1 /*
2 * Copyright (c) 1997, 2017, 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 Node *parent_ctrl;
576 if( cnt == 0 ) {
577 assert( req() == 1, "no inputs expected" );
578 // During IGVN phase such region will be subsumed by TOP node
579 // so region's phis will have TOP as control node.
580 // Kill phis here to avoid it. PhiNode::is_copy() will be always false.
581 // Also set other user's input to top.
582 parent_ctrl = phase->C->top();
583 } else {
584 // The fallthrough case since we already checked dead loops above.
585 parent_ctrl = in(1);
586 assert(parent_ctrl != NULL, "Region is a copy of some non-null control");
587 assert(!igvn->eqv(parent_ctrl, this), "Close dead loop");
588 }
589 if (!add_to_worklist)
590 igvn->add_users_to_worklist(this); // Check for further allowed opts
591 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
592 Node* n = last_out(i);
593 igvn->hash_delete(n); // Remove from worklist before modifying edges
594 if( n->is_Phi() ) { // Collapse all Phis
595 // Eagerly replace phis to avoid copies generation.
596 Node* in;
597 if( cnt == 0 ) {
598 assert( n->req() == 1, "No data inputs expected" );
599 in = parent_ctrl; // replaced by top
600 } else {
601 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
602 in = n->in(1); // replaced by unique input
603 if( n->as_Phi()->is_unsafe_data_reference(in) )
604 in = phase->C->top(); // replaced by top
605 }
606 igvn->replace_node(n, in);
607 }
608 else if( n->is_Region() ) { // Update all incoming edges
609 assert( !igvn->eqv(n, this), "Must be removed from DefUse edges");
610 uint uses_found = 0;
611 for( uint k=1; k < n->req(); k++ ) {
612 if( n->in(k) == this ) {
613 n->set_req(k, parent_ctrl);
614 uses_found++;
615 }
616 }
617 if( uses_found > 1 ) { // (--i) done at the end of the loop.
618 i -= (uses_found - 1);
619 }
620 }
621 else {
622 assert( igvn->eqv(n->in(0), this), "Expect RegionNode to be control parent");
623 n->set_req(0, parent_ctrl);
624 }
625 #ifdef ASSERT
626 for( uint k=0; k < n->req(); k++ ) {
627 assert( !igvn->eqv(n->in(k), this), "All uses of RegionNode should be gone");
628 }
629 #endif
630 }
631 // Remove the RegionNode itself from DefUse info
632 igvn->remove_dead_node(this);
633 return NULL;
634 }
635 return this; // Record progress
636 }
637
638
639 // If a Region flows into a Region, merge into one big happy merge.
640 if (can_reshape) {
641 Node *m = merge_region(this, phase);
642 if (m != NULL) return m;
643 }
644
645 // Check if this region is the root of a clipping idiom on floats
646 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
647 // Check that only one use is a Phi and that it simplifies to two constants +
648 PhiNode* phi = has_unique_phi();
649 if (phi != NULL) { // One Phi user
650 // Check inputs to the Phi
651 ConNode *min;
652 ConNode *max;
653 Node *val;
654 uint min_idx;
655 uint max_idx;
656 uint val_idx;
657 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) {
658 IfNode *top_if;
659 IfNode *bot_if;
660 if( check_if_clipping( this, bot_if, top_if ) ) {
661 // Control pattern checks, now verify compares
662 Node *top_in = NULL; // value being compared against
663 Node *bot_in = NULL;
664 if( check_compare_clipping( true, bot_if, min, bot_in ) &&
665 check_compare_clipping( false, top_if, max, top_in ) ) {
666 if( bot_in == top_in ) {
667 PhaseIterGVN *gvn = phase->is_IterGVN();
668 assert( gvn != NULL, "Only had DefUse info in IterGVN");
669 // Only remaining check is that bot_in == top_in == (Phi's val + mods)
670
671 // Check for the ConvF2INode
672 ConvF2INode *convf2i;
673 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
674 convf2i->in(1) == bot_in ) {
675 // Matched pattern, including LShiftI; RShiftI, replace with integer compares
676 // max test
677 Node *cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, min ));
678 Node *boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::lt ));
679 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt ));
680 Node *if_min= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
681 Node *ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
682 // min test
683 cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, max ));
684 boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::gt ));
685 iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
686 Node *if_max= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
687 ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
688 // update input edges to region node
689 set_req_X( min_idx, if_min, gvn );
690 set_req_X( max_idx, if_max, gvn );
691 set_req_X( val_idx, ifF, gvn );
692 // remove unnecessary 'LShiftI; RShiftI' idiom
693 gvn->hash_delete(phi);
694 phi->set_req_X( val_idx, convf2i, gvn );
695 gvn->hash_find_insert(phi);
696 // Return transformed region node
697 return this;
698 }
699 }
700 }
701 }
702 }
703 }
704 }
705
706 return modified ? this : NULL;
707 }
708
709
710
711 const RegMask &RegionNode::out_RegMask() const {
712 return RegMask::Empty;
713 }
714
715 // Find the one non-null required input. RegionNode only
716 Node *Node::nonnull_req() const {
717 assert( is_Region(), "" );
718 for( uint i = 1; i < _cnt; i++ )
719 if( in(i) )
720 return in(i);
721 ShouldNotReachHere();
722 return NULL;
723 }
724
725
726 //=============================================================================
727 // note that these functions assume that the _adr_type field is flattened
728 uint PhiNode::hash() const {
729 const Type* at = _adr_type;
730 return TypeNode::hash() + (at ? at->hash() : 0);
731 }
732 uint PhiNode::cmp( const Node &n ) const {
733 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
734 }
735 static inline
736 const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
737 if (at == NULL || at == TypePtr::BOTTOM) return at;
738 return Compile::current()->alias_type(at)->adr_type();
739 }
740
741 //----------------------------make---------------------------------------------
742 // create a new phi with edges matching r and set (initially) to x
743 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
744 uint preds = r->req(); // Number of predecessor paths
745 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at");
746 PhiNode* p = new PhiNode(r, t, at);
747 for (uint j = 1; j < preds; j++) {
748 // Fill in all inputs, except those which the region does not yet have
749 if (r->in(j) != NULL)
750 p->init_req(j, x);
751 }
752 return p;
753 }
754 PhiNode* PhiNode::make(Node* r, Node* x) {
755 const Type* t = x->bottom_type();
756 const TypePtr* at = NULL;
757 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
758 return make(r, x, t, at);
759 }
760 PhiNode* PhiNode::make_blank(Node* r, Node* x) {
761 const Type* t = x->bottom_type();
762 const TypePtr* at = NULL;
763 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
764 return new PhiNode(r, t, at);
765 }
766
767
768 //------------------------slice_memory-----------------------------------------
769 // create a new phi with narrowed memory type
770 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
771 PhiNode* mem = (PhiNode*) clone();
772 *(const TypePtr**)&mem->_adr_type = adr_type;
773 // convert self-loops, or else we get a bad graph
774 for (uint i = 1; i < req(); i++) {
775 if ((const Node*)in(i) == this) mem->set_req(i, mem);
776 }
777 mem->verify_adr_type();
778 return mem;
779 }
780
781 //------------------------split_out_instance-----------------------------------
782 // Split out an instance type from a bottom phi.
783 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const {
784 const TypeOopPtr *t_oop = at->isa_oopptr();
785 assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr");
786 const TypePtr *t = adr_type();
787 assert(type() == Type::MEMORY &&
788 (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
789 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
790 t->is_oopptr()->cast_to_exactness(true)
791 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
792 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop),
793 "bottom or raw memory required");
794
795 // Check if an appropriate node already exists.
796 Node *region = in(0);
797 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) {
798 Node* use = region->fast_out(k);
799 if( use->is_Phi()) {
800 PhiNode *phi2 = use->as_Phi();
801 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) {
802 return phi2;
803 }
804 }
805 }
806 Compile *C = igvn->C;
807 Arena *a = Thread::current()->resource_area();
808 Node_Array node_map = new Node_Array(a);
809 Node_Stack stack(a, C->live_nodes() >> 4);
810 PhiNode *nphi = slice_memory(at);
811 igvn->register_new_node_with_optimizer( nphi );
812 node_map.map(_idx, nphi);
813 stack.push((Node *)this, 1);
814 while(!stack.is_empty()) {
815 PhiNode *ophi = stack.node()->as_Phi();
816 uint i = stack.index();
817 assert(i >= 1, "not control edge");
818 stack.pop();
819 nphi = node_map[ophi->_idx]->as_Phi();
820 for (; i < ophi->req(); i++) {
821 Node *in = ophi->in(i);
822 if (in == NULL || igvn->type(in) == Type::TOP)
823 continue;
824 Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, NULL, igvn);
825 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL;
826 if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) {
827 opt = node_map[optphi->_idx];
828 if (opt == NULL) {
829 stack.push(ophi, i);
830 nphi = optphi->slice_memory(at);
831 igvn->register_new_node_with_optimizer( nphi );
832 node_map.map(optphi->_idx, nphi);
833 ophi = optphi;
834 i = 0; // will get incremented at top of loop
835 continue;
836 }
837 }
838 nphi->set_req(i, opt);
839 }
840 }
841 return nphi;
842 }
843
844 //------------------------verify_adr_type--------------------------------------
845 #ifdef ASSERT
846 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
847 if (visited.test_set(_idx)) return; //already visited
848
849 // recheck constructor invariants:
850 verify_adr_type(false);
851
852 // recheck local phi/phi consistency:
853 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
854 "adr_type must be consistent across phi nest");
855
856 // walk around
857 for (uint i = 1; i < req(); i++) {
858 Node* n = in(i);
859 if (n == NULL) continue;
860 const Node* np = in(i);
861 if (np->is_Phi()) {
862 np->as_Phi()->verify_adr_type(visited, at);
863 } else if (n->bottom_type() == Type::TOP
864 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
865 // ignore top inputs
866 } else {
867 const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
868 // recheck phi/non-phi consistency at leaves:
869 assert((nat != NULL) == (at != NULL), "");
870 assert(nat == at || nat == TypePtr::BOTTOM,
871 "adr_type must be consistent at leaves of phi nest");
872 }
873 }
874 }
875
876 // Verify a whole nest of phis rooted at this one.
