IterGVN();
1735 if (can_reshape && igvn != NULL) {
1736 igvn->_worklist.push(r);
1737 }
1738 set_req(j, top); // Nuke it down
1739 progress = this; // Record progress
1740 }
1741 }
1742 }
1743
1744 if (can_reshape && outcnt() == 0) {
1745 // set_req() above may kill outputs if Phi is referenced
1746 // only by itself on the dead (top) control path.
1747 return top;
1748 }
1749
1750 bool uncasted = false;
1751 Node* uin = unique_input(phase, false);
1752 if (uin == NULL && can_reshape) {
1753 uncasted = true;
1754 uin = unique_input(phase, true);
1755 }
1756 if (uin == top) { // Simplest case: no alive inputs.
1757 if (can_reshape) // IGVN transformation
1758 return top;
1759 else
1760 return NULL; // Identity will return TOP
1761 } else if (uin != NULL) {
1762 // Only one not-NULL unique input path is left.
1763 // Determine if this input is backedge of a loop.
1764 // (Skip new phis which have no uses and dead regions).
1765 if (outcnt() > 0 && r->in(0) != NULL) {
1766 // First, take the short cut when we know it is a loop and
1767 // the EntryControl data path is dead.
1768 // Loop node may have only one input because entry path
1769 // is removed in PhaseIdealLoop::Dominators().
1770 assert(!r->is_Loop() || r->req() <= 3, "Loop node should have 3 or less inputs");
1771 bool is_loop = (r->is_Loop() && r->req() == 3);
1772 // Then, check if there is a data loop when phi references itself directly
1773 // or through other data nodes.
1774 if ((is_loop && !uin->eqv_uncast(in(LoopNode::EntryControl))) ||
1775 (!is_loop && is_unsafe_data_reference(uin))) {
1776 // Break this data loop to avoid creation of a dead loop.
1777 if (can_reshape) {
1778 return top;
1779 } else {
1780 // We can't return top if we are in Parse phase - cut inputs only
1781 // let Identity to handle the case.
1782 replace_edge(uin, top);
1783 return NULL;
1784 }
1785 }
1786 }
1787
1788 if (uncasted) {
1789 // Add cast nodes between the phi to be removed and its unique input.
1790 // Wait until after parsing for the type information to propagate from the casts.
1791 assert(can_reshape, "Invalid during parsing");
1792 const Type* phi_type = bottom_type();
1793 assert(phi_type->isa_int() || phi_type->isa_ptr(), "bad phi type");
1794 // Add casts to carry the control dependency of the Phi that is
1795 // going away
1796 Node* cast = NULL;
1797 if (phi_type->isa_int()) {
1798 cast = ConstraintCastNode::make_cast(Op_CastII, r, uin, phi_type, true);
1799 } else {
1800 const Type* uin_type = phase->type(uin);
1801 if (!phi_type->isa_oopptr() && !uin_type->isa_oopptr()) {
1802 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true);
1803 } else {
1804 // Use a CastPP for a cast to not null and a CheckCastPP for
1805 // a cast to a new klass (and both if both null-ness and
1806 // klass change).
1807
1808 // If the type of phi is not null but the type of uin may be
1809 // null, uin's type must be casted to not null
1810 if (phi_type->join(TypePtr::NOTNULL) == phi_type->remove_speculative() &&
1811 uin_type->join(TypePtr::NOTNULL) != uin_type->remove_speculative()) {
1812 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, TypePtr::NOTNULL, true);
1813 }
1814
1815 // If the type of phi and uin, both casted to not null,
1816 // differ the klass of uin must be (check)cast'ed to match
1817 // that of phi
1818 if (phi_type->join_speculative(TypePtr::NOTNULL) != uin_type->join_speculative(TypePtr::NOTNULL)) {
1819 Node* n = uin;
1820 if (cast != NULL) {
1821 cast = phase->transform(cast);
1822 n = cast;
1823 }
1824 cast = ConstraintCastNode::make_cast(Op_CheckCastPP, r, n, phi_type, true);
1825 }
1826 if (cast == NULL) {
1827 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true);
1828 }
1829 }
1830 }
1831 assert(cast != NULL, "cast should be set");
1832 cast = phase->transform(cast);
1833 // set all inputs to the new cast(s) so the Phi is removed by Identity
1834 PhaseIterGVN* igvn = phase->is_IterGVN();
1835 for (uint i = 1; i < req(); i++) {
1836 set_req_X(i, cast, igvn);
1837 }
1838 uin = cast;
1839 }
1840
1841 // One unique input.
