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.
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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 #if INCLUDE_ALL_GCS
40 #include "gc_implementation/shenandoah/c2/shenandoahBarrierSetC2.hpp"
41 #include "gc_implementation/shenandoah/c2/shenandoahSupport.hpp"
42 #endif
43
44 // Portions of code courtesy of Clifford Click
45
46 // Optimization - Graph Style
47
48 //=============================================================================
49 //------------------------------Value------------------------------------------
50 // Compute the type of the RegionNode.
51 const Type *RegionNode::Value( PhaseTransform *phase ) const {
52 for( uint i=1; i<req(); ++i ) { // For all paths in
53 Node *n = in(i); // Get Control source
54 if( !n ) continue; // Missing inputs are TOP
55 if( phase->type(n) == Type::CONTROL )
56 return Type::CONTROL;
57 }
58 return Type::TOP; // All paths dead? Then so are we
59 }
60
61 //------------------------------Identity---------------------------------------
62 // Check for Region being Identity.
63 Node *RegionNode::Identity( PhaseTransform *phase ) {
64 // Cannot have Region be an identity, even if it has only 1 input.
65 // Phi users cannot have their Region input folded away for them,
66 // since they need to select the proper data input
67 return this;
68 }
69
70 //------------------------------merge_region-----------------------------------
71 // If a Region flows into a Region, merge into one big happy merge. This is
72 // hard to do if there is stuff that has to happen
73 static Node *merge_region(RegionNode *region, PhaseGVN *phase) {
74 if( region->Opcode() != Op_Region ) // Do not do to LoopNodes
75 return NULL;
76 Node *progress = NULL; // Progress flag
77 PhaseIterGVN *igvn = phase->is_IterGVN();
78
79 uint rreq = region->req();
80 for( uint i = 1; i < rreq; i++ ) {
81 Node *r = region->in(i);
82 if( r && r->Opcode() == Op_Region && // Found a region?
83 r->in(0) == r && // Not already collapsed?
84 r != region && // Avoid stupid situations
85 r->outcnt() == 2 ) { // Self user and 'region' user only?
86 assert(!r->as_Region()->has_phi(), "no phi users");
87 if( !progress ) { // No progress
88 if (region->has_phi()) {
89 return NULL; // Only flatten if no Phi users
90 // igvn->hash_delete( phi );
91 }
92 igvn->hash_delete( region );
93 progress = region; // Making progress
94 }
95 igvn->hash_delete( r );
96
97 // Append inputs to 'r' onto 'region'
98 for( uint j = 1; j < r->req(); j++ ) {
99 // Move an input from 'r' to 'region'
100 region->add_req(r->in(j));
101 r->set_req(j, phase->C->top());
102 // Update phis of 'region'
103 //for( uint k = 0; k < max; k++ ) {
104 // Node *phi = region->out(k);
105 // if( phi->is_Phi() ) {
106 // phi->add_req(phi->in(i));
107 // }
108 //}
109
110 rreq++; // One more input to Region
111 } // Found a region to merge into Region
112 // 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 int cnt = 0; // Count of values merging
454 DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count
455 int del_it = 0; // The last input path we delete
456 // For all inputs...
457 for( uint i=1; i<req(); ++i ){// For all paths in
458 Node *n = in(i); // Get the input
459 if( n != NULL ) {
460 // Remove useless control copy inputs
461 if( n->is_Region() && n->as_Region()->is_copy() ) {
462 set_req(i, n->nonnull_req());
463 i--;
464 continue;
465 }
466 if( n->is_Proj() ) { // Remove useless rethrows
467 Node *call = n->in(0);
468 if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) {
469 set_req(i, call->in(0));
470 i--;
471 continue;
472 }
473 }
474 if( phase->type(n) == Type::TOP ) {
475 set_req(i, NULL); // Ignore TOP inputs
476 i--;
477 continue;
478 }
479 cnt++; // One more value merging
480
481 } else if (can_reshape) { // Else found dead path with DU info
482 PhaseIterGVN *igvn = phase->is_IterGVN();
483 del_req(i); // Yank path from self
484 del_it = i;
485 uint max = outcnt();
486 DUIterator j;
487 bool progress = true;
488 while(progress) { // Need to establish property over all users
489 progress = false;
490 for (j = outs(); has_out(j); j++) {
491 Node *n = out(j);
492 if( n->req() != req() && n->is_Phi() ) {
493 assert( n->in(0) == this, "" );
494 igvn->hash_delete(n); // Yank from hash before hacking edges
495 n->set_req_X(i,NULL,igvn);// Correct DU info
496 n->del_req(i); // Yank path from Phis
497 if( max != outcnt() ) {
498 progress = true;
499 j = refresh_out_pos(j);
500 max = outcnt();
501 }
502 }
503 }
504 }
505 add_to_worklist = true;
506 i--;
507 }
508 }
509
510 if (can_reshape && cnt == 1) {
511 // Is it dead loop?
512 // If it is LoopNopde it had 2 (+1 itself) inputs and
513 // one of them was cut. The loop is dead if it was EntryContol.
514 // Loop node may have only one input because entry path
515 // is removed in PhaseIdealLoop::Dominators().
516 assert(!this->is_Loop() || cnt_orig <= 3, "Loop node should have 3 or less inputs");
517 if (this->is_Loop() && (del_it == LoopNode::EntryControl ||
518 del_it == 0 && is_unreachable_region(phase)) ||
519 !this->is_Loop() && has_phis && is_unreachable_region(phase)) {
520 // Yes, the region will be removed during the next step below.
521 // Cut the backedge input and remove phis since no data paths left.
522 // We don't cut outputs to other nodes here since we need to put them
523 // on the worklist.
524 del_req(1);
525 cnt = 0;
526 assert( req() == 1, "no more inputs expected" );
527 uint max = outcnt();
528 bool progress = true;
529 Node *top = phase->C->top();
530 PhaseIterGVN *igvn = phase->is_IterGVN();
531 DUIterator j;
532 while(progress) {
533 progress = false;
534 for (j = outs(); has_out(j); j++) {
535 Node *n = out(j);
536 if( n->is_Phi() ) {
537 assert( igvn->eqv(n->in(0), this), "" );
538 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
539 // Break dead loop data path.
540 // Eagerly replace phis with top to avoid phis copies generation.
541 igvn->replace_node(n, top);
542 if( max != outcnt() ) {
543 progress = true;
544 j = refresh_out_pos(j);
545 max = outcnt();
546 }
547 }
548 }
549 }
550 add_to_worklist = true;
551 }
552 }
553 if (add_to_worklist) {
554 phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis
555 }
556
557 if( cnt <= 1 ) { // Only 1 path in?
558 set_req(0, NULL); // Null control input for region copy
559 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is.
560 // No inputs or all inputs are NULL.
561 return NULL;
562 } else if (can_reshape) { // Optimization phase - remove the node
563 PhaseIterGVN *igvn = phase->is_IterGVN();
564 Node *parent_ctrl;
565 if( cnt == 0 ) {
566 assert( req() == 1, "no inputs expected" );
567 // During IGVN phase such region will be subsumed by TOP node
568 // so region's phis will have TOP as control node.
569 // Kill phis here to avoid it. PhiNode::is_copy() will be always false.
570 // Also set other user's input to top.
571 parent_ctrl = phase->C->top();
572 } else {
573 // The fallthrough case since we already checked dead loops above.
574 parent_ctrl = in(1);
575 assert(parent_ctrl != NULL, "Region is a copy of some non-null control");
576 assert(!igvn->eqv(parent_ctrl, this), "Close dead loop");
577 }
578 if (!add_to_worklist)
579 igvn->add_users_to_worklist(this); // Check for further allowed opts
580 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
581 Node* n = last_out(i);
582 igvn->hash_delete(n); // Remove from worklist before modifying edges
583 if( n->is_Phi() ) { // Collapse all Phis
584 // Eagerly replace phis to avoid copies generation.
585 Node* in;
586 if( cnt == 0 ) {
587 assert( n->req() == 1, "No data inputs expected" );
588 in = parent_ctrl; // replaced by top
589 } else {
590 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
591 in = n->in(1); // replaced by unique input
592 if( n->as_Phi()->is_unsafe_data_reference(in) )
593 in = phase->C->top(); // replaced by top
594 }
595 if (n->outcnt() == 0) {
596 in = phase->C->top();
597 }
598 igvn->replace_node(n, in);
599 }
600 else if( n->is_Region() ) { // Update all incoming edges
601 assert( !igvn->eqv(n, this), "Must be removed from DefUse edges");
602 uint uses_found = 0;
603 for( uint k=1; k < n->req(); k++ ) {
604 if( n->in(k) == this ) {
605 n->set_req(k, parent_ctrl);
606 uses_found++;
607 }
608 }
609 if( uses_found > 1 ) { // (--i) done at the end of the loop.
