1 /*
2 * Copyright (c) 1997, 2020, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "gc/shared/barrierSet.hpp"
28 #include "gc/shared/c2/barrierSetC2.hpp"
29 #include "memory/allocation.inline.hpp"
30 #include "memory/resourceArea.hpp"
31 #include "oops/objArrayKlass.hpp"
32 #include "opto/addnode.hpp"
33 #include "opto/castnode.hpp"
34 #include "opto/cfgnode.hpp"
35 #include "opto/connode.hpp"
36 #include "opto/convertnode.hpp"
37 #include "opto/loopnode.hpp"
38 #include "opto/machnode.hpp"
39 #include "opto/movenode.hpp"
40 #include "opto/narrowptrnode.hpp"
41 #include "opto/mulnode.hpp"
42 #include "opto/phaseX.hpp"
43 #include "opto/regmask.hpp"
44 #include "opto/runtime.hpp"
45 #include "opto/subnode.hpp"
46 #include "opto/vectornode.hpp"
47 #include "utilities/vmError.hpp"
48
49 // Portions of code courtesy of Clifford Click
50
51 // Optimization - Graph Style
52
53 //=============================================================================
54 //------------------------------Value------------------------------------------
55 // Compute the type of the RegionNode.
56 const Type* RegionNode::Value(PhaseGVN* phase) const {
57 for( uint i=1; i<req(); ++i ) { // For all paths in
58 Node *n = in(i); // Get Control source
59 if( !n ) continue; // Missing inputs are TOP
60 if( phase->type(n) == Type::CONTROL )
61 return Type::CONTROL;
62 }
63 return Type::TOP; // All paths dead? Then so are we
64 }
65
66 //------------------------------Identity---------------------------------------
67 // Check for Region being Identity.
68 Node* RegionNode::Identity(PhaseGVN* phase) {
69 // Cannot have Region be an identity, even if it has only 1 input.
70 // Phi users cannot have their Region input folded away for them,
71 // since they need to select the proper data input
72 return this;
73 }
74
75 //------------------------------merge_region-----------------------------------
76 // If a Region flows into a Region, merge into one big happy merge. This is
77 // hard to do if there is stuff that has to happen
78 static Node *merge_region(RegionNode *region, PhaseGVN *phase) {
79 if( region->Opcode() != Op_Region ) // Do not do to LoopNodes
80 return NULL;
81 Node *progress = NULL; // Progress flag
82 PhaseIterGVN *igvn = phase->is_IterGVN();
83
84 uint rreq = region->req();
85 for( uint i = 1; i < rreq; i++ ) {
86 Node *r = region->in(i);
87 if( r && r->Opcode() == Op_Region && // Found a region?
88 r->in(0) == r && // Not already collapsed?
89 r != region && // Avoid stupid situations
90 r->outcnt() == 2 ) { // Self user and 'region' user only?
91 assert(!r->as_Region()->has_phi(), "no phi users");
92 if( !progress ) { // No progress
93 if (region->has_phi()) {
94 return NULL; // Only flatten if no Phi users
95 // igvn->hash_delete( phi );
96 }
97 igvn->hash_delete( region );
98 progress = region; // Making progress
99 }
100 igvn->hash_delete( r );
101
102 // Append inputs to 'r' onto 'region'
103 for( uint j = 1; j < r->req(); j++ ) {
104 // Move an input from 'r' to 'region'
105 region->add_req(r->in(j));
106 r->set_req(j, phase->C->top());
107 // Update phis of 'region'
108 //for( uint k = 0; k < max; k++ ) {
109 // Node *phi = region->out(k);
110 // if( phi->is_Phi() ) {
111 // phi->add_req(phi->in(i));
112 // }
113 //}
114
115 rreq++; // One more input to Region
116 } // Found a region to merge into Region
117 igvn->_worklist.push(r);
118 // Clobber pointer to the now dead 'r'
119 region->set_req(i, phase->C->top());
120 }
121 }
122
123 return progress;
124 }
125
126
127
128 //--------------------------------has_phi--------------------------------------
129 // Helper function: Return any PhiNode that uses this region or NULL
130 PhiNode* RegionNode::has_phi() const {
131 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
132 Node* phi = fast_out(i);
133 if (phi->is_Phi()) { // Check for Phi users
134 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
135 return phi->as_Phi(); // this one is good enough
136 }
137 }
138
139 return NULL;
140 }
141
142
143 //-----------------------------has_unique_phi----------------------------------
144 // Helper function: Return the only PhiNode that uses this region or NULL
145 PhiNode* RegionNode::has_unique_phi() const {
146 // Check that only one use is a Phi
147 PhiNode* only_phi = NULL;
148 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
149 Node* phi = fast_out(i);
150 if (phi->is_Phi()) { // Check for Phi users
151 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
152 if (only_phi == NULL) {
153 only_phi = phi->as_Phi();
154 } else {
155 return NULL; // multiple phis
156 }
157 }
158 }
159
160 return only_phi;
161 }
162
163
164 //------------------------------check_phi_clipping-----------------------------
165 // Helper function for RegionNode's identification of FP clipping
166 // Check inputs to the Phi
167 static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) {
168 min = NULL;
169 max = NULL;
170 val = NULL;
171 min_idx = 0;
172 max_idx = 0;
173 val_idx = 0;
174 uint phi_max = phi->req();
175 if( phi_max == 4 ) {
176 for( uint j = 1; j < phi_max; ++j ) {
177 Node *n = phi->in(j);
178 int opcode = n->Opcode();
179 switch( opcode ) {
180 case Op_ConI:
181 {
182 if( min == NULL ) {
183 min = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
184 min_idx = j;
185 } else {
186 max = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
187 max_idx = j;
188 if( min->get_int() > max->get_int() ) {
189 // Swap min and max
190 ConNode *temp;
191 uint temp_idx;
192 temp = min; min = max; max = temp;
193 temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx;
194 }
195 }
196 }
197 break;
198 default:
199 {
200 val = n;
201 val_idx = j;
202 }
203 break;
204 }
205 }
206 }
207 return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) );
208 }
209
210
211 //------------------------------check_if_clipping------------------------------
212 // Helper function for RegionNode's identification of FP clipping
213 // Check that inputs to Region come from two IfNodes,
214 //
215 // If
216 // False True
217 // If |
218 // False True |
219 // | | |
220 // RegionNode_inputs
221 //
222 static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) {
223 top_if = NULL;
224 bot_if = NULL;
225
226 // Check control structure above RegionNode for (if ( if ) )
227 Node *in1 = region->in(1);
228 Node *in2 = region->in(2);
229 Node *in3 = region->in(3);
230 // Check that all inputs are projections
231 if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) {
232 Node *in10 = in1->in(0);
233 Node *in20 = in2->in(0);
234 Node *in30 = in3->in(0);
235 // Check that #1 and #2 are ifTrue and ifFalse from same If
236 if( in10 != NULL && in10->is_If() &&
237 in20 != NULL && in20->is_If() &&
238 in30 != NULL && in30->is_If() && in10 == in20 &&
239 (in1->Opcode() != in2->Opcode()) ) {
240 Node *in100 = in10->in(0);
241 Node *in1000 = (in100 != NULL && in100->is_Proj()) ? in100->in(0) : NULL;
242 // Check that control for in10 comes from other branch of IF from in3
243 if( in1000 != NULL && in1000->is_If() &&
244 in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) {
245 // Control pattern checks
246 top_if = (IfNode*)in1000;
247 bot_if = (IfNode*)in10;
248 }
249 }
250 }
251
252 return (top_if != NULL);
253 }
254
255
256 //------------------------------check_convf2i_clipping-------------------------
257 // Helper function for RegionNode's identification of FP clipping
258 // Verify that the value input to the phi comes from "ConvF2I; LShift; RShift"
259 static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) {
260 convf2i = NULL;
261
262 // Check for the RShiftNode
263 Node *rshift = phi->in(idx);
264 assert( rshift, "Previous checks ensure phi input is present");
265 if( rshift->Opcode() != Op_RShiftI ) { return false; }
266
267 // Check for the LShiftNode
268 Node *lshift = rshift->in(1);
269 assert( lshift, "Previous checks ensure phi input is present");
270 if( lshift->Opcode() != Op_LShiftI ) { return false; }
271
272 // Check for the ConvF2INode
273 Node *conv = lshift->in(1);
274 if( conv->Opcode() != Op_ConvF2I ) { return false; }
275
276 // Check that shift amounts are only to get sign bits set after F2I
277 jint max_cutoff = max->get_int();
278 jint min_cutoff = min->get_int();
279 jint left_shift = lshift->in(2)->get_int();
280 jint right_shift = rshift->in(2)->get_int();
281 jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1);
282 if( left_shift != right_shift ||
283 0 > left_shift || left_shift >= BitsPerJavaInteger ||
284 max_post_shift < max_cutoff ||
285 max_post_shift < -min_cutoff ) {
286 // Shifts are necessary but current transformation eliminates them
287 return false;
288 }
289
290 // OK to return the result of ConvF2I without shifting
291 convf2i = (ConvF2INode*)conv;
292 return true;
293 }
294
295
296 //------------------------------check_compare_clipping-------------------------
297 // Helper function for RegionNode's identification of FP clipping
298 static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) {
299 Node *i1 = iff->in(1);
300 if ( !i1->is_Bool() ) { return false; }
301 BoolNode *bool1 = i1->as_Bool();
302 if( less_than && bool1->_test._test != BoolTest::le ) { return false; }
303 else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; }
304 const Node *cmpF = bool1->in(1);
305 if( cmpF->Opcode() != Op_CmpF ) { return false; }
306 // Test that the float value being compared against
307 // is equivalent to the int value used as a limit
308 Node *nodef = cmpF->in(2);
309 if( nodef->Opcode() != Op_ConF ) { return false; }
310 jfloat conf = nodef->getf();
311 jint coni = limit->get_int();
312 if( ((int)conf) != coni ) { return false; }
313 input = cmpF->in(1);
314 return true;
315 }
316
317 //------------------------------is_unreachable_region--------------------------
318 // Find if the Region node is reachable from the root.
319 bool RegionNode::is_unreachable_region(PhaseGVN *phase) const {
320 assert(req() == 2, "");
321
322 // First, cut the simple case of fallthrough region when NONE of
323 // region's phis references itself directly or through a data node.
324 uint max = outcnt();
325 uint i;
326 for (i = 0; i < max; i++) {
327 Node* phi = raw_out(i);
328 if (phi != NULL && phi->is_Phi()) {
329 assert(phase->eqv(phi->in(0), this) && phi->req() == 2, "");
330 if (phi->outcnt() == 0)
331 continue; // Safe case - no loops
332 if (phi->outcnt() == 1) {
333 Node* u = phi->raw_out(0);
334 // Skip if only one use is an other Phi or Call or Uncommon trap.
335 // It is safe to consider this case as fallthrough.
336 if (u != NULL && (u->is_Phi() || u->is_CFG()))
337 continue;
338 }
339 // Check when phi references itself directly or through an other node.
340 if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe)
341 break; // Found possible unsafe data loop.
342 }
343 }
344 if (i >= max)
345 return false; // An unsafe case was NOT found - don't need graph walk.
346
347 // Unsafe case - check if the Region node is reachable from root.
348 ResourceMark rm;
349
350 Node_List nstack;
351 VectorSet visited;
352
353 // Mark all control nodes reachable from root outputs
354 Node *n = (Node*)phase->C->root();
355 nstack.push(n);
356 visited.set(n->_idx);
357 while (nstack.size() != 0) {
358 n = nstack.pop();
359 uint max = n->outcnt();
360 for (uint i = 0; i < max; i++) {
361 Node* m = n->raw_out(i);
362 if (m != NULL && m->is_CFG()) {
363 if (phase->eqv(m, this)) {
364 return false; // We reached the Region node - it is not dead.
365 }
366 if (!visited.test_set(m->_idx))
367 nstack.push(m);
368 }
369 }
370 }
371
372 return true; // The Region node is unreachable - it is dead.
373 }
374
375 bool RegionNode::try_clean_mem_phi(PhaseGVN *phase) {
376 // Incremental inlining + PhaseStringOpts sometimes produce:
377 //
378 // cmpP with 1 top input
379 // |
380 // If
381 // / \
382 // IfFalse IfTrue /- Some Node
383 // \ / / /
384 // Region / /-MergeMem
385 // \---Phi
386 //
387 //
388 // It's expected by PhaseStringOpts that the Region goes away and is
389 // replaced by If's control input but because there's still a Phi,
390 // the Region stays in the graph. The top input from the cmpP is
391 // propagated forward and a subgraph that is useful goes away. The
392 // code below replaces the Phi with the MergeMem so that the Region
393 // is simplified.
394
395 PhiNode* phi = has_unique_phi();
396 if (phi && phi->type() == Type::MEMORY && req() == 3 && phi->is_diamond_phi(true)) {
397 MergeMemNode* m = NULL;
398 assert(phi->req() == 3, "same as region");
399 for (uint i = 1; i < 3; ++i) {
400 Node *mem = phi->in(i);
401 if (mem && mem->is_MergeMem() && in(i)->outcnt() == 1) {
402 // Nothing is control-dependent on path #i except the region itself.
