1 /*
2 * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "memory/allocation.inline.hpp"
28 #include "oops/objArrayKlass.hpp"
29 #include "opto/addnode.hpp"
30 #include "opto/cfgnode.hpp"
31 #include "opto/connode.hpp"
32 #include "opto/convertnode.hpp"
33 #include "opto/loopnode.hpp"
34 #include "opto/machnode.hpp"
35 #include "opto/movenode.hpp"
36 #include "opto/narrowptrnode.hpp"
37 #include "opto/mulnode.hpp"
38 #include "opto/phaseX.hpp"
39 #include "opto/regmask.hpp"
40 #include "opto/runtime.hpp"
41 #include "opto/subnode.hpp"
42
43 // Portions of code courtesy of Clifford Click
44
45 // Optimization - Graph Style
46
47 //=============================================================================
48 //------------------------------Value------------------------------------------
49 // Compute the type of the RegionNode.
50 const Type *RegionNode::Value( PhaseTransform *phase ) const {
51 for( uint i=1; i<req(); ++i ) { // For all paths in
52 Node *n = in(i); // Get Control source
53 if( !n ) continue; // Missing inputs are TOP
54 if( phase->type(n) == Type::CONTROL )
55 return Type::CONTROL;
56 }
57 return Type::TOP; // All paths dead? Then so are we
58 }
59
60 //------------------------------Identity---------------------------------------
61 // Check for Region being Identity.
62 Node *RegionNode::Identity( PhaseTransform *phase ) {
63 // Cannot have Region be an identity, even if it has only 1 input.
64 // Phi users cannot have their Region input folded away for them,
65 // since they need to select the proper data input
66 return this;
67 }
68
69 //------------------------------merge_region-----------------------------------
70 // If a Region flows into a Region, merge into one big happy merge. This is
71 // hard to do if there is stuff that has to happen
72 static Node *merge_region(RegionNode *region, PhaseGVN *phase) {
73 if( region->Opcode() != Op_Region ) // Do not do to LoopNodes
74 return NULL;
75 Node *progress = NULL; // Progress flag
76 PhaseIterGVN *igvn = phase->is_IterGVN();
77
78 uint rreq = region->req();
79 for( uint i = 1; i < rreq; i++ ) {
80 Node *r = region->in(i);
81 if( r && r->Opcode() == Op_Region && // Found a region?
82 r->in(0) == r && // Not already collapsed?
83 r != region && // Avoid stupid situations
84 r->outcnt() == 2 ) { // Self user and 'region' user only?
85 assert(!r->as_Region()->has_phi(), "no phi users");
86 if( !progress ) { // No progress
87 if (region->has_phi()) {
88 return NULL; // Only flatten if no Phi users
89 // igvn->hash_delete( phi );
90 }
91 igvn->hash_delete( region );
92 progress = region; // Making progress
93 }
94 igvn->hash_delete( r );
95
96 // Append inputs to 'r' onto 'region'
97 for( uint j = 1; j < r->req(); j++ ) {
98 // Move an input from 'r' to 'region'
99 region->add_req(r->in(j));
100 r->set_req(j, phase->C->top());
101 // Update phis of 'region'
102 //for( uint k = 0; k < max; k++ ) {
103 // Node *phi = region->out(k);
104 // if( phi->is_Phi() ) {
105 // phi->add_req(phi->in(i));
106 // }
107 //}
108
109 rreq++; // One more input to Region
110 } // Found a region to merge into Region
111 igvn->_worklist.push(r);
112 // Clobber pointer to the now dead 'r'
113 region->set_req(i, phase->C->top());
114 }
115 }
116
117 return progress;
118 }
119
120
121
122 //--------------------------------has_phi--------------------------------------
123 // Helper function: Return any PhiNode that uses this region or NULL
124 PhiNode* RegionNode::has_phi() const {
125 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
126 Node* phi = fast_out(i);
127 if (phi->is_Phi()) { // Check for Phi users
128 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
129 return phi->as_Phi(); // this one is good enough
130 }
131 }
132
133 return NULL;
134 }
135
136
137 //-----------------------------has_unique_phi----------------------------------
138 // Helper function: Return the only PhiNode that uses this region or NULL
139 PhiNode* RegionNode::has_unique_phi() const {
140 // Check that only one use is a Phi
141 PhiNode* only_phi = NULL;
142 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
143 Node* phi = fast_out(i);
144 if (phi->is_Phi()) { // Check for Phi users
145 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
146 if (only_phi == NULL) {
147 only_phi = phi->as_Phi();
148 } else {
149 return NULL; // multiple phis
150 }
151 }
152 }
153
154 return only_phi;
155 }
156
157
158 //------------------------------check_phi_clipping-----------------------------
159 // Helper function for RegionNode's identification of FP clipping
160 // Check inputs to the Phi
161 static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) {
162 min = NULL;
163 max = NULL;
164 val = NULL;
165 min_idx = 0;
166 max_idx = 0;
167 val_idx = 0;
168 uint phi_max = phi->req();
169 if( phi_max == 4 ) {
170 for( uint j = 1; j < phi_max; ++j ) {
171 Node *n = phi->in(j);
172 int opcode = n->Opcode();
173 switch( opcode ) {
174 case Op_ConI:
175 {
176 if( min == NULL ) {
177 min = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
178 min_idx = j;
179 } else {
180 max = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
181 max_idx = j;
182 if( min->get_int() > max->get_int() ) {
183 // Swap min and max
184 ConNode *temp;
185 uint temp_idx;
186 temp = min; min = max; max = temp;
187 temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx;
188 }
189 }
190 }
191 break;
192 default:
193 {
194 val = n;
195 val_idx = j;
196 }
197 break;
198 }
199 }
200 }
201 return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) );
202 }
203
204
205 //------------------------------check_if_clipping------------------------------
206 // Helper function for RegionNode's identification of FP clipping
207 // Check that inputs to Region come from two IfNodes,
208 //
209 // If
210 // False True
211 // If |
212 // False True |
213 // | | |
214 // RegionNode_inputs
215 //
216 static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) {
217 top_if = NULL;
218 bot_if = NULL;
219
220 // Check control structure above RegionNode for (if ( if ) )
221 Node *in1 = region->in(1);
222 Node *in2 = region->in(2);
223 Node *in3 = region->in(3);
224 // Check that all inputs are projections
225 if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) {
226 Node *in10 = in1->in(0);
227 Node *in20 = in2->in(0);
228 Node *in30 = in3->in(0);
229 // Check that #1 and #2 are ifTrue and ifFalse from same If
230 if( in10 != NULL && in10->is_If() &&
231 in20 != NULL && in20->is_If() &&
232 in30 != NULL && in30->is_If() && in10 == in20 &&
233 (in1->Opcode() != in2->Opcode()) ) {
234 Node *in100 = in10->in(0);
235 Node *in1000 = (in100 != NULL && in100->is_Proj()) ? in100->in(0) : NULL;
236 // Check that control for in10 comes from other branch of IF from in3
237 if( in1000 != NULL && in1000->is_If() &&
238 in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) {
239 // Control pattern checks
240 top_if = (IfNode*)in1000;
241 bot_if = (IfNode*)in10;
242 }
243 }
244 }
245
246 return (top_if != NULL);
247 }
248
249
250 //------------------------------check_convf2i_clipping-------------------------
251 // Helper function for RegionNode's identification of FP clipping
252 // Verify that the value input to the phi comes from "ConvF2I; LShift; RShift"
253 static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) {
254 convf2i = NULL;
255
256 // Check for the RShiftNode
257 Node *rshift = phi->in(idx);
258 assert( rshift, "Previous checks ensure phi input is present");
259 if( rshift->Opcode() != Op_RShiftI ) { return false; }
260
261 // Check for the LShiftNode
262 Node *lshift = rshift->in(1);
263 assert( lshift, "Previous checks ensure phi input is present");
264 if( lshift->Opcode() != Op_LShiftI ) { return false; }
265
266 // Check for the ConvF2INode
267 Node *conv = lshift->in(1);
268 if( conv->Opcode() != Op_ConvF2I ) { return false; }
269
270 // Check that shift amounts are only to get sign bits set after F2I
271 jint max_cutoff = max->get_int();
272 jint min_cutoff = min->get_int();
273 jint left_shift = lshift->in(2)->get_int();
274 jint right_shift = rshift->in(2)->get_int();
275 jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1);
276 if( left_shift != right_shift ||
277 0 > left_shift || left_shift >= BitsPerJavaInteger ||
278 max_post_shift < max_cutoff ||
279 max_post_shift < -min_cutoff ) {
280 // Shifts are necessary but current transformation eliminates them
281 return false;
282 }
283
284 // OK to return the result of ConvF2I without shifting
285 convf2i = (ConvF2INode*)conv;
286 return true;
287 }
288
289
290 //------------------------------check_compare_clipping-------------------------
291 // Helper function for RegionNode's identification of FP clipping
292 static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) {
293 Node *i1 = iff->in(1);
294 if ( !i1->is_Bool() ) { return false; }
295 BoolNode *bool1 = i1->as_Bool();
296 if( less_than && bool1->_test._test != BoolTest::le ) { return false; }
297 else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; }
298 const Node *cmpF = bool1->in(1);
299 if( cmpF->Opcode() != Op_CmpF ) { return false; }
300 // Test that the float value being compared against
301 // is equivalent to the int value used as a limit
302 Node *nodef = cmpF->in(2);
303 if( nodef->Opcode() != Op_ConF ) { return false; }
304 jfloat conf = nodef->getf();
305 jint coni = limit->get_int();
306 if( ((int)conf) != coni ) { return false; }
307 input = cmpF->in(1);
308 return true;
309 }
310
311 //------------------------------is_unreachable_region--------------------------
312 // Find if the Region node is reachable from the root.
313 bool RegionNode::is_unreachable_region(PhaseGVN *phase) const {
314 assert(req() == 2, "");
315
316 // First, cut the simple case of fallthrough region when NONE of
317 // region's phis references itself directly or through a data node.
318 uint max = outcnt();
319 uint i;
320 for (i = 0; i < max; i++) {
321 Node* phi = raw_out(i);
322 if (phi != NULL && phi->is_Phi()) {
323 assert(phase->eqv(phi->in(0), this) && phi->req() == 2, "");
324 if (phi->outcnt() == 0)
325 continue; // Safe case - no loops
326 if (phi->outcnt() == 1) {
327 Node* u = phi->raw_out(0);
328 // Skip if only one use is an other Phi or Call or Uncommon trap.
329 // It is safe to consider this case as fallthrough.
330 if (u != NULL && (u->is_Phi() || u->is_CFG()))
331 continue;
332 }
333 // Check when phi references itself directly or through an other node.