1842 debug_only(Node* ident = Identity(phase));
1843 // The unique input must eventually be detected by the Identity call.
1844 #ifdef ASSERT
1845 if (ident != uin && !ident->is_top()) {
1846 // print this output before failing assert
1847 r->dump(3);
1848 this->dump(3);
1849 ident->dump();
1850 uin->dump();
1851 }
1852 #endif
1853 assert(ident == uin || ident->is_top(), "Identity must clean this up");
1854 return NULL;
1855 }
1856
1857 Node* opt = NULL;
1858 int true_path = is_diamond_phi();
1859 if( true_path != 0 ) {
1860 // Check for CMove'ing identity. If it would be unsafe,
1861 // handle it here. In the safe case, let Identity handle it.
1862 Node* unsafe_id = is_cmove_id(phase, true_path);
1863 if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) )
1864 opt = unsafe_id;
1865
1866 // Check for simple convert-to-boolean pattern
1867 if( opt == NULL )
1868 opt = is_x2logic(phase, this, true_path);
1869
1870 // Check for absolute value
1871 if( opt == NULL )
1872 opt = is_absolute(phase, this, true_path);
1873
1874 // Check for conditional add
1875 if( opt == NULL && can_reshape )
1876 opt = is_cond_add(phase, this, true_path);
1877
1878 // These 4 optimizations could subsume the phi:
1879 // have to check for a dead data loop creation.
1880 if( opt != NULL ) {
1881 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) {
1882 // Found dead loop.
1883 if( can_reshape )
1884 return top;
1885 // We can't return top if we are in Parse phase - cut inputs only
1886 // to stop further optimizations for this phi. Identity will return TOP.
1887 assert(req() == 3, "only diamond merge phi here");
1888 set_req(1, top);
1889 set_req(2, top);
1890 return NULL;
1891 } else {
1892 return opt;
1893 }
1894 }
1895 }
1896
1897 // Check for merging identical values and split flow paths
1898 if (can_reshape) {
1899 opt = split_flow_path(phase, this);
1900 // This optimization only modifies phi - don't need to check for dead loop.
1901 assert(opt == NULL || phase->eqv(opt, this), "do not elide phi");
1902 if (opt != NULL) return opt;
1903 }
1904
1905 if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) {
1906 // Try to undo Phi of AddP:
1907 // (Phi (AddP base base y) (AddP base2 base2 y))
1908 // becomes:
1909 // newbase := (Phi base base2)
1910 // (AddP newbase newbase y)
1911 //
1912 // This occurs as a result of unsuccessful split_thru_phi and
1913 // interferes with taking advantage of addressing modes. See the
1914 // clone_shift_expressions code in matcher.cpp
1915 Node* addp = in(1);
1916 const Type* type = addp->in(AddPNode::Base)->bottom_type();
1917 Node* y = addp->in(AddPNode::Offset);
1918 if (y != NULL && addp->in(AddPNode::Base) == addp->in(AddPNode::Address)) {
1919 // make sure that all the inputs are similar to the first one,
1920 // i.e. AddP with base == address and same offset as first AddP
1921 bool doit = true;
1922 for (uint i = 2; i < req(); i++) {
1923 if (in(i) == NULL ||
1924 in(i)->Opcode() != Op_AddP ||
1925 in(i)->in(AddPNode::Base) != in(i)->in(AddPNode::Address) ||
1926 in(i)->in(AddPNode::Offset) != y) {
1927 doit = false;
1928 break;
1929 }
1930 // Accumulate type for resulting Phi
1931 type = type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type());
1932 }
1933 Node* base = NULL;
1934 if (doit) {
1935 // Check for neighboring AddP nodes in a tree.
1936 // If they have a base, use that it.