877 void PhiNode::verify_adr_type(bool recursive) const {
878 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
879 if (Node::in_dump()) return; // muzzle asserts when printing
880
881 assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only");
882
883 if (!VerifyAliases) return; // verify thoroughly only if requested
884
885 assert(_adr_type == flatten_phi_adr_type(_adr_type),
886 "Phi::adr_type must be pre-normalized");
887
888 if (recursive) {
889 VectorSet visited(Thread::current()->resource_area());
890 verify_adr_type(visited, _adr_type);
891 }
892 }
893 #endif
894
895
896 //------------------------------Value------------------------------------------
897 // Compute the type of the PhiNode
898 const Type* PhiNode::Value(PhaseGVN* phase) const {
899 Node *r = in(0); // RegionNode
900 if( !r ) // Copy or dead
901 return in(1) ? phase->type(in(1)) : Type::TOP;
902
903 // Note: During parsing, phis are often transformed before their regions.
904 // This means we have to use type_or_null to defend against untyped regions.
905 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
906 return Type::TOP;
907
908 // Check for trip-counted loop. If so, be smarter.
909 CountedLoopNode* l = r->is_CountedLoop() ? r->as_CountedLoop() : NULL;
910 if (l && ((const Node*)l->phi() == this)) { // Trip counted loop!
911 // protect against init_trip() or limit() returning NULL
912 if (l->can_be_counted_loop(phase)) {
913 const Node *init = l->init_trip();
914 const Node *limit = l->limit();
915 const Node* stride = l->stride();
916 if (init != NULL && limit != NULL && stride != NULL) {
917 const TypeInt* lo = phase->type(init)->isa_int();
918 const TypeInt* hi = phase->type(limit)->isa_int();
919 const TypeInt* stride_t = phase->type(stride)->isa_int();
920 if (lo != NULL && hi != NULL && stride_t != NULL) { // Dying loops might have TOP here
921 assert(stride_t->_hi >= stride_t->_lo, "bad stride type");
922 if (stride_t->_hi < 0) { // Down-counter loop
923 swap(lo, hi);
924 return TypeInt::make(MIN2(lo->_lo, hi->_lo) , hi->_hi, 3);
925 } else if (stride_t->_lo >= 0) {
926 return TypeInt::make(lo->_lo, MAX2(lo->_hi, hi->_hi), 3);
927 }
928 }
929 }
930 } else if (l->in(LoopNode::LoopBackControl) != NULL &&
931 in(LoopNode::EntryControl) != NULL &&
932 phase->type(l->in(LoopNode::LoopBackControl)) == Type::TOP) {
933 // During CCP, if we saturate the type of a counted loop's Phi
934 // before the special code for counted loop above has a chance
935 // to run (that is as long as the type of the backedge's control
936 // is top), we might end up with non monotonic types
937 return phase->type(in(LoopNode::EntryControl));
938 }
939 }
940
941 // Until we have harmony between classes and interfaces in the type
942 // lattice, we must tread carefully around phis which implicitly
943 // convert the one to the other.
944 const TypePtr* ttp = _type->make_ptr();
945 const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL;
946 const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_klassptr() : NULL;
947 bool is_intf = false;
948 if (ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
949 is_intf = true;
950 } else if (ttkp != NULL && ttkp->is_loaded() && ttkp->klass()->is_interface()) {
951 is_intf = true;
952 }
953
954 // Default case: merge all inputs
955 const Type *t = Type::TOP; // Merged type starting value
956 for (uint i = 1; i < req(); ++i) {// For all paths in
957 // Reachable control path?
958 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
959 const Type* ti = phase->type(in(i));
960 // We assume that each input of an interface-valued Phi is a true
961 // subtype of that interface. This might not be true of the meet
962 // of all the input types. The lattice is not distributive in
963 // such cases. Ward off asserts in type.cpp by refusing to do
964 // meets between interfaces and proper classes.
965 const TypePtr* tip = ti->make_ptr();
966 const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL;
967 if (tiip) {
968 bool ti_is_intf = false;
969 ciKlass* k = tiip->klass();
970 if (k->is_loaded() && k->is_interface())
971 ti_is_intf = true;
972 if (is_intf != ti_is_intf)
973 { t = _type; break; }
974 }
975 t = t->meet_speculative(ti);
976 }
977 }
978
979 // The worst-case type (from ciTypeFlow) should be consistent with "t".
980 // That is, we expect that "t->higher_equal(_type)" holds true.
981 // There are various exceptions:
982 // - Inputs which are phis might in fact be widened unnecessarily.
983 // For example, an input might be a widened int while the phi is a short.
984 // - Inputs might be BotPtrs but this phi is dependent on a null check,
985 // and postCCP has removed the cast which encodes the result of the check.
986 // - The type of this phi is an interface, and the inputs are classes.
987 // - Value calls on inputs might produce fuzzy results.
988 // (Occurrences of this case suggest improvements to Value methods.)
989 //
990 // It is not possible to see Type::BOTTOM values as phi inputs,
991 // because the ciTypeFlow pre-pass produces verifier-quality types.
992 const Type* ft = t->filter_speculative(_type); // Worst case type
993
994 #ifdef ASSERT
995 // The following logic has been moved into TypeOopPtr::filter.
996 const Type* jt = t->join_speculative(_type);
997 if (jt->empty()) { // Emptied out???
998
999 // Check for evil case of 't' being a class and '_type' expecting an
1000 // interface. This can happen because the bytecodes do not contain
1001 // enough type info to distinguish a Java-level interface variable
1002 // from a Java-level object variable. If we meet 2 classes which
1003 // both implement interface I, but their meet is at 'j/l/O' which
1004 // doesn't implement I, we have no way to tell if the result should
1005 // be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows
1006 // into a Phi which "knows" it's an Interface type we'll have to
1007 // uplift the type.
1008 if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
1009 assert(ft == _type, ""); // Uplift to interface
1010 } else if (!t->empty() && ttkp != NULL && ttkp->is_loaded() && ttkp->klass()->is_interface()) {
1011 assert(ft == _type, ""); // Uplift to interface
1012 } else {
1013 // We also have to handle 'evil cases' of interface- vs. class-arrays
1014 Type::get_arrays_base_elements(jt, _type, NULL, &ttip);
1015 if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
1016 assert(ft == _type, ""); // Uplift to array of interface
1017 } else {
1018 // Otherwise it's something stupid like non-overlapping int ranges
1019 // found on dying counted loops.
1020 assert(ft == Type::TOP, ""); // Canonical empty value
1021 }
1022 }
1023 }
1024
1025 else {
1026
1027 // If we have an interface-typed Phi and we narrow to a class type, the join
1028 // should report back the class. However, if we have a J/L/Object
1029 // class-typed Phi and an interface flows in, it's possible that the meet &
1030 // join report an interface back out. This isn't possible but happens
1031 // because the type system doesn't interact well with interfaces.
1032 const TypePtr *jtp = jt->make_ptr();
1033 const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL;
1034 const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_klassptr() : NULL;
1035 if( jtip && ttip ) {
1036 if( jtip->is_loaded() && jtip->klass()->is_interface() &&
1037 ttip->is_loaded() && !ttip->klass()->is_interface() ) {
1038 assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) ||
1039 ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), "");
1040 jt = ft;
1041 }
1042 }
1043 if( jtkp && ttkp ) {
1044 if( jtkp->is_loaded() && jtkp->klass()->is_interface() &&
1045 !jtkp->klass_is_exact() && // Keep exact interface klass (6894807)
1046 ttkp->is_loaded() && !ttkp->klass()->is_interface() ) {
1047 assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) ||
1048 ft->isa_narrowklass() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), "");
1049 jt = ft;
1050 }
1051 }
1052 if (jt != ft && jt->base() == ft->base()) {
1053 if (jt->isa_int() &&
1054 jt->is_int()->_lo == ft->is_int()->_lo &&
1055 jt->is_int()->_hi == ft->is_int()->_hi)
1056 jt = ft;
1057 if (jt->isa_long() &&
1058 jt->is_long()->_lo == ft->is_long()->_lo &&
1059 jt->is_long()->_hi == ft->is_long()->_hi)
1060 jt = ft;
1061 }
1062 if (jt != ft) {
1063 tty->print("merge type: "); t->dump(); tty->cr();
1064 tty->print("kill type: "); _type->dump(); tty->cr();
1065 tty->print("join type: "); jt->dump(); tty->cr();
1066 tty->print("filter type: "); ft->dump(); tty->cr();
1067 }
1068 assert(jt == ft, "");
1069 }
1070 #endif //ASSERT
1071
1072 // Deal with conversion problems found in data loops.