403 m = mem->as_MergeMem();
404 uint j = 3 - i;
405 Node* other = phi->in(j);
406 if (other && other == m->base_memory()) {
407 // m is a successor memory to other, and is not pinned inside the diamond, so push it out.
408 // This will allow the diamond to collapse completely.
409 phase->is_IterGVN()->replace_node(phi, m);
410 return true;
411 }
412 }
413 }
414 }
415 return false;
416 }
417
418 //------------------------------Ideal------------------------------------------
419 // Return a node which is more "ideal" than the current node. Must preserve
420 // the CFG, but we can still strip out dead paths.
421 Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) {
422 if( !can_reshape && !in(0) ) return NULL; // Already degraded to a Copy
423 assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge");
424
425 // Check for RegionNode with no Phi users and both inputs come from either
426 // arm of the same IF. If found, then the control-flow split is useless.
427 bool has_phis = false;
428 if (can_reshape) { // Need DU info to check for Phi users
429 has_phis = (has_phi() != NULL); // Cache result
430 if (has_phis && try_clean_mem_phi(phase)) {
431 has_phis = false;
432 }
433
434 if (!has_phis) { // No Phi users? Nothing merging?
435 for (uint i = 1; i < req()-1; i++) {
436 Node *if1 = in(i);
437 if( !if1 ) continue;
438 Node *iff = if1->in(0);
439 if( !iff || !iff->is_If() ) continue;
440 for( uint j=i+1; j<req(); j++ ) {
441 if( in(j) && in(j)->in(0) == iff &&
442 if1->Opcode() != in(j)->Opcode() ) {
443 // Add the IF Projections to the worklist. They (and the IF itself)
444 // will be eliminated if dead.
445 phase->is_IterGVN()->add_users_to_worklist(iff);
446 set_req(i, iff->in(0));// Skip around the useless IF diamond
447 set_req(j, NULL);
448 return this; // Record progress
449 }
450 }
451 }
452 }
453 }
454
455 // Remove TOP or NULL input paths. If only 1 input path remains, this Region
456 // degrades to a copy.
457 bool add_to_worklist = false;
458 bool modified = false;
459 int cnt = 0; // Count of values merging
460 DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count
461 int del_it = 0; // The last input path we delete
462 // For all inputs...
463 for( uint i=1; i<req(); ++i ){// For all paths in
464 Node *n = in(i); // Get the input
465 if( n != NULL ) {
466 // Remove useless control copy inputs
467 if( n->is_Region() && n->as_Region()->is_copy() ) {
468 set_req(i, n->nonnull_req());
469 modified = true;
470 i--;
471 continue;
472 }
473 if( n->is_Proj() ) { // Remove useless rethrows
474 Node *call = n->in(0);
475 if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) {
476 set_req(i, call->in(0));
477 modified = true;
478 i--;
479 continue;
480 }
481 }
482 if( phase->type(n) == Type::TOP ) {
483 set_req(i, NULL); // Ignore TOP inputs
484 modified = true;
485 i--;
486 continue;
487 }
488 cnt++; // One more value merging
489
490 } else if (can_reshape) { // Else found dead path with DU info
491 PhaseIterGVN *igvn = phase->is_IterGVN();
492 del_req(i); // Yank path from self
493 del_it = i;
494 uint max = outcnt();
495 DUIterator j;
496 bool progress = true;
497 while(progress) { // Need to establish property over all users
498 progress = false;
499 for (j = outs(); has_out(j); j++) {
500 Node *n = out(j);
501 if( n->req() != req() && n->is_Phi() ) {
502 assert( n->in(0) == this, "" );
503 igvn->hash_delete(n); // Yank from hash before hacking edges
504 n->set_req_X(i,NULL,igvn);// Correct DU info
505 n->del_req(i); // Yank path from Phis
506 if( max != outcnt() ) {
507 progress = true;
508 j = refresh_out_pos(j);
509 max = outcnt();
510 }
511 }
512 }
513 }
514 add_to_worklist = true;
515 i--;
516 }
517 }
518
519 if (can_reshape && cnt == 1) {
520 // Is it dead loop?
521 // If it is LoopNopde it had 2 (+1 itself) inputs and
522 // one of them was cut. The loop is dead if it was EntryContol.
523 // Loop node may have only one input because entry path
524 // is removed in PhaseIdealLoop::Dominators().
525 assert(!this->is_Loop() || cnt_orig <= 3, "Loop node should have 3 or less inputs");
526 if ((this->is_Loop() && (del_it == LoopNode::EntryControl ||
527 (del_it == 0 && is_unreachable_region(phase)))) ||
528 (!this->is_Loop() && has_phis && is_unreachable_region(phase))) {
529 // Yes, the region will be removed during the next step below.
530 // Cut the backedge input and remove phis since no data paths left.
531 // We don't cut outputs to other nodes here since we need to put them
532 // on the worklist.
533 PhaseIterGVN *igvn = phase->is_IterGVN();
534 if (in(1)->outcnt() == 1) {
535 igvn->_worklist.push(in(1));
536 }
537 del_req(1);
538 cnt = 0;
539 assert( req() == 1, "no more inputs expected" );
540 uint max = outcnt();
541 bool progress = true;
542 Node *top = phase->C->top();
543 DUIterator j;
544 while(progress) {
545 progress = false;
546 for (j = outs(); has_out(j); j++) {
547 Node *n = out(j);
548 if( n->is_Phi() ) {
549 assert( igvn->eqv(n->in(0), this), "" );
550 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
551 // Break dead loop data path.
552 // Eagerly replace phis with top to avoid phis copies generation.
553 igvn->replace_node(n, top);
554 if( max != outcnt() ) {
555 progress = true;
556 j = refresh_out_pos(j);
557 max = outcnt();
558 }
559 }
560 }
561 }
562 add_to_worklist = true;
563 }
564 }
565 if (add_to_worklist) {
566 phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis
567 }
568
569 if( cnt <= 1 ) { // Only 1 path in?
570 set_req(0, NULL); // Null control input for region copy
571 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is.
572 // No inputs or all inputs are NULL.
573 return NULL;
574 } else if (can_reshape) { // Optimization phase - remove the node
575 PhaseIterGVN *igvn = phase->is_IterGVN();
576 // Strip mined (inner) loop is going away, remove outer loop.
577 if (is_CountedLoop() &&
578 as_Loop()->is_strip_mined()) {
579 Node* outer_sfpt = as_CountedLoop()->outer_safepoint();
580 Node* outer_out = as_CountedLoop()->outer_loop_exit();
581 if (outer_sfpt != NULL && outer_out != NULL) {
582 Node* in = outer_sfpt->in(0);
583 igvn->replace_node(outer_out, in);
584 LoopNode* outer = as_CountedLoop()->outer_loop();
585 igvn->replace_input_of(outer, LoopNode::LoopBackControl, igvn->C->top());
586 }
587 }
588 Node *parent_ctrl;
589 if( cnt == 0 ) {
590 assert( req() == 1, "no inputs expected" );
591 // During IGVN phase such region will be subsumed by TOP node
592 // so region's phis will have TOP as control node.
593 // Kill phis here to avoid it. PhiNode::is_copy() will be always false.
594 // Also set other user's input to top.
595 parent_ctrl = phase->C->top();
596 } else {
597 // The fallthrough case since we already checked dead loops above.
598 parent_ctrl = in(1);
599 assert(parent_ctrl != NULL, "Region is a copy of some non-null control");
600 assert(!igvn->eqv(parent_ctrl, this), "Close dead loop");
601 }
602 if (!add_to_worklist)
603 igvn->add_users_to_worklist(this); // Check for further allowed opts
604 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
605 Node* n = last_out(i);
606 igvn->hash_delete(n); // Remove from worklist before modifying edges
607 if( n->is_Phi() ) { // Collapse all Phis
608 // Eagerly replace phis to avoid copies generation.
609 Node* in;
610 if( cnt == 0 ) {
611 assert( n->req() == 1, "No data inputs expected" );
612 in = parent_ctrl; // replaced by top
613 } else {
614 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
615 in = n->in(1); // replaced by unique input
616 if( n->as_Phi()->is_unsafe_data_reference(in) )
617 in = phase->C->top(); // replaced by top
618 }
619 igvn->replace_node(n, in);
620 }
621 else if( n->is_Region() ) { // Update all incoming edges
622 assert( !igvn->eqv(n, this), "Must be removed from DefUse edges");
623 uint uses_found = 0;
624 for( uint k=1; k < n->req(); k++ ) {
625 if( n->in(k) == this ) {
626 n->set_req(k, parent_ctrl);
627 uses_found++;
628 }
629 }
630 if( uses_found > 1 ) { // (--i) done at the end of the loop.
631 i -= (uses_found - 1);
632 }
633 }
634 else {
635 assert( igvn->eqv(n->in(0), this), "Expect RegionNode to be control parent");
636 n->set_req(0, parent_ctrl);
637 }
638 #ifdef ASSERT
639 for( uint k=0; k < n->req(); k++ ) {
640 assert( !igvn->eqv(n->in(k), this), "All uses of RegionNode should be gone");
641 }
642 #endif
643 }
644 // Remove the RegionNode itself from DefUse info
645 igvn->remove_dead_node(this);
646 return NULL;
647 }
648 return this; // Record progress
649 }
650
651
652 // If a Region flows into a Region, merge into one big happy merge.
653 if (can_reshape) {
654 Node *m = merge_region(this, phase);
655 if (m != NULL) return m;
656 }
657
658 // Check if this region is the root of a clipping idiom on floats
659 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
660 // Check that only one use is a Phi and that it simplifies to two constants +
661 PhiNode* phi = has_unique_phi();
662 if (phi != NULL) { // One Phi user
663 // Check inputs to the Phi
664 ConNode *min;
665 ConNode *max;
666 Node *val;
667 uint min_idx;
668 uint max_idx;
669 uint val_idx;
670 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) {
671 IfNode *top_if;
672 IfNode *bot_if;
673 if( check_if_clipping( this, bot_if, top_if ) ) {
674 // Control pattern checks, now verify compares
675 Node *top_in = NULL; // value being compared against
676 Node *bot_in = NULL;
677 if( check_compare_clipping( true, bot_if, min, bot_in ) &&
678 check_compare_clipping( false, top_if, max, top_in ) ) {
679 if( bot_in == top_in ) {
680 PhaseIterGVN *gvn = phase->is_IterGVN();
681 assert( gvn != NULL, "Only had DefUse info in IterGVN");
682 // Only remaining check is that bot_in == top_in == (Phi's val + mods)
683
684 // Check for the ConvF2INode
685 ConvF2INode *convf2i;
686 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
687 convf2i->in(1) == bot_in ) {
688 // Matched pattern, including LShiftI; RShiftI, replace with integer compares
689 // max test
690 Node *cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, min ));
691 Node *boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::lt ));
692 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt ));
693 Node *if_min= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
694 Node *ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
695 // min test
696 cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, max ));
697 boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::gt ));
698 iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
699 Node *if_max= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
700 ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
701 // update input edges to region node
702 set_req_X( min_idx, if_min, gvn );
703 set_req_X( max_idx, if_max, gvn );
704 set_req_X( val_idx, ifF, gvn );
705 // remove unnecessary 'LShiftI; RShiftI' idiom
706 gvn->hash_delete(phi);
707 phi->set_req_X( val_idx, convf2i, gvn );
708 gvn->hash_find_insert(phi);
709 // Return transformed region node
710 return this;
711 }
712 }
713 }
714 }
715 }
716 }
717 }
718
719 if (can_reshape) {
720 modified |= optimize_trichotomy(phase->is_IterGVN());
721 }
722
723 return modified ? this : NULL;
724 }
725
726 //------------------------------optimize_trichotomy--------------------------
727 // Optimize nested comparisons of the following kind:
728 //
729 // int compare(int a, int b) {
730 // return (a < b) ? -1 : (a == b) ? 0 : 1;
731 // }
732 //
733 // Shape 1:
734 // if (compare(a, b) == 1) { ... } -> if (a > b) { ... }
735 //
736 // Shape 2:
737 // if (compare(a, b) == 0) { ... } -> if (a == b) { ... }
738 //
739 // Above code leads to the following IR shapes where both Ifs compare the
740 // same value and two out of three region inputs idx1 and idx2 map to
741 // the same value and control flow.
742 //
743 // (1) If (2) If
744 // / \ / \
745 // Proj Proj Proj Proj
746 // | \ | \
747 // | If | If If
748 // | / \ | / \ / \
749 // | Proj Proj | Proj Proj ==> Proj Proj
750 // | / / \ | / | /
751 // Region / \ | / | /
752 // \ / \ | / | /
753 // Region Region Region
754 //
755 // The method returns true if 'this' is modified and false otherwise.
