1 /*
2 * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "memory/allocation.inline.hpp"
28 #include "oops/objArrayKlass.hpp"
29 #include "opto/addnode.hpp"
30 #include "opto/cfgnode.hpp"
31 #include "opto/connode.hpp"
32 #include "opto/convertnode.hpp"
33 #include "opto/loopnode.hpp"
34 #include "opto/machnode.hpp"
35 #include "opto/movenode.hpp"
36 #include "opto/narrowptrnode.hpp"
37 #include "opto/mulnode.hpp"
38 #include "opto/phaseX.hpp"
39 #include "opto/regmask.hpp"
40 #include "opto/runtime.hpp"
41 #include "opto/subnode.hpp"
42
43 // Portions of code courtesy of Clifford Click
44
45 // Optimization - Graph Style
46
47 //=============================================================================
48 //------------------------------Value------------------------------------------
49 // Compute the type of the RegionNode.
50 const Type *RegionNode::Value( PhaseTransform *phase ) const {
51 for( uint i=1; i<req(); ++i ) { // For all paths in
52 Node *n = in(i); // Get Control source
53 if( !n ) continue; // Missing inputs are TOP
54 if( phase->type(n) == Type::CONTROL )
55 return Type::CONTROL;
56 }
57 return Type::TOP; // All paths dead? Then so are we
58 }
59
60 //------------------------------Identity---------------------------------------
61 // Check for Region being Identity.
62 Node *RegionNode::Identity( PhaseTransform *phase ) {
63 // Cannot have Region be an identity, even if it has only 1 input.
64 // Phi users cannot have their Region input folded away for them,
65 // since they need to select the proper data input
66 return this;
67 }
68
69 //------------------------------merge_region-----------------------------------
70 // If a Region flows into a Region, merge into one big happy merge. This is
71 // hard to do if there is stuff that has to happen
72 static Node *merge_region(RegionNode *region, PhaseGVN *phase) {
73 if( region->Opcode() != Op_Region ) // Do not do to LoopNodes
74 return NULL;
75 Node *progress = NULL; // Progress flag
76 PhaseIterGVN *igvn = phase->is_IterGVN();
77
78 uint rreq = region->req();
79 for( uint i = 1; i < rreq; i++ ) {
80 Node *r = region->in(i);
81 if( r && r->Opcode() == Op_Region && // Found a region?
82 r->in(0) == r && // Not already collapsed?
83 r != region && // Avoid stupid situations
84 r->outcnt() == 2 ) { // Self user and 'region' user only?
85 assert(!r->as_Region()->has_phi(), "no phi users");
86 if( !progress ) { // No progress
87 if (region->has_phi()) {
88 return NULL; // Only flatten if no Phi users
89 // igvn->hash_delete( phi );
90 }
91 igvn->hash_delete( region );
92 progress = region; // Making progress
93 }
94 igvn->hash_delete( r );
95
96 // Append inputs to 'r' onto 'region'
97 for( uint j = 1; j < r->req(); j++ ) {
98 // Move an input from 'r' to 'region'
99 region->add_req(r->in(j));
100 r->set_req(j, phase->C->top());
101 // Update phis of 'region'
102 //for( uint k = 0; k < max; k++ ) {
103 // Node *phi = region->out(k);
104 // if( phi->is_Phi() ) {
105 // phi->add_req(phi->in(i));
106 // }
107 //}
108
109 rreq++; // One more input to Region
110 } // Found a region to merge into Region
111 igvn->_worklist.push(r);
112 // Clobber pointer to the now dead 'r'
113 region->set_req(i, phase->C->top());
114 }
115 }
116
117 return progress;
118 }
119
120
121
122 //--------------------------------has_phi--------------------------------------
123 // Helper function: Return any PhiNode that uses this region or NULL
124 PhiNode* RegionNode::has_phi() const {
125 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
126 Node* phi = fast_out(i);
127 if (phi->is_Phi()) { // Check for Phi users
128 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
129 return phi->as_Phi(); // this one is good enough
130 }
131 }
132
133 return NULL;
134 }
135
136
137 //-----------------------------has_unique_phi----------------------------------
138 // Helper function: Return the only PhiNode that uses this region or NULL
139 PhiNode* RegionNode::has_unique_phi() const {
140 // Check that only one use is a Phi
141 PhiNode* only_phi = NULL;
142 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
143 Node* phi = fast_out(i);
144 if (phi->is_Phi()) { // Check for Phi users
145 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
146 if (only_phi == NULL) {
147 only_phi = phi->as_Phi();
148 } else {
149 return NULL; // multiple phis
150 }
151 }
152 }
153
154 return only_phi;
155 }
156
157
158 //------------------------------check_phi_clipping-----------------------------
159 // Helper function for RegionNode's identification of FP clipping
160 // Check inputs to the Phi
161 static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) {
162 min = NULL;
163 max = NULL;
164 val = NULL;
165 min_idx = 0;
166 max_idx = 0;
167 val_idx = 0;
168 uint phi_max = phi->req();
169 if( phi_max == 4 ) {
170 for( uint j = 1; j < phi_max; ++j ) {
171 Node *n = phi->in(j);
172 int opcode = n->Opcode();
173 switch( opcode ) {
174 case Op_ConI:
175 {
176 if( min == NULL ) {
177 min = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
178 min_idx = j;
179 } else {
180 max = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
181 max_idx = j;
182 if( min->get_int() > max->get_int() ) {
183 // Swap min and max
184 ConNode *temp;
185 uint temp_idx;
186 temp = min; min = max; max = temp;
187 temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx;
188 }
189 }
190 }
191 break;
192 default:
193 {
194 val = n;
195 val_idx = j;
196 }
197 break;
198 }
199 }
200 }
201 return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) );
202 }
203
204
205 //------------------------------check_if_clipping------------------------------
206 // Helper function for RegionNode's identification of FP clipping
207 // Check that inputs to Region come from two IfNodes,
208 //
209 // If
210 // False True
211 // If |
212 // False True |
213 // | | |
214 // RegionNode_inputs
215 //
216 static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) {
217 top_if = NULL;
218 bot_if = NULL;
219
220 // Check control structure above RegionNode for (if ( if ) )
221 Node *in1 = region->in(1);
222 Node *in2 = region->in(2);
223 Node *in3 = region->in(3);
224 // Check that all inputs are projections
225 if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) {
226 Node *in10 = in1->in(0);
227 Node *in20 = in2->in(0);
228 Node *in30 = in3->in(0);
229 // Check that #1 and #2 are ifTrue and ifFalse from same If
230 if( in10 != NULL && in10->is_If() &&
231 in20 != NULL && in20->is_If() &&
232 in30 != NULL && in30->is_If() && in10 == in20 &&
233 (in1->Opcode() != in2->Opcode()) ) {
234 Node *in100 = in10->in(0);
235 Node *in1000 = (in100 != NULL && in100->is_Proj()) ? in100->in(0) : NULL;
236 // Check that control for in10 comes from other branch of IF from in3
237 if( in1000 != NULL && in1000->is_If() &&
238 in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) {
239 // Control pattern checks
240 top_if = (IfNode*)in1000;
241 bot_if = (IfNode*)in10;
242 }
243 }
244 }
245
246 return (top_if != NULL);
247 }
248
249
250 //------------------------------check_convf2i_clipping-------------------------
251 // Helper function for RegionNode's identification of FP clipping
252 // Verify that the value input to the phi comes from "ConvF2I; LShift; RShift"
253 static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) {
254 convf2i = NULL;
255
256 // Check for the RShiftNode
257 Node *rshift = phi->in(idx);
258 assert( rshift, "Previous checks ensure phi input is present");
259 if( rshift->Opcode() != Op_RShiftI ) { return false; }
260
261 // Check for the LShiftNode
262 Node *lshift = rshift->in(1);
263 assert( lshift, "Previous checks ensure phi input is present");
264 if( lshift->Opcode() != Op_LShiftI ) { return false; }
265
266 // Check for the ConvF2INode
267 Node *conv = lshift->in(1);
268 if( conv->Opcode() != Op_ConvF2I ) { return false; }
269
270 // Check that shift amounts are only to get sign bits set after F2I
271 jint max_cutoff = max->get_int();
272 jint min_cutoff = min->get_int();
273 jint left_shift = lshift->in(2)->get_int();
274 jint right_shift = rshift->in(2)->get_int();
275 jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1);
276 if( left_shift != right_shift ||
277 0 > left_shift || left_shift >= BitsPerJavaInteger ||
278 max_post_shift < max_cutoff ||
279 max_post_shift < -min_cutoff ) {
280 // Shifts are necessary but current transformation eliminates them
281 return false;
282 }
283
284 // OK to return the result of ConvF2I without shifting
285 convf2i = (ConvF2INode*)conv;
286 return true;
287 }
288
289
290 //------------------------------check_compare_clipping-------------------------
291 // Helper function for RegionNode's identification of FP clipping
292 static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) {
293 Node *i1 = iff->in(1);
294 if ( !i1->is_Bool() ) { return false; }
295 BoolNode *bool1 = i1->as_Bool();
296 if( less_than && bool1->_test._test != BoolTest::le ) { return false; }
297 else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; }
298 const Node *cmpF = bool1->in(1);
299 if( cmpF->Opcode() != Op_CmpF ) { return false; }
300 // Test that the float value being compared against
301 // is equivalent to the int value used as a limit
302 Node *nodef = cmpF->in(2);
303 if( nodef->Opcode() != Op_ConF ) { return false; }
304 jfloat conf = nodef->getf();
305 jint coni = limit->get_int();
306 if( ((int)conf) != coni ) { return false; }
307 input = cmpF->in(1);
308 return true;
309 }
310
311 //------------------------------is_unreachable_region--------------------------
312 // Find if the Region node is reachable from the root.
313 bool RegionNode::is_unreachable_region(PhaseGVN *phase) const {
314 assert(req() == 2, "");
315
316 // First, cut the simple case of fallthrough region when NONE of
317 // region's phis references itself directly or through a data node.
318 uint max = outcnt();
319 uint i;
320 for (i = 0; i < max; i++) {
321 Node* phi = raw_out(i);
322 if (phi != NULL && phi->is_Phi()) {
323 assert(phase->eqv(phi->in(0), this) && phi->req() == 2, "");
324 if (phi->outcnt() == 0)
325 continue; // Safe case - no loops
326 if (phi->outcnt() == 1) {
327 Node* u = phi->raw_out(0);
328 // Skip if only one use is an other Phi or Call or Uncommon trap.