1073 ft = phase->saturate(ft, phase->type_or_null(this), _type);
1074
1075 return ft;
1076 }
1077
1078
1079 //------------------------------is_diamond_phi---------------------------------
1080 // Does this Phi represent a simple well-shaped diamond merge? Return the
1081 // index of the true path or 0 otherwise.
1082 // If check_control_only is true, do not inspect the If node at the
1083 // top, and return -1 (not an edge number) on success.
1084 int PhiNode::is_diamond_phi(bool check_control_only) const {
1085 // Check for a 2-path merge
1086 Node *region = in(0);
1087 if( !region ) return 0;
1088 if( region->req() != 3 ) return 0;
1089 if( req() != 3 ) return 0;
1090 // Check that both paths come from the same If
1091 Node *ifp1 = region->in(1);
1092 Node *ifp2 = region->in(2);
1093 if( !ifp1 || !ifp2 ) return 0;
1094 Node *iff = ifp1->in(0);
1095 if( !iff || !iff->is_If() ) return 0;
1096 if( iff != ifp2->in(0) ) return 0;
1097 if (check_control_only) return -1;
1098 // Check for a proper bool/cmp
1099 const Node *b = iff->in(1);
1100 if( !b->is_Bool() ) return 0;
1101 const Node *cmp = b->in(1);
1102 if( !cmp->is_Cmp() ) return 0;
1103
1104 // Check for branching opposite expected
1105 if( ifp2->Opcode() == Op_IfTrue ) {
1106 assert( ifp1->Opcode() == Op_IfFalse, "" );
1107 return 2;
1108 } else {
1109 assert( ifp1->Opcode() == Op_IfTrue, "" );
1110 return 1;
1111 }
1112 }
1113
1114 //----------------------------check_cmove_id-----------------------------------
1115 // Check for CMove'ing a constant after comparing against the constant.
1116 // Happens all the time now, since if we compare equality vs a constant in
1117 // the parser, we "know" the variable is constant on one path and we force
1118 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
1119 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more
1120 // general in that we don't need constants. Since CMove's are only inserted
1121 // in very special circumstances, we do it here on generic Phi's.
1122 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
1123 assert(true_path !=0, "only diamond shape graph expected");
1124
1125 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1126 // phi->region->if_proj->ifnode->bool->cmp
1127 Node* region = in(0);
1128 Node* iff = region->in(1)->in(0);
1129 BoolNode* b = iff->in(1)->as_Bool();
1130 Node* cmp = b->in(1);
1131 Node* tval = in(true_path);
1132 Node* fval = in(3-true_path);
1133 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
1134 if (id == NULL)
1135 return NULL;
1136
1137 // Either value might be a cast that depends on a branch of 'iff'.
1138 // Since the 'id' value will float free of the diamond, either
1139 // decast or return failure.
1140 Node* ctl = id->in(0);
1141 if (ctl != NULL && ctl->in(0) == iff) {
1142 if (id->is_ConstraintCast()) {
1143 return id->in(1);
1144 } else {
1145 // Don't know how to disentangle this value.
1146 return NULL;
1147 }
1148 }
1149
1150 return id;
1151 }
1152
1153 //------------------------------Identity---------------------------------------
1154 // Check for Region being Identity.
1155 Node* PhiNode::Identity(PhaseGVN* phase) {
1156 // Check for no merging going on
1157 // (There used to be special-case code here when this->region->is_Loop.
1158 // It would check for a tributary phi on the backedge that the main phi
1159 // trivially, perhaps with a single cast. The unique_input method
1160 // does all this and more, by reducing such tributaries to 'this'.)
1161 Node* uin = unique_input(phase, false);
1162 if (uin != NULL) {
1163 return uin;
1164 }
1165
1166 int true_path = is_diamond_phi();
1167 if (true_path != 0) {
1168 Node* id = is_cmove_id(phase, true_path);
1169 if (id != NULL) return id;
1170 }
1171
1172 return this; // No identity
1173 }
1174
1175 //-----------------------------unique_input------------------------------------
1176 // Find the unique value, discounting top, self-loops, and casts.
1177 // Return top if there are no inputs, and self if there are multiple.
1178 Node* PhiNode::unique_input(PhaseTransform* phase, bool uncast) {
1179 // 1) One unique direct input,
1180 // or if uncast is true:
1181 // 2) some of the inputs have an intervening ConstraintCast
1182 // 3) an input is a self loop
1183 //
1184 // 1) input or 2) input or 3) input __
1185 // / \ / \ \ / \
1186 // \ / | cast phi cast
1187 // phi \ / / \ /
1188 // phi / --
1189
1190 Node* r = in(0); // RegionNode
1191 if (r == NULL) return in(1); // Already degraded to a Copy
1192 Node* input = NULL; // The unique direct input (maybe uncasted = ConstraintCasts removed)
1193
1194 for (uint i = 1, cnt = req(); i < cnt; ++i) {
1195 Node* rc = r->in(i);
1196 if (rc == NULL || phase->type(rc) == Type::TOP)
1197 continue; // ignore unreachable control path
1198 Node* n = in(i);
1199 if (n == NULL)
1200 continue;
1201 Node* un = n;
1202 if (uncast) {
1203 #ifdef ASSERT
1204 Node* m = un->uncast();
1205 #endif
1206 while (un != NULL && un->req() == 2 && un->is_ConstraintCast()) {
1207 Node* next = un->in(1);
1208 if (phase->type(next)->isa_rawptr() && phase->type(un)->isa_oopptr()) {
1209 // risk exposing raw ptr at safepoint
1210 break;
1211 }
1212 un = next;
1213 }
1214 assert(m == un || un->in(1) == m, "Only expected at CheckCastPP from allocation");
1215 }
1216 if (un == NULL || un == this || phase->type(un) == Type::TOP) {
1217 continue; // ignore if top, or in(i) and "this" are in a data cycle
1218 }
1219 // Check for a unique input (maybe uncasted)
1220 if (input == NULL) {
1221 input = un;
1222 } else if (input != un) {
1223 input = NodeSentinel; // no unique input
1224 }
1225 }
1226 if (input == NULL) {
1227 return phase->C->top(); // no inputs
1228 }
1229
1230 if (input != NodeSentinel) {
1231 return input; // one unique direct input
1232 }
1233
1234 // Nothing.
1235 return NULL;
1236 }
1237
1238 //------------------------------is_x2logic-------------------------------------
1239 // Check for simple convert-to-boolean pattern
1240 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
1241 // Convert Phi to an ConvIB.
1242 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
1243 assert(true_path !=0, "only diamond shape graph expected");
1244 // Convert the true/false index into an expected 0/1 return.
1245 // Map 2->0 and 1->1.
1246 int flipped = 2-true_path;
1247
1248 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1249 // phi->region->if_proj->ifnode->bool->cmp
1250 Node *region = phi->in(0);
1251 Node *iff = region->in(1)->in(0);
1252 BoolNode *b = (BoolNode*)iff->in(1);
1253 const CmpNode *cmp = (CmpNode*)b->in(1);
1254
1255 Node *zero = phi->in(1);
1256 Node *one = phi->in(2);
1257 const Type *tzero = phase->type( zero );
1258 const Type *tone = phase->type( one );
1259
1260 // Check for compare vs 0
1261 const Type *tcmp = phase->type(cmp->in(2));
1262 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
1263 // Allow cmp-vs-1 if the other input is bounded by 0-1
1264 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
1265 return NULL;
1266 flipped = 1-flipped; // Test is vs 1 instead of 0!
1267 }
1268
1269 // Check for setting zero/one opposite expected
1270 if( tzero == TypeInt::ZERO ) {
1271 if( tone == TypeInt::ONE ) {
1272 } else return NULL;
1273 } else if( tzero == TypeInt::ONE ) {
1274 if( tone == TypeInt::ZERO ) {
1275 flipped = 1-flipped;
1276 } else return NULL;
1277 } else return NULL;
1278
1279 // Check for boolean test backwards
1280 if( b->_test._test == BoolTest::ne ) {
1281 } else if( b->_test._test == BoolTest::eq ) {
1282 flipped = 1-flipped;
1283 } else return NULL;
1284
1285 // Build int->bool conversion
1286 Node *n = new Conv2BNode( cmp->in(1) );
1287 if( flipped )
1288 n = new XorINode( phase->transform(n), phase->intcon(1) );
1289
1290 return n;
1291 }
1292
1293 //------------------------------is_cond_add------------------------------------
1294 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;"
1295 // To be profitable the control flow has to disappear; there can be no other
1296 // values merging here. We replace the test-and-branch with:
1297 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by
1298 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
1299 // Then convert Y to 0-or-Y and finally add.
