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