1937 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) {
1938 Node* u = this->fast_out(k);
1939 if (u->is_AddP()) {
1940 Node* base2 = u->in(AddPNode::Base);
1941 if (base2 != NULL && !base2->is_top()) {
1942 if (base == NULL)
1943 base = base2;
1944 else if (base != base2)
1945 { doit = false; break; }
1946 }
1947 }
1948 }
1949 }
1950 if (doit) {
1951 if (base == NULL) {
1952 base = new PhiNode(in(0), type, NULL);
1953 for (uint i = 1; i < req(); i++) {
1954 base->init_req(i, in(i)->in(AddPNode::Base));
1955 }
1956 phase->is_IterGVN()->register_new_node_with_optimizer(base);
1957 }
1958 return new AddPNode(base, base, y);
1959 }
1960 }
1961 }
1962
1963 // Split phis through memory merges, so that the memory merges will go away.
1964 // Piggy-back this transformation on the search for a unique input....
1965 // It will be as if the merged memory is the unique value of the phi.
1966 // (Do not attempt this optimization unless parsing is complete.
1967 // It would make the parser's memory-merge logic sick.)
1968 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.)
1969 if (progress == NULL && can_reshape && type() == Type::MEMORY) {
1970 // see if this phi should be sliced
1971 uint merge_width = 0;
1972 bool saw_self = false;
1973 for( uint i=1; i<req(); ++i ) {// For all paths in
1974 Node *ii = in(i);
1975 // TOP inputs should not be counted as safe inputs because if the
1976 // Phi references itself through all other inputs then splitting the
1977 // Phi through memory merges would create dead loop at later stage.
1978 if (ii == top) {
1979 return NULL; // Delay optimization until graph is cleaned.
1980 }
1981 if (ii->is_MergeMem()) {
1982 MergeMemNode* n = ii->as_MergeMem();
1983 merge_width = MAX2(merge_width, n->req());
1984 saw_self = saw_self || phase->eqv(n->base_memory(), this);
1985 }
1986 }
1987
1988 // This restriction is temporarily necessary to ensure termination:
1989 if (!saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0;
1990
1991 if (merge_width > Compile::AliasIdxRaw) {
1992 // found at least one non-empty MergeMem
1993 const TypePtr* at = adr_type();
1994 if (at != TypePtr::BOTTOM) {
1995 // Patch the existing phi to select an input from the merge:
1996 // Phi:AT1(...MergeMem(m0, m1, m2)...) into
1997 // Phi:AT1(...m1...)
1998 int alias_idx = phase->C->get_alias_index(at);
1999 for (uint i=1; i<req(); ++i) {
2000 Node *ii = in(i);
2001 if (ii->is_MergeMem()) {
2002 MergeMemNode* n = ii->as_MergeMem();
2003 // compress paths and change unreachable cycles to TOP
2004 // If not, we can update the input infinitely along a MergeMem cycle
2005 // Equivalent code is in MemNode::Ideal_common
2006 Node *m = phase->transform(n);
2007 if (outcnt() == 0) { // Above transform() may kill us!
2008 return top;
2009 }
2010 // If transformed to a MergeMem, get the desired slice
2011 // Otherwise the returned node represents memory for every slice
2012 Node *new_mem = (m->is_MergeMem()) ?
2013 m->as_MergeMem()->memory_at(alias_idx) : m;
2014 // Update input if it is progress over what we have now
2015 if (new_mem != ii) {
2016 set_req(i, new_mem);
2017 progress = this;
2018 }
2019 }
2020 }
2021 } else {
2022 // We know that at least one MergeMem->base_memory() == this
2023 // (saw_self == true). If all other inputs also references this phi
2024 // (directly or through data nodes) - it is dead loop.
2025 bool saw_safe_input = false;
2026 for (uint j = 1; j < req(); ++j) {
2027 Node *n = in(j);
2028 if (n->is_MergeMem() && n->as_MergeMem()->base_memory() == this)
2029 continue; // skip known cases
2030 if (!is_unsafe_data_reference(n)) {
2031 saw_safe_input = true; // found safe input
2032 break;
2033 }
2034 }
2035 if (!saw_safe_input)
2036 return top; // all inputs reference back to this phi - dead loop
2037
2038 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into
2039 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...))