1300 // This is a key transform for SpecJava _201_compress.
1301 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
1302 assert(true_path !=0, "only diamond shape graph expected");
1303
1304 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1305 // phi->region->if_proj->ifnode->bool->cmp
1306 RegionNode *region = (RegionNode*)phi->in(0);
1307 Node *iff = region->in(1)->in(0);
1308 BoolNode* b = iff->in(1)->as_Bool();
1309 const CmpNode *cmp = (CmpNode*)b->in(1);
1310
1311 // Make sure only merging this one phi here
1312 if (region->has_unique_phi() != phi) return NULL;
1313
1314 // Make sure each arm of the diamond has exactly one output, which we assume
1315 // is the region. Otherwise, the control flow won't disappear.
1316 if (region->in(1)->outcnt() != 1) return NULL;
1317 if (region->in(2)->outcnt() != 1) return NULL;
1318
1319 // Check for "(P < Q)" of type signed int
1320 if (b->_test._test != BoolTest::lt) return NULL;
1321 if (cmp->Opcode() != Op_CmpI) return NULL;
1322
1323 Node *p = cmp->in(1);
1324 Node *q = cmp->in(2);
1325 Node *n1 = phi->in( true_path);
1326 Node *n2 = phi->in(3-true_path);
1327
1328 int op = n1->Opcode();
1329 if( op != Op_AddI // Need zero as additive identity
1330 /*&&op != Op_SubI &&
1331 op != Op_AddP &&
1332 op != Op_XorI &&
1333 op != Op_OrI*/ )
1334 return NULL;
1335
1336 Node *x = n2;
1337 Node *y = NULL;
1338 if( x == n1->in(1) ) {
1339 y = n1->in(2);
1340 } else if( x == n1->in(2) ) {
1341 y = n1->in(1);
1342 } else return NULL;
1343
1344 // Not so profitable if compare and add are constants
1345 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
1346 return NULL;
1347
1348 Node *cmplt = phase->transform( new CmpLTMaskNode(p,q) );
1349 Node *j_and = phase->transform( new AndINode(cmplt,y) );
1350 return new AddINode(j_and,x);
1351 }
1352
1353 //------------------------------is_absolute------------------------------------
1354 // Check for absolute value.
1355 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
1356 assert(true_path !=0, "only diamond shape graph expected");
1357
1358 int cmp_zero_idx = 0; // Index of compare input where to look for zero
1359 int phi_x_idx = 0; // Index of phi input where to find naked x
1360
1361 // ABS ends with the merge of 2 control flow paths.
1362 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
1363 int false_path = 3 - true_path;
1364
1365 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1366 // phi->region->if_proj->ifnode->bool->cmp
1367 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
1368
1369 // Check bool sense
1370 switch( bol->_test._test ) {
1371 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break;
1372 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1373 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1374 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
1375 default: return NULL; break;
1376 }
1377
1378 // Test is next
1379 Node *cmp = bol->in(1);
1380 const Type *tzero = NULL;
1381 switch( cmp->Opcode() ) {
1382 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS
1383 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS
1384 default: return NULL;
1385 }
1386
1387 // Find zero input of compare; the other input is being abs'd
1388 Node *x = NULL;
1389 bool flip = false;
1390 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
1391 x = cmp->in(3 - cmp_zero_idx);
1392 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
1393 // The test is inverted, we should invert the result...
1394 x = cmp->in(cmp_zero_idx);
1395 flip = true;
1396 } else {
1397 return NULL;
1398 }
1399
1400 // Next get the 2 pieces being selected, one is the original value
1401 // and the other is the negated value.
1402 if( phi_root->in(phi_x_idx) != x ) return NULL;
1403
1404 // Check other phi input for subtract node
1405 Node *sub = phi_root->in(3 - phi_x_idx);
1406
1407 // Allow only Sub(0,X) and fail out for all others; Neg is not OK
1408 if( tzero == TypeF::ZERO ) {
1409 if( sub->Opcode() != Op_SubF ||
1410 sub->in(2) != x ||
1411 phase->type(sub->in(1)) != tzero ) return NULL;
1412 x = new AbsFNode(x);
1413 if (flip) {
1414 x = new SubFNode(sub->in(1), phase->transform(x));
1415 }
1416 } else {
1417 if( sub->Opcode() != Op_SubD ||
1418 sub->in(2) != x ||
1419 phase->type(sub->in(1)) != tzero ) return NULL;
1420 x = new AbsDNode(x);
1421 if (flip) {
1422 x = new SubDNode(sub->in(1), phase->transform(x));
1423 }
1424 }
1425
1426 return x;
1427 }
1428
1429 //------------------------------split_once-------------------------------------
1430 // Helper for split_flow_path
1431 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
1432 igvn->hash_delete(n); // Remove from hash before hacking edges
1433
1434 uint j = 1;
1435 for (uint i = phi->req()-1; i > 0; i--) {
1436 if (phi->in(i) == val) { // Found a path with val?
1437 // Add to NEW Region/Phi, no DU info
1438 newn->set_req( j++, n->in(i) );
1439 // Remove from OLD Region/Phi
1440 n->del_req(i);
1441 }
1442 }
1443
1444 // Register the new node but do not transform it. Cannot transform until the
1445 // entire Region/Phi conglomerate has been hacked as a single huge transform.
1446 igvn->register_new_node_with_optimizer( newn );
1447
1448 // Now I can point to the new node.
1449 n->add_req(newn);
1450 igvn->_worklist.push(n);
1451 }
1452
1453 //------------------------------split_flow_path--------------------------------
1454 // Check for merging identical values and split flow paths
1455 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) {
1456 BasicType bt = phi->type()->basic_type();
1457 if( bt == T_ILLEGAL || type2size[bt] <= 0 )
1458 return NULL; // Bail out on funny non-value stuff
1459 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a
1460 return NULL; // third unequal input to be worth doing
1461
1462 // Scan for a constant
1463 uint i;
1464 for( i = 1; i < phi->req()-1; i++ ) {
1465 Node *n = phi->in(i);
1466 if( !n ) return NULL;
1467 if( phase->type(n) == Type::TOP ) return NULL;
1468 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN || n->Opcode() == Op_ConNKlass )
1469 break;
1470 }
1471 if( i >= phi->req() ) // Only split for constants
1472 return NULL;
1473
1474 Node *val = phi->in(i); // Constant to split for
1475 uint hit = 0; // Number of times it occurs
1476 Node *r = phi->region();
1477
1478 for( ; i < phi->req(); i++ ){ // Count occurrences of constant
1479 Node *n = phi->in(i);
1480 if( !n ) return NULL;
1481 if( phase->type(n) == Type::TOP ) return NULL;
1482 if( phi->in(i) == val ) {
1483 hit++;
1484 if (PhaseIdealLoop::find_predicate(r->in(i)) != NULL) {
1485 return NULL; // don't split loop entry path
1486 }
1487 }
1488 }
1489
1490 if( hit <= 1 || // Make sure we find 2 or more
1491 hit == phi->req()-1 ) // and not ALL the same value
1492 return NULL;
1493
1494 // Now start splitting out the flow paths that merge the same value.
1495 // Split first the RegionNode.
1496 PhaseIterGVN *igvn = phase->is_IterGVN();
1497 RegionNode *newr = new RegionNode(hit+1);
1498 split_once(igvn, phi, val, r, newr);
1499
1500 // Now split all other Phis than this one
1501 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) {
1502 Node* phi2 = r->fast_out(k);
1503 if( phi2->is_Phi() && phi2->as_Phi() != phi ) {
1504 PhiNode *newphi = PhiNode::make_blank(newr, phi2);
1505 split_once(igvn, phi, val, phi2, newphi);
1506 }
1507 }
1508
1509 // Clean up this guy
1510 igvn->hash_delete(phi);
1511 for( i = phi->req()-1; i > 0; i-- ) {
1512 if( phi->in(i) == val ) {
1513 phi->del_req(i);
1514 }
1515 }
1516 phi->add_req(val);
1517
1518 return phi;
1519 }
1520
1521 //=============================================================================
1522 //------------------------------simple_data_loop_check-------------------------
1523 // Try to determining if the phi node in a simple safe/unsafe data loop.
1524 // Returns:
1525 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
1526 // Safe - safe case when the phi and it's inputs reference only safe data
1527 // nodes;
1528 // Unsafe - the phi and it's inputs reference unsafe data nodes but there
1529 // is no reference back to the phi - need a graph walk
1530 // to determine if it is in a loop;
1531 // UnsafeLoop - unsafe case when the phi references itself directly or through
1532 // unsafe data node.
1533 // Note: a safe data node is a node which could/never reference itself during
1534 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP.