756 bool RegionNode::optimize_trichotomy(PhaseIterGVN* igvn) {
757 int idx1 = 1, idx2 = 2;
758 Node* region = NULL;
759 if (req() == 3 && in(1) != NULL && in(2) != NULL) {
760 // Shape 1: Check if one of the inputs is a region that merges two control
761 // inputs and has no other users (especially no Phi users).
762 region = in(1)->isa_Region() ? in(1) : in(2)->isa_Region();
763 if (region == NULL || region->outcnt() != 2 || region->req() != 3) {
764 return false; // No suitable region input found
765 }
766 } else if (req() == 4) {
767 // Shape 2: Check if two control inputs map to the same value of the unique phi
768 // user and treat these as if they would come from another region (shape (1)).
769 PhiNode* phi = has_unique_phi();
770 if (phi == NULL) {
771 return false; // No unique phi user
772 }
773 if (phi->in(idx1) != phi->in(idx2)) {
774 idx2 = 3;
775 if (phi->in(idx1) != phi->in(idx2)) {
776 idx1 = 2;
777 if (phi->in(idx1) != phi->in(idx2)) {
778 return false; // No equal phi inputs found
779 }
780 }
781 }
782 assert(phi->in(idx1) == phi->in(idx2), "must be"); // Region is merging same value
783 region = this;
784 }
785 if (region == NULL || region->in(idx1) == NULL || region->in(idx2) == NULL) {
786 return false; // Region does not merge two control inputs
787 }
788 // At this point we know that region->in(idx1) and region->(idx2) map to the same
789 // value and control flow. Now search for ifs that feed into these region inputs.
790 ProjNode* proj1 = region->in(idx1)->isa_Proj();
791 ProjNode* proj2 = region->in(idx2)->isa_Proj();
792 if (proj1 == NULL || proj1->outcnt() != 1 ||
793 proj2 == NULL || proj2->outcnt() != 1) {
794 return false; // No projection inputs with region as unique user found
795 }
796 assert(proj1 != proj2, "should be different projections");
797 IfNode* iff1 = proj1->in(0)->isa_If();
798 IfNode* iff2 = proj2->in(0)->isa_If();
799 if (iff1 == NULL || iff1->outcnt() != 2 ||
800 iff2 == NULL || iff2->outcnt() != 2) {
801 return false; // No ifs found
802 }
803 if (iff1 == iff2) {
804 igvn->add_users_to_worklist(iff1); // Make sure dead if is eliminated
805 igvn->replace_input_of(region, idx1, iff1->in(0));
806 igvn->replace_input_of(region, idx2, igvn->C->top());
807 return (region == this); // Remove useless if (both projections map to the same control/value)
808 }
809 BoolNode* bol1 = iff1->in(1)->isa_Bool();
810 BoolNode* bol2 = iff2->in(1)->isa_Bool();
811 if (bol1 == NULL || bol2 == NULL) {
812 return false; // No bool inputs found
813 }
814 Node* cmp1 = bol1->in(1);
815 Node* cmp2 = bol2->in(1);
816 bool commute = false;
817 if (!cmp1->is_Cmp() || !cmp2->is_Cmp()) {
818 return false; // No comparison
819 } else if (cmp1->Opcode() == Op_CmpF || cmp1->Opcode() == Op_CmpD ||
820 cmp2->Opcode() == Op_CmpF || cmp2->Opcode() == Op_CmpD ||
821 cmp1->Opcode() == Op_CmpP || cmp1->Opcode() == Op_CmpN ||
822 cmp2->Opcode() == Op_CmpP || cmp2->Opcode() == Op_CmpN) {
823 // Floats and pointers don't exactly obey trichotomy. To be on the safe side, don't transform their tests.
824 return false;
825 } else if (cmp1 != cmp2) {
826 if (cmp1->in(1) == cmp2->in(2) &&
827 cmp1->in(2) == cmp2->in(1)) {
828 commute = true; // Same but swapped inputs, commute the test
829 } else {
830 return false; // Ifs are not comparing the same values
831 }
832 }
833 proj1 = proj1->other_if_proj();
834 proj2 = proj2->other_if_proj();
835 if (!((proj1->unique_ctrl_out() == iff2 &&
836 proj2->unique_ctrl_out() == this) ||
837 (proj2->unique_ctrl_out() == iff1 &&
838 proj1->unique_ctrl_out() == this))) {
839 return false; // Ifs are not connected through other projs
840 }
841 // Found 'iff -> proj -> iff -> proj -> this' shape where all other projs are merged
842 // through 'region' and map to the same value. Merge the boolean tests and replace
843 // the ifs by a single comparison.
844 BoolTest test1 = (proj1->_con == 1) ? bol1->_test : bol1->_test.negate();
845 BoolTest test2 = (proj2->_con == 1) ? bol2->_test : bol2->_test.negate();
846 test1 = commute ? test1.commute() : test1;
847 // After possibly commuting test1, if we can merge test1 & test2, then proj2/iff2/bol2 are the nodes to refine.
848 BoolTest::mask res = test1.merge(test2);
849 if (res == BoolTest::illegal) {
850 return false; // Unable to merge tests
851 }
852 // Adjust iff1 to always pass (only iff2 will remain)
853 igvn->replace_input_of(iff1, 1, igvn->intcon(proj1->_con));
854 if (res == BoolTest::never) {
855 // Merged test is always false, adjust iff2 to always fail
856 igvn->replace_input_of(iff2, 1, igvn->intcon(1 - proj2->_con));
857 } else {
858 // Replace bool input of iff2 with merged test
859 BoolNode* new_bol = new BoolNode(bol2->in(1), res);
860 igvn->replace_input_of(iff2, 1, igvn->transform((proj2->_con == 1) ? new_bol : new_bol->negate(igvn)));
861 }
862 return false;
863 }
864
865 const RegMask &RegionNode::out_RegMask() const {
866 return RegMask::Empty;
867 }
868
869 // Find the one non-null required input. RegionNode only
870 Node *Node::nonnull_req() const {
871 assert( is_Region(), "" );
872 for( uint i = 1; i < _cnt; i++ )
873 if( in(i) )
874 return in(i);
875 ShouldNotReachHere();
876 return NULL;
877 }
878
879
880 //=============================================================================
881 // note that these functions assume that the _adr_type field is flattened
882 uint PhiNode::hash() const {
883 const Type* at = _adr_type;
884 return TypeNode::hash() + (at ? at->hash() : 0);
885 }
886 bool PhiNode::cmp( const Node &n ) const {
887 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
888 }
889 static inline
890 const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
891 if (at == NULL || at == TypePtr::BOTTOM) return at;
892 return Compile::current()->alias_type(at)->adr_type();
893 }
894
895 //----------------------------make---------------------------------------------
896 // create a new phi with edges matching r and set (initially) to x
897 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
898 uint preds = r->req(); // Number of predecessor paths
899 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at");
900 PhiNode* p = new PhiNode(r, t, at);
901 for (uint j = 1; j < preds; j++) {
902 // Fill in all inputs, except those which the region does not yet have
903 if (r->in(j) != NULL)
904 p->init_req(j, x);
905 }
906 return p;
907 }
908 PhiNode* PhiNode::make(Node* r, Node* x) {
909 const Type* t = x->bottom_type();
910 const TypePtr* at = NULL;
911 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
912 return make(r, x, t, at);
913 }
914 PhiNode* PhiNode::make_blank(Node* r, Node* x) {
915 const Type* t = x->bottom_type();
916 const TypePtr* at = NULL;
917 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
918 return new PhiNode(r, t, at);
919 }
920
921
922 //------------------------slice_memory-----------------------------------------
923 // create a new phi with narrowed memory type
924 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
925 PhiNode* mem = (PhiNode*) clone();
926 *(const TypePtr**)&mem->_adr_type = adr_type;
927 // convert self-loops, or else we get a bad graph
928 for (uint i = 1; i < req(); i++) {
929 if ((const Node*)in(i) == this) mem->set_req(i, mem);
930 }
931 mem->verify_adr_type();
932 return mem;
933 }
934
935 //------------------------split_out_instance-----------------------------------
936 // Split out an instance type from a bottom phi.
937 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const {
938 const TypeOopPtr *t_oop = at->isa_oopptr();
939 assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr");
940 const TypePtr *t = adr_type();
941 assert(type() == Type::MEMORY &&
942 (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
943 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
944 t->is_oopptr()->cast_to_exactness(true)
945 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
946 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop),
947 "bottom or raw memory required");
948
949 // Check if an appropriate node already exists.
950 Node *region = in(0);
951 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) {
952 Node* use = region->fast_out(k);
953 if( use->is_Phi()) {
954 PhiNode *phi2 = use->as_Phi();
955 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) {
956 return phi2;
957 }
958 }
959 }
960 Compile *C = igvn->C;
961 Arena *a = Thread::current()->resource_area();
962 Node_Array node_map = new Node_Array(a);
963 Node_Stack stack(a, C->live_nodes() >> 4);
964 PhiNode *nphi = slice_memory(at);
965 igvn->register_new_node_with_optimizer( nphi );
966 node_map.map(_idx, nphi);
967 stack.push((Node *)this, 1);
968 while(!stack.is_empty()) {
969 PhiNode *ophi = stack.node()->as_Phi();
970 uint i = stack.index();
971 assert(i >= 1, "not control edge");
972 stack.pop();
973 nphi = node_map[ophi->_idx]->as_Phi();
974 for (; i < ophi->req(); i++) {
975 Node *in = ophi->in(i);
976 if (in == NULL || igvn->type(in) == Type::TOP)
977 continue;
978 Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, NULL, igvn);
979 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL;
980 if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) {
981 opt = node_map[optphi->_idx];
982 if (opt == NULL) {
983 stack.push(ophi, i);
984 nphi = optphi->slice_memory(at);
985 igvn->register_new_node_with_optimizer( nphi );
986 node_map.map(optphi->_idx, nphi);
987 ophi = optphi;
988 i = 0; // will get incremented at top of loop
989 continue;
990 }
991 }
992 nphi->set_req(i, opt);
993 }
994 }
995 return nphi;
996 }
997
998 //------------------------verify_adr_type--------------------------------------
999 #ifdef ASSERT
1000 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
1001 if (visited.test_set(_idx)) return; //already visited
1002
1003 // recheck constructor invariants:
1004 verify_adr_type(false);
1005
1006 // recheck local phi/phi consistency:
1007 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
1008 "adr_type must be consistent across phi nest");
1009
1010 // walk around
1011 for (uint i = 1; i < req(); i++) {
1012 Node* n = in(i);
1013 if (n == NULL) continue;
1014 const Node* np = in(i);
1015 if (np->is_Phi()) {
1016 np->as_Phi()->verify_adr_type(visited, at);
1017 } else if (n->bottom_type() == Type::TOP
1018 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
1019 // ignore top inputs
1020 } else {
1021 const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
1022 // recheck phi/non-phi consistency at leaves:
1023 assert((nat != NULL) == (at != NULL), "");
1024 assert(nat == at || nat == TypePtr::BOTTOM,
1025 "adr_type must be consistent at leaves of phi nest");
1026 }
1027 }
1028 }
1029
1030 // Verify a whole nest of phis rooted at this one.
1031 void PhiNode::verify_adr_type(bool recursive) const {
1032 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
1033 if (Node::in_dump()) return; // muzzle asserts when printing
1034
1035 assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only");
1036
1037 if (!VerifyAliases) return; // verify thoroughly only if requested
1038
1039 assert(_adr_type == flatten_phi_adr_type(_adr_type),
1040 "Phi::adr_type must be pre-normalized");
1041
1042 if (recursive) {
1043 VectorSet visited;
1044 verify_adr_type(visited, _adr_type);
1045 }
1046 }
1047 #endif
1048
1049
1050 //------------------------------Value------------------------------------------
1051 // Compute the type of the PhiNode
1052 const Type* PhiNode::Value(PhaseGVN* phase) const {
1053 Node *r = in(0); // RegionNode
1054 if( !r ) // Copy or dead
1055 return in(1) ? phase->type(in(1)) : Type::TOP;
1056
1057 // Note: During parsing, phis are often transformed before their regions.
1058 // This means we have to use type_or_null to defend against untyped regions.
1059 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1060 return Type::TOP;
1061
1062 // Check for trip-counted loop. If so, be smarter.
1063 CountedLoopNode* l = r->is_CountedLoop() ? r->as_CountedLoop() : NULL;
1064 if (l && ((const Node*)l->phi() == this)) { // Trip counted loop!
1065 // protect against init_trip() or limit() returning NULL
1066 if (l->can_be_counted_loop(phase)) {
1067 const Node *init = l->init_trip();
1068 const Node *limit = l->limit();
1069 const Node* stride = l->stride();
1070 if (init != NULL && limit != NULL && stride != NULL) {
1071 const TypeInt* lo = phase->type(init)->isa_int();
1072 const TypeInt* hi = phase->type(limit)->isa_int();
1073 const TypeInt* stride_t = phase->type(stride)->isa_int();
1074 if (lo != NULL && hi != NULL && stride_t != NULL) { // Dying loops might have TOP here
1075 assert(stride_t->_hi >= stride_t->_lo, "bad stride type");
1076 BoolTest::mask bt = l->loopexit()->test_trip();
1077 // If the loop exit condition is "not equal", the condition
1078 // would not trigger if init > limit (if stride > 0) or if
1079 // init < limit if (stride > 0) so we can't deduce bounds
1080 // for the iv from the exit condition.