2040 PhaseIterGVN *igvn = phase->is_IterGVN();
2041 Node* hook = new Node(1);
2042 PhiNode* new_base = (PhiNode*) clone();
2043 // Must eagerly register phis, since they participate in loops.
2044 if (igvn) {
2045 igvn->register_new_node_with_optimizer(new_base);
2046 hook->add_req(new_base);
2047 }
2048 MergeMemNode* result = MergeMemNode::make(new_base);
2049 for (uint i = 1; i < req(); ++i) {
2050 Node *ii = in(i);
2051 if (ii->is_MergeMem()) {
2052 MergeMemNode* n = ii->as_MergeMem();
2053 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) {
2054 // If we have not seen this slice yet, make a phi for it.
2055 bool made_new_phi = false;
2056 if (mms.is_empty()) {
2057 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C));
2058 made_new_phi = true;
2059 if (igvn) {
2060 igvn->register_new_node_with_optimizer(new_phi);
2061 hook->add_req(new_phi);
2062 }
2063 mms.set_memory(new_phi);
2064 }
2065 Node* phi = mms.memory();
2066 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice");
2067 phi->set_req(i, mms.memory2());
2068 }
2069 }
2070 }
2071 // Distribute all self-loops.
2072 { // (Extra braces to hide mms.)
2073 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2074 Node* phi = mms.memory();
2075 for (uint i = 1; i < req(); ++i) {
2076 if (phi->in(i) == this) phi->set_req(i, phi);
2077 }
2078 }
2079 }
2080 // now transform the new nodes, and return the mergemem
2081 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2082 Node* phi = mms.memory();
2083 mms.set_memory(phase->transform(phi));
2084 }
2085 if (igvn) { // Unhook.
2086 igvn->hash_delete(hook);
2087 for (uint i = 1; i < hook->req(); i++) {
2088 hook->set_req(i, NULL);
2089 }
2090 }
2091 // Replace self with the result.
2092 return result;
2093 }
2094 }
2095 //
2096 // Other optimizations on the memory chain
2097 //
2098 const TypePtr* at = adr_type();
2099 for( uint i=1; i<req(); ++i ) {// For all paths in
2100 Node *ii = in(i);
2101 Node *new_in = MemNode::optimize_memory_chain(ii, at, NULL, phase);
2102 if (ii != new_in ) {
2103 set_req(i, new_in);
2104 progress = this;
2105 }
2106 }
2107 }
2108
2109 #ifdef _LP64
2110 // Push DecodeN/DecodeNKlass down through phi.
2111 // The rest of phi graph will transform by split EncodeP node though phis up.
2112 if ((UseCompressedOops || UseCompressedClassPointers) && can_reshape && progress == NULL) {
2113 bool may_push = true;
2114 bool has_decodeN = false;
2115 bool is_decodeN = false;
2116 for (uint i=1; i<req(); ++i) {// For all paths in
2117 Node *ii = in(i);
2118 if (ii->is_DecodeNarrowPtr() && ii->bottom_type() == bottom_type()) {
2119 // Do optimization if a non dead path exist.
2120 if (ii->in(1)->bottom_type() != Type::TOP) {
2121 has_decodeN = true;
2122 is_decodeN = ii->is_DecodeN();
2123 }
2124 } else if (!ii->is_Phi()) {
2125 may_push = false;
2126 }
2127 }
2128
2129 if (has_decodeN && may_push) {
2130 PhaseIterGVN *igvn = phase->is_IterGVN();
2131 // Make narrow type for new phi.