610 i -= (uses_found - 1);
611 }
612 }
613 else {
614 assert( igvn->eqv(n->in(0), this), "Expect RegionNode to be control parent");
615 n->set_req(0, parent_ctrl);
616 }
617 #ifdef ASSERT
618 for( uint k=0; k < n->req(); k++ ) {
619 assert( !igvn->eqv(n->in(k), this), "All uses of RegionNode should be gone");
620 }
621 #endif
622 }
623 // Remove the RegionNode itself from DefUse info
624 igvn->remove_dead_node(this);
625 return NULL;
626 }
627 return this; // Record progress
628 }
629
630
631 // If a Region flows into a Region, merge into one big happy merge.
632 if (can_reshape) {
633 Node *m = merge_region(this, phase);
634 if (m != NULL) return m;
635 }
636
637 // Check if this region is the root of a clipping idiom on floats
638 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
639 // Check that only one use is a Phi and that it simplifies to two constants +
640 PhiNode* phi = has_unique_phi();
641 if (phi != NULL) { // One Phi user
642 // Check inputs to the Phi
643 ConNode *min;
644 ConNode *max;
645 Node *val;
646 uint min_idx;
647 uint max_idx;
648 uint val_idx;
649 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) {
650 IfNode *top_if;
651 IfNode *bot_if;
652 if( check_if_clipping( this, bot_if, top_if ) ) {
653 // Control pattern checks, now verify compares
654 Node *top_in = NULL; // value being compared against
655 Node *bot_in = NULL;
656 if( check_compare_clipping( true, bot_if, min, bot_in ) &&
657 check_compare_clipping( false, top_if, max, top_in ) ) {
658 if( bot_in == top_in ) {
659 PhaseIterGVN *gvn = phase->is_IterGVN();
660 assert( gvn != NULL, "Only had DefUse info in IterGVN");
661 // Only remaining check is that bot_in == top_in == (Phi's val + mods)
662
663 // Check for the ConvF2INode
664 ConvF2INode *convf2i;
665 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
666 convf2i->in(1) == bot_in ) {
667 // Matched pattern, including LShiftI; RShiftI, replace with integer compares
668 // max test
669 Node *cmp = gvn->register_new_node_with_optimizer(new (phase->C) CmpINode( convf2i, min ));
670 Node *boo = gvn->register_new_node_with_optimizer(new (phase->C) BoolNode( cmp, BoolTest::lt ));
671 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 ));
672 Node *if_min= gvn->register_new_node_with_optimizer(new (phase->C) IfTrueNode (iff));
673 Node *ifF = gvn->register_new_node_with_optimizer(new (phase->C) IfFalseNode(iff));
674 // min test
675 cmp = gvn->register_new_node_with_optimizer(new (phase->C) CmpINode( convf2i, max ));
676 boo = gvn->register_new_node_with_optimizer(new (phase->C) BoolNode( cmp, BoolTest::gt ));
677 iff = (IfNode*)gvn->register_new_node_with_optimizer(new (phase->C) IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
678 Node *if_max= gvn->register_new_node_with_optimizer(new (phase->C) IfTrueNode (iff));
679 ifF = gvn->register_new_node_with_optimizer(new (phase->C) IfFalseNode(iff));
680 // update input edges to region node
681 set_req_X( min_idx, if_min, gvn );
682 set_req_X( max_idx, if_max, gvn );
683 set_req_X( val_idx, ifF, gvn );
684 // remove unnecessary 'LShiftI; RShiftI' idiom
685 gvn->hash_delete(phi);
686 phi->set_req_X( val_idx, convf2i, gvn );
687 gvn->hash_find_insert(phi);
688 // Return transformed region node
689 return this;
690 }
691 }
692 }
693 }
694 }
695 }
696 }
697
698 return NULL;
699 }
700
701
702
703 const RegMask &RegionNode::out_RegMask() const {
704 return RegMask::Empty;
705 }
706
707 // Find the one non-null required input. RegionNode only
708 Node *Node::nonnull_req() const {
709 assert( is_Region(), "" );
710 for( uint i = 1; i < _cnt; i++ )
711 if( in(i) )
712 return in(i);
713 ShouldNotReachHere();
714 return NULL;
715 }
716
717
718 //=============================================================================
719 // note that these functions assume that the _adr_type field is flattened
720 uint PhiNode::hash() const {
721 const Type* at = _adr_type;
722 return TypeNode::hash() + (at ? at->hash() : 0);
723 }
724 uint PhiNode::cmp( const Node &n ) const {
725 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
726 }
727 static inline
728 const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
729 if (at == NULL || at == TypePtr::BOTTOM) return at;
730 return Compile::current()->alias_type(at)->adr_type();
731 }
732
733 //----------------------------make---------------------------------------------
734 // create a new phi with edges matching r and set (initially) to x
735 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
736 uint preds = r->req(); // Number of predecessor paths
737 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at");
738 PhiNode* p = new (Compile::current()) PhiNode(r, t, at);
739 for (uint j = 1; j < preds; j++) {
740 // Fill in all inputs, except those which the region does not yet have
741 if (r->in(j) != NULL)
742 p->init_req(j, x);
743 }
744 return p;
745 }
746 PhiNode* PhiNode::make(Node* r, Node* x) {
747 const Type* t = x->bottom_type();
748 const TypePtr* at = NULL;
749 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
750 return make(r, x, t, at);
751 }
752 PhiNode* PhiNode::make_blank(Node* r, Node* x) {
753 const Type* t = x->bottom_type();
754 const TypePtr* at = NULL;
755 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
756 return new (Compile::current()) PhiNode(r, t, at);
757 }
758
759
760 //------------------------slice_memory-----------------------------------------
761 // create a new phi with narrowed memory type
762 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
763 PhiNode* mem = (PhiNode*) clone();
764 *(const TypePtr**)&mem->_adr_type = adr_type;
765 // convert self-loops, or else we get a bad graph
766 for (uint i = 1; i < req(); i++) {
767 if ((const Node*)in(i) == this) mem->set_req(i, mem);
768 }
769 mem->verify_adr_type();
770 return mem;
771 }
772
773 //------------------------split_out_instance-----------------------------------
774 // Split out an instance type from a bottom phi.
775 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const {
776 const TypeOopPtr *t_oop = at->isa_oopptr();
777 assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr");
778 const TypePtr *t = adr_type();
779 assert(type() == Type::MEMORY &&
780 (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
781 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
782 t->is_oopptr()->cast_to_exactness(true)
783 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
784 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop),
785 "bottom or raw memory required");
786
787 // Check if an appropriate node already exists.
788 Node *region = in(0);
789 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) {
790 Node* use = region->fast_out(k);
791 if( use->is_Phi()) {
792 PhiNode *phi2 = use->as_Phi();
793 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) {
794 return phi2;
795 }
796 }
797 }
798 Compile *C = igvn->C;
799 Arena *a = Thread::current()->resource_area();
800 Node_Array node_map = new Node_Array(a);
801 Node_Stack stack(a, C->live_nodes() >> 4);
802 PhiNode *nphi = slice_memory(at);
803 igvn->register_new_node_with_optimizer( nphi );
804 node_map.map(_idx, nphi);
805 stack.push((Node *)this, 1);
806 while(!stack.is_empty()) {
807 PhiNode *ophi = stack.node()->as_Phi();
808 uint i = stack.index();
809 assert(i >= 1, "not control edge");
810 stack.pop();
811 nphi = node_map[ophi->_idx]->as_Phi();
812 for (; i < ophi->req(); i++) {
813 Node *in = ophi->in(i);
814 if (in == NULL || igvn->type(in) == Type::TOP)
815 continue;
816 Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, NULL, igvn);
817 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL;
818 if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) {
819 opt = node_map[optphi->_idx];
820 if (opt == NULL) {
821 stack.push(ophi, i);
822 nphi = optphi->slice_memory(at);
823 igvn->register_new_node_with_optimizer( nphi );
824 node_map.map(optphi->_idx, nphi);
825 ophi = optphi;
826 i = 0; // will get incremented at top of loop
827 continue;
828 }
829 }
830 nphi->set_req(i, opt);
831 }
832 }
833 return nphi;
834 }
835
836 //------------------------verify_adr_type--------------------------------------
837 #ifdef ASSERT
838 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
839 if (visited.test_set(_idx)) return; //already visited
840
841 // recheck constructor invariants:
842 verify_adr_type(false);
843
844 // recheck local phi/phi consistency:
845 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
846 "adr_type must be consistent across phi nest");
847
848 // walk around
849 for (uint i = 1; i < req(); i++) {
850 Node* n = in(i);
851 if (n == NULL) continue;
852 const Node* np = in(i);
853 if (np->is_Phi()) {
854 np->as_Phi()->verify_adr_type(visited, at);
855 } else if (n->bottom_type() == Type::TOP
856 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
857 // ignore top inputs
858 } else {
859 const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
860 // recheck phi/non-phi consistency at leaves:
861 assert((nat != NULL) == (at != NULL), "");
862 assert(nat == at || nat == TypePtr::BOTTOM,
863 "adr_type must be consistent at leaves of phi nest");
864 }
865 }
866 }
867
868 // Verify a whole nest of phis rooted at this one.