1081 if (bt != BoolTest::ne) {
1082 if (stride_t->_hi < 0) { // Down-counter loop
1083 swap(lo, hi);
1084 return TypeInt::make(MIN2(lo->_lo, hi->_lo) , hi->_hi, 3);
1085 } else if (stride_t->_lo >= 0) {
1086 return TypeInt::make(lo->_lo, MAX2(lo->_hi, hi->_hi), 3);
1087 }
1088 }
1089 }
1090 }
1091 } else if (l->in(LoopNode::LoopBackControl) != NULL &&
1092 in(LoopNode::EntryControl) != NULL &&
1093 phase->type(l->in(LoopNode::LoopBackControl)) == Type::TOP) {
1094 // During CCP, if we saturate the type of a counted loop's Phi
1095 // before the special code for counted loop above has a chance
1096 // to run (that is as long as the type of the backedge's control
1097 // is top), we might end up with non monotonic types
1098 return phase->type(in(LoopNode::EntryControl))->filter_speculative(_type);
1099 }
1100 }
1101
1102 // Until we have harmony between classes and interfaces in the type
1103 // lattice, we must tread carefully around phis which implicitly
1104 // convert the one to the other.
1105 const TypePtr* ttp = _type->make_ptr();
1106 const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL;
1107 const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_klassptr() : NULL;
1108 bool is_intf = false;
1109 if (ttip != NULL) {
1110 ciKlass* k = ttip->klass();
1111 if (k->is_loaded() && k->is_interface())
1112 is_intf = true;
1113 }
1114 if (ttkp != NULL) {
1115 ciKlass* k = ttkp->klass();
1116 if (k->is_loaded() && k->is_interface())
1117 is_intf = true;
1118 }
1119
1120 // Default case: merge all inputs
1121 const Type *t = Type::TOP; // Merged type starting value
1122 for (uint i = 1; i < req(); ++i) {// For all paths in
1123 // Reachable control path?
1124 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
1125 const Type* ti = phase->type(in(i));
1126 // We assume that each input of an interface-valued Phi is a true
1127 // subtype of that interface. This might not be true of the meet
1128 // of all the input types. The lattice is not distributive in
1129 // such cases. Ward off asserts in type.cpp by refusing to do
1130 // meets between interfaces and proper classes.
1131 const TypePtr* tip = ti->make_ptr();
1132 const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL;
1133 if (tiip) {
1134 bool ti_is_intf = false;
1135 ciKlass* k = tiip->klass();
1136 if (k->is_loaded() && k->is_interface())
1137 ti_is_intf = true;
1138 if (is_intf != ti_is_intf)
1139 { t = _type; break; }
1140 }
1141 t = t->meet_speculative(ti);
1142 }
1143 }
1144
1145 // The worst-case type (from ciTypeFlow) should be consistent with "t".
1146 // That is, we expect that "t->higher_equal(_type)" holds true.
1147 // There are various exceptions:
1148 // - Inputs which are phis might in fact be widened unnecessarily.
1149 // For example, an input might be a widened int while the phi is a short.
1150 // - Inputs might be BotPtrs but this phi is dependent on a null check,
1151 // and postCCP has removed the cast which encodes the result of the check.
1152 // - The type of this phi is an interface, and the inputs are classes.
1153 // - Value calls on inputs might produce fuzzy results.
1154 // (Occurrences of this case suggest improvements to Value methods.)
1155 //
1156 // It is not possible to see Type::BOTTOM values as phi inputs,
1157 // because the ciTypeFlow pre-pass produces verifier-quality types.
1158 const Type* ft = t->filter_speculative(_type); // Worst case type
1159
1160 #ifdef ASSERT
1161 // The following logic has been moved into TypeOopPtr::filter.
1162 const Type* jt = t->join_speculative(_type);
1163 if (jt->empty()) { // Emptied out???
1164
1165 // Check for evil case of 't' being a class and '_type' expecting an
1166 // interface. This can happen because the bytecodes do not contain
1167 // enough type info to distinguish a Java-level interface variable
1168 // from a Java-level object variable. If we meet 2 classes which
1169 // both implement interface I, but their meet is at 'j/l/O' which
1170 // doesn't implement I, we have no way to tell if the result should
1171 // be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows
1172 // into a Phi which "knows" it's an Interface type we'll have to
1173 // uplift the type.
1174 if (!t->empty() && ttip && ttip->is_loaded() && ttip->klass()->is_interface()) {
1175 assert(ft == _type, ""); // Uplift to interface
1176 } else if (!t->empty() && ttkp && ttkp->is_loaded() && ttkp->klass()->is_interface()) {
1177 assert(ft == _type, ""); // Uplift to interface
1178 } else {
1179 // We also have to handle 'evil cases' of interface- vs. class-arrays
1180 Type::get_arrays_base_elements(jt, _type, NULL, &ttip);
1181 if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
1182 assert(ft == _type, ""); // Uplift to array of interface
1183 } else {
1184 // Otherwise it's something stupid like non-overlapping int ranges
1185 // found on dying counted loops.
1186 assert(ft == Type::TOP, ""); // Canonical empty value
1187 }
1188 }
1189 }
1190
1191 else {
1192
1193 // If we have an interface-typed Phi and we narrow to a class type, the join
1194 // should report back the class. However, if we have a J/L/Object
1195 // class-typed Phi and an interface flows in, it's possible that the meet &
1196 // join report an interface back out. This isn't possible but happens
1197 // because the type system doesn't interact well with interfaces.
1198 const TypePtr *jtp = jt->make_ptr();
1199 const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL;
1200 const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_klassptr() : NULL;
1201 if( jtip && ttip ) {
1202 if( jtip->is_loaded() && jtip->klass()->is_interface() &&
1203 ttip->is_loaded() && !ttip->klass()->is_interface() ) {
1204 assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) ||
1205 ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), "");
1206 jt = ft;
1207 }
1208 }
1209 if( jtkp && ttkp ) {
1210 if( jtkp->is_loaded() && jtkp->klass()->is_interface() &&
1211 !jtkp->klass_is_exact() && // Keep exact interface klass (6894807)
1212 ttkp->is_loaded() && !ttkp->klass()->is_interface() ) {
1213 assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) ||
1214 ft->isa_narrowklass() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), "");
1215 jt = ft;
1216 }
1217 }
1218 if (jt != ft && jt->base() == ft->base()) {
1219 if (jt->isa_int() &&
1220 jt->is_int()->_lo == ft->is_int()->_lo &&
1221 jt->is_int()->_hi == ft->is_int()->_hi)
1222 jt = ft;
1223 if (jt->isa_long() &&
1224 jt->is_long()->_lo == ft->is_long()->_lo &&
1225 jt->is_long()->_hi == ft->is_long()->_hi)
1226 jt = ft;
1227 }
1228 if (jt != ft) {
1229 tty->print("merge type: "); t->dump(); tty->cr();
1230 tty->print("kill type: "); _type->dump(); tty->cr();
1231 tty->print("join type: "); jt->dump(); tty->cr();
1232 tty->print("filter type: "); ft->dump(); tty->cr();
1233 }
1234 assert(jt == ft, "");
1235 }
1236 #endif //ASSERT
1237
1238 // Deal with conversion problems found in data loops.
1239 ft = phase->saturate(ft, phase->type_or_null(this), _type);
1240
1241 return ft;
1242 }
1243
1244
1245 //------------------------------is_diamond_phi---------------------------------
1246 // Does this Phi represent a simple well-shaped diamond merge? Return the
1247 // index of the true path or 0 otherwise.
1248 // If check_control_only is true, do not inspect the If node at the
1249 // top, and return -1 (not an edge number) on success.
1250 int PhiNode::is_diamond_phi(bool check_control_only) const {
1251 // Check for a 2-path merge
1252 Node *region = in(0);
1253 if( !region ) return 0;
1254 if( region->req() != 3 ) return 0;
1255 if( req() != 3 ) return 0;
1256 // Check that both paths come from the same If
1257 Node *ifp1 = region->in(1);
1258 Node *ifp2 = region->in(2);
1259 if( !ifp1 || !ifp2 ) return 0;
1260 Node *iff = ifp1->in(0);
1261 if( !iff || !iff->is_If() ) return 0;
1262 if( iff != ifp2->in(0) ) return 0;
1263 if (check_control_only) return -1;
1264 // Check for a proper bool/cmp
1265 const Node *b = iff->in(1);
1266 if( !b->is_Bool() ) return 0;
1267 const Node *cmp = b->in(1);
1268 if( !cmp->is_Cmp() ) return 0;
1269
1270 // Check for branching opposite expected
1271 if( ifp2->Opcode() == Op_IfTrue ) {
1272 assert( ifp1->Opcode() == Op_IfFalse, "" );
1273 return 2;
1274 } else {
1275 assert( ifp1->Opcode() == Op_IfTrue, "" );
1276 return 1;
1277 }
1278 }
1279
1280 //----------------------------check_cmove_id-----------------------------------
1281 // Check for CMove'ing a constant after comparing against the constant.
1282 // Happens all the time now, since if we compare equality vs a constant in
1283 // the parser, we "know" the variable is constant on one path and we force
1284 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
1285 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more
1286 // general in that we don't need constants. Since CMove's are only inserted
1287 // in very special circumstances, we do it here on generic Phi's.
1288 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
1289 assert(true_path !=0, "only diamond shape graph expected");
1290
1291 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1292 // phi->region->if_proj->ifnode->bool->cmp
1293 Node* region = in(0);
1294 Node* iff = region->in(1)->in(0);
1295 BoolNode* b = iff->in(1)->as_Bool();
1296 Node* cmp = b->in(1);
1297 Node* tval = in(true_path);
1298 Node* fval = in(3-true_path);
1299 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
1300 if (id == NULL)
1301 return NULL;
1302
1303 // Either value might be a cast that depends on a branch of 'iff'.
1304 // Since the 'id' value will float free of the diamond, either
1305 // decast or return failure.
1306 Node* ctl = id->in(0);
1307 if (ctl != NULL && ctl->in(0) == iff) {
1308 if (id->is_ConstraintCast()) {
1309 return id->in(1);
1310 } else {
1311 // Don't know how to disentangle this value.
1312 return NULL;
1313 }
1314 }
1315
1316 return id;
1317 }
1318
1319 //------------------------------Identity---------------------------------------
1320 // Check for Region being Identity.
1321 Node* PhiNode::Identity(PhaseGVN* phase) {
1322 // Check for no merging going on
1323 // (There used to be special-case code here when this->region->is_Loop.
1324 // It would check for a tributary phi on the backedge that the main phi
1325 // trivially, perhaps with a single cast. The unique_input method
1326 // does all this and more, by reducing such tributaries to 'this'.)
1327 Node* uin = unique_input(phase, false);
1328 if (uin != NULL) {
1329 return uin;
1330 }
1331
1332 int true_path = is_diamond_phi();
1333 if (true_path != 0) {
1334 Node* id = is_cmove_id(phase, true_path);
1335 if (id != NULL) return id;
1336 }
1337
1338 // Looking for phis with identical inputs. If we find one that has
1339 // type TypePtr::BOTTOM, replace the current phi with the bottom phi.
1340 if (phase->is_IterGVN() && type() == Type::MEMORY && adr_type() !=
1341 TypePtr::BOTTOM && !adr_type()->is_known_instance()) {
1342 uint phi_len = req();
1343 Node* phi_reg = region();
1344 for (DUIterator_Fast imax, i = phi_reg->fast_outs(imax); i < imax; i++) {
1345 Node* u = phi_reg->fast_out(i);
1346 if (u->is_Phi() && u->as_Phi()->type() == Type::MEMORY &&
1347 u->adr_type() == TypePtr::BOTTOM && u->in(0) == phi_reg &&
1348 u->req() == phi_len) {
1349 for (uint j = 1; j < phi_len; j++) {
1350 if (in(j) != u->in(j)) {
1351 u = NULL;
1352 break;
1353 }
1354 }
1355 if (u != NULL) {
1356 return u;
1357 }
1358 }
1359 }
1360 }
1361
1362 return this; // No identity
1363 }
1364
1365 //-----------------------------unique_input------------------------------------
1366 // Find the unique value, discounting top, self-loops, and casts.
1367 // Return top if there are no inputs, and self if there are multiple.