334 if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe)
335 break; // Found possible unsafe data loop.
336 }
337 }
338 if (i >= max)
339 return false; // An unsafe case was NOT found - don't need graph walk.
340
341 // Unsafe case - check if the Region node is reachable from root.
342 ResourceMark rm;
343
344 Arena *a = Thread::current()->resource_area();
345 Node_List nstack(a);
346 VectorSet visited(a);
347
348 // Mark all control nodes reachable from root outputs
349 Node *n = (Node*)phase->C->root();
350 nstack.push(n);
351 visited.set(n->_idx);
352 while (nstack.size() != 0) {
353 n = nstack.pop();
354 uint max = n->outcnt();
355 for (uint i = 0; i < max; i++) {
356 Node* m = n->raw_out(i);
357 if (m != NULL && m->is_CFG()) {
358 if (phase->eqv(m, this)) {
359 return false; // We reached the Region node - it is not dead.
360 }
361 if (!visited.test_set(m->_idx))
362 nstack.push(m);
363 }
364 }
365 }
366
367 return true; // The Region node is unreachable - it is dead.
368 }
369
370 bool RegionNode::try_clean_mem_phi(PhaseGVN *phase) {
371 // Incremental inlining + PhaseStringOpts sometimes produce:
372 //
373 // cmpP with 1 top input
374 // |
375 // If
376 // / \
377 // IfFalse IfTrue /- Some Node
378 // \ / / /
379 // Region / /-MergeMem
380 // \---Phi
381 //
382 //
383 // It's expected by PhaseStringOpts that the Region goes away and is
384 // replaced by If's control input but because there's still a Phi,
385 // the Region stays in the graph. The top input from the cmpP is
386 // propagated forward and a subgraph that is useful goes away. The
387 // code below replaces the Phi with the MergeMem so that the Region
388 // is simplified.
389
390 PhiNode* phi = has_unique_phi();
391 if (phi && phi->type() == Type::MEMORY && req() == 3 && phi->is_diamond_phi(true)) {
392 MergeMemNode* m = NULL;
393 assert(phi->req() == 3, "same as region");
394 for (uint i = 1; i < 3; ++i) {
395 Node *mem = phi->in(i);
396 if (mem && mem->is_MergeMem() && in(i)->outcnt() == 1) {
397 // Nothing is control-dependent on path #i except the region itself.
398 m = mem->as_MergeMem();
399 uint j = 3 - i;
400 Node* other = phi->in(j);
401 if (other && other == m->base_memory()) {
402 // m is a successor memory to other, and is not pinned inside the diamond, so push it out.
403 // This will allow the diamond to collapse completely.
404 phase->is_IterGVN()->replace_node(phi, m);
405 return true;
406 }
407 }
408 }
409 }
410 return false;
411 }
412
413 //------------------------------Ideal------------------------------------------
414 // Return a node which is more "ideal" than the current node. Must preserve
415 // the CFG, but we can still strip out dead paths.
416 Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) {
417 if( !can_reshape && !in(0) ) return NULL; // Already degraded to a Copy
418 assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge");
419
420 // Check for RegionNode with no Phi users and both inputs come from either
421 // arm of the same IF. If found, then the control-flow split is useless.
422 bool has_phis = false;
423 if (can_reshape) { // Need DU info to check for Phi users
424 has_phis = (has_phi() != NULL); // Cache result
425 if (has_phis && try_clean_mem_phi(phase)) {
426 has_phis = false;
427 }
428
429 if (!has_phis) { // No Phi users? Nothing merging?
430 for (uint i = 1; i < req()-1; i++) {
431 Node *if1 = in(i);
432 if( !if1 ) continue;
433 Node *iff = if1->in(0);
434 if( !iff || !iff->is_If() ) continue;
435 for( uint j=i+1; j<req(); j++ ) {
436 if( in(j) && in(j)->in(0) == iff &&
437 if1->Opcode() != in(j)->Opcode() ) {
438 // Add the IF Projections to the worklist. They (and the IF itself)
439 // will be eliminated if dead.
440 phase->is_IterGVN()->add_users_to_worklist(iff);
441 set_req(i, iff->in(0));// Skip around the useless IF diamond
442 set_req(j, NULL);
443 return this; // Record progress
444 }
445 }
446 }
447 }
448 }
449
450 // Remove TOP or NULL input paths. If only 1 input path remains, this Region
451 // degrades to a copy.
452 bool add_to_worklist = false;
453 bool modified = false;
454 int cnt = 0; // Count of values merging
455 DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count
456 int del_it = 0; // The last input path we delete
457 // For all inputs...
458 for( uint i=1; i<req(); ++i ){// For all paths in
459 Node *n = in(i); // Get the input
460 if( n != NULL ) {
461 // Remove useless control copy inputs
462 if( n->is_Region() && n->as_Region()->is_copy() ) {
463 set_req(i, n->nonnull_req());
464 modified = true;
465 i--;
466 continue;
467 }
468 if( n->is_Proj() ) { // Remove useless rethrows
469 Node *call = n->in(0);
470 if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) {
471 set_req(i, call->in(0));
472 modified = true;
473 i--;
474 continue;
475 }
476 }
477 if( phase->type(n) == Type::TOP ) {
478 set_req(i, NULL); // Ignore TOP inputs
479 modified = true;
480 i--;
481 continue;
482 }
483 cnt++; // One more value merging
484
485 } else if (can_reshape) { // Else found dead path with DU info
486 PhaseIterGVN *igvn = phase->is_IterGVN();
487 del_req(i); // Yank path from self
488 del_it = i;
489 uint max = outcnt();
490 DUIterator j;
491 bool progress = true;
492 while(progress) { // Need to establish property over all users
493 progress = false;
494 for (j = outs(); has_out(j); j++) {
495 Node *n = out(j);
496 if( n->req() != req() && n->is_Phi() ) {
497 assert( n->in(0) == this, "" );
498 igvn->hash_delete(n); // Yank from hash before hacking edges
499 n->set_req_X(i,NULL,igvn);// Correct DU info
500 n->del_req(i); // Yank path from Phis
501 if( max != outcnt() ) {
502 progress = true;
503 j = refresh_out_pos(j);
504 max = outcnt();
505 }
506 }
507 }
508 }
509 add_to_worklist = true;
510 i--;
511 }
512 }
513
514 if (can_reshape && cnt == 1) {
515 // Is it dead loop?
516 // If it is LoopNopde it had 2 (+1 itself) inputs and
517 // one of them was cut. The loop is dead if it was EntryContol.
518 // Loop node may have only one input because entry path
519 // is removed in PhaseIdealLoop::Dominators().
520 assert(!this->is_Loop() || cnt_orig <= 3, "Loop node should have 3 or less inputs");
521 if (this->is_Loop() && (del_it == LoopNode::EntryControl ||
522 del_it == 0 && is_unreachable_region(phase)) ||
523 !this->is_Loop() && has_phis && is_unreachable_region(phase)) {
524 // Yes, the region will be removed during the next step below.
525 // Cut the backedge input and remove phis since no data paths left.
526 // We don't cut outputs to other nodes here since we need to put them
527 // on the worklist.
528 PhaseIterGVN *igvn = phase->is_IterGVN();
529 if (in(1)->outcnt() == 1) {
530 igvn->_worklist.push(in(1));
531 }
532 del_req(1);
533 cnt = 0;
534 assert( req() == 1, "no more inputs expected" );
535 uint max = outcnt();
536 bool progress = true;
537 Node *top = phase->C->top();
538 DUIterator j;
539 while(progress) {
540 progress = false;
541 for (j = outs(); has_out(j); j++) {
542 Node *n = out(j);
543 if( n->is_Phi() ) {
544 assert( igvn->eqv(n->in(0), this), "" );
545 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
546 // Break dead loop data path.
547 // Eagerly replace phis with top to avoid phis copies generation.
548 igvn->replace_node(n, top);
549 if( max != outcnt() ) {
550 progress = true;
551 j = refresh_out_pos(j);
552 max = outcnt();
553 }
554 }
555 }
556 }
557 add_to_worklist = true;
558 }
559 }
560 if (add_to_worklist) {
561 phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis
562 }
563
564 if( cnt <= 1 ) { // Only 1 path in?
565 set_req(0, NULL); // Null control input for region copy
566 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is.
567 // No inputs or all inputs are NULL.
568 return NULL;
569 } else if (can_reshape) { // Optimization phase - remove the node
570 PhaseIterGVN *igvn = phase->is_IterGVN();
571 Node *parent_ctrl;
572 if( cnt == 0 ) {
573 assert( req() == 1, "no inputs expected" );
574 // During IGVN phase such region will be subsumed by TOP node
575 // so region's phis will have TOP as control node.
576 // Kill phis here to avoid it. PhiNode::is_copy() will be always false.
577 // Also set other user's input to top.
578 parent_ctrl = phase->C->top();
579 } else {
580 // The fallthrough case since we already checked dead loops above.
581 parent_ctrl = in(1);
582 assert(parent_ctrl != NULL, "Region is a copy of some non-null control");
583 assert(!igvn->eqv(parent_ctrl, this), "Close dead loop");
584 }
585 if (!add_to_worklist)
586 igvn->add_users_to_worklist(this); // Check for further allowed opts
587 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
588 Node* n = last_out(i);
589 igvn->hash_delete(n); // Remove from worklist before modifying edges
590 if( n->is_Phi() ) { // Collapse all Phis
591 // Eagerly replace phis to avoid copies generation.
592 Node* in;
593 if( cnt == 0 ) {
594 assert( n->req() == 1, "No data inputs expected" );
595 in = parent_ctrl; // replaced by top
596 } else {
597 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
598 in = n->in(1); // replaced by unique input
599 if( n->as_Phi()->is_unsafe_data_reference(in) )
600 in = phase->C->top(); // replaced by top
601 }
602 igvn->replace_node(n, in);
603 }
604 else if( n->is_Region() ) { // Update all incoming edges
605 assert( !igvn->eqv(n, this), "Must be removed from DefUse edges");
606 uint uses_found = 0;
607 for( uint k=1; k < n->req(); k++ ) {
608 if( n->in(k) == this ) {
609 n->set_req(k, parent_ctrl);
610 uses_found++;
611 }
612 }
613 if( uses_found > 1 ) { // (--i) done at the end of the loop.
614 i -= (uses_found - 1);
615 }
616 }
617 else {
618 assert( igvn->eqv(n->in(0), this), "Expect RegionNode to be control parent");
619 n->set_req(0, parent_ctrl);
620 }
621 #ifdef ASSERT
622 for( uint k=0; k < n->req(); k++ ) {
623 assert( !igvn->eqv(n->in(k), this), "All uses of RegionNode should be gone");
624 }
625 #endif
626 }
627 // Remove the RegionNode itself from DefUse info
628 igvn->remove_dead_node(this);
629 return NULL;
630 }
631 return this; // Record progress
632 }
633
634
635 // If a Region flows into a Region, merge into one big happy merge.