2132 const Type* narrow_t;
2133 if (is_decodeN) {
2134 narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr());
2135 } else {
2136 narrow_t = TypeNarrowKlass::make(this->bottom_type()->is_ptr());
2137 }
2138 PhiNode* new_phi = new PhiNode(r, narrow_t);
2139 uint orig_cnt = req();
2140 for (uint i=1; i<req(); ++i) {// For all paths in
2141 Node *ii = in(i);
2142 Node* new_ii = NULL;
2143 if (ii->is_DecodeNarrowPtr()) {
2144 assert(ii->bottom_type() == bottom_type(), "sanity");
2145 new_ii = ii->in(1);
2146 } else {
2147 assert(ii->is_Phi(), "sanity");
2148 if (ii->as_Phi() == this) {
2149 new_ii = new_phi;
2150 } else {
2151 if (is_decodeN) {
2152 new_ii = new EncodePNode(ii, narrow_t);
2153 } else {
2154 new_ii = new EncodePKlassNode(ii, narrow_t);
2155 }
2156 igvn->register_new_node_with_optimizer(new_ii);
2157 }
2158 }
2159 new_phi->set_req(i, new_ii);
2160 }
2161 igvn->register_new_node_with_optimizer(new_phi, this);
2162 if (is_decodeN) {
2163 progress = new DecodeNNode(new_phi, bottom_type());
2164 } else {
2165 progress = new DecodeNKlassNode(new_phi, bottom_type());
2166 }
2167 }
2168 }
2169 #endif
2170
2171 return progress; // Return any progress
2172 }
2173
2174 //------------------------------is_tripcount-----------------------------------
2175 bool PhiNode::is_tripcount() const {
2176 return (in(0) != NULL && in(0)->is_CountedLoop() &&
2177 in(0)->as_CountedLoop()->phi() == this);
2178 }
2179
2180 //------------------------------out_RegMask------------------------------------
2181 const RegMask &PhiNode::in_RegMask(uint i) const {
2182 return i ? out_RegMask() : RegMask::Empty;
2183 }
2184
2185 const RegMask &PhiNode::out_RegMask() const {
2186 uint ideal_reg = _type->ideal_reg();
2187 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
2188 if( ideal_reg == 0 ) return RegMask::Empty;
2189 assert(ideal_reg != Op_RegFlags, "flags register is not spillable");
2190 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
2191 }
2192
2193 #ifndef PRODUCT
2194 void PhiNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2195 // For a PhiNode, the set of related nodes includes all inputs till level 2,
2196 // and all outputs till level 1. In compact mode, inputs till level 1 are
2197 // collected.
2198 this->collect_nodes(in_rel, compact ? 1 : 2, false, false);
2199 this->collect_nodes(out_rel, -1, false, false);
2200 }
2201
2202 void PhiNode::dump_spec(outputStream *st) const {
2203 TypeNode::dump_spec(st);
2204 if (is_tripcount()) {
2205 st->print(" #tripcount");
2206 }
2207 }
2208 #endif
2209
2210
2211 //=============================================================================
2212 const Type* GotoNode::Value(PhaseGVN* phase) const {
2213 // If the input is reachable, then we are executed.
2214 // If the input is not reachable, then we are not executed.
2215 return phase->type(in(0));
2216 }
2217
2218 Node* GotoNode::Identity(PhaseGVN* phase) {
2219 return in(0); // Simple copy of incoming control
2220 }
2221
2222 const RegMask &GotoNode::out_RegMask() const {
2223 return RegMask::Empty;
2224 }
2225
2226 #ifndef PRODUCT
2227 //-----------------------------related-----------------------------------------
2228 // The related nodes of a GotoNode are all inputs at level 1, as well as the
2229 // outputs at level 1. This is regardless of compact mode.
2230 void GotoNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2231 this->collect_nodes(in_rel, 1, false, false);
2232 this->collect_nodes(out_rel, -1, false, false);
2233 }
2234 #endif
2235
2236
2237 //=============================================================================
2238 const RegMask &JumpNode::out_RegMask() const {
2239 return RegMask::Empty;
2240 }
2241
2242 #ifndef PRODUCT
2243 //-----------------------------related-----------------------------------------
2244 // The related nodes of a JumpNode are all inputs at level 1, as well as the
2245 // outputs at level 2 (to include actual jump targets beyond projection nodes).
2246 // This is regardless of compact mode.