1368 Node* PhiNode::unique_input(PhaseTransform* phase, bool uncast) {
1369 // 1) One unique direct input,
1370 // or if uncast is true:
1371 // 2) some of the inputs have an intervening ConstraintCast
1372 // 3) an input is a self loop
1373 //
1374 // 1) input or 2) input or 3) input __
1375 // / \ / \ \ / \
1376 // \ / | cast phi cast
1377 // phi \ / / \ /
1378 // phi / --
1379
1380 Node* r = in(0); // RegionNode
1381 if (r == NULL) return in(1); // Already degraded to a Copy
1382 Node* input = NULL; // The unique direct input (maybe uncasted = ConstraintCasts removed)
1383
1384 for (uint i = 1, cnt = req(); i < cnt; ++i) {
1385 Node* rc = r->in(i);
1386 if (rc == NULL || phase->type(rc) == Type::TOP)
1387 continue; // ignore unreachable control path
1388 Node* n = in(i);
1389 if (n == NULL)
1390 continue;
1391 Node* un = n;
1392 if (uncast) {
1393 #ifdef ASSERT
1394 Node* m = un->uncast();
1395 #endif
1396 while (un != NULL && un->req() == 2 && un->is_ConstraintCast()) {
1397 Node* next = un->in(1);
1398 if (phase->type(next)->isa_rawptr() && phase->type(un)->isa_oopptr()) {
1399 // risk exposing raw ptr at safepoint
1400 break;
1401 }
1402 un = next;
1403 }
1404 assert(m == un || un->in(1) == m, "Only expected at CheckCastPP from allocation");
1405 }
1406 if (un == NULL || un == this || phase->type(un) == Type::TOP) {
1407 continue; // ignore if top, or in(i) and "this" are in a data cycle
1408 }
1409 // Check for a unique input (maybe uncasted)
1410 if (input == NULL) {
1411 input = un;
1412 } else if (input != un) {
1413 input = NodeSentinel; // no unique input
1414 }
1415 }
1416 if (input == NULL) {
1417 return phase->C->top(); // no inputs
1418 }
1419
1420 if (input != NodeSentinel) {
1421 return input; // one unique direct input
1422 }
1423
1424 // Nothing.
1425 return NULL;
1426 }
1427
1428 //------------------------------is_x2logic-------------------------------------
1429 // Check for simple convert-to-boolean pattern
1430 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
1431 // Convert Phi to an ConvIB.
1432 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
1433 assert(true_path !=0, "only diamond shape graph expected");
1434 // Convert the true/false index into an expected 0/1 return.
1435 // Map 2->0 and 1->1.
1436 int flipped = 2-true_path;
1437
1438 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1439 // phi->region->if_proj->ifnode->bool->cmp
1440 Node *region = phi->in(0);
1441 Node *iff = region->in(1)->in(0);
1442 BoolNode *b = (BoolNode*)iff->in(1);
1443 const CmpNode *cmp = (CmpNode*)b->in(1);
1444
1445 Node *zero = phi->in(1);
1446 Node *one = phi->in(2);
1447 const Type *tzero = phase->type( zero );
1448 const Type *tone = phase->type( one );
1449
1450 // Check for compare vs 0
1451 const Type *tcmp = phase->type(cmp->in(2));
1452 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
1453 // Allow cmp-vs-1 if the other input is bounded by 0-1
1454 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
1455 return NULL;
1456 flipped = 1-flipped; // Test is vs 1 instead of 0!
1457 }
1458
1459 // Check for setting zero/one opposite expected
1460 if( tzero == TypeInt::ZERO ) {
1461 if( tone == TypeInt::ONE ) {
1462 } else return NULL;
1463 } else if( tzero == TypeInt::ONE ) {
1464 if( tone == TypeInt::ZERO ) {
1465 flipped = 1-flipped;
1466 } else return NULL;
1467 } else return NULL;
1468
1469 // Check for boolean test backwards
1470 if( b->_test._test == BoolTest::ne ) {
1471 } else if( b->_test._test == BoolTest::eq ) {
1472 flipped = 1-flipped;
1473 } else return NULL;
1474
1475 // Build int->bool conversion
1476 Node *n = new Conv2BNode(cmp->in(1));
1477 if( flipped )
1478 n = new XorINode( phase->transform(n), phase->intcon(1) );
1479
1480 return n;
1481 }
1482
1483 //------------------------------is_cond_add------------------------------------
1484 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;"
1485 // To be profitable the control flow has to disappear; there can be no other
1486 // values merging here. We replace the test-and-branch with:
1487 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by
1488 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
1489 // Then convert Y to 0-or-Y and finally add.
1490 // This is a key transform for SpecJava _201_compress.
1491 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
1492 assert(true_path !=0, "only diamond shape graph expected");
1493
1494 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1495 // phi->region->if_proj->ifnode->bool->cmp
1496 RegionNode *region = (RegionNode*)phi->in(0);
1497 Node *iff = region->in(1)->in(0);
1498 BoolNode* b = iff->in(1)->as_Bool();
1499 const CmpNode *cmp = (CmpNode*)b->in(1);
1500
1501 // Make sure only merging this one phi here
1502 if (region->has_unique_phi() != phi) return NULL;
1503
1504 // Make sure each arm of the diamond has exactly one output, which we assume
1505 // is the region. Otherwise, the control flow won't disappear.
1506 if (region->in(1)->outcnt() != 1) return NULL;
1507 if (region->in(2)->outcnt() != 1) return NULL;
1508
1509 // Check for "(P < Q)" of type signed int
1510 if (b->_test._test != BoolTest::lt) return NULL;
1511 if (cmp->Opcode() != Op_CmpI) return NULL;
1512
1513 Node *p = cmp->in(1);
1514 Node *q = cmp->in(2);
1515 Node *n1 = phi->in( true_path);
1516 Node *n2 = phi->in(3-true_path);
1517
1518 int op = n1->Opcode();
1519 if( op != Op_AddI // Need zero as additive identity
1520 /*&&op != Op_SubI &&
1521 op != Op_AddP &&
1522 op != Op_XorI &&
1523 op != Op_OrI*/ )
1524 return NULL;
1525
1526 Node *x = n2;
1527 Node *y = NULL;
1528 if( x == n1->in(1) ) {
1529 y = n1->in(2);
1530 } else if( x == n1->in(2) ) {
1531 y = n1->in(1);
1532 } else return NULL;
1533
1534 // Not so profitable if compare and add are constants
1535 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
1536 return NULL;
1537
1538 Node *cmplt = phase->transform( new CmpLTMaskNode(p,q) );
1539 Node *j_and = phase->transform( new AndINode(cmplt,y) );
1540 return new AddINode(j_and,x);
1541 }
1542
1543 //------------------------------is_absolute------------------------------------
1544 // Check for absolute value.
1545 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
1546 assert(true_path !=0, "only diamond shape graph expected");
1547
1548 int cmp_zero_idx = 0; // Index of compare input where to look for zero
1549 int phi_x_idx = 0; // Index of phi input where to find naked x
1550
1551 // ABS ends with the merge of 2 control flow paths.
1552 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
1553 int false_path = 3 - true_path;
1554
1555 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1556 // phi->region->if_proj->ifnode->bool->cmp
1557 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
1558 Node *cmp = bol->in(1);
1559
1560 // Check bool sense
1561 if (cmp->Opcode() == Op_CmpF || cmp->Opcode() == Op_CmpD) {
1562 switch (bol->_test._test) {
1563 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break;
1564 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1565 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1566 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
1567 default: return NULL; break;
1568 }
1569 } else if (cmp->Opcode() == Op_CmpI || cmp->Opcode() == Op_CmpL) {
1570 switch (bol->_test._test) {
1571 case BoolTest::lt:
1572 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1573 case BoolTest::gt:
1574 case BoolTest::ge: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1575 default: return NULL; break;
1576 }
1577 }
1578
1579 // Test is next
1580 const Type *tzero = NULL;
1581 switch (cmp->Opcode()) {
1582 case Op_CmpI: tzero = TypeInt::ZERO; break; // Integer ABS
1583 case Op_CmpL: tzero = TypeLong::ZERO; break; // Long ABS
1584 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS
1585 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS
1586 default: return NULL;
1587 }
1588
1589 // Find zero input of compare; the other input is being abs'd
1590 Node *x = NULL;
1591 bool flip = false;
1592 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
1593 x = cmp->in(3 - cmp_zero_idx);
1594 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
1595 // The test is inverted, we should invert the result...
1596 x = cmp->in(cmp_zero_idx);
1597 flip = true;
1598 } else {
1599 return NULL;
1600 }
1601
1602 // Next get the 2 pieces being selected, one is the original value
1603 // and the other is the negated value.
1604 if( phi_root->in(phi_x_idx) != x ) return NULL;
1605
1606 // Check other phi input for subtract node
1607 Node *sub = phi_root->in(3 - phi_x_idx);
1608
1609 bool is_sub = sub->Opcode() == Op_SubF || sub->Opcode() == Op_SubD ||
1610 sub->Opcode() == Op_SubI || sub->Opcode() == Op_SubL;
1611
1612 // Allow only Sub(0,X) and fail out for all others; Neg is not OK
1613 if (!is_sub || phase->type(sub->in(1)) != tzero || sub->in(2) != x) return NULL;
1614
1615 if (tzero == TypeF::ZERO) {
1616 x = new AbsFNode(x);
1617 if (flip) {
1618 x = new SubFNode(sub->in(1), phase->transform(x));
1619 }
1620 } else if (tzero == TypeD::ZERO) {
1621 x = new AbsDNode(x);
1622 if (flip) {
1623 x = new SubDNode(sub->in(1), phase->transform(x));
1624 }
1625 } else if (tzero == TypeInt::ZERO && Matcher::match_rule_supported(Op_AbsI)) {
1626 x = new AbsINode(x);
1627 if (flip) {
1628 x = new SubINode(sub->in(1), phase->transform(x));
1629 }
1630 } else if (tzero == TypeLong::ZERO && Matcher::match_rule_supported(Op_AbsL)) {
1631 x = new AbsLNode(x);
1632 if (flip) {
1633 x = new SubLNode(sub->in(1), phase->transform(x));
1634 }
1635 } else return NULL;
1636
1637 return x;
1638 }
1639
1640 //------------------------------split_once-------------------------------------
1641 // Helper for split_flow_path
1642 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
1643 igvn->hash_delete(n); // Remove from hash before hacking edges
1644
1645 uint j = 1;
1646 for (uint i = phi->req()-1; i > 0; i--) {
1647 if (phi->in(i) == val) { // Found a path with val?
1648 // Add to NEW Region/Phi, no DU info
1649 newn->set_req( j++, n->in(i) );
1650 // Remove from OLD Region/Phi
1651 n->del_req(i);
1652 }
1653 }
1654
1655 // Register the new node but do not transform it. Cannot transform until the
1656 // entire Region/Phi conglomerate has been hacked as a single huge transform.
1657 igvn->register_new_node_with_optimizer( newn );
1658
1659 // Now I can point to the new node.
1660 n->add_req(newn);
1661 igvn->_worklist.push(n);
1662 }
1663
1664 //------------------------------split_flow_path--------------------------------
1665 // Check for merging identical values and split flow paths
1666 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) {
1667 BasicType bt = phi->type()->basic_type();
1668 if( bt == T_ILLEGAL || type2size[bt] <= 0 )
1669 return NULL; // Bail out on funny non-value stuff
1670 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a
1671 return NULL; // third unequal input to be worth doing
1672
1673 // Scan for a constant
1674 uint i;
1675 for( i = 1; i < phi->req()-1; i++ ) {
1676 Node *n = phi->in(i);
1677 if( !n ) return NULL;
1678 if( phase->type(n) == Type::TOP ) return NULL;
1679 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN || n->Opcode() == Op_ConNKlass )
1680 break;
1681 }
1682 if( i >= phi->req() ) // Only split for constants
1683 return NULL;
1684
1685 Node *val = phi->in(i); // Constant to split for
1686 uint hit = 0; // Number of times it occurs
1687 Node *r = phi->region();
1688
1689 for( ; i < phi->req(); i++ ){ // Count occurrences of constant
1690 Node *n = phi->in(i);
1691 if( !n ) return NULL;
1692 if( phase->type(n) == Type::TOP ) return NULL;
1693 if( phi->in(i) == val ) {
1694 hit++;
1695 if (PhaseIdealLoop::find_predicate(r->in(i)) != NULL) {
1696 return NULL; // don't split loop entry path
1697 }
1698 }
1699 }
1700
1701 if( hit <= 1 || // Make sure we find 2 or more
1702 hit == phi->req()-1 ) // and not ALL the same value
1703 return NULL;
1704
1705 // Now start splitting out the flow paths that merge the same value.
1706 // Split first the RegionNode.
1707 PhaseIterGVN *igvn = phase->is_IterGVN();
1708 RegionNode *newr = new RegionNode(hit+1);
1709 split_once(igvn, phi, val, r, newr);
1710
1711 // Now split all other Phis than this one
1712 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) {
1713 Node* phi2 = r->fast_out(k);
1714 if( phi2->is_Phi() && phi2->as_Phi() != phi ) {
1715 PhiNode *newphi = PhiNode::make_blank(newr, phi2);
1716 split_once(igvn, phi, val, phi2, newphi);
1717 }
1718 }
1719
1720 // Clean up this guy
1721 igvn->hash_delete(phi);
1722 for( i = phi->req()-1; i > 0; i-- ) {
1723 if( phi->in(i) == val ) {
1724 phi->del_req(i);
1725 }
1726 }
1727 phi->add_req(val);
1728
1729 return phi;
1730 }
1731
1732 //=============================================================================
1733 //------------------------------simple_data_loop_check-------------------------
1734 // Try to determining if the phi node in a simple safe/unsafe data loop.