329 // It is safe to consider this case as fallthrough.
330 if (u != NULL && (u->is_Phi() || u->is_CFG()))
331 continue;
332 }
333 // Check when phi references itself directly or through an other node.
334 if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe)
335 break; // Found possible unsafe data loop.
336 }
337 }
338 if (i >= max)
339 return false; // An unsafe case was NOT found - don't need graph walk.
340
341 // Unsafe case - check if the Region node is reachable from root.
342 ResourceMark rm;
343
344 Arena *a = Thread::current()->resource_area();
345 Node_List nstack(a);
346 VectorSet visited(a);
347
348 // Mark all control nodes reachable from root outputs
349 Node *n = (Node*)phase->C->root();
350 nstack.push(n);
351 visited.set(n->_idx);
352 while (nstack.size() != 0) {
353 n = nstack.pop();
354 uint max = n->outcnt();
355 for (uint i = 0; i < max; i++) {
356 Node* m = n->raw_out(i);
357 if (m != NULL && m->is_CFG()) {
358 if (phase->eqv(m, this)) {
359 return false; // We reached the Region node - it is not dead.
360 }
361 if (!visited.test_set(m->_idx))
362 nstack.push(m);
363 }
364 }
365 }
366
367 return true; // The Region node is unreachable - it is dead.
368 }
369
370 bool RegionNode::try_clean_mem_phi(PhaseGVN *phase) {
371 // Incremental inlining + PhaseStringOpts sometimes produce:
372 //
373 // cmpP with 1 top input
374 // |
375 // If
376 // / \
377 // IfFalse IfTrue /- Some Node
378 // \ / / /
379 // Region / /-MergeMem
380 // \---Phi
381 //
382 //
383 // It's expected by PhaseStringOpts that the Region goes away and is
384 // replaced by If's control input but because there's still a Phi,
385 // the Region stays in the graph. The top input from the cmpP is
386 // propagated forward and a subgraph that is useful goes away. The
387 // code below replaces the Phi with the MergeMem so that the Region
388 // is simplified.
389
390 PhiNode* phi = has_unique_phi();
391 if (phi && phi->type() == Type::MEMORY && req() == 3 && phi->is_diamond_phi(true)) {
392 MergeMemNode* m = NULL;
393 assert(phi->req() == 3, "same as region");
394 for (uint i = 1; i < 3; ++i) {
395 Node *mem = phi->in(i);
396 if (mem && mem->is_MergeMem() && in(i)->outcnt() == 1) {
397 // Nothing is control-dependent on path #i except the region itself.
398 m = mem->as_MergeMem();
399 uint j = 3 - i;
400 Node* other = phi->in(j);
401 if (other && other == m->base_memory()) {
402 // m is a successor memory to other, and is not pinned inside the diamond, so push it out.
403 // This will allow the diamond to collapse completely.
404 phase->is_IterGVN()->replace_node(phi, m);
405 return true;
406 }
407 }
408 }
409 }
410 return false;
411 }
412
413 //------------------------------Ideal------------------------------------------
414 // Return a node which is more "ideal" than the current node. Must preserve
415 // the CFG, but we can still strip out dead paths.
416 Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) {
417 if( !can_reshape && !in(0) ) return NULL; // Already degraded to a Copy
418 assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge");
419
420 // Check for RegionNode with no Phi users and both inputs come from either
421 // arm of the same IF. If found, then the control-flow split is useless.
422 bool has_phis = false;
423 if (can_reshape) { // Need DU info to check for Phi users
424 has_phis = (has_phi() != NULL); // Cache result
425 if (has_phis && try_clean_mem_phi(phase)) {
426 has_phis = false;
427 }
428
429 if (!has_phis) { // No Phi users? Nothing merging?
430 for (uint i = 1; i < req()-1; i++) {
431 Node *if1 = in(i);
432 if( !if1 ) continue;
433 Node *iff = if1->in(0);
434 if( !iff || !iff->is_If() ) continue;
435 for( uint j=i+1; j<req(); j++ ) {
436 if( in(j) && in(j)->in(0) == iff &&
437 if1->Opcode() != in(j)->Opcode() ) {
438 // Add the IF Projections to the worklist. They (and the IF itself)
439 // will be eliminated if dead.
440 phase->is_IterGVN()->add_users_to_worklist(iff);
441 set_req(i, iff->in(0));// Skip around the useless IF diamond
442 set_req(j, NULL);
443 return this; // Record progress
444 }
445 }
446 }
447 }
448 }
449
450 // Remove TOP or NULL input paths. If only 1 input path remains, this Region
451 // degrades to a copy.
452 bool add_to_worklist = false;
453 bool modified = false;
454 int cnt = 0; // Count of values merging
455 DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count
456 int del_it = 0; // The last input path we delete
457 // For all inputs...
458 for( uint i=1; i<req(); ++i ){// For all paths in
459 Node *n = in(i); // Get the input
460 if( n != NULL ) {
461 // Remove useless control copy inputs
462 if( n->is_Region() && n->as_Region()->is_copy() ) {
463 set_req(i, n->nonnull_req());
464 modified = true;
465 i--;
466 continue;
467 }
468 if( n->is_Proj() ) { // Remove useless rethrows
469 Node *call = n->in(0);
470 if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) {
471 set_req(i, call->in(0));
472 modified = true;
473 i--;
474 continue;
475 }
476 }
477 if( phase->type(n) == Type::TOP ) {
478 set_req(i, NULL); // Ignore TOP inputs
479 modified = true;
480 i--;
481 continue;
482 }
483 cnt++; // One more value merging
484
485 } else if (can_reshape) { // Else found dead path with DU info
486 PhaseIterGVN *igvn = phase->is_IterGVN();
487 del_req(i); // Yank path from self
488 del_it = i;
489 uint max = outcnt();
490 DUIterator j;
491 bool progress = true;
492 while(progress) { // Need to establish property over all users
493 progress = false;
494 for (j = outs(); has_out(j); j++) {
495 Node *n = out(j);
496 if( n->req() != req() && n->is_Phi() ) {
497 assert( n->in(0) == this, "" );
498 igvn->hash_delete(n); // Yank from hash before hacking edges
499 n->set_req_X(i,NULL,igvn);// Correct DU info
500 n->del_req(i); // Yank path from Phis
501 if( max != outcnt() ) {
502 progress = true;
503 j = refresh_out_pos(j);
504 max = outcnt();
505 }
506 }
507 }
508 }
509 add_to_worklist = true;
510 i--;
511 }
512 }
513
514 if (can_reshape && cnt == 1) {
515 // Is it dead loop?
516 // If it is LoopNopde it had 2 (+1 itself) inputs and
517 // one of them was cut. The loop is dead if it was EntryContol.
518 // Loop node may have only one input because entry path
519 // is removed in PhaseIdealLoop::Dominators().
520 assert(!this->is_Loop() || cnt_orig <= 3, "Loop node should have 3 or less inputs");
521 if (this->is_Loop() && (del_it == LoopNode::EntryControl ||
522 del_it == 0 && is_unreachable_region(phase)) ||
523 !this->is_Loop() && has_phis && is_unreachable_region(phase)) {
524 // Yes, the region will be removed during the next step below.
525 // Cut the backedge input and remove phis since no data paths left.
526 // We don't cut outputs to other nodes here since we need to put them
527 // on the worklist.
528 del_req(1);
529 cnt = 0;
530 assert( req() == 1, "no more inputs expected" );
531 uint max = outcnt();
532 bool progress = true;
533 Node *top = phase->C->top();
534 PhaseIterGVN *igvn = phase->is_IterGVN();
535 DUIterator j;
536 while(progress) {
537 progress = false;
538 for (j = outs(); has_out(j); j++) {
539 Node *n = out(j);
540 if( n->is_Phi() ) {
541 assert( igvn->eqv(n->in(0), this), "" );
542 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
543 // Break dead loop data path.
544 // Eagerly replace phis with top to avoid phis copies generation.
545 igvn->replace_node(n, top);
546 if( max != outcnt() ) {
547 progress = true;
548 j = refresh_out_pos(j);
549 max = outcnt();
550 }
551 }
552 }
553 }
554 add_to_worklist = true;
555 }
556 }
557 if (add_to_worklist) {
558 phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis
559 }
560
561 if( cnt <= 1 ) { // Only 1 path in?
562 set_req(0, NULL); // Null control input for region copy
563 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is.
564 // No inputs or all inputs are NULL.
565 return NULL;
566 } else if (can_reshape) { // Optimization phase - remove the node
567 PhaseIterGVN *igvn = phase->is_IterGVN();
568 Node *parent_ctrl;
569 if( cnt == 0 ) {
570 assert( req() == 1, "no inputs expected" );
571 // During IGVN phase such region will be subsumed by TOP node
572 // so region's phis will have TOP as control node.
573 // Kill phis here to avoid it. PhiNode::is_copy() will be always false.
574 // Also set other user's input to top.
575 parent_ctrl = phase->C->top();
576 } else {
577 // The fallthrough case since we already checked dead loops above.
578 parent_ctrl = in(1);
579 assert(parent_ctrl != NULL, "Region is a copy of some non-null control");
580 assert(!igvn->eqv(parent_ctrl, this), "Close dead loop");
581 }
582 if (!add_to_worklist)
583 igvn->add_users_to_worklist(this); // Check for further allowed opts
584 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
585 Node* n = last_out(i);
586 igvn->hash_delete(n); // Remove from worklist before modifying edges
587 if( n->is_Phi() ) { // Collapse all Phis
588 // Eagerly replace phis to avoid copies generation.
589 Node* in;
590 if( cnt == 0 ) {
591 assert( n->req() == 1, "No data inputs expected" );
592 in = parent_ctrl; // replaced by top
593 } else {
594 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
595 in = n->in(1); // replaced by unique input
596 if( n->as_Phi()->is_unsafe_data_reference(in) )
597 in = phase->C->top(); // replaced by top
598 }
599 igvn->replace_node(n, in);
600 }
601 else if( n->is_Region() ) { // Update all incoming edges
602 assert( !igvn->eqv(n, this), "Must be removed from DefUse edges");
603 uint uses_found = 0;
604 for( uint k=1; k < n->req(); k++ ) {
605 if( n->in(k) == this ) {
606 n->set_req(k, parent_ctrl);
607 uses_found++;
608 }
609 }
610 if( uses_found > 1 ) { // (--i) done at the end of the loop.