869 void PhiNode::verify_adr_type(bool recursive) const {
870 if (is_error_reported()) return; // muzzle asserts when debugging an error
871 if (Node::in_dump()) return; // muzzle asserts when printing
872
873 assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only");
874
875 if (!VerifyAliases) return; // verify thoroughly only if requested
876
877 assert(_adr_type == flatten_phi_adr_type(_adr_type),
878 "Phi::adr_type must be pre-normalized");
879
880 if (recursive) {
881 VectorSet visited(Thread::current()->resource_area());
882 verify_adr_type(visited, _adr_type);
883 }
884 }
885 #endif
886
887
888 //------------------------------Value------------------------------------------
889 // Compute the type of the PhiNode
890 const Type *PhiNode::Value( PhaseTransform *phase ) const {
891 Node *r = in(0); // RegionNode
892 if( !r ) // Copy or dead
893 return in(1) ? phase->type(in(1)) : Type::TOP;
894
895 // Note: During parsing, phis are often transformed before their regions.
896 // This means we have to use type_or_null to defend against untyped regions.
897 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
898 return Type::TOP;
899
900 // Check for trip-counted loop. If so, be smarter.
901 CountedLoopNode *l = r->is_CountedLoop() ? r->as_CountedLoop() : NULL;
902 if( l && l->can_be_counted_loop(phase) &&
903 ((const Node*)l->phi() == this) ) { // Trip counted loop!
904 // protect against init_trip() or limit() returning NULL
905 const Node *init = l->init_trip();
906 const Node *limit = l->limit();
907 if( init != NULL && limit != NULL && l->stride_is_con() ) {
908 const TypeInt *lo = init ->bottom_type()->isa_int();
909 const TypeInt *hi = limit->bottom_type()->isa_int();
910 if( lo && hi ) { // Dying loops might have TOP here
911 int stride = l->stride_con();
912 if( stride < 0 ) { // Down-counter loop
913 const TypeInt *tmp = lo; lo = hi; hi = tmp;
914 stride = -stride;
915 }
916 if( lo->_hi < hi->_lo ) // Reversed endpoints are well defined :-(
917 return TypeInt::make(lo->_lo,hi->_hi,3);
918 }
919 }
920 }
921
922 // Until we have harmony between classes and interfaces in the type
923 // lattice, we must tread carefully around phis which implicitly
924 // convert the one to the other.
925 const TypePtr* ttp = _type->make_ptr();
926 const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL;
927 const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_klassptr() : NULL;
928 bool is_intf = false;
929 if (ttip != NULL) {
930 ciKlass* k = ttip->klass();
931 if (k->is_loaded() && k->is_interface())
932 is_intf = true;
933 }
934 if (ttkp != NULL) {
935 ciKlass* k = ttkp->klass();
936 if (k->is_loaded() && k->is_interface())
937 is_intf = true;
938 }
939
940 // Default case: merge all inputs
941 const Type *t = Type::TOP; // Merged type starting value
942 for (uint i = 1; i < req(); ++i) {// For all paths in
943 // Reachable control path?
944 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
945 const Type* ti = phase->type(in(i));
946 // We assume that each input of an interface-valued Phi is a true
947 // subtype of that interface. This might not be true of the meet
948 // of all the input types. The lattice is not distributive in
949 // such cases. Ward off asserts in type.cpp by refusing to do
950 // meets between interfaces and proper classes.
951 const TypePtr* tip = ti->make_ptr();
952 const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL;
953 if (tiip) {
954 bool ti_is_intf = false;
955 ciKlass* k = tiip->klass();
956 if (k->is_loaded() && k->is_interface())
957 ti_is_intf = true;
958 if (is_intf != ti_is_intf)
959 { t = _type; break; }
960 }
961 t = t->meet_speculative(ti);
962 }
963 }
964
965 // The worst-case type (from ciTypeFlow) should be consistent with "t".
966 // That is, we expect that "t->higher_equal(_type)" holds true.
967 // There are various exceptions:
968 // - Inputs which are phis might in fact be widened unnecessarily.
969 // For example, an input might be a widened int while the phi is a short.
970 // - Inputs might be BotPtrs but this phi is dependent on a null check,
971 // and postCCP has removed the cast which encodes the result of the check.
972 // - The type of this phi is an interface, and the inputs are classes.
973 // - Value calls on inputs might produce fuzzy results.
974 // (Occurrences of this case suggest improvements to Value methods.)
975 //
976 // It is not possible to see Type::BOTTOM values as phi inputs,
977 // because the ciTypeFlow pre-pass produces verifier-quality types.
978 const Type* ft = t->filter_speculative(_type); // Worst case type
979
980 #ifdef ASSERT
981 // The following logic has been moved into TypeOopPtr::filter.
982 const Type* jt = t->join_speculative(_type);
983 if (jt->empty()) { // Emptied out???
984
985 // Check for evil case of 't' being a class and '_type' expecting an
986 // interface. This can happen because the bytecodes do not contain
987 // enough type info to distinguish a Java-level interface variable
988 // from a Java-level object variable. If we meet 2 classes which
989 // both implement interface I, but their meet is at 'j/l/O' which
990 // doesn't implement I, we have no way to tell if the result should
991 // be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows
992 // into a Phi which "knows" it's an Interface type we'll have to
993 // uplift the type.
994 if (!t->empty() && ttip && ttip->is_loaded() && ttip->klass()->is_interface()) {
995 assert(ft == _type, ""); // Uplift to interface
996 } else if (!t->empty() && ttkp && ttkp->is_loaded() && ttkp->klass()->is_interface()) {
997 assert(ft == _type, ""); // Uplift to interface
998 } else {
999 // We also have to handle 'evil cases' of interface- vs. class-arrays
1000 Type::get_arrays_base_elements(jt, _type, NULL, &ttip);
1001 if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
1002 assert(ft == _type, ""); // Uplift to array of interface
1003 } else {
1004 // Otherwise it's something stupid like non-overlapping int ranges
1005 // found on dying counted loops.
1006 assert(ft == Type::TOP, ""); // Canonical empty value
1007 }
1008 }
1009 }
1010
1011 else {
1012
1013 // If we have an interface-typed Phi and we narrow to a class type, the join
1014 // should report back the class. However, if we have a J/L/Object
1015 // class-typed Phi and an interface flows in, it's possible that the meet &
1016 // join report an interface back out. This isn't possible but happens
1017 // because the type system doesn't interact well with interfaces.
1018 const TypePtr *jtp = jt->make_ptr();
1019 const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL;
1020 const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_klassptr() : NULL;
1021 if( jtip && ttip ) {
1022 if( jtip->is_loaded() && jtip->klass()->is_interface() &&
1023 ttip->is_loaded() && !ttip->klass()->is_interface() ) {
1024 // Happens in a CTW of rt.jar, 320-341, no extra flags
1025 assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) ||
1026 ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), "");
1027 jt = ft;
1028 }
1029 }
1030 if( jtkp && ttkp ) {
1031 if( jtkp->is_loaded() && jtkp->klass()->is_interface() &&
1032 !jtkp->klass_is_exact() && // Keep exact interface klass (6894807)
1033 ttkp->is_loaded() && !ttkp->klass()->is_interface() ) {
1034 assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) ||
1035 ft->isa_narrowklass() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), "");
1036 jt = ft;
1037 }
1038 }
1039 if (jt != ft && jt->base() == ft->base()) {
1040 if (jt->isa_int() &&
1041 jt->is_int()->_lo == ft->is_int()->_lo &&
1042 jt->is_int()->_hi == ft->is_int()->_hi)
1043 jt = ft;
1044 if (jt->isa_long() &&
1045 jt->is_long()->_lo == ft->is_long()->_lo &&
1046 jt->is_long()->_hi == ft->is_long()->_hi)
1047 jt = ft;
1048 }
1049 if (jt != ft) {
1050 tty->print("merge type: "); t->dump(); tty->cr();
1051 tty->print("kill type: "); _type->dump(); tty->cr();
1052 tty->print("join type: "); jt->dump(); tty->cr();
1053 tty->print("filter type: "); ft->dump(); tty->cr();
1054 }
1055 assert(jt == ft, "");
1056 }
1057 #endif //ASSERT
1058
1059 // Deal with conversion problems found in data loops.
1060 ft = phase->saturate(ft, phase->type_or_null(this), _type);
1061
1062 return ft;
1063 }
1064
1065
1066 //------------------------------is_diamond_phi---------------------------------
1067 // Does this Phi represent a simple well-shaped diamond merge? Return the
1068 // index of the true path or 0 otherwise.
1069 // If check_control_only is true, do not inspect the If node at the
1070 // top, and return -1 (not an edge number) on success.