636 if (can_reshape) {
637 Node *m = merge_region(this, phase);
638 if (m != NULL) return m;
639 }
640
641 // Check if this region is the root of a clipping idiom on floats
642 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
643 // Check that only one use is a Phi and that it simplifies to two constants +
644 PhiNode* phi = has_unique_phi();
645 if (phi != NULL) { // One Phi user
646 // Check inputs to the Phi
647 ConNode *min;
648 ConNode *max;
649 Node *val;
650 uint min_idx;
651 uint max_idx;
652 uint val_idx;
653 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) {
654 IfNode *top_if;
655 IfNode *bot_if;
656 if( check_if_clipping( this, bot_if, top_if ) ) {
657 // Control pattern checks, now verify compares
658 Node *top_in = NULL; // value being compared against
659 Node *bot_in = NULL;
660 if( check_compare_clipping( true, bot_if, min, bot_in ) &&
661 check_compare_clipping( false, top_if, max, top_in ) ) {
662 if( bot_in == top_in ) {
663 PhaseIterGVN *gvn = phase->is_IterGVN();
664 assert( gvn != NULL, "Only had DefUse info in IterGVN");
665 // Only remaining check is that bot_in == top_in == (Phi's val + mods)
666
667 // Check for the ConvF2INode
668 ConvF2INode *convf2i;
669 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
670 convf2i->in(1) == bot_in ) {
671 // Matched pattern, including LShiftI; RShiftI, replace with integer compares
672 // max test
673 Node *cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, min ));
674 Node *boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::lt ));
675 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt ));
676 Node *if_min= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
677 Node *ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
678 // min test
679 cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, max ));
680 boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::gt ));
681 iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
682 Node *if_max= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
683 ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
684 // update input edges to region node
685 set_req_X( min_idx, if_min, gvn );
686 set_req_X( max_idx, if_max, gvn );
687 set_req_X( val_idx, ifF, gvn );
688 // remove unnecessary 'LShiftI; RShiftI' idiom
689 gvn->hash_delete(phi);
690 phi->set_req_X( val_idx, convf2i, gvn );
691 gvn->hash_find_insert(phi);
692 // Return transformed region node
693 return this;
694 }
695 }
696 }
697 }
698 }
699 }
700 }
701
702 return modified ? this : NULL;
703 }
704
705
706
707 const RegMask &RegionNode::out_RegMask() const {
708 return RegMask::Empty;
709 }
710
711 // Find the one non-null required input. RegionNode only
712 Node *Node::nonnull_req() const {
713 assert( is_Region(), "" );
714 for( uint i = 1; i < _cnt; i++ )
715 if( in(i) )
716 return in(i);
717 ShouldNotReachHere();
718 return NULL;
719 }
720
721
722 //=============================================================================
723 // note that these functions assume that the _adr_type field is flattened
724 uint PhiNode::hash() const {
725 const Type* at = _adr_type;
726 return TypeNode::hash() + (at ? at->hash() : 0);
727 }
728 uint PhiNode::cmp( const Node &n ) const {
729 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
730 }
731 static inline
732 const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
733 if (at == NULL || at == TypePtr::BOTTOM) return at;
734 return Compile::current()->alias_type(at)->adr_type();
735 }
736
737 //----------------------------make---------------------------------------------
738 // create a new phi with edges matching r and set (initially) to x
739 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
740 uint preds = r->req(); // Number of predecessor paths
741 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at");
742 PhiNode* p = new PhiNode(r, t, at);
743 for (uint j = 1; j < preds; j++) {
744 // Fill in all inputs, except those which the region does not yet have
745 if (r->in(j) != NULL)
746 p->init_req(j, x);
747 }
748 return p;
749 }
750 PhiNode* PhiNode::make(Node* r, Node* x) {
751 const Type* t = x->bottom_type();
752 const TypePtr* at = NULL;
753 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
754 return make(r, x, t, at);
755 }
756 PhiNode* PhiNode::make_blank(Node* r, Node* x) {
757 const Type* t = x->bottom_type();
758 const TypePtr* at = NULL;
759 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
760 return new PhiNode(r, t, at);
761 }
762
763
764 //------------------------slice_memory-----------------------------------------
765 // create a new phi with narrowed memory type
766 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
767 PhiNode* mem = (PhiNode*) clone();
768 *(const TypePtr**)&mem->_adr_type = adr_type;
769 // convert self-loops, or else we get a bad graph
770 for (uint i = 1; i < req(); i++) {
771 if ((const Node*)in(i) == this) mem->set_req(i, mem);
772 }
773 mem->verify_adr_type();
774 return mem;
775 }
776
777 //------------------------split_out_instance-----------------------------------
778 // Split out an instance type from a bottom phi.
779 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const {
780 const TypeOopPtr *t_oop = at->isa_oopptr();
781 assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr");
782 const TypePtr *t = adr_type();
783 assert(type() == Type::MEMORY &&
784 (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
785 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
786 t->is_oopptr()->cast_to_exactness(true)
787 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
788 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop),
789 "bottom or raw memory required");
790
791 // Check if an appropriate node already exists.
792 Node *region = in(0);
793 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) {
794 Node* use = region->fast_out(k);
795 if( use->is_Phi()) {
796 PhiNode *phi2 = use->as_Phi();
797 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) {
798 return phi2;
799 }
800 }
801 }
802 Compile *C = igvn->C;
803 Arena *a = Thread::current()->resource_area();
804 Node_Array node_map = new Node_Array(a);
805 Node_Stack stack(a, C->live_nodes() >> 4);
806 PhiNode *nphi = slice_memory(at);
807 igvn->register_new_node_with_optimizer( nphi );
808 node_map.map(_idx, nphi);
809 stack.push((Node *)this, 1);
810 while(!stack.is_empty()) {
811 PhiNode *ophi = stack.node()->as_Phi();
812 uint i = stack.index();
813 assert(i >= 1, "not control edge");
814 stack.pop();
815 nphi = node_map[ophi->_idx]->as_Phi();
816 for (; i < ophi->req(); i++) {
817 Node *in = ophi->in(i);
818 if (in == NULL || igvn->type(in) == Type::TOP)
819 continue;
820 Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, NULL, igvn);
821 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL;
822 if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) {
823 opt = node_map[optphi->_idx];
824 if (opt == NULL) {
825 stack.push(ophi, i);
826 nphi = optphi->slice_memory(at);
827 igvn->register_new_node_with_optimizer( nphi );
828 node_map.map(optphi->_idx, nphi);
829 ophi = optphi;
830 i = 0; // will get incremented at top of loop
831 continue;
832 }
833 }
834 nphi->set_req(i, opt);
835 }
836 }
837 return nphi;
838 }
839
840 //------------------------verify_adr_type--------------------------------------
841 #ifdef ASSERT
842 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
843 if (visited.test_set(_idx)) return; //already visited
844
845 // recheck constructor invariants:
846 verify_adr_type(false);
847
848 // recheck local phi/phi consistency:
849 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
850 "adr_type must be consistent across phi nest");
851
852 // walk around
853 for (uint i = 1; i < req(); i++) {
854 Node* n = in(i);
855 if (n == NULL) continue;
856 const Node* np = in(i);
857 if (np->is_Phi()) {
858 np->as_Phi()->verify_adr_type(visited, at);
859 } else if (n->bottom_type() == Type::TOP
860 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
861 // ignore top inputs
862 } else {
863 const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
864 // recheck phi/non-phi consistency at leaves:
865 assert((nat != NULL) == (at != NULL), "");
866 assert(nat == at || nat == TypePtr::BOTTOM,
867 "adr_type must be consistent at leaves of phi nest");
868 }
869 }
870 }
871
872 // Verify a whole nest of phis rooted at this one.
873 void PhiNode::verify_adr_type(bool recursive) const {
874 if (is_error_reported()) return; // muzzle asserts when debugging an error
875 if (Node::in_dump()) return; // muzzle asserts when printing
876
877 assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only");
878
879 if (!VerifyAliases) return; // verify thoroughly only if requested
880
881 assert(_adr_type == flatten_phi_adr_type(_adr_type),
882 "Phi::adr_type must be pre-normalized");
883
884 if (recursive) {
885 VectorSet visited(Thread::current()->resource_area());
886 verify_adr_type(visited, _adr_type);
887 }
888 }
889 #endif
890
891
892 //------------------------------Value------------------------------------------
893 // Compute the type of the PhiNode
894 const Type *PhiNode::Value( PhaseTransform *phase ) const {
895 Node *r = in(0); // RegionNode
896 if( !r ) // Copy or dead
897 return in(1) ? phase->type(in(1)) : Type::TOP;
898
899 // Note: During parsing, phis are often transformed before their regions.
900 // This means we have to use type_or_null to defend against untyped regions.
901 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
902 return Type::TOP;
903
904 // Check for trip-counted loop. If so, be smarter.
905 CountedLoopNode *l = r->is_CountedLoop() ? r->as_CountedLoop() : NULL;
906 if( l && l->can_be_counted_loop(phase) &&
907 ((const Node*)l->phi() == this) ) { // Trip counted loop!
908 // protect against init_trip() or limit() returning NULL
909 const Node *init = l->init_trip();
910 const Node *limit = l->limit();
911 if( init != NULL && limit != NULL && l->stride_is_con() ) {
912 const TypeInt *lo = init ->bottom_type()->isa_int();
913 const TypeInt *hi = limit->bottom_type()->isa_int();
914 if( lo && hi ) { // Dying loops might have TOP here
915 int stride = l->stride_con();
916 if( stride < 0 ) { // Down-counter loop
917 const TypeInt *tmp = lo; lo = hi; hi = tmp;
918 stride = -stride;
919 }
920 if( lo->_hi < hi->_lo ) // Reversed endpoints are well defined :-(
921 return TypeInt::make(lo->_lo,hi->_hi,3);
922 }
923 }
924 }
925
926 // Until we have harmony between classes and interfaces in the type
927 // lattice, we must tread carefully around phis which implicitly
928 // convert the one to the other.
929 const TypePtr* ttp = _type->make_ptr();
930 const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL;
931 const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_klassptr() : NULL;
932 bool is_intf = false;
933 if (ttip != NULL) {
934 ciKlass* k = ttip->klass();
935 if (k->is_loaded() && k->is_interface())
936 is_intf = true;
937 }
938 if (ttkp != NULL) {
939 ciKlass* k = ttkp->klass();
940 if (k->is_loaded() && k->is_interface())
941 is_intf = true;
942 }
943
944 // Default case: merge all inputs
945 const Type *t = Type::TOP; // Merged type starting value
946 for (uint i = 1; i < req(); ++i) {// For all paths in
947 // Reachable control path?