611 i -= (uses_found - 1);
612 }
613 }
614 else {
615 assert( igvn->eqv(n->in(0), this), "Expect RegionNode to be control parent");
616 n->set_req(0, parent_ctrl);
617 }
618 #ifdef ASSERT
619 for( uint k=0; k < n->req(); k++ ) {
620 assert( !igvn->eqv(n->in(k), this), "All uses of RegionNode should be gone");
621 }
622 #endif
623 }
624 // Remove the RegionNode itself from DefUse info
625 igvn->remove_dead_node(this);
626 return NULL;
627 }
628 return this; // Record progress
629 }
630
631
632 // If a Region flows into a Region, merge into one big happy merge.
633 if (can_reshape) {
634 Node *m = merge_region(this, phase);
635 if (m != NULL) return m;
636 }
637
638 // Check if this region is the root of a clipping idiom on floats
639 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
640 // Check that only one use is a Phi and that it simplifies to two constants +
641 PhiNode* phi = has_unique_phi();
642 if (phi != NULL) { // One Phi user
643 // Check inputs to the Phi
644 ConNode *min;
645 ConNode *max;
646 Node *val;
647 uint min_idx;
648 uint max_idx;
649 uint val_idx;
650 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) {
651 IfNode *top_if;
652 IfNode *bot_if;
653 if( check_if_clipping( this, bot_if, top_if ) ) {
654 // Control pattern checks, now verify compares
655 Node *top_in = NULL; // value being compared against
656 Node *bot_in = NULL;
657 if( check_compare_clipping( true, bot_if, min, bot_in ) &&
658 check_compare_clipping( false, top_if, max, top_in ) ) {
659 if( bot_in == top_in ) {
660 PhaseIterGVN *gvn = phase->is_IterGVN();
661 assert( gvn != NULL, "Only had DefUse info in IterGVN");
662 // Only remaining check is that bot_in == top_in == (Phi's val + mods)
663
664 // Check for the ConvF2INode
665 ConvF2INode *convf2i;
666 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
667 convf2i->in(1) == bot_in ) {
668 // Matched pattern, including LShiftI; RShiftI, replace with integer compares
669 // max test
670 Node *cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, min ));
671 Node *boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::lt ));
672 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt ));
673 Node *if_min= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
674 Node *ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
675 // min test
676 cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, max ));
677 boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::gt ));
678 iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
679 Node *if_max= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
680 ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
681 // update input edges to region node
682 set_req_X( min_idx, if_min, gvn );
683 set_req_X( max_idx, if_max, gvn );
684 set_req_X( val_idx, ifF, gvn );
685 // remove unnecessary 'LShiftI; RShiftI' idiom
686 gvn->hash_delete(phi);
687 phi->set_req_X( val_idx, convf2i, gvn );
688 gvn->hash_find_insert(phi);
689 // Return transformed region node
690 return this;
691 }
692 }
693 }
694 }
695 }
696 }
697 }
698
699 return modified ? this : NULL;
700 }
701
702
703
704 const RegMask &RegionNode::out_RegMask() const {
705 return RegMask::Empty;
706 }
707
708 // Find the one non-null required input. RegionNode only
709 Node *Node::nonnull_req() const {
710 assert( is_Region(), "" );
711 for( uint i = 1; i < _cnt; i++ )
712 if( in(i) )
713 return in(i);
714 ShouldNotReachHere();
715 return NULL;
716 }
717
718
719 //=============================================================================
720 // note that these functions assume that the _adr_type field is flattened
721 uint PhiNode::hash() const {
722 const Type* at = _adr_type;
723 return TypeNode::hash() + (at ? at->hash() : 0);
724 }
725 uint PhiNode::cmp( const Node &n ) const {
726 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
727 }
728 static inline
729 const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
730 if (at == NULL || at == TypePtr::BOTTOM) return at;
731 return Compile::current()->alias_type(at)->adr_type();
732 }
733
734 //----------------------------make---------------------------------------------
735 // create a new phi with edges matching r and set (initially) to x
736 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
737 uint preds = r->req(); // Number of predecessor paths
738 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at");
739 PhiNode* p = new PhiNode(r, t, at);
740 for (uint j = 1; j < preds; j++) {
741 // Fill in all inputs, except those which the region does not yet have
742 if (r->in(j) != NULL)
743 p->init_req(j, x);
744 }
745 return p;
746 }
747 PhiNode* PhiNode::make(Node* r, Node* x) {
748 const Type* t = x->bottom_type();
749 const TypePtr* at = NULL;
750 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
751 return make(r, x, t, at);
752 }
753 PhiNode* PhiNode::make_blank(Node* r, Node* x) {
754 const Type* t = x->bottom_type();
755 const TypePtr* at = NULL;
756 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
757 return new PhiNode(r, t, at);
758 }
759
760
761 //------------------------slice_memory-----------------------------------------
762 // create a new phi with narrowed memory type
763 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
764 PhiNode* mem = (PhiNode*) clone();
765 *(const TypePtr**)&mem->_adr_type = adr_type;
766 // convert self-loops, or else we get a bad graph
767 for (uint i = 1; i < req(); i++) {
768 if ((const Node*)in(i) == this) mem->set_req(i, mem);
769 }
770 mem->verify_adr_type();
771 return mem;
772 }
773
774 //------------------------split_out_instance-----------------------------------
775 // Split out an instance type from a bottom phi.
776 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const {
777 const TypeOopPtr *t_oop = at->isa_oopptr();
778 assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr");
779 const TypePtr *t = adr_type();
780 assert(type() == Type::MEMORY &&
781 (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
782 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
783 t->is_oopptr()->cast_to_exactness(true)
784 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
785 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop),
786 "bottom or raw memory required");
787
788 // Check if an appropriate node already exists.
789 Node *region = in(0);
790 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) {
791 Node* use = region->fast_out(k);
792 if( use->is_Phi()) {
793 PhiNode *phi2 = use->as_Phi();
794 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) {
795 return phi2;
796 }
797 }
798 }
799 Compile *C = igvn->C;
800 Arena *a = Thread::current()->resource_area();
801 Node_Array node_map = new Node_Array(a);
802 Node_Stack stack(a, C->unique() >> 4);
803 PhiNode *nphi = slice_memory(at);
804 igvn->register_new_node_with_optimizer( nphi );
805 node_map.map(_idx, nphi);
806 stack.push((Node *)this, 1);
807 while(!stack.is_empty()) {
808 PhiNode *ophi = stack.node()->as_Phi();
809 uint i = stack.index();
810 assert(i >= 1, "not control edge");
811 stack.pop();
812 nphi = node_map[ophi->_idx]->as_Phi();
813 for (; i < ophi->req(); i++) {
814 Node *in = ophi->in(i);
815 if (in == NULL || igvn->type(in) == Type::TOP)
816 continue;
817 Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, NULL, igvn);
818 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL;
819 if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) {
820 opt = node_map[optphi->_idx];
821 if (opt == NULL) {
822 stack.push(ophi, i);
823 nphi = optphi->slice_memory(at);
824 igvn->register_new_node_with_optimizer( nphi );
825 node_map.map(optphi->_idx, nphi);
826 ophi = optphi;
827 i = 0; // will get incremented at top of loop
828 continue;
829 }
830 }
831 nphi->set_req(i, opt);
832 }
833 }
834 return nphi;
835 }
836
837 //------------------------verify_adr_type--------------------------------------
838 #ifdef ASSERT
839 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
840 if (visited.test_set(_idx)) return; //already visited
841
842 // recheck constructor invariants:
843 verify_adr_type(false);
844
845 // recheck local phi/phi consistency:
846 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
847 "adr_type must be consistent across phi nest");
848
849 // walk around
850 for (uint i = 1; i < req(); i++) {
851 Node* n = in(i);
852 if (n == NULL) continue;
853 const Node* np = in(i);
854 if (np->is_Phi()) {
855 np->as_Phi()->verify_adr_type(visited, at);
856 } else if (n->bottom_type() == Type::TOP
857 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
858 // ignore top inputs
859 } else {
860 const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
861 // recheck phi/non-phi consistency at leaves:
862 assert((nat != NULL) == (at != NULL), "");
863 assert(nat == at || nat == TypePtr::BOTTOM,
864 "adr_type must be consistent at leaves of phi nest");
865 }
866 }
867 }
868
869 // Verify a whole nest of phis rooted at this one.
870 void PhiNode::verify_adr_type(bool recursive) const {
871 if (is_error_reported()) return; // muzzle asserts when debugging an error
872 if (Node::in_dump()) return; // muzzle asserts when printing
873
874 assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only");
875
876 if (!VerifyAliases) return; // verify thoroughly only if requested
877
878 assert(_adr_type == flatten_phi_adr_type(_adr_type),
879 "Phi::adr_type must be pre-normalized");
880
881 if (recursive) {
882 VectorSet visited(Thread::current()->resource_area());
883 verify_adr_type(visited, _adr_type);
884 }
885 }
886 #endif
887
888
889 //------------------------------Value------------------------------------------
890 // Compute the type of the PhiNode
891 const Type *PhiNode::Value( PhaseTransform *phase ) const {
892 Node *r = in(0); // RegionNode
893 if( !r ) // Copy or dead
894 return in(1) ? phase->type(in(1)) : Type::TOP;
895
896 // Note: During parsing, phis are often transformed before their regions.
897 // This means we have to use type_or_null to defend against untyped regions.
898 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
899 return Type::TOP;
900
901 // Check for trip-counted loop. If so, be smarter.
902 CountedLoopNode *l = r->is_CountedLoop() ? r->as_CountedLoop() : NULL;
903 if( l && l->can_be_counted_loop(phase) &&
904 ((const Node*)l->phi() == this) ) { // Trip counted loop!