1071 int PhiNode::is_diamond_phi(bool check_control_only) const {
1072 // Check for a 2-path merge
1073 Node *region = in(0);
1074 if( !region ) return 0;
1075 if( region->req() != 3 ) return 0;
1076 if( req() != 3 ) return 0;
1077 // Check that both paths come from the same If
1078 Node *ifp1 = region->in(1);
1079 Node *ifp2 = region->in(2);
1080 if( !ifp1 || !ifp2 ) return 0;
1081 Node *iff = ifp1->in(0);
1082 if( !iff || !iff->is_If() ) return 0;
1083 if( iff != ifp2->in(0) ) return 0;
1084 if (check_control_only) return -1;
1085 // Check for a proper bool/cmp
1086 const Node *b = iff->in(1);
1087 if( !b->is_Bool() ) return 0;
1088 const Node *cmp = b->in(1);
1089 if( !cmp->is_Cmp() ) return 0;
1090
1091 // Check for branching opposite expected
1092 if( ifp2->Opcode() == Op_IfTrue ) {
1093 assert( ifp1->Opcode() == Op_IfFalse, "" );
1094 return 2;
1095 } else {
1096 assert( ifp1->Opcode() == Op_IfTrue, "" );
1097 return 1;
1098 }
1099 }
1100
1101 //----------------------------check_cmove_id-----------------------------------
1102 // Check for CMove'ing a constant after comparing against the constant.
1103 // Happens all the time now, since if we compare equality vs a constant in
1104 // the parser, we "know" the variable is constant on one path and we force
1105 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
1106 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more
1107 // general in that we don't need constants. Since CMove's are only inserted
1108 // in very special circumstances, we do it here on generic Phi's.
1109 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
1110 assert(true_path !=0, "only diamond shape graph expected");
1111
1112 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1113 // phi->region->if_proj->ifnode->bool->cmp
1114 Node* region = in(0);
1115 Node* iff = region->in(1)->in(0);
1116 BoolNode* b = iff->in(1)->as_Bool();
1117 Node* cmp = b->in(1);
1118 Node* tval = in(true_path);
1119 Node* fval = in(3-true_path);
1120 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
1121 if (id == NULL)
1122 return NULL;
1123
1124 // Either value might be a cast that depends on a branch of 'iff'.
1125 // Since the 'id' value will float free of the diamond, either
1126 // decast or return failure.
1127 Node* ctl = id->in(0);
1128 if (ctl != NULL && ctl->in(0) == iff) {
1129 if (id->is_ConstraintCast()) {
1130 return id->in(1);
1131 } else {
1132 // Don't know how to disentangle this value.
1133 return NULL;
1134 }
1135 }
1136
1137 return id;
1138 }
1139
1140 //------------------------------Identity---------------------------------------
1141 // Check for Region being Identity.
1142 Node *PhiNode::Identity( PhaseTransform *phase ) {
1143 // Check for no merging going on
1144 // (There used to be special-case code here when this->region->is_Loop.
1145 // It would check for a tributary phi on the backedge that the main phi
1146 // trivially, perhaps with a single cast. The unique_input method
1147 // does all this and more, by reducing such tributaries to 'this'.)
1148 Node* uin = unique_input(phase);
1149 if (uin != NULL) {
1150 return uin;
1151 }
1152
1153 int true_path = is_diamond_phi();
1154 if (true_path != 0) {
1155 Node* id = is_cmove_id(phase, true_path);
1156 if (id != NULL) return id;
1157 }
1158
1159 return this; // No identity
1160 }
1161
1162 //-----------------------------unique_input------------------------------------
1163 // Find the unique value, discounting top, self-loops, and casts.
1164 // Return top if there are no inputs, and self if there are multiple.
1165 Node* PhiNode::unique_input(PhaseTransform* phase) {
1166 // 1) One unique direct input, or
1167 // 2) some of the inputs have an intervening ConstraintCast and
1168 // the type of input is the same or sharper (more specific)
1169 // than the phi's type.
1170 // 3) an input is a self loop
1171 //
1172 // 1) input or 2) input or 3) input __
1173 // / \ / \ \ / \
1174 // \ / | cast phi cast
1175 // phi \ / / \ /
1176 // phi / --
1177
1178 Node* r = in(0); // RegionNode
1179 if (r == NULL) return in(1); // Already degraded to a Copy
1180 Node* uncasted_input = NULL; // The unique uncasted input (ConstraintCasts removed)
1181 Node* direct_input = NULL; // The unique direct input
1182
1183 for (uint i = 1, cnt = req(); i < cnt; ++i) {
1184 Node* rc = r->in(i);
1185 if (rc == NULL || phase->type(rc) == Type::TOP)
1186 continue; // ignore unreachable control path
1187 Node* n = in(i);
1188 if (n == NULL)
1189 continue;
1190 Node* un = n->uncast();
1191 if (un == NULL || un == this || phase->type(un) == Type::TOP) {
1192 continue; // ignore if top, or in(i) and "this" are in a data cycle
1193 }
1194 // Check for a unique uncasted input
1195 if (uncasted_input == NULL) {
1196 uncasted_input = un;
1197 } else if (uncasted_input != un) {
1198 uncasted_input = NodeSentinel; // no unique uncasted input
1199 }
1200 // Check for a unique direct input
1201 if (direct_input == NULL) {
1202 direct_input = n;
1203 } else if (direct_input != n) {
1204 direct_input = NodeSentinel; // no unique direct input
1205 }
1206 }
1207 if (direct_input == NULL) {
1208 return phase->C->top(); // no inputs
1209 }
1210 assert(uncasted_input != NULL,"");
1211
1212 if (direct_input != NodeSentinel) {
1213 return direct_input; // one unique direct input
1214 }
1215 if (uncasted_input != NodeSentinel &&
1216 phase->type(uncasted_input)->higher_equal(type())) {
1217 return uncasted_input; // one unique uncasted input
1218 }
1219
1220 // Nothing.
1221 return NULL;
1222 }
1223
1224 //------------------------------is_x2logic-------------------------------------
1225 // Check for simple convert-to-boolean pattern
1226 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
1227 // Convert Phi to an ConvIB.
1228 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
1229 assert(true_path !=0, "only diamond shape graph expected");
1230 // Convert the true/false index into an expected 0/1 return.
1231 // Map 2->0 and 1->1.
1232 int flipped = 2-true_path;
1233
1234 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1235 // phi->region->if_proj->ifnode->bool->cmp
1236 Node *region = phi->in(0);
1237 Node *iff = region->in(1)->in(0);
1238 BoolNode *b = (BoolNode*)iff->in(1);
1239 const CmpNode *cmp = (CmpNode*)b->in(1);
1240
1241 Node *zero = phi->in(1);
1242 Node *one = phi->in(2);
1243 const Type *tzero = phase->type( zero );
1244 const Type *tone = phase->type( one );
1245
1246 // Check for compare vs 0
1247 const Type *tcmp = phase->type(cmp->in(2));
1248 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
1249 // Allow cmp-vs-1 if the other input is bounded by 0-1
1250 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
1251 return NULL;
1252 flipped = 1-flipped; // Test is vs 1 instead of 0!
1253 }
1254
1255 // Check for setting zero/one opposite expected
1256 if( tzero == TypeInt::ZERO ) {
1257 if( tone == TypeInt::ONE ) {
1258 } else return NULL;
1259 } else if( tzero == TypeInt::ONE ) {
1260 if( tone == TypeInt::ZERO ) {
1261 flipped = 1-flipped;
1262 } else return NULL;
1263 } else return NULL;
1264
1265 // Check for boolean test backwards
1266 if( b->_test._test == BoolTest::ne ) {
1267 } else if( b->_test._test == BoolTest::eq ) {
1268 flipped = 1-flipped;
1269 } else return NULL;
1270
1271 // Build int->bool conversion
1272 Node *n = new (phase->C) Conv2BNode( cmp->in(1) );
1273 if( flipped )
1274 n = new (phase->C) XorINode( phase->transform(n), phase->intcon(1) );
1275
1276 return n;
1277 }
1278
1279 //------------------------------is_cond_add------------------------------------
1280 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;"
1281 // To be profitable the control flow has to disappear; there can be no other
1282 // values merging here. We replace the test-and-branch with:
1283 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by
1284 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
1285 // Then convert Y to 0-or-Y and finally add.
1286 // This is a key transform for SpecJava _201_compress.
1287 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
1288 assert(true_path !=0, "only diamond shape graph expected");
1289
1290 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1291 // phi->region->if_proj->ifnode->bool->cmp
1292 RegionNode *region = (RegionNode*)phi->in(0);
1293 Node *iff = region->in(1)->in(0);
1294 BoolNode* b = iff->in(1)->as_Bool();
1295 const CmpNode *cmp = (CmpNode*)b->in(1);
1296
1297 // Make sure only merging this one phi here
1298 if (region->has_unique_phi() != phi) return NULL;
1299
1300 // Make sure each arm of the diamond has exactly one output, which we assume
1301 // is the region. Otherwise, the control flow won't disappear.