1535 // I mark Phi nodes as safe node not only because they can reference itself
1536 // but also to prevent mistaking the fallthrough case inside an outer loop
1537 // as dead loop when the phi references itselfs through an other phi.
1538 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const {
1539 // It is unsafe loop if the phi node references itself directly.
1540 if (in == (Node*)this)
1541 return UnsafeLoop; // Unsafe loop
1542 // Unsafe loop if the phi node references itself through an unsafe data node.
1543 // Exclude cases with null inputs or data nodes which could reference
1544 // itself (safe for dead loops).
1545 if (in != NULL && !in->is_dead_loop_safe()) {
1546 // Check inputs of phi's inputs also.
1547 // It is much less expensive then full graph walk.
1548 uint cnt = in->req();
1549 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1;
1550 for (; i < cnt; ++i) {
1551 Node* m = in->in(i);
1552 if (m == (Node*)this)
1553 return UnsafeLoop; // Unsafe loop
1554 if (m != NULL && !m->is_dead_loop_safe()) {
1555 // Check the most common case (about 30% of all cases):
1556 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con).
1557 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL;
1558 if (m1 == (Node*)this)
1559 return UnsafeLoop; // Unsafe loop
1560 if (m1 != NULL && m1 == m->in(2) &&
1561 m1->is_dead_loop_safe() && m->in(3)->is_Con()) {
1562 continue; // Safe case
1563 }
1564 // The phi references an unsafe node - need full analysis.
1565 return Unsafe;
1566 }
1567 }
1568 }
1569 return Safe; // Safe case - we can optimize the phi node.
1570 }
1571
1572 //------------------------------is_unsafe_data_reference-----------------------
1573 // If phi can be reached through the data input - it is data loop.
1574 bool PhiNode::is_unsafe_data_reference(Node *in) const {
1575 assert(req() > 1, "");
1576 // First, check simple cases when phi references itself directly or
1577 // through an other node.
1578 LoopSafety safety = simple_data_loop_check(in);
1579 if (safety == UnsafeLoop)
1580 return true; // phi references itself - unsafe loop
1581 else if (safety == Safe)
1582 return false; // Safe case - phi could be replaced with the unique input.
1583
1584 // Unsafe case when we should go through data graph to determine
1585 // if the phi references itself.
1586
1587 ResourceMark rm;
1588
1589 Arena *a = Thread::current()->resource_area();
1590 Node_List nstack(a);
1591 VectorSet visited(a);
1592
1593 nstack.push(in); // Start with unique input.
1594 visited.set(in->_idx);
1595 while (nstack.size() != 0) {
1596 Node* n = nstack.pop();
1597 uint cnt = n->req();
1598 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1;
1599 for (; i < cnt; i++) {
1600 Node* m = n->in(i);
1601 if (m == (Node*)this) {
1602 return true; // Data loop
1603 }
1604 if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases.
1605 if (!visited.test_set(m->_idx))
1606 nstack.push(m);
1607 }
1608 }
1609 }
1610 return false; // The phi is not reachable from its inputs
1611 }
1612
1613
1614 //------------------------------Ideal------------------------------------------
1615 // Return a node which is more "ideal" than the current node. Must preserve
1616 // the CFG, but we can still strip out dead paths.
1617 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1618 // The next should never happen after 6297035 fix.
1619 if( is_copy() ) // Already degraded to a Copy ?
1620 return NULL; // No change
1621
1622 Node *r = in(0); // RegionNode
1623 assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge");
1624
1625 // Note: During parsing, phis are often transformed before their regions.
1626 // This means we have to use type_or_null to defend against untyped regions.
1627 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1628 return NULL; // No change
1629
1630 // If all inputs are value types, push the value type node down through the
1631 // phi because value type nodes should be merged through their input values.
1632 if (req() > 2 && in(1) != NULL && in(1)->is_ValueTypeBase() && (can_reshape || in(1)->is_ValueType())) {
1633 int opcode = in(1)->Opcode();
1634 uint i = 2;
1635 for (; i < req() && in(i) && in(i)->is_ValueTypeBase(); i++) {
1636 assert(in(i)->Opcode() == opcode, "mixing pointers and values?");
1637 }
1638 if (i == req()) {
1639 ValueTypeBaseNode* vt = in(1)->as_ValueTypeBase()->clone_with_phis(phase, in(0));
1640 for (uint i = 2; i < req(); ++i) {
1641 vt->merge_with(phase, in(i)->as_ValueTypeBase(), i, i == (req()-1));
1642 }
1643 return vt;
1644 }
1645 }
1646
1647 if (type()->isa_valuetypeptr() && can_reshape) {
1648 // If the Phi merges the result from a mix of constant and non
1649 // constant method handles, only some of its inputs are
1650 // ValueTypePtr nodes and we can't push the ValueTypePtr node down
1651 // to remove the need for allocations. This if fixed by transforming:
1652 //
1653 // (Phi ValueTypePtr#1 Node#2) to (Phi ValueTypePtr#1 CheckCastPP#2)
1654 //
1655 // Then pushing the CheckCastPP up through Phis until it reaches
1656 // the non constant method handle call. The type of the return
1657 // value is then known from the type of the CheckCastPP. A
1658 // ValueTypePtr can be created by adding projections to the call
1659 // for all values being returned. See
1660 // CheckCastPPNode::Ideal(). That ValueTypePtr node can then be
1661 // pushed down through Phis.
1662 const TypeValueTypePtr* vtptr = NULL;
1663 for (uint i = 1; i < req(); i++) {
1664 if (in(i) != NULL && in(i)->is_ValueTypePtr()) {
1665 const TypeValueTypePtr* t = phase->type(in(i))->is_valuetypeptr();
1666 t = t->cast_to_ptr_type(TypePtr::BotPTR)->is_valuetypeptr();
1667 if (vtptr == NULL) {
1668 vtptr = t;
1669 } else {
1670 assert(vtptr == t, "Phi should merge identical value types");
1671 }
1672 } else {
1673 assert(in(i) == NULL || vtptr == NULL || phase->type(in(i))->higher_equal(vtptr) || phase->type(in(i)) == Type::TOP ||
1674 phase->type(in(i))->is_valuetypeptr()->is__Value(), "bad type");
1675 }
1676 }
1677 if (vtptr != NULL) {
1678 // One input is a value type. All inputs must have the same type.
1679 bool progress = false;
1680 PhaseIterGVN* igvn = phase->is_IterGVN();
1681 for (uint i = 1; i < req(); i++) {
1682 if (in(i) != NULL && !in(i)->is_Con() && !phase->type(in(i))->higher_equal(vtptr)) {
1683 // Can't transform because CheckCastPPNode::Identity can
1684 // push the cast up through another Phi and cause this same
1685 // transformation to run again, indefinitely
1686 Node* cast = igvn->register_new_node_with_optimizer(new CheckCastPPNode(NULL, in(i), vtptr));
1687 set_req(i, cast);
1688 progress = true;
1689 }
1690 }
1691 if (progress) {
1692 return this;
1693 }
1694 }
1695 }
1696
1697 Node *top = phase->C->top();
1698 bool new_phi = (outcnt() == 0); // transforming new Phi
1699 // No change for igvn if new phi is not hooked
1700 if (new_phi && can_reshape)
1701 return NULL;
1702
1703 // The are 2 situations when only one valid phi's input is left
1704 // (in addition to Region input).
1705 // One: region is not loop - replace phi with this input.
1706 // Two: region is loop - replace phi with top since this data path is dead
1707 // and we need to break the dead data loop.
1708 Node* progress = NULL; // Record if any progress made
1709 for( uint j = 1; j < req(); ++j ){ // For all paths in
1710 // Check unreachable control paths
1711 Node* rc = r->in(j);
1712 Node* n = in(j); // Get the input
1713 if (rc == NULL || phase->type(rc) == Type::TOP) {
1714 if (n != top) { // Not already top?
1715 PhaseIterGVN *igvn = phase->is_IterGVN();
1716 if (can_reshape && igvn != NULL) {
1717 igvn->_worklist.push(r);
1718 }
1719 set_req(j, top); // Nuke it down
1720 progress = this; // Record progress
1721 }
1722 }
1723 }
1724
1725 if (can_reshape && outcnt() == 0) {
1726 // set_req() above may kill outputs if Phi is referenced
1727 // only by itself on the dead (top) control path.
1728 return top;
1729 }
1730
1731 bool uncasted = false;
1732 Node* uin = unique_input(phase, false);
1733 if (uin == NULL && can_reshape) {
1734 uncasted = true;
1735 uin = unique_input(phase, true);
1736 }
1737 if (uin == top) { // Simplest case: no alive inputs.
1738 if (can_reshape) // IGVN transformation
1739 return top;
1740 else
1741 return NULL; // Identity will return TOP
1742 } else if (uin != NULL) {
1743 // Only one not-NULL unique input path is left.
1744 // Determine if this input is backedge of a loop.
1745 // (Skip new phis which have no uses and dead regions).
1746 if (outcnt() > 0 && r->in(0) != NULL) {
1747 // First, take the short cut when we know it is a loop and
1748 // the EntryControl data path is dead.