905 // protect against init_trip() or limit() returning NULL
906 const Node *init = l->init_trip();
907 const Node *limit = l->limit();
908 if( init != NULL && limit != NULL && l->stride_is_con() ) {
909 const TypeInt *lo = init ->bottom_type()->isa_int();
910 const TypeInt *hi = limit->bottom_type()->isa_int();
911 if( lo && hi ) { // Dying loops might have TOP here
912 int stride = l->stride_con();
913 if( stride < 0 ) { // Down-counter loop
914 const TypeInt *tmp = lo; lo = hi; hi = tmp;
915 stride = -stride;
916 }
917 if( lo->_hi < hi->_lo ) // Reversed endpoints are well defined :-(
918 return TypeInt::make(lo->_lo,hi->_hi,3);
919 }
920 }
921 }
922
923 // Until we have harmony between classes and interfaces in the type
924 // lattice, we must tread carefully around phis which implicitly
925 // convert the one to the other.
926 const TypePtr* ttp = _type->make_ptr();
927 const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL;
928 const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_klassptr() : NULL;
929 bool is_intf = false;
930 if (ttip != NULL) {
931 ciKlass* k = ttip->klass();
932 if (k->is_loaded() && k->is_interface())
933 is_intf = true;
934 }
935 if (ttkp != NULL) {
936 ciKlass* k = ttkp->klass();
937 if (k->is_loaded() && k->is_interface())
938 is_intf = true;
939 }
940
941 // Default case: merge all inputs
942 const Type *t = Type::TOP; // Merged type starting value
943 for (uint i = 1; i < req(); ++i) {// For all paths in
944 // Reachable control path?
945 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
946 const Type* ti = phase->type(in(i));
947 // We assume that each input of an interface-valued Phi is a true
948 // subtype of that interface. This might not be true of the meet
949 // of all the input types. The lattice is not distributive in
950 // such cases. Ward off asserts in type.cpp by refusing to do
951 // meets between interfaces and proper classes.
952 const TypePtr* tip = ti->make_ptr();
953 const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL;
954 if (tiip) {
955 bool ti_is_intf = false;
956 ciKlass* k = tiip->klass();
957 if (k->is_loaded() && k->is_interface())
958 ti_is_intf = true;
959 if (is_intf != ti_is_intf)
960 { t = _type; break; }
961 }
962 t = t->meet_speculative(ti);
963 }
964 }
965
966 // The worst-case type (from ciTypeFlow) should be consistent with "t".
967 // That is, we expect that "t->higher_equal(_type)" holds true.
968 // There are various exceptions:
969 // - Inputs which are phis might in fact be widened unnecessarily.
970 // For example, an input might be a widened int while the phi is a short.
971 // - Inputs might be BotPtrs but this phi is dependent on a null check,
972 // and postCCP has removed the cast which encodes the result of the check.
973 // - The type of this phi is an interface, and the inputs are classes.
974 // - Value calls on inputs might produce fuzzy results.
975 // (Occurrences of this case suggest improvements to Value methods.)
976 //
977 // It is not possible to see Type::BOTTOM values as phi inputs,
978 // because the ciTypeFlow pre-pass produces verifier-quality types.
979 const Type* ft = t->filter_speculative(_type); // Worst case type
980
981 #ifdef ASSERT
982 // The following logic has been moved into TypeOopPtr::filter.
983 const Type* jt = t->join_speculative(_type);
984 if( jt->empty() ) { // Emptied out???
985
986 // Check for evil case of 't' being a class and '_type' expecting an
987 // interface. This can happen because the bytecodes do not contain
988 // enough type info to distinguish a Java-level interface variable
989 // from a Java-level object variable. If we meet 2 classes which
990 // both implement interface I, but their meet is at 'j/l/O' which
991 // doesn't implement I, we have no way to tell if the result should
992 // be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows
993 // into a Phi which "knows" it's an Interface type we'll have to
994 // uplift the type.
995 if( !t->empty() && ttip && ttip->is_loaded() && ttip->klass()->is_interface() )
996 { assert(ft == _type, ""); } // Uplift to interface
997 else if( !t->empty() && ttkp && ttkp->is_loaded() && ttkp->klass()->is_interface() )
998 { assert(ft == _type, ""); } // Uplift to interface
999 // Otherwise it's something stupid like non-overlapping int ranges
1000 // found on dying counted loops.
1001 else
1002 { assert(ft == Type::TOP, ""); } // Canonical empty value
1003 }
1004
1005 else {
1006
1007 // If we have an interface-typed Phi and we narrow to a class type, the join
1008 // should report back the class. However, if we have a J/L/Object
1009 // class-typed Phi and an interface flows in, it's possible that the meet &
1010 // join report an interface back out. This isn't possible but happens
1011 // because the type system doesn't interact well with interfaces.
1012 const TypePtr *jtp = jt->make_ptr();
1013 const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL;
1014 const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_klassptr() : NULL;
1015 if( jtip && ttip ) {
1016 if( jtip->is_loaded() && jtip->klass()->is_interface() &&
1017 ttip->is_loaded() && !ttip->klass()->is_interface() ) {
1018 assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) ||
1019 ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), "");
1020 jt = ft;
1021 }
1022 }
1023 if( jtkp && ttkp ) {
1024 if( jtkp->is_loaded() && jtkp->klass()->is_interface() &&
1025 !jtkp->klass_is_exact() && // Keep exact interface klass (6894807)
1026 ttkp->is_loaded() && !ttkp->klass()->is_interface() ) {
1027 assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) ||
1028 ft->isa_narrowklass() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), "");
1029 jt = ft;
1030 }
1031 }
1032 if (jt != ft && jt->base() == ft->base()) {
1033 if (jt->isa_int() &&
1034 jt->is_int()->_lo == ft->is_int()->_lo &&
1035 jt->is_int()->_hi == ft->is_int()->_hi)
1036 jt = ft;
1037 if (jt->isa_long() &&
1038 jt->is_long()->_lo == ft->is_long()->_lo &&
1039 jt->is_long()->_hi == ft->is_long()->_hi)
1040 jt = ft;
1041 }
1042 if (jt != ft) {
1043 tty->print("merge type: "); t->dump(); tty->cr();
1044 tty->print("kill type: "); _type->dump(); tty->cr();
1045 tty->print("join type: "); jt->dump(); tty->cr();
1046 tty->print("filter type: "); ft->dump(); tty->cr();
1047 }
1048 assert(jt == ft, "");
1049 }
1050 #endif //ASSERT
1051
1052 // Deal with conversion problems found in data loops.
1053 ft = phase->saturate(ft, phase->type_or_null(this), _type);
1054
1055 return ft;
1056 }
1057
1058
1059 //------------------------------is_diamond_phi---------------------------------
1060 // Does this Phi represent a simple well-shaped diamond merge? Return the
1061 // index of the true path or 0 otherwise.
1062 // If check_control_only is true, do not inspect the If node at the
1063 // top, and return -1 (not an edge number) on success.
1064 int PhiNode::is_diamond_phi(bool check_control_only) const {
1065 // Check for a 2-path merge
1066 Node *region = in(0);
1067 if( !region ) return 0;
1068 if( region->req() != 3 ) return 0;
1069 if( req() != 3 ) return 0;
1070 // Check that both paths come from the same If
1071 Node *ifp1 = region->in(1);
1072 Node *ifp2 = region->in(2);
1073 if( !ifp1 || !ifp2 ) return 0;
1074 Node *iff = ifp1->in(0);
1075 if( !iff || !iff->is_If() ) return 0;
1076 if( iff != ifp2->in(0) ) return 0;
1077 if (check_control_only) return -1;
1078 // Check for a proper bool/cmp
1079 const Node *b = iff->in(1);
1080 if( !b->is_Bool() ) return 0;
1081 const Node *cmp = b->in(1);
1082 if( !cmp->is_Cmp() ) return 0;
1083
1084 // Check for branching opposite expected
1085 if( ifp2->Opcode() == Op_IfTrue ) {
1086 assert( ifp1->Opcode() == Op_IfFalse, "" );
1087 return 2;
1088 } else {
1089 assert( ifp1->Opcode() == Op_IfTrue, "" );
1090 return 1;
1091 }
1092 }
1093
1094 //----------------------------check_cmove_id-----------------------------------
1095 // Check for CMove'ing a constant after comparing against the constant.
1096 // Happens all the time now, since if we compare equality vs a constant in
1097 // the parser, we "know" the variable is constant on one path and we force
1098 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
1099 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more
1100 // general in that we don't need constants. Since CMove's are only inserted
1101 // in very special circumstances, we do it here on generic Phi's.
1102 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
1103 assert(true_path !=0, "only diamond shape graph expected");
1104
1105 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1106 // phi->region->if_proj->ifnode->bool->cmp
1107 Node* region = in(0);
1108 Node* iff = region->in(1)->in(0);
1109 BoolNode* b = iff->in(1)->as_Bool();
1110 Node* cmp = b->in(1);
1111 Node* tval = in(true_path);
1112 Node* fval = in(3-true_path);
1113 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
1114 if (id == NULL)
1115 return NULL;
1116
1117 // Either value might be a cast that depends on a branch of 'iff'.
1118 // Since the 'id' value will float free of the diamond, either
1119 // decast or return failure.
1120 Node* ctl = id->in(0);
1121 if (ctl != NULL && ctl->in(0) == iff) {
1122 if (id->is_ConstraintCast()) {
1123 return id->in(1);
1124 } else {
1125 // Don't know how to disentangle this value.
1126 return NULL;
1127 }
1128 }
1129
1130 return id;
1131 }
1132
1133 //------------------------------Identity---------------------------------------
1134 // Check for Region being Identity.
1135 Node *PhiNode::Identity( PhaseTransform *phase ) {
1136 // Check for no merging going on
1137 // (There used to be special-case code here when this->region->is_Loop.
1138 // It would check for a tributary phi on the backedge that the main phi
1139 // trivially, perhaps with a single cast. The unique_input method
1140 // does all this and more, by reducing such tributaries to 'this'.)
1141 Node* uin = unique_input(phase);
1142 if (uin != NULL) {
1143 return uin;
1144 }
1145
1146 int true_path = is_diamond_phi();
1147 if (true_path != 0) {
1148 Node* id = is_cmove_id(phase, true_path);
1149 if (id != NULL) return id;
1150 }
1151
1152 return this; // No identity
1153 }
1154
1155 //-----------------------------unique_input------------------------------------
1156 // Find the unique value, discounting top, self-loops, and casts.
1157 // Return top if there are no inputs, and self if there are multiple.