1302 if (region->in(1)->outcnt() != 1) return NULL;
1303 if (region->in(2)->outcnt() != 1) return NULL;
1304
1305 // Check for "(P < Q)" of type signed int
1306 if (b->_test._test != BoolTest::lt) return NULL;
1307 if (cmp->Opcode() != Op_CmpI) return NULL;
1308
1309 Node *p = cmp->in(1);
1310 Node *q = cmp->in(2);
1311 Node *n1 = phi->in( true_path);
1312 Node *n2 = phi->in(3-true_path);
1313
1314 int op = n1->Opcode();
1315 if( op != Op_AddI // Need zero as additive identity
1316 /*&&op != Op_SubI &&
1317 op != Op_AddP &&
1318 op != Op_XorI &&
1319 op != Op_OrI*/ )
1320 return NULL;
1321
1322 Node *x = n2;
1323 Node *y = NULL;
1324 if( x == n1->in(1) ) {
1325 y = n1->in(2);
1326 } else if( x == n1->in(2) ) {
1327 y = n1->in(1);
1328 } else return NULL;
1329
1330 // Not so profitable if compare and add are constants
1331 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
1332 return NULL;
1333
1334 Node *cmplt = phase->transform( new (phase->C) CmpLTMaskNode(p,q) );
1335 Node *j_and = phase->transform( new (phase->C) AndINode(cmplt,y) );
1336 return new (phase->C) AddINode(j_and,x);
1337 }
1338
1339 //------------------------------is_absolute------------------------------------
1340 // Check for absolute value.
1341 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
1342 assert(true_path !=0, "only diamond shape graph expected");
1343
1344 int cmp_zero_idx = 0; // Index of compare input where to look for zero
1345 int phi_x_idx = 0; // Index of phi input where to find naked x
1346
1347 // ABS ends with the merge of 2 control flow paths.
1348 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
1349 int false_path = 3 - true_path;
1350
1351 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1352 // phi->region->if_proj->ifnode->bool->cmp
1353 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
1354
1355 // Check bool sense
1356 switch( bol->_test._test ) {
1357 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break;
1358 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1359 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1360 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
1361 default: return NULL; break;
1362 }
1363
1364 // Test is next
1365 Node *cmp = bol->in(1);
1366 const Type *tzero = NULL;
1367 switch( cmp->Opcode() ) {
1368 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS
1369 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS
1370 default: return NULL;
1371 }
1372
1373 // Find zero input of compare; the other input is being abs'd
1374 Node *x = NULL;
1375 bool flip = false;
1376 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
1377 x = cmp->in(3 - cmp_zero_idx);
1378 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
1379 // The test is inverted, we should invert the result...
1380 x = cmp->in(cmp_zero_idx);
1381 flip = true;
1382 } else {
1383 return NULL;
1384 }
1385
1386 // Next get the 2 pieces being selected, one is the original value
1387 // and the other is the negated value.
1388 if( phi_root->in(phi_x_idx) != x ) return NULL;
1389
1390 // Check other phi input for subtract node
1391 Node *sub = phi_root->in(3 - phi_x_idx);
1392
1393 // Allow only Sub(0,X) and fail out for all others; Neg is not OK
1394 if( tzero == TypeF::ZERO ) {
1395 if( sub->Opcode() != Op_SubF ||
1396 sub->in(2) != x ||
1397 phase->type(sub->in(1)) != tzero ) return NULL;
1398 x = new (phase->C) AbsFNode(x);
1399 if (flip) {
1400 x = new (phase->C) SubFNode(sub->in(1), phase->transform(x));
1401 }
1402 } else {
1403 if( sub->Opcode() != Op_SubD ||
1404 sub->in(2) != x ||
1405 phase->type(sub->in(1)) != tzero ) return NULL;
1406 x = new (phase->C) AbsDNode(x);
1407 if (flip) {
1408 x = new (phase->C) SubDNode(sub->in(1), phase->transform(x));
1409 }
1410 }
1411
1412 return x;
1413 }
1414
1415 //------------------------------split_once-------------------------------------
1416 // Helper for split_flow_path
1417 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
1418 igvn->hash_delete(n); // Remove from hash before hacking edges
1419
1420 uint j = 1;
1421 for (uint i = phi->req()-1; i > 0; i--) {
1422 if (phi->in(i) == val) { // Found a path with val?
1423 // Add to NEW Region/Phi, no DU info
1424 newn->set_req( j++, n->in(i) );
1425 // Remove from OLD Region/Phi
1426 n->del_req(i);
1427 }
1428 }
1429
1430 // Register the new node but do not transform it. Cannot transform until the
1431 // entire Region/Phi conglomerate has been hacked as a single huge transform.
1432 igvn->register_new_node_with_optimizer( newn );
1433
1434 // Now I can point to the new node.
1435 n->add_req(newn);
1436 igvn->_worklist.push(n);
1437 }
1438
1439 //------------------------------split_flow_path--------------------------------
1440 // Check for merging identical values and split flow paths
1441 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) {
1442 BasicType bt = phi->type()->basic_type();
1443 if( bt == T_ILLEGAL || type2size[bt] <= 0 )
1444 return NULL; // Bail out on funny non-value stuff
1445 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a
1446 return NULL; // third unequal input to be worth doing
1447
1448 // Scan for a constant
1449 uint i;
1450 for( i = 1; i < phi->req()-1; i++ ) {
1451 Node *n = phi->in(i);
1452 if( !n ) return NULL;
1453 if( phase->type(n) == Type::TOP ) return NULL;
1454 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN || n->Opcode() == Op_ConNKlass )
1455 break;
1456 }
1457 if( i >= phi->req() ) // Only split for constants
1458 return NULL;
1459
1460 Node *val = phi->in(i); // Constant to split for
1461 uint hit = 0; // Number of times it occurs
1462 Node *r = phi->region();
1463
1464 for( ; i < phi->req(); i++ ){ // Count occurrences of constant
1465 Node *n = phi->in(i);
1466 if( !n ) return NULL;
1467 if( phase->type(n) == Type::TOP ) return NULL;
1468 if( phi->in(i) == val ) {
1469 hit++;
1470 if (PhaseIdealLoop::find_predicate(r->in(i)) != NULL) {
1471 return NULL; // don't split loop entry path
1472 }
1473 }
1474 }
1475
1476 if( hit <= 1 || // Make sure we find 2 or more
1477 hit == phi->req()-1 ) // and not ALL the same value
1478 return NULL;
1479
1480 // Now start splitting out the flow paths that merge the same value.
1481 // Split first the RegionNode.
1482 PhaseIterGVN *igvn = phase->is_IterGVN();
1483 RegionNode *newr = new (phase->C) RegionNode(hit+1);
1484 split_once(igvn, phi, val, r, newr);
1485
1486 // Now split all other Phis than this one
1487 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) {
1488 Node* phi2 = r->fast_out(k);
1489 if( phi2->is_Phi() && phi2->as_Phi() != phi ) {
1490 PhiNode *newphi = PhiNode::make_blank(newr, phi2);
1491 split_once(igvn, phi, val, phi2, newphi);
1492 }
1493 }
1494
1495 // Clean up this guy
1496 igvn->hash_delete(phi);
1497 for( i = phi->req()-1; i > 0; i-- ) {
1498 if( phi->in(i) == val ) {
1499 phi->del_req(i);
1500 }
1501 }
1502 phi->add_req(val);
1503
1504 return phi;
1505 }
1506
1507 //=============================================================================
1508 //------------------------------simple_data_loop_check-------------------------
1509 // Try to determining if the phi node in a simple safe/unsafe data loop.
1510 // Returns:
1511 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
1512 // Safe - safe case when the phi and it's inputs reference only safe data
1513 // nodes;
1514 // Unsafe - the phi and it's inputs reference unsafe data nodes but there
1515 // is no reference back to the phi - need a graph walk
1516 // to determine if it is in a loop;
1517 // UnsafeLoop - unsafe case when the phi references itself directly or through
1518 // unsafe data node.
1519 // Note: a safe data node is a node which could/never reference itself during
1520 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP.
1521 // I mark Phi nodes as safe node not only because they can reference itself
1522 // but also to prevent mistaking the fallthrough case inside an outer loop
1523 // as dead loop when the phi references itselfs through an other phi.
1524 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const {
1525 // It is unsafe loop if the phi node references itself directly.
1526 if (in == (Node*)this)
1527 return UnsafeLoop; // Unsafe loop
1528 // Unsafe loop if the phi node references itself through an unsafe data node.
1529 // Exclude cases with null inputs or data nodes which could reference
1530 // itself (safe for dead loops).
1531 if (in != NULL && !in->is_dead_loop_safe()) {
1532 // Check inputs of phi's inputs also.
1533 // It is much less expensive then full graph walk.
1534 uint cnt = in->req();
1535 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1;
1536 for (; i < cnt; ++i) {
1537 Node* m = in->in(i);
1538 if (m == (Node*)this)
1539 return UnsafeLoop; // Unsafe loop
1540 if (m != NULL && !m->is_dead_loop_safe()) {
1541 // Check the most common case (about 30% of all cases):
1542 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con).
1543 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL;
1544 if (m1 == (Node*)this)
1545 return UnsafeLoop; // Unsafe loop
1546 if (m1 != NULL && m1 == m->in(2) &&
1547 m1->is_dead_loop_safe() && m->in(3)->is_Con()) {
1548 continue; // Safe case
1549 }
1550 // The phi references an unsafe node - need full analysis.