948 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
949 const Type* ti = phase->type(in(i));
950 // We assume that each input of an interface-valued Phi is a true
951 // subtype of that interface. This might not be true of the meet
952 // of all the input types. The lattice is not distributive in
953 // such cases. Ward off asserts in type.cpp by refusing to do
954 // meets between interfaces and proper classes.
955 const TypePtr* tip = ti->make_ptr();
956 const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL;
957 if (tiip) {
958 bool ti_is_intf = false;
959 ciKlass* k = tiip->klass();
960 if (k->is_loaded() && k->is_interface())
961 ti_is_intf = true;
962 if (is_intf != ti_is_intf)
963 { t = _type; break; }
964 }
965 t = t->meet_speculative(ti);
966 }
967 }
968
969 // The worst-case type (from ciTypeFlow) should be consistent with "t".
970 // That is, we expect that "t->higher_equal(_type)" holds true.
971 // There are various exceptions:
972 // - Inputs which are phis might in fact be widened unnecessarily.
973 // For example, an input might be a widened int while the phi is a short.
974 // - Inputs might be BotPtrs but this phi is dependent on a null check,
975 // and postCCP has removed the cast which encodes the result of the check.
976 // - The type of this phi is an interface, and the inputs are classes.
977 // - Value calls on inputs might produce fuzzy results.
978 // (Occurrences of this case suggest improvements to Value methods.)
979 //
980 // It is not possible to see Type::BOTTOM values as phi inputs,
981 // because the ciTypeFlow pre-pass produces verifier-quality types.
982 const Type* ft = t->filter_speculative(_type); // Worst case type
983
984 #ifdef ASSERT
985 // The following logic has been moved into TypeOopPtr::filter.
986 const Type* jt = t->join_speculative(_type);
987 if (jt->empty()) { // Emptied out???
988
989 // Check for evil case of 't' being a class and '_type' expecting an
990 // interface. This can happen because the bytecodes do not contain
991 // enough type info to distinguish a Java-level interface variable
992 // from a Java-level object variable. If we meet 2 classes which
993 // both implement interface I, but their meet is at 'j/l/O' which
994 // doesn't implement I, we have no way to tell if the result should
995 // be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows
996 // into a Phi which "knows" it's an Interface type we'll have to
997 // uplift the type.
998 if (!t->empty() && ttip && ttip->is_loaded() && ttip->klass()->is_interface()) {
999 assert(ft == _type, ""); // Uplift to interface
1000 }
1001 else if (!t->empty() && ttkp && ttkp->is_loaded() && ttkp->klass()->is_interface()) {
1002 assert(ft == _type, ""); // Uplift to interface
1003 }
1004 else {
1005 // We also have to handle 'evil cases' of interface- vs. class-arrays
1006 const TypeAryPtr* ftap = jt->isa_aryptr();
1007 const TypeAryPtr* ktap = _type->isa_aryptr();
1008 if (!t->empty() && ftap != NULL && ktap != NULL) {
1009 // Handle multidimensional arrays
1010 const TypePtr* ftp = ftap->elem()->make_ptr();
1011 const TypePtr* ktp = ktap->elem()->make_ptr();
1012 while (ftp && ftp->isa_aryptr() && ktp && ktp->isa_aryptr()) {
1013 ftap = ftp->is_aryptr();
1014 ktap = ktp->is_aryptr();
1015 ftp = ftap->elem()->make_ptr();
1016 ktp = ktap->elem()->make_ptr();
1017 }
1018 const TypeInstPtr* ktip = ktp ? ktp->isa_instptr() : NULL;
1019 if (ktip != NULL && ktip->is_loaded() && ktip->klass()->is_interface()) {
1020 assert(ft == _type, ""); // Uplift to array of interface
1021 }
1022 else {
1023 // Otherwise it's something stupid like non-overlapping int ranges
1024 // found on dying counted loops.
1025 assert(ft == Type::TOP, ""); // Canonical empty value
1026 }
1027 }
1028 else {
1029 assert(ft == Type::TOP, ""); // Canonical empty value
1030 }
1031 }
1032 }
1033
1034 else {
1035
1036 // If we have an interface-typed Phi and we narrow to a class type, the join
1037 // should report back the class. However, if we have a J/L/Object
1038 // class-typed Phi and an interface flows in, it's possible that the meet &
1039 // join report an interface back out. This isn't possible but happens
1040 // because the type system doesn't interact well with interfaces.
1041 const TypePtr *jtp = jt->make_ptr();
1042 const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL;
1043 const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_klassptr() : NULL;
1044 if( jtip && ttip ) {
1045 if( jtip->is_loaded() && jtip->klass()->is_interface() &&
1046 ttip->is_loaded() && !ttip->klass()->is_interface() ) {
1047 assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) ||
1048 ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), "");
1049 jt = ft;
1050 }
1051 }
1052 if( jtkp && ttkp ) {
1053 if( jtkp->is_loaded() && jtkp->klass()->is_interface() &&
1054 !jtkp->klass_is_exact() && // Keep exact interface klass (6894807)
1055 ttkp->is_loaded() && !ttkp->klass()->is_interface() ) {
1056 assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) ||
1057 ft->isa_narrowklass() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), "");
1058 jt = ft;
1059 }
1060 }
1061 if (jt != ft && jt->base() == ft->base()) {
1062 if (jt->isa_int() &&
1063 jt->is_int()->_lo == ft->is_int()->_lo &&
1064 jt->is_int()->_hi == ft->is_int()->_hi)
1065 jt = ft;
1066 if (jt->isa_long() &&
1067 jt->is_long()->_lo == ft->is_long()->_lo &&
1068 jt->is_long()->_hi == ft->is_long()->_hi)
1069 jt = ft;
1070 }
1071 if (jt != ft) {
1072 tty->print("merge type: "); t->dump(); tty->cr();
1073 tty->print("kill type: "); _type->dump(); tty->cr();
1074 tty->print("join type: "); jt->dump(); tty->cr();
1075 tty->print("filter type: "); ft->dump(); tty->cr();
1076 }
1077 assert(jt == ft, "");
1078 }
1079 #endif //ASSERT
1080
1081 // Deal with conversion problems found in data loops.
1082 ft = phase->saturate(ft, phase->type_or_null(this), _type);
1083
1084 return ft;
1085 }
1086
1087
1088 //------------------------------is_diamond_phi---------------------------------
1089 // Does this Phi represent a simple well-shaped diamond merge? Return the
1090 // index of the true path or 0 otherwise.
1091 // If check_control_only is true, do not inspect the If node at the
1092 // top, and return -1 (not an edge number) on success.
1093 int PhiNode::is_diamond_phi(bool check_control_only) const {
1094 // Check for a 2-path merge
1095 Node *region = in(0);
1096 if( !region ) return 0;
1097 if( region->req() != 3 ) return 0;
1098 if( req() != 3 ) return 0;
1099 // Check that both paths come from the same If
1100 Node *ifp1 = region->in(1);
1101 Node *ifp2 = region->in(2);
1102 if( !ifp1 || !ifp2 ) return 0;
1103 Node *iff = ifp1->in(0);
1104 if( !iff || !iff->is_If() ) return 0;
1105 if( iff != ifp2->in(0) ) return 0;
1106 if (check_control_only) return -1;
1107 // Check for a proper bool/cmp
1108 const Node *b = iff->in(1);
1109 if( !b->is_Bool() ) return 0;
1110 const Node *cmp = b->in(1);
1111 if( !cmp->is_Cmp() ) return 0;
1112
1113 // Check for branching opposite expected
1114 if( ifp2->Opcode() == Op_IfTrue ) {
1115 assert( ifp1->Opcode() == Op_IfFalse, "" );
1116 return 2;
1117 } else {
1118 assert( ifp1->Opcode() == Op_IfTrue, "" );
1119 return 1;
1120 }
1121 }
1122
1123 //----------------------------check_cmove_id-----------------------------------
1124 // Check for CMove'ing a constant after comparing against the constant.
1125 // Happens all the time now, since if we compare equality vs a constant in
1126 // the parser, we "know" the variable is constant on one path and we force
1127 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
1128 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more
1129 // general in that we don't need constants. Since CMove's are only inserted
1130 // in very special circumstances, we do it here on generic Phi's.
1131 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
1132 assert(true_path !=0, "only diamond shape graph expected");
1133
1134 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1135 // phi->region->if_proj->ifnode->bool->cmp
1136 Node* region = in(0);
1137 Node* iff = region->in(1)->in(0);
1138 BoolNode* b = iff->in(1)->as_Bool();
1139 Node* cmp = b->in(1);
1140 Node* tval = in(true_path);
1141 Node* fval = in(3-true_path);
1142 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
1143 if (id == NULL)
1144 return NULL;
1145
1146 // Either value might be a cast that depends on a branch of 'iff'.
1147 // Since the 'id' value will float free of the diamond, either
1148 // decast or return failure.
1149 Node* ctl = id->in(0);
1150 if (ctl != NULL && ctl->in(0) == iff) {
1151 if (id->is_ConstraintCast()) {
1152 return id->in(1);
1153 } else {
1154 // Don't know how to disentangle this value.
1155 return NULL;
1156 }
1157 }
1158
1159 return id;
1160 }
1161
1162 //------------------------------Identity---------------------------------------
1163 // Check for Region being Identity.
1164 Node *PhiNode::Identity( PhaseTransform *phase ) {
1165 // Check for no merging going on
1166 // (There used to be special-case code here when this->region->is_Loop.
1167 // It would check for a tributary phi on the backedge that the main phi
1168 // trivially, perhaps with a single cast. The unique_input method
1169 // does all this and more, by reducing such tributaries to 'this'.)
1170 Node* uin = unique_input(phase);
1171 if (uin != NULL) {
1172 return uin;
1173 }
1174
1175 int true_path = is_diamond_phi();
1176 if (true_path != 0) {
1177 Node* id = is_cmove_id(phase, true_path);
1178 if (id != NULL) return id;
1179 }
1180
1181 return this; // No identity
1182 }
1183
1184 //-----------------------------unique_input------------------------------------
1185 // Find the unique value, discounting top, self-loops, and casts.
1186 // Return top if there are no inputs, and self if there are multiple.
1187 Node* PhiNode::unique_input(PhaseTransform* phase) {
1188 // 1) One unique direct input, or
1189 // 2) some of the inputs have an intervening ConstraintCast and
1190 // the type of input is the same or sharper (more specific)
1191 // than the phi's type.