1158 Node* PhiNode::unique_input(PhaseTransform* phase) {
1159 // 1) One unique direct input, or
1160 // 2) some of the inputs have an intervening ConstraintCast and
1161 // the type of input is the same or sharper (more specific)
1162 // than the phi's type.
1163 // 3) an input is a self loop
1164 //
1165 // 1) input or 2) input or 3) input __
1166 // / \ / \ \ / \
1167 // \ / | cast phi cast
1168 // phi \ / / \ /
1169 // phi / --
1170
1171 Node* r = in(0); // RegionNode
1172 if (r == NULL) return in(1); // Already degraded to a Copy
1173 Node* uncasted_input = NULL; // The unique uncasted input (ConstraintCasts removed)
1174 Node* direct_input = NULL; // The unique direct input
1175
1176 for (uint i = 1, cnt = req(); i < cnt; ++i) {
1177 Node* rc = r->in(i);
1178 if (rc == NULL || phase->type(rc) == Type::TOP)
1179 continue; // ignore unreachable control path
1180 Node* n = in(i);
1181 if (n == NULL)
1182 continue;
1183 Node* un = n->uncast();
1184 if (un == NULL || un == this || phase->type(un) == Type::TOP) {
1185 continue; // ignore if top, or in(i) and "this" are in a data cycle
1186 }
1187 // Check for a unique uncasted input
1188 if (uncasted_input == NULL) {
1189 uncasted_input = un;
1190 } else if (uncasted_input != un) {
1191 uncasted_input = NodeSentinel; // no unique uncasted input
1192 }
1193 // Check for a unique direct input
1194 if (direct_input == NULL) {
1195 direct_input = n;
1196 } else if (direct_input != n) {
1197 direct_input = NodeSentinel; // no unique direct input
1198 }
1199 }
1200 if (direct_input == NULL) {
1201 return phase->C->top(); // no inputs
1202 }
1203 assert(uncasted_input != NULL,"");
1204
1205 if (direct_input != NodeSentinel) {
1206 return direct_input; // one unique direct input
1207 }
1208 if (uncasted_input != NodeSentinel &&
1209 phase->type(uncasted_input)->higher_equal(type())) {
1210 return uncasted_input; // one unique uncasted input
1211 }
1212
1213 // Nothing.
1214 return NULL;
1215 }
1216
1217 //------------------------------is_x2logic-------------------------------------
1218 // Check for simple convert-to-boolean pattern
1219 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
1220 // Convert Phi to an ConvIB.
1221 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
1222 assert(true_path !=0, "only diamond shape graph expected");
1223 // Convert the true/false index into an expected 0/1 return.
1224 // Map 2->0 and 1->1.
1225 int flipped = 2-true_path;
1226
1227 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1228 // phi->region->if_proj->ifnode->bool->cmp
1229 Node *region = phi->in(0);
1230 Node *iff = region->in(1)->in(0);
1231 BoolNode *b = (BoolNode*)iff->in(1);
1232 const CmpNode *cmp = (CmpNode*)b->in(1);
1233
1234 Node *zero = phi->in(1);
1235 Node *one = phi->in(2);
1236 const Type *tzero = phase->type( zero );
1237 const Type *tone = phase->type( one );
1238
1239 // Check for compare vs 0
1240 const Type *tcmp = phase->type(cmp->in(2));
1241 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
1242 // Allow cmp-vs-1 if the other input is bounded by 0-1
1243 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
1244 return NULL;
1245 flipped = 1-flipped; // Test is vs 1 instead of 0!
1246 }
1247
1248 // Check for setting zero/one opposite expected
1249 if( tzero == TypeInt::ZERO ) {
1250 if( tone == TypeInt::ONE ) {
1251 } else return NULL;
1252 } else if( tzero == TypeInt::ONE ) {
1253 if( tone == TypeInt::ZERO ) {
1254 flipped = 1-flipped;
1255 } else return NULL;
1256 } else return NULL;
1257
1258 // Check for boolean test backwards
1259 if( b->_test._test == BoolTest::ne ) {
1260 } else if( b->_test._test == BoolTest::eq ) {
1261 flipped = 1-flipped;
1262 } else return NULL;
1263
1264 // Build int->bool conversion
1265 Node *n = new Conv2BNode( cmp->in(1) );
1266 if( flipped )
1267 n = new XorINode( phase->transform(n), phase->intcon(1) );
1268
1269 return n;
1270 }
1271
1272 //------------------------------is_cond_add------------------------------------
1273 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;"
1274 // To be profitable the control flow has to disappear; there can be no other
1275 // values merging here. We replace the test-and-branch with:
1276 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by
1277 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
1278 // Then convert Y to 0-or-Y and finally add.
1279 // This is a key transform for SpecJava _201_compress.
1280 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
1281 assert(true_path !=0, "only diamond shape graph expected");
1282
1283 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1284 // phi->region->if_proj->ifnode->bool->cmp
1285 RegionNode *region = (RegionNode*)phi->in(0);
1286 Node *iff = region->in(1)->in(0);
1287 BoolNode* b = iff->in(1)->as_Bool();
1288 const CmpNode *cmp = (CmpNode*)b->in(1);
1289
1290 // Make sure only merging this one phi here
1291 if (region->has_unique_phi() != phi) return NULL;
1292
1293 // Make sure each arm of the diamond has exactly one output, which we assume
1294 // is the region. Otherwise, the control flow won't disappear.
1295 if (region->in(1)->outcnt() != 1) return NULL;
1296 if (region->in(2)->outcnt() != 1) return NULL;
1297
1298 // Check for "(P < Q)" of type signed int
1299 if (b->_test._test != BoolTest::lt) return NULL;
1300 if (cmp->Opcode() != Op_CmpI) return NULL;
1301
1302 Node *p = cmp->in(1);
1303 Node *q = cmp->in(2);
1304 Node *n1 = phi->in( true_path);
1305 Node *n2 = phi->in(3-true_path);
1306
1307 int op = n1->Opcode();
1308 if( op != Op_AddI // Need zero as additive identity
1309 /*&&op != Op_SubI &&
1310 op != Op_AddP &&
1311 op != Op_XorI &&
1312 op != Op_OrI*/ )
1313 return NULL;
1314
1315 Node *x = n2;
1316 Node *y = NULL;
1317 if( x == n1->in(1) ) {
1318 y = n1->in(2);
1319 } else if( x == n1->in(2) ) {
1320 y = n1->in(1);
1321 } else return NULL;
1322
1323 // Not so profitable if compare and add are constants
1324 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
1325 return NULL;
1326
1327 Node *cmplt = phase->transform( new CmpLTMaskNode(p,q) );
1328 Node *j_and = phase->transform( new AndINode(cmplt,y) );
1329 return new AddINode(j_and,x);
1330 }
1331
1332 //------------------------------is_absolute------------------------------------
1333 // Check for absolute value.
1334 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
1335 assert(true_path !=0, "only diamond shape graph expected");
1336
1337 int cmp_zero_idx = 0; // Index of compare input where to look for zero
1338 int phi_x_idx = 0; // Index of phi input where to find naked x
1339
1340 // ABS ends with the merge of 2 control flow paths.
1341 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
1342 int false_path = 3 - true_path;
1343
1344 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1345 // phi->region->if_proj->ifnode->bool->cmp
1346 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
1347
1348 // Check bool sense
1349 switch( bol->_test._test ) {
1350 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break;
1351 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1352 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1353 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
1354 default: return NULL; break;
1355 }
1356
1357 // Test is next
1358 Node *cmp = bol->in(1);
1359 const Type *tzero = NULL;
1360 switch( cmp->Opcode() ) {
1361 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS
1362 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS
1363 default: return NULL;
1364 }
1365
1366 // Find zero input of compare; the other input is being abs'd
1367 Node *x = NULL;
1368 bool flip = false;
1369 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
1370 x = cmp->in(3 - cmp_zero_idx);
1371 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
1372 // The test is inverted, we should invert the result...
1373 x = cmp->in(cmp_zero_idx);
1374 flip = true;
1375 } else {
1376 return NULL;
1377 }
1378
1379 // Next get the 2 pieces being selected, one is the original value
1380 // and the other is the negated value.
1381 if( phi_root->in(phi_x_idx) != x ) return NULL;
1382
1383 // Check other phi input for subtract node
1384 Node *sub = phi_root->in(3 - phi_x_idx);
1385
1386 // Allow only Sub(0,X) and fail out for all others; Neg is not OK
1387 if( tzero == TypeF::ZERO ) {
1388 if( sub->Opcode() != Op_SubF ||
1389 sub->in(2) != x ||
1390 phase->type(sub->in(1)) != tzero ) return NULL;
1391 x = new AbsFNode(x);
1392 if (flip) {
1393 x = new SubFNode(sub->in(1), phase->transform(x));
1394 }
1395 } else {
1396 if( sub->Opcode() != Op_SubD ||
1397 sub->in(2) != x ||
1398 phase->type(sub->in(1)) != tzero ) return NULL;
1399 x = new AbsDNode(x);
1400 if (flip) {
1401 x = new SubDNode(sub->in(1), phase->transform(x));
1402 }
1403 }
1404
1405 return x;
1406 }
1407
1408 //------------------------------split_once-------------------------------------
1409 // Helper for split_flow_path
1410 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
1411 igvn->hash_delete(n); // Remove from hash before hacking edges
1412
1413 uint j = 1;
1414 for (uint i = phi->req()-1; i > 0; i--) {
1415 if (phi->in(i) == val) { // Found a path with val?
1416 // Add to NEW Region/Phi, no DU info
1417 newn->set_req( j++, n->in(i) );
1418 // Remove from OLD Region/Phi
1419 n->del_req(i);
1420 }
1421 }
1422
1423 // Register the new node but do not transform it. Cannot transform until the
1424 // entire Region/Phi conglomerate has been hacked as a single huge transform.
1425 igvn->register_new_node_with_optimizer( newn );
1426
1427 // Now I can point to the new node.