1551 return Unsafe;
1552 }
1553 }
1554 }
1555 return Safe; // Safe case - we can optimize the phi node.
1556 }
1557
1558 //------------------------------is_unsafe_data_reference-----------------------
1559 // If phi can be reached through the data input - it is data loop.
1560 bool PhiNode::is_unsafe_data_reference(Node *in) const {
1561 assert(req() > 1, "");
1562 // First, check simple cases when phi references itself directly or
1563 // through an other node.
1564 LoopSafety safety = simple_data_loop_check(in);
1565 if (safety == UnsafeLoop)
1566 return true; // phi references itself - unsafe loop
1567 else if (safety == Safe)
1568 return false; // Safe case - phi could be replaced with the unique input.
1569
1570 // Unsafe case when we should go through data graph to determine
1571 // if the phi references itself.
1572
1573 ResourceMark rm;
1574
1575 Arena *a = Thread::current()->resource_area();
1576 Node_List nstack(a);
1577 VectorSet visited(a);
1578
1579 nstack.push(in); // Start with unique input.
1580 visited.set(in->_idx);
1581 while (nstack.size() != 0) {
1582 Node* n = nstack.pop();
1583 uint cnt = n->req();
1584 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1;
1585 for (; i < cnt; i++) {
1586 Node* m = n->in(i);
1587 if (m == (Node*)this) {
1588 return true; // Data loop
1589 }
1590 if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases.
1591 if (!visited.test_set(m->_idx))
1592 nstack.push(m);
1593 }
1594 }
1595 }
1596 return false; // The phi is not reachable from its inputs
1597 }
1598
1599
1600 //------------------------------Ideal------------------------------------------
1601 // Return a node which is more "ideal" than the current node. Must preserve
1602 // the CFG, but we can still strip out dead paths.
1603 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1604 // The next should never happen after 6297035 fix.
1605 if( is_copy() ) // Already degraded to a Copy ?
1606 return NULL; // No change
1607
1608 Node *r = in(0); // RegionNode
1609 assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge");
1610
1611 // Note: During parsing, phis are often transformed before their regions.
1612 // This means we have to use type_or_null to defend against untyped regions.
1613 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1614 return NULL; // No change
1615
1616 Node *top = phase->C->top();
1617 bool new_phi = (outcnt() == 0); // transforming new Phi
1618 // No change for igvn if new phi is not hooked
1619 if (new_phi && can_reshape)
1620 return NULL;
1621
1622 // The are 2 situations when only one valid phi's input is left
1623 // (in addition to Region input).
1624 // One: region is not loop - replace phi with this input.
1625 // Two: region is loop - replace phi with top since this data path is dead
1626 // and we need to break the dead data loop.
1627 Node* progress = NULL; // Record if any progress made
1628 for( uint j = 1; j < req(); ++j ){ // For all paths in
1629 // Check unreachable control paths
1630 Node* rc = r->in(j);
1631 Node* n = in(j); // Get the input
1632 if (rc == NULL || phase->type(rc) == Type::TOP) {
1633 if (n != top) { // Not already top?
1634 PhaseIterGVN *igvn = phase->is_IterGVN();
1635 if (can_reshape && igvn != NULL) {
1636 igvn->_worklist.push(r);
1637 }
1638 // Nuke it down
1639 if (can_reshape) {
1640 set_req_X(j, top, igvn);
1641 } else {
1642 set_req(j, top);
1643 }
1644 progress = this; // Record progress
1645 }
1646 }
1647 }
1648
1649 if (can_reshape && outcnt() == 0) {
1650 // set_req() above may kill outputs if Phi is referenced
1651 // only by itself on the dead (top) control path.
1652 return top;
1653 }
1654
1655 Node* uin = unique_input(phase);
1656 if (uin == top) { // Simplest case: no alive inputs.
1657 if (can_reshape) // IGVN transformation
1658 return top;
1659 else
1660 return NULL; // Identity will return TOP
1661 } else if (uin != NULL) {
1662 // Only one not-NULL unique input path is left.
1663 // Determine if this input is backedge of a loop.
1664 // (Skip new phis which have no uses and dead regions).
1665 if (outcnt() > 0 && r->in(0) != NULL) {
1666 // First, take the short cut when we know it is a loop and
1667 // the EntryControl data path is dead.
1668 // Loop node may have only one input because entry path
1669 // is removed in PhaseIdealLoop::Dominators().
1670 assert(!r->is_Loop() || r->req() <= 3, "Loop node should have 3 or less inputs");
1671 bool is_loop = (r->is_Loop() && r->req() == 3);
1672 // Then, check if there is a data loop when phi references itself directly
1673 // or through other data nodes.
1674 if (is_loop && !uin->eqv_uncast(in(LoopNode::EntryControl)) ||
1675 !is_loop && is_unsafe_data_reference(uin)) {
1676 // Break this data loop to avoid creation of a dead loop.
1677 if (can_reshape) {
1678 return top;
1679 } else {
1680 // We can't return top if we are in Parse phase - cut inputs only
1681 // let Identity to handle the case.
1682 replace_edge(uin, top);
1683 return NULL;
1684 }
1685 }
1686 }
1687
1688 // One unique input.
1689 debug_only(Node* ident = Identity(phase));
1690 // The unique input must eventually be detected by the Identity call.
1691 #ifdef ASSERT
1692 if (ident != uin && !ident->is_top()) {
1693 // print this output before failing assert
1694 r->dump(3);
1695 this->dump(3);
1696 ident->dump();
1697 uin->dump();
1698 }
1699 #endif
1700 assert(ident == uin || ident->is_top(), "Identity must clean this up");
1701 return NULL;
1702 }
1703
1704
1705 Node* opt = NULL;
1706 int true_path = is_diamond_phi();
1707 if( true_path != 0 ) {
1708 // Check for CMove'ing identity. If it would be unsafe,
1709 // handle it here. In the safe case, let Identity handle it.
1710 Node* unsafe_id = is_cmove_id(phase, true_path);
1711 if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) )
1712 opt = unsafe_id;
1713
1714 // Check for simple convert-to-boolean pattern
1715 if( opt == NULL )
1716 opt = is_x2logic(phase, this, true_path);
1717
1718 // Check for absolute value
1719 if( opt == NULL )
1720 opt = is_absolute(phase, this, true_path);
1721
1722 // Check for conditional add
1723 if( opt == NULL && can_reshape )
1724 opt = is_cond_add(phase, this, true_path);
1725
1726 // These 4 optimizations could subsume the phi:
1727 // have to check for a dead data loop creation.
1728 if( opt != NULL ) {
1729 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) {
1730 // Found dead loop.
1731 if( can_reshape )
1732 return top;
1733 // We can't return top if we are in Parse phase - cut inputs only
1734 // to stop further optimizations for this phi. Identity will return TOP.
1735 assert(req() == 3, "only diamond merge phi here");
1736 set_req(1, top);
1737 set_req(2, top);
1738 return NULL;
1739 } else {
1740 return opt;
1741 }
1742 }
1743 }
1744
1745 // Check for merging identical values and split flow paths
1746 if (can_reshape) {
1747 opt = split_flow_path(phase, this);
1748 // This optimization only modifies phi - don't need to check for dead loop.
1749 assert(opt == NULL || phase->eqv(opt, this), "do not elide phi");
1750 if (opt != NULL) return opt;
1751 }
1752
1753 if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) {
1754 // Try to undo Phi of AddP:
1755 // (Phi (AddP base base y) (AddP base2 base2 y))
1756 // becomes:
1757 // newbase := (Phi base base2)
1758 // (AddP newbase newbase y)
1759 //
1760 // This occurs as a result of unsuccessful split_thru_phi and
1761 // interferes with taking advantage of addressing modes. See the
1762 // clone_shift_expressions code in matcher.cpp
1763 Node* addp = in(1);
1764 const Type* type = addp->in(AddPNode::Base)->bottom_type();
1765 Node* y = addp->in(AddPNode::Offset);
1766 if (y != NULL && addp->in(AddPNode::Base) == addp->in(AddPNode::Address)) {
1767 // make sure that all the inputs are similar to the first one,
1768 // i.e. AddP with base == address and same offset as first AddP
1769 bool doit = true;
1770 for (uint i = 2; i < req(); i++) {
1771 if (in(i) == NULL ||
1772 in(i)->Opcode() != Op_AddP ||
1773 in(i)->in(AddPNode::Base) != in(i)->in(AddPNode::Address) ||
1774 in(i)->in(AddPNode::Offset) != y) {
1775 doit = false;
1776 break;
1777 }
1778 // Accumulate type for resulting Phi
1779 type = type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type());
1780 }
1781 Node* base = NULL;
1782 if (doit) {
1783 // Check for neighboring AddP nodes in a tree.
1784 // If they have a base, use that it.