2247 void JumpNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2248 this->collect_nodes(in_rel, 1, false, false);
2249 this->collect_nodes(out_rel, -2, false, false);
2250 }
2251 #endif
2252
2253 //=============================================================================
2254 const RegMask &JProjNode::out_RegMask() const {
2255 return RegMask::Empty;
2256 }
2257
2258 //=============================================================================
2259 const RegMask &CProjNode::out_RegMask() const {
2260 return RegMask::Empty;
2261 }
2262
2263
2264
2265 //=============================================================================
2266
2267 uint PCTableNode::hash() const { return Node::hash() + _size; }
2268 uint PCTableNode::cmp( const Node &n ) const
2269 { return _size == ((PCTableNode&)n)._size; }
2270
2271 const Type *PCTableNode::bottom_type() const {
2272 const Type** f = TypeTuple::fields(_size);
2273 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2274 return TypeTuple::make(_size, f);
2275 }
2276
2277 //------------------------------Value------------------------------------------
2278 // Compute the type of the PCTableNode. If reachable it is a tuple of
2279 // Control, otherwise the table targets are not reachable
2280 const Type* PCTableNode::Value(PhaseGVN* phase) const {
2281 if( phase->type(in(0)) == Type::CONTROL )
2282 return bottom_type();
2283 return Type::TOP; // All paths dead? Then so are we
2284 }
2285
2286 //------------------------------Ideal------------------------------------------
2287 // Return a node which is more "ideal" than the current node. Strip out
2288 // control copies
2289 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2290 return remove_dead_region(phase, can_reshape) ? this : NULL;
2291 }
2292
2293 //=============================================================================
2294 uint JumpProjNode::hash() const {
2295 return Node::hash() + _dest_bci;
2296 }
2297
2298 uint JumpProjNode::cmp( const Node &n ) const {
2299 return ProjNode::cmp(n) &&
2300 _dest_bci == ((JumpProjNode&)n)._dest_bci;
2301 }
2302
2303 #ifndef PRODUCT
2304 void JumpProjNode::dump_spec(outputStream *st) const {
2305 ProjNode::dump_spec(st);
2306 st->print("@bci %d ",_dest_bci);
2307 }
2308
2309 void JumpProjNode::dump_compact_spec(outputStream *st) const {
2310 ProjNode::dump_compact_spec(st);
2311 st->print("(%d)%d@%d", _switch_val, _proj_no, _dest_bci);
2312 }
2313
2314 void JumpProjNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2315 // The related nodes of a JumpProjNode are its inputs and outputs at level 1.
2316 this->collect_nodes(in_rel, 1, false, false);
2317 this->collect_nodes(out_rel, -1, false, false);
2318 }
2319 #endif
2320
2321 //=============================================================================
2322 //------------------------------Value------------------------------------------
2323 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot
2324 // have the default "fall_through_index" path.
2325 const Type* CatchNode::Value(PhaseGVN* phase) const {
2326 // Unreachable? Then so are all paths from here.
2327 if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
2328 // First assume all paths are reachable
2329 const Type** f = TypeTuple::fields(_size);
2330 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2331 // Identify cases that will always throw an exception
2332 // () rethrow call
2333 // () virtual or interface call with NULL receiver
2334 // () call is a check cast with incompatible arguments
2335 if( in(1)->is_Proj() ) {
2336 Node *i10 = in(1)->in(0);
2337 if( i10->is_Call() ) {
2338 CallNode *call = i10->as_Call();
2339 // Rethrows always throw exceptions, never return
2340 if (call->entry_point() == OptoRuntime::rethrow_stub()) {
2341 f[CatchProjNode::fall_through_index] = Type::TOP;
2342 } else if( call->req() > TypeFunc::Parms ) {
2343 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) );
2344 // Check for null receiver to virtual or interface calls
2345 if( call->is_CallDynamicJava() &&
2346 arg0->higher_equal(TypePtr::NULL_PTR) ) {
2347 f[CatchProjNode::fall_through_index] = Type::TOP;
2348 }
2349 } // End of if not a runtime stub
2350 } // End of if have call above me
2351 } // End of slot 1 is not a projection
2352 return TypeTuple::make(_size, f);
2353 }
2354
2355 //=============================================================================
2356 uint CatchProjNode::hash() const {
2357 return Node::hash() + _handler_bci;
2358 }
2359
2360
2361 uint CatchProjNode::cmp( const Node &n ) const {
2362 return ProjNode::cmp(n) &&
2363 _handler_bci == ((CatchProjNode&)n)._handler_bci;
2364 }
2365
2366
2367 //------------------------------Identity---------------------------------------
2368 // If only 1 target is possible, choose it if it is the main control
2369 Node* CatchProjNode::Identity(PhaseGVN* phase) {
2370 // If my value is control and no other value is, then treat as ID
2371 const TypeTuple *t = phase->type(in(0))->is_tuple();
2372 if (t->field_at(_con) != Type::CONTROL) return this;
2373 // If we remove the last CatchProj and elide the Catch/CatchProj, then we
2374 // also remove any exception table entry. Thus we must know the call
2375 // feeding the Catch will not really throw an exception. This is ok for
2376 // the main fall-thru control (happens when we know a call can never throw
2377 // an exception) or for "rethrow", because a further optimization will
2378 // yank the rethrow (happens when we inline a function that can throw an
2379 // exception and the caller has no handler). Not legal, e.g., for passing
2380 // a NULL receiver to a v-call, or passing bad types to a slow-check-cast.