1192 // 3) an input is a self loop
1193 //
1194 // 1) input or 2) input or 3) input __
1195 // / \ / \ \ / \
1196 // \ / | cast phi cast
1197 // phi \ / / \ /
1198 // phi / --
1199
1200 Node* r = in(0); // RegionNode
1201 if (r == NULL) return in(1); // Already degraded to a Copy
1202 Node* uncasted_input = NULL; // The unique uncasted input (ConstraintCasts removed)
1203 Node* direct_input = NULL; // The unique direct input
1204
1205 for (uint i = 1, cnt = req(); i < cnt; ++i) {
1206 Node* rc = r->in(i);
1207 if (rc == NULL || phase->type(rc) == Type::TOP)
1208 continue; // ignore unreachable control path
1209 Node* n = in(i);
1210 if (n == NULL)
1211 continue;
1212 Node* un = n->uncast();
1213 if (un == NULL || un == this || phase->type(un) == Type::TOP) {
1214 continue; // ignore if top, or in(i) and "this" are in a data cycle
1215 }
1216 // Check for a unique uncasted input
1217 if (uncasted_input == NULL) {
1218 uncasted_input = un;
1219 } else if (uncasted_input != un) {
1220 uncasted_input = NodeSentinel; // no unique uncasted input
1221 }
1222 // Check for a unique direct input
1223 if (direct_input == NULL) {
1224 direct_input = n;
1225 } else if (direct_input != n) {
1226 direct_input = NodeSentinel; // no unique direct input
1227 }
1228 }
1229 if (direct_input == NULL) {
1230 return phase->C->top(); // no inputs
1231 }
1232 assert(uncasted_input != NULL,"");
1233
1234 if (direct_input != NodeSentinel) {
1235 return direct_input; // one unique direct input
1236 }
1237 if (uncasted_input != NodeSentinel &&
1238 phase->type(uncasted_input)->higher_equal(type())) {
1239 return uncasted_input; // one unique uncasted input
1240 }
1241
1242 // Nothing.
1243 return NULL;
1244 }
1245
1246 //------------------------------is_x2logic-------------------------------------
1247 // Check for simple convert-to-boolean pattern
1248 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
1249 // Convert Phi to an ConvIB.
1250 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
1251 assert(true_path !=0, "only diamond shape graph expected");
1252 // Convert the true/false index into an expected 0/1 return.
1253 // Map 2->0 and 1->1.
1254 int flipped = 2-true_path;
1255
1256 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1257 // phi->region->if_proj->ifnode->bool->cmp
1258 Node *region = phi->in(0);
1259 Node *iff = region->in(1)->in(0);
1260 BoolNode *b = (BoolNode*)iff->in(1);
1261 const CmpNode *cmp = (CmpNode*)b->in(1);
1262
1263 Node *zero = phi->in(1);
1264 Node *one = phi->in(2);
1265 const Type *tzero = phase->type( zero );
1266 const Type *tone = phase->type( one );
1267
1268 // Check for compare vs 0
1269 const Type *tcmp = phase->type(cmp->in(2));
1270 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
1271 // Allow cmp-vs-1 if the other input is bounded by 0-1
1272 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
1273 return NULL;
1274 flipped = 1-flipped; // Test is vs 1 instead of 0!
1275 }
1276
1277 // Check for setting zero/one opposite expected
1278 if( tzero == TypeInt::ZERO ) {
1279 if( tone == TypeInt::ONE ) {
1280 } else return NULL;
1281 } else if( tzero == TypeInt::ONE ) {
1282 if( tone == TypeInt::ZERO ) {
1283 flipped = 1-flipped;
1284 } else return NULL;
1285 } else return NULL;
1286
1287 // Check for boolean test backwards
1288 if( b->_test._test == BoolTest::ne ) {
1289 } else if( b->_test._test == BoolTest::eq ) {
1290 flipped = 1-flipped;
1291 } else return NULL;
1292
1293 // Build int->bool conversion
1294 Node *n = new Conv2BNode( cmp->in(1) );
1295 if( flipped )
1296 n = new XorINode( phase->transform(n), phase->intcon(1) );
1297
1298 return n;
1299 }
1300
1301 //------------------------------is_cond_add------------------------------------
1302 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;"
1303 // To be profitable the control flow has to disappear; there can be no other
1304 // values merging here. We replace the test-and-branch with:
1305 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by
1306 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
1307 // Then convert Y to 0-or-Y and finally add.
1308 // This is a key transform for SpecJava _201_compress.
1309 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
1310 assert(true_path !=0, "only diamond shape graph expected");
1311
1312 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1313 // phi->region->if_proj->ifnode->bool->cmp
1314 RegionNode *region = (RegionNode*)phi->in(0);
1315 Node *iff = region->in(1)->in(0);
1316 BoolNode* b = iff->in(1)->as_Bool();
1317 const CmpNode *cmp = (CmpNode*)b->in(1);
1318
1319 // Make sure only merging this one phi here
1320 if (region->has_unique_phi() != phi) return NULL;
1321
1322 // Make sure each arm of the diamond has exactly one output, which we assume
1323 // is the region. Otherwise, the control flow won't disappear.
1324 if (region->in(1)->outcnt() != 1) return NULL;
1325 if (region->in(2)->outcnt() != 1) return NULL;
1326
1327 // Check for "(P < Q)" of type signed int
1328 if (b->_test._test != BoolTest::lt) return NULL;
1329 if (cmp->Opcode() != Op_CmpI) return NULL;
1330
1331 Node *p = cmp->in(1);
1332 Node *q = cmp->in(2);
1333 Node *n1 = phi->in( true_path);
1334 Node *n2 = phi->in(3-true_path);
1335
1336 int op = n1->Opcode();
1337 if( op != Op_AddI // Need zero as additive identity
1338 /*&&op != Op_SubI &&
1339 op != Op_AddP &&
1340 op != Op_XorI &&
1341 op != Op_OrI*/ )
1342 return NULL;
1343
1344 Node *x = n2;
1345 Node *y = NULL;
1346 if( x == n1->in(1) ) {
1347 y = n1->in(2);
1348 } else if( x == n1->in(2) ) {
1349 y = n1->in(1);
1350 } else return NULL;
1351
1352 // Not so profitable if compare and add are constants
1353 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
1354 return NULL;
1355
1356 Node *cmplt = phase->transform( new CmpLTMaskNode(p,q) );
1357 Node *j_and = phase->transform( new AndINode(cmplt,y) );
1358 return new AddINode(j_and,x);
1359 }
1360
1361 //------------------------------is_absolute------------------------------------
1362 // Check for absolute value.
1363 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
1364 assert(true_path !=0, "only diamond shape graph expected");
1365
1366 int cmp_zero_idx = 0; // Index of compare input where to look for zero
1367 int phi_x_idx = 0; // Index of phi input where to find naked x
1368
1369 // ABS ends with the merge of 2 control flow paths.
1370 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
1371 int false_path = 3 - true_path;
1372
1373 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1374 // phi->region->if_proj->ifnode->bool->cmp
1375 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
1376
1377 // Check bool sense
1378 switch( bol->_test._test ) {
1379 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break;
1380 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1381 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1382 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
1383 default: return NULL; break;
1384 }
1385
1386 // Test is next
1387 Node *cmp = bol->in(1);
1388 const Type *tzero = NULL;
1389 switch( cmp->Opcode() ) {
1390 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS
1391 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS
1392 default: return NULL;
1393 }
1394
1395 // Find zero input of compare; the other input is being abs'd
1396 Node *x = NULL;
1397 bool flip = false;
1398 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
1399 x = cmp->in(3 - cmp_zero_idx);
1400 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
1401 // The test is inverted, we should invert the result...
1402 x = cmp->in(cmp_zero_idx);
1403 flip = true;
1404 } else {
1405 return NULL;
1406 }
1407
1408 // Next get the 2 pieces being selected, one is the original value
1409 // and the other is the negated value.
1410 if( phi_root->in(phi_x_idx) != x ) return NULL;
1411
1412 // Check other phi input for subtract node
1413 Node *sub = phi_root->in(3 - phi_x_idx);
1414
1415 // Allow only Sub(0,X) and fail out for all others; Neg is not OK
1416 if( tzero == TypeF::ZERO ) {
1417 if( sub->Opcode() != Op_SubF ||
1418 sub->in(2) != x ||
1419 phase->type(sub->in(1)) != tzero ) return NULL;
1420 x = new AbsFNode(x);
1421 if (flip) {
1422 x = new SubFNode(sub->in(1), phase->transform(x));
1423 }
1424 } else {
1425 if( sub->Opcode() != Op_SubD ||
1426 sub->in(2) != x ||
1427 phase->type(sub->in(1)) != tzero ) return NULL;
1428 x = new AbsDNode(x);
1429 if (flip) {
1430 x = new SubDNode(sub->in(1), phase->transform(x));
1431 }
1432 }
1433
1434 return x;
1435 }
1436
1437 //------------------------------split_once-------------------------------------
1438 // Helper for split_flow_path
1439 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
1440 igvn->hash_delete(n); // Remove from hash before hacking edges
1441
1442 uint j = 1;
1443 for (uint i = phi->req()-1; i > 0; i--) {
1444 if (phi->in(i) == val) { // Found a path with val?
1445 // Add to NEW Region/Phi, no DU info
1446 newn->set_req( j++, n->in(i) );
1447 // Remove from OLD Region/Phi
1448 n->del_req(i);
1449 }
1450 }
1451
1452 // Register the new node but do not transform it. Cannot transform until the
1453 // entire Region/Phi conglomerate has been hacked as a single huge transform.
1454 igvn->register_new_node_with_optimizer( newn );
1455
1456 // Now I can point to the new node.
1457 n->add_req(newn);
1458 igvn->_worklist.push(n);
1459 }
1460
1461 //------------------------------split_flow_path--------------------------------
1462 // Check for merging identical values and split flow paths
1463 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) {
1464 BasicType bt = phi->type()->basic_type();
1465 if( bt == T_ILLEGAL || type2size[bt] <= 0 )
1466 return NULL; // Bail out on funny non-value stuff
1467 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a
1468 return NULL; // third unequal input to be worth doing
1469
1470 // Scan for a constant
1471 uint i;
1472 for( i = 1; i < phi->req()-1; i++ ) {
1473 Node *n = phi->in(i);
1474 if( !n ) return NULL;
1475 if( phase->type(n) == Type::TOP ) return NULL;
1476 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN || n->Opcode() == Op_ConNKlass )
1477 break;
1478 }
1479 if( i >= phi->req() ) // Only split for constants
1480 return NULL;
1481
1482 Node *val = phi->in(i); // Constant to split for
1483 uint hit = 0; // Number of times it occurs
1484 Node *r = phi->region();
1485
1486 for( ; i < phi->req(); i++ ){ // Count occurrences of constant
1487 Node *n = phi->in(i);
1488 if( !n ) return NULL;
1489 if( phase->type(n) == Type::TOP ) return NULL;
1490 if( phi->in(i) == val ) {
1491 hit++;
1492 if (PhaseIdealLoop::find_predicate(r->in(i)) != NULL) {
1493 return NULL; // don't split loop entry path
1494 }
1495 }
1496 }
1497
1498 if( hit <= 1 || // Make sure we find 2 or more
1499 hit == phi->req()-1 ) // and not ALL the same value
1500 return NULL;
1501
1502 // Now start splitting out the flow paths that merge the same value.