1749 // Loop node may have only one input because entry path
1750 // is removed in PhaseIdealLoop::Dominators().
1751 assert(!r->is_Loop() || r->req() <= 3, "Loop node should have 3 or less inputs");
1752 bool is_loop = (r->is_Loop() && r->req() == 3);
1753 // Then, check if there is a data loop when phi references itself directly
1754 // or through other data nodes.
1755 if ((is_loop && !uin->eqv_uncast(in(LoopNode::EntryControl))) ||
1756 (!is_loop && is_unsafe_data_reference(uin))) {
1757 // Break this data loop to avoid creation of a dead loop.
1758 if (can_reshape) {
1759 return top;
1760 } else {
1761 // We can't return top if we are in Parse phase - cut inputs only
1762 // let Identity to handle the case.
1763 replace_edge(uin, top);
1764 return NULL;
1765 }
1766 }
1767 }
1768
1769 if (uncasted) {
1770 // Add cast nodes between the phi to be removed and its unique input.
1771 // Wait until after parsing for the type information to propagate from the casts.
1772 assert(can_reshape, "Invalid during parsing");
1773 const Type* phi_type = bottom_type();
1774 assert(phi_type->isa_int() || phi_type->isa_ptr(), "bad phi type");
1775 // Add casts to carry the control dependency of the Phi that is
1776 // going away
1777 Node* cast = NULL;
1778 if (phi_type->isa_int()) {
1779 cast = ConstraintCastNode::make_cast(Op_CastII, r, uin, phi_type, true);
1780 } else {
1781 const Type* uin_type = phase->type(uin);
1782 if (!phi_type->isa_oopptr() && !uin_type->isa_oopptr()) {
1783 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true);
1784 } else {
1785 // Use a CastPP for a cast to not null and a CheckCastPP for
1786 // a cast to a new klass (and both if both null-ness and
1787 // klass change).
1788
1789 // If the type of phi is not null but the type of uin may be
1790 // null, uin's type must be casted to not null
1791 if (phi_type->join(TypePtr::NOTNULL) == phi_type->remove_speculative() &&
1792 uin_type->join(TypePtr::NOTNULL) != uin_type->remove_speculative()) {
1793 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, TypePtr::NOTNULL, true);
1794 }
1795
1796 // If the type of phi and uin, both casted to not null,
1797 // differ the klass of uin must be (check)cast'ed to match
1798 // that of phi
1799 if (phi_type->join_speculative(TypePtr::NOTNULL) != uin_type->join_speculative(TypePtr::NOTNULL)) {
1800 Node* n = uin;
1801 if (cast != NULL) {
1802 cast = phase->transform(cast);
1803 n = cast;
1804 }
1805 cast = ConstraintCastNode::make_cast(Op_CheckCastPP, r, n, phi_type, true);
1806 }
1807 if (cast == NULL) {
1808 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true);
1809 }
1810 }
1811 }
1812 assert(cast != NULL, "cast should be set");
1813 cast = phase->transform(cast);
1814 // set all inputs to the new cast(s) so the Phi is removed by Identity
1815 PhaseIterGVN* igvn = phase->is_IterGVN();
1816 for (uint i = 1; i < req(); i++) {
1817 set_req_X(i, cast, igvn);
1818 }
1819 uin = cast;
1820 }
1821
1822 // One unique input.
1823 debug_only(Node* ident = Identity(phase));
1824 // The unique input must eventually be detected by the Identity call.
1825 #ifdef ASSERT
1826 if (ident != uin && !ident->is_top()) {
1827 // print this output before failing assert
1828 r->dump(3);
1829 this->dump(3);
1830 ident->dump();
1831 uin->dump();
1832 }
1833 #endif
1834 assert(ident == uin || ident->is_top(), "Identity must clean this up");
1835 return NULL;
1836 }
1837
1838 Node* opt = NULL;
1839 int true_path = is_diamond_phi();
1840 if( true_path != 0 ) {
1841 // Check for CMove'ing identity. If it would be unsafe,
1842 // handle it here. In the safe case, let Identity handle it.
1843 Node* unsafe_id = is_cmove_id(phase, true_path);
1844 if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) )
1845 opt = unsafe_id;
1846
1847 // Check for simple convert-to-boolean pattern
1848 if( opt == NULL )
1849 opt = is_x2logic(phase, this, true_path);
1850
1851 // Check for absolute value
1852 if( opt == NULL )
1853 opt = is_absolute(phase, this, true_path);
1854
1855 // Check for conditional add
1856 if( opt == NULL && can_reshape )
1857 opt = is_cond_add(phase, this, true_path);
1858
1859 // These 4 optimizations could subsume the phi:
1860 // have to check for a dead data loop creation.
1861 if( opt != NULL ) {
1862 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) {
1863 // Found dead loop.
1864 if( can_reshape )
1865 return top;
1866 // We can't return top if we are in Parse phase - cut inputs only
1867 // to stop further optimizations for this phi. Identity will return TOP.
1868 assert(req() == 3, "only diamond merge phi here");
1869 set_req(1, top);
1870 set_req(2, top);
1871 return NULL;
1872 } else {
1873 return opt;
1874 }
1875 }
1876 }
1877
1878 // Check for merging identical values and split flow paths
1879 if (can_reshape) {
1880 opt = split_flow_path(phase, this);
1881 // This optimization only modifies phi - don't need to check for dead loop.
1882 assert(opt == NULL || phase->eqv(opt, this), "do not elide phi");
1883 if (opt != NULL) return opt;
1884 }
1885
1886 if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) {
1887 // Try to undo Phi of AddP:
1888 // (Phi (AddP base base y) (AddP base2 base2 y))
1889 // becomes:
1890 // newbase := (Phi base base2)
1891 // (AddP newbase newbase y)
1892 //
1893 // This occurs as a result of unsuccessful split_thru_phi and
1894 // interferes with taking advantage of addressing modes. See the
1895 // clone_shift_expressions code in matcher.cpp
1896 Node* addp = in(1);
1897 const Type* type = addp->in(AddPNode::Base)->bottom_type();
1898 Node* y = addp->in(AddPNode::Offset);
1899 if (y != NULL && addp->in(AddPNode::Base) == addp->in(AddPNode::Address)) {
1900 // make sure that all the inputs are similar to the first one,
1901 // i.e. AddP with base == address and same offset as first AddP
1902 bool doit = true;
1903 for (uint i = 2; i < req(); i++) {
1904 if (in(i) == NULL ||
1905 in(i)->Opcode() != Op_AddP ||
1906 in(i)->in(AddPNode::Base) != in(i)->in(AddPNode::Address) ||
1907 in(i)->in(AddPNode::Offset) != y) {
1908 doit = false;
1909 break;
1910 }
1911 // Accumulate type for resulting Phi
1912 type = type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type());
1913 }
1914 Node* base = NULL;
1915 if (doit) {
1916 // Check for neighboring AddP nodes in a tree.
1917 // If they have a base, use that it.
1918 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) {
1919 Node* u = this->fast_out(k);
1920 if (u->is_AddP()) {
1921 Node* base2 = u->in(AddPNode::Base);
1922 if (base2 != NULL && !base2->is_top()) {
1923 if (base == NULL)
1924 base = base2;
1925 else if (base != base2)
1926 { doit = false; break; }
1927 }
1928 }
1929 }
1930 }
1931 if (doit) {
1932 if (base == NULL) {
1933 base = new PhiNode(in(0), type, NULL);
1934 for (uint i = 1; i < req(); i++) {
1935 base->init_req(i, in(i)->in(AddPNode::Base));
1936 }
1937 phase->is_IterGVN()->register_new_node_with_optimizer(base);
1938 }
1939 return new AddPNode(base, base, y);
1940 }
1941 }
1942 }
1943
1944 // Split phis through memory merges, so that the memory merges will go away.
1945 // Piggy-back this transformation on the search for a unique input....
1946 // It will be as if the merged memory is the unique value of the phi.
1947 // (Do not attempt this optimization unless parsing is complete.
1948 // It would make the parser's memory-merge logic sick.)
1949 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.)
1950 if (progress == NULL && can_reshape && type() == Type::MEMORY) {
1951 // see if this phi should be sliced
1952 uint merge_width = 0;
1953 bool saw_self = false;
1954 for( uint i=1; i<req(); ++i ) {// For all paths in
1955 Node *ii = in(i);
1956 // TOP inputs should not be counted as safe inputs because if the
1957 // Phi references itself through all other inputs then splitting the
1958 // Phi through memory merges would create dead loop at later stage.
1959 if (ii == top) {
1960 return NULL; // Delay optimization until graph is cleaned.
1961 }
1962 if (ii->is_MergeMem()) {
1963 MergeMemNode* n = ii->as_MergeMem();
1964 merge_width = MAX2(merge_width, n->req());
1965 saw_self = saw_self || phase->eqv(n->base_memory(), this);
1966 }
1967 }
1968
1969 // This restriction is temporarily necessary to ensure termination:
1970 if (!saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0;
1971
1972 if (merge_width > Compile::AliasIdxRaw) {
1973 // found at least one non-empty MergeMem
1974 const TypePtr* at = adr_type();
1975 if (at != TypePtr::BOTTOM) {
1976 // Patch the existing phi to select an input from the merge:
1977 // Phi:AT1(...MergeMem(m0, m1, m2)...) into
1978 // Phi:AT1(...m1...)