1735 // Returns:
1736 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
1737 // Safe - safe case when the phi and it's inputs reference only safe data
1738 // nodes;
1739 // Unsafe - the phi and it's inputs reference unsafe data nodes but there
1740 // is no reference back to the phi - need a graph walk
1741 // to determine if it is in a loop;
1742 // UnsafeLoop - unsafe case when the phi references itself directly or through
1743 // unsafe data node.
1744 // Note: a safe data node is a node which could/never reference itself during
1745 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP.
1746 // I mark Phi nodes as safe node not only because they can reference itself
1747 // but also to prevent mistaking the fallthrough case inside an outer loop
1748 // as dead loop when the phi references itselfs through an other phi.
1749 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const {
1750 // It is unsafe loop if the phi node references itself directly.
1751 if (in == (Node*)this)
1752 return UnsafeLoop; // Unsafe loop
1753 // Unsafe loop if the phi node references itself through an unsafe data node.
1754 // Exclude cases with null inputs or data nodes which could reference
1755 // itself (safe for dead loops).
1756 if (in != NULL && !in->is_dead_loop_safe()) {
1757 // Check inputs of phi's inputs also.
1758 // It is much less expensive then full graph walk.
1759 uint cnt = in->req();
1760 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1;
1761 for (; i < cnt; ++i) {
1762 Node* m = in->in(i);
1763 if (m == (Node*)this)
1764 return UnsafeLoop; // Unsafe loop
1765 if (m != NULL && !m->is_dead_loop_safe()) {
1766 // Check the most common case (about 30% of all cases):
1767 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con).
1768 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL;
1769 if (m1 == (Node*)this)
1770 return UnsafeLoop; // Unsafe loop
1771 if (m1 != NULL && m1 == m->in(2) &&
1772 m1->is_dead_loop_safe() && m->in(3)->is_Con()) {
1773 continue; // Safe case
1774 }
1775 // The phi references an unsafe node - need full analysis.
1776 return Unsafe;
1777 }
1778 }
1779 }
1780 return Safe; // Safe case - we can optimize the phi node.
1781 }
1782
1783 //------------------------------is_unsafe_data_reference-----------------------
1784 // If phi can be reached through the data input - it is data loop.
1785 bool PhiNode::is_unsafe_data_reference(Node *in) const {
1786 assert(req() > 1, "");
1787 // First, check simple cases when phi references itself directly or
1788 // through an other node.
1789 LoopSafety safety = simple_data_loop_check(in);
1790 if (safety == UnsafeLoop)
1791 return true; // phi references itself - unsafe loop
1792 else if (safety == Safe)
1793 return false; // Safe case - phi could be replaced with the unique input.
1794
1795 // Unsafe case when we should go through data graph to determine
1796 // if the phi references itself.
1797
1798 ResourceMark rm;
1799
1800 Node_List nstack;
1801 VectorSet visited;
1802
1803 nstack.push(in); // Start with unique input.
1804 visited.set(in->_idx);
1805 while (nstack.size() != 0) {
1806 Node* n = nstack.pop();
1807 uint cnt = n->req();
1808 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1;
1809 for (; i < cnt; i++) {
1810 Node* m = n->in(i);
1811 if (m == (Node*)this) {
1812 return true; // Data loop
1813 }
1814 if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases.
1815 if (!visited.test_set(m->_idx))
1816 nstack.push(m);
1817 }
1818 }
1819 }
1820 return false; // The phi is not reachable from its inputs
1821 }
1822
1823 // Is this Phi's region or some inputs to the region enqueued for IGVN
1824 // and so could cause the region to be optimized out?
1825 bool PhiNode::wait_for_region_igvn(PhaseGVN* phase) {
1826 PhaseIterGVN* igvn = phase->is_IterGVN();
1827 Unique_Node_List& worklist = igvn->_worklist;
1828 bool delay = false;
1829 Node* r = in(0);
1830 for (uint j = 1; j < req(); j++) {
1831 Node* rc = r->in(j);
1832 Node* n = in(j);
1833 if (rc != NULL &&
1834 rc->is_Proj()) {
1835 if (worklist.member(rc)) {
1836 delay = true;
1837 } else if (rc->in(0) != NULL &&
1838 rc->in(0)->is_If()) {
1839 if (worklist.member(rc->in(0))) {
1840 delay = true;
1841 } else if (rc->in(0)->in(1) != NULL &&
1842 rc->in(0)->in(1)->is_Bool()) {
1843 if (worklist.member(rc->in(0)->in(1))) {
1844 delay = true;
1845 } else if (rc->in(0)->in(1)->in(1) != NULL &&
1846 rc->in(0)->in(1)->in(1)->is_Cmp()) {
1847 if (worklist.member(rc->in(0)->in(1)->in(1))) {
1848 delay = true;
1849 }
1850 }
1851 }
1852 }
1853 }
1854 }
1855 if (delay) {
1856 worklist.push(this);
1857 }
1858 return delay;
1859 }
1860
1861 //------------------------------Ideal------------------------------------------
1862 // Return a node which is more "ideal" than the current node. Must preserve
1863 // the CFG, but we can still strip out dead paths.
1864 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1865 // The next should never happen after 6297035 fix.
1866 if( is_copy() ) // Already degraded to a Copy ?
1867 return NULL; // No change
1868
1869 Node *r = in(0); // RegionNode
1870 assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge");
1871
1872 // Note: During parsing, phis are often transformed before their regions.
1873 // This means we have to use type_or_null to defend against untyped regions.
1874 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1875 return NULL; // No change
1876
1877 Node *top = phase->C->top();
1878 bool new_phi = (outcnt() == 0); // transforming new Phi
1879 // No change for igvn if new phi is not hooked
1880 if (new_phi && can_reshape)
1881 return NULL;
1882
1883 // The are 2 situations when only one valid phi's input is left
1884 // (in addition to Region input).
1885 // One: region is not loop - replace phi with this input.
1886 // Two: region is loop - replace phi with top since this data path is dead
1887 // and we need to break the dead data loop.
1888 Node* progress = NULL; // Record if any progress made
1889 for( uint j = 1; j < req(); ++j ){ // For all paths in
1890 // Check unreachable control paths
1891 Node* rc = r->in(j);
1892 Node* n = in(j); // Get the input
1893 if (rc == NULL || phase->type(rc) == Type::TOP) {
1894 if (n != top) { // Not already top?
1895 PhaseIterGVN *igvn = phase->is_IterGVN();
1896 if (can_reshape && igvn != NULL) {
1897 igvn->_worklist.push(r);
1898 }
1899 // Nuke it down
1900 if (can_reshape) {
1901 set_req_X(j, top, igvn);
1902 } else {
1903 set_req(j, top);
1904 }
1905 progress = this; // Record progress
1906 }
1907 }
1908 }
1909
1910 if (can_reshape && outcnt() == 0) {
1911 // set_req() above may kill outputs if Phi is referenced
1912 // only by itself on the dead (top) control path.
1913 return top;
1914 }
1915
1916 bool uncasted = false;
1917 Node* uin = unique_input(phase, false);
1918 if (uin == NULL && can_reshape &&
1919 // If there is a chance that the region can be optimized out do
1920 // not add a cast node that we can't remove yet.
1921 !wait_for_region_igvn(phase)) {
1922 uncasted = true;
1923 uin = unique_input(phase, true);
1924 }
1925 if (uin == top) { // Simplest case: no alive inputs.
1926 if (can_reshape) // IGVN transformation
1927 return top;
1928 else
1929 return NULL; // Identity will return TOP
1930 } else if (uin != NULL) {
1931 // Only one not-NULL unique input path is left.
1932 // Determine if this input is backedge of a loop.
1933 // (Skip new phis which have no uses and dead regions).
1934 if (outcnt() > 0 && r->in(0) != NULL) {
1935 // First, take the short cut when we know it is a loop and
1936 // the EntryControl data path is dead.
1937 // Loop node may have only one input because entry path
1938 // is removed in PhaseIdealLoop::Dominators().
1939 assert(!r->is_Loop() || r->req() <= 3, "Loop node should have 3 or less inputs");
1940 bool is_loop = (r->is_Loop() && r->req() == 3);
1941 // Then, check if there is a data loop when phi references itself directly
1942 // or through other data nodes.
1943 if ((is_loop && !uin->eqv_uncast(in(LoopNode::EntryControl))) ||
1944 (!is_loop && is_unsafe_data_reference(uin))) {
1945 // Break this data loop to avoid creation of a dead loop.
1946 if (can_reshape) {
1947 return top;
1948 } else {
1949 // We can't return top if we are in Parse phase - cut inputs only
1950 // let Identity to handle the case.
1951 replace_edge(uin, top);
1952 return NULL;
1953 }
1954 }
1955 }
1956
1957 if (uncasted) {
1958 // Add cast nodes between the phi to be removed and its unique input.
1959 // Wait until after parsing for the type information to propagate from the casts.
1960 assert(can_reshape, "Invalid during parsing");
1961 const Type* phi_type = bottom_type();
1962 assert(phi_type->isa_int() || phi_type->isa_ptr(), "bad phi type");
1963 // Add casts to carry the control dependency of the Phi that is
1964 // going away
1965 Node* cast = NULL;
1966 if (phi_type->isa_int()) {
1967 cast = ConstraintCastNode::make_cast(Op_CastII, r, uin, phi_type, true);
1968 } else {
1969 const Type* uin_type = phase->type(uin);
1970 if (!phi_type->isa_oopptr() && !uin_type->isa_oopptr()) {
1971 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true);
1972 } else {
1973 // Use a CastPP for a cast to not null and a CheckCastPP for
1974 // a cast to a new klass (and both if both null-ness and
1975 // klass change).
1976
1977 // If the type of phi is not null but the type of uin may be
1978 // null, uin's type must be casted to not null
1979 if (phi_type->join(TypePtr::NOTNULL) == phi_type->remove_speculative() &&
1980 uin_type->join(TypePtr::NOTNULL) != uin_type->remove_speculative()) {
1981 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, TypePtr::NOTNULL, true);
1982 }
1983
1984 // If the type of phi and uin, both casted to not null,
1985 // differ the klass of uin must be (check)cast'ed to match
1986 // that of phi
1987 if (phi_type->join_speculative(TypePtr::NOTNULL) != uin_type->join_speculative(TypePtr::NOTNULL)) {
1988 Node* n = uin;
1989 if (cast != NULL) {
1990 cast = phase->transform(cast);
1991 n = cast;
1992 }
1993 cast = ConstraintCastNode::make_cast(Op_CheckCastPP, r, n, phi_type, true);
1994 }
1995 if (cast == NULL) {
1996 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true);
1997 }
1998 }
1999 }
2000 assert(cast != NULL, "cast should be set");
2001 cast = phase->transform(cast);
2002 // set all inputs to the new cast(s) so the Phi is removed by Identity
2003 PhaseIterGVN* igvn = phase->is_IterGVN();
2004 for (uint i = 1; i < req(); i++) {
2005 set_req_X(i, cast, igvn);
2006 }
2007 uin = cast;
2008 }
2009
2010 // One unique input.
2011 debug_only(Node* ident = Identity(phase));
2012 // The unique input must eventually be detected by the Identity call.
2013 #ifdef ASSERT
2014 if (ident != uin && !ident->is_top()) {
2015 // print this output before failing assert
2016 r->dump(3);
2017 this->dump(3);
2018 ident->dump();
2019 uin->dump();
2020 }
2021 #endif
2022 assert(ident == uin || ident->is_top(), "Identity must clean this up");
2023 return NULL;
2024 }
2025
2026 Node* opt = NULL;
2027 int true_path = is_diamond_phi();
2028 if( true_path != 0 ) {
2029 // Check for CMove'ing identity. If it would be unsafe,
2030 // handle it here. In the safe case, let Identity handle it.
2031 Node* unsafe_id = is_cmove_id(phase, true_path);
2032 if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) )
2033 opt = unsafe_id;
2034
2035 // Check for simple convert-to-boolean pattern
2036 if( opt == NULL )
2037 opt = is_x2logic(phase, this, true_path);
2038
2039 // Check for absolute value
2040 if( opt == NULL )
2041 opt = is_absolute(phase, this, true_path);
2042
2043 // Check for conditional add
2044 if( opt == NULL && can_reshape )
2045 opt = is_cond_add(phase, this, true_path);
2046
2047 // These 4 optimizations could subsume the phi:
2048 // have to check for a dead data loop creation.
2049 if( opt != NULL ) {
2050 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) {
2051 // Found dead loop.
2052 if( can_reshape )
2053 return top;
2054 // We can't return top if we are in Parse phase - cut inputs only
2055 // to stop further optimizations for this phi. Identity will return TOP.