1503 // Split first the RegionNode.
1504 PhaseIterGVN *igvn = phase->is_IterGVN();
1505 RegionNode *newr = new RegionNode(hit+1);
1506 split_once(igvn, phi, val, r, newr);
1507
1508 // Now split all other Phis than this one
1509 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) {
1510 Node* phi2 = r->fast_out(k);
1511 if( phi2->is_Phi() && phi2->as_Phi() != phi ) {
1512 PhiNode *newphi = PhiNode::make_blank(newr, phi2);
1513 split_once(igvn, phi, val, phi2, newphi);
1514 }
1515 }
1516
1517 // Clean up this guy
1518 igvn->hash_delete(phi);
1519 for( i = phi->req()-1; i > 0; i-- ) {
1520 if( phi->in(i) == val ) {
1521 phi->del_req(i);
1522 }
1523 }
1524 phi->add_req(val);
1525
1526 return phi;
1527 }
1528
1529 //=============================================================================
1530 //------------------------------simple_data_loop_check-------------------------
1531 // Try to determining if the phi node in a simple safe/unsafe data loop.
1532 // Returns:
1533 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
1534 // Safe - safe case when the phi and it's inputs reference only safe data
1535 // nodes;
1536 // Unsafe - the phi and it's inputs reference unsafe data nodes but there
1537 // is no reference back to the phi - need a graph walk
1538 // to determine if it is in a loop;
1539 // UnsafeLoop - unsafe case when the phi references itself directly or through
1540 // unsafe data node.
1541 // Note: a safe data node is a node which could/never reference itself during
1542 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP.
1543 // I mark Phi nodes as safe node not only because they can reference itself
1544 // but also to prevent mistaking the fallthrough case inside an outer loop
1545 // as dead loop when the phi references itselfs through an other phi.
1546 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const {
1547 // It is unsafe loop if the phi node references itself directly.
1548 if (in == (Node*)this)
1549 return UnsafeLoop; // Unsafe loop
1550 // Unsafe loop if the phi node references itself through an unsafe data node.
1551 // Exclude cases with null inputs or data nodes which could reference
1552 // itself (safe for dead loops).
1553 if (in != NULL && !in->is_dead_loop_safe()) {
1554 // Check inputs of phi's inputs also.
1555 // It is much less expensive then full graph walk.
1556 uint cnt = in->req();
1557 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1;
1558 for (; i < cnt; ++i) {
1559 Node* m = in->in(i);
1560 if (m == (Node*)this)
1561 return UnsafeLoop; // Unsafe loop
1562 if (m != NULL && !m->is_dead_loop_safe()) {
1563 // Check the most common case (about 30% of all cases):
1564 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con).
1565 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL;
1566 if (m1 == (Node*)this)
1567 return UnsafeLoop; // Unsafe loop
1568 if (m1 != NULL && m1 == m->in(2) &&
1569 m1->is_dead_loop_safe() && m->in(3)->is_Con()) {
1570 continue; // Safe case
1571 }
1572 // The phi references an unsafe node - need full analysis.
1573 return Unsafe;
1574 }
1575 }
1576 }
1577 return Safe; // Safe case - we can optimize the phi node.
1578 }
1579
1580 //------------------------------is_unsafe_data_reference-----------------------
1581 // If phi can be reached through the data input - it is data loop.
1582 bool PhiNode::is_unsafe_data_reference(Node *in) const {
1583 assert(req() > 1, "");
1584 // First, check simple cases when phi references itself directly or
1585 // through an other node.
1586 LoopSafety safety = simple_data_loop_check(in);
1587 if (safety == UnsafeLoop)
1588 return true; // phi references itself - unsafe loop
1589 else if (safety == Safe)
1590 return false; // Safe case - phi could be replaced with the unique input.
1591
1592 // Unsafe case when we should go through data graph to determine
1593 // if the phi references itself.
1594
1595 ResourceMark rm;
1596
1597 Arena *a = Thread::current()->resource_area();
1598 Node_List nstack(a);
1599 VectorSet visited(a);
1600
1601 nstack.push(in); // Start with unique input.
1602 visited.set(in->_idx);
1603 while (nstack.size() != 0) {
1604 Node* n = nstack.pop();
1605 uint cnt = n->req();
1606 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1;
1607 for (; i < cnt; i++) {
1608 Node* m = n->in(i);
1609 if (m == (Node*)this) {
1610 return true; // Data loop
1611 }
1612 if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases.
1613 if (!visited.test_set(m->_idx))
1614 nstack.push(m);
1615 }
1616 }
1617 }
1618 return false; // The phi is not reachable from its inputs
1619 }
1620
1621
1622 //------------------------------Ideal------------------------------------------
1623 // Return a node which is more "ideal" than the current node. Must preserve
1624 // the CFG, but we can still strip out dead paths.
1625 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1626 // The next should never happen after 6297035 fix.
1627 if( is_copy() ) // Already degraded to a Copy ?
1628 return NULL; // No change
1629
1630 Node *r = in(0); // RegionNode
1631 assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge");
1632
1633 // Note: During parsing, phis are often transformed before their regions.
1634 // This means we have to use type_or_null to defend against untyped regions.
1635 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1636 return NULL; // No change
1637
1638 Node *top = phase->C->top();
1639 bool new_phi = (outcnt() == 0); // transforming new Phi
1640 // No change for igvn if new phi is not hooked
1641 if (new_phi && can_reshape)
1642 return NULL;
1643
1644 // The are 2 situations when only one valid phi's input is left
1645 // (in addition to Region input).
1646 // One: region is not loop - replace phi with this input.
1647 // Two: region is loop - replace phi with top since this data path is dead
1648 // and we need to break the dead data loop.
1649 Node* progress = NULL; // Record if any progress made
1650 for( uint j = 1; j < req(); ++j ){ // For all paths in
1651 // Check unreachable control paths
1652 Node* rc = r->in(j);
1653 Node* n = in(j); // Get the input
1654 if (rc == NULL || phase->type(rc) == Type::TOP) {
1655 if (n != top) { // Not already top?
1656 PhaseIterGVN *igvn = phase->is_IterGVN();
1657 if (can_reshape && igvn != NULL) {
1658 igvn->_worklist.push(r);
1659 }
1660 set_req(j, top); // Nuke it down
1661 progress = this; // Record progress
1662 }
1663 }
1664 }
1665
1666 if (can_reshape && outcnt() == 0) {
1667 // set_req() above may kill outputs if Phi is referenced
1668 // only by itself on the dead (top) control path.
1669 return top;
1670 }
1671
1672 Node* uin = unique_input(phase);
1673 if (uin == top) { // Simplest case: no alive inputs.
1674 if (can_reshape) // IGVN transformation
1675 return top;
1676 else
1677 return NULL; // Identity will return TOP
1678 } else if (uin != NULL) {
1679 // Only one not-NULL unique input path is left.
1680 // Determine if this input is backedge of a loop.
1681 // (Skip new phis which have no uses and dead regions).
1682 if (outcnt() > 0 && r->in(0) != NULL) {
1683 // First, take the short cut when we know it is a loop and
1684 // the EntryControl data path is dead.
1685 // Loop node may have only one input because entry path
1686 // is removed in PhaseIdealLoop::Dominators().
1687 assert(!r->is_Loop() || r->req() <= 3, "Loop node should have 3 or less inputs");
1688 bool is_loop = (r->is_Loop() && r->req() == 3);
1689 // Then, check if there is a data loop when phi references itself directly
1690 // or through other data nodes.
1691 if (is_loop && !uin->eqv_uncast(in(LoopNode::EntryControl)) ||
1692 !is_loop && is_unsafe_data_reference(uin)) {
1693 // Break this data loop to avoid creation of a dead loop.
1694 if (can_reshape) {
1695 return top;
1696 } else {
1697 // We can't return top if we are in Parse phase - cut inputs only
1698 // let Identity to handle the case.
1699 replace_edge(uin, top);
1700 return NULL;
1701 }
1702 }
1703 }
1704
1705 // One unique input.
1706 debug_only(Node* ident = Identity(phase));
1707 // The unique input must eventually be detected by the Identity call.
1708 #ifdef ASSERT
1709 if (ident != uin && !ident->is_top()) {
1710 // print this output before failing assert
1711 r->dump(3);
1712 this->dump(3);
1713 ident->dump();
1714 uin->dump();
1715 }
1716 #endif
1717 assert(ident == uin || ident->is_top(), "Identity must clean this up");
1718 return NULL;
1719 }
1720
1721
1722 Node* opt = NULL;
1723 int true_path = is_diamond_phi();
1724 if( true_path != 0 ) {
1725 // Check for CMove'ing identity. If it would be unsafe,
1726 // handle it here. In the safe case, let Identity handle it.
1727 Node* unsafe_id = is_cmove_id(phase, true_path);
1728 if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) )
1729 opt = unsafe_id;
1730
1731 // Check for simple convert-to-boolean pattern
1732 if( opt == NULL )
1733 opt = is_x2logic(phase, this, true_path);
1734
1735 // Check for absolute value
1736 if( opt == NULL )
1737 opt = is_absolute(phase, this, true_path);
1738
1739 // Check for conditional add
1740 if( opt == NULL && can_reshape )
1741 opt = is_cond_add(phase, this, true_path);
1742
1743 // These 4 optimizations could subsume the phi:
1744 // have to check for a dead data loop creation.
1745 if( opt != NULL ) {
1746 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) {
1747 // Found dead loop.
1748 if( can_reshape )
1749 return top;
1750 // We can't return top if we are in Parse phase - cut inputs only
1751 // to stop further optimizations for this phi. Identity will return TOP.
1752 assert(req() == 3, "only diamond merge phi here");
1753 set_req(1, top);
1754 set_req(2, top);
1755 return NULL;
1756 } else {
1757 return opt;
1758 }
1759 }
1760 }
1761
1762 // Check for merging identical values and split flow paths
1763 if (can_reshape) {
1764 opt = split_flow_path(phase, this);
1765 // This optimization only modifies phi - don't need to check for dead loop.