1979 int alias_idx = phase->C->get_alias_index(at);
1980 for (uint i=1; i<req(); ++i) {
1981 Node *ii = in(i);
1982 if (ii->is_MergeMem()) {
1983 MergeMemNode* n = ii->as_MergeMem();
1984 // compress paths and change unreachable cycles to TOP
1985 // If not, we can update the input infinitely along a MergeMem cycle
1986 // Equivalent code is in MemNode::Ideal_common
1987 Node *m = phase->transform(n);
1988 if (outcnt() == 0) { // Above transform() may kill us!
1989 return top;
1990 }
1991 // If transformed to a MergeMem, get the desired slice
1992 // Otherwise the returned node represents memory for every slice
1993 Node *new_mem = (m->is_MergeMem()) ?
1994 m->as_MergeMem()->memory_at(alias_idx) : m;
1995 // Update input if it is progress over what we have now
1996 if (new_mem != ii) {
1997 set_req(i, new_mem);
1998 progress = this;
1999 }
2000 }
2001 }
2002 } else {
2003 // We know that at least one MergeMem->base_memory() == this
2004 // (saw_self == true). If all other inputs also references this phi
2005 // (directly or through data nodes) - it is dead loop.
2006 bool saw_safe_input = false;
2007 for (uint j = 1; j < req(); ++j) {
2008 Node *n = in(j);
2009 if (n->is_MergeMem() && n->as_MergeMem()->base_memory() == this)
2010 continue; // skip known cases
2011 if (!is_unsafe_data_reference(n)) {
2012 saw_safe_input = true; // found safe input
2013 break;
2014 }
2015 }
2016 if (!saw_safe_input)
2017 return top; // all inputs reference back to this phi - dead loop
2018
2019 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into
2020 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...))
2021 PhaseIterGVN *igvn = phase->is_IterGVN();
2022 Node* hook = new Node(1);
2023 PhiNode* new_base = (PhiNode*) clone();
2024 // Must eagerly register phis, since they participate in loops.
2025 if (igvn) {
2026 igvn->register_new_node_with_optimizer(new_base);
2027 hook->add_req(new_base);
2028 }
2029 MergeMemNode* result = MergeMemNode::make(new_base);
2030 for (uint i = 1; i < req(); ++i) {
2031 Node *ii = in(i);
2032 if (ii->is_MergeMem()) {
2033 MergeMemNode* n = ii->as_MergeMem();
2034 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) {
2035 // If we have not seen this slice yet, make a phi for it.
2036 bool made_new_phi = false;
2037 if (mms.is_empty()) {
2038 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C));
2039 made_new_phi = true;
2040 if (igvn) {
2041 igvn->register_new_node_with_optimizer(new_phi);
2042 hook->add_req(new_phi);
2043 }
2044 mms.set_memory(new_phi);
2045 }
2046 Node* phi = mms.memory();
2047 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice");
2048 phi->set_req(i, mms.memory2());
2049 }
2050 }
2051 }
2052 // Distribute all self-loops.
2053 { // (Extra braces to hide mms.)
2054 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2055 Node* phi = mms.memory();
2056 for (uint i = 1; i < req(); ++i) {
2057 if (phi->in(i) == this) phi->set_req(i, phi);
2058 }
2059 }
2060 }
2061 // now transform the new nodes, and return the mergemem
2062 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2063 Node* phi = mms.memory();
2064 mms.set_memory(phase->transform(phi));
2065 }
2066 if (igvn) { // Unhook.
2067 igvn->hash_delete(hook);
2068 for (uint i = 1; i < hook->req(); i++) {
2069 hook->set_req(i, NULL);
2070 }
2071 }
2072 // Replace self with the result.
2073 return result;
2074 }
2075 }
2076 //
2077 // Other optimizations on the memory chain
2078 //
2079 const TypePtr* at = adr_type();
2080 for( uint i=1; i<req(); ++i ) {// For all paths in
2081 Node *ii = in(i);
2082 Node *new_in = MemNode::optimize_memory_chain(ii, at, NULL, phase);
2083 if (ii != new_in ) {
2084 set_req(i, new_in);
2085 progress = this;
2086 }
2087 }
2088 }
2089
2090 #ifdef _LP64
2091 // Push DecodeN/DecodeNKlass down through phi.
2092 // The rest of phi graph will transform by split EncodeP node though phis up.
2093 if ((UseCompressedOops || UseCompressedClassPointers) && can_reshape && progress == NULL) {
2094 bool may_push = true;
2095 bool has_decodeN = false;
2096 bool is_decodeN = false;
2097 for (uint i=1; i<req(); ++i) {// For all paths in
2098 Node *ii = in(i);
2099 if (ii->is_DecodeNarrowPtr() && ii->bottom_type() == bottom_type()) {
2100 // Do optimization if a non dead path exist.
2101 if (ii->in(1)->bottom_type() != Type::TOP) {
2102 has_decodeN = true;
2103 is_decodeN = ii->is_DecodeN();
2104 }
2105 } else if (!ii->is_Phi()) {
2106 may_push = false;
2107 }
2108 }
2109
2110 if (has_decodeN && may_push) {
2111 PhaseIterGVN *igvn = phase->is_IterGVN();
2112 // Make narrow type for new phi.
2113 const Type* narrow_t;
2114 if (is_decodeN) {
2115 narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr());
2116 } else {
2117 narrow_t = TypeNarrowKlass::make(this->bottom_type()->is_ptr());
2118 }
2119 PhiNode* new_phi = new PhiNode(r, narrow_t);
2120 uint orig_cnt = req();
2121 for (uint i=1; i<req(); ++i) {// For all paths in
2122 Node *ii = in(i);
2123 Node* new_ii = NULL;
2124 if (ii->is_DecodeNarrowPtr()) {
2125 assert(ii->bottom_type() == bottom_type(), "sanity");
2126 new_ii = ii->in(1);
2127 } else {
2128 assert(ii->is_Phi(), "sanity");
2129 if (ii->as_Phi() == this) {
2130 new_ii = new_phi;
2131 } else {
2132 if (is_decodeN) {
2133 new_ii = new EncodePNode(ii, narrow_t);
2134 } else {
2135 new_ii = new EncodePKlassNode(ii, narrow_t);
2136 }
2137 igvn->register_new_node_with_optimizer(new_ii);
2138 }
2139 }
2140 new_phi->set_req(i, new_ii);
2141 }
2142 igvn->register_new_node_with_optimizer(new_phi, this);
2143 if (is_decodeN) {
2144 progress = new DecodeNNode(new_phi, bottom_type());
2145 } else {
2146 progress = new DecodeNKlassNode(new_phi, bottom_type());
2147 }
2148 }
2149 }
2150 #endif
2151
2152 return progress; // Return any progress
2153 }
2154
2155 //------------------------------is_tripcount-----------------------------------
2156 bool PhiNode::is_tripcount() const {
2157 return (in(0) != NULL && in(0)->is_CountedLoop() &&
2158 in(0)->as_CountedLoop()->phi() == this);
2159 }
2160
2161 //------------------------------out_RegMask------------------------------------
2162 const RegMask &PhiNode::in_RegMask(uint i) const {
2163 return i ? out_RegMask() : RegMask::Empty;
2164 }
2165
2166 const RegMask &PhiNode::out_RegMask() const {
2167 uint ideal_reg = _type->ideal_reg();
2168 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
2169 if( ideal_reg == 0 ) return RegMask::Empty;
2170 assert(ideal_reg != Op_RegFlags, "flags register is not spillable");
2171 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
2172 }
2173
2174 #ifndef PRODUCT
2175 void PhiNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2176 // For a PhiNode, the set of related nodes includes all inputs till level 2,
2177 // and all outputs till level 1. In compact mode, inputs till level 1 are
2178 // collected.
2179 this->collect_nodes(in_rel, compact ? 1 : 2, false, false);
2180 this->collect_nodes(out_rel, -1, false, false);
2181 }
2182
2183 void PhiNode::dump_spec(outputStream *st) const {
2184 TypeNode::dump_spec(st);
2185 if (is_tripcount()) {
2186 st->print(" #tripcount");
2187 }
2188 }
2189 #endif
2190
2191
2192 //=============================================================================
2193 const Type* GotoNode::Value(PhaseGVN* phase) const {
2194 // If the input is reachable, then we are executed.
2195 // If the input is not reachable, then we are not executed.
2196 return phase->type(in(0));
2197 }
2198
2199 Node* GotoNode::Identity(PhaseGVN* phase) {
2200 return in(0); // Simple copy of incoming control
2201 }
2202
2203 const RegMask &GotoNode::out_RegMask() const {
2204 return RegMask::Empty;
2205 }
2206
2207 #ifndef PRODUCT
2208 //-----------------------------related-----------------------------------------
2209 // The related nodes of a GotoNode are all inputs at level 1, as well as the
2210 // outputs at level 1. This is regardless of compact mode.