1428 n->add_req(newn);
1429 igvn->_worklist.push(n);
1430 }
1431
1432 //------------------------------split_flow_path--------------------------------
1433 // Check for merging identical values and split flow paths
1434 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) {
1435 BasicType bt = phi->type()->basic_type();
1436 if( bt == T_ILLEGAL || type2size[bt] <= 0 )
1437 return NULL; // Bail out on funny non-value stuff
1438 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a
1439 return NULL; // third unequal input to be worth doing
1440
1441 // Scan for a constant
1442 uint i;
1443 for( i = 1; i < phi->req()-1; i++ ) {
1444 Node *n = phi->in(i);
1445 if( !n ) return NULL;
1446 if( phase->type(n) == Type::TOP ) return NULL;
1447 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN || n->Opcode() == Op_ConNKlass )
1448 break;
1449 }
1450 if( i >= phi->req() ) // Only split for constants
1451 return NULL;
1452
1453 Node *val = phi->in(i); // Constant to split for
1454 uint hit = 0; // Number of times it occurs
1455 Node *r = phi->region();
1456
1457 for( ; i < phi->req(); i++ ){ // Count occurrences of constant
1458 Node *n = phi->in(i);
1459 if( !n ) return NULL;
1460 if( phase->type(n) == Type::TOP ) return NULL;
1461 if( phi->in(i) == val ) {
1462 hit++;
1463 if (PhaseIdealLoop::find_predicate(r->in(i)) != NULL) {
1464 return NULL; // don't split loop entry path
1465 }
1466 }
1467 }
1468
1469 if( hit <= 1 || // Make sure we find 2 or more
1470 hit == phi->req()-1 ) // and not ALL the same value
1471 return NULL;
1472
1473 // Now start splitting out the flow paths that merge the same value.
1474 // Split first the RegionNode.
1475 PhaseIterGVN *igvn = phase->is_IterGVN();
1476 RegionNode *newr = new RegionNode(hit+1);
1477 split_once(igvn, phi, val, r, newr);
1478
1479 // Now split all other Phis than this one
1480 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) {
1481 Node* phi2 = r->fast_out(k);
1482 if( phi2->is_Phi() && phi2->as_Phi() != phi ) {
1483 PhiNode *newphi = PhiNode::make_blank(newr, phi2);
1484 split_once(igvn, phi, val, phi2, newphi);
1485 }
1486 }
1487
1488 // Clean up this guy
1489 igvn->hash_delete(phi);
1490 for( i = phi->req()-1; i > 0; i-- ) {
1491 if( phi->in(i) == val ) {
1492 phi->del_req(i);
1493 }
1494 }
1495 phi->add_req(val);
1496
1497 return phi;
1498 }
1499
1500 //=============================================================================
1501 //------------------------------simple_data_loop_check-------------------------
1502 // Try to determining if the phi node in a simple safe/unsafe data loop.
1503 // Returns:
1504 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
1505 // Safe - safe case when the phi and it's inputs reference only safe data
1506 // nodes;
1507 // Unsafe - the phi and it's inputs reference unsafe data nodes but there
1508 // is no reference back to the phi - need a graph walk
1509 // to determine if it is in a loop;
1510 // UnsafeLoop - unsafe case when the phi references itself directly or through
1511 // unsafe data node.
1512 // Note: a safe data node is a node which could/never reference itself during
1513 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP.
1514 // I mark Phi nodes as safe node not only because they can reference itself
1515 // but also to prevent mistaking the fallthrough case inside an outer loop
1516 // as dead loop when the phi references itselfs through an other phi.
1517 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const {
1518 // It is unsafe loop if the phi node references itself directly.
1519 if (in == (Node*)this)
1520 return UnsafeLoop; // Unsafe loop
1521 // Unsafe loop if the phi node references itself through an unsafe data node.
1522 // Exclude cases with null inputs or data nodes which could reference
1523 // itself (safe for dead loops).
1524 if (in != NULL && !in->is_dead_loop_safe()) {
1525 // Check inputs of phi's inputs also.
1526 // It is much less expensive then full graph walk.
1527 uint cnt = in->req();
1528 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1;
1529 for (; i < cnt; ++i) {
1530 Node* m = in->in(i);
1531 if (m == (Node*)this)
1532 return UnsafeLoop; // Unsafe loop
1533 if (m != NULL && !m->is_dead_loop_safe()) {
1534 // Check the most common case (about 30% of all cases):
1535 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con).
1536 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL;
1537 if (m1 == (Node*)this)
1538 return UnsafeLoop; // Unsafe loop
1539 if (m1 != NULL && m1 == m->in(2) &&
1540 m1->is_dead_loop_safe() && m->in(3)->is_Con()) {
1541 continue; // Safe case
1542 }
1543 // The phi references an unsafe node - need full analysis.
1544 return Unsafe;
1545 }
1546 }
1547 }
1548 return Safe; // Safe case - we can optimize the phi node.
1549 }
1550
1551 //------------------------------is_unsafe_data_reference-----------------------
1552 // If phi can be reached through the data input - it is data loop.
1553 bool PhiNode::is_unsafe_data_reference(Node *in) const {
1554 assert(req() > 1, "");
1555 // First, check simple cases when phi references itself directly or
1556 // through an other node.
1557 LoopSafety safety = simple_data_loop_check(in);
1558 if (safety == UnsafeLoop)
1559 return true; // phi references itself - unsafe loop
1560 else if (safety == Safe)
1561 return false; // Safe case - phi could be replaced with the unique input.
1562
1563 // Unsafe case when we should go through data graph to determine
1564 // if the phi references itself.
1565
1566 ResourceMark rm;
1567
1568 Arena *a = Thread::current()->resource_area();
1569 Node_List nstack(a);
1570 VectorSet visited(a);
1571
1572 nstack.push(in); // Start with unique input.
1573 visited.set(in->_idx);
1574 while (nstack.size() != 0) {
1575 Node* n = nstack.pop();
1576 uint cnt = n->req();
1577 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1;
1578 for (; i < cnt; i++) {
1579 Node* m = n->in(i);
1580 if (m == (Node*)this) {
1581 return true; // Data loop
1582 }
1583 if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases.
1584 if (!visited.test_set(m->_idx))
1585 nstack.push(m);
1586 }
1587 }
1588 }
1589 return false; // The phi is not reachable from its inputs
1590 }
1591
1592
1593 //------------------------------Ideal------------------------------------------
1594 // Return a node which is more "ideal" than the current node. Must preserve
1595 // the CFG, but we can still strip out dead paths.
1596 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1597 // The next should never happen after 6297035 fix.
1598 if( is_copy() ) // Already degraded to a Copy ?
1599 return NULL; // No change
1600
1601 Node *r = in(0); // RegionNode
1602 assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge");
1603
1604 // Note: During parsing, phis are often transformed before their regions.
1605 // This means we have to use type_or_null to defend against untyped regions.
1606 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1607 return NULL; // No change
1608
1609 Node *top = phase->C->top();
1610 bool new_phi = (outcnt() == 0); // transforming new Phi
1611 // No change for igvn if new phi is not hooked
1612 if (new_phi && can_reshape)
1613 return NULL;
1614
1615 // The are 2 situations when only one valid phi's input is left
1616 // (in addition to Region input).
1617 // One: region is not loop - replace phi with this input.
1618 // Two: region is loop - replace phi with top since this data path is dead
1619 // and we need to break the dead data loop.
1620 Node* progress = NULL; // Record if any progress made
1621 for( uint j = 1; j < req(); ++j ){ // For all paths in
1622 // Check unreachable control paths
1623 Node* rc = r->in(j);
1624 Node* n = in(j); // Get the input
1625 if (rc == NULL || phase->type(rc) == Type::TOP) {
1626 if (n != top) { // Not already top?
1627 PhaseIterGVN *igvn = phase->is_IterGVN();
1628 if (can_reshape && igvn != NULL) {
1629 igvn->_worklist.push(r);
1630 }
1631 set_req(j, top); // Nuke it down
1632 progress = this; // Record progress
1633 }
1634 }
1635 }
1636
1637 if (can_reshape && outcnt() == 0) {
1638 // set_req() above may kill outputs if Phi is referenced
1639 // only by itself on the dead (top) control path.
1640 return top;
1641 }
1642
1643 Node* uin = unique_input(phase);
1644 if (uin == top) { // Simplest case: no alive inputs.
1645 if (can_reshape) // IGVN transformation
1646 return top;
1647 else
1648 return NULL; // Identity will return TOP
1649 } else if (uin != NULL) {
1650 // Only one not-NULL unique input path is left.
1651 // Determine if this input is backedge of a loop.
1652 // (Skip new phis which have no uses and dead regions).
1653 if (outcnt() > 0 && r->in(0) != NULL) {
1654 // First, take the short cut when we know it is a loop and
1655 // the EntryControl data path is dead.
1656 // Loop node may have only one input because entry path
1657 // is removed in PhaseIdealLoop::Dominators().
1658 assert(!r->is_Loop() || r->req() <= 3, "Loop node should have 3 or less inputs");
1659 bool is_loop = (r->is_Loop() && r->req() == 3);
1660 // Then, check if there is a data loop when phi references itself directly
1661 // or through other data nodes.
1662 if (is_loop && !uin->eqv_uncast(in(LoopNode::EntryControl)) ||
1663 !is_loop && is_unsafe_data_reference(uin)) {
1664 // Break this data loop to avoid creation of a dead loop.
1665 if (can_reshape) {
1666 return top;
1667 } else {
1668 // We can't return top if we are in Parse phase - cut inputs only
1669 // let Identity to handle the case.
1670 replace_edge(uin, top);
1671 return NULL;
1672 }
1673 }
1674 }
1675
1676 // One unique input.
1677 debug_only(Node* ident = Identity(phase));
1678 // The unique input must eventually be detected by the Identity call.
1679 #ifdef ASSERT
1680 if (ident != uin && !ident->is_top()) {
1681 // print this output before failing assert
1682 r->dump(3);
1683 this->dump(3);
1684 ident->dump();
1685 uin->dump();
1686 }
1687 #endif
1688 assert(ident == uin || ident->is_top(), "Identity must clean this up");
1689 return NULL;
1690 }
1691
1692
1693 Node* opt = NULL;
1694 int true_path = is_diamond_phi();
1695 if( true_path != 0 ) {
1696 // Check for CMove'ing identity. If it would be unsafe,
1697 // handle it here. In the safe case, let Identity handle it.