1766 assert(opt == NULL || phase->eqv(opt, this), "do not elide phi");
1767 if (opt != NULL) return opt;
1768 }
1769
1770 if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) {
1771 // Try to undo Phi of AddP:
1772 // (Phi (AddP base base y) (AddP base2 base2 y))
1773 // becomes:
1774 // newbase := (Phi base base2)
1775 // (AddP newbase newbase y)
1776 //
1777 // This occurs as a result of unsuccessful split_thru_phi and
1778 // interferes with taking advantage of addressing modes. See the
1779 // clone_shift_expressions code in matcher.cpp
1780 Node* addp = in(1);
1781 const Type* type = addp->in(AddPNode::Base)->bottom_type();
1782 Node* y = addp->in(AddPNode::Offset);
1783 if (y != NULL && addp->in(AddPNode::Base) == addp->in(AddPNode::Address)) {
1784 // make sure that all the inputs are similar to the first one,
1785 // i.e. AddP with base == address and same offset as first AddP
1786 bool doit = true;
1787 for (uint i = 2; i < req(); i++) {
1788 if (in(i) == NULL ||
1789 in(i)->Opcode() != Op_AddP ||
1790 in(i)->in(AddPNode::Base) != in(i)->in(AddPNode::Address) ||
1791 in(i)->in(AddPNode::Offset) != y) {
1792 doit = false;
1793 break;
1794 }
1795 // Accumulate type for resulting Phi
1796 type = type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type());
1797 }
1798 Node* base = NULL;
1799 if (doit) {
1800 // Check for neighboring AddP nodes in a tree.
1801 // If they have a base, use that it.
1802 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) {
1803 Node* u = this->fast_out(k);
1804 if (u->is_AddP()) {
1805 Node* base2 = u->in(AddPNode::Base);
1806 if (base2 != NULL && !base2->is_top()) {
1807 if (base == NULL)
1808 base = base2;
1809 else if (base != base2)
1810 { doit = false; break; }
1811 }
1812 }
1813 }
1814 }
1815 if (doit) {
1816 if (base == NULL) {
1817 base = new PhiNode(in(0), type, NULL);
1818 for (uint i = 1; i < req(); i++) {
1819 base->init_req(i, in(i)->in(AddPNode::Base));
1820 }
1821 phase->is_IterGVN()->register_new_node_with_optimizer(base);
1822 }
1823 return new AddPNode(base, base, y);
1824 }
1825 }
1826 }
1827
1828 // Split phis through memory merges, so that the memory merges will go away.
1829 // Piggy-back this transformation on the search for a unique input....
1830 // It will be as if the merged memory is the unique value of the phi.
1831 // (Do not attempt this optimization unless parsing is complete.
1832 // It would make the parser's memory-merge logic sick.)
1833 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.)
1834 if (progress == NULL && can_reshape && type() == Type::MEMORY) {
1835 // see if this phi should be sliced
1836 uint merge_width = 0;
1837 bool saw_self = false;
1838 for( uint i=1; i<req(); ++i ) {// For all paths in
1839 Node *ii = in(i);
1840 if (ii->is_MergeMem()) {
1841 MergeMemNode* n = ii->as_MergeMem();
1842 merge_width = MAX2(merge_width, n->req());
1843 saw_self = saw_self || phase->eqv(n->base_memory(), this);
1844 }
1845 }
1846
1847 // This restriction is temporarily necessary to ensure termination:
1848 if (!saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0;
1849
1850 if (merge_width > Compile::AliasIdxRaw) {
1851 // found at least one non-empty MergeMem
1852 const TypePtr* at = adr_type();
1853 if (at != TypePtr::BOTTOM) {
1854 // Patch the existing phi to select an input from the merge:
1855 // Phi:AT1(...MergeMem(m0, m1, m2)...) into
1856 // Phi:AT1(...m1...)
1857 int alias_idx = phase->C->get_alias_index(at);
1858 for (uint i=1; i<req(); ++i) {
1859 Node *ii = in(i);
1860 if (ii->is_MergeMem()) {
1861 MergeMemNode* n = ii->as_MergeMem();
1862 // compress paths and change unreachable cycles to TOP
1863 // If not, we can update the input infinitely along a MergeMem cycle
1864 // Equivalent code is in MemNode::Ideal_common
1865 Node *m = phase->transform(n);
1866 if (outcnt() == 0) { // Above transform() may kill us!
1867 return top;
1868 }
1869 // If transformed to a MergeMem, get the desired slice
1870 // Otherwise the returned node represents memory for every slice
1871 Node *new_mem = (m->is_MergeMem()) ?
1872 m->as_MergeMem()->memory_at(alias_idx) : m;
1873 // Update input if it is progress over what we have now
1874 if (new_mem != ii) {
1875 set_req(i, new_mem);
1876 progress = this;
1877 }
1878 }
1879 }
1880 } else {
1881 // We know that at least one MergeMem->base_memory() == this
1882 // (saw_self == true). If all other inputs also references this phi
1883 // (directly or through data nodes) - it is dead loop.
1884 bool saw_safe_input = false;
1885 for (uint j = 1; j < req(); ++j) {
1886 Node *n = in(j);
1887 if (n->is_MergeMem() && n->as_MergeMem()->base_memory() == this)
1888 continue; // skip known cases
1889 if (!is_unsafe_data_reference(n)) {
1890 saw_safe_input = true; // found safe input
1891 break;
1892 }
1893 }
1894 if (!saw_safe_input)
1895 return top; // all inputs reference back to this phi - dead loop
1896
1897 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into
1898 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...))
1899 PhaseIterGVN *igvn = phase->is_IterGVN();
1900 Node* hook = new Node(1);
1901 PhiNode* new_base = (PhiNode*) clone();
1902 // Must eagerly register phis, since they participate in loops.
1903 if (igvn) {
1904 igvn->register_new_node_with_optimizer(new_base);
1905 hook->add_req(new_base);
1906 }
1907 MergeMemNode* result = MergeMemNode::make(new_base);
1908 for (uint i = 1; i < req(); ++i) {
1909 Node *ii = in(i);
1910 if (ii->is_MergeMem()) {
1911 MergeMemNode* n = ii->as_MergeMem();
1912 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) {
1913 // If we have not seen this slice yet, make a phi for it.
1914 bool made_new_phi = false;
1915 if (mms.is_empty()) {
1916 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C));
1917 made_new_phi = true;
1918 if (igvn) {
1919 igvn->register_new_node_with_optimizer(new_phi);
1920 hook->add_req(new_phi);
1921 }
1922 mms.set_memory(new_phi);
1923 }
1924 Node* phi = mms.memory();
1925 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice");
1926 phi->set_req(i, mms.memory2());
1927 }
1928 }
1929 }
1930 // Distribute all self-loops.
1931 { // (Extra braces to hide mms.)
1932 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
1933 Node* phi = mms.memory();
1934 for (uint i = 1; i < req(); ++i) {
1935 if (phi->in(i) == this) phi->set_req(i, phi);
1936 }
1937 }
1938 }
1939 // now transform the new nodes, and return the mergemem
1940 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
1941 Node* phi = mms.memory();
1942 mms.set_memory(phase->transform(phi));
1943 }
1944 if (igvn) { // Unhook.
1945 igvn->hash_delete(hook);
1946 for (uint i = 1; i < hook->req(); i++) {
1947 hook->set_req(i, NULL);
1948 }
1949 }
1950 // Replace self with the result.
1951 return result;
1952 }
1953 }
1954 //
1955 // Other optimizations on the memory chain
1956 //
1957 const TypePtr* at = adr_type();
1958 for( uint i=1; i<req(); ++i ) {// For all paths in
1959 Node *ii = in(i);
1960 Node *new_in = MemNode::optimize_memory_chain(ii, at, NULL, phase);
1961 if (ii != new_in ) {
1962 set_req(i, new_in);
1963 progress = this;
1964 }
1965 }
1966 }
1967
1968 #ifdef _LP64
1969 // Push DecodeN/DecodeNKlass down through phi.
1970 // The rest of phi graph will transform by split EncodeP node though phis up.
1971 if ((UseCompressedOops || UseCompressedClassPointers) && can_reshape && progress == NULL) {
1972 bool may_push = true;
1973 bool has_decodeN = false;
1974 bool is_decodeN = false;
1975 for (uint i=1; i<req(); ++i) {// For all paths in
1976 Node *ii = in(i);
1977 if (ii->is_DecodeNarrowPtr() && ii->bottom_type() == bottom_type()) {
1978 // Do optimization if a non dead path exist.
1979 if (ii->in(1)->bottom_type() != Type::TOP) {
1980 has_decodeN = true;
1981 is_decodeN = ii->is_DecodeN();
1982 }
1983 } else if (!ii->is_Phi()) {
1984 may_push = false;
1985 }
1986 }
1987
1988 if (has_decodeN && may_push) {
1989 PhaseIterGVN *igvn = phase->is_IterGVN();
1990 // Make narrow type for new phi.
1991 const Type* narrow_t;
1992 if (is_decodeN) {
1993 narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr());
1994 } else {
1995 narrow_t = TypeNarrowKlass::make(this->bottom_type()->is_ptr());
1996 }
1997 PhiNode* new_phi = new PhiNode(r, narrow_t);
1998 uint orig_cnt = req();
1999 for (uint i=1; i<req(); ++i) {// For all paths in
2000 Node *ii = in(i);
2001 Node* new_ii = NULL;
2002 if (ii->is_DecodeNarrowPtr()) {
2003 assert(ii->bottom_type() == bottom_type(), "sanity");
2004 new_ii = ii->in(1);
2005 } else {
2006 assert(ii->is_Phi(), "sanity");
2007 if (ii->as_Phi() == this) {
2008 new_ii = new_phi;
2009 } else {
2010 if (is_decodeN) {
2011 new_ii = new EncodePNode(ii, narrow_t);
2012 } else {
2013 new_ii = new EncodePKlassNode(ii, narrow_t);
2014 }
2015 igvn->register_new_node_with_optimizer(new_ii);
2016 }
2017 }
2018 new_phi->set_req(i, new_ii);
2019 }
2020 igvn->register_new_node_with_optimizer(new_phi, this);
2021 if (is_decodeN) {
2022 progress = new DecodeNNode(new_phi, bottom_type());
2023 } else {
2024 progress = new DecodeNKlassNode(new_phi, bottom_type());
2025 }
2026 }
2027 }
2028 #endif
2029
2030 return progress; // Return any progress
2031 }
2032
2033 //------------------------------is_tripcount-----------------------------------
2034 bool PhiNode::is_tripcount() const {
2035 return (in(0) != NULL && in(0)->is_CountedLoop() &&
2036 in(0)->as_CountedLoop()->phi() == this);
2037 }
2038
2039 //------------------------------out_RegMask------------------------------------
2040 const RegMask &PhiNode::in_RegMask(uint i) const {
2041 return i ? out_RegMask() : RegMask::Empty;
2042 }
2043
2044 const RegMask &PhiNode::out_RegMask() const {
2045 uint ideal_reg = _type->ideal_reg();
2046 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
2047 if( ideal_reg == 0 ) return RegMask::Empty;
2048 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
2049 }
2050
2051 #ifndef PRODUCT
2052 void PhiNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2053 // For a PhiNode, the set of related nodes includes all inputs till level 2,
2054 // and all outputs till level 1. In compact mode, inputs till level 1 are
2055 // collected.
