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