2056 assert(req() == 3, "only diamond merge phi here");
2057 set_req(1, top);
2058 set_req(2, top);
2059 return NULL;
2060 } else {
2061 return opt;
2062 }
2063 }
2064 }
2065
2066 // Check for merging identical values and split flow paths
2067 if (can_reshape) {
2068 opt = split_flow_path(phase, this);
2069 // This optimization only modifies phi - don't need to check for dead loop.
2070 assert(opt == NULL || phase->eqv(opt, this), "do not elide phi");
2071 if (opt != NULL) return opt;
2072 }
2073
2074 if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) {
2075 // Try to undo Phi of AddP:
2076 // (Phi (AddP base address offset) (AddP base2 address2 offset2))
2077 // becomes:
2078 // newbase := (Phi base base2)
2079 // newaddress := (Phi address address2)
2080 // newoffset := (Phi offset offset2)
2081 // (AddP newbase newaddress newoffset)
2082 //
2083 // This occurs as a result of unsuccessful split_thru_phi and
2084 // interferes with taking advantage of addressing modes. See the
2085 // clone_shift_expressions code in matcher.cpp
2086 Node* addp = in(1);
2087 Node* base = addp->in(AddPNode::Base);
2088 Node* address = addp->in(AddPNode::Address);
2089 Node* offset = addp->in(AddPNode::Offset);
2090 if (base != NULL && address != NULL && offset != NULL &&
2091 !base->is_top() && !address->is_top() && !offset->is_top()) {
2092 const Type* base_type = base->bottom_type();
2093 const Type* address_type = address->bottom_type();
2094 // make sure that all the inputs are similar to the first one,
2095 // i.e. AddP with base == address and same offset as first AddP
2096 bool doit = true;
2097 for (uint i = 2; i < req(); i++) {
2098 if (in(i) == NULL ||
2099 in(i)->Opcode() != Op_AddP ||
2100 in(i)->in(AddPNode::Base) == NULL ||
2101 in(i)->in(AddPNode::Address) == NULL ||
2102 in(i)->in(AddPNode::Offset) == NULL ||
2103 in(i)->in(AddPNode::Base)->is_top() ||
2104 in(i)->in(AddPNode::Address)->is_top() ||
2105 in(i)->in(AddPNode::Offset)->is_top()) {
2106 doit = false;
2107 break;
2108 }
2109 if (in(i)->in(AddPNode::Offset) != base) {
2110 base = NULL;
2111 }
2112 if (in(i)->in(AddPNode::Offset) != offset) {
2113 offset = NULL;
2114 }
2115 if (in(i)->in(AddPNode::Address) != address) {
2116 address = NULL;
2117 }
2118 // Accumulate type for resulting Phi
2119 base_type = base_type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type());
2120 address_type = address_type->meet_speculative(in(i)->in(AddPNode::Address)->bottom_type());
2121 }
2122 if (doit && base == NULL) {
2123 // Check for neighboring AddP nodes in a tree.
2124 // If they have a base, use that it.
2125 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) {
2126 Node* u = this->fast_out(k);
2127 if (u->is_AddP()) {
2128 Node* base2 = u->in(AddPNode::Base);
2129 if (base2 != NULL && !base2->is_top()) {
2130 if (base == NULL)
2131 base = base2;
2132 else if (base != base2)
2133 { doit = false; break; }
2134 }
2135 }
2136 }
2137 }
2138 if (doit) {
2139 if (base == NULL) {
2140 base = new PhiNode(in(0), base_type, NULL);
2141 for (uint i = 1; i < req(); i++) {
2142 base->init_req(i, in(i)->in(AddPNode::Base));
2143 }
2144 phase->is_IterGVN()->register_new_node_with_optimizer(base);
2145 }
2146 if (address == NULL) {
2147 address = new PhiNode(in(0), address_type, NULL);
2148 for (uint i = 1; i < req(); i++) {
2149 address->init_req(i, in(i)->in(AddPNode::Address));
2150 }
2151 phase->is_IterGVN()->register_new_node_with_optimizer(address);
2152 }
2153 if (offset == NULL) {
2154 offset = new PhiNode(in(0), TypeX_X, NULL);
2155 for (uint i = 1; i < req(); i++) {
2156 offset->init_req(i, in(i)->in(AddPNode::Offset));
2157 }
2158 phase->is_IterGVN()->register_new_node_with_optimizer(offset);
2159 }
2160 return new AddPNode(base, address, offset);
2161 }
2162 }
2163 }
2164
2165 // Split phis through memory merges, so that the memory merges will go away.
2166 // Piggy-back this transformation on the search for a unique input....
2167 // It will be as if the merged memory is the unique value of the phi.
2168 // (Do not attempt this optimization unless parsing is complete.
2169 // It would make the parser's memory-merge logic sick.)
2170 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.)
2171 if (progress == NULL && can_reshape && type() == Type::MEMORY) {
2172 // see if this phi should be sliced
2173 uint merge_width = 0;
2174 bool saw_self = false;
2175 for( uint i=1; i<req(); ++i ) {// For all paths in
2176 Node *ii = in(i);
2177 // TOP inputs should not be counted as safe inputs because if the
2178 // Phi references itself through all other inputs then splitting the
2179 // Phi through memory merges would create dead loop at later stage.
2180 if (ii == top) {
2181 return NULL; // Delay optimization until graph is cleaned.
2182 }
2183 if (ii->is_MergeMem()) {
2184 MergeMemNode* n = ii->as_MergeMem();
2185 merge_width = MAX2(merge_width, n->req());
2186 saw_self = saw_self || phase->eqv(n->base_memory(), this);
2187 }
2188 }
2189
2190 // This restriction is temporarily necessary to ensure termination:
2191 if (!saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0;
2192
2193 if (merge_width > Compile::AliasIdxRaw) {
2194 // found at least one non-empty MergeMem
2195 const TypePtr* at = adr_type();
2196 if (at != TypePtr::BOTTOM) {
2197 // Patch the existing phi to select an input from the merge:
2198 // Phi:AT1(...MergeMem(m0, m1, m2)...) into
2199 // Phi:AT1(...m1...)
2200 int alias_idx = phase->C->get_alias_index(at);
2201 for (uint i=1; i<req(); ++i) {
2202 Node *ii = in(i);
2203 if (ii->is_MergeMem()) {
2204 MergeMemNode* n = ii->as_MergeMem();
2205 // compress paths and change unreachable cycles to TOP
2206 // If not, we can update the input infinitely along a MergeMem cycle
2207 // Equivalent code is in MemNode::Ideal_common
2208 Node *m = phase->transform(n);
2209 if (outcnt() == 0) { // Above transform() may kill us!
2210 return top;
2211 }
2212 // If transformed to a MergeMem, get the desired slice
2213 // Otherwise the returned node represents memory for every slice
2214 Node *new_mem = (m->is_MergeMem()) ?
2215 m->as_MergeMem()->memory_at(alias_idx) : m;
2216 // Update input if it is progress over what we have now
2217 if (new_mem != ii) {
2218 set_req(i, new_mem);
2219 progress = this;
2220 }
2221 }
2222 }
2223 } else {
2224 // We know that at least one MergeMem->base_memory() == this
2225 // (saw_self == true). If all other inputs also references this phi
2226 // (directly or through data nodes) - it is a dead loop.
2227 bool saw_safe_input = false;
2228 for (uint j = 1; j < req(); ++j) {
2229 Node* n = in(j);
2230 if (n->is_MergeMem()) {
2231 MergeMemNode* mm = n->as_MergeMem();
2232 if (mm->base_memory() == this || mm->base_memory() == mm->empty_memory()) {
2233 // Skip this input if it references back to this phi or if the memory path is dead
2234 continue;
2235 }
2236 }
2237 if (!is_unsafe_data_reference(n)) {
2238 saw_safe_input = true; // found safe input
2239 break;
2240 }
2241 }
2242 if (!saw_safe_input) {
2243 // There is a dead loop: All inputs are either dead or reference back to this phi
2244 return top;
2245 }
2246
2247 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into
2248 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...))
2249 PhaseIterGVN* igvn = phase->is_IterGVN();
2250 Node* hook = new Node(1);
2251 PhiNode* new_base = (PhiNode*) clone();
2252 // Must eagerly register phis, since they participate in loops.
2253 if (igvn) {
2254 igvn->register_new_node_with_optimizer(new_base);
2255 hook->add_req(new_base);
2256 }
2257 MergeMemNode* result = MergeMemNode::make(new_base);
2258 for (uint i = 1; i < req(); ++i) {
2259 Node *ii = in(i);
2260 if (ii->is_MergeMem()) {
2261 MergeMemNode* n = ii->as_MergeMem();
2262 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) {
2263 // If we have not seen this slice yet, make a phi for it.
2264 bool made_new_phi = false;
2265 if (mms.is_empty()) {
2266 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C));
2267 made_new_phi = true;
2268 if (igvn) {
2269 igvn->register_new_node_with_optimizer(new_phi);
2270 hook->add_req(new_phi);
2271 }
2272 mms.set_memory(new_phi);
2273 }
2274 Node* phi = mms.memory();
2275 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice");
2276 phi->set_req(i, mms.memory2());
2277 }
2278 }
2279 }
2280 // Distribute all self-loops.
2281 { // (Extra braces to hide mms.)
2282 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2283 Node* phi = mms.memory();
2284 for (uint i = 1; i < req(); ++i) {
2285 if (phi->in(i) == this) phi->set_req(i, phi);
2286 }
2287 }
2288 }
2289 // now transform the new nodes, and return the mergemem
2290 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2291 Node* phi = mms.memory();
2292 mms.set_memory(phase->transform(phi));
2293 }
2294 if (igvn) { // Unhook.
2295 igvn->hash_delete(hook);
2296 for (uint i = 1; i < hook->req(); i++) {
2297 hook->set_req(i, NULL);
2298 }
2299 }
2300 // Replace self with the result.
2301 return result;
2302 }
2303 }
2304 //
2305 // Other optimizations on the memory chain
2306 //
2307 const TypePtr* at = adr_type();
2308 for( uint i=1; i<req(); ++i ) {// For all paths in
2309 Node *ii = in(i);
2310 Node *new_in = MemNode::optimize_memory_chain(ii, at, NULL, phase);
2311 if (ii != new_in ) {
2312 set_req(i, new_in);
2313 progress = this;
2314 }
2315 }
2316 }
2317
2318 #ifdef _LP64
2319 // Push DecodeN/DecodeNKlass down through phi.
2320 // The rest of phi graph will transform by split EncodeP node though phis up.
2321 if ((UseCompressedOops || UseCompressedClassPointers) && can_reshape && progress == NULL) {
2322 bool may_push = true;
2323 bool has_decodeN = false;
2324 bool is_decodeN = false;
2325 for (uint i=1; i<req(); ++i) {// For all paths in
2326 Node *ii = in(i);
2327 if (ii->is_DecodeNarrowPtr() && ii->bottom_type() == bottom_type()) {
2328 // Do optimization if a non dead path exist.
2329 if (ii->in(1)->bottom_type() != Type::TOP) {
2330 has_decodeN = true;
2331 is_decodeN = ii->is_DecodeN();
2332 }
2333 } else if (!ii->is_Phi()) {
2334 may_push = false;
2335 }
2336 }
2337
2338 if (has_decodeN && may_push) {
2339 PhaseIterGVN *igvn = phase->is_IterGVN();
2340 // Make narrow type for new phi.
2341 const Type* narrow_t;
2342 if (is_decodeN) {
2343 narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr());
2344 } else {
2345 narrow_t = TypeNarrowKlass::make(this->bottom_type()->is_ptr());
2346 }
2347 PhiNode* new_phi = new PhiNode(r, narrow_t);
2348 uint orig_cnt = req();
2349 for (uint i=1; i<req(); ++i) {// For all paths in
2350 Node *ii = in(i);
2351 Node* new_ii = NULL;
2352 if (ii->is_DecodeNarrowPtr()) {
2353 assert(ii->bottom_type() == bottom_type(), "sanity");
2354 new_ii = ii->in(1);
2355 } else {
2356 assert(ii->is_Phi(), "sanity");
2357 if (ii->as_Phi() == this) {
2358 new_ii = new_phi;
2359 } else {
2360 if (is_decodeN) {
2361 new_ii = new EncodePNode(ii, narrow_t);
2362 } else {
2363 new_ii = new EncodePKlassNode(ii, narrow_t);
2364 }
2365 igvn->register_new_node_with_optimizer(new_ii);
2366 }
2367 }
2368 new_phi->set_req(i, new_ii);
2369 }
2370 igvn->register_new_node_with_optimizer(new_phi, this);
2371 if (is_decodeN) {
2372 progress = new DecodeNNode(new_phi, bottom_type());
2373 } else {
2374 progress = new DecodeNKlassNode(new_phi, bottom_type());
2375 }
2376 }
2377 }
2378 #endif
2379
2380 // Phi (VB ... VB) => VB (Phi ...) (Phi ...)