2211 void GotoNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2212 this->collect_nodes(in_rel, 1, false, false);
2213 this->collect_nodes(out_rel, -1, false, false);
2214 }
2215 #endif
2216
2217
2218 //=============================================================================
2219 const RegMask &JumpNode::out_RegMask() const {
2220 return RegMask::Empty;
2221 }
2222
2223 #ifndef PRODUCT
2224 //-----------------------------related-----------------------------------------
2225 // The related nodes of a JumpNode are all inputs at level 1, as well as the
2226 // outputs at level 2 (to include actual jump targets beyond projection nodes).
2227 // This is regardless of compact mode.
2228 void JumpNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2229 this->collect_nodes(in_rel, 1, false, false);
2230 this->collect_nodes(out_rel, -2, false, false);
2231 }
2232 #endif
2233
2234 //=============================================================================
2235 const RegMask &JProjNode::out_RegMask() const {
2236 return RegMask::Empty;
2237 }
2238
2239 //=============================================================================
2240 const RegMask &CProjNode::out_RegMask() const {
2241 return RegMask::Empty;
2242 }
2243
2244
2245
2246 //=============================================================================
2247
2248 uint PCTableNode::hash() const { return Node::hash() + _size; }
2249 uint PCTableNode::cmp( const Node &n ) const
2250 { return _size == ((PCTableNode&)n)._size; }
2251
2252 const Type *PCTableNode::bottom_type() const {
2253 const Type** f = TypeTuple::fields(_size);
2254 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2255 return TypeTuple::make(_size, f);
2256 }
2257
2258 //------------------------------Value------------------------------------------
2259 // Compute the type of the PCTableNode. If reachable it is a tuple of
2260 // Control, otherwise the table targets are not reachable
2261 const Type* PCTableNode::Value(PhaseGVN* phase) const {
2262 if( phase->type(in(0)) == Type::CONTROL )
2263 return bottom_type();
2264 return Type::TOP; // All paths dead? Then so are we
2265 }
2266
2267 //------------------------------Ideal------------------------------------------
2268 // Return a node which is more "ideal" than the current node. Strip out
2269 // control copies
2270 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2271 return remove_dead_region(phase, can_reshape) ? this : NULL;
2272 }
2273
2274 //=============================================================================
2275 uint JumpProjNode::hash() const {
2276 return Node::hash() + _dest_bci;
2277 }
2278
2279 uint JumpProjNode::cmp( const Node &n ) const {
2280 return ProjNode::cmp(n) &&
2281 _dest_bci == ((JumpProjNode&)n)._dest_bci;
2282 }
2283
2284 #ifndef PRODUCT
2285 void JumpProjNode::dump_spec(outputStream *st) const {
2286 ProjNode::dump_spec(st);
2287 st->print("@bci %d ",_dest_bci);
2288 }
2289
2290 void JumpProjNode::dump_compact_spec(outputStream *st) const {
2291 ProjNode::dump_compact_spec(st);
2292 st->print("(%d)%d@%d", _switch_val, _proj_no, _dest_bci);
2293 }
2294
2295 void JumpProjNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2296 // The related nodes of a JumpProjNode are its inputs and outputs at level 1.
2297 this->collect_nodes(in_rel, 1, false, false);
2298 this->collect_nodes(out_rel, -1, false, false);
2299 }
2300 #endif
2301
2302 //=============================================================================
2303 //------------------------------Value------------------------------------------
2304 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot
2305 // have the default "fall_through_index" path.
2306 const Type* CatchNode::Value(PhaseGVN* phase) const {
2307 // Unreachable? Then so are all paths from here.
2308 if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
2309 // First assume all paths are reachable
2310 const Type** f = TypeTuple::fields(_size);
2311 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2312 // Identify cases that will always throw an exception
2313 // () rethrow call
2314 // () virtual or interface call with NULL receiver
2315 // () call is a check cast with incompatible arguments
2316 if( in(1)->is_Proj() ) {
2317 Node *i10 = in(1)->in(0);
2318 if( i10->is_Call() ) {
2319 CallNode *call = i10->as_Call();
2320 // Rethrows always throw exceptions, never return
2321 if (call->entry_point() == OptoRuntime::rethrow_stub()) {
2322 f[CatchProjNode::fall_through_index] = Type::TOP;
2323 } else if( call->req() > TypeFunc::Parms ) {
2324 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) );
2325 // Check for null receiver to virtual or interface calls
2326 if( call->is_CallDynamicJava() &&
2327 arg0->higher_equal(TypePtr::NULL_PTR) ) {
2328 f[CatchProjNode::fall_through_index] = Type::TOP;
2329 }
2330 } // End of if not a runtime stub
2331 } // End of if have call above me
2332 } // End of slot 1 is not a projection
2333 return TypeTuple::make(_size, f);
2334 }
2335
2336 //=============================================================================
2337 uint CatchProjNode::hash() const {
2338 return Node::hash() + _handler_bci;
2339 }
2340
2341
2342 uint CatchProjNode::cmp( const Node &n ) const {
2343 return ProjNode::cmp(n) &&
2344 _handler_bci == ((CatchProjNode&)n)._handler_bci;
2345 }
2346
2347
2348 //------------------------------Identity---------------------------------------
2349 // If only 1 target is possible, choose it if it is the main control
2350 Node* CatchProjNode::Identity(PhaseGVN* phase) {
2351 // If my value is control and no other value is, then treat as ID
2352 const TypeTuple *t = phase->type(in(0))->is_tuple();
2353 if (t->field_at(_con) != Type::CONTROL) return this;
2354 // If we remove the last CatchProj and elide the Catch/CatchProj, then we
2355 // also remove any exception table entry. Thus we must know the call
2356 // feeding the Catch will not really throw an exception. This is ok for
2357 // the main fall-thru control (happens when we know a call can never throw
2358 // an exception) or for "rethrow", because a further optimization will
2359 // yank the rethrow (happens when we inline a function that can throw an
2360 // exception and the caller has no handler). Not legal, e.g., for passing
2361 // a NULL receiver to a v-call, or passing bad types to a slow-check-cast.
2362 // These cases MUST throw an exception via the runtime system, so the VM
2363 // will be looking for a table entry.
2364 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode
2365 CallNode *call;
2366 if (_con != TypeFunc::Control && // Bail out if not the main control.
2367 !(proj->is_Proj() && // AND NOT a rethrow
2368 proj->in(0)->is_Call() &&
2369 (call = proj->in(0)->as_Call()) &&
2370 call->entry_point() == OptoRuntime::rethrow_stub()))
2371 return this;
2372
2373 // Search for any other path being control
2374 for (uint i = 0; i < t->cnt(); i++) {
2375 if (i != _con && t->field_at(i) == Type::CONTROL)
2376 return this;
2377 }
2378 // Only my path is possible; I am identity on control to the jump
2379 return in(0)->in(0);
2380 }
2381
2382
2383 #ifndef PRODUCT
2384 void CatchProjNode::dump_spec(outputStream *st) const {
2385 ProjNode::dump_spec(st);
2386 st->print("@bci %d ",_handler_bci);
2387 }
2388 #endif
2389
2390 //=============================================================================
2391 //------------------------------Identity---------------------------------------
2392 // Check for CreateEx being Identity.
2393 Node* CreateExNode::Identity(PhaseGVN* phase) {
2394 if( phase->type(in(1)) == Type::TOP ) return in(1);
2395 if( phase->type(in(0)) == Type::TOP ) return in(0);
2396 // We only come from CatchProj, unless the CatchProj goes away.
2397 // If the CatchProj is optimized away, then we just carry the
2398 // exception oop through.
2399
2400 // CheckCastPPNode::Ideal() for value types reuses the exception
2401 // paths of a call to perform an allocation: we can see a Phi here.
2402 if (in(1)->is_Phi()) {
2403 return this;
2404 }
2405 CallNode *call = in(1)->in(0)->as_Call();
2406
2407 return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) )
2408 ? this
2409 : call->in(TypeFunc::Parms);
2410 }
2411
2412 //=============================================================================
2413 //------------------------------Value------------------------------------------
2414 // Check for being unreachable.
2415 const Type* NeverBranchNode::Value(PhaseGVN* phase) const {
2416 if (!in(0) || in(0)->is_top()) return Type::TOP;
2417 return bottom_type();
2418 }
2419
2420 //------------------------------Ideal------------------------------------------
2421 // Check for no longer being part of a loop
2422 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2423 if (can_reshape && !in(0)->is_Loop()) {
2424 // Dead code elimination can sometimes delete this projection so
2425 // if it's not there, there's nothing to do.
2426 Node* fallthru = proj_out(0);
2427 if (fallthru != NULL) {
2428 phase->is_IterGVN()->replace_node(fallthru, in(0));
2429 }
2430 return phase->C->top();
2431 }
2432 return NULL;
2433 }
2434
2435 #ifndef PRODUCT
2436 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const {
2437 st->print("%s", Name());
2438 }
2439 #endif