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