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