2381 if (EnableVectorReboxing && can_reshape && progress == NULL) {
2382 PhaseIterGVN* igvn = phase->is_IterGVN();
2383
2384 bool all_inputs_are_equiv_vboxes = true;
2385 for (uint i = 1; i < req(); ++i) {
2386 Node* n = in(i);
2387 if (in(i)->Opcode() != Op_VectorBox) {
2388 all_inputs_are_equiv_vboxes = false;
2389 break;
2390 }
2391 // Check that vector type of vboxes is equivalent
2392 if (i != 1) {
2393 if (Type::cmp(in(i-0)->in(VectorBoxNode::Value)->bottom_type(),
2394 in(i-1)->in(VectorBoxNode::Value)->bottom_type()) != 0) {
2395 all_inputs_are_equiv_vboxes = false;
2396 break;
2397 }
2398 if (Type::cmp(in(i-0)->in(VectorBoxNode::Box)->bottom_type(),
2399 in(i-1)->in(VectorBoxNode::Box)->bottom_type()) != 0) {
2400 all_inputs_are_equiv_vboxes = false;
2401 break;
2402 }
2403 }
2404 }
2405
2406 if (all_inputs_are_equiv_vboxes) {
2407 VectorBoxNode* vbox = static_cast<VectorBoxNode*>(in(1));
2408 PhiNode* new_vbox_phi = new PhiNode(r, vbox->box_type());
2409 PhiNode* new_vect_phi = new PhiNode(r, vbox->vec_type());
2410 for (uint i = 1; i < req(); ++i) {
2411 VectorBoxNode* old_vbox = static_cast<VectorBoxNode*>(in(i));
2412 new_vbox_phi->set_req(i, old_vbox->in(VectorBoxNode::Box));
2413 new_vect_phi->set_req(i, old_vbox->in(VectorBoxNode::Value));
2414 }
2415 igvn->register_new_node_with_optimizer(new_vbox_phi, this);
2416 igvn->register_new_node_with_optimizer(new_vect_phi, this);
2417 progress = new VectorBoxNode(igvn->C, new_vbox_phi, new_vect_phi, vbox->box_type(), vbox->vec_type());
2418 }
2419 }
2420
2421 return progress; // Return any progress
2422 }
2423
2424 //------------------------------is_tripcount-----------------------------------
2425 bool PhiNode::is_tripcount() const {
2426 return (in(0) != NULL && in(0)->is_CountedLoop() &&
2427 in(0)->as_CountedLoop()->phi() == this);
2428 }
2429
2430 //------------------------------out_RegMask------------------------------------
2431 const RegMask &PhiNode::in_RegMask(uint i) const {
2432 return i ? out_RegMask() : RegMask::Empty;
2433 }
2434
2435 const RegMask &PhiNode::out_RegMask() const {
2436 uint ideal_reg = _type->ideal_reg();
2437 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
2438 if( ideal_reg == 0 ) return RegMask::Empty;
2439 assert(ideal_reg != Op_RegFlags, "flags register is not spillable");
2440 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
2441 }
2442
2443 #ifndef PRODUCT
2444 void PhiNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2445 // For a PhiNode, the set of related nodes includes all inputs till level 2,
2446 // and all outputs till level 1. In compact mode, inputs till level 1 are
2447 // collected.
2448 this->collect_nodes(in_rel, compact ? 1 : 2, false, false);
2449 this->collect_nodes(out_rel, -1, false, false);
2450 }
2451
2452 void PhiNode::dump_spec(outputStream *st) const {
2453 TypeNode::dump_spec(st);
2454 if (is_tripcount()) {
2455 st->print(" #tripcount");
2456 }
2457 }
2458 #endif
2459
2460
2461 //=============================================================================
2462 const Type* GotoNode::Value(PhaseGVN* phase) const {
2463 // If the input is reachable, then we are executed.
2464 // If the input is not reachable, then we are not executed.
2465 return phase->type(in(0));
2466 }
2467
2468 Node* GotoNode::Identity(PhaseGVN* phase) {
2469 return in(0); // Simple copy of incoming control
2470 }
2471
2472 const RegMask &GotoNode::out_RegMask() const {
2473 return RegMask::Empty;
2474 }
2475
2476 #ifndef PRODUCT
2477 //-----------------------------related-----------------------------------------
2478 // The related nodes of a GotoNode are all inputs at level 1, as well as the
2479 // outputs at level 1. This is regardless of compact mode.
2480 void GotoNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2481 this->collect_nodes(in_rel, 1, false, false);
2482 this->collect_nodes(out_rel, -1, false, false);
2483 }
2484 #endif
2485
2486
2487 //=============================================================================
2488 const RegMask &JumpNode::out_RegMask() const {
2489 return RegMask::Empty;
2490 }
2491
2492 #ifndef PRODUCT
2493 //-----------------------------related-----------------------------------------
2494 // The related nodes of a JumpNode are all inputs at level 1, as well as the
2495 // outputs at level 2 (to include actual jump targets beyond projection nodes).
2496 // This is regardless of compact mode.
2497 void JumpNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2498 this->collect_nodes(in_rel, 1, false, false);
2499 this->collect_nodes(out_rel, -2, false, false);
2500 }
2501 #endif
2502
2503 //=============================================================================
2504 const RegMask &JProjNode::out_RegMask() const {
2505 return RegMask::Empty;
2506 }
2507
2508 //=============================================================================
2509 const RegMask &CProjNode::out_RegMask() const {
2510 return RegMask::Empty;
2511 }
2512
2513
2514
2515 //=============================================================================
2516
2517 uint PCTableNode::hash() const { return Node::hash() + _size; }
2518 bool PCTableNode::cmp( const Node &n ) const
2519 { return _size == ((PCTableNode&)n)._size; }
2520
2521 const Type *PCTableNode::bottom_type() const {
2522 const Type** f = TypeTuple::fields(_size);
2523 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2524 return TypeTuple::make(_size, f);
2525 }
2526
2527 //------------------------------Value------------------------------------------
2528 // Compute the type of the PCTableNode. If reachable it is a tuple of
2529 // Control, otherwise the table targets are not reachable
2530 const Type* PCTableNode::Value(PhaseGVN* phase) const {
2531 if( phase->type(in(0)) == Type::CONTROL )
2532 return bottom_type();
2533 return Type::TOP; // All paths dead? Then so are we
2534 }
2535
2536 //------------------------------Ideal------------------------------------------
2537 // Return a node which is more "ideal" than the current node. Strip out
2538 // control copies
2539 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2540 return remove_dead_region(phase, can_reshape) ? this : NULL;
2541 }
2542
2543 //=============================================================================
2544 uint JumpProjNode::hash() const {
2545 return Node::hash() + _dest_bci;
2546 }
2547
2548 bool JumpProjNode::cmp( const Node &n ) const {
2549 return ProjNode::cmp(n) &&
2550 _dest_bci == ((JumpProjNode&)n)._dest_bci;
2551 }
2552
2553 #ifndef PRODUCT
2554 void JumpProjNode::dump_spec(outputStream *st) const {
2555 ProjNode::dump_spec(st);
2556 st->print("@bci %d ",_dest_bci);
2557 }
2558
2559 void JumpProjNode::dump_compact_spec(outputStream *st) const {
2560 ProjNode::dump_compact_spec(st);
2561 st->print("(%d)%d@%d", _switch_val, _proj_no, _dest_bci);
2562 }
2563
2564 void JumpProjNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2565 // The related nodes of a JumpProjNode are its inputs and outputs at level 1.
2566 this->collect_nodes(in_rel, 1, false, false);
2567 this->collect_nodes(out_rel, -1, false, false);
2568 }
2569 #endif
2570
2571 //=============================================================================
2572 //------------------------------Value------------------------------------------
2573 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot
2574 // have the default "fall_through_index" path.
2575 const Type* CatchNode::Value(PhaseGVN* phase) const {
2576 // Unreachable? Then so are all paths from here.
2577 if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
2578 // First assume all paths are reachable
2579 const Type** f = TypeTuple::fields(_size);
2580 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2581 // Identify cases that will always throw an exception
2582 // () rethrow call
2583 // () virtual or interface call with NULL receiver
2584 // () call is a check cast with incompatible arguments
2585 if( in(1)->is_Proj() ) {
2586 Node *i10 = in(1)->in(0);
2587 if( i10->is_Call() ) {
2588 CallNode *call = i10->as_Call();
2589 // Rethrows always throw exceptions, never return
2590 if (call->entry_point() == OptoRuntime::rethrow_stub()) {
2591 f[CatchProjNode::fall_through_index] = Type::TOP;
2592 } else if( call->req() > TypeFunc::Parms ) {
2593 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) );
2594 // Check for null receiver to virtual or interface calls
2595 if( call->is_CallDynamicJava() &&
2596 arg0->higher_equal(TypePtr::NULL_PTR) ) {
2597 f[CatchProjNode::fall_through_index] = Type::TOP;
2598 }
2599 } // End of if not a runtime stub
2600 } // End of if have call above me
2601 } // End of slot 1 is not a projection
2602 return TypeTuple::make(_size, f);
2603 }
2604
2605 //=============================================================================
2606 uint CatchProjNode::hash() const {
2607 return Node::hash() + _handler_bci;
2608 }
2609
2610
2611 bool CatchProjNode::cmp( const Node &n ) const {
2612 return ProjNode::cmp(n) &&
2613 _handler_bci == ((CatchProjNode&)n)._handler_bci;
2614 }
2615
2616
2617 //------------------------------Identity---------------------------------------
2618 // If only 1 target is possible, choose it if it is the main control
2619 Node* CatchProjNode::Identity(PhaseGVN* phase) {
2620 // If my value is control and no other value is, then treat as ID
2621 const TypeTuple *t = phase->type(in(0))->is_tuple();
2622 if (t->field_at(_con) != Type::CONTROL) return this;
2623 // If we remove the last CatchProj and elide the Catch/CatchProj, then we
2624 // also remove any exception table entry. Thus we must know the call
2625 // feeding the Catch will not really throw an exception. This is ok for
2626 // the main fall-thru control (happens when we know a call can never throw
2627 // an exception) or for "rethrow", because a further optimization will
2628 // yank the rethrow (happens when we inline a function that can throw an
2629 // exception and the caller has no handler). Not legal, e.g., for passing
2630 // a NULL receiver to a v-call, or passing bad types to a slow-check-cast.
2631 // These cases MUST throw an exception via the runtime system, so the VM
2632 // will be looking for a table entry.
2633 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode
2634 CallNode *call;
2635 if (_con != TypeFunc::Control && // Bail out if not the main control.
2636 !(proj->is_Proj() && // AND NOT a rethrow
2637 proj->in(0)->is_Call() &&
2638 (call = proj->in(0)->as_Call()) &&
2639 call->entry_point() == OptoRuntime::rethrow_stub()))
2640 return this;
2641
2642 // Search for any other path being control
2643 for (uint i = 0; i < t->cnt(); i++) {
2644 if (i != _con && t->field_at(i) == Type::CONTROL)
2645 return this;
2646 }
2647 // Only my path is possible; I am identity on control to the jump
2648 return in(0)->in(0);
2649 }
2650
2651
2652 #ifndef PRODUCT
2653 void CatchProjNode::dump_spec(outputStream *st) const {
2654 ProjNode::dump_spec(st);
2655 st->print("@bci %d ",_handler_bci);
2656 }
2657 #endif
2658
2659 //=============================================================================
2660 //------------------------------Identity---------------------------------------
2661 // Check for CreateEx being Identity.
2662 Node* CreateExNode::Identity(PhaseGVN* phase) {
2663 if( phase->type(in(1)) == Type::TOP ) return in(1);
2664 if( phase->type(in(0)) == Type::TOP ) return in(0);
2665 // We only come from CatchProj, unless the CatchProj goes away.
2666 // If the CatchProj is optimized away, then we just carry the
2667 // exception oop through.
2668 CallNode *call = in(1)->in(0)->as_Call();
2669
2670 return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) )
2671 ? this
2672 : call->in(TypeFunc::Parms);
2673 }
2674
2675 //=============================================================================
2676 //------------------------------Value------------------------------------------
2677 // Check for being unreachable.
2678 const Type* NeverBranchNode::Value(PhaseGVN* phase) const {
2679 if (!in(0) || in(0)->is_top()) return Type::TOP;
2680 return bottom_type();
2681 }
2682
2683 //------------------------------Ideal------------------------------------------
2684 // Check for no longer being part of a loop
2685 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2686 if (can_reshape && !in(0)->is_Loop()) {
2687 // Dead code elimination can sometimes delete this projection so
2688 // if it's not there, there's nothing to do.
2689 Node* fallthru = proj_out_or_null(0);
2690 if (fallthru != NULL) {
2691 phase->is_IterGVN()->replace_node(fallthru, in(0));
2692 }
2693 return phase->C->top();
2694 }
2695 return NULL;
2696 }
2697
2698 #ifndef PRODUCT
2699 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const {
2700 st->print("%s", Name());
2701 }
2702 #endif