2381 // These cases MUST throw an exception via the runtime system, so the VM
2382 // will be looking for a table entry.
2383 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode
2384 CallNode *call;
2385 if (_con != TypeFunc::Control && // Bail out if not the main control.
2386 !(proj->is_Proj() && // AND NOT a rethrow
2387 proj->in(0)->is_Call() &&
2388 (call = proj->in(0)->as_Call()) &&
2389 call->entry_point() == OptoRuntime::rethrow_stub()))
2390 return this;
2391
2392 // Search for any other path being control
2393 for (uint i = 0; i < t->cnt(); i++) {
2394 if (i != _con && t->field_at(i) == Type::CONTROL)
2395 return this;
2396 }
2397 // Only my path is possible; I am identity on control to the jump
2398 return in(0)->in(0);
2399 }
2400
2401
2402 #ifndef PRODUCT
2403 void CatchProjNode::dump_spec(outputStream *st) const {
2404 ProjNode::dump_spec(st);
2405 st->print("@bci %d ",_handler_bci);
2406 }
2407 #endif
2408
2409 //=============================================================================
2410 //------------------------------Identity---------------------------------------
2411 // Check for CreateEx being Identity.
2412 Node* CreateExNode::Identity(PhaseGVN* phase) {
2413 if( phase->type(in(1)) == Type::TOP ) return in(1);
2414 if( phase->type(in(0)) == Type::TOP ) return in(0);
2415 // We only come from CatchProj, unless the CatchProj goes away.
2416 // If the CatchProj is optimized away, then we just carry the
2417 // exception oop through.
2418
2419 // CheckCastPPNode::Ideal() for value types reuses the exception
2420 // paths of a call to perform an allocation: we can see a Phi here.
2421 if (in(1)->is_Phi()) {
2422 return this;
2423 }
2424 CallNode *call = in(1)->in(0)->as_Call();
2425
2426 return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) )
2427 ? this
2428 : call->in(TypeFunc::Parms);
2429 }
2430
2431 //=============================================================================
2432 //------------------------------Value------------------------------------------
2433 // Check for being unreachable.
2434 const Type* NeverBranchNode::Value(PhaseGVN* phase) const {
2435 if (!in(0) || in(0)->is_top()) return Type::TOP;
2436 return bottom_type();
2437 }
2438
2439 //------------------------------Ideal------------------------------------------
2440 // Check for no longer being part of a loop
2441 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2442 if (can_reshape && !in(0)->is_Loop()) {
2443 // Dead code elimination can sometimes delete this projection so
2444 // if it's not there, there's nothing to do.
2445 Node* fallthru = proj_out_or_null(0);
2446 if (fallthru != NULL) {
2447 phase->is_IterGVN()->replace_node(fallthru, in(0));
2448 }
2449 return phase->C->top();
2450 }
2451 return NULL;
2452 }
2453
2454 #ifndef PRODUCT
2455 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const {
2456 st->print("%s", Name());
2457 }
2458 #endif