1698 Node* unsafe_id = is_cmove_id(phase, true_path);
1699 if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) )
1700 opt = unsafe_id;
1701
1702 // Check for simple convert-to-boolean pattern
1703 if( opt == NULL )
1704 opt = is_x2logic(phase, this, true_path);
1705
1706 // Check for absolute value
1707 if( opt == NULL )
1708 opt = is_absolute(phase, this, true_path);
1709
1710 // Check for conditional add
1711 if( opt == NULL && can_reshape )
1712 opt = is_cond_add(phase, this, true_path);
1713
1714 // These 4 optimizations could subsume the phi:
1715 // have to check for a dead data loop creation.
1716 if( opt != NULL ) {
1717 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) {
1718 // Found dead loop.
1719 if( can_reshape )
1720 return top;
1721 // We can't return top if we are in Parse phase - cut inputs only
1722 // to stop further optimizations for this phi. Identity will return TOP.
1723 assert(req() == 3, "only diamond merge phi here");
1724 set_req(1, top);
1725 set_req(2, top);
1726 return NULL;
1727 } else {
1728 return opt;
1729 }
1730 }
1731 }
1732
1733 // Check for merging identical values and split flow paths
1734 if (can_reshape) {
1735 opt = split_flow_path(phase, this);
1736 // This optimization only modifies phi - don't need to check for dead loop.
1737 assert(opt == NULL || phase->eqv(opt, this), "do not elide phi");
1738 if (opt != NULL) return opt;
1739 }
1740
1741 if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) {
1742 // Try to undo Phi of AddP:
1743 // (Phi (AddP base base y) (AddP base2 base2 y))
1744 // becomes:
1745 // newbase := (Phi base base2)
1746 // (AddP newbase newbase y)
1747 //
1748 // This occurs as a result of unsuccessful split_thru_phi and
1749 // interferes with taking advantage of addressing modes. See the
1750 // clone_shift_expressions code in matcher.cpp
1751 Node* addp = in(1);
1752 const Type* type = addp->in(AddPNode::Base)->bottom_type();
1753 Node* y = addp->in(AddPNode::Offset);
1754 if (y != NULL && addp->in(AddPNode::Base) == addp->in(AddPNode::Address)) {
1755 // make sure that all the inputs are similar to the first one,
1756 // i.e. AddP with base == address and same offset as first AddP
1757 bool doit = true;
1758 for (uint i = 2; i < req(); i++) {
1759 if (in(i) == NULL ||
1760 in(i)->Opcode() != Op_AddP ||
1761 in(i)->in(AddPNode::Base) != in(i)->in(AddPNode::Address) ||
1762 in(i)->in(AddPNode::Offset) != y) {
1763 doit = false;
1764 break;
1765 }
1766 // Accumulate type for resulting Phi
1767 type = type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type());
1768 }
1769 Node* base = NULL;
1770 if (doit) {
1771 // Check for neighboring AddP nodes in a tree.
1772 // If they have a base, use that it.
1773 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) {
1774 Node* u = this->fast_out(k);
1775 if (u->is_AddP()) {
1776 Node* base2 = u->in(AddPNode::Base);
1777 if (base2 != NULL && !base2->is_top()) {
1778 if (base == NULL)
1779 base = base2;
1780 else if (base != base2)
1781 { doit = false; break; }
1782 }
1783 }
1784 }
1785 }
1786 if (doit) {
1787 if (base == NULL) {
1788 base = new PhiNode(in(0), type, NULL);
1789 for (uint i = 1; i < req(); i++) {
1790 base->init_req(i, in(i)->in(AddPNode::Base));
1791 }
1792 phase->is_IterGVN()->register_new_node_with_optimizer(base);
1793 }
1794 return new AddPNode(base, base, y);
1795 }
1796 }
1797 }
1798
1799 // Split phis through memory merges, so that the memory merges will go away.
1800 // Piggy-back this transformation on the search for a unique input....
1801 // It will be as if the merged memory is the unique value of the phi.
1802 // (Do not attempt this optimization unless parsing is complete.
1803 // It would make the parser's memory-merge logic sick.)
1804 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.)
1805 if (progress == NULL && can_reshape && type() == Type::MEMORY) {
1806 // see if this phi should be sliced
1807 uint merge_width = 0;
1808 bool saw_self = false;
1809 for( uint i=1; i<req(); ++i ) {// For all paths in
1810 Node *ii = in(i);
1811 if (ii->is_MergeMem()) {
1812 MergeMemNode* n = ii->as_MergeMem();
1813 merge_width = MAX2(merge_width, n->req());
1814 saw_self = saw_self || phase->eqv(n->base_memory(), this);
1815 }
1816 }
1817
1818 // This restriction is temporarily necessary to ensure termination:
1819 if (!saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0;
1820
1821 if (merge_width > Compile::AliasIdxRaw) {
1822 // found at least one non-empty MergeMem
1823 const TypePtr* at = adr_type();
1824 if (at != TypePtr::BOTTOM) {
1825 // Patch the existing phi to select an input from the merge:
1826 // Phi:AT1(...MergeMem(m0, m1, m2)...) into
1827 // Phi:AT1(...m1...)
1828 int alias_idx = phase->C->get_alias_index(at);
1829 for (uint i=1; i<req(); ++i) {
1830 Node *ii = in(i);
1831 if (ii->is_MergeMem()) {
1832 MergeMemNode* n = ii->as_MergeMem();
1833 // compress paths and change unreachable cycles to TOP
1834 // If not, we can update the input infinitely along a MergeMem cycle
1835 // Equivalent code is in MemNode::Ideal_common
1836 Node *m = phase->transform(n);
1837 if (outcnt() == 0) { // Above transform() may kill us!
1838 return top;
1839 }
1840 // If transformed to a MergeMem, get the desired slice
1841 // Otherwise the returned node represents memory for every slice
1842 Node *new_mem = (m->is_MergeMem()) ?
1843 m->as_MergeMem()->memory_at(alias_idx) : m;
1844 // Update input if it is progress over what we have now
1845 if (new_mem != ii) {
1846 set_req(i, new_mem);
1847 progress = this;
1848 }
1849 }
1850 }
1851 } else {
1852 // We know that at least one MergeMem->base_memory() == this
1853 // (saw_self == true). If all other inputs also references this phi
1854 // (directly or through data nodes) - it is dead loop.
1855 bool saw_safe_input = false;
1856 for (uint j = 1; j < req(); ++j) {
1857 Node *n = in(j);
1858 if (n->is_MergeMem() && n->as_MergeMem()->base_memory() == this)
1859 continue; // skip known cases
1860 if (!is_unsafe_data_reference(n)) {
1861 saw_safe_input = true; // found safe input
1862 break;
1863 }
1864 }
1865 if (!saw_safe_input)
1866 return top; // all inputs reference back to this phi - dead loop
1867
1868 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into
1869 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...))
1870 PhaseIterGVN *igvn = phase->is_IterGVN();
1871 Node* hook = new Node(1);
1872 PhiNode* new_base = (PhiNode*) clone();
1873 // Must eagerly register phis, since they participate in loops.
1874 if (igvn) {
1875 igvn->register_new_node_with_optimizer(new_base);
1876 hook->add_req(new_base);
1877 }
1878 MergeMemNode* result = MergeMemNode::make(new_base);
1879 for (uint i = 1; i < req(); ++i) {
1880 Node *ii = in(i);
1881 if (ii->is_MergeMem()) {
1882 MergeMemNode* n = ii->as_MergeMem();
1883 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) {
1884 // If we have not seen this slice yet, make a phi for it.
1885 bool made_new_phi = false;
1886 if (mms.is_empty()) {
1887 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C));
1888 made_new_phi = true;
1889 if (igvn) {
1890 igvn->register_new_node_with_optimizer(new_phi);
1891 hook->add_req(new_phi);
1892 }
1893 mms.set_memory(new_phi);
1894 }
1895 Node* phi = mms.memory();
1896 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice");
1897 phi->set_req(i, mms.memory2());
1898 }
1899 }
1900 }
1901 // Distribute all self-loops.
1902 { // (Extra braces to hide mms.)
1903 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
1904 Node* phi = mms.memory();
1905 for (uint i = 1; i < req(); ++i) {
1906 if (phi->in(i) == this) phi->set_req(i, phi);
1907 }
1908 }
1909 }
1910 // now transform the new nodes, and return the mergemem
1911 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
1912 Node* phi = mms.memory();
1913 mms.set_memory(phase->transform(phi));
1914 }
1915 if (igvn) { // Unhook.
1916 igvn->hash_delete(hook);
1917 for (uint i = 1; i < hook->req(); i++) {
1918 hook->set_req(i, NULL);
1919 }
1920 }
1921 // Replace self with the result.
1922 return result;
1923 }
1924 }
1925 //
1926 // Other optimizations on the memory chain
1927 //
1928 const TypePtr* at = adr_type();
1929 for( uint i=1; i<req(); ++i ) {// For all paths in
1930 Node *ii = in(i);
1931 Node *new_in = MemNode::optimize_memory_chain(ii, at, NULL, phase);
1932 if (ii != new_in ) {
1933 set_req(i, new_in);
1934 progress = this;
1935 }
1936 }
1937 }
1938
1939 #ifdef _LP64
1940 // Push DecodeN/DecodeNKlass down through phi.
1941 // The rest of phi graph will transform by split EncodeP node though phis up.
1942 if ((UseCompressedOops || UseCompressedClassPointers) && can_reshape && progress == NULL) {
1943 bool may_push = true;
1944 bool has_decodeN = false;
1945 bool is_decodeN = false;
1946 for (uint i=1; i<req(); ++i) {// For all paths in
1947 Node *ii = in(i);
1948 if (ii->is_DecodeNarrowPtr() && ii->bottom_type() == bottom_type()) {
1949 // Do optimization if a non dead path exist.
1950 if (ii->in(1)->bottom_type() != Type::TOP) {
1951 has_decodeN = true;
1952 is_decodeN = ii->is_DecodeN();
1953 }
1954 } else if (!ii->is_Phi()) {
1955 may_push = false;
1956 }
1957 }
1958
1959 if (has_decodeN && may_push) {
1960 PhaseIterGVN *igvn = phase->is_IterGVN();
1961 // Make narrow type for new phi.