1785 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) {
1786 Node* u = this->fast_out(k);
1787 if (u->is_AddP()) {
1788 Node* base2 = u->in(AddPNode::Base);
1789 if (base2 != NULL && !base2->is_top()) {
1790 if (base == NULL)
1791 base = base2;
1792 else if (base != base2)
1793 { doit = false; break; }
1794 }
1795 }
1796 }
1797 }
1798 if (doit) {
1799 if (base == NULL) {
1800 base = new (phase->C) PhiNode(in(0), type, NULL);
1801 for (uint i = 1; i < req(); i++) {
1802 base->init_req(i, in(i)->in(AddPNode::Base));
1803 }
1804 phase->is_IterGVN()->register_new_node_with_optimizer(base);
1805 }
1806 return new (phase->C) AddPNode(base, base, y);
1807 }
1808 }
1809 }
1810
1811 // Split phis through memory merges, so that the memory merges will go away.
1812 // Piggy-back this transformation on the search for a unique input....
1813 // It will be as if the merged memory is the unique value of the phi.
1814 // (Do not attempt this optimization unless parsing is complete.
1815 // It would make the parser's memory-merge logic sick.)
1816 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.)
1817 if (progress == NULL && can_reshape && type() == Type::MEMORY) {
1818 // see if this phi should be sliced
1819 uint merge_width = 0;
1820 bool saw_self = false;
1821 for( uint i=1; i<req(); ++i ) {// For all paths in
1822 Node *ii = in(i);
1823 if (ii->is_MergeMem()) {
1824 MergeMemNode* n = ii->as_MergeMem();
1825 merge_width = MAX2(merge_width, n->req());
1826 saw_self = saw_self || phase->eqv(n->base_memory(), this);
1827 }
1828 }
1829
1830 // This restriction is temporarily necessary to ensure termination:
1831 if (!saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0;
1832
1833 if (merge_width > Compile::AliasIdxRaw) {
1834 // found at least one non-empty MergeMem
1835 const TypePtr* at = adr_type();
1836 if (at != TypePtr::BOTTOM) {
1837 // Patch the existing phi to select an input from the merge:
1838 // Phi:AT1(...MergeMem(m0, m1, m2)...) into
1839 // Phi:AT1(...m1...)
1840 int alias_idx = phase->C->get_alias_index(at);
1841 for (uint i=1; i<req(); ++i) {
1842 Node *ii = in(i);
1843 if (ii->is_MergeMem()) {
1844 MergeMemNode* n = ii->as_MergeMem();
1845 // compress paths and change unreachable cycles to TOP
1846 // If not, we can update the input infinitely along a MergeMem cycle
1847 // Equivalent code is in MemNode::Ideal_common
1848 Node *m = phase->transform(n);
1849 if (outcnt() == 0) { // Above transform() may kill us!
1850 return top;
1851 }
1852 // If transformed to a MergeMem, get the desired slice
1853 // Otherwise the returned node represents memory for every slice
1854 Node *new_mem = (m->is_MergeMem()) ?
1855 m->as_MergeMem()->memory_at(alias_idx) : m;
1856 // Update input if it is progress over what we have now
1857 if (new_mem != ii) {
1858 set_req(i, new_mem);
1859 progress = this;
1860 }
1861 }
1862 }
1863 } else {
1864 // We know that at least one MergeMem->base_memory() == this
1865 // (saw_self == true). If all other inputs also references this phi
1866 // (directly or through data nodes) - it is dead loop.
1867 bool saw_safe_input = false;
1868 for (uint j = 1; j < req(); ++j) {
1869 Node *n = in(j);
1870 if (n->is_MergeMem() && n->as_MergeMem()->base_memory() == this)
1871 continue; // skip known cases
1872 if (!is_unsafe_data_reference(n)) {
1873 saw_safe_input = true; // found safe input
1874 break;
1875 }
1876 }
1877 if (!saw_safe_input)
1878 return top; // all inputs reference back to this phi - dead loop
1879
1880 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into
1881 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...))
1882 PhaseIterGVN *igvn = phase->is_IterGVN();
1883 Node* hook = new (phase->C) Node(1);
1884 PhiNode* new_base = (PhiNode*) clone();
1885 // Must eagerly register phis, since they participate in loops.
1886 if (igvn) {
1887 igvn->register_new_node_with_optimizer(new_base);
1888 hook->add_req(new_base);
1889 }
1890 MergeMemNode* result = MergeMemNode::make(phase->C, new_base);
1891 for (uint i = 1; i < req(); ++i) {
1892 Node *ii = in(i);
1893 if (ii->is_MergeMem()) {
1894 MergeMemNode* n = ii->as_MergeMem();
1895 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) {
1896 // If we have not seen this slice yet, make a phi for it.
1897 bool made_new_phi = false;
1898 if (mms.is_empty()) {
1899 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C));
1900 made_new_phi = true;
1901 if (igvn) {
1902 igvn->register_new_node_with_optimizer(new_phi);
1903 hook->add_req(new_phi);
1904 }
1905 mms.set_memory(new_phi);
1906 }
1907 Node* phi = mms.memory();
1908 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice");
1909 phi->set_req(i, mms.memory2());
1910 }
1911 }
1912 }
1913 // Distribute all self-loops.
1914 { // (Extra braces to hide mms.)
1915 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
1916 Node* phi = mms.memory();
1917 for (uint i = 1; i < req(); ++i) {
1918 if (phi->in(i) == this) phi->set_req(i, phi);
1919 }
1920 }
1921 }
1922 // now transform the new nodes, and return the mergemem
1923 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
1924 Node* phi = mms.memory();
1925 mms.set_memory(phase->transform(phi));
1926 }
1927 if (igvn) { // Unhook.
1928 igvn->hash_delete(hook);
1929 for (uint i = 1; i < hook->req(); i++) {
1930 hook->set_req(i, NULL);
1931 }
1932 }
1933 // Replace self with the result.
1934 return result;
1935 }
1936 }
1937 //
1938 // Other optimizations on the memory chain
1939 //
1940 const TypePtr* at = adr_type();
1941 for( uint i=1; i<req(); ++i ) {// For all paths in
1942 Node *ii = in(i);
1943 Node *new_in = MemNode::optimize_memory_chain(ii, at, NULL, phase);
1944 if (ii != new_in ) {
1945 set_req(i, new_in);
1946 progress = this;
1947 }
1948 }
1949 }
1950
1951 #ifdef _LP64
1952 // Push DecodeN/DecodeNKlass down through phi.
1953 // The rest of phi graph will transform by split EncodeP node though phis up.
1954 if ((UseCompressedOops || UseCompressedClassPointers) && can_reshape && progress == NULL) {
1955 bool may_push = true;
1956 bool has_decodeN = false;
1957 bool is_decodeN = false;
1958 for (uint i=1; i<req(); ++i) {// For all paths in
1959 Node *ii = in(i);
1960 if (ii->is_DecodeNarrowPtr() && ii->bottom_type() == bottom_type()) {
1961 // Do optimization if a non dead path exist.
1962 if (ii->in(1)->bottom_type() != Type::TOP) {
1963 has_decodeN = true;
1964 is_decodeN = ii->is_DecodeN();
1965 }
1966 } else if (!ii->is_Phi()) {
1967 may_push = false;
1968 }
1969 }
1970
1971 if (has_decodeN && may_push) {
1972 PhaseIterGVN *igvn = phase->is_IterGVN();
1973 // Make narrow type for new phi.
1974 const Type* narrow_t;
1975 if (is_decodeN) {
1976 narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr());
1977 } else {
1978 narrow_t = TypeNarrowKlass::make(this->bottom_type()->is_ptr());
1979 }
1980 PhiNode* new_phi = new (phase->C) PhiNode(r, narrow_t);
1981 uint orig_cnt = req();
1982 for (uint i=1; i<req(); ++i) {// For all paths in
1983 Node *ii = in(i);
1984 Node* new_ii = NULL;
1985 if (ii->is_DecodeNarrowPtr()) {
1986 assert(ii->bottom_type() == bottom_type(), "sanity");
1987 new_ii = ii->in(1);
1988 } else {
1989 assert(ii->is_Phi(), "sanity");
1990 if (ii->as_Phi() == this) {
1991 new_ii = new_phi;
1992 } else {
1993 if (is_decodeN) {
1994 new_ii = new (phase->C) EncodePNode(ii, narrow_t);
1995 } else {
1996 new_ii = new (phase->C) EncodePKlassNode(ii, narrow_t);
1997 }
1998 igvn->register_new_node_with_optimizer(new_ii);
1999 }
2000 }
2001 new_phi->set_req(i, new_ii);
2002 }
2003 igvn->register_new_node_with_optimizer(new_phi, this);
2004 if (is_decodeN) {
2005 progress = new (phase->C) DecodeNNode(new_phi, bottom_type());
2006 } else {
2007 progress = new (phase->C) DecodeNKlassNode(new_phi, bottom_type());
2008 }
2009 }
2010 }
2011 #endif
2012
2013 return progress; // Return any progress
2014 }
2015
2016 //------------------------------is_tripcount-----------------------------------
2017 bool PhiNode::is_tripcount() const {
2018 return (in(0) != NULL && in(0)->is_CountedLoop() &&
2019 in(0)->as_CountedLoop()->phi() == this);
2020 }
2021
2022 //------------------------------out_RegMask------------------------------------
2023 const RegMask &PhiNode::in_RegMask(uint i) const {
2024 return i ? out_RegMask() : RegMask::Empty;
2025 }
2026
2027 const RegMask &PhiNode::out_RegMask() const {
2028 uint ideal_reg = _type->ideal_reg();
2029 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
2030 if( ideal_reg == 0 ) return RegMask::Empty;
2031 assert(ideal_reg != Op_RegFlags, "flags register is not spillable");
2032 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
2033 }
2034
2035 #ifndef PRODUCT
2036 void PhiNode::dump_spec(outputStream *st) const {
2037 TypeNode::dump_spec(st);
2038 if (is_tripcount()) {
2039 st->print(" #tripcount");
2040 }
2041 }
2042 #endif
2043
2044
2045 //=============================================================================
2046 const Type *GotoNode::Value( PhaseTransform *phase ) const {
2047 // If the input is reachable, then we are executed.