2056 this->collect_nodes(in_rel, compact ? 1 : 2, false, false);
2057 this->collect_nodes(out_rel, -1, false, false);
2058 }
2059
2060 void PhiNode::dump_spec(outputStream *st) const {
2061 TypeNode::dump_spec(st);
2062 if (is_tripcount()) {
2063 st->print(" #tripcount");
2064 }
2065 }
2066 #endif
2067
2068
2069 //=============================================================================
2070 const Type *GotoNode::Value( PhaseTransform *phase ) const {
2071 // If the input is reachable, then we are executed.
2072 // If the input is not reachable, then we are not executed.
2073 return phase->type(in(0));
2074 }
2075
2076 Node *GotoNode::Identity( PhaseTransform *phase ) {
2077 return in(0); // Simple copy of incoming control
2078 }
2079
2080 const RegMask &GotoNode::out_RegMask() const {
2081 return RegMask::Empty;
2082 }
2083
2084 #ifndef PRODUCT
2085 //-----------------------------related-----------------------------------------
2086 // The related nodes of a GotoNode are all inputs at level 1, as well as the
2087 // outputs at level 1. This is regardless of compact mode.
2088 void GotoNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2089 this->collect_nodes(in_rel, 1, false, false);
2090 this->collect_nodes(out_rel, -1, false, false);
2091 }
2092 #endif
2093
2094
2095 //=============================================================================
2096 const RegMask &JumpNode::out_RegMask() const {
2097 return RegMask::Empty;
2098 }
2099
2100 #ifndef PRODUCT
2101 //-----------------------------related-----------------------------------------
2102 // The related nodes of a JumpNode are all inputs at level 1, as well as the
2103 // outputs at level 2 (to include actual jump targets beyond projection nodes).
2104 // This is regardless of compact mode.
2105 void JumpNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2106 this->collect_nodes(in_rel, 1, false, false);
2107 this->collect_nodes(out_rel, -2, false, false);
2108 }
2109 #endif
2110
2111 //=============================================================================
2112 const RegMask &JProjNode::out_RegMask() const {
2113 return RegMask::Empty;
2114 }
2115
2116 //=============================================================================
2117 const RegMask &CProjNode::out_RegMask() const {
2118 return RegMask::Empty;
2119 }
2120
2121
2122
2123 //=============================================================================
2124
2125 uint PCTableNode::hash() const { return Node::hash() + _size; }
2126 uint PCTableNode::cmp( const Node &n ) const
2127 { return _size == ((PCTableNode&)n)._size; }
2128
2129 const Type *PCTableNode::bottom_type() const {
2130 const Type** f = TypeTuple::fields(_size);
2131 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2132 return TypeTuple::make(_size, f);
2133 }
2134
2135 //------------------------------Value------------------------------------------
2136 // Compute the type of the PCTableNode. If reachable it is a tuple of
2137 // Control, otherwise the table targets are not reachable
2138 const Type *PCTableNode::Value( PhaseTransform *phase ) const {
2139 if( phase->type(in(0)) == Type::CONTROL )
2140 return bottom_type();
2141 return Type::TOP; // All paths dead? Then so are we
2142 }
2143
2144 //------------------------------Ideal------------------------------------------
2145 // Return a node which is more "ideal" than the current node. Strip out
2146 // control copies
2147 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2148 return remove_dead_region(phase, can_reshape) ? this : NULL;
2149 }
2150
2151 //=============================================================================
2152 uint JumpProjNode::hash() const {
2153 return Node::hash() + _dest_bci;
2154 }
2155
2156 uint JumpProjNode::cmp( const Node &n ) const {
2157 return ProjNode::cmp(n) &&
2158 _dest_bci == ((JumpProjNode&)n)._dest_bci;
2159 }
2160
2161 #ifndef PRODUCT
2162 void JumpProjNode::dump_spec(outputStream *st) const {
2163 ProjNode::dump_spec(st);
2164 st->print("@bci %d ",_dest_bci);
2165 }
2166
2167 void JumpProjNode::dump_compact_spec(outputStream *st) const {
2168 ProjNode::dump_compact_spec(st);
2169 st->print("(%d)%d@%d", _switch_val, _proj_no, _dest_bci);
2170 }
2171
2172 void JumpProjNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2173 // The related nodes of a JumpProjNode are its inputs and outputs at level 1.
2174 this->collect_nodes(in_rel, 1, false, false);
2175 this->collect_nodes(out_rel, -1, false, false);
2176 }
2177 #endif
2178
2179 //=============================================================================
2180 //------------------------------Value------------------------------------------
2181 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot
2182 // have the default "fall_through_index" path.
2183 const Type *CatchNode::Value( PhaseTransform *phase ) const {
2184 // Unreachable? Then so are all paths from here.
2185 if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
2186 // First assume all paths are reachable
2187 const Type** f = TypeTuple::fields(_size);
2188 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2189 // Identify cases that will always throw an exception
2190 // () rethrow call
2191 // () virtual or interface call with NULL receiver
2192 // () call is a check cast with incompatible arguments
2193 if( in(1)->is_Proj() ) {
2194 Node *i10 = in(1)->in(0);
2195 if( i10->is_Call() ) {
2196 CallNode *call = i10->as_Call();
2197 // Rethrows always throw exceptions, never return
2198 if (call->entry_point() == OptoRuntime::rethrow_stub()) {
2199 f[CatchProjNode::fall_through_index] = Type::TOP;
2200 } else if( call->req() > TypeFunc::Parms ) {
2201 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) );
2202 // Check for null receiver to virtual or interface calls
2203 if( call->is_CallDynamicJava() &&
2204 arg0->higher_equal(TypePtr::NULL_PTR) ) {
2205 f[CatchProjNode::fall_through_index] = Type::TOP;
2206 }
2207 } // End of if not a runtime stub
2208 } // End of if have call above me
2209 } // End of slot 1 is not a projection
2210 return TypeTuple::make(_size, f);
2211 }
2212
2213 //=============================================================================
2214 uint CatchProjNode::hash() const {
2215 return Node::hash() + _handler_bci;
2216 }
2217
2218
2219 uint CatchProjNode::cmp( const Node &n ) const {
2220 return ProjNode::cmp(n) &&
2221 _handler_bci == ((CatchProjNode&)n)._handler_bci;
2222 }
2223
2224
2225 //------------------------------Identity---------------------------------------
2226 // If only 1 target is possible, choose it if it is the main control
2227 Node *CatchProjNode::Identity( PhaseTransform *phase ) {
2228 // If my value is control and no other value is, then treat as ID
2229 const TypeTuple *t = phase->type(in(0))->is_tuple();
2230 if (t->field_at(_con) != Type::CONTROL) return this;
2231 // If we remove the last CatchProj and elide the Catch/CatchProj, then we
2232 // also remove any exception table entry. Thus we must know the call
2233 // feeding the Catch will not really throw an exception. This is ok for
2234 // the main fall-thru control (happens when we know a call can never throw
2235 // an exception) or for "rethrow", because a further optimization will
2236 // yank the rethrow (happens when we inline a function that can throw an
2237 // exception and the caller has no handler). Not legal, e.g., for passing
2238 // a NULL receiver to a v-call, or passing bad types to a slow-check-cast.
2239 // These cases MUST throw an exception via the runtime system, so the VM
2240 // will be looking for a table entry.
2241 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode
2242 CallNode *call;
2243 if (_con != TypeFunc::Control && // Bail out if not the main control.
2244 !(proj->is_Proj() && // AND NOT a rethrow
2245 proj->in(0)->is_Call() &&
2246 (call = proj->in(0)->as_Call()) &&
2247 call->entry_point() == OptoRuntime::rethrow_stub()))
2248 return this;
2249
2250 // Search for any other path being control
2251 for (uint i = 0; i < t->cnt(); i++) {
2252 if (i != _con && t->field_at(i) == Type::CONTROL)
2253 return this;
2254 }
2255 // Only my path is possible; I am identity on control to the jump
2256 return in(0)->in(0);
2257 }
2258
2259
2260 #ifndef PRODUCT
2261 void CatchProjNode::dump_spec(outputStream *st) const {
2262 ProjNode::dump_spec(st);
2263 st->print("@bci %d ",_handler_bci);
2264 }
2265 #endif
2266
2267 //=============================================================================
2268 //------------------------------Identity---------------------------------------
2269 // Check for CreateEx being Identity.
2270 Node *CreateExNode::Identity( PhaseTransform *phase ) {
2271 if( phase->type(in(1)) == Type::TOP ) return in(1);
2272 if( phase->type(in(0)) == Type::TOP ) return in(0);
2273 // We only come from CatchProj, unless the CatchProj goes away.
2274 // If the CatchProj is optimized away, then we just carry the
2275 // exception oop through.
2276 CallNode *call = in(1)->in(0)->as_Call();
2277
2278 return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) )
2279 ? this
2280 : call->in(TypeFunc::Parms);
2281 }
2282
2283 //=============================================================================
2284 //------------------------------Value------------------------------------------
2285 // Check for being unreachable.
2286 const Type *NeverBranchNode::Value( PhaseTransform *phase ) const {
2287 if (!in(0) || in(0)->is_top()) return Type::TOP;
2288 return bottom_type();
2289 }
2290
2291 //------------------------------Ideal------------------------------------------
2292 // Check for no longer being part of a loop
2293 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2294 if (can_reshape && !in(0)->is_Loop()) {
2295 // Dead code elimination can sometimes delete this projection so
2296 // if it's not there, there's nothing to do.
2297 Node* fallthru = proj_out(0);
2298 if (fallthru != NULL) {
2299 phase->is_IterGVN()->replace_node(fallthru, in(0));
2300 }
2301 return phase->C->top();
2302 }
2303 return NULL;
2304 }
2305
2306 #ifndef PRODUCT
2307 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const {
2308 st->print("%s", Name());
2309 }
2310 #endif