1962 const Type* narrow_t;
1963 if (is_decodeN) {
1964 narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr());
1965 } else {
1966 narrow_t = TypeNarrowKlass::make(this->bottom_type()->is_ptr());
1967 }
1968 PhiNode* new_phi = new PhiNode(r, narrow_t);
1969 uint orig_cnt = req();
1970 for (uint i=1; i<req(); ++i) {// For all paths in
1971 Node *ii = in(i);
1972 Node* new_ii = NULL;
1973 if (ii->is_DecodeNarrowPtr()) {
1974 assert(ii->bottom_type() == bottom_type(), "sanity");
1975 new_ii = ii->in(1);
1976 } else {
1977 assert(ii->is_Phi(), "sanity");
1978 if (ii->as_Phi() == this) {
1979 new_ii = new_phi;
1980 } else {
1981 if (is_decodeN) {
1982 new_ii = new EncodePNode(ii, narrow_t);
1983 } else {
1984 new_ii = new EncodePKlassNode(ii, narrow_t);
1985 }
1986 igvn->register_new_node_with_optimizer(new_ii);
1987 }
1988 }
1989 new_phi->set_req(i, new_ii);
1990 }
1991 igvn->register_new_node_with_optimizer(new_phi, this);
1992 if (is_decodeN) {
1993 progress = new DecodeNNode(new_phi, bottom_type());
1994 } else {
1995 progress = new DecodeNKlassNode(new_phi, bottom_type());
1996 }
1997 }
1998 }
1999 #endif
2000
2001 return progress; // Return any progress
2002 }
2003
2004 //------------------------------is_tripcount-----------------------------------
2005 bool PhiNode::is_tripcount() const {
2006 return (in(0) != NULL && in(0)->is_CountedLoop() &&
2007 in(0)->as_CountedLoop()->phi() == this);
2008 }
2009
2010 //------------------------------out_RegMask------------------------------------
2011 const RegMask &PhiNode::in_RegMask(uint i) const {
2012 return i ? out_RegMask() : RegMask::Empty;
2013 }
2014
2015 const RegMask &PhiNode::out_RegMask() const {
2016 uint ideal_reg = _type->ideal_reg();
2017 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
2018 if( ideal_reg == 0 ) return RegMask::Empty;
2019 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
2020 }
2021
2022 #ifndef PRODUCT
2023 void PhiNode::dump_spec(outputStream *st) const {
2024 TypeNode::dump_spec(st);
2025 if (is_tripcount()) {
2026 st->print(" #tripcount");
2027 }
2028 }
2029 #endif
2030
2031
2032 //=============================================================================
2033 const Type *GotoNode::Value( PhaseTransform *phase ) const {
2034 // If the input is reachable, then we are executed.
2035 // If the input is not reachable, then we are not executed.
2036 return phase->type(in(0));
2037 }
2038
2039 Node *GotoNode::Identity( PhaseTransform *phase ) {
2040 return in(0); // Simple copy of incoming control
2041 }
2042
2043 const RegMask &GotoNode::out_RegMask() const {
2044 return RegMask::Empty;
2045 }
2046
2047 //=============================================================================
2048 const RegMask &JumpNode::out_RegMask() const {
2049 return RegMask::Empty;
2050 }
2051
2052 //=============================================================================
2053 const RegMask &JProjNode::out_RegMask() const {
2054 return RegMask::Empty;
2055 }
2056
2057 //=============================================================================
2058 const RegMask &CProjNode::out_RegMask() const {
2059 return RegMask::Empty;
2060 }
2061
2062
2063
2064 //=============================================================================
2065
2066 uint PCTableNode::hash() const { return Node::hash() + _size; }
2067 uint PCTableNode::cmp( const Node &n ) const
2068 { return _size == ((PCTableNode&)n)._size; }
2069
2070 const Type *PCTableNode::bottom_type() const {
2071 const Type** f = TypeTuple::fields(_size);
2072 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2073 return TypeTuple::make(_size, f);
2074 }
2075
2076 //------------------------------Value------------------------------------------
2077 // Compute the type of the PCTableNode. If reachable it is a tuple of
2078 // Control, otherwise the table targets are not reachable
2079 const Type *PCTableNode::Value( PhaseTransform *phase ) const {
2080 if( phase->type(in(0)) == Type::CONTROL )
2081 return bottom_type();
2082 return Type::TOP; // All paths dead? Then so are we
2083 }
2084
2085 //------------------------------Ideal------------------------------------------
2086 // Return a node which is more "ideal" than the current node. Strip out
2087 // control copies
2088 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2089 return remove_dead_region(phase, can_reshape) ? this : NULL;
2090 }
2091
2092 //=============================================================================
2093 uint JumpProjNode::hash() const {
2094 return Node::hash() + _dest_bci;
2095 }
2096
2097 uint JumpProjNode::cmp( const Node &n ) const {
2098 return ProjNode::cmp(n) &&
2099 _dest_bci == ((JumpProjNode&)n)._dest_bci;
2100 }
2101
2102 #ifndef PRODUCT
2103 void JumpProjNode::dump_spec(outputStream *st) const {
2104 ProjNode::dump_spec(st);
2105 st->print("@bci %d ",_dest_bci);
2106 }
2107 #endif
2108
2109 //=============================================================================
2110 //------------------------------Value------------------------------------------
2111 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot
2112 // have the default "fall_through_index" path.
2113 const Type *CatchNode::Value( PhaseTransform *phase ) const {
2114 // Unreachable? Then so are all paths from here.
2115 if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
2116 // First assume all paths are reachable
2117 const Type** f = TypeTuple::fields(_size);
2118 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2119 // Identify cases that will always throw an exception
2120 // () rethrow call
2121 // () virtual or interface call with NULL receiver
2122 // () call is a check cast with incompatible arguments
2123 if( in(1)->is_Proj() ) {
2124 Node *i10 = in(1)->in(0);
2125 if( i10->is_Call() ) {
2126 CallNode *call = i10->as_Call();
2127 // Rethrows always throw exceptions, never return
2128 if (call->entry_point() == OptoRuntime::rethrow_stub()) {
2129 f[CatchProjNode::fall_through_index] = Type::TOP;
2130 } else if( call->req() > TypeFunc::Parms ) {
2131 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) );
2132 // Check for null receiver to virtual or interface calls
2133 if( call->is_CallDynamicJava() &&
2134 arg0->higher_equal(TypePtr::NULL_PTR) ) {
2135 f[CatchProjNode::fall_through_index] = Type::TOP;
2136 }
2137 } // End of if not a runtime stub
2138 } // End of if have call above me
2139 } // End of slot 1 is not a projection
2140 return TypeTuple::make(_size, f);
2141 }
2142
2143 //=============================================================================
2144 uint CatchProjNode::hash() const {
2145 return Node::hash() + _handler_bci;
2146 }
2147
2148
2149 uint CatchProjNode::cmp( const Node &n ) const {
2150 return ProjNode::cmp(n) &&
2151 _handler_bci == ((CatchProjNode&)n)._handler_bci;
2152 }
2153
2154
2155 //------------------------------Identity---------------------------------------
2156 // If only 1 target is possible, choose it if it is the main control
2157 Node *CatchProjNode::Identity( PhaseTransform *phase ) {
2158 // If my value is control and no other value is, then treat as ID
2159 const TypeTuple *t = phase->type(in(0))->is_tuple();
2160 if (t->field_at(_con) != Type::CONTROL) return this;
2161 // If we remove the last CatchProj and elide the Catch/CatchProj, then we
2162 // also remove any exception table entry. Thus we must know the call
2163 // feeding the Catch will not really throw an exception. This is ok for
2164 // the main fall-thru control (happens when we know a call can never throw
2165 // an exception) or for "rethrow", because a further optimization will
2166 // yank the rethrow (happens when we inline a function that can throw an
2167 // exception and the caller has no handler). Not legal, e.g., for passing
2168 // a NULL receiver to a v-call, or passing bad types to a slow-check-cast.
2169 // These cases MUST throw an exception via the runtime system, so the VM
2170 // will be looking for a table entry.
2171 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode
2172 CallNode *call;
2173 if (_con != TypeFunc::Control && // Bail out if not the main control.
2174 !(proj->is_Proj() && // AND NOT a rethrow
2175 proj->in(0)->is_Call() &&
2176 (call = proj->in(0)->as_Call()) &&
2177 call->entry_point() == OptoRuntime::rethrow_stub()))
2178 return this;
2179
2180 // Search for any other path being control
2181 for (uint i = 0; i < t->cnt(); i++) {
2182 if (i != _con && t->field_at(i) == Type::CONTROL)
2183 return this;
2184 }
2185 // Only my path is possible; I am identity on control to the jump
2186 return in(0)->in(0);
2187 }
2188
2189
2190 #ifndef PRODUCT
2191 void CatchProjNode::dump_spec(outputStream *st) const {
2192 ProjNode::dump_spec(st);
2193 st->print("@bci %d ",_handler_bci);
2194 }
2195 #endif
2196
2197 //=============================================================================
2198 //------------------------------Identity---------------------------------------
2199 // Check for CreateEx being Identity.
2200 Node *CreateExNode::Identity( PhaseTransform *phase ) {
2201 if( phase->type(in(1)) == Type::TOP ) return in(1);
2202 if( phase->type(in(0)) == Type::TOP ) return in(0);
2203 // We only come from CatchProj, unless the CatchProj goes away.
2204 // If the CatchProj is optimized away, then we just carry the
2205 // exception oop through.
2206 CallNode *call = in(1)->in(0)->as_Call();
2207
2208 return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) )
2209 ? this
2210 : call->in(TypeFunc::Parms);
2211 }
2212
2213 //=============================================================================
2214 //------------------------------Value------------------------------------------
2215 // Check for being unreachable.
2216 const Type *NeverBranchNode::Value( PhaseTransform *phase ) const {
2217 if (!in(0) || in(0)->is_top()) return Type::TOP;
2218 return bottom_type();
2219 }
2220
2221 //------------------------------Ideal------------------------------------------
2222 // Check for no longer being part of a loop
2223 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2224 if (can_reshape && !in(0)->is_Loop()) {
2225 // Dead code elimination can sometimes delete this projection so
2226 // if it's not there, there's nothing to do.
2227 Node* fallthru = proj_out(0);
2228 if (fallthru != NULL) {
2229 phase->is_IterGVN()->replace_node(fallthru, in(0));
2230 }
2231 return phase->C->top();
2232 }
2233 return NULL;
2234 }
2235
2236 #ifndef PRODUCT
2237 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const {
2238 st->print("%s", Name());
2239 }
2240 #endif