2048 // If the input is not reachable, then we are not executed.
2049 return phase->type(in(0));
2050 }
2051
2052 Node *GotoNode::Identity( PhaseTransform *phase ) {
2053 return in(0); // Simple copy of incoming control
2054 }
2055
2056 const RegMask &GotoNode::out_RegMask() const {
2057 return RegMask::Empty;
2058 }
2059
2060 //=============================================================================
2061 const RegMask &JumpNode::out_RegMask() const {
2062 return RegMask::Empty;
2063 }
2064
2065 //=============================================================================
2066 const RegMask &JProjNode::out_RegMask() const {
2067 return RegMask::Empty;
2068 }
2069
2070 //=============================================================================
2071 const RegMask &CProjNode::out_RegMask() const {
2072 return RegMask::Empty;
2073 }
2074
2075
2076
2077 //=============================================================================
2078
2079 uint PCTableNode::hash() const { return Node::hash() + _size; }
2080 uint PCTableNode::cmp( const Node &n ) const
2081 { return _size == ((PCTableNode&)n)._size; }
2082
2083 const Type *PCTableNode::bottom_type() const {
2084 const Type** f = TypeTuple::fields(_size);
2085 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2086 return TypeTuple::make(_size, f);
2087 }
2088
2089 //------------------------------Value------------------------------------------
2090 // Compute the type of the PCTableNode. If reachable it is a tuple of
2091 // Control, otherwise the table targets are not reachable
2092 const Type *PCTableNode::Value( PhaseTransform *phase ) const {
2093 if( phase->type(in(0)) == Type::CONTROL )
2094 return bottom_type();
2095 return Type::TOP; // All paths dead? Then so are we
2096 }
2097
2098 //------------------------------Ideal------------------------------------------
2099 // Return a node which is more "ideal" than the current node. Strip out
2100 // control copies
2101 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2102 return remove_dead_region(phase, can_reshape) ? this : NULL;
2103 }
2104
2105 //=============================================================================
2106 uint JumpProjNode::hash() const {
2107 return Node::hash() + _dest_bci;
2108 }
2109
2110 uint JumpProjNode::cmp( const Node &n ) const {
2111 return ProjNode::cmp(n) &&
2112 _dest_bci == ((JumpProjNode&)n)._dest_bci;
2113 }
2114
2115 #ifndef PRODUCT
2116 void JumpProjNode::dump_spec(outputStream *st) const {
2117 ProjNode::dump_spec(st);
2118 st->print("@bci %d ",_dest_bci);
2119 }
2120 #endif
2121
2122 //=============================================================================
2123 //------------------------------Value------------------------------------------
2124 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot
2125 // have the default "fall_through_index" path.
2126 const Type *CatchNode::Value( PhaseTransform *phase ) const {
2127 // Unreachable? Then so are all paths from here.
2128 if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
2129 // First assume all paths are reachable
2130 const Type** f = TypeTuple::fields(_size);
2131 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2132 // Identify cases that will always throw an exception
2133 // () rethrow call
2134 // () virtual or interface call with NULL receiver
2135 // () call is a check cast with incompatible arguments
2136 if( in(1)->is_Proj() ) {
2137 Node *i10 = in(1)->in(0);
2138 if( i10->is_Call() ) {
2139 CallNode *call = i10->as_Call();
2140 // Rethrows always throw exceptions, never return
2141 if (call->entry_point() == OptoRuntime::rethrow_stub()) {
2142 f[CatchProjNode::fall_through_index] = Type::TOP;
2143 } else if( call->req() > TypeFunc::Parms ) {
2144 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) );
2145 // Check for null receiver to virtual or interface calls
2146 if( call->is_CallDynamicJava() &&
2147 arg0->higher_equal(TypePtr::NULL_PTR) ) {
2148 f[CatchProjNode::fall_through_index] = Type::TOP;
2149 }
2150 } // End of if not a runtime stub
2151 } // End of if have call above me
2152 } // End of slot 1 is not a projection
2153 return TypeTuple::make(_size, f);
2154 }
2155
2156 //=============================================================================
2157 uint CatchProjNode::hash() const {
2158 return Node::hash() + _handler_bci;
2159 }
2160
2161
2162 uint CatchProjNode::cmp( const Node &n ) const {
2163 return ProjNode::cmp(n) &&
2164 _handler_bci == ((CatchProjNode&)n)._handler_bci;
2165 }
2166
2167
2168 //------------------------------Identity---------------------------------------
2169 // If only 1 target is possible, choose it if it is the main control
2170 Node *CatchProjNode::Identity( PhaseTransform *phase ) {
2171 // If my value is control and no other value is, then treat as ID
2172 const TypeTuple *t = phase->type(in(0))->is_tuple();
2173 if (t->field_at(_con) != Type::CONTROL) return this;
2174 // If we remove the last CatchProj and elide the Catch/CatchProj, then we
2175 // also remove any exception table entry. Thus we must know the call
2176 // feeding the Catch will not really throw an exception. This is ok for
2177 // the main fall-thru control (happens when we know a call can never throw
2178 // an exception) or for "rethrow", because a further optimization will
2179 // yank the rethrow (happens when we inline a function that can throw an
2180 // exception and the caller has no handler). Not legal, e.g., for passing
2181 // a NULL receiver to a v-call, or passing bad types to a slow-check-cast.
2182 // These cases MUST throw an exception via the runtime system, so the VM
2183 // will be looking for a table entry.
2184 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode
2185 CallNode *call;
2186 if (_con != TypeFunc::Control && // Bail out if not the main control.
2187 !(proj->is_Proj() && // AND NOT a rethrow
2188 proj->in(0)->is_Call() &&
2189 (call = proj->in(0)->as_Call()) &&
2190 call->entry_point() == OptoRuntime::rethrow_stub()))
2191 return this;
2192
2193 // Search for any other path being control
2194 for (uint i = 0; i < t->cnt(); i++) {
2195 if (i != _con && t->field_at(i) == Type::CONTROL)
2196 return this;
2197 }
2198 // Only my path is possible; I am identity on control to the jump
2199 return in(0)->in(0);
2200 }
2201
2202
2203 #ifndef PRODUCT
2204 void CatchProjNode::dump_spec(outputStream *st) const {
2205 ProjNode::dump_spec(st);
2206 st->print("@bci %d ",_handler_bci);
2207 }
2208 #endif
2209
2210 //=============================================================================
2211 //------------------------------Identity---------------------------------------
2212 // Check for CreateEx being Identity.
2213 Node *CreateExNode::Identity( PhaseTransform *phase ) {
2214 if( phase->type(in(1)) == Type::TOP ) return in(1);
2215 if( phase->type(in(0)) == Type::TOP ) return in(0);
2216 // We only come from CatchProj, unless the CatchProj goes away.
2217 // If the CatchProj is optimized away, then we just carry the
2218 // exception oop through.
2219 CallNode *call = in(1)->in(0)->as_Call();
2220
2221 return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) )
2222 ? this
2223 : call->in(TypeFunc::Parms);
2224 }
2225
2226 //=============================================================================
2227 //------------------------------Value------------------------------------------
2228 // Check for being unreachable.
2229 const Type *NeverBranchNode::Value( PhaseTransform *phase ) const {
2230 if (!in(0) || in(0)->is_top()) return Type::TOP;
2231 return bottom_type();
2232 }
2233
2234 //------------------------------Ideal------------------------------------------
2235 // Check for no longer being part of a loop
2236 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2237 if (can_reshape && !in(0)->is_Loop()) {
2238 // Dead code elimination can sometimes delete this projection so
2239 // if it's not there, there's nothing to do.
2240 Node* fallthru = proj_out(0);
2241 if (fallthru != NULL) {
2242 phase->is_IterGVN()->replace_node(fallthru, in(0));
2243 }
2244 return phase->C->top();
2245 }
2246 return NULL;
2247 }
2248
2249 #ifndef PRODUCT
2250 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const {
2251 st->print("%s", Name());
2252 }
2253 #endif